Abstract: In a method of thermal treatment of particles, the particles are blown into a hot gas stream by means of a reactor blower. In a circle around a fuel jet and through an entry opening the particles are blown through a diffuser into the bottom of a vertically oriented cylindrical reactor chamber of a suspended gas rector. They are passed through an exit opening at the top of the reactor chamber. During this process the fuel gas stream, which is produced by a burner and is directed into the reactor chamber, forms a convective stream with the particles located therein. Particles that exceed a certain predetermined maximum size are fed into a part of the reactor chamber that is above the diffuser.

Abstract: A method for the heat treatment of finely granular material, particularly for the production of cement, employs a multi-stage cyclone preheater, a rotary tubular kiln, a cooler, and a single kiln off-gas line which is formed between the rotary tubular kiln and the cyclone preheater and is flown through substantially in upward direction by the off-gasses of the rotary kiln and to which tertiary air is fed in two partial-streams for the combustion of additional fuel. The method employs steps of feeding fuel to a lower partial stream of tertiary air, directing material to be treated above a second partial stream of tertiary air, and applying precalcined material in countercurrent with the off-gas line below the tertiary air.

Abstract: In a method and apparatus for the heat treatment of gypsum or like heat material, in which the material is heated in a vessel by indirect heat exchange with hot gas produced by the fluidized combustion of a fuel, material is fed into a first fluidized bed of the material. Partially treated material is removed from the lower region of the first bed and introduced with the assistance of compressed air into the upper region of a second fluidized bed. Treated material is removed from the second bed. The beds of material are both fluidized by means of the introduction of the hot gas product of the fluidized combustion bed, further heating the beds. The first bed may be operated at a lower temperature than the second bed, although both beds may receive substantially the same heat input.

Abstract: An apparatus and method for drying or otherwise treating materials within a controlled environment are provided. Included is a combination of features that imparts a fluidized state to particulate materials on a foraminous conveyor belt, which features also permit selecting other modes of operation including downflow of treating gas to and through the foraminous conveyor belt and upflow of treating gas to and through the foraminous conveyor belt. By this arrangement, a single apparatus can be used to accomplish a plurality of different treatments by selectively adjusting treatment variables.

Abstract: An improved flame holder based tunable pulse combustor, and a processing system employing same. The processing system is for thermal, chemical, and physical processes which employ natural acoustic modes in a processing chamber to enhance the processing. An acoustically resonant processing chamber is provided as the processing vessel. A frequency tunable pulse combustor comprising a flame holder is positioned to excite natural acoustic modes in the processing chamber. Material introduced into the processing chamber is thereby subjected to acoustic pulsations while the material is being processed. The acoustic excitations in the system result in improved moisture removal and particle heating. Also disclosed are various embodiments of frequency and amplitude tunable pulse combustors which may be employed to excite the natural acoustic modes in the processing chamber, including axially translatable acoustic decoupler and flame holder configurations.

Abstract: A process for enhancing heat transfer between combustion products formed in a fluidized bed combustion (FBC) reactor and the water-containing tubes surrounding the reactor wherein particles of an inert material, e.g., mineral calcium sulfate (gypsum), having a spheroidal shape ranging in size from about 50 to 1000 .mu.m and having a Moh's hardness of between 2.0 and 4.0 are introduced into the reactor in the presence of a solid fuel and an oxygen-containing gas. Introduction of such particles into the FBC reactor increases the particle density within the reactor thereby increasing radiant and convective heat transfer between the circulating bed and the surrounding water cooled walls. The improved process allows more precise control of the operating temperature regime. Erosion of the reactor walls is also substantially reduced.

