CA2047660A1 - Simultaneous removal of so2 and h2s from exhaust gases - Google Patents
Simultaneous removal of so2 and h2s from exhaust gasesInfo
- Publication number
- CA2047660A1 CA2047660A1 CA002047660A CA2047660A CA2047660A1 CA 2047660 A1 CA2047660 A1 CA 2047660A1 CA 002047660 A CA002047660 A CA 002047660A CA 2047660 A CA2047660 A CA 2047660A CA 2047660 A1 CA2047660 A1 CA 2047660A1
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-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/52—Hydrogen sulfide
- B01D53/523—Mixtures of hydrogen sulfide and sulfur oxides
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Environmental & Geological Engineering (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Treating Waste Gases (AREA)
- Chemical Vapour Deposition (AREA)
- Gas Separation By Absorption (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
Process for a simultaneous removal of SO2 and H2S
from exhaust gases in which the exhaust gases are contacted in a first stage in a countercurrent operation with a first suspension, which contains 60 to 95 g/l ZnSO3, 80 to 90 g/l ZnO, and 0.1 to 1.0 g/l ZnS. 40 to 60% by volume of the suspension collected in the sump of the first stage are recycled and are re-supplied to the first stage at its top.
The exhaust gas which has been depleted of SO2 and H2S is contacted in a second stage in a countercurrent operation with a second suspension, which contains 80 to 150 g/l ZnO, and with a third suspension, which contains 60 to 95 g/l ZnSO3, 80 to 90 g/l ZnO, and 0.1 to 1.0 g/l ZnS 40 to 60% by volume of the suspension which as been collected in the sump of the secnd stage are recycled and are re-supplied as the third suspension to the second stage at its top. The pure gas is withdrawn from the second stage at its top.
Process for a simultaneous removal of SO2 and H2S
from exhaust gases in which the exhaust gases are contacted in a first stage in a countercurrent operation with a first suspension, which contains 60 to 95 g/l ZnSO3, 80 to 90 g/l ZnO, and 0.1 to 1.0 g/l ZnS. 40 to 60% by volume of the suspension collected in the sump of the first stage are recycled and are re-supplied to the first stage at its top.
The exhaust gas which has been depleted of SO2 and H2S is contacted in a second stage in a countercurrent operation with a second suspension, which contains 80 to 150 g/l ZnO, and with a third suspension, which contains 60 to 95 g/l ZnSO3, 80 to 90 g/l ZnO, and 0.1 to 1.0 g/l ZnS 40 to 60% by volume of the suspension which as been collected in the sump of the secnd stage are recycled and are re-supplied as the third suspension to the second stage at its top. The pure gas is withdrawn from the second stage at its top.
Description
7 ~ ~ ~
Metallgesellschaft AG July 25, 1990 Reute~eg 14 ~000 Frankfurt-an-Main 1 Case No. 890069 Simultaneous Removal of S02 and H2S From Exhaust Gases DESCRIPTION
This ~nvention relates to a process for a simul-taneous removal of S02 and H2S from exhaust gases.
When bro~n coal, natural gas or petroleum coke are used as fuels or as raw materi21s for chemical prDcesses, the resulting exhaust gases often contain comblned sulfur.
For instance, exhaust gases which have a relatively high con-centration of S02 or also H2S and a residual content of Dxygen are produced in po~er plants in the generation oF steam,in roasting urnaces for producing sulfuric acid and in rotary kilns for producing titanium dioxide, zlnc sulfide or barium sulfide. For a simultaneous removal of S02 and H2S from the exhaust gases, said ~ollutants are catalytically reacted on adsorption catalysts to form sulfur, whlch is adsorbed on the surface of the catalyst and in a succeeding desarption by means of a hot g3s i9 rerovered as elementary sulfur of high purity. The adsorption catalyst consists, e.g., of alumlna (Ullmanns Enzyklopadie d~r techni-schen Chemie, 4th editlon, volume Z, p~ge 614).
