DK149784B - PROCEDURE FOR RECOVERING CHEMICALS FROM USED SODIUM BASE SULPHITE LIQUID - Google Patents
PROCEDURE FOR RECOVERING CHEMICALS FROM USED SODIUM BASE SULPHITE LIQUID Download PDFInfo
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- DK149784B DK149784B DK212673AA DK212673A DK149784B DK 149784 B DK149784 B DK 149784B DK 212673A A DK212673A A DK 212673AA DK 212673 A DK212673 A DK 212673A DK 149784 B DK149784 B DK 149784B
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- Prior art keywords
- sodium
- sulfite
- hydrogen
- liquor
- carbon dioxide
- Prior art date
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- 238000000034 method Methods 0.000 title claims description 38
- 239000011734 sodium Substances 0.000 title claims description 14
- 239000000126 substance Substances 0.000 title claims description 10
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 title claims description 7
- 229910052708 sodium Inorganic materials 0.000 title claims description 7
- 239000007788 liquid Substances 0.000 title claims description 5
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 title 1
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 76
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 claims description 50
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 claims description 49
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 43
- 239000007789 gas Substances 0.000 claims description 43
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 42
- 239000001569 carbon dioxide Substances 0.000 claims description 37
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 claims description 33
- 238000006243 chemical reaction Methods 0.000 claims description 28
- 229910000037 hydrogen sulfide Inorganic materials 0.000 claims description 25
- 235000010265 sodium sulphite Nutrition 0.000 claims description 25
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 claims description 22
- 239000000243 solution Substances 0.000 claims description 22
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 21
- 238000011084 recovery Methods 0.000 claims description 20
- 238000002485 combustion reaction Methods 0.000 claims description 18
- HEMHJVSKTPXQMS-UHFFFAOYSA-M sodium hydroxide Substances [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 15
- DWAQJAXMDSEUJJ-UHFFFAOYSA-M Sodium bisulfite Chemical compound [Na+].OS([O-])=O DWAQJAXMDSEUJJ-UHFFFAOYSA-M 0.000 claims description 15
- 235000010267 sodium hydrogen sulphite Nutrition 0.000 claims description 15
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 claims description 13
- 239000000203 mixture Substances 0.000 claims description 13
- 239000011593 sulfur Substances 0.000 claims description 13
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 12
- 229910052717 sulfur Inorganic materials 0.000 claims description 12
- 235000017557 sodium bicarbonate Nutrition 0.000 claims description 11
- 229910000030 sodium bicarbonate Inorganic materials 0.000 claims description 11
- 229940079827 sodium hydrogen sulfite Drugs 0.000 claims description 10
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 claims description 9
- 229910001868 water Inorganic materials 0.000 claims description 9
- 239000003546 flue gas Substances 0.000 claims description 8
- 229910052979 sodium sulfide Inorganic materials 0.000 claims description 8
- 239000000155 melt Substances 0.000 claims description 7
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 claims description 7
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 claims description 6
- 229940079826 hydrogen sulfite Drugs 0.000 claims description 6
- WQDSRJBTLILEEK-UHFFFAOYSA-N sulfurous acid Chemical compound OS(O)=O.OS(O)=O WQDSRJBTLILEEK-UHFFFAOYSA-N 0.000 claims description 6
- 238000010521 absorption reaction Methods 0.000 claims description 5
- 238000004537 pulping Methods 0.000 claims description 5
- 239000004289 sodium hydrogen sulphite Substances 0.000 claims description 5
- HYHCSLBZRBJJCH-UHFFFAOYSA-M sodium hydrosulfide Chemical compound [Na+].[SH-] HYHCSLBZRBJJCH-UHFFFAOYSA-M 0.000 claims description 5
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 4
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 claims description 4
- 239000007864 aqueous solution Substances 0.000 claims description 4
- 230000003197 catalytic effect Effects 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 235000019988 mead Nutrition 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 claims 1
- 239000000567 combustion gas Substances 0.000 claims 1
- 239000003085 diluting agent Substances 0.000 claims 1
- 238000010248 power generation Methods 0.000 claims 1
- 235000017550 sodium carbonate Nutrition 0.000 description 14
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 238000005201 scrubbing Methods 0.000 description 2
- 229910052938 sodium sulfate Inorganic materials 0.000 description 2
- 235000011152 sodium sulphate Nutrition 0.000 description 2
- GNFTZDOKVXKIBK-UHFFFAOYSA-N 3-(2-methoxyethoxy)benzohydrazide Chemical compound COCCOC1=CC=CC(C(=O)NN)=C1 GNFTZDOKVXKIBK-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 244000201986 Cassia tora Species 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910004809 Na2 SO4 Inorganic materials 0.000 description 1
- 239000007832 Na2SO4 Substances 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000010000 carbonizing Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- TXKMVPPZCYKFAC-UHFFFAOYSA-N disulfur monoxide Inorganic materials O=S=S TXKMVPPZCYKFAC-UHFFFAOYSA-N 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- NCAIGTHBQTXTLR-UHFFFAOYSA-N phentermine hydrochloride Chemical compound [Cl-].CC(C)([NH3+])CC1=CC=CC=C1 NCAIGTHBQTXTLR-UHFFFAOYSA-N 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000003265 pulping liquor Substances 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 229910000342 sodium bisulfate Inorganic materials 0.000 description 1
- WBHQBSYUUJJSRZ-UHFFFAOYSA-M sodium bisulfate Chemical compound [Na+].OS([O-])(=O)=O WBHQBSYUUJJSRZ-UHFFFAOYSA-M 0.000 description 1
- SRRKNRDXURUMPP-UHFFFAOYSA-N sodium disulfide Chemical compound [Na+].[Na+].[S-][S-] SRRKNRDXURUMPP-UHFFFAOYSA-N 0.000 description 1
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 1
- 229910001948 sodium oxide Inorganic materials 0.000 description 1
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 1
- 235000019345 sodium thiosulphate Nutrition 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000000153 supplemental effect Effects 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C11/00—Regeneration of pulp liquors or effluent waste waters
- D21C11/02—Regeneration of pulp liquors or effluent waste waters of acid, neutral or alkaline sulfite lye
Landscapes
- Paper (AREA)
- Treating Waste Gases (AREA)
- Processing Of Solid Wastes (AREA)
- Physical Water Treatments (AREA)
Description
149784149784
Den foreliggende opfindelse angår en fremgangsmåde til genvinding af kemikalier fra brugt natriumbase-sulfitlud, ved hvilken den brugte lud koncentreres og brændes i en reduktivt virkende genvindingsovn til dannelse af en. smelte indeholdende natriumsulfid og natriumcarbonat, som derefter opløses i vand og derpå carboneres og sulfiteres til omdannelse af natriumsulfidet og natriumcar-bonatet til genanvendeligt natriumsulfit.The present invention relates to a process for the recovery of chemicals from spent sodium base sulfite liquor, in which the spent liquor is concentrated and burned in a reductively operating recovery furnace to form one. melt containing sodium sulfide and sodium carbonate, which is then dissolved in water and then carbonated and sulfated to convert the sodium sulfide and sodium carbonate into recyclable sodium sulfite.
