CA1156428A - Process for the concentration and cleaning of sulfuric acid - Google Patents
Process for the concentration and cleaning of sulfuric acidInfo
- Publication number
- CA1156428A CA1156428A CA000347107A CA347107A CA1156428A CA 1156428 A CA1156428 A CA 1156428A CA 000347107 A CA000347107 A CA 000347107A CA 347107 A CA347107 A CA 347107A CA 1156428 A CA1156428 A CA 1156428A
- Authority
- CA
- Canada
- Prior art keywords
- acid
- sulfuric acid
- h2so4
- heating
- vessel
- 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
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/69—Sulfur trioxide; Sulfuric acid
- C01B17/90—Separation; Purification
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/69—Sulfur trioxide; Sulfuric acid
- C01B17/90—Separation; Purification
- C01B17/905—Removal of organic impurities
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
- Cleaning Or Drying Semiconductors (AREA)
Abstract
ABSTACT OF THE DISCLOSURE
The invention provides a two-step process for cleaning impurities from waste sulfuric acid and increasing the H2SO4 content comprising in a first step heating waste sulfuric acid in a first vessel in a series of stages, the last stage of which is at a pressure of 10 to 20 millibars absolute; and then in a second step electrically heating the waste sulfuric acid from the first step in a second vessel at a temperature of at least 280°C under atmospheric or super atmospheric pressure until the sulfuric acid attains a concentration of about 90-98 weight percent H2SO4.
The invention provides a two-step process for cleaning impurities from waste sulfuric acid and increasing the H2SO4 content comprising in a first step heating waste sulfuric acid in a first vessel in a series of stages, the last stage of which is at a pressure of 10 to 20 millibars absolute; and then in a second step electrically heating the waste sulfuric acid from the first step in a second vessel at a temperature of at least 280°C under atmospheric or super atmospheric pressure until the sulfuric acid attains a concentration of about 90-98 weight percent H2SO4.
Description
4 ~ ~
The present invention relates to a process for the concentrati~n and cleaniny of sulfuric acid.
secause of ecological effects, the recycling of sulfuric acid is hecoming more ancl more irnpor~ant. The problem is to increase the concentration of dilute sulfuric acid solutions and to clean dirty sulfuric acid solutions to the point where they can be termed "technically clean". In order to be termed "technically clean", the sulfuric acid must comprise from 96 to 98 weight percent H2SO4. Furthermore, organic impurities must be removed and inorganic impurities must be reduced to a point where they are soluble. It is furthermore desirable that the process for removing the organic impurities not be substance specific, but universally applicable. Thus the waste acids can be treated indépendently of their origin. As the same time, the cleaning process should not result in any additional undesirable ecological effects. Finally, the entire process should be economically advantageous, which, in the ideal case, means that the recycled sulfuric acid should be no more expensive than the use of fresh sulfuric acid including with it the combined necessary finishing costs, for example, neutralization.
Cost-calculations have shown that this may be achieved only when the concentration process and the cleaning process are separate.
In the concentrationprocess, the costs are controlled mainly by the heating costs. However, storage and maintenance costs have the greatest effect on the cleaning process.
A great number of concentration processes for sulfuric acid are known. An example of one oE the more recent is DE-AS
The present invention relates to a process for the concentrati~n and cleaniny of sulfuric acid.
secause of ecological effects, the recycling of sulfuric acid is hecoming more ancl more irnpor~ant. The problem is to increase the concentration of dilute sulfuric acid solutions and to clean dirty sulfuric acid solutions to the point where they can be termed "technically clean". In order to be termed "technically clean", the sulfuric acid must comprise from 96 to 98 weight percent H2SO4. Furthermore, organic impurities must be removed and inorganic impurities must be reduced to a point where they are soluble. It is furthermore desirable that the process for removing the organic impurities not be substance specific, but universally applicable. Thus the waste acids can be treated indépendently of their origin. As the same time, the cleaning process should not result in any additional undesirable ecological effects. Finally, the entire process should be economically advantageous, which, in the ideal case, means that the recycled sulfuric acid should be no more expensive than the use of fresh sulfuric acid including with it the combined necessary finishing costs, for example, neutralization.