That kno~n process for a simultaneous removalf 52 and H2S from exhaust gases has the disadvantage thst the stoichiometry of the reaction equation 2HzS + S02 -> 3S + 2H20 . - 2 -must substantially be maintained in the exhaust gas because a relatively high structural expenditure will otherwise oe required to keEo the pollutants cG2 and H2S in the pure gas below the limits specified in TA Luft (German technical instructions on air Pollution control) of February 27, 19~6.
For this reason it is an object af the invention to provide for a simultaneous removal of S02 and H25 fro~ ex-haust gases a process which can be carried out at low cost and by which $he contents of SOz and H~S in the pure gas can be kept relatively far below the limits specified in TA Luft of February 27, 19B6.
The object underlying the invention is accompli~
shed in that the exhasst ga~, which contains S02 and H2S is contacted in a first stage in a countercurrent operation with a first suspension, which contains 60 to 95 g/l ZnSG3, BO to 90 g/l ZnO, and o.1 to 1.0 g/l ZnS, the suspension collected in the sump of the first stage contains 20 to 35 g/l ZnS, 130 to 145 g/l ZnSG4, and 0.1 to B o/l ZnS03, 40 to 60% oy volume of the latter suspension are withdrawn from the sump of the first stage and continuously re-supplied to the first atage st its top, the exhaust gas which has been depleted of SOz and H2S in the first stage i9 withdrawn from the first stage at its top and is contacted in a secùnd 3tage in a countercurrent operation with a second suspension, which contains BO to 150 g/l ZnO, and with a third suspension, which contains 60 to ~ J;~
95 g~l ZnS03, ~0 to 90 g~l ZnG, and 0.1 to 1.0 g~l ZnS, the third suspension cons~sts of ~D ~o 6D90 by volume o~ the 9US-Dension which has been collected in the sump of the second stage and which contains 60 to 9S o/l ZnS03, 80 tn 90 g~l ZnO and 0.1 to 1.0 g~l ZnS and is withdrawn from the sump of the second stage and is continuously re-gupplied to the second stage at the top thereof, the first suspenginn consists of 60 to 40% by volume of the suspension collected in the sump of the second stage ~nd is supplied tD the first stage at its tDp, and the pure gas is ~ithdrawo from the top of the second staoe.
The first and second stages are constituted by packed columns. The suspensions recirculated throuo,h the first and second stages are equeous suspensions hsving pH values of 2.0 to 5.5. It has surprisingly been found that the pollutants HzS and S020 will be almost entirely removed from exhaust gases oy the process in accordance with the invention even if they are contained in the exhaust gases at a fluctuating concentra-tion r~tio. Owing to the relatively high average trickling flo~
rate of ZO to 60 m~Jm2 h through the ~irst and second stages the process in ~ccordance with the invention permits a sub-stantially complete reaction of the reactant3 so that the pollu-tants H2S and SOz are removed from the exhaust gases at lnw C09t.
A preferred feature of the invention re~ideo ln that the fir~t stage and/or the second stage is constituted by an ordered scrubbing column. The term l'ordered scrubbinq column"
descrlbes pscked columns in which the~packing elements are 7 ~ ~ ~
arrano,ed in a Lertain arder in ~ependence on their oeometrical configuration an~ ~ay com~rise 02ckino consistina of pre-fabricated ordere~ ele~ents. If the first staoe and/ar the second staoe is constituted oy an ordered scrubbing column, the pressure droo in each staoe ~ill desirably oe reduced.
According to a further preferred feature of the invention the second staoe is arran~ed on top of the first stage within a separating column. This will afford the advan-tage that piping bet~een the first and secnnd sta~ ~ill not oe required so that the costs of the processing will further be reduced.
