Influence of In-Vessel Filtration on the Operating Characteristics of Slurry Bed Reactors
The slurry bed reactor is most widely employed for low temperature Fischer-Tropsch synthesis process,and the in-vessel filtration system is usually applied to continuously separate liquid products from reactions.The influence of in-vessel filtration on the operating characteristics of the slurry bed reactor was experimentally studied from two aspects,i.e.,the variation of gas leakage ratio and average gas holdup in the filtration region under different conditions,and the effect of gas back-flushing on the operating stability of slurry bed.The study reveals that the average gas holdup in the filtration region decreases significantly due to gas leakage from the filters.The filtration differential pressure increases from 8 kPa to 16 kPa,resulting in a corresponding increase in both gas leakage ratio and average gas holdup,but the mean growth value of average gas holdup decreases from 0.0059 to 0.0044.The gas leakage ratio reaches its maximum in the gas-liquid system,resulting in a low average gas holdup ranging from 0.063 to 0.145.When the catalyst particle mass fraction is increased up to 5％,the average gas holdup is increased and ranges from 0.062 to 0.146 due to the decrease in gas leakage ratio.The filter element pore size decreases from 80 μm to 30 μm,leading to a large decrease in gas leakage ratio in the gas-liquid system,along with a mean growth value of average gas holdup increasing from 0.0040 to 0.0049.When adding particles with the mass fraction of 5％,the range of gas leakage ratio is being narrowed,leading to a corresponding decline in the mean growth value of average gas holdup from 0.0018 to 0.0012.Based on the fluctuations of transient bed pressure difference in the filtration region,it is evident that gas back-flushing can significantly disturb the operating stability of the slurry bed.Particularly,the larger the filter element pore size,the stronger the disturbance effect.
slurry bed reactorin-vessel filtrationaverage gas holdupgas leakage ratioback-flushingJohnson screen filter element
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