CA2102570A1 - Process to recover liquid methane - Google Patents
Process to recover liquid methaneInfo
- Publication number
- CA2102570A1 CA2102570A1 CA002102570A CA2102570A CA2102570A1 CA 2102570 A1 CA2102570 A1 CA 2102570A1 CA 002102570 A CA002102570 A CA 002102570A CA 2102570 A CA2102570 A CA 2102570A CA 2102570 A1 CA2102570 A1 CA 2102570A1
- Authority
- CA
- Canada
- Prior art keywords
- methane
- carbon dioxide
- gas mixture
- stage
- hydrocarbons
- 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.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L55/00—Devices or appurtenances for use in, or in connection with, pipes or pipe systems
- F16L55/02—Energy absorbers; Noise absorbers
- F16L55/027—Throttle passages
- F16L55/02745—Throttle passages by passing through a mass of particles or a porous member
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
- B60T17/002—Air treatment devices
- B60T17/008—Silencer devices
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L55/00—Devices or appurtenances for use in, or in connection with, pipes or pipe systems
- F16L55/02—Energy absorbers; Noise absorbers
- F16L55/033—Noise absorbers
Abstract
"PROCESS TO RECOVER LIQUID METHANE"
Abstract of the Disclosure To recover liquid methane from a feed gas mixture (1) essentially consisting of methane, C2+ hydrocarbons, carbon dioxide and nitrogen, the feed gas mixture (1) is fed first to an adsorption unit (E) and freed from water; dried feed gas mixture (2) is fed to a membrane separating unit (F), wherein the carbon dioxide is separated down to a residual content less than 2% by volume (9) and resultant gas mixture (3) now essentially consisting of methane, C2+ hydrocarbons and nitrogen is fed to a low-temperature distillation (A) wherein the C2+ hydrocarbons as well as the residual content of carbon dioxide are separated by distillation.
Abstract of the Disclosure To recover liquid methane from a feed gas mixture (1) essentially consisting of methane, C2+ hydrocarbons, carbon dioxide and nitrogen, the feed gas mixture (1) is fed first to an adsorption unit (E) and freed from water; dried feed gas mixture (2) is fed to a membrane separating unit (F), wherein the carbon dioxide is separated down to a residual content less than 2% by volume (9) and resultant gas mixture (3) now essentially consisting of methane, C2+ hydrocarbons and nitrogen is fed to a low-temperature distillation (A) wherein the C2+ hydrocarbons as well as the residual content of carbon dioxide are separated by distillation.
Description
P~OC$~ ~O RECOVB!R LIQ~ID ~E~ANB
The invention relates to a process to recover liguid methane ~rom a feed gas mixture compri6ing essentially methane, C2~ hydrocarbons, carbon dioxide and nitrogen.
Highly pure liquid methane is used to an increasing extent as a non-polluting ~uel Por diesel engines in locomo-tives, buses and trucks. The liquid methane is generally recovered ~rom natural gas. For example, in U~S. Patent No.
~,761,167, a process to recover methane from a gas ~ixture containing methane, C2~ hydrocarbons, carbon dioxide and nitrogen provides ~eeding the gas mixture first to a cryo-genic distillation stagef in which the C2~ hydrocarbon frac tion a6 well as a firist carbon dioxide fraction are re-: covered. The remaining CH4/N2/CO2 gas mixture is then con veyed to a pressure swing ad~orption stage where the mixture is freed from carbon dioxide. In a nitrogen separating unit i i downs~ream o~ the pressure swing adsorption stage, the re ~-sultant gas ~ixture is separated to provide the methane pro-duct fraction a~ well as a nitrogen fraction, and the latter ~ 20 is used to regenerate the adsorber loaded with carbon diox-'~
1,';
~,~
ide. This process is particularly useful i~t the nitrogen concentration in the feed gas mixture is approximately of the same order of magnitude as the methane concentration.
In an alternative to this process, there is employed, instead of the cryogenic distillation stage, an amine scrub-bing stage to separate the carbon dioxide from the feed gas mixture. In this case, is neceit~sary to employ a downstr~i?iam adsorption unik for drying the resultant water saiturated ~eed gas mixture from the amine washing stage. This proce-dure has the drawback, however, that the adsorption unit,because of the complPte water saturation of the gas stxeam exiting from the amine washing stage, must ~e very large.
Furthermore, the sy~tem must provide for the disposal or recycling of the amine scrubbing agent used in the carbon dioxide separation stage.
An object of one aspect of this invention is to provide a process to recover liquid methane, in which, on the one hand, an amine washing stage can be avoided, and, on the other hand, an adsorption unit can be used which is smaller in comparison with prior art procesiies.
To achieve this object according to the invention, a process is provided wherein:
a) the feed gas mixtur~? is fed fir~t to an adsorption unit and freed ~rom water in the latter;
b) the dried feed gas mixture is fed to a membrane ~ separation stage where the carbon dioxide is separated down I to a contenk lower than 2% by volume; and c) the gas mixture now essentially consisting of methane, C2~ hydrocarbon~ an~ nitrogen is fed to a low-temperature distillation stage wherein the C2+ hydrocarbons as well as the residual content of carbon dioxide are separated by distillation.
