Abstract: A fluidized bed combustion system in which a separator receives a mixture of flue gases and entrained particulate material from a fluidized bed in a furnace. A loop seal valve, in the form of three ducts, connects an outlet of the separator to the furnace for recycling the separated particulate material back to the furnace. One of the ducts extends vertically from the separation and another duct extends horizontally from the latter duct and connects this latter duct to an angled duct which registers with an opening in the furnace wall. The last duct is angled downwardly to provide an increased throughput when compared to standard loop seal devices.

Abstract: When burning solid fuels in a combustor, which operates with a circulating fluidized bed, substantially oxidizing conditions are maintained in the lower parts of the combustion chamber and approximately stoichiometric conditions in the upper parts of the combustion chamber, and afterburning of the flue gases separated from the bed particles is carried out.

Abstract: A process for the continuous fluidized bed agglomeration of a solid in powder form, wherein the powder, a granulating liquid and propelling air are fed through a three-substance nozzle into the center of a fluidized bed to form a three-phase mixture in the center of the fluidized bed.

Abstract: An apparatus for carrying out a physical and/or a chemical process, such as a heat exchanger, a reservoir, in which a fluidized bed of granular material is present, is provided with upwardly directed tubes to a top box. Particles circulate up through the tubes, to a downcomer arranged outside the reservoir. The top of the downcomer is connected to a separating device, and the bottom of the downcomer opens into a collecting reservoir. The collecting reservoir communicates via a valve with the fluidized bed in the reservoir.

Abstract: A fluidized bed combustion system in which a separator receives a mixture of flue gases and entrained particulate separated material from a fluidized bed in a furnace. A pressure seal valve connects an outlet of the separator to the furnace or a fluidized bed heat exchanger disposed adjacent the furnace for recycling the separated particulate separated material back to the furnace. The pressure seal valve includes a downflow leg, and upflow leg and a horizontal leg connecting the downflow leg to the upflow leg. A horizontal overflow leg is connected to the upflow leg and at least two return legs connect the overflow leg to the furnace. The separated material from the separator passes through the legs of the pressure seal valve and sometimes through a heat exchanger (if included) before reentering the furnace.

Abstract: A fluidized-bed combustor combusts combustible material smoothly while smoothly removing any incombustible material or components from the fluidized-bed furnace without depositing the incombustible material or components therein. The fluidized-bed combustor has a first diffuser plate, a second diffuser plate each having a plurality of fluidizing gas supply holes, and an incombustible material discharge port disposed between the first diffuser plate and the second diffuser plate. A portion of the fluidizing gas is supplied from the incombustible material discharge port to generate an uninterrupted fluidized bed on the bottom of the fluidized-bed furnace. The first diffuser plate has a downwardly inclined surface directed toward the incombustible material discharge port, and the second diffuser plate has an upwardly inclined surface which is progressively higher away from the incombustible material discharge port.

Abstract: A fluidized bed combustion system in which a partition is disposed in an enclosure to divide the enclosure into two furnace sections for receiving beds of combustible particulate material. Air is introduced into each bed in quantities sufficient to fluidize the material and insufficient to completely combust said material, and additional air is introduced through said partition and into said sections in quantities sufficient to completely combust said material. An equalization port is provided through the partition for equalizing the pressure between the furnace sections.

Abstract: Methods and Systems for catalyzing the oxidative destruction of animal tissues, particularly medical waste and animal and human corpses. A reaction chamber containing a fluidizable media is maintained at a temperature sufficient to cause the fluidized media, typically silica sand, silica gel, or alumina, to become highly reactive in the presence of moisture. Typically the reaction chamber is maintained at a temperature in a range from about 400.degree. C. to about 500.degree. C. The methods and systems quickly and efficiently destroy medical waste and a variety of other animal tissues such as corpses. The apparatus can be small to fit into small rooms or large to serve institutional needs. It replaces incineration, autoclaving, plasma formation, and the like as the preferred method for effectively disinfecting and destroying medical wastes and corpses.

Abstract: A method of and apparatus for detecting an abnormality of a fluidized bed boiler is characterized in that an abnormality of the fluidized bed boiler is detected on the basis of a physical quantity related to a condition change of a gas existing in a space defined by a pressure vessel and the fluidized bed boiler accommodated within the pressure vessel.

