CA1237064A - Process and apparatus for scrubbing gaseous components out of gaseous mixtures - Google Patents

Process and apparatus for scrubbing gaseous components out of gaseous mixtures

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Publication number
CA1237064A
CA1237064A CA000470562A CA470562A CA1237064A CA 1237064 A CA1237064 A CA 1237064A CA 000470562 A CA000470562 A CA 000470562A CA 470562 A CA470562 A CA 470562A CA 1237064 A CA1237064 A CA 1237064A
Authority
CA
Canada
Prior art keywords
solvent
gaseous
scrubbing
fraction
methanol
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000470562A
Other languages
French (fr)
Inventor
Heinz Karwat
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Linde GmbH
Original Assignee
Linde GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Linde GmbH filed Critical Linde GmbH
Application granted granted Critical
Publication of CA1237064A publication Critical patent/CA1237064A/en
Expired legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation 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
    • B01D53/14Separation 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
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02CCAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00Capture or disposal of greenhouse gases
    • Y02C20/40Capture or disposal of greenhouse gases of CO2

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Gas Separation By Absorption (AREA)
  • Treating Waste Gases (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Abstract

"PROCESS AND APPARATUS FOR SCRUBBING GASEOUS COMPONENTS OUT OF GASEOUS MIXTURES" Gaseous components are scrubbed from gaseous mixtures with a physical solvent; the latter, after absorption of the scrubbed-out gaseous components, is regenerated by expansion and stripping, wherein the gaseous fraction being released is discharged and the regenerated solvent is recycled into the scrubbing step. To reduce the content of solvent vapors in the gases to be exhausted into the atmosphere, the released gaseous fraction is cooled in heat exchange with non-thermally degasified solvent in order to condense out entrained solvent vapors from the gaseous fraction.

Description

D 7~

PROCESS AND APPARATUS FOR SCRUBBING GASEOUS COMPONENTS
OUT OF GASEOUS MIXTURES
The invention re:Lates to a process and apparatus for scrubbing out gaseous components from gaseous mixtures with a physical solvent which is regenerated by expansion and stripping and in particular wherein the gaseous fraction from the stripping step is discharged and the resultant regenerated solvent is recycled to the scrubbing step.
It is old to utilize physical solvents for the purification of gases/ e.g., synthesis raw gases containing C02, COS, and H2S, or of cracked gase6 of acetylene. Since the absorption capacity of -the physical solvents, such as methanol, for example, for the gaseous components to be scrubbed out increases with decreasing temperature, these scrubbing operations are conducted at as low a temperature as economically and technically feasible. In this connection, with the use of methanol, -the scrubbing temperatures are considerably below 0C, e.g., generally at about -5 to -65C~ Regeneration of the physical solvent loaded with the scrubbed-out gaseous components is conventionally conducted in a combination of pressure reduction and/or stripping and/or thermal regeneration steps. In this regeneration process, the absorbed gaseous components are released and the regenerated solvent is recycled into the scrubbing step.
Among tbe thus-released gases, C02 and N2~ the latter is generally utilized as the stripping gas, and can be discharged, for example, directly into the atmosphereO
However, this gaseous fraction still contains in all instances a proportion of concomitantly driven-ou-t solvent vapors. This solvent conkent of the gases leaving the scrubbing step is dependent on the temperat.ure and pressure at which the gases are separated Erom the l:iquid solvent.
According to presently enforced regulations to prevent atmospheric pollution, the expulsion oE solvent vapors must not exceed a content dependenk on the respective type of solvent. For this reason, it has been suggested to subject the gases to be discharged into the a-tmosphere to an additional purifying process, for example a water scrub or an adsorption procedure, in order to lower the solven.
content in the gas. However, separation oE the solvent from water, or regeneration of the adsorber requires a considerable expenditure in energy and apparatus.
An object of one aspect oE this invention is to provide l a process of the type described above in such a way that the content of solven-t vapors of the gases to be discharged into the atmosphere is reduced in a simple and economical fashion.
An object of another aspect of this invention is to provide apparatus for the process.
These objects are attained according to the invention by cooling the gas fraction being released in heat exchange with non-thermally degasified solvent and condensing out entrained solvent vapors from the gaseous traction.
The process of this invention makes it possible, or example, to meet the requirements of air pollution regulatory laws. Also, my virtue of this invention, it is possible to avoid the use of the water scrub column or the adsorbers of the conventional process, as well as team or the separation of a solvent-water mixture, or the energy input required for adsorber regeneration.
The refrigeration required for the cooling step is made available by heat exchange with non-thermally degasified solvent, i.e., by heat exchange wikh cold-stripped or pressure-reduced solvent, namely solvent from which the 3 ~3}.7~