Der kendes flere fremgangsmåder baseret på forbrænding af brugt natriumbase-sulfitlud i en reduktivt virkende genvindingsovn til dannelse af en uorganisk smelte indeholdende natriumsulfid og natriumcarbonat. Ved den almindeligste af disse fremgangsmåder behandles denne smelte med vand og carbondioxid til fjernelse af svovlet som hydrogensulfid og til dannelse af et carbonat. Derefter oxideres til SO^, som føres sammen med natriumcarbonatet til gendannelse af natriumsulfitet 2 149784 til genanvendelse i en pulpningslud.Several methods are known based on the combustion of spent sodium base sulfite liquor in a reductively recovered furnace to form an inorganic melt containing sodium sulfide and sodium carbonate. In the most common of these processes, this melt is treated with water and carbon dioxide to remove the sulfur as hydrogen sulfide and to form a carbonate. It is then oxidized to SO 2, which is passed with the sodium carbonate to recover sodium sulfite for recycling in a pulping liquor.
Stora-processen, som den kendes i dag, er karakteriseret ved (1) modstrøms-behandling af en klaret smelteopløsning indeholdende natriumcarbonat og natriumsulfid ved forhøjede temperaturer i en kolonne med binde med i det væsentlige rent carbondioxid til uddrivning af en blanding af carbondioxid og hydrogensulfid og til dannelse af en opløsning af natriumhydrogencarbonat og natriumcarbonat, (2) omsætning af denne opløsning med en opløsning af natriumhydrogensulfit ved den såkaldte decarboneringsreaktion til dannelse af natriumsulfit og til frigørelse af carbondioxid, som anvendes i det første trin, (3) omsætning af de blandede carbondioxid- og hydrogensulfidgasser fra det første trin med i det væsentlige rent svovldioxid i en katalytisk virkende Claus-reaktor til dannelse af smeltet svovl og et gasformigt produkt bestående hovedsagligt af carbondioxid med en lille mængde svovldioxid, som kan sendes tilbage til anvendelse i det første trin eller carboneringstrinet, (4) forbrænding af svovlet i en svovlovn til dannelse af svovldioxid, (5) absorption og desorption af svovldioxid fra vand til fremstilling af koncentreret svovldioxid til anvendelse i trin 3 og (6) absorption af svovldioxid i natriumsulfit fra trin 2 til dannelse af natriumhydrogensulfit til anvendelse i trin 2 og/eller til anvendelse ved pulpning. Denne proces er blevet udviklet over et tidsrum på flere år, og mange alternativer er blevet foreslået.The Stora process, as it is known today, is characterized by (1) countercurrent treatment of a clear melt solution containing sodium carbonate and sodium sulfide at elevated temperatures in a column of essentially pure carbon dioxide to expel a mixture of carbon dioxide and hydrogen sulfide. and to form a solution of sodium bicarbonate and sodium carbonate, (2) reacting this solution with a solution of sodium hydrogen sulfite in the so-called decarbonation reaction to form sodium sulfite and to release carbon dioxide used in the first step, (3) reacting the mixed carbon dioxide and hydrogen sulfide gases from the first stage with substantially pure sulfur dioxide in a catalytic Claus reactor to form molten sulfur and a gaseous product consisting mainly of carbon dioxide with a small amount of sulfur dioxide which can be returned for use in the first stage. step or carbonation step, (4) combustion of so wetted in a sulfur furnace to produce sulfur dioxide, (5) absorption and desorption of sulfur dioxide from water to produce concentrated sulfur dioxide for use in step 3, and (6) absorption of sulfur dioxide in sodium sulfite from step 2 to form sodium hydrogen sulfite for use in step 2 and / or for use in pulping. This process has been developed over a period of several years and many alternatives have been proposed.
I U.S.A.-patentskrift nr. 2.909.407 er der beskrevet en fremgangsmåde, hvorved der anvendes S tora-processens hovedtrin, men hvori desuden indgår omsætning af hydrogensulfid med svovldioxid til dannelse af svovl i nærværelse af vand og anvendelse af varme til koagulering og fraskillelse af svovlet.U.S. Patent No. 2,909,407 discloses a process utilizing the main steps of the S tora process, but additionally involving the reaction of hydrogen sulfide with sulfur dioxide to generate sulfur in the presence of water and the use of heat to coagulate and separate the sulfur.
