Method and apparatus for preheating a rotatable fluidizable bed

A method for preheating a rotating fluidized bed combustor to the ignition temperature of the exothermic combustion reaction desired to occur therein, said combustor including an elongated fluidization chamber having a longitudinally extending axis and a perforated peripheral wall, a bed of pulverulent solid particles in said chamber, heating means in thermal communication with said bed, means for rotating said chamber about said axis to cause the particles to centrifugally gravitate toward said perforated peripheral wall and means for selectively initiating a flow of combustible fuel in a gaseous agent stream into said chamber through said peripheral perforated wall, said gaseous agent stream fluidizing said bed particles and said fuel reacting with said gaseous agent in said chamber, said method comprising the steps of:

• (a) slowly rotating said chamber at a speed sufficient to cause tumbling and mixing of said bed particles but insufficient to cause centrifugal gravitation toward said peripheral wall prior to initiating the flow of said gaseous agent stream;
• and
• (b) applying thermal energy to said tumbling particles to heat said particles to said ignition temperature.