Galyanchuk I. Modeling of convective heat-transfer systems of steam boilers of thermal power plants

The thesis is dedicated to the questions of increase of the efficiency of operation of convective heat-transferring systems of steam boilers of thermal power plants in the modes from minimum to maximum load, which leads to energy conservation during generation of thermal and electric energy. On the basis of the review of literary sources, it is established that the existing methodical apparatus of calculations of several interrelated convective heat-exchanging units of steam boilers, which are a complex thermal energy system, does not meet new requirements, conditions and possibilities of investigations of their operation modes. As a result of performed work, methodical foundations for building models of heat-transferring systems of interrelated heat-exchangers are elaborated, with the use of generalized non-dimensional object parameters, outgoing and incoming temperatures of coolants. Methodology of mode calculations is perfected, which allows determining the consequences of introduced mode and objective changes in the heat-transferring system of several heat-exchanging units, interrelated with a heating coolant. This gives a possibility to forecast the impact of change of incoming temperatures of coolants on change of their outgoing temperatures, to detect possible improvements of heat-transferring systems, as well as to analyze the operation of heat-exchanging units. For steam boilers TPP-312, TPP-210А, TP-100, TP-92, TP-10, models of convective heating surfaces are worked out, which reflect the main physical phenomena of heat transmission in them. Mutual impact of the parameters and components of the mechanism of heat-exchange on the process of heat-transfer from the heating to heated coolants is studied. The elaborated models allow forecasting the influence of change of incoming temperatures of coolants on change of their outgoing temperatures, as well as analyzing operation of heat-exchanging units in modes from minimum to maximum load. For the above-mentioned models of heat-transferring systems of convective heating surfaces of steam boilers, dependences are deduced, and numeral values of mode coefficients KiN for the nominal operation mode with outgoing values of their object parameters are determined. On the basis of analysis of the adjustment processes of the steam temperature of intermediate overheating and modeling injection devices, we have suggested and received patents for new ways of adjustment of the steam temperature of intermediate overheating in the start-up modes of operation of steam boilers and power generating units of thermal power plants.