Mead-genvindingsprocessen er karakteriseret ved en sammenkobling af genvindingsovnen og carboneringssystemet ved en kontinuerlig adiabatisk driftsmåde under anvendelse af røggasserne fra forbrændingen af den brugte lud til carboneringen af smelteopløsningen, forbrænding af det frigjorte hydrogensulfid i genvindingsovnen og skrubning af svovldioxidet fra de samlede røggasser med den carbonerede opløsning. Det kritiske carboneringstrin udføres efter modstrømsprincippet i et pakket tårn ved forhøjede temperaturer under anvendelse af en koncentreret, klaret smelteopløsning. Processen er blevet yderligere udviklet ved inkorporering af et pre-carboneringstrin under anvendelse af en del af de hydrogensulfidholdige afgangsgasser til precarbonering, således at volumenet af hydrogensulfidet formindskes og koncentrationen af hydrogensulfidet forøges i de gasser, der sendes tilbage til genvindingsovnen. Denne forbedrede udførelsesform er beskrevet i U.S.A.-patentskrifterne nr. 2.788.273 og 2.849.292 og en ændret udførelsesform heraf i U.S.A.-patentskrift nr. 3.026.240, hvor precarbonering udføres direkte med SO^-fri røggas parallelt med hovedcarboneringen i stedet for i serie med denne.The Mead recovery process is characterized by an interconnection of the recovery furnace and the carbonation system by a continuous adiabatic mode of operation using the flue gases from the combustion of the spent liquor to the carbonation of the melt solution, combustion of the released hydrogen sulphide in the recovery furnace and the scrubbing of the combined sulfur gases. resolution. The critical carbonation step is carried out according to the countercurrent principle in a packed tower at elevated temperatures using a concentrated, clarified melt solution. The process has been further developed by incorporating a pre-carbonation step using a portion of the hydrogen sulphide-containing exhaust gases for precarbonation so that the volume of the hydrogen sulphide is reduced and the concentration of the hydrogen sulphide is increased in the gases sent back to the recovery furnace. This improved embodiment is described in United States Patent Nos. 2,788,273 and 2,849,292, and a modified embodiment thereof in U.S. Patent 3,026,240, wherein precarbonation is performed directly with SO 2 -free flue gas in parallel with the main carbonation instead of series with this one.
Den i II.S.A.-patentskrift nr. 3.005.686 beskrevne Weyerhaeuser-proces er en natriumsulfitgenvindingsproces, der kan anvendes på lud stammende fra pulpning 3 149784 ved kraftprocessen, den neutrale sulfitproces eller den sure sulfitproces. Ved denne proces behandles en smelteopløsning indeholdende natriumcarbonat og natriumsulfid i et første carbondioxid- og hydrogensulfid-absorptionstrin efterfulgt af et carbonerings- og hydrogensulfidstripningstrin i efter hinanden følgende, efter modstrømsprincippet virkende pakkede tårne. Den anvendte gas består hovedsageligt af nitrogen og carbondioxid, der recirkuleres fra et katalytisk omdannelsestrin· Hydrogensulfidet, i en koncentration på mindre end 6% i de dannede gasser, omdannes til svovl eller svovldioxid ved katalytisk oxidation i nærværelse af luft. Den carbonerede lud behandles i et decarboneringstrin med natriumhydrogensulfit til frigørelse af carbondioxid, som også anvendes i carboneringstrinet. Natriumhyd-rogensulfitet dannes i et sulfiteringstårn ved omsætning af den opnåede lud fra decarboneringsreaktionen med svovldioxidet fra en svovlovn.The Weyerhaeuser process described in II.S.A. Patent No. 3,005,686 is a sodium sulfite recovery process that can be applied to liquids derived from pulp 3 149784 by the power process, the neutral sulfite process, or the acid sulfite process. In this process, a melt solution containing sodium carbonate and sodium sulfide is treated in a first carbon dioxide and hydrogen sulfide absorption step, followed by a carbonation and hydrogen sulfide stripping step in successive packed counter-acting towers. The gas used mainly consists of nitrogen and carbon dioxide which are recycled from a catalytic conversion stage · The hydrogen sulfide, at a concentration of less than 6% in the gases formed, is converted to sulfur or sulfur dioxide by catalytic oxidation in the presence of air. The carbonated broth is treated in a decarbonation step with sodium hydrogen sulfite to release carbon dioxide, which is also used in the carbonation step. Sodium hydrogen sulphite is formed in a sulphitation tower by reaction of the obtained liquor from the decarbonation reaction with the sulfur dioxide from a sulfur furnace.
Yderligere fremgangsmåder til carbonering ved fremgangsmåder til genvinding af natriumbase-pulpningslud er beskrevet i Paper Trade Journal, Vol. 154, Issue 25, side 39-49 (1970).Further methods of carbonation by methods for recovering sodium base pulp liquor are described in the Paper Trade Journal, Vol. 154, Issue 25, pages 39-49 (1970).
Formålet med opfindelsen er at tilvejebringe en fremgangsmåde, der er selvforsynende med hensyn til carbondioxid og kan gennemføres adskilt fra genvindingsovnen, og hvor der efter carboneringen opnås en gasformig effluent, som indeholder tilstrækkeligt til at kunne brændes direkte med luft til dannelse af et gasformigt produkt indeholdende og SC^.The object of the invention is to provide a process which is self-sufficient with respect to carbon dioxide and can be carried out separately from the recovery furnace, and where after the carbonation a gaseous effluent containing sufficient to be capable of burning directly with air to obtain a gaseous product containing and SC
Dette opnås ved fremgangsmåden ifølge opfindelsen, der er ejendommelig ved, at der tilvejebringes et carboneringssystem, som er uafhængigt af genvindingsovnen og selvforsynende med hensyn til carbondioxid, idet fremgangsmåden omfatter følgende trin, ved hvilke man (a) precarbonerer opløst smelte ved intim lud/gas-kontakt med en indført gas indeholdende carbondioxid og hydrogensulfid til opnåelse af en første ludfraktion indeholdende natriumhydrogensulfid, natriumhydrogencarbonat og natriumcarbonat og en første gasformig effluent, der hovedsageligt består af N2 og vanddamp,som er i det væsentlige fri for og har formindsket CC^-indhold, (b) carbonerer den nævnte første ludfraktion ved intim lud/gas-kontakt med en gas indeholdende nitrogen og carbondioxid i en koncentration på mindre end 50 volumen % CC^, beregnet på de under carboneringen tilstedeværende gasser på tør basis, til opnåelse af en anden ludfraktion indeholdende natriumhydrogencarbonat og natriumcarbonat, men i det væsentlige strippet for sulfid, og en anden gasformig effluent indeholdende carbondioxid og hydrogensulfid i en større koncentration end 6 volumen %, af hvilken anden gasformig effluent en del anvendes som tilførselsgas i trin a, og en del eventuelt omdannes ved forbrænding til opnåelse af et gasformigt forbrændingsprodukt indeholdende nitrogen, carbondioxid og svovldioxid, og (c) blander den nævnte anden ludfraktion indeholdende natriumhydrogencarbonat 4 149784 og natriumcarbonat med en vandig opløsning af natriumhydrogensulfit og natriumsulfit ved forhøjet temperatur til fremkaldelse af en reaktion mellem nævnte carbonat og hydrogensulfit resulterende i en omdannelse af det sidstnævnte til natriumsulfit til dannelse af en med sulfit beriget vandig hydrogensulfit-sulfit-opløsning og carbondioxid, hvilket CC^ anvendes som en del af carboneringsgasserne i trin b.This is achieved by the process according to the invention, characterized in that a carbonation system is provided which is independent of the recovery furnace and self-sufficient with respect to carbon dioxide, the process comprising the steps of (a) precarbonating dissolved melt by intimate liquor / gas contact with an introduced gas containing carbon dioxide and hydrogen sulfide to obtain a first lye fraction containing sodium hydrogen sulfide, sodium hydrogen carbonate and sodium carbonate, and a first gaseous effluent consisting essentially of N 2 and water vapor which are substantially free of and have reduced CC (b) carbonizing said first liquor fraction by intimate liquor / gas contact with a gas containing nitrogen and carbon dioxide at a concentration of less than 50% by volume of CC 2, calculated on the gases present during the carbonation on dry basis, to give a other liquor fraction containing sodium bicarbonate and sodium carbonate, but substantially stripped for sulfide, and another gaseous effluent containing carbon dioxide and hydrogen sulfide at a concentration greater than 6% by volume, of which other gaseous effluent is partially used as feed gas in step a, and part optionally converted by combustion to obtain a gaseous combustion product containing nitrogen, carbon dioxide and sulfur dioxide, and (c) mixing said second lye fraction containing sodium hydrogen carbonate 4 149784 and sodium carbonate with an aqueous solution of sodium hydrogen sulfite and sodium sulfite at elevated temperature to cause a reaction between said carbonate and hydrogen sulfite resulting in the latter conversion sodium sulfite to form a sulfite-enriched aqueous hydrogen sulfite-sulfite solution and carbon dioxide, which CC is used as part of the carbonation gases of step b.
