| Recently, with the rapid development of economy and consumption of fossil fuels, the amount of CO2explored into the earth’s atmosphere is increasing, which leads to greenhouse effect intensify and global climate anomaly; meanwhile, excessive emission of NOx (especially in China) causes a lot of environmental problems, such as acid rain and haze weather. CO2emission reduction and NOx removal are desperately needed.Many studies show that the chemical absorption method is one of the most suitable technologies for large-scale CO2capture. In recent years, CO2capture using ionic liquids as absorbent has become a hot research field. Ionic liquids have a lot of advantages, which are suitable for CO2capture by chemical absorption, such as low volatility, stable property and adjustable structure. However, due to the high viscosity of ionic liquids, gas-liquid mass transfer process and absorption rate of CO2in ionic liquids is really slow and the absorption time is quite long, which are the practical application bottlenecks for CO2capture using ionic liquids. Previous research on complex solution for NO removal shows that the complexation rate between NO and complex solution is generally very fast and the complexation reaction is a process controlled by gas-liquid mass transfer. In summary, the key problem to be solved in the two chemical absorption processes is the same:intensification of the gas-liquid mass transfer in order to promote the chemical absorption is the key point of the development of chemical absorption method for decarbonization and denitration.Rotating packed bed (RPB) is a new type of multiphase flow mixing contactor and reactor, which could greatly strengthen the liquid-liquid, gas-liquid mass transfer. The technique has been successfully applied to the chemical separation process and the preparation of nanometer materials. In this paper, RPB, as a gas-liquid reactor, has been successfully applied to CO2capture and NO removal process. The CO2physical absorption and chemical absorption processes in ionic liquids in RPB have been studied and the mass transfer coefficient in RPB has been measured. New promising processes for CO2capture and for NO removal have been proposed. Based on the experimental research and the results of previous studies, a mathematical model for the process of CO2chemical absorption in ionic liquid under high gravity environment has been proposed. The gas-liquid mass transfer intensification mechanism under the high gravity environment has been researched and the operating parameters and equipment size have been optimized based on the model, which could provide support for the pratical application process. The main innovative works of this dissertation are as follows:1. CO2physical absorption process in traditional ionic liquid [Bmim][PF6] was used as a research system and the mass transfer coefficient of this system in RPB was measured. Mass transfer coefficient of this system in a packed column was also measured as a comparison study. The result of this comparison showed that under similar operating conditions, liquid volumetric mass transfer coefficient kL was0.95-3.9×l0-2s-1in RPB, while0.63-1.9×10-3s-1in the packed tower. Compared to traditional packed tower, liquid volumetric mass transfer coefficient in RPB could be increased by more than an order of magnitude and the absoption process has been effectively strengthened by RPB.2. The chemical absorption process of CO2in functional ionic liquid [Choline][Pro] was used as a research system. The CO2removal efficiency and absorbent capacity were investigated under different operating conditions. The results showed that in RPB, it took only0.2second to reach0.2mol CO2/mol IL at293K, indicating that RPB was kinetically favorable to the absorption of CO2in ionic liquid. The absorbent capacity could achieve25Kg CO2/m3IL (using10%mixed gas) and the removal efficiency could maintain over90%. The absorbent capacity could achieve40Kg CO2/m3IL using20%mixed gas. The method shows good prospect for practical application.3. The chemical absorption process of CO2in functional ionic liquid [Choline][Pro] was used as a gas-liquid mass transfer system. A model describing the gas-liquid mass transfer accompanying reversible reaction under high gravity environment was built based on the Higbie’s penetration theory. The analytical expression of CO2concentration in the liquid film with time and depth of penetration was obtained and the mass transfer coefficient in RPB could be further derived. The CO2removal efficiency under different operating conditions in RPB could be predicted and the predicted results were in good agreement with the experimental results. The model revealed that the gas-liquid mass transfer intensification in RPB was achieved by heightening concentration gradient of soluble gas in the liquid film. The effect of the packing radius size on CO2removal efficiency was predicted by this model. Then the absorbent capacity under different operating conditions could be improved by optimizing the packing radius size.4. FeII(EDTA) complexation absorbent was prepared using FeSO4and Na2EDTA crystalline hydrates and the NO removal experiments by complexation reaction in RPB were studied. The effect of high gravity level, gas-liquid flow rate ratio, gas-liquid flow rate, pH value of the complexation absorbent, temperature of the complexation absorbent, inlet gas pressure and NO concentration of the inlet gas on NO removal efficiency were investigated. The experimental results indicated that it was optimal for NO removal when the pH value of the complexation absorbent was7and the high gravity level in RPB was200g. The NO removal efficiency decreased with the increase of the temperature of the absorbent and the gas-liquid volume flow rate, while increased with the increase of the concentration of the absorbent and pressure of the inlet gas. When the concentration of the absorbent was0.04mol/L, the gas-liquid volume flow rate was125:1, the high gravity level in RPB was200g, the NO concentration of the inlet mix gas was1000ppm, the pressure of the inlet gas was0.35MPa and the temperature of the experiment system was298K, the NO removal efficiency reached the highest level95%. |
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