Modelling continuous foam fractionation with reflux

An equilibrium stage approach is taken to modelling the performance of a continuous foam fractionation column with reflux. Such an approach has been facilitated by recent developments in the understanding of pneumatic columns of foam that allow liquid rates within the rising column of foam to be predicted with confidence. It is shown that the recovery of surfactant into the product stream increases monotonically with increasing reflux ratio but this is at the expense of reduced product rate.     

Optimization of the sulfolane extraction plant based on modeling and simulation

An optimization system, based on modeling and simulation, was developed for a sulfolane extraction plant. The primary objective of the operation of this plant is to increase benzene composition, which is mostly affected by the recycle streams in the plant. In this work the optimal recycle streams were identified and resulting product compositions were evaluated. In the optimization, suitable parametric models for each process unit were obtained first from the steady-state rigorous modeling and simulation of the sulfolane extraction plant. The parametric models were then employed to develop the optimization system based on the SQP scheme. Results of simulations show promise for further economic improvements over present operation states.     

全电动注塑机混合驱动式合模机构优化分析

以加快合模机构移模速度和优化移模速度曲线为目的,优化设计出一种新型混合驱动式合模机构,并对该合模机构的开合模过程进行运动学仿真和动力学仿真。结果表明,相比于现有全电动注塑机混合驱动合模机构,新型混合驱动式合模结构在移模速度上有了显著提高,移模速度曲线也更接近理想的正弦曲线。新型全电动精密注塑机混合驱动合模结构具有低成本化的优势,同时其机构运动学和动力学的性能也超越了已有全电动混合驱动合模结构。     

Optimal operation of the pressure swing adsorption (PSA) process for CO<Subscript>2</Subscript> recovery

The operation of PSA (Pressure Swing Adsorption) processes is a highly nonlinear and challenging problem. We propose a systematic procedure to achieve the optimal operation of a PSA process. The model of the PSA process for CO₂ separation and recovery is developed first and optimization is performed to identify optimal operating conditions based on the model. The effectiveness of the model developed is demonstrated by numerical simulations and experiments using CO₂ and N₂ gases and zeolite 13X. Breakthrough curves and temperature changes in the bed are computed from the model and the results are compared with those of experiments. The effects of the adsorption time and reflux ratio on the product purity and the recovery are identified through numerical simulations. The optimization problem is formulated based on nonlinear equations obtained from simulations. The optimal operating conditions identified are applied to experiments. The results show higher recovery of CO₂ under optimal operating conditions.     

反应精馏过程模拟优化的研究进展

反应精馏过程的数学模拟是反应精馏塔设计、放大、控制的基础。对反应精馏过程模拟模型、求解方法以及优化的研究进展进行了综述。     

Model based prediction of required cut size diameter for fractionation of fly ash from a grate-fired wood chip incineration plant

Utilization of biomass ash as a soil improvement material is limited by the admissible input of heavy metals. It is well known that heavy metal concentrations are increased in fine ash fractions. In this study, two models are investigated to describe the distribution of various heavy metals in different size fractions of fly ash from a grate-fired biomass incineration plant incinerating wood chips. The second model assuming a dependence of the heavy metal concentration from the reciprocal particle diameter to the power of the variable N correlated well with measured concentrations. This model was then used in the calculation of the required cut size of a classifier for the production of a coarse fraction with heavy metal concentrations below limits from a fly ash sample exceeding the Austrian limits for a soil improvement material. The predicted concentrations of the critical heavy metals Cd and Pb and the total mass of the coarse fraction produced corresponded well with measured values, and although the concentration of Zn was considerably underestimated in the model, the produced coarse fraction was within the limits for utilization.     