absorbed gaseous components have been removed without supplyirlg external hea,t. This measure is especially useEul in cases where the scrubbing step is not Eollowed by a low-temperature Eacility, for example a scrubbing process with liquid nitrogen to obtain NH3 synthesis gas, where the necessary cold demand could otherwise be available.
It is especially advantageous to cool the gaseous fraction to temperatures close to the melting point of the solvent. Particularly with the use of methanol, it proved to be advantageous to effect cooling to temperatures of -50C to -97C, preEerably -60C to -85C. The lower temperature limit of -85C is preferred because at even lower temperatures, the increased viscosity of the methanol becomes undesirable.
It is thereby made possible to cool to close the CO2 dew point so that hardly any methanol will remain in the gas to be discharged.
The lowest temperatures can be attained by the use of pressure reduction, e.g., vacuum--for the replacement or saving of stripping gas.
In a further development of the process aspect of this invention, it is provided that a maximum methanol content of 300 mg/Nm3 is set in the gaseous Eraction being released. This level is attained by proper cooling of the gaseous fraction, under the particular gas pressure involved.
According to a still further developmen-t of the process aspect of this invention involving the scrubbing of a gas containing CO2 and H2S, it is contemplated where CO2 and H2S are absorbed that the loaded scrubbing liquid be obtained as two fractions, with one fraction being treated by a non-thermal degasification process to desorb CO2, and the other fraction being treated by a thermal degasification process to desorb H2S.

The proportion oE non--thermally and thermally regenerated me-thanol is determinecl by the relative amounts of dissolved CO2 and ~l2~ in methanol. The very low temperature level reached is obtained by the relative quantity of CO2 evaporating from methanol.
The invention moreover relates to an apparatus for conducting the process with a scrubbing column and non-thermal deyasiEying means, e.g., an expansion and/or stripping facility arranged downstream -thereof, said degasiEying means comprising an inlet for solven-t loaded with scrubbed-out gaseous components and an outlet for regenerated solvent, as well as a discharge conduit for the gaseous fraction being released. This apparatus is characterized in that at least one heat exchanger is arranged in the discharge conduit, and that the heat exchanger is in heat exchange communication with the outlet for regeneration solvent from the non-thermal degasification means.
The process of this invention can be utilized for depleting all gaseous fractions of solvent vapors to avoid solvent losses, such as in the process involving the removal of the H2S fraction or the acetylene fraction Erom a cracked gas, which solvent vapors are not to be discharged into the atmosphere, or wherein recovered gas components to be used for further processing, must be free of solvent vapors. Especially in the case of the H2~
fraction, cooling to less low temperatures is su~Eicient because this fraction is treated in a Claus plant where higher amounts of methanol can be tolerated than in gases being exhausted into the atmosphere.
As Eurther fractions, the CO2 fraction from the expansion step and the CO2/N2 traction frm the stripping step can also be depleted of solvent vapors. The process, in this connection, is applicable in case of all physical solvents, especially those of a high vapor pressure, such as, :Eor example, methanol, ethanol, acetone, dimethyl:eorma-mide, N-methylpyrrolidone.
The attached drawing is a schematically illustrated pre.~erred embodiment comprehensive oE the present invention.
At 1, 10,000 Nm3/h of crude gas to be purified enters into a methanol scrubbing column 2 with a temperature of -20C and under a pressure of 40 bar. The crude gas consis-ts essentially oE H2, CO, and CO2, but also contains COS and ~2S. In the scrubblng column 2, in the lower portion thereof, the sulfur compounds are scrubbed out with a partial quantity of methanol. In the central section of the scrubbing column 2, the rough CO2 scrubbing step takes place, using the main quantity of methanol, and the fine purification is performed in the upper section. The scrubbing step is carried out in the central section of scrubbing column 2 with partially regenerated methanol, in the upper section with completely regenerated methanol.
The puriEied gas is discharged via a conduit 3, optionally in order to precool the crude gas to be purified, and then is passed on to further treatment.
The CO2-loaded methanol, after optional supercooling in cooler 4a, e.g., an ammonia cooler, is expanded via conduit 4 with valve 5 into a separator 6. Duriny expansion, the main quan-tity of the H2 and CO, dissolved in the methanol, is released together with a small portion of the dissolved C2 and flows via conduit 7 from separator 6 to a recycle compressor 12 and back into the crude gas. The methanol, still loaded with CO2, is introduced from separator 6 via a conduit 8 into a regenerating column g and freed therein of C2 by stripping with a stripping gas, e.g. N2, supplied via conduit 10. The thus-liberated gases, primarily CO2 and the nitrogen, are removed from column 9 overhead via the discharge conduit 11. The CO2-depleted methanol is again pumped at 14 to the pressure of the scrubbing column conduit 13 and, after partial heating in a heat exchanger ~3~

