Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
  • B01D53/1456—Removing acid components
  • B01D53/1462—Removing mixtures of hydrogen sulfide and carbon dioxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
  • B01D53/1425—Regeneration of liquid absorbents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
  • B01D53/1493—Selection of liquid materials for use as absorbents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/46—Removing components of defined structure
  • B01D53/62—Carbon oxides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
  • B01D53/86—Catalytic processes
  • B01D53/8603—Removing sulfur compounds
  • B01D53/8612—Hydrogen sulfide
  • B01D53/8618—Mixtures of hydrogen sulfide and carbon dioxides
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS
  • C10L3/00—Gaseous fuels; Natural gas; Synthetic natural gas obtained by processes not covered by subclass C10G, C10K; Liquefied petroleum gas
  • C10L3/06—Natural gas; Synthetic natural gas obtained by processes not covered by C10G, C10K3/02 or C10K3/04
  • C10L3/10—Working-up natural gas or synthetic natural gas
  • C10L3/101—Removal of contaminants
  • C10L3/102—Removal of contaminants of acid contaminants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/20—Organic absorbents
  • B01D2252/202—Alcohols or their derivatives
  • B01D2252/2021—Methanol
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/20—Organic absorbents
  • B01D2252/202—Alcohols or their derivatives
  • B01D2252/2023—Glycols, diols or their derivatives
  • B01D2252/2025—Ethers or esters of alkylene glycols, e.g. ethylene or propylene carbonate
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/20—Organic absorbents
  • B01D2252/202—Alcohols or their derivatives
  • B01D2252/2023—Glycols, diols or their derivatives
  • B01D2252/2026—Polyethylene glycol, ethers or esters thereof, e.g. Selexol
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/20—Organic absorbents
  • B01D2252/202—Alcohols or their derivatives
  • B01D2252/2023—Glycols, diols or their derivatives
  • B01D2252/2028—Polypropylene glycol, ethers or esters thereof
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/20—Organic absorbents
  • B01D2252/204—Amines
  • B01D2252/20436—Cyclic amines
  • B01D2252/20457—Cyclic amines containing a pyridine-ring
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/20—Organic absorbents
  • B01D2252/204—Amines
  • B01D2252/20478—Alkanolamines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/20—Organic absorbents
  • B01D2252/205—Other organic compounds not covered by B01D2252/00 - B01D2252/20494
  • B01D2252/2053—Other nitrogen compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/20—Organic absorbents
  • B01D2252/205—Other organic compounds not covered by B01D2252/00 - B01D2252/20494
  • B01D2252/2056—Sulfur compounds, e.g. Sulfolane, thiols
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
  • Y02C20/00—Capture or disposal of greenhouse gases
  • Y02C20/40—Capture or disposal of greenhouse gases of CO2

