Double-stepping fuel combustion method and its double-stepping cyclone burner

THe present invention relates to a double fractional combustion method for fuel and its double fractional cyclone combustor, and is characterized by that the coal powder carried by first air is fed into the first air channel of combustor, in first air channel the first air and coal powder mixed material is passed through the venturitube and separated into concentrated phase and dilute phase, the concentrated phase air powder mixture is sprayed out from first air channel, and the dilute phase air powder mixture is passed through the first air channel and secondary air channel communicated place in the interior of the combustor, and fed into secondary air channel and mixed with secondary air, and is sprayed out from secondary air channel. Said combustor is simple in structure, and its combustion is full and stable.