~ ccording to a further preferred feature of the invention a part of the suspension collected in the sump of the First stage is withdrawn fro~ the first stage and, for an adjust~ent to a oH value of 0.5 to 1.G, Hz504 in a concentra-tion of 4B to 9?~ is added to the part of the suspension which hes thu~ oeen ~ithdrawn. This will result in a ~ixture of S02 and H2C in accordance ~ith the follo~ino reaction equations:
Zn~C3 + HzSG4 ~ ZnS04 I H20 + S02 ZnS + H2S04 ---~ ZnS04 + H2S
The mixture of S02 and HzS may be processed fur-ther in a factory for producing sulfuric acid in a process in whichH2S is initially oxidized ~ith air to form S02.
~ ccnrding to a further preferred feature of the invention a part of the suspension collected in the sump of the first stage is withdra~n from the first stage and, for an ' "' .
~7~
adjustment to a pH value of 1.3 tc 1 8, Olz is added to the part of the suspension ~hich has thus been withdra~n. This will result in thE followino che~ical reactions:
ZnSO3 + Cl2 + H2C ~ ZnS 4 ZnS + Clz ---~ ZnCl2 + S
The sulfur formed by the chlorination i5 subsequently removed ~rom the solution by filtration.
The invention ~ill no~ be explained mwre in detail with reference to the single f1nure oF the drawing.
The drawino shows schematically a column, which comprises the first and secono staoes.
The first and second staoes 1 and Z are arranged one over the other in the illustrated column 11. The exhaust gas 4 ~hich contains SO2 and H2S is horizontally fed intu the first stage 1 and is cDntacted therein in a countercurrent operation with a suspension 5a, which contains ZnS03, ZnO, and ZnS. This results in the ~ollowino chemical reactions, for which the required oxygen is taken from the exhaust gas:
H2S + ZnC ~--~ ZnS + H20 ZnO + SOz ---~ ZnS03 ZnSD3 + 1JZ 2 ~~~~ ZnSO4 A suspension e, ~hich cDntain~ ZnS, ZnS04 and ZnS03, is collected in the sump 1b of the first 3tag~ 1 and is withdrawn from the column 11, specifically from the sump lb of the first stage 1. A part ~b of the suspension B is supolied by a pump 13 to the first stage 1 at its top 1a and is re-con-..
:. :
~7~
tactPd in a countercurrent operation with the exhaust gas 4,which contains S02 and H2~ The other part 8a of the 5US-oension c is w1th~rawn frnm the system through the three-way olug valve 12 and is processed further by an addition of H2S04 or ~lz. The exhaust gas 9 which has been deDleted of S2 and HzS is withdrawn from the first staoe 1 at its too la sno is supplied to the second staoe 2 a~ its sump 2b. In the second stage 2 the exhaust gas 9 which has been depleted of SG2 and HzS is contacted in a countercurrent operation with a second suspension _, which contains Zn5, and with a third sus-Dension 5b, which contains ZnO, ZnS03, and ZnS. The third sus-pension 5b is cons~ituted by a 02rt of the suspension 5 which has been collected in the sump Zb of the second sta~e 2. ~e-fore the second suspension ~ and the third suspension 5b enter the second staae 2, the suspensions 6 and 5b are mixed t a mixlng ~unction 7. In the second stage ? the pollutants H2S an~
S03 react with the 2nO accordino to the followino reactinn equations:
H~S I ZnO ~ Zn~ + H70 SC2 + ZnO ---~ ZnSC3 The other part 5a of the suspension 5 is with-drawn through the three-way plug valve 3 and i5 supplied to the first stage 1 at its top 1a. The pure gas lD i9 removed from the second stage at its top 2a.
The invention will now be described more in de-tail with reference to an example.
