Based on the analysis of flow characteristics of the FCC riser feedstock injection zone, two novel feedstock injection structures are put forward. By investigating three flow parameters in the feedstock injection zone...Based on the analysis of flow characteristics of the FCC riser feedstock injection zone, two novel feedstock injection structures are put forward. By investigating three flow parameters in the feedstock injection zone under the three different structures (the traditional and the novel No. 1, No. 2 structures): the local density, the particle backmixng ratio, and the jet eigen-concentration, the flow feature under three structures were obtained. The experimental results demonstrate that the flow features under both proposed structures are obviously improved comparing with those under the traditional structure. Especially, the performance of the deflector-structured No. 2 is more desirable than that of No. 1.展开更多
This paper presents the application of gamma ray scanning technique to distillation/absorption columns and FCC risers.The flow regime transition.clear liquid height,froth height.crestliquid height over the exit weir o...This paper presents the application of gamma ray scanning technique to distillation/absorption columns and FCC risers.The flow regime transition.clear liquid height,froth height.crestliquid height over the exit weir on a V-1 type valve tray and downcomer hydraulics were investigatedusing the scanning device previously developed.The solid distribution and coke deposition were experi-mentally simulated in a FCC riser simulator by employing a three dimensional scanning device devel-oped for the present investigation.The success of this investigation should shed a light forquantifying two-phase contact phenomena in various gas liquid and gas solid two phase flow system.展开更多
A handy gamma-ray transmission method for estimating the particle concentration distribution in a fluid catalytic cracking （FCC） riser is proposed. The method is based on an empirical correlation ε（r）= ε-（0.19...A handy gamma-ray transmission method for estimating the particle concentration distribution in a fluid catalytic cracking （FCC） riser is proposed. The method is based on an empirical correlation ε（r）= ε-（0.191＋φ25＋3φ11）, which has only one unknown parameter y, hence only one single-beam experimental result is enough to estimate the particle concentration distribution in the riser. In order to verify the feasibility of this method, the particle concentrations of three cross-sections of the laboratory riser were measured and the distribution profiles were compared with those reported in the literature. Furthermore, by comparing other gamma-ray function methods applied in the measurement of risers, this method has distinct advantages, such as the device is simple and has no moving parts, the measurement is rapid, and the safety is high because only one gamma-ray beam is used. Therefore, the method has promising applications in estimating particle concentrations or monitoring operation conditions of risers.展开更多
A CFD simulation was proposed to investigate the electrostatic effect on the hydrodynamic behavior of turbulent gas-solid flow in FCC risers. The simulation was first verified using the open experimental data with exp...A CFD simulation was proposed to investigate the electrostatic effect on the hydrodynamic behavior of turbulent gas-solid flow in FCC risers. The simulation was first verified using the open experimental data with expected electrostatic effects observed in FCC risers. The influences of several operating parameters on the degree of electrification in FCC risers were analyzed, such as surface charge densities, pressure, gas velocity. It was noted that the gas velocity played a highly significant role compared with solid flux, while the effect of pressure was relatively weak. Further analysis showed that a much stronger electrostatic effect was found in small-scale FCC risers than their large-scale counterparts, and in addition, the major regions affected by the electrostatic charge depend on the scale of the riser. Finally, an external electric field was applied to optimize the flow field distribution in the FCC riser. The results of the electrostatic effects on the hydrodynamic behaviors in FCC risers are of great use in providing a reference for the optimization of FCC risers and their scaling.展开更多
In our present work, a post-riser regeneration technology （PRRT） for fluid catalytic cracking （FCC） units was developed to deal with increasingly heavier feedstock and hereby the larger amount of coke deposited on...In our present work, a post-riser regeneration technology （PRRT） for fluid catalytic cracking （FCC） units was developed to deal with increasingly heavier feedstock and hereby the larger amount of coke deposited on the catalyst particles during reaction. This technology can make full use of the advantages of riser regenerator, such as high cokeburning efficiency and low residual carbon, and at the same time overcome its disadvantages, such as difficulty in starting combustion. The average particles concentration on the cross section of the system was studied on a large scale cold model experimental set-up. Also a necessary software was developed by combining the hydrodynamics research results in our work with the coke-burning kinetics model and the heat and mass transfer model developed by previous researchers. The simulation results showed that the PRRT could increase regeneration capability by 16.28%-26.24% over the conventional turbulent fluidized bed regenerator under the similar operation conditions, and that the residual carbon could be kept below 0.1 wt %.展开更多
A steady state model was developed for simulating the performance of an industrial fluid catalytic cracking (FCC) unit which was subsequently used in parametric sensitivity studies. The simulator includes kinetic mode...A steady state model was developed for simulating the performance of an industrial fluid catalytic cracking (FCC) unit which was subsequently used in parametric sensitivity studies. The simulator includes kinetic models for the riser reactor and the regeneration systems. Mass and energy balances were performed for each of these sections and simulation results were compared with the plant data available in the literature. Model predictions were found to be in close agreement with the reported data. Finally this validated model was used for studying the effects of independent variables such as feed preheat temperature (Tfeed) and feed flow rate (Ffeed) on the unit performance at either fixed regenerated catalyst temp/regenerator temp (Trgn) or constant reactor outlet temperature (ROT). The catalyst circulation rate (CCR) was automatically adjusted to keep the ROT constant with varying the independent variables feed preheat temperature while the air rate adjusted for keeping the regenerator temperature constant which consequences the dependency of both dependent and independent variables on the unit performance. The air flow rate to the regenerator was also an independent variable during the parametric sensitivity analysis and its effect on FCC performance was investigated at constant Tfeed, Ffeed and CCR. Combining all the sensitivity analysis, it has been found to increase gas oil conversion and product yields by 5 to 6 percent with decrease of say, 10 K, in the feed preheat temperature (Tfeed) and corresponding increase in air rate (Fair) and catalyst circulation rate (Frgc) at constant reactor outlet temperature (ROT) and regenerated catalyst temperature (Trgc).展开更多
文摘Based on the analysis of flow characteristics of the FCC riser feedstock injection zone, two novel feedstock injection structures are put forward. By investigating three flow parameters in the feedstock injection zone under the three different structures (the traditional and the novel No. 1, No. 2 structures): the local density, the particle backmixng ratio, and the jet eigen-concentration, the flow feature under three structures were obtained. The experimental results demonstrate that the flow features under both proposed structures are obviously improved comparing with those under the traditional structure. Especially, the performance of the deflector-structured No. 2 is more desirable than that of No. 1.
