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University of Edinburgh , School of Engineering, Edinburgh
SCCS – Scottish Carbon Capture and Storage Centre
Process Simulation in Edinburgh
Carbon Capture GroupHyungwoong Ahn, Maria-Chiara Ferrari, Stefano Brandani
CCS Systems Workshop, 30th Jan., 2013
Our interests lie in• Post-combustion capture
a) Adsorption process
b) Membrain process
c) Amine process
d) Carbonate Looping process
e) CFB process with amine-functionalised sorbent
• Pre-combustion capture
a) Selexol process
b) Membrane process
• Process Integration
a) IGCC - Shell/GEE gasifier, Selexol, WGSR, Claus Plant, HRSG,,,
b) Coal-fired boiler power plants with capture units
c) Co-generation of power/H2 from coal gasification
d) CO2 VSA process for SMR H2 plant
e) Cement plants integrated with capture units
Research Projects
£2,461,089Gas-FACTS: Gas-Future Advanced Capture Technology Options – Consortium
proposed by Cranfield, Edinburgh, Imperial, Leeds and SheffieldEP/J020788/1CoI
£1,111,261AMPGas – Adsorption Materials and Processes for Carbon Capture from Gas-Fired
Power PlantsEP/J02077X/1PI
£100,199Carbon Capture in the Refining Process (First Grant)EP/J018198/1PI
€252,000Offshore Gas Separation (with UFC & Malaga)IRSES-OFFGASPI
£190,000Development of an IGCC process with H2 Production (with Yonsei University –
South Korea)KETEPPI
£194,000Next Generation in Carbon Capture Technology - led by CostainETI NGCTPI
PI EP/G062129/1Innovative Gas Separations for Carbon Capture (with St Andrews, Cardiff, Imperial
College, Manchester, University College London)£2,081,429
CoI EP/G02037X/1 Carbon Capture and Storage Interactive: CCSI – Edinburgh £113,159
CoI EP/F034520/1Science & Innovation Award - Carbon Capture from Power Plant and Atmosphere
(capacity building with HWU)£4,049,919
PI EP/I010939/1 FOCUS – Fundamentals of Optimised Capture Using Solids (in collaboration with
North China Electric Power University, Beijing)£644,440
CoI EP/I016686/1 Carbon Nanotube for Carbon Capture £247,913
PI
US-DOE Project
DE-FC26-
07NT43092
Carbon Dioxide Removal from Flue Gas Using Microporous Metal Organic
FrameworksUS$458,000
Approximately £4,000,000 of external funding to the group.
CySim: Adsorption Cycle SimulatorModular simulator for general adsorption processes
• Units: adsorption column, valves, …
• Arbitrary number and connection of units
• Tailored discretisation schemes
• Acceleration of convergence to CSS
Event name 4
Complete model
Non-Isothermal: 1T
Non-Isothermal: 2T
Non-Isothermal: 3T
Isothermal
No Pressure drop
Pressure drop
No Film resistance
Film resistance
NoMacropore
MacroporeLDF
MacroporeDiffusion
MicroporeLDF
MicroporeDiffusion
MicroporeEquilibrium
Dusty Gas Model
MS-Surface diffusion
Complete model
Non-Isothermal: 1T
Non-Isothermal: 2T
Non-Isothermal: 3T
Isothermal
No Pressure drop
Pressure drop
No Film resistance
Film resistance
NoMacropore
MacroporeLDF
MacroporeDiffusion
MicroporeLDF
MicroporeDiffusion
MicroporeEquilibrium
Dusty Gas Model
MS-Surface diffusion
Simulation of Skarstrom Cycle
Event name 5
Feed
Pressurisation
Adsorption
Evacuation
PE
Purge
PE
Column 2
Column 1
Skarstrom PSA/VSA cycle
• 2 columns
• 6 step cycle with two-sided
pressure equalisation
Use of CySim in UniSim
6
• Matlab-based integration (COM- Interface)
• Molar flow rate, compositions, temperature
and pressure values are taken from UniSim
• Matlab runs CySim, provides inlets and collects
outlets.
• The compositions, temperatures and pressures
calculated in CySim are returned to Unisim.
Base schematic diagram
Interface of CySim in Unisim
Automated fitting of ZLC data
Event name 7
Automated fitting
•Simulate the ZLC system with CySim: valves, ZLC and detector
•Apply an optimisation routine to minimise the least-square error between
the experimental data and the simulation
• First, fit the blank
• Second, fit multiple experiments at once
• Investigate different equilibrium and mass transfer models
DP-PSA: Analysis of Experiments
Event name 8
Compare and analyse experimental data with CySim
• Isothermal model usually sufficient for large cycle times >10s
• Temperature has an effect on the pressure profile for faster cycles
4s cycle time
0.0
0.2
0.4
0.6
0.8
1.0
0 200 400 600 800 1000 1200 1400 1600
CO
2 m
ole
frac
tion
Time [s]
Event nameEvent name
CO2 PVSA Simulation (gPROMS)• gPROMS code: Simulated a Skarstrom cycle with PE steps. All the results have
been cross-checked with in-house simulator results.
