Cryogenic CO2/H2S capture technologies for remote natural gas processing

1
Cryogenic CO2/H2S capture technologies for
remote natural gas processing

• Mehdi Panahi
• Trial Lecture

December 1st, 2011 Trondheim
2

• Outline
• Introduction
• 2. Cryogenic technologies
• Ryan Holmes method
• Controlled freeze zone (CFZ) method
• Cryocell method
• Sprex method
• Twister technology
• 3. Conclusions

3

• Outline
• Introduction
• 2. Cryogenic technologies
• Ryan Holmes method
• Controlled freeze zone (CFZ) method
• Cryocell method
• Sprex method
• Twister technology
• 3. Conclusions

4
CO2 effect on Global warming
Green house gases cause global warming CO2, the
major one

• World energy demand is increasing
• more fossil fuels
• 130 rise in CO2 emissions by 2050
• rise in global average temperature by 6C

Intergovernmental Panel on Climate Change
(IPCC) Emissions must be reduced by 50 to 85
by 2050 if global warming is to be confined to
between 2C to 2.4C
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CO2 emission from gas processing plants
Associated CO2 with natural gas is one of the
sources of global CO2 emissions CO2 content in
natural gas varies between 2-65 and in some
reserves is even more! Increasing demand for
natural gas has made reserves with high CO2
content economically H2S is often present with
CO2 in natural gas reserves
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Definitions and Spec in gas processing plants
Natural gas containing H2S gt 4 ppm is called
sour gas Natural gas containing acidic gases
like CO2/H2S is called acid gas To produce
sweet gas, CO2 and H2S (for technical and
environmental reasons) must be removed and
stored Specs. for natural gas pipelines CO2
2-4 mol (varies by the country) H2S 4 ppm
Specs. of natural gas for LNG plants CO2 lt
50 ppm H2S lt 4 ppm
7
High acid gas content natural gas reserves
Most high CO2 natural gas resources are located
in SE Asia, NW Australia, Central USA, North
Africa and Middle East It is estimated 1/5-1/3
of global natural gas resources have significant
amounts of CO2 and H2S Natuna gas field in
Indonesia, the largest high CO2 reserve
(gt70v) LaBarge gas field (65 CO2) in SW
Wyoming (USA), discovered in 1963, production
delayed until1986 because of high CO2
concentration
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Different (old/new) Technologies for CO2/H2S
removal
Adsorption (chemical,C / physical,P) Activated
carbon (C), Chemsweet (C), Molecular sieves (P),
Zinc oxide (C) Absorption (mostly chemical) ADIP,
Alkazid, Amisol, Benfield, Catacarb, CNG (P),
Estasolvan, Flexsorb SE, Flour Econamine, Flour
solvent, Giammarco-Vetrocoke, MEA, MDEA, Purisol
(P), Rectisol (P), Seaboard, Selexol (P),
Sepasolv MPE (P), SNPA-DEA, Stretford, Sulfiban,
Sulfinol, Tripotassium Phosphate, Vaccum
Carbonate, Zinc oxide Cryogenic
distillation Controlled Freeze Zone (CFZ), Ryan
Holmes, Cryocell, Sprex, Twister Membrane
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Applications of different technologies in gas
processing plants for removing of acid gases
Adsorption Suitable for reducing CO2 content from
3 to 0.5 Not applicable for high CO2
concentration streams since it needs frequent
regeneration of solid bed Absorption Suitable for
low pressure streams with CO2 content of
3-25 This method is the conventional method,
which is widely used in natural gas processing
industries Not suitable for very high CO2
concentration streams due to large solvent
recirculation and consequently large heat duty in
the stripper for solvent regeneration
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Applications of different technologies in gas
processing plants for removing of acid gases
Membrane Flexible for different CO2
concentrations, but maintaining high performance
of membrane in presence of varying contaminants
of natural gas stream is a challenge Traditional
technologies - remove acid gases at near
atmospheric pressures, - required significant
amount of energy to compress acid gases for
re-injection for Enhanced Oil Recovery (EOR)
Cryogenic distillation Suitable for removing
high CO2/H2S contents from natural gas streams
especially for offshore applications
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• Outline
• Introduction
• 2. Cryogenic technologies
• Ryan Holmes method
• Controlled freeze zone (CFZ) method
• Cryocell method
• Sprex method
• Twister technology
• 3. Conclusions

