Research On Stripping In Cold Flow Packing Stripper Of FCC Unit

The research on fluidization of FCC stripper using cascade rings as internal instead of baffles or nothing was conducted inФ90×1000mm transparent plexiglas model by hydrogen tracing. Based on stabile gas and catalyst circulations, the effects of fluidized superficial velocity, catalyst flux, catalyst loading etc. on stripping efficiency were investigated by hydrogen tracer. Fluiding behavior in stripper whose internal was packing or nothing was studied by impuled hydrogen tracing.In continuous hydrogen trace way, nonlinear character of pulsant times serials of hydrogen ratio and concentration of hydrogen distributing rules along axes and radial were analyzed. Expand rate and pressure of beds were also studied.One dimension mass transfer mathematic model of packings stripper was established according to hydrogen distribution, two phase theory of bubbling fluidized bed, some suggestion, and solved by least-square via computer programming.The results of hydrogen tracing showed that stripping efficiency of packing stripper was better than stripper with nothing as internal, numerical value increased about 4%~7% in the same condition. Stripping efficiency increases with fluidized superficial velocity increasing, catalyst flux and loading decreasing, particle diameter increasing. Comparing with stripper with nothing as internal,Gas phase backmixing in packing stripper was reduced,gas phase residence time decreased.The largest Lyapunov exponent of concentration pulsant times serials of hydrogen was all positive number in packing stripper, average exponent emanative ratio is between 0.2~0.3,which is a chaos system.Concentration of hydrogen tracer decreases gradually with descendding along axis, radial concentration was almost identical because of violent mixture. Utilized space was corresponded to stripper with nothing as internal,gas flowing resistance was enhanced. The calculated values by mass transfer model were consistent with experimental values,and semi-experienced exponent relating formula of hydrogen tracer distribution along packing stripper axis was obtained.