• Our code uses more rigorous H/M balances derived by our group than a
commerical software.
• When applied to power plant flue gas, the adsorption unit should have more
than two stages to achieve high CO2 purity and recovery at the same time.
0 5 10 15 20 2548
50
52
54
56
58
60
62
64
CO
2 P
urity
0 5 10 15 20 2578
80
82
84
86
88
90
92
94
96
Number of cycles
CO
2 Rec
over
y
Purity
Recovery
Simulation results of 2-column 4-step CO2 VSA
Equilibrium Theory- based CO2 VSA Simulator (ESIM)
Event name 10
• CO2 adsorption is mostly driven by equilibrium compared to axial dispersion and
adsorption rate. By neglecting the axial dispersion term, the mass balance
becomes a hyperbolic equation.
• ESIM can capture the shock (discontinuity) while the other simulators cannot due
to numerical dispersion.
Membrane_UoE
• Aim: formulation of models able to predict the separation through
industrially available membrane modules
• Analysis of the most common flow-patterns and formulation of the
mass balance through the system
• Implementation in C language linked to the SUNDIALS libraries
• Set of differential equations reduced to a nonlinear system by using
both Finite Differences (FD) and Orthogonal Collocations on Finite
Elements (OCFEM)
• Advantages of OCFEM: more stable and quicker resolution (up to
50% of the simulation time)
11
Serban et al. https://computation.llnl.gov/casc/sundials/main.html. (2009)
Modelling: partial pressure profiles
Example of countercurrent
partial pressure profile
2D cross-flow model:
example of permeate partial
pressure profile
12
010
2030
0 5 10 15 20 25 30
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
Width [-]Length [-]
CO
2 par
tial
pre
ssu
re [
atm
]
dA
Feed
Permeate
Retentate
Sweep
Integration into UniSim Design®• Complete integration of the simulation tools previously created into
Honeywell UniSim® Design (R400) based on a C++ interface
• Possibility of integrating new unit operations into the simulation
environment thanks to the so-developed interface
• Davide Bocciardo has been awarded as winner of the 2012 Honeywell
UniSim Design Challenge for the innovative application of UniSim® Design
13
Honeywell EMEA Conference, Istanbul, November 2012
Integration of Cement Plant with Ca-looping Process
14
• An exemplary cement plant has been simulated using UniSim Design.
• CO2 is selectively captured by CaO in the carbonator.
• Purge stream (mainly CaO) from capture unit can be added to kiln feed.
UniSim User Defined Ops. - Carbonator Unit
15
• A user defined operation to simulate ‘carbonator’ can be used as one of
unit operations in UniSim like reactors, distillation column, and so on.
Unisim User Unit Operation as a Carbonator The interface of carbonator in Unisim
Carbonator Model
• Stream properties
• Carbonator specifications • Capture efficiency
• Reactor volume
• Pressure drop
Amine Process Configuration Study
Many other process configurations are possible.
1.0200.330.693.286
1.100.250.230.622.955
1.000.080.330.592.804
1.0000.330.673.193
1.0100.330.683.242
0.90
1.00
0.99
1.08
Total Energy
Consumption
[MJe/kgCO2]
0.46
0.59
0.66
0.75
Equivalent Reboiler
Duty [MJe/kg CO2]
0.11
0.08
0
0
Additional Work
[MJe/kg CO2]
9
8
7
1
0.332.20
0.332.80UOE design
0.333.15
0.333.56
Existing
Existing
CO2 compression
Work
[MJe/kg CO2]
Reboiler duty
[MJth/kg CO2]Configuration
• The energy consumption (mainly, steam in the stripper reboiler) in amine process
can be reduced by modifying amine process configuration.
Stripper overhead compression Heat recovery Split amine flow
Honeywell UniSim Design R400 environment BR&E ProMax environment
IGCC Simulation
• Developing a process simulation of IGCC power plants with and without carbon
capture using UniSim Design R400 and BR&E ProMax.
• The simulation includes gasifier, syngas cooler, WGSR, single-stage or dual-stage
Selexol units, gas turbine, HRSG, sour stripper, Claus plant…
• Comparison of performances of IGCC plants designed based on different
gasification technologies.
Henry Constants
T=294 K
0
500
1000
1500
2000
2500
3000
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
CO2 mole fraction [-]
P [
kPa]
UniSim
Xu et al.
T=294 K
0
500
1000
1500
2000
2500
3000
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8CO2 mole fraction [-]
P [
kPa]
UoE
Xu et al.
Xu, Y., R.P. Schutte, and L.G. Hepler, Solubilities of carbon dioxide, hydrogen sulfide and sulfur dioxide in physical solvents. The Canadian Journal of
Chemical Engineering, 1992. 70(3): p. 569-573.
• New set of parameters for Henry constants of CO2 and H2S absorption
into Selexol have been found and applied to UniSim simulation.
ETI-funded Project• Our independent IGCC simulation has been developed to evaluate
the NGCT technology. It confirmed the quantative performance gain of new process over the existing Selexol unit (+1.8% in net power efficiency at 95% capture).
Thank you for your attention
