CA1048232A - Chlorine recovery with aqueous hydrochloric acid - Google Patents
Chlorine recovery with aqueous hydrochloric acidInfo
- Publication number
- CA1048232A CA1048232A CA75225465A CA225465A CA1048232A CA 1048232 A CA1048232 A CA 1048232A CA 75225465 A CA75225465 A CA 75225465A CA 225465 A CA225465 A CA 225465A CA 1048232 A CA1048232 A CA 1048232A
- Authority
- CA
- Canada
- Prior art keywords
- chlorine
- aqueous hydrochloric
- hydrochloric acid
- vapor
- gaseous mixture
- 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
Links
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- Drying Of Gases (AREA)
Abstract
ABSTRACT
Impure chlorine vapor, typically from the lique-faction step of a chlorine plant, is purified by contacting the vapor with aqueous hydrochloric acid which takes up the chlorine vapor but not the usual gaseous impurities The absorbed chlorine is separated from the acid and recovered by heating and/or by pressure reduction and the acid can be reused, preferably by recycling to contact other portions of the impure chlorine vapor.
Impure chlorine vapor, typically from the lique-faction step of a chlorine plant, is purified by contacting the vapor with aqueous hydrochloric acid which takes up the chlorine vapor but not the usual gaseous impurities The absorbed chlorine is separated from the acid and recovered by heating and/or by pressure reduction and the acid can be reused, preferably by recycling to contact other portions of the impure chlorine vapor.
Description
3;:
This invention provides a method for recovering at least a portion of the chlorine content of a gaseous mixture containing less than about 60 percent chlorine by weight comprising contacting said mixture with an aqueous hydrochloric acid solution of concentration between about 10 and 40 weight percent and at a temperature ranging from the freezing point of the solution to about 220F, which solution is supplied at a superatmospheric pressure, said gaseous mixture being supplied at a pressure not less than that of said solution, whereby a major portion of the chlorine content is absorbed leaving unabsorbed gases.
The solution containing the absorbed chlorine may then be separated from the unabsorbed gases. The aqueous acid containing absorbed chlorine may then be exposed to a reduced pressure or heated, or both, which causes release of the absorbed chlorine. The chlorine vapor is removed from the acid and the acid is recovered for further fluid contacting as by recycling, or is otherwise reused.
The drawing of Figure 1 illustrates in schematic form a preferred embodiment of a system using the method ~- of the present invention. ;
Figure 2 is a fragmentary schematic view of -a modification of the preferred embodiment shown in Figure 1.
The operation of a chlorine recovery system typical of the method of the present invention may be better understood by reference to Figure 1 together with the following description.
.,.
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gaseous mixture consi.sting of impure chlorine vapor is introduced through the supply pipe 11 to a con-tactor 12 wherein the vapor .is brought into contact with aqueous hydrochloric acid supplied under superatmospheric pressure by a supply pipe 13. A major portion of the ,:
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chlorine eontent of the gaseous mixture entering through the supply pipe ll is absorbed by thP aqueous acid~ gen-erating heat. This heat causes the temperature of the acid to rise. Tfie warmed acid is conducted by a pipe 14 leading from the contactor 12 to the flash pot 15. The acid under ~ pressure in pipe 14 is exposed subsequently to a pressure t ' drop in the flash pot 15 which is maintained at a lower pressure than the acid in pipe 14J such as atmospheric, or lower~ pressure. This results in rapid release of a major portion of the chlorine absorbed in the aqueous acid.
~he released chlorine vapor is extracted through a pipe 18 ~- and directed back to the drying and liquefaction step (not shown) or other suitable use.
The liberation of c~lorine vapor in the flash pot ~1 cools the acid solution 16 which is drawn into a pump 17 and returned to the contactor 12 at a superatmos-pheric pressure via the supply pipe 13. The residual gas - mixture remaining after substantîally all the chlorine has been removed therefrom is vented through an effluent pipe lO to a user of dilute chlorine vapor, such as an iron chloride production unit. Make-up agueous hydrochloric ~ acid is added through inlet pipe l9 to the contactor 12 - as required to replace that lost in the process.