If desired, the resultant purified methane can be liquefied by an external refrigeration cycle and an expan-sion step. The resultant liquid methane is then transPerred to a storage tank. By virtue of boil-off from thP storage tank, the liquid is gradua].ly depleted in residual nitrogen, as one method of removing the nitrogen.
The combination according to the invention of adsorp-tion to dry the feed gas stream, membrane separation to re-move carbon dioxide, and low-temperature distillation to recover the liquid methane product stream results in a pro-cess that is very easy to operate, quick to start and eco-nomical. In addition to the water contained in the feed gas mixture, any glycol in the feed gas can also be removed by the adsorption stage. Adsorption processe~ to dry all types of gas streams are well known ~rom the literature. Adsorp-tion agents for the drying step of this invenkion include but are not limited to silica gel, activated alumina and molecular sieve (zeolite).
In the membrane separation stage, a reduction of the carbon dioxide content to less than 2% by volume, generally about 0.5 to 1.8% by volume, can be achiev~d with the - selection O:e suitable membranes in one, two or more separa-. . : . , ,~ :: . . . ~ : , ,.
tion stages, for example, a spinal wound membrane manufac-tured by Grace Membrane Systems from cellulosic acetate, described in Chemical Enqineerinq Proqress, January 1989, pages 41-62, "Economics of Gas Separation Membranes".
In the liquef~ction occurring in the downstream low-temperature distillation sta~e, the residual carbon dioxide together with the C2~ hydrocarbons is removed down to a con-centration of less than 50 ppm with very little additional expenditure over that generally required for the liquefac-10 tion of the methane. Moreover, this minor additional expen-diture is also offset, in that the gas stream exiting from the membrane separation unit enters the low temperature distillation stage at about 300 K~ In contrast, in the case of an amine scrubbing stage up~tream of the low temperature I distillation stage, the temperature of the exit gas was ¦ approximately 322 K. This 22 differencf again would, of course, entail an additional expenditure of energy ~or the liquefaction of the resultant gas within the low-temperature distillation stage.
In the process according to the invention, additional preferred features are optionally employed. In one, the carbon dioxide fraction recovered in the membrane s~paration stage is mixed together with the C2, hydrocarbon ~raction from the low-temperaturP distillation stage as well as with the boil-off gas from a liquid methane storage tank down-stream of the process, an~ the resultant mixture is fed to Sll - the adsorption unit as regenerati~g gas.
~ 4 ~
.,.,, . . ... .~ ,: , .-. -.- .
In a further development of the invention, it is pro-posed to compress in one stage or in multiple stages the carbon dioxide fraction, recovered in the membrane separat-ing unit, together with the bo~ o~f gas before mixing with the C2; hydrocarbon fraction.
In another advantageous embodiment of the process, in the low-temperature distillati.on, a column is provided to separate a liquid cut of C2~ hydrocarbons and the residual carbon dioxide. This liquid cut is vaporized by indirect heat exchange with the gas mixture from the membrane ~epa-ration stage, said gas mixture essentially consisting of methane, C2~ hydrocarbons and nitrogen, and having been previously cooled by a partial stream of a refrigeration cycle medium used for the low-temperature distillation stage.
Figure 1 is a box Plowsheet of the process of U.S.
The invention relates to a process to recover liguid methane ~rom a feed gas mixture compri6ing essentially methane, C2~ hydrocarbons, carbon dioxide and nitrogen.
Highly pure liquid methane is used to an increasing extent as a non-polluting ~uel Por diesel engines in locomo-tives, buses and trucks. The liquid methane is generally recovered ~rom natural gas. For example, in U~S. Patent No.
~,761,167, a process to recover methane from a gas ~ixture containing methane, C2~ hydrocarbons, carbon dioxide and nitrogen provides ~eeding the gas mixture first to a cryo-genic distillation stagef in which the C2~ hydrocarbon frac tion a6 well as a firist carbon dioxide fraction are re-: covered. The remaining CH4/N2/CO2 gas mixture is then con veyed to a pressure swing ad~orption stage where the mixture is freed from carbon dioxide. In a nitrogen separating unit i i downs~ream o~ the pressure swing adsorption stage, the re ~-sultant gas ~ixture is separated to provide the methane pro-duct fraction a~ well as a nitrogen fraction, and the latter ~ 20 is used to regenerate the adsorber loaded with carbon diox-'~
1,';
~,~
ide. This process is particularly useful i~t the nitrogen concentration in the feed gas mixture is approximately of the same order of magnitude as the methane concentration.
