Execution and Evaluation of Kiln Performance Tests
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Transcript of Execution and Evaluation of Kiln Performance Tests
T R A N S L A T I O N
GERMAN ASSOCIATION OF
CEMENT WORKS (VDZ)
Tannenstrasse 2
4 Düsseldorf Germany
Execution and
Evaluation of Kiln
Performance Tests
PROCESS TECHNOLOGY
COMMITTEE
KILN PERFORMANCE
TESTS TASK FORCE
May 1992
Specification Vt 10
May 1992 Specification Vt 10 Page 2
TABLE OF CONTENTS
1. PRELIMINARY REMARKS...........................................................................7
2. DESCRIPTION OF THE CLINKER BURNING PROCESS ...........................8
2.1 Reactions of the kiln feed............................................................................................................... 8
2.2 Burning process............................................................................................................................ 10
3. EXECUTION OF KILN PERFORMANCE TESTS.......................................16
3.1 Mode of operation of the kiln system.......................................................................................... 16
3.2 Duration of the performance test................................................................................................ 16
3.3 Measuring methods...................................................................................................................... 17
3.3.1 Solid substances.................................................................................................................... 17 3.3.1.1 Sampling .......................................................................................................................... 17 3.3.1.2 Analysis ........................................................................................................................... 18 3.3.1.3 Mass flows ....................................................................................................................... 25
3.3.2 Gases..................................................................................................................................... 27 3.3.2.1 Sampling .......................................................................................................................... 27 3.3.2.2 Analysis ........................................................................................................................... 28 3.3.2.3 Volume flows................................................................................................................... 28
3.3.3 Liquids.................................................................................................................................. 30 3.3.3.1 Heating oil ....................................................................................................................... 30 3.3.3.2 Water................................................................................................................................ 30
3.3.4 Temperatures ........................................................................................................................ 31 3.3.5 Pressures ............................................................................................................................... 32 3.3.6 Strokes and rotational speeds................................................................................................ 32 3.3.7 Electricity consumption ........................................................................................................ 33 3.3.8 Ambient conditions............................................................................................................... 33 3.3.9 Ensuring the precision of the measurements and analyses ................................................... 34
4. EVALUATION OF KILN PERFORMANCE TESTS.....................................35
4.1 Balancing of the entire system..................................................................................................... 35
4.1.1 Solid substance mass flows .................................................................................................. 40 4.1.2 Gas volume flows ................................................................................................................. 42
May 1992 Specification Vt 10 Page 3
4.1.2.1 Dry gas............................................................................................................................. 42 4.1.2.1.1 Minimum air volume flow.......................................................................................... 42 4.1.2.1.2 Air proportionality factor............................................................................................ 45 4.1.2.1.3 Infiltrated air at the kiln hood ..................................................................................... 46 4.1.2.1.4 Secondary air .............................................................................................................. 47 4.1.2.1.5 Cooler intake air ......................................................................................................... 48 4.1.2.1.6 Raw gas ...................................................................................................................... 48 4.1.2.1.7 Gas downstream from the burning area ...................................................................... 50 4.1.2.1.8 Gas downstream from the rotary kiln (kiln inlet) ....................................................... 50
4.1.2.2 Water vapor...................................................................................................................... 51 4.1.2.2.1 Humidity in the air...................................................................................................... 51 4.1.2.2.2 Water from the kiln feed............................................................................................. 51 4.1.2.2.3 Water from the fuel..................................................................................................... 52 4.1.2.2.4 Injection water ............................................................................................................ 52
4.1.2.3 Moist gas.......................................................................................................................... 52 4.1.2.3.1 Air............................................................................................................................... 52 4.1.2.3.2 Raw gas ...................................................................................................................... 53
4.1.3 Liquid mass flows................................................................................................................. 53 4.1.4 Energy flows......................................................................................................................... 53
4.1.4.1 Energy input..................................................................................................................... 53 4.1.4.1.1 Fuel ............................................................................................................................. 53 4.1.4.1.2 Kiln feed ..................................................................................................................... 57 4.1.4.1.3 Air............................................................................................................................... 60 4.1.4.1.4 Injection water ............................................................................................................ 62 4.1.4.1.5 Mechanical performance ............................................................................................ 62
4.1.4.2 Energy output................................................................................................................... 62 4.1.4.2.1 Reaction enthalpy of the kiln feed .............................................................................. 62
4.1.4.2.1.1 C3S, C2S, C3A and C4AF in the clinker ............................................................... 64 4.1.4.2.1.2 CaCO3 and MgCO3 in the kiln feed and in the raw gas dust ............................... 65 4.1.4.2.1.3 CaCO3 and C2S in the bypass dust....................................................................... 66 4.1.4.2.1.4 Balance equations ................................................................................................ 66
4.1.4.2.2 Water evaporation....................................................................................................... 70 4.1.4.2.3 Waste gas losses ......................................................................................................... 70 4.1.4.2.4 Dust losses .................................................................................................................. 71 4.1.4.2.5 Incomplete combustion............................................................................................... 72 4.1.4.2.6 Clinker ........................................................................................................................ 72 4.1.4.2.7 Radiation and convection ........................................................................................... 74 4.1.4.2.8 Uncoupled heat ........................................................................................................... 78
4.1.4.3 Energy balance................................................................................................................. 79
4.2 Balancing of the partial systems.................................................................................................. 80
4.2.1 Clinker cooler ....................................................................................................................... 80 4.2.1.1 Solid substance mass flows.............................................................................................. 83 4.2.1.2 Gas volume flows ............................................................................................................ 84 4.2.1.3 Energy flows ........................................................................................................................... 84
4.2.1.3.1 Energy input ............................................................................................................... 84 4.2.1.3.1.1 Hot clinker ........................................................................................................... 84 4.2.1.3.1.2 Cooler intake air .................................................................................................. 85 4.2.1.3.1.3 Injection water ..................................................................................................... 85 4.2.1.3.1.4 Mechanical performance ..................................................................................... 85
May 1992 Specification Vt 10 Page 4
4.2.1.3.2 Energy output ............................................................................................................. 85 4.2.1.3.2.1 Clinker, clinker dust ............................................................................................ 85 4.2.1.3.2.2 Radiation and convection .................................................................................... 86 4.2.1.3.2.3 Uncoupled heat .................................................................................................... 86 4.2.1.3.2.4 Cooler vent air, secondary air, tertiary air ........................................................... 86 4.2.1.3.2.5 Water evaporation................................................................................................ 86
4.2.1.3.3 Energy balance ........................................................................................................... 86 4.2.1.4 Evaluation quantities........................................................................................................ 87
4.2.1.4.1 Pre-cooling zone ......................................................................................................... 87 4.2.1.4.2 Energy loss flow of the cooling area .......................................................................... 89 4.2.1.4.3 Cooling area efficiency............................................................................................... 89 4.2.1.4.4 Cooler efficiency ........................................................................................................ 90
4.2.2 Calcinator (only for kiln system with cyclone preheater)..................................................... 90 4.2.2.1 Determination of the degree of precalcining.................................................................... 92
4.2.3 Preheater (only for kiln system with cyclone preheater) ...................................................... 93 4.2.3.1 Degree of separation of individual cyclone stages........................................................... 94
5. EVALUATION OF THE SUBSTANCE CIRCULATION SYSTEMS ............98
6. EVALUATION OF THE CEMENT CLINKER ..............................................99
6.1 Degree of burning......................................................................................................................... 99
6.2 Particle-size distribution.............................................................................................................. 99
6.3 Grindability ................................................................................................................................ 100
6.4 Chemical composition ................................................................................................................ 100
6.5 Phase composition ...................................................................................................................... 103
6.6 Microscopic examination........................................................................................................... 103
6.7 Cement testing ............................................................................................................................ 104
7. EVALUATION OF THE EMISSIONS ........................................................105
8. FORMULA SIGNS AND INDICES ............................................................106
9. LITERATURE REFERENCES...................................................................112
9.1 General literature references .................................................................................................... 112
9.2 Technical literature references.................................................................................................. 113
May 1992 Specification Vt 10 Page 5
10. EVALUATION EXAMPLE 1 (KILN SYSTEM WITH A CYCLONE PREHEATER, CALCINATOR AND TERTIARY AIR DUCT) ...........................118
10.1 Balancing the entire system .................................................................................................. 118
10.1.1 Solid substance mass flows ................................................................................................ 118 10.1.2 Gas volume flows ............................................................................................................... 119
10.1.2.1 Dry gas ...................................................................................................................... 119 10.1.2.1.1 Minimum air volume flow...................................................................................... 119 10.1.2.1.2 Air proportionality factors ...................................................................................... 120 10.1.2.1.3 Infiltrated air at the kiln hood ................................................................................. 120 10.1.2.1.4 Secondary air .......................................................................................................... 121 10.1.2.1.5 Cooler intake air ..................................................................................................... 121 10.1.2.1.6 Raw gas .................................................................................................................. 122 10.1.2.1.7 Gas downstream from the burning area .................................................................. 123 10.1.2.1.8 Gas downstream from the rotary kiln (kiln inlet) ................................................... 124 10.1.2.1.9 Infiltrated air (preheater)......................................................................................... 125 10.1.2.1.10 Infiltrated air (calcinator)...................................................................................... 125
10.1.2.2 Water vapor............................................................................................................... 125 10.1.2.2.1 Humidity in the air.................................................................................................. 125 10.1.2.2.2 Water from the kiln feed......................................................................................... 126 10.1.2.2.3 Water from the fuel................................................................................................. 127 10.1.2.2.4 Injection water ........................................................................................................ 127
10.1.2.3 Moist gas (examples) ................................................................................................ 128 10.1.3 Liquid mass flows............................................................................................................... 128 10.1.4 Energy flows....................................................................................................................... 128
10.1.4.1 Energy input .............................................................................................................. 128 10.1.4.1.1 Fuel ......................................................................................................................... 128 10.1.4.1.2 Kiln feed ................................................................................................................. 129 10.1.4.1.3 Air........................................................................................................................... 130 10.1.4.1.4 Injection water ........................................................................................................ 130 10.1.4.1.5 Mechanical performance ........................................................................................ 130
10.1.4.2 Energy output ............................................................................................................ 131 10.1.4.2.1 Reaction enthalpy of the kiln feed .......................................................................... 131
10.1.4.2.1.1 C3S, C2S, C3A and C4AF in the clinker ........................................................... 131 10.1.4.2.1.2 CaCO3, and MgCO3 in the kiln feed and in the raw gas dust........................... 132 10.1.4.2.1.3 CaCO3 and C2S in the bypass dust................................................................... 132 10.1.4.2.1.4 Balance equations ............................................................................................ 132
10.1.4.2.2 Water evaporation................................................................................................... 134 10.1.4.2.3 Waste gas losses ..................................................................................................... 134 10.1.4.2.4 Dust losses .............................................................................................................. 135 10.1.4.2.5 Incomplete combustion........................................................................................... 136 10.1.4.2.6 Clinker .................................................................................................................... 136 10.1.4.2.7 Radiation and convection: ...................................................................................... 137 10.1.4.2.8 Uncoupled heat ....................................................................................................... 137
10.1.4.3 Energy balance .......................................................................................................... 137
10.2 Balancing of the partial systems........................................................................................... 138 10.2.1 Clinker cooler ..................................................................................................................... 138
10.2.1.1 Solid substance mass flows ....................................................................................... 138
May 1992 Specification Vt 10 Page 6
10.2.1.2 Gas volume flows...................................................................................................... 138 10.2.1.3 Energy flows ............................................................................................................. 139
10.2.1.3.1 Energy input ........................................................................................................... 139 10.2.1.3.2 Energy output ......................................................................................................... 139 10.2.1.3.3 Energy balance ....................................................................................................... 141
10.2.1.4 Evaluation quantities................................................................................................. 142 10.2.1.4.1 Pre-cooling zone ..................................................................................................... 142 10.2.1.4.2 Energy loss flow of the cooling area ...................................................................... 142 10.2.1.4.3 Cooling area efficiency........................................................................................... 143
10.2.2 Calcinator ........................................................................................................................... 143 10.2.3 Preheater ............................................................................................................................. 144
10.3 Estimation of error................................................................................................................ 145
10.4 Tables...................................................................................................................................... 146
May 1992 Specification Vt 10 Page 7
1. Preliminary remarks
In cement plants, kiln performance tests not only serve to gather data on the performance
of the kiln system (clinker output, specific fuel-energy consumption), but also to create a
reliable foundation for the optimization of individual system components, of the opera-
tion and of the cement quality, as well as for the reduction of the level of emissions. The
important aspect here is the absolute value of the measured values. For this reason, this
specification, in addition to the evaluation, specifically contains information for carrying
out performance tests, including significant remarks pertaining to measurement technol-
ogy.
The units indicated in Section 8 apply to all numerical value equations. The practical fea-
sibility of the evaluation is always the main priority in the formulation of the numerical
value equations. The evaluation equations are employed in two practical examples in
Sections 10 and 11.
This specification deals primarily with energy and mass balances. Information on pres-
sure levels, stroke numbers and rotational speeds as well as on the consumption of elec-
tricity, in contrast, only serves to assess the kiln operation. Additional information in this
context would be necessary in order to obtain a precise measurement.
May 1992 Specification Vt 10 Page 8
2. Description of the clinker burning process
2.1 Reactions of the kiln feed
Portland cement clinker is made from a finely-ground raw material mixture consisting of
limestone, marl, clay and sand. The oxidic main components are calcium oxide (CaO),
silicon dioxide (SiO2), aluminum oxide (Al2O3) and iron oxide (Fe2O3).
The raw material mixture is heated up and burned in the rotary kiln to form clinker, a
process in which several chemical reactions take place, some of them consecutively, and
some of them in parallel to each other (see Figure 1).
Figure 1 - Schematic representation of the clinker formation reaction.
May 1992 Specification Vt 10 Page 9
The clinker formation reactions can be depicted as a model broken down into the fol-
lowing temperature stages:
• starting composition:
calcite (CaCO3), quartz (SiO2), clay minerals (SiO2-Al2O3-H2O) and iron ore (Fe2O3);
• up to about 700°C [1292°F], activation of the silicates through water expulsion and
modification change;
• between 700°C and 900°C [1292°F and 1652°F], calcination of the CaCO3 and concur-
rent binding of Al2O3, Fe2O3 as well as of activated SiO2 and CaO;
• once a maximum of 1200°C [2192°F] is reached, the formation of belite (“C2S”) from
SiO2 on CaO (“free lime”) is completed;
• starting at 1250°C [2282°F], and forced above 1300°C [2372°F] due to melt formation,
reaction of the belite with the remaining free lime to form alite (“C3S”);
• upon cooling, crystallization of the melt to form C3A and C4AF. In this process, the
alite and the belite remain virtually unchanged in their form and composition.
First of all, the physically bound water is removed when the kiln feed is preheated, while
the chemically bound water is removed up to a temperature of about 700°C [1292°F].
This is followed by the calcination (decarbonation, dissociation) of the calcium carbonate
into CaO and CO2, which practically takes place between 800°C and 900°C [1472°F and
1652°F]. After the complete decarbonation, the kiln feed has lost about 35% of its dry
weight.
Owing to solid-state reactions, the formation of the dicalcium silicate (2CaO · SiO2, in
short, C2S) already starts at about 700°C [1292°F]. Moreover, various calcium aluminate
and calcium ferrite compounds are formed as transition phases which, however, disinte-
grate again once the clinker melt starts to form at about 1280°C [2336°F]. At a sintering
temperature of around 1450°C [2642°F], it reaches a fraction of about 20% to 30% by
weight. The melt plays a significant role in the finishing burn of the clinker, since it pro-
May 1992 Specification Vt 10 Page 10
motes the formation of tricalcium silicate (3CaO · SiO2, in short, C3S) from solid dical-
cium silicate and CaO, which is indispensable for the strength properties of the cement.
As the melt cools down, essentially tricalcium aluminate (3CaO · Al2O3, in short, C3A)
and aluminate ferrite (4CaO · Al2O3 · Fe2O3, in short, C4AF) crystallize out.
After completion of the sintering, the cement clinker has to be cooled off so quickly that
the tricalcium silicate does not disintegrate, and the tricalcium aluminate crystallizes with
the finest grain possible. On the other hand, the cooling rate should not be so high that the
melt becomes glassy as it solidifies. In this context, qualitative differences occur which
depend on the composition of the kiln feed [48-53]. Consequently, the cooling of the
cement clinker has to be optimally harmonized with the required clinker properties.
2.2 Burning process
In Germany nowadays, cement clinker is produced in rotary kiln systems with kiln feed
preheaters located upstream and clinker coolers located downstream (for other process
techniques, see [2-4, 6-9 and 11-15]).
Rotary kilns are fire-proof, brick-lined tubes, having diameters of up to 6 meters and
inclined at an angle ranging from about 2.5° to 4.0°, which are operated at 1.5 to 3 rpm.
As a result of the inclination and rotation, the kiln feed coming from the preheater moves
towards the main burner of the rotary kiln, which is located at the lower end of the rotary
kiln. Rotary kilns with preheaters located upstream have a length that is 10 to 17 times
longer than their diameters. In order to reach the sintering temperature of about 1350°C
to 1500°C [2462°F to 2732°F] that is necessary for the formation of the clinker phase and
in view of the unfavorable heat-conduction conditions in the kiln feed, burning tempera-
May 1992 Specification Vt 10 Page 11
tures ranging from 1800°C to 2000°C [3272°F to 3632°F] or even higher are needed. In
order to be able to reach such high temperatures, the combustion air is preheated to about
600°C to 1000°C [1112°F to 1832°F] in a clinker cooler located downstream from the
sintering process, and it is then fed to the rotary kiln burner as so-called secondary air.
Grate-type coolers, satellite coolers and rotary coolers are employed as clinker coolers in
the cement industry. With grate-type coolers, the clinker that drops out of the rotary kiln
after the sintering operation is cooled in a crosscurrent. In the case of the rotary coolers or
satellite coolers, which usually consist of 10 satellite tubes attached around the periphery
of the rotary kiln, the clinker dissipates its energy to the cooling air that is flowing in a
cross current or countercurrent.
When it comes to kiln systems, a distinction is made as to whether they are operated with
a grate-type preheater or with a cyclone preheater. Grate-type preheaters consist of a
traveling grate on which the kiln feed that has been made into granules or briquettes trav-
els through a closed tunnel that is divided into a hot chamber and a dry chamber. An
intermediate gas fan blows the process gas of the rotary kiln from the top to the bottom
through the layer of granules in the hot chamber. After the coarse dust has been separated
out, the gas is once again blown from the top to the bottom through the moist granules in
the dry chamber.
The cyclone preheater essentially consists of four to five cyclone stages arranged one
above the other in a tower that is 50 to 100 meters high, depending on the clinker output.
The process gases coming from the rotary kiln flow through the cyclone preheater from
the bottom to the top. The dry, raw meal mixture is fed into the waste gases prior to
entering the uppermost cyclone stage, and it is once again separated from the gas in the
cyclones; afterwards, it re-enters the gas stream prior to the next-lower cyclone stage.
