Feasibility Study On Heat Supply Scheme Of Waste Heat Recovery From Industrial Sewage Of An Iron And Steel Plant In Yichun City

With the rapid development of China's economy,energy and ecological problems are becoming more and more serious.At present,the utilization rate of low-temperature waste heat resources in China's iron and steel enterprises is relatively low.The slag water of blast furnace belongs to low-temperature waste heat resources and is relatively abundant,which has great application potential.If it is rationally utilized in the field of heating,it will greatly reduce the consumption of coal for heating in winter and reduce the emission of air pollutants in large quantities.In this paper,the methods,technical difficulties and main problems of waste heat recovery of blast furnace slag water in Chinese iron and steel enterprises are investigated and analyzed.Adopt the method of theoretical calculation and field investigation,a steel mill in Yichun City of blast furnace slag waste heat water potential was analyzed,and get the factory blast furnace cinder flushing water waste heat potential can be fully meet the demand of the factory expansion of new buildings heating.The common waste heat recovery technology of blast furnace slag washing water is analyzed comprehensively.It is found that the waste heat recovery system of direct and interfeed blast furnace slagging water can not completely solve the problems of equipment blockage and scale formation in operation even after the application of efficient filtration and scale inhibition technologies.The heat exchange technology which can effectively solve the technical problem of waste heat recovery from blast furnace slagging water in steel works is introduced and determined according to the engineering practice.Combined with the actual engineering situation,four heating schemes are drawn up,which are vacuum phase change heat transfer waste heat heating scheme,connecting municipal heat supply network heating scheme,electric boiler heat storage heating scheme and gas-fired District boiler room heating scheme.Preliminary system design and equipment selection are carried out for different heating schemes.The recovery mechanism and technical reliability of vacuum phase change waste heat are analyzed in depth.The vacuum system performance,heat transfer efficiency,adaptability of offset slag water temperature change and adaptability to end load change of the vacuum phase conversion heat unit are all good,which can ensure the stable and continuous heating for end users in winter.According to the above four heating schemes,comprehensive comparative analysis is made from the aspects of technology,economy,energy conservation and environmental protection benefits.The initial investment of the vacuum phase transformation heat waste heat heating scheme is large,but the operation cost is relatively low.The dynamic evaluation method of equal annual value is adopted to find the best comprehensive economy.Using the primary energy utilization PER evaluation method,the PER value of the vacuum phase-change heat recovery heating system is 32.2,far higher than other central heating schemes,saving about6497 tons of standard coal PER year.At the same time,the vacuum phase-change waste heat recovery heating scheme can reduce carbon dioxide emissions of17022.14 tons,sulfur dioxide emissions of 55.22 tons,nitrogen oxide emissions of48.08 tons and carbon monoxide emissions of 149.4 tons per year,respectively,and its environmental protection benefits are also extremely considerable.