12
Point 1 Feed
Phase diagram for CO2/CH4 in 650 Psia (44 bar)
Target natural gas product with 1 CO2
Feed 50 CH4/50 CO2
Chilling the feed
Point 2 reaching the VL zone
-8 (-22C)
Point 3
Liquid 18 CH4
Vapor 72 CH4
Achieving natural gas with CH4 purity of gt85 is
not possible in one conventional distillation
column
Point 4
Solidification point of CO2
Vapor 85 CH4
(-62C)
Figure from H.G. Donnelly and D.L. Katz, Phase
equilibria in the carbon dioxide-methane system,
IEC, 46 (1954), 3, 511-517
13

• Outline
• Introduction
• 2. Cryogenic technologies
• Ryan Holmes method
• Controlled freeze zone (CFZ) method
• Cryocell method
• Sprex method
• Twister technology
• 3. Conclusions

14
Ryan Holmes method
Invented by Arthur S. Holmes and James S. Ryan at
Koch Process Systems, US in 1982
Agent should have a freezing temp. below
condenser Temp.
Idea Adding a solids-preventing agent e.g. NGL,
to the solids potential zone of cryogenic
distillation column
Pre-cooler
By adding sufficiently agent, the liquid
composition is moved away from the freezing point
Cooling to cryogenic temperatures
This method is commonly used in gas processing
plants Suitable for offshore applications?
The Figure from A. S. Holmes, J. M. Ryan,
Cryogenic distillation separation of acid gases
from methane, US patent, 1982
15

• Outline
• Introduction
• 2. Cryogenic technologies
• Ryan Holmes method
• Controlled freeze zone (CFZ) method
• Cryocell method
• Sprex method
• Twister technology
• 3. Conclusions

16
Controlled Freeze Zone method (CFZTM)
CFZTM method invented at Exxon production
research in 1983 patented in 1985 First pilot
plant (the picture in the right) at Exxons
Clear Lake Gas plant in Pasedena (1987) 0.6
MMSCFD, CO2 (from 15 to 65),
pressure (38-42 bar) Quality of products while
the design of top product (natural gas)
specification was pipeline specs, it met LNG
feed required specs! The design of methane loss
at the bottom product (liquid CO2) was 1, but
it reached 0.5 Further studies were stopped due
to collapse in oil prices
Figure from J. A. Valencia, P. S. Northorp, C.
J. Mart, Controlled Freeze Zone Technology for
enabling processing of high CO2 and H2S gas
reserves, ExxonMobil Upstream Research Company
IPTC 12708 (2008)
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Exxons first CFZ commercial demonstration plant
at Shute Creek gas processing plant
Scale up 23 Integrated with a gas field
injection Initial tests prove removal of CO2
content from 65 down to lt1000ppm (July 2011) The
tests are still being done in 2011-2012
Figure from C. Condon, M. Parker, Shute Creek
Gas Treating Facility Project Updates, The
Wyoming Enhanced Oil Recovery Institute 5th
Annual Wyoming CO2 Capture Conference, 13 July
2011
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CFZ method thermodynamic concept
82 bar
critical point of methane
42 bar
critical point of CO2
14 bar
-57C
-1C
32C
-101C
Rather than avoiding solidification, CFZ allows
acid gases to freeze Operating at higher pressure
than CO2 solidification pressure (?) Limitation
of locus of the critical points Still far from
the required purity for methane product
Figure from the references below H.G. Donnelly
and D.L. Katz, Phase equilibria in the carbon
dioxide-methane system, IEC, 46 (1954), 3,
511-517 and J. A. Valencia, P. S. Northorp, C. J.
Mart, Controlled Freeze Zone Technology for
enabling processing of high CO2 and H2S gas
reserves, ExxonMobil Upstream Research Company
IPTC 12708 (2008)
19
CFZ distillation operation