Cost-calculations have shown that this may be achieved only when the concentration process and the cleaning process are separate.
In the concentrationprocess, the costs are controlled mainly by the heating costs. However, storage and maintenance costs have the greatest effect on the cleaning process.
A great number of concentration processes for sulfuric acid are known. An example of one oE the more recent is DE-AS
2,242,055. At concentrations less than 90 weight per cent H2SO4 basically ali usual evaporation systems can be employed, such as the so-called kettle system, natural circuit system, re-circulation system, and the film evaporation system as long as the construction, the selection of materials and the operating - 1 - ~;~
1 ~ 5~j~2~
temperatures are properl~ selected. Fven immersiorl heating systems can be selected.
For the concentr~-tlon of sulfuric ~cid haviny over gO~
H2SO4, there are only two possibilities. First evapora-t:ion under atmospheric pressure at a temperature up ~o 330C. In this process, the only practical heating medium is natural gas. 'rhe second possibility is distillation under vacuum at a pressure as low as 5 millibars absolute wherein the temperature can be lowered to 160CC. In such a process, common heating steam having a pressure, for example, of 16 bars can be emplo~ed.
Cleaning processes for sulfuric acid, by which is meant processes for the removal of organic impurities, are known only in limited numbers.
At the present time, there is only one process that is in practical universal use. That is the self-cleaning of sulfuric acid by the oxidation of the organic impurities at concentrations in excess of 96 weight percent of H2SO4 and at temperatures between 270 and 330C. This principle has up to the present time only been employed in a Pauling-Kettle where it is employed in combination with concentrating the acid. However, because of corrosion and wear and tear, the installation costs and the maintenance oosts are too high.
Cleaning processes with an oxidizing agent such as nitric acid or hydrogen peroxide are not widel~ used. Particular-ly so because of the exhaust gas problern with HNO3 and the uneconomical piping costs for H2O2.
Furthermore, direct electrolysis results in incomplete oxidation. It is not employed because of hydrogen evolution and costs connected with the use of platinum electrodes.
Accordingly, the present invention provides a process for the concentration and cleaning of sulfuric acid substantially free of one or more of the disadvantages of known processes.
2 ~
.
According to the present invention there is provided a process for concen-trating and cleaning waste sulfuric acid comprising the steps of: I. concent.rating waste sulfuric acid to about 94% H2SO4 by heating it in a f;.rst vessel .in one or more stages, the last stage of which is at a pressure of 10 to 20 ~n:Lllibars absolute, maintaining a maximum temperature of about 170 C, II. transEerring the 94% H2SO4 acid to a second vessel which is enamel lined, III. cleaning the 94% H2SO4 acid in the second vessel under atmospheric or super atmospheric pressure by electrically heating at a temperature between 270 and 330C in order to oxidize organic impurities, and IV. re-covering the clean sulfuric acid of 94~ or greater up to 98%
H2SO4.
In a particular embodiment thereof the present inven-tion provides a process for concentrating waste sulfuric acid and removing impurities therefrom comprising heating waste sulfuric acid in a recirculation evaporator at normal pressure utilizing steam having a pressure of 16 bars and employing a temperature of 160C to effect removal of water and thereby concentrate the sulfuric acid to about 90% H2SO4, changing the pressure of the recirculating evaporator to about 10-20 milli-bars absolute pressure and maintaining a maximum temperature of about 170C with heating with saturated steam in order to concentrate the sulfuric acid to about 94~ H2SO~, removing and cooling the water vapors being distilled from the acid by directly contacting the vapors with cold water at 0C, minimi~-ing the H2SO4 content of the water vapors b.y purification using a spray of weak acid, transferring the 94~ H2S04 acid to a second vessel which is enamel lined, heating the 94~ H2SO4 acid electricallry by use of an infra~red heating means protected by quartz pipes and submerged in the acid in the vessel under atmospheric or super atmospheric pressure, the heating being
1 ~ 5~j~2~
temperatures are properl~ selected. Fven immersiorl heating systems can be selected.
