Novakivsky M. Complex heat- utilization systems for low and middle power boilers with increased moisture content of waste gases

The thesis is devoted to the thermophysical justification of complex systems for heat utilization of the exhaust gases of gas consuming boilers of municipal heat power engineering with increased moisture content of these gases. A battery of studies of heat and moisture regimes and thermal effectiveness of heat utilization systems designed to heating of input boiler water and cold water for chemical water treatment, as well as systems with heating of boiler water and air for combustion were carried out. The results of studies to determine the effects of the level of moisture content of the flue gases of the boiler on the main heat engineering characteristics of these heat utilization systems are given. The data of comparison of efficiency indicators and characteristics of the heat and moisture state of these systems are presented. The advantages of heat utilization technologies with heating of boiler water and blown air over the technology for heating boiler water and water for chemical water treatment are discussed with respect to its thermal efficiency. For heat utilization systems with heating of boiler water and air for combustion, the dependences on the moisture content of the flue gases of the boiler for such generalized characteristics of this system as the annual generation of heat energy, the average annual increase in the efficiency of the boiler, the optimum ratio of the areas of water and air heaters, and other, are studied. For different types of boilers and their operation modes, studies of the thermophysical aspects of the new proposed complex heat utilization system with preheating and humidification of air for combustion and heating of cold water for chemical water treatment are performed. The data of the comparative analysis of the main characteristics of this system and the corresponding system without water heating for the chemical water treatment are given. The issues of protection of gas removal ducts of boiler plants with the proposed heat utilization systems are considered at increased moisture content of flue gases. It is shown that when using these systems, the coefficient of utilization of the heat of the boiler fuel is increased: by 5.8 - 11.1% for systems with heating of the input boiler water and water for chemical water treatment; on 8,9 - 11,4% for systems with heating of boiler water and air for combustion; by 11.3 - 17.8% for systems with heating and humidifying air for combustion and heating water for chemical water treatment. The payback period for the cost of implementing the developed systems in municipal boiler houses varies within 1.0 - 2.5 years, depending on the type of equipment used, its operating modes, etc.