Study On Hydrodynamic Characteristics Of Oxidative Dehydrogenation Of Butane To Butadiene

Butadiene is an important petrochemical raw materials that supports the development of synthetic rubber and some other industries.With the deterioration of raw materials of ethylene cracking,the process of oxidative dehydrogenation of butane attract public attention again.Due to the high pressure drop of the reactor and the atmospheric pressure characteristics of the traditional axial fixed bed,the production scale is limited.Radial flow reactor has low pressure drop,large circulation area and is easier to achieve large-scale production of butadiene.As the complexity of the law of the flow field,it has an important significance to study the law of the fluid and the reaction characteristic.According to the performance of the catalyst,we design the appropriate size of the reactor with the goal of 10 million tons/year of butadiene.We use the Fluent software to simulate the flow field and verify the model rationality.The flow and density could not cause a significant impact on the fluid distribution,so we could use the inert media in the simulation process instead of raw materials.The comparison of the velocity and pressure field analysis of the four types of the radial flow reactor provide a guidance and reference for the subsequent optimization work.Secondly,the optimization of the structure of the π-type flow and z-type flow type reactors is discussed separately.The main factors influencing the uniformity of π-type reactor are the cross-sectional area ratio of center pipe to annular channel and the ratio of height to diameter.The best value for cross-sectional area ratio is between 1/3 and 1/2;the smaller ratio of height to diameter is beneficial to the uniformity of the flow field.The diameter of the center pipe is recommended to take the value of 1.5m;the pipe porosity has little effect on the uniformity ofπ-flow type reactor.The optimization method for π-flow type reactor could not apply to z-flow type reactor.But a reasonable design of the guiding cone is a better choice.We can also improve the uniformity by design a variable porosity distribution for the perforated plate to achieve our goal.Finally,the kinetic model of oxidative dehydrogenation of butane and the cold state were coupled to simulate the concentration field distritution in the reactor with different degree of uniformity.Through comparison and analysis,it was found that the uniformity had little effect on the conversion rate of the reaction and the selectivity of the product.