Trickle Bed Reactor's Particle Scale Simulation And Structural Optimization

Trickle bed reactors(TBRs)are widely-applied gas-liquid-solid multiphase catalysis devices in which gas and liquid flow co-currently through a fixed bed filled with catalyst particles.The multiphase flow behavior in TBRs is extremely complex,with acting force between different phase at different directions.Despite TBRs have a long history of industrial application,the design and scaling-up of TBRs still tend to be challenging.The simulation and optimization methods of TBRs need to be developed and improved.On the basis of the existing research,this paper analyzed a laboratorial scale high liquid flux trickle bed reactor's fluid flow,mass transfer and chemical reaction in particle scale.The multiphase flow's computational fluid dynamics(CFD)model were established.The fluid flow and mass transfer simulation were carried by Eulerian model with the help of finite volume method.2D numerical simulations of TBR's mass transfer in bubble flow regime have been carried out,in which searching-interpolation algorithm and interior mass transfer date generated by pre-simulation were embedded in TBR's macro multiphase flow model.The predicted Pe numbers and liquid outlet's tracer concentration curves were fitting well with the experiment results.The predicted Pe number's averaged relative error is 12.2%.Next,the structure optimization of a micro TRB reactor was conducted with the help of moving asymptotes method.The resulting optimized velocity field,reactant concentration and permeability distribution in the micro bed were generated and the catalytic conversion efficiency of the micro reactor was improved.At the end,the topologic optimization of TBR catalysis particle structure was conducted.An objective function based on SIMP(Solid Isotropic Material with Penalization)method was designed.The SNOPT(Sparse Nonlinear Optimization Algorithm)were applied to achieve trickle bed reactor catalyst particle's topological optimized geometric structure and catalyst component distribution.A series of numerical optimization under different reaction rate constants,reaction orders and reactant diffusion coefficients were conducted.The comparison of catalytic performance simulation results before and after optimization were made.Optimization results show that the onion rings or tree-like hole structures were the favored optimization results.Fixing particle shape,the catalyst component distribution optimization results show that it's better to deploy catalytic component under particles' lateral surface.The geometric topologic optimization is effective when the reaction is fast or reactant diffusion coefficient in particle is low.While the reaction rate is slow or diffusion coefficient is high,the topologic optimization for catalytic component distribution is applicable.Regarding the TBRs multiphase simulation and particle topological optimization results,the TBRs' particle scale simulation and optimization routine could be considered effective.The result could serve as a reference in future TBRs design and optimization...