En hensigtsmæssig udførelsesform for fremgangsmåden ifølge opfindelsen består i, at en del af den nævnte anden gasformige effluent indeholdende carbondioxid og hydrogensulfid behandles til nedsættelse af fugtighedsindholdet og derefter brændes med luft til opnåelse af et gasformigt forbrændingsprodukt indeholdende CO2 og SO2· Den nævnte nedsættelse af fugtighedsindholdet kan ske i en passende kondensator og sætter hydrogensulfidet i stand til lettere at undergå forbrænding til produktion af en betydelig varmemængde, som anvendes til frembringelse af den forhøjede temperatur i fremgangsmådens trin c.A convenient embodiment of the process according to the invention consists in treating part of said second gaseous effluent containing carbon dioxide and hydrogen sulfide to reduce the moisture content and then burning it with air to obtain a gaseous combustion product containing CO2 and SO2. is effected in a suitable condenser and enables the hydrogen sulfide to more easily undergo combustion to produce a considerable amount of heat which is used to produce the elevated temperature in step c of the process.
Ved den ovennævnte udførelsesform er det ifølge opfindelsen hensigtsmæssigt, at det nævnte gasformige forbrændingsprodukt bringes i intim væske/gas-kontakt med en del af den med sulfit.berigede vandige hydrogensulfit-sulfit-opløsning fra trin c til dannelse af en med hydrogensulfit beriget opløsning indeholdende natriumhydrogensulfit og natriumsulfit og en gasformig effluent indeholdende nitrogen og carbondioxid, men i det væsentlige strippet for svovldioxid. Medens svovldioxidet absorberes og anvendes i systemet, hvorved der kan opnås en blanding indeholdende lige dele NaHSO^ og Na2S0^, kan der udsendes en uskadelig gasblanding bestående af nitrogen, carbondioxid, oxygen og vand, hvilket selvsagt er betydningsfuldt set fra et økologisk synspunkt. Idet den sidstnævnte gasblanding er ret rig på CC^, sender man dog almindeligvis ikke alt af den ud i atmosfæren, men genanvender ifølge opfindelsen hensigtsmæssigt carbondioxidet ved, at en del af den nævnte gasformige effluent indeholdende nitrogen og carbondioxid, men i det væsentlige strippet for svovldioxid, anvendes ved carboneringen af den nævnte første ludfraktion indeholdende natriumhydrogensulfid, natriumhydrogencarbonat og natriumcarbonat. Herved forbedres økonomien ligesom ved en yderligere hensigtsmæssig udførelsesform bestående i, at den nævnte med hydrogensulfit berigede vandige opløsning af natriumhydrogensulfit og natriumsulfit anvendes som opløsningen af natriumhydrogensulfit og natriumsulfit i trin c.In the above embodiment, it is preferred that the said gaseous combustion product be brought into intimate liquid / gas contact with a portion of the sulfite-enriched aqueous hydrogen sulfite-sulfite solution of step c to form a hydrogen-enriched-sulfur solution containing sodium hydrogen sulfite and sodium sulfite and a gaseous effluent containing nitrogen and carbon dioxide, but essentially stripped of sulfur dioxide. While the sulfur dioxide is absorbed and used in the system to obtain a mixture containing equal parts of NaHSO4 and Na2SO4, a harmless gas mixture of nitrogen, carbon dioxide, oxygen and water can be emitted, which is of course significant from an ecological point of view. However, since the latter gas mixture is quite rich in CC 2, not all of it is emitted into the atmosphere, but the carbon dioxide is appropriately recycled according to the invention in that a portion of said gaseous effluent containing nitrogen and carbon dioxide, but substantially stripped of sulfur dioxide, is used in the carbonation of said first liquor fraction containing sodium hydrogen sulfide, sodium bicarbonate and sodium carbonate. This improves the economy, as in a further convenient embodiment, in that the aqueous solution of sodium sulphite enriched with sodium sulphite and sodium sulphite is used as the solution of sodium hydrogen sulphite and sodium sulphite in step c.
Ifølge opfindelsen er det endvidere hensigtsmæssigt, at en del af den med sulfit berigede vandige hydrogensulfit-sulfit-opløsning fra trin c anvendes til absorption af svovldioxid fra røggasserne fra genvindingsovnen til fuldendelse af svovlgenvindingen i pulpnings- og genvindingssysternet. Den nødvendige yderligere mængde svovldioxid opnås herved på en måde, der indebærer yderligere økologiske fordele.Further, according to the invention, it is preferred that a portion of the sulfite-enriched aqueous hydrogen sulfite-sulfite solution from step c is used to absorb sulfur dioxide from the flue gases from the recovery furnace to complete the sulfur recovery in the pulping and recovery system. The required additional amount of sulfur dioxide is hereby obtained in a way which offers additional ecological benefits.
