BOILER UNIT Russian patent published in 1994 - IPC

FIELD: preparation and burning of polyfraction high-moisture solid fuel at thermal power stations and in industrial boiler houses. SUBSTANCE: wet polyfraction fuel (coal, peat) is fed from bunker 13 to lower portion of vertical drying column 16 by means of feeder 14 through chute 15. High-temperature inert gases (drying agent) drawn from furnace 2 through gas intake ports 23 are fed towards fuel being supplied via gas duct 21 by rarefaction created by mill 18. At minimum sections 19 and 20 of column 16 and gas duct 21, the polyfraction fuel is divided by fractions at maximum speed of drying agent according to free-fall velocities of its particles. Its main part consisting of small and average fractions falls off and is subjected to short-duration drying in the separation zone in soft mode with the aid of drying agent partially cooled in gas duct 21, after which it is accelerated and is carried to drying column 16 where it is additionally dried at speed reduced by height of ascending flow of the drying agent and is crushed at multiple reciprocating of fuel particles in the course of flash drying. Particles of fuel which lost their mass whose the free-fall velocity becomes lesser than minimum velocity of drying agent in the upper (larger) section 17 of column 16 flow to mill 18 through suction branch pipe; in mill 18, they are finally crushed and then dust thus prepared is carried by the drying agent via dust line 26 to vortex pulverized coal burner 7 to which hot air is fed from air duct 39. Prepared dust from the second individual dust preparation system which is identical to the first one is also fed to second burner 7 of the same pair. EFFECT: enhanced reliability. 3 cl, 6 dwg