In-bed solids control valve

A circulating fluidized bed (CFB) boiler comprising:

• a CFB reaction chamber having side walls and a grid defining a floor at a lower end of the CFB reaction chamber for providing fluidizing gas into the CFB reaction chamber;
• a bubbling fluidized bed (BFB) located within a lower portion of the CFB reaction chamber, the BFB being above a grid for providing fluidizing gas into the BFB, and being bound by enclosure walls and the floor of the CFB reaction chamber;
• at least one controllable in-bed heat exchanger (IBHX), the IBHX occupying a lower part of the CFB reaction chamber and being surrounded by the enclosure walls of the BFB;
• and
• at least one non-mechanical valve designed to permit the control of solids discharge from the BFB into the CFB reaction chamber, the valve including at least one opening in the enclosure wall of the BFB, at least one independently controlled first fluidizing means located upstream of the at least one opening in the enclosure wall, at least one independently controlled second fluidizing means located downstream of the at least one opening in the enclosure wall,
• wherein the first and second independently controlled fluidizing means are separately controllable from the at least one grid;
• wherein the elevation of the bottom of the at least one non-mechanical valve opening in the enclosure wall being at or above the top of both of the independently controlled first and second fluidizing means,
• wherein the at least one IBHX is selected from one or more of a superheater, a reheater, an economizer or an evaporative surface, and
• wherein the tubes of the at least one IBHX are protected by a layer of erosion- resistant material formed on the surface of the tubes in the vicinity of the at least one opening.

A circulating fluidized bed (CFB) boiler comprising:

• a CFB reaction chamber having side walls and a grid defining a floor at a lower end of the CFB reaction chamber for providing fluidizing gas into the CFB reaction chamber;
• a bubbling fluidized bed (BFB) located within a lower portion of the CFB reaction chamber and being bound by enclosure walls and the floor of the CFB reaction chamber;
• at least one controllable in-bed heat exchanger (IBHX), the IBHX occupying part of the lower end of the CFB reaction chamber and being surrounded by the enclosure walls of the BFB;
• at least one non-mechanical valve designed to permit the control of solids discharge from the BFB into the CFB reaction chamber, the valve including at least one opening in the enclosure wall of the BFB, at least one independently controlled first fluidizing means located upstream of the at least one opening in the enclosure wall, at least one independently controlled second fluidizing means located downstream of the at least one opening in the enclosure wall, and
• at least one flow control barrier that is located downstream of the at least one opening in the enclosure wall, wherein the elevation of the top of the flow control barrier is at or above the elevation of the bottom of the at least one opening in the enclosure wall.