Circulating fluidized bed boiler with bottom-supported in-bed heat exchanger

A circulating fluidized bed (CFB) boiler comprising:

• a CFB reaction chamber having walls and an open-bottom grid defining a floor at a lower end of the CFB reaction chamber for providing fluidizing gas into the CFB reaction chamber;
• at least one 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, with the fluidizing gas feed to the BFB portion of the grid controlled separately from the fluidizing gas feed to the CFB portion of the grid;
• at least one controllable in-bed heat exchanger (IBHX), the IBHX occupying part of the CFB reaction chamber floor and being surrounded by the enclosure walls of the BFB;
• hoppers containing dormant solids disposed under the CFB and the BFB;
• and
• the enclosure walls of the BFB being supported off the bottom-supported hoppers.

A circulating fluidized bed (CFB) boiler comprising:

• a CFB reaction chamber having walls and an open-bottom grid defining a floor at a lower end of the CFB reaction chamber for providing fluidizing gas into the CFB reaction chamber;
• at least one 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, with the fluidizing gas feed to the BFB portion of the grid controlled separately from the fluidizing gas feed to the CFB portion of the grid;
• the enclosure walls of the BFB are of cooled membrane gas-tight design;
• at least one controllable in-bed heat exchanger (IBHX), the IBHX occupying part of the CFB reaction chamber floor and being surrounded by the enclosure walls of the BFB;
• hoppers containing dormant solids disposed under the CFB and the BFB;
• and
• the enclosure walls of the BFB being connected to at least one of the bottom-supported hoppers with supports and becoming of a loose design with sufficient flexibility for accommodating differences in thermal expansion of the tubes and the hopper as the tubes penetrate the hopper wall.