Presentation given by Sergey Martynov of University College London on "CO2QUEST - The effect of impurities on compression and pipeline transportation of CO2" at the EC FP7 Projects: Leading the way in CCS implementation event, London, 14-15 April 2014

1. CO2QUEST
The effect of impurities on
compression and pipeline
transportation of CO2
Sergey Martynov
University College London
http://www.co2quest.eu

2. 2CO2QUEST
CO2 compression and transportation in CCS
Transportation and injection into geological formations of large
amounts of CO2 requires compression of captured stream to dense-
phase or supercritical states
P > Pcr= 73 bar
P (1km) = 100 bar

3. 3CO2QUEST
In case of CO2 sequestration, where CCS brings no direct
commercial benefits (unlike in EOR projects), the question is
What are the costs of CO2 compression and transportation?
• 100 MWe coal-fired power plant emits ~ 1Mt CO2 per year
• Compression of 1 Mt/a CO2 from 1 to 150 bar pressure: ~ 10 MW
Hence, the CO2 compression penalty is ~ 10%
Any improvements in design and operation of compression,
transportation and injection will help to reduce the cost of the
technology
CO2 compression and transportation in CCS – costs

4. CO2 Transport – tasks in CO2QUEST
Use mathematical modelling to
evaluate the impact of
impurities on compression
and the pipeline transportation
• Thermodynamic analysis of
the CO2 compression –
schemes with the minimum
power requirements
• Thermo-hyrdaulic analysis
of CO2 flows in pipelines –
minimum costs of
transportation
4CO2QUEST

5. CO2 Transport – tasks in CO2QUEST
Use mathematical modelling to
evaluate the impact of
impurities on compression
and the pipeline transportation
• Thermodynamic analysis of
the CO2 compression –
schemes with the minimum
power requirements
• Analysis of CO2 flows in
pipelines in various regimes
of operation
5CO2QUEST

6. 6CO2QUEST
1. Review of various compression strategies,
including isothermal and isentropic multi-stage
compression with intermediate cooling.
2. Thermodynamic analysis of the impact of
impurities in CO2 streams from different sources
on the compression power requirements
Analysis of CO2 compression – methodology

7. 7CO2QUEST
Pipeline transportation/ Storage
Compression of
captured/ purified CO2
Vapour
Liquid
CO2 compression for CCS
Super-
critical fluid

8. Vapour
Liquid
Super-
critical fluid
8CO2QUEST
CO2 compression strategies in p-h diagram
Gas compression
followed by
liquefaction +
liquid pumping
Conventional multi-
stage gas compression
centrifugal compressors
Shock-wave
turbo-
compressors

9. 9CO2QUEST
Compression and refrigeration pumping
Witkowski, A., et al., 2013. Comprehensive analysis of pipeline transportation systems for CO2 sequestration.
Thermodynamics and safety problems. Energy Conversion and Management 76, 665-673.
8-stages integrally geared
compressor with inter-cooling
Ramgen’s supersonic
two-stage axial
compressorMAN Turbo
netl.doe.gov
CO2 compression processes – reference data
The study is based on the process data for industrial compressors
from the literature

10. 10CO2QUEST
Compression power:
Isothermal compression :
Isentropic compression:
Inter-stage cooling heat:
P = pressure
G = mass flow rate
η = efficiency
v = specific volume
h = enthalpy
Z = compressibility factor
γ = Cp / Cv
∫= vdpGw
1
2
ln
P
PZRTG
wIsothermal
η
=
( )










−





−
=
−
1
1
1
1
2
γ
γ
γη
γ
P
PRTGZ
wIsentropic
)( 23 hhGQ ngIntercooli −=
Thermodynamic analysis of CO2 compression

11. 11CO2QUEST
Composition of CO2 streams
Component Oxy-fuel Pre-comb Post-comb
CO2 (v/v %) 79.47 98.066 99.664
O2 (v/v %) 6.0 - 0.0035
N2 (v/v %) 9.8 0.02 0.29
Ar (v/v %) 4.47 0.018 0.021
NO2 (ppmv) 709 - 38.8
SO2 (ppmv) 800 700 67.1
H2O (ppmv) 100 150 100
CO (ppmv) 50 1300 10
H2S (ppmv) - 1700 -
H2 (ppmv) - 15000 20
CH4 (ppmv) - 110 -

12. 12CO2QUEST
Properties of CO2 mixtures
0
20
40
60
80
100
120
260 280 300 320
Pressure(bar)
Temperature (K)
Pure CO2
Oxy-fuel
Pre-combustion
Post-combustion
Vapour-liquid equilibrium in P-T and p-density diagrams for oxy-fuel,
pre-combustion and post-combustion mixtures. Calculations using
Peng-Robinson equation of state in REFPROP.

