CA2024547A1 - Process and apparatus for concentrating a liquid which contains sulfuric acid and water - Google Patents
Process and apparatus for concentrating a liquid which contains sulfuric acid and waterInfo
- Publication number
- CA2024547A1 CA2024547A1 CA002024547A CA2024547A CA2024547A1 CA 2024547 A1 CA2024547 A1 CA 2024547A1 CA 002024547 A CA002024547 A CA 002024547A CA 2024547 A CA2024547 A CA 2024547A CA 2024547 A1 CA2024547 A1 CA 2024547A1
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- Canada
- Prior art keywords
- liquid
- processing stage
- zone
- evaporating
- heated
- 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.)
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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
- C01B17/88—Concentration of sulfuric acid
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D1/00—Evaporating
- B01D1/26—Multiple-effect evaporating
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G23/00—Compounds of titanium
- C01G23/04—Oxides; Hydroxides
- C01G23/047—Titanium dioxide
- C01G23/053—Producing by wet processes, e.g. hydrolysing titanium salts
- C01G23/0532—Producing by wet processes, e.g. hydrolysing titanium salts by hydrolysing sulfate-containing salts
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
- Heat Treatment Of Water, Waste Water Or Sewage (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
ABSTRACT
Two heated processing stages and a flashing stage for obtaining the final concentration are used to concentrate a salt-containing dilute sul-furic acid. The first processing stage consists of evaporating means which comprise a circuit for ciru-lating a liquid, an indirect heat exchanger and an evaporating vessel. The second processing stage con-sists of one or two of such evaporating means. The li-quid to be processed is first fed to the first heated processing stage, in which the highest temperatures are between 50 and 70 °C. The highest temperatures in the second processing stage are between 130 to 160 °C. The second processing steam is heated with live steam and the first processing stage with vapors from the second stage. The liquid which is withdrawn from the flashing zone has an H2SO4 concentration from 60 to 80 % by weight, calculated without solids.
Two heated processing stages and a flashing stage for obtaining the final concentration are used to concentrate a salt-containing dilute sul-furic acid. The first processing stage consists of evaporating means which comprise a circuit for ciru-lating a liquid, an indirect heat exchanger and an evaporating vessel. The second processing stage con-sists of one or two of such evaporating means. The li-quid to be processed is first fed to the first heated processing stage, in which the highest temperatures are between 50 and 70 °C. The highest temperatures in the second processing stage are between 130 to 160 °C. The second processing steam is heated with live steam and the first processing stage with vapors from the second stage. The liquid which is withdrawn from the flashing zone has an H2SO4 concentration from 60 to 80 % by weight, calculated without solids.
Description
~ ~ 740~
I.- ~etall~esellschaft AG ~c~o~ 27, 1989 ~euter~e~ 14 6000 ~rankfurt-on-~ain 1 Case No. 890124 Process and Apparatu~ for Conceutrating a Liquid ~hich Contains Sulfuric Acid a~d Water DESC~IPTI0~
Thi~ invention relates to a process of concentrating a liquid ~hich contaiDs sulfuric acid and ~ater and ln ~hich the concentration of ~2S04, calcu-lated ~ithout solids, i8 aboub 15 to 30 % by ~eight, aDd an apparatus rOr carrying out that process.
ID that procoss lt is i~portant to inl-mizo tbo de~aDd ror livo stoa~, to avoid a roruation Or di~turbing crusts ror the longest po~lblo ti~o~
a~d to achlevo hl~h throughput rate~. In ordor to a¢r co~plish that ob~oct it iJ propo~od 1D accordan¢o ~lth the iD~-ntioD that tho llguld i~ ¢irculatod i~ a rir~t hoatod ~roco~ing ~tage at highe~t to porature~ o~ 50 to 70 C through a rirst hest oxchange zooo, ~hich is lndirectl~ heated ~ith ~ater ~apor, and through a ~irst ovaporating zone, vapors and a liquld strea~ ~hich ' : '., , . .
---`` 202~7 co~tains sulfuric acid, water and dissolved salts and has an H2S04 content of about 25 to 40 % by ~ei~ht, calculated ~ithout solids, are separatel~ ~ithdraun from the first evaporating zone aDd fed to a second heated pro-cessing stage, the liq~id is circulated in the ~econd heated processing stage at highest temperatures of 130 to 160 C and under a ~ressure which is higher than in the first proces~ing ~tage in at lea~t one circuit through at least one heat exchange zone ~hich is heated with live steam, and through at least one ~aporating zone, the vapors from the evaporating zone or zones a~e fed to the first heat exdEnge zone as a heating fluid, partly concentrated liquid ha~ing an H2S04 content Or 55 to 70 %
b~ weight, calculated ~ithout solids, is ~ithdrawn from a~ evaporating zone of the second proce~sing stage and i~
red to a fla~hing zone, iD ~hich the liquid i9 flashed wlth a reduction of the temperatw e o~ the liquid to 8 valuo ~hich is lower by 20 to 70 C than the highest tempo-raturo ln the ~econd processing ~tage and concentratod llquld having an ~ ~ 04 conte~t Or 60 to 80 % by ~oi~ht~
¢alculatod ~ithout ~olid~ ithdra~n ~ro~ the rl~hing zono. In the calculation of the H ~ 04 concentration ~ith-out ~olid~ dlssol~et salt~ are al~o Dot takeD into account.
also ~hat proce~s is/particularly desirable ; for a processlng Or dllute sulfuric acid, ~hich beco~es ., ., , ~ 2~2~7 available in the production of TiO2 pigments. Such dilute sulfuric acid contains 5 to 20 % by weight dis-solved salts, particularly ~sulfates of iron, manganese, aluminum and calcium.
