Chernyavskyy M. Scientific and technical bases and methods of increasing the efficiency of energy use of solid fuels

In the dissertation the important scientific and applied problem of development of scientific bases and introduction of ways of increase of solid fuels power use efficiency is solved. The processes of pyrolysis, gasification, combustion, physic-chemical properties of thermal coal, the technical solutions for improving the safety and efficiency of solid fuels use and the results of their apply at power plants are considered. The main regularities of pyrolysis of coal particles under rapid heating in the pressure range of 0.1-2.5 MPa are found. The effective kinetic characteristics of gas evolution depending on particle size and heating conditions are determined, the method for calculating the dynamics of pyrolysis under rapid heating is developed. For the first time it is found that during rapid pyrolysis in the environment of own products the gas release rate is limited by the equilibrium partial pressures of the products. The dependence of carbon reactivity on its state in coal (free, in carbon-mineral aggregates, in graphitized inclusions) is found, the influence of ash content on the com-bustion rate and on the carbon burnout is determined. Methods for calculating the com-bustion rate of particles in the transition mode of reaction are developed. It is proved that in conditions of pulverized coal flame bituminous coal burns closer to the external diffusion mode with weak degree dependence, and anthracite - to the internal-diffusion mode with strong exponential dependence on temperature. It is found that when burn-ing anthracite with bituminous coal mixture, the decrease in the burning rate of anth-racite by reducing the concentration of oxygen spent on bituminous coal burning is compensated by flame temperature increasing due to bituminous coal volatiles burning. The established characteristics of gas evolution during rapid pyrolysis of coal at high-temperature thermal shock, of dynamics of conversion of coal of various ranges in the fluidized bed are used in the design of combined cycle power plants with intra-cycle gasification in CFB and entrained flow under pressure, of pulverized anthracite burner with thermo-chemical dust preparation, of CFB-boilers of steam productivity of 10, 50 and 75 t/h. Technological schemes are developed and initial data are issued for the design of the spouting bed pre-combustor-igniter for pulverized coal boilers, of the vortex pre-furnace on brown coal for boilers of low and medium capacity. Basing on the found effect of schlamm agglomeration, the operation of schlamm dryer of the 215 MW CFB unit of Starobeshivska TPP was optimized. The solutions on fuel preparation and combustion regimes were introduced, which brought the unit to design indicators for schlamm content in fuel and combustion efficiency. In conditions of termination of Donetsk anthracite deliveries, fuels with non-design characteristics and fuel mixtures were used at 7 power plants. 4 anthracite boilers at 2 TPPs were converted to bituminous coal. This allowed to replace 10 mln tons of anthracite by domestic bituminous coal and imported fuels, to save 430 mln m3 of gas, to increase efficiency and to improve the environmental performance of boilers.