In an alternative to this process, there is employed, instead of the cryogenic distillation stage, an amine scrub-bing stage to separate the carbon dioxide from the feed gas mixture. In this case, is neceit~sary to employ a downstr~i?iam adsorption unik for drying the resultant water saiturated ~eed gas mixture from the amine washing stage. This proce-dure has the drawback, however, that the adsorption unit,because of the complPte water saturation of the gas stxeam exiting from the amine washing stage, must ~e very large.
Furthermore, the sy~tem must provide for the disposal or recycling of the amine scrubbing agent used in the carbon dioxide separation stage.
An object of one aspect of this invention is to provide a process to recover liquid methane, in which, on the one hand, an amine washing stage can be avoided, and, on the other hand, an adsorption unit can be used which is smaller in comparison with prior art procesiies.
To achieve this object according to the invention, a process is provided wherein:
a) the feed gas mixtur~? is fed fir~t to an adsorption unit and freed ~rom water in the latter;
b) the dried feed gas mixture is fed to a membrane ~ separation stage where the carbon dioxide is separated down I to a contenk lower than 2% by volume; and c) the gas mixture now essentially consisting of methane, C2~ hydrocarbon~ an~ nitrogen is fed to a low-temperature distillation stage wherein the C2+ hydrocarbons as well as the residual content of carbon dioxide are separated by distillation.
If desired, the resultant purified methane can be liquefied by an external refrigeration cycle and an expan-sion step. The resultant liquid methane is then transPerred to a storage tank. By virtue of boil-off from thP storage tank, the liquid is gradua].ly depleted in residual nitrogen, as one method of removing the nitrogen.
The combination according to the invention of adsorp-tion to dry the feed gas stream, membrane separation to re-move carbon dioxide, and low-temperature distillation to recover the liquid methane product stream results in a pro-cess that is very easy to operate, quick to start and eco-nomical. In addition to the water contained in the feed gas mixture, any glycol in the feed gas can also be removed by the adsorption stage. Adsorption processe~ to dry all types of gas streams are well known ~rom the literature. Adsorp-tion agents for the drying step of this invenkion include but are not limited to silica gel, activated alumina and molecular sieve (zeolite).
In the membrane separation stage, a reduction of the carbon dioxide content to less than 2% by volume, generally about 0.5 to 1.8% by volume, can be achiev~d with the - selection O:e suitable membranes in one, two or more separa-. . : . , ,~ :: . . . ~ : , ,.
tion stages, for example, a spinal wound membrane manufac-tured by Grace Membrane Systems from cellulosic acetate, described in Chemical Enqineerinq Proqress, January 1989, pages 41-62, "Economics of Gas Separation Membranes".
In the liquef~ction occurring in the downstream low-temperature distillation sta~e, the residual carbon dioxide together with the C2~ hydrocarbons is removed down to a con-centration of less than 50 ppm with very little additional expenditure over that generally required for the liquefac-10 tion of the methane. Moreover, this minor additional expen-diture is also offset, in that the gas stream exiting from the membrane separation unit enters the low temperature distillation stage at about 300 K~ In contrast, in the case of an amine scrubbing stage up~tream of the low temperature I distillation stage, the temperature of the exit gas was ¦ approximately 322 K. This 22 differencf again would, of course, entail an additional expenditure of energy ~or the liquefaction of the resultant gas within the low-temperature distillation stage.
In the process according to the invention, additional preferred features are optionally employed. In one, the carbon dioxide fraction recovered in the membrane s~paration stage is mixed together with the C2, hydrocarbon ~raction from the low-temperaturP distillation stage as well as with the boil-off gas from a liquid methane storage tank down-stream of the process, an~ the resultant mixture is fed to Sll - the adsorption unit as regenerati~g gas.
~ 4 ~
.,.,, . . ... .~ ,: , .-. -.- .
In a further development of the invention, it is pro-posed to compress in one stage or in multiple stages the carbon dioxide fraction, recovered in the membrane separat-ing unit, together with the bo~ o~f gas before mixing with the C2; hydrocarbon fraction.
In another advantageous embodiment of the process, in the low-temperature distillati.on, a column is provided to separate a liquid cut of C2~ hydrocarbons and the residual carbon dioxide. This liquid cut is vaporized by indirect heat exchange with the gas mixture from the membrane ~epa-ration stage, said gas mixture essentially consisting of methane, C2~ hydrocarbons and nitrogen, and having been previously cooled by a partial stream of a refrigeration cycle medium used for the low-temperature distillation stage.
Figure 1 is a box Plowsheet of the process of U.S.
4,761,167;
Figure 2 is a box flowsheet of a prior art process employing an amine scrubbing stage;
;: 20 Flgure 3 is a box ~lowsheet of the invention;
Figure 4 is a comprehensive schematic flowsheet of the :':
invention wherein two interchangeable adsorbers are employed and certain gas streams are recycled to the adsorbers for regeneration purposes; and : Figure 5 is a sch~matic comprehensive flowsheet of the low temperat:ure distillation stage of Figure 4 with ancil-lary equipment.
