METHOD OF PROCESSING SOLID FUEL Russian patent published in 1997 - IPC

FIELD: heat-power engineering and environmental protection. SUBSTANCE: invention relates to preventing pollution of effluent gases by nitrogen oxides and reducing carbon dioxide content in them when burning solid fuels in combustion chambers of boilers at heat and power stations, industrial and district heating plants. Method consists in four-step processing of solid fuel. First, feeding blowing gas with minimum oxygen content (α = 0.05-0.15) in conjunction with heating fuel-gas mixture to 600- 650 C ensure reaction of amines, predominantly NH, NH₂, and NH₃ with each other to form elementary nitrogen and its simultaneous oxidation into oxide and dioxide as intermediates which successively react with hydrocarbon pyrolysis products to form elementary nitrogen. In the second step, burning of coke residue is conducted under oxygen deficiency conditions (α = 0.85-0.90) at minimum CO₂ yield and temperature as high as 800 C providing conversion of CN and HCN into elementary nitrogen through formation of nitrogen oxides and passage over two kinetic barriers with participation of free radicals. In the third step, effluent gases are cooled to temperature below 140 C and ozone is fed to provide conversion of residual oxides into nitrogen dioxide and tetroxide and fast reaction with supplied water to yield nitric acid or with alkali solution to yield nitrates. Finally, pure high-energy gas is burned at temperature not higher than 800 C to exclude probability of arising secondary nitrogen oxides or is used to produce methanol. Using oxygen mixed with steam when conducting burning under pressure provides essentially complete purification of effluent gases to safe purity degree and decrease of burning chamber dimensions. EFFECT: enhanced efficiency of process. 3 cl