Abstract: A new and improved method and apparatus for altering the firing pattern of an existing furnace of the type including at least one pair of vertically spaced apart burners mounted on a wall of the furnace and supplied with secondary air from a common windbox. The method involves cutting a rectangular panel from the furnace wall around a first burner wherein the burner is located asymmetrically toward a first panel end and spaced farther away from a vertically opposite second end of the panel. The cut-out panel is then reversed in orientation from end to end so that the first burner is then spaced farther apart at a greater distance from a second burner. The panel is reinstalled in the furnace wall in reverse orientation thereby providing a greater spacing or staging distance between the first and second burners producing a reduced level of NO.sub.x when the burners are fired.

Abstract: A flame retaining nozzle tip for a burner for a pulverized fuel fired furnace receiving a primary stream of pulverized fuel and primary transport and combustion air for discharge into the combustion zone of the furnace comprises a hollow, open-ended, choke or body having an inlet end of generally polygonal flow cross-section for receiving the stream and an outlet end of generally rounded cross-section for accelerating and discharging the stream into the furnace. The outlet end of the choke has a flow cross-sectional area that is less than that of the inlet end to provide choking action. An elongated center element is mounted in coaxial alignment with a central axis of the choke body extending between the inlet and outlet ends.

Abstract: Apparatus for reburning ash material of a previously burned primary fuel includes a reburn combustion vessel having an inlet for receiving ash material from a primary combustion unit such as a boiler or furnace and an outlet for discharging the products of combustion from the vessel produced from burning the ash material. The outlet of the ash reburn vessel is connected to the primary combustion unit at an elevated height above the firing level. A floor is provided in the ash reburn vessel for supporting a discrete bubbling bed of burning ash material and the floor includes a plurality of spaced apart openings distributed relatively uniformly over substantially all of the area of the floor. Combustion air is introduced into the reburn vessel at a relatively low velocity to provide a source of underfire combustion air for the bubbling bed.

Abstract: A device for promoting the flow rate of solid particulates from a fluidized bed of solids into a downcomer extending from a discharge outlet in a wall or the bed includes a hollow, funnel-like, horn element having a lower end connected upstream of the discharge outlet and an upper end portion spaced upwardly of the lower end and flared outwardly at progressively higher levels to form an enlarged flow entrance for the fluidized solid particulates to move from said bed toward said discharge outlet into the downcomer. The funnel-like, horn element has an enlarged open upper end formed with a rim around the flow entrance spaced above the lower wall of the bed and has a flow cross-section substantially greater than that of the discharge outlet. A bubble ring is provided adjacent the rim for injecting gaseous fluid into the solids to fluidize the solid particulates for movement in a generally horizontal direction towards a center axis of the flow entrance of the funnel-like, horn element.

Abstract: A vertical tube heat exchanger for use with fluidized solid particulates as a heat transfer medium includes a plurality of vertically extending spaced apart tubes for containing an internal fluid flowing in heat transfer relationship with the walls of the tube. A containment housing is provided around the tubes for containing a flow of fluidized solid particulates moving through a heat exchange chamber in the housing around the exterior surface of the tubes. A gas plenum chamber is provided adjacent a lower end of the containment housing for directing fluidizing gas into the solid particulates. The housing includes a dividing floor between an upper heat exchange chamber and a lower plenum chamber and the floor is formed with openings in concentric alignment with the vertical tubes for injecting fluidizing gas into the heat exchange chamber around the tubes to flow upwardly into a bed of solid particulates.

Abstract: An integrated, vertical tube heat exchanger for use with a plurality of heat transfer mediums including fluidized solid particulates and hot gaseous products of combustion includes a plurality of vertically extending spaced apart, tubes for containing water/steam flow in close heat transfer relationship with the walls of the tubes. A unitary and compact containment housing is provided around a bank of said vertical tubes for directing a generally lateral flow of fluidized solid particulates moving through a first heat exchange chamber formed around the exterior surface of lower portions of the tubes. A gas plenum chamber is provided adjacent a first end of the lower heat exchange chamber for directing fluidizing gas into the solid particulates in the chamber. The housing is provided with a dividing wall forming a second heat exchange chamber that is separate from and operationally independent of the first heat exchange chamber.

Abstract: A heat exchanger for use in a multi-solid fluidized bed heat generating system includes a housing for containing a flowing volume of hot gas and fluidized recirculating solid particulate material. The housing includes outer side walls, a top wall and an intermediate bottom structure comprising water wall panels for containing a flow of water/steam to be heated from the hot gas and solid material contained within the enclosure formed by the housing walls. A supply header is provided to direct water/steam to be heated into the water wall panels at a lower level and a takeoff header is utilized for removing the heated water/steam from the wall panels at an upper level. A fluidizing gas injector system is provided for directing a high velocity flow of gaseous fluid into the enclosure formed by the housing water wall panels at a lower level therein for fluidizing the recirculating solid particulate material, which material is recycled back into a combustion vessel of the fluidized bed heat generating system.

