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 ...
The use of moist unformed refractories for the production of steel-teeming ladle monolithic linings increases the role of drying as a production operation regulating the preparation of linings and influencing the life of the lining in service of the ladle.Until now the process of drying of linings with the use of the energy liberated in combustion of gas in the ladle has remained unstudied.In the few publications devoted to this operation, its disadvantages have been noted.Nonuniform heating of the surface with the flame of the burning gas leads to significant moistening of the reinforcing layer and formation of undried zones [i, 2], the occurrence of cracks on the whole surface, spalling, and screes in the lower portion of the ladle, and in some cases to collapse of the lining [3,4]. To eliminate the defects occurring attempts have been made to do the drying in two or more stages with different rates of gas consumption [5,6].However, the ladle drying programs developed in some plants have not been soundly based and opinions on the maximum temperature at the boundary of the lining working and reinforcing layers at the moment of completion of drying have been contradictory.We should also turn our attention to the long drying time, which involves significant losses of heat in combustion of gas in the ladle.The efficiency of existing drying equipment based on gas burners has been determined as not more than 5% [i].The basic reasons for the low effectiveness of drying of linings by the products of gas combustion are the result of the drying method itself.The input of heat to the moist surface from the high-temperature flame of the burning gas creates high gradients of temperature, capillary or chemical potential, and pressure of the stream-air mixture in the pores of the lining surface layer.Under the action of temperature and pressure gradients, filtration transfer of moisture in the form of water and steam into the depth of the lining predominates over diffusion mass transfer to the open surface of the lining under the action of the capillary or chemical potential gradient. As the result intense moistening of the reinforcing layer and accumulation of water at the ladle shell in the less heated zones of the monolithic layer occur.Evaporation of the moisture within the lining and removal through the steam holes in the shell require significantly more energy and time than evaporation of it from the open surface. This is responsible for the long drying time and the presence of undried zones in the lining of the lower portion of the ladle.Input of heat from the gas burner flame which is nonuniform over the surface creates in the monolithic lining nonuniform distributions of temperature, moisture content, and excess pressure of the steam-air mixture both across the wall thickness and in the height of the ladle.Nonuniform and sharply unsteady temperature and moisture content fields are the reason for the occurrence of temperature and moisture (mass-thermal) stresses [7] in the lining working layer.The mass-thermal stresse...
The engineering department of the Nizhnedneprovsk Pipe Plant has completed drawings and specifications for equipment designed to apply an enamel coating to the inside surface of pipes made in accordance with GOST 8731-74 and GOST 8732-78. A suitable technology that employs this equipment has also been developed. The pipes are made of steel 10-20 and have a diameter of 89-273 mm, wall-thickness of 5-12 mm, and length of 8-12 m.The thickness of the enamel coating is 0.3-0.4 m. A distinguishing feature of the new technology is that it is realized using relatively simple equipment occupying a limited area and requiring a minimum number of operations. Existing equipment is used in several of the operations, and the process can be fully mechanized.Enameled test specimens have met the hygiene standards currently in effect. The specifications for the enamel and the finished pipes were also developed in accordance with existing hygiene-sanitation standards.The pipes can be used in different sectors of the economy: for pumping oil and the accompanying corrosive components, as well as other aggressive media.The service life of the enameled pipes should be at least 20 yrs. The enameling technology is protected by a patent.Nizhnedneprovsk Pipe Plant.
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