It i9 imp~tant fo~khe proce s that the final concentration after the second heated processing stage i~ achieved only by flashiDg ~ithout a use of heating sur~aces. As a result, the risk of in-crustatioD, which is particularly high owing to the high concentration of H25~4 and ~alts, is minimized. A thermal heating is effected only in the first and second proces-sing ~tages, in ~hich the acid flo~s countercurrently to the vapors. ID the first processing stage the concentra-, .
ting treatment iY controlled to keep the H2S04 contentat or belo~ 4~% by weight, calculated without solids, because a higher coDteDt night result in a higher tenden-cy to~ard a precip~tation and ~ormation o~ crusta.
ID ac¢ordance with a further feature of the invention the second processing ~tage compri~es t~o ll~uld circuit~, each o~ ~hich include~ a heat es-change ZOD8, ~hich i9 heated ~ith llve ~team, and an e~aporating zoDe~ and the t~o e~aporating zones are operated under the ~ame pres~ure. In that ca~e the t~o partial stages may be designed to permit of a change-over of their connections or can lndividuall~ be shut do~n. A~ a result~ any crusts formed in the partial stage ~hich contains the more highly concentrated liquid can be : . . - .
i ' .
.
., ~ .
202~7 eliminated at least in part or a further growth of such cru~t~ can be prevented if a change-over is efrected so that said partial stage is now supplied ~ith leas highlg conce~trated liquid. In this manner the time for which the pla~t can be operated before it must be shut down and the heating surface-s must be cleaned can co~siderably be prolonged.
It is not necessar~ in the proce~s to effect a preconcentrating, at a higber or lower ex-pense, of the liquid which is to be supplied to the first processing s~age. But it ma~ be desirable to preheat such liquid by meaDs o~ ~aste heat, e.g., b~ meaDs of condensate obtained from vapors and/or live steam.
The apparatus for carr~ing out the process described first hereinbefore comprises a first heated processin6 stage, ~hich is provided ~ith a ~uppl~ lino ~or the llquid to be concentrated, a ~irst evaporating vess~l, a ~ir~t indirect heat exchaDger~ a ~irst circulatiDg liDe, a pump lncorporated iD said rirst circulating llDe, and a liquid discharge line~
~hich lead~ to a Jecond heated proce~sing ~tage~ ~hich comprisos at leaJt one o~aporatlng ~s~Jol aDd at loa~t one lndlrect heat exchaDger pro~ided ~ith me aD~ rOr ~uppl~ing llve ~team. The ~econd ~tage also compri~eJ
9 ~apor line lea~ng from the e~aporatin~ ve~sel to the indirect heat exchanger Or the first processing stage and a liquid linc leading from the second processin~
:
I.- ~etall~esellschaft AG ~c~o~ 27, 1989 ~euter~e~ 14 6000 ~rankfurt-on-~ain 1 Case No. 890124 Process and Apparatu~ for Conceutrating a Liquid ~hich Contains Sulfuric Acid a~d Water DESC~IPTI0~
Thi~ invention relates to a process of concentrating a liquid ~hich contaiDs sulfuric acid and ~ater and ln ~hich the concentration of ~2S04, calcu-lated ~ithout solids, i8 aboub 15 to 30 % by ~eight, aDd an apparatus rOr carrying out that process.
ID that procoss lt is i~portant to inl-mizo tbo de~aDd ror livo stoa~, to avoid a roruation Or di~turbing crusts ror the longest po~lblo ti~o~
a~d to achlevo hl~h throughput rate~. In ordor to a¢r co~plish that ob~oct it iJ propo~od 1D accordan¢o ~lth the iD~-ntioD that tho llguld i~ ¢irculatod i~ a rir~t hoatod ~roco~ing ~tage at highe~t to porature~ o~ 50 to 70 C through a rirst hest oxchange zooo, ~hich is lndirectl~ heated ~ith ~ater ~apor, and through a ~irst ovaporating zone, vapors and a liquld strea~ ~hich ' : '., , . .
---`` 202~7 co~tains sulfuric acid, water and dissolved salts and has an H2S04 content of about 25 to 40 % by ~ei~ht, calculated ~ithout solids, are separatel~ ~ithdraun from the first evaporating zone aDd fed to a second heated pro-cessing stage, the liq~id is circulated in the ~econd heated processing stage at highest temperatures of 130 to 160 C and under a ~ressure which is higher than in the first proces~ing ~tage in at lea~t one circuit through at least one heat exchange zone ~hich is heated with live steam, and through at least one ~aporating zone, the vapors from the evaporating zone or zones a~e fed to the first heat exdEnge zone as a heating fluid, partly concentrated liquid ha~ing an H2S04 content Or 55 to 70 %
b~ weight, calculated ~ithout solids, is ~ithdrawn from a~ evaporating zone of the second proce~sing stage and i~
red to a fla~hing zone, iD ~hich the liquid i9 flashed wlth a reduction of the temperatw e o~ the liquid to 8 valuo ~hich is lower by 20 to 70 C than the highest tempo-raturo ln the ~econd processing ~tage and concentratod llquld having an ~ ~ 04 conte~t Or 60 to 80 % by ~oi~ht~
¢alculatod ~ithout ~olid~ ithdra~n ~ro~ the rl~hing zono. In the calculation of the H ~ 04 concentration ~ith-out ~olid~ dlssol~et salt~ are al~o Dot takeD into account.
also ~hat proce~s is/particularly desirable ; for a processlng Or dllute sulfuric acid, ~hich beco~es ., ., , ~ 2~2~7 available in the production of TiO2 pigments. Such dilute sulfuric acid contains 5 to 20 % by weight dis-solved salts, particularly ~sulfates of iron, manganese, aluminum and calcium.