Abstract: A fluidized-bed activation furnace for activated carbon is disclosed. The furnace is provided with a central hollow pillar having an outlet for discharging activated carbon granules at the upper portion thereof, a bowl-shaped cap covering the top portion of the central hollow pillar and a perforated plate fixed to the outer periphery of the central hollow pillar below the outlet for discharging activated carbon granules. After the granules of carbon are activated while a fluidized-bed is formed of the activated carbon granules, the substantially whole amount of granular activated carbon is discharged in a short time maintaining a high temperature.

Abstract: A method and apparatus for the manufacture of cement from raw cement meal wherein the meal passes through a series of preheating cyclones, through a calcining zone, through a rotary sintering furnace and to a cooler with the flow of meal from a penultimate cyclone heat exchanger divided into subflows with one chamber receiving air from the cooler and also receiving burning fuels that are extremely difficult to burn and both calcining chambers delivering meal to the last heat exchanger for delivery to the furnace.

Abstract: A plant for manufacturing cement clinker is constituted by the following portions: a suspension preheater for preheating a cement material powder; a spouted-bed type furnace for granulating the preheated cement material powder; a fluidized-bed type furnace for sintering the granulated cement material powder; a cooling system for cooling the granulated and burned product; a plurality of burners disposed at a lower portion of the spouter-bed type furnace so as to oppose to one another such that their ends are directed obliquely upward and direct streams of fuel to converge on a central axis of the spouted bed, thereby to form a local hot region in the spouted bed; a preheated material charging chute disposed slightly above the local hot region and adapted for charging the preheated material powder from the suspension preheater into the spouted-bed type furnace; and a granulated material discharging chute provided on one side of the local hot region.

Abstract: Process and apparatus for fluidized bed mixing of fluids and gases in which the fluid is injected with a high angular velocity through a relatively narrow, preferably single, orifice (3). The angular velocity may be imparted by injecting the fluid at high velocity tangentially at the periphery of the squate chamber (4) so that angular momentum is gained as it spirals inwards towards orifice (3). Optionally, an open-topped hopper (5) for solids is suspended above orifice (3). The lower end of the hopper (5) terminates in a second orifice (7) located vertically above orifice (3). The solid particles are thereby swept radially outwards towards the wall of the chamber (1) in co-current admixture with the fluid.

Abstract: A fuel burning power plant comprises a bed vessel with a bottom grate which divides the bed vessel into an upper combustion chamber and a lower part with at least one ash chamber. The bed grate consists of parallel air distribution tubes each with air nozzles, between which tubes gaps are provided where bed material may pass from the combustion chamber down to the ash chamber. Below the tubes there is a transverse air distribution chamber. The tubes are connected in groups to the air distribution chamber by a double-walled sleeve extending down from the tubes.

Abstract: A novel melting gasifier (7) is disclosed, in which material at least largely comprising metal is melted in a fluidized bed. The latter is maintained by oxygen-containing gas laterally injected through approximately equidistant nozzles in the lower part of the melting gasifier. A carbon carrier and from above the material to be melted are also introduced into the melting gasifier. Over at least part of the fluidized bed height, the gasifier has a horizontal cross-section, which has different dimensions in two directions perpendicular to one another. The nozzles can project by different amounts into the gasifier vessel.

Abstract: The invention relates to apparatus for the heat treatment of fine-grained material with a rotary drum furnace, a preheater and a combustion chamber for precalcination, in which the cover of the combustion chamber has a central recess which serves for spin stabilization and has the fuel supply provided in its base. Such a combustion chamber is distinguished by improved combustion conditions, particularly an improved mode of combustion.

Abstract: A pulse combustion energy system including a pulse combustor coupled to a processing tube for flowing material to be processed therethrough, the processing tube being coupled to a pair of cyclone collectors for receiving the material flowing therefrom. An optional recycling section is coupled to the cyclone collectors for flowing vapor from the cyclone collectors back to the upstream end of the processing tube. The pulse combustor includes a rotary valve, a combustion chamber, an inner tail pipe and an outer tail pipe. The combustion chamber and inner tail pipe are conical and tubular sections mounted in longitudinal compression, and the compressive forces are transmitted externally across the junction of the combustion chamber and tail pipe by a strongback assembly. The rotary valve includes first, second, and third closely adjacent cylinders defining an interior air chamber. The cylinders have radially oriented, substantially aligned apertures which define an air intake.

