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WO1998048102A1 - Separation des metaux alcalins d'une liqueur noire gazeifiee - Google Patents

Separation des metaux alcalins d'une liqueur noire gazeifiee Download PDF

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Publication number
WO1998048102A1
WO1998048102A1 PCT/SE1998/000637 SE9800637W WO9848102A1 WO 1998048102 A1 WO1998048102 A1 WO 1998048102A1 SE 9800637 W SE9800637 W SE 9800637W WO 9848102 A1 WO9848102 A1 WO 9848102A1
Authority
WO
WIPO (PCT)
Prior art keywords
process according
cooling medium
gas
gasifier
tube
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.)
Ceased
Application number
PCT/SE1998/000637
Other languages
English (en)
Inventor
Bengt Nilsson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Metso Fiber Karlstad AB
Original Assignee
Kvaerner Pulping AB
Kvaerner Pulping Technologies AB
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Kvaerner Pulping AB, Kvaerner Pulping Technologies AB filed Critical Kvaerner Pulping AB
Priority to DE69839182T priority Critical patent/DE69839182T2/de
Priority to EP98919692A priority patent/EP0977919B1/fr
Priority to US09/096,506 priority patent/US6062547A/en
Publication of WO1998048102A1 publication Critical patent/WO1998048102A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • D21C11/12—Combustion of pulp liquors
    • D21C11/125—Decomposition of the pulp liquors in reducing atmosphere or in the absence of oxidants, i.e. gasification or pyrolysis
    • 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
    • D21C11/06—Treatment of pulp gases; Recovery of the heat content of the gases; Treatment of gases arising from various sources in pulp and paper mills; Regeneration of gaseous SO2, e.g. arising from liquors containing sulfur compounds
    • D21C11/063—Treatment of gas streams comprising solid matter, e.g. the ashes resulting from the combustion of black liquor
    • D21C11/066—Separation of solid compounds from these gases; further treatment of recovered products

