CO2 Processing Unit for Oxy-Fuel
Fired Rotary Cement Kiln
Presenter: Bill Mahoney
Authors: Kenneth Burgers, Stefan Laux, Minish Shah
175 East Park Drive, Tonawanda, NY 14150, USA
3rd Oxyfuel Combustion Conference
9-13 September 2013 – Ponferrada, Spain
Copyright
© 2013 Praxair Technology, Inc. All rights reserved.
1 | 9/11/2013
The ecra CCS Study

Carbon Capture and Storage
study by the European Cement
Research Academy (ecra)

Multi-phase research initiative to study the implications for capturing carbon dioxide at
cement plants and develop cost estimates
– Post-combustion capture technology
– Oxy-fuel combustion

Phase III, Work Package A5: “General Layout of a Flue Gas Conditioning Facility for
Oxy-fuel Operation of a Rotary Cement Kiln”

This presentation focuses on the design and performance of the
CO2 Processing Unit (CPU)
2 | 9/11/2013
Oxy-Fuel Combustion for CCS
100%

Oxy-fuel combustion reduces flue gas volume

CO2 rich (>80% dry basis) flue gas minimizes purification costs

Potential for fuel savings

Improved heat transfer  increased productivity

Flue gas recirculation used to manage combustion temperatures
Air
Air Separation
Luftzerlegung
Unit (ASU)
Fuel:
Methane
N2
Nitrogen
Flue Gas Recirculation
Vent of Non-Condensable
Gases (N2, Ar, O2, Traces)
Oxygen
Flue gas
(CO2- rich)
Fuel
Raw meal
ClinkerKlinker
Burning
brennprozess
Process
CO2 Processing
Unit (CPU)
Clinker
Water
3 | 9/11/2013
H2O
CO2
CO2
26%
O2 H O
2
CO2
Air vs Oxy-Fuel
Flue Gas Volume
Work Package A5

Compress and purify CO2-rich flue gas from a 3000 t/d oxy-fuel cement kiln for pipeline
transport at supercritical pressure

Process variations studied
– Inlet CO2 concentration to quantify effect of air inleakage
– Outlet CO2 purity to quantify effect of pipeline requirements

Major Deliverables
– Process design and utility requirements
– Conceptual layout
– Budgetary capital costs (+/- 30%)
4 | 9/11/2013
Air-Fuel Cement Process
Exhaust
cleaning
Raw Material
Raw Mill
Preheater
Fuel
Fuel
Preparation
Precalciner
Vent
Rotary Kiln
Cooler
Clinker
Air
5 | 9/11/2013
Oxy-Fuel Cement Process
Heat
exchanger
Bag filter
CO2 rich
flue gas
CO2 purity
specification?
CO2-Storage
Exhaust
cleaning
Transport
Raw Material
Optimum excess oxygen
for combustion?
Vent
CO2 Purification
Raw Mill
Preheater
Air Ingress
Fuel
Air
Ingress
Water
Fuel
Preparation
CO2 Compression
Air Ingress
Level of
air ingress
into process?
Precalciner
Rotary Kiln
Cooler
Air Ingress
Air
Separation
Unit
6 | 9/11/2013
Clinker
Oxygen
Nitrogen
Gas Mixing
Best O2 purity?
Flue Gas
Recirculation
Cooler
Air
CPU Process Schematic