~, ~
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Example 700 sm3/h (sm3 - sta~dard cubic meter) of zn exhaust gas 4, which on 8 dry basis contains 9~0 mg/sm3 sc2 and 300 mg/sm3 H2S, are supplie~ to a first stage 1, which is constituted by an ordered scrubbina column, and in a caunter-current operation are canta~ted with 5 ~'/h o~ a ~irst ~uspen-sion 5a, which contains 6Z.7 g/l ZnS~3, ~5.5 g/l ZnO, and 0.3 g/l ZnS. In the first stage 1 the pH value is 2.0 and the trickling flow rate is 40 m3/m2 h. The suspension a collecte~
in the sump of the first stage 1 cDntains 34.3 g/l ZnS, 0.9 9/
ZnS03, and 135.9 g/l ZnS04O 60~ by volume of the latter 8US-pension are withdr~wn and are recycled to the top 1a of the ~irst stage 1 and are contacted therein in a countercurrent operation wlth the exhaust gas. 40~ by volume o~ the suspension 8 collected in the sump lb of the first stage 1 are withdrawn from the system and processed by an addition of HzS04. The exhaust gas 9 which has been depleted of S02 and H2S and on a dry basis contains 850 mg/sm3 SL2 and Z00 ~g/sm3 H2S i9 supplied to the sump 2b of the second staoe 2. That second stage 2 is also constituted by an ordered scrubbing column. In the second stage the exhsust gsg 9, which has been depleted of S02 and H2S, is contacted in a countercurrent operation with 5 m3/h o~
a suspension 6, which contains 117 g/l ZnO~ and with 4.8 m3/h of a third suspension 5b, which contains 62.7 g/l ZnSO3, 85.5 9/1 ZnO, and 0.3 g/l ZnS and which is taken from the suspenslon 5, which is collected in the sump 2b of the second stage 2. The average ;, .: .,, ' :.
pH value in the second stage is between 5.0 and 5.5. The trick-ling flnw rate in the second staoge Z is 40 m3/mZ h. The re-maining 5 m3/h of the suspension 5 collected in the sump 2b o~ the second staqe 2 are withdrawn from the gecond staae 2 and as a first susDension are suPPlied to the first stape 1 at its top 1a. The pure gas 10 is withdrawn from the top 2a of the second stage 2 and on a dry basis contains 70 mg/sm3 S07 and 1 mg/sm3 H2S.
It is apparent that the process in accordance with the invention permits the contents of H2S and S02 to be kept relatively below the limits (5 mg/sm3 HzS and 500 mg/sm3 Saz) specified in TA Luft.
~' ., !
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Metallgesellschaft AG July 25, 1990 Reute~eg 14 ~000 Frankfurt-an-Main 1 Case No. 890069 Simultaneous Removal of S02 and H2S From Exhaust Gases DESCRIPTION
This ~nvention relates to a process for a simul-taneous removal of S02 and H2S from exhaust gases.
When bro~n coal, natural gas or petroleum coke are used as fuels or as raw materi21s for chemical prDcesses, the resulting exhaust gases often contain comblned sulfur.
For instance, exhaust gases which have a relatively high con-centration of S02 or also H2S and a residual content of Dxygen are produced in po~er plants in the generation oF steam,in roasting urnaces for producing sulfuric acid and in rotary kilns for producing titanium dioxide, zlnc sulfide or barium sulfide. For a simultaneous removal of S02 and H2S from the exhaust gases, said ~ollutants are catalytically reacted on adsorption catalysts to form sulfur, whlch is adsorbed on the surface of the catalyst and in a succeeding desarption by means of a hot g3s i9 rerovered as elementary sulfur of high purity. The adsorption catalyst consists, e.g., of alumlna (Ullmanns Enzyklopadie d~r techni-schen Chemie, 4th editlon, volume Z, p~ge 614).
That kno~n process for a simultaneous removalf 52 and H2S from exhaust gases has the disadvantage thst the stoichiometry of the reaction equation 2HzS + S02 -> 3S + 2H20 . - 2 -must substantially be maintained in the exhaust gas because a relatively high structural expenditure will otherwise oe required to keEo the pollutants cG2 and H2S in the pure gas below the limits specified in TA Luft (German technical instructions on air Pollution control) of February 27, 19~6.
For this reason it is an object af the invention to provide for a simultaneous removal of S02 and H25 fro~ ex-haust gases a process which can be carried out at low cost and by which $he contents of SOz and H~S in the pure gas can be kept relatively far below the limits specified in TA Luft of February 27, 19B6.