Figure 2 is a box flowsheet of a prior art process employing an amine scrubbing stage;
;: 20 Flgure 3 is a box ~lowsheet of the invention;
Figure 4 is a comprehensive schematic flowsheet of the :':
invention wherein two interchangeable adsorbers are employed and certain gas streams are recycled to the adsorbers for regeneration purposes; and : Figure 5 is a sch~matic comprehensive flowsheet of the low temperat:ure distillation stage of Figure 4 with ancil-lary equipment.
,,1 ;i Figure 1 represents a process as it is described in U.S. Patent No. 4 761 167. In this case, the feed gas stream is fed to cryogenic distillation stage A by pipe 1 and in the distillation, the C2+ hydrocarbons as well as a first carbon dioxide stream are recovered by pipe 5. A
CH4tN2tCOz gas mixture is fed to pressure swing adsorptior stage B by pipe 2. In it, an adsorptive separation of this gas mixture provides a C02-rich ~raction, discharged by pipe 6, and a CH4/N2-rich fraction, which is fed by pip2 3 to nitrogell separation unit C. While the methane product stream is recovered by pipe 4, the nitro~en fraction is re-cycled by pipe 7 to pressure swing adsorption stage B and used therein as regenerating gas for the adsorbers loaded with carbon dioxide.
Figure 2 shows a combination of an amine scrubbing D to ~emove the carbon dioxide, an adsorption unit E to dry the resultant C02 depleted feed ~as mixture and a cryogenic distillatio~ A to separate the C2+ hydrocarbons. The carbon ¦ dioxide separated in the amine scrubbing stage D is dis-charged by pipe 8, the water recovered in adsorption unit E
by pipe 6 and the C2, ~raction separated in cryogenic distillation A by pipe 5.
Figure 3 shows the process according to the invention, comprisin~ an adsorption unit E to dry the feed gas mixture, a membrane separation unit F to separate carbon dioxide as ~3 well as a low-temperature distillation stage A to separate - the dried gas stream, partially freed from carbon dioxide, !~ - 6 . .
!~
.:
into a liquid methane product fraction, which i5 discharyed by pipe 4, as well as in a C2+- and C02-containing ~raction, which is given o~f by pipe 5. The carbon dioxide fraction drawn off from membrane separation unit F by pipe 9, to-gether with the C2~- and C02-rich fraction drawn off from low-temperature dietillation A by pipe 5 and a boil-off gas brought in by pipe 10, which comes from a methane tank down-stream to this process, can be fed by pipe 11 to adsorption unit E as regenerating gas to regenerate the adsorber loaded with H20. As the ad~orption material in stage E, it is pre-~erred to employ molecular sieve (zeolite). As the membrane material in stage F, it is preferred to employ cellulosic acetate or a composite material (dimethylsilicone and poly-ester). Nitrogen in the methane can be removed in the boil-off gas or by intermediate flashing to a gas/liquid separa-tor or by a shipping column.
Figure 4 shows an embodiment of the process according to the invention analogous to Fiqure ~. The drying of the feed gas mixture from pipe 1 takes place in this case in an adsorption unit comprising at least two adsorbers E1 and E2.
The dried feed gas mixture is fed by pipe 2 to a membrane separation unit F, wherein carbon dioxide is separated and withdrawn by pipe 9~ The resultant gas mixture now essen-tially consisting of methane, Cz~ hydrocarbons and nitrogen is fed by pipe 3 to a low-temperature unit A wherein the C2~
hydrocarbons as well as the residual carbon dioxide are sep-arated by distillation and removed by pipe 5 and the nitro-~ 7 ,, . , , . , ,. . ,, ... . ... ~ . .. - . . ~ -gen is removed by expansion. The highly pure liquid methane product stream recovered in khe low-temperature distillation stage is conveyed by pipe 4 to liquid methane storage tank S. The boil-off gas escaping from liquid methane storage tank S is recycled by pipe lOa to the low-temperature unit A, warmed th~reon to transfer the refrigeration values and then fed by pipe lOb to comprlessor V, after being admixed with the CO2-rich process stream in pipe 9 from the membrane separation unit, After compression, this process stream is mixed with the Cz-rich ~raction in pipe 5 and fed to adsorb-ers E1 and E2 by pipe 11 as regenerating gas. The regene-rating gas loaded with water is discharged from the unit by pipe 12.
Figure 5 shows a detailed embodiment of the low-tempe-rature distillation stage of Figure 4. A conventional re-~rigerant mixture cycle G is used to provide the needed pro-ces~ refrigeration. The process stream conveyed from mem-brane separating unit F (fig. 3) by pipe 3 to the low-temperature distillation is first cooled in heat exchanger W1 countercurrently to the process streams to be heated.
