EP0251533A1 - Alkaline black liquor treatment - Google Patents

Alkaline black liquor treatment Download PDF

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Publication number
EP0251533A1
EP0251533A1 EP87305198A EP87305198A EP0251533A1 EP 0251533 A1 EP0251533 A1 EP 0251533A1 EP 87305198 A EP87305198 A EP 87305198A EP 87305198 A EP87305198 A EP 87305198A EP 0251533 A1 EP0251533 A1 EP 0251533A1
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EP
European Patent Office
Prior art keywords
black liquor
wet
liquor
concentrated
percent
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.)
Withdrawn
Application number
EP87305198A
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German (de)
English (en)
French (fr)
Inventor
Gerald L. Bauer
Claude E. Ellis
Robert B. Ely
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.)
Zimpro Passavant Inc
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Zimpro Inc
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Filing date
Publication date
Application filed by Zimpro Inc filed Critical Zimpro Inc
Publication of EP0251533A1 publication Critical patent/EP0251533A1/en
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    • 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
    • D21C11/14—Wet combustion ; Treatment of pulp liquors without previous evaporation, by oxidation of the liquors remaining at least partially in the liquid phase, e.g. by application or pressure

Definitions

  • the invention relates to an improvement in the use of wet oxidation as a means for increasing the solids throughput capacity of an alkaline black liquor recovery boiler which is limited by the black liquor firing rate (BTU/hr), while simultaneously reducing the quantity or sulphur lost in flue gas emissions.
  • Alkaline pulping of wood or other cellulosic material results in a black liquor which contains high concentrations of non -cellulosic organic wood components as well as some cellulose and spent pulping chemicals.
  • pulping of wood by the kraft process i.e. using sodium sulfate as the makeup pulping chemical, results in a black liquor in which the concentration of organic matter is about equal to that of the spent pulping chemicals.
  • Such a black liquor will have a heat of combustion of about 6600 BTU per pound of total solids (3670 Kcal. per Kg.), or 13,200 BTU per pound (7330 Kcal. per Kg.) of organic matter.
  • the recovery of pulping chemicals is widely practiced and usually comprises concentration of the black liquor to 60-65 percent solids by several stages of evaporation, followed by drying and combustion of the concentrated black liquor in a furnace. Makeup chemicals are typically added to the concentrated black liquor prior to combustion, to compensate for losses in the overall pulping process.
  • Pulping chemicals are recovered from the bottom of the furnace and steam is generated utilizing the heat of combustion of the organic matter in the black liquor.
  • a typical process for chemical (soda and sulfur) recovery from kraft black liquor consists of the following unit processes:
  • the recovery furnace is normally the single most expensive item of equipment in a pulp mill. Typically it has been designed with minimal excess capacity or firing rate.
  • the mechanical nature of a recovery furnace resists capacity expansion by modification and "fine tuning" of the operation to a greater extent than other parts of the plant.
  • the recovery furnace at most pulp mills today imposes an upper limitation upon production capacity of the entire mill. It is obvious that any method or apparatus which will inexpensively increase the throughput of the recovery furnace is extremely valuable.
  • Oxidation in the aqueous phase with oxygen or oxygen containing gas is conducted at temperatures of 250 to 650°F (120 to 340°C), and at pressures necessary to maintain a liquid phase, typically 200 to 4000 psig (1500 to 28,000 KPa).
  • temperatures of 250 to 650°F (120 to 340°C) typically 200 to 4000 psig (1500 to 28,000 KPa).
  • pressures necessary to maintain a liquid phase typically 200 to 4000 psig (1500 to 28,000 KPa).
  • thermal and/or mechanical energy is recovered from the vapor and/or liquid streams from the wet oxidation process.
  • Pradt U.S. Patent 4,013,560 describes a prior art wet oxidation process with energy recovery.
  • Schoeffel U.S. Patent 3,097,988 discloses a process for treating alkaline black liquors by "complete" wet oxidation.
  • Pradt U.S. Patent 3,714,911 proposes a wet oxidation process to replace the conventional evaporation and concentration steps.
  • This invention is an improvement in a widely-used process for recovering inorganic pulping chemicals, abbreviated herein as PC, from an alkaline aqueous black liquor which also contains oxidizable organic matter, abbreviated herein as OM.