The term gaseous mixture as used herein refers to impure chlorine vapor consisting of a mixture of chlorine and one or more yases with each of which aqueous hydrochloric acid is not completely miscible and is not reactive although trace amounts of reactive gases may be -~ tolerated. This gaseous mixture is supplied to the con-39 tactor a~ most any pressure reasonably contemplated in :'' 16,364-F -2-, 3~
chlorine m~nu~acturing processes. Usually the pr~ssure employed is that at which the Lmpure chlorine vapor i~
available. For example~ a chlorine vapor stream from a liquefaction plant may be at a pressure of about 50-65 pounds per square inch gauge (psig). ~igher pressures en~ance the extent to which chlorine vapor is absorbed in the contactor and are appropriate where the chlorLne con-tent of the 1uid is low, e.g.~ less than about 30 percent by weight. The chlorine is recoverable, according to the ~0 present inventionJ from a ~as mixture containing most any percentage of chlorine below about 60 weight percent although a content o between about 10 and about 60 weight percent chlorine is more likely to be encountered as a practical matter. A gaseous mixture containing more than about 60 weight percent chlorine vapor may be treated according to the invention but will usually be most econo-mically treated in another way as by liquefaction of the chlorine vapor. The temperature of the stream of impure chlorine vapor may be most any temperature likely to be ~o encountered in the operation of a liquefaction unit, al~hough chlorine is recovered more efficiently at lower temperatures since ths solubility of chlorine vapor in aqueous hydrochloric acid varies inversely with the tem- ;~
perature of the acid.
The contactor is a device, for example, a bubble cap tower or a packed column, in which two fluids can be intLmately admixed and then separated. Close contact between the aqueous hydrochloric acid and the impure chloxine vapor enhancesmore complete chlorine absorption.
16,364-F _3_ 3~
The efficiency of chlorine vapor absorption by ; aqueous hydrochloric acid varies depending upon the chlorine concentration, the contactor efficiency, the number of-contactors used in series, the gas to liquid ratio in the contactor and the temperature and pressure conditions inside the contactor~ all as generally under-stood i~ the art.
However, about 75 to about 90 weight percent ?
of the chlorine vapor eontent of the gaseous mixture is absorbed by the acid passing through the contactor in most cases. The unabsorbed portion consists of the unremoved chlorine and inerts such as oxygen, nitrogen, and traces of argo~ and helium. This remainder in a~nix-~` ture with some water vapor and hydrogen chloride absorbed .~ 15 in the tower or column is conducted to an absorber or other means for utilizing a stream of low chlorine contant. For example, alkaline brines, caustic scrubbersJ or devices which produce FeC13 or CaC12 may be proviaed to take up the residual chlorine in a safe and sometimes productive ~ 20 manner.
! ~ The aqueous hydrochloric acid may be supplied ; to the contactor, i.e., a tower or a colu~n, at any tem- perature between its freezing point and about 220F.
However, the lower the acid temperature, the lower will be the contacting temperature and the greater the percentage of chlorine absorbed. A temper~ture of between about 40F
and 80F is preferred; it is easily attainable and chlorine is much more soluble in aqueous hydrochloric acid than in water at such temperatures. The concentration o~ the hydrogen chloride in the aqueous hydrochloric acid should 16,364-F _4_ . ..
be between about 10 and about 40 weight percent, ideally about 25 percent by weight. The acid is supplied to the contactor at a supera~mospheric pressure, for example~
from about 40 to about 80 p5ig (about 3 to about 6 atmos-pheres). The high~r pressure facilitates absorption of chlorine vapor in the contactor and maintenance of a pres-sure drop in the flash pot to e~fect the escape or release of absorbed chlorinP from the acid solution.
