US3428107A - Method in evaporation of waste liquor discharged from continuously operating cellulose digester or boiler - Google Patents

Method in evaporation of waste liquor discharged from continuously operating cellulose digester or boiler Download PDF

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Publication number
US3428107A
US3428107A US571313A US3428107DA US3428107A US 3428107 A US3428107 A US 3428107A US 571313 A US571313 A US 571313A US 3428107D A US3428107D A US 3428107DA US 3428107 A US3428107 A US 3428107A
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stage
vapor
liquor
expansion
heating
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US571313A
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English (en)
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Erik Hugo Backteman
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Rosenblads Patenter AB
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Rosenblads Patenter AB
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/06—Flash distillation
    • B01D3/065—Multiple-effect flash distillation (more than two traps)
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D1/00—Evaporating
    • B01D1/26—Multiple-effect evaporating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/06—Flash distillation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S159/00—Concentrating evaporators
    • Y10S159/08—Multieffect or multistage

Definitions

  • the method relates to evaporation of waste liquor or lye discharged from a continuously operating cellulose digester or boiler which operates at high pressure and at high temperature, i.e. the liquor being in the state in which it leaves the digester after completion of the pulping process. More particularly the method relates to the case, in which the liquor after pre-evaporation according to the flash-expansion principle will be evaporated further in an indirect evaporator of multiple effect type.
  • the liquor which for example can be obtained at a pressure of about 8 atmospheres superatmospheric pressure and at a temperature of about 170 C.
  • the liquor will first be subjected to a preliminary evaporation by reduction of the pressure in two successive expansion stages, to the effect that in the first stage liquor vapor of a temperature of about 140 C. suitable ⁇ for alkalinization of the digester Chips will be obtained and utilized for this purpose.
  • the pressure will be reduced further, so that the lye will get a temperature of for example about 100 C., which is considered to be a suitable temperature for storage as well as a suitable supply temperature for the final evaporation process, the lye vapor produced, having a corresponding temperature, being withdrawn through a condenser.
  • the nal evaporation process is effected in an indirect multiple stage evaporator, which in its first stage is heated by freshly generated steam and in each one of its subsequent stages is heated by lye vapor from an immediately preceding heating stage.
  • the invention aims at effecting such cooperation between the pre-evaporation of the multi-ple expansion stage type and subsequent evaporation stages, that all vapor liberated in the pre-evaporation during the expansion stages following upon the first stage of evaporation will ybe utilized as heating vapor during subsequent evaporating operations in a most eicient manner in order to reduce the need for freshly generated steam, while the vapor from the first evaporation stage can be utilized separately, for example for the alkalinization mentioned and/ or for other purpose.
  • the invention is primarily characterized by the fact that the lye Ivapor or liquor vapor formed is conducted as an additional heating vapor from each expansion stage, with the exception of the first one, to the said heating stage according to the rule: from the second expansion stage to the second heating stage etc. in turn to the extent that there are any further expansion stages and ICC heating stages, the last expansion stage, which Supplies the pre-evaporated liquor to some of the heating stages of the multiple evaporator except the last one being adapted to supply additional heating vapor to the next following heating stage.
  • FIGS. l and 2 respectively each illustrate in the form of a flow diagram a modification of an evaporation installation for performing the method according to the invention
  • FIG. 3 illustrates part of the installation according to FIG. 2.
  • FIG. 1 the liquor from the digester (not shown in the figure) flows through the intake conduit 5 and the connecting conduits 6, 7, 8 and 9 and through expansion vessels 1, 2, 3 and 4 in the sequence now stated.
  • I, II, III, IV and V are the different heating stages of an indirect multiple stage evaporator of substantially conventional design, through the liquor chambers of which the liquor flows from the last expansion vessel 4 in the sequence III, W, V, I and Il through the connecting conduits 9, 10, 11 and 12, the circulation pump 13, the connecting conduits 14 and 15, and the discharge conduit 16.
  • Stage I will hereby be fed with freshly generated vapor or steam as heating medium through conduit 17, while the subsequent stages II, III, IV and V are supplied with liquor vapor as heating medium from the immediately next preceding stage through the vapor conduits 18, 1.9, 20 and 21 respectively; the liquor vapor from stage V being withdrawn to a condenser (not shown in the figure) through the conduit 22.