  • alkaline black liquor is first concentrated by water evaporation to an intermediate solids concentration, using an evaporator apparatus such as a multiple effect evaporator, long-tube vertical evaporator, thermal compression evaporator and/or Digester Flash Evaporative System (DIFES).
  • evaporator apparatus such as a multiple effect evaporator, long-tube vertical evaporator, thermal compression evaporator and/or Digester Flash Evaporative System (DIFES).
  • DIFS Digester Flash Evaporative System
  • the evaporated black liquor having an intermediate solids concentration is generally further concentrated, typically by direct contact with hot furnace gases in a plate cascade evaporator or cyclone evaporator. While this further step is generally known as “concentration”, performed in a “concentrator”, and the prior step is commonly called “evaporation”, performed in an “evaporator”, both steps are evaporative.
  • concentration performed in a “concentrator”
  • evaporation performed in an “evaporator
  • both steps are evaporative.
  • the terms “evaporate” and “evaporation” shall be construed to include evaporation in “evaporators” and/or “concentrators”, unless otherwise specifically limited.
  • the black liquor drawn off from the pulping process is concentrated by one or more steps of evaporation.
  • BLOX black liquor air oxidation
  • the concentrated black liquor is passed to a chemical recovery furnace where it is dried and combusted to produce a smelt of recovered inorganic pulping chemicals (PC).
  • makeup chemicals may be added to the concentrated black liquor fed to the furnace.
  • the improvement of this invention comprises the steps of:
  • the point at which black liquor is diverted to the wet oxidation step may be prior to, or subsequent to several steps of evaporation and concentration, but is before the final step of concentration.
  • the wet oxidized black liquor may be combined with the remainder of unoxidized black liquor at any point in the process prior to combustion in the chemical recovery furnace.
  • This invention allows pumping, concentration and combustion of black liquors having increased concentrations of total solids and pulping chemicals, because of the discovery that at a given solids concentration, a mixture of oxidized black liquor and unoxidized black liquor has a lower viscosity than either liquor by itself. Thus the solids throughput of the evaporators and/or furnace may be increased.
  • this invention permits ready control over the PC/OM ratio and the final solids concentration in the furnace feed, regardless of continual changes in rate of black liquor production, its total solids concentration and/or its PC/OM ratio.
  • This invention is a process for improving the operation of a pulp mill's black liquor chemical recovery plant.
  • the conventional recovery plant to which this invention applies is illustrated in FIG. 1, and treats the black liquor in one or more steps of concentration by evaporation, followed by combustion of the concentrated black liquor in a chemical recovery furnace.
  • Evaporator 2 typically comprises several stages and is then known as a multiple-effect evaporator.
  • Evaporated black liquor 4 is further concentrated in concentrator 5 , and additional moisture 6 is driven off.
  • Concentrated black liquor 7 together with makeup pulping chemicals 8 is sprayed into recovery furnace 9 where air 10 is introduced to burn the organic matter in the black liquor.
  • Product smelt 12 of pulping chemicals is recovered; oxidation products and steam are discharged in offgas 11 .
  • weak black liquor 1 is first wet oxidized with air or oxygen 14 in wet oxidizer 13 , producing an offgas 15 which contains moisture.
  • the wet oxidized black liquor 16 then passes through evaporator 17 to produce a liquor 19 , of intermediate concentration.
  • the black liquor 22 and optional makeup chemicals 23 are burned with air 25 , in recovery furnace 24 .
  • Water vapor is discharged from the system in streams 15 , 18 , 21 and 26 .
  • a smelt 27 of chemicals is recovered.
  • weak black liquor 1 is wet oxidized in wet oxidizer 28 with air or oxygen 29 .
  • the wet oxidation step includes an integral flash evaporation step to remove a large amount of water 30 and concentrate the black liquor prior to optional mixing with makeup chemicals 32 and combustion with air 34 in furnace 33 .
  • the chemical smelt 36 and offgases 35 are discharged from the furnace.
  • the wet oxidation step is typically operated to provide a partial oxidation; for example, 30 - 60 percent of the organic matter (OM) is destroyed.
  • OM organic matter
  • the present invention is distinguished from prior processes utilizing wet oxidation in that a portion, rather than all, of the black liquor stream is wet oxidized.
  • the wet oxidized portion generally having an elevated viscosity (at the same total solids concentration) is combined with the unoxidized black liquor, either before or after the unoxidized liquor is concentrated by evaporation.
