Abstract: In a power plant with combustion of particulate fuel in a fluidized bed, unburnt particles are after-burnt in a burner which is based on the principle of vortex collapse and coarser particles are separated in connection with the after-burning. Such a burner may be designed as a double-cone burner, wherein unburnt fuel particles are burnt. Larger particles move around in a helical movement inside the extension of the burner cone. A coarse particles separator integrated with the burner, is arranged and comprises a circular gap which is located near the extension of the burner cone and which collects coarser particles rotating at the side of the combustion zone of the burner. These separated particles, collected by the circular gap, are forwarded to a space which surrounds the burner and from where the separated coarser particles are returned to the primary combustion space, for example, to the fluidized bed in the plant.

Abstract: An improved pulverized coal burner that reduces the formation of nitrogen oxides. The coal burner includes fuel splitters that separate a mixture of primary air and coal into a plurality of streams while the mixture is discharged through a diffuser having a plurality of partially open areas and a plurality of blocked areas. After passing through the diffuser, the plurality of streams are discharged into a furnace to be burned. The plurality of partially open areas and blocked areas are created by removing sections of the diffuser and replacing the removed sections with fuel spiders. Creation of these discrete streams delays mixing with secondary air. Because primary air is supplied in sub-stoichiometric quantities, the coal in these split streams will be burned under fuel-rich conditions for the first 100 to 200 milliseconds of combustion, until the delayed mixing of secondary air occurs. Combustion in a fuel-rich environment retards formation of nitrogen oxides in two ways.

Abstract: A burner for the combustion of a pulverized coal plus primary air mixture includes a nozzle pipe having an inlet for receiving a pulverized coal plus primary air mixture and an outlet for discharging same. A hollow plug extends axially within the nozzle pipe and defines an annular space between the plug and the nozzle pipe for conveying the pulverized coal plus primary air mixture therethrough. The hollow plug is axially moveable within the nozzle pipe. A variable amount of core air is supplied into the hollow plug so that it mixes with the primary air plus pulverized coal mixture at an outlet of the burner to vary the PA/PC ratio and maintain a desired primary air to primary coal ratio at the outlet of the burner. Natural gas can also be supplied into the hollow plug as a supplemental fuel for cofiring at the outlet end of the burner.

Abstract: A steam generator is operated under both of supercritical pressure and subcritical pressure and has having generating tubes that form a furnace wall. Upper and lower generating tubes which are directed vertically and central generating tubes are inclined by 10.degree. to 35.degree. with respect to a vertical line. The steam generator further includes a burner wind box which is inclined along the inclination of the central generating tubes and are vertically divided into a plurality of stages.

Abstract: A method of burning coal with less than 10% volatiles in a burner supported by air. The coal is pulverized in a pulverizer and supplied to the burner mixed with a vehicle in the form of air. The object is more reliable ignition. The coal is separated from the air before it enters the burner and is combined into a new mixture with heated air. The second mixture is forwarded at a higher temperature and with a lower level of coal. The coal is separated from the second mixture and combined into a third mixture with heated air. The third mixture is forwarded at a higher temperature and with a higher level of coal.

Abstract: A pulverized fuel burner having lower emissions and lower unburned fuel losses by outwardly diverting and swirling pulverized fuel at the outlet of a fuel nozzle carrying the pulverized fuel. Diverting cone is positioned at the outlet of the fuel nozzle and include swirling plates connected there between for outwardly diverting some of the pulverized fuel and swirling a remainder of the pulverized fuel. Together these effects reduce the axial momentum of the fuel, shortening the flame and improving its emission and unburned fuel loss characteristics.

Abstract: A system and method for preheating a mixture of fuel and air as the mixture is introduced into a furnace combustion chamber comprises passing the mixture through a nozzle extending into an upstream portion of an opening defined in a wall enclosing the combustion chamber. The nozzle is sized so that an annular space is formed between the nozzle and the opening. Hot air is introduced through the annular space and mixes with and preheats, in a downstream portion of the opening, the mixture passing through the nozzle. The preheated mixture then passes into the furnace combustion chamber for combustion therein.

