Emission Monitoring and Reporting (EMR) Guidelines for ... · PDF file(EMR) Guidelines for ......

1/58

Emission Monitoring and Reporting (EMR)

Guidelines for Annual Discontinuous Emissions Measurements in Holcim

Cement Plants

(European Version)

HGRS-CTS/MT J. Waltisberg

HGRS-CIE/ETPS Th. Lang

Version: 2003-02/E (20.03.2003)

2/58

TABLES OF CONTENTS

1. INTRODUCTION / GENERAL .................................................................................... 5

1.1 General Situation with regard to EMR: ........................................................................ 5

1.2 Supporting Documents............................................................................................... 5

2. AREA OF APPLICABILITY, TERMINOLOGY.............................................................. 6

2.1 Performing Measurements.......................................................................................... 6

2.2 Terminology and Symbols .......................................................................................... 6 2.2.1 General Terminology .............................................................................................. 6 2.2.2 Symbols ................................................................................................................. 7 2.2.3 Conversions of Various Units .................................................................................. 8 2.2.4 Standard Conditions ............................................................................................... 8

3. PLANNING EMISSIONS MEASUREMENTS ............................................................ 10

3.1 Analysis of the Measurement Task ........................................................................... 10

3.2 Measurement Program............................................................................................. 12 3.2.1 Measurement Variables in Exhaust Gas ................................................................ 12 3.2.2 Duration of Measurement and Number of Individual Measurements....................... 12

3.3 Measuring Station .................................................................................................... 12

3.4 Measuring Plane and Measuring Points .................................................................... 12

3.5 References............................................................................................................... 14

4. MEASURING PHYSICAL PARAMETERS................................................................. 15

4.1 Measurement Variables for the Main Volume Stream................................................ 15 4.1.1 Measuring Pressure in the Exhaust Gas Channel .................................................. 15 4.1.2 Measuring Exhaust Gas Temperature ................................................................... 15 4.1.3 Measuring Exhaust Gas Velocity........................................................................... 16

4.2 Measurement Variables for the Partial Volume Flow.................................................. 17

4.3 References............................................................................................................... 18

5. MEASURING PARTICULATE CONCENTRATIONS ................................................. 19

5.1 General Remarks ..................................................................................................... 19 5.1.1 Reference Method ................................................................................................ 19 5.1.2 Isokinetic Sampling ............................................................................................... 19 5.1.3 Measurement Variables ........................................................................................ 20

3/58

5.2 Measuring Particulates with Filter Head Devices ....................................................... 20 5.2.1 Summary of the Measurement Procedures............................................................ 20 5.2.2 Measuring with an Internal Filter Housing .............................................................. 22 5.2.3 Measuring with an Internal Flat Filter ..................................................................... 24

5.3 References............................................................................................................... 25

6. MEASURING METALS, METALLOIDS, AND THEIR COMPOUNDS......................... 26

6.1 General Remarks ..................................................................................................... 26

6.2 Determining Metals, Metalloids, and their Compounds (Except Mercury) ................... 26 6.2.1 Sampling .............................................................................................................. 26 6.2.2 Processing and Analyzing Samples....................................................................... 30

6.3 Determining Mercury ................................................................................................ 31 6.3.1 Sampling Mercury................................................................................................. 31 6.3.2 Area of Application................................................................................................ 32 6.3.3 Characteristics of the Reference Method ............................................................... 32 6.3.4 Supplement and Deviations to the Reference Method............................................ 32 6.3.5 Processing and Analyzing Mercury Samples ......................................................... 32 6.3.6 Supplement and Deviations to the Reference Method............................................ 32

6.4 References............................................................................................................... 33

7. MEASURING GASEOUS INORGANIC POLLUTANTS ............................................. 34

7.1 General Remarks and Terms.................................................................................... 34 7.1.1 On-Line Measuring Method................................................................................... 34 7.1.2 Off-Line Method (with Separate Sampling and Analysis) ........................................ 34

7.2 Gas Sample Processing ........................................................................................... 34 7.2.1 General Remarks.................................................................................................. 34 7.2.2 Filtering the Gas Sample....................................................................................... 35 7.2.3 Preventing Unwanted Condensation of Water........................................................ 35

7.3 On-Line Measurement Methods................................................................................ 36 7.3.1 Overview .............................................................................................................. 36 7.3.2 Calibration at the Measuring Station...................................................................... 37 7.3.3 Oxygen Concentration .......................................................................................... 37 7.3.4 Water Concentration, Moisture.............................................................................. 39 7.3.5 Carbon Dioxide Concentration; Non-Dispersive Infrared Photometry (NDIR) .......... 40 7.3.6 Carbon Monoxide Concentration; Non-Dispersive Infrared Photometry (NDIR) ....... 40 7.3.7 Nitrogen Monooxide Concentration ....................................................................... 41 7.3.8 Nitrogen Dioxide Concentration............................................................................. 42 7.3.9 Sulfur Dioxide Concentration................................................................................. 43

7.4 Off-Line Measurement Methods................................................................................ 46 7.4.1 General Remarks on Enrichment Sampling ........................................................... 46 7.4.2 Water Concentration............................................................................................. 48 7.4.3 Concentration of Inorganic Chlorine Compounds ................................................... 49

4/58

7.4.4 Sulfur Dioxide Concentration................................................................................. 49 7.4.5 Ammonia and Ammonium Compounds.................................................................. 50

7.5 References............................................................................................................... 52

8. MEASURING ORGANIC COMPOUNDS................................................................... 53

8.1 Measuring Total Carbon by Flame Ionization Detection (FID) .................................... 53 8.1.1 Measuring Principle .............................................................................................. 53 8.1.2 Conventions ......................................................................................................... 53 8.1.3 Sampling and Gas Sample Processing.................................................................. 53 8.1.4 Calibration ............................................................................................................ 54 8.1.5 Accounting for Moisture ........................................................................................ 54 8.1.6 Evaluation............................................................................................................. 55

8.2 Benzene .................................................................................................................. 55

8.3 Polychloridized Dioxin and Furan.............................................................................. 56 8.3.1 Reference Method ................................................................................................ 56 8.3.2 Summary of the Methods ...................................................................................... 57 8.3.3 Analysis................................................................................................................ 58 8.3.4 Characteristics ...................................................................................................... 58

8.4 References............................................................................................................... 58

5/58

1. INTRODUCTION / GENERAL

1.1 General Situation with regard to EMR:

• With the adherence to the WBCSD Holcim has accepted to publish a corporate SD report (Including a chapter on environment) within two years from the date of adherence.

• In discussions around AFR implementation the lack of a systematic record of emission data always again is a matter of concern.

• Authorities more and more proceed to the issuing or revision of emission limit values for industries and thus also need reliable back-up data.

• Holcim's engagement for continuous (environmental) improvement, too, needs reliable emission data for adequate preparation of decisions.

To this ends, the Holcim ExCo has adopted the EMR scheme, which requires the Group plants: A) To install and operate continuous emission monitoring (CEM) equipment for

Dust, NOx, SO2, VOC (and O2). B) To measure HCl, NH3, C6H6 (benzene), D/F and HM emissions (at least)

once per year. C) To calibrate CEM equipment (at least) once per year. D) To report in a standardized form once per year (01.03.xy) to HGRS-CIE. E) To see for it that organizations entrusted with work according to points B) and

C) above are capable of delivering quality work.

Note: Points C) and E) are not directly subjects of the above cited Exco decision, but mandatory to assure a high quality level of information according to points A) and B).

1.2 Supporting Documents

In order to standardize and streamline emission measuring and reporting in the Group, to facilitate EMR implementation and generally to assure a high EMR quality level, three documents were prepared by HGRS CIE and CTS, namely: • Emission Monitoring and Reporting Manual for European Countries • Guidelines for Continuous Emissions Measurements in Holcim Cement Plants • Guidelines for Annual Discontinuous Emissions Measurements in Holcim

Cement Plants (Document on hand) In the document on hand continuous emission measuring devices for dust, NOx, SO2, VOC, O2 and other compounds are specified and declared Holcim standard. All three documents can be found in ENVIROnet on HolSpace.

6/58

2. AREA OF APPLICABILITY, TERMINOLOGY

The prescribed annual measurement consists of: • Calibration of the emissions-measuring instruments installed to continuously

monitor dust, nitrogen oxide (NO), sulfur dioxide (SO2), volatile organic com-pounds (VOC), oxygen (O2) and other components that may be present (e.g. CO, HCl, NH3, etc.).

• Emissions measurement of other pollutant components that are not continu-

ously monitored (e.g. benzene, heavy metals, dioxins).

2.1 Performing Measurements

• The plants must have these measurements carried out by a recognized measur-ing team (test house). Execution must comply with the provisions set down in the Holcim EMR Manual and the measuring proceedings are defined precisely in this document, and it is to be used as required procedure by the measuring team.

• This guideline applies to the annual measurements required by Holcim and to any other emissions measurements that may be required by authorities.

• This guideline applies for the measurement of dust and gaseous emissions from the main stack of cement plants. However, it can also be applied analogously for the measurement of other emissions sources (e.g. cement mills).

2.2 Terminology and Symbols

2.2.1 General Terminology

Analysis function: The (mathematical) correlation between the response of an in-strument and the (apparently) true value, determined by using a convention proce-dure. Equivalent measurement method: A procedure that produces measurement re-sults equal to those of the reference method. Determination limit: The smallest concentration of a substance that can be quanti-fied with a prescribed certainty (generally 95 [%]). Official calibration: Testing and certification of a measurement instrument carried out by official calibration authorities in accordance with calibration regulations. Emissions: Air contaminating substances discharged into the open atmosphere. Emissions factor: The ratio between the mass of emissions to the mass of manu-factured or processed product (e.g. kilogram per ton [kg/t]). Calibration: Determining the variance of response of a measuring device by com-paring against values produced by a reference method. Calibration is a means of establishing or checking the analysis function of measuring equipment in continuous operation at a plant. Concentration: The mass of an emitted substance in relation to the volume of ex-haust gas (e.g. in milligrams per cubic meter [mg/m3]).

7/58

Mass flow: The mass of an emitted substance per unit of time (e.g. in grams per hour [g/h]). Measuring plane: The measuring plane is orthogonal to the direction of flow of the exhaust gas and contains all measurement points. Measuring location: The position within the exhaust gas channel where sampling is performed. Measuring station: A working platform for performing measurements and where measuring equipment is installed. Limit of detection: The smallest concentration of a substance, which can be distin-guished from a blank sample. Calibration gases: Gases with accurately defined composition. Calibration gases are prepared by specialized suppliers. Reference method: A measurement procedure established by a recognized techni-cal organization for determining a measurement variable. Used properly, the refer-ence method should produce correct results. If a different measurement procedure is to be used, its results must first be proven to be equal to those of the reference method.

2.2.2 Symbols

Symbol Meaning Units A Area (e.g. cross-section of an exhaust gas

channel) m2

b Barometric pressure hPa, mbar ic Mean concentration of component i g/m3, mg/m3

ci Concentration of component i g/m3, mg/m3 D Diameter of a circular exhaust gas channel m, cm Dh Hydraulic diameter of the exhaust gas channel m, cm d Effective diameter of a measuring probe cm, mm f Moisture kg/m3, vol % m Mass kg, g, mg m& Mass flow kg/h, mg/h, g/h Mi Molar mass of gas i kg/kmol n Number of measured values --- p Pressure bar, N/m2 (Pa) ?p Pressure difference bar, N/m2 (Pa) pi Partial pressure of component i bar, N/m2 (Pa) ri Volume percentage of gas i m3/m3, vol %, ppm ρi Density of gas i kg/m3

s Standard deviation T Temperature K, °C t Time h, min, s τ Dew point °C U Circumference of an exhaust gas channel u Measurement uncertainty

8/58

Symbol Meaning Units V Exhaust gas volume m3

V& Volume flow, volume flow rate m3/h, m3/s VM Molar volume of ideal gases under standard

conditions 22.4 m3/kmol

v Gas velocity m/s x Measured value x Mean value of a set of measurements

Indices Meaning d Dynamic (for pressure measurements) f Moist gas g Gaseous i Individual value max Maximum value of a measured variable n Standard conditions (273 [°C], 1013 [mbar]) N Normalized, e.g. referenced to a certain O2 con-

centration; EMR --> 10 [vol %] O2 s Static

2.2.3 Conversions of Various Units

2.2.3.1 Pressure

Pascal: Bar: 1 [Pa] = 1 [N/m2] 1 [bar] = 0.9870 [atm]

= 10-5 [bar] 1 [atm] = 1.013 [bar] = 0.01 [mbar] 1 [mbar] = 0.7501 [Torr] or [mm Hg]

1 [bar] = 105 [Pa] 1 [Torr] = 1.333 [mbar] = 10.20 [mm H2O]

1 [mm H2O] = 0.09807 [mbar]

2.2.3.2 Temperature

Degree Celsius: 0 [°C] = 273.15 [K] (kelvin)

2.2.4 Standard Conditions

2.2.4.1 Temperature and pressure

Europe and Holcim standard: 1'013 [mbar] and 0 [°C]

9/58

2.2.4.2 Standard Volume

Europe (and Holcim) 22.41 [m3

n /kmol]

Formula: [ ]( )CT273.150.08206kmolm

M3n °+⋅=

2.2.4.3 Concentrations

These conversion factors apply to standard conditions.

