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 300-400.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 reactor for combusting material at an elevated temperature and generating heat. The reactor includes an upright reactor chamber delimited by at least one supporting wall having an internally refractory lined lower portion, the reactor chamber defining a space containing an abrading flow of fluidized bed material, a refractory lining provided on the internal side of the lower portion of the supporting wall, a recess provided on the internal side of the supporting wall above the refractory lining, the recess being defined by at least an upper endwall and a bottom, and a coating provided on the internal side of the supporting wall above the refractory lining. The coating extends from the upper endwall of the recess to the refractory lining, for recessing at least an upper border region of the coating.

Abstract: Solid particles are transported from a first chamber (e.g. combustion chamber of a fluidized bed reactor) to an adjacent second chamber (e.g. a transporting and/or processing chamber) by providing a solid flow gas seal, a controllable solid flow valve, or both in a partition between the chambers. Transporting gas is introduced into the first chamber to transport solid particles as multiple solid flows from the first chamber to the second chamber. A number of narrow passages in the partition wall disposed one on top of the other, and having a height to length ratio of less than 0.5, less than 50 mm, act as the gas seal and controllable solid flow valve in the partition.

Abstract: The present invention refers to an improved method and an improved apparatus for reducing the concentration of nitrogen oxides in flue gases produced by the combustion of carbonaceous fuel in combustion units having a furnace with a fluidized bed of solids therein. Hot gases produced within the furnace flow mainly upward within the furnace. Heat is recovered from the hot gases and hot solid material by heat transfer surfaces within the furnace. A nitrogen oxides reducing agent is introduced into the furnace through injection means integrally connected to the heat transfer surfaces, for keeping the temperature of the reducing agent at a sufficiently low temperature level at the introduction thereof and for efficiently mixing it with the mainly upward flowing hot gases.

Abstract: A method and apparatus for recovering heat from solid particles in a fluidized bed reactor, utilize a heat transfer chamber, having heat transfer surfaces disposed therein. Hot solid particles are continuously fed into the heat transfer chamber and gas is introduced into and discharged from the heat transfer chamber. Gas is introduced into the heat transfer chamber for controlling the flow of solid particles therein. The heat transfer chamber is divided into at least one heat transfer zone and at least one solid particle transport zone, by providing more heat transfer surfaces in the heat transfer zones (e.g. 90% or more of the total heat transfer area) than in the solid particle transport zones. The heat transfer is controlled by introducing separately controlled flows of gas into the heat transfer zones and the solid particle transport zones.

Abstract: A centrifugal separator has a plurality of substantially planar walls, including a first wall, defining a vortex chamber having an interior gas volume and for establishing at least one gas vortex in the gas volume, and the gas volume has a cross section that is distinctly non-circular, (and preferably quadrate). In addition to conventional outlets the separator includes a gas inlet having at least one elongated jet-defining wall with a free end portion extending into the gas volume a first distance from the first wall, to define a gas jet that extends substantially tangentially to the gas vortex in the gas volume. An insert extends between the jet-defining wall free end portion and the first wall and defines a gas flow direction changing surface. The insert may be substantially solid refractory material, or include a number of cooling fluids circulating tubes, and a gas flow direction changing surface may be substantially planar or curved.

Abstract: In a fluidized bed reactor system having a gas cooler, with cooling surfaces, downstream of a first cyclone separator, the cooling surfaces are cleaned by introducing sufficient concentration of bed particles into the gas during, or just prior to, cooling, so that the particles mechanically dislodge deposits from, and thereby clean, the cooling surfaces. The particles are then removed downstream of the cooler by a second separator, and the bed particles separated by the second separator may be returned to the fluidized bed reactor at or just before the cooler to again be used to effect cooling. Cleaning may be practiced in spaced time intervals only (e.g. periodically or intermittently), or continuously.

Abstract: A method and apparatus for cooling hot gas in a reactor which is provided with a mixing chamber for hot gas and a chamber encompassing a bubbling fluidized bed in the lower section of the reactor, a riser in the middle section, a gas outlet in the upper section of the reactor, and heat transfer surfaces for recovering heat from solid particles. The hot gas is introduced through the mixing chamber into the lower section of the reactor. In the mixing chamber solid particles are supplied to the hot gas for cooling the gas. The gas containing solid particles is conveyed into a separator. From the separator, the gas is conveyed through the riser into particle separators and, when purified, out of the reactor. The solid particles separated in the particle separator are returned to the lower section of the reactor, preferably both directly into the mixing chamber and into the fluidized bed. From the fluidized bed, cooled solid particles are conveyed to the mixing chamber for cooling of hot gas.

Abstract: Separation of a high temperature (e.g., 300.degree.-1200.degree. C.) and high pressure (e.g., 2-20 bar) solids-gas stream from a pressurized fluidized bed reactor into solids and gas while reducing the pressure of both the gas and solids takes place in a vertical de-entrainment vessel having a packed bed of solids within it. The possibility of fluidization of the solids is minimized by causing the velocity of the gas component of the solids-gas stream to be reduced during, or just prior to, introduction of the gas into the packed bed of solids, e.g., by providing an expanding conical end to the inlet for the solids-gas stream into the vessel. A gas permeable solids impermeable element may also or alternatively be connected to the inlet and extend toward (optionally all the way to) the side wall of the vessel, to substantially prevent fluidization.