Before being fed to column K, the resultant cooled proce~s stream from the membrane separation unit is further cooled in heat exchanger W4 by a C2-rich liquid stream drawn off from column K by pipe 20, which in turn is vaporized and is recycled into rolumn K below the plate holding said liquid stream. The head of column K is cooled by a partial stream drawn off in pipe 30 from refrigerant mixture cycle G. At :. . : . ~ ~
. , , ~ .. : , : : .-: : . : . - : . ., . . . ; , :
the bottom of column K, a c2t hydrocarbon fraction, in which the residual carbon dioxide is contained~ is drawn off by pipe 5, heated in heat ex~hanger Wl and then is discharged from the low-temperature stage. At the head of column K, a purified methane fraction is recovered, liquefied in heat exchanger W3 and conveyed by pipe 4 to liquid methane stor-age tank S. The boil-off gas exiting from this liquid methane storage tank S is conveyed by pipe lOa back to the low-temperature unit, heated in the latter in heat exchang ers W2 and Wl and is then removed by pipe lOh from the low-temperature unit.
Table 1 contains an exempli~ied material balance re-latîng to the process represented in Figures 4 and 5. In this case, the material balance data are calculated at the points in the process piping to which the respective re~er énce numbers pertain.
The invention is particularly applicable to the re-cov2ry of liquid methane from feed gases of the following composition: ~ by vol~me B.~.P.
C~+ 1-15 H20saturated This invention is applic~ble to the production of high-ly pure liquid methane which i5 defined herein as greater 1 than 99% by volume, preferably greater than 99.5~ by volume.
:f - 9 V 7~ r~
p ~ O o o O O ~ I_ ~_ ~1, p g O ~ O~ ~ O _ OU~ Ul o~
o ~ o ..
o o o ~ .
(D
o o r~l ~ ` o (D .
.~ _ ,o o _ Co 5.
~ _ W oo o ~ Cl~
tD
,_ ~ _ oo o ~ o o~o o ~ W
:: ~n ~;
~o ~
o o ~ _ _ :,, ~n 0 - ~ ~
: - o o o o ~., W
~:
c ~ o ~n ~ ~ o O O O ~ ~ ~D - ~n ~o o ~ ~ ~ o o o W ,~, - -' W _ ~ ~
o o o i The entire disclosures of all applications, patents, and publications, cited above, and of corresponding German Application P 42 37 620.3~ ~iled November 6, 1992, are hereby incorporated by reference.
CH4tN2tCOz gas mixture is fed to pressure swing adsorptior stage B by pipe 2. In it, an adsorptive separation of this gas mixture provides a C02-rich ~raction, discharged by pipe 6, and a CH4/N2-rich fraction, which is fed by pip2 3 to nitrogell separation unit C. While the methane product stream is recovered by pipe 4, the nitro~en fraction is re-cycled by pipe 7 to pressure swing adsorption stage B and used therein as regenerating gas for the adsorbers loaded with carbon dioxide.
Figure 2 shows a combination of an amine scrubbing D to ~emove the carbon dioxide, an adsorption unit E to dry the resultant C02 depleted feed ~as mixture and a cryogenic distillatio~ A to separate the C2+ hydrocarbons. The carbon ¦ dioxide separated in the amine scrubbing stage D is dis-charged by pipe 8, the water recovered in adsorption unit E
by pipe 6 and the C2, ~raction separated in cryogenic distillation A by pipe 5.
Figure 3 shows the process according to the invention, comprisin~ an adsorption unit E to dry the feed gas mixture, a membrane separation unit F to separate carbon dioxide as ~3 well as a low-temperature distillation stage A to separate - the dried gas stream, partially freed from carbon dioxide, !~ - 6 . .
!~
.:
into a liquid methane product fraction, which i5 discharyed by pipe 4, as well as in a C2+- and C02-containing ~raction, which is given o~f by pipe 5. The carbon dioxide fraction drawn off from membrane separation unit F by pipe 9, to-gether with the C2~- and C02-rich fraction drawn off from low-temperature dietillation A by pipe 5 and a boil-off gas brought in by pipe 10, which comes from a methane tank down-stream to this process, can be fed by pipe 11 to adsorption unit E as regenerating gas to regenerate the adsorber loaded with H20. As the ad~orption material in stage E, it is pre-~erred to employ molecular sieve (zeolite). As the membrane material in stage F, it is preferred to employ cellulosic acetate or a composite material (dimethylsilicone and poly-ester). Nitrogen in the methane can be removed in the boil-off gas or by intermediate flashing to a gas/liquid separa-tor or by a shipping column.
Figure 4 shows an embodiment of the process according to the invention analogous to Fiqure ~. The drying of the feed gas mixture from pipe 1 takes place in this case in an adsorption unit comprising at least two adsorbers E1 and E2.