  • the hot liquor from the digester on passing through the expansion vessels will supply vapor under stepwise reduction of pressure, this vapor serving as additional heating vapor and being discharged from the expansion stages 2, 3 and 4 through the conduits 23, 24 and 25 respectively, to the heating stage Il, to the heating stage III, and to the heating stage 1V, whereby the liquor thus pre-evaporated will be conducted through the connecting conduit 9 to the liquor chamber or space of heating stage III at least approximately at the pressure and temperature conditions prevailing in that chamber.
  • the steam consumption will be about 150 ⁇ kilos per 1000 kilos evaporated water, while a conventional -stage evaporator consumes approximately 250 kilos of steam for the same amount of evaporation. If combined with preevaporation in two stages of expansion and condensation of the thereby produced vapor in accordance with the known method indicated above, only a very modest improvement can be obtained, viz. a'bout 220 kilos per 1000 kilos of evaporated water. Thus, the improvement of the steam economy achieved by means of the invention is important.
  • the installation according to FdG. 2 differs from that according to FIG. 1 only insofar as the expansion vessels 2, 3 and 4 according to FIG. 1 have been replaced Iby expansion chambers 2a, 3a and 4a in the steam and liquid separators 35, 36 and 37 respectively of the heating stages I, I-I and III, most clearly illustrated in FIG. 3, so that the previously used steam conduits 23, 24 and 2S could be omitted.
  • the separator for example 35 in the heating stage lI, is separated into a separator chamber 40 below the bottom and the expansion chamber 2a above the same.
  • a separator chamber 40 below the bottom and the expansion chamber 2a above the same.
  • vapor and liquor from the liquor and vapor mixture produced during the beating stage are separated from each other, the liquor being withdrawn through the conduit and the vapor being discharged through the vapor piping 39, the expansion chamber 2a and the conduit 118 to the next heati-ng stage II.
  • the liquor from the first expansion stage is introduced tangentially into the expansion chamber through the conduit 6, so as to be separated by the centrifugal force from the thereby produced vapor, and collected at the bottom 38 about the vapor piping 39, from where it is discharged through the conduit 7 to the next expansion chamber 3a.
  • the vapor produced is simultaneously mixed with the through-flowing vapor from the separator chamber, and will 'be entrained to the next heating stage II as additional heating vapor.
  • the processes are analogical in the two subsequent stages 3a, II and 4a, II I.
  • the liquid llow direction III-'lV-V-I--II illustrated is most frequently used in S-stage evaporators, in first line because the liquor, on account of its viscosity increasing vwith the increasing concentration, preferably should be finally evaporated at a high temperature, which however should not be permitted to rise above about C., that is to say the highest temperature at which the liquor can be storaged at atmospheric pressure. Suc'h a temperature of the liquor will generally be found in stage II, which in consequence then should constitute the final stage, whereby the aforesaid liquor flow conduction will be the most convenient one.
  • the liquor should be fed to a multiple stage evaporator at a temperature, which at least not substantially is lower than the digesting teruperature in the heating stage to which it is supplied.
  • the pre-evaporated liquor, fed to the heating stage III should have 'a temperature in the proximity of the digesting temperature in this stage, which it will acquire in the last expansion vessel 4 because the latter, which supplies additional vapor to the next following heating stage IV, thereby also is subjected to a pressure approximately equal to the pressure prevailing in the liquor chamber of the heating stage III.
  • the number may be increased to tive, if stage IV is permitted to constitute a supplying step, resulting in still further reduction of the steam consumption.
  • a further increase of the number of stages does not result in any additional advantage, because an arrangement wherein stage V is a feeding step and a further expansion stage is included would cause that the vapor from the latter stage would ow to the discharge 22 directly.
  • moving the intake to a stage operating at a higher temperature would cause a reduction of the number of such expansion stages, for example to three stages on feeding in at stage II, whereby obviously also another heating stage has to constitute the final step.
  • the invention restricted to the case in which the vapor from the first expansion stage to some extent is utilized for steaming the chips but this vapor can also be used for other purposes.
  • the vapor will for example contain turpentine, which should be recuperated.
  • the vapor may conveniently be conducted in its entirety to a so called turpentine condenser. I-n this case the preheater 27 may possibly serve such purpose.