For the concentr~-tlon of sulfuric ~cid haviny over gO~
H2SO4, there are only two possibilities. First evapora-t:ion under atmospheric pressure at a temperature up ~o 330C. In this process, the only practical heating medium is natural gas. 'rhe second possibility is distillation under vacuum at a pressure as low as 5 millibars absolute wherein the temperature can be lowered to 160CC. In such a process, common heating steam having a pressure, for example, of 16 bars can be emplo~ed.
Cleaning processes for sulfuric acid, by which is meant processes for the removal of organic impurities, are known only in limited numbers.
At the present time, there is only one process that is in practical universal use. That is the self-cleaning of sulfuric acid by the oxidation of the organic impurities at concentrations in excess of 96 weight percent of H2SO4 and at temperatures between 270 and 330C. This principle has up to the present time only been employed in a Pauling-Kettle where it is employed in combination with concentrating the acid. However, because of corrosion and wear and tear, the installation costs and the maintenance oosts are too high.
Cleaning processes with an oxidizing agent such as nitric acid or hydrogen peroxide are not widel~ used. Particular-ly so because of the exhaust gas problern with HNO3 and the uneconomical piping costs for H2O2.
Furthermore, direct electrolysis results in incomplete oxidation. It is not employed because of hydrogen evolution and costs connected with the use of platinum electrodes.
Accordingly, the present invention provides a process for the concentration and cleaning of sulfuric acid substantially free of one or more of the disadvantages of known processes.
2 ~
.
According to the present invention there is provided a process for concen-trating and cleaning waste sulfuric acid comprising the steps of: I. concent.rating waste sulfuric acid to about 94% H2SO4 by heating it in a f;.rst vessel .in one or more stages, the last stage of which is at a pressure of 10 to 20 ~n:Lllibars absolute, maintaining a maximum temperature of about 170 C, II. transEerring the 94% H2SO4 acid to a second vessel which is enamel lined, III. cleaning the 94% H2SO4 acid in the second vessel under atmospheric or super atmospheric pressure by electrically heating at a temperature between 270 and 330C in order to oxidize organic impurities, and IV. re-covering the clean sulfuric acid of 94~ or greater up to 98%
H2SO4.
In a particular embodiment thereof the present inven-tion provides a process for concentrating waste sulfuric acid and removing impurities therefrom comprising heating waste sulfuric acid in a recirculation evaporator at normal pressure utilizing steam having a pressure of 16 bars and employing a temperature of 160C to effect removal of water and thereby concentrate the sulfuric acid to about 90% H2SO4, changing the pressure of the recirculating evaporator to about 10-20 milli-bars absolute pressure and maintaining a maximum temperature of about 170C with heating with saturated steam in order to concentrate the sulfuric acid to about 94~ H2SO~, removing and cooling the water vapors being distilled from the acid by directly contacting the vapors with cold water at 0C, minimi~-ing the H2SO4 content of the water vapors b.y purification using a spray of weak acid, transferring the 94~ H2S04 acid to a second vessel which is enamel lined, heating the 94~ H2SO4 acid electricallry by use of an infra~red heating means protected by quartz pipes and submerged in the acid in the vessel under atmospheric or super atmospheric pressure, the heating being
- 3 -h~- "t'' ~, s ~
at a temperature between 270~C and 330C in order to oxidize organic impurities, and recovering the clean 94% or greater H2SO4 sulfuric acid.
~aste sulfuric acid generally has a concentration Gf - 3a -,.
1 l~G~
20 to 70 weight percen-t ll2SO4. The concc~rl-tration of sulfuric acid having a lower concentration, es~ecially a conccn-tratiorl less than 50 weight percen-t l~2SO4, is purely an energy cost problem.
The process o~ the present invention advantageously employs a circulating st,eam sys-tern to concentrate the sulfuric acid. In this way, it is po.ssible to make use o~ the vapor energy.
Because o~ the high heat transfer values in the heatiny vessel of this evaporator high speciflc pressures are ob~ained. With the vacuum evaporation, which is exclusively heated with saturated steam, acid concentrations of at least 90~ and preferably 94~
H2SO4 are achieved. Immediately thereafter the sul~uric acid is led to a cleaning ves.sel and under normal pressure heated to a temperature of at least 270C and no more than 330C. This destroys the organic impurities.