It i9 imp~tant fo~khe proce s that the final concentration after the second heated processing stage i~ achieved only by flashiDg ~ithout a use of heating sur~aces. As a result, the risk of in-crustatioD, which is particularly high owing to the high concentration of H25~4 and ~alts, is minimized. A thermal heating is effected only in the first and second proces-sing ~tages, in ~hich the acid flo~s countercurrently to the vapors. ID the first processing stage the concentra-, .
ting treatment iY controlled to keep the H2S04 contentat or belo~ 4~% by weight, calculated without solids, because a higher coDteDt night result in a higher tenden-cy to~ard a precip~tation and ~ormation o~ crusta.
ID ac¢ordance with a further feature of the invention the second processing ~tage compri~es t~o ll~uld circuit~, each o~ ~hich include~ a heat es-change ZOD8, ~hich i9 heated ~ith llve ~team, and an e~aporating zoDe~ and the t~o e~aporating zones are operated under the ~ame pres~ure. In that ca~e the t~o partial stages may be designed to permit of a change-over of their connections or can lndividuall~ be shut do~n. A~ a result~ any crusts formed in the partial stage ~hich contains the more highly concentrated liquid can be : . . - .
i ' .
.
., ~ .
202~7 eliminated at least in part or a further growth of such cru~t~ can be prevented if a change-over is efrected so that said partial stage is now supplied ~ith leas highlg conce~trated liquid. In this manner the time for which the pla~t can be operated before it must be shut down and the heating surface-s must be cleaned can co~siderably be prolonged.
It is not necessar~ in the proce~s to effect a preconcentrating, at a higber or lower ex-pense, of the liquid which is to be supplied to the first processing s~age. But it ma~ be desirable to preheat such liquid by meaDs o~ ~aste heat, e.g., b~ meaDs of condensate obtained from vapors and/or live steam.
The apparatus for carr~ing out the process described first hereinbefore comprises a first heated processin6 stage, ~hich is provided ~ith a ~uppl~ lino ~or the llquid to be concentrated, a ~irst evaporating vess~l, a ~ir~t indirect heat exchaDger~ a ~irst circulatiDg liDe, a pump lncorporated iD said rirst circulating llDe, and a liquid discharge line~
~hich lead~ to a Jecond heated proce~sing ~tage~ ~hich comprisos at leaJt one o~aporatlng ~s~Jol aDd at loa~t one lndlrect heat exchaDger pro~ided ~ith me aD~ rOr ~uppl~ing llve ~team. The ~econd ~tage also compri~eJ
9 ~apor line lea~ng from the e~aporatin~ ve~sel to the indirect heat exchanger Or the first processing stage and a liquid linc leading from the second processin~
:
- 2~2~3~
stage to a flashing vessel. ~he plant in accordance ~ith the inveDtio~ is operated without a need for complicated evaporator units and particularlg ~ith-out a need for f~lling-film or rising-film evapora-tors.
wing to the agzressive nature of the fluids to be processed the materials used in the plant must be carefully selected. It is desirable to use steel which is lined with lead and stone. In that case the circul~ing lin~s and even tke evaporating vessels may be durabl~ protected a~ain~t an attack by acid.
The tubes of the heat exchanger may consist, e.g., of graphite.
EmbodimeDts of the process and of the apparatu~ will be ~xplained ~ith reference to the draw-inB-~ iguro 1 sho~ a ~irst ~ariant.
~ igure 2 shoRs a ~ariant in ~hich the second pro¢esaing stage ¢oDaists o~ t~o part~.
In accordaDce ~ith Fi~ure 1 the liquld ~hich ia to be concentratod and ~hich contains sul~uria acid~ water and dl~ol~ed salt i8 supplled in line 1.
The ~2S~4 coDtent lies in the range of about 15 to 25 %
b~ ~eight, calculated ~ithout solids. ~he rirst thermal processing stage compri~es the circulating indirect heat line 2, the circulatiDg pump 3 incorporated in the line 2, the first indirect heat exchanger 4 and the first ,. . ..
- ~2~7 evaporatiDg vessel 5. The heat exchanger 4 is heated ; with vapors from line 7. Conden3ate obtained rro~ the vapors is drained in li~e 8. ~he evaporating vessel is filled ~ith liquid only iD part and vapors are wit~-drawn iD line 9. ~he highest temperatures of the liquid in the first processing stage occur at the outle~ of the heat exchanger 4 and in the vessel 5 a~d lie i~ the - range from 5C to 70 C. In that stage the H2S04 co~tent of the liquid will be about 25 to 40 % bg weight, cal-culated without solids.