The flash pot is an enclosed æone within which chlorine is liberated by pressure reduction or by heating or by a combination thereof. Maintaining the flash pot at a pressure lower than that of the chlorine enriched ~cid outlet o the contactor allows substantially all of the chlorine which was absorbed in the contactor to be recovered. Since other gases than chlorine tend to have a low solubility in the aqueous acid they are absorbed only to a small extent by the acid in passing through the - contactor. The acid stream leading to the flash pot is therefore essentially free of dissolved gases ot~er than chlorine. Thus ~he chlorine vapor stream removed throug~
the effluent pipe la leading from the flash pot usually contains from about 90 to about 99 weight percent chlorine;
the balance of this stre~m consists of water vapor and hydrogen chloride. After this stream is dried, it may be conveyed back to a liquefaction stage.
Some aqueous hydrochloric acid is lost through pipes 18 and 10 as water vapor and hydro~en chloride, ; replacement acid is added through pipe 19.
-;16,364-F ~5~
;23~:
Modifications to this basic system may be useul where the chlorine content of the gaseous mixture is low~
e.g., below about 30 percentg or where the chlorine is supplied at a relatively low pressure~ e.g.~ at about atmospheric.
one modification involves cooling the acid stream used in the chlorine vapor absorption process in the con-tactor. The resulting absorption is effected at a lower temperature wherein a greater percentage o chlorine is absorbed or the chlorine is absorbed at a higher rate.
This cooling may be accomplished wi~h heat exchangers, external refrigexation devices, or a combination thereof applied to recycled aqueous acid.
Another modification involves compressing the impure chlorine vapor stream and then cooling the so-compressed gases to provide a gas stream of highar pressure to the contactor. SuperatmQspheric pressures in the range from about 2 to about 5 atmosplleres facili-tate the efficient absorption o~ chlorine.
One may also provide multiple absorption towers or contactors as well as multiple flash pots in respective series to improve chlorine vapor recovery.
A particularly useful modification is an inte-grated sch~me for the combination of the present invention with a process for the purification of product stream chlorine utilizing aqueous hydrochloric acid to remove ~mpurities such as salt sprays~ waterg and nitrogen trichloride.
In this scheme the chlorine absorbed according to the practice o~ ~he present invention is released in 16,364-F -6-~4 ~ 2 ~ ~
tha zone in whîch the product stxeam is treated for removal of impurities. Maintenanc~ of a reduced pressure within an existing chlorine product stream scrubb~r allows r~ chlorine to be released therewithin, obviating the need for a flash pot.
Reference to ~igure 2 aids in the understanding of the method of this embodiment. Therein a vapor mixture ~' rich in chlorine from electrolytic cells is conducted by an inlet pipe 21 into a contactor 31 for purification.
Impurities contained in the gaseous mixture such as water~
salt spray3 and nitrogen trichloride are largely absorbed by the aqueous hydrochloric aci~ supplied by supply pipe 23 at a superatmospheric pressure. Acid is returned from tha contactor 31 at a reduced pressure relative to that in the supply pipe 23, e.g., atmospheric. The pressure in ~ ~
contactor 31 is lower than in contactor 12 or pipe 23. ~`
Exposure of the acid from pipe 23 to this pressure drop ~
1, , causes the release of a large portion of the chlorine con-tent of said acid which was obtained in the contactor 12 from the chlorine stream supplied through pipe 32 from a liquefaction unit aecording to the practice of the present r invention.
I The purified chlorine vapor from the electrolytic cells and the chlorine vapor released by the acid delivered by supply pipe 23 are removed by pipe 22 for further treat-~ ment~ eOg., by drying with H2S0~.
,; The aqueou~ hydrochloric acid is r~moved from the contactor 31 through the return pîpe 24 by the pump 17~ Thereaft~r a small portion of the acid is removed .: .
from the system by dilute acîd recovery pipe 27,o make-up .
