Study On Carbon Monoxide Production Via Methane Carbon Dioxide Auto Thermal Reforming Process

Carbon monoxide,usually produced by hydrocarbon reforming,is an important raw material for hydro-formylation and synthesis of dimethyl carbonate.Methane carbon dioxide reforming converts CH4 and CO2 into syngas,which can not only produce carbon monoxide with high selectivity,but also make full use of carbon resources and reduce greenhouse gas emissions.In this paper,based on Ni-based structured catalyst,the kinetic tests of methane carbon dioxide reforming have been carried out,and the macroscopic kinetics model of the reforming reaction has been established.Then,by means of computational fluid dynamics simulation,the reaction flow in the reactor has been simulated using the method of gradual convergence,and the flow,heat transfer as well as mass transfer rules in the reaction process have been investigated.On this basis,the field distribution data obtained by quantitative analysis have been used to evaluate the reaction results.Finally,the whole process has been simulated with Aspen Plus software to optimize the reaction conditions,and the influence of hydrogen recirculation on the reaction process has been investigated.The main research work and conclusions in the present study are as follows:(1)The power function rate equation was selected to establish the kinetic model of methane carbon dioxide reforming on Ni-based structured catalyst,and the parameter estimation algorithms were improved.The optimization algorithms combining simulated annealing method and Marquardt method was adopted.The algorithms have stronger adaptability and more stability.The statistical tests and error analysis on the established kinetic model of methane carbon dioxide reforming show that the kinetic model is well established and the estimated parameters are reliable.(2)The design of a new type of reactor for methane carbon dioxide reforming into CO was proposed,and the influence of turbulence model and nozzle diameter on the combustion reaction process was discussed.By comparing the performance of different turbulence models in a cold propane jet,a Realizable k-s model was adopted to simulate the flow field.The variation rules of methane combustion in the reactor with different nozzle radius were simulated respectively,and it was found that the nozzle with r=5mm was more conducive to the uniform mixing of fuel gas and air,which led to more effective combustion,an appropriate flame length,abundant methane flow and uniform downstream temperature distribution.A full field numerical simulation of methane-carbon dioxide auto-thermally reforming reactor was carried out by means of gradual convergence.O2 had been fully consumed at the entrance of reforming stage,and the reaction temperature,speed and concentration of CH4,CO2 and other components were evenly distributed,basically approaching a plug flow,which provides a more appropriate reaction condition for catalytic reforming.Under the simulation conditions,the conversion of methane reached 98.10%and the selectivity of carbon monoxide was 69.79%.(3)Studies on the whole process simulation of methane carbon dioxide reforming were performed using Aspen Plus software.The flow data in each unit and process were obtained,and the effects of feed ratio,steam feed and hydrogen recirculation on reaction conversion and selectivity were investigated.On this basis the process conditions and energy circulation were optimized.It was found that the temperature of reforming reactions was mainly controlled by varying O2/CH4,and the optimal feed ratio of CH4/O2/CO2 was 4/2/1.The addition of steam can promote the proceeding of carbon elimination and inhibit the catalyst activity decline caused by carbon deposition.(4)CFD simulation was used to investigate the influence of hydrogen recirculation on the combustion and reaction results of methane in the reactor.The hydrogen recirculation accelerates the methane combustion,not only promotes the combustion of methane in the air,improves the ignition performance and the thermal efficiency of methane carbon dioxide auto thermal reforming process,but also retards the coking reactions and raises the selectivity of the target product-carbon monoxide.With hydrogen recirculation,the selectivity of carbon monoxide increased from 69.79%to 80.11%.