~ hat liquid is withdr~w~ in line 10 and is fed to the secoDd thermal processing stage. The second thermal processiDg stage comprises the circulating line 12, the circulating pump 13, the iDdirect heat ex-changer 14 and the evaporatiDg vessel 15. ~hat ~econd stage 13 heated ~ith livo ~team, ~hich i8 ~ed in line 17 to the heat exchanger 14. Conden~ate i9 drained in line 18, The evaporating ve~sel 15 is also rilled ~lth llquid only iD part and the vapors withdra~n from it rlo~ in line 7 to the heat exchanger 4, At th0 outlet of the heat ex¢hanger 14 and in the evaporatiDg ve~el 15 the temperatures of the liquid lie in the range from 130 to 160 C and the llquid ha~ an ~2S04 content Or 55 to 70 ~ by ~eight~ cal-culated without ~olids. ~he pres~ure iD the evaporatlng vessel 15 i~ higher by 0,2 to 1 bar than in the evaporat-;
' ' '' ' ' ~ ~ , , ,: ' ' - 2~2~7 iD5 vessel 5. In order to overcome that pressure ~-ference and the inevitable friction losses without a rleed for a feed pump in line 10, the e~aporating vessel 5 of the ~irst processin~ stage is disp~sed on a level which is hi~her by several meters, particularly by 2 to 10 meters, than the level of the evaporatin~ vessel 15 of the second processiDg stage 90 that the higher hydro-static pressure in the container 5 is sufficieDt for effecting a flow of the liquid through line 10 into the circulating line 12.
Partly co~centrated liquid i9 with-dra~n from the evaporating vessel 15 in line 19 and is delivered to a circulatiDg line 22, which belongs to a flashiDg vessel 25 and in which a circulating pump 23 is lncorporated~ The flashing vessel 25 i5 fiiled wlth liquid i~ part. The concentrated liquid is withdra~n from the rlashin~ ves~el 25 through line 26. ~he ~inal concentratio~ corresponds to an X2S04 coutent Or 60 to 80 X b~ ~elght~ preferabl~ at least 65 % b~ weiBh~ cal-culated ~ithout solids. The prossure in the ~l~bl~g ~essel 25 19 lower b~ 0~2 to 1 bar tha~ iD th~ evaporat-ins vess~l 15. Vapor~ lea~e the ~lashiD~ vessel 25 in line 27 and in a ~a~i~old 28 are fed togethor wlth the vapor~ from llne 9 to a condeuser 21, which i8 CoDneCted to a vacuum source 29.
In the variant shown in Fl~ure 2 the process comprises a ~econd thermal processiu~ sta~e, ~hich coDsists of two parts, and the two partial ~ta~es , 2~2~ 7 can be changed over and are so de3igned that their con-nections can be chan~ed over and each of them can be shut off. The first proc~ssing stage comprises the 5Upp-1~ line 1, the circulatin~ line 2 and th~evaporating vessel 5 and is designed exactly as has been explained ~ith reference to Figure 1. In ~igure 2 the pumps in the circulating line3 ha~e not been ~hown, for the sake of clearness, also the condenser 21 and the associated vacuum source 29 sho~n in Figure 1.
Liqu~d which leaves the first thermal processing stage in line 10 enters through line 11 and ~he opened valve lla the circulating line 12a, which extends through the heat exchanger 14a and the eva-porating ~essel 15a. The heat exchanger 14a is heated by l~ve steam rrom line 17a. Vapors are wi~hdrawn f~om the ves~el 15a in llne 7a. ~he valve 20 in line l9a i8 open aDd the ~al~e 30 in ~ine 31 is clo~ed. ~he partl~
concentrated liguid ~lo~i in llne 19a to the other par-tlal stage o~ the second ~hermal processing stage. ~hat other partial stage comp ~ ses the circulatlng line 12b~
the heat exchanger 14b~ t le evaporating ve8sel 15b~ the li~e 17b for feeding live ~team and the lino 7 ror ~ith-dra~ing ~apor~. The press ~re in the two V0~8el8 15a and i 15b ls the same and the ~por~ rrom said two ~essels ser~e to heat the heat exchanger 4 Or the first thermal processing stage.
; Partl~ concentrated liquid is ~ith-drawn iD line l9b from thi second thermal proce~sing ~tage t ~ ., 2 0 2 ~ Y L~l 7 g and i9 deliver~d through the ope~ valve ,2 to the cir-culating line 22, which leads to the flashing vessel 25. The valve 34 in line 35 is closed. Liquid having the final co~centration is withdrawn ir. line 26. The vapors are conducted in li~es 27 and 28 to the conden-ser, not shown.
In the arrangement shown in Figure 2 it may be desired to ~hut down the second partial ~tage of the ~econd thermal processing stage.
That second paxtial -qtage comprises the evaporating vessel 15b. That shutdown can be effected in th~t the valve 20 i~ closed and the valve 34 is opened so that liquid is flowing to the circulating line 22 from the vessel 15a through liDe 35. OD the other hand, it ma~
be desired to shut down only the first partial stage, ~hl¢h comprises the evaporating vessel 15a. In that case thevslveY lla and 20 are closed and liquld ~iowo rrom llne 10 through line ~1 and the now opeD valvo 30 to the clrculating lin~ 12b. Owing to these change9 o~
the connections, the ~econd processing stage remaine operable but has a lowor capacit~.
In another de9irable ~ariant the con-nection~ Or the two partial stages Or the second thermal processing stage shown ln Fi~uro 2 ma~ be changed ~o that that partial stage which i~ first flown through b~ the liquid and compri~es the evapor~ting ve~sel 15a is now flowD throu~h after the other partlal stage, which 2~2~
--10-- .
comprises the evaporating vessel 15b. For that purpose the valve lla i9 closed and liquid is conducted rom line 10 through line 31 and the DOW open valve 30 to the circulating line 12b. When the val~e 32 is closed the liquid ~hich is drained in line 19b is fed through the now open valve 36 and the line 37 to the circulating line 12a. The liquid drained from the evaporating vessel 15a flows through the now open valve 34 and the line 35 to the circulating line 22. That change of connections will be desirable, e.g., when crusts ha~e been formed in that partial stage which was initially supplied with more highl~ concentrated liquid and it is desired now to supply that partial stage with less highl~ concen-trated liquid from line 10 90 that the crusts are dis-~olved or at least are prevented from growiDg further.