Abstract: A combustion apparatus includes a combustion chamber having a bottom portion, and a blower for supplying air. An air blowing section is provided at a lower portion of the combustion chamber and blows out the air supplied from the blower toward the bottom portion. As a result, air is moved toward the bottom portion in the center portion of the lower portion of the combustion chamber in a radius direction and combustion gas rises upwardly along a wall of the combustion chamber. Therefore, a maximum combustion temperature portion is confined in the vicinity of the bottom portion by a forced air flow. Also, the combustion temperature in the lower portion of the combustion apparatus is high and that in the upper portion thereof is low. That is, the combustion temperature distribution is inverted, compared to that in the conventional combustion apparatus.

Abstract: Unreacted gas generated at outside is introduced through a gas inlet tangentially into a secondary combustion chamber with a substantially cylindrical side wall, so that a spiral ascending flow of the unreacted gas is generated in the chamber. A bulk material in the chamber is blown up by the unreacted gas introduced through the gas inlet to be circulated in the chamber so as to substantially completely burn unburnt solids entrained in the unreacted gas.

Abstract: The invention concerns a method and a device in the cooling of the circulating material in a fluidized-bed boiler. In the method the fuel (A) is introduced into the circulating-powder combustion chamber (10) of the fluidized-bed boiler into the lower part of the circulating-powder combustion chamber (10) and an inert circulating material, which contains a proportion of unburned powdered fuel (A), is circulated from the top part of the circulating-powder combustion chamber (10) to the lower part of the circulating-powder combustion chamber (10). The flue gases are passed in the method from the powder separator (13) along the duct (15) into the exhaust-gas boiler (16), through whose heat exchanger (16a) thermal energy of the flue gases is transferred further to other useful use.

Abstract: The invention relates to a method for lime sludge reburning in a fluidizing bed. The method is characterized in that a cooling medium (10) is injected immediately above the fluidizing bed (3). The invention also comprises means for performing the method. The arrangement which is known per se is provided with an injection device (10) for a cooling medium above the fluidizing bed (3).

Abstract: A method of incinerating wastes while controlling the production of dioxins wherein water vapor or water is sprayed in the main combustion zone of an incinerator. An apparatus for practicing the method of waste incineration, including a line for supplying main combustion air, either alone or together with a line for supplying recycled combustion gas, to the incinerator from below its hearth, is provided with a line for supplying water vapor or water in communication with the line or lines.

Abstract: A high temperature furnace and method for thermally decomposing solid combustible fuels into usable products to provide a source of heat to a selected area is disclosed. Solid combustible fuel, such as waste automobile tires, are introduced into a reaction vessel or combustion chamber which is defined by an outer wall. The reaction vessel has an upper portion and a lower portion with a central partition dividing the lower portion into compartments. Each compartment holds a fuel bed having a selected height wherein the sold fuel accumulates as it is being decomposed. Each compartment also has a bottom opening. Air ducts located along the outer wall of the reaction vessel and in the central partition supply pressurized air to the interior of the reaction vessel. An exhaust duct which communicates with the upper portion of the reaction vessel is supplied for venting off combustion or pyrolysis products from the reaction vessel to the selected area.

Abstract: This invention related to aprocessing device such as a calciner or the like. The processing vessel is vertical with concentric cylindrical inner and outer walls, closely spaced and heated for rapid thermal processing, with strong boiling, evaporating, fluidizing and gasifying feed. This vigorous action is helping the steady gravitational movement of feed through the vessel. A top inlet for feed and a bottom outlet for residue are provided. Means for preventing air infiltration and means for controlling flow and keeping vessel filled during processing are provided. Any number of outlets for steam, boiling hot water, fluidized and gasified material at various heights of the vessel. Some material require addition of catalysts to bring about a chemical change and reduction in a pyrolitic process.