• Operating the column in lower pressure than
  solidification pressure
• Operation crosses the solidification region
• 3 operational zones are present
• Stripping section (conventional distillation)
• Solidification (controlled freeze zone, CFZ)
  section
• Rectifying section (conventional distillation)

Feed (mixture of CH4 and CO2) enters somewhere
near the middle of column Reboiler duty
allowable loss of methane in CO2 liquid bottom
product Condenser temperature required specs
for purified methane
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Liquid from the top distillation section is
sprayd into the CFZ section Warmer temperature
vaporize the lighter components
methane product (high quality) available in high
pressure
Solid (pure CO2) is formed in CFZ section and
fall on the liquid layer Bottom part of CFZ is
kept above solidification temperature
CO2 product (liquid)/or any other acid gas,
easily to be pumped for geo-sequestration or for
EOR purposes
Vapor rises from the bottom distillation section
to the CFZ section Colder temperature in CFZ
section condenses CO2
Figure from B.T.Kelly, J. A. Valencia, P. S.
Northorp, C. J. Mart, Controlled Freeze Zone for
developing sour gas reserves, Energy Procedia 4
(2011), 824-829
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Optimal operation of CFZ distillation

• Operational temperature will depend on feed
  composition and product specification
• CFZ distillation operates at constant pressure
• Optimized pressure of CFZ column depends on
• pressure of the gas reserve,
• required pressure for purified natural gas
  (sales spec),
• geometry of the column

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Advantages of CFZ method
Suitable for high CO2/H2S content natural gas
reserves Separation is done in a single column,
low investment cost, less challenges for offshore
applications Purified natural gas product in high
pressure (reduce the compressor work to export by
the pipeline) Availability of CO2/H2S product in
liquid form, readily to be pumped for EOR,
geo-sequestration purposes
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• Outline
• Introduction
• 2. Cryogenic technologies
• Ryan Holmes method
• Controlled freeze zone (CFZ) method
• Cryocell method
• Sprex method
• Twister technology
• 3. Conclusions

24
Cryocell method
This method was developed by Cool Energy Ltd and
tested in collaboration with Shell in Australia
(Perth) Idea CO2 sublimation point -78.5C (at
1 bar) CH4 (major component of Natural gas)
sublimation point -182C (at 1 bar) Mixture of
light hydrocarbons CO2 at certain T,P
Vapor-Liquid-Solid phases Solid phase pure CO2,
Vapor/Liquid phase CO2 hydrocarbons
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Thermodynamic behavior of mixture of hydrocarbons
CO2
1- Mixture (feed) at pressure gt 50 bar and
ambient temperature
2- Feed is cooled down to above solidification
temperature of CO2(liquid phase) 3- Liquid is
isenthalpic flashed through a Joule-Thomson valve
into a separator solid-vapor-liquid
before JT valve
after JT valve
Selection of appropriate - pre-cooling
temperature - flash pressure to minimize CO2
content in vapor phase and methane content in
liquid phase
VLSE diagram for a high CO2 content natural gas
50 CO2, 40 CH4, 10 other light hydrocarbons
Figure from A. Hart and N. Gnanendran, Cryogenic
CO2 Capture in Natural Gas, Energy Procedia 1
(2009), 697-706
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Different Cryocell configurations
Based on natural gas composition - high
(gt20) or low (lt20) CO2 composition - lean
(recovery uneconomical) or rich of NGLs 4
process flow configurations low CO2/lean Natural
gas low CO2/Rich Natural gas high CO2/lean
Natural gas high CO2/Rich Natural gas
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Cryocell process diagram for low CO2/lean Natural
gas
Base case Cryocell flow diagram
Figure from A. Hart and N. Gnanendran, Cryogenic
CO2 Capture in Natural Gas, Energy Procedia 1
(2009), 697-706
28
Cryocell process diagram for high CO2/Rich
Natural gas
Additional bulk CO2 removal column and NGL
recovery
Figure from A. Hart and N. Gnanendran, Cryogenic
CO2 Capture in Natural Gas, Energy Procedia 1
(2009), 697-706
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Cryocell field results
Design of demonstration plant based on scheme for
low CO2-lean gas (2008, 2009) Removing down CO2
content from 60 to 26, 40 to 14, 21 to 4
and from 13 to 3 Excellent match between tests
and simulation results (Aspen Hysys CryoFlash)
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Comparison between Cryocell and Amine Absorption
Amine Amine CryoCell CryoCell
Sale gas rate, MMSCFD 37.7 27.8 38.2 29.6
Investment cost (1000 AUD), accuracy 30 CO2 20 CO2 35 CO2 20 CO2 35
Investment cost (1000 AUD), accuracy 30 64,359 108,777 48,877 67,464
Compression Power (MW) 1.9 3.8 4.3 7
Electrical load (MW) 1.3 2.2 0.2 0.3
Process Heating (MW) 19 35 lt 0.1 lt 0.1
Other advantages of Cryocell No need for
chemical solvent, no make up water, no heating
system, no potential foaming Cryocell has higher
maintenance costs for rotating equipment Suitable
for offshore applications
The data from A. Hart and N. Gnanendran,
Cryogenic CO2 Capture in Natural Gas, Energy
Procedia 1 (2009), 697-706
31

