Кафедра ливарного виробництва (ДМетІ)

Permanent URI for this communityhttp://crust.ust.edu.ua/handle/123456789/15008

ENG: Department of casting production (DMetI)

Browse

Now showing 1 - 3 of 3

Construction of a Kinetic Equation of Carbon Removal for Controlling Steel Melting in the Metallurgical System "Cupola Furnace – Small Converter"
(TECHNOLOGY CENTER PC, Kharkiv, 2025) Makarenko, Dmytro M.; Selivorstova, Tetiana V.; Dotsenko, Yuriy V.; Osypenko, Iryna O.; Dzevochko, Oleksandr M.; Pereverzieva, Alevtyna M.; Dzevochko, Alona I.
ENG: The object of research in the paper is the process of steelmaking in a small converter, which works in tandem with a cupola furnace. The existing problem is that the control of the process of obtaining steel in an oxygen converter is complicated by the need to determine in real time the current chemical composition of the melt, in particular carbon. This is due to the fact that the rate of carbon removal is too high, as a result of which the process of carbon removal is transient. Therefore, it is too difficult to implement regulation based on feedback on continuous measurement. The presence of the specified problem requires solutions related to the possibilities of developing or improving software control of the process. It is shown that in certain sections of the process within each time section of oxygen purging of the melt in the converter, the kinetic curve has a linear form with a constant coefficient value in front of the inlet mine. But the value of the initial coefficient for each equation that describes the process within its limits changes. This allows to state that in case of a change in the initial condition, the kinetic curves shift relative to each other in parallel. On this basis, a system of equations has been constructed that describes the process of carbon removal in a small oxygen converter that receives liquid iron from a cupola furnace. It has been shown that to use the obtained system of equations, it is necessary to know the initial carbon content in the melt discharged from the cupola furnace, and it depends on the method of oxygen supply to the cupola furnace. Based on the modeling of this process in two variants – using a “sharp blow” and supplying oxygen to the air blown into the tuyeres, a nomogram has been constructed. It allows to determine the initial carbon content for the practical use of the obtained system of equations. Using the obtained system makes it possible to determine the time after which oxygen cutoff should be made. This will allow to decide to implement software control of the melt blowing process in the converter. The presented study will be useful for machine-building enterprises that have foundry shops in their structure, where cast iron is smelted for the manufacture of castings.
Determination of Conditions for Preventing Chemical Wear of Induction Furnace Lining in the "Cupola Furnace – Induction Furnace" Duplex Process
(TECHNOLOGY CENTER PC, Kharkiv, 2025) Nikolaev, Denis A.; Selivorstov, Vadim Yu.; Dotsenko, Yuriy V.; Osypenko, Iryna O.; Kuznetsow, Eugene V.
ENG: The object of research is the melting of cast iron in the “cupola furnace – induction furnace” duplex process. The need to study such a duplex process is dictated by the condition of ensuring the required quality of cast iron in the event that a low-quality or uncontrolled charge is used. This condition cannot be met if the induction furnace is used as the only melting unit. But the problem is that in the process of induction melting of cast iron, in particular at the stage of overheating and holding the melt, a crucible reaction may begin, which leads to chemical wear of the lining. The need to reduce the carbon content in the melt discharged from the cupola furnace requires an increase in temperatures, which creates risks for the onset of a crucible reaction. Based on statistical calculations of cupola melting parameters, it was found that in the melt discharged from the cupola furnace into the induction furnace, the average carbon content is C = 3.47% with a standard deviation SC = 0.14%, and the average silicon content is Si = 2.05% with a standard deviation SSi = 0.21%. At the same time, with a probability of 96%, the carbon content is C = (3.33–3.75)%, and the silicon content corresponds to the range Si = (1.84–2.46)% with a probability of 98%. It was found that the equilibrium constant is in the range (0.15–0.21) with a probability of 97.8% at an average temperature T = 1355°C with a standard deviation of temperature ST = 6°C. With such melt parameters, which are supplied to the induction furnace, the risks of the onset of a crucible reaction do not arise. It was determined that even at temperature regimes sufficient to remove FeO, the risk of the onset of a crucible reaction is minimal. In order to ensure conditions that prevent the onset of a crucible reaction, the following recommendations should be followed for the content of carbon and silicon in high-temperature melting when the temperature is in the range T > 1480°C: C > 0.3% and Si < 0.3%. The results of the study can be used in the melting sections of foundries equipped with cupola furnaces and induction furnaces.
Identification of Temperature in Cupola Furnace Based on the Construction of the "Slag Composition – Slag Viscosity" Model
(TECHNOLOGY CENTER PC, Kharkiv, 2025) Nikolaiev, Denys A.; Selivorstov, Vadim Yu.; Dotsenko, Yuriy V.; Dzevochko, Oleksandr M.; Pereverzieva, Alevtyna M.; Dzevochko, Alona I.
ENG: The object of the study in the work is the temperature regime of melting in a cupola. The existing problem is that due to the aggressive high-temperature environment, continuous measurement of the parameters of the internal environment in the working space of the cupola furnace is too difficult. Even with the implementation of such a possibility, errors of the first and second types may occur. This necessitates indirect control of the temperature regime, which could provide a solution to the identification problem – whether the control system is really operating in normal mode and meets the accuracy requirements, or whether there is a parametric failure along the corresponding control circuit. The existence of the specified problem requires solutions related to the definition of criteria for evaluating the temperature regime, by which it would be possible to verify the reliable functioning of the melting control system. A criterion for evaluating the temperature regime of melting by the viscosity of the slag as a function of its composition is proposed, which allows identifying the temperature regime of melting with an accuracy of 96 %. This result is due to the proposed two-stage procedure, in which the first stage is the construction of mathematical models that describe the influence of the slag composition on the viscosity, and the second is the construction of a criterion based on the density distribution of the discriminant function for both temperature regimes. Using the obtained criterion also makes it possible to determine the areas of chemical compositions, by which the temperature regime can also be identified. The relationships between the variables for the identification procedure are presented in the form of a structural diagram. The proposed solutions will allow determining the quality of the functioning of the temperature control loop in the melting control system based on periodic control. The presented study will be useful for machine-building enterprises that have foundries in their structure, where cast iron is smelted for the manufacture of castings.