Abstract: Method and apparatus for using biofuel or waste material or both for energy production. The biofuel or the waste material is gasified in a fluidized bed gasifier (10), preferably a circulating fluidized bed gasifier. The gas produced in the gasifier is introduced into a boiler (12) equipped with fossil fuel burners (28, 28'28"), typically burners for pulverized coal. The gas is introduced at a level above the burners. Ash from the boiler may be used to form the bed of the gasifier. For control of NO.sub.x, the gas is burned in the upper part of the boiler at a low temperature level of 800.degree.-1050.degree. C. (1472.degree.-1922.degree. F.), preferably 850.degree.-900.degree. C. (1562.degree.-1652.degree. F.), and with a small excess air content of about 5-10 percent. In a second embodiment, the raw gas may be cleaned of harmful or noxious components, and cooled if desired, between the gasifier and the boiler in an additional circulating fluidized bed reactor (152) having a bed of coal ash.

Abstract: A combustion method and apparatus in which combustible matter, e.g., waste matter, coal, etc., is gasified to produce a combustible gas containing a sufficiently large amount of combustible component to melt ash by its own heat. A fluidized-bed furnace has an approximately circular horizontal cross-sectional configuration. A moving bed, in which a fluidized medium settles and diffuses, is formed in a central portion of the furnace, and a fluidized bed, in which the fluidized medium is actively fluidized, is formed in a peripheral portion in the furnace. The fluidized medium is turned over to the upper part of the moving bed from the upper part of the fluidized bed, thus circulating through the two beds. Combustible matter is cast into the upper part of the moving bed and gasified to form a combustible gas while circulating, together with the fluidized medium.

Abstract: A combination reaction chamber and gas/solids separator is provided in a common reactor vessel. The reactor is capable of carrying out various types of gas/solids reactions within the reaction chamber and, contemporaneously, separates the gas from the particulate solids by way of a separator disposed within the reaction chamber. Gas exits the reaction chamber through an outlet disposed along a central axis of the chamber. Solids exit the chamber through an outlet disposed along the outer periphery of the chamber. The reactor provides improved mass transfer rates as well as selective residence times.

Abstract: A method for treating sludge by dewatering to form thick sludge and drying to form dry sludge includes the steps of mechanically predewatering thick sludge to produce predewatered thick sludge and mixing the predewatered thick sludge with non-cooled dry sludge to produce a sludge mixture. The temperature of the sludge mixture to be dried is measured and the dry substance contents of the dry sludge based on the measured temperature is determined. Fluctuations in the dry substance contents of the dry sludge are compensated by controlling the amount of recirculated dry sludge to be mixed with the predewatered thick sludge as a function of the temperature of the sludge mixture to be dried. The sludge mixture is dried to produce dry sludge and a portion of the dry sludge is recirculated to be mixed with the predewatered thick sludge.

Abstract: Method and apparatus for providing a gas seal in a CFB reactor, which is provided with a vertical, slot-shaped return duct (16), and for regulating the flow of circulating mass therein. The gas seal (22) is formed by arranging barrier means (22, 24, 26) on two different levels in the regulation zone of the return duct to slow down the flow of the circulating mass through the regulation zone. The flow of the circulating mass through the regulation zone is regulated by injecting fluidizing gas (56, 58, 60) into the regulation zone.

Abstract: The present invention relates to a combined cycle power plant comprising a air compressor providing pressurized air at pressure greater than 2 bar; a gas turbine means for driving the gas compressor means; a pressure vessel, circular in cross-section, connected to said air compressor and being capable of withstanding pressures greater than 2 bar; a pressurized circulating fluidized bed reactor enclosed by the pressure vessel, the circulating fluidized bed reactor having a reactor chamber, including substantially planar steam generation tube walls having a bottom section; means for leading hot combustion gases away from said reactor; one or more non-circular centrifugal separator(s) disposed within said pressure vessel being adapted to the reactor chamber and internal pressure vessel geometry for receiving and purifying hot combustion gases, having a gas outlet leading from said separator out of said pressure vessel; said centrifugal separator comprising a vertical vortex chamber having distinctly planar steam

Abstract: The waste burning boiler comprises a cylindrical outer wall, a cylindrical inner wall consisting of a plurality of vertical water pipes having the gaps therebetween closed by plate members. The plate members are provided with a plurality of holes communicating the annular chamber between the inner and outer walls with the combustion chamber defined inside the inner wall. Compressed air is introduced into the annular chamber, and is blown into the combustion chamber from these small holes. The air blown from these holes provide a sufficient amount of oxygen for combustion, and raises the combustion temperature. Additionally, the air flow from the small holes provide a favorable stirring effect which improves the transfer of heat produced by combustion to the water pipes.

