In the process of plasma surface hardening, a surface layer that consists of zones of different sizes with different phase and structural composition is formed. The minimum grain size for plasma surface heating is determined by the initial austenitic grain. Its size depends on the dispersion of the initial structure. The rate of plasma heating at 200-1000 °C/s affects the size of the initial grain. The further growth of austenite crystallites with an increase of temperature essentially depends on the heating rate: small rates and high temperatures of plasma surface heating can lead to a significant enlargement of the grain. Increase of the heating temperature in the zone of thermal influence during welding from 900 to 1040 °C of rail steel 76F leads to the growth of the austenitic grain from No. 9 to No. 7 and individual grains – from No. 8 to No. 3. The largest austenite grains while heated at 1000 and 1040 °C form separate zones where conglomerates of large grains predominate. Stiffness of 76F steel, heat-strengthened on the troosto-sorbitol structure, deteriorates substantially when the temperature of rapid heating increases from 900 to 1040 °C. This also increases the instability of stiffness.
Due to new requirements of the Russian laws on the environment and energy efficiency, studies on effective methods for recovering waste heat from flue gases are crucial. Most oil and gas, metallurgy and chemical manufacturers remove high-temperature process gases. Gas cooling preceding cleaning reduces a volume of cleaned gases. For example, the most efficient dust and gas cleaning systems usually operate at a gas temperature of up to 200 °C. An increase in gas temperature can cause irreversible deformations of metal structures of the gas cleaning equipment and its premature failure. In addition, bag filters used for gas cleaning have strict limitations on gas temperature. As a part of the present project, an optimal design of staggered heat exchange elements in the form of perforated copper ribs was developed. The design documentation was developed and an experimental heat exchanger was designed. To monitor and control heat exchanger parameters, sensors were installed on the experimental heat exchanger (EHE). The algorithms of the automated system were developed. Laboratory and pilot tests proved the efficiency of the equipment designed for cooling waste process gases. The heat exchanger can be installed in gas flues of various diameters. The number of cooling units depends on technical requirements and operating and installation conditions.
The description of the complex of technical means of the automated system for controlling the technological process of thermal vortex enrichment was carried out as part of the project to create a comprehensive resource-saving technology and the organization of high-tech production of carbon and silicon dioxide nanostructures to improve the properties of building and structural materials. The description of the complex of technical means was made taking into account the justification for choosing the structure of the complex of technical means, the description of its functioning, the main decisions on the placement of technical means, the rationale for the application and technical requirements for equipment, as well as the justification of methods for protecting technical means. Computer equipment and data transmission equipment were selected. The described set of technical means is necessary and sufficient to achieve the goal of creating an automated control system for the technological process of thermal vortex enrichment, namely, to carry out continuous technological control of the equipment and process parameters of the automated process control system of the thermal vortex enrichment technological process; process safety in the production of MD1; collection of data on technological processes and equipment operation, their processing, display and documentation; optimization of the technological process through the use of advanced visualization tools, modern management algorithms and analysis of accumulated technological information; minimize the impact of human factors on the processes of collecting and processing information about the technological process; automatic prevention of the development of emergency situations.
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