Search

The work analytically investigates a new recuperative-transformer system with subcooling of the recirculation flow of furnace cooling, which increases the heat-technological and energy efficiency of furnace units, expanding the technical and economic efficiency of industrial heat supply. The basis of the research is the conclusion that the application of heat pump technologies for energy saving in the production of building materials in rotating furnaces with the utilization of low-temperature gas-air flows is very promising. It is noted that the stabilization of the thermal mode of furnace cooling during the year is an important technical and economic task aimed at improving the thermal process and energy saving, primarily for the firing zone. An analytical study of the recuperative transformer system with subcooling of the recirculation flow was conducted. The equation of the heat balance of the heat extraction system of the gas-air circuit in the process of furnace cooling is presented. The transfer of heat absorbed from the surface of the furnace in recuperative heat exchangers, as well as in the evaporator of the thermotransformer circuit of the vapor compression heat pump is described. A generalized dependence was obtained for the heat flow of furnace cooling and a low-potential source in the gas-air circulation circuit of the heat supply system. The dependence for the real conversion factor is determined. A graphical interpretation of the dependence of the effective conversion factor on the ratio of the consumption of the heating medium and the heated medium is presented. It is emphasized that the results of the study of the rational interrelationship of the initial and mode parameters create a basis for the engineering development of the proposed heat supply systems based on the stabilizing cooling of the rotating furnace. [ABSTRACT FROM AUTHOR]

In Ukraine, the design life of the most NPP units has expired. In this regard, it is proposed to extend the life of the NPP by combining it with a gas turbine plant (GTP), namely, the use of a waste heat boiler (WHB) on exhaust gases to produce 20% of the nominal steam consumption. The power of the reactor unit is reduced to 80%, which makes it possible to increase the life time of the reactor by reducing the rate of accumulation of fluence, and the steam turbine will operate at nominal mode. In addition, the gas turbine can be used as a backup power source for the reactor unit. In the schemes of combining steam turbine units (STU) of NPPs with GTP presented in the literature, options for increasing the power of the steam turbine are considered. From the analysis it follows that this always leads to a non-design mode, which is characterized by a decrease in the efficiency of the stages and the turbine as a whole. In the proposed scheme, the STU operates in nominal mode with the design resource and efficiency. The method of calculation of the proposed scheme of combining GTP with NPP is considered in the work and the optimization of the basic parameters (gas compression ratio, temperature of the gas in the WHB, temperature difference in the WHB) in relation to the maximum of the electric efficiency of the GTP and the nuclear power complex (NPK) (ηGTP = 40,79%; ηNPK = 41,19%) is carried out. The scheme with intermediate overheating of the gas in the WHB. As a result, it was determined that the intermediate overheating of the gas allows to increase the efficiency of the gas turbine to 45,44 % (T0 = 1350 ºC, compression ratio 25 and gas temperature at the outlet of the WHB 903 K). The efficiency of the NPK ηNPK = 42,9 %. This mode of operation for 20 years makes it possible to extend the life time of the NPP for 5 years, which is enough for the construction of a new unit. In the autonomous mode, at WHB bypass and air heating in the regenerative heater, ηGTP = 50,87 %. [ABSTRACT FROM AUTHOR]

Purpose. The solid waste management system in Ukraine consists from the land disposal of waste. In this case, there is no control over environmental pollution, which in turn leads to environmental risks. A considerable amount of solid waste is formed at the railway transport enterprises. The solution of the problem of the elimination of wastes generated at large railway stations and in the process of servicing trains, namely directly at the place of their formation, is considered in this work. Methodology. The authors propose to use mobile waste processing plants, which eliminate the negative impact of the process of accumulation of solid industrial and municipal waste on the human habitat; while they can serve a certain number of waste producers. The study was conducted on a waste processing plant (WPP-300) located in Kharkiv on the Southern Railway. Findings. The design and purpose of the main units of waste processing plant are described. The bottom ash after incineration of solid waste accounts for 5-10 % of the initial volume of waste and corresponds to the safe IVth class of the waste classification catalog. Multi-stage thermal catalytic cleaning of waste gases provides concentration of harmful substances, including dioxin group within the limits of permissible norms. For complete combustion of all components of the waste, the temperature in the furnace was 850-900 ºC, the presence of flue gases in the afterburner at 1100-1200 ºC for at least two seconds, the defined excess air 1.4. Originality. The authors for the first time conducted a study of the parameters of incineration of various elemental wastes. We calculated the total theoretical volume of combustion products on a mobile waste-processing complex. Practical value. The use of a mobile incineration plant allows solving the problem of solid domestic waste disposal. As shown by the practice of its operation, such measures are justified and are not only economically viable, but also environmentally friendly. The results of the work allow estimating the amount of waste gases at various morphological compositions of the waste of the railway transport.

In view of the tightening of the requirements of the International Convention for the Prevention of Pollution from Ships, in particular, the Regulation on the Prevention of Air Pollution from Ships, it becomes urgent to introduce new methods for monitoring and limiting the concentration of harmful emissions from ship units into the atmosphere. The NOx content in the exhaust gases can be achieved by influencing the maximum combustion temperature provided by the introduction of recirculation gases. Flue gases with a temperature of 300-400 ° C are selected in front of the air heater and recirculation smoke extractors and fed into the furnace. As a result, the maximum temperature in the furnace is reduced by 120-130 ° C and the oxygen concentration in the combustion zone decreases, which also reduces the formation of fuel NOx. The efficiency of the steam boiler is reduced relatively little (0.01-0.03% per 1% of recirculation gases). The efficiency of suppression of the formation of nitrogen oxides during the introduction of recirculation gases is determined by the following factors: the place of selection of gases for recirculation; the conditions of their introduction into the furnace; the degree of recycling r,%; distribution of recirculation gases by the volume of the combustion chamber; boiler condition. The study of methods for reducing the concentration of NOx in the exhaust gases of ship steam boilers. The modern scientific approaches in the field of reducing harmful emissions are considered, in particular, their advantages and disadvantages are indicated. A method is proposed that implements a neural network algorithm in a flue gas recirculation control system, which is characterized by the ability to minimize the content of NOx values when a ship's boiler is operating at different thermal loads. Comparative modeling of the proposed neural network ACS and traditional ACS of the flue gas recirculation process when a ship's boiler is operating at 50% load has shown the advantage of a neural network control system trained to achieve the lowest possible content of harmful emissions in the atmosphere. [ABSTRACT FROM AUTHOR]

The energy efficiency of marine internal combustion engines depends substantially on the efficiency of the exhaust gas heat recovery systems, as their thermal potentials account for more than half of the heat flow generated by the combustion of the fuel. One of the effective methods of utilizing the heat of the exhaust gases is gas turbine inflating systems, which allows to increase the effective efficiency and to significantly increase the power of the internal combustion engines without any additional increase in their dimensions. In thermodynamic analysis of thermomechanical systems, the most appropriate method is the function (exergy), which, compared to the traditional method of cycles, is simpler and more versatile, since it does not require the identification and analysis of auxiliary models of comparison. The use of the exergy method in thermodynamic analysis of gas turbine inflator systems allows to consider not only quantitative indicators in energy transformations in processes, but also to determine qualitative characteristics of energy flows. The paper presents a methodology for the calculation of energy and exergy flows in a gas turbine blast system based on a turbine unit with a gas turbine and a centrifugal compressor, which are most commonly used in internal combustion engines. The calculations of the exergy indices of the output gas flow of the internal combustion ship engine with the gas turbine inflator system and the diagram of exergy streams based on them allow us to determine the processes with the highest irreversibility (the level of degradation of energy), both in absolute and relative terms. This approach allows us to recommend priority measures to optimize the processes of energy conversion in internal combustion engines in order to improve their overall technical and economic efficiency. [ABSTRACT FROM AUTHOR]

Copyright of Science-Based Technologies is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of research is to lay the theoretical foundation and specify the control model of bath dynamics along the blowdown. The research is conducted on converters of 160 tons. Specifically, we study the control dynamics of decarbonization and changes of bath temperature. We use deterministic and statistical methods to process the research results. We obtain the estimates of carbon content and temperature of bath converter depending on the accuracy of priori (intensity purging, distance lance to the level of metal, etc.) and posteriori information (analysis of exhaust gases from the converter, heat flows into the tuyere cooler and converter gases, etc.) as well as the kinetic melting period. We obtain the smallest errors relying on compatible balance and statistical methods. The easiest way to control the bath dynamics is direct measurement of initial parameters of the process, notably temperature, composition of metal and slag and their masses. The mathematical model is tested when the carbon mass fraction is predicted at the converter facility of the V.I. Lenin Metallurgy Plant. Finally, we determine that standard deviation of calculated mass fraction of carbon for medium-and low-carbon steels is 0,045%. [ABSTRACT FROM AUTHOR]