Abstract: A system and method of operating a pressurized fluidized bed system in which a bed of particulate material is fluidized by distributing air through the bed. A mixture of flue gases and entrained, relatively fine, material from the reactor is passed to a separator and the material is separated from the gases and passed to an external heat exchanger. A portion of the material is cooled in the heat exchanger and it, along with the remaining portion of material, is recycled to the reactor.

Abstract: A fluidized bed hearth floor comprises a supporting metal sheet provided with fluidization-gas injection nozzles. The supporting sheet is made of refractory metal, and is covered with a plurality of flat elements made of refractory metal, each flat element being fixed to the supporting sheet by welding in a localized zone, e.g., substantially at a point.

Abstract: An air nozzle assembly for use in an associated combustion apparatus which includes a secondary air nozzle apparatus. The air nozzle apparatus may be a part of the windbox of an associated furnace. The apparatus includes a housing which has at least a part thereof disposed surrounding a first axis. The part has respective first second third and fourth cross-sectional areas at first, second, third and fourth axially spaced planes that are perpendicular to and axially spaced along the first axis of the part of the housing. The cross sectional area of each of the first second third and fourth cross-sectional areas each different from each other of the cross sectional areas. The apparatus also includes a diffuser member; apparatus for supporting the diffuser; and apparatus for moving the apparatus for supporting along a second axis, the second axis is parallel to the first axis. In some forms of the invention the diffuser member is a rotationally symmetrical object which may be a truncated conical body.

Abstract: The amount of N.sub.2 O emission from a fluidized bed reactor is reduced by adding a hydrogen radical providing additive (e.g. a hydrogen containing fuel such as natural gas or alcohol) to the flue gases discharged from the fluidized bed. Sufficient oxygen is present in the flue gases--either by addition with the additive, or by addition of an excess to the combustion chamber--so that the additive reacts with the oxygen, typically raising the temperature of the flue gases (e.g. from about 700.degree.-900.degree. C. to about 950.degree.-1100.degree. C.) so that N.sub.2 O production is reduced about 10-90%. The additive may be injected in or just prior to a cyclone for separating particles from the flue gases, in a gas discharge immediately after the cyclone (e.g. just downstream of a heat exchanger for cooling the flue gases and flattening the velocity profile of the flue gases), just prior to a superheater of a convection section, or in a combustion chamber just prior to a gas turbine.

Abstract: A system and method are disclosed for lowering NO.sub.x levels in flue gases of a fluidized bed reactor using selective non-catalytic reduction. A reactor is connected to a separator by a duct, and a reactant is introduced into the duct for decreasing NO.sub.x levels in the flue gases passing from the reactor, through the duct, and into the separator. The reactant, such as ammonia or urea, is selectively injected into a gaseous-rich region of the duct, near an upper, inner portion of the duct, so that a high degree of mixing of the reactant with flue gases is achieved while maintaining a low degree of mixing of the reactant with the particulate materials. The point of injection of the reactant into the duct is also at a location nearer to the reactor than to the separator to provide for increased residence time. In this manner, the reactant is used efficiently while obtaining the desired lowering of NO.sub.x levels in the flue gases.

Abstract: The present invention relates to a fastening system for fastening a through pipe to a hearth wall, the pipe opening into a box. The fastening system comprises external pipe-securing means for securing the pipe to said screen, and an internal metal guide tube fitted over said pipe and having one of its ends interposed between said pipe and the orifice through which said pipe passes, its other end being externally threaded. The guide tube carries a rigid washer which is disposed so as to abut against the inside face of the inside layer, and against which a wall of the box is mounted, which wall is provided with an orifice that is larger than the cross-section of the guide tube, a sealing device being clamped against the wall of the box by a nut screwed onto the threaded end of the guide tube.

