Method for reducing air flow when operating a coal burner

A method for reducing air flow required to convey pulverized coal through feeder pipes of a coal burner in suspended condition and into a primary combustion zone of the coal burner, the method comprising,

• obtaining an initial coal having a dry basis ash content of at least 30% and a first density such that pulverized initial coal made from the initial coal requires a first quantity of air 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 yield refined coal having a second dry basis ash content of less than about 20% and a second density that is lower than the first density;
• pulverizing the refined coal to yield pulverized refined coal;
• conveying the pulverized refined coal in suspended condition through the feeder pipes of the coal burner to the primary combustion zone using a second quantity of air that is less than the first quantity of air required to maintain pulverized initial coal in suspended condition when conveyed through the feeder pipes of the coal burner and so as to;
• burning the pulverized refined coal in the primary combustion zone of the coal burner with an air/fuel ratio of less than about 2;
• and
• introducing a secondary air and/or tertiary air into the coal burner so as to maintain a combustor exit oxygen level of at least about 2%.

A method for reducing air flow required to convey pulverized coal through feeder pipes of a coal burner in suspended condition and into a primary combustion zone of the coal burner, the method comprising,

• providing a refined coal obtained by cleaning an initial coal having a first dry basis ash content, a first density, and a first carbon content such that pulverized initial coal made from the initial coal requires a first quantity of air to maintain the pulverized initial coal in suspended condition without settling out when conveyed through the feeder pipes of the coal burner,
• the refined coal having a second dry basis ash content that is reduced by at least about 20% compared to the first dry basis ash content of the initial coal, a second density lower than the first density, and a second carbon content greater than the first carbon content;
• pulverizing the refined coal to yield pulverized refined coal;
• conveying the pulverized refined coal in suspended condition through the feeder pipes of the coal burner to the primary combustion zone using a second quantity of air that is less than the first quantity of air required to maintain pulverized initial coal in suspended condition 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.

A method for reducing air flow required to convey pulverized coal through feeder pipes of a coal burner in suspended condition and into a primary combustion zone of the coal burner, the method comprising,

• providing a refined coal obtained by cleaning an initial coal having a dry basis ash content of at least 30% and a first density such that pulverized initial coal made from the initial coal requires a first quantity of air to maintain the pulverized initial coal in suspended condition without settling out when conveyed through the feeder pipes of the coal burner,
• the refined coal having a second dry basis ash content of less than about 20% and a second density that is lower than the first density;
• pulverizing the refined coal to yield pulverized refined coal;
• conveying the pulverized refined coal in suspended condition through the feeder pipes of the coal burner to the primary combustion zone using a second quantity of air that is less than the first quantity of air required to maintain pulverized initial coal in suspended condition 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.