May 1992 Specification Vt 10 Page 12
Both with cyclone preheater systems and with grate-type preheater systems, the process
gas from the rotary kiln has a temperature of about 1000°C to 1200°C [1832°F to
2192°F]. The kiln feed entering the rotary kiln reaches temperatures of 820°C to 850°C
[1508°F to 1562°F] at precalcining degrees of up to about 90%. Upon leaving the cyclone
preheater, the waste gases have a temperature of around 290°C to 400°C [554°F to
752°F], depending on the number of stages and capacity flow ratio. As a function of the
process, the waste gases of the grate-type preheater have a temperature of about 90°C to
120°C [194°F to 248°F].
Figure 2 shows a schematic representation of a cement rotary kiln system with a cyclone
preheater and waste gas utilization. Figure 3 schematically shows a rotary kiln system
with a grate-type preheater.
Figure 2 - Schematic representation of a cement rotary kiln system
with cyclone preheaters and waste gas utilization.
May 1992 Specification Vt 10 Page 13
Figure 3 - Schematic representation of a cement rotary kiln system
with a grate-type preheater.
Since about 1970, the further development of kiln systems has led to the process involv-
ing precalcining. In this process, the fuel energy is divided up over two burners and, with
the secondary burner located between the rotary kiln and the preheater, the amount of
energy supplied is such that 70% to 95% of the calcium carbonate of the kiln feed has
already decarbonated by the time it enters the rotary kiln. For this purpose, new systems
with cyclone preheaters are provided with an enlarged combustion chamber between the
rotary kiln inlet and the lowermost cyclone, which is designated as the calcinator.
The combustion air for the secondary burner can be conveyed through the rotary kiln,
that is to say, together with the waste gas from the main burner. This method is employed
with old systems in particular. In the case of new systems with cyclone preheaters, how-
ever, the combustion air is conveyed in a separate gas duct, the so-called “tertiary air
duct”, which leads from the clinker cooler past the rotary kiln, and from there to the sec-
ondary burner. The principle involved in both techniques for conveying the combustion
May 1992 Specification Vt 10 Page 14
air is shown in Figure 4. A rotary kiln system with precalcining, consisting of a four-
stage cyclone preheater, calcinator, rotary kiln, reciprocating grate-type cooler and terti-
ary air duct, is shown in Figure 5. In rotary kiln systems having a calcinator but without a
tertiary air duct, up to 30% – in systems with a tertiary air duct, up to 60% – of the total
fuel energy needed can be employed in the secondary burner.
Figure 4 - Precalcining process with and without tertiary air duct.
May 1992 Specification Vt 10 Page 15
Figure 5 - Schematic representation of a cement rotary kiln system
with a cyclone preheater, calcinator and tertiary air
duct.
May 1992 Specification Vt 10 Page 16
3. Execution of kiln performance tests
3.1 Mode of operation of the kiln system
The considerations elaborated upon below apply exclusively to the stationary operation a
kiln system. The latter has to be safeguarded by means of appropriate measures.
The essential operating data (for instance, the mass flow of the kiln feed, the energy frac-
tion of the secondary fuel, types of fuel, composition of the kiln feed, type of combined
drying and grinding operation) should already have been determined during the planning
phase of the performance test and, in cases of major changes vis-à-vis normal operations,
should already have been established one week prior to the start of the performance test.
Neither shortly before nor during the performance test should there be any changes in the
composition of the kiln feed or of the fuel (for example, by changing the mixed bed).
Possible criteria for interrupting the performance test should also be laid down in
advance.
3.2 Duration of the performance test
A kiln performance test should last for at least 24 hours, preferably 48 or 72 hours. If the
type of combined drying and grinding operation changes (in, out, partial load), the per-
formance test should preferably last 72 hours.
May 1992 Specification Vt 10 Page 17
3.3 Measuring methods
3.3.1 Solid substances
3.3.1.1 Sampling
The objective of sampling is to obtain a random sample of each solid substance mass
flow that is representative of the parent population being examined.
The samples are taken from the belt (for instance, conveyor belt, apron conveyor), at the
discharge end of the conveyors (for instance, bucket elevator, screw conveyor) or from
the meal pipes (for example, the hot-meal pipe of a cyclone). The safety regulations that
apply in such cases must be observed. It must be ensured that the sample is taken over the
entire width of the material stream in order to take into account possible de-mixing phe-
nomena. Thus, for instance, when two partial streams having different concentrations of
the component to be examined are combined, which could give rise to insufficient
blending by the time the sampling site is reached, then this non-homogeneity has to be
taken into consideration by enlarging the scope of the sampling, that is to say, the sam-
pling amount and the sampling frequency have to be adapted to the prevailing test con-
ditions. Table 1 shows an example of a sampling plan.
Table 1 - Sampling amount and sampling frequency in rotary kiln performance tests.
Material
Sampling amount in kg
Sampling frequency
clinker ≥ 1 every hour
coal dust (main burner) ≥ 0.5 every four hours
coal dust (secondary burner) ≥ 0.5 every four hours
kiln feed ≥ 0.5 every four hours
raw gas dust ≥ 0.5 every four hours 1)
tertiary air dust ≥ 0.5 every four hours 1)
bypass dust ≥ 0.5 every two hours
Kiln feed in the preheater ≥ 0.5 every four hours 1) With partial-stream suction, every 12 hours.
May 1992 Specification Vt 10 Page 18
A partially decarbonated kiln feed should be cooled off rapidly and air-tight so as to
avoid, for example, further decarbonation of CaCO3 or a residual burn-out of carbon.
For practical reasons, the samples can also be taken at time-staggered intervals. Samples
of solid substances from flowing gases (raw gas dust, tertiary air dust) can also be taken
by means of isokinetic suction of a partial stream. In this process, care should be taken to
ensure that the suction is representative.
The individual samples are pre-comminuted (for example, clinker), homogenized and
combined to form a weighed average sample for the duration of the performance test.
As a matter of principle, the individual and average samples should be stored air-tight in
order to avoid a falsification of the H2O and CO2 contents. High levels of moisture (for
instance, in the raw material) should be determined on larger individual samples; the
average sample is subsequently formed on the basis of the pre-dried individual samples.
3.3.1.2 Analysis
Table 2 shows an example of an analysis plan. As a matter principle, the laboratory
should be informed about the source and presumed composition of the samples. This
ensures that the best suited decomposition and analysis methods will be selected for each
particular case.
May 1992 Specification Vt 10 Page 19
Table 2 - Analysis and analysis method for rotary kiln performance tests.
Material
Analysis
Analysis method
Coal dust
sampling, sample preparation
DIN 51701 (Part 3), ISO 1988, ISO 2309
calorific value DIN 51900, ISO 1928
H2O DIN 51718, ISO 331, ISO 348, ISO 579, ISO 589, ISO 687, ISO 1015
ash DIN 51719, ISO 1171
ash composition DIN 51729
volatile components DIN 51720, ISO 562
C and H DIN 51721, ISO 609, ISO 625
S DIN 51724 (Part 1), ISO 334, ISO 351
Cl – DIN 51727, ISO 352, ISO 587
N DIN 51722 (Part 1), ISO 333
O subtraction
Oil
sampling
DIN 51570 (Parts 1 to 3)
calorific value DIN 51900, ISO 1928
H2O DIN 51777, ISO 3733
ash DIN EN 7
C and H DIN 51721 1)
S DIN EN 41, DIN 51400
Cl – DIN 51722 1)
N subtraction
Natural gas
composition
DIN 51872
O DIN 51856
S DIN 51855
Clinker, tertiary
air dust
sample preparation
Grinding for complete passage through the sieve, 0.09 mm (for CaOfree 0.063)
loss on ignition 1000°C [1832°F] ± 25 K (10 min) or 950°C [1742°F] ± 25 K until weight constancy is achieved
May 1992 Specification Vt 10 Page 20
X-ray fluorescent
full analysis 2) a) fluxing agent tablet (≤ 1000°C [1832°F]; 81%
by weight of Li2B4O7 + 8.1% by weight of LiF + 8.9% by weight of SrO + 2% by weight of V2O5 as the decomposition agent; dilution of 1:5 to 1:20); analysis including SO3 and alkali
b) fluxing agent tablet (1050°C [1922°F]; 90% by weight of Li2B4O7 + 10% by weight of LiF as the decomposition agent; dilution of 1:10); determination of SO3, K2O and Na2O with other analytical methods, subsequent correction of the results
c) fluxing agent tablet (1200°C [2192°F]; 100% by weight of Li2B4O7 as the decomposition agent; dilution of 1:5); determination of SO3, K2O and Na2O with other analytical methods, subsequent correction of the results
Cl – (including Br and I) 3) Decomposition:
a) nitric acid (1 part of concentrated nitric acid + 19 parts of water)
b) acetic anhydride (7+6)
c) thermal reaction in a moist O2 stream at 1000°C [1832°F] so as to form hydrogen chloride
Analysis:
a) potentiometric titration with silver nitrate
b) titration according to Volhardt
c) introduction of the hydrogen chloride into an acetic silver nitrate solution and coulometric titration
The weighed-in amount has to be adapted to the low Cl – content of the clinker (5 to 10 g)
Σ SO3 a) gravimetric
b) thermal reaction of the sulfur compounds with additives in the oxygen stream. Measurement of the SO2 by means of an IR detector or else iodometrically
K2O, Na2O J.L. Smith decomposition, hydrofluoric acid decomposition / perchloric acid decomposition (observe the safety regulations!) or melt decompo-sition (< 1000°C [1832°F]) with Li2B4O7, flame photometry (emission, absorption)
CaOfree a) method according to Franke
b) method according to Schläpfer and Bukowski Depending on the boundary conditions, the results can deviate from one method to another
May 1992 Specification Vt 10 Page 21
Kiln feed
sample preparation
Grinding for complete passage through the sieve, 0.09 mm
CO2 Thermal degradation in the inert gas stream at 1000°C [1832°F] or chemical degradation with acid
a) gravimetric
b) coulometric
c) IR detection
H2O < 110°C [230°F] 4) Weighing, drying at 110°C [230°F], cooling in a desiccator, weighing
Σ H2O Thermal desorption in an inert gas stream at 1000°C [1832°F]
a) KF titration
b) IR detection
c) gravimetric
Corg Decarbonation with hydrochloric acid, thermal reaction of the carbon compounds in an oxygen stream
a) gravimetric
b) coulometric
c) IR detection
X-ray fluorescent full analysis 2)
a) fluxing agent tablet (≤ 1000°C [1832°F]; 81% by weight of Li2B4O7 + 8.1% by weight of LiF + 8.9% by weight of SrO + 2% by weight of V2O5 as the decomposition agent; dilution of 1:5 to 1:20); analysis including SO3 and alkali
b) fluxing agent tablet (1050°C [1922°F]; 90% by weight of Li2B4O7 + 10% by weight of LiF as the decomposition agent; dilution of 1:10); determination of SO3, K2O and Na2O with other analytical methods, subsequent correction of the results
c) fluxing agent tablet (1200°C [2192°F]; 100% by weight of Li2B4O7 as the decomposition agent; dilution of 1:5); determination of SO3, K2O and Na2O with other analytical methods, subsequent correction of the results
Cl – (including Br and I) 3) Decomposition:
a) nitric acid (1 part of concentrated nitric acid + 19 parts of water)
b) acetic anhydride (7+6)
c) thermal reaction in a moist O2 stream at 1000°C [1832°F] so as to form hydrogen chloride
May 1992 Specification Vt 10 Page 22
Analysis:
a) potentiometric titration with silver nitrate
b) titration according to Volhardt
c) introduction of the hydrogen chloride into an acetic silver nitrate solution and coulometric titration
The weighed-in amount has to be adapted to the low Cl – content of the clinker (5 to 10 g)
Σ SO3 a) oxidation with bromine water, gravimetric
b) thermal reaction of the sulfur compounds with additives in the oxygen stream. Measurement of the SO2 by means of an IR detector or else iodometrically
K2O, Na2O J.L. Smith decomposition, hydrofluoric acid
decomposition / perchloric acid decomposition (observe the safety regulations!) or melt decompo-sition (< 1000°C [1832°F]) with Li2B4O7, flame photometry (emission, absorption)
S2– Dissolution with hydrochloric acid containing SnCl2 in the presence of Cr (metallic), pick-up in a cooled (≤ 15°C [59°F]) ammoniacal ZnSO4 or CdCl2 solu-tion, iodometry
sample preparation Grinding for complete passage through the sieve, 0.09 mm
Raw gas dust 5)
(cyclone preheater
kiln) CO2 Thermal degradation in an inert gas stream at 1000°C [1832°F] or chemical degradation with acid
a) gravimetric
b) coulometric
c) IR detection
Σ H2O Thermal desorption in an inert gas stream at 1000°C [1832°F]
a) KF titration
b) IR detection
c) gravimetric
Corg Decarbonation with hydrochloric acid, thermal reaction of the carbon compounds in an oxygen stream
a) gravimetric
b) coulometric
c) IR detection
May 1992 Specification Vt 10 Page 23
X-ray fluorescent
full analysis 2) a) fluxing agent tablet (≤ 1000°C [1832°F]; 81%
by weight of Li2B4O7 + 8.1% by weight of LiF + 8.9% by weight of SrO + 2% by weight of V2O5 as the decomposition agent; dilution of 1:5 to 1:20); analysis including SO3 and alkali
b) fluxing agent tablet (1050°C [1922°F]; 90% by weight of Li2B4O7 + 10% by weight of LiF as the decomposition agent; dilution of 1:10); determination of SO3, K2O and Na2O with other analytical methods, subsequent correction of the results
c) fluxing agent tablet (1200°C [2192°F]; 100% by weight of Li2B4O7 as the decomposition agent; dilution of 1:5); determination of SO3, K2O and Na2O with other analytical methods, subsequent correction of the results
Cl – (including Br and I) 3) Decomposition:
a) nitric acid (1 part of concentrated nitric acid + 19 parts of water)
b) acetic anhydride (7+6)
c) thermal reaction in a moist O2 stream at 1000°C [1832°F] so as to form hydrogen chloride
Analysis:
a) potentiometric titration with silver nitrate
b) titration according to Volhardt
c) introduction of the hydrogen chloride into an acetic silver nitrate solution and coulometric titration
The weighed-in amount has to be adapted to the low Cl – content of the clinker (5 to 10 g)
Σ SO3 a) oxidation with bromine water, gravimetric
b) thermal reaction of the sulfur compounds with additives in the oxygen stream. Measurement of the SO2 by means of an IR detector or else iodometrically
K2O, Na2O J.L. Smith decomposition, hydrofluoric acid decomposition / perchloric acid decomposition (observe the safety regulations!) or melt decompo-sition (< 1000°C [1832°F]) with Li2B4O7, flame photometry (emission, absorption)
S2– Dissolution with hydrochloric acid containing SnCl2 in the presence of Cr (metallic), pick-up in a cooled (≤ 15°C [59°F]) ammoniacal ZnSO4 or CdCl2 solu-tion, iodometry
May 1992 Specification Vt 10 Page 24
sample preparation
Grinding for complete passage through the sieve, 0.09 mm
Bypass dust 5)
Kiln feed in the
preheater5)
Raw gas dust 5)
(grate-type pre-
heating kiln)
CO2 Thermal degradation in an inert gas stream at 1000°C [1832°F] or chemical degradation with acid
a) gravimetric
b) coulometric
c) IR detection
Σ H2O Thermal desorption in an inert gas stream at 1000°C [1832°F]
a) KF titration
b) IR detection
c) gravimetric
Corg Decarbonation with hydrochloric acid, thermal reaction of the carbon compounds in an oxygen stream
a) gravimetric
b) coulometric
c) IR detection
K2O, Na2O J.L. Smith decomposition, hydrofluoric acid decomposition / perchloric acid decomposition (observe the safety regulations!) or melt decompo-sition (< 1000°C [1832°F]) with Li2B4O7, flame photometry (emission, absorption)
Cl – (including Br and I) 3) Decomposition:
a) nitric acid (1 part of concentrated nitric acid + 19 parts of water)
b) acetic anhydride (7+6)
Analysis:
a) potentiometric titration with silver nitrate
b) titration according to Volhardt
c) coulometric titration
d) gravimetric
Σ SO3 a) oxidation with bromine water, gravimetric
b) thermal reaction of the sulfur compounds with additives in the oxygen stream. Measurement of the SO2 by means of an IR detector or else iodometrically
S2– Dissolution with hydrochloric acid containing SnCl2 in the presence of Cr (metallic), pick-up in a cooled (≤ 15°C [59°F]) ammoniacal ZnSO4 or CdCl2 solu-tion, iodometry
May 1992 Specification Vt 10 Page 25
1) Since there are no specifications for mineral oils, the analysis method for fuels is employed. 2) SiO2, Al2O3, TiO2, P2O5, Fe2O3, Mn2O3, CaO, MgO, SO3, K2O, Na2O. (Σ SO3, K2O, Na2O should be
checked by other analytical methods. In addition to the above-mentioned compounds, the solid materials might also contain fluoride, barium oxide and strontium oxide or S2–. During the reducing burning proc-ess, clinker contains FeO and MnO. If this is already known to be so, the laboratory should be informed to this effect.)
3) Nitric acid extraction does not always dissolve all of the halides out of the sample matrix. This can lead to erroneously low results at low levels of Cl– in the raw material.
4) Alternatively, < 105°C [221°F]. 5) Dust as well as the kiln feed in the preheater can also contain highly volatile compounds such as, for
instance, (NH4)2SO4. In the case of sensitive samples that are hygroscopic or that react during the drying process, the examinations should be performed in the delivery state.
3.3.1.3 Mass flows
Clinker:
The clinker is loaded onto trucks or railroad cars and weighed on calibrated scales (for
example, shipping scales). In each case, the trucks or railroad cars are weighed both
empty and fully loaded (varying amounts of fuel in the tank, dirt). An interim result
should be determined every 4 to 6 hours in order to obtain information about the time
course of the mass flow. The duration of the clinker weighing can differ from the per-
formance test duration, but it should not be shorter than 24 hours. The maximum error is
smaller with a duration of 48 hours. Prior to the test, the weighing procedure should be
checked.
Continuously operating clinker scales can be adjusted by the above-mentioned method,
even over shorter periods of time. For this purpose, several measuring intervals are
needed, for example, every 4 hours with different clinker production. The measured value
from the performance test is then multiplied by the resulting correction values.
May 1992 Specification Vt 10 Page 26
In the case of immediately consecutive kiln performance tests, a second clinker weighing
procedure is not necessary if it is ensured that all of the dust mass flows remain constant.
The following relationship applies:
Fuels:
Fuels are weighed on industrial scales which have been previously adjusted. However,
the precision levels achieved in this manner are often not sufficient for evaluating the kiln
system. For this reason, the fuel energy consumption is usually balanced by means of a
comparison of the energy output with the energy input (see Section 4.1.4.3).
