Trial Lecture - Fakultet for naturvitenskap - · PPT file · Web view ·...

1/41 M. Panahi ’Cryogenic CO2/H2S capture technologies for remote natural gas processing’

Cryogenic CO2/H2S capture technologies for

remote natural gas processing

Mehdi Panahi

Trial Lecture

December 1st, 2011Trondheim


Outline

1. Introduction

2. Cryogenic technologies

- Ryan Holmes method

- Controlled freeze zone (CFZ) method

- Cryocell method

- Sprex method

- Twister technology

3. Conclusions


Outline

1. Introduction




- Cryocell method

- Sprex method


3. Conclusions


Green house gases cause global warming: CO2, the major one

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 2°C to 2.4°C”

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

CO2 effect on Global warming


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

CO2 emission from gas processing plants


Natural gas containing H2S > 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: < 50 ppmH2S: < 4 ppm

Definitions and Spec in gas processing plants


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: (>70%v)

LaBarge gas field (65% CO2) in SW Wyoming (USA), discovered in 1963, production delayed until1986 because of high CO2 concentration

High acid gas content natural gas reserves


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 distillationControlled Freeze Zone (CFZ), Ryan Holmes, Cryocell, Sprex, Twister

Membrane

Different (old/new) Technologies for CO2/H2S removal


Applications of different technologies in gas processing plants for removing of acid gases

AdsorptionSuitable for reducing CO2 content from 3% to 0.5%

Not applicable for high CO2 concentration streams since it needs frequent regeneration of solid bed

AbsorptionSuitable 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


Applications of different technologies in gas processing plants for removing of acid gases

MembraneFlexible 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 distillationSuitable for removing high CO2/H2S contents from natural gas streams especially for offshore applications


Outline

1. Introduction




- Cryocell method

- Sprex method


3. Conclusions


Point 1:Feed

Point 2: reaching the VL zone

Chilling the feed

Point 3:

-8 (-22°C)

Vapor: 72% CH4

Liquid: 18% CH4

Point 4: Vapor: 85% CH4

Target: natural gas product with 1% CO2

Feed: 50% CH4/50% CO2

Achieving natural gas with CH4 purity of >85% is not possible in one conventional distillation column

Solidification point of CO2

Phase diagram for CO2/CH4 in 650 Psia (44 bar)

(-62°C)

Figure from: H.G. Donnelly and D.L. Katz, Phase equilibria in the carbon dioxide-methane system, I&EC, 46 (1954), 3, 511-517


Outline

1. Introduction




- Cryocell method

- Sprex method


3. Conclusions


Ryan Holmes method

The Figure from: A. S. Holmes, J. M. Ryan, Cryogenic distillation separation of acid gases from methane, US patent, 1982

Idea: Adding a solids-preventing agent e.g. NGL, to the solids potential zone of cryogenic distillation column

Invented by Arthur S. Holmes and James S. Ryan at Koch Process Systems, US in 1982

Pre-cooler

Cooling to cryogenic

temperatures

Agent should have a freezing temp. below condenser Temp.

By adding sufficiently agent, the liquid composition is moved away from the freezing point

This method is commonly used in gas processing plants

Suitable for offshore applications?


Outline

1. Introduction




- Cryocell method

- Sprex method


3. Conclusions


Controlled Freeze Zone method (CFZTM)CFZTM method:

invented at Exxon production research in 1983patented in 1985

First pilot plant (the picture in the right) at Exxon’s 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 pricesFigure 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)


Exxon’s 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 <1000ppm (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


CFZ method: thermodynamic concept

-57°C

14 bar

42 bar

32°C-101°C

82 bar

Figure from the references below:

H.G. Donnelly and D.L. Katz, Phase equilibria in the carbon dioxide-methane system, I&EC, 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)

critical point of

methane

critical point of CO2

Rather than avoiding solidification, CFZ allows acid gases to freezeOperating at higher pressure than CO2 solidification pressure (?)Limitation of locus of the critical pointsStill far from the required purity for methane product

-1°C


Operating the column in lower pressure than solidification pressure

Operation crosses the solidification region

3 operational zones are present:

1. Stripping section (conventional distillation)

2. Solidification (controlled freeze zone, CFZ) section

3. 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

CFZ distillation operation


Liquid from the top distillation section is sprayd into the CFZ section

Warmer temperature vaporize the lighter components

Solid (pure CO2) is formed in CFZ section and fall on the liquid layer

Bottom part of CFZ is kept above solidification temperature

Vapor rises from the bottom distillation section to the CFZ section

Colder temperature in CFZ section condenses CO2

CO2 product (liquid)/or any other acid gas, easily to be pumped for geo-sequestration or for EOR purposes

methane product (high quality) available in high pressure

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


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

Optimal operation of CFZ distillation


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


Outline

1. Introduction




- Cryocell method

- Sprex method


3. Conclusions


Cryocell method

This method was developed by Cool Energy Ltd and tested in collaboration with Shell in Australia (Perth)