Definitions

• the present invention relates to a method for using a physical solvent such as a dimethyl ether of polyethylene glycol (DMPEG) to treat a contaminated gas such as a contaminated natural gas or a synthesis gas from gasification to concentrate and to remove carbon dioxide and hydrogen sulfide at a reduced energy and capital requirement.
• a physical solvent such as a dimethyl ether of polyethylene glycol (DMPEG)
• DMPEG polyethylene glycol
• flash regenerated semi-lean solvent is circulated between the bottom section of the carbon dioxide absorber and one or more lower pressure flash drums in order to remove carbon dioxide from the synthesis gas flowing through the carbon dioxide absorber.
• This semi-lean solvent (which contains a relatively small amount of carbon dioxide) can have a prohibitively large flow rate in this type of design. Cooling the solvent to a temperature of between -30 0 C (-22 0 F) and 15°C (59°F) increases the solvent capacity and reduces the required solvent flow rate, but it is economically unattractive to cool this stream to low temperatures directly due to the high refrigeration duties and large equipment sizes involved.
• the current practice in a commercial unit in operation utilizes a total draw-off tray near the bottom of the carbon dioxide absorber where all of the loaded solvent flowing down the column is taken out of the column and pumped into a refrigerated exchanger where it is mixed and cooled with the gas exiting the upstream hydrogen sulfide absorber before entering the bottom sump section of the carbon dioxide absorber.
• This total draw-off scenario effectively decreases the temperature of the loaded solvent in the bottom sump section of the carbon dioxide absorber and as the solvent is flash regenerated through the series of flash drums, the semi-lean solvent temperature is further reduced by the cooling effect of the carbon dioxide flashing out of the solvent. Since a lower temperature of this semi-lean solvent increases the solvent capacity for absorbing carbon dioxide, the solvent flow rate can be reduced.
• Cooling the solvent by refrigeration prior to the successive carbon dioxide flashes allows for a temperature in the final flash drum that is lower than is otherwise practical in a typical refrigerated exchanger. Negatives to this design are that the total draw-off tray increases the size of the carbon dioxide absorber tangent length significantly, adds to the column internals cost, adds to the equipment count for the unit by requiring a dedicated pump, and significantly adds to the solvent inventory of the unit.
• the mixer/exchanger for the prior art design is also very large and difficult to design to have a predictable and satisfactory performance. There are also concerns with the operation of this mixer/exchanger.
• the present invention involves a partial pumparound of the solvent. Instead of drawing from a draw-off tray, the solvent for the pumparound is split from a branch of the main flow exiting the bottom sump section of the column. This loaded solvent is pumped from the bottom of the carbon dioxide absorber with an existing pump service used to deliver loaded solvent to the hydrogen sulfide absorber and cooled in an exchanger that is shared with the loaded solvent used to supply the hydrogen sulfide absorber. Just after being chilled to approximately 5°C (40 0 F), the pumparound portion of the solvent is slit off and is routed to a static mixer where it is mixed with the gas coming from the top of the hydrogen sulfide absorber before being routed to the bottom sump section of the carbon dioxide absorber.
• the solvent flow rate in the pumparound is determined by the temperature desired in the final flash drum of the flash regeneration section. Increasing the pumparound flow will decrease the carbon dioxide absorber bottom temperature and the final flash temperature. Temperatures as low as -30 0 C (-22 0 F) are achievable without lowering the required temperature of the refrigerant used in the unit or without adding any additional pumps, exchangers or substantially increasing the tangent length of the carbon dioxide absorber.
• the FIGURE shows a flow scheme to use a physical solvent to treat a synthesis gas or other gas stream to remove and concentrate carbon dioxide and hydrogen sulfide.
• the present invention employs a physical solvent to remove impurities such as hydrogen sulfide and carbon dioxide from a gas stream.
• Representative physical solvents for use in this invention include N-methyl pyrrolidone, the dialkylethers of polyethylene glycol, tributyl phosphate, tetramethylene sulfone, propylene carbonate, methanol, alkanolpyridines and Sulfolane (tetrahydrothiophene dioxide).
• Dimethyl ethers of propylene glycol are a preferred solvent.
• a flow of synthesis gas 1 that has been through a shift reactor is shown passing through a feed/product exchanger 4 to line 8 and then entering the bottom of hydrogen sulfide absorber 10 containing a solvent that contacts the flow of synthesis gas to remove hydrogen sulfide and other sulfur compounds.
• a stream 12 exits the hydrogen sulfide absorber 10 and contains an increased concentration of hydrogen sulfide. The stream 12 then passes to a sulfur regeneration section 14 from which hydrogen sulfide is removed to recover from the system shown as flow 16.
• a second stream 28 is shown exiting the top of hydrogen sulfide absorber 10 and then going to a static mixer 30 to be mixed with a cooled loaded solvent stream 78 and then a combined stream enters the bottom of carbon dioxide absorber 34 through line 32.
• a solvent stream 38 that is loaded with carbon dioxide, exits the bottom of carbon dioxide absorber 34 and is split into stream 39 to continue to a series of flash drums and stream 68 as part of the partial pumparound.
• Stream 68 is shown being pumped by loaded solvent pump 70 into line 72 and then to loaded solvent chiller 74 into line 76.
• Stream 76 is split into stream 79 to enter the top of hydrogen sulfide absorber 10 and stream 78 which goes to static mixer 30 to be combined with second stream 28.
• Stream 39 is shown passing to high flash pressure CO2 flash drum 40 with line 42 showing the exiting of the carbon dioxide and the solvent passing through line 44 to medium flash pressure carbon dioxide flash drum 46 with carbon dioxide leaving through line 48 and the solvent continuing in line 50 on to low flash pressure CO2 flash drum 52 with carbon dioxide leaving as shown at line 54 and the resulting semi-lean solvent passes through line 56 to semi-lean solvent pump 58 to line 60 and then returning to carbon dioxide absorber 34 as shown.
• the purified synthesis gas exits the top of carbon dioxide absorber 34 to pass through line 36 to feed product exchanger 4 to line 6 and then be further processed as desired.
• stream 62 passing from sulfur regeneration section 14 through lean solvent chiller 64 to line 66 and then to carbon dioxide absorber 34.
• Line 18 passes from sulfur regeneration section 14 to recycle compressor 20 to line 22, recycle gas cooler 24 and line 26 to hydrogen sulfide absorber 10.
• the use of the partial pumparound of the present invention allows for a decrease in the semi-lean flow rate and associated equipment size of 10-15% compared to not using the partial pumparound at all.
• the invention provides lower temperatures with lower required solvent flow rates or higher capacity for the same flow rate without the need for additional pumps or additional problematic exchangers.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Environmental & Geological Engineering (AREA)
• Health & Medical Sciences (AREA)
• Biomedical Technology (AREA)
• Organic Chemistry (AREA)
• Gas Separation By Absorption (AREA)
• Industrial Gases (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Carbon And Carbon Compounds (AREA)

Applications Claiming Priority (2)

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• 2009
  • 2009-04-29 CA CA2726640A patent/CA2726640A1/en not_active Abandoned
  • 2009-04-29 CN CN2009801236748A patent/CN102065976A/zh active Pending
  • 2009-04-29 WO PCT/US2009/042093 patent/WO2009158064A2/en not_active Ceased
  • 2009-04-29 JP JP2011516360A patent/JP2011525860A/ja active Pending
  • 2009-04-29 KR KR1020107028534A patent/KR20110016945A/ko not_active Ceased
  • 2009-04-29 AU AU2009262906A patent/AU2009262906A1/en not_active Abandoned
  • 2009-04-29 EP EP09770599A patent/EP2291229A4/de not_active Withdrawn

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