~xamples , ' In each Or the t~o follo~i~g Examples a ~ater-containiDg preheated sul~uri¢ acid is conce`n-trated ~hich has be¢ome availablo iD the production Or ~i2 pi~meDts. In th~ rirst ~xample, the processing is iD accordance ~ith ~igure l; correspondiDg ~alues are ~tated in the Tables ih columD~ providod ~ith the letter (~) be3ide the referenco nu~erals for the lines, where this is necessary. In the second Example the processing i9 in accordance wlth Figure 2 and the corresFondiDg ~alues are stated in column~ provided with the letter (B) ~eside the rererence Dumerals fDr the line.
, - -- 2~2~7 1 (A) 1 (B) 10 (A) 10 (B~
Rate (kg/h) 22,000 20,000 15,500 14,000 S04 (% by ~eight) 19.4 19.4 27.4 27.4 Salts (% bD weight) 14.4 14.4 20.4 20.4 ~ater (% by weight) 66.2 66.2 52.2 52.2 H S04 content (~ by we?ight, ~ithout solids) 23.0 23.0 34-5 34-5 ~emperature (C) 76 76 56 56 19 19a 19b ?6(A)26(B) Rate (kg/~) 9,600 9,950 8,650 9,3508,420 H2S04 (% by ~eight) 44~4 39,o 44,4 45,645,6 Salt~ (% by weiæht) 33,0 28,9 33,0 35,235,2 ~ater (% bg weight) 22,6 42,1 22,6 19,419,4 H2S04 content (% by 67,5 48,0 67,5 70,070,0 ~ol6ht, ~ithout solid~) Temperature ( C) 142 120 142 115 115 ;
S~ppl~ o~ e stea~throu6h lino~ 17, 17a and 17b:
17 17a 1 j7b Rato (kg/h) 8 ~ 800 5 ~ 9 2 ~ 100 Temporaturo (C) 170 155 155 Pressure (bars) 8 5.5 5.5 .
, - 2~2~
Vapors f~om ves~els 5, 15, 15a, 15b and 25:
5 (A) 5 (B) 15 15a 15b 25 (A~ 25 (~`
Rate (kg~h) 6,450 5,800 5,950 4,050 1,300 250 23C
Temperature (C) 42 42 79 79 79 42 42 The pressure in each of the vessels 15, 15a and 15b is 0.47 bars. O~ing to the vacuum source 29, the pressure in the vessels 5 and 25 is about 0.08 bar in both Example9.
' ' ,
stage to a flashing vessel. ~he plant in accordance ~ith the inveDtio~ is operated without a need for complicated evaporator units and particularlg ~ith-out a need for f~lling-film or rising-film evapora-tors.
wing to the agzressive nature of the fluids to be processed the materials used in the plant must be carefully selected. It is desirable to use steel which is lined with lead and stone. In that case the circul~ing lin~s and even tke evaporating vessels may be durabl~ protected a~ain~t an attack by acid.
The tubes of the heat exchanger may consist, e.g., of graphite.
EmbodimeDts of the process and of the apparatu~ will be ~xplained ~ith reference to the draw-inB-~ iguro 1 sho~ a ~irst ~ariant.
~ igure 2 shoRs a ~ariant in ~hich the second pro¢esaing stage ¢oDaists o~ t~o part~.
In accordaDce ~ith Fi~ure 1 the liquld ~hich ia to be concentratod and ~hich contains sul~uria acid~ water and dl~ol~ed salt i8 supplled in line 1.
The ~2S~4 coDtent lies in the range of about 15 to 25 %
b~ ~eight, calculated ~ithout solids. ~he rirst thermal processing stage compri~es the circulating indirect heat line 2, the circulatiDg pump 3 incorporated in the line 2, the first indirect heat exchanger 4 and the first ,. . ..
- ~2~7 evaporatiDg vessel 5. The heat exchanger 4 is heated ; with vapors from line 7. Conden3ate obtained rro~ the vapors is drained in li~e 8. ~he evaporating vessel is filled ~ith liquid only iD part and vapors are wit~-drawn iD line 9. ~he highest temperatures of the liquid in the first processing stage occur at the outle~ of the heat exchanger 4 and in the vessel 5 a~d lie i~ the - range from 5C to 70 C. In that stage the H2S04 co~tent of the liquid will be about 25 to 40 % bg weight, cal-culated without solids.
~ hat liquid is withdr~w~ in line 10 and is fed to the secoDd thermal processing stage. The second thermal processiDg stage comprises the circulating line 12, the circulating pump 13, the iDdirect heat ex-changer 14 and the evaporatiDg vessel 15. ~hat ~econd stage 13 heated ~ith livo ~team, ~hich i8 ~ed in line 17 to the heat exchanger 14. Conden~ate i9 drained in line 18, The evaporating ve~sel 15 is also rilled ~lth llquid only iD part and the vapors withdra~n from it rlo~ in line 7 to the heat exchanger 4, At th0 outlet of the heat ex¢hanger 14 and in the evaporatiDg ve~el 15 the temperatures of the liquid lie in the range from 130 to 160 C and the llquid ha~ an ~2S04 content Or 55 to 70 ~ by ~eight~ cal-culated without ~olids. ~he pres~ure iD the evaporatlng vessel 15 i~ higher by 0,2 to 1 bar than in the evaporat-;
' ' '' ' ' ~ ~ , , ,: ' ' - 2~2~7 iD5 vessel 5. In order to overcome that pressure ~-ference and the inevitable friction losses without a rleed for a feed pump in line 10, the e~aporating vessel 5 of the ~irst processin~ stage is disp~sed on a level which is hi~her by several meters, particularly by 2 to 10 meters, than the level of the evaporatin~ vessel 15 of the second processiDg stage 90 that the higher hydro-static pressure in the container 5 is sufficieDt for effecting a flow of the liquid through line 10 into the circulating line 12.
