Research On The Filtering And Mixing Characteristics In The Internal Filtering Jet Loop Reactor

For its simple structure, being mixed fully, good characters of heat transfer and mass transfer, low energy consumption, easy to be engineering amplified, jet loop reactor has been more and more widely used in biological chemistry, chemical industry and wastewater treatment and the hydrogenation of coal liquefaction, and other fields.This research designed a newly type of jet loop reactor in order to solve the problem of liquid-solid separation in actual production. The draft tube of the traditional reversed flow jet loop reactor was designed as a filtering draft tube which was composed of two concentric cartridges. The inner was the filtering cylinder, functioning as draft tube and filter. The reactor combines reaction and liquid-solid separation technology, and it’s especially suitable for continuous catalytic reaction in which the solid was regarded as the catalyst.The diameter of the device in this study is 150 mm, the height to diameter ratio is 2.5, and the diameter of filtering draft tube is 84 mm, meanwhile the height to diameter ratio is 2.5 too. The material of the inner cylinder is sintered stainless steel powder, the filtration precision achieves 2μm. Tap water, air, activated carbon (catalyst oxidants)are adopted to be the study objects to do research on the filtering and mixing characteristics.1. In the filtering characteristics research work, it focuses on the effect of filtering pressure drop, superficial gas velocity, solid holdup and liquid circulation velocity on filtration flux. The experimental results show that: the filtering effect is good, and clear filtrate can be obtained. The filter have a "self-cleaning" effect, and the filter can achieve dynamic balance. The filtration flux increases with filtering pressure increasing, yet the growth rate of the flux slows while filtering pressure increases. In the meantime, the filtration flux also increases with circulation flow rate increasing, and solid holdup reducing. The filtration flux increases first and then decreases with superficial gas velocity increasing. Nevertheless the impact of solid holdup and superficial gas velocity on the filtration flux is weaker than filtering pressure drop and liquid circulation velocity.2. In the research of mixing characteristics, NaCl solution was chosen as a tracer, and the liquid residence time distribution (RTD) was measured with a step tracing technique. The research shows that:Superficial gas velocity has great impact on the liquid backmixing, the higher the gas velocity, the shorter the mean residence time and the bigger the variance. With the filtration pressure increasing, the liquid backmixing slightly increases.