13. Thermodynamic paths for 8-stage compression/intercooling of
pure CO2 (a), oxy-fuel (b), pre-combustion (c), and post-combustion (d) mixtures.
Pin= 1.51 bar, Pout=166.4 bar, Tin = 311 K, η=80%, Pr=1.8 13CO2QUEST
Compression of impure CO2 – case study

14. 14CO2QUEST
0
10
20
30
40
50
60
70
80
Power(kW)
Compression
Cooling
Comparison of compression and cooling power requirements for
8-stage compression of CO2 streams of different purity (G=0.156 kg/s)
Effect of impurities on compression work

15. CO2 Transport – tasks in CO2QUEST
Use mathematical modelling to
evaluate the impact of
impurities on compression
and the pipeline transportation
• Thermodynamic analysis of
the CO2 compression power
requirements
• Thermo-hyrdaulic analysis
of CO2 flows in pipelines
15CO2QUEST
– the impact of impurities on the pipeline
capacity, pressure drop, fluid phase
– recommend models to use in techno-
economic analysis of CCS networks

16. 1CO2QUEST
1. Friction and heat transfer
(subsea, buried and insulated
pipelines)
2. Pipeline inclination
3. Auxiliary equipment (fittings,
bends and branches, junctions,
valves and pumps)
4. Variation of properties of CO2
stream with p, T and impurities
Non-isothermal steady-state flow model
1D compressible flow model accounting for :
Cross-section of a buried
and insulated pipeline

17. 17CO2QUEST
Density of CO2 fluid at a supercritical pressure
Pipeline pressure drop – preliminary analysis

18. 18CO2QUEST
Pressure(bar)
Distance (km)
Over-ground
pipeline
Diameter 16’’
Length 240 km
Inlet p = 110 bar
Inlet T = 50oC
Flowrate 35 kg/s
Increasing
fluid density
What is the accuracy of integral pressure drop models?
Pure CO2
Post-combustion
Oxy-fuel
Pre-combustion
Pipeline pressure drop – simulations
Correlation between pressure drop and density is in
qualitative agreement with the Darcy-Weisbach equation,
attractive for use in techno-echonomic studies

19. 19CO2QUEST
Parameter Value Unit
Pipe internal diameter 0.8 (m)
Pipe wall thickness 17.25 (mm)
Pipe wall roughness 0.0475 (mm)
Pipe length 1 - 60 (km)
Pipe axis below the ground
surface
1.4 (m)
Soil thermal conductivity 1.21 (W/m/K)
Ambient heat transfer
coefficient
5 (W/m2/K)
Fluid pressure at pipe inlet 110 (bar)
Velocity at the pipe inlet 3 (m/s)
Flow conditions for the pipeline pressure drop study
Assessment of integral pressure drop models
* ρ and cP are evaluated at the pipe exit
D
L
A
Gf
p 2
2
2ρ
=∆
D
L
cu
q
TT
p
w
in
⋅
+=
ρ
4
An integral flow model *:
Rigorous differential
equations flow model: op∆ oT
Pipe exit temperaturePipe pressure drop

20. 20CO2QUEST
Ratio of the pressure drops
calculated using the integral and
the rigorous flow models
D
L
A
Gf
p 2
2
2ρ
=∆
D
L
cu
q
TT
p
w
in
⋅
+=
ρ
4
An integral flow model:
Rigorous differential
equations flow model: op∆ oT
Assessment of integral pressure drop models
Absolute difference in the pipe exit
temperatures predicted using the
two flow models
Pipe exit temperaturePipe pressure drop
opp ∆∆ / )(KTT o−
~5%
~10%

21. 21
Summary
CO2QUEST
• Thermodynamic analysis of power requirements for
compression of impure CO2 for the identified
compression strategies
• Recommendations for calculation of pressure drop in
pipelines transporting CO2 streams

22. 22
Acknowledgements
The research leading to the results described in this
presentation has received funding from the European Union 7th
Framework Programme FP7-ENERGY-2012-1-2STAGE under
grant agreement number 309102.
The presentation reflects only the authors’ views and the European Union is
not liable for any use that may be made of the information contained therein.
CO2QUEST
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