Abstract

A furnace is a device (enclosure) for generating controlled heat with the objective of performing work. In fossil-fuel furnaces, the work application may be direct (eg, rotary kilns) or indirect (eg, plants for electric power generation). The furnace chamber is either cooled (waterwall enclosure) or not cooled (refractory lining). Furnaces related to metallurgy such as blast furnaces are excluded. Fuel-fired furnaces primarily utilize carbonaceous or hydrocarbon fuels. Since the purpose of a furnace is to generate heat for some useful application, flame temperature and heat transfer are important aspects of furnace design. Industrial furnaces are an order of magnitude smaller than power-plant furnaces since the applications are usually on an individual basis rather than feeding power to a regional electric grid. Like the power-plant furnace, the function of the industrial furnace usually is to generate steam, generally for a chemical process, mechanical power, or heating application, rather than electric power generation. New furnace concepts in evolutionary stages include fluidized-bed furnaces, coal gasification furnaces, and MHD furnaces. Fluidized-bed combustion has reached commercial-scale operations.