Kiln feed:
The kiln feed mass flow is calculated. It results from the component balance of the sum
of the non-volatile substances (see Section 4.1.1).
Dust:
Dust is preferably weighed on calibrated scales (for example, shipping scales). Here, care
should be taken to ensure that the cleaning of the filter is switched to continuous opera-
tion before the dust is discharged. If weighing is not possible, the dust mass flow is
determined by means of an isokinetic partial stream suction (in this context, also see the
VDZ Specification titled “Dust quantity measurements in cement plants” [17]).
Translator’s note: See Section 8 for the list of abbreviations used in the formulas.
May 1992 Specification Vt 10 Page 27
3.3.2 Gases
For the gas analysis, more information can be obtained from the VDZ Specification titled
“Continuous gas analysis in cement plants” [20]), while information on volume flow
measurement is to be found in the VDZ Specification titled “Quantity measurement of
gases by means of velocity measurements” [16]). Table 3 shows an example of a meas-
urement plan.
Table 3 - Volume flow measurement and gas analysis in rotary kiln performance tests.
Measuring site
Volume flow measurement
Gas analysis
raw gas pitot tube CO2, O2, CO
bypass gas (with cooling air) pitot tube CO2, O2, CO 1)
bypass gas (without cooling air) – CO2, O2, CO 1)
downstream from the burning area – CO2, O2, CO
kiln inlet – CO2, O2, CO
tertiary air pitot tube –
cooler intake air – –
cooler vent air pitot tube –
burner air (main burner) pitot tube + rated values –
burner air (secondary burner) pitot tube + rated values –
conveying air (kiln feed) rated values –
1) Discontinuous measurement is often sufficient.
3.3.2.1 Sampling
In the raw gas, in the bypass gas and in the gas downstream from the burning area, vari-
ous gas compositions can occur over the cross section of the duct. Moreover, in the case
of double-string cyclone preheaters, there are also differences in the individual strings. In
the gas downstream from the burning area, the time intervals at which the probes need to
May 1992 Specification Vt 10 Page 28
be cleaned can be extended by placing the measuring gas sampling opening as far as pos-
sible from the meal inlet pipes. The probe in the gas downstream from the burning area
should be cooled.
In the rotary kiln inlet, the process gas usually displays great differences in concentration,
both with respect to location and to time. For this reason, it is not possible to specify a
representative measuring site. Sampling sites in the upper third of the rotary kiln cross
section are recommended. The sampling opening should project about 0.5 m into the
rotating part of the kiln in order to avoid falsifications of the measured results due to
infiltrated air that gets into the inlet gasket or as a result of falling kiln feed material.
Since the measuring site is also frequently exposed to falling material, the sampling probe
should be built laterally into the refractory brickwork. So as to prevent falsifications of
the concentration values due to the scrubbing out of individual gas components, the
measuring gas should be sampled dry, that is to say, without injection water or scrubbing
water. The probe should be cooled.
3.3.2.2 Analysis
The gas analysis should be carried out continuously. At the very least, determinations of
CO2, O2 and CO are required.
3.3.2.3 Volume flows
The volume flows are primarily measured with a pitot tube. With volumes flows that
fluctuate markedly (for instance, cooler vent air), the pitot tube should be installed in the
May 1992 Specification Vt 10 Page 29
gas duct and the differential pressure as well as the appertaining temperature should be
recorded continuously.
There are three methods for measuring the raw gas volume flow:
a) direct measurement with a pitot tube (in the case of unfavorable measuring condi-
tions, for example, deflection of the gas upstream from the measuring site, substantial
pressure fluctuations or a high amount of dust [for instance, > 50 g/m³], this is often
very imprecise);
b) calculation on the basis of a CO2 and an H2O balance of the kiln system (imprecise
when secondary fuels are used) [30];
c) conversion of the clean gas volume flow to raw gas conditions using an O2 or CO2
balance or an H2O balance (additional gas analysis and measurement of the volume
flow in the clean gas is necessary; only possible if clean gases of the kiln can be
detected in their entirety; expensive but accurate).
There are three methods for measuring the volume flow of the cooler intake air:
a) inlet nozzles (often very imprecise);
b) fan characteristic curves (only possible for fans with adjustable rotational speeds);
c) air balance of the cooler (often the most precise way with continuous volume flow
measurement of the cooler vent air after the dust removal).
The bypass gas is measured with a pitot tube after admixing the cooling air. The bypass
gas volume flow prior to the admixture is derived from the gas analysis before and after
the admixture of the cooling air.
May 1992 Specification Vt 10 Page 30
The volume flow of infiltrated air at the kiln hood is calculated on the basis of the open
cross-sectional area and of the differential pressure at the kiln hood (see Section 4.1.2.3).
The cross-sectional surface area is either measured or estimated.
The conveying air volume flow of the coal dust and, if applicable, of the kiln feed is
derived from the nominal data of the fan.
Heating gas that has been measured volumetrically has to be converted to the standard
conditions.
3.3.3 Liquids
3.3.3.1 Heating oil
Heating oil can be sampled either by means of an automatic sampling system or else a
sample is taken from the oil tank. The amount of oil that passes through the burner nozzle
per unit of time is for the most part measured volumetrically by means of an oil meter. In
order to determine the actual volume flow that passes through, the result that is read off
the meter has to be corrected by means of a calibration curve. Moreover, it is necessary to
take into account the density, which changes as a function of the temperature.
3.3.3.2 Water
The water mass flow of a cooling chute (cooling water) or into the clinker cooler (injec-
tion water) is measured with water meters that have to be installed in advance.
May 1992 Specification Vt 10 Page 31
3.3.4 Temperatures
Table 4 shows the example of a measuring plan.
Table 4 - Temperature measurement in rotary kiln performance tests.
Measuring site Measuring device Frequency
cold clinker compensation temperature in adiabatic vessel, Pt 100
every hour
hot clinker quotient pyrometer continuously
kiln feed in the preheater (e.g. hot meal) NiCr Ni twice per day
bypass dust Pt 100 or NiCr Ni once per day
raw meal (for instance, kiln feed)
Pt 100 or surface temperature of the conveying line with partial-radiation pyrometer
once per day
fuels Pt 100 or surface temperature of the conveying line with partial-radiation pyrometer
once per day
raw gas Pt 100 or NiCr Ni continuously
bypass gas (with cooling air) Pt 100 or NiCr Ni continuously
gas downstream from the burning area NiCr Ni continuously
tertiary air upstream from the preheater NiCr Ni once per day
tertiary air downstream from the cooler NiCr Ni continuously
cooler intake air meteorological station continuously 1)
cooler vent air Pt 100 or NiCr Ni continuously
burner air (main burner) Pt 100 or NiCr Ni once per day
burner air (secondary burner) Pt 100 or NiCr Ni once per day
conveying air (kiln feed) like kiln feed –
surface temperature - rotary kiln partial-radiation pyrometer (ε = 0.9)
twice per day
surface temperature - cooler partial-radiation pyrometer (ε = 0.9) once per day 2)
twice per day 3)
kiln hood partial-radiation pyrometer (ε = 0.9) once per day
calcinator partial-radiation pyrometer (ε = 0.9) once per day
preheater partial-radiation pyrometer (ε = 0.9) once per day 1) if available 2) with grate-type coolers 3) with rotary coolers or satellite coolers
May 1992 Specification Vt 10 Page 32
3.3.5 Pressures
In order to evaluate the kiln operation, the following differential pressures should be
measured or recorded by the operating measuring pick-ups:
• cooler (chambers 1 through N);
• kiln outlet;
• kiln inlet;
• preheater (stages 1 through N);
• upstream from the waste gas fan;
• downstream from the waste gas fan.
The above-mentioned differential pressures have to be measured with damped measuring
pick-ups.
3.3.6 Strokes and rotational speeds
In order to evaluate the kiln operation, the strokes and rotational speeds of the following
aggregates should be measured or recorded by the operating measuring pick-ups:
• cooler;
• kiln;
• grate-type preheater;
• waste gas fan;
• bag house fan / ESP fan;
• cooler vent fan;
• bypass fan.
May 1992 Specification Vt 10 Page 33
3.3.7 Electricity consumption
In order to evaluate the kiln operation, the meter readings of the main consumers should
be recorded at intervals of, for example, 8 hours.
A large proportion of the electricity is converted into heat in the kiln system. Conse-
quently, when the balancing space is calculated, the consumption of electricity should be
considered as an input item of the energy balance.
If several consumers are connected to one meter, the energy distribution should be meas-
ured with prong-type instruments. The following consumers should be taken into consid-
eration:
• cooler fans;
• cooler vent fan;
• cooler drives;
• burner air fan;
• rotary kiln drive;
• bypass fan;
• waste gas fan;
• kiln feed feeding system;
• fuel feeding system.
3.3.8 Ambient conditions
The temperature, pressure and relative humidity of the ambient air are recorded by a
meteorological station.
May 1992 Specification Vt 10 Page 34
3.3.9 Ensuring the precision of the measurements and analyses
The precision of a kiln examination depends on the systematic maintenance and upkeep
of the measuring instruments. In addition to regularly checking the status and settings
during the performance test, it is also necessary to routinely replace wearing parts as pre-
ventive maintenance and to conduct function tests with comparative measured values
(calibration). Checks and corrections should be documented and should be indicated on
the measuring equipment used, together with the date.
Status checks should be made every hour and setting checks should be carried out at least
before and after the performance test. The time schedule for replacing wearing parts and
for the function tests with comparative measured values depends on the measuring instru-
ments and should be laid down appropriately.
Table 5 provides an overview of possible comparative measuring methods.
Table 5 - Comparative measuring instruments or method for rotary kiln performance tests.
Measuring instrument
Comparative measuring instrument or method
gas analyzer gas analyzer with another measuring principle wet-chemical analysis
gas meters testing by the Board of Weights and Measures
thermal elements resistance thermometer
test thermometer and normal thermometer (for instance, plati-num resistance thermometer)
pyrometer black body radiator tungsten band lamp (only above 500°C [932°F])
pressure transducer liquid pressure gage (for instance, miniscope or U-tube)
humidity measuring device sealed container with several aqueous saturated salt solutions
The solid substance analyses have to be conducted by a laboratory that has sufficient
experience with the execution of the analyses listed in Table 2.
May 1992 Specification Vt 10 Page 35
4. Evaluation of kiln performance tests
4.1 Balancing of the entire system
When the mass balance is drawn up, the gas and solid substance mass flows should be
balanced together, since there are interactions between both of these as a result of chemi-
cal reactions.
Figure 6 shows the balancing space of a kiln system with a cyclone preheater (V), calci-
nator (C), tertiary air duct (T), rotary kiln (D) and cooler (K) with the mass and energy
flows that exceed the balance limit as an example. With other kiln types, the changes are
only gradual, as a result of which a separate presentation has not been provided. The fol-
lowing mass and energy flows have been taken into account:
Incoming solid substance mass flows:
S1m& for the kiln feed
B7m& for the fuel (main burner) *)
B3m& for the fuel (secondary burner) *)
Outgoing solid substance mass flows:
S10m& for the clinker
St5m& for the bypass dust
St1m& for CFl,H& raw gas dust
St12m& for the discharged tertiary air dust (only relevant in kiln systems with a terti-
ary air duct and high levels of dust in the tertiary air)
*) Liquid or gaseous fuel can also be fed in.
May 1992 Specification Vt 10 Page 36
Incoming gas volume flows **)
L10V& for the cooler intake air
L7V& for the burner air (main burner)
L3V& for the burner air (secondary burner)
L1V& for the conveying air (kiln feed)
DFl,V& for the infiltrated air (kiln hood)
C Fl,V& for the infiltrated air (calcinator)
V Fl,V& for the infiltrated air (preheater)
Outgoing gas volume flows:
L11V& for the cooler vent air
G1V& for the raw gas
G5V& for the bypass gas
Incoming liquid mass flows:
O,10H 2m& for the cooler injection water
Incoming energy flows:
S1H& for the kiln feed
B7H& for the fuel (main burner)
B3H& for the fuel (secondary burner)
**) The formula sign V& below designates the volume flow related to standard conditions (0°C [32°F], 1013
hPA), while the formula sign trV& designates the volume flow related to standard conditions after removal
of the water-vapor fraction.
May 1992 Specification Vt 10 Page 37
L10H& for the cooler intake air
L7H& for the burner air (main burner)
L3H& for the burner air (secondary burner)
L1H& for the conveying air (kiln feed)
DFl,H& for the infiltrated air (kiln hood)
CFl,H& for the infiltrated air (calcinator)
VFl,H& for the infiltrated air (preheater)
BR,H&∆ for the reaction enthalpy of the fuels
10 O,H2H& for the cooler injection water
mechP for the mechanical performance
Outgoing energy flows:
S10H& for the clinker
St5H& for the bypass dust
St1H& for the raw gas dust
St12H& for the discharged tertiary air dust
L11H& for the cooler vent air
G1H& for the raw gas
G5H& for the bypass gas
SR,H&∆ for the reaction enthalpy of the kiln feed
OHV, 2H&∆ for the evaporation enthalpy of the cooler injection water
KK,Q& for the uncoupled heat (cooler)
May 1992 Specification Vt 10 Page 38
COR,H&∆ for the incomplete burning
VW,Q& for radiation and convection losses (preheater)
CW,Q& for radiation and convection losses (calcinator)
DW,Q& for radiation and convection losses (rotary kiln)
TW,Q& for radiation and convection losses (tertiary air duct)
KW,Q& for radiation and convection losses (cooler + kiln hood)
May 1992 Specification Vt 10 Page 39
Figure 6 - Balancing spaces for preheater, calcinator, tertiary air duct, rotary kiln and cooler with incoming and outgoing mass and energy flows.
May 1992 Specification Vt 10 Page 40
With rotary and satellite coolers, the cooling air volume flow is used completely as com-
bustion air in the process, whereas in contrast, it is only partially used as such with grate-
type coolers. In the case of the latter, excess cooling air is released as cooler vent air.
When the waste gas leaves the preheater, it still contains relatively large amounts of dust.
Therefore, the waste gas is designated as “raw gas” and the dust as “raw gas dust”. With
grate-type coolers, some of the cooler vent air can be returned to the cooler as intake air
via a fan once the dust has been removed and cooled (duothermal configuration). This
was taken into consideration in the figure by the uncoupled heat flow KK,Q& . Cooler vent
air dust has not been taken into account.
4.1.1 Solid substance mass flows
Measured quantities: clinker, fuel (main burner), fuel (secondary burner), bypass
dust, raw gas dust, discharged tertiary air dust.
Operands: mass flow of the kiln feed.
In order to balance the mass flows, a component balance is drawn up of the sum of the
non-volatile substances (for example, SiO2, Al2O3, TiO2, P2O5, Fe2O3, Mn2O3, CaO,
MgO) whose mass concentration in the individual substance flows is designated by xNF *).
The following applies:
*) The formula sign x below stands for the mass concentration of the solids at the balance limit (= delivery
condition in the laboratory).
May 1992 Specification Vt 10 Page 41
The loss on ignition can also be used for a rough estimate. By using xG to designate the
mass concentration of the substances that are released during calcination at about 1000°C
[1832°F] until weight constancy is achieved, the following applies analogously:
The kiln feed mass flow necessary for the clinker burning process then results from
Equation (2):
As an approximation, the following applies to the kiln feed mass flow that actually
becomes clinker (including discharged tertiary air dust):
The ratio of kiln feed to clinker necessary for the clinker burning process then results
from Equation (4):
May 1992 Specification Vt 10 Page 42
Analogously, the following applies:
4.1.2 Gas volume flows
Measured quantities: fuel (main burner), fuel (secondary burner), cooler vent air
(if present), burner air (main burner), burner air (secondary
burner), bypass gas, raw gas, conveying air (kiln feed).
Operands: infiltrated air, secondary air, cooler intake air (see Section
3.3.2.3).
4.1.2.1 Dry gas
4.1.2.1.1 Minimum air volume flow
In order to calculate the dry, minimum air volume flow, the burning of all combustible
substances has to be taken into consideration. For this reason, in addition to the fuel mass
flows B7m& and B3m& , the combustible components (organically bound carbon, sulfide sul-
fur) of the kiln feed also have to be taken into account.
May 1992 Specification Vt 10 Page 43
By designating the carbon content of the kiln feed as xC,S1, the carbon content of the raw
gas dust as xC, St1 and the carbon content of the bypass dust as xC, St5, the following results
for the carbon mass flow S eff,C,m& effectively fed into the kiln system:
Analogously, the following applies for S eff, S,m& :
Frequently, St5C,x and St5S,x are approximately zero. The minimum air volume flow
minL,V& to burn all of the combustible substances then amounts to the following:
lmin is the minimum air demand of the fuel in question in its raw state. This value can be
calculated on the basis of elementary analyses of the fuel according to Equation (11):
May 1992 Specification Vt 10 Page 44
Accordingly, the numerical value equation is the following:
For oil and coal, lmin can be calculated as an approximation using the lower calorific
value of the fuel *). The following applies:
For lignitic coal and coal:
For heating oil:
Table 6 shows examples of elementary analyses and calorific value-related combustion
gas quantities of lignitic coal and coal. Calorific value-related combustion gas quantities
of secondary fuels can differ markedly from the indicated uppermost and lowermost val-
ues.
*) The formula sign hu below stands for the lower calorific value of the coal at the balance limit threshold
(= delivery condition in the laboratory).
May 1992 Specification Vt 10 Page 45
Table 6 - Elementary analyses of lignitic coal dust and coal dust
with the combustion gas quantities calculated therefrom
and related to the lower calorific value in the raw state.
Lignitic coal dust
Coal dust
Analyses (raw) in % by weight:
L M U L M U
water 8.7 11.8 14.0 0.8 1.9 2.9
ash 3.4 4.5 8.3 11.9 19.1 29.3
C 56.1 59.2 61.4 57.3 65.8 71.7
H 3.9 4.2 4.5 2.6 3.6 4.4
O 16.1 19.4 23.7 4.5 7.2 8.7
N 0.4 0.5 0.6 0.7 1.3 2.0
S 0.2 0.3 0.7 0.6 1.0 2.1
calorific value (raw) in MJ/kg: 20.22 21.92 22.76 21.35 25.05 27.80
Calorific value-related combus-
tion gas quantity in kg/MJ:
minimum air demand 0.332 0.339 0.347 0.339 0.341 0.344
carbon dioxide 0.096 0.098 0.101 0.094 0.096 0.099
water vapor 0.021 0.022 0.024 0.011 0.014 0.016
moist flue gas 0.374 0.382 0.392 0.370 0.373 0.375 L = lowermost value; M = mean value; U = uppermost value
4.1.2.1.2 Air proportionality factor
The following applies in general:
May 1992 Specification Vt 10 Page 46
The air proportionality factor in the waste gas results as an approximation from the values
of the gas analysis (in the case of Orsat analyses and measuring methods that work with
extraction, as a rule related to dry measuring gas):
The expression in the denominator of the lower fraction corresponds to N2.
