Waste-Heat Boiler

a boiler without its own firebox, which uses the heat of waste gases from industrial or power equipment. The temperature of gases entering a waste-heat boiler is 350°-400°C (in the case of a boiler installed behind an internal-combustion engine) to 900°−1500°C (if it is installed behind a reverberatory or refining furnace or a cement kiln). Large waste-heat boilers are equipped with all components of a boiler unit, with the exception of the firebox and other equipment associated with fuel combustion. For low outputs and pressures, waste-heat boilers with gas tubes are used; they may have multiple forced circulation or, less frequently, natural circulation and a direct-flow separator or drum design. Waste-heat boilers for heating water are usually called utilization economizers or pre-heaters. In some cases waste-heat boilers are integrated with other components of technical equipment to such a degree that they are no longer a separate unit (for example, evaporative cooling equipment for open-hearth furnaces and chemical installations). Waste-heat boilers are widely used in the chemical, petroleum, food, and textile industries.