循环喷雾闪蒸影响因素的实验研究

Experimental investigation on the influencing factors of circulatory spray flash evaporation

闪蒸是液体经历压力突降时的快速汽化现象,循环喷雾闪蒸具有节能环保、可充分利用低品位热能的特点,在高耗能行业的余热回收方面展现出良好的应用前景。文章以闪蒸在余热发电领域的应用为出发点,以工业余热为热源,基于大型闪蒸实验平台,使用控制变量法,进行循环喷雾闪蒸变工况实验,研究液体过热度、闪蒸压力、供水流量、喷射方向和喷嘴尺寸对闪蒸特性的影响,分析闪蒸蒸汽流量和汽化率的变化规律。结果表明:闪蒸蒸汽流量和汽化率随过热度的提高而增大,随闪蒸压力的提高而减小,蒸汽流量随供水流量近似成比例的变化;液体向下喷射的闪蒸效果优于向上喷射,喷嘴尺寸的减小使喷雾液滴粒径减小,缩短了液体在闪蒸罐内停留时间。

Flash evaporation is the instant boiling phenomenon of a liquid caused by an abrupt pressure drop.Circulatory spray flash evaporation is energy-saving and environmentally friendly,and can fully utilize low-grade thermal energy.It is a promising method for waste heat recovery in energy-intensive industries.This study focuses on the application of flash evaporation in waste heat recovery process.A large-scale flash evaporation experimental system is built,which uses industrial waste heat as heat source.Experiments on circulatory spray flash evaporation under various conditions are carried out with the control-variate method.The influence of superheat degree,evaporation pressure,flow rate of supplied water,injecting direction and nozzle size on the characteristics of flash evaporation is investigated.The variation of the flow rate of flashed vapor and the evaporation ratio is analyzed.The results show that both the flow rate of flashed vapor and the evaporation ratio increase with the increase of superheat,and decrease with the elevation of evaporation pressure.The flow rate of flashed vapor is nearly proportional to that of supplied water.Downward injection outperforms upward injection.The reduction in nozzle size reduces the size of droplets in the spray,and at the same time shortens the residence time of the liquid in the flash chamber.