The dried feed gas mixture is fed by pipe 2 to a membrane separation unit F, wherein carbon dioxide is separated and withdrawn by pipe 9~ The resultant gas mixture now essen-tially consisting of methane, Cz~ hydrocarbons and nitrogen is fed by pipe 3 to a low-temperature unit A wherein the C2~
hydrocarbons as well as the residual carbon dioxide are sep-arated by distillation and removed by pipe 5 and the nitro-~ 7 ,, . , , . , ,. . ,, ... . ... ~ . .. - . . ~ -gen is removed by expansion. The highly pure liquid methane product stream recovered in khe low-temperature distillation stage is conveyed by pipe 4 to liquid methane storage tank S. The boil-off gas escaping from liquid methane storage tank S is recycled by pipe lOa to the low-temperature unit A, warmed th~reon to transfer the refrigeration values and then fed by pipe lOb to comprlessor V, after being admixed with the CO2-rich process stream in pipe 9 from the membrane separation unit, After compression, this process stream is mixed with the Cz-rich ~raction in pipe 5 and fed to adsorb-ers E1 and E2 by pipe 11 as regenerating gas. The regene-rating gas loaded with water is discharged from the unit by pipe 12.
Figure 5 shows a detailed embodiment of the low-tempe-rature distillation stage of Figure 4. A conventional re-~rigerant mixture cycle G is used to provide the needed pro-ces~ refrigeration. The process stream conveyed from mem-brane separating unit F (fig. 3) by pipe 3 to the low-temperature distillation is first cooled in heat exchanger W1 countercurrently to the process streams to be heated.
Before being fed to column K, the resultant cooled proce~s stream from the membrane separation unit is further cooled in heat exchanger W4 by a C2-rich liquid stream drawn off from column K by pipe 20, which in turn is vaporized and is recycled into rolumn K below the plate holding said liquid stream. The head of column K is cooled by a partial stream drawn off in pipe 30 from refrigerant mixture cycle G. At :. . : . ~ ~
. , , ~ .. : , : : .-: : . : . - : . ., . . . ; , :
the bottom of column K, a c2t hydrocarbon fraction, in which the residual carbon dioxide is contained~ is drawn off by pipe 5, heated in heat ex~hanger Wl and then is discharged from the low-temperature stage. At the head of column K, a purified methane fraction is recovered, liquefied in heat exchanger W3 and conveyed by pipe 4 to liquid methane stor-age tank S. The boil-off gas exiting from this liquid methane storage tank S is conveyed by pipe lOa back to the low-temperature unit, heated in the latter in heat exchang ers W2 and Wl and is then removed by pipe lOh from the low-temperature unit.
Table 1 contains an exempli~ied material balance re-latîng to the process represented in Figures 4 and 5. In this case, the material balance data are calculated at the points in the process piping to which the respective re~er énce numbers pertain.
The invention is particularly applicable to the re-cov2ry of liquid methane from feed gases of the following composition: ~ by vol~me B.~.P.
C~+ 1-15 H20saturated This invention is applic~ble to the production of high-ly pure liquid methane which i5 defined herein as greater 1 than 99% by volume, preferably greater than 99.5~ by volume.
:f - 9 V 7~ r~
p ~ O o o O O ~ I_ ~_ ~1, p g O ~ O~ ~ O _ OU~ Ul o~
o ~ o ..
o o o ~ .
(D
o o r~l ~ ` o (D .
.~ _ ,o o _ Co 5.
~ _ W oo o ~ Cl~
tD
,_ ~ _ oo o ~ o o~o o ~ W
:: ~n ~;
~o ~
o o ~ _ _ :,, ~n 0 - ~ ~
: - o o o o ~., W
~:
c ~ o ~n ~ ~ o O O O ~ ~ ~D - ~n ~o o ~ ~ ~ o o o W ,~, - -' W _ ~ ~
o o o i The entire disclosures of all applications, patents, and publications, cited above, and of corresponding German Application P 42 37 620.3~ ~iled November 6, 1992, are hereby incorporated by reference.
Claims (11)
1. A process to recover methane from a feed gas mixture of methane, C2+ hydrocarbons, carbon dioxide, nitrogen and H2O, said process comprising:
a) introducing the feed gas mixture first to a regenerable adsorption stage (E) to selectively remove water therefrom;
b) passing the resultant dried feed gas mixture to a membrane separating stage (F) to selectively remove the carbon dioxide down to a residual content less than 2% by volume (9); and c) passing the resultant gas mixture of methane, C2+
hydrocarbons and nitrogen to a low-temperature distillation stage (A) to separate the C2+ hydrocarbons and the residual content of carbon dioxide from the methane.
a) introducing the feed gas mixture first to a regenerable adsorption stage (E) to selectively remove water therefrom;
b) passing the resultant dried feed gas mixture to a membrane separating stage (F) to selectively remove the carbon dioxide down to a residual content less than 2% by volume (9); and c) passing the resultant gas mixture of methane, C2+
hydrocarbons and nitrogen to a low-temperature distillation stage (A) to separate the C2+ hydrocarbons and the residual content of carbon dioxide from the methane.
2. A process according to claim 1 further comprising liquefying the resultant methane from the distillation stage, passing the liquefied methane to a liquid methane storage tank, and withdrawing boil-off gas from said storage tank, thereby gradually reducing the relative content of nitrogen in the liquefied methane.
