Application of Condensing Heat Utilizers at Heat-Power Engineering Objects (Review)

Abstract

Increasing the efficiency of fuel use in the production of electricity and heat can be achieved by carrying out activities aimed at modernizing existing power plants. Such highly effective measures include equipping boilers with a condensing heat utilizer (CHU) that allows the use of low-potential heat of outgoing flue gases. When the flue gases are cooled in CHU below the dew point temperature of the water vapor contained therein, up to 12–15% of the heat recovery can be obtained, which can be used to heat the return-network water in the heat network. It is most effective to use CHU in boilers burning natural gas and biofuel whose combustion products contain a large amount of water vapor. The temperature of the return-network water has a great influence on the efficiency of the CHU use. Three characteristic ranges of utilization efficiency of low-potential heat, which depends on the temperature of the reverse network water, are selected. Various solutions are given that allow ensuring a high degree of utilization in CHU of the heat released during condensation of water vapor contained in the combustion products at the temperature of the reverse-network water close to the dew-point temperature. Examples of the successful application of CHU of various brands at power plants in the Nordic countries, namely Sweden, Denmark, Latvia, and Estonia, that have similar climatic conditions with Russia and similar district heating systems are considered. CHU with preheating and humidification of air supplied to the boiler for combustion, which will not only effectively utilize low-potential heat but also significantly reduce emissions of nitrogen oxides into the atmosphere, are also considered.