Abstract: A pulse combustion dehydration apparatus includes a pulse combustor designed to operate with a low pressure fuel gas supply and having valve means to stop the supply of gas to the combustion chamber during high pressure portions of the pulse combustion cycle. Gas enters the combustion chamber through a fuel distributor having a series of radial gas outlets downstream of an annular flame trap through which combustion air is admitted to the combustion chamber from an air cushion chamber. These features increase the amplitude of the combustion cycle and reduce the amount of residual flame in the combustion chamber, resulting in a strong cycle. An air bypass pipe from the air cushion chamber to the exhaust pipe apparently increases the compression in the combustion chamber from the returning pressure waves. The deydration apparatus further includes a rotary drum into which material is to be dehydrated is delivered in the exhaust gas stream from the exhaust pipe of the pulse combustor.

Abstract: According to the invention, a combustion apparatus includes an upright type combustion chamber having a bottom, conduit means extending below and along the bottom of the combustion chamber and having a nozzle which passes upwardly through the bottom and opens into the combustion chamber, a ringed body supported in the combustion chamber with a gap formed between the lower edge of the ringed body and the bottom of the combustion chamber, air blasted from the nozzle passing through the ringed body, a heating medium contained in the combustion chamber. Particles of the heating medium blasted by the action of the nozzle from the lower part of the ringed body are circulated through the inner bore of the ringed body.

Abstract: A method of controlling the particle size distribution in a fluidized bed reactor in which a primary bed of particulate material having a varying size and including fuel is established. Air is introduced into the bed to fluidize the material and promote the combustion of the fuel. A portion of the particulate material is discharged from the bed and into a secondary bed. Air is introduced to the secondary bed at a velocity sufficient to fluidize the particulate material and entrain some of the finer portions of the particulate material. The air and the entrained finer material from the secondary bed are passed back to the primary bed and the velocity of the air introduced to the secondary bed is varied to vary the amount of the finer material that is entrained and thus control the size of the material in the primary bed.

Abstract: A tubular reactor for heat treatment of granular material in suspension has a vessel (1) up through which a flow of gas and burning fuel passes. The vessel contains vanes (20) which cause the gas to follow a helical path and fling outwards entrained material, which falls down the vessel wall and is displaced inwardly by frusto-conical rings (30).

Abstract: Fluidized bed apparatus 1 for use in heat treating metal articles in a bed of fluidized particles 6 includes a heat insulated structure 2 and a removable module 4. The module is a metallic assembly integrating a vessel 5 for receiving the fluidizable particles, a bottom plate 8 of the vessel having a plurality of gas inlet nozzles 9, and a gas plenum chamber 11 fed by a gas admission conduit comprising a gas duct 12 and an entry pipe 13. Each nozzle 9 comprises a vertical inlet pipe 25 and a distinct cap 26 of specific channel design mounted on top of the pipe for deflecting a fluidizing gas flow into the particle bed 6.

Abstract: A grain drying system includes a fluidized bed for burning grain dust. The hot gases produced by the combustion of the grain dust are directed to a cyclone for cleaning and then to a known grain dryer. The ashes or other particles removed from the hot gases by the cyclone are returned to the fluidized bed.

Abstract: A fluid bed reactor for treatment of refractory materials with a hot fluidizing gas and a method to use same. Both the refractory materials and the fluidizing gas are introduced from the top of the reactor. Unusually high reaction temperatures of up to 2000.degree. C. are maintained in the reaction chamber due to the presence of heating elements within the reactor and due to countercurrent heat transfer.

