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自本世纪二十年代起,大火力发电厂纷纷由烧煤块改烧煤粉,就是把块煤磨成细粉,再喷入锅炉进行燃烧,这样就比烧块煤的旧式锅炉燃烧完全,热效率也得到了很大的提高。煤粉一进锅炉的炉膛,立即被卷入旋风般的空气湍流之中,化作熊熊烈火,温度高达1300～1700℃。燃烧之后,煤粉中的碳份和可燃部分都烧掉了,所剩下的灰粒随着炽热的气流,自烟道排入天空或被收尘装置收集下来。这些灰粒就是粉煤灰。煤粉燃烧时,要发生一系列的物理化学变化,生成含有硅、铝、铁等金属氧化物的
Since the 1920s, large coal-fired power plants have switched from coal-burning blocks to coal-fired pulverized coal, that is, to pulverize lump coal into fine powder and then spray it into boilers for combustion. This burns the older boilers that burn lump coal. Thermal efficiency has also been greatly improved. When the pulverized coal enters the hearth of the boiler, it is immediately entrained in the turbulent air turbulence and turned into a raging fire with temperatures as high as 1,300 to 1,700°C. After combustion, the carbon and combustible parts of the pulverized coal are burned, and the remaining ash particles are discharged from the flue to the sky or collected by the dust collecting device along with the hot airflow. These soot particles are fly ash. When pulverized coal is burned, a series of physical and chemical changes take place to produce metal oxides containing silicon, aluminum, and iron.