| In the process of the electric furnace steelmaking,the energy is taken away about 22～27 percent by the cooling water,flue gas and dust.The process is a high energy-consuming technology.Sha-steel Group Co.LTD has been running 5×100t UHP electric arc furnaces for making steel product.It has implemented flue gas waste heat recovery projects on the 1#～4#electric furnace.The 1#～3#electric furnace are applied to the heat pipe waste heat boiler technology,and the 4#electric furnace is the column heat recovery boiler technology.Due to the design defects of the 4#electric furnace waste heat recovery system,it has not been operating normally after the operation,and the recovery efficiency is obviously lower than the normal level.Through the analysis and research of the design defects of waste heat recovery system in this paper,the direct causes of various faults are found and analyzed,and some structural changes are made by using the engineering transformation experience,so that the system performance and the waste heat recovery level are greatly improved.The main conclusions are obtained as follows:(1)Through analyzing the cracking sample of water-cooled flue,the main reason is that the material and structure of the pipeline are unreasonable.Creep failure and stress failure of water cooling pipes caused by local periodic overheat led to leakage of pipelines.This paper proposes that improve the service life of the flue by optimizing the structure and material of pipe and the flue gas flow rate and cooling speed,etc.(2)By consulting the actual operation data,the main reasons for the low in let flue gas temperature,high exhaust gas temperature and low steam production are as follows:insufficient iron-to-water ratio,low flue gas volume,low flue gas temperature and insufficient heat exchange area of the boiler.After re-calibrating the actual flue gas flow,selecting reasonable flue gas flow and temperature according to different smelting conditions,and adding new boiler heat exchange area,the adaptability of the waste heat boiler to the actual working conditions were enhanced,and the recovery efficiency was improved.(3)The main reason for the impact of steam from waste heat boiler are the unreasonable design of heat accumulator pipeline and control mode.By adjusting the heat charging,exothermic way and control mode of steam accumulator,the steam pressure and flow are stabilized,the impact of the steam on the external network is reduced,and the value of steam utilization is increased.(4)The performance data shows that the level of recovered energy is much higher than the previous system,produce steam is as high as 279.846 kg/t of steel at peak time when hot metal charging ratio is high.The average value is 163.8kg/t of steel and the recovery efficiency is nearly 50%higher than the previous system. |
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