• Outline
• Introduction
• 2. Cryogenic technologies
• Ryan Holmes method
• Controlled freeze zone (CFZ) method
• Cryocell method
• Sprex method
• Twister technology
• 3. Conclusions

32
Sprex (Special pre-extraction) method
Patented by IFP in 1994 and further developed in
joint with TOTAL Idea Improving the economics of
amine absorption processes for removal of high
H2S content (as high as 40) in natural gas,
where acid gases are re-injected to the
reservoir Temperature of cryogenic section is
-65C High pressure liquid H2S ready to be pumped
into the reservoir
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Sprex (Special pre-extraction) method
A temperature of -60C to -70C must be attained
Much smaller amine absorption
Figure from ToTAL website http//www.total.com/ME
DIAS/MEDIAS_INFOS/239/EN/sour-gas-2007.pdf?PHPSESS
IDcec2fdfc960710c595870d3827bb4269
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Comparison of Sprex method with Amine absorption
Raw gas flowrate (MMSM3/day) 4.6 (165 MMSCFD)
Treatment Pressure 70 bar
Acid gas injection pressure 150 bar
Feed gas composition H2S35, CO27.5, C165.2, C21
Treated gas specs H2S 4ppm, CO2 2
Amine AmineSprex 30
Capex (MM USD) 153 128
Power consumption (MW) 52 30
Steam consumption (MW) 46 34
Sprex decreses the amine absorption size
significantly
The data from F. Lallemand, F. Lecomte and C.
Striecher, Highly Sour Gas Processing, H2S bulk
removal with the Sprex Process, IPTC 10581, 2005
35

• Outline
• Introduction
• 2. Cryogenic technologies
• Ryan Holmes method
• Controlled freeze zone (CFZ) method
• Cryocell method
• Sprex method
• Twister technology
• 3. Conclusions

36
Twister method
Idea condensation and separation in supersonic
velocity (extremely short residence time),
thermodynamically similar to a turbo-expander
Pressure Recovery
Distillation
Expansion
Temperature drop by transforming pressure to
kinetic energy (i.e. supersonic velocity)
Figure from P. Schinkelshoek, H. D. Epsom,
Supersonic gas conditioning commercialization of
Twister technology, 87th annual convention,
Grapevine, Texas, USA
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Twister method
Twister method has been successfully applied for
water dehydration and NGL/LPG extraction First
commercial offshore application in 2004 for
dehydration of 600 MMSCFD sour gas at Bintulu in
Malaysia (6 Twister tubes in two parallel
dehydration units) A Twister process scheme has
been developed for H2S/CO2 bulk removal from sour
gas An amine absorption process is needed to
purify the outlet of Twister to the required
specs methane recovery of 95 is expected
Compact lightweight Twister can significantly
decrease the size of conventional absorption
processes, suitable for offshore applications
38