Component 1 [ppm] corresponds

to: [mg/m3]

Molar mass

[kg/kmol]

Molar volume

1)

[m3/kmol]

Standard density

ρn [kg/m3]

org. C (VOC) 2) 1.607 CO 1.250 28.0 22.40 1.251 CO2 1.963 44.0 22.26 1.977 HCl 1.627 36.5 22.25 1.639 H2O 4) 0.804 18.0 22.40 0.804 air 29.0 22.40 1.293 N2 28.0 22.40 1.251 NH3 0.760 17.0 22.07 0.771 NO NO --> NO2 3)

1.339 2.053

30.0 22.39 1.340

NO2 4) 2.053 46.0 22.40 2.053 O2 32.0 22.39 1.429 SO2 2.858 64.1 21.89 2.927 SO3 4) 3.572 80.1 22.40 3.572

1) The molar volume of ideal gases under standard conditions is 22.4

[m3/kmol] 2) [ppm] Propane-equivanlent --> [mgC/m3] 3) [ppm] NO or NOx --> [mgNO2/m3] 4) Assumption: ideal gas

2.2.4.4 Conversion for ideal gases

[ ] [ ]ppmc

kmolm

M

kmolkg

GasofMassMolarm/mgc

3n

3n ⋅

=

10/58

3. PLANNING EMISSIONS MEASUREMENTS

Various preparations must be made before a measuring campaign can begin. Only with proper preparation reliable scientific measurement are possible (see [3-1] and [3-2]). The configuration and equipment at the measuring location can also signifi-cantly influence the measurement results.

3.1 Analysis of the Measurement Task

Measuring must be carefully planned in order to collect the needed information at reasonable technical expense. In planning before measuring, the following ques-tions must be answered: 1. Why are measurements being performed?

• What prompted the measuring campaign? − Annual measurement required by Holcim − Requirement by authorities − Planning of a plant expansion, etc.

• What is the aim of the measuring campaign? − To calibrate the continuous emissions measuring instruments of a

plant and measure specific emissions − To check specified and limit values (e.g. conversion of a dust collec-

tor) − To optimize the mode of operation of a system regarding emissions

(e.g. eliminating raw-material components that cause excessive emissions)

2. What is to be measured?

• Measurement variables − Concentrations, emission mass flows, emission factors − Physical quantities (pressure, temperature, velocity, volume flow) − Expected orders of magnitude of the measurement variables (con-

centration, volume flow)? − What concentration levels are critical in the assessment (limit val-

ues, specified values, etc.)? 3. How should the measurements be performed?

• The measurement methods should be selected based on the factors listed above (determination limit, measurement uncertainty, durability of extracted samples, etc.).

4. Under what operating conditions of the system and with what fuels should

measurements be performed? • Direct operation (with raw mill stopped) and/or compound operation (with

raw mill running) for preheater kilns. • With or without the coal mill in operation, if a fraction of the exhaust gas is

to be extracted from the system. • Fuels for primary and secondary firing • Possible definition of raw materials (e.g. alternative raw-material compo-

nents).

11/58

5. Which operating parameters are typical for the condition and mode of opera-tion of the kiln and the quality of the product? • Which operating parameters are to be recorded? • How is this data to be collected?

− Reading or registering a plant’s own measurements − Hiring an independent agency to perform measurements

• Who is to record the operating parameters? − The emissions measuring team − Employees of the cement plant

6. When are measurements to be performed?

• How do emissions characteristics change over time? − Switching from one mode of operation to another (e.g. compound to

direct operation) − Change in fuel type

• When are the highest emissions levels to be expected? • Is the time chosen for sampling representative for the cement-making proc-

ess? 7. Where are measurements to be performed?

• In dedusted gas − Main exhaust stack − Exit preheater

8. How are the measurements to be organized and who is to perform which

measurements? • Who is responsible for operating the kiln system?

− Preparations for the various operating phases − Information in case of operational disturbance

• Who is to perform the actual emissions measurements (emissions measur-ing team)?

• Who is to be responsible for recording the operating parameters? − The emissions measuring team − Employees of the cement plant

• Who is to coordinate the various participants? • Is a joint report to be issued? If so, by whom?

12/58

3.2 Measurement Program

A measuring program is to be developed based on analysis of the measurement task (Chapter 3.1).

3.2.1 Measurement Variables in Exhaust Gas

The variables to be measured are grouped into three categories: • Physical parameters: Pressure (p), temperature (T), and the exhaust gas ve-

locity (v) are needed for calculating volume flow and converting to normalized conditions.

• Exhaust gas composition: Water vapor, oxygen, nitrogen, and carbon dioxide are the main components of exhaust gas from cement plants. These quantities are used for instance to calculate gas density (ρ).

• Pollutants: The third category of measurement variables includes dust, carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), heavy metals, and other pollutants. The measured emissions values are to be normalized to 10 [vol- %] oxygen.

3.2.2 Duration of Measurement and Number of Individual Measurements

The time period over which all emissions are measured must be sufficiently repre-sentative for assessing the emissions behavior of the cement kiln system. The num-ber of measurements required is defined in the "EMR Manual". For matrix meas-urements (see below), the arithmetic mean of a set of point measurements in one measuring plane is treated as one individual measurement.

3.3 Measuring Station

The configuration of the measuring station and choice of measuring location can significantly affect the representativeness of measurements. This infrastructure must be implemented by each plant and is defined in the "EMR Manual".

3.4 Measuring Plane and Measuring Points

The measuring plane is located at the measuring location and contains all measur-ing points. The plane is oriented perpendicularly to the direction of the exhaust flow. Particulates must be measured using such a matrix of points that together deliver the mean concentration measured across the channel area. Sampling partial vol-ume streams at the various matrix points on the measuring plane does this. These points are analyzed during every single measurement (see [3-2]). Number of measuring points: The number measuring points required depends on the cross-sectional area of the channel or stack. Generally, the number of measur-ing points is determined according to the table below. But additional factors must also be considered: The flow conditions and the stream profile of the exhaust gas. These factors may require an increased number of measuring points.

13/58

Measuring Area

(cross section) [m2] Number of Measuring Points

in the Measuring Area < 1.0 4 > 1.0 4 per [m2]

(maximum 20) Any decision to use fewer measuring points must be sufficiently justified, e.g. with results of prior measurements of exhaust gas velocity or gas or dust concentrations (using the prescribed number of measuring points across the entire measuring area). Circular cross section: • Measuring points must be located along two measuring axes, oriented perpen-

dicular to one another. The number of measuring points in the table above in-cludes both measuring axes.

• Positioning of the measuring points is based on subdividing the measuring area into rings of equal surface area. The measuring points are positioned on the central axes of these rings. Figure 1 shows an example with four such rings and 8 measuring points on each measuring axis. The two measuring axes give a to-tal of 16 measuring points, the number of measuring points required for an area of approximately 4 [m2].

Figure 1: Configuration of measurement points in a channel with circular cross

section Messpunkt = Measuring point Messachse = Measuring axis Messöffnung = Sampling port

14/58

The positioning of the measuring points on the central axes of the rings is deter-mined according to the table below.

Circular Cross-Sectional Area Number of Measurement Points per Measurement Axis

No. 2 Measure-

ment points

4 Measure-

ment points

6 Measure-

ment points

8 Measure-

ment points

10 Measure-

ment points 1 0.146 D 0.067 D 0.044 D 0.032 D 0.026 D 2 0.854 D 0.250 D 0.146 D 0.105 D 0.082 D 3 0.750 D 0.296 D 0.194 D 0.146 D 4 0.933 D 0.704 D 0.323 D 0.226 D 5 0.854 D 0.677 D 0.342 D 6 0.956 D 0.806 D 0.658 D 7 0.895 D 0.774 D 8 0.968 D 0.854 D 9 0.918 D 10 0.974 D

Rectangular cross section: The measuring area is to be subdivided into segments of equal area that are similar in form to the overall channel area. The centers of gravity of each segment are used as the measuring points.

3.5 References

[3-1] VDI/VDE Guideline 2448 page 1; Planning of spot sampling measure-ments of stationary source emissions; 1992-04

[3-2] VDI Guideline 2066 page 1; Staubmessungen in strömenden Gasen Gravimetrische Bestimmung der Staubbeladung, Übersicht; 1975-10

15/58

4. MEASURING PHYSICAL PARAMETERS

4.1 Measurement Variables for the Main Volume Stream

4.1.1 Measuring Pressure in the Exhaust Gas Channel

Pressure values are needed for calculating the standard volume flow of emissions. In general, the barometric pressure (b) is discontinuously measured, as is the pres-sure differential (∆pS) between barometric pressure and the static pressure in the exhaust gas channel [4-1]. These pressure differentials are small, compared to barometric pressure, and do not greatly affect calculations. Measuring with e.g. a U-tube manometer usually suffices. More important is the exact measurement of the barometric pressure. Here, aneroid barometers have proven suitable, but they must be regularly checked. Usual measurement uncertainty Barometric pressure: at least ± 1 [%]: ± 10 [mbar] Differential pressure: at least ± 2 [%]: ± 0.1 [mbar]

4.1.2 Measuring Exhaust Gas Temperature

• The exhaust gas temperature is needed for calculating the standard volume flow of emissions [4-1]. Exhaust gas temperatures in the main stacks of cement plants generally are between 80 [°C] and 200 [°C]. Temperature is measured with a corrosion-resistant encased thermocouple, also known as a mineral-insulated thermocouple. ([4-2])

• Mainly types J and K are used for measuring emissions at cement plants ([4-3], [4-4]).

Type Thermo-

couple Application Range Max. Deviation

(higher value applies) J +Fe-CuNi -40 to +750 [°C] Class 1: 1.5 [°C] or t004.0 ⋅

Class 2: 2.5 [°C] or t0075.0 ⋅ Class 3: 2.5 [°C] or t015.0 ⋅

K +NiCr-Ni -40 to +1000 [°C] Class 1: 1.5 [°C] or t004.0 ⋅

Class 2: 2.5 [°C] or t0075.0 ⋅

Class 3: 2.5 [°C] or t015.0 ⋅

Usual measurement uncertainty Entire measuring system (thermocouple including compensation and indicator) Temperature < 200 [°C]: ± 5 [°C]

> 200 [°C]: ± 10 [°C]

16/58

4.1.3 Measuring Exhaust Gas Velocity

Depending on the kiln system, exhaust gas velocities vary between approx. 5 [m/s] and about 20 [m/s]. The velocity must be measured for: • calculating the main volume flow and emissions mass flow • isokinetic (same-velocity) sampling of particulates Pitot-static tubes (Prandtl tubes and S-pitot tubes) are used for measuring velocity. Measuring velocity with an impeller anemometer is not recommended because these instruments are too sensitive to dust.

4.1.3.1 Pitot-Static Tubes (Prandtl Tube and S-Pitot Tube)

The Prandtl tube is used to determine the difference between total pressure (frontal pressure; p1) and static pressure (p2). The differential pressure (∆p) is used to com-pute the exhaust gas velocity (v). Figure 2: Prandtl tube

Velocity can be calculated with these formulas:

ρ∆⋅

=p2

v

where: ∆p = differential pressure ρ = exhaust gas density v = exhaust gas velocity

This formula applies for ∆p in mm on a water column (WS):

[ ]

ρ∆⋅

=WSmmp62.19

v

Note: An additional factor must be considered when using an S-pitot tube because of the different geometry (observe manufacturer's recommendations).