The advantages of the preceding will be apparent by comparison to the requisite heat effeciency of a Pauling-Vessel that is continually charged with a 70 weight percent sulfuric acid solution and which is concentrated to 96 weight percent H2SO4 and which must be simultaneously cleaned. Consider especially that in the second step of the process of the present invention the acid is only concentrated to a small extent and is almost entirely a cleaning process. For each 1,000 kilograms of 96 weight percent sulfuric acid, there are 371 kilograms of water evaporated in the first step and only 21 kilograms in the second step. This greatly decreased thermal energy demand of the cleaning vessel allows one to introduce an industrial material not previously employed and a heating system which achieves the greatest advantages of the inventive process.
The concentration process utilizes a recirculatin~
30 , evaporator and is designed to have multistages. Preponderantly a pressure circulating evaporator is employed which has the advantage that the heat transfer value of the heater (stear.-heated) 1 ~ ~ B~ ~ ~
in contrast to the natural cycle evaporator is not dependent on the temperature difference between the boiliny acid and the condensation temperature o~ the steam ~or heating. This fact is important when, in order to save energ~, two evaporator stages are operated with waste steam. For the end concentration of processing to 90% HzSO4 the evaporator system is operated under normal pressure or under vacuum, such that the operating pressure is so chosen that the boiling point lies between 120 and 160C. Of course, in the sys-tem utilizing waste steam, the boiling point in the secondary system must as much as possible lie under 80C, in order to have available an adequate temperature difference between the heating medium and the acid.
For concentrations greater than 90% H2SO4, a few details of the evaporator axe changed:
The operating pressure is dropped to about 10-20 millibars absolute pressure. This gives an H2SO~ concentration of about 94~ at a boiling point maximum of 170C. In that situation operation with 16 bar steam for heating ~tc~nd=200C) is still possible. For the water vapor condensation (Condensation temperature about 8C) the vapors are either directly worked with cold water at 0C or supercharged with a steam jet at about 60 Torr. To minimize the H2SO4 content in the water vapors a purification process with injected weak acid is employed.
According to the invention the finishing process can be interrupted with this second acid-concentration or it can proceed directly by carrying the acid over into the cleaning stage.
The cleaning process is practiced in a manner alone known in the art but now known in combination with the other steps that make up the process of the present invention. In the cleaning process, the concentrated waste sulfuric from Step 1 is raised to a high temperature o~ 270to 330C. In this manner, the or~anic impurities are oxidized.
1 ~5~2~
Because of -the face that the waste sulfuric acid has been concentrated in a previous firs-t step -to approxirnately 94 weight percent 1125O~, th~re are a number of remarkahle advantages:
(a) First, the eneryy u-tilization for cleaniny constitutes onl~ about 120 kilowatts per 1,000 kilograms of waste sulfuric acid, based on waste sulfuric acid comprising 96 weight percent H2SO4. As previously described, waste sulfuric acid having this weight percent of H2SO4 is achieved by means of Step 1.
(b) Second, this relatively small energy utilization makes the use of electric current especially advantageous as a means for providing energy to Step II. In this manner, there is a wide departure from the previously employed natural gas heating with its attendant pyrotechnic display.
(c) Third, the use of electrical current permits the direct heating of the sulfuric acid by use of infrared heating that can be supplied to the vessels in protective pipes construct-ed of quartz glass, for example, which are submerged in the waste sulfuric acid.
(d) Fourth, the use of radiant heating indicated above has the additional advantage of not requiring the heat to be supplied to the vessel through the walls of the vessel. This is a great advantage over previous processes which require the temperature of the walls of the vessel to be higher than the contents of the vessel. This creates special advantages with respect to corrosion and permits the use of standard construction materials.
(e) Fifth, because of the use of radiant heat, the vessel can be constructed of steel having an enamel coating.
This is because the temperature level of the walls will not rise above the temperature of the waste sulEuric acid in the vessel.