The object underlying the invention is accompli~
shed in that the exhasst ga~, which contains S02 and H2S is contacted in a first stage in a countercurrent operation with a first suspension, which contains 60 to 95 g/l ZnSG3, BO to 90 g/l ZnO, and o.1 to 1.0 g/l ZnS, the suspension collected in the sump of the first stage contains 20 to 35 g/l ZnS, 130 to 145 g/l ZnSG4, and 0.1 to B o/l ZnS03, 40 to 60% oy volume of the latter suspension are withdrawn from the sump of the first stage and continuously re-supplied to the first atage st its top, the exhaust gas which has been depleted of SOz and H2S in the first stage i9 withdrawn from the first stage at its top and is contacted in a secùnd 3tage in a countercurrent operation with a second suspension, which contains BO to 150 g/l ZnO, and with a third suspension, which contains 60 to ~ J;~
95 g~l ZnS03, ~0 to 90 g~l ZnG, and 0.1 to 1.0 g~l ZnS, the third suspension cons~sts of ~D ~o 6D90 by volume o~ the 9US-Dension which has been collected in the sump of the second stage and which contains 60 to 9S o/l ZnS03, 80 tn 90 g~l ZnO and 0.1 to 1.0 g~l ZnS and is withdrawn from the sump of the second stage and is continuously re-gupplied to the second stage at the top thereof, the first suspenginn consists of 60 to 40% by volume of the suspension collected in the sump of the second stage ~nd is supplied tD the first stage at its tDp, and the pure gas is ~ithdrawo from the top of the second staoe.
The first and second stages are constituted by packed columns. The suspensions recirculated throuo,h the first and second stages are equeous suspensions hsving pH values of 2.0 to 5.5. It has surprisingly been found that the pollutants HzS and S020 will be almost entirely removed from exhaust gases oy the process in accordance with the invention even if they are contained in the exhaust gases at a fluctuating concentra-tion r~tio. Owing to the relatively high average trickling flo~
rate of ZO to 60 m~Jm2 h through the ~irst and second stages the process in ~ccordance with the invention permits a sub-stantially complete reaction of the reactant3 so that the pollu-tants H2S and SOz are removed from the exhaust gases at lnw C09t.
A preferred feature of the invention re~ideo ln that the fir~t stage and/or the second stage is constituted by an ordered scrubbing column. The term l'ordered scrubbinq column"
descrlbes pscked columns in which the~packing elements are 7 ~ ~ ~
arrano,ed in a Lertain arder in ~ependence on their oeometrical configuration an~ ~ay com~rise 02ckino consistina of pre-fabricated ordere~ ele~ents. If the first staoe and/ar the second staoe is constituted oy an ordered scrubbing column, the pressure droo in each staoe ~ill desirably oe reduced.
According to a further preferred feature of the invention the second staoe is arran~ed on top of the first stage within a separating column. This will afford the advan-tage that piping bet~een the first and secnnd sta~ ~ill not oe required so that the costs of the processing will further be reduced.
~ ccording to a further preferred feature of the invention a part of the suspension collected in the sump of the First stage is withdrawn fro~ the first stage and, for an adjust~ent to a oH value of 0.5 to 1.G, Hz504 in a concentra-tion of 4B to 9?~ is added to the part of the suspension which hes thu~ oeen ~ithdrawn. This will result in a ~ixture of S02 and H2C in accordance ~ith the follo~ino reaction equations:
Zn~C3 + HzSG4 ~ ZnS04 I H20 + S02 ZnS + H2S04 ---~ ZnS04 + H2S
The mixture of S02 and HzS may be processed fur-ther in a factory for producing sulfuric acid in a process in whichH2S is initially oxidized ~ith air to form S02.
~ ccnrding to a further preferred feature of the invention a part of the suspension collected in the sump of the first stage is withdra~n from the first stage and, for an ' "' .
