Research On CO₂ Liquefaction And Separation Based On Low Temperature Adsorption Distillation

With the increasingly serious energy crisis and global warming,the issue of carbon emission reduction has attracted worldwide attention.In order to alleviate the fossil energy crisis and global warming,and achieve the strategic goal of "carbon peaking and carbon neutrality",fuel ethanol is widely promoted to replace fossil energy worldwide.As a by-product in ethanol production,carbon dioxide can be used as an important raw material in various industries.It is widely used in the industry,so the value and significance of carbon dioxide recovery are very important.In this paper,the fermentation tail gas of an ethanol production enterprise is used as the raw material gas,and the liquefaction and separation of carbon dioxide is studied by the combined method of low temperature adsorption and rectification.The main contents are as follows:(1)Establish a thermodynamic model for the low-temperature adsorption distillation process for recovering carbon dioxide.Combined with the theory of phase transition thermodynamics and chemical thermodynamics,the thermodynamic model suitable for this process is analyzed.The analysis shows that the Peng-Robinson cubic equation of state conforms to the physical property system of this paper;the model is established by Aspen Plus and the accuracy of the thermodynamic model is verified by comparing the simulation results with the measured data of the distillation process of a certain enterprise.(2)Research on the influence of energy material balance and liquefaction rate.Use Aspen Plus to complete the simulation of each section and the whole process,complete the material balance calculation according to the simulation results,determine the processing volume of raw gas,the actual output and product quality of the main product;determine the input and output material flow and quality of each equipment According to the simulation results,the energy balance calculation was completed,and the energy flow of all equipment was calculated;the influence of raw gas conditions on the unit energy consumption and liquefaction rate was explored.The results show that the raw material gas temperature,pressure and carbon dioxide concentration have a great influence on the unit energy consumption of the process,but have little effect on the carbon dioxide liquefaction rate.Through sensitivity analysis,the reasonable raw gas temperature is 30℃,the raw gas pressure is 100 k Pa,and the carbon dioxide concentration is 95%.Unit energy consumption: 43.7k W/kmol/h,liquefaction rate:91.7%.(3)Comparison of industrial test sampling analysis and simulation results.Using double-headed sampling steel cylinder to sample,send it to the laboratory to determine the composition of raw gas by gas chromatography and compare it with the simulation results;the test analysis results show that the carbon dioxide concentration and other impurity content correspond to the simulation results and reach the food-grade standard,which verifies the simulation results.reliability.