催化裂化反再系统计算机模拟与优化

采用离线调优的方法,对石油一厂催化裂化反再系统的操作条件进行了优化计算,建立了较精确的生产过程数学模型。在对生产过程进行模拟与优化的基础上,针对催化裂化装置在原料性质及加工量变化状况,就如何选择各种工艺参数等问题进行了优化处理;为确定生产装置调优指标和改造措施提供了方便可行的方案,同时也为提高催化裂化装置的经济效益提供了可靠信息。     

空气分离装置的模拟与优化

采用ASPEN系统模拟软件对某空分装置的设计工况和实际工况进行了模拟计算,给出了以纯氧产量最大为目标函数的操作参数的优化结果,其结果可以为空气深冷分离设计和操作提供可靠的参考数据。     

乙烯装置冷箱脱甲烷系统模拟优化

中国石化扬子石化股份有限公司烯烃厂650kt／a乙烯装置因二元制冷系统效率低，无法为冷箱、脱甲烷塔系统提供足够的冷量，加之部分操作控制指标不尽合理，导致乙烯损失大。文中介绍了应用Aspen软件对该系统工艺流程进行模拟计算的过程，分析了存在的问题，提出了最优化操作控制指标。     

离心式气液分离器内流场的数值模拟与结构优化

基于计算流体动力学(CFD)方法,采用Gambit建模,利用Fluent软件,对常规立罐式离心气液分离器进行了模拟仿真。通过流场分析可以看出,流场对称性很差,底流出口附近气体含量较多,说明气液分离效果不好。通过结构优化,包括将底流出口改为正下方排液,单入口改为双入口结构,减小罐体直径,溢流管伸入分离器内部入口管之下,以及将分离器下端改为锥形结构等,改善分离器内部流场的轴对称性及气相体积分数分布情况,并提高分离器的净化程度。     

Enrichment of Lysophosphatidylcholine in Canola Lysolecithin

Lysophosphatidylcholine (LPC) possesses excellent oil‐in‐water emulsifying properties and health benefits. The objective of this study was to produce an LPC‐enriched fraction from lysolecithin generated during enzymatic degumming of crude canola oil. Three alcohols (methanol, ethanol and isopropanol) were evaluated for their effectiveness at enriching LPC. A 3 × 3 full factorial design was employed to study the effects of two processing parameters (temperature and alcohol/lysolecithin ratio) on three responses (yield and LPC concentration of alcohol soluble fraction, and LPC recovery) with the most effective alcohol. Ethanol was found to be the best solvent to enrich LPC in lysolecithin. An ethanol soluble fraction with more than 50 % LPC was produced. Quadratic models with R² > 0.9 were developed to describe the relationship between the processing parameters and the responses in the 3 × 3 full factorial experiment. Both ethanol soluble fraction yield and LPC recovery increased with increasing temperature and ethanol/lysolecithin ratio. LPC concentration in the ethanol soluble fraction was enhanced with decreasing temperature and ethanol/lysolecithin ratio. According to the analysis, ethanol soluble fractions with LPC concentration higher than 66 % could be obtained at temperatures of 0–40 °C and an ethanol/lysolecithin ratio of 2:1 (v/w).     

An Optimization of Capital and Operating Alternatives in a NGL Recovery Unit

A natural gas liquids (NGL) recovery unit currently in operation has been simulated and compared with a real unit. Optimized operating conditions have been determined, in which the objective function is based on cost analysis. Following this, different turboexpansion processes have been analyzed and the best flow sheet selected, based on capital analysis and operating limitations. Parameter optimization of the entire modified plant has been performed using an advanced genetic algorithm program, to determine optimal operating conditions. The best revamping alternative is a turboexpander‐exchanger process, in which case the profit is increased by 28 %.     

Model Optimization for the Dynamic Simulation of Reactive Absorption Processes

The optimal design of reactive separations is impossible without reliable process models. Especially for the dynamic simulation and the model‐based control of complex reactive absorption processes the model development leads to a contradiction between the required model accuracy to reflect the process complexity and the feasibility of process simulations regarding the computation time. In this respect, we have developed a new rigorous dynamic two‐phase model based on the two‐film theory as a first step, which takes into account the influence of chemical reactions and additional driving forces in electrolyte systems on mass transfer considering thermodynamic nonidealities as well as the impact of column internals on the process hydrodynamics. For a model optimization, we have performed an analysis of different model approaches for complicated industrial absorption processes and determined an appropriate model complexity. Based on results of sensitivity studies, we have accomplished different model modifications leading to a stabilization of the numerical solution without affecting the good agreement between simulation results and the experimental data. This time‐optimized model can be considered superior as compared to previous approaches and facilitates for the first time a rigorous dynamic simulation of entire reactive absorption columns and the application within an on‐line process control system.     