Abstract: A process of improving overall quality of coals or other solid fuels comprising heat treating those coals in a controlled, spontaneous, fluidized bed reactor system. The bed system is of such a geometry that in combination with the control system a higher velocity region exists where the fluidizing gas and fuel are fed than where the treated solids exit. The offgas exiting the top of the reactor has a velocity of the average of the inlet gas velocities. Treated coal is withdrawn intermediate to top and bottom. Residence time is controlled by the amount of the solid fuel feed, the location of the treated solid fuel overflow, and the temperature is maintained by oxygen to flue gas ratio, feedstock size and fluidizing velocity. The unit can be operated in a drying mode or a devolatilization mode, to control volatiles, moisture and fines.

Abstract: The present invention relates to a method of supplying coal and sulphur absorbent to a combustor with combustion in a fluidized bed. The coal is crushed and sorted into a fine and a coarse fraction. The fine fraction is mixed with water, possibly with oil and/or emulsifier, into a paste which is pumped into the bed of the combustor via a number of first nozzles. The coarse coal fraction is supplied to the combustor pneumatically in dry state, directly or via at least one lock hopper systems and a number of other nozzles. The invention also relates to a power plant for application of the method.

Abstract: A porous matrix, surface combustor-fluid heating apparatus comprising a combustion chamber, a porous stationary bed disposed within the combustion chamber, a porous bed heat exchanger for retaining the porous stationary bed within the combustion chamber, a fuel/oxidant inlet for introducing a fuel/oxidant mixture into the stationary porous bed, a distributor plate for distributing the fuel/oxidant mixture within the stationary porous bed proximate an inlet end of the combustion chamber, and a porous bed heat exchanger comprising at least one vertically oriented, fluid-cooled tube disposed in the stationary porous bed.

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: Particles in a fluidized bed reactor (e.g. a circulating fluidized bed reactor) are discharged from the reactor chamber and then cooled (heat is recovered from them) in a processing chamber. This is accomplished in a particularly advantageous way by discharging the particles from the reactor chamber at a first level (e.g. through a non-mechanical seal or a classifying wall) into a lifting chamber. Upwardly flowing gas in the lifting chamber entrains the particles and lifts them into the processing chamber. After processing, the particles in the processing chamber are returned to the reactor chamber at level higher than the first level, at which point the pressure in the processing chamber is higher than the pressure in the reactor chamber. The particles may be classified in the lifting chamber by utilizing fluidizing gas to transport solid particles smaller than a predetermined size to the processing chamber while discharging larger particles from the bottom of the lifting chamber.

Abstract: A method for controlling gas flow direction through a regenerative incinerator system coupled to a flow reversing valve, and for reversing the flow direction of the gas stream through the regenerative incinerator system. The regenerative incinerator system having a combustion zone and one or more heat accumulating and heat exchanging zones. The method establishes a combustion zone base temperature set-point, or T.sub.CB for referencing combustion zone temperatures, or T.sub.C 's, and an outlet base temperature set-point, or T.sub.OB, for referencing outlet temperatures, or T.sub.O 's, from the regenerative incinerator system. A switching temperature, or T.sub.S, is also established as a function of T.sub.C, T.sub.CB and T.sub.OB such that the slope of said function, i.e. dT.sub.S /dT.sub.C, is never negative over a predetermined range of combustion zone temperatures, or T.sub.C 's. The switching temperature being equal to T.sub.OB when the combustion zone temperature is equal to T.sub.CB.

Abstract: Repowering industrial and utility boilers with a circulating fluidized bed combustor to reduce SOx and NOx emissions emanating from the boilers by the following steps.First combusting high sulfur-containing carbonaceous solid fuel in a circulating fluidized bed combustor in admixture with limestone and air.Secondly combusting a carbonaceous fuel in an industrial or utility boiler.Thirdly mixing the flue gases generated in the circulating fluidized bed combustor with the exhaust gases produced in the industrial or utility boiler.Finally controlling the total heat generation by maintaining the circulating fluidized bed heat input to the boiler furnace from about 70 to 90% and the heat input of the boiler furnace from about 30 to 10%.

Abstract: A fluidized bed reactor system includes a reaction chamber comprising a circulating (fast) fluidized bed, with a first grid for the introduction of fluidizing gas, and a bubbling (slow) fluidized bed having a second grid for introduction of fluidizing gas. The second grid is mounted below the first grid. First and second interconnections are provided between the circulating and bubbling beds. Particles flow from the circulating bed through the first interconnection to the bubbling bed, and vice versa for the second connection. The interconnections are positioned with respect to each other so that the pressure and density conditions within the beds are the sole mechanisms that provide the driving force to control the flow of particles from the circulating bed to the bubbling bed.

