Internal circulating fluidized bed type boiler and method of controlling the same

A method of controlling an internal recycling type fluidized bed boiler constructed by comprising:

• a primary fluidized bed incinerating chamber constructed by an air diffusion plate provided at the bottom of an incinerator and adapted to inject fluidizing air upwardly under a mass flow that is at least greater at one side than that at another side;
• an inclined partition wall provided above a portion of said diffusion plate 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 another side of said diffusion plate where the mass flow is smaller;
• a thermal energy recovery chamber formed between said inclined partition wall and a side wall of the incinerator or between the back sides of two inclined partition walls;
• a heat exchanging surface means provided within said thermal energy recovery chamber for the passage of a heat sink fluid therethrough;
• and
• an air diffuser provided at a lower portion of said thermal energy recovery chamber and a back side of said inclined partition wall;
• said thermal energy recovery chamber being communicated at upper and lower portions thereof with said primary fluidized bed incinerating chamber;
• said method comprising regulating the amount of air injected from said diffusion plate so that a moving bed is formed above the portion of said diffusion plate where the injected mass flow is smaller with a fluidizing medium descending and diffusing within said moving bed, and a circulating fluidized bed is formed above the portion of the diffusion plate where the mass flow of the fluidizing air is greater with said fluidizing medium being actively fluidized and circulated towards a position above said moving bed and a part of said fluidizing medium being introduced into said thermal energy recovery chamber beyond an upper portion of said inclined partition wall, the fluidizing air being injected from said diffuser in said recovery chamber so as to cause said fluidizing medium within said recovery chamber to descend and recycle in the state of a moving bed, controlling the amount of thermal energy recovered by said thermal energy recovery chamber by the regulation of the amount of gas injected from said diffuser in said recovery chamber based on demands from a user side utilizing generated vapor and hot water, and controlling the amount of fuel supplied to the primary fluidized bed incinerating chamber based on the temperature of said primary fluidized bed incinerating chamber.

A method of controlling a fluidized bed boiler, including an incinerator containing a primary fluidized bed of fluidizing medium and a diffusor means, a thermal energy recovery chamber containing a thermal recovery bed of fluidizing medium and an auxiliary diffusor means, an inclined partition wall separating said primary fluidized bed and said thermal recovery bed with said primary fluidized bed and said thermal recovery bed being in communication with each other at upper and lower ends thereof, a heat exchanging surface means provided within said thermal recovery bed for the passage of a fluid therethrough, said method comprising:

• supplying a fluidizing gas from said diffusor means at a higher mass flow rate to a region below said inclined partition wall than to a region opposite said partition wall, and thereby forming a rising bed at said inclined partition wall and a descending bed opposite said inclined partition wall, with said rising and descending beds forming a circulating bed;
• controlling the mass flow of said fluidizing gas from said diffusor means to said region of said inclined partition wall such that part of the fluidizing medium in said circulating bed flies upwardly and reaches said energy recovery chamber;
• and
• regulating the mass flow of a gas supplied by said auxiliary diffusor means to said thermal recovery bed, thereby controlling the overall coefficient of heat transfer and thus controlling the amount of thermal energy recovered by said fluid passing through said heat exchanging surface means.

A fluidized bed boiler comprising:

• an incinerator including a primary fluidized bed and a diffusor means for supplying thereto different amounts of a fluidizing gas;
• a thermal energy recovery chamber including a thermal recovery bed and an auxiliary diffusor means for supplying thereto a gas;
• an inclined partition wall separating said primary fluidized bed and said thermal recovery bed such that said primary fluidized bed and said thermal recovery bed are in communication with each other at upper and lower ends thereof;
• heat exchanging surface means, provided within said thermal recovery bed, for the passage of a fluid therethrough;
• said auxiliary diffusor means being located at a lower portion of said thermal energy recovery chamber, and said thermal recovery chamber having adjacent said lower portion thereof an opening to enable material of said thermal recovery bed to move downwardly through said opening from said thermal energy recovery chamber to said incinerator;
• and
• a portion of said diffusor means being beneath said inclined partition wall and providing an upward mass flow of said fluidizing gas in the area of said inclined partition wall that is larger than the mass flow provided by other parts of said diffusor means.