Patent ID: 8316782

Claim:
An indirect heating system in which a solid fuel circulates in the form of particles, comprising: a grinding station that grinds the solid fuel into coarse particles that require re-grinding, fine particles having an average diameter smaller than the coarse particles, but larger than 75 microns and particles having an average diameter less than 75 microns referred to as ‘ultrafine particles’, and releases them as a stream of flowing particles; a separator receives the stream from the grinding station and intercepts the coarse particles from the stream passing them back to the grinding station; an intermediate silo adapted to store fine particles, at least one main burner adapted to burn fine particles; at least one cyclone that receives the stream from the separator, and intercepts the fine particles from the stream and stores the fine particles in an intermediate silo, until they are provided to the main burner; and a dust extractor receives the stream after the cyclone and intercepts the ultrafine particles from the stream; at least one dedicated burner adapted to burn ultrafine particles; a second intermediate silo that receives the ultrafine particles from the dust extractor, wherein the ultrafine particles are then provided by a dedicated pipe to the dedicated burner for burning in the combustion chamber; and a feeder that controls the amount of ultrafine particles provided from the second intermediate silo to the dedicated burner.