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: 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 method of treating solid residue resulting from combustion of a sulfur-containing fuel in the hearth of a boiler having a circulating fluidized bed, in which method limestone is inserted into the hearth so as to make it possible to absorb the resulting sulfur dioxide in the form of calcium sulfate CaSO.sub.4, the method further including the following steps:1) prior to being inserted into the hearth, the fuel is ground down to less than 100 microns;2) prior to being inserted into the hearth, the limestone is ground down to a grain-size centered in the range 100 microns to 150 microns, with a maximum of 1 mm;3) at the base of the hearth, the combustion residue is collected, which residue includes lime and calcium sulfate resulting from taking up the sulfur dioxide SO.sub.2 evolved by the combustion, and the residue is subjected to heat treatment in a reactor, in which both solid matter based on lime CaO, and also a gaseous mixture containing, in particular, sulfur dioxide SO.sub.

Abstract: A burner (10) for the combustion of fuel comprises a passage (32) through which in operation a mixed flow of fuel and air passes for primary combustion at it's outlet. Two further annular passages (34, 36), concentric with and radially outward of the passage (32), are provided through which supplementary flows of air pass to support the primary combustion. The outlets of the two annular passages (34, 36) diverge to discharge the supplementary flows of air at an angle to the mixed flow of fuel and air. Members (62) are provided in the annular passage which obstruct the discharge of the supplementary flow of air. Furnace gases circulate in the region downstream of the obstruction members (62). Circulation of the furnace gases delays the mixing of the fuel and air mixture with the supplementary air flows to reduce the nitrogen oxides produced.

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: An outage protection system for a SCR (selective catalytic reduction) reactor utilizes a pair of dampers to isolate the catalyst bed and the ammonia injection grid of the SCR reactor and to provide a blower driven closed loop flow of externally heated air from the injector grid across the catalyst bed to an external heater and back to the injection grid.

Abstract: A particulate waste wood fuel comprising wood particles comprising less than 20% water by weight and having a particle size distribution suitable for combustion of the particulate wood fuel in a particulate fossil fuel suspension furnace. A method for making the particulate wood fuel includes shredding of waste wood and drying the shredded waste wood to obtain the desired particle size distribution and water content. A method for producing energy comprises injecting the particulate wood fuel into the combustion chamber of a particulate fuel suspension furnace separately from a particulate fossil fuel which is also injected into the combustion chamber. The particulate fossil fuel and particulate wood fuel are combusted in the combustion chamber in a gas flow through the combustion chamber to form a flame in the gas flow. The wood particles are substantially completely combusted within the combustion chamber while suspended in the gas flow and are not combusted at the furnace wall.

Abstract: Device for mixing gas, liquids or pulverized solid substances with a gas flow (1), whirling (vortex) around an axis in the flow direction. The whirling gas flow is guided through a converging passage (4) and, during or after being charged with the substance, abruptly widens in cylindrical space (11), as a result of which vortex break down occurs and an exceptionally thorough mixing and/or atomizing of the substance is obtained. Application in a burner improves the combustion result, keeps the NOX-values low and prevents the flame from being blown off.

Abstract: Method and apparatus for reducing the NOX levels in stack emissions of compact boilers and fluid heaters through selective injection of exhaust flue gases into the combustion process. Flue gas injection into the primary and secondary air of the burner along with flue gas injection directly into the combustion process is utilized. Injection of generated steam obtained from various components of a compact boiler, selectively injected into the combustion process is also provided.

Abstract: High sulfur content fuel is combusted in the presence of oil shale containing significant amounts of calcium carbonate so that the sulfur and calcium carbonate oxidize and react to form calcium sulfate particulate which captures the sulfur and in the fuel and prevents its release to the atmosphere.

Abstract: An improved pulverized coal burner that reduces the formation of nitrogen oxides. The coal burner includes fuel splitters that separate a mixture of primary air and coal into a plurality of streams while the mixture is discharged through a diffuser having a plurality of partially open areas and a plurality of blocked areas. After passing through the diffuser, the plurality of streams are discharged into a furnace to be burned. The plurality of partially open areas and blocked areas are created by removing sections of the diffuser and replacing the removed sections with fuel splitters. Creation of these discrete streams delays mixing with secondary air. Because primary air is supplied in sub-stoichiometric quantities, the coal in these split streams will be burned under fuel-rich conditions for the first 100 to 200 milliseconds of combustion, until the delayed mixing of secondary air occurs. Combustion in a fuel-rich environment retards formation of nitrogen oxides in two ways.

