Research On The Design And Characteristics Of The Heat Pump Sludge Drying System

With the rapid development of China's economy and society,domestic sewage and industrial waste water emissions are increasing year by year,and the output of sewage sludge which is the output of sewage treatment is increasing.The policy of environmental protection and energy conservation and emission reduction is becoming stricter,so the rational and effective treatment of sludge has become a key task to be solved urgently.In the process of sludge resource treatment,sludge drying is a vital necessary link.Compared with the traditional drying methods,the heat pump sludge drying system has obvious advantages.However,the research on the heat pump sludge drying system is less and lack of in-depth theoretical and experimental analysis,which limits the development of the technology,so it is of great significance to carry out relevant research on the heat pump sludge drying system.In this paper,the work flow optimization,system design method,low temperature drying characteristics and system performance of the heat pump sludge drying system were studied by means of theoretical analysis and experimental research.Firstly,based on the principle and characteristics of heat pump drying,the optimum design of air working process for sludge drying was carried out,and the favorable configuration of the heat pump sludge drying system was put forward.Secondly,this paper summarized and analyzed the design method of the heat pump sludge drying system.The main design idea was based on two aspects of compressor capacity and drying capacity.It mainly involved the selection and determination of the system running state,the design and calculation of the drying box,the selection and calculation of the heat pump equipment and so on.It provided a reliable theoretical basis for design of the system.Thirdly,the effects of sludge form,drying temperature,drying humidity and drying wind speed on the drying characteristics of sludge were investigated in this paper,and the drying model was analyzed and fitted.The results showed that the form of columnar sludge was a better form for sludge drying,and in the experiment the drying wind velocity had the greatest influence on the drying rate,followed by the drying temperature,and the drying humidity had the least influence on the drying rate of the sludge,and the Page model was the best to fit the process of the low temperature drying of the sludge.Finally,the steady state mathematical model of the heat pump sludge drying system was set up,and the operation of the system was simulated.The system dehumidification,the drying time of the sludge,the COPH of the heat pump and the power consumption were obtained,and the key parameters to measure the performance of the heat pump sludge drying system were also pointed out,which were the sludge drying time and specific moisture extraction ratio.In combination with the above parameters,the ideal operating range of the heat pump sludge drying system was given,and it was the drying temperature of the system reaching 65? ~75?.