~7~
adjustment to a pH value of 1.3 tc 1 8, Olz is added to the part of the suspension ~hich has thus been withdra~n. This will result in thE followino che~ical reactions:
ZnSO3 + Cl2 + H2C ~ ZnS 4 ZnS + Clz ---~ ZnCl2 + S
The sulfur formed by the chlorination i5 subsequently removed ~rom the solution by filtration.
The invention ~ill no~ be explained mwre in detail with reference to the single f1nure oF the drawing.
The drawino shows schematically a column, which comprises the first and secono staoes.
The first and second staoes 1 and Z are arranged one over the other in the illustrated column 11. The exhaust gas 4 ~hich contains SO2 and H2S is horizontally fed intu the first stage 1 and is cDntacted therein in a countercurrent operation with a suspension 5a, which contains ZnS03, ZnO, and ZnS. This results in the ~ollowino chemical reactions, for which the required oxygen is taken from the exhaust gas:
H2S + ZnC ~--~ ZnS + H20 ZnO + SOz ---~ ZnS03 ZnSD3 + 1JZ 2 ~~~~ ZnSO4 A suspension e, ~hich cDntain~ ZnS, ZnS04 and ZnS03, is collected in the sump 1b of the first 3tag~ 1 and is withdrawn from the column 11, specifically from the sump lb of the first stage 1. A part ~b of the suspension B is supolied by a pump 13 to the first stage 1 at its top 1a and is re-con-..
:. :
~7~
tactPd in a countercurrent operation with the exhaust gas 4,which contains S02 and H2~ The other part 8a of the 5US-oension c is w1th~rawn frnm the system through the three-way olug valve 12 and is processed further by an addition of H2S04 or ~lz. The exhaust gas 9 which has been deDleted of S2 and HzS is withdrawn from the first staoe 1 at its too la sno is supplied to the second staoe 2 a~ its sump 2b. In the second stage 2 the exhaust gas 9 which has been depleted of SG2 and HzS is contacted in a countercurrent operation with a second suspension _, which contains Zn5, and with a third sus-Dension 5b, which contains ZnO, ZnS03, and ZnS. The third sus-pension 5b is cons~ituted by a 02rt of the suspension 5 which has been collected in the sump Zb of the second sta~e 2. ~e-fore the second suspension ~ and the third suspension 5b enter the second staae 2, the suspensions 6 and 5b are mixed t a mixlng ~unction 7. In the second stage ? the pollutants H2S an~
S03 react with the 2nO accordino to the followino reactinn equations:
H~S I ZnO ~ Zn~ + H70 SC2 + ZnO ---~ ZnSC3 The other part 5a of the suspension 5 is with-drawn through the three-way plug valve 3 and i5 supplied to the first stage 1 at its top 1a. The pure gas lD i9 removed from the second stage at its top 2a.
The invention will now be described more in de-tail with reference to an example.
~, ~
2~7~
Example 700 sm3/h (sm3 - sta~dard cubic meter) of zn exhaust gas 4, which on 8 dry basis contains 9~0 mg/sm3 sc2 and 300 mg/sm3 H2S, are supplie~ to a first stage 1, which is constituted by an ordered scrubbina column, and in a caunter-current operation are canta~ted with 5 ~'/h o~ a ~irst ~uspen-sion 5a, which contains 6Z.7 g/l ZnS~3, ~5.5 g/l ZnO, and 0.3 g/l ZnS. In the first stage 1 the pH value is 2.0 and the trickling flow rate is 40 m3/m2 h. The suspension a collecte~
in the sump of the first stage 1 cDntains 34.3 g/l ZnS, 0.9 9/
ZnS03, and 135.9 g/l ZnS04O 60~ by volume of the latter 8US-pension are withdr~wn and are recycled to the top 1a of the ~irst stage 1 and are contacted therein in a countercurrent operation wlth the exhaust gas. 40~ by volume o~ the suspension 8 collected in the sump lb of the first stage 1 are withdrawn from the system and processed by an addition of HzS04. The exhaust gas 9 which has been depleted of S02 and H2S and on a dry basis contains 850 mg/sm3 SL2 and Z00 ~g/sm3 H2S i9 supplied to the sump 2b of the second staoe 2. That second stage 2 is also constituted by an ordered scrubbing column. In the second stage the exhsust gsg 9, which has been depleted of S02 and H2S, is contacted in a countercurrent operation with 5 m3/h o~
a suspension 6, which contains 117 g/l ZnO~ and with 4.8 m3/h of a third suspension 5b, which contains 62.7 g/l ZnSO3, 85.5 9/1 ZnO, and 0.3 g/l ZnS and which is taken from the suspenslon 5, which is collected in the sump 2b of the second stage 2. The average ;, .: .,, ' :.
