FIELD: boiler engineering where natural gas and liquid fuel are used. SUBSTANCE: water-to-air heat recovery unit has evaporation stage 3 above which upper nozzle 7 and water pipe lines 8 and 10 are mounted and condensation stage 18 at whose inlet fan 15 with water evaporation and injection pipe lines 16 and 4 is mounted. It also connected to inlet of evaporation stage 3. They are connected in way of motion of waste to LH and RH branches of U-shaped package of heat recovery unit which are connected through condensate receiver 21; besides that, they contain tubes finned by common fins forming alternating passages for flow of air and combustion products. Outer passages are used for transportation of air. Finned tubes of both branches are interconnected by means of water-to-water heat exchanger 1. Construction provides for simultaneous heating of water and air, thus ensuring stable cooling of waste gases irrespective of fluctuations in flow rate of water. EFFECT: enhanced efficiency. 2 dwg
