Browsing by Author "Choshnova D."

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    Enhancing the energy and environmental efficiency of the fire refining of blister copper in anode furnace part I: Optimization of the heat generation in the operations area of the furnace
    (2018-01-01) Choshnova D.; Iliev P.
    The presented study provides useful information about the tendencies for optimization of the heat generation in the working area of the fire refining furnace of blister copper. A theoretical analysis of the possibility for replacing of the used fuel oil with natural gas is made. For the porpuses of the present study in house software product ``GOR`` of the Department of Physical Metallurgy and Heat Aggregates at the University of Chemical Technology and Metallurgy, Sofia, is used. The change of the theoretical combustion temperature of both fuels under different process conditions is studied. It is found that at combustion of natural gas with 2 % oxygen enrichment of the oxidation stream, values comparable to the theoretical combustion temperature of the fuel oil are achieved. The environmental effects from replacing of the fuels are exposed. The obtained results can be used to predict the change of the temperature field in the anode furnace when changing the conditions of its operation.
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    Gas-blast regime of blast-furnace smelting at the beginning of the furnace blowing-in period after thorough repairs
    (2015-01-01) Ivleva L.; Titov V.; Choshnova D.; Inozemtsev N.
    Thermal and gas-dynamic phenomena on the top throat of the blast furnace in the blowing-in period regarding the oxidation and heat transfer processes in the hearth of the blast furnace are considered. The first blast should be produced in the forced mode to prevent the emergence of anomalous thermal and gas-dynamic phenomena at the throat that are dangerous to the blast furnace construction and to speed up the normal operating mode parameters of the furnace.
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    Improving of the water preparation systems in the industry thermal power plants
    (2018-01-09) Choshnova D.
    Some modern possibilities for modernization of the water preparation in the heat power plants of metallurgical enterprises are presented. It is focused on the ecological and technological advantages of the methods for obtaining of ultra-pure water. This work is not intended to justify the need of usage of particular technology in an object. This is a separate task requiring in-depth consideration.
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    INFLUENCE OF LOW-TEMPERATURE THERMAL RADIATION AT THE HEAT TRANSFER TO AN AIR AMBIENT
    (2020-01-01) Stanev R.; Choshnova D.; Velibashev S.
    The availability of some contradictory recommendations and facts in diferent literature sources has given a reason as a purpose of the present work to be chosen the fulfllment of a quantitative analysis of the influence of the radiative component in the total low-temperature energy fux. This aim is realized, as three typical for the practice cases are examined. They are connected to the heat transfer through a window of a residential room, from a tube with warm water to the environment and in a steel recuperator for air preheating by the internal energy of the outgoing fue gas from an industrial furnace. The results from the quantitative analysis of the influence of the radiative constituent in the total low-temperature heat transfer are commend and on the basis of them are formulated concrete ascertainments, to what kind of errors would lead the neglecting of the discussed mechanism
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    Investigation of the Possibilities for Infrared Diagnosis of Peirce–Smith Converters in Non-Ferrous Metallurgy
    (2025-09-01) Mihailov E.; Choshnova D.; Ivanova M.; Asenova M.
    To implement predictive maintenance of units in the practice of metallurgical manufacturers, computer information and diagnostic systems are being developed to assess the current state of individual units throughout their entire life cycle. This publication presents the results of a study on developing an infrared diagnostic system for predictive maintenance of converter units in the non-ferrous metallurgy industry. A 3D mathematical model of the transient heat transfer in the wall of a real operating unit has been developed and numerically implemented to study, analyze, and diagnose surface temperature fields resulting from wear and local damage. To adjust the operation of the mathematical model, the design parameters and the results for operating and technological parameters from an industrial experiment are taken into consideration. Using the model, a full-factor experiment was simulated to study the surface temperature fields resulting from the erosion wear of the wall and the presence of local damage. Based on the simulation results, the optimal time range for thermographic monitoring is determined. A regression dependence was derived to predict the refractory wall wear as a function of the outer surface temperature of the converter unit. The results are part of a comprehensive investigation aimed at developing thermal imaging techniques for converter units in non-ferrous metallurgy.