Patent ID: 8539891

Claim:
A method for reducing an air/fuel ratio required to convey pulverized coal through feeder pipes of a coal burner in suspended condition without settling out and into a primary combustion zone of the coal burner, the method comprising, obtaining an initial coal having a dry basis ash content and density such that pulverized initial coal with 70% passing through a 200 mesh screen and at least 99% passing through a 50 mesh screen made from the initial coal requires a first air/fuel ratio to maintain the pulverized initial coal in suspended condition without settling out when conveyed through the feeder pipes of the coal burner; cleaning the initial coal to reduce the dry basis ash content by at least about 20% and thereby yield a refined coal having a reduced density compared to the density of the initial coal; pulverizing the refined coal to yield pulverized refined coal; conveying the pulverized refined coal in suspended condition without settling out through the feeder pipes of the coal burner to the primary combustion zone using a second air/fuel ratio that is reduced by at least about 5% compared to the first air/fuel ratio required to maintain pulverized initial coal in suspended condition without settling out when conveyed through the feeder pipes of the coal burner; and burning the pulverized refined coal in the primary combustion zone of the coal burner.