; 4 2 ~
In the above manner, -the prob]ern of vessel corrosion has been solved. Furtherrnore, the main disadvantaye of hiyh temperature cleaning, nalrlely, the larye mainkenance costs of the apparatus have been avoided. By means of the combina-tion of concentraticn stepsand cleaning steps as in the above-described manner, as well as by the use of especially acid-resistant construction materials such as glass, enameled glass, tantalum, graphite, and polytetrafluoroethylene for the construc-tion of the apparatus one achieves the greatest possible reduction in construction costs and operating expenses.
At the same time, the disadvantages commonly grouped under the term of art "acid problems", have been avoided. In accordance with the present invention, the regeneration of waste sulfuric acid at many locations will be economically attractive under conditions which result in a clean environment.
at a temperature between 270~C and 330C in order to oxidize organic impurities, and recovering the clean 94% or greater H2SO4 sulfuric acid.
~aste sulfuric acid generally has a concentration Gf - 3a -,.
1 l~G~
20 to 70 weight percen-t ll2SO4. The concc~rl-tration of sulfuric acid having a lower concentration, es~ecially a conccn-tratiorl less than 50 weight percen-t l~2SO4, is purely an energy cost problem.
The process o~ the present invention advantageously employs a circulating st,eam sys-tern to concentrate the sulfuric acid. In this way, it is po.ssible to make use o~ the vapor energy.
Because o~ the high heat transfer values in the heatiny vessel of this evaporator high speciflc pressures are ob~ained. With the vacuum evaporation, which is exclusively heated with saturated steam, acid concentrations of at least 90~ and preferably 94~
H2SO4 are achieved. Immediately thereafter the sul~uric acid is led to a cleaning ves.sel and under normal pressure heated to a temperature of at least 270C and no more than 330C. This destroys the organic impurities.
The advantages of the preceding will be apparent by comparison to the requisite heat effeciency of a Pauling-Vessel that is continually charged with a 70 weight percent sulfuric acid solution and which is concentrated to 96 weight percent H2SO4 and which must be simultaneously cleaned. Consider especially that in the second step of the process of the present invention the acid is only concentrated to a small extent and is almost entirely a cleaning process. For each 1,000 kilograms of 96 weight percent sulfuric acid, there are 371 kilograms of water evaporated in the first step and only 21 kilograms in the second step. This greatly decreased thermal energy demand of the cleaning vessel allows one to introduce an industrial material not previously employed and a heating system which achieves the greatest advantages of the inventive process.
The concentration process utilizes a recirculatin~
30 , evaporator and is designed to have multistages. Preponderantly a pressure circulating evaporator is employed which has the advantage that the heat transfer value of the heater (stear.-heated) 1 ~ ~ B~ ~ ~
in contrast to the natural cycle evaporator is not dependent on the temperature difference between the boiliny acid and the condensation temperature o~ the steam ~or heating. This fact is important when, in order to save energ~, two evaporator stages are operated with waste steam. For the end concentration of processing to 90% HzSO4 the evaporator system is operated under normal pressure or under vacuum, such that the operating pressure is so chosen that the boiling point lies between 120 and 160C. Of course, in the sys-tem utilizing waste steam, the boiling point in the secondary system must as much as possible lie under 80C, in order to have available an adequate temperature difference between the heating medium and the acid.
For concentrations greater than 90% H2SO4, a few details of the evaporator axe changed:
The operating pressure is dropped to about 10-20 millibars absolute pressure. This gives an H2SO~ concentration of about 94~ at a boiling point maximum of 170C. In that situation operation with 16 bar steam for heating ~tc~nd=200C) is still possible. For the water vapor condensation (Condensation temperature about 8C) the vapors are either directly worked with cold water at 0C or supercharged with a steam jet at about 60 Torr. To minimize the H2SO4 content in the water vapors a purification process with injected weak acid is employed.
According to the invention the finishing process can be interrupted with this second acid-concentration or it can proceed directly by carrying the acid over into the cleaning stage.
The cleaning process is practiced in a manner alone known in the art but now known in combination with the other steps that make up the process of the present invention. In the cleaning process, the concentrated waste sulfuric from Step 1 is raised to a high temperature o~ 270to 330C. In this manner, the or~anic impurities are oxidized.
