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• Main Authors: Chu-Yun Cheng, 鄭筑勻
• Other Authors: Cheng-Tung Chou
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/4jhbxg

碩士 === 國立中央大學 === 化學工程與材料工程學系 === 107 === In order to reduce carbon dioxide emissions, we use pressure swing adsorption process to capture carbon dioxide from flue gas in a thermal power plan . Pressure swing adsorption (PSA) is a cyclic process to separate gas mixtures based on the difference of adsorption capacity of each component on adsorbent. Pressure swing adsorption plays an important role in the separation of gas mixtures with its low energy consumption, low investment, and simple operation. This study aims to capture carbon dioxide from flue gas of 1kW coal-fired and gas-fired power plant by PSA process for bottom product CO2 purity 85% and top product N2 purity 90%. To validate the accuracy of PSA program, the extended Langmuir-Freundlich equation was adopted to fit isotherm to describe the adsorption equilibrium of adsorbent. Next, we used linear driving force (LDF) model and compared the results of breakthrough curves and desorption curves between experiments and simulation to verify the accuracy of mass transfer coefficient kLDF value. We further verified the simulation with the 100 hours steady state experiment of 3-bed 9-step PSA process . Next, this study could be divided into 2 parts and both of them used EIKME 13X zeolite as adorbent. For the first part of study, a 3-bed 9-step pressure swing adsorption (PSA) process for flue gas after desulphurization and water removal (13.5 % CO2, 86.5% N2) of subcritical 1kW- coal-fired power plant was designed. After simulation, we obtained a bottom product CO2 purity at 85.96% with 82.09% recovery, and a top product N2 purity at 97.61 % with 92.05% recovery while at feed flow rate 60 L/min (NTP), feed pressure 3 atm, vacuum pressure 0.05 atm, feed temperature 303.14 K, adsorption time 430 s, cocurrent time 80 s, vacuum time 300 s, and pressurization equilibrium time 50 s. The mechanical energy consumption was estimated to be 1.06-1.24 GJ/tonne-CO2. In order to find the optimal operating conditions, we combined the results of 1kW-power plant flue gas PSA process with design of experiments (DOE) method. After analysis, we obtained a bottom product CO2 purity at 89.20% with 88.20% recovery, and a top product N2 purity at 98.49 % with 93.56 % recovery while at feed pressure 3.66 atm, vacuum pressure 0.05 atm, cocurrent depressurization 0.3 atm , surrounding temperature 323.14 K, step 1/4/7 time 94 s, step 2/5/8 time 350 s, bed length 46cm as the optimal results. The mechanical energy consumption was estimated to be 1.17-1.41 GJ/tonne-CO2. For the second part of study, we use same process for capturing CO2 from flue gas of a power plant with natural gas as fuel. The composition of flue gas was assumed 5% CO2 and 95% N2 .After simulation, we obtained a bottom product CO2 purity at 86.31 % with 65.50 % recovery , and a top product N2 purity at 98.36% with 96.83 % recovery while at feed flow rate 132.59 L/min (NTP), feed pressure 4 atm, vacuum pressure 0.05 atm, cocurrent depressurization pressure 0.2 atm, feed temperature 303.14 K, adsorption time 620 s, cocurrent time 120 s, vacuum time 450 s, and pressurization equilibrium time 50 s. The mechanical energy consumption was estimated to be 4.03-4.93 GJ/tonne-CO2.