Idea:

CO2 sublimation point: -78.5°C (at 1 bar)

CH4 (major component of Natural gas) sublimation point: -182°C (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


Figure from: A. Hart and N. Gnanendran, Cryogenic CO2 Capture in Natural Gas, Energy Procedia 1 (2009), 697-706

Thermodynamic behavior of mixture of hydrocarbons + CO2

VLSE diagram for a high CO2 content natural gas: 50% CO2, 40% CH4, 10%

other light hydrocarbons

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

1- Mixture (feed) at pressure > 50 bar and ambient temperature

Selection of appropriate: - pre-cooling temperature - flash pressure

to minimize CO2 content in vapor phase and methane content in liquid phase

before JT valve

after JT valve


Different Cryocell configurations

Based on natural gas composition:

- high (>20%) or low (<20%) 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


Cryocell process diagram for low CO2/lean Natural gas


Base case Cryocell flow diagram



Cryocell process diagram for high CO2/Rich Natural gas

Additional bulk CO2 removal column and NGL recovery


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)


Comparison between Cryocell and Amine Absorption

Amine CryoCellSale 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%

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 < 0.1 < 0.1

The data from: A. Hart and N. Gnanendran, Cryogenic CO2 Capture in Natural Gas, Energy Procedia 1 (2009), 697-706

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


Outline

1. Introduction




- Cryocell method

- Sprex method


3. Conclusions


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 -65°C

High pressure liquid H2S ready to be pumped into the reservoir


A temperature of -60°C to -70°C must be attained

Sprex (Special pre-extraction) method

Figure from: ToTAL website

http://www.total.com/MEDIAS/MEDIAS_INFOS/239/EN/sour-gas-2007.pdf?PHPSESSID=cec2fdfc960710c595870d3827bb4269

Much smaller amine absorption


Raw gas flowrate (MMSM3/day) 4.6 (165 MMSCFD)

Treatment Pressure 70 bar

Acid gas injection pressure 150 bar

Feed gas composition H2S:35%, CO2:7.5%, C1:65.2%, C2+:1%

Treated gas specs H2S: 4ppm, CO2: 2%

Amine Amine+Sprex 30

Capex (MM USD) 153 128

Power consumption (MW) 52 30

Steam consumption (MW) 46 34

The data from: F. Lallemand, F. Lecomte and C. Striecher, “Highly Sour Gas Processing, H2S bulk removal with the Sprex Process”, IPTC 10581, 2005

Comparison of Sprex method with Amine absorption

Sprex decreses the amine absorption size significantly


Outline

1. Introduction




- Cryocell method

- Sprex method


3. Conclusions


Twister method

Idea: condensation and separation in supersonic velocity (extremely short residence time), thermodynamically similar to a turbo-expander

Figure from: P. Schinkelshoek, H. D. Epsom, Supersonic gas conditioning commercialization of Twister technology, 87th annual convention, Grapevine, Texas, USA

Expansion DistillationPressure Recovery

Temperature drop by transforming pressure to kinetic energy (i.e. supersonic velocity)


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

Twister method


Outline

1. Introduction




- Cryocell method

- Sprex method


3. Conclusions


CFZ, Cryocell, Sprex and Twister seem to be very promising and advanced options

Increasing demand for natural gas has made high acid gas reserves economically

Conclusions

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


References[1] Sources of CO2 IPCC Special Report on Carbon dioxide Capture and Storagehttp://www.ipcc.ch/pdf/special-reports/srccs/srccs_chapter2.pdf

[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), 2178–2184

[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,%20Part%204,%20Pages%20298%20-%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.pdf

http://www.ipcc.ch/pdf/special-reports/srccs/srccs_chapter2.pdf

http://www.sciencedirect.com/science/journal/03767388



http://en.wikipedia.org/wiki/Sour_gas

http://www.fischer-tropsch.org/DOE/DOE_reports/GRI/gri-86_0009-1/86_0009-1,%20Part%204,%20Pages%20298%20-%20409.pdf

http://www.fischer-tropsch.org/DOE/DOE_reports/GRI/gri-86_0009-1/86_0009-1,%20Part%204,%20Pages%20298%20-%20409.pdf

http://www.geos.ed.ac.uk/ccs/Publications/Keskes.pdf

http://www.geos.ed.ac.uk/ccs/Publications/Keskes.pdf


References[10] H.G. Donnelly and D.L. Katz, Phase equilibria in the carbon dioxide-methane system, I&EC, 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_INFOS/239/EN/sour-gas-2007.pdf?PHPSESSID=cec2fdfc960710c595870d3827bb4269


Thank you for your attention!

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