Multiscale Simulation And Optimization Of Ehylene Oxide Fixed-Bed Reactor In Reaction Performance

Ethylene oxide is an important organic raw material and intermediate in the chemical industry, and the demand is huge, as ethylene makes up a large amount of the cost of this production process, the increase of selectivity and yield has significant meaning for this process. In this study, models at catalyst particle scale, fixed-bed reactor scale, and fixed-bed membrane scale were set up for ethylene epoxidation with the software Fluent, in order to explore the optimizating measures of reaction performance.First, in single particle catalyst scale, the reaction performance (temperature distribution, component distribution, selectivity) of different particles with the condition of reaction-internal diffusion was studied, moreover, effects of the particle shape on the flow performance and the reaction performance of the reactor tube were studied. The results show that: (1) with the same geometric volume and the same operation conditions, the effect of different catalyst shapes on the reaction performance of the catalyst particles is very small; (2) among these different catalyst particles, the pressure drop of the reactor tube filled with 7-channel cylinder catalyst particle is the smallest, and its conversion and yield are the highest.In the fixed-bed reactor scale, based on 7-channel cylinder catalyst particle, effects of different operation conditions on the reaction performance of the single reactor tube were obtained; the rationality and feasibility of active temperature control and catalyst grading control were also researched. The results show that:(1) the inlet temperature is not the sensitive factor of the reactor tube, and the wall temperature is the sensitive factor; (2) the main response is more sensitive to the operation pressure, increasing pressure is advantageous to increase the selectivity, the side response is more sensitive to the temperature, increasing temperature can not improve the reaction performance; (3) the inlet concentration of CO2 and ethylene are the sensitive factors of the reactor tube, increasing the ethylene concentration can increase the selectivity and improve the reaction performance, but CO2 can inhibit the reaction, so its concentration should be appropriately controlled; (4) the effect of catalyst activity control is not as good as that of wall temperature control, the measure of active temperature control can not be achieved in practice, and it is not really necessary, so we can take this measure of controlling the wall temperature (control the coolant temperature) to optimize the reaction performance.In the packed-bed membrane reactor scale, the reaction performance such as selectivity, conversion and yield of both fixed-bed reactor and packed-bed membrane reactor were studied under the same operation conditions; then the wall temperatures and the operation pressures of the fixed-bed reactor were changed to make sure that the two reactors have the same selectivity, and the reactor performance (conversion and yield) of the two reactors were compared with each other. The results show that:in comparison with the fixed-bed reactor, (1) with the same operation conditions, the selectivity of the packed-bed membrane reactor is higher, but the conversion and yield is lower; (2) with the same selectivity, the conversion and yield of the packed-bed membrane reactor is higher.