Heat-recovery technology of exhaust gases with high moisture content for gas-fired boilers of municipal heat-energy

Abstract

To improve the operational and environmental performance of steam and water-heating gas-fired boilers, is proposed the efficient technology based on a complex heat-recovery system with heating and humidifying the blown air and heating the cold water of the chemical water-purification system. In terms of the implementation of this technology, the heat-recovery system uses the utilized heat simultaneously for different needs of the boiler plant, this allows the condensation mode of operation of the heat-recovery equipment during the entire heating period. The aim of the work is to study the thermophysical aspects of the creation and operating efficiency of the proposed complex heat-recovery system, provided that the exhaust-gases of the boilers are of high moisture content. Researches of the heat and humidity characteristics of exhaust-gases hath carried out and the increase of the coefficient the use heat of fuel of boiler with the use of this complex heat-recovery system with heating and humidifying the blown air and heating (or without it) of cold water of the chemical water-purification system for various types of boilers (steam and water-heating) and the corresponding modes of their operation. The made comparative analysis of these systems, namely, the comparison data of such characteristics of heat-recovery systems as: their heat capacity Q, the increase of coefficient the use heat of fuel of boiler Δη caused by their use, the heating and humidifying parameters of the blown air and exhaust-gases after the heat-recovery installation. It is shown that for the proposed heat-recovery system in comparison with the corresponding system without the heating of cold water of chemical water-purification system, increases by 1.3 ÷ 1.6 times the general heating capacity of the system and up to 6.6 % rises coefficient the use heat of fuel of boiler. Also, the humidity content of the exhaust-gases is much reduced after the heat-recovery system, and consequently lowered the heat loss with the exhaust-gases.