Coal Combustion: Plasma-Assisted
ByV.E. Messerle, A.B. Ustimenko
Pages 15

This entry presents modern plasma technology for solid fuel ignition and combustion. It promotes more effective and environmentally friendly low-rank coal incineration. To implement this technology at coal-fired thermal power plants, plasma–fuel systems (PFSs) were developed. PFS is a pulverized coal burner equipped with an arc plasma torch producing a high-temperature air stream of 4000–6000°C. The basic technology used in PFS is plasma thermochemical preparation of coal for burning. It consists of plasma heating of an air–coal mixture up to temperature with coal volatiles being released and char–carbon partial gasification. In PFS, the air–coal mixture is deficient in oxygen; therefore, carbon is oxidized mainly to carbon monoxide. As a result, at the PFS exit, a highly reactive mixture is formed of combustible gases and partially burned char particles, together with products of combustion, while the temperature of the mixture is around 1050°C. Further mixing with air promotes intensive ignition and combustion of the prepared fuel. PFSs have been tested for boiler start-ups and pulverized coal flame stabilization at 30 power boilers of 75 to 950 t/h steam productivity. The boilers were equipped with different types of pulverized coal burners: direct flow, muffle, and swirl burners. In tests of the PFS, power coals of all ranks (lignite, bituminous, anthracite, and their mixtures) were incinerated. Their volatile content was in range of 4–50%, ash varied from 15% to 48%, and heat of combustion was from 6690 to 25,100 kJ/kg.