文摘This paper presents the application of gamma ray scanning technique to distillation/absorption columns and FCC risers.The flow regime transition.clear liquid height,froth height.crestliquid height over the exit weir on a V-1 type valve tray and downcomer hydraulics were investigatedusing the scanning device previously developed.The solid distribution and coke deposition were experi-mentally simulated in a FCC riser simulator by employing a three dimensional scanning device devel-oped for the present investigation.The success of this investigation should shed a light forquantifying two-phase contact phenomena in various gas liquid and gas solid two phase flow system.
基金the financial support of the China National High Technology Research and DevelopmentProgram(863 Program)(Grant no.2011AA060802)the National Natural Science Foundation of China(Grant no.21176250)
文摘A handy gamma-ray transmission method for estimating the particle concentration distribution in a fluid catalytic cracking （FCC） riser is proposed. The method is based on an empirical correlation ε（r）= ε-（0.191＋φ25＋3φ11）, which has only one unknown parameter y, hence only one single-beam experimental result is enough to estimate the particle concentration distribution in the riser. In order to verify the feasibility of this method, the particle concentrations of three cross-sections of the laboratory riser were measured and the distribution profiles were compared with those reported in the literature. Furthermore, by comparing other gamma-ray function methods applied in the measurement of risers, this method has distinct advantages, such as the device is simple and has no moving parts, the measurement is rapid, and the safety is high because only one gamma-ray beam is used. Therefore, the method has promising applications in estimating particle concentrations or monitoring operation conditions of risers.
基金The authors thank the National Ministry of Science and Tech- nology of China （No. 2012CB21500402）, the National Natural Science Foundation of China （No. U1462101）, the State Key Laboratory of Coal Conversion of China （No. J13-14-102） and the Research Fund for the Doctoral Program of Higher Education （No. 20130073110077） for supporting this work.
文摘A CFD simulation was proposed to investigate the electrostatic effect on the hydrodynamic behavior of turbulent gas-solid flow in FCC risers. The simulation was first verified using the open experimental data with expected electrostatic effects observed in FCC risers. The influences of several operating parameters on the degree of electrification in FCC risers were analyzed, such as surface charge densities, pressure, gas velocity. It was noted that the gas velocity played a highly significant role compared with solid flux, while the effect of pressure was relatively weak. Further analysis showed that a much stronger electrostatic effect was found in small-scale FCC risers than their large-scale counterparts, and in addition, the major regions affected by the electrostatic charge depend on the scale of the riser. Finally, an external electric field was applied to optimize the flow field distribution in the FCC riser. The results of the electrostatic effects on the hydrodynamic behaviors in FCC risers are of great use in providing a reference for the optimization of FCC risers and their scaling.
文摘In our present work, a post-riser regeneration technology （PRRT） for fluid catalytic cracking （FCC） units was developed to deal with increasingly heavier feedstock and hereby the larger amount of coke deposited on the catalyst particles during reaction. This technology can make full use of the advantages of riser regenerator, such as high cokeburning efficiency and low residual carbon, and at the same time overcome its disadvantages, such as difficulty in starting combustion. The average particles concentration on the cross section of the system was studied on a large scale cold model experimental set-up. Also a necessary software was developed by combining the hydrodynamics research results in our work with the coke-burning kinetics model and the heat and mass transfer model developed by previous researchers. The simulation results showed that the PRRT could increase regeneration capability by 16.28%-26.24% over the conventional turbulent fluidized bed regenerator under the similar operation conditions, and that the residual carbon could be kept below 0.1 wt %.
文摘A steady state model was developed for simulating the performance of an industrial fluid catalytic cracking (FCC) unit which was subsequently used in parametric sensitivity studies. The simulator includes kinetic models for the riser reactor and the regeneration systems. Mass and energy balances were performed for each of these sections and simulation results were compared with the plant data available in the literature. Model predictions were found to be in close agreement with the reported data. Finally this validated model was used for studying the effects of independent variables such as feed preheat temperature (Tfeed) and feed flow rate (Ffeed) on the unit performance at either fixed regenerated catalyst temp/regenerator temp (Trgn) or constant reactor outlet temperature (ROT). The catalyst circulation rate (CCR) was automatically adjusted to keep the ROT constant with varying the independent variables feed preheat temperature while the air rate adjusted for keeping the regenerator temperature constant which consequences the dependency of both dependent and independent variables on the unit performance. The air flow rate to the regenerator was also an independent variable during the parametric sensitivity analysis and its effect on FCC performance was investigated at constant Tfeed, Ffeed and CCR. Combining all the sensitivity analysis, it has been found to increase gas oil conversion and product yields by 5 to 6 percent with decrease of say, 10 K, in the feed preheat temperature (Tfeed) and corresponding increase in air rate (Fair) and catalyst circulation rate (Frgc) at constant reactor outlet temperature (ROT) and regenerated catalyst temperature (Trgc).
