Numerical Simulation Of The Fixed Bed For Vinyl Acetate Synthesis Via Acetylene Method

Vinyl acetate (VAc) was used to produce vinyl acetate derivatives through its own polymerization or with monomer copolymerization, which was used widely in producing many kinds of chemical products, i.e. polyvinyl acetate (PVAc), polyvinyl alcohol (PVOH), resist printing, size, adhesive, fine-denier vinylon, thin films, vinyl copolymer resin and acetal resin. Therefore, it was regarded as an important organic raw material and vinyl acetate industry had the promising future.In this paper, the process of vinyl acetate vapor method synthesis from acetic acid as well as acetylene and especially the fixed-bed with new heat exchange structure were briefly introduced, against a background of which the two-dimension pseudo homogeneous model was established. Crank-Nicholson difference method was used to solve the 2-D model numerically combining with Matlab to obtain the temperature and concentration distribution in the fixed-bed based on the regressed reaction kinetics of active carbon-zinc acetate catalyst.By comparing with the traditional fixed-bed reactor, the simulation results not only showed that the heat exchange capacity was improved in the new reactor and hence hot point in the reactor was decreased but also indicated that the new reactor had important value of application. The influences of operating conditions, i.e. mass flow rate, input temperature of reactant, wall temperature, the ratio of reactant and the dimension of reactor tube on the maximum temperature and the production rate of the reactor were also discussed in the paper. The simulation results showed the factors mentioned above exerted certain effects on the maximum temperature and the production rate of the reactor, based on which the optimal operating conditions of the fixed-bed were suggested. The simulation results also indicated that the difference method used in the paper had good convergence property. Besides, the established two-dimension pseudo homogeneous model could express the feature of fixed-bed reactor, as a result of which, quantitative analysis according to the different operating conditions could achieve broad application with new structure.