17/58

Conditions of use: Pitot-static tubes can be used for exhaust gas velocities greater than approx. 3 [m/s]. They are generally suitable for measuring emissions in cement plants. Usual measurement uncertainty Exhaust gas velocity (Pitot-static tube; v > 3 [m/s]): ± 5 to 10 [%]

4.1.3.2 Mean Velocity of Exhaust Gas

The mean velocity of exhaust gas in the channel is computed using a number of point measurements taken across the channel cross section. The measuring points must be determined according to Paragraph 3.4: Measuring Plane and Measuring Points. The mean velocity of the exhaust gas is the arithmetic mean of the individual measured values.

∑=

=n

1iiv

n1

v

where: v = mean velocity of exhaust gas n = number of measurement points

4.1.3.3 Main Volume Flow

The main volume flow of the exhaust gas is the volume that flows through the measuring cross-sectional area within a certain period of time. It is calculated using the mean velocity of exhaust gas in the measuring plane and the corresponding cross-sectional area (A) of the channel: vAV ⋅=&

where: V&=main volume flow v = mean velocity of exhaust gas A = cross-sectional area of channel

4.2 Measurement Variables for the Partial Volume Flow

• The partial volume flow is the volume, which is extracted from the main volume flow by sampling equipment within a period of time. The extracted gas volume can be determined with gas flowmeters (wet or dry gas meters).

• The pressure and temperature in the gas flowmeter must be measured. This in-formation is used in converting the gas volume to normalized conditions.

Usual measurement uncertainty Gas flowmeter: ± 3 %

18/58

4.3 References

[4-1] VDI Guideline 2066 page 1; Staubmessungen in strömenden Gasen Gravimetrische Bestimmung der Staubbeladung, Übersicht; 1975-10

[4-2] VDI Guideline 3511 page 1; Temperature measurement in industry - Principles and special methods of temperature measurement; 1996-03

[4-3] EN 61515; Mineral insulated thermocouple cables and thermocouples (IEC 61515:1995)

[3-4] EN 60584; Thermocouples Part 1: Reference tables (IEC 60584-1:1995) Part 2: Tolerances (IEC: 60584-2:1982 and A1:1989)

19/58

5. MEASURING PARTICULATE CONCENTRATIONS

5.1 General Remarks

5.1.1 Reference Method

This Chapter describes methods of measuring particulate emissions at cement plants. The reference methods are described in the following documents: • Filter head device – housings filled with glass wool:

VDI Guideline 2066 page 2 [5-2] • Filter head device with flat filter; for exhaust gases with low particulate concen-

tration (20 [mg/m3]): VDI Guideline 2066 page 7 [5-3]

Exhaust gases at cement plants are generally "dry", meaning the gas temperature is not lower than the dew-point temperature (water dew point). Saturated or supersatu-rated exhaust gases can occur only in exceptional cases, such as with wet scrub-bers in-line after the actual cement-making process. This case is not handled here.

5.1.1.1 Definition of Particulates

Particulates are defined as any materials that can be collected in a measuring filter at a known temperature and that increase the weight of the conditioned filter. Any particulates that accumulate in the sampling system upstream of the measuring filter are to be added to the particulates collected in the filter.

5.1.1.2 Measuring Principle

A partial volume flow is isokinetically extracted from the main volume flow of the ex-haust gas. The particulates contained in the partial flow are collected on a measur-ing filter. Quantitative analysis of the particulates is done by gravimetry. The particu-late concentration in the main volume flow is computed using the extracted partial volume and the quantity of particulates contained in this partial volume.

5.1.2 Isokinetic Sampling

Same-velocity (isokinetic) extraction of the partial stream is necessary so that no in-ertial forces are induced at the probe entrance that would cause a change in con-centration of the particulates being measured. Because underkinetic sampling causes significantly greater error than does overkinetic sampling [5-6], sampling is generally done slightly overkinetic (usually approx. 5 to 10 [%]). Experience shows that for emissions measurements at cement plants the error due to non-isokinetic sampling is insignificant, because the dust emitted is very fine, so that inertial forces have little influence. The extracting velocity is governed by pump capacity and using sampling probes with different effective diameters.

20/58

Calculating the probe diameter:

[ ] ( )( )Stack,smax

Stackf,n

pbv

T273V6.3cmd

∆+⋅

+⋅⋅=

&

where:

b = barometric pressure (atmospheric) [mbar] d = diameter of the probe [cm] ∆ps,Kamin differential pressure [mbar]; static pressure in the exhaust

channel minus ambient pressure (barometric pressure) TKamin temperature in exhaust-gas channel [°C] vmax highest gas velocity in the measuring area [m/s]

f,nV& sampling volume flow (usual condition moist) [m3/h]

If in-between values are calculated, the next smaller available probe diameter is to be used.

5.1.3 Measurement Variables

5.1.3.1 Main Volume Flow

• Area of the measuring cross-section (cross-sectional area of the exhaust-gas channel)

• Exhaust gas velocity • Static pressure in the channel • Temperature • Percentages of the main components of the exhaust gas: oxygen, carbon diox-

ide, water, and nitrogen

5.1.3.2 Partial Volume Flow

• Dust mass (loading) • Volume flow, values for converting to normalized conditions

5.1.3.3 Other Factors

• Date and time • Ambient pressure

5.2 Measuring Particulates with Filter Head Devices

5.2.1 Summary of the Measurement Procedures

These methods all share the characteristic that the particulate collection system is positioned in the exhaust channel immediately behind the sample probe (Figure 3). Because the exhaust gases heat the collection system, filtration occurs at exhaust gas temperature. Filter housings [5-2] or flat filters [5-3] can be used as collection systems.

21/58

5.2.1.1 Important Aspects of the Equipment and Application

• An adjustable pump is used to draw the partial volume flow through the filter, the extraction tube, and the water separator (condensate trap and drying tower). The partial volume is then measured using a gas flow meter.

• The gas-conducting parts of the sampling system up to and including the collec-tion system must be made of corrosion-resistant material, and where necessary, heat-resistant material (e.g. stainless steel or titanium).

Probe: The probe dimensions must be suitable for isokinetic sampling. The geome-try depends on the collection system being used. Measuring filter housing: Filter housing and measuring filter must be separated from each other by a gas-tight seal. Preheating can be done in the exhaust stream (with the sample probe closed) or outside the exhaust channel, using auxiliary heating. Throughout the entire sampling, the temperature in the collection system must never drop below the dew point. In handling after sampling, care must be taken to ensure that no particulates are added to or lost from the probes or the collection system. This is especially important when inserting the probe into the exhaust channel, when removing it, and during the preheating phase in the exhaust channel. Figure 3: Diagram of a sampling system with an internal filter (inside of the channel)

1 Sample probe 2 Elbow and filter head 3 Gas-extraction tube 4 Cooler with condensate trap 5 Measuring equipment for the partial volume flow, with drying

tower (a), pump (b), rotameter (c), thermometer and pressure measurement (d), and gas flowmeter (e)

1

2 3

4

5

a

b

c

d

e

1

2 3

4

5

a

b

c

d

e

22/58

Storing filters: Measuring filters are to be stored in dust-proof containers. Gas extraction tube: The extraction tube (3) can be heated to prevent condensation. Drying tower: The exhaust gas entering the drying tower (5a) containing silica gel must be pre-dried (if necessary) with a gas cooler (4) connected upstream. Pump: A corrosion-proof vacuum pump with in-line protective filter must be used. A governor valve must be used to regulate the partial volume flow. If gas volume is measured behind the pump, the pump must be gas-tight. Gas volume indicator: A flow meter (rotameter, (5c)) is to be used in addition to the gas flow meter (5e) for better control of partial volume flow.

5.2.1.2 Supplement to the Reference Method

The tightness of the sampling system from the probe orifice to gas flowmeter must be verified. Testing for tightness is to be done with the probe closed and under negative pressure that exceeds the negative pressure to be expected during sam-pling. Under these conditions, the leak air volume flow may not exceed 2 [%] of the partial volume flow to be sampled during subsequent measuring (activity).

5.2.2 Measuring with an Internal Filter Housing

This collection system is suitable for measuring "dry" exhaust gases (i.e. above dew point) only.


Probe and filter housing: See VDI 2066 sheet 2 [5-2] for an example setup of a probe and filter housing. The collection system consists e.g. of a filter housing filled with glass wool. A flat filter can be added behind if required. Measuring filter: The filter medium must be inert against components in the exhaust gas. For instance, chemically pure and resistant glass wool is suitable. The filter medium is to be heated to 250 [°C] or more for one hour to remove any volatile im-purities. If the temperature in the exhaust gas channel is higher than 250 [°C], it may be necessary to carry out this procedure at correspondingly higher temperatures. After the filter housing is filled, it is to be flushed with air to remove any broken fibers (duration 10 min. with a volume flow of at least 1.1 x the volume flow of the subse-quent measurement). Conditioning the measuring filter: Before and after measurement, the stuffed filter housings are to be dried for one hour at 120 [°C], cooled in a desiccator (with blue silica gel), and weighed on an analytical balance.

23/58

5.2.2.2 Area of Application

• This method is suitable for dry exhaust gases with dust contents of about 1 to 1000 [mg/m3]. For dust concentrations between 1 and 20 [mg/m3] the filter hous-ing must be augmented with a flat filter.

• This maximum absorption capacity for particulates is about 1000 [mg] per filter. • Heavy metal contents of dust samples collected with this method can be deter-

mined using appropriate methods (see Chapter 6). Limitations • This method is not suitable for exhaust gases that are saturated with water or for

supersaturated exhaust gases. • This method has been tested with exhaust gas temperatures up to 700 [°C] and

thus can also be used for measurements inside the cement kiln system. • If exhaust gas temperatures are high, results may be lower than accurate be-

cause certain substances condense only at lower temperatures.


• The filters must be labeled (numbered). • Specifications for the housings and the filter inserts, as well as for pretreatment,

can be varied as long as collection efficiency is not impaired. • Only glass wool may be used as the filter medium. Usually, a combination of two

different glass wools is used: 1/4 of the filter wool with an average fiber diameter of 3 [µm] and 3/4 of the filter wool with an average fiber diameter of 9 [µm] (Fig-ure 4-2).

• Flat filters must have a collection efficiency of 99.95 % according to DIN 24184 [5-7] and be made of glass wool (with no organic binders).

• Differential pressure across the filter housing can be up to about 400 [mbar], de-pending on the design.

Figure 4: Example of a stuffed filter housing

Grobe Quarzwatte = Coarse glass wool Feine Quarzwatte = Fine glass wool Planfilter = Flat filter

A total of about 1 [g] glass wool per 30 [cm3] housing volume • Coarse: Fiber diameter approx. 9 [µm]; about 3/4 of the volume • Fine: Fiber diameter approx. 3 [µm]; about 1/4 of the volume

24/58

5.2.2.4 Measurement Characteristics

• The determination limit is 1 [mg/m3] of particulates (in combination with a flat fil-ter) per extracted volume of approx. 2 [m3].

• Measurement uncertainty for individual values varies depending on plant type and dust loading. Measurement uncertainty is about 15 [%], but at least 1 [mg/m3]

• The given measurement characteristics apply for ideal measuring locations and error-free performance in measuring.

5.2.3 Measuring with an Internal Flat Filter

This collection system is suitable for detecting low dust content in dry exhaust gases. Flat filters with specified collection rates are used as measuring filters.


Probe and filter housing: For an exemplary setup of a probe and filter housing, see VDI 2066 sheet 7 [5-2], e.g. configuration example 1. Measuring filter: • The filter medium must be inert to the components of the exhaust gas (e.g. Tef-

lon, glass fiber, or glass wool). • For every series of measurements, blank values are to be determined by sub-

jecting 3 to 5 control filters to the entire measurement procedure (except for dust sampling). This includes pretreatment, conditioning, weighing, transport, after-treatment, conditioning, and weighing.

Conditioning and weighing filters: Both the filters and the filter holders must be num-bered. They are to be pretreated in a drying kiln at not less than 150 [°C] (or if nec-essary, 20 [°C] above the sampling temperature). The filter is brought to equilibrium by storage for 24 hours in an air-conditioned weighing room, then weighed on an analytical balance, and put in a dust-proof transport container. After measuring, the filter is to be dried and weighed under the same conditions. The results are to be corrected if the control filters indicate systematic deviation.


