CA1082860A - Burning process for black liquor - Google Patents
Burning process for black liquorInfo
- Publication number
- CA1082860A CA1082860A CA254,183A CA254183A CA1082860A CA 1082860 A CA1082860 A CA 1082860A CA 254183 A CA254183 A CA 254183A CA 1082860 A CA1082860 A CA 1082860A
- Authority
- CA
- Canada
- Prior art keywords
- black liquor
- liquor
- gases
- stream
- green liquor
- 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.)
- Expired
Links
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
-
- 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
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- Paper (AREA)
Abstract
ABSTRACT
Black liquor formed during paper making processes is burned in such a manner as to provide maximum recovery of the chemicals utilized in the paper making process yet provide combustible gases having heat value, which when utilized in a separate burning process may be useful in waste heat recovery processes such as making of steam.
Black liquor formed during paper making processes is burned in such a manner as to provide maximum recovery of the chemicals utilized in the paper making process yet provide combustible gases having heat value, which when utilized in a separate burning process may be useful in waste heat recovery processes such as making of steam.
Description
The present invention relates to paper-making processes and in particular to the treatment of black liquor formed during such paper-making processes.
0f the various processes for the manufacture of paper the "Kraft Process" is responsible for the major part of the pulp manufactured at the present time. Other processes include "Soda Pulp", utilizing basically sodium hydroxide (NaOH), "Sulfite Pulp" and other minor processes.
Although ~his invention is applicable to the recovery of chemicals in the other pulping processes, it is described initially in terms of Kraft black liquor recovery.
Typically, in the manufacture of Kraft paper, a "white liquor" comprising an aqueous solution of sodium sulfide and sodium hydroxide is used in the digestion of wood chips or the like. The spent cooking liquor, herein identified as "black liquor" is recovered. Black liquor contains sodium salts of a variety of complex chemicals which are derived from the lignin present in the wood and also contains other wood derivatiYes, sodium sulfide and other sulfur bearing compounds.
Heretofore, Kraft black liquor recovery proces-ses involved the concentration of black liquor and its combustion in a recovery boiler or a furnace. Typical of such furnaces are those described in United States Patents No. 3,607,117, No. 2,582,792 and No. 3,574,446 and may other references. The concentrated black liquor is usually introduced as a spray through a nozzle about midway between the top and bottom of the boiler. The spray flows towards the boiler hearth whereupon water is vaporized and carbonaceous material is partly burned.
The spray particles collect in a large pile on the hearth ~Q8Z860 of the furnace and are there burned by the introduction of air which is directed over the pile of burning matter. The carbonaceous material is either di8tilled off or burned while the mineral matter is reduced to a mixture of sodium carbonate and sodium sulfide containing relatively small amounts of other mineral constituents.
The gases that rise from the burning mass of liquor pass upwardly through the furnace in countercurrent contact with the descending spray and are thereafter contacted with additional air to mix with the rising gases to complete the combustion. These rising gases leaving the combustion chamber are usually caused to pass over boiler tubes to which the heat is transferred for the creation of steam.
Thereafter the gases have been attempted to be purified by removing fumes and dust while sulfur compounds in the gases are burned to sulfur dioxide. Heretofore such waste gases have been discharged into the atmosphere with other combustion products and thus now represents a major source of air pollution.
A sodium carbonate-sulfide mixture is removed as a smelt from the bottom of the furnace where it is sprayed into a tank of water to form a solution of the sales known as "green liquor." Further treatment converts the sodium carbonate to sodium hydroxide and thus provides reconstituted chemical "white liquor," which is then returned as useful in the digesting or cooking processes.
The black liquor recovery furnace is one of the most expensive items of equipment in the papermaking 10828~i0 proccss. The ~rocess ~nd reactions that occur therein are not completely safe. It is not at all uncommon to have serious explosions caused by the failure of a furnace boiler tube allowing water to spill onto the burning pilo of black liquor on the hearth. In addition, the air-pollution problems hcroto-forc known with the papermaking processes are under current scrutiny by governments all over the world. Not only does the process usually result in malodorous emissions, which include hydrogen sulfide and other mercaptan products, but the particle-laden flume usually associated with the wood pulp industry have become highly undesirable.
It is an object of this invention to provide a process capable of replacing and/or acting as a standby alternate for the heretofore used black liquid recovery furnace used in the paper pulp industry.
According to the present invention, there is provided a method of continuously processing a stream of black liquor, comprising the steps of:
spraying a first portion of said black liquor stream into a burner structure connected to a combustion chamber; injecting air and any necded auxiliary fuel into said burner structure such that the ratio of air to said black liquor stream is less than the stoichiometric requirement of oxygen to totally oxidize said black liquor stream yet is sufficient to maintain stable combustion; spraying the remaining portion of said black liquor stream into said combustion chamber; quenching the total gaseous and solid mineral products of combustion with water or aqueous green liquor capable of inter-cepting and absorbing a portion of said solid mineral products contained in said gaseous stream to form green liquor; collecting said green liquor;
venturi scrubbing the effluent gases of said quenching step with water or aqueous green liquor to remove residual solid mineral matter to form additional green liquor; separating and collecting said additional green liquor and create particulate-free gases; burning said gases; and withdrawing said collected green liquor for use elsewhere. Thus, concentrated black liquor is introduced, like a fuel, into a vertically downfired burner under conditions wherein air is introduced to support the burning at less than ~ _ 4 _ stoichiomctric conditions. 'I'his brings about the oxidation and reforming of the organic constituents into combustible gaseous and inorganic solid components. As a result significant amounts of combustibles, e.g., carbon monoxide, hydrogen and other organic combustible gases are produced. The resulting gases are quenched with a water spray which may comprise recycle green liquor with subsequent separations of vapor and liquid and wet scrubbing operations upon the gas to capture the particulate matter.
- 4a -~,, 108'~860 The vapors therefrom are subsequently burned under oxidizing conditions with the hot products of combustion contacting a waste heat boiler utilized to make steam.
Clean exhaust gases are vented to the atmosphere.
Additionally, the process includes other optional equipment, including sweetening or removal of sulfurous containing products from the resultant combustible vapor products.
As a result this invention provides a black liquor recovery process free from the disadvantages of cost and explosive hazards but yet provides adequate chemical recovery advantages free from air pollution.
FIGURE 1 is a process flow sheet describing the invention.
FIGURE 2 is a partial-sectional view of a typical burner capable of use in the black liquor or the like salt recovery process of this invention.
FIGURE 3 is a frontal view of the injection nozzle taken along the line 3-3 of FIGURE 3.
FIGURE 4 is a top-sectional view of another form of furnace and burner arrangement for burning black liquor.
Before explaining the present invention in detail it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings since the invention is capable of other embodiments and of being practiced or carried out in a variety of ways.
Also, it is to be understood that the phraseology or : ' . ~ . . .
terminology employed herein is for the purpose of description and not of limitation.
Referring now to the drawings and, in particular, to FIGURE 1, black liquor is fed by way of conduit 10 into the system where it may be divided, as for example , 55~ of the flow stream passing through conduit 12 into burner 14 while the remainder of the stream is sprayed into the combustion chamber 16 by way of conduit 18. Air is supplied by way of conduit 20 into the burner such that the burner 14 is operated under less than stoichiometric conditions whereby a large amount of combustibles are created. The gases resulting from the combustion in chamber 16 are caused to pass into a throat section 22 and thence to the quench tank 24.
Prior to entry into the quench tank a liquid is sprayed into the gases via conduit 26. Such liquid is typically green liquor taken from vapor-liquid separating tank 28 and/or the quench tank 24 by the action of pump 39.
Makeup water may be introduced into conduit 26 via conduit 32. Additional portions of green liquor are pumped to conduit 34, where it enters the throat of a venturi scrubber 36. Surplus amounts of green liquor are caused to be taken from the system via conduit 38 for further processing to white liquor or other chemicals capable of being utilized in the pulping or paper making process.
The resulting gases from the vapor-liquid separator 28 are caused to pass through a demisting device 40 thence through conduit 42 to further processing of the gases to -.~ ' ,''' ' ~
.
utilize the BTU content thereof. In the instance shown the gases are caused to enter a preheater 44 formed as a part of the exhaust stack 46 with the outlet thereto passing by way of conduit 48 to a burner 50. Air may also be heat exchanged with the hot exhaust gases in stack 46 by its entry via passageway 52 and outlet 54 to the burner 50. The combustible mixture is then burned in the combustion zone 56 with resulting hot gases caused to flow across boiler tubes in boiler 58 resulting in an output of steam as shown at conduit 60.
The resulting cooled gases are then exhausted via stack 46 into the atmosphere.
An alternate treatment of the gases issuing through conduit 42 is applicable for those processes where the gases contain large amounts of sulfur-containing products as in the Kraft process. As such, appropriate and known types of gas-sweetening processes ~e.g. amine) generally designated by the numeral 70 with any valuable reusable sulfur compounds issuing therefrom passing via conduit 72 back to the process either by way of line 72A to the combustion chamber or by way of 72B to the scrubber intake.
A typical example of the use of this invention is set forth wherein 25,000 pounds per hour of black liquor having 60~ solid material therein at a temperature of 250 F. is finely atomized through a burner. Alternatively only a portion of the black liquor is burned directly in the burner, the remainder being injected into the combustion chamber proper. Air is supplied to the burner at the rate -., of 1,435,2 mols per hour, thus providing 55% of the stoichiometric air requirements of the total black liquor steam being burned. The amount of black liquor fed to the burner must be sufficient to provide a stable flame and sufficient heat for combustion of the remaining portion. The resulting combustion process occurs at 1,800 F. producing 26.7% combustible gases on a dry basis. The combustion chamber is designed so that there is a burning retention time of from 1 to 3 seconds therein.
The resulting combustion gase~ and solids are comprised as follows:
CompoundMols/Hr.
H20 1,046.5 C2 214.8 N2 1,134.4 C0 175.8 H2 316.4 Salts 78.2 Green liquor plus any make-up water is introduced into 2C the gases at the rate of 176.2 gallons per minute (GPM).
This quench process reduces the gases and materials to a temperature within the quench tank 24 to within the temperature range of 180 to 200 F. Green liquor is removed from the system to further processing and use.
This green liquor is removed at the rate of 106.2 GPM
and has a chemical content as follows:
Compound Wt.
Na2C3 7.78 NaHC03 5.23 Na2S 3.34 The resulting gases and any particles therein pass through a venturi scrubber to remove the remainder of the particulate matter, green liquor being injected as the scrubbing medium. Separation is effected within the vapor-liquid knock-out separator. The gases in the separator are at substantially the same temperature as the quench tank. The resulting gases in the effluent from the separator are comprised as follows:
Compound Mols per Hour H20 3,000.3 C2 136.3 N2 113.4 C0 175.8 H2 316.4 Salts -0-It is this particulate-free gas that is then caused to pass into a preheater, thence used as a fuel in a waste heat boiler furnace where combustion of the products occurs, with the heat being utilized to create steam.
Clean gases are then exhausted to atmosphere.
Referring now to FIGURE 2, a typical burner is shown in cross section and includes a housing suitably protected by a refractory and attached to a combustion chamber 82. An air inlet 84 is connected with a plenum 11~82860 chamber 86, which air ultimately enters the inlet zone 88 for passage across the baffle plate 96. Suitable means including an inlet 90 for black liquor provides a conduit to supply the same to an atomizing nozzle 92.
This inlet is adjus~ably secured within a housing 94 which terminates near the nozzle in a conical air deflection baffle 96 having a plurality of openings 98 therein. A suitable ignition device 100 is provided.
Referring now to FIGURE 4, an alternate embodiment of a burner means is provided by a cylindrical housing or combustion chamber 16A about the periphery of which are placed a plurality of burners 14A, 14B, 14C and 14D.
Intermediate thereof are provisions for injecting black liquor as a fine spray at 18A, 18B, 18C and 18D. It is to be understood, however, that other modifications and burner and spray combustion chamber designs are with the purview of this invention.
Modifications of the process herein include the applicability of the process to other sodium base recovery processes typical, however, of those in paper pulp industry, e.g., soda process, etc.
Preferably the input black liquor is over 50%
solids, although liquids containing less solids are also inclusive of the invention. Usually the moisture content is reduced as by evaporative means or the like prior to flow into the process of this invention.
The air to the initial burner is adju.sted to be within the range of 40 to 80~ of the stoichiometric requirements .
of the black liquor. In some instances the burner or burners in which a portion of the black liquor is conducted may be operated at stoichiometric conditions for that amount of black liquor. When the remaining portion of black liquor is injected into the combustion zone the overall less than stoichiometric conditions as taught herein will occur. The temperature within the combustion zone preferably should not be over 2,200 F.
preferably within the range of 1400-2200 F. Residence times may vary from 0.6 to 6 seconds.
In some instances auxiliary or waste fuel is supplied to either the first or second burners 14 and 50, respectively, when needed for additional heat.
~ ecause of the absence of a smelt bed and complete particulate removal prior to heat recovery Applicants' process provides apparatus of lower investment without explosive hazard, boiler and heat exchanger fouling or particulate or odorous emissions, yet utilizing the available fuel energy of the gaseous products from the process. The broadest aspect of this invention is directed to the discovery of first directly burning the black liquor with insufficient oxygen in a burner and secondly the recovery and separation of the gaseous and particulate material by the processes shown herein or by electrostatic precipitation, or use of bag filters after a quench of the resulting products of combustion.
' ~
0f the various processes for the manufacture of paper the "Kraft Process" is responsible for the major part of the pulp manufactured at the present time. Other processes include "Soda Pulp", utilizing basically sodium hydroxide (NaOH), "Sulfite Pulp" and other minor processes.
Although ~his invention is applicable to the recovery of chemicals in the other pulping processes, it is described initially in terms of Kraft black liquor recovery.
Typically, in the manufacture of Kraft paper, a "white liquor" comprising an aqueous solution of sodium sulfide and sodium hydroxide is used in the digestion of wood chips or the like. The spent cooking liquor, herein identified as "black liquor" is recovered. Black liquor contains sodium salts of a variety of complex chemicals which are derived from the lignin present in the wood and also contains other wood derivatiYes, sodium sulfide and other sulfur bearing compounds.
Heretofore, Kraft black liquor recovery proces-ses involved the concentration of black liquor and its combustion in a recovery boiler or a furnace. Typical of such furnaces are those described in United States Patents No. 3,607,117, No. 2,582,792 and No. 3,574,446 and may other references. The concentrated black liquor is usually introduced as a spray through a nozzle about midway between the top and bottom of the boiler. The spray flows towards the boiler hearth whereupon water is vaporized and carbonaceous material is partly burned.
The spray particles collect in a large pile on the hearth ~Q8Z860 of the furnace and are there burned by the introduction of air which is directed over the pile of burning matter. The carbonaceous material is either di8tilled off or burned while the mineral matter is reduced to a mixture of sodium carbonate and sodium sulfide containing relatively small amounts of other mineral constituents.
The gases that rise from the burning mass of liquor pass upwardly through the furnace in countercurrent contact with the descending spray and are thereafter contacted with additional air to mix with the rising gases to complete the combustion. These rising gases leaving the combustion chamber are usually caused to pass over boiler tubes to which the heat is transferred for the creation of steam.
Thereafter the gases have been attempted to be purified by removing fumes and dust while sulfur compounds in the gases are burned to sulfur dioxide. Heretofore such waste gases have been discharged into the atmosphere with other combustion products and thus now represents a major source of air pollution.
A sodium carbonate-sulfide mixture is removed as a smelt from the bottom of the furnace where it is sprayed into a tank of water to form a solution of the sales known as "green liquor." Further treatment converts the sodium carbonate to sodium hydroxide and thus provides reconstituted chemical "white liquor," which is then returned as useful in the digesting or cooking processes.
The black liquor recovery furnace is one of the most expensive items of equipment in the papermaking 10828~i0 proccss. The ~rocess ~nd reactions that occur therein are not completely safe. It is not at all uncommon to have serious explosions caused by the failure of a furnace boiler tube allowing water to spill onto the burning pilo of black liquor on the hearth. In addition, the air-pollution problems hcroto-forc known with the papermaking processes are under current scrutiny by governments all over the world. Not only does the process usually result in malodorous emissions, which include hydrogen sulfide and other mercaptan products, but the particle-laden flume usually associated with the wood pulp industry have become highly undesirable.
It is an object of this invention to provide a process capable of replacing and/or acting as a standby alternate for the heretofore used black liquid recovery furnace used in the paper pulp industry.
According to the present invention, there is provided a method of continuously processing a stream of black liquor, comprising the steps of:
spraying a first portion of said black liquor stream into a burner structure connected to a combustion chamber; injecting air and any necded auxiliary fuel into said burner structure such that the ratio of air to said black liquor stream is less than the stoichiometric requirement of oxygen to totally oxidize said black liquor stream yet is sufficient to maintain stable combustion; spraying the remaining portion of said black liquor stream into said combustion chamber; quenching the total gaseous and solid mineral products of combustion with water or aqueous green liquor capable of inter-cepting and absorbing a portion of said solid mineral products contained in said gaseous stream to form green liquor; collecting said green liquor;
venturi scrubbing the effluent gases of said quenching step with water or aqueous green liquor to remove residual solid mineral matter to form additional green liquor; separating and collecting said additional green liquor and create particulate-free gases; burning said gases; and withdrawing said collected green liquor for use elsewhere. Thus, concentrated black liquor is introduced, like a fuel, into a vertically downfired burner under conditions wherein air is introduced to support the burning at less than ~ _ 4 _ stoichiomctric conditions. 'I'his brings about the oxidation and reforming of the organic constituents into combustible gaseous and inorganic solid components. As a result significant amounts of combustibles, e.g., carbon monoxide, hydrogen and other organic combustible gases are produced. The resulting gases are quenched with a water spray which may comprise recycle green liquor with subsequent separations of vapor and liquid and wet scrubbing operations upon the gas to capture the particulate matter.
- 4a -~,, 108'~860 The vapors therefrom are subsequently burned under oxidizing conditions with the hot products of combustion contacting a waste heat boiler utilized to make steam.
Clean exhaust gases are vented to the atmosphere.
Additionally, the process includes other optional equipment, including sweetening or removal of sulfurous containing products from the resultant combustible vapor products.
As a result this invention provides a black liquor recovery process free from the disadvantages of cost and explosive hazards but yet provides adequate chemical recovery advantages free from air pollution.
FIGURE 1 is a process flow sheet describing the invention.
FIGURE 2 is a partial-sectional view of a typical burner capable of use in the black liquor or the like salt recovery process of this invention.
FIGURE 3 is a frontal view of the injection nozzle taken along the line 3-3 of FIGURE 3.
FIGURE 4 is a top-sectional view of another form of furnace and burner arrangement for burning black liquor.
Before explaining the present invention in detail it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings since the invention is capable of other embodiments and of being practiced or carried out in a variety of ways.
Also, it is to be understood that the phraseology or : ' . ~ . . .
terminology employed herein is for the purpose of description and not of limitation.
Referring now to the drawings and, in particular, to FIGURE 1, black liquor is fed by way of conduit 10 into the system where it may be divided, as for example , 55~ of the flow stream passing through conduit 12 into burner 14 while the remainder of the stream is sprayed into the combustion chamber 16 by way of conduit 18. Air is supplied by way of conduit 20 into the burner such that the burner 14 is operated under less than stoichiometric conditions whereby a large amount of combustibles are created. The gases resulting from the combustion in chamber 16 are caused to pass into a throat section 22 and thence to the quench tank 24.
Prior to entry into the quench tank a liquid is sprayed into the gases via conduit 26. Such liquid is typically green liquor taken from vapor-liquid separating tank 28 and/or the quench tank 24 by the action of pump 39.
Makeup water may be introduced into conduit 26 via conduit 32. Additional portions of green liquor are pumped to conduit 34, where it enters the throat of a venturi scrubber 36. Surplus amounts of green liquor are caused to be taken from the system via conduit 38 for further processing to white liquor or other chemicals capable of being utilized in the pulping or paper making process.
The resulting gases from the vapor-liquid separator 28 are caused to pass through a demisting device 40 thence through conduit 42 to further processing of the gases to -.~ ' ,''' ' ~
.
utilize the BTU content thereof. In the instance shown the gases are caused to enter a preheater 44 formed as a part of the exhaust stack 46 with the outlet thereto passing by way of conduit 48 to a burner 50. Air may also be heat exchanged with the hot exhaust gases in stack 46 by its entry via passageway 52 and outlet 54 to the burner 50. The combustible mixture is then burned in the combustion zone 56 with resulting hot gases caused to flow across boiler tubes in boiler 58 resulting in an output of steam as shown at conduit 60.
The resulting cooled gases are then exhausted via stack 46 into the atmosphere.
An alternate treatment of the gases issuing through conduit 42 is applicable for those processes where the gases contain large amounts of sulfur-containing products as in the Kraft process. As such, appropriate and known types of gas-sweetening processes ~e.g. amine) generally designated by the numeral 70 with any valuable reusable sulfur compounds issuing therefrom passing via conduit 72 back to the process either by way of line 72A to the combustion chamber or by way of 72B to the scrubber intake.
A typical example of the use of this invention is set forth wherein 25,000 pounds per hour of black liquor having 60~ solid material therein at a temperature of 250 F. is finely atomized through a burner. Alternatively only a portion of the black liquor is burned directly in the burner, the remainder being injected into the combustion chamber proper. Air is supplied to the burner at the rate -., of 1,435,2 mols per hour, thus providing 55% of the stoichiometric air requirements of the total black liquor steam being burned. The amount of black liquor fed to the burner must be sufficient to provide a stable flame and sufficient heat for combustion of the remaining portion. The resulting combustion process occurs at 1,800 F. producing 26.7% combustible gases on a dry basis. The combustion chamber is designed so that there is a burning retention time of from 1 to 3 seconds therein.
The resulting combustion gase~ and solids are comprised as follows:
CompoundMols/Hr.
H20 1,046.5 C2 214.8 N2 1,134.4 C0 175.8 H2 316.4 Salts 78.2 Green liquor plus any make-up water is introduced into 2C the gases at the rate of 176.2 gallons per minute (GPM).
This quench process reduces the gases and materials to a temperature within the quench tank 24 to within the temperature range of 180 to 200 F. Green liquor is removed from the system to further processing and use.
This green liquor is removed at the rate of 106.2 GPM
and has a chemical content as follows:
Compound Wt.
Na2C3 7.78 NaHC03 5.23 Na2S 3.34 The resulting gases and any particles therein pass through a venturi scrubber to remove the remainder of the particulate matter, green liquor being injected as the scrubbing medium. Separation is effected within the vapor-liquid knock-out separator. The gases in the separator are at substantially the same temperature as the quench tank. The resulting gases in the effluent from the separator are comprised as follows:
Compound Mols per Hour H20 3,000.3 C2 136.3 N2 113.4 C0 175.8 H2 316.4 Salts -0-It is this particulate-free gas that is then caused to pass into a preheater, thence used as a fuel in a waste heat boiler furnace where combustion of the products occurs, with the heat being utilized to create steam.
Clean gases are then exhausted to atmosphere.
Referring now to FIGURE 2, a typical burner is shown in cross section and includes a housing suitably protected by a refractory and attached to a combustion chamber 82. An air inlet 84 is connected with a plenum 11~82860 chamber 86, which air ultimately enters the inlet zone 88 for passage across the baffle plate 96. Suitable means including an inlet 90 for black liquor provides a conduit to supply the same to an atomizing nozzle 92.
This inlet is adjus~ably secured within a housing 94 which terminates near the nozzle in a conical air deflection baffle 96 having a plurality of openings 98 therein. A suitable ignition device 100 is provided.
Referring now to FIGURE 4, an alternate embodiment of a burner means is provided by a cylindrical housing or combustion chamber 16A about the periphery of which are placed a plurality of burners 14A, 14B, 14C and 14D.
Intermediate thereof are provisions for injecting black liquor as a fine spray at 18A, 18B, 18C and 18D. It is to be understood, however, that other modifications and burner and spray combustion chamber designs are with the purview of this invention.
Modifications of the process herein include the applicability of the process to other sodium base recovery processes typical, however, of those in paper pulp industry, e.g., soda process, etc.
Preferably the input black liquor is over 50%
solids, although liquids containing less solids are also inclusive of the invention. Usually the moisture content is reduced as by evaporative means or the like prior to flow into the process of this invention.
The air to the initial burner is adju.sted to be within the range of 40 to 80~ of the stoichiometric requirements .
of the black liquor. In some instances the burner or burners in which a portion of the black liquor is conducted may be operated at stoichiometric conditions for that amount of black liquor. When the remaining portion of black liquor is injected into the combustion zone the overall less than stoichiometric conditions as taught herein will occur. The temperature within the combustion zone preferably should not be over 2,200 F.
preferably within the range of 1400-2200 F. Residence times may vary from 0.6 to 6 seconds.
In some instances auxiliary or waste fuel is supplied to either the first or second burners 14 and 50, respectively, when needed for additional heat.
~ ecause of the absence of a smelt bed and complete particulate removal prior to heat recovery Applicants' process provides apparatus of lower investment without explosive hazard, boiler and heat exchanger fouling or particulate or odorous emissions, yet utilizing the available fuel energy of the gaseous products from the process. The broadest aspect of this invention is directed to the discovery of first directly burning the black liquor with insufficient oxygen in a burner and secondly the recovery and separation of the gaseous and particulate material by the processes shown herein or by electrostatic precipitation, or use of bag filters after a quench of the resulting products of combustion.
' ~
Claims
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method Or continuously processing a stream of black liquor, comprising the steps of:
spraying a first portion of said black liquor stream into a burner structure connected to a combustion chamber;
injecting air and any needed auxiliary fuel into said burner structure such that the ratio of air to said black liquor stream is less than the stoichiometric requirement of oxygen to totally oxidize said black liquor stream yet is sufficient to maintain stable combustion;
spraying the remaining portion of said black liquor stream into said combustion chamber, quenching the total gaseous and solid mineral products of combustion with water or aqueous green liquor capable of intercepting and absorbing a portion of said solid mineral products contained in said gaseous stream to form green liquor;
collecting said green liquor;
venturi scrubbing the effluent gases of said quenching step with water or aqueous green liquor to remove residual solid mineral matter to form additional green liquor;
separating and collecting said additional green liquor and create particulate-free gases;
burning said gases, and withdrawing said collected green liquor for use elsewhere.
spraying a first portion of said black liquor stream into a burner structure connected to a combustion chamber;
injecting air and any needed auxiliary fuel into said burner structure such that the ratio of air to said black liquor stream is less than the stoichiometric requirement of oxygen to totally oxidize said black liquor stream yet is sufficient to maintain stable combustion;
spraying the remaining portion of said black liquor stream into said combustion chamber, quenching the total gaseous and solid mineral products of combustion with water or aqueous green liquor capable of intercepting and absorbing a portion of said solid mineral products contained in said gaseous stream to form green liquor;
collecting said green liquor;
venturi scrubbing the effluent gases of said quenching step with water or aqueous green liquor to remove residual solid mineral matter to form additional green liquor;
separating and collecting said additional green liquor and create particulate-free gases;
burning said gases, and withdrawing said collected green liquor for use elsewhere.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US59753875A | 1975-07-21 | 1975-07-21 | |
| US597,538 | 1975-07-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1082860A true CA1082860A (en) | 1980-08-05 |
Family
ID=24391943
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA254,183A Expired CA1082860A (en) | 1975-07-21 | 1976-06-07 | Burning process for black liquor |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS5215603A (en) |
| CA (1) | CA1082860A (en) |
| DE (1) | DE2620063A1 (en) |
| FI (1) | FI762029A (en) |
| FR (1) | FR2318976A1 (en) |
| GB (1) | GB1535953A (en) |
| IT (1) | IT1066048B (en) |
| NL (1) | NL7606055A (en) |
| NO (1) | NO762236L (en) |
| SE (1) | SE7608226L (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE448007B (en) * | 1983-04-21 | 1987-01-12 | Skf Steel Eng Ab | PROCEDURE AND DEVICE FOR RECOVERY OF CHEMICALS |
| SE9103707L (en) † | 1991-12-16 | 1993-02-15 | Chemrec Ab | SET TO MAKE HIGH SULFIDITY COOKIES |
| DE19718131C2 (en) * | 1997-04-29 | 1999-10-14 | Krc Umwelttechnik Gmbh | Method and device for the regeneration of a liquid obtained in the power process for the digestion of wood by gasification |
| CN102852020A (en) * | 2011-06-28 | 2013-01-02 | 王新德 | Integrated combination device for physicochemical treatment of black liquid |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2772240A (en) * | 1950-06-10 | 1956-11-27 | Trobeck Karl Gustaf | Method of treating residual liquors obtained in the manufacture of pulp by the sulphate cellulose process |
| FR1161788A (en) * | 1956-10-24 | 1958-09-04 | Improvements in the treatment of liquors containing dry substances with a high calorific value, in particular black liquors from paper mills | |
| GB922774A (en) * | 1961-02-03 | 1963-04-03 | Hans Joachim Zimmer | Utilisation of spent digestion liquors obtained in cellulose production |
| FR1466700A (en) * | 1965-02-02 | 1967-01-20 | Babcock & Wilcox Co | Method and apparatus for absorbing hydrogen sulphide contained in combustion gases |
| FR1481806A (en) * | 1965-06-02 | 1967-05-19 | Mo Och Domsjoe Ab | Process and apparatus for the production of purified hot water by recovering heat from combustion gases emitted in the treatment of cellulose by the sulphite process or the sulphate process |
| SE363651B (en) * | 1969-06-03 | 1974-01-28 | Svenska Cellulosa Ab |
-
1976
- 1976-04-05 GB GB13683/76A patent/GB1535953A/en not_active Expired
- 1976-05-05 FR FR7613412A patent/FR2318976A1/en not_active Withdrawn
- 1976-05-06 DE DE19762620063 patent/DE2620063A1/en not_active Withdrawn
- 1976-06-04 NL NL7606055A patent/NL7606055A/en not_active Application Discontinuation
- 1976-06-07 CA CA254,183A patent/CA1082860A/en not_active Expired
- 1976-06-28 NO NO762236A patent/NO762236L/no unknown
- 1976-06-28 JP JP51076322A patent/JPS5215603A/en active Pending
- 1976-07-12 FI FI762029A patent/FI762029A/fi not_active Application Discontinuation
- 1976-07-19 SE SE7608226A patent/SE7608226L/en unknown
- 1976-07-19 IT IT50489/76A patent/IT1066048B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| NL7606055A (en) | 1977-01-25 |
| IT1066048B (en) | 1985-03-04 |
| NO762236L (en) | 1977-01-24 |
| FI762029A (en) | 1977-01-22 |
| FR2318976A1 (en) | 1977-02-18 |
| GB1535953A (en) | 1978-12-13 |
| DE2620063A1 (en) | 1977-02-10 |
| SE7608226L (en) | 1977-01-22 |
| JPS5215603A (en) | 1977-02-05 |
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