incinerator, furnace for burning refuse. The older and simpler kind of incinerator was a brick-lined cell with a metal grate over a lower ash pit, with one opening in the top or side for loading and another opening in the side for removing incombustible masses called clinkers. Many small incinerators formerly found in apartment houses have now been replaced by trash compacters. The rotary-kiln incinerator used by municipalities and by large factories has a long, slightly inclined passageway through which refuse is moved continuously. In the first section the refuse is dried on moving steps, then moved onto a rocking grate where it is ignited and partially burned. The third and last section is a refractory-lined cylinder where combustion is completed. Clinkers spill out at the end. The heat from the incinerator generates steam in a boiler, producing as much as 100 megawatts of electricity. A high stack, fan, or steam jet supplied from the boiler supplies a draft. Ash drops through the grate, but many particles are carried along with the hot gases. These particles and volatile gases are burned in a combustion chamber fed by several furnaces. In order to control air pollution, the remaining gases are further treated, with acid gas scrubbers to control sulfuric and nitric acid emissions, and baghouses to remove all remaining dust particles, before they are released into the environment.