  • the liquor mixture has a viscosity lower than either the unoxidized or wet oxidized black liquor alone, and it is possible to concentrate the liquor to a higher concentration prior to burning in the recovery furnace.
  • the mixed black liquor has a higher PC/OM ratio, increasing the furnace throughput.
  • This invention is particularly useful as a modification of an existing chemical recovery plant to increase its throughput and efficiency without a prohibitively large capital expenditure. As will be seen in the ensuing description, the invention not only achieves an increased throughput in the recovery furnace, but may also overcome limitations on throughput presented by the evaporator and/or concentrator.
  • FIGS. 6 through 10 illustrate several practical applications of the invention, but are not exhaustive thereof.
  • a flow 1 of alkaline pulping weak black liquor is diverted by splitter 37 into a portion 38 which is passed to wet oxidizer 39 .
  • the diverted liquor is wet oxidized at a pressure of 200 - 4000 psig (1500 - 28,000 KPa) and at a temperature of 300 - 650°F (150 - 340°C) with oxygen or an oxygen containing gas 40 to destroy all or part of the oxidizable organic matter (OM).
  • OM oxidizable organic matter
  • the fraction of weak black liquor diverted to the wet oxidizer comprises up to about one-half, but may be as little as 5 percent of the flow.
  • the fraction of OM destroyed in the wet oxidizer may range from about 5 percent to nearly quantitataive.
  • the ratio of inorganic pulping chemicals (PC) to oxidizable matter (OM) is increased as OM is destroyed.
  • PC/OM of the oxidized liquor is doubled when the wet oxidation step is operated at 50% oxidation.
  • the optimal design is achieved when a relatively small fraction, 5 to 35 percent, of the black liquor is wet oxidized to destroy at least 30 percent of the oxidizable organic matter.
  • oxidized black liquor 42 is combined with the remainder 43 of unoxidized black liquor to produce a mixture 44 having increased PC/OM and decreased viscosity relative to unoxidized black liquor 1 .
  • the mixture 44 is evaporated to an intermediate solids concentration in evaporator 45 , and the resulting black liquor 47 is concentrated in final concentrator 48 .
  • Moisture 46 , 49 is driven off by thermal energy input, usually steam, not shown.
  • Makeup chemicals 51 are optionally added to the concentrated black liquor 50 and the mixture passed to the chemical recovery furnace 52 .
  • Oxidizable organic matter is burned with air 53 , producing offgas 54 , and a smelt 55 of pulping chemicals is recovered.
  • a portion 57 of weak black liquor 1 is diverted by splitter 56 to wet oxidizer 58 .
  • the liquor is wet oxidized with air or oxygen containing gas 59 to produce a wet oxidized liquor 61 .
  • wet oxidation conditions may be controlled to evaporate a considerable portion of water, which leaves the system in stream 60 .
  • Wet oxidized black liquor 61 may then be combined with unoxidized black liquor at a location preceding recovery furnace 76 .
  • wet oxidized liquor 61 may be combined with remaining unoxidized black liquor:
  • the flow of wet oxidized liquor 61 may be split by splitter 62 into two or three streams 63 , 69 , 74 to achieve optimal operation of the evaporator, concentrator and furnace.
  • all or part of the wet oxidized liquor may be combined as streams 69 and/or 74 rather than as stream 63 . If it is added as a single stream, of course, splitter 62 is not needed or used.
  • Wet oxidized black liquor is generally added as stream 74 following the concentrator only when the wet oxidizer 58 is operated at high oxidation conditions of about 80 percent or greater, and a large portion of water is removed in the wet oxidation step.
  • the solids content of liquor stream 74 is roughly the same as that of concentrated black liquor 73 , and autogenous combustion can be achieved in the furnace 76 .
  • a combustible material will support autogenous combustion when the released thermal energy meets or exceeds the total thermal energy required by the furnace to operate at the desired conditions of temperature, throughput rate and degree of combustion.
  • Adding all or a portion of wet oxidized black liquor as stream 69 to evaporated liquor 68 has special advantages. Since the maximum solids concentration which can be achieved in concentrator 71 is usually limited by black liquor viscosity, adding wet oxidized liquor prior to the concentrator reduces viscosity and permits a higher solids concentration to be achieved.
  • FIG. 8 shows a further embodiment illustrating the invention.
  • the weak black liquor 1 is first passed through evaporator 80 , to evaporate a large portion of water as vapor 81 .
  • Black liquor 82 of intermediate concentration is divided into two fractions by splitter 83 .