3. A process according to claim 2 further comprising withdrawing resultant removed carbon dioxide from the mem-brane separating stage and mixing said carbon dioxide together with the separated C2+ hydrocarbon fraction from the low-temperature distillation stage and the boil-off gas from the liquid methane storage tank and passing the resultant mixture to the adsorption stage and employing said mixture as a regenerating gas to regenerate the adsorption stage.
4. A process according to claim 3, wherein the carbon dioxide recovered from the membrane separation stage, together with the boil-off gas is compressed before being mixed with the C2+ hydrocarbon fraction.
5. A process according to claim 2, wherein the membrane separation stage comprises at least two membrane separation units.
6. A process according to claim 1, wherein the adsorption stage comprises at least two interchangeable adsorbers.
7. A process according to claim 5, wherein the adsorption stage comprises at least two interchangeable adsorbers.
8. A process according to claim 1, said low-temperature distillation stage comprising a refrigeration cycle and a column to separate the C2+ hydrocarbons and the residual carbon dioxide, and wherein the separated C2+ hydro-carbons and the residual carbon dioxide are passed in indirect heat exchange relationship to the gas mixture from the membrane separation unit, said gas mixture consisting essentially of methane, C2+ hydrocarbons and nitrogen.
9. A process according to claim 3, said low-temperature distillation stage comprising a refrigeration cycle and a column to separate the C2+ hydrocarbons and the residual carbon dioxide, and wherein the separated C2+
hydrocarbons and the residual carbon dioxide are passed in indirect heat exchange relationship to the gas mixture from the membrane separation unit, said gas mixture consisting essentially of methane, C2+ hydrocarbons and nitrogen.
hydrocarbons and the residual carbon dioxide are passed in indirect heat exchange relationship to the gas mixture from the membrane separation unit, said gas mixture consisting essentially of methane, C2+ hydrocarbons and nitrogen.
10. A process according to claim 8, wherein said gas mixture is previously cooled by said refrigeration cycle prior to said indirect heat exchange.
11. A process according to claim 9, wherein said gas mixture is previously cooled by said refrigeration cycle prior to said indirect heat exchange.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4237630A DE4237630A1 (en) | 1992-11-05 | 1992-11-05 | Compressed air ventilation device |
| DEP4237630.3 | 1992-11-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2102570A1 true CA2102570A1 (en) | 1994-05-07 |
Family
ID=6472334
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002102570A Abandoned CA2102570A1 (en) | 1992-11-05 | 1993-11-05 | Process to recover liquid methane |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0596220B1 (en) |
| AT (1) | ATE136104T1 (en) |
| CA (1) | CA2102570A1 (en) |
| DE (2) | DE4237630A1 (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4412517C2 (en) * | 1994-04-12 | 1997-01-16 | Bbm Technik Ges Fuer Die Verwe | Blow-out silencer |
| DE4437315A1 (en) * | 1994-10-19 | 1996-04-25 | Bosch Gmbh Robert | Compressed air device with noise damper, in particular brake device for compressed air brake systems of motor vehicles |
| DE19701361C1 (en) * | 1997-01-16 | 1998-05-20 | Knorr Bremse Systeme | Sound damper for valve fittings in compressed air system of vehicle |
| DE102004036030A1 (en) * | 2004-07-23 | 2006-02-16 | Wabco Gmbh & Co.Ohg | Thread for acoustic insulation material, in particular for silencers in compressed air devices |
| DE202004011630U1 (en) | 2004-07-24 | 2004-11-11 | Wabco Gmbh & Co.Ohg | Muffler for compressed air equipment |
| DE102008029489A1 (en) | 2008-06-20 | 2009-12-24 | Wabco Gmbh | Silencer for compressed air systems of vehicles |
| DE102013013281A1 (en) * | 2013-08-09 | 2015-02-12 | Knorr-Bremse Systeme für Nutzfahrzeuge GmbH | Noise-reduced silencer for an air treatment plant |
| DE102014012709A1 (en) * | 2014-08-27 | 2016-03-03 | Wabco Gmbh | Valve unit for pressure modulation in a compressed air brake system |
| DE102015111515A1 (en) * | 2015-07-16 | 2017-01-19 | Knorr-Bremse Systeme für Nutzfahrzeuge GmbH | Silencer system |
| DE102015111512A1 (en) * | 2015-07-16 | 2017-01-19 | Knorr-Bremse Systeme für Nutzfahrzeuge GmbH | silencer |
