| 摘要 |
PURPOSE:To reduce NOx, decrease an air ratio in response to an increased temperature when a load is increased and to improve a combustion efficiency by a method wherein the air ratio is increased in response to a reduction in temperature when the load is decreased. CONSTITUTION:An air ratio in a furnace 3 and a concentration of NOx contained in a discharged gas are varied in response to a temperature within the furnace 1. As the temperature is decreased, the air ratio is required to increase. Temperature and air ratio setting means may calculate an output having this characteristic and its output is inputted to a low level selector together with an output from the load air ratio setting means. The selector circuit operates the low level selector when an amount of reduction of the load becomes more than a predetermined value. The low level selector may calculate a signal expressing an air ratio corresponding to a load from the load air ratio setting means and another signal expressing an air ratio from a temperature air ratio setting means, i.e., a signal having a low air ratio to an output circuit. In this way, under a transmitted state for reducing the load, a reduction of the concentration of NOx can be performed as much as possible. |
