Integral fluidized bed heat exchanger in an energy producing plant

A process for controlling bed temperature of a circulating fluidized bed in a fluidized bed reactor comprising:

• introducing carbonaceous material into a fluid bed in an upright reactor;
• fluidizing the carbonaceous material in said fluid bed with a primary fluidizing gas introduced at the bottom of said bed, introducing a secondary gas into said fluid bed at a level above that at which the primary gas is introduced and above the bottom of the fluid bed, at least the secondary gas containing oxygen;
• burning the carbonaceous material with the oxygen;
• separating solids from a gas effluent from said bed to collect solid particles;
• measuring the temperature of the gas effluent and in dependence therein controlling the relative amount of solids fed into a second chamber;
• said second chamber housing heat transfer means and having a wall section common to said second chamber and said reactor, said common wall having at least one perforation therein adapted for fluid communication between said second chamber and said reactor;
• fluidizing said solids in said second chamber to operate under bubbling bed conditions with a high pressure fluidizing gas;
• and
• maintaining the pressure of the higher pressure fluidizing gas in said second chamber at a pressure higher than that in the reactor to cause said fluidizing gas and solids to flow through said perforation thereby controlling the temperature of the bed in the reactor.