Partly co~centrated liquid i9 with-dra~n from the evaporating vessel 15 in line 19 and is delivered to a circulatiDg line 22, which belongs to a flashiDg vessel 25 and in which a circulating pump 23 is lncorporated~ The flashing vessel 25 i5 fiiled wlth liquid i~ part. The concentrated liquid is withdra~n from the rlashin~ ves~el 25 through line 26. ~he ~inal concentratio~ corresponds to an X2S04 coutent Or 60 to 80 X b~ ~elght~ preferabl~ at least 65 % b~ weiBh~ cal-culated ~ithout solids. The prossure in the ~l~bl~g ~essel 25 19 lower b~ 0~2 to 1 bar tha~ iD th~ evaporat-ins vess~l 15. Vapor~ lea~e the ~lashiD~ vessel 25 in line 27 and in a ~a~i~old 28 are fed togethor wlth the vapor~ from llne 9 to a condeuser 21, which i8 CoDneCted to a vacuum source 29.
In the variant shown in Fl~ure 2 the process comprises a ~econd thermal processiu~ sta~e, ~hich coDsists of two parts, and the two partial ~ta~es , 2~2~ 7 can be changed over and are so de3igned that their con-nections can be chan~ed over and each of them can be shut off. The first proc~ssing stage comprises the 5Upp-1~ line 1, the circulatin~ line 2 and th~evaporating vessel 5 and is designed exactly as has been explained ~ith reference to Figure 1. In ~igure 2 the pumps in the circulating line3 ha~e not been ~hown, for the sake of clearness, also the condenser 21 and the associated vacuum source 29 sho~n in Figure 1.
Liqu~d which leaves the first thermal processing stage in line 10 enters through line 11 and ~he opened valve lla the circulating line 12a, which extends through the heat exchanger 14a and the eva-porating ~essel 15a. The heat exchanger 14a is heated by l~ve steam rrom line 17a. Vapors are wi~hdrawn f~om the ves~el 15a in llne 7a. ~he valve 20 in line l9a i8 open aDd the ~al~e 30 in ~ine 31 is clo~ed. ~he partl~
concentrated liguid ~lo~i in llne 19a to the other par-tlal stage o~ the second ~hermal processing stage. ~hat other partial stage comp ~ ses the circulatlng line 12b~
the heat exchanger 14b~ t le evaporating ve8sel 15b~ the li~e 17b for feeding live ~team and the lino 7 ror ~ith-dra~ing ~apor~. The press ~re in the two V0~8el8 15a and i 15b ls the same and the ~por~ rrom said two ~essels ser~e to heat the heat exchanger 4 Or the first thermal processing stage.
; Partl~ concentrated liquid is ~ith-drawn iD line l9b from thi second thermal proce~sing ~tage t ~ ., 2 0 2 ~ Y L~l 7 g and i9 deliver~d through the ope~ valve ,2 to the cir-culating line 22, which leads to the flashing vessel 25. The valve 34 in line 35 is closed. Liquid having the final co~centration is withdrawn ir. line 26. The vapors are conducted in li~es 27 and 28 to the conden-ser, not shown.
In the arrangement shown in Figure 2 it may be desired to ~hut down the second partial ~tage of the ~econd thermal processing stage.
That second paxtial -qtage comprises the evaporating vessel 15b. That shutdown can be effected in th~t the valve 20 i~ closed and the valve 34 is opened so that liquid is flowing to the circulating line 22 from the vessel 15a through liDe 35. OD the other hand, it ma~
be desired to shut down only the first partial stage, ~hl¢h comprises the evaporating vessel 15a. In that case thevslveY lla and 20 are closed and liquld ~iowo rrom llne 10 through line ~1 and the now opeD valvo 30 to the clrculating lin~ 12b. Owing to these change9 o~
the connections, the ~econd processing stage remaine operable but has a lowor capacit~.
In another de9irable ~ariant the con-nection~ Or the two partial stages Or the second thermal processing stage shown ln Fi~uro 2 ma~ be changed ~o that that partial stage which i~ first flown through b~ the liquid and compri~es the evapor~ting ve~sel 15a is now flowD throu~h after the other partlal stage, which 2~2~
--10-- .
comprises the evaporating vessel 15b. For that purpose the valve lla i9 closed and liquid is conducted rom line 10 through line 31 and the DOW open valve 30 to the circulating line 12b. When the val~e 32 is closed the liquid ~hich is drained in line 19b is fed through the now open valve 36 and the line 37 to the circulating line 12a. The liquid drained from the evaporating vessel 15a flows through the now open valve 34 and the line 35 to the circulating line 22. That change of connections will be desirable, e.g., when crusts ha~e been formed in that partial stage which was initially supplied with more highl~ concentrated liquid and it is desired now to supply that partial stage with less highl~ concen-trated liquid from line 10 90 that the crusts are dis-~olved or at least are prevented from growiDg further.