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  • Chemical Kinetics & Catalysis (AREA)
  • Paper (AREA)
  • Nonmetallic Welding Materials (AREA)
US571313A 1965-08-19 1966-08-09 Method in evaporation of waste liquor discharged from continuously operating cellulose digester or boiler Expired - Lifetime US3428107A (en)

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SE1085165 1965-08-19

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US (1) US3428107A (en, 2012)
AT (1) AT262047B (en, 2012)
DE (1) DE1692824C3 (en, 2012)
FI (1) FI45474C (en, 2012)
NO (1) NO119205B (en, 2012)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3839160A (en) * 1972-06-23 1974-10-01 Hitachi Ltd Multiple effect evaporator
US3926739A (en) * 1973-08-15 1975-12-16 Hitachi Ltd Multiple-effect multi-stage flash evaporation process and apparatus for demineralizing water
FR2368669A1 (fr) * 1976-10-25 1978-05-19 Wiegand Karlsruhe Gmbh Procede et dispositif pour echauffer un fluide en circulation dans une installation destinee a vaporiser et secher un produit
US4132588A (en) * 1976-02-06 1979-01-02 Asahi Kasei Kogyo Kabushiki Kaisha Concentration process by multistage, multiple effect evaporator
EP0072045A1 (de) * 1981-08-04 1983-02-16 Metallgesellschaft Ag Verfahren zur Konzentration von Schlempen
EP0078531A3 (en) * 1981-11-04 1984-05-09 Hoechst Aktiengesellschaft Method for the continuous rectification of an alcohol-containing liquid mixture
US4687546A (en) * 1985-07-19 1987-08-18 Georgia Kaolin Company, Inc. Method of concentrating slurried kaolin
US5112441A (en) * 1985-04-25 1992-05-12 Oy Tampella Ab Process for the recovery of heat and chemicals from spent liquor
WO1993012854A1 (en) * 1991-12-31 1993-07-08 Comalco Aluminium Limited Evaporative concentration of clay slurries

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4953607A (en) * 1989-02-17 1990-09-04 A. Ahlstrom Multistage evaporating system

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR709044A (fr) * 1930-01-02 1931-08-01 Procédé et appareil pour récupérer les éléments volatifs des solutions destinées à être évaporées
US2544885A (en) * 1946-02-27 1951-03-13 Gen Am Transport Vertical tube evaporator
US2651356A (en) * 1948-08-25 1953-09-08 Henry M Hunter Apparatus for evaporation
US3021265A (en) * 1957-07-05 1962-02-13 Chicago Bridge & Iron Co Multiple effect evaporating system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR709044A (fr) * 1930-01-02 1931-08-01 Procédé et appareil pour récupérer les éléments volatifs des solutions destinées à être évaporées
US2544885A (en) * 1946-02-27 1951-03-13 Gen Am Transport Vertical tube evaporator
US2651356A (en) * 1948-08-25 1953-09-08 Henry M Hunter Apparatus for evaporation
US3021265A (en) * 1957-07-05 1962-02-13 Chicago Bridge & Iron Co Multiple effect evaporating system

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3839160A (en) * 1972-06-23 1974-10-01 Hitachi Ltd Multiple effect evaporator
US3926739A (en) * 1973-08-15 1975-12-16 Hitachi Ltd Multiple-effect multi-stage flash evaporation process and apparatus for demineralizing water
US4132588A (en) * 1976-02-06 1979-01-02 Asahi Kasei Kogyo Kabushiki Kaisha Concentration process by multistage, multiple effect evaporator
FR2368669A1 (fr) * 1976-10-25 1978-05-19 Wiegand Karlsruhe Gmbh Procede et dispositif pour echauffer un fluide en circulation dans une installation destinee a vaporiser et secher un produit
US4239588A (en) * 1976-10-25 1980-12-16 Wiegand Karlsruhe Gmbh Method of effectively utilizing thermal energy in spray drying
EP0072045A1 (de) * 1981-08-04 1983-02-16 Metallgesellschaft Ag Verfahren zur Konzentration von Schlempen
EP0078531A3 (en) * 1981-11-04 1984-05-09 Hoechst Aktiengesellschaft Method for the continuous rectification of an alcohol-containing liquid mixture
US4511437A (en) * 1981-11-04 1985-04-16 Hoechst Aktiengesellschaft Process for the continuous rectification of alcoholic fermates
US5112441A (en) * 1985-04-25 1992-05-12 Oy Tampella Ab Process for the recovery of heat and chemicals from spent liquor
US4687546A (en) * 1985-07-19 1987-08-18 Georgia Kaolin Company, Inc. Method of concentrating slurried kaolin
WO1993012854A1 (en) * 1991-12-31 1993-07-08 Comalco Aluminium Limited Evaporative concentration of clay slurries
US5730836A (en) * 1991-12-31 1998-03-24 Comalco Aluminium Limited Evaporative concentration of clay slurries

Also Published As

Publication number Publication date
AT262047B (de) 1968-05-27
FI45474C (fi) 1972-06-12
DE1692824C3 (de) 1975-12-11
DE1692824B2 (de) 1975-04-30
NO119205B (en, 2012) 1970-04-06
DE1692824A1 (de) 1971-09-30
FI45474B (en, 2012) 1972-02-29

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