• This method can be used for dry exhaust gases with dust content of about 0.2 to 20 [mg/m3]. It is suitable e.g. for measurements behind fabric filters.

• The maximum absorption capacity for particulates is about 20 [mg] per filter. • Heavy metals contents of dust samples collected by this method can be deter-

mined using appropriate methods (see Chapter 6). Limitations • This method is not suitable for exhaust gases that are saturated with water or for

supersaturated exhaust gases. • This method has been tested with exhaust gas temperatures up to 700 [°C], but

cannot be used for measurements in the cement system itself, because the dust content in the system will always exceed 20 [mg/m3].

25/58


Filter: Other dimensions may be used if this has no negative influence on measure-ment results.

5.2.3.4 Measurement Characteristics

• The determination limit is 0.2 [mg/m3] of particulates per extracted volume of ap-prox. 2 [m3].

• Measurement uncertainty for individual values varies depending on plant type and dust loading. Measurement uncertainty is about 15 [%], but at least 0.2 [mg/m3]

• The given measurement characteristics apply for ideal measuring locations and error-free performance in measuring.

5.3 References

[5-1] VDI Guideline 2066 page 1; Staubmessungen in strömenden Gasen

Gravimetrische Bestimmung der Staubbeladung, Übersicht; 1975-10 [5-2] VDI Guideline 2066 page 2; Measurement of particulate matter; manual

dust measurement in flowing gases; gravimetric determination of dust load; tubular filter devices; 1993-08

[5-3] VDI Guideline 2066 page 7; Measurement of particulate matter; manual dust measurement in flowing gases; gravimetric determination of dust load; plane filter devices; 1993-08

[5-4] VDI Guideline 3868 page 1; Determination of total emission of metals, metalloids, and their compounds - Manual measurement in flowing, emitted gases - Sampling system for particulate and filter-passing mat-ter; 1994-12

[5-5] VDI Guideline 3868 page 2; Determination of total emission of metals, metalloids, and their compounds - Measurement of mercury - Atomic absorption spectrometry with cold vapour technique; 1995-11

[5-6] Düwel U. and Dannecker W.; Neuartige Probenahmeeinrichtung zur Staubkonzentrationsmessung in Reingasen von Grossfeuerungsanla-gen zum Zweck der Bestimmung anorganischer und organischer Staub-inhaltsstoffe, Staub-Reinhaltung der Luft 43:227-284 (1983)

[5-7] German Institute for Standardization (DIN) Standard 24 184 - 1974; Typprüfung von Schwebstoffiltern

26/58

6. MEASURING METALS, METALLOIDS, AND THEIR COMPOUNDS

6.1 General Remarks

• This Chapter describes methods used for measuring metals, metalloids, and their compounds. Reference methods are described in the Association of Ger-man Engineers (VDI) Guideline No. 3868, pages 1 and 2 [6-1] [6-2].

• All acceptable significant deviations and simplifications of the reference methods are explicitly mentioned.

• For reference methods of analytical determination for the above-mentioned sub-stances, refer to VDI Guideline 2268, pages 1 to 5 ([6-3] to [6-7]).

• The measurement procedure described under Paragraph 5.2 of VDI 3868, page 1 [6-1] was developed for the following components: antimony, arsenic, beryl-lium, lead, cadmium, chromium, cobalt, copper, nickel, selenium, thallium, vana-dium and zinc. Mercury determination is covered in Paragraph 5.3 of VDI 3868, page 2 [6-2].

• To completely determine the emitted substances, the fraction collected in filters must be measured, and the non-filterable fraction (gaseous and finest particles bound with metal) must also be measured.

• The dust sampling methods described in Chapter 5 form the basis for measuring particle-bound fractions. For the non-filterable fractions a collection system con-sisting of several impingers in series is used.

6.2 Determining Metals, Metalloids, and their Compounds (Except Mercury)

6.2.1 Sampling


A partial volume flow is isokinetically extracted from the exhaust gas. Particulates and particle-bound metals contained in the partial volume flow are collected on a measuring filter (see Chapter 5). Non-filterable metals are collected in a system fur-ther downstream. Outside the exhaust gas channel (after the extraction tube and particulates collection system), the partial volume stream is split into a bypass vol-ume stream and one or more individual gas volume streams. The individual gas vol-ume streams are sent through a series of three or more impingers filled with an ab-sorption solution. Gas flowmeters are used to determine the bypass volume flow as well as the individual gas volume flows.

27/58

Figure 5: Diagram of equipment for sampling metals, metalloids, and their com-pounds

1 Particle collection system with sample probe and elbow 2 Gas sampling tube with controllable heating 3 Partial volume flow temperature measurement and regulation

equipment 4 Insulated adapter, heated if necessary 5 Absorption system with impingers 6 Condensate collector 7 Pump system with bypass control 8 Shutoff valve 9 Gas volume flow indicator (rotameter) 10 Gas volume meter with thermometer 11 Individual gas volume flow (wet gas) 12 Bypass volume flow (dry gas) 13 Main gas volume T Temperature measurement P Pressure measurement G Gas analysis v Velocity measurement

13

28/58


Materials: The parts of the sampling and collection system must be made of heat-resistant materials, and to avoid contamination, low-interactive materials (e.g. tita-nium or glass, but not stainless steel). Sample probe, extraction tube, particle collection system, adapter The sampling system, up to and including the adapter (4), must be heated to pre-vent condensation. Handling the filters: The flat filters and/or the stuffed filter housings must be dried, stored approx. 12 to 24 hours in a desiccator or in a conditioned weighing room, and then weighed. Filter housings must first be vacuumed in order to remove any possi-ble broken fibers. After sampling, the measur ing filters are dried for 3 hours at ap-prox. 130 [°C], conditioned, and then weighed. If the particulate content of a sample is to be determined in addition to the metal, the filter must be conditioned according to the instructions for metal determination. Cleaning the sampling system: Before every sampling series all gas-conducting parts are to be flushed with a cleaning solution at room temperature for 1 hour, and then for another 10 minutes at approx. 60 [°C]. The cleaning solution shall consist of 15 parts by volume nitric acid (approx. 65 [weight %]) and 85 parts by volume water. Before drying (with filtered air), the parts are to be rinsed with water until they are acid free. The parts are then to be stored protected from dust. After sampling, the sampling system must be cleaned following the same instructions. The cleaning so-lutions are to be analyzed and the content detected to be taken into account in the evaluation. For particulates determination, an extraction with acetone can first be done to collect deposition in the collection system and sampling tube. The metal content is also to be determined from the dry sediment of the acetone rinsing solu-tion. Absorption system: • Several absorption lines can be set up in parallel. Each absorption line usually

consists of a series of at least three fritted impingers (frit D00, volume 250 [ml], filled with approx. 40 [ml] absorption solution), which can be cooled if neces-sary. Two absorption solutions can be used for determining the metals men-tioned above. They contain the following concentrations:

− Solution A: 3 parts per volume hydrochloric acid (approx. 35 [weight %]) is

mixed with 1 part per volume nitric acid (approx. 65 [weight %]). 1 part per volume of this solution is then diluted with 9 parts per volume water.

2.6 % HCl + 1.6 % HNO3

29/58

− Solution B: 1 part per volume nitric acid (approx. 65 [weight %]) is mixed with 1 part per volume hydrogen peroxide solution (approx. 35 [weight %]). 1 part per volume of this solution is then diluted with 13 parts per volume water.

4.3 % HNO3 + 2.3 % H2O2

• Solution B is generally used for measurements at cement plants, but there is no

reason not to use Solution A. • Prior to sampling, the impingers are to be treated with the cleaning solution at

approx. 60 [°C] for approx. 24 hours. During sampling, mixing of the absorption solutions it is to be avoided. No uncontrolled overflow from one impinger to an-other may be permitted.

• Once sampling is completed, the solutions can be brought directly to the labora-tory in their original containers, or else the total quantity can be transferred into transport containers of glass or polyethylene. This is to be done in a dust-free room.

Seal test: The entire sampling system is to be tested for tightness, with filters in place and absorption units filled, at maximum operating negative pressure. The indi-vidual gas volume flow and the bypass volume flow are all to be tested separately. The leak-air volume flow should be less than 2 [%] of the volume flow to be ex-tracted during actual sampling. Sampling: The sampling system is to be used in accordance with the instructions given in Chapter 4. Note that the sum of all volume flows together give one isoki-netic sampling. The maximum volume flows are: • Bypass volume flow: = 4 [m3/h] • Individual volume flow: = 0.2 [m3/h] Determining blank values: For every sampling, blank values are to be determined using the entire sampling system. As during the actual sampling, the measuring filter is to be inserted, the absorption solutions filled in, and tightness checked. Without feeding sample gas through the sampling system, the collection phases (absorption solutions, filters) are to be changed again, and treated and analyzed in the same way as the actual samples.


• This method is suitable for the following metals: Antimony, arsenic, beryllium, lead, cadmium, chromium, cobalt, copper, nickel, selenium, thallium, vanadium, and zinc.

• For manganese, palladium, platinum, rhodium, tellurium and tin no validated measurement procedures exist at this time. It is recommended to determine these using an analogous method.

30/58

6.2.1.4 Characteristics of the Reference Method

Specific characteristics of the method, such as determination limit and measurement uncertainty, are covered in [6-1].

6.2.1.5 Supplement and Deviations to the Reference Method

Sample probe, gas extraction tube, particle collection system, adapter • When using an internal filter, the temperature of the extraction tube and the

adapter in general should correspond to the temperature of the exhaust gas. If parts of the system that handle gas (in front of the impingers) are at a lower temperature, losses can occur e.g. through condensation.

• When using an external filter, the gas temperature at the end of the extraction tube, in the filter, and in the adapter, is to be adjusted to 120 ± 10 [°C].

Seal test: Testing for tightness is to be carried out in accordance with the reference method. Degree of collection: The degree of collection of the absorption system must be veri-fied for each sampling. This is done by separately analyzing the metal content in the last impinger. This fraction should not exceed 10 [%] of the total concentration (par-ticle-bound and non-filterable). Cleaning: Simplified cleaning procedures e.g. of impingers at room temperature can be used if the blank values are so low that any negative effect on measurements can be ruled out.

6.2.2 Processing and Analyzing Samples

Matrix influences cannot be ruled out in the analysis of emissions samples. Thus it is necessary to first test the samples for the presence of disturbing matrix influences ([6-3] to [6-7]). If there are such, the standard addition method is to be used.

6.2.2.1 Particulate-Bonded Metals (Filter)

Atomic absorption- and atomic emission spectroscopy (AAS, ICP-AES): • VDI Guideline 2268 page 1 [6-3] describes the method using atomic spectromet-

ric to determine barium, beryllium, cadmium, chromium, cobalt, copper, nickel, lead, strontium, vanadium, and zinc in emitted dusts.

• After gravimetric analysis of the particulates, the particle filter is to be dissolved in a solution of nitric acid (approx. 65 [weight %]) and hydrofluoric acid (approx. 40 [weight %]). This should be done under pressure if possible. Depending on the concentration, analysis is done using flame-, graphite-furnace atomic ab-sorption (AAS)-, or optical emissions spectrometry (ICP-AES).

31/58

X-ray spectrometry • VDI Guideline 2268 page 5 [6-7] describes the method using x-ray fluorescence

analysis to determine lead, cadmium, chromium, cobalt, copper, manganese, nickel, thallium, strontium, vanadium and zinc in emitted dusts. The analysis is carried out directly on the surface of the loaded flat filter.

• This method is not suitable for the low concentrations expected in samples from cement plants. Do not use this analysis method.

6.2.2.2 Non-Filterable Metals Fraction

Samples can usually be analyzed immediately after the prescribed collecting and/or enrichment process. Residues indicate error in particle collection.

6.2.2.3 Supplement and Deviations to the Reference Method

• As an alternative to wet-chemical decomposition, the loaded filter wool can be ground e.g. in a tungsten carbide vibromill or a disc vibromill. The metals (except for mercury) can then be analyzed by x-ray spectrometry. For mercury, an ex-traction with nitric acid (approx. 33 [weight %]) followed by cold vapor AAS is carried out using a portion of the ground filter wool (see Paragraph 6.3).

• Other suitable methods of analysis may be used (e.g. excitation in an inductively coupled plasma with mass-specific detection ICP-MS).

