The mechanism and kinetics of the target components extraction from mineral raw materials (sulfur from sulfur ore by tetrachlorethylene, Al 2 O 3 from bauxite specs by NaOH, copper from ore and malachite by hydrochloric acid), as well as vegetable oils (from amaranth, amaranth hybrid and сamelina by organic solvents) have been studied. Experimental studies to confirm the diffusive nature of the target components extraction from mineral sources have been conducted. Diffusion coefficients for mineral samples have been obtained. It has been established that the target component extraction from the plant raw material occurs by the internal diffusion transfer of the component to the surface of the phase contact and the external diffusion from the surface to the liquid volume. Kinetic and diffusion coefficients for the samples of vegetable raw materials were determined.
The plain problem of drying of a cylindrical timber beam in average statement is considered. The thermal diffusivity coefficients are expressed in terms of the porosity of the timber, the density of the components of vapour, air, and timber skeleton. The problem of mutual phase distribution during drying of timber has been solved using the energy balance equation. The indicators of the drying process of the material depend on the correct choice and observance of the parameters of the drying medium.
Heating the air in the boiler air heater with the heat of fuel combustion products performs the functions of increasing the fuel combustion temperature, increasing the temperature level of gases in convective heating surfaces, improving ignition and fuel combustion conditions, increasing boiler efficiency by utilizing waste gas heat, improving fuel quality due to its preliminary supply, etc. However, the peculiarities of the process of heating the air in the air heaters do not allow to achieve a decrease in the temperature of the exhaust gases. This is due to the unfavorable ratio of heat capacities of flue gases and air, as well as corrosion and contamination of the heating surfaces of air heaters. The research of heat transfer processes and hydraulic resistance of unified package of cold layer of RAH is depicted at this work. The graphic dependence of the change in the coefficient of hydraulic resistance and Nu number for unified packages with single line of sheets and simplified profile with corrosion resistance enamel from the Reynolds number for different values of the length of the replaced areas was constructed. The unified packing of the simplified profile has increased by 1.17 times equivalent diameter and is characterized by good operational parameters and takes into account the risk of contamination of heating surfaces due to the enamel coating.
Thermal power stations play the main role not only in carrying the base load, but also in ensuring the coverage of peak and semi-peak loads of electricity consumption. Improving the operational maintenance of energy equipment gives a greater economic effect, since the costs of modernization of regenerative air heaters, which improve their density and thermal efficiency, are repaid in a short time. The efficiency and cost-effectiveness of the operation of regenerative air heaters was increased by the reconstruction of the heating installation. The results of the reconstruction of the design heaters of the TГМП-314 boilers with sections of sanitary-technical heaters КФСО -II and КФБО -II with replacement by sections of energy heaters (СО-110) are presented. The improved heating installation is installed in front of each regenerative air heater of the ТГМП-314 boiler and is made of two walls placed sequentially according to the air movement, in each of which 12 sections of reconstructed CO-110 heaters with a downward movement of the heating steam flow are installed. An important advantage of the proposed sequential installation of radiators is an increase in the uniformity of the temperature field in the box in front of the regenerative air heater due to two-stage air heating. Sequential installation of radiator walls increases the heat transfer coefficient approximately 1.6 times compared to parallel connection, which makes it possible to double the air speed in the radiators for the same number of sections. The possibility of formation of stagnant zones of sections of CO-110 heaters is excluded. In this case, it is recommended to reconstruct single-pass radiators with the installation of a pipe board and heating steam condensate removal chambers. The high efficiency of the improved heating installation made it possible to carry out all boiler ignitions with the possibility of supplying flue gases immediately through the RAH.
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