Definitions

  • the present invention relates to a process for recovering of chemicals and energy from spent liquors which are obtained during pulp production by means of chemical deligmfication of fibre raw material.
  • the invention particularly relates to a process for separating alkali metal salts from gasified black liquor.
  • a spent liquor generally termed black liquor
  • black liquor which contains organic material and the residual chemicals which have been used when cooking the fibre raw material.
  • this black liquor is evaporated and conveyed to a separate process for recovering of the energy content of the organic material and recovering the cooking chemicals as so-called green liquor.
  • Tomlinson process has been the commercially dominant method used for this recovery of energy and chemicals.
  • a disadvantage of this process which is now very old, is that it requires very large combustion ovens which are complicated both from the technical point of view and as regards their operation.
  • Swedish patent SE 448,173 describes a more recent process which, besides requiring process equipment which is appreciably simplified, achieves an improved recovery of both energy and chemicals.
  • This process is based on a pyrolysis reaction in which the black liquor is gasified in a reactor, resulting in the formation of an en- ergy-rich gas, principally comprising carbon monoxide, carbon dioxide, methane, hydrogen and hydrogen sulphide, and of inorganic chemicals in the form of small drops of smelt, principally comprising sodium carbonate, sodium hydroxide and sodium sulphide.
  • the resulting mixture of gas and smelt drops is rapidly cooled, in a first stage, by means of direct contact with a cooling liquid consisting of water and green liquor, which is formed when the smelt chemicals dissolve in the cooling li- quid.
  • the gas is subsequently washed, in a second stage, in a gas-washing apparatus of the scrubber type.
  • the gas is then used as a fuel for generating steam and/or electric power.
  • the physical calorific value of the gas can also be utilized when the gas is cooled down from the gasification temperature to the saturation temperature for aqueous steam at the selected pressure.
  • conesponding to 40 bar for example, steam having a pressure of 3-8 bar can be generated when the green liquor is cooled and when the gas is cooled and its water content is condensed downstream of the gas-washing tower.
  • Figure 1 shows a prefened embodiment of the concept according to the invention.
  • Figure 2 is a simplified sketch illustrating the need of causticizing the salts of green liquor produced by gasifying spent liquor as a function of the degree of superheating in the zone where the salt particles are separated from the gaseous compounds in the gasifier product.
  • receiving liquor relates to an aqueous liquid com- prising alkali metal salts, such as green liquor or white liquor.
  • cooling medium relates to steam and/or an aqueous liquid substantially free from alkali metal ions, such as a condensate from a counter- current condensor or a sulphur-containing condensate from evaporation of spent liquor.
  • alkali metal ions such as a condensate from a counter- current condensor or a sulphur-containing condensate from evaporation of spent liquor.
  • steam is prefened.
  • washing liquid relates to an aqueous liquid which preferably comprises a condensate from indirect cooling.
  • quench vessel relates to a vessel containing the receiving liquor.
  • the quench vessel is ananged in such a way that salt particles solidifying or close to solidifying as a result of injection of cooling medium in the stream from the gasifier, can be separated and dissolved in the receiving liquor.
  • gasifier product relates to the hot mixture of gases and salt smelt that enters the down-coming tube from the gasifier.
  • the term "superheated gas” relates to a gaseous mixture containing steam and does not contain any condensed water, i.e. steam of a certain pressure which is heated above the condensation/boiling temperature of that pressure.
  • alkali is partly converted to alkali hydrogen carbonate, which is a highly undesirable compound in green liquor as it puts an extra load on the causticizing system. Twice as much lime is needed for conversion of alkali hydrogen carbonate to hydroxide compared to conversion from alkali carbonate.
  • the concept behind the method which has been devised is to bring about the possibility of producing green liquor and/or white liquor without unwanted hydrogen carbonate being formed in this liquor, and unwanted hydrogen sulfide being formed in the gas.
  • the principle is that the gasifier product leaving the reactor is cooled by means of direct contact with one or more cooling media, causing mostly solidification of the salts. Any extensive contact between the gas and the receiving liquor is avoided to the greatest extent possible.
  • carbon dioxide in the gasifier product is prevented from reacting with sodium carbonate (reaction (6) above), and carbon dioxide is prevented from reacting with sodium hydroxide (reaction (3) above) and forming sodium carbonate.
  • carbon dioxide is prevented from reacting with sodium hydrogen sulfide (reaction (4) above) and forming sodium hydrogen carbonate and also hydrogen sulfide desorption from the reaction between sodium hydrogen carbonate and sodium hydrogen sulfide is avoided.
  • the need of causticizing of green liquor produced according to the present invention is illustrated in fig. 2.
  • the figure discloses a simplified sketch showing the need for causticizing the produced green liquor as a function of the temperature in the quench region where the alkali metal salts in the gasifier product are separated from the gaseous compounds in said gasifier product.
  • the above mentioned superheated gaseous compounds are quenched in a second stage, which is configured so that the maximum degree of contact is achieved between the gas and the washing liquid. Since the alkali metal salts were separated from the gas in the first stage the above mentioned equillibrium reactions cannot occur in this stage, and thus the intense contact between gas and liquid does not impair the result.