6.3 Determining Mercury

6.3.1 Sampling Mercury


The method for sampling mercury is essentially analogous to the method for other metals (Paragraph 6.2). VDI Guideline 3868 page 2 [6-2] describes the reference method.


Particulate collection system: Especially mild decomposition is required for mercury because of the volatility of this element. Thus, measuring particle-bound mercury will require collecting a special particulate sample in certain cases. Absorption system: • Absorption is done with at least 2 fritted impingers (frit D00, volume 250 [ml],

filled with approx. 40 [ml] absorption solution), filled with a solution of 2 [%] KMnO4 in 10 [%] H2SO4.

• After sampling, the absorption system is to be sealed and brought in for analysis in the original container.

Gas sample flow: The maximum volume flows are: • Bypass volume flow: = 4 [m3/h] • Individual volume flow: = 0.2 [m3/h]

32/58

6.3.2 Area of Application

• This method is suitable for measuring emissions in the concentration range > 5 [µg/m3], measured as total concentration (particulate-bound and non-filterable fractions).

• Limitations: Organic compounds or SO2 can interfere with absorption.

6.3.3 Characteristics of the Reference Method

Specifications for the characteristics of the method, such as determination limit and measurement uncertainty, are covered in [6-2].

6.3.4 Supplement and Deviations to the Reference Method

The degree of collection of the absorption system must be verified for each sam-pling. This is done by separately analyzing the mercury content in the last impinger. The concentration should not exceed 10 [%] of the overall concentration (particu-late-bound and non-filterable). Determination limit • In exhaust gas with a partial gas volume of 1 [m3] and individual volume flows of

0.1 [m3]: 1 [µg/m3] mercury • Measurement uncertainty under same conditions:

< 20 [µg/m3]: 5 [µg/m3] (particles bound with and non-filterable mercury) > 20 [µg/m3]: 25 [%]

• The indicated characteristics apply for ideal measuring locations and error-free performance of measurements.

6.3.5 Processing and Analyzing Mercury Samples

6.3.5.1 Particulate-Bound Mercury

The loaded filter medium is to be decomposed by backflushing for 30 minutes with diluted nitric acid (33 [weight %]) at approx. 130 [°C]. Analysis is done by cold vapor atomic absorption spectrometry.

6.3.5.2 Non-Filterable Mercury

The permanganate solutions are analyzed by cold vapor AAS after reduction e.g. with a hydroxyl ammonium sulfate solution (10 [weight %]).

6.3.6 Supplement and Deviations to the Reference Method

If the sample is homogenized (ground), the mercury in a dust sample can be deter-mined along with the metals and metalloids (see Paragraph 6.2). A portion of the ground filter wool is decomposed with nitric acid and then analyzed by a suitable method e.g., cold-vapor atomic absorption (AAS).

33/58

6.4 References

[6-1] VDI Guideline 3868 page 1; Determination of total emission of metals,

metalloids, and their compounds - Manual measurement in flowing, emitted gases - Sampling system for particulate and filter-passing mat-ter; 1994-12

[6-2] VDI Guideline 3868 page 2; Determination of total emission of metals, metalloids, and their compounds - Measurement of mercury - Atomic absorption spectrometry with cold vapour technique; 1995-11

[6-3] VDI Guideline 2268 page 1; Chemical analysis of particulate matter; de-termination of Ba, Be, Cd, Co, Cr, Cu, Ni, Pb, Sr, V, Zn in particulate emissions by atomic spectrometric methods; 1987-04

[6-4] VDI Guideline 2268 page 2; Chemical analysis of particulate matter; determination of arsenic, antimony and selenium in dust emissions by atomic absorption spectrometry after separation of their volatile hy-drides; 1990-02

[6-5] VDI Guideline 2268 page 3; Chemical analysis of particulate matter; de-termination of thallium in particulate emissions by atomic absorption spectrometry; 1988-12

[6-6] VDI Guideline 2268 page 4; Chemical analysis of particulate matter; de-termination of arsenic, antimony and selenium in dust emissions by graphite-furnace atomic absorption spectrometry; 1990-05

[6-7] VDI Guideline 2268 page 5; Stoffbestimmung an Partikeln, Bestimmung der Elemente Blei, Cadmium, Chrom, Kobalt, Kupfer, Mangan, Nickel, Thallium, Zink in emittierten Stäuben mittels energiedispersiver Rönt-genfluoreszenzanalyse (preliminary draft 1991)

34/58

7. MEASURING GASEOUS INORGANIC POLLUTANTS

7.1 General Remarks and Terms

In general, measuring these emissions is done by extractive methods using mobile measuring equipment.

7.1.1 On-Line Measuring Method

A partial volume flow is fed through a test cell. The compound is continuously measured by means of physical measurement principle; the response is continu-ously indicated.

7.1.2 Off-Line Method (with Separate Sampling and Analysis)

• A partial volume is directed through a collecting phase (absorption liquid or ab-sorptive solid); the analyte is collected and concentrated (enriched). Basically, such enrichment sampling can be performed using: − Impingers (liquid collecting phases) − Adsorption tubes (solid collecting phases)

• Continuous measurement over longer periods is possible only with on-line measurement methods. Emission measurement by enrichment sampling em-ploys continuous sampling procedures, but measurement is interrupted when samples are changed.

7.2 Gas Sample Processing

7.2.1 General Remarks

• On-line measurement methods are used exclusively for determining gaseous components 1. In measuring emissions of gaseous substances at cement plants, it can be assumed that these are distributed sufficiently homogeneously across the measuring area. Thus the sampling of gases can be done from a point ap-proximately at the center of the measuring cross-sectional area.

• In most cases the gas sample must be processed in order not to contaminate the test cell through either dust or condensed water [7-1]. Dedusting is done by filter (generally glass wool), which must be heated if condensation is expected.

• There are three ways to prevent unwanted condensation in measuring devices and connection tubes: − Remove the moisture through suitable gas preparation − Heat the entire gas path − Dilute the exhaust gases

1 Only permanently installed measuring equipment can provide on-line measuring of

dust.

35/58

7.2.2 Filtering the Gas Sample

• In general, filtration is used in measuring gaseous components to protect the measuring equipment. But the filtration must be configured so as not to influence the concentration of the analyte. This applies also to methods of enrichment sampling.

• In addition to internal filters, which are used at exhaust-gas temperature, exter-nal filters can also be used. Here the filter temperature is generally 120 °C ± 10 [°C]. For these exceptions, particular care must be taken that all connections and equipment that come in contact with the gas sample are heated at least to the temperature of the filter.

7.2.3 Preventing Unwanted Condensation of Water

7.2.3.1 Removing Water by Condensation

• Water can be removed from a gas stream by condensation in a measuring-gas cooler. This method is suitable for preparing the following gases: oxygen (O2), carbon monoxide (CO), carbon dioxide (CO2) and nitrogen oxide (NO). The con-nection tube from the exhaust gas channel to the measuring device should gen-erally be kept as short as possible.

• Only when the temperature of the cooler is sufficiently low (= 4 [°C]) can the re-maining residual moisture be neglected in the analysis, otherwise the water con-tent in the gas sample must be considered in the analysis.

Figure 6: Example of gas preparation with a measuring-gas cooler

1 Heated gas-sampling tube (120 [°C])

2 Heated filter (120 [°C]) 3 PTFE connection tube 4 Measuring-gas cooler 5 Drying unit (if required) 6 Fine dust filter (if required)

36/58

7.2.3.2 Removing Water by Permeation (Permeation Drying)

Permeation driers have proven unsuitable for measuring emissions in cement plants. Other components contained in the exhaust gas condense during cooling and block the permeation drier. These systems are not to be used for measure-ments in cement plants.

7.2.3.3 Removing Water by Dilution

The gas sample is diluted with dry air. This drops the dew point of the gas mixture (gas sample and dry air) so low that the gas can be fed to the various instruments with no problem. Because dilution at factors of 20 to 100 must be achieved, devices that can measure in low concentration ranges (ambient air measuring devices) must be used. The dilution method is used mainly for determining the sulfur dioxide con-tent.

7.2.3.4 Using Heated Measuring Devices

• Moist exhaust gases can be measured directly in measuring devices when it can be ensured that the gas-sample temperature will remain above the water dew point at all locations. After extracting the partial volume flow, dedusting is done with a filter, which can be heated if necessary. The gas sample is fed to the measuring device through heated tubing. Condensation problems can occur at cold spots. Thus, special attention must be given to the connections between the various system components, including tubing, filter, and measuring devices.

• With this method it must be borne in mind that the concentration of a moist ex-haust gas is being measured. The water content must be known so that it can be figured into the evaluation. If water content is high, it must be carefully verified whether the measurements are corrupted by interference, because dry calibra-tion gases are normally used.

7.3 On-Line Measurement Methods

7.3.1 Overview

Basically because of their physical/chemical properties many gaseous substances can be measured using these methods. The following overview shows some exam-ples, limited to the substances, which for which on-line measurement methods are frequently used.

Analyte Measurement Principle / Measurement Method O2 Paramagnetism, electrochemical measuring cell CO2 NDIR photometry CO NDIR photometry NO Chemiluminescence, NDIR photometry NO2 Converter SO2 NDIR photometry H2O NDIR photometry (only heated measuring devices), dew-point

mirror method, impact radiation psychrometer

37/58

The following description covers only the generally applicable aspects of the differ-ent measurement principles. Problems related to specific devices are not ad-dressed. Each specific device should be used in accordance with the instructions or recommendations of the manufacturer.

7.3.2 Calibration at the Measuring Station

• Measuring equipment is to be calibrated e.g. using suitable calibration gases at least before beginning and after completing the sampling. For measurements of long duration, calibration is usually done three times daily, more often if neces-sary. The calibration should be suited to the measurement task, in particular to the relevant examination variables (limit values). Before the first calibration the gas path is to be tested for tightness. The calibration gas must be fed without pressure (e.g. flowmeter or liquid-lock overflow opening) through the entire sam-ple-gas path (with heated filter, heated tubing, measuring-gas processing).

• Generally, the zero point of an instrument is first set using a blank gas (e.g. ni-trogen), or the response registered for subsequent computational correction. Then the calibration gas is introduced and the pitch of the calibration function is adjusted, or the response is registered for subsequent computational correction. Certain devices require that the zero point then be rechecked.

• The purpose of calibration after measuring is not to adjust the instrument, but to register the indicated values. This allows drift to be figured in. Special attention is required regarding zero-point drift, because not every instrument indicates negative values or generates negative output signals.

• Calibration is to be suited to the measurement task, focused on the same meas-uring region as the actual measurement. Instrument responses generated during calibration are part of the measuring data and should be archived as such.

• Various manufacturers have built calibration cuvettes into their instruments. These cuvettes must be checked regularly using calibration gases. Testing in-tervals are prescribed by applicable certification requirements (e.g. those recog-nized by the 17th BimSchV in Germany). If these testing intervals are observed, calibration using the cuvettes is allowed. The same guidelines for calibration with gases apply analogously here.

7.3.3 Oxygen Concentration

7.3.3.1 Paramagnetism

Measuring principle: Continuous measurement of oxygen (O2) is based on the prin-ciple of high magnetic susceptibility of oxygen. For example, a body filled with nitro-gen within an inhomogeneous magnetic field can be used. Depending on the oxy-gen concentration of the gas sample, this body will be displaced to a differing de-gree by the magnetic field. The displacement determines the measurement re-sponse. Reference: [7-2].