4.1.2.1.3 Infiltrated air at the kiln hood
The volume flow of infiltrated air at the kiln hood can be roughly calculated using the
Bernoulli equation. The following applies theoretically:
Equation (17) presupposes a frictionless flow and an incompressible medium. In reality,
neither is present. As a consequence, the equation yields an excessively high gas velocity.
Consequently, for actual practice, the gas velocity has to be multiplied by a dimension-
less factor which lies between 0.6 and 0.9, Here, it has been set at 0.75. Thus, the fol-
lowing applies:
May 1992 Specification Vt 10 Page 47
With /FVv &= for the gas velocity and with the density ratio ρ L /ρ L,N for dry air (the
water present in the air is ignored here), the result is a calculation equation for the volume
flow of infiltrated air:
wherein
∆p = differential pressure at the kiln hood in Pa
ρ L = density of the air in the cross section F in kg/m³
ρ L,N = density of the ambient air under standard conditions (s.c.) in kg/m³
F = open cross-section area in m²
tr D,Fl,V& = volume flow of infiltrated air in m³ (s.c.)/s
As a simplification, the density of the ambient air can be taken as the basis for ρ L.
4.1.2.1.4 Secondary air
The following applies for the volume flow of the secondary air (also see Figure 12):
Due to non-representative gas analyses in the kiln inlet, trL8,V& can only be calculated very
imprecisely.
May 1992 Specification Vt 10 Page 48
4.1.2.1.5 Cooler intake air
The following applies for the volume flow of the cooler intake air (also see Figure 12):
4.1.2.1.6 Raw gas
1. Calculation on the basis of the CO2 balance
The following applies for the CO2 balance:
S,CO2V& stems from the decarbonation and the combustion of organic components of the
kiln feed. The following applies:
wherein
and
Seff,,Cm& according to Equation (8).
May 1992 Specification Vt 10 Page 49
B,CO2V& stems from the combustion of the fuel. The following applies:
If the elementary analysis is not available, Equation (26) can be employed:
wherein
2COµ = 5.01 · 10 –
5 m³ of CO2/kJ for lignitic coal
and 2COµ = 4.87 · 10
– 5 m³ of CO2/kJ for coal.
G5,CO2V& results from the gas analysis and from the measurement of the gas volume flow
in the bypass gas:
With
the result is the calculation equation for the raw gas volume flow:
May 1992 Specification Vt 10 Page 50
2. Calculation on the basis of the clean gas volume flow
This calculation is only possible if the entire clean gas volume flow of the kiln system
can be determined and if no auxiliary burner is operated in the combined drying and
grinding mill.
CO2 balance:
O2 balance:
4.1.2.1.7 Gas downstream from the burning area
trG2,V& is calculated according to Equations (30) or (31) on the basis of the raw gas vol-
ume flow. A gas analysis downstream from the burning area is needed for this purpose.
4.1.2.1.8 Gas downstream from the rotary kiln (kiln inlet)
trG6,V& can be calculated according to [30]. Due to non-representative gas analyses in the
kiln inlet, the calculated values are often very imprecise.
May 1992 Specification Vt 10 Page 51
4.1.2.2 Water vapor
4.1.2.2.1 Humidity in the air
The humidity in the air results from the relative humidity and from the saturation pressure
of water-vapor at ambient temperature. The following applies:
wherein
xD = water content in kg of H2O/kg of dry air
ϕ = relative humidity
ps (ϑ L,U) = saturation pressure of the water vapor in Pa
p = ambient pressure in Pa
and
Then, the following applies for the moisture volume flow of the air:
4.1.2.2.2 Water from the kiln feed
May 1992 Specification Vt 10 Page 52
4.1.2.2.3 Water from the fuel
4.1.2.2.4 Injection water
4.1.2.3 Moist gas
4.1.2.3.1 Air
The following applies in general:
Altogether,
is fed into the kiln system. λ G1 should be calculated with the gas concentration values
which would result after the mixing of raw gas and bypass gas.
May 1992 Specification Vt 10 Page 53
4.1.2.3.2 Raw gas
λ G1 should be calculated with the gas concentration values which would result after the
mixing of raw gas and bypass gas. With grate-type coolers, O,10H 2V& often equals zero.
G5O,H 2y often equals G6O,H 2
y .
4.1.3 Liquid mass flows
Measured quantities: fuel (main burner), fuel (secondary burner), water.
4.1.4 Energy flows
Since standard reaction enthalpies and calorific values are related to 25°C [77°F], a refer-
ence temperature of 25°C [77°F] was likewise selected for the calculation of the individ-
ual enthalpy flows.
4.1.4.1 Energy input
4.1.4.1.1 Fuel
Combustion:
May 1992 Specification Vt 10 Page 54
Sensible enthalpy flows: *)
For dry coal, the following applies (also see Figure 7):
wherein xF,B = sum of the volatile components in the coal.
Equation (43) also applies, as an approximation, to dry lignitic coal. Here, however, the
water content of the lignitic coal has to be taken into account. The following then applies:
wherein OH 2c ≈ 4.2 kJ/kg K for 0°C [32°F] < ϑ < 100°C [212°F].
The following applies in the case of oil (also see Figure 8):
wherein ρ = density of the oil in kg/m³ at 15°C [59°F].
*) The formula sign c or cp below stands for the mean specific thermal capacity
ϑF][77 C25pc °° .
May 1992 Specification Vt 10 Page 55
Figure 7 - Mean specific thermal capacity of dry coal (reference temperature = 25°C [77°F]).
May 1992 Specification Vt 10 Page 56
Figure 8 - Mean specific thermal capacity of oil (reference temperature = 25°C [77°F]).
May 1992 Specification Vt 10 Page 57
The specific thermal capacity of the heating gas is calculated on the basis of the mean
specific thermal capacities of the individual gas components according to Table 7. The
following applies here:
Table 7 - Mean specific thermal capacity cp of the fuel gas compo-
nents (reference temperature = 25°C [77°F]).
Specific thermal capacity cp in kJ/m³ (s.c.) K
Fuel gas component
25°C [77°F] 100°C [212°F] 200°C [392°F] methane
CH4
1.582
1.700
1.817
ethylene C2H4 2.270 2.402 2.519
acetylene C2H2 1.985 2.137 2.246
propadiene C3H4 2.631 2.918 3.172
n-butane C4H10 4.579 5.156 5.717
propylene 1) C3H6 4.101 4.555 5.113
hydrogen sulfide H2S 1.531 1.579 1.602
1) Use C3H6 use for CmHn.
s.c. = under standard conditions
4.1.4.1.2 Kiln feed
Sensible enthalpy flows:
May 1992 Specification Vt 10 Page 58
The following applies as an approximation for the commonly employed composition of
the kiln feed:
The specific thermal capacities of individual components of the kiln feed are shown in
Figure 9.
May 1992 Specification Vt 10 Page 59
Figure 9 - Mean specific thermal capacity of kiln feed components
(reference temperature = 25°C [77°F]).
May 1992 Specification Vt 10 Page 60
4.1.4.1.3 Air
Sensible enthalpy flows:
wherein
(For the calculation of cp, j according to Equations (85) through (87), also see Figure 10).
As an approximation, it is also possible to use the specific thermal capacity of dry air for
the calculation. The following applies in this case:
May 1992 Specification Vt 10 Page 61
Figure 10 - Mean specific thermal capacity of gas components (ref-
erence temperature = 25°C [77°F]).
May 1992 Specification Vt 10 Page 62
4.1.4.1.4 Injection water
As a rule, the sensible enthalpy flow of the injection water can be ignored.
4.1.4.1.5 Mechanical performance
Within the balancing space, the mechanical performance of the electric drives has to be
taken into consideration. This is particularly true of the intake air fans and of the kiln
drive. In simplified form, the following applies:
4.1.4.2 Energy output
4.1.4.2.1 Reaction enthalpy of the kiln feed
For the calculation of the reaction enthalpy of the kiln feed, the degradation reactions of
the starting materials and the reactions for the formation of the clinker phases have to be
taken into account. Table 8 is a compilation of the main reactions that take place during
the clinker burning process, with the standard reaction enthalpies needed in each case (for
the additional reaction enthalpies, see [22, 23 and 25 through 27]). The data shown in the
two right-hand columns are each related to the substance in the left-hand column. The
actual reaction enthalpies to be employed result from balance equations. For this purpose,
it is first necessary to calculate the contents of C3S, C2S, C3A, C4AF in the clinker, the
contents of CaCO3 and MgCO3 in the kiln feed and in the raw gas dust as well as the
contents of CaCO3 and C2S in the bypass dust.
May 1992 Specification Vt 10 Page 63
Table 8 - Reactions of the kiln feed and reaction enthalpies (298 K)
during the production of Portland cement clinker.
Reaction
Reaction equation
Reaction enthalpy 1)
at 298 K
kJ/kg kJ/mole
I. Formation of oxides and
degradation reactions
1. Evaporation of H2O H2O (fl) � H2O (g) + 2446 + 44
2. Decomposition of
• kaolinite (relative to Al2O3)
kaolinite � α-Al2O3 + 2 · β-SiO2 + H2O (fl)
+ 1519 + 155
• montmorillonite (relative to Al2O3)
montmorillonite � α-Al2O3 + 4 · β-SiO2 + n · H2O (fl)
+ 744 + 76
• illite (relative to Al2O3)
illite � α-Al2O3 + 4 · β-SiO2 + m · H2O (fl)
+ 884 + 90
3. Organic clay components (relative to C)
C + O2 � CO2 – 32786 – 394
4. MgCO3 dissociation MgCO3 � MgO + CO2 + 1396 +118
5. CaCO3 dissociation CaCO3 � CaO + CO2 + 1772 + 178
6. Pyrite (FeS2) 2 FeS2 + 5½ O2 � α-Fe2O3 + 4 SO2 – 6902 – 828
II. Formation of the clinker phases
7. Formation of C4AF 4 CaO + α-Al2O3 + α-Fe2O3 � C4AF – 67 – 33
8. Formation of C3A 3 CaO + α-Al2O3 � C3A + 74 + 20
9. Formation of β-C2S 2 CaO + β-SiO2 � β-C2S – 700 – 121
10. Formation of C3S 3 CaO + β-SiO2 � C3S – 495 – 113
11. Formation of K2SO4 K2O = SO2 + ½ O2 � α-K2SO4 – 4452 – 776
1) Related to the substance in the left-hand column.
May 1992 Specification Vt 10 Page 64
4.1.4.2.1.1 C3S, C2S, C3A and C4AF in the clinker
For normal Portland cement clinker or tertiary air dust, which consists primarily of C3S,
C2S, C3A and C4AF (TM > 0.64), the clinker phases can be calculated according to
Bogue [45 and 46]. In this context, the value employed for the CaO bound in the clinker
phases is the one that is obtained after the subtraction of the free CaO and of the CaO
bound to SO3. The following applies:
For S10 O,NaS10 O,KS10 ,SO 223x292.1x85.0x ⋅+⋅≤ , the following applies:
For S10 O,NaS10 O,KS10 ,SO 223x292.1x85.0x ⋅+⋅> , the following applies:
The following results from this:
May 1992 Specification Vt 10 Page 65
4.1.4.2.1.2 CaCO3 and MgCO3 in the kiln feed and in the raw gas dust
The content of CaCO3 and MgCO3 of the kiln feed results from the content of CO2 and
CaO. Assuming that the CO2 is primarily bound to the CaO, the following applies in the
case of
1.274 · CaOCO xx2
≤ :
and
in the case of
1.274 · CaOCO xx2
> :
and
May 1992 Specification Vt 10 Page 66
4.1.4.2.1.3 CaCO3 and C2S in the bypass dust
The content of CaCO3 results from the content of CO2 in the bypass dust.
For purposes of calculating the C2S content, it is assumed that Al2O3 and Fe2O3 have
completely reacted with CaO to form C4AF and C12A7. The following then applies:
The calculation of St5,CaO 3SOx is made according to Equations (55) or (56).
4.1.4.2.1.4 Balance equations
The balance equations are based on the following assumptions and simplifications:
1) 0x St5 O,H 2=
2) xC, St5 = 0
3) 0x St5 ,MgCO3=
4) xS, St5 = 0
5) The formation enthalpy of C4AF and of C12A7 in the bypass dust is negligibly small.
6) The starting materials as shown in Table 8 are present.
7) The fuel ash is present in the form of oxides.
May 1992 Specification Vt 10 Page 67
According to Figure 6, the following applies for the balance equations:
1) Evaporation of H2O:
2) Decomposition of clay:
100%-kaolinite:
100%-montmorillonite:
100%-illite:
3) Organic clay components:
May 1992 Specification Vt 10 Page 68
4) MgCO3 dissociation:
5) CaCO3 dissociation:
6) Pyrite:
7) Formation of C4AF:
8) Formation of C3A:
May 1992 Specification Vt 10 Page 69
9) Formation of β-CsS:
10) Formation of C3S:
11) Formation of K2SO4:
In Equation (79), the actual SO3 contents (without sulfide sulfur) should be used.
In order to calculate the reaction enthalpy of a special clinker, for instance, TM < 0.64, or
of a clinker from a kiln feed with calcareous fly ash, blast-burner slag or gypsum from
flue gas desulfurization plants, or of a clinker from a burning process involving other
substance flow configurations, the balance equations need to be changed or supple-
mented. Moreover, in the case of fly ash and blast-burner slag, assumptions also have to
be made pertaining to the devitrification enthalpies.
May 1992 Specification Vt 10 Page 70
The following applies to the sum of the reaction enthalpies of the kiln feed:
4.1.4.2.2 Water evaporation
Evaporation enthalpy for cooler injection water:
4.1.4.2.3 Waste gas losses
Raw gas:
wherein
The following approximation equations apply for the essential components of the waste
gas (also see Figure 10):
May 1992 Specification Vt 10 Page 71
Bypass gas:
Cooler vent air:
4.1.4.2.4 Dust losses
Raw gas dust:
(for cSt1, see Section 4.1.4.1.2; ϑ St1 = ϑ G1).
May 1992 Specification Vt 10 Page 72
Bypass gas dust:
(for cSt5, see Section 4.1.4.1.2; ϑ St5 = ϑ G5).
Discharged tertiary air dust:
(for cSt12, see Equation (95); ϑ St12 = ϑ L9).
Losses due to cooler vent air dust are usually negligibly small.
4.1.4.2.5 Incomplete combustion
In cases of high energy losses due to incomplete combustion (for example, yCO,G1 > 0.01),
an analyzer that operates continuously should be used for the calorific value of the gas for
the balancing.
4.1.4.2.6 Clinker
May 1992 Specification Vt 10 Page 73
The following applies for the specific thermal capacity of the clinker (also see Figure 11):
Figure 11 - Mean specific thermal capacity of Portland cement
clinker (reference temperature = 25°C [77°F]).
May 1992 Specification Vt 10 Page 74
4.1.4.2.7 Radiation and convection
Rotary kiln:
First of all, the heat flow of individual tube elements is calculated on the basis of the
mean circumferential temperature ϑ W,m of the tube element and of the ambient tempera-
ture ϑ L,U:
wherein
and
αconv results from approximation equations. The following applies for wind velocities
w ≤ 2 m/s:
wherein
a = 0.3
a0 = 4.0
May 1992 Specification Vt 10 Page 75
a1 = 3.5
a2 = -0.85
a3 = 0.076
Scope of validity:
w ≤ 2 m/s
100°C [212°F] ≤ ϑ W,m ≤ 500°C [932°F]
2 m ≤ Da ≤ 8 m
10°C [50°F] ≤ ϑ L,U ≤ 30°C [86°F]
The following applies for wind velocities w > 2 m/s:
wherein
Diameter range in m
b
b0
b1
*1b
2.75 ≤ Da < 3.25 2.37 4.98 0.73 - 0.244
3.25 3.75 2.27 5.05 0.79 - 0.243
3.75 4.25 2.18 5.11 0.83 - 0.238
4.25 4.75 2.11 5.19 0.88 - 0.236
4.75 5.25 2.05 5.27 0.92 - 0.233
5.25 5.75 1.98 5.40 0.93 - 0.227
5.75 6.25 1.93 5.48 0.97 - 0.227
6.25 6.75 1.87 5.66 0.97 - 0.220
6.75 7.25 1.83 5.70 1.00 - 0.219
May 1992 Specification Vt 10 Page 76
Scope of validity:
2 m/s < w ≤ 10 m/s
100°C [212°F] ≤ ϑ W,m ≤ 500°C [932°F]
2.75 m ≤ Da ≤ 7.25 m
10°C [50°F] ≤ ϑ L,U ≤ 30°C [86°F]
The following applies for αStr:
wherein
ε W = 0.9
σ = 5.67 · 10 –
8 W/(m² · K4)
TW,m = mean surface temperature in K
TL,U = ambient air temperature in K
The radiation and convection loss flow DW,Q& for the entire rotary kiln results from the
addition of the radiation and convection loss flows of the individual tube elements:
More details on the calculation of the radiation and convection loss flow can be found in
literature references [28 and 31].
May 1992 Specification Vt 10 Page 77
Cooler:
Equations (96) through (101) can be employed directly for the rotary cooler. For satellite
coolers, it is recommended to employ the imaginary surface area of a cylinder surround-
ing the satellite cooler as the heat-transfer surface area. The diameter of this surrounding
cylinder can then be used to calculate the heat-transfer coefficient αtotal as an approxima-
tion according to Equations (98) through (101). The mean circumferential temperature ϑ
W,m is calculated as an arithmetic mean value of all of the individual temperature meas-
ured values calculated over the circumference, that is to say, the satellite temperatures as
well as the temperatures in the interstitial spaces. Moreover, an empirical factor of 1.6
should be used for the calculation of the heat flow. The following applies:
The following applies as a good approximation for the grate-type cooler and the kiln
hood:
wherein
αconv = 7 W/(m²·K)
ε W = 0.9
At higher wind velocities, Equation (104) yields a heat loss flow that is too low. In such
cases, the surface temperature should be measured only on the side facing away the wind.
May 1992 Specification Vt 10 Page 78
Preheater and calcinator:
Equations (104) should be employed accordingly.
Tertiary air duct:
Equations (96) through (102) should be employed accordingly.
4.1.4.2.8 Uncoupled heat
The following applies as an approximation for the heat uncoupling via a cooling chute:
wherein
OH2c ≈ 4.2 kJ/kg K for 0°C [32°F] < ϑ < 100°C [212°F].
The following applies for the heat uncoupling through the cooling of the cooler circula-
tion air:
May 1992 Specification Vt 10 Page 79
4.1.4.3 Energy balance
The following applies for the sum of the energy input and energy output:
and
With kiln performance tests, the energy input and the energy output are compared to each
other. Usually the input and the output do not offset each other completely, so that a bal-
ance deficit remains which, however, should not make up more than ± 3% of the total
energy output.
