A study using MEA removes carbon dioxide in fuel gas

• Main Authors: Wen-Feng Lee, 李文峰
• Other Authors: Chu Hsin
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/8536fy

碩士 === 國立成功大學 === 環境工程學系碩博士班 === 90 === The increase in atmospheric carbon dioxide has primarily resulted from the consumption of fossil fuels for energy. The atmospheric CO2 is transparent to visible light but absorbs infrared radiation returning from the earth. Thus, the atmospheric CO2 may alter the radioactive balance of the earth and raise the global temperature. This so-called “greenhouse effect”could dramatically cause global climatic and environmental changes in precipitation, storm patterns, and increases in sea level.Therefore, it is the time to research and develop technologies for reducing CO2 emissions from energy production system that is the largest source of CO2 emissions. This study was set up a bench-scale agitated vessel reactor system to removal CO2 in the simulated fuel gas. In reactor, the stir turning of gas phase is 235 rpm and liquid phase is 200rpm. To measure the absorption rate of CO2 at various operating conditions; followed by using MEA(aq); DEA(aq); MDEA(aq); NH3(aq); NaOH(aq) and mixing amine as the additive and absorbent, respectively, to determine the chemical kinetics data. The result of this study shows the following: 1.The effect of MEA concentration on CO2 absorption rate. It is conducted condition: temperature 50℃, CO2 concentration 15%(V/V), gas flow rate 2~12 L/min and absorbent MEA =10~50% (w/w). The result shows that the absorption rate goes up by increasing the gas flow rate but the amount of changing absorption rate decrease with increasing the gas flow rate. In different concentration of absorbent condition, the absorption rate goes up by increasing the concentration of absorbent, however, the absorption rate is the fast in MEA=30%. It is conducted condition: temperature 50℃, CO2 concentration 5~15%(V/V), gas flow rate 12 L/min and absorbent MEA =10~50% (w/w). The result shows that the more higher CO2 inert concentration the more fast absorption rate, and the condition of absorbent is alike the above-mentioned. 2.The effect of operating temperature on CO2 absorption rate. It is conducted condition: temperature 30~70℃, CO2 concentration 15%(V/V), gas flow rate 12 L/min and absorbent MEA=10~50% (w/w). The result shows that the absorption rate goes up by increasing temperature, and the condition of absorbent is alike the above-mentioned. 3.The effect of NOx and SO2 on CO2 absorption rate. It is conducted condition: temperature 50℃, CO2 concentration 15%(V/V), gas flow rate 12 L/min, entering NOx=300~800 ppm or SO2=500~1500 ppm or NOx =500 ppm + SO2=1000 ppm and absorbent MEA =10~50% (w/w). The result shows that the absorption rate reduces by entering NOx and SO2. 4.The effect of additives CO2 absorption rate It is conducted condition: temperature 50℃, CO2 concentration 15%(V/V), gas flow rate 12 L/min, NOx=500 ppm, SO2=10000 ppm and absorbent MEA/NH3 = 30/1, 30/3, MEA/DEA = 30/10, 30/20, MEA/MDEA = 30/5, 30/10. The result shows that entering NH3 can help to increase absorption rate and compete to NOx, SO2 bad affecting for MEA absorb CO2 and the absorption rate increase with increasing NH3 concentration. When liquid was added with DEA or MDEA, it has a bad affecting for MEA absorbing CO2, and the more concentration the bad absorption rate. 5.The effect of absorbent type on CO2 absorption rate. It is conducted condition: temperature 50℃, CO2 concentration 15%(V/V), gas flow rate 12 L/min, and absorbent concentration NH3=0.57~2.51M; NaOH=1~3M; MEA=1.64~4.91M; DEA=0.98~2.93M; MDEA=0.87~2.62M. The result shows that the absorption rate is NH3>MEA>NaOH>DEA>MDEA. 6.We get the reaction kinetics equation form difference absorbent concentration (MEA=10~50%) absorb difference CO2 concentration (CO2=5~20%). In difference operating temperature (30~50℃), we can get active energy , factor of colliding and reaction constant equation. Ea=32.26 Kj/mol A=2.573*105 7.According to the experimental data, we get an regression equation by using the computer program SAS:The sequence of the effect by these factors is MEA concentration, CO2 inert concentration, operating temperature, flow rate, NOx inert concentration and SO2 inert concentration.