' :
16,364-F -7-.. - . . ~
~4~
aqueous HCl .is added through pipe 25. ~he larger portion of the acid is cooled by its passage through a heat exchanger 26 and then is delivered to the contactor 12 by a pipe 28. The heat exchanger 26 is supplied wlth cool refrigerant by inlet pipe 29, warmed re~rigexant is removed through outlet pipe 30. The residual gas mixture remaining after substantially all the chloxine has been removed therefrom is vented through an effluent pipe 20 to a user of dilute chlorine vaporj such as an iron chloride production unit.
16,364-~ -8-
This invention provides a method for recovering at least a portion of the chlorine content of a gaseous mixture containing less than about 60 percent chlorine by weight comprising contacting said mixture with an aqueous hydrochloric acid solution of concentration between about 10 and 40 weight percent and at a temperature ranging from the freezing point of the solution to about 220F, which solution is supplied at a superatmospheric pressure, said gaseous mixture being supplied at a pressure not less than that of said solution, whereby a major portion of the chlorine content is absorbed leaving unabsorbed gases.
The solution containing the absorbed chlorine may then be separated from the unabsorbed gases. The aqueous acid containing absorbed chlorine may then be exposed to a reduced pressure or heated, or both, which causes release of the absorbed chlorine. The chlorine vapor is removed from the acid and the acid is recovered for further fluid contacting as by recycling, or is otherwise reused.
The drawing of Figure 1 illustrates in schematic form a preferred embodiment of a system using the method ~- of the present invention. ;
Figure 2 is a fragmentary schematic view of -a modification of the preferred embodiment shown in Figure 1.
The operation of a chlorine recovery system typical of the method of the present invention may be better understood by reference to Figure 1 together with the following description.
.,.
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, , . . ~ ~ : . . .
~4~;~3;~
gaseous mixture consi.sting of impure chlorine vapor is introduced through the supply pipe 11 to a con-tactor 12 wherein the vapor .is brought into contact with aqueous hydrochloric acid supplied under superatmospheric pressure by a supply pipe 13. A major portion of the ,:
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. ~
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chlorine eontent of the gaseous mixture entering through the supply pipe ll is absorbed by thP aqueous acid~ gen-erating heat. This heat causes the temperature of the acid to rise. Tfie warmed acid is conducted by a pipe 14 leading from the contactor 12 to the flash pot 15. The acid under ~ pressure in pipe 14 is exposed subsequently to a pressure t ' drop in the flash pot 15 which is maintained at a lower pressure than the acid in pipe 14J such as atmospheric, or lower~ pressure. This results in rapid release of a major portion of the chlorine absorbed in the aqueous acid.
~he released chlorine vapor is extracted through a pipe 18 ~- and directed back to the drying and liquefaction step (not shown) or other suitable use.
The liberation of c~lorine vapor in the flash pot ~1 cools the acid solution 16 which is drawn into a pump 17 and returned to the contactor 12 at a superatmos-pheric pressure via the supply pipe 13. The residual gas - mixture remaining after substantîally all the chlorine has been removed therefrom is vented through an effluent pipe lO to a user of dilute chlorine vapor, such as an iron chloride production unit. Make-up agueous hydrochloric ~ acid is added through inlet pipe l9 to the contactor 12 - as required to replace that lost in the process.
The term gaseous mixture as used herein refers to impure chlorine vapor consisting of a mixture of chlorine and one or more yases with each of which aqueous hydrochloric acid is not completely miscible and is not reactive although trace amounts of reactive gases may be -~ tolerated. This gaseous mixture is supplied to the con-39 tactor a~ most any pressure reasonably contemplated in :'' 16,364-F -2-, 3~
chlorine m~nu~acturing processes. Usually the pr~ssure employed is that at which the Lmpure chlorine vapor i~
available. For example~ a chlorine vapor stream from a liquefaction plant may be at a pressure of about 50-65 pounds per square inch gauge (psig). ~igher pressures en~ance the extent to which chlorine vapor is absorbed in the contactor and are appropriate where the chlorLne con-tent of the 1uid is low, e.g.~ less than about 30 percent by weight. The chlorine is recoverable, according to the ~0 present inventionJ from a ~as mixture containing most any percentage of chlorine below about 60 weight percent although a content o between about 10 and about 60 weight percent chlorine is more likely to be encountered as a practical matter. A gaseous mixture containing more than about 60 weight percent chlorine vapor may be treated according to the invention but will usually be most econo-mically treated in another way as by liquefaction of the chlorine vapor. The temperature of the stream of impure chlorine vapor may be most any temperature likely to be ~o encountered in the operation of a liquefaction unit, al~hough chlorine is recovered more efficiently at lower temperatures since ths solubility of chlorine vapor in aqueous hydrochloric acid varies inversely with the tem- ;~
perature of the acid.