  • Diverted portion 84 is wet oxidized in wet oxidizer 85 by air or oxygen containing gas 86 resulting in an offgas 87 , containing water vapor.
  • Wet oxidized black liquor 88 is combined with the remainder 89 of unoxidized black liquor from evaporator 80 .
  • the mixed stream 90 having an increased PC/OM ratio and reduced viscosity, is passed to concentrator 91 where further water vapor 92 is driven off, and the concentrated liquor 98 is burned in recovery furnace 99 with air 100 to burn the remaining organic matter. Offgas 101 and a smelt 102 of recoverable chemicals are produced.
  • a particular advantage to this embodiment is that the fraction of black liquor to be wet oxidized is a much smaller volume of a more concentrated stream.
  • the reduced size of the wet oxidation system results in appreciable cost savings over that of the embodiments in FIGS. 6 and 7.
  • the wet oxidized black liquor 94 may optionally be diverted to a splitter 95 which divides the stream into two fractions.
  • a first fraction 96 is combined with the remainder of evaporated unoxidized black liquor 89 , forming mixture 90 .
  • a second fraction 97 of wet oxidized black liquor is combined with concentrated mixed black liquor 93 prior to burning in furnace 99 .
  • black liquor to be wet oxidized is diverted both before and after the evaporation step, in order to optimally control the concentration of the wet oxidizer feed.
  • a portion 104 of weak black liquor 1 is diverted by splitter 103 to wet oxidizer 105 .
  • the remaining black liquor 106 is evaporated in evaporator 107 , discharging water 108 and black liquor 109 at an intermediate concentration.
  • a portion 111 of black liquor 109 is diverted by splitter 110 to wet oxidizer 105 which wet oxidizes the mixture of black liquor streams 104 and 111 with air or oxygen containing gas 112 . Water vapor is discharged in offgas 113 .
  • black liquor is diverted to the wet oxidizer 105 at two locations.
  • Each diverted liquor has a different solids concentration, and a calculation of the total fraction of black liquor which undergoes wet oxidation is based upon the weight of inorganic pulping chemicals in each diverted stream.
  • wet oxidized black liquor 115 is combined with the remaining intermediate concentration black liquor 114 to form mixed black liquor 116 .
  • Liquor 116 is further concentrated by evaporation in concentrator 117 .
  • Water vapor 118 is discharged and concentrated black liquor 119 is dried and burned in furnace 120 with air 121 to produce offgas 122 and smelt 123 of recovered pulping chemicals.
  • black liquor may be diverted from an intermediate stage or stages to provide an optimum solids concentration to the wet oxidizer 105 .
  • each diverted stream may be continuously controlled to provide proper operation of the wet oxidizer.
  • black liquor strength (solids concentration) and/or rate may vary with time, it may be desirable to control each diverted flow rate to achieve wet oxidation of a constant volumetric rate of black liquor containing a constant fraction of the total solids.
  • the splitter shown in the FIGS. 6-9, 11 and 12 is any device which will divert a portion of the black liquor flow to the wet oxidizer, and may include a flow control valve or valves, or a positive displacement pump.
  • FIG. 10 The effect of wet oxidizing a portion of the black liquor upon the PC/OM ratio of black liquor entering the furnace is illustrated in FIG. 10.
  • the PC/OM ratio must be increased in order to increase throughput.
  • Many combinations of (a) percent diversion to the wet oxidizer and (b) percent oxidation will achieve the desired result. From FIG. 10, three such combinations are:
  • the portion of black liquor which is wet oxidized may range from 5 to about 50 percent, in most cases the optimal diverted portion is 5 to about 35 percent.
  • quantitative wet oxidation of 50 percent of the black liquor will increase the PC/OM ratio of furnace feed by a factor of 2.0.
  • the optimal degree of oxidation may lie in the 30 - 70 percent range, but in particular cases the degree of oxidation (percentage OM reduction) in the wet oxidation step may be as low as 5 percent or as high as essentially 100 percent.
  • the wet oxidizer When the degree of oxidation exceeds about 15 percent, the wet oxidizer may be operated at pressures and temperatures to result in evaporation of a large quantity of water. In some cases, the wet oxidized black liquor may be sufficiently concentrated to have a heating value equal to or greater than the furnace requirement for autogenous combustion.
  • the energy released in the wet oxidation step may be recovered and used to heat and evaporate water from the black liquor, for example, in the evaporator and/or concentrator. Excess steam may be used in other operations of the mill.