~xamples , ' In each Or the t~o follo~i~g Examples a ~ater-containiDg preheated sul~uri¢ acid is conce`n-trated ~hich has be¢ome availablo iD the production Or ~i2 pi~meDts. In th~ rirst ~xample, the processing is iD accordance ~ith ~igure l; correspondiDg ~alues are ~tated in the Tables ih columD~ providod ~ith the letter (~) be3ide the referenco nu~erals for the lines, where this is necessary. In the second Example the processing i9 in accordance wlth Figure 2 and the corresFondiDg ~alues are stated in column~ provided with the letter (B) ~eside the rererence Dumerals fDr the line.
, - -- 2~2~7 1 (A) 1 (B) 10 (A) 10 (B~
Rate (kg/h) 22,000 20,000 15,500 14,000 S04 (% by ~eight) 19.4 19.4 27.4 27.4 Salts (% bD weight) 14.4 14.4 20.4 20.4 ~ater (% by weight) 66.2 66.2 52.2 52.2 H S04 content (~ by we?ight, ~ithout solids) 23.0 23.0 34-5 34-5 ~emperature (C) 76 76 56 56 19 19a 19b ?6(A)26(B) Rate (kg/~) 9,600 9,950 8,650 9,3508,420 H2S04 (% by ~eight) 44~4 39,o 44,4 45,645,6 Salt~ (% by weiæht) 33,0 28,9 33,0 35,235,2 ~ater (% bg weight) 22,6 42,1 22,6 19,419,4 H2S04 content (% by 67,5 48,0 67,5 70,070,0 ~ol6ht, ~ithout solid~) Temperature ( C) 142 120 142 115 115 ;
S~ppl~ o~ e stea~throu6h lino~ 17, 17a and 17b:
17 17a 1 j7b Rato (kg/h) 8 ~ 800 5 ~ 9 2 ~ 100 Temporaturo (C) 170 155 155 Pressure (bars) 8 5.5 5.5 .
, - 2~2~
Vapors f~om ves~els 5, 15, 15a, 15b and 25:
5 (A) 5 (B) 15 15a 15b 25 (A~ 25 (~`
Rate (kg~h) 6,450 5,800 5,950 4,050 1,300 250 23C
Temperature (C) 42 42 79 79 79 42 42 The pressure in each of the vessels 15, 15a and 15b is 0.47 bars. O~ing to the vacuum source 29, the pressure in the vessels 5 and 25 is about 0.08 bar in both Example9.
' ' ,
Claims (7)
1. A process of concentrating a liquid which contains sulfuric acid and water and in which the concentration of H2SO4, calculated without solids, is about 15 to 30 % by weight, characterized in that the liquid is circulated in a first heated processing stage at highest temperatures of 50 to 70 °C through a first heat exchange zone, which is indirectly heated with water vapor, and through a first evaporating zone, vapors and a liquid stream which contains sulfuric acid, water and dissolved salts and has an H2SO4 content of about 25 to 40 % by weight, calculated without solids, are separately withdrawn from the first evaporating zone and red to a second heated processing stage, the liquid is circulated in the second heated processing stage at highest temperatures of 130 to 160 °C and under a pressure which is higher than in the first processing stage is at least one circuit through at least one heat exchange zone, which is heated with live steam, and through at least one evaporating zone, the vapors from the evaporating zone or zones are fed to the first heat exchange zone as a heating fluid, partly concentrated liquid having an H2SO4 content of 55 to 70 % by weight, calculated without solids, is withdr awn from an evapo-rating zone of the second processing stage and is fed to a flashing zone, in w hich the liquid is flashed with a reduction of the temperature of the liquid to a value which is lower by 20 to 70 °C than the highest temperature in the second processing stage and concentrated liquid having an H2SO4 content of 60 to 80 % by weight, calcu-lated without solids, is withdrawn from the flashing zone.
2. A process according to claim 1, characterized in that the second processing stage comprises two liquid circuits, each of which includes a heat ex-change zone, which is heated with live steam, and an eva-porating zone, and the two evaporating zones are operated under the same pressure.
3. A process according to claim 2, characterized in that each of the two liquid circuits of the second processing stage is adapted to be selectively supplied first with liquid from the first processing stage.
4. A process according to claim 1 2 or 3, characterized in that the liquid supplied to the first processing stage has been obtained in the produc-tion of TiO2 pigments and contains 5 to 20 % by weight dissolved salts.
5. An apparatus for concentrating a liquid which contains sulfuric acid and water and in which the concentration of H2SO4, calculated without solids, is about 15 to 30 % by weight, characterized by a first heated processing stage, which is provided with a supply line for the liquid to be concentrated, a first evaporating vessel, a first indirect heat exchanger, a first circulating line, a pump incorporated in said first circulating line, and a liquid discharge line, which leads to a second heated processing stage, which com-prises at least one evaporating vessel and at least one indirect heat exchanger provided with means for supply-ing live steam, and also a vapor line leading from the evaporating vessel to the indirect heat exchanger of the first processing stage and a liquid line leading from the second processing stage to a flashing vessel.
6. An apparatus according to claim 5, characterized in that the evaporating vessel of the first processing stage is disposed on a level which is 2 to 10 meters above the level of the evaporating vessel or vessels of the second processing stage.
