Fundamental Research On Catalytic Hydrogenation Of Poly Alpha Olefin Intensified By Microbubble Generated By HMG

With the implementation of Carbon Peaking and Carbon Neutrality,energy saving,carbon reduction,quality and efficiency improvement have become the urgent demands for the development of petrochemical industry.Compared with the classical hydrogenation in trickle bed reactor,liquid phase hydrogenation process can greatly reduce the energy consumption by eliminating the recycle gas compressor and improving the utilization efficiency of catalyst.The liquid phase hydrogenation technology based on microbubbles can further increase the amount of hydrogen carried in liquid phase,which is of great significance to improve the reaction efficiency of liquid phase hydrogenation and promote the high-quality development of industries such as catalytic hydrogenation of petrochemical products.In this dissertation,aiming to liquid phase hydrogenation technology based on microbubbles,the innovative research work was carried out in three aspects:generation and modulation of microbubbles in high-gravity（Hi Gee）environment,transfer behavior of microbubble swarm,and hydrogenation reaction performance.It was the first time to analyze the energy transfer rule during the generation of microbubbles under the Hi Gee environment,and establish the model of energy dissipation rate of the Hi Gee microbubble generator（HMG）.The flexible modulation and size prediction of microbubbles were realized,and the mechanism of HMG enhancing gas-liquid dispersion was revealed.The flow process of microbubble swarm was obtained,and the mechanism of interaction between reactor bed and microbubble swarm was revealed.The intensified principle of gas-liquid process by HMG was described.The pilot hydrogenation process of poly alpha olefin（PAO）in fixed bed reactor enhanced by microbubble generated by HMG was studied.A new process for liquid phase catalytic hydrogenation intensified by microbubbles generated by HMG was formed,providing a scientific basis for the design of HMG and the industrial application of new processes The main research contents of this dissertation are as follows:1.Construction and validation of model of energy dissipation rate of HMG.The energy transfer process in the Hi Gee environment was analyzed.The energy input by the motor was first converted into mechanical energy of rotor rotation,and then drove the internal fluid to rotate at high rotational speed,converting the energy into the turbulent kinetic energy of the liquid.Finally,the energy was converted into the surface energy of the bubble through the turbulent vortex,so as to realize the dispersion process of the gas phase and form the microbubble swarm.The model of energy dissipation rate of HMG was established.The experimental and calculated values of the energy dissipation rate were compared and the error was±15%.The energy dissipation rate of the designed HMG was 0～1500 W/kg,which is higher than that of stirring tank and bubble column.Meanwhile,it could achieve flexible modulation of microbubble size in a larger range by rotational speed.2.Size characteristics and modulation mechanism of microbubble generated by HMG.Based on the established model of energy dissipation rate,the prediction model of the characteristic size of microbubbles in HMG was further developed.The results showed that the error between the experimental and calculated values was±10%.The diameter of microbubbles mostly ranged from 20 to 300μm.The size distribution of microbubbles generated by HMG satisfied the lognormal distribution,and the experiment showed that the rotational speed can significantly affect the size distribution and characteristic size of microbubbles:the higher the rotational speed,the narrower the size distribution of bubbles,and the smaller the size of microbubbles.The mechanism of microbubble generated by HMG was proposed:synergistic microbubble generation mechanism of micro-nano structured packing crushing and turbulent vortex crushing.The micro-nano structured packing performed the coarse dispersion process for the gas phase and then the turbulent vortex realized the fine dispersion process.The performance of different bubble generators was compared,and it was found that HMG can achieve flexible modulation of characteristic size and size distribution of microbubble by rotational speed at a large gas-liquid volume flow rate（G/L）.3.Flow behavior of the microbubble swarm and its regularity of mass transfer in catalyst bed.Hi Gee microbubble cold-model experimental system with hundred-ton capacity for hydrogenation was built,and a microbubble size measurement and flow analysis software with independent intellectual property rights was developed.Compared with the macrobubbles,microbubbles had more uniform gas phase distribution,slower velocity,and longer residence time,which improved the gas-liquid contact time.The characteristic size of the microbubbles in the catalyst bed was analyzed to find that the microbubbles coalesced to a certain extent after passing through the catalyst bed,and the outlet d₃₂increased by 2.7%to43.7%compared to the inlet d₃₂.As the rotational speed of the HMG increased,the size of the microbubbles was smaller,and it was more difficult for the microbubbles to coalesce.Based on experimental data,the correlation equation was established as follows:(d₃₂)_o/(d₃₂)_i=1.797β^-0.1262Re_L^-0.0872Re_G^0.0732ε_b^0.0378（R²=0.91）The gas holdup of catalyst bed was measured.It was found that the gas holdup increased with the increment of the rotational speed of the HMG and G/L.The effective interface area of the reactor bed was further analyzed,ranging from 2000 to 6000 m^-1,which was much higher than that of the packed bed.This result demonstrated the excellent performance of the HMG in the process intensification of gas-liquid mass transfer.4.Study on PAO hydrorefining enhanced by microbubbles generated by HMG.Cooperated with enterprises,a pilot experimental setup of PAO hydrogenation in fixed bed reactor enhanced by HMG was built to study the effects of different operating conditions on the aromatic content in PAO 4 products.It was found that the aromatic content decreased with the increment of rotational speed of the HMG.The aromatic content decreased from 50μg/g to 31.08μg/g and 15.38μg/g,respectively,when the rotational speed increased from 0 r/min to 840 r/min and 1624 r/min.When the hydrogen pressure reduced from 4 MPa to 3 MPa,the aromatic content did not change significantly.Besides,the aromatic content of the product increased from 27.26μg/g to 57.41μg/g when the liquid hourly space velocity（LHSV）increased from 0.2 h^-1to 0.4 h^-1.The macrokinetic model for PAO 4 hydrorefining enhanced by microbubbles generated by HMG was established as follow:-（dC_A）/（dt）=74365exp（-44770/（RT））P^0.84（H/O）^0.13C_A^1.54β^0.40The error between the calculated and experimental values was±20%.It can be used to guide the design of reactor in industrial application...