Hvad angår temperaturforholdene er det til opnåelse af en fordelagtig kom- 5 149784 bination af bekvem udførelse og god økonomi ifølge opfindelsen hensigtsmæssigt, at den nævnte precarbonering udføres ved en temperatur på ca. 50 til 70°C, og at carboneringen udføres ved en temperatur på ca. 60 til ca. 82°C,og endvidere, hvad angår trin c, at den nævnte forhøjede temperatur holdes på ca. 105 til ca. 115°C. Specielt fordelagtige er således de forholdsvis lave temperaturer ved precarbone-ringen og carboneringen.Concerning the temperature conditions, in order to obtain an advantageous combination of convenient embodiment and good economy according to the invention, it is desirable that said precarbonation be carried out at a temperature of approx. 50 to 70 ° C and that the carbonation is carried out at a temperature of approx. 60 to approx. 82 ° C, and furthermore, with respect to step c, the said elevated temperature is maintained at approx. 105 to approx. 115 ° C. Thus, particularly advantageous are the relatively low temperatures of the precarboning and carbonation.
En yderligere hensigtsmæssig udførelsesform for fremgangsmåden ifølge opfindelsen består i, at det i trin g frigjorte carbondioxid er hovedkilden til carbondioxid til carboneringen i trin b. Dette i sig selv og i kombination med de øvrige udførelsesformer bidrager til på enkel måde at bibringe systemet dets karakter af et uafhængigt system.A further convenient embodiment of the process according to the invention consists in that the carbon dioxide released in step g is the main source of carbon dioxide for the carbonation in step b. This in itself and in combination with the other embodiments contributes in a simple way to impart to the system its character of an independent system.
Opfindelsen belyses nærmere under henvisning til tegningen, hvorpå fig. 1 er et skematisk procesdiagram, der viser den generelle udførelse af fremgangsmåden ifølge opfindelsen, og fig. 2 er en mere detaljeret udgave af det i fig. 1 viste strømningsmønster.BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic process diagram showing the general embodiment of the method according to the invention; and FIG. 2 is a more detailed version of the embodiment of FIG. 1.
Der fremstilles en pulp under anvendelse af en kemikalieblanding indeholdende 18% natriumsulfit, 3 1/2% natriumsulfid, 3 1/2% natriumcarbonat og 2 1/2% indifferente stoffer (natriumsulfat og natriumthiosulfat), alt udtiykt som vægt-% natriumoxid beregnet på vægtmængden af træ i ovntør tilstand. Den brugte lud ini deholder ca. 58% uorganisk materiale og 42% organisk materiale og har en brutto-forbrændingsvarme på ca.9800 til'c'a. 10700 joule pr. gram sortlud-tørstof. Den brugte lud fjernes fra pulpen og opsamles ved hjælp af konventionelle metoder og koncentreres i multieffekt-inddampere til et totalt tørstofindhold på ca. 60%, hvorefter den brændes i en konventionel genvindingsovn af kraft-typen til opnåelse af røggasser indeholdende svovldioxid Og en smelte med omtrent følgende molære sammensætning: ^ 57%A pulp is prepared using a chemical mixture containing 18% sodium sulfite, 3 1/2% sodium sulfide, 3 1/2% sodium carbonate and 2 1/2% inert substances (sodium sulfate and sodium thiosulfate), all expressed as weight% sodium oxide calculated on weight weight of wood in oven-dry state. The used lye ini contains approx. 58% inorganic material and 42% organic material and has a gross combustion heat of about 9800 to'c'a. 10700 joules pr. grams of black liquor solids. The spent liquor is removed from the pulp and collected by conventional methods and concentrated in multi-effect evaporators to a total dry matter content of approx. 60%, after which it is burned in a conventional power-type recovery furnace to obtain flue gases containing sulfur dioxide And a melt of approximately the following molar composition: ^ 57%
Na2C03 40%Na2CO3 40%
Na2S04 3%Na 2 SO 4 3%
Ialt 100%Total 100%
For ca. 1000 ton pulp pr. dag indeholder røggasserne fra genvindingsovnen ca. 145 pound-mol svarende til ca. 4220 kg pr. time af S02· Et pound-mol defineres som •molekylvægten i pounds.For approx. 1000 tonnes of pulp per Today, the flue gases from the recycling oven contain approx. 145 pound moles corresponding to approx. 4220 kg per · One pound-mole is defined as • the molecular weight in pounds.
For 1000 ton pulp pr. dag dannes der ca. 20400 kg pr. tårne af smelte.For 1000 tonnes of pulp per day, approx. 20400 kg per towers of melt.