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: Heat is recovered from the hot solids discharged from the combustion chamber of a fluidized bed reactor. Hot solid particles as a result of combustion are removed either in the form of ash, or particles separated from a gas stream, and are passed into indirect heat exchange relationship with water, producing hot water. The hot water is mixed with fuel or other solid material to simultaneously heat and moisten the solid material (e.g. to a moisture content of 15-50%). The heated and moistened solid material is then fed into the combustion chamber, along with fluidizing air, to establish a fluidized bed in which combustion takes place. The heat exchange may take place in a closed heat exchange vessel, and the cooled solid particles may be discharged from the vessel through a pressure reduction valve.

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 invention relates to a method and apparatus for cooling the exhaust gases of a molten stage furnace. The method relates to furnace structures in which the shaft (3) is vertical and the exhaust gases are passed through an outlet in the furnace roof to the cooling equipment without recovering heat from the exhaust gases through the wall portions above the furnace. The exhaust gases are cooled in two stages first indirectly by a circulating mass cooler (1) and then further in a waste heat recovery boiler. In the apparatus according to the invention, the vertical shaft section above the furnace is connected to a circulating mass cooler which is connected to a waste heat recovery boiler arranged, e.g., next to the furnace and/or the shaft.

Abstract: Separation of a high temperature (e.g., 300.degree.-1200.degree. C.) and high pressure (e.g., 2-20 bar) solids-gas stream from a pressurized fluidized bed reactor into solids and gas while reducing the pressure of both the gas and solids takes place in a vertical de-entrainment vessel having a packed bed of solids within it. The possibility of fluidization of the solids is minimized by causing the velocity of the gas component of the solids-gas stream to be reduced during, or just prior to, introduction of the gas into the packed bed of solids, e.g., by providing an expanding conical end to the inlet for the solids-gas stream into the vessel. A gas permeable solids impermeable element may also or alternatively be connected to the inlet and extend toward (optionally all the way to) the side wall of the vessel, to substantially prevent fluidization.

Abstract: An expansion joint for protectively shielding a seal member disposed in a joint between two flue sections, includes a first shield member having a foot for attachment to an end of a first flue section, the shield member having a curved panel portion for extending over and protectively shielding a seal member, and a second shield member having a foot for attachment to an end of a second flue section, the second shield member having a curved panel portion for extending over a portion of the first shield and along the direction of gas flow.

Abstract: Either atmospheric pressure or superatmospheric pressure high temperature gases, as from a gasifier or other circulating fluidized bed reactor, are filtered using monolithic ceramic filter elements mounted in an advantageous manner within a vessel. At least one generally upright hollow chamber element is mounted by a tube plate within the vessel, and has at least one gas impervious side wall having a column of openings in it, an open end, and a closed end. Monolithic ceramic filter elements are mounted in the openings. A number of chamber elements are typically provided, e.g. mounted in a circular pattern, and/or mounted to extend downwardly from a top tube plate and upwardly from a bottom tube plate. Backflushing of the filter elements dislodges separated particles, which fall down to the bottom of the vessel and are removed through a central discharge opening.

Abstract: In the filtering of high temperature (e.g. greater than 400.degree. C.) and high pressure (e.g. greater than 5 bar) gas--such as produced by pressurized fluidized bed combustion or gasification of coal--there is often a buildup of particles on the supporting elements for the filters, and on surrounding structures. This buildup of particles can damage the filter elements, or greatly reduce their effectiveness. This problem is avoided by periodically automatically cleaning the supporting and/or surrounding surfaces of the filters, as by directing high pressure gas streams at the supporting and/or surrounding surfaces. The filters may also be backflushed with compressed gas, as is conventional, at the same time as, or at different times than, when the supporting and/or surrounding structures are cleaned. Conduits with nozzles may be mounted directly on the supporting and/or surrounding surfaces and connected by a pipe with an automatically controlled valve to a source of high pressure fluid.

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: A fluidized bed assembly, such as an ash cooler, includes first and second fluidized bed chambers each having a bottom portion and side walls. Fluidizing gas is introduced into the bottom portions to fluidize particulates within the chambers. A flow equalizer (such as a barrier having a number of openings associated with it) separates the chambers and provides a substantial uniform flow of particulates from the first chamber to the second chamber so that no dead spots or corners form in the chambers adjacent the flow equalizer. Heat exchanger components are typically provided in the barrier for circulating heat exchange fluid through the barrier. Also, heat exchangers are provided in one or both of the chambers to cool the particulates. The particulates mix in the second chamber, and after cooling may be recirculated to a gasifier/combustor for supplying ash to the first chamber. A classifier chamber is connected between the reactor and the first chamber.