A liquid-liquid cyclone reactor(LLCR)was designed to achieve mixing-reaction-separation integration during isobutane alkylation catalyzed by ionic liquids.However,studies of the droplets deformation and breakage in th...A liquid-liquid cyclone reactor(LLCR)was designed to achieve mixing-reaction-separation integration during isobutane alkylation catalyzed by ionic liquids.However,studies of the droplets deformation and breakage in the kind of reactors are lacking.In this work,the research studied the velocity distribution,pressure field,and turbulent field to investigate the flow pattern and the main energy loss location in the LLCR through the computational fluid dynamics(CFD)method.The simulation results were verified by experiemnts to prove the correctness of the model.Then the deformation and breakage process of droplets,and the influencing factors of droplets breakage were studied by remodeling which was based on the tangential velocity distribution result of the three dimensional model.The three dimensional simulation results clearly showed that the pressure of the LLCR was mainly concentrated in the cone section and fluid turbulent motion was the most intense near the lateral wall.The reconstruct the results of the two dimensional model clearly showed that the deformation and breakage location of droplets were mainly occurred in the velocity boundary layer,while it was difficult to break in the mainstream region.In addition,low surface tension and high Weber number had a positive effect on droplet breakage.展开更多
The microstructure and properties of the coke samples collected from 4 different wall regions of the cyclone in the reactor of a residue fluid catalytic cracking unit(RFCCU) were analyzed by using the scanning-electro...The microstructure and properties of the coke samples collected from 4 different wall regions of the cyclone in the reactor of a residue fluid catalytic cracking unit(RFCCU) were analyzed by using the scanning-electron microscope(SEM), and the possible coke formation processes were investigated as well. The results showed that some of the heavy nonvolatile oil droplets entrained in the flowing oil and gas mixture could possibly deposit or collide on the walls by gravity settling or turbulence diffusion, and then were gradually carbonized into solid coke by condensing and polymerization along with dehydrogenation. Meanwhile some of fine catalyst particles also built up and integrated into the solid coke. The coke can be classified into two types, namely, the hard coke and the soft coke, according to its property, composition and microstructure. The soft coke is formed in the oil and gas mixture's stagnant region where the oil droplets and catalyst particles are freely settled on the wall. The soft coke appears to be loose and contains lots of large catalyst particles. However, the hard coke is formed in the oil and gas mixture's flowing region where the oil droplets and catalyst particles diffuse towards the wall. This kind of coke is nonporous and very hard, which contains a few fine catalyst particles. Therefore, it is clear that the oil and gas mixture not only carries the oil droplets and catalyst particles, but also has the effects on their deposition on the wall, which can influence the composition and characteristics of deposited coke.展开更多
基金financial support of the Natural Science Foundation of China(21890763)National Science and Technology Innovation Leading Talents Project of National Ten Thousand People Plan。
文摘A liquid-liquid cyclone reactor(LLCR)was designed to achieve mixing-reaction-separation integration during isobutane alkylation catalyzed by ionic liquids.However,studies of the droplets deformation and breakage in the kind of reactors are lacking.In this work,the research studied the velocity distribution,pressure field,and turbulent field to investigate the flow pattern and the main energy loss location in the LLCR through the computational fluid dynamics(CFD)method.The simulation results were verified by experiemnts to prove the correctness of the model.Then the deformation and breakage process of droplets,and the influencing factors of droplets breakage were studied by remodeling which was based on the tangential velocity distribution result of the three dimensional model.The three dimensional simulation results clearly showed that the pressure of the LLCR was mainly concentrated in the cone section and fluid turbulent motion was the most intense near the lateral wall.The reconstruct the results of the two dimensional model clearly showed that the deformation and breakage location of droplets were mainly occurred in the velocity boundary layer,while it was difficult to break in the mainstream region.In addition,low surface tension and high Weber number had a positive effect on droplet breakage.
基金financial support from the National Natural Science Foundation of China (No. 21176250, No. 21566038)
文摘The microstructure and properties of the coke samples collected from 4 different wall regions of the cyclone in the reactor of a residue fluid catalytic cracking unit(RFCCU) were analyzed by using the scanning-electron microscope(SEM), and the possible coke formation processes were investigated as well. The results showed that some of the heavy nonvolatile oil droplets entrained in the flowing oil and gas mixture could possibly deposit or collide on the walls by gravity settling or turbulence diffusion, and then were gradually carbonized into solid coke by condensing and polymerization along with dehydrogenation. Meanwhile some of fine catalyst particles also built up and integrated into the solid coke. The coke can be classified into two types, namely, the hard coke and the soft coke, according to its property, composition and microstructure. The soft coke is formed in the oil and gas mixture's stagnant region where the oil droplets and catalyst particles are freely settled on the wall. The soft coke appears to be loose and contains lots of large catalyst particles. However, the hard coke is formed in the oil and gas mixture's flowing region where the oil droplets and catalyst particles diffuse towards the wall. This kind of coke is nonporous and very hard, which contains a few fine catalyst particles. Therefore, it is clear that the oil and gas mixture not only carries the oil droplets and catalyst particles, but also has the effects on their deposition on the wall, which can influence the composition and characteristics of deposited coke.
