已知锅炉燃烧产物飞灰可燃物<img src="/Image1/36/3636bcebe96b0ccf3572f5ee2e615984.jpg" />，燃煤收到基灰分<img src="/Image1/d8/d8f5a98647058294f45249afc3a4db4f.jpg" />，燃煤低位发热量<img src="/Image1/d4/d453bda2a3d637a590fe5db230d6a321.jpg" />，飞灰占燃总灰分的份额<img src="/Image1/d2/d2985234452e985b081b929589d73cfe.jpg" />（锅炉效率每下降1%，煤耗增加3.5g/kWh）。求飞灰可燃物对煤耗的影响。