1 ~5~2~
Because of -the face that the waste sulfuric acid has been concentrated in a previous firs-t step -to approxirnately 94 weight percent 1125O~, th~re are a number of remarkahle advantages:
(a) First, the eneryy u-tilization for cleaniny constitutes onl~ about 120 kilowatts per 1,000 kilograms of waste sulfuric acid, based on waste sulfuric acid comprising 96 weight percent H2SO4. As previously described, waste sulfuric acid having this weight percent of H2SO4 is achieved by means of Step 1.
(b) Second, this relatively small energy utilization makes the use of electric current especially advantageous as a means for providing energy to Step II. In this manner, there is a wide departure from the previously employed natural gas heating with its attendant pyrotechnic display.
(c) Third, the use of electrical current permits the direct heating of the sulfuric acid by use of infrared heating that can be supplied to the vessels in protective pipes construct-ed of quartz glass, for example, which are submerged in the waste sulfuric acid.
(d) Fourth, the use of radiant heating indicated above has the additional advantage of not requiring the heat to be supplied to the vessel through the walls of the vessel. This is a great advantage over previous processes which require the temperature of the walls of the vessel to be higher than the contents of the vessel. This creates special advantages with respect to corrosion and permits the use of standard construction materials.
(e) Fifth, because of the use of radiant heat, the vessel can be constructed of steel having an enamel coating.
This is because the temperature level of the walls will not rise above the temperature of the waste sulEuric acid in the vessel.
; 4 2 ~
In the above manner, -the prob]ern of vessel corrosion has been solved. Furtherrnore, the main disadvantaye of hiyh temperature cleaning, nalrlely, the larye mainkenance costs of the apparatus have been avoided. By means of the combina-tion of concentraticn stepsand cleaning steps as in the above-described manner, as well as by the use of especially acid-resistant construction materials such as glass, enameled glass, tantalum, graphite, and polytetrafluoroethylene for the construc-tion of the apparatus one achieves the greatest possible reduction in construction costs and operating expenses.
At the same time, the disadvantages commonly grouped under the term of art "acid problems", have been avoided. In accordance with the present invention, the regeneration of waste sulfuric acid at many locations will be economically attractive under conditions which result in a clean environment.
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for concentrating and cleaning waste sulfuric acid comprising the steps of: I. concentrating waste sulfuric acid to about 94% H2SO4 by heating it in a first ves-sel in one or more stages, the last stage of which is at a pres-sure of 10 to 20 millibars absolute, maintaining a maximum tem-perature of about 170°C, II. transferring the 94% H2SO4 acid to a second vessel which is enamel lined, III. cleaning the 94%
H2SO4 acid in the second vessel under atmospheric or super at-mospheric pressure by electrically heating at a temperature be-tween 270° and 330°C in order to oxidize organic impurities, and IV. recovering the clean sulfuric acid of 94% or greater up to 98% H2SO4.
H2SO4 acid in the second vessel under atmospheric or super at-mospheric pressure by electrically heating at a temperature be-tween 270° and 330°C in order to oxidize organic impurities, and IV. recovering the clean sulfuric acid of 94% or greater up to 98% H2SO4.
2. The process of claim 1, wherein the electric heat-ing of Step III is carried out by the use of an infra-red heat-ing means submerged in the sulfuric acid.
3. The process of claim 2, wherein the infra-red heat-ing means is protected by quartz pipes.
4. A process for concentrating waste sulfuric acid and removing impurities therefrom comprising heating waste sul-furic acid in a recirculation evaporator at normal pressure uti-lizing steam having a pressure of 16 bars and employing a tem-perature of 160°C to effect removal of water and thereby con-centrate the sulfuric acid to about 90% H2SO4, changing the pressure of the recirculating evaporator to about 10-20 milli-bars absolute pressure and maintaining a maximum temperature of about 170°C with heating with saturated steam in order to con-centrate the sulfuric acid to about 94% H2SO4, removing and cool-ing the water vapors being distilled from the acid by directly contacting the vapors with cold water at 0°C, minimizing the H2SO4 content of the water vapors by purification using a spray of weak acid, transferring the 94% H2S04 acid to a second vessel which is enamel lined, heating the 94% H2SO4 acid elec-trically by use of an infra-red heating means protected by quartz pipes and submerged in the acid in the vessel at atmos-pheric or super atmospheric pressure, the heating being at a temperature between 270°C and 330°C in order to oxidize organic impurities, and recovering the clean 94% or greater H2SO4 sul-furic acid.