Abstract: A burner block for mounting a burner within a furnace containing a melt to be heated by the burner. The burner block comprises a body having a passageway terminating in a divergent opening. The passageway is configured to receive the burner so that the burner is recessed within the divergent opening and a flame produced by the burner is directed out of the divergent opening and over the melt. The divergent opening has a lower section angled in a downward direction and the lower section has a reversed step to produce a primary recirculation zone beneath the flame, thereby to draw the flame in a downward direction toward the melt. The reversed step is positioned within the divergent opening so that when the burner is in use, a secondary recirculation zone forms between the opening and the melt and further draws the flame in the downward direction toward the melt.

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 method of burning waste comprised essentially of plastic, especially PVC waste. The waste is burned in a revolving cylindrical furnace accompanied by the addition to the waste of at least one finely ground solid additive having at least one component with a melting temperature higher than the melting temperature of the plastic of the waste.

Abstract: A method and apparatus for reducing the formation of nitrogen oxides during combustion in a roof-fired furnace is disclosed. By blocking at least some of the fuel nozzles associated with a roof-fired burner while leaving open the secondary air openings associated with the blocked fuel nozzles, reduction in NOX emissions from roof-fired furnaces is accomplished. This blocking results in the creation of a localized fuel-rich or just slightly fuel-lean environment near open fuel nozzles because part of the secondary air needed for combustion is being added at a location distant from where the initial combustion occurs. By creating a localized fuel-rich or slightly fuel-lean environment near the open fuel nozzles, the initial stages of combustion occur with little or no excess oxygen present. Because much of the fuel-bound nitrogen is liberated during the initial stages of combustion, it will preferentially react to form molecular nitrogen rather than nitrogen oxides because of the lack of available oxygen.

Abstract: A low nox burner for use in a tangentially-fired furnace having a pivotally mounted burner tip attached to a fuel passage that in operation, conveys pulverized coal carried by an airstream. The burner tip includes a plurality of first and second blade members extending substantially radially from a centrally positioned, cone-shaped support member. A fuel guide surrounds and is attached to the outer ends of the first and second blade members thereby defining alternating fuel-rich and fuel-lean channels between the centrally positioned support member and inside of the fuel guide. An air guide surrounds the fuel guide and defines a passage for combustion air which is received from an air housing. The position of the air guide with respect to the fuel guide is maintained by a plurality of angled vanes which are operative to impart rotational forces to the combustion air traveling between the air guide and the fuel guide.

Abstract: Pulverized coal and air flowing-in a coal nozzle are distributed for combustion with low NOX generation by a concentric central duct with long exterior spiraling vanes which extend upstream and attach to a support pipe extending further upstream in the nozzle. The space from the downstream end of the support pipe to the upstream end of the central duct, and the cross section of the pipe relative to the cross section of the central duct regulate the entry of coal and air into the central duct from which the flow emerges with reduced velocity as a central stream stabilizing the flame. The central duct also has an exterior short vane attached to each long vane to separate the pulverized fuel and air outerflow into fuel-enriched swirling streams and fuel-depleted recirculation zones.

Abstract: A method and apparatus are provided for operating a pressurized reactor system in order to precisely control the temperature within a pressure vessel in order to minimize condensation of corrosive materials from gases on the surfaces of the pressure vessel or contained circulating fluidized bed reactor, and to prevent the temperature of the components from reaching a detrimentally high level, while at the same time allowing quick heating of the pressure vessel interior volume during start-up. Superatmospheric pressure gas is introduced from the first conduit into the fluidized bed reactor and heat derived reactions such as combustion and gassification are maintained in the reactor. Gas is exhausted from the reactor and pressure vessel through a second conduit.