• Outline
• Introduction
• 2. Cryogenic technologies
• Ryan Holmes method
• Controlled freeze zone (CFZ) method
• Cryocell method
• Sprex method
• Twister technology
• 3. Conclusions

39
Conclusions
Increasing demand for natural gas has made high
acid gas reserves economically
Cryogenic technologies are suitable for offshore
applications processes, and operation in high
pressure
- small sizes compared to conventional amine
absorption
- less energy requirement
- separation of acid gases in liquid form and
high pressure readily to be pumped to the
reservoir
CFZ, Cryocell, Sprex and Twister seem to be very
promising and advanced options
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References 1 Sources of CO2 IPCC Special Report
on Carbon dioxide Capture and Storage http//www.i
pcc.ch/pdf/special-reports/srccs/srccs_chapter2.pd
f 2 J. Hao, P.A. Rice, S.A. Stern, Upgrading
low-quality natural gas with H2S and CO2
selective polymer membranes Part I. Process
design and economics of membrane stages without
recycle streams, Journal of Membrane Science,
209, 1, 177-206 3 D. A. Coyle, V. Patel,
Process and Pump services in the LNG industry,
Proceedings of 22nd international pump user
symposium 2005, 4 http//en.wikipedia.org/wiki/
Sour_gas 5 WFJ Burgers, PS Northrop, HS
Kheshgi, JA Valencia, Worldwide development
potential for sour gas, Energy Procedia, 4
(2011), 21782184 6 H. J. Herzog and E. M.
Drake, Carbon dioxide recovery and disposal from
large energy systems, Energy and the Environment,
12 (1996), 145-166 7 J. A. Valencia, B. K.
Mentzer, Processing of High CO2and H2S Gas with
Controlled Freeze Zone Technology, ExxonMobil
Upstream Research Company GASEX 2008
Conference 8 http//www.fischer-tropsch.org/DOE
/DOE_reports/GRI/gri-86_0009-1/86_0009-1,20Part2
04,20Pages2029820-20409.pdf 9 E. Keskes,
C.S. Adjiman, A. Galindo, and G. Jackson, a
physical absorption process for the capture of
CO2 from CO2-rich natural gas streams, Chemical
Engineering Department, Imperial College London,
http//www.geos.ed.ac.uk/ccs/Publications/Keskes.p
df
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References 10 H.G. Donnelly and D.L. Katz,
Phase equilibria in the carbon dioxide-methane
system, IEC, 46 (1954), 3, 511-517 11 J. A.
Valencia, P. S. Northorp, C. J. Mart, Controlled
Freeze Zone Technology for enabling processing
of high CO2 and H2S gas reserves, ExxonMobil
Upstream Research Company IPTC 12708 (2008) 12
B.T.Kelly, J. A. Valencia, P. S. Northorp, C. J.
Mart, Controlled Freeze Zone for developing sour
gas reserves, Energy Procedia 4 (2011),
824-829 13 C. Condon, M. Parker, Shute Creek
Gas Treating Facility Project Updates, The
Wyoming Enhanced Oil Recovery Institute 5th
Annual Wyoming CO2 Capture Conference, 13 July
2011 14 A. Hart and N. Gnanendran, Cryogenic
CO2 Capture in Natural Gas, Energy Procedia 1
(2009), 697-706 15 P. Schinkelshoek, H. D.
Epsom, Supersonic gas conditioning
commercialization of Twister technology, 87th
annual convention, Grapevine, Texas, 2008 16
P. Schinkelshoek, H. D. Epsom, Supersonic gas
conditioning for NGL recovery, offshore
technology conference, Houston, 2008 17 A. S.
Holmes, J. M. Ryan, Cryogenic distillation
separation of acid gases from methane, US patent,
1982 18 http//www.total.com/MEDIAS/MEDIAS_INFO
S/239/EN/sour-gas-2007.pdf?PHPSESSIDcec2fdfc96071
0c595870d3827bb4269
42
Thank you for your attention!