Since the reaction enthalpy flow of the fuel as energy input can often only be determined
very imprecisely, it should be calculated on the basis of the difference between the
energy output and the other energy input values according to Equation (109); it is also
designated as fuel energy consumption.
May 1992 Specification Vt 10 Page 80
4.2 Balancing of the partial systems
4.2.1 Clinker cooler
A complete mass and energy balance can only be drawn up for the clinker cooler within
the limits set by its design. For this reason, the fact that considerable dust circulation can
occur between the rotary kiln and the clinker cooler has to be taken into account. More-
over, the hot clinker temperature can only be measured in a very imprecise manner.
Figure 12 - Balancing space of the cooler with the incoming and
outgoing mass and energy flows.
May 1992 Specification Vt 10 Page 81
Figure 12 shows the balancing space of a clinker cooler with the mass and energy flows
that exceed the balance limit. Thus, for example, several exhaust air flows can be dis-
charged from the cooler. In the case of rotary and satellite coolers, the exhaust air volume
flow, in contrast, has to be set as zero. The following mass and energy flows have been
taken into consideration:
Incoming solid substance mass flows:
S8m& for the hot clinker
Outgoing solid substance mass flows:
S10m& for the clinker
St8m& for the secondary air dust
St9m& for the tertiary air dust
Incoming gas volume flows:
L10V& for the cooler intake air
Outgoing gas volume flows
L8V& for the secondary air
L9V& for the tertiary air (cooler)
L11V& for the cooler vent air
Incoming liquid mass flows:
10 O,H 2m& for the cooler injection water
May 1992 Specification Vt 10 Page 82
Incoming energy flows:
S8H& for the hot clinker
L10H& for the cooler intake air
10 O,H2H& for the cooler injection water
Kmech,P for the mechanical performance (cooler)
Outgoing energy flows:
S10H& for the clinker
St8H& for the secondary air dust
St9H& for the tertiary air dust
L8H& for the secondary air
L9H& for the tertiary air
L11H& for the cooler vent air
KW,Q& for radiation and convection losses (cooler + kiln hood)
KK,Q& for the uncoupled heat (cooler)
O HV, 2H&∆ for the evaporation enthalpy of the cooler injection water
May 1992 Specification Vt 10 Page 83
4.2.1.1 Solid substance mass flows
Measured quantities: clinker, discharged and returned tertiary air dust.
Operands: secondary air dust, hot clinker.
Only in the case of kiln systems with a tertiary air duct can the secondary air dust mass
flow be calculated on the basis of the discharged and returned tertiary air dust assuming
equal dust contents in the secondary air and in the tertiary air. The secondary air dust
mass flow then results from the dust mass flow measured in the tertiary air and from the
fraction calculated on this basis for the secondary air volume flow:
In other cases, the dust concentration in the secondary air should be estimated. With a
“clear” kiln discharge, the dust concentration is about 30 to 50 g/m³. In the case of a pro-
nounced dust circulation, this value can rise to more than 200 g/m³.
The following applies for the hot clinker mass flow:
May 1992 Specification Vt 10 Page 84
4.2.1.2 Gas volume flows
Measured quantities: cooler vent air (if present), tertiary air.
Operands: cooler intake air, secondary air.
The secondary air volume flow results from Equations (20) and (38), and the cooler
intake air volume flow results from Equations (21) and (38). The water vapor from the
water injection should also be taken into account.
4.2.1.3 Energy flows
A reference temperature of 25°C [77°F] is selected for the calculation of the individual
energy flows.
4.2.1.3.1 Energy input
4.2.1.3.1.1 Hot clinker
(cS8 according to Equation (95) or Figure 11).
May 1992 Specification Vt 10 Page 85
Only the surface temperature of the hot clinker can be measured by means of instruments.
Therefore, the calculated hot clinker energy flow is fundamentally too low. This error
increases as the temperature drops and the particle size increases. Therefore, the hot
clinker energy flow is associated with a high level of uncertainty.
4.2.1.3.1.2 Cooler intake air
4.2.1.3.1.3 Injection water
See Section 4.1.4.1.4.
4.2.1.3.1.4 Mechanical performance
4.2.1.3.2 Energy output
4.2.1.3.2.1 Clinker, clinker dust
See Section 4.1.4.2.6.
May 1992 Specification Vt 10 Page 86
4.2.1.3.2.2 Radiation and convection
See Section 4.1.4.2.7.
4.2.1.3.2.3 Uncoupled heat
See Section 4.1.4.2.8.
4.2.1.3.2.4 Cooler vent air, secondary air, tertiary air
See Section 4.1.4.2.3.
4.2.1.3.2.5 Water evaporation
See Section 4.1.4.2.2.
4.2.1.3.3 Energy balance
If a reliable measured value for the secondary air temperature is available, the hot clinker
enthalpy flow S8H& can be calculated on the basis of the energy balance. As a rule, this is
the case whenever tertiary air is removed from the kiln hood (ϑ L9 = ϑ L8) or when the
secondary air can be measured error-free (for example, with sound-over-time measure-
ment or a suction-type thermometer). The following then applies:
May 1992 Specification Vt 10 Page 87
The hot clinker enthalpy flow calculated according to this equation serves as the basis for
the calculation of the cooler efficiency (see Section 4.2.1.4.4).
4.2.1.4 Evaluation quantities
4.2.1.4.1 Pre-cooling zone
For the evaluation of the clinker cooler, it is necessary to take into account the fact that
the first cooling of the clinker already takes place inside the rotary kiln, in the so-called
pre-cooling zone, which is where radiation and convection losses occur. Figure 13 shows
the principle of the balance limits of the burning area and of the cooling area and its sub-
division into the pre-cooling zone and the cooler.
Figure 13 - Balance limits of the burning area and cooling area, of
the pre-cooling zone as well as of the cooler with the
example of a kiln system with a rotary cooler.
May 1992 Specification Vt 10 Page 88
In order to calculate the radiation and convection losses in the pre-cooling zone, it is nec-
essary to know their length Lpre-cool. Since this length cannot be measured and no calcula-
tion method is known for this at the present time, the position of the burner lance serves
as the reference point for estimating this length (also see Figure 13).:
wherein
Lpre-cool = length of the pre-cooling zone, in m
Lburner = length of the burner in the rotating part of the kiln, in m
Da = outer diameter of the rotary kiln, in m
The estimation according to Equation (116) diverges from that described in the VDZ
Specification titled “Grate-type, satellite and rotary coolers in the cement industry” [33].
It was selected because of the high degree of measuring uncertainty associated with the
determination of the hot clinker temperature.
The radiation and convection loss coolpreW,Q −& in the pre-cooling zone of the rotary kiln
amounts to the following:
Here, αtotal stands for the mean heat-transfer coefficient, which can be calculated accord-
ing to Equations (98) through (101) with a superimposition of the radiation (rad) as well
as free and forced convection (conv).
May 1992 Specification Vt 10 Page 89
4.2.1.4.2 Energy loss flow of the cooling area
The energy consumption of a rotary kiln system depends to a decisive degree on the
extent to which the enthalpy of the clinker in the cooling area can be recovered for the
process. The fraction that is not recovered constitutes the energy loss of the cooling area,
which has to be replaced by fuel energy.
The energy loss flow areacoolingloss,E& is the sum of the heat and enthalpy flows that are
released by the cooler into the atmosphere. In this context, for the clinker and cooler vent
air, those enthalpy flows that would be released during the cooling procedure from the
appertaining outlet temperature to the ambient air temperature should be seen as energy
flows,
In this equation, h(ϑ L,U) stands for the specific enthalpy at the ambient air temperature.
4.2.1.4.3 Cooling area efficiency
For comparisons, it is advantageous to relate the energy loss flow of the cooling area to a
theoretical enthalpy flow change on the part of the clinker and thus to define a cooling
area efficiency:
May 1992 Specification Vt 10 Page 90
For the sake of harmonization, a sintering temperature of 1450°C [2642°F] was presup-
posed, which should prevail at the site of transition from the burning area to the cooling
area. Future improvements of the burning process or special compositions of the kiln feed
could make it necessary to stipulate a sintering temperature that differs from this.
The cooling area efficiency makes it possible to thermally evaluate the cooling in the
entire process.
4.2.1.4.4 Cooler efficiency
The efficiency values of the cooler are described in the VDZ Specification titled “Grate-
type, satellite and rotary coolers in the cement industry” [33]. The limitations outlined in
Section 4.2.1.3.1.1 apply when using the formulas.
4.2.2 Calcinator (only for kiln system with cyclone preheater)
The balancing space of the calcinator starts at the rotary kiln inlet and ends downstream
from the lowermost cyclone (Figure 14). The lowermost stage of the cyclone preheater
counts as part of the calcinator. With degrees of precalcining below approximately 90%,
the equilibrium temperature of the calcium carbonate dissociation sets in at the lowermost
stage, irrespective of the burning or pre-heating conditions. Thus, at this site, the waste
gas acquires a chemically determined temperature that is very well-suited for determining
this balance limit. In contrast, this does not apply for the “rotary kiln inlet” balance limit
where the energy and mass flows can only be determined very imprecisely. For this rea-
son, the calcinator is often balanced together with the rotary kiln, since it is in these
aggregates that the essential reactions of the kiln feed and of the fuel take place.
May 1992 Specification Vt 10 Page 91
Figure 14 - Balancing space of the calcinator with incoming and
outgoing mass and energy flows.
May 1992 Specification Vt 10 Page 92
4.2.2.1 Determination of the degree of precalcining
The degree of precalcining can be used to evaluate the progress of the decarbonation of
the kiln feed in the preheater and in the calcinator. In this context, the degree of precal-
cining refers to the degree of dissociation of the calcium carbonate contained in the kiln
feed prior to its entry into the rotary kiln. The actual degree of precalcining ϕ actual is
defined according to Equation (120) as the ratio of the carbon dioxide mass flow
VCCO ,2m& that has escaped from the kiln feed in the preheater and in the calcinator to the
carbon dioxide mass flow 0CO ,2m& that was originally bound in the kiln feed as carbonate:
The degree of precalcining calculated according to Equation (120) can only be deter-
mined by using complete gas or solid substance balances. More details on this can be
found in literature reference [30].
As a simplification, the degree of precalcining can also be determined on the basis of the
solid substance analyses. It is designated as the apparent degree of precalcining ϕ apparent.
Provided that the raw gas dust St1m& has the same chemical composition as the kiln feed
S1m& , and by ignoring the dust in the rotary kiln inlet gas, the apparent degree of precal-
cining ϕ apparent results from the CO2 concentrations 2COx and the concentrations of non-
volatile components xNF of the kiln feed (index S1) and of the kiln feed at the kiln inlet
(index S6):
May 1992 Specification Vt 10 Page 93
In reality, however, the more highly decarbonated dust St4m& and St6m& influences the
composition of the kiln feed mass flow S6m& . For this reason, the apparent degree of pre-
calcining ϕ apparent calculated according to Equation (121) generally simulates a higher
decarbonation of the kiln feed. If the dust mass flows St4m& and St6m& have been com-
pletely decarbonated, the following relationship exists between the apparent and the
actual degree of precalcining:
4.2.3 Preheater (only for kiln system with cyclone preheater)
Figure 15 shows the balancing space of the preheater. As a rule, it consists of 3 to 5 pre-
heating stages in which gas and the kiln feed are fed in a countercurrent with respect to
each other. The degrees of separation of the individual cyclone stages are relevant for an
evaluation of the preheater.
May 1992 Specification Vt 10 Page 94
Figure 15 - Balancing space of the preheater with incoming and
outgoing mass and energy flows.
4.2.3.1 Degree of separation of individual cyclone stages
Figure 16 shows the incoming and outgoing solid substance mass flows of a preheating
stage. According to it, the following applies for the degree of separation:
May 1992 Specification Vt 10 Page 95
The mass flows iS,m& and 1iSt,m +& result from the mass and energy balance of the ith stage.
The following applies as an approximation for the solid substance balance:
The following applies for the energy balance:
In this context, iW,Q& stands for the radiation and convection loss flow of the ith cyclone
stage and iR,H&∆ stands for the reaction enthalpy flow of the raw material in stage i.
Equations (124) and (125) yield the mass flows iS,m& and 1iSt,m +& :
Equations (126) and (127) can be employed in the area of the preheater where hardly any
solid/gas reactions (decarbonation) occur. As a rule, this is the case with the uppermost
cyclone stages (ϑ < 600°C [1112°F]). In this context, it is assumed that there is tempera-
ture equilibrium between the gas and the kiln feed in the cyclone stage.
May 1992 Specification Vt 10 Page 96
Figure 16 - Incoming and outgoing solid substance mass flows of a
preheating stage with a cyclone separator.
If the alkali compounds in the kiln feed differ sufficiently, the mass flows can also be
ascertained on the basis of component balances. This generally applies to the lower stages
of the preheater, but also to the cyclone separator of the calcinator. If effNF,m& stands for
the mass flow of non-volatile substances effectively fed into the kiln system,
and if effalk,m& stands for the mass flow of alkali compounds that are effectively fed into
the system by means of the kiln feed,
then, provided that the dust and solid substance mass flows exiting from each individual
stage have the same chemical composition, it is possible to determine the mass flows of
the kiln feed and the dust between the individual cyclone stages:
May 1992 Specification Vt 10 Page 97
From a technical standpoint, xNF, N+1 and xalk, N+1 (N= cyclone separator of the calcinator)
are very difficult to measure, as a result of which, for purposes of simplification, both
concentration values should be pre-defined.
Equations (126) and (127) as well as (130) and (131) constitute very rough approxima-
tions, as a consequence of which only changes in these operands, for example, between
two performance tests, should be interpreted, but not the absolute value.
May 1992 Specification Vt 10 Page 98
5. Evaluation of the substance circulation systems
Relevant substance circulation systems should be measured during a kiln performance
test or else calculated on the basis of measured and analytical data.
May 1992 Specification Vt 10 Page 99
6. Evaluation of the cement clinker
As a rule, new systems are only examined once the clinker properties and thus also the
cement properties have been achieving the desired quality requirements for quite some
time. In contrast, kiln performance tests with old systems can also serve to optimize the
quality of the cement and clinker.
6.1 Degree of burning
The degree of burning of the cement clinker is usually monitored on the basis of the bulk
density (weight per unit volume) of a narrow particle range, for instance, 5 to 7 mm,
whose values lie between 1.2 and 1.6 kg/dm³. The bulk density, however, is not only
dependent on the degree of burning, but also on the chemical composition and on the
porosity of the clinker. Moreover, the content of free CaO also provides information
about the degree of burning.
6.2 Particle-size distribution
The coarse and fines fractions of the clinker (for example, < 2 mm and > 25 mm) provide
information about the kiln operation and the clinker quality. They are ascertained by
means of sieve analysis.
May 1992 Specification Vt 10 Page 100
6.3 Grindability
The grindability of the clinker provides information about the necessary work in the
cement mill. It is primarily tested with the device according to Zeisel.
6.4 Chemical composition
The chemical composition yields the lime standard (KSt), the silica ratio (SM), the
alumina/iron ratio (TM), the sulfatization degree (SG), the total alkali fraction (A) and
the melt phase fraction (S).
The lime standard indicates the content of CaO actually present in the raw material mix-
ture or clinker as a percentage of the maximum CaO content that can be bound to SiO2,
Al2O3 and Fe2O3 under industrial burning and cooling conditions.
Several formulas, which do not differ markedly from each other, are commonly
employed to calculate the lime standard. According to F.M. Lea and T.W. Parker, for
example, the following applies [7]:
May 1992 Specification Vt 10 Page 101
The silica modulus is the ratio of silicon dioxide to the sum of aluminum oxide and iron
oxide. The following applies:
Since the silicon dioxide is primarily bound in the solid phases tricalcium silicate and di-
calcium silicate at the sintering temperature, but since aluminum oxide and iron oxide are
present in the melt, the silica modulus refers to the solid-to-liquid ratio in the sintering
zone of the cement kiln. Generally speaking, the silica modulus lies between SM = 1.8
and SM = 3.0, most frequently and most advantageously between SM = 2.3 and SM =
2.8.
The alumina/iron ratio (TM) is the ratio of the aluminum oxide content to the iron oxide
content. The following applies:
It provides information about the quantity ratio of calcium aluminate to calcium alumi-
nate ferrite and consequently about the clinker melt. With clinker having a commonly
employed composition, this value lies between 1.5 and 4.0. With an alumina/iron ratio of
0.638, the calculation indicates that all of the aluminum oxide contained in the clinker is
bound as calcium aluminate ferrite having the assumed composition
4 CaO · Al2O3 · Fe2O3.
May 1992 Specification Vt 10 Page 102
The sulfatization degree (SG) indicates the percentage of alkalis in the clinker, which are
present as alkali sulfate:
The total alkali fraction (A) results from the conversion of the fraction of potassium
oxide into the equivalent sodium fraction according to the following equation:
The following applies as an approximation for the melt phase (S):
(for ϑ S = 1338°C [2440.4°F] and TM > 1.38).
(for ϑ S = 1338°C [2440.4°F] and TM < 1.38).
(for ϑ S = 1400°C [2552°F]).
(for ϑ S = 1450°C [2642°F]).
May 1992 Specification Vt 10 Page 103
xMgO enters into the formulas with xMgO = 0.02 at the maximum; at higher contents,
xMgO = 0.02.
6.5 Phase composition
The phase composition of the clinker can be calculated on the basis of the values of the
chemical analysis, for instance, according to equations (54) through (60). However, it is
necessary to assume that the clinker phases have the composition indicated by their for-
mulas and that the clinker melt is in a continuous state of thermodynamic equilibrium
with the solid phases of the clinker, not only at the sintering temperature but also and
especially when they crystallize during the cooling procedure. For these reasons, the cal-
culation only provides an approximation of the actual clinker composition [7].
6.6 Microscopic examination
The microscopic examination of the clinker provides information about the type, consti-
tution and distribution of the clinker compounds. Whereas the type of the compounds
depends primarily on the chemical composition of the kiln feed, the structure, that is to
say, the constitution and distribution of the clinker compounds and their coalescence,
provide information about the preparation of the raw material mixture and about the con-
ditions during the burning and cooling of the clinker.
May 1992 Specification Vt 10 Page 104
6.7 Cement testing
The results of the quality tests with the ground-up cement types within the scope of our
own as well as outside monitoring also provide essential information about the properties
of the cement clinker. They are of decisive significance for the optimization of opera-
tions.
May 1992 Specification Vt 10 Page 105
7. Evaluation of the emissions
Relevant emissions have to be measured and/or recorded during a kiln performance test.
