View
1.003
Download
0
Category
Tags:
Preview:
Citation preview
Assessment of Hybrid Membrane – Low Temperature Process for Post-Combustion Capture
X. P. Zhang, T. GundersenNorwegian University of Science and Technology, Trondheim, Norway
R. Anantharaman, D. BerstadSINTEF Energy Research, Trondheim, Norway
Presentation Outline
►Background►Gas membrane separation process evaluation►Hybrid Membrane – Low Temperature process►Results and discussion►Conclusion
2
3
Challenges of CCS► Energy: Energy penalty (Electricity, steam……)► Economy: Cost increase (Investment, operational cost…)► Environment: Additional impact (MEA degradation…)
► Industries: Understand the status of energy/mass efficiency, economic performance and environmental impacts;
► Researchers: Provide information to develop new or retrofit old CCS technologies, new material synthesis, process design……
► Decision-makers: Provide a roadmap for the commercialization of CCS
Integration & assessment of CCS ChainMotivation
CO2 capture technologies
4
J. D. Figueroa, T. Fout, S. Plasynski, H. McIlvried and R. D. Srivastava, Int J Greenh Gas Control, 2008, 2, 9-20.
2010 2015 2020
Post-combustion capture
MEA-based systemEconamine FG+KS-1Cansolv process
……Chilled ammonia
1.Ready for Demonstration
MembraneCarbonate-based sorbentsIonic liquidsEnzyme-based systems……
2. Emerging technologies
DOE & NETL
MEA-based capture system
CO2 capture ratio: ~90%, CO2 purity > 95%, Lean solvent: MEA 28.3%(wt)Absorption temp.: 35-50oC., Stripper temp.: 100-120oC
Energy demands:Q1 (Sensible) + Q2 (Reaction) + Q3 (Stripping) + W1 (Blower) + W2 (Pumps)Advanced solvent methods aim to reduce all or parts of these energies
6
Two-stage gas membrane capture process
Energy demands:Q1 (Sensible) + Q2 (Reaction) + Q3 (Stripping) + W1 (Compressors) + W2 (Pumps)
7
Chemical solvent based and Membrane systemsLimitations of chemical solvent based system► Degradation: results in high material costs and high disposal costs;► Additional environmental pollution caused, emissions of NH3, MEA; ► High energy consumption, extraction of LP steam from turbine; ► Auxiliary retrofitting measures or costs in power plants
Hussain, A.; Hagg, M. B. Journal of Membrane Science 2010, 359, (1-2), 140-148. Zhao, L.; Riensche, E.; Blum, L.; Stolten, D. Journal of Membrane Science 2010, 359, (1-2), 160-172.
Some viewpoints on membranes
► Less environmental impact, and small footprint; ► Lower energy requirement (no steam load, but significant shaftwork requirement); ► Ease of scale up, both for grassroot power plants and retrofitting of existing ones► Suitable when high purity gas streams are not vital
8
Tech. DataMembrane model
with PRO/II®
Techno-Economic assessment models
Cost Models 22
( +0.2 )CC(US $ / ton CO )=fluegas CO
VOM TPIm x CR
VOM: Annual variable operating & maintenance costTPI: Total plant investmentCR: Capture ratio
Membrane Models
Flow structure
InputOperational parameters:PressureTemperatureFlow rateGas Composition
Membrane parameters:Membrane areaSelectivityPermeance
OutputCapture ratioCO2 purityGas volumesGas compositions
Parameter optimization
Fick’s lawHagen-Poiselle eq.
Parametric study - membrane process
9
Capture ratio 90%, CO2 purity 90% (mol); CR 90% and XCO2 90%(mol)1-stage with Turboexpander; Excluding CO2 compression; PPermeate 0.05 bar, CO2/N2Selectivity: 150 – 250, CO2 permeance value: 1 - 5 Nm3/m2•bar•hr.
Increasing selectivity will decrease energy consumption and increase area, thus permeance & selectivity should be optimized due to an inverse relationship
0.0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
0.5
0.7
0.9
1.1
1.3
1.5
1.7
1.9
150 170 190 210 230 250 270
E1E2E3E4E5A1A2A3A4A5
CO2/N2 Selectivity
Mem
bran
earea (10
6m
2 )
Specific energy
consum
ption (M
Je/ t C
O2)
Specific equivalent enery consumed with MEA
A B
Per-1
Per-5
Inverse relationship of Area~Power
10
N2
CO2
W1 W2
W3
Total power= W1 + W2 – W3
P1 P2
P1 P0
Trade-off between energy consumption and area
11
Two-stage gas membrane capture process
Influence of parameters on capture cost
12
Energy
Area
Cost
2-stage capture, CO2 purity: 95% (mol); capture ratio: 90%
CO2/N2 selectivity: 70~90
Influence of capture ratio
13
Optimal capture ratio range: 65~70% (50 $ /m2 membrane) 75~80% (100 $ /m2 membrane
Motivation for Hybrid Membrane –Low Temperature Process► Polymeric membranes function ideally as a bulk separation medium► With CO2/N2 selectivities of 50-100 single stage membrane process is not
feasible to attain required CO2 purity (95%) and degree of separation (90%)► Driving force is partial pressure difference across the membrane and hence
significant compression work required for separation Increases exponentially with purity and degree of separation
► Low temperature processes have been the standard for CO2 purification in oxy-combustion cases Efficient process to attain high purity CO2 when feed stream has CO2 concentration
14
Process Block Diagram15
Membrane – LT interface
USC Coal Fired Power Plant16
European Benchmarking Task Force – Reference case ► Power plant: Net electricity 754 MWe (without capture)► Flue gas flowrate: 596.4 Nm3/s (781.8 kg/s)► Flue gas composition: CO2 13.73%, N2 72.86%, O2 3.65%, H2O 9.73% (mol)
Membrane section PFD17
Low Temperature section PFD18
Energy requirement - Membrane19
CO2/N2 selectivity: 70, CO2 permeance: 5 Nm3/m2·bar·hr
Energy Requirement – LT process20
Hybrid processOverall performance
21
Hybrid processOverall performance
22
Comparing performance of processes23
Comparing performance of processes24
CO2/N2 selectivity: 80CO2 permeance: 5 Nm3/m2.bar.hr
Membrane properties
8% improvement over 2-satge Membrane process
Comparing performance of processes25
CO2/N2 selectivity: 200CO2 permeance: 1 Nm3/m2.bar.hr
Membrane properties
Energy penalty nearly the same as MEA case
Conclusions
► Membrane method has weak advantages over MEA process for CO2 capture due to relatively lower capture cost. However, membrane processes have larger energy consumption
► Membrane – Low Temperature hybrid process have lower energy penalty than 2-stage membrane process for high CO2 capture ratios. 8% lower energy penalty at 90% capture
► 2-stage membrane process perform better than the hybrid process at capture ratios below ~80%.
► MEA capture process performs better than the hybrid and membrane processes at 90% capture ratio.
► New membranes optimized for these processes are expected reduce cost and energy consumption.
► Further work: Develop cost models for the low temperature process to optimize overall process design.
26
Acknowledgements
This publication has been produced with support from the BIGCCS Centre, performed under the Norwegian research program Centres for Environment-friendly Energy Research (FME). The authors acknowledge the following partners for their contributions: Aker Solutions, ConocoPhillips, Gassco, Shell, Statoil, TOTAL, GDF SUEZ and the Research Council of Norway (193816/S60).
Recommended