The contactor is a device, for example, a bubble cap tower or a packed column, in which two fluids can be intLmately admixed and then separated. Close contact between the aqueous hydrochloric acid and the impure chloxine vapor enhancesmore complete chlorine absorption.
16,364-F _3_ 3~
The efficiency of chlorine vapor absorption by ; aqueous hydrochloric acid varies depending upon the chlorine concentration, the contactor efficiency, the number of-contactors used in series, the gas to liquid ratio in the contactor and the temperature and pressure conditions inside the contactor~ all as generally under-stood i~ the art.
However, about 75 to about 90 weight percent ?
of the chlorine vapor eontent of the gaseous mixture is absorbed by the acid passing through the contactor in most cases. The unabsorbed portion consists of the unremoved chlorine and inerts such as oxygen, nitrogen, and traces of argo~ and helium. This remainder in a~nix-~` ture with some water vapor and hydrogen chloride absorbed .~ 15 in the tower or column is conducted to an absorber or other means for utilizing a stream of low chlorine contant. For example, alkaline brines, caustic scrubbersJ or devices which produce FeC13 or CaC12 may be proviaed to take up the residual chlorine in a safe and sometimes productive ~ 20 manner.
! ~ The aqueous hydrochloric acid may be supplied ; to the contactor, i.e., a tower or a colu~n, at any tem- perature between its freezing point and about 220F.
However, the lower the acid temperature, the lower will be the contacting temperature and the greater the percentage of chlorine absorbed. A temper~ture of between about 40F
and 80F is preferred; it is easily attainable and chlorine is much more soluble in aqueous hydrochloric acid than in water at such temperatures. The concentration o~ the hydrogen chloride in the aqueous hydrochloric acid should 16,364-F _4_ . ..
be between about 10 and about 40 weight percent, ideally about 25 percent by weight. The acid is supplied to the contactor at a supera~mospheric pressure, for example~
from about 40 to about 80 p5ig (about 3 to about 6 atmos-pheres). The high~r pressure facilitates absorption of chlorine vapor in the contactor and maintenance of a pres-sure drop in the flash pot to e~fect the escape or release of absorbed chlorinP from the acid solution.
The flash pot is an enclosed æone within which chlorine is liberated by pressure reduction or by heating or by a combination thereof. Maintaining the flash pot at a pressure lower than that of the chlorine enriched ~cid outlet o the contactor allows substantially all of the chlorine which was absorbed in the contactor to be recovered. Since other gases than chlorine tend to have a low solubility in the aqueous acid they are absorbed only to a small extent by the acid in passing through the - contactor. The acid stream leading to the flash pot is therefore essentially free of dissolved gases ot~er than chlorine. Thus ~he chlorine vapor stream removed throug~
the effluent pipe la leading from the flash pot usually contains from about 90 to about 99 weight percent chlorine;
the balance of this stre~m consists of water vapor and hydrogen chloride. After this stream is dried, it may be conveyed back to a liquefaction stage.
Some aqueous hydrochloric acid is lost through pipes 18 and 10 as water vapor and hydro~en chloride, ; replacement acid is added through pipe 19.
-;16,364-F ~5~
;23~:
Modifications to this basic system may be useul where the chlorine content of the gaseous mixture is low~
e.g., below about 30 percentg or where the chlorine is supplied at a relatively low pressure~ e.g.~ at about atmospheric.
one modification involves cooling the acid stream used in the chlorine vapor absorption process in the con-tactor. The resulting absorption is effected at a lower temperature wherein a greater percentage o chlorine is absorbed or the chlorine is absorbed at a higher rate.