  • the invention may be used with any alkaline pulping liquor, and is particularly applicable to kraft cellulose pulping liquors. While batch-wise operation of wet oxidation systems may be cost effective for certain small pulp plants, continuous operation is the preferred mode of operation.
  • make-up chemicals may typically be added to the concentrated black liquor prior to drying and combustion in furnace.
  • Viscosities are measured with a Brookfield rotating spindle viscometer. Viscosity values in centipoise (cp) obtained at 100 rpm and 180°F (82°C) were used for comparing the various samples. Although each pulp mill may use its own particular type of viscometer and test conditions, the results are comparable to the data presented herein. For example, some mills use viscosity measurements obtained at 200°F (93°C) where the viscosity is considerably lower than at 180°F (82°C).
  • the raw black liquor resulting from kraft pulping of hardwood had the following analysis: Total Solids, percent 42.0 Organic Matter, percent 20.5 Inorganic Pulping Chemicals, percent 21.5 Chemical Oxygen Demand (COD), percent 45.7 Heat of Combustion, BTU per lb. solids 5911 (Kcal. per kg solids) 3285 PC/OM Ratio 1.05 pH 13.1 Sp. Gr. 1.266 Viscosity, Brookfield, cp at 180°F(82°C), 100 rpm 28
  • a first portion of the raw black liquor was evaporated to a concentration suitable for combustion in a recovery boiler.
  • the analysis of the concentrated liquor was: Total Solids, percent 69.6 Organic Matter, percent 33.8 Inorganic Pulping Chemicals, percent 35.8 Chemical Oxygen Demand, percent 70.0 Heat of Combustion, BTU per lb. solids 6236 (Kcal. per kg. solids) 3465 PC/OM Ratio 1.06 pH 12.4 Sp. Gr. 1.520 Viscosity, Brookfield, cp at 180°F(82°C), 100 rpm 1400
  • a second portion of the raw black liquor was subjected to wet oxidation treatment at 400°F (204°C) using oxygen as the oxidant. A total of 37.4 percent of the oxidizable organic matter was destroyed, as determined by the COD reduction.
  • the analysis of wet oxidized black liquor was as follows: Total Solids, percent 35.7 Organic Matter, percent 13.9 Inorganic Pulping Chemicals, percent 21.8 Chemical Oxygen Demand, percent 27.9 Heat of Combustion, BTU per lb. solids 4061 (Kcal. per kg. solids) 2257 PC/OM Ratio 1.57 pH 9.1 Sp. Gr. 1.264 Viscosity, Brookfield, cp at 180°F(82°C), 100 rpm 28
  • Example 1 The data of Example 1 will be applied to three modes of pre-furnace operation:
  • the furnace feed materials (after concentration) will have the following calculated compositions:
  • wet oxidizing the entire black liquor stream There are several disadvantages to wet oxidizing the entire black liquor stream.
  • viscosity effect of wet oxidation reverses when complete oxidation of the OM is approached.
  • the viscosity of such highly oxidized black liquor may be equal to or lower than the original black liquor.
  • furnace capacity is increased by a further 3.6 percent, providing a 9.5 percent total increase in furnace capacity.
  • a raw black liquor resulting from kraft pulping of fir had the following analysis: Total Solids, percent 46.3 Organic Matter, percent 23.2 Inorganic Pulping Chemicals, percent 23.1 Chemical Oxygen Demand (COD), percent 49.4 Heat of Combustion, BTU per lb. solids 6030 (Kcal. per kg. solids) 3351 PC/OM Ratio 1.00 pH 13.0 Sp. Gr. 1.307 Viscosity, Brookfield, cp at 180°F(82°C), 100 rpm 40
  • a first portion of the raw black liquor was concentrated by evaporation to a concentration suitable for combustion in a recovery boiler.
  • the analysis of the concentrated liquor was: Total solids, percent 68.8 Organic Matter, percent 34.1 Inorganic Pulping Chemicals, percent 34.7 Chemical Oxygen Demand, percent 72.0 Heat of Combustion, BTU per lb. solids 6273 (Kcal. per kg. solids) 3486 PC/OM Ratio 1.02 pH 11.9 Sp. Gr. 1.890 Viscosity, Brookfield, cp at 180°F(82°C), 100 rpm 2000
  • FIGS. 11, 12 and 13 compare material balances for several embodiments of this invention applied to a chemical recovery plant treating 500,000 Kg/day of black liquor containing 80,000 Kg. solids.
  • FIG. 11 shows the existing recovery plant, having the flowsheet and indicia of FIG. 1. It is assumed that the limiting factors in these examples are the evaporative capacities of the evaporator and concentrator.
  • the invention is adapted to the process of Example 4, using the flowsheet of FIG. 8.
  • the wet oxidizer treats 50 percent of the black liquor from evaporator 80 , oxidizing 25 percent of the organic matter.
  • the wet oxidizer is operated to evaporate 73.6 percent of the moisture in the diverted portion of black liquor.
  • the net increase in PC capacity of the recovery plant is 10.0 percent.
  • the invention is adapted to the process of Example 4, using the flowsheet of FIG. 7.
  • the wet oxidizer treats 15 percent of the weak black liquor, evaporating about one-half of its water and oxidizing 50 percent of the organic matter.
  • the PC capacity of the recovery plant is increased by 5 percent.

