Mathematical Simulation Of High-Temperature Adiabatic Fix-Bed Process Of Syngas Methanation

With the development of economy and environmental policy,the demand of natural gas is expanding fast in China.Considering China’s resource endowment concept of the "rich coal,poor gas",it’s beneficial for both adjusting and optimizing the energy structure that if the coal can be easily converted into natural gas.In practice,methanation are the key steps in coal utilizing to synthetic natural gas(CSNG).The core technology of the methanation processes is the development of catalyst and the design of reactor and process with the specified catalyst.The dissertation is focused on the design and simulation of the methanation-process with the AM-830 high-temperature-resistant catalyst.Three optional methanation-process schemes(Scheme 1,Scheme 2 and Scheme 3)were designed on the basis of researching and analysing the existing high-temperature adiabatic fix-bed technologies.Namely,Scheme 1 was based on the process of Davy technology,Scheme 2 and Scheme 3 were both based on the processes of Tops(?)e technology.Firstly,the mathematical model for the methanantion process was established,which consists of adiabatic fix-bed reactor model,identification of the related physical parameters,the compressor model and flow-mix model.To valid of the established model,the simulation results were compared with the data of a CSNG factory a CSNG factory and the result shows that the model is highly-confident.Furthermore,the provided three schemes were simulated in MATLAB and two different operation conditions were considered for each scheme.To save the energy consumption,the split ratio was adjusted to determine the minimum recycle ratio with the constraint of outlet temperatures of the main reactors.In addition,the work consumption of compressor,catalyst consumption,natural gas profit and steam profit for each scheme were investigated under the outlet temperature of main reactor as 610℃,620℃...700℃.By analyzing results of the simulation,the main conclusions are as follows:(1)The work consumption of the compressor can decrease by reasonably adjusting the recycle ratio and split ratio with the constraint of the outlet temperature for the main reactors;(2)It is profitable for the process with suitable high temperature and feedstock condition;(3)Scheme 1 has evident merit on reducing compression consumption,but Scheme 3 has obvious advantage on total profit;(4)The effects of the recycle ratio on the work consumption of compressor and steam profit are opposite;(5)The work consumption of the compressor is less than the profit of the steam,which indicates that it is necessary to optimize the steam profit in future work.