This cooling may be accomplished wi~h heat exchangers, external refrigexation devices, or a combination thereof applied to recycled aqueous acid.
Another modification involves compressing the impure chlorine vapor stream and then cooling the so-compressed gases to provide a gas stream of highar pressure to the contactor. SuperatmQspheric pressures in the range from about 2 to about 5 atmosplleres facili-tate the efficient absorption o~ chlorine.
One may also provide multiple absorption towers or contactors as well as multiple flash pots in respective series to improve chlorine vapor recovery.
A particularly useful modification is an inte-grated sch~me for the combination of the present invention with a process for the purification of product stream chlorine utilizing aqueous hydrochloric acid to remove ~mpurities such as salt sprays~ waterg and nitrogen trichloride.
In this scheme the chlorine absorbed according to the practice o~ ~he present invention is released in 16,364-F -6-~4 ~ 2 ~ ~
tha zone in whîch the product stxeam is treated for removal of impurities. Maintenanc~ of a reduced pressure within an existing chlorine product stream scrubb~r allows r~ chlorine to be released therewithin, obviating the need for a flash pot.
Reference to ~igure 2 aids in the understanding of the method of this embodiment. Therein a vapor mixture ~' rich in chlorine from electrolytic cells is conducted by an inlet pipe 21 into a contactor 31 for purification.
Impurities contained in the gaseous mixture such as water~
salt spray3 and nitrogen trichloride are largely absorbed by the aqueous hydrochloric aci~ supplied by supply pipe 23 at a superatmospheric pressure. Acid is returned from tha contactor 31 at a reduced pressure relative to that in the supply pipe 23, e.g., atmospheric. The pressure in ~ ~
contactor 31 is lower than in contactor 12 or pipe 23. ~`
Exposure of the acid from pipe 23 to this pressure drop ~
1, , causes the release of a large portion of the chlorine con-tent of said acid which was obtained in the contactor 12 from the chlorine stream supplied through pipe 32 from a liquefaction unit aecording to the practice of the present r invention.
I The purified chlorine vapor from the electrolytic cells and the chlorine vapor released by the acid delivered by supply pipe 23 are removed by pipe 22 for further treat-~ ment~ eOg., by drying with H2S0~.
,; The aqueou~ hydrochloric acid is r~moved from the contactor 31 through the return pîpe 24 by the pump 17~ Thereaft~r a small portion of the acid is removed .: .
from the system by dilute acîd recovery pipe 27,o make-up .
' :
16,364-F -7-.. - . . ~
~4~
aqueous HCl .is added through pipe 25. ~he larger portion of the acid is cooled by its passage through a heat exchanger 26 and then is delivered to the contactor 12 by a pipe 28. The heat exchanger 26 is supplied wlth cool refrigerant by inlet pipe 29, warmed re~rigexant is removed through outlet pipe 30. The residual gas mixture remaining after substantially all the chloxine has been removed therefrom is vented through an effluent pipe 20 to a user of dilute chlorine vaporj such as an iron chloride production unit.
16,364-~ -8-
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for recovering at least a portion of the chlorine content of a gaseous mixture containing less than about 60 percent chlorine by weight comprising contacting said mixture with an aqueous hydrochloric acid solution of concentration between about 10 and 40 weight percent and at a temperature ranging from the freezing point of the solution to about 220°F, which solution is supplied at a superatmospheric pressure, said gaseous mixture being supplied at a pressure not less than that of said solution, whereby a major portion of the chlorine content is absorbed leaving unabsorbed gases.
2. The method of Claim 1 wherein the solution containing absorbed chlorine is separated from said unabsorbed gases.
3. The method of Claim 2 wherein the absorbed chlorine is discharged from the aqueous hydrochloric acid by exposing the acid to at least one of (1) a pressure reduction and (2) heating sufficient to cause release of the chlorine as vapor.