Abstract: A compact, self-contained apparatus and method for expanding loose fill foam material for packaging includes an eductor having a fan, a venturi chamber, and a wire mesh cage arrangement for automatically feeding expandable loose fill material to a hopper. The loose fill material is then uniformly fed through the hopper by air pressure in conjunction with gravity to an expansion chamber. The expansion chamber includes a stepped conveyance platform disposed over a stepped steam chamber, and a track arrangement for simultaneously conveying and tumbling the loose fill material across each conveyance platform step. A condensing unit disposed above the expansion chamber removes excess moisture from the expansion chamber and provides warm dry air to a discharge housing from which the expanded loose fill material is discharged from the expansion chamber.

Abstract: An improved pulsating processing system for thermal, chemical, and physical processes which employs nonlongitudinal acoustic modes in a processing chamber to enhance the processing. An acoustically resonant processing chamber is provided as the processing vessel. A frequency tunable pulse combustor or other selectively variable frequency acoustic exciter is positioned to excite natural nonlongitudinal acoustic modes in the processing chamber. Material introduced into the processing chamber is thereby subjected to nonlongitudinal acoustic pulsations while the material is being processed. Also disclosed is an improved frequency and amplitude tunable pulse combustor which may be employed to excite the natural acoustic modes in the processing chamber. One disclosed embodiment is a system for drying a slurry of material such as kaolin. The nonlongitudinal acoustic excitations in the system result in improved moisture removal and particle heating.

Abstract: Upper and lower vortex chambers are disposed immediately below a calcining furnace for calcining powdery raw materials. The scattering clinker particles from a fluidized-bed burning furnace are trapped in the lower vortex chamber and are returned to the fluidized-bed burning furnace so that the scattering clinker particles are positively prevented from flowing into the upper vortex chamber and the calcining furnace.

Abstract: There is described a fluidized-bed plant, notably for heat-processing metal goods, such as wires, bars, etc., comprising at least one chamber filled partly at least with a powdered material suspended in a gas, and at least one disperser provided adjacent the chamber bottom, wherefrom the gas may be fed and distributed substantially continuously inside said chamber, which further comprises means to retain a gas re-circulation inside the disperser.

Abstract: An apparatus for remotely calcining a slurry or solution feed stream of toxic or hazardous material, such as ammonium diurante slurry or uranyl nitrate solution, is disclosed. The calcining apparatus includes a vertical substantially cylindrical inner shell disposed in a vertical substantially cylindrical outer shell, in which inner shell is disposed a fluidized bed comprising the feed stream material to be calcined and spherical beads to aid in heat transfer. Extending through the outer and inner shells is a feed nozzle for delivering feed material or a cleaning chemical to the beads. Disposed in and extending across the lower portion of the inner shell and upstream of the fluidized bed is a support member for supporting the fluidized bed, the support member having uniform slots for directing uniform gas flow to the fluidized bed from a fluidizing gas orifice disposed upstream of the support member.

Abstract: A fluidized bed reactor (1) comprising a reactor chamber (4) having a gas distributor plate (5) for feeding primary air, and a space above said distributor plate (5) is divided into compartments (6) by means of partition walls (7) having discharge openings (9) for feeding secondary air to the circulating bed.

Abstract: A conduit extends through the bottom of an upright type combustion chamber and terminates in a nozzle. A heating medium is contained in the combustion chamber and forms a naturally formed substantially conical shape having an apex. An intake port is provided at the bottom of the combustion chamber at a position corresponding to the apex of the conical shape and extends to the conduit. Particles of the heating medium which are ejected from the nozzle, via the conduit and the intake port, roll along the conical surface of the heating medium and fall into the intake port.