Abstract: A fluidized bed steam generating system includes an upstanding combustion vessel, a gas/solids separator, a convection pass boiler and a heat exchanger positioned directly below the boiler and all of the above elements except the gas/solids separator are enclosed within a waterwall structure having outside waterwalls and a central waterwall common to the reactor vessel on one hand and the convection pass boiler and heat exchanger on the other hand. The close proximity of the components of the system eliminate numerous problems present in conventional multi-solid fluidized bed steam generators.

Abstract: A new and improved system for feeding solid particulate material such as refuse derived fuel for burning in a combustion reactor vessel such as a boiler includes a fuel injector chute having a lower end for directing a flow of said solid particulate material into the vessel and an upper end for receiving a flow of said material. A feeder is provided having a discharge end for delivering a continuous controllable flow of said material to the inlet of the injector chute and a plurality of separate, spaced apart, vibratory feed hoppers are mounted above the feeder to supply the feeder with a steady flow of material from one or both hoppers. Each hopper is adapted for holding a reservoir or supply of said solid particulate material and is selectively controllable to provide a steady flow of solid particulate material into the feeder for delivery through the injector chute to the combustion reactor vessel.

Abstract: A fluidized bed heat generator includes a combustion reactor vessel containing a recirculating flow of fluid entrained fine solid particulate material with a dense bed section of limited space in the vessel containing a fluidized coarse solid particulate material retained therein. A recirculating path defined in part within the vessel and externally thereof provides for a recirculating flow of said fine solid particulate material into and out of the combustion vessel and through the coarse material of the dense bed section. Air or gas is supplied for fluidizing the coarse solid particulate material in the dense bed section and for entraining the fine solid material to flow through the dense bed and around the recirculating path. A separator system is provided for maintaining both the fine solid particulate material and the coarse solid particulate material in the dense bed section within selected particle size ranges to promote maximum efficiency of operation at variable loads.

Abstract: A flow control device for solid particulate material such as recycled granular solids utilized in a fluidized bed combustion vessel includes a generally horizontal material feeder conduit having an outlet end in communication with the fluidized bed of the combustion vessel and a receiving end remote therefrom. An upstanding material collector conduit having a lower end in communication with a receiving end of the feeder conduit is provided and an upper end of the collector conduit is adapted to receive a flow of particulate solid material to be fed at a controlled flow rate into the combustion vessel. The upstanding collector conduit forms a standpipe for retaining a quantity of material to establish a pressure sealing head or column of material extending upwardly of the receiving end of the feeder conduit.

Abstract: A furnace, a burner and a method for burning pulverized coal in a highly efficient and precisely controlled manner includes a tubular nozzle with a venturi flow control adjacent the outlet for directing a primary air and coal mixture into a primary combustion zone of the furnace for burning. A coal spreader is mounted in the divergent outlet section of the venturi and swirl vanes on the spreader divide and form the stream into plurality of fuel rich and fuel lean streams discharged into the combustion zone. A tubular conduit in coaxial alignment around the coal nozzle directs a swirling flow of secondary air into the combustion zone around the primary combustion zone and a plurality of tertiary air conduits spaced outwardly of the secondary air conduit are provide to introduce directionally controllable streams of tertiary air into the combustion zone.

Abstract: A new and improved burner for pulverized coal comprises a tubular nozzle for containing a primary, flowing stream of coal/air mixture having an outlet for discharging the stream into a combustion zone of a furnace. A venturi is mounted in the nozzle having a convergent section, a throat, and divergent flow section adjacent the outlet. The convergent section concentrates the pulverized coal toward a central portion of the flowing stream in the throat of the venturi. A conical flow spreader is mounted in the divergent section and includes a hollow, open outer end.

Abstract: A method of burning pulverized coal and other fuels comprises the steps of containing a primary flowing stream of coal/air mixture received adjacent an inlet end of a tubular nozzle for discharge at an outlet end into a combustion zone of a furnace for burning. The stream is accelerated in a convergent venturi section upstream of the outlet to distribute and concentrate the coal particles toward a central portion of the venturi in a minimum area throat, followed by decelerating the flow downstream of the venturi throat in a convergent flow section while forming a shallow, annular, conically shaped flow pattern around a hollow spreader cone mounted in the convergent section.