Fluid Dynamic Study Of Bubble Column Reactor With Packing Internals

Coalescence and backmixing of bubbles in bubble column reactors without internals are serious,which is unable to meet production requirements.Using internals can significantly enhance the gas-liquid mass and heat transfer in bubble column.However,to date there is neither quantitative study on fluid dynamic characteristics of bubble column reactors with different packing,nor any report of correlations between bubble size,gas holdup and gas-liquid surface area in literature.A quantitative study on fluid dynamic characteristics of bubble column reactors with packing internals have been performed in this study through a series of cold-flow model tests,which can provide bases for the design and scale-up study of gas-liquid bubble column reactors.First the fluid dynamic behaviors of bubbles in bubble column reactor without internals were studied using single orifice plate and multiple orifice plate.The initial shape of bubbles was flat in a bubble column with a single orifice,where the bubble coalescence and breakage was serious.When multiple orifice plate was used,the bubble size was the smallest with the pore size of 1mm and pores of 16.However,the bubble dispersion was still bad and the bubbles were still large,which demonstrates the necessity of internals to enhance the gas-liquid contact in column reactors.On this basis the fluid dynamic characteristics of bubble column reactors with bulk packings were studied.The results showed that the ?10 ? ring and ?25 Pall ring were the best in cutting bubbles in their types respectively.The Sauter mean diameter under ?25 Pall ring was smaller,however,more bubbles are trapped in the ? ring layer,which leaded to higher gas holdup;the gas-liquid specific surface area under ?25 Pall ring was greater.The correlation of bubble diameter,gas holdup and gas-liquid specific surface area under Pall ring was constructed.Further the fluid dynamic characteristics of bubble column reactors with structural packings were studied.500Y and 500BX were the best in cutting bubbles in their types respectively.The Sauter mean diameter under 500BX was smaller,however,the gas holdup under 500Y was higher so that the gas-liquid specific surface area under500Y was greater.The correlation of bubble diameter,gas holdup and gas-liquid specific surface area under 500Y and 5 00BX were constructed.The mass transfer parameters under ?25 Pall ring,500Y and 500BX were studied.The results showed that the gas-liquid specific surface area and volumetric mass transfer coefficient of 500Y were the largest,which was best to enhance bubble column gas-liquid mass transfer.