Abstract: Tendrillar carbonaceous material is used as a fluidization aid for fluidized beds. The tendrillar carbonaceous material can be used to fluidize cohesive solids. Further, it can be used to improve fluidization of particulate solids by reducing entrainment, eliminating bubbling, and/or eliminating channelling. The tendrillar carbonaceous material can be a fibrous, particulate carbonaceous material comprising carbon fibers and a ferrous group metal component dispersed thoughout the carbon fibers as nodules. The tendrillar carbonaceous material has a bulk density of from about 0.01 to about 0.7 g/cm.sup.3 and comprises an agglomeration of tendrils having a diameter of from about 0.01 to about 1 micron and a length to diameter ratio of from about 5:1 to about 1000:1.

Abstract: Tendrillar carbonaceous material is used as a fluidization aid for fluidized beds. The tendrillar carbonaceous material can be used to fluidized cohesive solids. Further, it can be used to improve fluidization of particulate solids by reducing entrainment, eliminating bubbling, and/or eliminating channelling. The tendrillar carbonaceous material can be a fibrous, particulate carbonaceous material comprising carbon fibers and a ferrous group metal component dispersed throughout the carbon fibers as nodules. The tendrillar carbonaceous material has a bulk density of from about 0.01 to about 0.7 g/cm.sup.3 and comprises an agglomeration of tendrils having a diameter of from about 0.01 to about 1 micron and a length to diameter ratio of from about 5:1 to about 1000:1.

Abstract: The invention relates to a method of reclaiming contaminated industrial sand including the steps of subjecting the sand to the influence of heat in a fluidizing bed, forcing sand fed to said bed to follow a flow path including a plurality of generally heightwise directed path portions including at least one generally upwardly directed path portion and at least one generally downwardly directed path portion. In an example of the invention, the heat is applied to the sand in a first group of path portions and the sand is cooled in a second group of path portions.

Abstract: There is disclosed a process for producing dried and cleaned metal chips by entraining metal chips in a gas, introducing the gas into a cyclone separator having a wall heated to fluid-vaporizing temperature by combustion effected in a surrounding chamber, purging fluid from said chips, exhausting hot gases and exiting dried metal chips from said separator, conducting hot gaseous products of combustion from the combustion chamber to a continuous centrifuge, extracting extractable fluid from starting metal chips, which may be previously uncleaned and/or unwashed, in the centrifuge, entraining the chips in the hot gaseous products of combustion introduced into the centrifuge, and conducting the gaseous products with entrained chips from the continuous centrifuge to the cyclone separator, thereby providing an essentially closed system.

Abstract: Apparatus for the heat treatment of fine material comprises a multi-stage cyclone preheater, a rotary kiln and a calciner supplied with tertiary air from a cooler for precalcination of the preheated fine material. The tertiary air pipe is narrowed at the point where it joins into the calciner. In this way an intensification of the mixing together of material, fuel and gas is achieved as well as an improved combustion, particularly fuels which are slow to react.

Abstract: According to the present invention, white cement clinker particles are not burned in a rotary kiln and the burned clinker particles are not immersed in the water to be cooled. White cement clinker raw materials are burned in a fluidized bed burning furnace with a fluid bed or a spouted bed and the clinker particles thus burned are reduced with a reducing gas. The clinker particles thus reduced are first cooled with the water which is sprayed over the clinker particles and then further cooled with the air. The white cement clinker raw material particles fed into the fluidized bed burning furnace are burned into clinker particles while forming a fluidized bed and then the clinker particles thus burned drop through a jet injection pipe into a reduction chamber disposed below the burning furnace and are reduced. The clinker particles thus reduced are rapidly cooled to 600.degree.-700.degree. C.

Abstract: A process and apparatus for manufacturing low sulfur cement clinker from cement raw meal containing sulfur or with fuel containing high levels of sulfur or a combination thereof. The process is carried out in an apparatus which includes a preheater, calcining furnace, clinkering furnace and clinker cooler. A separate source of fuel is added to the feed end of the kiln to maintain reducing conditions and temperatures for decomposing the sulfur compounds. Fresh air is added to the riser duct connecting the clinkering furnace with the calcining furnace and the preheater for converting sulfur dioxide to sulfur trioxide. Calcium oxide is added to the riser duct for absorbing the sulfur trioxide to form calcium sulfate. The calcium sulfate is then removed by a gas solid separator from the system. Excess fuel added to maintain reducing condition at the feed end is utilized in the calcining furnace.

