An essential element of any modern technology for the production of metal for transport vehicles --including railroad wheels --is treatment of the metal outside the furnace and its vacuum degassing. There are several methods of vacuum degassing in use, each having its advantages and disadvantages. The ladle method was chosen for the open-hearth shop at the Nizhnedneprovsk Pipe Plant, due to the specifics of OH steelmaking and the limited potential for obtaining a low-sulfur product on the one hand and, on the other hand, the increasing demand for low-sulfur steel in the world market.The following must be done for successful vacuum degassing: prevent furnace slag from entering the ladle or remove it if it does; provide for additional heating of the metal to compensate for the substantial heat loss from degassing and allow additional desulfurization with the introduction of slag-forming materials; correct the chemical composition of the metal, if necessary. The degassing system also provides for blowing of the metal with argon.These operations are performed on a "furnace-ladle" unit. The nature of the operations described above shows that the vacuum-degassing unit is actually a complex of equipment which in addition to the basic components includes a high-voltage substation with a filter-compensation unit, a water recycling system, a waste-beat boiler, a draft system for removing and cleaning outgoing gases, a section for monitoring the concentrations of gases dissolved in the metal, and other important components. The plant contracted with the Mannesman--Demag company to build such a system at its facility. The equipment layout was the responsibility of Ukrgipromez (Ukrainian State Institute for the Planning of Metallurgical Plants).In order to fit the equipment into the open-hearth shop, OH furnace No. 1 was taken out of service, while OH furnace Nos. 2 and 3 were provided with oscillating chutes to control the distribution of metal and divert the furnace slag. All of the equipment of the complex was supplied by subcontractors of Mannesman--Demag.Except for a few operations, the entire complex is completely automated. All of its components can be controlled from the central control post. Accomplishing this required the use of special programs, sophisticated computer technology, and debugging routines. The contract provides for two levels of system automation. All information on the condition of the controlsystem components and the measured process parameters is displayed on three monitors positioned in front of the operator. The computer keyboard is used to retrieve needed data to the monitor screen and control the system elements. The first level of the system provides for visual recording of process parameters, while the second level records the parameters in the memory of a special computer, retrieves cumulative data to the screen at the operator's request, and prints it out on demand.The process equipment and the hardware and software of the automatic control system (ACS), delivered, installed, and now being ...
One of the key components of the complex of equipment required for the operation of vacuum-degassing units is the system that measures the level of the melt in the ladle during vacuum degassing. This system was developed by the authors of this article. Prompt determinations of this parameter are necessary because the plant lacks enough overhead electric traveling cranes to quickly transfer more ladles to the degassing section for large heats. Thus, only a small part of each ladle used in vacuum degassing is left unfilled. Here, the freeboard AH --the distance from the still surface of the melt to the top edge of the ladle --is usually within the range 500-600 mm. The measurement system operates on the principle of radar. It entails the continuous emission of a frequency-modulated radio signal, reception of its reflection from an object, and calculation of the mean frequency of the difference signal --which is proportional to the distance to the object.The German company "MESSO, ~ as the main supplier of the equipment of the system, devised a method to link all of the elements of the system to the object (the vacuum degassing unit) by means of the initial data.The radar part of the system consists of an SHF block which continuously emits a frequency-modulated signal with a carrier frequency of 37 GHz (wavelength 8 mm) and a block that analyzes the signals reflected from the surface of the melt. The analysis block f'tlters out noise and analyzes the information, changing it into an analog signal for subsequent representation on the display of the control computer and recording by the recording equipment. A protective aiming device was developed to allow the SHF block to function properly in an environment of high gas and dust concentrations and thermal noise and permit adjustment of the emitter, i.e., checking of the direction of the radio waves in relation to the surface being monitored. The device includes a water-cooled thermostat that houses the SHF block and a scavenging chamber. A protective plate that is transparent to radio waves is positioned in front of the emitter to protect the antenna, part of the system. The protective aiming device, with the SHF block enclosed, is mounted directly on the cover of the vacuum-degassing unit, while the signal analysis block is located in the control room.The level-measurement system was calibrated on a still steel surface before it was placed in operation. The aiming" device was used to adjust the vertical position of the SHF block for the maximum intensity of reflected signal. The calibration was done for five distances to the object (target) within the range 2-4 m. For each distance, we recorded the current of the output signal and the distance from the surface of the receiving-transmitting antenna of the SHF block to the surface of the bath. Two measurements were obtained for each level: distance to the target was decreased for each level in the first series of measurements and increased in the second series. The dependence of the output current on distance is distin...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.