Abstract: A method and apparatus for a pellet fuel burning heating unit for burning corn or wood pellets having a balanced pressure system having a four-way split combustion intake airstream. The invention includes a combustion air blower system for providing combustion air into a firebox containing a burner under positive pressure and at the same time providing a negative pressure to remove the combustion gases from the firebox. A pressure regulator and air splitter maintains a balance between the positive and negative pressure and adjusts the air flow into the firebox and out the exhaust. The exhaust is provided through a bank of exhaust tubes running from the top of the firebox to an exhaust manifold. The blower air moves into the pressure regulator and air splitter dividing the air flow such that a portion enters the heating unit exhaust manifold to produce a negative pressure and the remaining portion enters the heating unit burner under positive pressure.

Abstract: A method for disposing of paper in an asphalt plant, comprising the steps of: a) providing a container for heating stone aggregate, providing in the container a burner for producing a flame to provide thermal energy for heating the stone aggregate in the container; b) providing a stream of air into the burner flame; c) introducing the paper into the stream of air, such that the paper is entrained in the stream of air, such that the stream of air having therein the entrained paper is introduced into the burner flame, and such that the paper is substantially incinerated in the container.

Abstract: Combustible gases from a solid fuel are produced by pyrolyzing the fuel in a pyrolyzer which also produces carbonaceous material. The carbonaceous material from the pyrolyzer is combusted in a furnace to produce combustion products that include hot flue gases and ash particulate. The combustion products are separated into a plurality of streams, one of which contains flue gases, and another of which contains hot ash which is directed into the pyrolyzer. Finally, the stream of flue gases from the furnace is used to dry the fuel that is supplied to said pyrolyzer.

Abstract: A combustion is performed with a fuel which has been reformed by mixing with combustion products and/or water steam to supress NO.sub.x formation.

Abstract: A method and system for Very Low Temperature Ashing (VLTA). In one embodiment, there is provided a method of ashing solid fuel or combusted or partly combusted fuel or any organic and inorganic matrix which contains minerals in a furnace with a partial pressure less than atmospheric pressure including the step of mixing of oxygen and helium with a total pressure less than the atmospheric pressure and producing a plasma in which the mineral components in the samples are not being affected essentially, wherein the proportion of the gas mixture achieve a surface temperature not exceeding 150.degree. C. on the sample. In an alternative embodiment, there is provided a method of ashing solid fuel or combusted or partly combusted fuel or any organic and inorganic matrix which contains minerals in a surface with a plasma including the step of regulating the proportion between oxygen and helium by a reduction of oxygen content, wherein the surface temperature shall not exceed 150.degree. C.

Abstract: A pulverized coal steam generator employing tangential, concentric firing with oxidizing conditions adjacent the furnace walls and using overfire air and low NO.sub.x firing methods is operated at very low excess air levels. This is possible because the unburned carbon in the flyash is measured and the pulverizers are adjusted to control the particles size of the pulverized coal and maintain a desired carbon level. The slagging and corrosion associated with deep staging is overcome by the concentric firing. Overall plant efficiency is obtained while still meeting performance objectives and emissions controls.

Abstract: A furnace apparatus which includes a plurality of water walls. Each includes a plurality of tubes and the water walls collectively enclose a combustion chamber. The apparatus includes a plurality of windboxes, each of the windboxes is disposed intermediate adjacent water walls. A pulverizer and ducting to direct the flow of pulverized coal to the windboxes is also a part of the apparatus in accordance with the invention as is a bisector regenerative air heater having a rotor a housing having a generally cylindrical cavity in which a drum shaped rotor having heat transfer surfaces thereon is mounted for rotation on a shaft. The heater includes ducting for directing flue gas and forced draft air respectively into first and second angular sectors of the cavity which at any one instant will flow over respective angular sectors of the rotor. The rotor is heated during the travel of any portion thereof in the first angular sector and is cooled in the second angular sector.

Abstract: Method and apparatus for reducing the NOX levels in stack emissions of compact boilers and fluid heaters through selective injection of exhaust flue gases into the combustion process. Flue gas injection into the primary and secondary air of the burner along with flue gas injection directly into the combustion process is utilized. Injection of generated steam from a compact boiler, selectively injected into the combustion process is also provided.

