INCREASING THE EFFICIENCY OF FUEL-FIRED PLANTS WITH DUSTY WASTE GASES

Abstract

The results of a set of thermal calculations of the air-heating heat exchanger of the dusty waste gases of the thermal disposal of household waste are given. The initial data for the calculations were taken in the practical range when incinerating 1t/h of household waste from the experience of using the specified installations. The heat-recovery unit is designed to heat air for combustion by recovering the heat of the exhaust gases leaving after the turbine of this installation. Its design solution is characterized by the possibility of cleaning work surfaces from deposits of technological dust. The thermal indicators (temperatures of coolants and heat productivity) of the proposed heat-recovery unit under the conditions of its use for waste incineration plants were investigated. Calculations were performed in different modes of operation of the heat-recovery unit during the year, namely: at inlet temperatures of air and exhaust gases in the range from -20 to +20 ºС and from 200 to 300 ºС, respectively, the coefficient of excess air in waste gases from 1.5 to 2, 5 and different levels of dust on the heating surface. The influence of dustiness on the thermal parameters was characterized by the coefficient k, which determined the level of reduction in the thermal efficiency of the heat exchanger as a result of dust deposits on the specified surface and varied in the range from 1 to 0.5. Under the considered conditions was established, that use of the proposed air heater it provides heat output of 72 ÷ 263 kW, cooling of flue gases to a temperature of 107 ÷ 245 °С and heating of air to 96 ÷ 220 °С. At such levels of flue gas cooling, the efficiency of the thermal disposal of household waste increases by 2 ÷ 5%. In the case of a decrease in the heat-recovery capacity of the heat-recovery unit to technologically unacceptable levels, it is necessary to carry out its forced cleaning with compressed air, as provided for in the technical solution of such an air heater.