Application Analysis Of Mechanical Vapor Recompression Technology In Disc Dryer

Drying is not only one of the oldest unit operations, but also large energy consumption.Disc dryer which belongs to conduction type dryer, transfer heat to the wet material through the metal wall. the waste heat steam generated in the drying process contains a lot of low quality heat, and a small amount of dust particles. That steam discharged directly, not only wasting energy, but also polluting the environment. Transmitting heat pump drying technology, using the technology of mechanical vapor compression, is used for reuse the waste heat of steam discharged by transmitting dryer.The study of it is less at home and abroad, and no successful engineering example were reported.In this paper, the mechanical vapor compression technology was applied to the disc dryer, and a kind of energy conservation and environmental protection technology was designed.Using two heating modes technology, the compressor is not affected by the pressure and temperature of raw steam, and work more stably.The compression ratio was reduced.Condensed water from the heating process is partly used to washing the waste steam.Waste water is discharged to the filtering process., avoidding sewage emissions.The theory of system analysis of the technology were made, and according to the characteristics of high compression ratio and small flow in MVR drying process,a model of the liquid piston compressor was put forward.Factors analysis,exergy analysis and economical estimation Of the process were made by Aspen plus,and the process were compared with other two kinds of processes.The problem of non-condensable gas in the MVR evaporation experiment were analyzed, providing reference for MVR drying process.Analysis shows that the presence of non-condensable gas can reduce water vapor partial pressure in drying process,increasing the power of moisture transfer,and promoting the drying process, but part of the steam will be took away.Non-condensable gas enters the MVR drying process, making both steam consumption and compressor power consumption increase,therefore more operation cost were needed;When the compression ratio is 2, and no condensate gas, the calculation results show that exergy loss of MVR drying process was about half of that of the traditional drying process;Temperature difference between the condensation temperature of compressed steam and the drying temperature increases, making the compressor power increase, and then making the performance coefficient COP of heat pump lower;Drying temperature changing has little influence on the system’s COP coefficient; Economy estimates of the MVR drying technology and traditional technology show that MVR process saves more running cost, but the equipment cost of MVR process is more than the traditional process.Besides the cost increasing of device will be recycled at least in a year.MVR drying technology is suitable for materials of larger moisture content.The greater moisture content,the more operating cost saved.