Modeling and optimization of a large-scale slurry bubble column reactor for producing 10,000 bbl/day of Fischer-Tropsch liquid hydrocarbons

A user-friendly simulator based on a comprehensive computer model for slurry bubble column reactors (SBCRs) for Fischer-Tropsch (F-T) synthesis, taking into account the hydrodynamics, kinetics, heat transfer, and mass transfer was developed. The hydrodynamic and mass transfer data obtained in our laboratories under typical F-T conditions along with those available in the literature were correlated using Back Propagation Neural Network and empirical correlations with high confidence levels. The data used covered wide ranges of reactor geometry, gas distributor, and operating conditions. All reactor partial differential equations, equation parameters and boundary conditions were simultaneously solved numerically.The simulator was systematically used to predict the effects of reactor geometry (inside diameter and height) as well as superficial gas velocity and catalyst concentration on the performance of a large-scale SBCR provided with cooling pipes and operating under F-T conditions with cobalt-supported catalyst and H₂/CO = 2. The performance of the SBCR was expressed in terms of CO conversion, liquid hydrocarbon yield, catalyst productivity, and space time yield. The simulator was also used to optimize the reactor geometry and operating conditions in order to produce 10,000 barrels/day (bbl/day) of liquid hydrocarbons.     

Investigation of pressure drop in a cocurrent downflow three-phase moving bed

Based on a self-established cold-flow experimental device, the pressure drop in a cocurrent downflow three-phase moving bed was investigated under a wide range of gas, liquid, and solid flow rates during dynamic and steady-state operation. The results showed that for the startup of the bed, since the first bed layer packed by fall-falling of particles had lower voidage, it would take at least one bed volume time to make the voidage in the bed reach the steady-state. Under steady-state conditions, the pressure drop increased with the increase of gas and liquid mass flow rates, liquid viscosity, and decreased with the increase of solid flow rate. Furthermore, it was found that the liquid distribution became more uniform due to particle movement. The experimental data obtained in this study was used to develop a correlation to predict the pressure drop in a three-phase moving bed with an average relative error of 9.32%.     

操作变量对大型浆态床反应器流体力学特性的影响

研究了系统压力、表观气速和固体颗粒体积分数对浆态床反应器气含率、气泡直径及气液接触面积的影响 ,通过试验得出了气含率和操作变量之间的统计关联式 ,给出了在湍流条件下浆态床反应器中气含率和气体动量之间的关系     

A study on the accuracy of force analogy method in nonlinear static analysis

In this paper, the accuracy of the force analogy method (FAM) for nonlinear static (pushover) analysis is investigated. Hence, after explanation of the concept of FAM by a new approach, 12 2D steel special moment resisting frames with different configurations were derived from two different 3D archetypes and modeled using four various methods of capturing nonlinearity including SAP2000 super elements, OpenSees force‐based and displacement‐based fiber method, and FAM. In addition, a MATLAB code was developed for modeling and analyzing the frames by FAM. The accuracy of FAM in predictions of pushover curves, base shear forces, and plastic rotation of the critical hinges was investigated. The results indicated that in general, the predictions obtained using the FAM had a good agreement and compatibility with those from other methods of analysis currently used in practice for seismic performance assessment of structures.     

Laboratory and numerical modeling of strip footing on geotextile-reinforced sand with cement-treated interface

This paper presents the results of a laboratory and numerical study on the effects of cement treatment of the interface between geotextile and sand on the bearing capacity of a foundation built on geotextile-reinforced sand. The bearing capacity of a 25 cm × 7.5 cm strip footing on a 90 cm × 25 cm × 30 cm sand box reinforced using a single-layer reinforcement of different lengths including, 20, 30, 45, 60, 75 and 90 cm, was studied in a laboratory. A cement-treated zone was created on the geotextile to improve the friction and adhesion of the interface zone. Tests were also conducted on reinforced soil without a cement-treated zone and the results were compared. A finite element model was calibrated and used for further studies. The results of the laboratory tests indicated that cement treatment of the interface between the geotextile and sand increases the bearing capacity of the foundation by 6%–17%, depending on the length of the reinforcement. The effectiveness of the cement-treated interface on improving of the bearing capacity is more evident with shorter-length reinforcements. For a certain bearing capacity, the required length of the reinforcement was reduced by approximately 40% when the interface zone of the sand and reinforcement was cement-treated. The effect of the cement-treated zone on the bearing capacity was more evident in low settlement levels, and decreased as the length of the reinforcement increased.     

中心复合设计法研究浆液床反应器的气液传质特性

采用中心复合设计法研究系统压力(P)、气体表观气速(UG)以及固体颗粒体积浓度(Cv)对浆液床中体积气液传质系数(kLa)的影响。在实验中发现,体积气液传质系数随系统压力和气体表观气速的增加而增加,当增加固体颗粒体积浓度时反而下降。在0.1～1.5MPa的压力范围内,甲烷的饱和溶解度遵守亨利定律。