Mercury in Cement Clinker Production - Behaviour and...
Transcript of Mercury in Cement Clinker Production - Behaviour and...
Mercury in Cement Clinker Production -
Behaviour and Abatement of Emissions
June 21st, 2016 | Reinhard Beilmann | tkIS
Peru, 1st Conference – Determination and Abatement of Mercury Emissions
2 | June 21st, 2016 | Mercury in Cement Clinker Production | Reinhard Beilmann tkIS
Behaviour of heavy Metals in Cement Kilns
Volatility
Arsenic
Nickel
Chrome
Copper
Cobalt
Cadmium
Lead Thallium Mercury
non low light high
Emissions
solid, (bounded) bounded
and gaseous
Enrichment on filter dust (%)
0
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Mercury – Emission Measurements at German Cement kilns
Limit: 30 μg/Nm³
Exceptional Limit: 50 μg/Nm³
if caused by Raw Material
Source: VDZ 2008
34 yearly averages from
continuous control and 112
measurements from
44 plants. 5 Values below detection
limit.
Measurement
Concentr
atio
n in m
g/N
m³
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Mercury – Emission Measurements at US Cement kilns
Source:
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Mercury Cycle in Cement Kilns – direct operation
Clinker
Dust Hg
Hg
Silo
Hg
Hg-Sources: Fuels + Raw Meal
Direct operation:
High mercury emissions
Adsorption on the dust (depends on the temperature)
Raw Meal
Fuels
Silo
Filter
Mercury evaporation from Raw Meal
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Mercury Cycle in Cement Kilns – compound operation
Clinker
Hg
Hg
Silo
Hg
Hg-Sources: Fuels/Raw Materials/Meal
Compound operation:
Enrichment in the outer cycle (depending on mill type, amount of kiln gas used for grinding)
Lower mercury emissions
Raw Meal
Fuels
Raw Materials
Dust
Filter
Silo
Bypass
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Mercury - Typical Emission Behavior
Compound Operation Compound Operation Direct
Operation
Stack
Source: tkIS
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Reduce Mercury input into the System
Primary Mercury Abatement Technologies
Fuels:
could be possible
Raw Materials: might be possible if a minor component is the source but hardly achievable if the Limestone Quarry is the Source
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Primary Mercury Abatement Technologies
Quecksilberabscheidung in Abhängigkeit
von der Gastemperatur
80 100 120 140 160 180 200 220 0
25
50
75
100
Gas Temperature in °C
Mercury Removal in %
Exhaust gas cooling as a Precondition
Dust shuttling (typically in direct operation)
Filter-dust
back to process
(Silo)
Filter-dust to
Clinker grinding or disposal
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Primary Mercury Abatement Technologies
Effect of Dust shuttling in direct operation
Hg Emission without Dust Shuttling
compound operation
clean gas temperature cle
an
ga
s te
mp
era
ture
(°C
)
Hg
co
nce
ntr
atio
n c
lea
n g
as (
µg/N
m³)
Hg concentration clean gas
Hg Emission with Dust Shuttling in dircet operation
compound operation
clean gas temperature
cle
an
ga
s te
mp
era
ture
(°C
)
Hg
co
nce
ntr
atio
n c
lea
n g
as (
µg/N
m³)
Hg concentration clean gas
Source: ZKG 11 2001, 591-601
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Secondary Mercury Abatement Technologies: ACI
Dust Shuttling with ACI (typically in Direct Operation)
Filter-dust
back to process
(Silo)
Filter-dust to
Clinker grinding or disposal
Activated Carbon - Injection
approx. 30-40mgAC/Am³ @3000tpd Clinker 12-15kg AC/h
approx. 10 t/h ; 0,15% C @3000tpd Clinker and 8%Dust related to Clinker
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Expected Hg-Removal with ACI from Industrial Trials (Landreth and Hardtke ZKG 11 2012, 46-51)
1 lb/MMacf equal to approx. 16mg/Nm³
Secondary Mercury Abatement Technologies: ACI
Removal efficiency generally confirmed by plant operations
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ACI with two Baghouses
Filter-dust
back to process
(Silo)
landfill
recycling
…
Secondary Mercury Abatement Technology: ACI
• improved efficiency
• pure activated carbon
• high investment
Activated Carbon - Injection
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Secondary Mercury Abatement Technologies: ACI
ACI - Hg-Removal Experience with two Baghouses
Source: Mercury Reduction - The Plant Experience
Terry Kerby, IEEE 2016
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Filter-dust
back to process
(Silo)
Hg-Desorption
Secondary Mercury Abatement Technology – ACI with
Hg-Desorption from Dust
Activated Carbon - Injection
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Secondary Mercury Abatement Technology -
Thermal dust treatment for Hg-Desorption by TKIS
o Waste minimization: High Hg Enrichment factor
o Extremely compact design, mobile full scale
demonstration plant possible
Product
Product Heat
Exchanger
Feed
Cyclone
Reactor
Clean Gas ACF
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Indirectly
heated Rotary kiln
for thermal Treatment
of EP-Dust
Industrial Installation in 1992
Secondary Mercury Abatement Technology -
Thermal dust treatment for Hg-Desorption by TKIS
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Mercury Online Measurement
Big discussions about accuracy in cement process in Germany.
Very low concentration (µg/Nm³)
Alternating concentrations Different measurement ranges in compound and direct operation
Interferences (newer analyser with underground compensation)
Hg
HgCl2
Only detection of elemental mercury (photometer)
Ionic mercury hast to be converted to the elemental form
Older analysers uses a converter material → Deactivation by the sample gas of the kiln exhaust
Newer analysers: Thermal conversation
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Conclusion Mercury in Cement Kilns
• Mercury is completly volatile in the preheater
• During mill down times (direct operation), the outer cycle is partly unloaded
• Dust Shuttling is the first step to reduce Mercury Emission
• Low temperatures in the filter are advantageous
• Activated Carbon Injection may further reduce Emissions
• Plant specific emissions and the maximum allowable emission determine the suitable
abatement technology
Mercury in Cement Clinker Production –
Behaviour and Abatement Strategies
Any questions?
Thank you for your attention!