Fast fluidized bed reactor and method of operating the reactor

A fast fluidized bed reactor, comprising:

• (a) a fluidized bed reaction chamber for containing a bed of granular material, said chamber having an upper region and a lower region, said upper region having a cylindrically shaped interior surface and a cylindrically shaped exit throat aligned concentrically with said interior surface, said exit throat having a diameter within the range of from about 4/10 to about 7/10 the diameter of said interior surface;
• (b) means for feeding matter to be reacted into said lower region of the reaction chamber;
• (c) means for supplying a first stream of pressurized air to said reaction chamber through a plurality of openings at the bottom of said lower region at a sufficient velocity to fluidize said granular material in the circulating regime, whereby at least a substantial portion of the granular material is continually entrained upward into said upper region;
• and
• (d) means for tangentially supplying a second stream of pressurized air to said upper region of the reaction chamber through at least one opening in said cylindrically shaped interior surface, wherein, at maximum operating capacity for the reactor, the second stream of air constitutes in excess of about 50% of the total pressurized air fed to the reaction chamber, said second stream being supplied, and said reactor being constructed, in a manner adapted to:
• (i) provide a Swirl number of at least about 0.6 and a Reynolds number of at least about 18,000 in said upper region, thereby creating a cyclone of turbulence in said entrained bed material and any gases present in the upper region which increases the rate of reaction in said chamber and internally generates at least one reverse flow zone in said upper region for returning said entrained bed material to said lower region of said chamber, and (ii) permit the gases resulting from the reaction in said chamber to exit from said reaction chamber through said exit throat while retaining substantially all of said entrained granular material within said chamber.

A fast fluidized bed reactor, comprising:

• (a) a fluidized bed reaction chamber for containing a bed of granular material, said chamber having an upper region and a lower region, said upper region having its longitudinal axis aligned substantially horizontally and having a cylindrically shaped interior surface and a cylindrically shaped exit throat aligned concentrically with said interior surface, said exit throat having a smaller diameter than that of said interior surface;
• (b) means for feeding matter to be reacted into said lower region of the reaction chamber;
• (c) means for supplying a first stream of pressurized air to said reaction chamber through a plurality of openings in said lower region at a sufficient velocity to fluidize said granular material in the circulating regime, whereby at least a portion of the granular material is continually entrained upward into said upper region;
• (d) means for tangentially supplying a second stream of pressurized air to said upper region of the reaction chamber through at least one opening in said cylindrically shaped interior surface, wherein, at maximum operating capacity for the reactor, the second stream of air constitutes in excess of about 50% of the total pressurized air fed to the reaction chamber, said second stream being supplied, and said reactor being constructed, in a manner adapted to:
• (i) provide a Swirl number of at least about 0.6 and a Reynolds number of at least about 18,000 in said upper region, thereby creating a cyclone of turbulence in the upper region which increases the rate of reaction in said chamber and creates at least one reverse flow zone in said upper region for returning at least a portion of said granular material to said lower region of said chamber, and (ii) permit the reaction gases in said upper region to exit from said reaction chamber through said exit throat while retaining substantially all of said granular material within said chamber;
• and
• (e) a fire tube boiler having its central fire tube fluidly connected to said reaction chamber exit throat, whereby said reaction gases exiting from said chamber supply heat to said fire tube boiler, said fire tube including:
• a substantially flat plate situated beneath said exit throat and extending essentially the entire length of said fire tube, wherein the fly ash contained in said reaction gases collects on said plate;
• and
• means for providing a plurality of streams of gas flowing toward the end of said fire tube opposite from said exit throat for directing said collected fly ash out of said fire tube through said opposite end, the end of said boiler adjacent said opposite end being adapted to collect said fly ash to permit removal thereof from said boiler, and
• wherein said means for providing a plurality of streams of gas includes:
• a plurality of nozzles extending through said plate, said plate being sealingly engaged in said fire tube to form a plenum chamber for supplying gas to said nozzles;
• and
• means for supplying gas to said plenum chamber.

A method of operating a circulating fluidized bed reactor, comprising:

• providing a fluidized bed reactor containing a bed of granular material and having an upper region and a lower region, said upper region having a cylindrically shaped interior surface and a cylindrically shaped exit throat aligned concentrically with said interior surface, said exit throat having a diameter within the range of from about 4/10 to about 7/10 the diameter of said interior surface;
• feeding matter to be reacted into said lower region of the reactor;
• supplying a first stream of pressurized gaseous material to said reactor through a plurality of openings at the bottom of said lower region at a sufficient velocity to fluidize said granular material in the circulating regime, whereby at least a substantial portion of said granular material is continually entrained into said upper region;
• tangentially supplying a second stream of pressurized gaseous material to said upper region of the reactor through at least one opening in said cylindrical interior surface, wherein, at maximum operating capacity for the reactor, said second stream of gaseous material constitutes in excess of about 50% of the total pressurized gaseous material fed to the reactor;
• maintaining a Swirl number of at least about 0.6 and a Reynolds number of at least about 18,000 in said upper region for inducing in said entrained bed material and any gases present in said upper region a cyclone of turbulence which increases the rate of reaction in the reactor and internally generates at least one reverse flow zone in said upper region for returning said entrained bed material to said lower region of the reactor;
• and
• permitting the gases resulting from the reaction in said reactor to exit from the reactor through said exit throat, while retaining substantially all of said entrained granular material within the reactor.