Hydrodynamics and mass transfer performance analysis of flow-guided trapezoid spray packing tray

Distillation is the most common separation technology utilized in the petroleum and chemistry industries.Due to the wide usage of the distillation column,even a small improvement in performance may result in significant energy cost savings.Aiming to improve the hydrodynamics and mass transfer performance,the flow-guided trapezoid spray-packing tray(FTS-PT)was designed by combining flow-guided holes and trapezoidal caps with structured packing.And the experimental measurements of the FTSPT,including pressure drop,clear liquid height,weeping,entrainment,and tray efficiency,were conducted in a 500 mm diameter plexiglass column with the air-water-oxygen system.Moreover,the performance of the FTS-PT was compared with that of new vertical sieve tray(New VST)and F1 valve tray.The results show that FTS-PT has a significant advantage in pressure drop,entrainment,and capacity.Furthermore,the calculation model of the pressure drop was derived and used for the FTS-PT with a relative deviation of less than 5%.

植保施药机械喷雾雾滴飘移研究进展

中国农药产品80%以上通过喷雾方式施用,药液从喷头到靶标作物过程中产生的随风飘移和蒸发飘移是农药造成人畜健康风险、生态环境破坏的重要因素之一。随着航空施药技术的发展,解决或减少喷雾雾滴飘移的问题成为施药技术研究的重点和热点。基于此,本文分别从喷雾雾滴(尺寸分布、黏度、表面张力、蒸气压、挥发性、密度等)、喷雾模式(喷头类型、喷雾速度和高度、喷施方法)和外界条件(风速、风向、温度、湿度、气流等环境条件和操作人员技术水平等)等方面系统分析了产生雾滴飘移的主要原因;同时详细综述了采用田间试验、室内试验、计算机模拟及新型测试技术测定喷雾雾滴飘移的优点及局限性,针对植保无人飞机施药,提出应通过室内测定、田间试验与计算机模拟相结合的方式开展雾滴飘移研究。在此基础上分析并总结了从改变雾滴的运动方式、理化性质等方面直接控制和从田间布局间接控制的喷雾雾滴飘移风险控制技术。