Abstract: Fluidized bed apparatus includes a body having located therein a distributor provided with discharge ports connected to classifiers. Plates are located over the ports and air lances are disposed intermediate the plates and the ports. The plates serve to protect inbed tubing from erosion by entrained particles and the lances control the flow of material into the classifiers.

Abstract: There is disclosed a process for producing dry metal chips by entraining fluid-containing metal chips in a gas, introducing the gas into a cyclone separator having an internal wall heated to fluid-vaporizing temperature by combustion in a surrounding chamber, purging and vaporizing fluid from said chips, exhausting hot gases and exiting dried metal chips from said separator, conducting hot gaseous products of combustion from the combustion chamber to a continuous centrifuge, extracting extractable fluid from starting metal chips in the centrifuge, entraining the chips in the hot gaseous products of combustion introduced into the centrifuge, and conducting the gaseous products with entrained chips from the continuous centrifuge to the cyclone separator, thereby providing an essentially closed system. The combustion chamber may be a part of an afterburner furnace and hot gases entraining vaporized oil exhausted from the cyclone separator may be recycled and employed as fuel for the combustion chamber.

Abstract: An improved apparatus for roasting fine material which includes recirculation of at least partially roasted material through the roasting furnace for further roasting. An adjustable gate is included in the recirculation system for controlling the quantity of material recirculated. A high temperature fluidizing gravity conveyor is used in the recirculation system to maintain a low profile for the system. The invention utilizing a system for classifying large particles so that they may be removed from the recirculation system. Gas locks are included for preventing the short circuiting of hot gases. The system also includes overflow conduit in the event of a plug or blockage in the system.

Abstract: A method for the pyrolytic destruction of microfilm products by utilizing hot silicon oil heated to a temperature of about 250.degree. C. Destruction of the various types of microfilm is accomplished within a five minute time frame.

Abstract: Improved construction for the dehydration sections of pulse jet combustors for the drying of particulate materials including provisions for maintaining the surface of the downstream end thereof at elevated temperatures.

Abstract: An improved pulsating processing system for thermal, chemical, and physical processes which employs nonlongitudinal acoustic modes in a processing chamber to enhance the processing. An acoustically resonant processing chamber is provided as the processing vessel. A frequency tunable pulse combustor or other selectively variable frequency acoustic exciter is positioned to excite natural nonlongitudinal acoustic modes in the processing chamber. Material introduced into the processing chamber is thereby subjected to nonlongitudinal acoustic pulsations while the material is being processed. Also disclosed is an improved frequency and amplitude tunable pulse combustor which may be employed to excite the natural acoustic modes in the processing chamber. One disclosed embodiment is a system for drying a slurry of material such as kaolin. The nonlongitudinal acoustic excitations in the system result in improved moisture removal and particle heating.

Abstract: Improved longitudinal axis feed system for the dehydration section of pulse jet combustion apparatus used for the drying of particulate materials.

Abstract: Pulse combustor apparatus for the drying of particulate materials having the combustion chamber and the exhaust system components disposed on a common longitudinal axis and wherein backflow gas flowing through an adjacent augmenter duct is directed into encircling relation with the downstream exhaust system components to control the temperature conditions therewithin.

Abstract: A process for thermal treatment of solid particles in a fluidized bed wherein the solid particles by thermal treatment form a lighter weight fraction and a heavier weight fraction, relative to the total contents of the bed. The process is characterized by use of a selective heavier particle discharge conduit in the sloping bed support and maintenance of a discrete fluid fueled flame in close proximity to and above the opening to the heavier particle discharge conduit. This forms a higher temperature zone in and surrounding the flame, at least about 100.degree. F. higher than the remainder bed temperature. Circulation of solid particles through the flame and its surrounding higher temperature region is promoted both by directing of fluidization gas jets in the fluidized bed support and by the jetting action of the upwardly flowing heavier particle discharge gas.

