Simulation Calculation Of Syngas Methanation Reactor

Based on the low-temperature and high-activity Ni-based methanation catalyst developed by our group,this paper designs a low-temperature methanation process based on the existing methanation process,which is the industrial application of the catalyst,methanation reactor and The design of the process provides a reference.The mathematical model of the methanation fixed-bed reactor was established.The parameters such as concentration,temperature and pressure of the reactor were simulated by Matlab software.The methanation process model was proposed on the model of reactor.When the composition gas flow rate were 500 kmol/h and its composition（molar fraction）was y_CH4=0.1195,y_CO2=0.1032,y_CO=0.0879,y_H2=0.6498,y_N2=0.0396,the inlet temperatures of the reactors were 553 K,593 K,and 553 K,respectively and the inlet pressures of the reactors were 3 MPa,the cycle ratio was 3.0,and the outlet temperatures of the reactors were 794 K,741 K and 592 K,respectively.The CO conversion at the reactor outlet were 86.58%,96.09%and 99.43%respectively.There are many factors affecting the methanation reaction.From the thermodynamic point of view,the methanation reaction is a strong exothermic,shrinking chemical reaction,Therefore,the reaction should be carried out under suitable conditions such as temperature and pressure.The flow rate and ratio of feed should also be controlled within a reasonable range to ensure stable,safe and efficient operation.For this,the effects of feed gas flow rate,feed gas H₂O-syngas ratio,feed gas hydrogen-carbon ratio,inlet temperature,inlet pressure and cycle ratio on methanation reaction were investigated.The results show that in the certain range of feed flow,as the flow rate of feed increased,the hot spot position of the catalytic bed gradually moved backward and the reactor catalytic bed temperature,conversion of CO and outlet CH₄ concentration remain basically unchanged.As the feed flow further increased,the reactor bed temperature was significantly reduced,and the conversion of CO and the outlet CH₄ concentration were both reduced.The water-gas ratio of feed increases,the hot spot position gradually moves back,the temperature decreases significantly,the CH₄ concentration at the outlet of the reactor decreases,and the conversion of CO increases.The ratio of hydrogen to carbon in the feed gas increased,the hot spot position shifted slightly,the temperature increased slightly,the conversion of CO increased slightly,and the outlet CH₄ concentration increased slightly.As the reactor inlet temperature increased,the methanation reactor hot spot position moved forward,the hot spot temperature increased,the outlet conversion of CO is lowered,and the outlet CH₄ concentration decreased.As the inlet pressure of the reactor increased,the hot spot of the methanation reactor moved forward and the hot spot temperature increased,but the amplitude become smaller and smaller,the conversion of CO increased,the CH₄ concentration of the outlet gas increased.As the cycle ratio increased,the hot spot position moved backward,the hot spot temperature decreased,the conversion of CO increased and the outlet CH₄ concentration increased.By optimizing the process conditions,the efficiency and stability of the methanation system were improved,which provided a reference for the independent research and development of the synthesis gas for methane technology in China.