FIELD: boilers working on natural gas or oils. SUBSTANCE: air preheater is made in form of U-shaped unit with evaporating stage 3 mounted in its left-hand leg in way of motion of waste gases: mounted above evaporating stage 3 are upper nozzle 5 and pipe lines 6 and 7 for continuous and periodic blow; water-to-air heat exchanger 1 located in lower portion is placed in volume of condensate receiver 14 provided with cleaning pipe line 16. It connects evaporating stage 3 with lower nozzle 13 mounted in right-hand leg and condensation stage 11. Fan 4 with water evaporation and sprinkling pipe lines 12 and 2 is mounted at inlet of condensation stage 11 in air end. It is also connected to water-to-air heat exchanger 1 and evaporating stage 3. EFFECT: intensification of heat exchanger process; avoidance of low-temperature corrosion effect. 1 dwg