  • the gas is quenched by being allowed to bubble through a liquid bath which principally consists of washing liquid. In this way, the originally superheated hot gas can be efficiently cooled and moist saturated.
  • Fig. 1 discloses a prefened embodiment of the present invention.
  • Spent liquor is gasified in a ceramically lined gasification reactor (1).
  • the reactor (1) is provided with an inlet for black liquor (not shown) and an inlet for oxygen or oxygen-containing gas (not shown), and a burner (not shown).
  • the temperature of the gasifier is kept within the range of 500°C-1600°C, preferably 800°C-1200°C.
  • the pressure in the gasifier is held in the range of 1-150 bar.
  • There are two separate kinds of gasification processes namely low-pressure (or atmospherical) gasification or high- pressure (or pressurized) gasification.
  • Low-pressure gasification e.g. sulphide reactor
  • Low-pressure gasification is carried out at 1.5-5 bar, preferably 1.5-3 bar.
  • High pressure gasification (e.g. green liquor reactor), which is prefened, is carried out at 1.5-150 bar, preferably 10- 80 bar, and most preferably 25-40 bar.
  • the bottom of the reactor opens as a down- coming tube (2), which in turn ends above the resting surface of the receiving liquor (14) in the quench vessel (3).
  • the down-coming tube (2) ends (19) more than 0.5 m, preferably more than 0.7 m and most preferably more than 1.0 m above the surface of the receiving liquid.
  • One ore more cooling media are transported in at least one conduit (8) to at least one nozzle (7) and is then injected into the hot gasifier pro- duct. The cooling medium is injected at a pressure above the pressure in the down- coming tube (2).
  • the temperature of the resulting mixture formed by the injected cooling medium and the gasifier product remains superheated in order to prevent dissociation of the salts and unnecessary formation of carbonates and hydrocarbonates, and that this temperature preferably is lower than the smelt temperature of the alkali metals in order enable the smelt to solidify or partially sodifi- fied or form sufficiently sized drops of smelt in the separation zone before reacliing the surface of the receiving liquor (14).
  • said mixture temperature is within the range of 250-800°C, preferably 250-600°C and most preferably 250- 400°C.
  • the temperature of the mixture of the cooling medium and gasifier products in the down-coming tube (2) is in the range of 150-800°C, preferably 150-600°C and most preferably 150-400°C.
  • the injected cooling medium may at least partially be in liquid state, provided that the resulting mixture is superheated.
  • the cooling effect is stronger if a liquid cooling medium is injected because evaporation of the liquid requires energy.
  • the skilled person can easily determine the amount of cooling medium that can be mixed with the above mentioned hot gasifier product so that this superheating requirement is fulfilled.
  • cooling medium/media is/are injected perpendicularly in relation to the gasifier product stream, or at an angle towards the quench vessel.
  • cooling medium is introduced into a space (annulus, tubes) around the reactor in order to cool it before being supplied.
  • the solidified or partially sodified salt particles (5) are moved downwards by the resulting gas stream and into the liquid by means of gravity and are finally dissolved in the receiving liquor (14).
  • the concentration of the receiving liquor in quench vessel (3) is controlled by adding water or a suitable aqueous solution through pipe (18) and transporting receiving liquor away through conduit (6).
  • the gaseous constituents of the mixture of cooling medium and gasifier products are passed through at least one opening (15) after the down-coming tube (2).
  • the outlet (15) is arranged at least 0.5 m, preferably 0.7 m and most preferably 1 m downwards from nozzle (7) in order to obtain a suitable level of superheating of the gaseous compounds/smelt drops within the tube (2).
  • the superheated gases are subsequently quenched, and optionally cooled and moist-saturated in a second stage after passing through opening (15).
  • the gases are forced into at least one preferably annular cavity (12) at least partially filled with washing liquid (11).
  • Washing liquid is introduced into the side cavity (12) by means of at least one conduit (10) and at least one nozzle (9). It is preferable to inject the washing liquid in a manner so as to not dilute the receiving liquor.
  • the gases are passed through the side cavity (12) an intense contact with the washing liquor (11) is obtained.
  • the gas is let out via conduit (16) together with at least a part of the washing liquid. It is also possible to let out excess washing liquid via pipe (17).
  • the present invention can, of course, be applied to recovering alkali metal salts from different steps in different pulping processes, such as recovering alkali metal salts from spent bleach liquor, or spent liquor from production of CTMP, or spent liquor from a pulping process based on potassium hydroxide.
  • Gasified black liquor was quenched by a process according to the present invention. Gaseous compounds and small smelt drops were let in a down-coming tube ending 1 m above the resting surface of green liquor. The temperature of the gas/smelt mixture was 950 °C and the pressure was 32 bar. As cooling media were injected condensate downstream followed by moist saturated steam of 40 bar, 250°C, in the down-coming tube, whereby the temperature of the resulting superheated mixture became 410°C. The superheated steam and the gaseous compounds were let out through the down-coming tube to a second quenching step and the solidified smelt or partially solidified salt particles were separated from the gas stream by means of gravity and subsequently dissolved in green liquor. The results are disclosed in the table below.
  • Gasified black liquor was quenched according to the teachings of SE-C-448,173.
  • the gasification process were performed in the same manner as in the example. The results are disclosed in the table below.