6 1497846 149784
Smelten opløses i vand til dannelse af en grønlud med en total natriumkoncentration på ca. 5 normal og klares ved konventionelle metoder til opnåelse af en klaret grønlud med en sammensætning svarende til: kg/time mol/timeThe melt is dissolved in water to form a green liquor with a total sodium concentration of approx. 5 is normal and cleared by conventional methods to obtain a clarified green liquor having a composition equal to: kg / hour mol / hour
Na2S 9700 274,2Na 2 S 9700 274.2
Na2C03 9800 203,8Na 2 CO 3 9800 203.8
Na2S2°3 1090 15,2Na2S2 ° 3 1090 15.2
Na2S04 1000 15,5Na2 SO4 1000 15.5
Talt 21590 508,7Counted 21590 508.7
De nye træk ved fremgangsmåden ifølge opfindelsen, anvendt ved behandling af en sådan lud, belyses tydeligere på fig. 2, der dækker viderebehandlingen af den klarede smelteopløsning fra ca. 1000 ton pr. dag af pulp. Hvis det ønskes kun at behandle en del af den klarede grønlud, kan strømmene selvsagt formindskes og indstilles svarende héi'til. Den klarede grønlud pumpes og afmåles ved hjælp af konventionelle midler gennem en ledning 1 i en reguleret mængde på ca. 1500 til ca. 1900 liter pr.minut til et preabsorptionstårn 2, hvori den efter modstrømsprincippet bringes i kontakt med gasser indeholdende både hydrogensulfid og carbondioxid, som drives ved hjælp af en blæser 18 gennem en ledning 17 fra toppen af et reaktionstårn 5. Preabsorptionstårnet er hensigtsmæssigt eh klokkebunds- eller sibundskolonne, men der kan dog også anvendes en passende pakket kolonne. Udtrykt i mol pr. time svarer det totale kemikalieindhold i grønluden, der træder ind i precarboneringstårnet, omtrent til det ovenfor angivne. Desuden indeholder grønr luden ca. 91800 kg vand pr. time for ialt ca. 113400 kg pr. time af grønlud.The new features of the method according to the invention used in the treatment of such a lye are illustrated more clearly in FIG. 2, which covers further processing of the clarified melt solution from ca. 1000 tons per day of pulp. If it is desired to treat only part of the clarified green liquor, the currents can of course be reduced and adjusted accordingly. The clarified green liquor is pumped and measured by conventional means through a conduit 1 in a controlled amount of approx. 1500 to approx. 1900 liters per minute to a preabsorption tower 2 in which it is contacted by gases containing both hydrogen sulfide and carbon dioxide, which are driven by a blower 18 through a conduit 17 from the top of a reaction tower 5. According to the countercurrent principle, the preabsorption tower is suitably an or sibund column, but an appropriately packed column can also be used. Expressed in moles per per hour, the total chemical content of the green liquor entering the precarbonation tower corresponds approximately to the above. In addition, the green lute contains approx. 91800 kg of water per hour for a total of approx. 113400 kg per hour of green liquor.
Luden fra precarboneringståmet 2 har ved en temperatur på ca. 71°C en aktiv kemikaliesammensætning svarende til følgende omtrentlige kemikaliestrømningshastighed:The liquor from the precarbonation frame 2 has a temperature of approx. 71 ° C an active chemical composition corresponding to the following approximate chemical flow rate:
Mol/timeMol / hr
NaHS 397NaHS 397
NaHC03 203NaHCO3 203
Na2C03 178Na 2 CO 3 178
Luden fra preabsorptionstårnet 2 . pumpes ved hjælp af en pumpe 3 gennem en ledning 4 til toppen af reaktionstårnet 5, som i det væsentlige består af en klokkebundskolonne af kendt udformning, sådan som den er velkendt i jordolieindustrien, med passende åbninger og forbindelser til gas og væsker som vist i fig. 2. Efterhånden som luden strømmer nedad fra bund til bund gennem denne kolonne, strippes dens sulfidindhold fra som hydrogensulfid af de opadstigende gasser i kolonnen, medens den samtidig absorberer carbondioxidet fra disse gasser, således at den på det tidspunkt, hvor luden når den nedre del af kolonnen svarende til 7 149784 indgangsstedet for en ledning 16, har en aktiv kemikaliesammensætning svarende omtrent til følgende kemikaliestrømningshastighed:The sound of the preabsorption tower 2. is pumped by means of a pump 3 through a conduit 4 to the top of the reaction tower 5, consisting essentially of a bell bottom column of known design, as is well known in the petroleum industry, with suitable openings and connections for gas and liquids as shown in FIG. . 2. As the liquor flows downward from bottom to bottom through this column, its sulfide content is stripped off as hydrogen sulfide by the rising gases in the column while simultaneously absorbing the carbon dioxide from these gases so that at the time the liquor reaches the lower portion. of the column corresponding to the entry point of a conduit 16, has an active chemical composition approximately equal to the following chemical flow rate:
Mol/timeMol / hr
NaHCOg 346NaHCO3 346
Na2C03 305Na 2 CO 3 305
En lud indeholdende ca. 1900 til ca. 2000 mol aktivt Na20 pr. time med ca. 50% i form af natriumsulfit og 50% i form af natriumhydrogensulfit indføres gennem ledningen 16 i kolonnen 5 og blandes med den fra toppen af kolonnen nedadstrøm-mende lud. I den nedre del af kolonnen, under indgangsstedet for ledningen 16, reagerer disse lude til dannelse af en blandet opløsning indeholdende ca. 2400 til ca. 2500 mol pr. time af aktivt Na^O, primært i form af natriumsulfit, medens den nedadstrømmende luds carbonatindhold uddrives som carbondioxid i denne decar-boneringsdel af tårnet 5.A lye containing approx. 1900 to ca. 2000 moles of active Na 2 hour by approx. 50% in the form of sodium sulfite and 50% in the form of sodium hydrogen sulfite are introduced through conduit 16 in column 5 and mixed with the liquor flowing down from the top of the column. In the lower part of the column, below the entry point of the conduit 16, these lids react to form a mixed solution containing approx. 2400 to approx. 2500 moles per hour of active Na 2 O, primarily in the form of sodium sulphite, while the carbonate content of the downstream liquor is expelled as carbon dioxide in this decarbonation portion of the tower 5.
Til fremskyndelse af denne decarboneringsreaktion opvarmes de blandede lude til kogepunktet ved varmeudveksling med vanddamp i en varmeudveksler 6. Det blandede ludprodukt punpes ved ca. 105 til ca. 115°C ved hjælp af en pumpe 7 gennem en ledning 8 til en varmeudveksler 9 og passerer gennem varmeudveksle-ren 9 i modstrøm mod sulfit-hydrogensulfit-luden, som træder ind i reaktionstårnet 5 gennem ledningen 16, for at bevare varmen og foropvarmer denne ludstrøm.To speed up this decarboning reaction, the mixed liquor is heated to the boiling point by heat exchange with water vapor in a heat exchanger 6. The mixed liquor product is punctured at ca. 105 to approx. 115 ° C by means of a pump 7 through a conduit 8 to a heat exchanger 9 and passing through the heat exchanger 9 countercurrent to the sulphite-hydrogen sulphite liquor entering the reaction tower 5 through conduit 16 to retain heat and preheat it. ludstrøm.
