Air dryers

Air dryers can be classified according to different characteristics such as operation process, operation pressure, heating mode, wet material movement mode or structure.  According to the operation process, air dryer is divided into intermittent (batch operation) and continuous two types;  

According to the operating pressure, air dryer is divided into atmospheric pressure air dryer and vacuum air dryer, operating under vacuum can reduce the space of wet steam partial pressure and accelerate the drying process, and can reduce the wet boiling point and material drying temperature, steam is not easy to leak, so,  Vacuum air dryer is suitable for drying heat sensitive, easily oxidized, explosive and toxic materials and wet steam needs to be recovered.  

According to the heating mode, air dryer is divided into flow, conduction type, radiation type, dielectric type and other types.  Flow air dryer, also known as direct air dryer, is the use of hot drying medium and wet material direct contact, heat transfer by convection, and the steam generated away;  Conduction type air dryer, also known as indirect air dryer, it uses the conduction mode from the heat source through the metal partition wall to transfer heat to the wet material, the generated wet steam can be removed by vacuum suction, through a small amount of purge gas or in a separate set of low temperature condenser surface condensation.  This kind of air dryer does not use drying medium, high thermal efficiency, the product is not contaminated, but the drying ability is limited by the metal wall heat transfer area, the structure is more complex, often operate under vacuum;  Radiant air dryer is the use of various radiators emitted a certain wavelength range of electromagnetic waves, wet material surface selectively absorbed after the change into heat for drying;  Dielectric air dryer uses high frequency electric field to dry the wet material.  

According to the movement of wet materials, air dryer can be divided into fixed bed type, agitation type, spray type and combined type;  According to the structure, air dryer can be divided into the van type air dryer, conveyor type air dryer, rotary air dryer, vertical air dryer, mechanical stirring type air dryer, rotary type air dryer, fluidized bed type air dryer, pneumatic air dryer, vibration type air dryer, spray dryer, air and combined air dryer, etc.  

The future development of air dryers will be in the in-depth study of drying mechanism and material drying characteristics, grasp the optimal operating conditions for different materials, the development and improvement of air dryers;  In addition, large, high strength, high economy, and improve the adaptability of raw materials and product quality, is the basic trend of the development of air dryer;  At the same time further research and development of new efficient and adapt to the special requirements of the air dryer, such as frozen dehumidifier, runner dehumidifier and air freeze dryer.  

The development of air dryer should pay attention to energy saving and comprehensive utilization of energy, such as the use of a variety of combined heating methods, transplant heat pump and heat pipe technology, the development of solar air dryer;  The automatic control technology of air dryer should be developed to ensure the realization of the optimal operating conditions.  In addition, with the attention of human beings to environmental protection, improving the environmental protection measures of air dryer to reduce the leakage of dust and waste gas will also be the direction of in-depth research.