38/58

Measuring gas preparation: The measuring gas can be prepared with systems with measuring-gas coolers according to Paragraph 7.2. Calibration Blank gas: Nitrogen Calibration gas: Atmospheric oxygen or calibration gas containing oxygen Characteristics Measuring range: 0 to 25 [vol %]

0 to 100 [vol %] (suitable only to a limited extent) Measurement uncertainty: at least 0.2 [vol %]

depending on concentration of the sample gas, between ± 2 [%] and ±10 [%]

7.3.3.2 Electrochemical Cells

Measuring principle: There are different types of electrochemical oxygen sensors. One type operates on the principle of a lead-acid cell. The cathode of this electro-chemical cell is gold and the anode lead. A weak acid serves as the electrolyte. Oxygen from the gas sample diffuses and electrochemically collects on the cathode, thus adding electrons. Electrons are emitted from the anode as the lead oxidizes to lead oxide. This produces an electrical current in an external circuit that is propor-tional to the diffused oxygen. A porous barrier limits the diffusion from the vapor phase so that the signal produced is a linear function of the oxygen concentration. The surface of the lead anode continuously regenerates itself as the lead oxide dis-solves in the electrolyte. Such sensors are built chiefly into measuring instruments that measure other com-ponents (e.g. CO, NO). Service life of sensors: Electrochemical sensors have a limited service life (at least > 1 year) and must be periodically replaced according to the manufacturer’s recommendations. Note: Currently, electrochemical cells have proven suitable only for measuring oxy-gen. Test cells may not be used for other components (CO, CO2, NO, SO2, etc.). Measuring gas preparation: Measuring gas can be prepared with systems with measuring-gas coolers according to Paragraph 7.2. Calibration Blank gas: Nitrogen Calibration gas: Atmospheric oxygen or calibration gas containing oxygen

39/58

Characteristics Measuring range: 0 to 25 [vol %]

0 to 100 [vol %] (suitable only to a limited extent) Measurement uncertainty: at least 0.2 [vol %]

depending on concentration of the sample gas, between ± 2 [%] and ±10 [%]

7.3.4 Water Concentration, Moisture

7.3.4.1 Dew Point Mirror

Measuring principle: Controlled condensation occurs on a dew point mirror at con-trolled temperature. The dew point correlates to the partial pressure of the water. This value, plus the absolute pressure in the exhaust-gas channel, is used to com-pute the water content of the exhaust gas. Calibration: At the measuring location only one function check is possible: ice forma-tion/melting at 0 [°C]. Measuring gas preparation: For determining water concentration, only particulates (dust) are removed from the gas sample (by filter). The entire gas-sample path up to the test cell must be heated carefully so that no condensation of water can occur. Characteristics for measuring dew point with dew point mirror Measuring range: Dew point from approx. - 20 to 100 [°C]

(under standard conditions, corresponds to approx. 0.1 to 100 [vol %])

Measurement uncertainty: Dew point < 40 [°C]: ± 5 [%] (relative) Dew point > 40 [°C]: ± 2.0 [°C]

Important aspects of measuring water content • Avoid cold spots anywhere along the entire sample-gas path up to and including

the instrument connection. • The mirror surface must be clean. Experience in measuring emissions at cement plants shows that fine dust and con-densing substances (ammonium aerosols) can accumulate on the mirror. These can significantly corrupt measurements. This method can be used for short-term measurement of water content, but never for continuous measurement.

7.3.4.2 Psychrometer

Measuring principle: The sample-gas stream is fed into a small container filled with water whose temperature is precisely measured. Depending on the water concen-tration of the gas sample, water evaporates and draws heat from the container. The temperature of the gas sample and temperature of the bath are used to calculate the moisture content of the gas sample.

40/58

Measuring gas preparation: For determining water concentration, only particulates (dust) are removed from the gas sample (by filter). The entire gas-sample path up to the test cell must be heated carefully so that no condensation of water can occur. On the other hand, the temperature of sample gas entering certain devices must not be too high. Calibration at the measuring location is not possible. Characteristics for measuring dew point with the psychrometer Measuring range: Dew point approx. 10 to 100 [°C]

(under standard conditions, corresponds to approx. 1 to 100 [vol %])

Measurement uncertainty: Dew point < 40 [°C]: ± 2 [°C] (absolute) Dew point > 40 [°C]: ± 5 [%] (relative)

7.3.5 Carbon Dioxide Concentration; Non-Dispersive Infrared Photometry (NDIR)

Measuring principle: This measurement procedure is based on the absorption of in-frared radiation by CO2 without spectral resolution (non-dispersive). The absorption in a reference cuvette is compared with that of a cuvette filled with sample gas. Ref-erence: [7-2] Measuring gas preparation: Although carbon dioxide is soluble in water, with the relatively high concentrations only a negligible fraction is lost in the "acidic" conden-sate. Thus the measuring gas can be prepared according to the specifications in Paragraph 7.2. Note: Silica gel adsorbs carbon dioxide to a certain degree, and can lead to lower-than-accurate results. Calibration Blank gas: e.g. nitrogen Calibration gas: range 20 to 25 [vol %] Characteristics for measuring CO2 Measuring range: 0 to 30 [vol %] Determination limit: approx. 0.5 [vol %] Measurement uncertainty: at least 0.2 [vol %] for the given concentrations: ± 10 [%]

7.3.6 Carbon Monoxide Concentration; Non-Dispersive Infrared Photometry (NDIR)

Measuring principle: This measurement procedure is based on the absorption of in-frared radiation by CO without spectral resolution (non-dispersive). The absorption in a reference cuvette is compared with that of a cuvette filled with sample gas. Ref-erence: [7-2]

41/58

Cross sensitivity: • The generally much higher concentrations of carbon dioxide (CO2) in exhaust

gases from combustion processes can produce interference, which is automati-cally compensated for by most devices. The problem is that in the cement-making process far higher concentrations of carbon dioxide arise than in other combustion processes, and the interference is not completely compensated. The interference of a device can be verified by using a calibration gas with high car-bon-dioxide content. Reference: [7-2]

• Nitrogen oxide absorbs IR radiation in the same spectral regions as carbon monoxide; this can also cause interference in NDIR instruments. Nitrogen oxide occurs in the cement-making process only in very small concentrations and the influence is negligible. However, when removing nitrogen oxides by SNCR with urea as the reducing agent it is possible that nitrogen oxide could occur in higher concentrations. Such formation of nitrogen oxide when using SNCR to remove nitrogen oxides in the cement-making process has not yet been studied in detail.

Measuring gas preparation: Measuring gas can be prepared with systems with measuring-gas coolers according to Paragraph 7.2. Calibration Blank gas: e.g. nitrogen Calibration gas: range approx. 1000 [mg/m3] Characteristics for measuring CO Measuring renge: 0 – 2,000 [ppm] (0 – 2,500 [mg/m3]) Determination limit: approx. 50 [mg/m3] Measurement uncertainty: ± 10 [%] (relative)

7.3.7 Nitrogen Monooxide Concentration

7.3.7.1 Chemiluminescence

Measuring principle: Nitrogen monoxide (NO) reacts with ozone (O3) to produce ni-trogen dioxide (NO 2). Some of the NO2 molecules produced will be in an excited state. These excited molecules pass into normal state and thereby emit luminescent radiation. By measuring the intensity of this radiation the NO concentration can be determined. References: [7-3 through 7-8] Measuring gas preparation: • The measuring gas can be prepared with systems with measuring-gas coolers

according to Paragraph 7.2. • The radiation intensity of the luminescence depends on the composition of the

gas sample. High concentrations, particularly of water, carbon dioxide, and pos-sibly other components, can cause “quenching” in certain instruments, leading to lower-than-accurate results. In cement plants, particularly carbon dioxide can negatively influence measurements. The interference is to be determined using calibration gases containing CO2 and figured into the measurements.

42/58

Calibration Blank gas: e.g. nitrogen Calibration gas: range 500 - 700 [ppm] Characteristics for measuring NO Measuring ranges: 0 - 750 [ppm]

(0 - 1000 [mg NO/m3], 0 - 538 [mg NO2/m3]) Determination limit: 30 [mg/m3] (indicated as NO 2) Measurement uncertainty: ± 10 [%] (relative)

7.3.7.2 Non-Dispersive Infrared Photometry (NDIR)

Measuring principle: This measurement procedure is based on the absorption of in-frared radiation by NO without spectral resolution (non-dispersive). The absorption in a reference cuvette is compared with that of a cuvette filled with sample gas. Ref-erence: [7-2] Measuring gas preparation: Refer to 7.3.7.1: Measuring gas preparation. Calibration Blank gas: e.g. nitrogen Calibration gas: range 500 - 700 [ppm] Characteristics for measuring NO Measuring range: 0 - 750 [ppm]

(0 - 1000 [mg NO/m3], 0 - 1538 [mg NO2/m3]) Determination limit: 30 [mg/m3] (indicated as NO 2) Measurement uncertainty: ± 10 [%] (relative)

7.3.8 Nitrogen Dioxide Concentration

Measuring principle: Nitrogen dioxide (NO2) is not directly determined with emis-sions measuring instruments. Rather, this gas component is deoxidized into nitro-gen oxide (NO) in converters and measured together with the nitrogen monoxide (NO) as a sum (NOx). Various converters are used for measuring emissions: e.g. carbon converters, molybdenum converters, and steel converters. • Carbon converter:

NO2 + C → NO + CO Operating temperature approx. 350 [°C]

• Molybdenum converter: 2 NO2 → 2 NO + O2 3 NO2 + 2 Mo → 3 NO + 2 MoO3 Operating temperature approx. 450 [°C]

• Steel converter: 2 NO2 → 2 NO + O2 (Catalytic effect only) Operating temperature 650 - 750 [°C]

43/58

In exhaust gases of cement plants the nitrogen dioxide content of overall ni-trogen oxides (NOx) is generally under 5 [%]. This small fraction can be ig-nored when using a converter. Problems with converters: • Cross sensitivity to ammonia differs with converter type. This is quite significant

because certain cement plants produce high concentrations of ammonia. • Corrosion and fouling, and thus reduced conversion efficiency. • Secondary reactions of nitrogen oxide in the converter. References: [7-3 through 7-8] Measuring gas processing: If a converter is used before the measuring-gas prepara-tion (measuring-gas cooler), the nitrogen oxides in the processed sample gas will be nitrogen monooxide (NO). The water content can be removed from the gas sample e.g. through condensation (see Paragraph 7.2). Calibration Blank gas: e.g. nitrogen Calibration gas: NO calibration gas is used for both channels. NO2 calibration

gases are generally not used at the measuring location because they are very problematic.

Converter: The efficiency of the converter must be checked regularly (e.g. at least once a year), and any time faulty operation is suspected.

7.3.9 Sulfur Dioxide Concentration

Problematic nature of measuring: • Sulfur dioxide (SO2) is generally determined by the principle of non-dispersive

infrared analysis (NDIR). Investigations [7-12] have shown that cement-plant exhaust gases contain gaseous components (e.g. ammonia) that react with a fraction of the sulfur dioxide when the gasses cool, and this is discharged from the measuring-gas cooler along with the condensate. Thus lower-than-accurate results are given by the analyzer.

• Consequently, sulfur dioxide emissions must be measured using modified ver-sions of the usual measuring equipment with gas cooler and NDIR analyzer. Or other measurement methods (e.g. measurement procedure with dilution) must be used.

7.3.9.1 NDIR Analysis with Acidification

• The reactive components of cement-plant exhaust gases can be eliminated by acidification. This is done in permanently installed emission monitoring systems through continuous injection (Figure 7a) of nitric acid before the measuring-gas cooler. Mobile emission measuring systems (Figure 7b) do not use acid injec-tion. Here, the sample gas is sent through an acid receiver (which must be re-placed at regular intervals), before entering the measuring-gas cooler.

44/58

• Before the actual emissions measurement, the effect of the acid receiver on the measurement results should be verified with the kiln in the operation mode that produces higher sulfur dioxide emissions (e.g. direct operation). For this purpose a short measurement is made with and without the acid receiver. If the influence of the acid receiver is small, it can be disregarded.

Figure 7: Gas processing with measuring-gas cooler and acid receiver

a.) with permanently installed continuous injection

1 Heated gas-sampling tube

(120 [°C]) 2 Heated filter (120 [°C]) 3 Short sample-gas tubing

(PTFE) with acid injection 4 Measuring-gas cooler 5 Drying unit (if required) 6 Fine dust filter (if required) 7 Acid container 8 Dosage pump (e.g. perisaltic

pump)

b) with replenishable receiver

1 Heated gas-sampling tube

(120 [°C]) 2 Heated filter (120 [°C]) 3 Short sample-gas tube

(PTFE) with acid receiver 4 Measuring-gas cooler 5 Drying unit (if required) 6 Fine dust filter (if required)

Measuring procedure: This measurement procedure is based on the absorption of infrared radiation by SO2 without spectral resolution (non-dispersive). The absorp-tion in a reference cuvette is compared with that of a cuvette filled with sample gas.