4. The method of Claim 2 comprising the sequence of steps (a) sufficiently contacting the gaseous mixture with an aqueous hydrochloric acid solution to effect absorption of a major portion of the chlorine content of said gaseous mixture, (b) venting the remainder of the gaseous mixture, (c) exposing the acid to at least one of (1) a pressure reduction and (2) heating sufficient to release the absorbed chlorine as vapor from said acid solution, (d) removing the chlorine vapor from the vicinity of the aqueous acid, and (e) reusing the aqueous hydro-chloric acid for the recovery of chlorine.
5. The method of Claim 4 wherein the source of the gaseous mixture is the gaseous discharge from a chlorine liquefaction unit.
6. The method of Claim 4 wherein the gaseous mixture contains from about 10 to about 60 weight percent chlorine.
7. The method of Claim 4 wherein from about 75 to about 90 weight percent of the chlorine content of the gaseous mixture is recovered.
8. The method of Claim 4 wherein the concentra-tion of hydrogen chloride in the aqueous hydrochloric acid is about 25 weight percent.
9. The method of Claim 4 wherein the temperature of the aqueous hydrochloric acid when brought into contact with the gaseous mixture is from about 40° to about 80°F.
10. The method of Claim 4 carried out in conjunc-tion with scrubbing with aqueous hydrochloric acid the chlorine vapor product stream supplied from an electrolytic cell for making chlorine, wherein the aqueous hydrochloric acid utilized for scrubbing is aqueous hydrochloric acid which has absorbed a substantial portion of the chlorine content of said gaseous mixture containing less than about 60 percent by weight chlorine the said acid during said scrubbing being subjected to a pressure drop resulting in the release of absorbed chlorine as a vapor into the said product stream, whereby chlorine is added to the product stream and acid miscible impurities are removed from the product stream during the same step.
11. Method of Claim 1 which comprises concurrently recovering at least a portion of the chlorine content of a gaseous mixture containing less than about 60 weight percent chlorine vapor and scrubbing with an aqueous hydrochloric acid solution a product stream containing greater than about 60 weight percent chlorine vapor supplied from an electro-lytic cell at a predetermined superatmospheric pressure which comprises (a) feeding said aqueous hydrochloric acid solution into a contacting device concurrently with said product stream, which aqueous hydrochloric acid solution (1) has previously absorbed a substantial portion of the chlorine content of said gaseous mixture by having contacted it while said gaseous mixture was at a pressure not less than that of said acid solution, and (2) is under a pressure higher than said predetermined pressure, (b) scrubbing, in said contacting device at substantially said predetermined pressure, impurities from said product stream, which impurities enter into said aqueous hydrochloric acid solu-tion, (c) releasing at least a portion of the chlorine content of said aqueous hydrochloric acid solution as a vapor by exposure of said aqueous hydrochloric acid solu-tion to pressure reduction within said contacting device, which reduction is due to the difference between said pre-determined pressure of the chlorine vapor in the contacting device and the higher pressure of said aqueous hydrochloric acid solution admitted thereto, (d) separating said scrubbed product stream vapor from said aqueous hydrochloric acid solution containing said impurities, and (e) reusing said aqueous hydrochloric separated acid solution to recover chlorine from said gaseous mixture.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA75225465A CA1048232A (en) | 1975-04-25 | 1975-04-25 | Chlorine recovery with aqueous hydrochloric acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA75225465A CA1048232A (en) | 1975-04-25 | 1975-04-25 | Chlorine recovery with aqueous hydrochloric acid |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1048232A true CA1048232A (en) | 1979-02-13 |
Family
ID=4102906
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA75225465A Expired CA1048232A (en) | 1975-04-25 | 1975-04-25 | Chlorine recovery with aqueous hydrochloric acid |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1048232A (en) |
-
1975
- 1975-04-25 CA CA75225465A patent/CA1048232A/en not_active Expired
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