pH value in the second stage is between 5.0 and 5.5. The trick-ling flnw rate in the second staoge Z is 40 m3/mZ h. The re-maining 5 m3/h of the suspension 5 collected in the sump 2b o~ the second staqe 2 are withdrawn from the gecond staae 2 and as a first susDension are suPPlied to the first stape 1 at its top 1a. The pure gas 10 is withdrawn from the top 2a of the second stage 2 and on a dry basis contains 70 mg/sm3 S07 and 1 mg/sm3 H2S.
It is apparent that the process in accordance with the invention permits the contents of H2S and S02 to be kept relatively below the limits (5 mg/sm3 HzS and 500 mg/sm3 Saz) specified in TA Luft.
~' ., !
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' , ." "'` - '
Claims (9)
1. A process for a simultaneous removal of SO2 and H2S from exhaust gases, characterized in that the exhaust gas (4), which contains SO2 and H2S, is contacted in a first stage (1) in a countercurrent operation with a first suspen-sion (5a), which contains 60 to 95 g/l ZnSO3, 80 to 90 g/l ZnO, and 0.1 to 1.0 g/l ZnS, the suspension collected in the sump (lb) of the first stage (1) contains 20 to 35 g/l ZnS, 130 to 145 g/l ZnSO4, and 0.1 to 8 g/l ZnSO3, 40 to 60% by volume of the latter suspension are withdrawn from the sump (1b) of the first stage (1) and continuously re-supplied to the first stage (1) at its top (1a), the exhaust gas (9) which has been depleted of SO2 and H2S in the first stage (1) is withdrawn from the first stage (1) at its top (1a) and is contacted in a second stage (2) in a countercurrent operation with a second suspension (6), which contains 80 to 150 g/l ZnO, and with a third suspension (5b), which contains 60 to 95 g/l ZnSO3, 80 to 90 g/l ZnO, and 0.1 to 1.0 g/l ZnS, the third suspension (5b) consists of 40 to 60% by volume of the sus-pension (5) which has been collected in the sump (2b) of the second stage (2) and which contains 60 to 95 g/l ZnSO3, 80 to 90 g/l ZnO and 0.1 to 1.0 g/l ZnS and is withdrewn from the sump (2b) of the second stage (2) and is continuously re-sup-plied to the second stage (2) at the top (2a) thereof, the first suspension (5a) consists of 60 to 40% by volume of the suspension (5) collected in the sump (2b) of the second stage (2) and is supplied to the first stage (1) at its top (1a), and the pure gas (10) is withdrawn from the top (2a) of the second stage (2).
2. A process according to claim 1, characterized in that the first stage or the second stage is constituted by an ordered scrubbing column.
3. A process according to claim 1, characterized in that the second stage is arranged on top of the first stage within a separating column.
4. A process according to claim 1, 2 or 3, characterized in that a part of the suspension collected in the sump of the first stage is withdrawn from the first stage and for an adjustment to a pH value of 0.6 to 1.0, H2SO4 in a concentration of 48 to 97% is added to the part of the suspension which has thus been withdrawn.
5. A process according to claim 1, 2 or 3, characterized in that a part of the suspension collected in the sump of the first stage is withdrawn from the first stage and, for an adjustment to a pH value of 1.3 to 1.8 C12 is added to the part of the suspension which has thus been withdrawn.
