| 摘要 |
PURPOSE:To enable energy saving, polution prevention and combustion safety irrespective of any load change and any apparatus state by setting the excess air limit of an optimum combustion zone in the multi-fuel combustion in accordance with the content of load change and the response speed of the fuel and air, and limiting the excess air ratio to a range between the excess air ratio and the excess air limit. CONSTITUTION:The upper and lower limits of the air flow quantity and total theoretical air quantity obtained from respective fuel flow quanties thereby to control the excess air ratio. When the boiler is subjected to multi-fuel combustion by the air flow quantity and the fuel flow quantity limited by the upper and lower limit values set by taking consideration of the smoke emitting limit and excess air limit corresponding to the load variation in an supply quantity control system 30 and a fuel supply control system 40, the excess air ratio mua within the boiler is constantly limited within an optimum combustion zone between the smoke emitting limit and the excess air limit. In a transient state, when the load abruptly varies, the excess air ratio mua varies in accordance therewith but returns again to a steady-state condition after a short period of time. The excess air ratio mua is limited within predetermined upper and lower ranges of the predetermined excess air ratio mu. |