7. An apparatus according to claim 5 or 6, characterized in that at least one evaporating vessel and one circulating line are internally provided with a lining of lead and a lining of stone.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3935892A DE3935892C2 (en) | 1989-10-27 | 1989-10-27 | Method and device for concentrating a liquid containing sulfuric acid and water |
| DEP3935892.5 | 1989-10-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2024547A1 true CA2024547A1 (en) | 1991-04-28 |
Family
ID=6392409
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002024547A Abandoned CA2024547A1 (en) | 1989-10-27 | 1990-09-04 | Process and apparatus for concentrating a liquid which contains sulfuric acid and water |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0425000B2 (en) |
| JP (1) | JPH03146408A (en) |
| AU (1) | AU624540B2 (en) |
| BR (1) | BR9005114A (en) |
| CA (1) | CA2024547A1 (en) |
| DE (2) | DE3935892C2 (en) |
| ES (1) | ES2047829T5 (en) |
| MY (1) | MY106697A (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH682398A5 (en) * | 1991-09-13 | 1993-09-15 | Escher Wyss Ag | A method for saving energy in the production of titanium dioxide. |
| DE19741511A1 (en) * | 1997-09-20 | 1999-04-01 | Metallgesellschaft Ag | Process for concentrating thin acid by utilizing process heat in a forced circulation evaporator system |
| GB9816464D0 (en) * | 1998-07-30 | 1998-09-23 | Tioxide Group Services Ltd | Process for the concentration of dilute sulphuric acid solutions |
| CA2385865A1 (en) | 1999-09-28 | 2001-04-05 | Takashi Okamura | Triazolopurine derivatives, pharmaceutical compositions containing the derivatives, and adenosine a3 receptor affinitive agents |
| DE10024457A1 (en) * | 2000-05-18 | 2001-11-29 | Sachtleben Chemie Gmbh | Preventing incrustation in recovery of sulfuric acid in titanium dioxide production by pre-concentrating the dilute acid to above 32-45 weight percent |
| ITPR20040050A1 (en) * | 2004-07-20 | 2004-10-20 | Fmc Technologies Italia Spa | EVAPORATION PLANT FOR FRUITS AND VEGETABLE PRODUCTS WITH LOW ENERGY CONSUMPTION AND VERY LIMITED THERMAL DAMAGE. |
| WO2008003297A2 (en) * | 2006-07-03 | 2008-01-10 | Lailach Guenter | Method and system for concentrating metal sulfate-containing sulfuric acid |
| JP6001328B2 (en) * | 2012-05-23 | 2016-10-05 | パンパシフィック・カッパー株式会社 | Sulfuric acid acidic liquid concentration apparatus, sulfuric acid acidic liquid concentration method, and crude nickel sulfate recovery method |
| JP2016180187A (en) * | 2016-07-05 | 2016-10-13 | パンパシフィック・カッパー株式会社 | Concentrating apparatus of sulfuric acid acidic solution, concentrating method of sulfuric acid acidic solution, and recovery method of crude nickel sulfate |
| DE102020131827A1 (en) | 2020-12-01 | 2022-06-02 | Andreas Wilk | Device and method for concentrating corrosive liquids |
| DE102023102313A1 (en) | 2023-01-31 | 2024-08-01 | Mkr Metzger Gmbh Recyclingsysteme | Device and method for the preparation of process medium |
Family Cites Families (7)
| 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 |
| DE1233368B (en) * | 1962-08-13 | 1967-02-02 | Heraeus Schott Quarzschmelze | Process for the continuous distillation of sulfuric acid in apparatus made of ceramic materials |
| DE2632989A1 (en) * | 1976-07-22 | 1978-02-02 | Hoechst Ag | PROCESS FOR REGENERATING SULFURIC ACID |
| DE2824010A1 (en) * | 1978-06-01 | 1979-12-13 | Metallgesellschaft Ag | METHOD FOR CONCENTRATING DILUSED PHOSPHORIC ACID |
| EP0022181B1 (en) * | 1979-06-13 | 1983-10-12 | Bayer Ag | Process and apparatus for regenerating sulfuric acid |
| DE3327769A1 (en) * | 1983-08-02 | 1985-02-14 | Bayer Ag, 5090 Leverkusen | METHOD FOR THE TREATMENT OF THICK ACID |
| DE3632623A1 (en) * | 1986-09-25 | 1988-03-31 | Bayer Ag | METHOD FOR CONCENTRATING SULFURIC ACID |
-
1989
- 1989-10-27 DE DE3935892A patent/DE3935892C2/en not_active Expired - Lifetime
-
1990
- 1990-03-29 MY MYPI90000493A patent/MY106697A/en unknown
- 1990-09-04 CA CA002024547A patent/CA2024547A1/en not_active Abandoned
- 1990-09-26 DE DE90202545T patent/DE59003963D1/en not_active Expired - Fee Related
- 1990-09-26 EP EP90202545A patent/EP0425000B2/en not_active Expired - Lifetime
- 1990-09-26 ES ES90202545T patent/ES2047829T5/en not_active Expired - Lifetime
- 1990-10-11 JP JP2273143A patent/JPH03146408A/en active Pending
- 1990-10-12 BR BR909005114A patent/BR9005114A/en not_active Application Discontinuation
- 1990-10-26 AU AU64992/90A patent/AU624540B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE59003963D1 (en) | 1994-02-03 |
| JPH03146408A (en) | 1991-06-21 |
| EP0425000B2 (en) | 1996-11-27 |
| DE3935892C2 (en) | 1994-08-25 |
| AU6499290A (en) | 1991-05-02 |
| AU624540B2 (en) | 1992-06-11 |
| ES2047829T5 (en) | 1997-01-16 |
| MY106697A (en) | 1995-07-31 |
| BR9005114A (en) | 1991-09-17 |
| EP0425000B1 (en) | 1993-12-22 |
| EP0425000A1 (en) | 1991-05-02 |
| ES2047829T3 (en) | 1994-03-01 |
| DE3935892A1 (en) | 1991-05-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |