Abstract: The present invention relates to an acrylic acid production equipment which includes a raw material gasification apparatus for converting liquefied propylene into a propylene gas; an oxidation reaction apparatus for converting the propylene gas into crude acrylic acid; and a purification apparatus for converting the crude acrylic acid into acrylic acid, wherein the raw material gasification apparatus includes a heating apparatus in the inside thereof and also includes a heating apparatus in the periphery including at least a bottom of the raw material gasification apparatus, by which not only energy can be effectively utilized, but also it is possible to achieve a stopping operation efficiently and within a short time.

Abstract: A method and integrated reactor system are provided for producing one or more organic acids, organic acid degradation compounds, and combinations thereof, from various types of biomass, including sludge from a pulp and paper mill.

Abstract: It is described a process for thermal hydrolysis and team explosion of biomass, said method comprising the steps of: (i) leading the biomass approximately continuous to a first preheating step and preheat the biomass, (ii) leading the preheated biomass into at least two reactors sequentially, (iii) heating and pressurising the reactor by addition of steam, (iv) keeping the reactor(s) at a certain temperature and pressure for a certain time, (v) leading the heated and pressurized biomass from the reactor(s) to a first pressure relief tank without any substantial pressure reduction and quickly relief the pressure of the biomass by means of a nozzle, in order to disintegrate the biomass, (vi) leading the biomass from the first pressure relief tank to a second pressure relief tank having a lower pressure than the pressure of the first pressure relief tank, (vii) leading the so treated biomass to a downstream facility for subsequent treatment. The invention also comprises a device for thermal treatment of biomass.

Abstract: A molten and cast refractory material having a chemical composition, in weight percent on the basis of oxides, of: —Al2O3: the remainder up to 100%; —MgO: 28% to 50%; —CuO: 0.05% to 1.0%; —B2O3: ?1.0%; —SiO2: <0.5%; —Na2O+K2O: <0.3%; —CaO: <1.0%; —Fe2O3+TiO2: <0.55%; —and other oxide species: <0.5%.

Abstract: A molten and cast refractory material having a chemical composition, in weight percent on the basis of oxides, of: —Al2O3: the remainder up to 100%; —MgO: 28% to 50%; —CuO: 0.05% to 1.0%; —B2O3: ?1.0%; —SiO2: <0.5%; —Na2O+K2O: <0.3%; —CaO: <1.0%; —Fe2O3+TiO2: <0.55%; —and other oxide species: <0.5%.

Abstract: An improved system and method for using polyethylene glycol (PEG) as a processing fluid additive for safely and effectively treating water-wet hogout propellant as well as any other water-wet propellants, explosives and hazardous wastes (solids and liquids) to make them compatible with the MSO process. The method includes the step of applying liquid PEG to the hazardous waste to create a slurry or feedstock that when fed directly into the MSO reactor vessel prevents the occurrence of smelt-water explosions due to the accumulation of dangerous levels of sodium chloride, and/or sodium sulfide in the molten salt bath. The PEG possesses special qualities that make it ideal for this purpose. It is a low cost, low viscosity, commercially available, non-hazardous (per OSHA standards), water soluble, low toxicity chemical that burns cleanly leaving little or no residue.

Abstract: A sulfur-bearing residue treatment system is provided for the recovery of valuable organic components and the reduction of capital costs and operating costs. The treatment system involves the use of a stripping vessel in conjunction with a heating apparatus. All elements of the treatment system may be coupled together to form one integral piece of equipment.

Abstract: Solid waste resource recovery in space is effected by pyrolysis processing, to produce light gases as the main products (CH4, H2, CO2, CO, H2O, NH3) and a reactive carbon-rich char as the main byproduct. Significant amounts of liquid products are formed under less severe pyrolysis conditions, and are cracked almost completely to gases as the temperature is raised. A primary pyrolysis model for the composite mixture is based on an existing model for whole biomass materials, and an artificial neural network models the changes in gas composition with the severity of pyrolysis conditions.

Abstract: Solid waste resource recovery in space is effected by pyrolysis processing, to produce light gases as the main products (CH4, H2, CO2, CO, H2O, NH3) and a reactive carbon-rich char as the main byproduct. Significant amounts of liquid products are formed under less severe pyrolysis conditions, and are cracked almost completely to gases as the temperature is raised. A primary pyrolysis model for the composite mixture is based on an existing model for whole biomass materials, and an artificial neural network models the changes in gas composition with the severity of pyrolysis conditions.

Abstract: Described is a method for discriminating complex biological samples using an array of discrete biological sensing elements immobilized onto a solid support in which constituents bound to the sensor array is directly determined by measuring the mass increase on the surface; data analysis of said method is performed using neutral network or statical based pattern recognition techniques. In a preferred embodiment the liquid sample is tested for the presence of soluble constituent(s) by contacting said sample with said sensor array under specific conditions, removing unbound sample constituent(s), determining the mass increase on the surface and comparising said mass increase data with a reference standard using pattern recognition software.

Abstract: The invention relates to a reactor vessel and method for the gasification of carbon-containing fuel, residual and waste materials using an oxygen-containing oxidizing agent and in a reaction chamber which is designed as an entrained-bed reactor, at pressures between ambient pressure and 80 bar, preferably between ambient pressure and 30 bar, the contour of the reaction chamber being delimited by a cooling system, and the pressure in the cooling system always being held at a higher level than the pressure in the reaction chamber, and the cooling system withstanding the maximum possible pressure difference with respect to the reaction chamber, which has been depressurized to atmospheric pressure, which reactor vessel is distinguished by the fact that cooling channels are formed by webs which are in contact both with a refractory protective layer and with the pressure shell.

Abstract: Process and apparatus for regenerating spent acid liquor includes a primary roasting furnace for evaporating a substantial portion of the liquid from the spent acid to produce acid vapors and partially roasted metal salts. The partially roasted metal salts are transferred to a secondary roasting chamber where the acids adhering to the surface of the metal salts is vaporized and the metal salts are oxidized. The acid vapors from the primary roasting furnace are then transferred to an absorption column to regenerate the acid. The primary roasting furnace is operated at a different temperature from the secondary roasting chamber and has different retention times for the metal salts. The secondary roasting chamber includes a raking device to mix and convey the metal salts during the secondary roasting step to produce a uniformly roasted metal oxide.

Abstract: A method of mixing two or more dissimilar fluids such a gas and a liquid is provided. The method includes the steps of introducing one fluid into the other to form a mixture, inducing cavitation in the mixture to reduce at least one of the fluids to a large number of relatively small units, and distributing the small units uniformly throughout the mixture. In a preferred embodiment, the step of inducing cavitation comprises introducing the mixture into a chamber having a rotating disk formed with a plurality of irregularities such as bores. The irregularities on the rotating disk induce cavitation in the mixture. The cavitation also breaks down van der Waals attractions within the mixture to enhance mixing.

Abstract: Arrangement for understoichiometric gasification of spent liquor from chemical pulp production, comprising an upper reactor part (2), which upper reactor part is provided with a burner (5) for the spent liquor and with an internally clad reactor jacket (4), and lower separating part (8) for separating a phase of solid and/or molten material, formed on gasification, from a phase of combustible gaseous material. According to the invention, at least the upper reactor part (2), with its clad reactor jacket, is surrounded by an outer vessel (1), with a gap (13) being present between the reactor jacket (4) and the outer vessel (1). Connected to the said gap (13) there are one or more inlets (14) and at least one outlet (21) for a coolant medium.

Abstract: A method and an apparatus for controlling a causticizing process, the process comprising slaking, causticizing and white liquor preparation. The slaking is carried out using a slaker into which green liquor and lime is fed to produce lime milk. The causticizing process is controlled by applying a model that describes at least a part of the causticizing process.

Abstract: A method and apparatus for producing clean, sweet, fuel gas for use in a combustion process and for producing other useful products by processing a waste stream from digestion of lignocellulosic material. Essentially, the waste stream is partially oxidized to form hot gases and molten salts. The hot gases and molten salts are then cooled using a quench liquor to form quenched gas and carbonate liquor. Particles are removed from the quenched gas to form a raw fuel gas, preferably by subjecting the quenched gas to a multi-step fume reduction process which includes heat extraction from the quenched gas to reduce particulate load and water content of the quenched gas to form a low fume fuel gas. H2S is removed from the low fume fuel gas using an H2S removal process which is more selective for H2S than it is for CO2, the removing step forming clean, sweet, fuel gas and acid gases.

Abstract: Arrangement in a soda recovery boiler, comprising normal melt chutes (6) for removing molten salt from the recovery boiler (1). The recovery boiler (1) comprises an outlet (8), mounted in the wall of the recovery boiler such that it is situated lower down than the normal melt chutes (6), in which case the molten salt can be removed from the bottom of the recovery boiler substantially through the outlet (8), when the recovery boiler (1) is emptied for maintenance or the like.

Abstract: In a recovery boiler for burning spent liquor of a pulp mill, a combustion chamber has heat transfer walls formed of tubes, at least one vertical heat transfer surface formed of tubes, and superheaters in an upper part of the combustion chamber for recovering heat generated by combustion and for cooling flue gases. The at least one vertical heat transfer surface divides the combustion chamber in a transverse direction into two combustion spaces.

Abstract: A method of removing nitrogen oxides from flue gases of a cellulose pulp mill recovery boiler does so in a cost effective and environmentally friendly manner. In the heat recovery section of the recovery boiler, a peroxide solution (e.g. a water solution containing about 1-35% hydrogen peroxide) is brought into contact with (e.g. sprayed into) the flue gases in the heat recovery section, so that the flue gases and the peroxide remain in contact between about 0.5-5 (preferably between about 1-2) seconds. The majority (e.g. about 60-90%) of the nitrogen oxides are converted to nitrogen dioxide. The temperature of the flue gases at the time of contact with the peroxide solution is between about 300-800.degree. (preferably 400-600.degree.) C. The nitrogen dioxide is removed by scrubbing the flue gases, downstream of the recovery boiler, with an alkaline liquid (e.g. a liquid otherwise used in the pulp mill having a pH of greater than 9) to convert the majority of the nitrogen dioxides into nitrate.

Abstract: Provided is a process for recovering chemicals and energy from spent liquor obtained when producing paper pulp by chemical delignificatation of fibrous raw material. The spent liquor is gasified in at least two reactors, a first and a second stream of solid and/or smelt material and of combustible gaseous material being formed. The formed material is treated in one or more devices (5, 6, 7, 8), whereby a first (9) and a second liquor (27) are formed. The pressure and/or temperature in the first reactor differ(s) from the pressure and/or temperature in the second reactor. In addition, one or more process chemicals are recovered selectively from the formed liquor and/or gas, and are thereafter returned in whole or in part to one or more of the reactors (1, 2) and/or to one or more of the devices (5, 6, 7, 8) for treatment of the formed material.

Abstract: A Pulp Mill Recovery installation for producing liquors containing different concentrations of recovered process chemicals or combustion gasses containing different concentrations of process chemicals from a spent liquor obtained from the production of pulp.

Abstract: Apparatus for safely carrying out pressurized peroxide bleaching of pulp in a bleaching vessel at a consistency exceeding 8%, the bleaching vessel designed for at least 0.5 MPa overpressure, with the pulp being pumped to the bleaching vessel through a mixer at a temperature exceeding 90.degree. C., wherein a bypass conduit is provided to bypass the mixer and wherein a valve is provided in the bleaching vessel, the valve opening when the pressure in the bleaching vessel or an affiliated part thereof reaches a first set point.

Abstract: Methods of increasing the throughput of recovery boilers equipped with at least two levels of injection of air, the methods improving the thermal efficiency of the boiler with oxygen enrichment of the air in at least one level of the combustion air system, at or above the secondary air level. In one method, a black liquor recover boiler having two levels of air injection is retrofitted with a third level of oxidant injection below or at the same level as the original secondary air, and oxygen enrichment is applied to at least the original secondary air stream and the third level air stream. A preferred method is for the third level to be placed at or close to the same level as the black liquor injector ports.

Abstract: A process of improving the heat efficiency by condensation of vapor in concentrated chemical solutions, according to which vapor and a concentrated chemical solution are introduced into an absorber comprising a cooler/condenser. In accordance with the invention, the condensate formed in the condensation process is utilized to dilute the concentrated chemical solution in the absorber, and the heat of condensation and the heat of solution generated from the dilution step are recovered by heat exchanged thereof with a heat-absorbing medium. A plant for performing the process is described, comprising an absorber (1) and a cooler (condenser) associated therewith, and at least one heat exchanger (3) having an inlet and an outlet for supply and withdrawal of a heat-absorbing medium.

Abstract: In the installation for decontaminating a liquid effluent contaminated by at least one organic substance, a gaseous combustible is burned in a reactor to produce a flame containing hydroxyl free radicals OH.degree. and oxygen O.sub.2 and that flame is centered on the geometrical axis of the reactor. A helical flow of liquid effluent is produced on the inner cylindrical wall of the reactor to cause a direct contact between the hydroxyl free radicals and the organic substance contaminating the liquid effluent. Having hydroxyl free radicals present, the organic substance is oxidized in liquid phase. The high temperature of the flame enables completion of the oxidation of the organic substance, in liquid phase, by means of the oxygen O.sub.2 present in the flame. At the outlet of the reactor, the liquid and gaseous products are separated; the liquid product is collected while the gaseous product is evacuated.

Abstract: The invention is directed towards the method of processing of fibrous mass by a chemical agent and the set up needed for the conducting of the process. Fibrous mass is mixed with a gas transfer agent in the mixing cell and goes to the flow-type tube cell which is shaped like a spiral with the 1:18-1:60 ratio between tube and loop diameters. The chemical agent is transferred immediately to the reactor throughout the jets attached to the reactor lengthwise. The process is carried out in a turbulent regime of motion of the reaction mixture with the velocity of 1-50 m/s. The current invention allows to reach the higher effective processing of fibrous mass, to reduce the consumption of the chemical agent and to increase the quality of the processed material. It can be utilized in paper and pulp industry for the processing of cellulose using a bleaching agent.

Abstract: A method of recycling sodium-based salts used for digesting wood in a digester during the manufacture of pulp and paper. The method comprises collecting a black liquor from the digester, concentrating the black liquor, and adding a salt to the black liquor in an amount sufficient to reduce the viscosity thereof. Preferred salts are thiocyanate salts. The black liquor is then oxidized to produce a green liquor and a causticizer added to the green liquor to produce a white liquor containing the sodium-based salts to be recycled. The white liquor is then returned to the digester.

Abstract: Method of reducing corrosion in a power boiler of a pulp mill using biofuel and suspended matter obtained from the waste water treatment of the mill. In the method flue gases obtained from a waste heat boiler are fed into the power boiler, causing the sulfur dioxide contained in them to react with the alkali chlorides in the boiler and the chlorine to form hydrogen chloride.

Abstract: An integrated flue gas treatment and condensing heat exchanger is used to scrub sulfur dioxide from the flue gas produced by a power boiler used in a paper mill operating a kraft process. Sensible and latent heat from the flue gas is recovered and the condensate effluent from the condensing heat exchanger contains valuable chemicals that are returned to and used in the kraft process.

Abstract: The invention relates to a device for dissolving smelt chemicals from recovery boilers, a so-called soda smelt dissolver, and to a process for such dissolution using the device. The device is characterized in that it consists of at least two separate dissolving tanks (I, II), which are connected to each other near the bottom, via a connecting pipe (3), to allow free flow of liquid between them, and of devices for the separate supply to each tank of dissolving liquid and smelt chemicals in dependence on the measured and established chemical concentration in the solution in each of the tanks (I, II), wherein the outlets from the tanks (I, II) can be separately shut off and regulated. The process according to the invention involves using the device and switching over the functions of the different tanks.

Abstract: A system and method for producing product gas using residual waste liquor is described with a gasifier reactor having a fluidized bed located therein. The gasifier reactor is heated to a predetermined temperature range with either an external heater or a second fluidized bed located at a position below the first fluidized bed. A heat exchanger may be positioned in the first fluidized bed and/or the second fluidized bed for indirectly heating the respective fluidized beds. Condensing heat exchanger means recovers heat from the product gas and condenses an acid gas therefrom for recycling the chemicals. A reagent is sprayed in the condensing heat exchanger means to clean the product gas. Pressurization allows the cleaned product gas to be directly fired in a turbine.

Abstract: A method of regulating the temperature in a chemical melt dissolving tank, where chemical melt produced in combustion of spent liquor of a cellulose pulp mill is dissolved in liquid, producing green liquor, provides excellent heat economy, while minimizing the amount of liquid needed to dissolve the melt to produce green liquor at a temperature below boiling. Green liquor produced in the dissolving tank is expanded (and thereby cooled) in a vacuum tank, and a least a significant part of the cooled liquor is returned to the dissolving tank, for regulating the temperature in the tank. The heat energy contained in the generated expansion steam may be used in many different ways, for example, for indirectly heating (e.g. in a heat exchanger acting as a condenser) water or other liquid to a sufficiently high temperature so that the liquid is useful elsewhere in the pulp mill.

Abstract: An integrated, at least substantially self-contained and at least substantially closed-loop combustion process and system for the control of gaseous, ionic, colloidal, liquid or particulate matter, particularly noxious contaminants contained in the off-gas of a combustion unit, the system comprising a:(a) chemical treatment chamber;(b) a reactant source communicating with the treatment chamber and adapted to provide reactant chemicals in contact with the off-gas;(c) a reactant chemical selector associated with the reactant source;(d) a control device communicating with the off-gas within the combustion system for analyzing the off-gas and actuating the selector in response to the analysis to provide reactant chemicals for contact with the off-gas;(e) an expansion chamber communicating with the treatment chamber and adapted to provide a reduced pressure region of treated off-gas received from the treatment chamber means;(f) an exhaust port in the expansion chamber for discharging the off-gas, and(g) cooling me

Abstract: Regeneration of hydrochloric acid by hydrolysis of iron chloride in aqueous solution employs a Pelletiser (5) after preconcentration of acid solution in a "Pre-Evaporator" (1). Pelletiser (5) controls pellet mixture to between 12% and 14% free water by recycling dried solids from Roaster (3), from Screen (7), or from dust removal Cyclone (9), and waste liquid from Preconcentrator (1). Preconcentrator (1) is contacted with superheated gas from Fluid Bed Roaster (3). Rotary Drier (6) dries pellets with a concurrent hot gas stream and the pellets are screened at (7) with oversize being sent to a Mill (8), undersize recycled to Pelletiser (5), and sized feed delivered to Roaster (3). HCl is produced as gas offtake from Preconcentrator (1) and passes via a demisting Cyclone into adiabatic Absorption Process section (11), where weak acid liquor and water (10) are added as required.

Abstract: A kraft black liquor gasification system is provided with a hot flue gas generator which serves both as a means for generating a hot flue gas to warm-up the gasifier in preparation for start-up and as a means for generating an inert purge gas to purge the gasifier of flammable gases in the event of an emergency trip of the gasifier. A control system controls the operation of the burner during warm-up in response to the gasifier temperature and during the purge in response to the purge gas composition and temperature.

Abstract: An oxygen delignification method and apparatus in which a charge of heated wood pulp is reacted with oxygen in the presence of a charge of caustic soda in a plurality of reaction stages located between mixing stages in which caustic is mixed with the wood pulp. The use of the plurality of mixing stages reduces peak pH exposure of the wood pulp that would otherwise occur if the charges of caustic and wood pulp were mixed all at once. Moreover, the caustic mixed in such manner replenishes neutralized caustic and ensures that the average pH level is increased above that in conventional oxygen delignification. The increase in average pH level favors an increase in the delignification. Filtrate from a washing stage is introduced into the mixing stages to prevent wood pulp degradation.

Abstract: This invention relates to a device for thermal decomposition of stock, especially a spent liquor obtained from pulp manufacture, where the gas stream formed in this connection passes through a liquid bath. The decomposition device has a reactor with a chamber in which thermal decomposition takes place, and a separation zone including a liquid bath for separating off components contained in the gas stream leaving the chamber. The separation zone includes a housing for the liquid bath and a tipping chute arranged adjacent the outlet of the chamber, so that the tipping chute at least partially increases in cross-sectional area in the direction of flow of the gas stream.

Abstract: An improved black liquor recovery system for use in a kraft pulping mill is provided. Molten kraft smelt from a black liquor recovery boiler or recovery system is fed into a fluidized bed reactor where it is cooled and solidified to form solid kraft smelt particles. The solid kraft smelt particles are then fed into a dissolving tank containing an aqueous solution to form a green liquor. The green liquor, after clarification, is treated with lime to form a white liquor containing the regenerated pulping chemicals. Waste steam is an especially preferred fluidizing gas for use in the fluidized bed reactor. This process provides improved energy recovery and process productivity, reduction in gaseous sulfur-containing emissions, reduction in landfilled wastes, and improved safety as compared to a conventional kraft smelt treatment process.

Abstract: A system for providing heated fluidized bed gasification of a residual waste liquor provides a bed of granular material and a source of liquor provided to the material bed. An injector is situated in the material bed and communicates with an air source, a fuel source and a steam source. Fuel and air are combusted in the injector and mixed with the steam which forms a combustion product and steam mixture which is in turn injected into the material bed. The combustion and mixing is separated from the bed material by being confined within the injector. The injector is a bubble cap having at least one hole or an injector made of a porous ceramic material.

Abstract: A method of producing oxidized white liquor from white liquor in which sodium sulfide is oxidized to sodium sulfate. In accordance with the method, an oxygen containing gas is contacted with the white liquor at a temperature of at least 110.degree. C. and such that the total pressure of oxygen and water vapor is no less than 9.2 atmospheres during the contacting.

Abstract: A black liquor gasification system intended for use as a replacement for a Tomlinson cycle, Chemical Recovery Unit, and which operates at a temperature below the ash melting temperature thereby removing the potential for smelt-water reactions and explosions. The subject black liquor gasification system is based on the use of a circulating fluidized bed operating at atmospheric pressure that produces dry, recoverable salts as well as low calorific gases to be used within the paper-making process.

Abstract: A reactor for gasification of cellulose-waste liquors, especially black liquor. The reactor includes a reactor cladding a supply for liquor and combustion air in the upper part of the reactor, an outlet opening for gases and other material in the lower part, and a heat-insulating lining at the cladding and bottom part. The lining is arranged at a distance from the surrounding wall, thereby forming a gap for gas or air having a pressure exceeding that in the hearth of the reactor.

Abstract: A method for white liquor oxidation in a kraft mill utilizes a two-stage selective oxidation system in which the first stage is operated to remove sulfide while the second stage is operated to oxidize a significant fraction of the remaining oxidizable sulfur compounds to sulfate. The resulting selectively oxidized white liquor products are used as alkali sources for various process steps in the mill. Optionally, white liquor can be oxidized in a single stage to convert a significant fraction of the oxidizable sulfur compounds to sulfate. Methods for controlling the selective oxidation process are disclosed.

Abstract: The grit conveyance system of a classifier having a wash region above the liquid layer is provided with a vacuum means in the wash region for positive removal of liquids through a metal screen for disposal.

Abstract: Damper apparatus for air ports of a chemical recovery furnace is mounted on a removable windbox faceplate. Damper blades extend from cantilevered arms pivoted at the forward side of the faceplate, with the damper blades being otherwise unsupported, i.e., they are not confined to travel in tracks within the windbox. Rather, a spring or counterweight urges the damper blades against the air port opening whereby the whole mechanism is free for removal as a unit with the faceplate. Cooperatively operable air port cleaning apparatus is also mounted on the faceplate.

Abstract: Damper apparatus for air ports of a chemical recovery furnace is mounted on a removable windbox faceplate. Damper blades extend from a cantilevered arm pivoted at the forward side of the faceplate, with the damper blades being otherwise unsupported, i.e., they are not confined to travel in tracks within the windbox. Rather, a counterweight urges the damper blades against the air port opening whereby the whole mechanism is free for removal as a unit with the faceplate. Cooperatively operable air port cleaning apparatus is also mounted on the faceplate.

Abstract: Nozzles for directing a jet of steam against a spout flow stream of sodium recovery boiler smelt are secured to an articulating anchor mount for the purpose of maximizing the shattering impact of the steam jet upon the smelt flow stream under a wide range of boiler operating conditions.

Abstract: Organic constituents in a liquid, such as a waste water from a municipal or industrial process (e.g. bleach plant extraction liquor from the bleaching of paper pulp) may proceed effectively without the addition of alkali. When the organic constituents are reacted with an oxygen containing gas at appropriate pressure and temperature conditions, oxidized organics and gaseous acidic products of oxidation (e.g. CO.sub.2) that are produced are continuously and immediately removed from the liquid so that they do not significantly contribute to lowering of the pH of the liquid, so that the reaction may proceed and the liquid remain alkaline.

Abstract: Apparatus (10) for the two stage oxidation of white liquor. The reaction vessel includes a central first stage chamber (24) and a second stage annular outer chamber (26). Heated air is first introduced through the outer second stage chamber (26) by pipes (36) and then directed through elements (38, 40, 44) to the central first stage chamber (24) for completion of the oxidation reaction. Unoxidized white liquor with a small amount of black liquor to catalyze the process is introduced to the first stage of the reaction vessel at a temperature in excess of 185 degrees F. Oxidized white liquor is removed from the second stage chamber and air is venter to atmosphere through the stack at the top of the first stage chamber. The second stage is preferably pressurized for greater efficiency.

Abstract: A method of drying black liquor to a dry solids content of about 100% in which water is evaporated from the black liquor by direct heat exchange contact with hot smelt from a recovery furnace in which the dried black liquor is burned.