Technology adapted from industrial CO2 process

Auto-refrigeration with partial condensation or distillation

Inert gases (N2, Ar, O2) are removed and vented

CO is removed using Catox
FG Cooler/
Condenser
Vent
Cold Box
Vent
Catox
Compressor
H2O
Carbon
bed
H2O
SOx/NOx/
Removal
CO2-Rich
Oxyfuel
Flue Gas
Condensate
Cold
Box
Dryer
Hg
Dilute acid
Condensate
7 | 9/11/2013
Expander
> 95%
CO2
Design Basis
Study Case
Air
Intrusion
CO2 Purity mol%
Type of CO2
Processing Unit (CPU)
1
2%
> 95%
Partial Condensation
2
4%
> 95%
Partial Condensation
3
6%
> 95%
Partial Condensation
4
6%
> 99.5%
Distillation
8 | 9/11/2013
Inlet Flue Gas Conditions
Case No.
1
2
3
4
2%
4%
6%
6%
Partial
Condens.
Partial
Condens.
Partial
Condens.
Distillation
Vol Flow, Nm3/h (dry)
56,887
58,971
61,523
61,523
Mass Flow, kg/h
112,232
114,784
118,013
118,013
Temperature, oC
50
50
50
50
Pressure, mbara
1063
1063
1063
1063
CO2
90.43%
86.84%
82.97%
82.97%
N2
4.13%
7.44%
11.09%
11.09%
O2
2.67%
2.98%
3.26%
3.26%
Ar
1.41%
1.37%
1.34%
1.34%
H2O
1.00%
1.00%
1.00%
1.00%
Air Intrusion
CPU Type
Composition, mol%
9 | 9/11/2013
Minor Flue Gas Components
Component
Inlet Concentration
Dust
< 10 mg/Nm3 stp
CO
< 1000 mg/Nm3 stp
NOx
< 1200 mg/Nm3 stp
SOx
< 400 mg/Nm3 stp
Hg
< 0.085 mg/Nm3 stp
HCl
< 5 mg/Nm3 stp
Mercury and HCl levels assumed by Praxair
10 | 9/11/2013
Key Assumptions/Specifications

CO2 outlet pressure
138 bara

Cooling water inlet temperature
18 C

Cooling water outlet temperature
26 C

Steam pressure
22 bara

Currency Conversion
€ 1.00 = $1.40 US

Cost of Electricity
€ 0.071/kWh

Cost of Steam
€ 21.66/tonne

Cost of Cooling Water
€ 0.028/tonne

Cost of Process Water
€ 0.66/tonne
11 | 9/11/2013
CPU Cost and Performance
Case No.
1
2
3
4
Air Intrusion
2%
4%
6%
6%
Type of CPU
Partial
Condens.
Partial
Condens.
Partial
Condens.
Distill.
Feed CO2 Purity (dry) mol%
91.5%
87.9%
84.0%
84.0%
Product CO2 Purity, mol%
95.8%
95.2%
95.0%
99.9%
CO2 Capture Eff.
93.5%
92.6%
90.3%
90.0%
CO2 Captured, tonnes/day
2353
2320
2255
2248
Relative CPU Power
100
101.5
103
113
CO2 Compression and
Purification Cost , €/tonne of
CO2
€ 23.90
€ 24.60
€ 25.40
€ 27.20
12 | 9/11/2013
Atmospheric Emission Reduction
Case No.
1
2
3
4
Air Intrusion
2%
4%
6%
6%
Type of CPU
Partial
Condens.
Partial
Condens.
Partial
Condens.
Distill.
Atmospheric Emission Reduction
13 | 9/11/2013
CO
99.44%
99.33%
99.28%
99.00%
SOx
99.99%
99.99%
99.99%
99.99%
NOx
99.36%
99.26%
99.12%
98.79%
Hg
>99.9%
>99.9%
>99.9%
>99.9%
Study Conclusions

Between 2250 and 2350 tonnes/day of CO2 at a pipeline pressure of 138 bar(a) can be
captured from a 3000 t/d oxy-fuel cement kiln.

Cost of CO2 compression and purification ranges from about € 24/tonne to about €
27/tonne

CPU is able to maintain CO2 recovery of >90% with air intrusion rates of up to 6%. Cost
increases by about € 1.50/tonne when air intrusion increases from 2% to 6%.

Increasing CO2 from 95% to 99.99% increases cost by € 1.80/tonne
14 | 9/11/2013
Summary

Oxygen combustion is used in many industries, including the cement industry

Air separation and CO2 compression/purification
– Technology is available and impact of oxygen purity can be determined
– Equipment scale is not a challenge
– Tradeoffs exists between investment costs and operating costs (energy)

The integration of oxy-fuel combustion into the cement process is a significant challenge
– Effect on process
– Costs

Sequestration requirements and legal framework need to be defined
15 | 9/11/2013
Questions?
Thank You for Your Attention!
16 | 9/11/2013