CFD Simulation Of Fluid Flow In Sulfuric Acid Alkylation Reactor

Owing to the complexity of sulfuric acid alkylation reactor, it’s extremely tough and expensive to design an optimized reactor totally by experiment study. Ongoing development of commercial computational fluid dynamics (CFD) software and increasing computer power are continuously improving the conditions for simulation of the turbulent flow structure in reactors. Use of CFD for simulation fluid flow in alkylation reactor can generate useful data to provide design reference.Numerical predictions using standard k-εmodel, Realizable k-εmodel, standard k-ωmodel and SSTk-ωmodel have been performed on an alkylation reactor. The results showed that:these turbulence models obtained similar Np, Nq and flow field but with regard to impeller zone in the reactor these models obtained different turbulence characters. Prediction of k andεof impeller zone in the reactor were obviously distinct.This work presented a comprehensive study of different reactor structures, including the C, D/Td0, LIT, local structure of the reactor, impeller types and d, by numerical simulation using standard k-εmodel. The results showed that:(1) To maintain a larger value of Nq and keep an appropriate turbulence dissipation, the suitable value of C was 0.2T.(2) When D/Td0 decreased to 0.686, Nq was large enough to prevent droplet settlement between tube bundles, and k,ε,γkept a high level which was useful for droplet breakage.(3) In order to obtain a larger level of Nq, k,ε,γand V, L/T=5 was preferable.(4) The enclosing shape of reactor turned to circular truncated cone which was a good choice to increase k,ε,γ, and restricted droplet coalescence. Due to eccentric transition zone of the reactor, Np increased and k,εandγin the hydraulic head increased a lot which was beneficial to droplet breakage and dispersion.(5) Various forms of impellers showed different results under the condition of N=2000rpm. The sequence of Np and Nq was:A315-45>6K5U>A315-30>propeller. The sequence of k,εandγin impeller zone was:A315-45>6K5U>A315-30>propeller.(6) In impeller area of the alkyation reactor. a high axial velocity would prevent droplet settlement and a highεwould restrict droplet coalescence. When d increased from 0.01m to 0.015, axial velocity between tube bundles slightly increased butεdecreased a lot. So d=0.01m would be more appropriate.