Investigating the thermal work and construction of annular furnace on “Chelyabinsk pipe-rolling plant” PJSC to improve heat technical indicators of its work

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 heating 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 (to48.3 kgconditional fuel/ton) specific fuel consumption. 

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