Optimization of Methanol Yield from a Lurgi Reactor

Methanol is an important chemical with the potential to become an alternative fuel. An optimization study was performed for a Lurgi methanol synthesis reactor using the commercial process simulator Aspen Plus. The optimization routine is coupled with a steady‐state model of the methanol synthesis reactor. Syngas inlet temperature, steam drum pressure, and cooling water volumetric flow rate were optimized so that methanol production in the reactor outlet was maximized. The methanol yield increased by 7.04 %.     

A microscopic approach to determine the origin and mechanism of coke formation in fractionation towers

This study investigated the deposition of coke in a fractionation tower following thermal cracking of heavy feedstocks. A simple microscopic technique was used to determine whether the coke formed in situ in the fractionator or was formed elsewhere (e.g. in the reactor vessel) and was subsequently entrained in the vapour phase. The reflectance of coke types, mode of occurrence, and distributions from the bottom to the top of the fractionator were used to interpret the range of temperatures responsible for coke formation. Both isotropic and anisotropic (mosaic) coke was observed in the samples. The anisotropic textural features indicated that asphaltenes carry-over was a minor problem and that the vast majority of the isotropic coke precursors were the maltenes present in the gas phase that entered the fractionator. The formation of perfectly spherical mesophase was attributed to the gas oil stream itself used to quench the vapours exiting the thermal cracking vessel. Microscopic evidence, along with metals concentration in the coke at various locations of the operation provided useful information as to the nature of the coke precursors.     

苯乙烯装置中脱氢尾气吸收系统的建立与优化

阐述了苯乙烯的现状并分析装置脱氢尾气的价值。重点对绝热脱氢法中粗苯乙烯塔进行了模拟设计和优化。通过Aspen Plus软件的模拟,建立了一套脱氢尾气吸收系统,并且探讨了吸收塔的影响因素,确立了最优工况,对实际工业生产起到一定的指导作用。     

激光加工多孔端面机械密封结构参数的协调优化

通过建立激光加工多孔端面机械密封的理论分析模型,采用有限差分法求解雷诺方程,得到不同微孔结构参数下密封端面间的膜压分布,进而可以计算多目标优化方法构建的液膜刚度与泄漏量之比的协调函数,获得了最佳的微孔结构参数值。研究表明,当微孔深径比ε为0.1069和微孔密度sp为0.492时,刚漏比最大。     

茂名乙烯裂解汽油加氢操作工艺的优化

分析了造成茂名石化裂解汽油加氢装置混合芳烃产品损失率以及能耗较高的原因,介绍了茂名石化乙烯裂解汽油加氢装置在工艺操作方面采取的优化措施。通过操作工艺的优化达到了降低裂解汽油加氢装置的能耗和混合芳烃产品损失的目的。     

Simulation and Optimization of an Adiabatic Multi‐Bed Catalytic Reactor for the Oxidation of SO2

A software package was developed for the simulation and optimization of a multi‐bed adiabatic reactor for the catalytic oxidation of SO₂, using a heterogeneous plug flow model. The orthogonal collocation (OC) technique with up to eight collocation points was used for the solution of a nonlinear, two‐point boundary value differential equation for the catalyst particle, and it was shown that the use of the OC technique with two collocation points can describe the system well. Because of the nonlinear behavior of the effectiveness factor along the bed, optimal catalyst distribution between the beds and corresponding inlet temperatures were determined by two methods, including: the use of (1) intrinsic or (2) actual rate of reaction in the optimization criteria. The results showed that for the second case, the minimum amount of the catalyst can be reached at lower temperatures, the amount of catalyst required is always less, and the number of beds is greater than or equal to that of the first case.     

等值渗流阻力法在整体压裂优化设计计算中的应用

压裂改造技术是油气井增产、水井增注的一项重要技术措施,随着压裂技术的发展,从单井的增产增注逐渐发展到整个油藏的总体压裂优化设计。目前整体压裂优化设计计算大多采用数值模拟的方法,该方法适应性强但计算方法复杂。本文提出一种简单的优化设计计算方法:利用水电相似原理,建立等效渗流阻力优化计算模型。该方法计算简单适用,能够分析井网及压裂参数对压裂生产井产能的影响。