5. A process of claim 4, wherein the recirculating evaporation is operated with waste steam.
6. A process of claim 4, wherein the water vapors are condensed by supercharging with a steam jet at about 60 Torr.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19792909029 DE2909029C2 (en) | 1979-03-08 | 1979-03-08 | Process for concentrating and purifying sulfuric acid |
| DEP2909029.7 | 1979-03-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1156428A true CA1156428A (en) | 1983-11-08 |
Family
ID=6064796
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000347107A Expired CA1156428A (en) | 1979-03-08 | 1980-03-06 | Process for the concentration and cleaning of sulfuric acid |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0016987B1 (en) |
| JP (1) | JPS55126510A (en) |
| CA (1) | CA1156428A (en) |
| DE (1) | DE2909029C2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4663490A (en) * | 1984-03-16 | 1987-05-05 | Bayer Aktiengesellschaft | Process for the production of dinitrotoluene |
| US4772757A (en) * | 1984-03-16 | 1988-09-20 | Bayer Aktiengesellschaft | Process for the production of nitrobenzene |
| US5228885A (en) * | 1990-09-20 | 1993-07-20 | Metallgesellschaft Aktiengesellschaft | Process of concentrating a dilute sulfuric acid in a three-stage forced-circulation vacuum evaporation plant |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4230099C2 (en) * | 1992-09-09 | 1998-09-24 | Bayer Ag | Process for regenerating used sulfuric acid |
| WO2023025372A1 (en) * | 2021-08-24 | 2023-03-02 | Bertrams Chemieanlagen Ag | Sulfuric acid concentration plant |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE972412C (en) * | 1951-06-01 | 1959-07-16 | Metallgesellschaft Ag | Process for the evaporation of sulfuric acid or similarly behaving solutions |
| US3545519A (en) * | 1968-08-06 | 1970-12-08 | Maruzen Oil Co Ltd | Process and apparatus for the treatment of waste sulfuric acid |
| DE2242055C3 (en) * | 1972-08-26 | 1979-05-31 | Industrie Chemie Thoma Gmbh, 6000 Frankfurt | Process for the concentration and purification of sulfuric acid contaminated by organic substances |
| DE2360706C3 (en) * | 1973-12-06 | 1980-10-16 | Hoechst Ag, 6000 Frankfurt | Process for the regeneration of sulfuric acid |
| DE2706456C3 (en) * | 1977-02-16 | 1981-05-07 | Heraeus Quarzschmelze Gmbh, 6450 Hanau | Sulfuric acid distillation device |
-
1979
- 1979-03-08 DE DE19792909029 patent/DE2909029C2/en not_active Expired
-
1980
- 1980-03-05 EP EP19800101096 patent/EP0016987B1/en not_active Expired
- 1980-03-06 CA CA000347107A patent/CA1156428A/en not_active Expired
- 1980-03-07 JP JP2818180A patent/JPS55126510A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4663490A (en) * | 1984-03-16 | 1987-05-05 | Bayer Aktiengesellschaft | Process for the production of dinitrotoluene |
| US4772757A (en) * | 1984-03-16 | 1988-09-20 | Bayer Aktiengesellschaft | Process for the production of nitrobenzene |
| US5228885A (en) * | 1990-09-20 | 1993-07-20 | Metallgesellschaft Aktiengesellschaft | Process of concentrating a dilute sulfuric acid in a three-stage forced-circulation vacuum evaporation plant |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0016987A1 (en) | 1980-10-15 |
| EP0016987B1 (en) | 1982-07-07 |
| DE2909029A1 (en) | 1980-09-11 |
| JPS55126510A (en) | 1980-09-30 |
| DE2909029C2 (en) | 1990-05-31 |
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