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  • Paper (AREA)
  • Treating Waste Gases (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

L'invention concerne un procédé permettant de séparer les composants alcalins entraînés dans un gaz surchauffé produit par la combustion partielle d'une liqueur utilisée dans un procédé de lessivage de cellulose. Au moins un agent de refroidissement est injecté dans un mélange gaz/sel en fusion dans une quantité telle que le mélange résultant demeure surchauffé et que les particules de sel soient au moins partiellement solidifiées. Le gaz est emmené pour subir un refroidissement et un lavage séparés et les particules de sel sont dissoutes dans une liqueur de réception.
PCT/SE1998/000637 1994-06-22 1998-04-07 Separation des metaux alcalins d'une liqueur noire gazeifiee Ceased WO1998048102A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
DE69839182T DE69839182T2 (de) 1997-04-24 1998-04-07 Verfahren zur abtrennung der alkalimetalle aus vergaster schwarzlauge
EP98919692A EP0977919B1 (fr) 1997-04-24 1998-04-07 Separation des metaux alcalins d'une liqueur noire gazeifiee
US09/096,506 US6062547A (en) 1994-06-22 1998-06-12 Quench vessel for recovering chemicals and energy from spent liquors

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9701546-5 1997-04-24
SE9701546A SE9701546D0 (sv) 1997-04-24 1997-04-24 New process

Publications (1)

Publication Number Publication Date
WO1998048102A1 true WO1998048102A1 (fr) 1998-10-29

Family

ID=20406712

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1998/000637 Ceased WO1998048102A1 (fr) 1994-06-22 1998-04-07 Separation des metaux alcalins d'une liqueur noire gazeifiee

Country Status (5)

Country Link
EP (1) EP0977919B1 (fr)
AT (1) ATE387536T1 (fr)
DE (1) DE69839182T2 (fr)
SE (1) SE9701546D0 (fr)
WO (1) WO1998048102A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000075421A1 (fr) * 1999-06-07 2000-12-14 Chemrec Aktiebolag Dispositif de gazeification d'une liqueur epuisee

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4808264A (en) * 1985-06-03 1989-02-28 Kignell Jean Erik Process for chemicals and energy recovery from waste liquors
EP0459962A1 (fr) * 1990-05-31 1991-12-04 Chemrec Aktiebolag Procédé de purification du produit gazeux obtenu lors de la combustion partielle de la liqueur noire
SE470516B (sv) * 1992-11-05 1994-06-27 Chemrec Ab Rening av gas från svartlutsförgasning
WO1995035410A1 (fr) * 1994-06-22 1995-12-28 Kvaerner Pulping Ab Procede de lavage du gaz resultant de la gazeification de la liqueur noire

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4808264A (en) * 1985-06-03 1989-02-28 Kignell Jean Erik Process for chemicals and energy recovery from waste liquors
EP0459962A1 (fr) * 1990-05-31 1991-12-04 Chemrec Aktiebolag Procédé de purification du produit gazeux obtenu lors de la combustion partielle de la liqueur noire
SE470516B (sv) * 1992-11-05 1994-06-27 Chemrec Ab Rening av gas från svartlutsförgasning
WO1995035410A1 (fr) * 1994-06-22 1995-12-28 Kvaerner Pulping Ab Procede de lavage du gaz resultant de la gazeification de la liqueur noire

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000075421A1 (fr) * 1999-06-07 2000-12-14 Chemrec Aktiebolag Dispositif de gazeification d'une liqueur epuisee
US6780211B1 (en) 1999-06-07 2004-08-24 Chemrec Aktiebolag Device for gasification of spent liquor

Also Published As

Publication number Publication date
EP0977919A1 (fr) 2000-02-09
DE69839182T2 (de) 2009-02-19
DE69839182D1 (de) 2008-04-10
SE9701546D0 (sv) 1997-04-24
EP0977919B1 (fr) 2008-02-27
ATE387536T1 (de) 2008-03-15

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