WATER-TUBE BOILER Russian patent published in 1998 - IPC

FIELD: boilers working on solid fuels. SUBSTANCE: boiler has upper (1) and lower drums communicated by means of uptake and downtake tubes of convective bank. Furnace 5 adjoining the tube bank is bounded by tubular shields connected to respective headers which are connected in their turn with drums. Boiler is additionally provided with settling afterburner chamber 23 formed in way of motion of gases by gastight rear shield of furnace from -shaped tubes whose convex side is directed towards gas flow and rear wall of boiler. Upper inclined section of -shaped tubes is made in two levels. Some tubes adjoining convective bank are located below level of upper inclined section of tubes adjoining side shield forming transversal passage 22 for flue gases flowing from furnace 5 to settling afterburner chamber 23 where ejectors are mounted for return of fly ash to furnace 5. EFFECT: intensification of heat exchange; improved after-combustion of fuel due to reburning of fly ash; reduction of ash erosion. 3 dwg