Experimental Study On Heat Transfer Of Blast Furnace Slag Particles Around Circular Tubes In Waste Heat Boilers

China’s steel industry produces a large amount of blast furnace slag every year,but the waste heat resources contained in the blast furnace slag have not been effectively used.At present,the mainstream method for treating blast furnace slag in China is still water quenching,which not only wastes a large amount of waste heat resources in the blast furnace slag,but also consumes a large amount of water,electricity and generates harmful gases during the water quenching process.Dry granulation of blast furnace slag has great advantages over water quenching.It can recover waste heat during the granulation process without consuming slag water,and basically produces harmful gases.In this paper,a semi-industrial waste heat recovery experimental bench,a self-flow bed waste heat boiler,is designed to recover blast furnace slag particles obtained by dry granulation.This article designed and built a semi-industrial waste heat recovery experimental bench-self-flow bed waste heat boiler and examines the changes in the slag particle size,slag particle flow rate,heat exchange tube arrangement,and the vertical and horizontal spacing of the heat transfer tubes to the overall heat transfer coefficient of the self-flow bed waste heat boiler and the slag particle temperature drop Rate and heat recovery rate,in order to find a feasible solution to strengthen heat exchange,and prepare for the industrial application of the self-flow bed waste heat boiler.The experiment reached the following conclusions.(1)The comprehensive heat transfer coefficient of the self-flow bed waste heat boiler decreases with the increase of the particle size of the blast furnace slag particles,and gradually increases with the increase of the flow rate of the blast furnace slag particles.The comprehensive heat transfer coefficient is higher than the integrated heat transfer coefficient of the self-flow bed waste heat boiler when arranged in a row.The increase in the horizontal and vertical spacing of the heat exchange tubes will cause the comprehensive heat transfer coefficient of the self-flow bed waste heat boiler to decrease.(2)The heat recovery rate of the self-fluidized bed waste heat boiler gradually decreases with the increase of the particle size of the blast furnace slag particles.With the flow rate of the blast furnace slag particles increases,the heat recovery rate increases first and then decreases;The heat recovery rate of the bed waste heat boiler is higher than the heat recovery rate of the self-flow bed waste heat boiler when arranged in a row.The increase in the horizontal and vertical spacing of the heat exchange tubes will reduce the comprehensive heat transfer coefficient of the selfflow bed waste heat boiler.(3)The temperature drop rate of blast furnace slag particles decreases with the increase of the blast furnace slag particle size,and gradually increases with the flow velocity of the blast slag particles.The temperature drop rate when the rows of heat exchange tubes are arranged in a row.The temperature drop rate of the heat transfer tube increases.The increase in the horizontal and vertical spacing of the heat exchange tubes will cause the temperature drop rate of the blast furnace slag particles to decrease.Comprehensively considering the influencing factors that affect the heat transfer coefficient of the slag measurement of the self-fluidized bed waste heat boiler,the correlation of the slag measurement and heat transfer experiment is obtained through dimensional analysis,which can meet the industrial application requirements within a certain parameter range.