Abstract: A method and apparatus for producing cement which includes intermixing the cement forming raw materials with water, coal or coke cement as a binder and forming this mixture of materials into nodules by pelletizing or extrusion. The system is particularly designed for use in making white cement where raw materials low in coloring compound are used as raw feed. The nodules are then sized to obtain a feed material having a size range on the order of one quarter inch by 14 mesh which is suitable for use in a fluidized bed reactor. The nodulized raw material is thermally processed in a fluidized bed reactor at temperatures in the range of approximately 2500.degree. to 2700.degree. F. for white cement and 2350.degree.-2450.degree. F. for typical gray Portland Cement. The coal or coke mixed with the raw material serves to supply between 60% and 90% percent of the fuel required for the process with the remainder being supplied directly to the fluidized bed.

Abstract: A method and apparatus for calcining an aluminum hydroxide source to an aluminum oxide in which the amount of the .alpha.-modification can be controlled from very low to very high values. In accordance with the present invention, the calcination of the source material takes place in two stages, in the first of which the material is preheated with air and then passed to a fluidized bed calciner after which it is delivered to a holding cyclone. In the second stage, the previously calcined material which may contain up to about 80% of the .alpha.-modification is calcined further in a rotary tubular kiln which is followed downsteam by a cooler.

Abstract: There is here disclosed a calcining apparatus for a powdery material comprising a first preheating series composed of a calcining kiln and preheaters at a plurality of stages for heating the powdery material with an exhaust gas from the calcining kiln, a second preheating series composed of other preheaters at a plurality of stages for heating the powdery material with an exhaust gas from a rotary kiln, and a gas carrying pipe for connecting the first and second prehating series in the middle thereof, a flow path for the powdery material being adapted so that the powdery material fed to each series may be led into the rotary kiln via a combining duct disposed in front of the undermost preheaters in both the series and then via the undermost portions of both the series. Further, disclosed is a calcining apparatus for a powdery material in which a sub-calcining kiln and a calcining chamber are disposed on an exhaust gas pipe extending from a rotary kiln.

Abstract: An apparatus and process for calcining gypsum is disclosed which utilizes a flash furnace for rapidly calcining fine particulate gypsum while the material is suspended in a stream of hot gas. The method and apparatus utilize a two-stage suspension preheater for utilizing waste gases from the calcining furnace for preheating raw material to be calcined and a two-stage suspension cooler for cooling hot calcined gypsum which is discharged from the calcining furnace. Spent cooling gas is supplied to the preheater for use in preheating the fresh gypsum to be calcined. The invention also contemplates recirculating a portion of the gypsum discharged from the furnace back to the furnace for further calcination. Hot product may be discharged directly from the furnace.

Abstract: A device for varying the height of a bed in a fluidized combustion chamber inside a pressurized housing. Bed material is supplied to the chamber from hoppers or returned back to the hoppers from the chamber through a supply line. The supply line connects the chamber and the hoppers. The hoppers have means of increasing or decreasing the pressure. To improve the means of both increasing and decreasing pressure in the known device and of cleaning the gas that enters into contact with the material in the hopper, each hopper contains a hot-gas filter that gas can flow through in two directions and each hopper communicates above the filter with a gas connection that can be maintained at either a higher or a lower pressure than the fluidized combustion chamber.

Abstract: A fluidized bed reactor (1) comprising a reactor chamber (4) having a gas distributor plate (5) for feeding primary air, and a space above said distributor plate (5) is divided into compartments (6) by means of partition walls (7) having discharge openings (9) for feeding secondary air to the circulating bed.