| 摘要 |
A fluidized bed gas-solids contact reactor, which utilizes at least one capped concentric dual-sided riser-downcomer unit having a central inner riser passageway and a concentric outer downcomer passageway. The riser-downcomer unit is usually located above the fluidized bed, and is adapted for directing the downflowing solids back into the fluidized bed for recycle. The reactor unit inner and outer passageway surfaces include a heat exchange panel having inner and outer channels each containing a circulating liquid. Particulate solids from the dense phase fluidized bed are continuously circulated in dilute phase through the riser-downcomer unit passageways by a reactant gas to exchange heat with the liquid. The particulate solids can be a catalyst or a fuel material. The invention also includes a combustion system and method for combusting a particulate fuel such as coal in air to generate pressurized saturated liquid for producing saturated steam. The coal feed particles are substantially completely reacted or combusted during their controlled passage through the reactor unit, and ash can be withdrawn from the lower portion of the fluidized bed.
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