May 1992 Specification Vt 10 Page 106
8. Formula signs and indices
Roman letters
a factor (Section 4.1.4.2.7)
A total alkali fraction in kg/kg
b factor (Section 4.1.4.2.7)
c mean specific thermal capacity of solids and liquids in kJ/kg K
cp mean specific thermal capacity of gases in kJ/m³ under standard condi-
tions (s.c.) K
D diameter in m
E& energy flow in kJ/s
f ratio of kiln feed to clinker in kg/kg of clinker
F surface area in m²
hu lower calorific value in kJ/kg
h specific enthalpy in kJ/s
H& sensible enthalpy flow in kJ/s
RH&∆ reaction enthalpy flow in kJ/s
VH&∆ evaporation enthalpy flow in kJ/s
KSt lime standard in %
L length in m
lmin minimum air demand in m³ of air (s.c.) / kg of fuel
m& mass flow in kg/s
M molecular weight in kg/mole
N stage number in the cyclone preheater, chamber number in the grate-type
cooler
p pressure in Pa
May 1992 Specification Vt 10 Page 107
P performance in kJ/s
Q& heat flow in kJ/s
S melt phase content
SG sulfatization degree in %
SM silica modulus
T absolute temperature in K
TM alumina/iron ratio
v gas velocity in m/s
V& volume flow under standard conditions (0°C [32°F] and 1013 hPa) in m³/s
w wind velocity in m/s
x mass concentration in kg/kg
y volume concentration in m³/m³
Greek letters
α heat transition coefficient in W/m² · K
∆ difference
εW emission ratio of the wall surface
η cooling area cooling area efficiency
ϑ temperature in °C
λ excess air coefficient
µ combustion product per energy unit in m³ (s.c.) / kJ
ξ degree of separation of a cyclone
ρ density in kg/m³
σ Stefan-Boltzmann constant
σ = 5.67 · 10 –
8
42Km
W
ϕ degree of precalcining, relative humidity
May 1992 Specification Vt 10 Page 108
Indices
0 initial state
0 through 11 reactions of the kiln feed (Section 4.1.4.2.1.4)
0 through 12 balance limits
1 preheater (kiln feed, raw gas)
2 preheater / calcinator
3 calcinator (secondary burner)
4 calcinator (tertiary air duct)
5 calcinator (bypass)
6 calcinator / rotary kiln
7 rotary kiln (main burner)
8 rotary kiln / cooler
9 tertiary air duct / cooler
10 cooler (clinker, cooler intake air)
11 cooler (cooler vent air)
12 tertiary air duct (discharged tertiary air dust)
a outside
Alk alkali compounds
out balance output
Out outlet
B fuel
burner burner
C calcinator, carbon
D rotary kiln, vapor under standard conditions (0°C [32°F] and 1013 hPA)
eff effective
in balance input
In inlet
May 1992 Specification Vt 10 Page 109
F sum of the volatile substances
Fl infiltrated air
total total
G gas, loss on ignition
surr surrounding cylinder
i variable
K cooler, uncoupled
Kl clinker
con convection
L air
m mean value
max maximum
mech mechanical
min minimum
N standard conditions (s.c.) (0°C [32°F] and 1013 hPA)
NV sum of non-volatile substances
p at constant pressure
R reaction
clean gas clean gas
grate grate-type cooler
s saturation
app apparent
S solid, sulfide sulfur
Sat satellite cooler
St dust
Str radiation (rad)
actual actual
theor theoretical
May 1992 Specification Vt 10 Page 110
tr dry
T tertiary air duct
U ambient
Um circulation air
V preheater, evaporation enthalpy
loss loss
pre-cool pre-cooling zone
W radiation and convection losses
Chemical formula signs
C3A tricalcium aluminate (3 CaCO · Al2O3)
C12A7 (12 CaO · 7Al2O3)
C4AF aluminate ferrite (4 CaO · Al2O3 · Fe2O3)
C2S dicalcium silicate (2 CaO · SiO2)
C3S tricalcium silicate (3 CaO · SiO2)
Al2O3 aluminum oxide
C carbon
CaCO3 calcium carbonate
CaO calcium oxide
Cl – chloride
CO carbon monoxide
CO2 carbon dioxide
Fe2O3 iron(III)-oxide
H hydrogen, atomic
H2O water
K2O potassium oxide
K2SO4 potassium sulfate
MgCO3 magnesium carbonate
May 1992 Specification Vt 10 Page 111
MgO magnesium oxide
Mn2O3 manganese(III)-oxide
N2 nitrogen
Na2O sodium oxide
O oxygen, atomic
O2 oxygen
P2O5 phosphorus pentoxide
S2– sulfide
SiO2 silicon dioxide
SO3 sulfur(VI)-oxide (sulfate)
TiO2 titanium dioxide
May 1992 Specification Vt 10 Page 112
9. Literature references
9.1 General literature references
[1] Kühl, H.: Zement-Chemie. Band 1. Die physikalisch-chemischen Grundlagen der
Zement-Chemie. VEB Verlag Technik, Berlin 1956. [2] Kühl, H.: Zement-Chemie. Band 11. Das Wesen und die Herstellung der hydrau-
lischen Bindemittel. VEB Verlag Technik, Berlin 1958. [3] Keil, F: Zement-Herstellung und Eigenschaften. Springer-Verlag, Berlin 1971. [4] Seidel, G., Huckauf, H., und Stark, J.: Technologie der Bindebaustoffe. Band 3.
Brennprozeß und Brennanlagen. VEB Verlag für Bauwesen, Berlin 1978. [5) Baehr, H.D.: Thermodynamik. Springer-Verlag, Berlin 1981. [6] Labahn, O.: Ratgeber für Zementingenieure. Bauverlag GmbH, Wiesbaden 1982. [7] Locher, F. W: Zement. Ullmanns Enzyklopädie der technischen Chemie, Band 24,
pp. 545-574, Verlag Chemie GmbH, Weinheim 1983. [8] Duda, W.H.: Cement-Data-Book. Band 1. Internationale Verfahrenstechniken der
Zementindustrie. Bauverlag GmbH, Wiesbaden 1985. [9] Stark, J., Huckauf, H., und Seidel, G.: Bindebaustoff-Taschenbuch. Band 3. Brenn-
prozeß und Brennanlagen. VEB Verlag Für Bauwesen, Berlin 1985. [10] Brandt, F: Brennstoffe und Verbrennungsrechnung. FDBR-Fachbuchreihe, Band 1.
Vulkan-Verlag, Essen 1991.
May 1992 Specification Vt 10 Page 113
9.2 Technical literature references
Description of the clinker burning process [11] Sprung, S.: Technologische Probleme beim Brennen des Zementklinkers, Ursache
und Lösung. Schriftenreihe der Zementindustrie, Vol. 43,1982. [12] Garrett, H.M.: Precalciners today - a review. Rock Products, July (1985) pp. 39-61. [13] Wolter, A.: Einfluß des Ofensystems auf die Klinkereigenschaften. Zement-Kalk-
Gips 38 (1985) Vol. 10, pp. 612-614. [14] Bonn, W., und Lang, Th.: Brennverfahren. Zement-Kalk-Gips 39 (1986) Vol. 3, pp.
105-114. [15] Rosemann, H.: Theoretische und betriebliche Untersuchungen zum Brennstoff-
energieverbrauch von Zementofenanlagen mit Vorcalcinierung. Schriftenreihe der Zementindustrie, Vol. 48,1987.
Execution of kiln performance tests [16] VDZ-Merkblatt “Mengenmessung von Gasen durch Geschwindigkeitsmessung”,
Verein Deutscher Zementwerke e.V., Düsseldorf 1961. [17] VDZ-Merkblatt “Staubmengenmessungen auf Zementwerken”, Verein Deutscher
Zementwerke e.V., Düsseldorf 1962. [18] Hengstenberg, J., Sturm, B., und Winkler, O.: Messen, Steuern und Regeln in der
Chemischen Technik. Band 1. Messung von Zustandsgrößen, Stoffmengen und Hilfsgrößen. Springer-Verlag, Berlin 1980.
[19] Hengstenberg, J., Sturm, B., und Winkler, O.: Messen, Steuern und Regeln in der
Chemischen Technik. Band 11. Messung von Stoffeigenschaften und Konzentra-tionen. Springer-Verlag, Berlin 1980.
[20] VDZ-Merkblatt “Kontinuierliche Gasanalyse in Zementwerken”, Verein Deutscher
Zementwerke e.V., Düsseldorf 1990.
May 1992 Specification Vt 10 Page 114
Evaluation of kiln performance tests [21] Schwiete, H.E.: Die spezifische Wärme des Portlandzementklinkers. Tonindustrie-
Zeitung 56 (1932) Nr. 22, pp. 304-306. [22] Schwiete, H.E., und Ziegler, G.: Beitrag zur Thermochemie von Zementrohstoffen.
Zement-Kalk-Gips 9 (1956) Vol. 6, pp. 257-262. [23] zur Strassen, H.: Der theoretische Wärmebedarf des Zementbrandes. Zement-Kalk-
Gips 10 (1957) Vol. 1, pp. 1-12. [24] VDZ-Merkblatt “Berechnungsunterlagen für Ofenversuche”, Verein Deutscher
Zementwerke e.V., Düsseldorf 1959. [25] Petrosjan, M.: Thermodynamik der Silikate, VEB Verlag für Bauwesen, Berlin
1966. [26] Barin, I., und Knacke, O.: Thermochemical properties of inorganic substances.
Springer-Verlag, Berlin 1973, [27] Barin, I., Knacke, O., und Kubaschewski, O.: Thermochemical properties of inor-
ganic substances. Supplement. Springer-Verlag, Berlin 1977. [28] Gardeik, H.O., Ludwig, H., und Steinbiß, E.: Berechnung des Wandwärmeverlustes
von Drehöfen und Mühlen. Teil 1: Grundlagen. Zement-Kalk-Gips 33 (1980) Vol. 2, pp. 53-62.
[29] VDI-Wärmeatlas, Berechnungsblätter für den Wärmeübergang, VDI-Verlag
GmbH, Düsseldorf 1983. [30] Rosemann, H., und Gardeik, H.O.: Rechnergesteuerte Meßdatenerfassung und -
verarbeitung bei der Durchführung von Ofenversuchen. Zement-Kalk-Gips 37 (1984) Vol. 9, pp. 465-473.
[31] Gardeik, H.O., und Ludwig, H.: Berechnung des Wandwärmeverlustes von Dreh-
öfen und Mühlen. Teil 2: Näherungsgleichungen und Anwendungen. Zement-Kalk-Gips 38 (1985) Vol. 3, pp. 144-149.
[32] Wolter, A.: Phase composition of calcined raw meal. Proc. 8th International Con-
gress on the Chemistry of Cement, Rio de Janeiro, 1986, pp. 89-94.
May 1992 Specification Vt 10 Page 115
[33] VDZ-Merkblatt “Rost-, Satelliten- und Rohrkühler in der Zementindustrie”, Verein Deutscher Zementwerke e.V., Düsseldorf, 1989,
Evaluation of the substance circulation systems [34] Weber, P.: Warmeübergang im Drehofen unter Berücksichtigung der Kreislauf-
vorgänge und der Phasenneubildung. Dissertation, Bergakademie Clausthal-Zellerfeld 1959, Zement-Kalk-Gips, Sonderausgabe Nr. 9 (1960).
[35] Goes, C.: Ober des Verhalten der Alkalien beim Zementbrennen. Schriftenreihe der
Zementindustrie, Vol. 4, 1960. [36] Weber, R: Alkaliprobleme und Beseitigung bei wärmesparenden Trockenöfen.
Zement-Kalk-Gips 17 (1964) Vol. 8, pp. 335-344. [37] Sprung, S.: Das Verhaften des Schwefels beim Brennen von Zementklinker
Schriftenreihe der Zementindustrie, Vol. 31, 1964. [381 Ritzmann, H.: Kreislaufe in Drehofensystemen. Zement-Kalk-Gips 24 (1971) Vol.
8, pp. 338-343. [39] Locher, F W, Sprung, S., und Opitz, D.: Reaktionen im Bereich der Ofengase.
Zement-Kalk-Gips 25 (1972) Vol. 1, pp. 1-12. [40] Locher, F. W: Stoffkreisläufe und Emissionen beim Brennen von Zementklinker.
Fortschritte der Mineralogie 60 (1982) Vol. 2, pp. 215-234. [41] Kreft, W: Methode zur Vorausberechnung von Schadstoffkreisläufen in Zement-
öfen. Zement-Kalk-Gips 35 (1982) Vol. 9, pp. 456-459. [42] Rosemann, H., und Gardeik, H.O.: Einflüsse auf die Energieumsetzung in Calci-
natoren bei der Vorcalcination von Zementrohmehl. Zement-Kalk-Gips 36 (1983) Vol. 9, pp. 509-511.
[43] Kreft, W: Alkali- und Schwefelverdampfung in Zementofen in Gegenwart hoher
Chloreinnahmen. Zement-Kalk-Gips 38 (1985) Vol. 8, pp. 418-422. [44] Schütte, R., und Kupper, D.: Die Bedeutung von Kreislaufbetrachtungen für Pro-
duktqualität und Umweltverträglichkeit der Zementherstellung. Zement-Kalk-Gips 43 (1990) Vol. 12, pp. 565-570.
May 1992 Specification Vt 10 Page 116
Evaluation of the cement clinker [45] Bogue, R.H.: Calculation of the compounds in portland cement. Industrial and
Engineering Chemistry 1 (1929) pp. 192-197. [46] Bogue, R.H.: The chemistry of portland cement. Reinhold Publishing Corporation,
New York 1955. [47] Locher, F W: Berechnung der Klinkerphasen. Schriftenreihe der Zementindustrie,
Vol. 29,1962, pp. 7-29. [48] Locher, F.W: Einfluß der Klinkerherstellung auf die Eigenschaften des Zements.
Zement-Kalk-Gips 28 (1975) Vol. 7, pp. 265-272. [49] Sylla, H.-M.: Einfluß der Klinkerkühlung auf Erstarren und Festigkeit von Zement.
Zement-Kalk-Gips 28 (1975) Vol. 9, pp. 357-362. [50] Locher, F. W: Verfahrenstechnik und Zementeigenschaften. Zement-Kalk-Gips 31
(1978) Vol. 6, pp. 269-277. [51] Sylla, H.-M.: Einfluß der Ofenatmosphäre beim Brennen von Zementklinker.
Zement-Kalk-Gips 31 (1978) Vol. 6, pp. 291-293. [52] Locher, F.W, Richartz, W., Sprung, S., and Sylla, H.-M.: Erstarren von Zement.
Teil III: Einfluß der Klinkerherstellung. Zement-Kalk-Gips 35 (1982) Vol. 12, pp. 669-676.
[53] Sprung, S.: Einflüsse der Verfahrenstechnik auf die Zementeigenschaften. Zement-
Kalk-Gips 38 (1985) Vol. 10, pp. 577-585.
May 1992 Specification Vt 10 Page 117
Evaluation of the emissions [54] Kroboth, K., und Xeller, H.: Entwicklungen beim Umweltschutz in der Zement-
industrie. Zement-Kalk-Gips 39 (1986) Vol. 1, pp. 1-14. [55] Sprung, S.: Spurenelemente - Anreicherungen und Minderungsmaßnahmen.
Zement-Kalk-Gips 41 (1988) Vol. 5, pp. 251-257. [56] Locher, F W: Entwicklung des Umweltschutzes in der Zementindustrie. Zement-
Kalk-Gips 42 (1989) Vol. 3, pp. 120-127. [57] Kroboth, K., und Kuhlmann, K.: Stand der Technik der Emissionsminderung in
Europa. Zement-Kalk-Gips 43 (1990) Vol. 3, pp. 121-131. [58] Wischers, G., und Kuhlmann, K.: Ökobilanz von Zement und Beton. Zement-Kalk-
Gips 44 (1991) Vol. 11, pp. 545-553.
May 1992 Specification Vt 10 Page 118
10. Evaluation example 1 (kiln system with a cyclone pre-heater, calcinator and tertiary air duct)
10.1 Balancing the entire system
10.1.1 Solid substance mass flows
S10m& = 18.00 kg/s S10 NF,x = 0.9760
St12m& = 0 kg/s St12 NF,x not applicable
B7m& = 1.29 kg/s B7NF,x = ashNV,B7ash, xx ⋅ = 0.04 · 0.8007
B3m& = 1.24 kg/s B3NF,x = ashNF, B7ash, xx ⋅ = 0.04 · 0.8007
St1m& = 0.84 kg/s St1 NF,x = 0.6454
St5m& = 0 kg/s St5NF,x not applicable
S1 NF,x = 0.6316
Kiln feed mass flow (Equation 4):
0.6316
6454.084.08007.004.0)24.129.1(976.000.18mS1
⋅+⋅⋅+−⋅=& = 28.55 kg/s.
Ratio of kiln feed to clinker necessary for burning clinker (Equation 6):
000.18
28.55fS1
+= = 1.586 kg/kg.