12

3

45

6

7

8

12

3

45

6

7

8

12

34

5

6

12

34

5

6

45/58

Calibration Blank gas: e.g. nitrogen Calibration gas: range 400 - 600 [mg/m3] Characteristics for measuring SO2 Measuring range: 0 - 750 [mg/m3] (in 1000 [mg/m3]) Determination limit: 10 [mg/m3] Measurement uncertainty: ± 10 [%] (relative)

7.3.9.2 Measuring by the Dilution Method

• The gas to be measured is diluted with dry air [7-12]. Dilution occurs directly af-ter the gas enters the sampling probe installed in the exhaust stack. This has the effect that the entire dilution probe is heated up by the exhaust gas, so that no condensation can occur in the sampling location area. A defined diluted gas sample exits the measuring-gas diluter. The dew point of this gas is so low that no condensation can occur, even in the measuring device.

• Figure 8 shows the configuration of the measuring-gas diluter (in the exhaust stack) and control unit. The measuring gas (1) is extracted and diluted by a backflushable filter system (2-3) and critical nozzle of an injector pump (com-pressed-air ejector, 5). Depending on the critical nozzle (4), the negative pres-sure induced by the injector creates a constant measuring-gas flow (depending on the nozzle, between 20 and 500 [l/min]), which is fed into and diluted by a blank gas stream (15) (dry air), governed by a precision pressure regulator (16). Figure 8: SO2 measuring equipment for dilution method

((Messgasverdünner = Measuring-gas diluter)) ((Steuereinheit = Control unit))

1 Measuring gas 6 Exit of diluted gas 2 Stainless steel filter 7 Negative pressure (nozzle) 3 Glass wool filter 8 Blank gas connection (air) 4 critical nozzle 9 Precision pressure regulator 5 Injector pump 10 Backflushing valve 11 Calibration gas port 12 Negative pressure (exhaust stack)

46/58

• A fluorescence analyzer with suitably high sensitivity (immission device) is used for analyzing the diluted measuring gas. The measurement principle is based on the excitation of SO2 molecules by radiation in ultra-violet light. This excitation causes fluorescence emission that is proportional to the sulfur dioxide concen-tration in the measuring gas.

Calibration Blank gas: e.g. nitrogen Calibration gas: range 400 - 600 [mg/m3] Characteristics for measuring SO2 Measuring range: 0 - 750 [mg/m3] (1000 [mg/m3]) Determination limit: 10 [mg/m3] Measurement uncertainty: ± 10 [%] (relative)

7.4 Off-Line Measurement Methods

Advantages of these methods compared to on-line methods are: • More economical measuring equipment; the labor-intensive analysis can be per-

formed in the laboratory • Higher selectivity can usually be achieved because selective analysis is pre-

ceded by selective enrichment. These advantages contrast with two significant disadvantages: • Enrichment sampling provides no information about the distribution of emissions

over time during the sampling period. • Analysis results are not immediately available at the time of sampling.

7.4.1 General Remarks on Enrichment Sampling

• Enrichment sampling methods involve drawing a partial volume flow through a collecting phase (impingers, adsorption tube, cold trap) by means of a vacuum pump. The analyte is collected and enriched, and then taken to a laboratory for analysis. Basically, both liquid and solid collecting phases can be used. For measuring inorganic gases, liquid collecting phases are used almost exclusively. The precise determination of the gas sample volume is an important aspect of these methods, and is explained in more detail in Chapter 4.

• In order to avoid condensation of water and thus loss of analyte, the gas-conducting parts of the sampling system are to be heated. If a short unheated connection tube (e.g. PTFE) is used between the manifold and the collecting phase, its contents belong together with the sample. Thus the connector must be flushed out after sampling and the rinsing solution added to the first absorp-tion solution.

47/58

Figure 9: Example of sampling equipment 1 Sampling probe with heated extraction tube and heated filter if required (inter-

nal or external) 2 Heated manifold for splitting the partial volume flow for parallel sampling of

various components 3 Short unheated connector (e.g. PTFE) if required 4 Absorption system, cooled if necessary 5 Demister unit, cooled if necessary 6 Pump with controls 7 Gas meter with thermometer, e.g. liquid-lock gas meter or drying tower and bel-

lows gas meter Sampling by absorption: The partial volume flow is fed through impingers (fritted gas-wash bottles) filled with a suitable absorption solution. At least two impingers are to be connected in series, but the last bottle must not absorb more than 10 [%] of the total amount of analyte. In line behind the absorption system are a demister unit, pump, and gas meter. Note: • Carbon dioxide dissolves to a certain extent in water. When using water-lock gas

meters, CO2 saturation of the water should be reached (e.g. by flushing with sample gas for 10 minutes) before measuring begins.

• When using volatile absorption solutions, or if the exhaust gases are very hot, the absorption solutions must be cooled. If necessary a cooler is to be con-nected in front of the absorption system. The condensate from the cooler be-longs in the analysis.

48/58

Following are the reference methods for determining some gaseous inorganic pol-lutants:

Pollutant Absorption solution VDI guidelines Inorganic chlorine compounds

Water 3480 p.1 [7-9]

Sulfur dioxide Hydrogen peroxide solution 2462 p.8 [7-11] Basic N-compounds Ammonia

Diluted sulfuric acid 3496 p.1 [7-6]

7.4.2 Water Concentration

7.4.2.1 Sampling by Condensation

When measuring particulates, a relatively large partial volume flow is extracted from the exhaust-gas channel. After filtration, a large fraction of the water contained in the exhaust gas is condensed out. The residual moisture after the cooler must be taken into account. If the residue concentration is small, it can be computed by us-ing the temperature at the cooler discharge as the dew point. If the pre-cooled gas sample is also fed through a drying tower (e.g. blue silica gel), then the water ad-sorbed there can be measured gravimetrically and added to the condensate. Analysis: Volumetry and/or gravimetry Characteristics for measuring water concentration by condensation Measuring range: Lower limit: The dew point of the sample must be signifi-

cantly higher than the cooler temperature, and conden-sate volume must be measurable. If required, 2 blue silica gel cartridges in series are to be used after condensation.

Measurement uncertainty: ± 10 % (relative)

7.4.2.2 Sampling by Adsorption

Water content of exhaust gas can also be completely determined by means of ad-sorption (e.g. blue silica gel). The gas-sample path is to be carefully heated and kept as short as possible. The gas sample is fed through a pre-weighed blue silica gel cartridge, and the volume measured e.g. with a gas meter, as usual for enriched sampling methods. The exhaust gas volume will depend on the water concentration in the exhaust gas and the dimension of the adsorber. Analysis: Gravimetry Characteristics for measuring water concentration by adsorption Measuring range: Lower limit: 0.1 [vol %] (scale accuracy) Measurement uncertainty: ± 10 [%] (relative) If required, 2 blue silica gel cartridges in series are to be used. It must be ensured that the water content following the adsorber is negligible.

49/58

7.4.3 Concentration of Inorganic Chlorine Compounds

Sampling: VDI Guideline 3480 page 1 describes the reference method [7-9]. En-richment sampling in water is the method used to determine the concentration of gaseous inorganic chlorine compounds (indicated in the results as HCl). Analysis: The VDI guideline describes the following methods of analyzing absorption solutions: • Mohr titration (silver nitrate/potassium dichromate) • Potentiometric titration (silver nitrate) • Photometric analysis (mercury thiocyanate) In variance to the prescribed methods, samples are often analyzed using ion chro-matography. Various cases of analysis have produced lower-than-accurate results. Thus, ion chromatography is not to be used for this analysis. Characteristics for measuring the concentration of gaseous inorganic chlorine com-pounds Gas-sample volume: approx. 100 [l] Determination limit: depending on analysis method: 0.5 - 20 [mg/m3] Measurement uncertainty: concentrations < 3.5 [mg/m3]: ± 0.5 [mg/m3]

concentrations > 3.5 [mg/m3]: ± 15 % (relative)

7.4.4 Sulfur Dioxide Concentration

Sampling: • VDI Guideline 2462 page 8 describes the reference method [7-11]. Determining

sulfur dioxide concentration (SO2) is done by enrichment sampling in a 3 [%] hy-drogen peroxide solution. The sulfur dioxide is oxidized into sulfate and retained as such in this solution.

• The temperature of the heated sampling probe and the filter (glass wool) is to be set so high that condensation (acid dew point) is prevented.

• Generally, the sum of the sulfur oxides is determined with this method. The re-sult of the sulfur oxide concentration is given as sulfur dioxide (SO2).

Analysis: • For analyzing the absorption solutions, the VDI guideline describes titration with

a barium perchlorate solution against thorin. • In variance to the prescribed methods, samples are often analyzed using ion

chromatography or ICP-OES. Various cases of analysis have produced lower-than-accurate results. Thus, ion chromatography and ICP-OES are not to be used for this analysis.

References: [7-11], [7-12]

50/58

Parameters for measuring sulfur dioxide concentration Gas sample volume: approx. 100 [l] Determination limit: 2 [mg/m3] Measurement uncertainty: concentrations < 15 [mg/m3]: ± 2 [mg/m3]

concentrations > 15 [mg/m3]: ± 15 % (relative)

7.4.5 Ammonia and Ammonium Compounds

General remarks: Ammonium compounds can occur as gases or particles in emis-sions. In cement plants the concentration of dust is generally much lower than the concentration of gaseous ammonia and ammonium compounds. Thus, in measuring emissions only the gaseous fraction is determined and a simplified method is used. Following is a review of both analysis methods.

7.4.5.1 Method for Determining Gaseous and Particulate Emissions

If the particulate-bound fraction is to be measured, this must be done by matrix measurement and isokinetic sampling. 0.05 M H2SO4 is used as the absorption me-dia for the gaseous fraction. Sampling: Two configurations can be used for sampling:

1. Measuring filter (internal or external) for particulates and impingers for the gaseous fraction.

2. Standard impingers (cf. VDI 3496) for particulate and gaseous fractions. Both cases involve enrichment sampling according to Chapter 7.4. In addition, the equipment and conditions pertaining to particulate sampling must comply with Chap-ter 5. This particularly applies to nozzle, elbow, filter, gas extraction tube, and vol-ume flow. The entire gas path must be flushed with an absorption solution after each individual sampling. Analysis: • The reference method for determining the concentration of ammonia and am-

monium compounds is photometric analysis of ammonium in steam distillate af-ter conversion to indophenol in an alkaline solution (VDI 3496). VDI 2461 ad-dresses interference, particularly by organic nitrogen compounds. Organic ni-trogen compounds occur only in negligibly small concentrations in cement-plant emissions.

• The ammonium compounds collected in the filter are extracted by agitating in 0.05 M H2SO4.

• Because in configuration 2 the entire volume flow is exposed to the absorption solution, the ammonium-containing solutions used for particulates and the rins-ing solution can be analyzed together with the absorption solution from the first impinger.

51/58

Estimated characteristics Gas sample volume: approx. 100 [l] (impinger, configuration 1)

approx. 1000 [l] (impinger, configuration 2) Determination limit: 0.5 [mg/m3] Measurement uncertainty: < 3 [mg/m3]: ± 0.5 [mg/m3] (absolute)

> 3 [mg/m3]: ± 15 [%] (relative) Limit of detection: 0.1 [mg/l] Important: • Ion chromatography or ion-sensitive electrodes are expected to produce deviat-

ing results. These methods may not be used. • The analytical limit of detection depends on the method used. • The filters used here cannot be used for gravimetric determination of particulate

concentration because the conditioning required for this (e.g. Chapter 5.2.3) can lead to loss of analyte.