15, i.s returned into colu~nn 2 and introduced into the central section thereon as part;.all.y regenerated ethanol via conduit 16.
The methanol, containing H2S and CO2, collecting in the sump of scrubbing column 2 passes via conduit 17 and an intermediate expansion stage, not shown herein, which is analogous to 5, 6, and via heat exchangers 18 and 19 into a thermal-regenerating column 20. In heat exchanger 18, the methanol is heated to approximately ambient temperature, in heat exchanger 19 to about 65C. In regenerating column 20, the methanol is completely degasified by boiling. The thus-regenerated methanol is withdrawn from -the sump of the hot-regenerating column 20 via conduit 21, cooled in heat exchangers 19 to 30C and 18 to -10C. After another cooling step to about -40C in a refrigerant vaporizer 22, the methanol is returned to the scrubbing column 2 and is introduced to the upper section thereof via conduit 23 as completely regenerated methanol. The H2S and CO2 fraction liberated in the thermal-regenerating column 20 exits via conduit 24 from the head of column 20 and can be further treated to obtain elemental sulfur.
The gases in the discharge conduit 11 contain about 2g/Nm3 of methanol vapor. It is desired, however, that the methanol content not exceed 300 mg/Nm3. Therefore, the provision is made in accordance with the invention to treat the gases to be exhausted into the atmosphere by heat exchange with cold, non-thermally regenerated methanol.
For this purpose, the gases are cooled in a heat exchanger 15 against cold-stripped methanol to -67C (30C higher than the melting point of methanol) and introduced into a separator 26. In this separator, the condensed methanol is collected and withdrawn via conduit 27, and i5 recycled into the methanol cycle. The gaseous fraction, at this point freed almost entirely of methanol, leaves the separator 26 after partial heating by heat exchanger 25 via 7 7~

conduit 28. The resultant gay i5 then warmed to approximately ambient temperature aga:in~t crude gay in a heat exchanger not shown herein, and it the exhausted into the atmosphere.
s

Claims (8)

The embodiments of the invention in which an exclusive property or privilege is claimed are as follows:
1. In a process for scrubbing gaseous components from gaseous mixtures comprising scrubbing the gaseous mixture with a physical solvent, regenerating resultant loaded solvent by a process comprising subjecting at least a fraction of the loaded solvent to non-thermal degasification to obtain a gaseous fraction and regenerated solvent, and recycling the regenerated solvent into the scrubbing step, the improvement which comprises cooling said discharged gaseous fraction in heat exchange with non-thermally degasified regenerated solvent at sufficiently low temperatures to condense out entrained solvent vapors from the gaseous fraction.
2. A process according to claim 1 wherein the solvent is methanol and the cooling step is conducted at temperatures of -50°C to -97°C.
3. A process according to claim 1 wherein the solvent is methanol and the cooling step is conducted at temperatures of -60°C to -85°C.
4. A process according to claim 3, the resultant gaseous fraction having not more than 300 Nm3 of methanol.
5. A process according to claim 1 wherein the non-thermal degasification comprises expansion and/or stripping.
6. A process as claimed in claim 1, wherein said process further comprises regenerating a fraction of the loaded solvent by thermally expanding and then thermally regenerating the loaded solvent.
7. A process as claimad in claim 1, wherein said condensed out entrained solvent vapors from the gaseous fraction are further recovered and recycled to the scrubbing step.
8. A process as claimed in claim 1, wherein said discharged gaseous fraction, after the solvent vapors are condensed, is separated from the condensate and is heated in heat exchange with said discharged gaseous fraction, and is then released into the atmosphere.
CA000470562A 1983-12-20 1984-12-19 Process and apparatus for scrubbing gaseous components out of gaseous mixtures Expired CA1237064A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP3346038.8 1983-12-20
DE19833346038 DE3346038A1 (en) 1983-12-20 1983-12-20 METHOD AND DEVICE FOR WASHING GAS COMPONENTS FROM GAS MIXTURES

Publications (1)

Publication Number Publication Date
CA1237064A true CA1237064A (en) 1988-05-24

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ID=6217459

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000470562A Expired CA1237064A (en) 1983-12-20 1984-12-19 Process and apparatus for scrubbing gaseous components out of gaseous mixtures

Country Status (8)

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US (1) US4609389A (en)
EP (1) EP0147738B1 (en)
JP (1) JPS60153920A (en)
AT (1) ATE32665T1 (en)
CA (1) CA1237064A (en)
DE (2) DE3346038A1 (en)
IN (1) IN163850B (en)
ZA (1) ZA849808B (en)