May 1992 Specification Vt 10 Page 119
10.1.2 Gas volume flows
10.1.2.1 Dry gas
10.1.2.1.1 Minimum air volume flow
S1m& = 28.55 kg/s S1 C,x = 0.0015 S1 S,x = 0.0004
St1m& = 0.84 kg/s St1 C,x = 0.0021 St1 S,x = 0.0008
B7m& = 1.29 kg/s B7u,h = 22684 kJ/kg
B3m& = 1.24 kg/s B3u,h = 22684 kJ/kg
The carbon mass flow (Equation 8) and the sulfide mass flow (Equation 9) effectively fed
in with the kiln feed:
S eff, C,m& = 28.55 · 0.0015 – 0.84 · 0.0021 = 0.0411 kg/s
S eff, S,m& = 28.55 · 0.0004 – 0.84 · 0.0008 = 0.0107 kg/s
Minimum air demand of the fuels (Equation 13):
lmin, B7 = lmin, B3 = 0.44 + 0.000245 · 22684 = 5.998 m³/kg
Minimum air volume flow (Equation 10):
trmin, L,V& = (1.29 + 1.24) · 5.998 + 0.0411 · 8.88 + 0.0107 · 3.32 = 15.58 m³/s
May 1992 Specification Vt 10 Page 120
10.1.2.1.2 Air proportionality factors
G1tr,,CO2y = 0.2925 G1tr,CO,y = 0.0007 G1tr,,O2
y = 0.0489
G2tr,,CO2y = 0.3290 G2tr,CO,y = 0.0006 G2tr,,O2
y = 0.0318
G6tr,,CO2y = 0.2108 G6tr,CO,y = 0.0005 G2tr,,O2
y = 0.0302
Air proportionality factors in the waste gas downstream from the preheater, from the
burning area and from the rotary kiln (Equation 16):
)0489.00007.00.2925(1
0007.05.00489.03.7621
1G1
−−−
⋅−−
=λ = 1.3843
)0318.00006.00.3290(1
0006.05.00318.03.7621
1G2
−−−
⋅−−
=λ = 1.2278
)0302.00005.00.2108(1
0005.05.00302.03.7621
1G6
−−−
⋅−−
=λ = 1.1745
10.1.2.1.3 Infiltrated air at the kiln hood
F ≈ 0.25 m² ∆p = 5 Pa ϑ U = 5°C [41°F]
ρ L,N = 1.29 kg/m³ p = 1010 hPa
May 1992 Specification Vt 10 Page 121
Density of the ambient air:
ρ L = 1.29 · 277
273
1013
1010⋅ = 1.268 kg/m³
Infiltrated air volume flow (Equation 19):
2268.1529.1
25.075.0V trD,Fl, ⋅⋅⋅
⋅≈& = 0.52 m³/s
10.1.2.1.4 Secondary air
λ G6 = 1.1745 B7m& = 1.29 kg/s trL7,V& = 1.39 m³/s
lmin, B7 = 5.998 m³/kg trD,Fl,V& = 0.52 m³/s
Secondary air volume flow (Equation 20):
trL8,V& = 1.1745 · 1.29 · 5.998 – 1.39 – 0.52 = 7.18 m³/s
10.1.2.1.5 Cooler intake air
trL8,V& = 7.18 m³/s trL9,V& = 6.73 m³/s trL11,V& = 23.17 m³/s
Cooler intake air volume flow (Equation 21):
trL10,V& =7.18 + 6.73 + 23.17 = 37.08 m³/s
May 1992 Specification Vt 10 Page 122
10.1.2.1.6 Raw gas
S1m& = 28.55 kg/s S1,CO2x = 0.3380
St1m& = 0.84 kg/s St1,CO2x = 0.3256
St5m& = 0 St5,CO2x not applicable
Seff,C,m& = 0.0411 kg/s
B7m& = 1.29 kg/s B7u,h = 22684 kJ/kg (lignitic coal)
B3m& = 1.24 kg/s B3u,h = 22684 kJ/kg (lignitic coal)
trG5,V& = 0 G5tr,,CO2y ; G5tr,CO,y not applicable
G1tr,,CO2y = 0.2925 G1tr,CO,y = 0.0007 G1tr,,O2
y = 0.0489
trgas,pureV& = 60.42 m³/s gaspuretr,,CO2y = 0.1262 gas puretr,,O2
y = 0.1426
1. Calculation on the basis of the CO2 balance:
Carbon dioxide mass flow (Equation 24) effectively fed in with the kiln feed:
Seff,,CO2m& = 28.55 · 0.3380 – 0.84 · 0.3256 = 9.376 kg/s
CO2 from the kiln feed (Equation 23):
97.1
1
12.01
44.010411.0376.9V S,CO2
+=& = 4.84 m³/s
CO2 from the fuel (Equation 26):
B,CO2V& = (1.29 + 1.24) · 5.01 · 10
– 5
· 22684 = 2.88 m³/s
May 1992 Specification Vt 10 Page 123
Raw gas volume flow (Equation 29):
0007.02925.0
088.284.4V trG1,
+
−+=& = 26.33 m³/s
2. Calculation on the basis of the clean gas volume flow:
Raw gas volume flow (Equations 30 and 31):
a) CO2 balance:
2925.0
1262.042.60V trG1, =& = 26.07 m³/s
b) O2 balance:
0489.021.0
1426.021.042.60V trG1,
−
−=& = 25.28 m³/s
The following applies:
trG1,V& = 0.5 (26.07 + 25.28) = 25.68 m³/s
10.1.2.1.7 Gas downstream from the burning area
G1tr,,CO2y = 0.2925 G1tr,,O2
y = 0.0489 trG1,V& = 25.68 m³/s
G2tr,,CO2y = 0.3290 G2tr,,O2
y = 0.0318
Gas volume downstream from the burning area (Equations 30 and 31):
a) CO2 balance:
3290.0
2925.068.25V trG2, =& = 22.83 m³/s
May 1992 Specification Vt 10 Page 124
b) O2 balance:
0318.021.0
0489.021.068.25V trG2,
−
−=& = 23.22 m³/s
The following applies:
trG2,V& = 0.5 (22.83 + 23.22) = 23.03 m³/s
10.1.2.1.8 Gas downstream from the rotary kiln (kiln inlet)
G1tr,,CO2y = 0.2925 G1tr,CO,y = 0.0007 G1tr,,O2
y = 0.0489
trG1,V& = 25.68 m³/s
G6tr,,CO2y = 0.2108 G6tr,,O2
y = 0.0005 G6tr,,O2y = 0.0302
B3m& = 1.24 kg/s lmin,B3 = 5.998 m³/kg
S eff, C,m& = 0.0411 kg/s lmin,C = 8.88 m³/kg
S eff, S,m& = 0.0107 kg/s lmin,S = 3.32 m³/kg
Gas volume flow downstream from the rotary kiln [30]:
/sm32.9
21.0
0302.02108.01
0007.068.2521.0
5.032.30107.088.80411.0998.524.179.0
21.0
0302.02108.01
21.0
0489.00007.02925.0168.25
V
3
trG6,
=
−−
⋅⋅−⋅+⋅+⋅
−
−−
−−−
=&
May 1992 Specification Vt 10 Page 125
10.1.2.1.9 Infiltrated air (preheater)
trGl,V& = 25.68 m³/s trG2,V& = 23.03 m³/s L1V& = 1.60 m³/s
10.1.2.1.10 Infiltrated air (calcinator)
B3m& = 1.24 kg/s lmin,B3 = 5.998 m³/kg
S eff, C,m& = 0.0411 kg/s lmin,C = 8.88 m³/kg
S eff, S,m& = 0.0107 kg/s lmin,S = 3.32 m³/kg
trG2,V& = 23.03 m³/s G2tr,,O2y = 0.0318 G2tr,,O2
y = 0.0006
trG6,V& = 9.32 m³/s G6tr,,O2y = 0.0302
trL4,V& = 6.73 m³/s trL3,V& = 0.19 m³/s
Infiltrated air volume flow (calcinator) according to [30]:
21.0
1V Ctr,Fl, =& (23.03 · (0.0318 – 0.5 · 0.0006) – 9.32 · 0.0302) + 1.24 · 5.998 +
0.0411 · 8.88 + 0.0107 · 3.32 – 6.73 – 0.19 = 3.03 m³/s
10.1.2.2 Water vapor
10.1.2.2.1 Humidity in the air
p = 101000 Pa ϑ L,U = 4°C [39.2°F] ϕ = 0.4
May 1992 Specification Vt 10 Page 126
Saturation pressure of the water vapor at ambient temperature (Equation 33):
ps (ϑ L,U) = 611.5 + 43.87 · 4 + 1.470 · 42 + 2.564 · 10
– 5
· 43 + 2.877 · 10
– 4
· 44 + 10
– 6
· 45 =
812.2 Pa
Water content of the dry air (Equation 32):
xD = 0.622 2.812
4.0
1010002.812
−
= 0.0020 kg/kg
Humidity volume flows (Equation 34):
a) downstream from the preheater
trmin,L,G1LO,H VV2
&& ⋅= λ · 1.608 · xD = 1.3843 · 15.58 · 1.608 · 0.002 = 0.07 m³/s
b) downstream from the burning area
LO,H2V& = 1.2278 · 15.58 · 1.608 · 0.002 = 0.06 m³/s
c) downstream from the rotary kiln (kiln inlet)
LO,H2V& = 1.1745 · 1.29 · 5.998 · 1.608 · 0.002 = 0.03 m³/s
10.1.2.2.2 Water from the kiln feed
S1m& = 28.55 kg/s S1O,H2x = 0.0204 DO,H2
ρ = 0.8 kg/m³
St1m& = 0.84 kg/s St1O,H2x = 0.0190
May 1992 Specification Vt 10 Page 127
Moisture volume flow from the kiln feed (Equation 35):
8.0
1)019.084.00204.055.28(V SO,H 2⋅⋅−⋅=& = 0.71 m³/s
10.1.2.2.3 Water from the fuel
B7m& = 1.29 kg/s B7O,H2x = 0.087 B7H,x = 0.0453
B3m& = 1.24 kg/s B3O,H2x = 0.087 B3H,x = 0.0453
Moisture volume flows (Equation 36):
a) Main burner
8.0
1
2
180453.0087.029.1V B7O,H 2
+=& = 0.80 m³/s
b) Secondary burner
8.0
1
2
180453.0087.024.1V B3O,H 2
+=& = 0.77 m³/s
10.1.2.2.4 Injection water
10O,H 2m& = 0
May 1992 Specification Vt 10 Page 128
10.1.2.3 Moist gas (examples)
Raw gas volume flow (Equation 40):
G1V& = 25.68 + 0.07 + 0.71 + 0.80 + 0.77 = 28.03 m³/s
Volume flow downstream from the burning area:
G2V& = 23.03 + 0.06 + 0.80 + 0.77 = 24.66 m³/s
Volume flow downstream from the rotary kiln (kiln inlet):
G6V& = 9.32 + 0.03 + 0.80 = 10.15 m³/s
10.1.3 Liquid mass flows
Does not apply.
10.1.4 Energy flows
10.1.4.1 Energy input
10.1.4.1.1 Fuel
B7m& = 1.29 kg/s B7u,h = 22684 kJ/kg B7ϑ = 32°C [89.6°F]
B3m& = 1.24 kg/s B3u,h = 22684 kJ/kg B3ϑ = 32°C [89.6°F]
B7O,H2x = B3O,H2
x = 0.087 B7F,x = B3F,x =)087.01(
496.0
−
May 1992 Specification Vt 10 Page 129
Mean specific thermal capacity for dry lignitic coal (Equation 43):
−
⋅+≈
087.01
496.0803.0846.0c trB, (1 + 1.5 · 10
– 3
· 32 – 8 · 10 –
10
· 323) = 1.344 kJ/kg K
Mean specific thermal capacity for the water in the coal:
OH2c ≈ 4.2 kJ/kg K
Mean specific thermal capacity for moist lignitic coal (Equation 44):
cB7 = cB3 = (1 – 0.087) · 1.344 + 0.087 · 4.2 = 1.592 kJ/kg K
Reaction enthalpy flow of the fuel (Equation 41):
BR,H&∆ = (1.29 + 1.24) · 22684 = 57391 kJ/s
Sensible enthalpy flow of the fuel (Equation 42):
BH& = (1.29 + 1.24) · 1.592 · (32 – 25) = 28 kJ/s
10.1.4.1.2 Kiln feed
S1m& = 28.55 kg/s S1ϑ = 63°C [145.4°F]
Mean specific thermal capacity of the kiln feed (Equation 49):
cS1 ≈ 0.8 + 7.3 ·10 –
4 · 63 – 4.6 ·10
– 7 · 632 + 5.2 · 10
– 11 · 633 = 0.844 kJ/kg K
Enthalpy flow of the kiln feed (Equation 48):
S1H& = 28.55 · 0.844 · (63 – 25) = 916 kJ/s
May 1992 Specification Vt 10 Page 130
10.1.4.1.3 Air
G1λ = 1.3843 trmin,L,V& = 15.58 m³/s xD = 0.002 kg/kg
trL11,V& = 23.17 m³/s ϑ L,U = 4°C [39.2°F]
Sum of the air volume flows fed in (Equation 39):
∑i
LiV& = (1.3843 · 15.58 + 23.17) (1 + 1.608 · 0.002) = 44.88 m³/s
Mean specific thermal capacity of the air fed in (Equation 52):
cp,L,tr = 1.297 + 5.75 · 10 –
5 · 4 + 8.06 · 10
– 8 · 42 – 2.86 · 10
– 11 · 43 = 1.297 kJ/m³ K
Enthalpy flow of the air fed in (Equation 50):
totalL,H& = 44.88 · 1.297 · (4 – 25) = -1223 kJ/s
10.1.4.1.4 Injection water
Does not apply.
10.1.4.1.5 Mechanical performance
Pmech, air-intake fan = 337 kJ/s Pmech, kiln drive = 117 kJ/s
Mechanical performance (Equation 53):
Pmech = (337 + 117) · 0.9 = 409 kJ/s
May 1992 Specification Vt 10 Page 131
10.1.4.2 Energy output
10.1.4.2.1 Reaction enthalpy of the kiln feed
Chemical analyses of the solid substance average samples, each according to Table 10.
10.1.4.2.1.1 C3S, C2S, C3A and C4AF in the clinker
SO3 bound to the CaO in the clinker (Equation 55 or 56):
0.85 · 0.0083 + 1.292 · 0.0010 = 0.0083 > 0.0067
The following then results: S10,CaO3SO
x = 0
CaO bound in the clinker phases (Equation 54):
S10,CaO*x = 0.6641 – 0.0143 – 0 = 0.6498
Clinker phases (Equations 57 through 60):
S10S,C3x = 4.071 · 0.6498 – 7.602 · 0.2137 – 1.43 · 0.0234 – 6.718 · 0.0632 = 0.563
S10S,C2x = 2.868 · 0.2137 – 0.754 · 0.563 = 0.188
S10A,C3x = 2.65 · 0.0632 – 1.692 · 0.0234 = 0.128
S10AF,C4x = 3.043 · 0.0234 = 0.071
May 1992 Specification Vt 10 Page 132
10.1.4.2.1.2 CaCO3, and MgCO3 in the kiln feed and in the raw gas dust
a) kiln feed (Equations 61 through 64):
1.274 · 0.3380 = 0.4306 > 0.4304
The following then results: S1,CaCO3x = 1.785 · 0.4304 = 0.7683
S1,MgCO3x = 1.916 · (0.3380 – 0.785 · 0.4304) = 0.0003
b) raw gas dust (Equations 61 through 64):
1.274 · 0.3256 = 0.4148 < 0.4235
The following then results: St1,CaCO3x = 2.274 · 0.3256 = 0.7404
St1,MgCO3x = 0
10.1.4.2.1.3 CaCO3 and C2S in the bypass dust
Does not apply.
10.1.4.2.1.4 Balance equations
S1m& = 28.55 kg/s St5m& = 0 kg/s St12m& = 0 kg/s
St1m& = 0.84 kg/s S10m& = 18.00 kg/s
Reaction enthalpy flows (Equations 67 through 79):
1) Evaporation of H2O:
R1H&∆ = 2446 (0.0204 · 28.55 – 0.0190 · 0.84) = 1386 kJ/s
May 1992 Specification Vt 10 Page 133
2) Decomposition of clay:
assumption: 100%-illite
R2H&∆ = 884 (0.0402 · 28.55 – 0.0499 · 0.84) = 978 kJ/s
3) Organic clay components:
R3H&∆ = -32786 (0.0015 · 28.55 – 0.0021 · 0.84) = -1346 kJ/s
4) MgCO3 dissociation:
R4H&∆ = 1396 (0.0003 · 28.55 – 0 · 0.84) = 12 kJ/s
5) CaCO3 dissociation:
R5H&∆ = 1778 (0.7683 · 28.55 – 0.7404 · 0.84) = 37895 kJ/s
6) Pyrite:
R6H&∆ = -12914 (0.0004 · 28.55 – 0.0008 · 0.84) = -139 kJ/s
7) Formation of C4AF:
R7H&∆ = -67 · 0.071 · 18.00 = -86 kJ/s
8) Formation of C3A:
R8H&∆ = 74 · 0.128 · 18.00 = 170 kJ/s
9) Formation of β-C2S:
R9H&∆ = -700 · 0.188 · 18.00 = -2369 kJ/s
May 1992 Specification Vt 10 Page 134
10) Formation of C3S:
R10H&∆ = -495 · 0.563 · 18.00 = -5016 kJ/s
11) Formation of K2SO4:
R11H&∆ = -9690 (0.0067 · 18.00 + 0.0014 · 0.84 – 0.0010 · 28.55) = -903 kJ/s
Sum of the reaction enthalpy flow of the kiln feed (Equation 80):
SR,H&∆ = 1386 + 978 – 1346 + 12 + 37895 – 139 – 86 + 170 – 2369 – 5016 – 903 =
30582 kJ/s
10.1.4.2.2 Water evaporation
Does not apply.
10.1.4.2.3 Waste gas losses
G1V& = 28.03 m³/s ϑ G1 = 330°C [626°F] G1O,H2y = 0.0838
L11V& = 23.25 m³/s ϑ L11 = 278°C [532.4°F]
G1,CO2y = (1 – 0.0838) · 0.2925 = 0.2680
G1,O2y = (1 – 0.0838) · 0.0489 = 0.0448
G1,N2y = 1 – 0.0838 – 0.2680 – 0.0448 = 0.6034
May 1992 Specification Vt 10 Page 135
a) Raw gas
Mean specific thermal capacity of the raw gas (Equations 83 through 87):
2COp,c = 1.633 + 9.631 · 10 –
4 · 330 – 4.606 · 10
– 7 · 3302
+ 8.90 · 10 –
11
· 3303 = 1.904 kJ/m³ K
OHp, 2c = 1.489 + 9.52 · 10
– 5 · 330 + 2.021 · 10
– 7 · 3302
– 7.35 · 10 –
11
·3303 = 1.540 kJ/m³ K
2Np,c = 1.301 + 3.05 · 10 –
5 · 330 + 9.65 · 10
– 8 · 3302
– 3.22 · 10 –
11
·3303 = 1.320 kJ/m³ K
2Op,c = 1.304 + 1.916 · 10 –
4 · 330 – 9.4 · 10
– 9 · 3302
– 1.01 · 10 –
11
·3303 = 1.366 kJ/m³ K
G1p,c = 0.268 + 1.904 + 0.0838 · 1.54 + 0.6034 · 1.32 + 0.0448 · 1.366 = 1.497 kJ/m³ K
Enthalpy flow of the raw gas (Equation 82):
G1H& = 28.03 · 1.497 (330 – 25) = 12798 kJ/s
b) Cooler vent air
Mean specific thermal capacity of the cooler vent air (Equation 52):
cp, L11 ≈ 1.297 + 5.75 · 10 –
5 · 278 + 8.06 · 10
– 8 · 2782 – 2.86 · 10
– 11 · 2783 = 1.319 kJ/m³ K
Enthalpy flow of the cooler vent air (Equation 89):
L11H& = 23.25 · 1.319 (278 – 25) = 7759 kJ/s
10.1.4.2.4 Dust losses
St1m& = 0.84 kg/s ϑ St1 = 330°C [626°F]
Mean specific thermal capacity of the raw gas dust (Equation 49):
CSt1 ≈ 0.8 + 7.3 · 10 –
4 · 330 – 4.6 · 10
– 7 · 3302 + 5.2 · 10
– 11 · 3303 = 0.993 kJ/kg K
May 1992 Specification Vt 10 Page 136
Enthalpy flow of the raw gas dust (Equation 90):
St1H& = 0.84 · 0.993 (330 – 25) = 254 kJ/s
10.1.4.2.5 Incomplete combustion
trG1,V& = 25.68 m³/s y CO,tr,G1 = 0.0007
Reaction enthalpy flow (Equation 93):
COR,H&∆ = 25.68 · 0.0007 · 12645 = 227 kJ/s
10.1.4.2.6 Clinker
S10m& = 18.00 kg/s ϑ S10 = 120°C [248°F]
Mean specific thermal capacity of the raw gas dust (Equation 95):
CS10 = 0.729 + 5.921 · 10 –
4
· 120 – 5.369 · 10 –
7 · 1202
+ 2.124 · 10 –
10
· 1203 = 0.793 kJ/m³ K
Enthalpy flow of the clinker (Equation 94):
S10H& = 18.00 · 0.793 (120 – 25) = 1355 kJ/s
May 1992 Specification Vt 10 Page 137
10.1.4.2.7 Radiation and convection:
For calculation examples, see [31]:
VW,Q& = 720 kJ/s
CW,Q& = 360 kJ/s
DW,Q& = 4266 kJ/s
TW,Q& = 486 kJ/s
KW,Q& = 252 kJ/s
10.1.4.2.8 Uncoupled heat
Does not apply.