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 coal-fired firetube boiler and a method for converting a gas-fired firetube boiler to a coal-fired firetube boiler, the converted boiler including a plurality of combustion zones within the firetube and controlled stoichiometry within the combustion zones.

Abstract: A method of operating a fossil fuel-fired power generation system (10, 10', 10", 10'") in order to thereby optimize the operating efficiency thereof.

Abstract: Method for disposing of absorbent material impregnated with waste. The capillary retention capability of the absorbent material impregnated with waste is destroyed, thereby releasing the waste retained in the material. The absorbent material and released waste form a mixture for disposal at a boiler, industrial furnace or incinerator.

Abstract: A burner flame stabilizer which circumferentially stages the air to form circumferentially-spaced fuel rich and fuel lean zones for lowering of NO.sub.x is described. A circumferential solid fuel stager is described, which operates with a fuel stabilizer to provide increased dwell time for coal particles volatilization in a recirculation zone established by the flame stabilizer. Various embodiments are described.

Abstract: A method of feeding particulate material into a pressurized fluidized bed combustor including the steps of: feeding the particulate material from a source which is at a substantially lower pressure than that existing in the pressurized fluidized bed combustor into the upper end of an elongate, generally vertical gravity feed conduit constructed to have an inner bore which is substantially smaller at its lower end than at its upper end, and selecting the vertical height of the feed conduit and the extent of reduction in its bore over its length to ensure that the particulate material will move by gravity between the open input end of the conduit and the pressurized fluidized bed combustor notwithstanding the difference in pressure between the pressurized combustor and at the input end of the conduit.

Abstract: A method for combusting a fossil material so as to produce an exhaust stream having a low level of pollutants. The fossil material is introduced into a fluidized bed combustor which is operated at a temperature of at least approximately 1775.degree. F. to produce a partially cleansed exhaust stream having a low level of N.sub.2 O. SO.sub.2 is removed from the partially cleansed exhaust stream outside of the fluidized bed combustor to produce a cleansed exhaust stream having a low level of SO.sub.2. An apparatus is provided for performing the method of the invention.

Abstract: Combustible gases are produced from a solid fuel by pyrolizing the fuel in a pyrolyzer containing a low grade solid fuel producing combustible gases, and carbonaceous material that is combusted in a furnace to produce hot products that include hot flue gases and particulate material. The hot products are separated into a plurality of streams, one of which contains comparatively coarse ash which is directed into the pyrolyzer for effecting the pyrolyzation of the fuel. A stream of reaction gases is applied to the pyrolyzer in such a way that the stream of reaction gases bubbles through the carbonaceous material in the pyrolyzer without fluidizing such material. In effect, the reaction gases activate the void fraction in the pyrolyzer thereby reducing the residence time of the material therein.

Abstract: A low-nox burner for use in industrial furnaces and/or boilers which burn pulverized coal. The burner includes a burner tip which divides an annular pulverized coal stream into alternating fuel-rich and fuel-lean streams. The tip includes a plurality of alternating main and secondary blade members which are skewed to produce rotational movement in the streams. The main blade has a leading edge that is aligned with a radial vector extending through a center axis of the burner and a trailing edge that is tilted with respect to the radial vector in order to define a substantially planar surface between the leading and trailing edges. The secondary blade includes leading and trailing edges that are both aligned with radial vectors and defines a twisted surfaces between the edges. The secondary blade is skewed with respect to the longitudinal direction by an angle that is substantially greater than the angle at which the main blade is skewed.

Abstract: A process is provided for burning a coal water slurry comprising providing clean coal fines of less than 100 mesh at about 50 weight % and water at about 50 weight % by co-firing the coal water slurry in a continuous stream with a separate stream of pulverized coal wherein about 80% of the total BTU output of the furnace is provided from the pulverized coal and approximately 20% of the BTU output is provided from the coal water slurry. First, a quarl in the furnace is preheated using natural gas, for example. The furnace is next fired with a fuel source of 60% pulverized coal and 40% natural gas. A coal water slurry with fines of minus 100 or smaller is subsequently gradually introduced into the furnace as the gas input is gradually decreased.