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US4740222A (en) * 1982-05-03 1988-04-26 Advanced Extraction Technologies, Inc. Recovery and purification of hydrogen from refinery and petrochemical off-gas streams
DE3532955A1 (en) * 1985-09-14 1987-03-19 Ruhrchemie Ag METHOD FOR PURIFYING GASES
DE3539554A1 (en) * 1985-11-07 1987-05-14 Linde Ag METHOD FOR DETERMINING C (DOWN ARROW) 2 (DOWN ARROW) (DOWN ARROW) + (DOWN ARROW) OR C (DOWN ARROW) 3 (DOWN ARROW) (DOWN ARROW) + (DOWN ARROW) CARBON WASTE
JPH0642511Y2 (en) * 1988-01-19 1994-11-09 池田物産株式会社 Vehicle seat
ZA899705B (en) * 1989-01-26 1990-09-26 Aeci Ltd Purification of gases
US4980140A (en) * 1989-03-13 1990-12-25 Shell Oil Company Selective removal of carbonyl sulfide from a hydrogen sulfide containing gas mixture
DE4036922A1 (en) * 1990-11-20 1992-05-21 Olaf Gille Removal of harmful prods. from furniture or reactor off-gas - by condensn,. of temp.-controlled off-gas in specified liquids
US6098425A (en) * 1993-10-01 2000-08-08 Stothers; William R. Thermodynamic separation
US6174348B1 (en) * 1999-08-17 2001-01-16 Praxair Technology, Inc. Nitrogen system for regenerating chemical solvent
MY148928A (en) * 2006-12-08 2013-06-14 Shell Int Research Process for producing a purified synthesis gas stream
GB0709433D0 (en) * 2007-05-16 2007-06-27 Gasconsult Ltd Process for removal of carbon dioxide from gases
DE102011016434A1 (en) 2011-04-08 2012-10-11 GM Global Technology Operations LLC (n. d. Gesetzen des Staates Delaware) Identification device for passenger car, has identification plate comprising plate upper side and designed as light conductor plate i.e. plastic plate, with edge sides, where conductor plate has light scattering nano-dopant particles
DE102011016358A1 (en) 2011-04-08 2012-10-11 GM Global Technology Operations LLC (n. d. Gesetzen des Staates Delaware) Number plate device for car, has carrier comprising light conductor material that is provided with light-scattering nano-dopant particles, and number plate comprising plastic plate, where particles are distributed in volume of carrier
DE102011016410A1 (en) 2011-04-08 2012-10-11 GM Global Technology Operations LLC (n. d. Gesetzen des Staates Delaware) Indicator device for vehicle, has indicator frame fixed on vehicle outer contour, and indicator plate with indicator icons which is fixed in frame, where illumination device illuminates top surface
DE102011016435A1 (en) 2011-04-08 2012-10-11 GM Global Technology Operations LLC (n. d. Gesetzen des Staates Delaware) Indicator device for vehicle e.g. car, has base plate and indicator plate that are provided with light guide plates which consist of light-scattering nano-dopant particles
JP6071622B2 (en) * 2013-02-21 2017-02-01 三菱重工業株式会社 CO2 and H2S containing gas recovery system and method
JP5995746B2 (en) * 2013-02-21 2016-09-21 三菱重工業株式会社 CO2 and H2S containing gas recovery system and method
DE102013022083A1 (en) * 2013-12-23 2015-06-25 Linde Aktiengesellschaft Method for operating a gas scrubbing and gas scrubbing
EP4011483A1 (en) * 2020-12-08 2022-06-15 L'Air Liquide - Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude Method and system for removing thiols from synthesis gas

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US3718006A (en) * 1968-12-11 1973-02-27 Linde Ag Process for selective absorption
US3886757A (en) * 1970-12-24 1975-06-03 Phillips Petroleum Co Reduction of hydrate formation in a natural gas stream by contacting with anit-freeze agent
DE2924162A1 (en) * 1979-06-15 1980-12-18 Linde Ag METHOD FOR SELECTIVE WASHING OUT OF SULFUR COMPOUNDS FROM DAMP GAS MIXTURES
DE3036936A1 (en) * 1980-09-30 1982-05-27 Linde Ag, 6200 Wiesbaden METHOD AND DEVICE FOR REGULATING THE AMMONIA CONTENT IN THE DETERGENT OF A GAS WASHER
US4475347A (en) * 1982-09-16 1984-10-09 Air Products And Chemicals, Inc. Process for separating carbon dioxide and sulfur-containing gases from a synthetic fuel production process off-gas

Also Published As

Publication number Publication date
DE3469492D1 (en) 1988-04-07
EP0147738A2 (en) 1985-07-10
DE3346038A1 (en) 1985-06-27
JPS60153920A (en) 1985-08-13
EP0147738A3 (en) 1986-10-22
ZA849808B (en) 1985-08-28
EP0147738B1 (en) 1988-03-02
IN163850B (en) 1988-11-26
US4609389A (en) 1986-09-02
ATE32665T1 (en) 1988-03-15

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