Search

One of the most energy-intensive industries is ferrous metallurgy. The metallurgical sector in industrially developed countries is reducing its specific energy consumption per one ton of products by approximately 1.0 - 1.5 % per annum. In Russia, obsolete technology is the main reason for the high-energy intensity of industrial product. Energy saving in industrial production is associated with production technology and the scope of fuel and energy resources consumption. Therefore, ways to improve energy efficiency focus on reducing energy consumption of any kind during a specific process in a specific process or thermal unit. Ensuring the economical operation of furnace units requires detailed preliminary and verification analyses, upgrading and introduction of state-of-the-art equipment. The study presents a flow diagram and features of thermal operation of a new drum-type chamber furnace for heating metal products for quenching. The technical parameters of the furnace, the results of the thermo-technical analysis, the heat balance and the specific fuel consumption as applicable to the created design are also presented. The flow diagram of the furnace has significant advantages in terms of the energy efficiency of fuel as compared to the roller and conveyor methods of metal transportation. Placing blanks on the drum significantly reduces the complexity of their transportation. Thanks to its small length the proposed design is compact and easy to place in a workshop. The use of a recuperative fuel burning device allows the efficient use of the heat of waste gases in the heating process. The proposed design and method of products transportation in the furnace working space can be used for the heat treatment of bars, pipes, strips, as well as rolled steel of various shapes. © 2021 National University of Science and Technology MISIS. All rights reserved.

Presently, the furnace stock of the ferrous metallurgy and heavy engineering industry comprises approximately 55%–60% of units with service life over 30–50 years. Considering that constructing new furnaces requires significant financial investments and reduces production over a long period, the technical re-equipment and modernization of units in accordance with modern requirements have become widely adopted. This paper presents an appropriate methodology for the technical re-equipment and modernization, one that enables reducing time and achieving the optimal result with the lowest cost.

Fuel combustion processes play an important role when firing materials in rotary kilns. In this paper, we provide brief information on the design and operation principle of the burner with a combined combustion system that was developed specifically for the new rotary kiln for burning chamotte. The computer modeling results of the natural gas combustion process performed in the ANSYS software package are presented.

—The productivity of rolling and pipe-rolling mills and the product quality may be improved by heating the metal billet in furnaces with minimum oxidation and decarburization. That is possible in annular furnaces, which are widely used in the rolling of pipe and railroad wheels. High-quality heating permits the creation of metal structure with specified thermophysical and operational properties, as well as the plasticity required for subsequent machining. In the present work, the operation of an annular furnace used to heat pipe blanks before rolling at PAO Chelyabinskii Trubokatnyi Zavod (ChTPZ) is analyzed. Thermal problems are considered: in particular, the high fuel consumption in heating blanks and high external temperatures of the walls and roof; the low rate of blank heating; and the serious leakage of air into the furnace’s working space. In addition, a defect of the gas-burner design is that the gas supply cannot be regulated, despite the wide load range (including periodic shutdown). Finally, practically no use is made of the thermal energy in the exhaust gases. In the analysis of these problems, the heating of the metal is calculated, and the thermal balance of the annular furnace is formulated. The analysis reveals factors that decrease the energy efficiency of the existing furnace design. Measures are proposed for furnace modernization so as to decrease the fuel productivity and increase the productivity: for example, the use of fiber refractories; regenerator burners; and barriers that are not water-cooled. To assess the effectiveness of these measures, we formulate the thermal balance of the redesigned annular furnace and analyze its thermal operation. The proposed measures are expected to provide significant economic benefit and to improve the heating of the metal, with decrease in fuel consumption and increase in productivity. In particular, after reconstruction, increase in the furnace’s total efficiency (by 18.1%) and thermal efficiency (by 31.0%) is expected, as well as decrease in fuel consumption by 48.3 kg CF/t.

High productivity of rolling and pipe rolling mills, good quality of finished metal products is possible to provide in the presence of powerful heating furnaces, well heating the metal with minimal oxidation and decarburization. Such conditions are provided by ring furnaces which are widely used for heating the preparations at rolling of pipes, wheels and bands of the railway rolling stock. The purpose of the heat – receiving structure of the metal, providing a set of physical and working properties, or impart to these materials the ductility required for subsequent machining. The article deals with the design and thermal performance of the ring furnace operating at ChelPipe’s Pipe Rolling Plant No.2. The problems arising during the operation of the thermal unit are analyzed. The paper describes the calculation of heating of metal and heat balance of the ring furnace. In the course of the analysis of the results of design studies, the shortcomings of the existing heat recovery system are revealed and measures for the reconstruction of the furnace to reduce fuel consumption and increase productivity (replacement of the existing brick lining with fibrous, the use of regenerative burners, the use of non-water-cooled partitions, etc.) are proposed. The paper analyzes the design and thermal performance of the ring furnace for heating of pipe billets before rolling. It shows a heat balance of the ring heating furnace and provides measures for furnace reconstruction aimed at reduction in fuel consumption and increase in efficiency: replacement of the existing lining with fiber lining, use of regenerative burners, application of non-water cooled walls.

In the report the scheme and features of thermal work of the chamber furnace of drum type for heating of metal products under hardening are presented. The technical characteristics of the furnace, some results of thermal calculation are shown. Computer simulation of gas motion and heat exchange processes in the furnace are presented. The study was performed using CAE-system (CAE, Computer aided Engineering) – software module ANSYS Fluent. Boundary conditions of flow flow flow were set in this module. To verify the convergence of the calculations, the control of the current values and calculated temperature residuals was used. The simulation results are presented graphically and contain a visualization of the temperature and velocity distribution fields, as well as a vector distribution of gas flow velocities. The obtained results of computer simulation allowed to estimate the efficiency of thermal and gas-dynamic work of the developed design of the chamber drum-type furnace with a constant temperature of the working space. The developed design of the furnace for heating metal billets with the movement of billets in the furnace on the drum allows to solve some problems of resource and energy saving, can also be used for heat treatment of bars, pipes, strips, and rolled bars of various shapes.

The thermal-performance and design characteristics of modern energy-saving reheating furnaces for heating various types of metal products are presented. The furnaces developed by the VNIIMT satisfy current requirements on unit energy consumption, emissions, and the level of automation of industrial processes. The furnaces have been introduced at various plants and their operating indices have been shown to fully correspond the design data.

High performance of rolling and tube rolling mills, good quality of finished metal products can be obtained by heating metal billets with minimal oxidation and decarburization in heating furnaces. Such conditions can be provided by annular furnaces, which are widely used in the rolling production of pipes, railway wheels and tires. High-quality heating allows us to obtain the structure of metal products with given thermal and working properties, as well as the plasticity necessary for subsequent mechanical processing. In this paper, we consider thermal engineering features of the operation of an annular furnace for heaŧing billets before rolling at “Chelyabinsk Tube Rolling Plant” PJSC (ChTPZ). The problems arising during the operation of thermal unit were analyzed: High specific fuel consumption for billets heating; high temperatures of walls external surfaces and roof external surfaces; low heating rate of the billet; large amount of air leaks into the furnace working space. Also design of gas-burning devices does not provide the possibility of regulating gas supply in a large range of loads, up to a periodic complete shutdown. And thermal energy of waste gases is practically not used. Metal heating has been analyzed and annular furnace heat balance has been compiled. Analysis of the results of computational studies has revealed factors that reduce energy efficiency of the existing furnace design. The measures were proposed for its modernization in order to reduce fuel consumption and to increase productivity (use of fibrous refractory materials, regenerative burners, non-water-cooled partitions, etc.). To assess impact of the proposed measures, the furnace heat balance after its systems reconstruction and assembly has been compiled, the main indicators of the furnace heat operation have been determined. When implementing proposed measures, significant economic effect is expected, including improvement in quality of metal heating while reducing fuel consumption and increasing productivity of the unit. In particular, after furnace reconstruction it is expected to increase the total (by 18.1 %) and heat (by 31.0 %) efficiency of the furnace, and to decrease (to 48.3 kg conditional fuel/ton) specific fuel consumption. © 2019, National University of Science and Technology MISIS. All rights reserved.

The reconstruction of a furnace with a rolling hearth for the heat treatment of welded metal structures is described. The primary heating system based on twelve high-speed recuperative burners is supplemented by a recirculation system for the exhaust gas, which is heated in a portable chamber. That ensures uniform temperature distribution in the furnace’s working chamber, to within ±10°C. The introduction and debugging of the furnace is considered.

Electric heaters with radiant-convective heat transfer between the heating elements and the walls of the sealed housing are developed. Industrial tests show that intensification of the heat liberation from the coils by ventilation using a circulatory fan increases their life by 30–50% in comparison with existing devices, by reducing the temperature of the elements. The sealed housing permits their use in convective furnaces with protective or aggressive atmospheres.

An aerodynamic system with periodic reversal of the hot-gas flow is proposed for a convective furnace, so as to ensure uniform temperature distribution over long parts. The hot gas is driven by a reversible device consisting of two centrifugal fans mounted in opposite directions. Experimental data are obtained for the hydraulic losses of fans of different types with reverse flow of air. The best centrifugal fans for use in reversible devices are identified.

A high-temperature furnace with regenerative burners is tested. A heating system with high-speed pulsed burners is shown to make maximum use of the heat of the fuel within the furnace and uniform billet heating, while meeting emissions standards.