Abstract: Method for producing hot drying gas by a burning flowable biological refuse in an incinerator which comprises a vertical cyclone furnace. Fuel together with primary combustion air is tangentially injected into the vertical cyclone furnace, and secondary combustion air and tertiary combustion air are injected into a throat. A cooled rotating ash scrapper is provided in the bottom of the vertical cyclone furnace and waste gas is conducted through the throat to a secondary combustion chamber in which an incineration of residuals takes place and from which a drying gas is removed. A combustion retarding gas is injected into the hottest area of the vertical cyclone furnace so that a sintering and the formation of slag is avoided.

Abstract: A flame stabilizer for a burner of solid fuel, such as pulverized coal or sander wood dust, is described whereby the swirl number is varied radially to enhance swirl inducement towards the periphery of the flame stabilizer while more axial flow occurs near the central conduit through which fuel is supplied. The amount of swirl and the amount of combustion air being selected so as to provide an integrated swirl number for the flame stabilizer in the range from about 0.6 to about 2.0. A pressure control ring is described with which the static pressure in the windbox is increased to a level where flame pulsations attributable to low static pressure in the windbox are reduced while the vortex is maintained. An enhanced axial combustion air flow around the discharge end of the fuel supply conduit is described to modify the position of the adverse pressure gradient boundary in a downstream direction.

Abstract: The gasification burner of this invention capable of maintaining a high combustion rate for a long period of time comprises a combustion chamber having a ceiling with a small hole in its center, a pre-mixing pipe fitted into the small hole and having a nozzle at its top, wherein the pre-mixing pipe and the combustion chamber are concentric, and the spread angle of the gas flow sprayed from the end of the pre-mixing pipe is between 10 and 40 degrees, so that the relationship between the bottom of the combustion chamber and the conical gas flow is regulated by keeping a good balance between the gasification rate of the powdered coke and the life of the combustion chamber.

Abstract: A method and a device for preheating a particulate fluidized bed which is supplied with air for fluidization of bed material and for combustion of main fuel through gas paths that include fluidization members for injection and distribution of the air over the fluidized bed. The bed material is preheated to the ignition temperature for the main fuel used in the fluidized bed by members arranged in the gas paths for combustion of starting fuel. These members are designed and arranged so that the air is supplied to the fluidized bed along the same path through gas paths and fluidization members upon preheating with starting fuel as upon combustion of main fuel in the fluidized bed. The members for combustion of starting fuel are arranged in the fluidization members and comprise fuel injectors, fuel pipes, ignition members and control members.

Abstract: An advanced overfire air system for NO.sub.x control designed for use in a firing system of the type that is particularly suited for use in fossil fuel-fired furnaces and a method of operating such a furnace which embodies an advanced overfire air system. The advanced overfire air system for NO.sub.x control includes multi-elevations of overfire air compartments consisting of a plurality of close coupled overfire air compartments and a plurality of separated overfire air compartments. The close coupled overfire air compartments are supported at a first elevation in the furnace and the separated overfire air compartments are supported at a second elevation in the furnace so as to be spaced from but aligned with the close coupled overfire air compartments.

Abstract: Active rice husk ash is produced by a method which includes placing a hollow platform having many holes of a size too small for rice husk to enter on an enclosed floor slab, erecting a chimney on the hollow platform in communication with the interior of the hollow platform, forming a cone of rice husk around the chimney to completely cover the hollow platform, igniting the rice husk at the small holes for smolderingly incinerating the rice husk into carbonized rice husk, and allowing the carbonized rice husk to self-burn into ash.

Abstract: A method is shown for producing a lightweight aggregate by treating flyash and sewage sludge. The flyash and sewage sludge are mixed together and then agglomerated into pellets, with or without the use of a binder. The pellets may be coated and then are dried. The dried pellets are introduced into a rotary kiln in a direction that is co-current with the flow of fuel and air through the kiln. The pellets in the kiln will be indurated and will experience complete calcination as well as varying degrees of pyrolizing and sintering. The product of the kiln is a nodular material having a low density but with a hard and porous structure. The product of the kiln is feed to a cooler. The flyash sewage sludge mixture has a significant fuel value that is usable in the kiln. Furthermore, the fuel valve available in the kiln off-gases may be used for drying the materials.