10.1.4.3 Energy balance
Energy output (Equation 108):
outE& = 30582 + 12798 + 7759 + 254 + 227 + 1355 + 720 + 360 + 4266 + 486 + 252 =
59059 kJ/s
Reaction enthalpy flow of the fuel including the balance remainder (Equation 109):
BR,H&∆ = 59059 – 28 – 916 + 1223 – 409 = 58929 kJ/s
Balance deficit: 58929 – 57391 = 1538 kJ/s
This corresponds to 2.6% of the balance sum.
May 1992 Specification Vt 10 Page 138
10.2 Balancing of the partial systems
10.2.1 Clinker cooler
10.2.1.1 Solid substance mass flows
S10m& = 18.00 kg/s trL8,V& = 7.18 m³/s
St9m& = 0.35 kg/s trL9,V& = 6.73 m³/s
Secondary air dust mass flow (Equation 110):
73.6
18.735.0mSt8 ⋅=& = 0.37 kg/s
Hot clinker mass flow (Equation 111):
S8m& = 18.00 + 0.35 + 0.37 = 18.72 kg/s
10.2.1.2 Gas volume flows
trL8,V& = 7.18 m³/s trL10,V& = 37.08 m³/s xD = 0.0020 kg/kg
Secondary air volume flow (Equation 38):
L8V& = 7.18 (1 + 1.608 · 0.002) = 7.20 m³/s
Cooler intake air volume flow (Equation 38):
L10V& = 37.08 (1 + 1.608 · 0.002) = 37.20 m³/s
May 1992 Specification Vt 10 Page 139
10.2.1.3 Energy flows
10.2.1.3.1 Energy input
L10V& = 37.20 m³/s ϑ U = 4°C [39.2°F] Pmech, intake air fan = 337 kJ/s
cp,L10 = 1.297 kJ/m³ K (for the calculation, see above)
The enthalpy flow of the hot clinker results from the balance remainder from the energy
balance.
Enthalpy flow of the cooler intake air (Equation 113):
L10H& = 37.20 · 1.297 (4 – 25) = -1014 kJ/s
The enthalpy flow of the injection water does not apply here.
Mechanical performance (Equation 114):
Pmech, K = 337 · 0.9 = 303 kJ/s
10.2.1.3.2 Energy output
L9V& = L4V& = 6.75 m³/s St9m& = St4m& = 0.35 kg/s ϑ L4 = 853°C [1567.4°F]
L8V& = 7.20 m³/s St8m& = 0.37 kg/s TW,Q& = 486 kJ/s
May 1992 Specification Vt 10 Page 140
Enthalpy flow of the clinker (for the calculation, see above):
S10H& = 1355 kJ/s
Radiation and convection loss flow of the cooler including the kiln hood:
KW,Q& = 252 kJ/s
The uncoupled heat flow does not apply here.
Enthalpy flow of the cooler vent air (for the calculation, see above):
L11H& = 7759 kJ/s
Enthalpy flow of the tertiary air at the calcinator (Equations 52 and 89):
cp,L4 = 1.297 + 5.75 · 10 –
5 · 8.53 + 8.06 · 10
– 8 · 8532 – 2.86 · 10
– 11 · 8533 = 1.387 kJ/m³ K
L4H& = 6.75 · 1.387 · (853 – 25) = 7752 kJ/s
Enthalpy flow of the tertiary air dust at the calcinator (Equations 95 and 99):
CSt4 = 0.729 + 5.921 · 10 –
4
· 8.53 – 5.369 · 10 –
7
· 8532 + 2.124 · 10
– 10
· 8533 = 0.975 kJ/kg K
St4H& = 0.35 · 0.975 · (853 – 25) = 283 kJ/s
Energy balance for the tertiary air duct:
T W,St4L4St9L9 QHHHH &&&&& ++=+ = 7752 + 283 + 486 = 8521 kJ/s
The iterative calculation then results in the following: ϑ L9 = ϑ St9 ≈ 901°C [1653.8°F]
May 1992 Specification Vt 10 Page 141
Enthalpy flow of the secondary air (Equations 52 and 89):
Cp,L8 = 1.297 + 5.75 · 10 –
5
· 901 + 8.06 · 10 –
8
· 9012 – 2.86 · 10
– 11
· 9013 = 1.390 kJ/m³ K
L8H& = 7.2 · 1.39 (901 – 25) = 8767 kJ/s
Enthalpy flow of the secondary air dust (Equations 95 and 94):
CSt8 = 0.729 + 5.921 · 10 –
4
· 901 – 5.369 · 10 –
7 · 9012
– 2.124 · 10 –
10
· 9013 = 0.982 kJ/kg K
St8H& = 0.37 · 0.982 (901 – 25) = 318 kJ/s
The evaporation enthalpy flow of the water does not apply here.
10.2.1.3.3 Energy balance
Enthalpy flow of the hot clinker (Equation 115):
S8H& = 8767 + 318 + 8521 + 7759 + 1355 + 252 + 1014 – 303 = 27683 kJ/s
Hot clinker temperature:
25cm
H
S8S8
S8S8 +
⋅=
&
&
ϑ
cS8 (1389°C [2532.2°F]) = 1.084 kJ/kg K S8m& = 18.72 kg/s
The following then results: 251.08472.18
27683S8 +
⋅=ϑ = 1389°C [2532.2°F]
May 1992 Specification Vt 10 Page 142
10.2.1.4 Evaluation quantities
10.2.1.4.1 Pre-cooling zone
LB = -0.2 m ϑ W,m ≈ 200°C [392°F] ϑ U = 4°C [39.2°F]
Da = 3.2 m
Heat-transition coefficients (Equations 98, 99 and 101):
αconv = 0.3 · 3.2 + 4.0 + 3.5 100
200 – 0.85
2
100
200
+ 0.076
3
100
200
= 9.168 W/m² K
αrad = 0.9 · 5.67 · 10 –
8
277473
277473 44
−
−= 11.499 W/m² K
αtotal = 9.168 + 11.499 = 20.667 W/m² K
Radiation and convection loss flow of the pre-cooling zone (Equation 117):
coolpreW,Q −& = 20.667 · π · 3.2 (3.2 – 0.2) (200 – 4)
1000
1= 122 kJ/s
10.2.1.4.2 Energy loss flow of the cooling area
Enthalpy flow of the clinker at 4°C [39.2°F]:
S10H& (4°C [39.2°F]) = 18.00 · 0.731 · (4 – 25) = -276 kJ/s
Enthalpy flow of the cooler vent air at 4°C [39.2°F]:
L11H& (4°C [39.2°F]) = 25.25 · 1.298 · (4 – 25) = -688 kJ/s
May 1992 Specification Vt 10 Page 143
Energy loss of the cooling area (Equation 118):
area coolingloss,E& = 1355 + 276 + 7759 + 688 + 252 + 122 = 10452 kJ/s
10.2.1.4.3 Cooling area efficiency
Enthalpy flow of the clinker at 1450°C [2642°F]:
S10H& (1450°C [2642°F]) = 18.00 · 1.106 · (1450 – 25) = 28370 kJ/s
Cooling area efficiency (Equation 119):
η cooling area = 1 – 27628370
10452
+= 0.635
10.2.2 Calcinator
S6,CO2x = 0.0532 xNF,S6 = 0.9016 (sum 1 to 8 in Table 10)
S1,CO2x = 0.3380 xNF,S1 = 0.6316 (sum 1 to 8 in Table 10)
Apparent degree of precalcining of the kiln feed at the kiln inlet (Equation 121):
6316.0
3380.09016.0
0532.0
1apparent −=ϕ = 0.89
May 1992 Specification Vt 10 Page 144
10.2.3 Preheater
Calculation of the mass flows and degrees of separation according to Equations (123),
(126), (127), (130) and (131).
Assumptions made for the calculations:
1) The conveying air volume flow for the kiln feed enters into stage 1.
2) One-fourth of the moisture volume flow from the kiln feed is desorbed in each of the
four uppermost stages.
3) The infiltrated air volume flow of the preheater is uniformly distributed over the four
stages.
4) The following aspects are taken into account for the reaction enthalpy flow in the
preheater:
• evaporation of H2O
• degradation of clay
• organic components
• MgCO3 dissociation
• pyrite
5) The sum of the reaction enthalpy flows in the preheater is uniformly distributed
among the four stages.
6) The cyclone of the calcinator is assigned the number 5.
7) The dust from the rotary kiln and from the tertiary air duct contains 10% alkalis and
90% non-volatile components.
May 1992 Specification Vt 10 Page 145
Results:
energy balance alkali balance
i
ϑ
cS
GV&
cp,G
WQ&
RH&∆ Sm& Stm& Sm& Stm&
ξ
0 63 0.844 – – – – 28.55 – 28.55 – –
1 330 0.993 28.02 1.497 180 223 43.14 0.84 – 0.84 0.98
2 480 1.050 25.97 1.555 180 223 34.67 15.43 34.67 – 0.69
3 638 1.092 25.53 1.595 180 223 49.26 6.96 48.62 7.19 0.87
4 744 1.110 25.09 1.619 180 223 – 21.55 62.03 21.31 0.80
5 – – – – – – – – 23.26 28.92 0.35
6 – – – – – – – – – 3.87 –
10.3 Estimation of error
Table 16 provides an overview of how possible errors in the measured or input quantities
(column 2) impact on the fuel energy consumption when it is calculated according to
Equation (109) or according to Equation (41) and then related to the clinker mass flow
(columns 3 and 4). Thus, the table provides information about the necessary measuring
precision for the individual measured quantities during a performance test.
May 1992 Specification Vt 10 Page 146
10.4 Tables
(The operands are printed in boldface!)
Table 9 - Solid substance mass flows (kiln system with a cyclone
preheater, calcinator and tertiary air duct).
Designation
t/d
kg/s
Clinker
Discharged tertiary air dust
1555
–
18.00
–
Kiln feed
a) meter status
b) calculated
lignitic coal (main burner)
lignitic coal (secondary burner)
2506
2466
111.4
107.3
–
28.55
1.29
1.24
Raw gas dust
Bypass dust
Returned tertiary air dust
73.0
–
30
0.84
–
0.35
May 1992 Specification Vt 10 Page 147
Table 10 - Chemical analyses of the solid substance average sam-
ples in % by weight of the substance entailing loss on
ignition (kiln system with a cyclone preheater, calcinator
and tertiary air duct).
Kiln feed downstream from the cyclone
No.
Components
Kiln
feed
Raw gas
dust
Clinker
Fuel
ash 1a 1b 2 3 4 5
1 SiO2 13.91 14.72 21.37 8.13 14.25 13.65 14.12 14.84 15.85 19.76
2 Al2O3 4.02 4.99 6.32 3.36 4.13 3.95 4.12 4.42 4.59 5.82
3 TiO2 – – – 0.32 – – – – – –
4 P2O5 – – – 0.02 – – – – – –
5 Fe2O3 1.51 1.70 2.34 12.23 1.51 1.51 1.50 1.58 1.62 2.15
6 Mn2O3 – – – 0.25 – – – – – –
7 CaO 43.04 42.35 66.41 48.22 43.60 42.57 43.92 45.22 47.45 61.42
8 MgO 0.68 0.78 1.16 7.54 0.64 0.63 0.64 0.70 0.72 1.01
9 SiO3 0.10 0.14 0.67 17.04 0.49 0.31 0.45 0.45 0.44 0.61
10 S2 – 0.04 0.08 – – – – – – – –
11 Cl – 0.008 0.05 0.001 – 0.03 0.02 0.05 0.15 0.30 0.47
12 K2O 0.57 0.72 0.83 0.15 0.57 0.57 0.57 0.77 1.03 1.85
13 Na2O 0.23 0.22 0.10 0.45 0.30 0.31 0.26 0.23 0.25 0.30
14 ignition loss 35.64 34.00 0.26 2.10 34.58 34.75 34.43 31.72 27.85 6.51
15 sum 1-14 99.75 99.75 99.46 99.81 100.10 98.27 100.06 100.08 100.10 99.90
16 sum 1-8 63.16 64.54 97.60 80.07 61.13 62.31 64.30 66.76 70.23 90.16
17 C 0.15 0.21 – – – – – – – –
18 CO2 33.80 35.56 0.14 – 33.80 33.80 33.76 31.48 27.40 5.32
19 H2O (< 110°C) 0.08 0.07 – – – – – – – –
20 H2O (> 110°C) 1.96 1.83 – – – – – – – –
21 CaOfree – – 1.43 – – – – – – –
May 1992 Specification Vt 10 Page 148
Table 11 - Fuels (kiln system with a cyclone preheater, calcinator
and tertiary air duct).
Designation
Unit
Fuel (main burner)
Fuel (secondary burner)
lower calorific value kJ/kg 22,684 22,684
water wgt.-% 8.70 8.70
ash wgt.-% 4.00 4.00
carbon wgt.-% 60.20 60.20
hydrogen wgt.-% 4.53 4.53
sulfur wgt.-% 0.27 0.27
nitrogen wgt.-% 0.56 0.56
oxygen wgt.-% 21.74 21.74
volatile components 1) wgt.-% 49.60 49.60 1) Relative to the dry substance.
May 1992 Specification Vt 10 Page 149
Table 12 - Temperatures (kiln system with a cyclone preheater,
calcinator and tertiary air duct).
Designation
Temperature (°C [°F]) Kiln feed
Raw gas
Kiln feed (cyclone 2)
Kiln feed (cyclone 3)
Kiln feed (cyclone 4)
Kiln feed (cyclone 5)
Tertiary air (calcinator)
Kiln inlet gas
Hot clinker
Secondary air
Cooler vent air
Clinker
Ambient air
Fuel (main burner)
Fuel (secondary burner)
63°C [145.4°F]
330°C [626°F]
480°C [896°F]
638°C [1180.4°F]
744°C [1371.2°F]
845°C [1553°F]
853°C [1567.4°F]
1024°C [1875.2°F]
1389°C [2532.2°F]
901°C [1653.8°F]
278°C [532.4°F]
120°C [248°F]
4°C [39.2°F]
32°C [89.6°F]
32°C [89.6°F]
May 1992 Specification Vt 10 Page 150
Table 13 - Gas volume flows and composition (kiln system with a
cyclone preheater, calcinator and tertiary air duct).
Gas composition, related to
Dry gas
Moist gas
dry gas moist
gas
Designation
m³(s.c.)/h m³(s.c.)/h m³(s.c.)/h m³(s.c.)/h CO2 O2 CO vol-%
… … H2O vol-%
clean gas 217500 60.42 244000 67.76 12.62 14.26 0.03 – – 10.8
raw gas 92400 25.68 100900 28.03 29.25 4.89 0.07 – – 8.4
gas after burning area 82900 23.03 88700 24.66 32.90 3.18 0.06 – – 6.6
kiln inlet gas 1) (33600) (9.32) 36500 (10.15) 21.08 3.02 0.05 – – 8.0
secondary air 1) (25900) (7.18) (26000) (7.20)
tertiary air 24200 6.73 24300 6.75
cooler vent air 83400 23.17 83700 23.25
cooler intake air 133600 37.08 134000 37.20
conveying air (kiln feed) 5800 1.60 5800 1.61
burner air (secondary burner) 700 0.19 700 0.19
burner air (main burner) 5000 1.39 5000 1.39
infiltrated air (preheater) 3800 1.05 3800 1.05
infiltrated air (calcinator) 1) (10900) (3.03) (10900) (3.04)
infiltrated air (kiln hood) 1900 0.52 1900 0.52
air with 0.3 vol-% of H2O
1) Calculated, but often very imprecise since gas analysis at the kiln inlet is not representative.
s.c. = under standard conditions
May 1992 Specification Vt 10 Page 151
Table 14 - Energy balance of the kiln system (kiln system with a
cyclone preheater, calcinator and tertiary air duct).
Designation
kJ/s
kJ/kg Kl
Input
Fuel main burner secondary burner sensible enthalpy balance remainder
Kiln feed
Air
Mechanical performance
Sum
29262
28129
28
1538
916
–1223
409
59059
1626
1563
1
85
51
–68
23
3281
Output
Reaction enthalpy of the kiln feed
Water evaporation
Waste gas losses
raw gas cooler vent air
Dust losses
Incomplete combustion
Clinker
Radiation and convection Preheater Calcinator Rotary kiln Tertiary air duct cooler + kiln hood
Heat uncoupling
Sum
30582
—
12798
7759
254
227
1355
720
360
4266
486
252
—
59059
1699
—
711
431
14
13
75
40
20
237
27
14
—
3281
Fuel energy consumption including the balance remainder 58929 3274
May 1992 Specification Vt 10 Page 152
Table 15 - Energy balance of the cooler (kiln system with a cyclone
preheater, calcinator and tertiary air duct).
Designation
kJ/s
kJ/kg Kl
Input
Hot clinker (balance remainder)
Cooler intake air
Mechanical performance
27683
–1014
303
1538
–57
17
Sum 26972 1498
Output
Clinker
Radiation and convection
Cooler vent air
Tertiary air and tertiary air dust
Secondary air
Secondary air dust
Heat uncoupling
Water evaporation
1355
252
7759
8521
8767
318
–
–
75
14
431
473
487
18
–
–
Sum 26972 1498
Evaluation quantities
Energy loss of the cooling area in kJ/kg Kl
Cooling area efficiency (1450°C [2642°F])
581
0.635
May 1992 Specification Vt 10 Page 153
Table 16 - Influence of measuring errors on the calculated fuel
energy consumption (kiln system with a cyclone pre-
heater, calcinator and tertiary air duct).
Input quantity
Relative error
in the input
parameter in %
Relative error in
the fuel energy
consumption in %
(Equation 109)
Relative error in
the fuel energy
consumption in %
(Equation 41)
Hu fuel 2 0 2
Ash content of fuel 10 –0.08
Mass flow of fuel 10 0.15 10
Mass flow of raw gas dust 50 0.22
Mass flow of clinker 3 –1.42 3
Volume flow of dry raw gas 10 2.12
Volume flow of dry cooler vent air 10 1.43
Temperature of clinker 5 0.09
Temperature of raw gas 2 0.51
Temperature of kiln feed 10 –0.27
Temperature of cooler vent air 2 0.3
Radiation and convection loss of preheater
50 0.93
Radiation and convection loss of kiln 10 0.74
SiO2 content in the clinker –2 0.29
CO2 content in the kiln feed 5 1.28
CO2 content in kiln feed and raw gas dust
5 1.24
Translation by:
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