En delmængde af ludproduktet svarende til den oprindeligt tilførte mængde opløsning aftages som en opløsning af hovedsageligt natriumsulfit gennem en ledning 10 til anvendelse ved fremstilling af frisk kogelud til pulpning. Størstedelen af luden fra bunden af reaktionstårnet strømmer efter passage af varmeudvek-sleren 9 gennem en ledning 11 for at blive sulfiteret. En del af eller fortrinsvis al denne lud anvendes først til skrubning af røggasserne fra genvindingsovnen til absorbering og genvinding af SC^-indholdet. Dette udføres i konventionelt apparatur, som er udformet til skrubning af sådanne ovnrøggasser til genvinding af SO^ og til undgåelse af luftforurening. Disse lude, der nu har fået forøget SOj-indholdet, sendes tilbage gennem en ledning 12 og sulfiteres yderligere i et hydrogensulfit-tårn 13 med gasser, der træ ifør ind gennem en ledning 36 fra en hydrogensulfidovn 27, til opnåelse af det ønskede forhold mellem natriumsulfit og natriumhydrogensulfit til indføring i reaktionstårnet 5. Disse lude pumpes fra hydrogensulf ittårnet 13 ved hjælp af en pumpe 14 gennem en ledning 15, gennem varme-udveksleren 9 og gennem ledningen 16 til reaktionstårnet 5.A subset of the lye product corresponding to the initially applied amount of solution is taken off as a solution of mainly sodium sulfite through a conduit 10 for use in preparing fresh pulp liquor for pulping. The majority of the liquor from the bottom of the reaction tower flows after passing the heat exchanger 9 through a conduit 11 to be sulfitated. Some or preferably all of this liquor is first used for scrubbing the flue gases from the recovery furnace to absorb and recover the SC 2 content. This is done in conventional apparatus designed to scrub such furnace flue gases to recover SO 2 and to avoid air pollution. These lobes, which have now increased SO₂ content, are sent back through line 12 and further sulfated in a hydrogen sulfite tower 13 with gases entering through a line 36 from a hydrogen sulfide furnace 27 to obtain the desired ratio of sodium sulphite and sodium hydrogen sulphite for introduction into the reaction tower 5. These valves are pumped from the hydrogen sulphite tower 13 by means of a pump 14 through a conduit 15, through the heat exchanger 9 and through the conduit 16 to the reaction tower 5.
Gasserne fra toppen af reaktionstårnet 5 deles op i to strømme, med en temperatur på ca. 60 til ca.70°C, afhængig af det tryk, ved hvilket tårnet drives.The gases from the top of the reaction tower 5 are divided into two streams, with a temperature of approx. 60 to about 70 ° C, depending on the pressure at which the tower is operated.
En af disse strømme, der omtrent har følgende sammensætning udtrykt i mol pr. time: 8 149784One of these streams having approximately the following composition expressed in moles per hour: 8 149784
Mol/time N2 624 C02 218 H2S 122 02 8 H2° 324Mol / hour N2 624 C02 218 H2S 122 02 8 H2 ° 324
Ialt 1.296 føres gennem ledningen 17 og gennem blæseren 18 ind i preabsorptionstårnet 2.A total of 1,296 is passed through line 17 and through fan 18 into the preabsorption tower 2.
I dette tårn genabsorberes i det væsentlige alt hydrogensulfidet og det meste af carbondioxidet i den klarede grønlud} der indføres gennem ledningen 1. Restgassen fra preabsorptionstårnet 2, med en temperatur på ca. 50 til ca. 70°C afhængig af temperaturen af den indkommende grønlud, kan sendes ud i atmosfæren under normale driftsbetingelser, men den kan også skrubbes yderligere med supplerende natrium-carbonat eller natriumhydroxid i en yderligere skrubningsenhed (ikke vist) til sikring af, at der ikke sendes noget hydrogensulfid ud i atmosfæren, navnlig under eventuelle· driftsforstyrrelser. Alternativt kan sådanne gasser recirkulerestil reaktionstårnet 5. En anden del af gasserne fra toppen af reaktionstårnet 5, svarende i dette eksempel"til en strømningshastighed som følger:In this tower, substantially all of the hydrogen sulphide and most of the carbon dioxide in the clarified green liquor introduced through the conduit is absorbed 1. The residual gas from the pre-absorption tower 2, at a temperature of approx. 50 to approx. 70 ° C, depending on the temperature of the incoming green liquor, can be emitted into the atmosphere under normal operating conditions, but it can also be further scrubbed with supplemental sodium carbonate or sodium hydroxide in an additional scrubber unit (not shown) to ensure that no hydrogen sulfide into the atmosphere, especially during any · operating disturbances. Alternatively, such gases may recycle to the reaction tower 5. Another portion of the gases from the top of the reaction tower 5, corresponding in this example "to a flow rate as follows:
Mol/time N2 1.411 C02 494 H2S 275 02 18 H2° 733Mol / hour N2 1.411 C02 494 H2S 275 02 18 H2 ° 733
Ialt 2.931 udtages gennem en ledning 20 til en varmeudveksler 21, hvori gasserne afkøles ved hjælp af kølevand, der indføres ved 22. Kondensatet fra gasserne udtages gennem en ledning 23 og kan udledes som spildevand, men det sendes fortrinsvis tilbage til smelteopløsningssystemet og anvendes ved fremstilling af grønluden, eller det kan indføres på ethvert egnet sted i preabsorptionstårnet 2. De afkølede gasser med et lavere fugtighedsindhold føres fra varmeudveksleren 21 gennem en ledning 24 til en foropvarmer 25, som opvarmer dem over dugpunktet, og derefter til en blæser 26, som tjener til at trække disse gasser gennem reaktionstårnet og køleren og tilføre dem til hydrogensulfidovnen 27. Der trækkes luft ind i hydrogensulfidovnen gennem åbninger ved 28, og desuden opretholdes der en tændflamme ved hjælp af olie eller naturgas, der indføres gennem en ledning 29, for at sikre antænding af hydrogensulfidet. Tændbrænderen anvendes også til foropvarmning af ovnen og til 9 149784 at sikre opretholdelsen af en tilstrækkelig temperatur indei-i ovnen, således at forbrændingen af hydrogensulfidet er fuldstændig selv under unormale driftsbetingelser. Svovl i en tilstrækkelig mængde til erstatning af svovltabene i pulpnings-og genvindingssystemet kan også indføres i H^S-ovnen til forbrænding til dannelse af svovldioxid og til opnåelse af de ønskede omdannelser til sulfit i tårnet 13. Efter ovnsektionen 27 afkøles gasserne fra hydrogensulfidforbrændingen, og der produceres vanddamp ud fra kedelfødevand, som indføres gennem en ledning 30 og.