| 摘要 |
PURPOSE:To reduce cost for power in a plant, by a method wherein draft is increased only when a kind of coal, whose combustion gas contains NOX of high concentration, is used and the draft is reduced in other cases, when various kinds of coal, provided with different natures, are burnt. CONSTITUTION:An airflow damper 14 for two-step combustion is closed and a burner air resister is opened by 50-60% from starting to 20% load while the damper 14 is opened by a NOX setter 25 upon throwing coal into a furnace. When the fuel ratio and nitrogen content of the coal are high and the NOX/ unburnt constituent thereof is large, the opening degree of a resister 30 is coped with the set value of NOX by bypassing by the damper 14 while chocking control is effected so as to reduce the unburnt constituents. When the fuel ratio and nitrogen content are low, the opening degree of the resister 30 is increased to reduce a draft and a burner is operated with the small opening degree of the damper 14. The generation of NOX is increased when a furnace temperature is increased upon increasing the load of the burner, therefore, oxygen is reduced by the burner and the opening degree of the damper 30 is increased to suppress the unburnt constituents by the supply of air. The setter 25 corrects the damper 14 through a bias device 31 for two-step combustion and an adder 32. |
