Research On Low Temperature Waste Heat In Dealing With The Sewage Of Iron And Steel Industry Process

The iron and steel industrial process is a sophisticated chemical course which is accompanied by the phenomenon of water and heat symbiosis.At present,the main producing route of most steel enterprises is combination method of long process,which is consisted of sintering,coking,iron smelting,steelmaking and rolling.There is not only plenty of sewage discharged in the process of each stage of production,but abundant waste heat from middle and low temperature gas.Based on the production status of steel enterprises above,the article put forward a sewage disposal technology by the method of vacuum distillation to deal with the sewage of iron and steel industry process.The technology heats the sewage with the abundant waste heat from middle and low temperature gas under the negative pressure condition.The temperature of the gas can be reduced to 150?.The distilled water is used for making-up the new water of production in the iron and steel industry process.While the spissated sewage should be transport to the next process for further dispose.The technology can not only solve pressure of follow process of water dispose,but can also realize the efficient of water dispose and recycle.The paper makes the feasibility analysis of the method of vacuum distillation for each stage of production.The result shows that except sintering,all other stages can achieve the two basic rules of vacuum distillation,which is plenty of sewage waiting to be disposed and abundant waste heat from middle and low temperature gas.The result makes the method of vacuum distillation feasible in dealing with the sewage of iron and steel industry process.The paper also pays attention to the research on vacuum distillation in dealing with four kinds of the sewage of iron and steel industry process,analyzes the changing rules of distilled water quality index with different operating parameters,gives out ways and index of different kind of sewage while disposed under the method of vacuum distillation and makes sure the treatment method of distilled water and spissated sewage.The research shows that the sewage of coking process should be disposed by the method combined with vacuum distillation and adsorption and the other three kinds of sewage could be disposed by the method of vacuum distillation only.Totally,for all these four kind of sewage,the operating pressure should be controlled between 0.01 MPa and 0,03 MPa and the evaporation rate should be 40%to 50%.There is no need to control pH of the sewage,because the quality of distilled water fit the standard of water reusing in iron and steel industry process without any change of pH of sewage.The distilled water is used for making-up the new water of production in the iron and steel industry process.While the spissated sewage should be transport to the next process for further dispose.The technology finally achieve goal of water recycle and reducing.Furthermore,the paper also carries out laboratorystudies and case analysis on vacuum distillation process which unite the ues of low temperature wasteheat and the treatment of sewage of production process.The results show that blast furnace gas washing sewage can get efficient pertreated under thepressure of 0.025 MPa and the evaporation rate of 50%.The paper also figures out the heat transfer efficiency of the vacuum distillation device by 39.23%.If the method of vacuum distillation can be carried out over the sewage pertreament of coking,iron smelting,steelmaking and rolling,There will be sewage reduction quantity as 1235000 t,280600 t,217000t and 510000 t,and sewage reduction rate as 8.81%,18.62%,13.29%and 9.79%.The total sewage reduction quantity and sewage reduction rate are 2242600 m3 and 10%.The distilled water can be used for making-up the new water of production in the iron and steel industry process.And the spissated sewage is easy to be treated.The process serves multiple ends,saves water,reduces emissions,saves energy and reduces energy consumption.