Abstract: A circulating fluidized bed reactor has substantially vertical walls with cooling elements, defining the interior of the reactor chamber, and a device for introducing fluidization gas at the bottom of the fluidized bed reactor. Particulate material is introduced into the reactor. A separator separates particulate material from the exhaust gases, the separator being in connection with the reactor chamber. A return duct is connected to the separator. A bubbling fluidized bed is adjacent the reactor and provided with a heat exchanger for cooling particulate material, and side walls, rear and front walls having cooling elements in fluid communication with the cooling elements of the reactor chamber; and a discharge channel with a separate fluidizing gas source for discharging particles from the bottom of the bubbling bed to adjacent the top of the bubbling bed in the reactor chamber.

Abstract: The present invention provides a system and method (1) for reducing the amount of air toxic elements, particularly mercury (16), in concentrations down to and including trace levels, from a flyash (2) laden combustion gas stream (4). The method includes a step of combusting a fuel (14), often coal or solid waste to form flyash, and a step to concentrate the interaction of the flyash (2) in the combustion gas stream (4) for use as a sorbent.

Abstract: A circulating fluidized bed reactor includes a lower zone having a fluidization grid, primary and secondary air injection inlets, and fuel feed inlets, an upper zone, internal bubbling beds at the top of the lower zone collecting solid matter from recirculation internal to the reactor and delivering a fraction thereof to external bubbling bed heat exchangers close coupled with the walls of the reactor level with the internal beds. The external heat exchangers reject the solid matter into the lower zone after exchanging heat with an external fluid. The reactor is simple in structure and benefits from the advantages of bubbling external beds while maintaining conventional design in the lower zone.

Abstract: A method of heating of bed material in a PFBC plant including a combustor and wherein bed level adjustment due to a load change is accomplished by injecting bed material into or discharging it from the combustor through feeding devices, the method including the steps of arranging two storage vessels, each adapted for injecting the bed material therefrom into the combustor and for storing bed material discharged from the combustor, and heating and maintaining the bed material in the storage vessels at the temperature corresponding to the bed temperature while maintaining the bed level of the combustor constant, by discharging bed material with the temperature of the bed from the combustor via the feeding device adapted for discharge of bed material, into one of the storage vessels with a predetermined feed speed and at the same time and at the same feed speed injecting bed material from the second storage vessel into the combustor via the feeding device adapted for injection of bed material.

Abstract: In a pressurized fluidized bed boiler, furnace means is divided into at least two separate furnaces: a furnace with an evaporator and a superheater disposed therethrough, and a furnace with the superheater and a reheater disposed therethrough. The furnaces are accommodated in separate pressure vessels, respectively. Air is supplied into the pressure vessels through air pipes connected to the pressure vessels, where it is used for pressurizing the pressure vessels, and then supplied into the furnaces through their lower portions, where it is used as a combustion air. An oxygen concentration meter is mounted in an exhaust gas pipe in an outlet of the furnace, and an air flow rate adjusting valve 3 is mounted outside each of the pressure vessels.

Abstract: A fluidized bed reactor system, including a reactor chamber defined by a wall structure formed by a plurality of tubes through which a heat transfer medium circulates, is constructed so as to provide numerous advantages over conventional constructions. A fast fluidized bed of solid material is established in the reactor chamber. A solid material processing chamber is disposed adjacent the reactor chamber on the outer side of a wall structure defining the reactor chamber, e.g. for recovering heat from the solid material. The processing chamber shares a common wall portion with the reactor chamber and a slow fluidized bed of solid material is provided in the processing chamber. Particle passage openings are provided in the common wall. Particles from the processing chamber are recirculated to the reactor chamber after treatment (typically cooling).

Abstract: A fluidized bed combustion system in which a fluidized bed of particulate fuel material is established in a furnace. A duct is formed in the upper portion of said furnace for passing a mixture of flue gases and entrained particulate fuel material to a separator located adjacent the furnace outlet. A heat exchanger is also disposed in the upper portion of the furnace at approximately the same height as the duct so that a portion of the mixture passes over the heat exchanger and then exits via the duct and another portion of the mixture exits directly through the duct.

