Fast fluidized bed reactor and method of operating the reactor

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

• providing a substantially upright 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;
• feeding matter to be reacted into said lower region of the reactor;
• supplying a first stream of pressurized air to said reactor 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 said granular material is continually entrained upward into said upper region;
• tangentially supplying a second stream of pressurized air to said upper region of the reactor through at least one opening in said cylindrical interior surface;
• 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 providing a cyclone of turbulence in said upper region which increases the rate of reaction in the reactor, wherein, at maximum operating capacity for the reactor, said second stream of air constitutes in excess of about 50% of the total pressurized air fed to the reactor;
• removing a portion of the granular material and the reaction gases from said upper region of the reactor through an exit port situated adjacent the upper boundary of said cyclone of turbulence;
• providing a cyclone separator operatively connected between said exit port and said lower region for separating said portion of the granular material from said reaction gases in said separator and returning said separated granular material to said lower region of the reactor, and
• further comprising the step of providing a fluidized bed trap operatively connected between said cyclone separator and said lower region of the reactor for receiving the separated granular material from the cyclone separator and overflowing it into said lower region of the reactor, said fluidized bed trap containing a solid partition for eliminating cross flow of gases between said reactor and said cyclone separator.

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

• providing a substantially upright 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;
• feeding matter to be combusted into said lower region of the reactor;
• supplying a first stream of pressurized air 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 upward into said upper region;
• tangentially supplying a second stream of pressurized air to said upper region of the reactor through at least one opening in said cylindrical interior surface;
• 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 high turbulence and at least one, internally generated recirculation zone in said upper region which increases the rate of combustion in the reactor, wherein, at maximum operating capacity for the reactor, said second stream of air constitutes in excess of about 50% of the total pressurized air fed to the reactor;
• providing a closed annular chamber concentrically surrounding at least the upper portion of said upper region of the reactor and operatively connected at its lower end to said lower region of the reactor, said interior surface having an annular gap located in its upper portion and extending into said annular chamber;
• and
• passing at least a portion of the turbulently flowing entrained granular material from said upper region of the reactor through said gap and into said annular chamber by centrifugal force, thereby separating said portion of the granular material from the gases present in said upper region;
• and returning said separated granular material by the force of gravity through said lower end of the annular chamber into said lower region of the reactor.

In a method of operating an upright circulating fluidized bed combustion reactor containing material to be combusted and a bed of granular material fluidized by a first stream of pressurized air at a velocity sufficient to fluidize said granular material in the circulating regime, so as to entrain at least a substantial portion of the granular material in said first stream, thereby elevating said portion into a cylindrically shaped upper region of the reactor, said elevated portion being then externally returned from said upper region to said bed of granular material, the improvement comprising:

• creating a cyclonic flow of turbulent gases and at least one, internally generated recirculation zone in said upper region of the reactor for turbulently flowing a portion of the material to be reacted, any gases present in said upper region, and said entrained portion of granular bed material by tangentially introducing a second stream of pressurized air into said upper region through at least two symmetrically arranged openings in the interior wall of the reactor, said second stream of air and the geometry of said upper region of the reactor being jointly adapted to maintain a Swirl number of at least about 0.6 and a Reynolds number of at least about 18,000 in said upper region, wherein at maximum operating capacity for the reactor, said second stream of air constitutes in excess of about 50% of the total pressurized air fed to the reactor;
• and
• removing said entrained portion of granular material and the combustion gases from said upper region of the reactor adjacent the upper boundary of said cyclone of turbulent gases.

A fast fluidized bed reactor, comprising:

• (a) a substantially upright 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;
• (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 and 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, said second stream being supplied, and said reactor being constructed, in a manner adapted to 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, 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;
• and
• (e) cyclone separator means for separating the granular material and the reaction gases exiting from said reaction chamber and returning the separated granular material to said lower region of the reaction chamber, said cyclone separator means being operatively connected between an exit port in said reaction chamber situated adjacent to the upper boundary of said cyclone of turbulence and an inlet port located in said lower region of said reaction chamber, and further comprising a fluidized bed trap operatively connected between said cyclone separator and said inlet port for receiving the separated granular material from the cyclone separator and overflowing it into said inlet port, said fluidized bed trap containing a solid partition for eliminating cross flow of gases between said reaction chamber and said cyclone separator.