Pressurized internal circulating fluidized-bed boiler

A pressurized internal circulating fluidized-bed boiler for use in a combined-cycle electric generating system, comprising:

• a pressure vessel;
• a combustor disposed in said pressure vessel and having a cylindrical outer wall;
• a main fluidized bed combustion chamber having an air diffusion device provided at the bottom of said combustor and adapted to inject fluidizing air upwardly under a mass flow that is at least greater at an outer side than that at a central side;
• a partition having a cylindrical partition and a conical partition formed at an upper portion of said cylindrical partition, said conical partition being provided above a portion of said air diffusion device where the mass flow is greater so as to interfere with the upward flow of the fluidizing air and thereby to deflect the air towards a portion above said central side of said air diffusion device where the mass flow is smaller;
• an annular thermal energy recovery chamber partitioned from said main combustion chamber by said partition;
• a heat transfer surface means provided in said thermal energy recovery chamber for a passage of a heat receiving fluid therethrough;
• and
• an air diffuser provided at a lower portion of said thermal energy recovery chamber;
• wherein said thermal energy recovery chamber is communicated at upper and lower portions thereof with said main fluidized bed combustion chamber, a moving bed is formed above the portion of said air diffusion device where the injected mass flow is smaller so that a fluidized medium descends and diffuses within the moving bed, and a circulating fluidized bed is formed above the portion of said air diffusion device where the mass flow of the fluidizing air is greater so that said fluidized medium is intensely fluidized and whirled towards a position above said moving bed and a part of said fluidized medium is introduced into said thermal energy recovery chamber beyond an upper portion of said conical partition, the formation of said moving bed and said circulating fluidized bed is effected by regulation of the amount of air injected upwardly from said air diffusion device in said main combustion chamber and regulation of the fluidizing air injected from said air diffuser in said thermal energy recovery chamber causes the fluidized medium within said thermal energy recovery chamber to descend in a state of a moving bed for circulation to said main combustion chamber.

A topping-cycle combined electric generating system including a gasifier for generating a gas and char, an oxidizer for combusting said char to produce combustion gas, and a gas turbine which is driven by a high-temperature gas produced by combusting mixture of said generated gas and said combustion gas, at least one of said gasifier and said oxidizer comprising a pressurized internal circulating fluidized-bed boiler which comprises:

• a pressure vessel;
• a combustor disposed in said pressure vessel and having a cylindrical outer wall;
• a main fluidized bed combustion chamber having an air diffusion device provided at the bottom of said combustor and adapted to inject fluidizing air upwardly under a mass flow that is at least greater at an outer side than that at a central side;
• a partition having a cylindrical partition and a conical partition formed at an upper portion of said cylindrical partition, said conical partition being provided above a portion of said air diffusion device where the mass flow is greater so as to interfere with the upward flow of the fluidizing air and thereby to deflect the air towards a portion above said central portion of said air diffusion device where the mass flow is smaller;
• an annular thermal energy recovery chamber partitioned from said main combustion chamber by said partition;
• a heat transfer surface means provided in said thermal energy recovery chamber for a passage of a heat receiving fluid therethrough;
• and
• an air diffuser provided at a lower portion of said thermal energy recovery chamber;
• wherein said thermal energy recovery chamber is communicated at upper and lower portions thereof with said main fluidized bed combustion chamber, a moving bed is formed above the portion of said air diffusion device where the injected mass flow is smaller so that a fluidized medium descends and diffuses within the moving bed, and a circulating fluidized bed is formed above the portion of said air diffusion device where the mass flow of the fluidizing air is greater so that said fluidized medium is intensely fluidized and whirled towards a position above said moving bed and a part of said fluidized medium is introduced into said thermal energy recovery chamber beyond an upper portion of said conical partition, the formation of said moving bed and said circulating fluidized bed is effected by regulation of the amount of air injected upwardly from said air diffusion device in said main combustion chamber and regulation of the fluidizing air injected from said air diffuser in said thermal energy recovery chamber causes the fluidized medium within said thermal energy recovery chamber to descend in a state of a moving bed for circulation to said main combustion chamber.

An integral type of fluidized-bed furnace for use in a topping-cycle combined electric generating system, comprising:

• a cylindrical outer wall;
• a cylindrical partition provided concentrically with said cylindrical outer wall;
• a gasifier formed inside said cylindrical partition;
• an oxidizer formed between said cylindrical outer wall and said cylindrical partition;
• an air diffusion device provided at the bottom of said gasifier and adapted to inject fluidizing air upwardly under a mass flow that is at least greater at an outer side than that at a central side;
• a conical partition formed on said cylindrical partition, said conical partition being provided above a portion of said air diffusion device where the mass flow is greater so as to interfere with the upward flow of the fluidizing air and thereby to deflect the air towards a portion above said central side of said air diffusion device where the mass flow is smaller;
• an air diffuser provided at a lower portion of said oxidizer;
• and
• a first free board defined above said gasifier and a second free board defined above said oxidizer, said first and second free boards being separated from each other by said cylindrical partition so that a gas produced by said gasifier and combustion gas from said oxidizer are separately discharged towards the outside;
• wherein said oxidizer is communicated at intermediate and lower portions thereof with said gasifier, a moving bed is formed above the portion of said air diffusion device where the injected mass flow is smaller so that a fluidized medium descends and diffuses within the moving bed, and a circulating fluidized bed is formed above the portion of said air diffusion device where the mass flow of the fluidizing air is greater so that said fluidized medium is intensely fluidized and whirled towards a position above said moving bed and a part of said fluidized medium is introduced into said oxidizer through an opening formed in an intermediate portion of said partition, the formation of said moving bed and said circulating fluidized bed is effected by regulation of the amount of air injected upwardly from said air diffusion device in said gasifier and regulation of the fluidizing air injected from said air diffuser in said oxidizer causes the fluidized medium within said oxidizer to descend in a state of a moving bed for circulation to said gasifier.