· ledes gennem en foropvarmer 31 til en kedelsektion 32 og gennem en overheder 33. Vanddampene aftages gennem en ledning 34. De afkølede gasser fra H^S-forbrænd ingen, der har en sammensætning svarende omtrent til en strømningshastighed på:A total of 2,931 is taken out through a conduit 20 to a heat exchanger 21 wherein the gases are cooled by cooling water introduced at 22. The condensate from the gases is taken out through a conduit 23 and may be discharged as wastewater, but it is preferably sent back to the melt solution system and used in preparation. of the green liquor or it can be introduced at any suitable location in the preabsorption tower 2. The cooled gases having a lower moisture content are passed from the heat exchanger 21 through a conduit 24 to a preheater 25 which heats them above the dew point, and then to a fan 26 which serves. to draw these gases through the reaction tower and cooler and supply them to the hydrogen sulphide furnace 27. Air is drawn into the hydrogen sulphide furnace through openings at 28, and in addition, an ignition flame is maintained by oil or natural gas introduced through a conduit 29 to ensure ignition of the hydrogen sulfide. The ignition burner is also used for preheating the furnace and for maintaining a sufficient temperature inside the furnace so that the combustion of the hydrogen sulfide is complete even under abnormal operating conditions. Sulfur in a sufficient amount to replace the sulfur losses in the pulping and recovery system may also be introduced into the H 2 S furnace for combustion to generate sulfur dioxide and to achieve the desired sulfite conversion in tower 13. After furnace section 27, the gases are cooled from hydrogen sulfide combustion. and water vapor is produced from boiler feed water introduced through a conduit 30 and. · is passed through a preheater 31 to a boiler section 32 and through a superheater 33. The steams are taken off through a conduit 34. The cooled gases from H having a composition approximately equal to a flow rate of:
Mol/time N2 3.040 C02 494 S02 275 02 38 H2° 675Mol / hour N2 3.040 C02 494 S02 275 02 38 H2 ° 675
Ialt 4.522 udtages fra ovnen ved hjælp af en blæser 35 og føres gennem ledningen 36 ind i hydrogensulfittårnet 13, hvor S02 absorberes. Gasstrømmen fra hydrogensulfit«. tårnet opdeles i to dele, hvoraf ca. en trediedel af den totale strøm udtømmes gennem en ledning 37 til atmosfæren, medens de resterende to trediedele, svarende til en strømningshastighed på ca.:A total of 4,522 is removed from the furnace by means of a fan 35 and passed through conduit 36 into the hydrogen sulfite tower 13 where SO2 is absorbed. The gas flow from hydrogen sulfite '. the tower is divided into two parts, of which approx. a third of the total current is discharged through a conduit 37 to the atmosphere, while the remaining two thirds, corresponding to a flow rate of about:
Mol/time N2 2.035 C02 331 02 25 H2° 584Mol / hour N2 2.035 C02 331 02 25 H2 ° 584
Ialt 2.975 indføres gennem en ledning 38 i den nedre del af reaktionstårnet 5. Gasserne fra ledningen 38 med det carbondioxid, der frigøres i den nedre decarbonerings-sektion af reaktionstårnet 5, stiger opad i modstrøm mod ludstrømmen gennem reaktionstårnet, stripper i det væsentlige alt hydrogensulfidet fra den nedad-strømraende lud og afgiver en del af deres carbondioxid til den nedadstrømmende lud til opnåelse af de anførte lud- og gassammensætninger.A total of 2,975 is introduced through a conduit 38 into the lower portion of the reaction tower 5. The gases from conduit 38 with the carbon dioxide released in the lower decarbonation section of the reaction tower 5 rise upwardly in countercurrent flow through the reaction tower, essentially stripping all of the hydrogen sulfide. from the downstream liquor and emit a portion of their carbon dioxide to the downstream liquor to obtain the listed liquor and gas compositions.
Sammenfattende kan det anføres, at sulfidet i grønluden omdannes først til hydrogensulfid og derefter til S02> som absorberes i en opløsning af natriumsul-In summary, it can be stated that the sulphide in the green liquor is first converted to hydrogen sulphide and then to SO 2 which is absorbed in a solution of sodium sulphide.
Claims (9)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US24636772A | 1972-04-21 | 1972-04-21 | |
| US24636772 | 1972-04-21 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| DK149784B true DK149784B (en) | 1986-09-29 |
| DK149784C DK149784C (en) | 1987-02-16 |
Family
ID=22930369
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| DK212673A DK149784C (en) | 1972-04-21 | 1973-04-17 | PROCEDURE FOR RECOVERING CHEMICALS FROM USED SODIUM BASE SULPHITE LIQUID |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5330801B2 (en) |
| CA (1) | CA988662A (en) |
| DK (1) | DK149784C (en) |
| FI (1) | FI55367B (en) |
| NO (1) | NO143754C (en) |
| SE (1) | SE386923B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI92726C (en) * | 1991-12-02 | 1994-12-27 | Ahlstroem Oy | Method and apparatus for recovering sulfur dioxide from the chemical cycle of a sulphate pulp mill |
| JP6569865B2 (en) * | 2016-02-29 | 2019-09-04 | 三菱重工業株式会社 | Solid state laser equipment |
| JP7341673B2 (en) | 2019-02-27 | 2023-09-11 | 三菱重工業株式会社 | laser equipment |
-
1973
- 1973-03-19 SE SE7303781A patent/SE386923B/en unknown
- 1973-03-26 NO NO1244/73A patent/NO143754C/en unknown
- 1973-03-26 FI FI928/73A patent/FI55367B/en active
- 1973-04-10 CA CA168,346A patent/CA988662A/en not_active Expired
- 1973-04-17 DK DK212673A patent/DK149784C/en active
- 1973-04-20 JP JP4423673A patent/JPS5330801B2/ja not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FI55367B (en) | 1979-03-30 |
| JPS4920402A (en) | 1974-02-22 |
| NO143754B (en) | 1980-12-29 |
| SE386923B (en) | 1976-08-23 |
| DK149784C (en) | 1987-02-16 |
| JPS5330801B2 (en) | 1978-08-29 |
| CA988662A (en) | 1976-05-11 |
| NO143754C (en) | 1981-04-08 |
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