dc.description.abstract | In 2021, the government plans to increase the proportion of gas-fired power generation to 50%. Compared to coal-fired power generation, Gas-fired power generation can significantly reduce a lot of air pollution emissions. Government plans energy policy to reduce air pollution and to improve domestic air quality. It wishes to adjust the power structure to low-carbon natural gas power generation accounted for 50% , to reduce the proportion of coal-fired power generation to 30%, and renewable energy power generation will reach by 20% in 2025.Therefore, the carbon dioxide emitted from natural gas power plant has gradually received attention.
In order to mitigate the effects of global warming and reduce emissions, we use pressure swing adsorption process to capture carbon dioxide from flue gas in a natural gas power plant. Among the methods for carbon dioxide capturing, pressure swing adsorption (PSA) is a cyclic process to separate gas mixtures based on the difference of adsorption capacity of each component on adsorbent, and based on the properties of adsorption at high pressure and desorption at low pressure, PSA uses these characteristics to achieve the target of gas separation, and pressure swing adsorption process (PSA) has obtained more attention, which is characterized by advantages such as low energy consumption, low investment, and simple operation.
This work presents a study for capturing carbon dioxide from simulate dry flue gas (5% CO2 / 95% N2) emitted from a natural gas power plant using UOP 13X as adsorbent.The breakthrough and desorption curves were discussed by changing different feed pressure and temperature,and results were used to conduct the design of experiment of dual-bed PSA process.
Then, the simulation is verified with experiments of a single-bed PSA process.A two stage PSA process is studied to capture CO2 from flue gas of natural gas power plant.The first stage 2-bed 6-step PSA process is used with adsorption, pressure equalization, cocurrent depressurization and countercurrent depressurization steps and the second stage 1-bed 3-step PSA process is used with adsorption, cocurrent depressurization and vacuum steps to separate flue gas with simulation.
In order to find the optimal operating conditions, this study combined the simulation of the first-stage 2-bed 6-step PSA process with design of experiments (DOE) method. Parameter study was implemented to obtain a series of optimized settings of operating variables by investigating the effects of feed pressure, feed temperature, vacuum pressure, pressurization/ countercurrent depressurization time, adsorption/ cocurrent depressurization time. After simulation analysis, the bottom product CO2 purity is 45.35 % with 93.32 % recovery while at feed pressure 3.45 atm, feed temperature 338K, vacuum pressure 0.15 atm, step 1/4 time 20 s, and step 3/6 time 30 s as the optimal results. The mechanical energy consumption was estimated to be 5.31 GJ/t-CO2. Then the purity of carbon dioxide obtained from the second-stage 1-bed 3-step PSA process. The bottom product CO2 purity is 94.83 % with 95.20 % recovery, which makes a total recovery of 88.84% .The energy of the second stage PSA is 1.23 GJ/t-CO2, which makes a total energy consumption of 6.81% | en_US |