6. A process according to claim 2, characterized in that the second stage is arranged on top of the first stage within a separating column.
7. A process according to claim 6, characterized in that a part of the suspension collected in the sump of the first stage is withdrawn from the first stage and for an adjustment to a pH value of 0.6 to 1.0, H2SO4 in a concentration of 48 to 97% is added to the part of the suspension which as thus been withdrawn.
8. A process according to claim 1, 6 or 7, characterized in that a part of the suspension collected in the sump of the first stage is withdrawn from the first stage and, for an adjustment to a pH value of 1.3 to 1.8 Cl2 is added to the part of the suspension which has thus been withdrawn.
9. A process according to claim 1, characterized in that the first stage and the second stage are constituted by an ordered scrubbing column.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4023926A DE4023926A1 (en) | 1990-07-27 | 1990-07-27 | Simultaneous removal of sulphur di:oxide and hydrogen sulphide - from waste gas by two=stage countercurrent contact with suspension contg. zinc oxide and prods. |
| DEP4023926.8 | 1990-07-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2047660A1 true CA2047660A1 (en) | 1992-01-28 |
Family
ID=6411161
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002047660A Abandoned CA2047660A1 (en) | 1990-07-27 | 1991-07-23 | Simultaneous removal of so2 and h2s from exhaust gases |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0469659B1 (en) |
| AT (1) | ATE106769T1 (en) |
| CA (1) | CA2047660A1 (en) |
| DE (2) | DE4023926A1 (en) |
| ES (1) | ES2055519T3 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1977570B1 (en) | 2006-01-11 | 2014-11-26 | Qualcomm Incorporated | Establishing communications between devices supporting different communication protocols |
| CN102008886B (en) * | 2010-11-22 | 2012-07-18 | 浙江双屿实业有限公司 | Zinc oxide wet turbulent washing flue gas desulfurization device and process |
| CN102716657A (en) * | 2012-06-13 | 2012-10-10 | 河南豫光锌业有限公司 | Zinc oxide desulfurization method applicable to zinc smelting system |
| CN106731632A (en) * | 2016-12-30 | 2017-05-31 | 云南雄冶科技有限公司 | The device and its technique of a kind of zinc oxide removing sulfur dioxide in flue gas |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4276271A (en) * | 1979-02-05 | 1981-06-30 | Combustion Engineering, Inc. | Process for the removal of hydrogen sulfide from gas mixtures |
| US4374105A (en) * | 1979-12-11 | 1983-02-15 | Institute Of Gas Technology | Purification of fuel gases |
| DE3544937A1 (en) * | 1985-12-19 | 1987-06-25 | Kali Chemie Ag | DESULFURATION PROCESS |
| GB8610196D0 (en) * | 1986-04-25 | 1986-05-29 | Ici Plc | Sulphur compounds removal |
| US4842843A (en) * | 1987-12-17 | 1989-06-27 | Amoco Corporation | Removal of water vapor diluent after regeneration of metal oxide absorbent to reduce recycle stream |
-
1990
- 1990-07-27 DE DE4023926A patent/DE4023926A1/en active Granted
-
1991
- 1991-07-05 ES ES91201757T patent/ES2055519T3/en not_active Expired - Lifetime
- 1991-07-05 AT AT91201757T patent/ATE106769T1/en not_active IP Right Cessation
- 1991-07-05 EP EP91201757A patent/EP0469659B1/en not_active Expired - Lifetime
- 1991-07-05 DE DE59101835T patent/DE59101835D1/en not_active Expired - Fee Related
- 1991-07-23 CA CA002047660A patent/CA2047660A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| ATE106769T1 (en) | 1994-06-15 |
| EP0469659B1 (en) | 1994-06-08 |
| EP0469659A1 (en) | 1992-02-05 |
| ES2055519T3 (en) | 1994-08-16 |
| DE4023926C2 (en) | 1993-06-03 |
| DE4023926A1 (en) | 1992-01-30 |
| DE59101835D1 (en) | 1994-07-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |