Novel Design And Performance Study Of MVR Rake Drying System

Drying generally refers to the direct or indirect way to transfer energy(usually heat)to the wet material,the moisture(in most cases,it's water)separation and material transformation,to achieve a certain moisture content of solid products.The energy consumption of drying process is related to the heat of phase change,heat and mass transfer,and energy recovery.As the heat of the phase change of moisture(especially water)is larger,the energy needed for dehumidification will be greater.Using MVR(mechanical vapor recompression)technology,recovery of drying process of removal things'(secondary steam)phase change heat(condensation heat),energy saving effect is remarkable.Traditional rake drying systems use steam(or hot water,etc.)into the jacket and hollow shaft to as heat materials,generally drying is under the vacuum,exhaust gas after filtered,condensation dehumidification then discharge by the vacuum pump.In order to reduce the energy consumption of the vacuum rake drying process,the Roots steam compressor was used to replace the vacuum pump in the rake drying system.The moisture(secondary steam)has been compressed,and humidified to eliminate overheating,then add a small amount of steam as a heat source to use.Not only saving a lot of heat energy,but also saving the cooling energy,energy-saving effect is remarkable.Just like traditional rake drying systems,this system is particularly suitable for drying heat-sensitive,easily oxidized and moisture-recoverable materials.The material to be dried may be a powder,a paste,a slurry,or a solution(in this case,there are evaporation,crystallization and drying process).A set of MVR rake drying experiment system was designed.The main equipment needed for MVR rake drying system was selected.According to the experimental process,built experimental MVR rake drying system,and the relevant performance were tested.Based on the experimental results of the MVR rake drying system,it is found that the selection of appropriate small compression ratio,appropriate low drying pressure and controlling steam superheat are all beneficial to improve the operating efficiency of the system.The experimental results show that the COP is 4.4~8.8 and the SMER is 2.0~3.4kg/(kW·h)in the experiment of water evaporation experiment.And the experiment is also carried out with Sodium carbonate solution as the dry material.The COP is 3.1~7.3,and SMER is 1.2~2.8kg/(kW·h).Its' energy efficiency is significantly better than the traditional rake dryer,we can continue to developing related technologies to make the system applied to reality.