Abstract: A method of reducing the nitrogen oxide level in the flue gases issuing from combustion units by introduction of reducing agents into contact with gases containing nitrogen oxides in first and second reducing stages, is provided. The first reducing stage is a non-catalytic stage (e.g. at temperatures over 800.degree. C.), while the second stage is a catalytic stage (e.g. at temperatures of about 300.degree.-400.degree. C.). A steam generation boiler with improved nitrogen reduction facilities is also provided. The amount of nitrogen oxides in the hot gases is reduced in the combination of the first and second reducing stages while producing steam in a steam generation boiler system, thus resulting in gases essentially free from nitrogen oxides while eliminating the possibility of NH.sub.3 (or other reducing agent) slip in the exhausted flue gases. Heat transfers in a convection section as used to establish stabilized temperature conditions for catalytic reduction.

Abstract: A fluidized bed combustion system and method in which a recycle heat exchanger is located adjacent the furnace section of the recycle heat exchanger. Heat exchange surfaces are provided in a compartment of the recycle heat exchanger for removing heat from the solids, and a bypass compartment is provided through which the solids directly pass to the furnace during start-up and low load conditions. The flow of solids between compartments is selectively controlled and an L-valve connects one of the compartments to the furnace section. Air is passed into the L-valve to promote the flow of the separated materials from the latter compartment to the furnace. The flow rate of the air is modulated to vary the duty of the recycle heat exchanger.

Abstract: A system and method are disclosed for lowering NO.sub.x levels in flue gases of a fluidized bed reactor using selective non-catalytic reduction. A reactor is connected to a separator by a duct, and a reactant is introduced into the duct for decreasing NO.sub.x levels in the flue gases passing from the reactor, through the duct, and into the separator. The reactant, such as ammonia or urea, is selectively injected into a gaseous-rich region of the duct, near an upper, inner portion of the duct, so that a high degree of mixing of the reactant with flue gases is achieved while maintaining a low degree of mixing of the reactant with the particulate materials. The point of injection of the reactant into the duct is also at a location nearer to the reactor than to the separator to provide for increased residence time. In this manner, the reactant is used efficiently while obtaining the desired lowering of NO.sub.x levels in the flue gases.

Abstract: A pressurized fluidized bed reactor is provided utilizing a centrifugal separator having a gas space that is distinctly non-circular, preferably having a circularity of greater than or equal to 1.15. Most desirably the cyclone has a quadrate (e.g. square) cross-section, and is disposed inside of the pressure vessel along with the reactor chamber containing the fluidized bed. A number of ceramic candle or honeycomb filters may be provided connected to the gas outlet from the cyclone separator, within the pressure vessel, to filter the gas. This construction provides a minimized diameter of the pressure vessel because the reactor chamber with square cyclones is more compact than if conventional circular cross-section cyclones are employed. Also a second pressure vessel is not needed for the candle or honeycomb filters since there is sufficient room within the pressure vessel to accommodate them.

Abstract: The invention relates to a boiler for the production of steam, the boiler having a maximum capacity of 100 ton/hr or more and comprising a furnace having a substantially constant rectangular cross-section and a back pass with a substantially constant rectangular cross-section. The furnace and the back pass are mounted close to each other and means are provided for superheating the steam. The steam superheating means are positioned within the back pass, so that no superheater is positioned within the furnace.

Abstract: Organic and/or inorganic substances and water are thermally separated from contaminated materials, solid aggregates, the contaminated material is pretreated and is subsequently heated in a directly or indirectly heated furnace, which includes a rotary kiln, a fluidized bed furnace or a floating zone reactor, and during the heating the material is treated with recycled hot gases or recycled hot steam and with oxidizing agents. The exiting processing gases, which contain water vapor, are dedusted, and 80 to 90% by volume of the water vapor-containing processing gases are recycled to the furnace to act as entraining gas. The remaining water vapor-containing processing gases are condensed, the resulting liquid phase is withdrawn, and pollutants are removed from the withdrawn liquid phase by a wet chemical or physical processing.