7.4.5.2 Simplified Method for Determining Gaseous Emissions

If only gaseous components are to be measured, matrix measuring with isokinetic sampling is not necessary. Under this procedure, a partial volume flow is drawn by vacuum pump through a collecting phase (impinger, 0.05 M H2SO4). The gaseous ammonium compounds and ammonia are collected, enriched, and then taken to the laboratory for analysis. Analysis: The reference method for determining the concentration of ammonia and ammonium compounds is photometric analysis of ammonium in steam distillate af-ter conversion to indophenol in an alkaline solution (VDI 3496). Interference, particu-lar by organic nitrogen compounds, is addressed in VDI Standard 2461. In cement-plant emissions, interfering nitrogen compounds occur only in negligibly small con-centrations. Estimated characteristics Gas sample volume: approx. 100 [l] (impinger) Determination limit: 0.5 [mg/m3] Measurement uncertainty: < 3 [mg/m3]: ± 0.5 [mg/m3] (absolute)

> 3 [mg/m3]: ± 15 [%] (relative) Limit of detection: 0.1 [mg/l]

52/58

7.5 References

[7-1] ISO No. 10396; Stationary Source Emissions - Sampling for the Auto-

mated Determination of Gas Concentrations; 1993-10 [7-2] ISO No. 12039; Stationary Source Emissions - Determination of the

Volumetric Concentration of CO, CO2, and Oxygen - Performance Characteristics and Calibration of an Automated Measuring System; 2001-06

[7-3] VDI Guideline 2459, page 6; Messen gasförmiger Emissionen; Messen der Kohlenmonoxid-Konzentration; Verfahren der nicht dispersiven Inf-rarot-Absortion; 1980-11

[7-4] VDI Guideline 2456 page 7; Messen gasförmiger Emissionen; Messen

von Stickstoffmonoxid-Gehalten; Chemilumineszenz-Analysatoren (Atomosphärendruckgeräte); 1981-04

[7-5] VDI Guideline 2456 page 6; Messen gasförmiger Emissionen; Messen der Summe von Stickstoffmonoxid und Stickstoffdioxid als Stickstoffmo-noxid unter Einsatz eines Konverters; 1978-05

[7-6] VDI Guideline 3496 page 1; Messen gasförmiger Emissionen; Bestim-men der durch Absorption in Schwefelsäure erfassbaren basischen Stickstoffverbindungen; 1982-04

[7-7] ISO No. 10849.2; Stationary Source Emissions - Determination of the Mass Concentration of Nitrogen Oxides - Performance Characteristics of Automated Measuring Systems; 1996-04

[7-8] ISO No. 7996; Determination of Mass Concentration of Nitrogen Oxide (Ambient Air) Efficiency of the Converter

[7-9] VDI Guideline 3480 page 1; Gaseous emission measurement; meas-urement of hydrogen chloride; measurement of the hydrogen chloride concentration in waste gases with a low content of particulate chloride; 1984-07

[7-10] VDI Guideline 2462 page 8; Measurement of gaseous emissions; measurement of the sulfur-dioxide concentration; H2O2-thorin method; 1985-03

[7-11] VDI Guideline 2462 page 7; Measurement of gaseous emissions; measurement of the sulfur-trioxide concentration; 2-propanol method; 1985-03

[7-12] H. Nyffenegger, J. Waltisberg; Experience with measuring devices for the determination of sulphur dioxide emission at Swiss cement plants; Zement-Kalk-Gips, issue 4/1988, pages 202-205 (German version) Zement-Kalk-Gips International, issue 6/1988, pages 155-159 (English translation)

53/58

8. MEASURING ORGANIC COMPOUNDS

8.1 Measuring Total Carbon by Flame Ionization Detection (FID)

8.1.1 Measuring Principle

The flame ionization detector (FID) is used to continuously determine the cumulative concentration of the organically bound carbon in [mgC/m3]. The gas sample is burned in a flame of hydrogenous fuel gas and air. The conductance of the flame is measured as current between two electrically charged electrodes. This signal is proportional to the number of carbon atoms burned in the flame. It must be noted that the response factor depends on the type of bond of the respective carbon at-oms.

8.1.2 Conventions

• The flame ionization detector (FID) is used for investigating cement plants. Re-sults are given in terms of total carbon (volatile organic compounds). The re-sponse factors of the measured compounds are set equal to 1 in the analysis.

• Remark: EN Standard 12619 (Bestimmung der Massenkonzentration des ge-samten gasförmigen organisch gebundenen Kohlenstoffs in geringen Konzentra-tionen in Abgasen [8-1]) prescribes minimum criteria for instruments to be used. The standard defines maximum tolerable deviations for linearity, oxygen cross-sensitivity, and response factors for selected compounds.

• Regarding FID analysis, gas and gaseous substances are defined as those that pass through a suitable filter heated to 150 ± 10 [°C].

8.1.3 Sampling and Gas Sample Processing

• In cement plants, gases and gaseous organic substances are sufficiently homo-geneously distributed across the measuring cross-sectional area. Thus gases can be extracted at a fixed point approximately in the center of the measuring area. Filtration in sampling volatile organic compounds generally serves to pro-tect the measuring devices.

• To prevent condensation and adsorption all tubing and system components are heated to 180 [°C]. Experience shows that temperatures below 180 [°C] in cer-tain components of the measuring train (e.g. fine filter) can allow depositions that falsify measurements. The tubing between the filter and FID instrument is to be heated, kept as short as possible, and made of stainless steel or PTFE. Figure 10 shows a schematic diagram of an FID measuring system.

54/58

Figure 10: Sampling and measuring with FID

1 Heated filter (180 [°C] ± 10 [°C]) 2 Heated tubing 3 Flame ionization detector (FID) 4 Data recording

8.1.4 Calibration

• For determining volatile organic compounds, the FID is to be calibrated using a compound of propane and nitrogen that includes a concentration of approx. 80 [%] of the measuring range, or the determining critical concentration. Pure nitro-gen is to be used as the blank gas. Calibration must include the entire gas sam-ple system – extraction device, filter, tubing, etc. If the instrument is calibrated directly (via a separate calibration gas port), afterwards the entire gas-sample path must be checked with both blank gas and calibration gas.

• The response will be influenced by oxygen when using certain devices or fuel gases. If the oxygen sensitivity of the measuring device is known precisely enough, such cross sensitivity can be corrected computationally. But this leads to greater measurement uncertainty, so the calculations must be documented in detail in the measuring report.

• EN12619 prescribes that oxygen cross-sensitivity must be less than 0.8 [mgC/m3] for the measuring region of 0 [mgC/m3] to 20 [mgC/m3] and the total effect of all interferants must be less than 1 [mgC/m3] [8-1].

8.1.5 Accounting for Moisture

FID units are generally calibrated using dry calibration gases, whereas sampling normally involves moist exhaust gases. Thus during evaluation, results must be cor-rected to dry conditions. This requires that water content of the exhaust gas is known exactly enough, or determined parallel to FID measurement.

55/58

8.1.6 Evaluation

Chapter 8 provides detailed information on evaluation in general. The following sec-tion covers only method-specific topics. For measuring volatile organic compounds (VOC) in emissions, the response is converted to a concentration of total carbon, using formula (1) and/or (2).

M

)C(rPGVOC V

MCNSC

⋅⋅= ( 1 )

S61.1CVOC ⋅= ( 2 )

CVOC VOC concentration [mgC/m3]

without accounting for the response factor S Measured response (signal) of the calibrated FID [ppmv] CNPG Carbon number in calibration-gas molecules (propane CNPG = 3) Mr(C) Molar mass of carbon: 12.01 [kg/kmol] VM Molar volume of ideal gas: 22.4 [m3/kmol]

The conventions defined above result in the following: Measurement uncertainty in determining VOCs is relatively large compared with other measurement procedures. Measurement uncertainty: ± 20 [%], at least ± 2 [mg/m3]

8.2 Benzene

NIOSH method 1501 [8-2] can be used for non-continuous benzene (benzol) meas-urement in cement-plant exhaust gases. This method is based on adsorptive en-richment in activated carbon followed by liquid desorption. The method is also suit-able for the following compounds: cumene, a-methylstyrene, styrene, vinyltoluene, p-tert-butyltoluene, ethylbenzene, naphthalene, toluene, and xylene. Sampling The water must be removed prior to absorption by activated carbon. Figure 11 shows the scheme of an example sampling system.

56/58

Figure 11: Sampling system for benzene

1 Heated gas-extraction tube (120 [°C]) 2 Heated filter (120 [°C]) 3 Condensate collector (measuring-gas

cooler, silica gel cartridges, etc.) 4 Gas-sample pump 5 Regulator and shut-off valve 6 Activated carbon tube 7 Gas volume meter

Adsorption in activated carbon at a flow of 0.5 to 1.5 [l/min] up to a maximum vol-ume of 50 - 100 [l]. Breakthrough is not expected at these flows and volumes. Preparation and analysis • Desorption with CS2 • Gas chromatography with flame ionization detection or mass spectrometry

8.3 Polychloridized Dioxin and Furan

8.3.1 Reference Method

EN 1948, pages 1 to 3 [8-3], describes the reference method for determining the mass concentration of polychloridized dibenzo-p-dioxin and di-benzofuran in ex-haust gases. This standard consists of 3 parts: • Page 1: Sampling • Page 2: Extraction and Purification • Page 3: Identification and Quantification

57/58

Table: International Toxicity Equivalence Factors (I-TEF)

Dioxin Congener I-TEF Furan Congener I-TEF 2,3,7,8-TCDD 1 2,3,7,8-TCDF 0.1 1,2,3,7,8-PeCDD 0.5 2,3,4,7,8-PeCDF 0.5 1,2,3,7,8-PeCDF 0.05 1,2,3,4,7,8-HxCDD 0.1 1,2,3,4,7,8-HxCDF 0.1 1,2,3,6,7,8-HxCDD 0.1 1,2,3,6,7,8-HxCDF 0.1 1,2,3,7,8,9-HxCDD 0.1 1,2,3,7,8,9-HxCDF 0.1 2,3,4,6,7,8-HxCDF 0.1 1,2,3,4,6,7,8-HpCDD 0.01 1,2,3,4,6,7,8-HpCDF 0.01 1,2,3,4,7,8,9-HpCDF 0.01 OCDD 0.001 OCDF 0.001

Of a total of 70 dioxin isomers, 7 individual dioxin congeners (with chlorine substitu-tion at positions 2,3,7,8) are identified and quantified. Of a total of 140 furan iso-mers, 10 individual furan congeners (with chlorine substitution at positions 2,3,7,8) are identified and quantified. The international toxicity equivalent (I-TEQ) for these 17 compounds is calculated using the international toxicity equivalence factors (I-TEF) given in the table. Normal concentrations of these compounds are in the ultra trace range ([ng/m3]). This demands thorough validation of methods by every user.

8.3.2 Summary of the Methods

8.3.2.1 Sampling (Page 1)

Page 1 describes three different sampling methods that are considered equal: Filter/cooler method (LAGA method) Configuration: probe / gas-extraction tube / filter / cooler / condensate flasks / two-stage adsorber / pump / volume measuring device (with or without partial streams) Dilution method Configuration: probe / gas-extraction tube / prepared dilution air / mixing chamber / filter / two-stage adsorber / pump / volume measuring device Cooled extraction tube Configuration: probe / gas-extraction tube (cooled) / condensate flasks / two-stage adsorber / filter / pump / volume measuring device Orther important sampling factors: • Isokinetic sampling • Matrix measuring • The spike in the first enrichment stage (13C12-marked components) is used to

check the sampling. This value is not considered in quantification. • Sampling duration approx. 4 to 8 hours

58/58

8.3.2.2 Processing (Page 2)

• PCDD/PCDF is determined based on quantification by the isotope dilution method using GC/MS. 13C12-marked 2,3,7,8-chlorine substituted PCDD/PCDF congeners are added in different stages of the overall method.

• In a first phase the analytes are extracted from the sampling equipment and col-lecting phases using various solvents.

• The raw extracts gained in this way are first concentrated and then purified by complex liquid chromatographic methods. The standard includes examples of such methods, but prescribes only the quality criteria to be achieved.

8.3.3 Analysis (Page 3)

• The purified extracts are analyzed using high-resolution gas chromatography with high-resolution mass spectrometric detection. Quantification is done by ap-plying dilution series and internal standards.

• Losses occurring during extraction and processing are taken into account in this method.

8.3.4 Characteristics

Characteristics depend greatly on the sampling matrix. For the validation measure-ments during the development of standards, limits of detection were determined in the region [pg/m3].

8.4 References

[8-1] EN 12619; Stationary source emissions - Determination of the mass

concentration of total gaseous organic carbon at low concentrations in flue gases - Continuous flame ionisation detector method (1998)

[8-2] NIOSH Manual of Analytical Methods, 3rd Ed., US Department of Health and Human Services, National Institute for Occupational Safety and Health, Cincinnati, USA, (1994)

http://www.cdc.gov/niosh/nmam/nmammenu.html [8-3] EN 1948, pages 1 to 3; source emissions - Determination of the mass

concentration of PCDDs/PCDFs; 1997-05 Page 1: Sampling Page 2: Extraction and Purification Page 3: Identification and Quantification

Emission Monitoring and Reporting (EMR) Guidelines for ... · PDF file(EMR) Guidelines for ......

Documents

Transcript of Emission Monitoring and Reporting (EMR) Guidelines for ... · PDF file(EMR) Guidelines for ......