| DE102016100140A1 (en) | 2016-01-05 | 2017-07-06 | Knorr-Bremse Systeme für Nutzfahrzeuge GmbH | Silencer for a compressed air system of a vehicle, in particular a commercial vehicle |
| DE102016100139A1 (en) * | 2016-01-05 | 2017-07-06 | Knorr-Bremse Systeme für Nutzfahrzeuge GmbH | Silencer for a compressed air system of a vehicle, in particular commercial vehicle |
| DE202016102158U1 (en) | 2016-04-22 | 2016-05-12 | Thoenes Dichtungstechnik Gmbh | Silencer material and silencer |
| DE102017122215A1 (en) | 2017-09-26 | 2019-03-28 | Knorr-Bremse Systeme für Nutzfahrzeuge GmbH | Silencer for compressed air systems and a method for its production |
| DE102019101556A1 (en) * | 2019-01-23 | 2020-07-23 | Wabco Gmbh | Vent cap on a solenoid valve in compressed air systems, for example for vehicles |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1851423U (en) * | 1962-03-08 | 1962-05-10 | Maria Tobisch | SILENCER. |
| DE2232559A1 (en) * | 1972-07-03 | 1974-01-24 | Messerschmitt Boelkow Blohm | SILENCERS TO REDUCE THE NOISE CREATED BY LEAKING GASES |
| DE2910209A1 (en) * | 1979-03-15 | 1980-09-25 | Wabco Fahrzeugbremsen Gmbh | NOISE SHOCK ABSORBER FOR VALVE DEVICES IN COMPRESSED AIR BRAKE SYSTEMS |
| DE2922677C2 (en) * | 1979-06-02 | 1982-12-09 | Wabco Fahrzeugbremsen Gmbh, 3000 Hannover | Silencer for valve devices in compressed air brake systems |
| DE2933105C2 (en) * | 1979-08-16 | 1983-12-15 | Robert Bosch Gmbh, 7000 Stuttgart | silencer |
| DE3216914A1 (en) * | 1982-05-06 | 1983-11-10 | Wabco Westinghouse Fahrzeugbremsen GmbH, 3000 Hannover | NOISE SHOCK ABSORBER FOR VALVE DEVICES IN COMPRESSED AIR BRAKE SYSTEMS |
| DE3327902A1 (en) * | 1983-08-02 | 1985-02-14 | Knorr-Bremse GmbH, 8000 München | NOISE SHOCK ABSORBER FOR VALVE ARRANGEMENTS IN COMPRESSED AIR SYSTEMS, ESPECIALLY IN VEHICLE AIR BRAKE SYSTEMS |
| DE3832030A1 (en) * | 1988-09-21 | 1990-03-29 | Wabco Westinghouse Fahrzeug | SOUND ABSORBER |
| DE3901335A1 (en) * | 1989-01-18 | 1990-07-19 | Knorr Bremse Ag | MUFFLER |
-
1992
- 1992-11-05 DE DE4237630A patent/DE4237630A1/en not_active Withdrawn
-
1993
- 1993-09-10 EP EP93114557A patent/EP0596220B1/en not_active Expired - Lifetime
- 1993-09-10 DE DE59302041T patent/DE59302041D1/en not_active Expired - Lifetime
- 1993-09-10 AT AT93114557T patent/ATE136104T1/en active
- 1993-11-05 CA CA002102570A patent/CA2102570A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| EP0596220B1 (en) | 1996-03-27 |
| EP0596220A1 (en) | 1994-05-11 |
| DE4237630A1 (en) | 1994-05-11 |
| DE59302041D1 (en) | 1996-05-02 |
| ATE136104T1 (en) | 1996-04-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5414190A (en) | Process to recover liquid methane | |
| CA2102570A1 (en) | Process to recover liquid methane | |
| CA1302051C (en) | Removel of mercury from gases | |
| US5842357A (en) | Landfill gas recovery | |
| US3312073A (en) | Process for liquefying natural gas | |
| US4372925A (en) | Process for the removal of acid gases from gas mixtures containing methane | |
| US5486227A (en) | Integrated process for purifying and liquefying a feed gas mixture with respect to its less strongly adsorbed component of lower volatility | |
| AU2002323607B2 (en) | High-pressure separation of a multi-component gas | |
| US4229188A (en) | Selective adsorption process | |
| US4238204A (en) | Selective adsorption process | |
| NZ502042A (en) | Methane rich gas liquefaction at expansion pressure below liquid bubble point | |
| RU2730344C1 (en) | Extraction of helium from natural gas | |
| EP0234895B1 (en) | Recovery of argon | |
| US4606741A (en) | Process for purifying natural gas | |
| US3691779A (en) | Hydrogen purification | |
| FR1575098A (en) | ||
| US7964025B2 (en) | Reclaiming carbon dioxide from boiler flue gas | |
| MY112365A (en) | Multi-component regrigeration process for liquefaction of natural gas. | |
| GB2069118A (en) | Method for purifying a gas mixture | |
| US7678349B2 (en) | System for liquefying light hydrocarbon gas with a plurality of light hydrocarbon gas liquefaction trains | |
| US4659351A (en) | Combined process to produce liquid helium, liquid nitrogen, and gaseous nitrogen from a crude helium feed | |
| US3126266A (en) | Meisler | |
| US4332598A (en) | Process for treating industrial gas stream | |
| US3599438A (en) | Crude helium enrichment process | |
| AU7878198A (en) | Process for the conversion of a flow containing hydrocarbons by partial oxidation |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |