Carbon Dioxide Capture Coupled With Green Hydrogen Synthesis Of Methanol System Integration And Techno-economic Evaluation

The efficient conversion and utilization of CO₂ is of great strategic significance to alleviate the energy crisis,change the industrial structure and achieve the goal of"carbon peak and carbon neutrality".Combining CO₂ capture with renewable electric power electrolysis H₂ to synthesize methanol can effectively solve the problems of peak absorption of renewable energy and the stability of power grid connection,providing a direction for the development of large-scale long-term liquid energy storage system,which not only promotes the clean and green transformation of energy system,but also makes an important contribution to carbon emission reduction.In this paper,the process models of four carbon capture technologies are established and the simulation results are verified.On this basis,four carbon capture technologies were evaluated by energy consumption,investment,cost and other evaluation methods.The results showed that compared with the traditional MEA method,the energy consumption of PCS,DMC and GMS was reduced by 29.83%,24.33%and 40.33%respectively.Compared with MEA,the TCI of PCS,DMC and GMS processes increased by 1.4%,2.8%and 3.8%,respectively.The CO₂ capture costs of PCS,DMC,MEA and GMS were 272.8,292.6,322.7 and 376.4 CNY/t-CO₂,respectively.According to the carbon emission analysis,GMS technology has the lowest carbon emission,which is 0.18 t-CO₂/t-CO₂.According to the results of technical and economic analysis,PCS technology has the greatest potential in energy consumption and economy.The mathematical models of two methanol synthesis processes（direct hydrogenation and indirect hydrogenation）were established,and the energy integration and optimization design of the processes were carried out.Finally,the technical and economic analysis was carried out.The results showed that the unit methanol energy consumption of CTM_Ⅰand CTM_Ⅱprocesses were 2.04 GJ/t-CH₃OH and 4.53 GJ/t-CH₃OH,respectively.The utilization rates of carbon and hydrogen in CTM_Ⅰprocess are 95.96%and 64.42%,respectively.The utilization rates of carbon and hydrogen in CTM_Ⅱprocess are 98.95%and 98.63%,respectively,which are both higher than those in CTM_Ⅰprocess.Through technical and economic analysis,the TPC of CTM_Ⅰand CTM_Ⅱprocesses is 4204 and 2572 CNY/t-CH₃OH,and the net present value is-19.53×10⁹ CNY and-8.42×10⁹ CNY.The carbon emissions of CTM_Ⅰand CTM_Ⅱprocesses were 0.37 and 0.18 t-CO₂/t-CH₃OH,respectively,and both achieved net CO₂ emission reduction,but the emission reduction effect of CTM_Ⅱprocess was better and the impact on the environment was less.Comprehensive analysis shows that the technical and economic performance of CTM_Ⅱprocess is the best.A system integrated process for hydrogenation of carbon dioxide to methanol was established and compared with three coal processes.The results showed that the energy efficiency of CCt M process was improved by 32.87%compared with that of CTM process,and the total production cost of CCt M process was 2572 yuan/ton,which increased by 35.58%compared with traditional CTM process.When H₂ price is lower than 13.6 CNY/kg and carbon tax is higher than 223.3 CNY/t-CO₂,CCt M process products can compete with traditional coal-to-methanol price.The integrated process is designed to provide a low carbonization and clean way to synthesize methanol.