a cyclone furnace in which the gas-air stream carrying particles of fuel and slag describes a spiral motion. Vortex furnaces are used as precombustion chambers for chamber furnaces in steam power plants and as industrial furnaces—for example, in the calcination of copper ores. In vortex furnaces the particles of fuel are maintained in a suspended state because of the lifting force of a powerful vortex, so that even coarser particles (5-10 mm and larger) do not settle. In modern vortex furnaces, in which the speed of the incoming air stream is 30-150 m/sec, lumps of solid fuel 2-100 mm in size are burned.
Both horizontal and vertical cyclone precombustion chambers exist; the latter are used much less frequently. The diameter D of horizontal cyclone precombustion chambers is 1.2-4.0 m, and the relative length L/D does not exceed 1.5-1.6. Furnaces of this type are widely used outside the USSR (in the USA, the Federal Republic of Germany, and Czechoslovakia) but are much less frequent in the USSR. Vortex furnaces are characterized by high thermal stress in the cross section of the furnace chamber—42-63 gigajoules per sq m · hr [GJ/(m2 · hr)], or (10-15) × 106 kilocalories per sq m · hr [kcal/(m2-hr)]—and in the volume of the chamber [8.5-21.0 GJ/(m3 · hr), or (2-5) × 106kcal/(m3 · hr)] and by slag recovery, of up to 90 percent. In a chamber furnace the thermal stress of the volume is 10-20 times less, and the degree of slag recovery does not exceed 80 percent. One large vortex furnace is capable of matching the evaporating capacity of boilers only up to 150-180 tons per hour, so that as many as 12-14 horizontal cyclone precombustion chambers are in-stalled with high-capacity boilers.
S. S. FILIMONOV