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EP87305198A 1986-06-23 1987-06-12 Alkaline black liquor treatment Withdrawn EP0251533A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US87715686A 1986-06-23 1986-06-23
US877156 1986-06-23

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EP0251533A1 true EP0251533A1 (en) 1988-01-07

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EP (1) EP0251533A1 (fi)
AU (1) AU7361687A (fi)
BR (1) BR8703602A (fi)
FI (1) FI872751A (fi)
NO (1) NO872605D0 (fi)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012117161A1 (en) * 2011-02-28 2012-09-07 Aalto University Foundation Method of recovering chemicals
EP3124693A1 (fr) 2015-07-31 2017-02-01 Commissariat A L'energie Atomique Et Aux Energies Alternatives Dispositif et procede de traitement de la liqueur noire provenant de la preparation de pate a papier par liquefaction hydrothermale

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3714911A (en) * 1971-03-10 1973-02-06 Sterling Drug Inc Method of treatment of alkaline pulping black liquors by wet air oxidation
WO1985004202A1 (en) * 1984-03-21 1985-09-26 Spannuth Robert J A process for producing a partially oxidized, concentrated, spent pulping liquor

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3714911A (en) * 1971-03-10 1973-02-06 Sterling Drug Inc Method of treatment of alkaline pulping black liquors by wet air oxidation
WO1985004202A1 (en) * 1984-03-21 1985-09-26 Spannuth Robert J A process for producing a partially oxidized, concentrated, spent pulping liquor

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
TAPPI JOURNAL, vol. 67, no. 11, November 1984, pages 52-58, Atlanta, Georgia, US; T.M. GRACE: "Increasing recovery boiler throughput" *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012117161A1 (en) * 2011-02-28 2012-09-07 Aalto University Foundation Method of recovering chemicals
US9102533B2 (en) 2011-02-28 2015-08-11 Aalto University Foundation Method of recovering chemicals
EP3124693A1 (fr) 2015-07-31 2017-02-01 Commissariat A L'energie Atomique Et Aux Energies Alternatives Dispositif et procede de traitement de la liqueur noire provenant de la preparation de pate a papier par liquefaction hydrothermale

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NO872605D0 (no) 1987-06-22
FI872751A0 (fi) 1987-06-22
BR8703602A (pt) 1988-08-23
FI872751A (fi) 1987-12-24
AU7361687A (en) 1987-12-24

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