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双语推荐:模拟移动床

以 C8芳烃混合物的吸附分离过程作为研究对象,应用多目标教学优化算法(multi-objective teaching-learning-based optimization algorithm, MOTLBO)对模拟移动床多目标优化问题进行求解。采用TMB方法,建立了模拟移动床模型,并对两个典型的模拟移动床多目标操作优化问题进行了优化设计。通过与NSGA-Ⅱ算法的比较,证明了多目标教学优化算法在求解模拟移动床多目标优化问题上的有效性和优势。此外,还分析了抽出液流量、抽余液流量以及步进时间等对多目标优化非劣解的影响,优化结果为模拟移动床分离过程的工艺设计和操作提供了依据。
Multi-objective teaching-learning-base optimization (MOTLBO) algorithm has been employed to investigate the multi-objective optimization problem of simulated moving bed chromatography separation for the recovery of p-xylene from a mixture of C8 aromatics. The separation process was simulated using true moving bed (TMB) modeling strategy. Based on the MOTLBO algorithm, the optimal operation conditions are designed for two typical multi-objective optimization problems. Comparing with NSGA-Ⅱ, the MOTLBO algorithm has been verified to be more efficient in solving the multi-objective optimization problem of simulated moving bed. In addition, The influences of the extract flow rate, the raffinate flow rate and the switching time on the pareto optimal solutions were also analyzed. The optimization can facilitate the design and operation of simulated moving bed.

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模拟移动床色谱操作参数的模拟和优化对实际分离生产具有重要的指导意义。本文采用平衡扩散模型,对模拟移动床色谱分离D-塔格糖和D-半乳糖进行了模拟研究,根据三角形理论确定了其最佳操作参数,并考察了各区柱数配置、切换时间和分离区流量等变化对分离效果的影响,验证了模拟移动床操作参数的敏感性和模型建立的必要性。
The simulation and optimization of simulated moving bed (SMB) operation parameters are significant for the practical application. In this paper, the equilibrium-dispersive mode was used to simulate the SMB process for the separation of D-tagatose and D-galactose. The optimal operating parameters were determined by the triangle theory. And effects of column distribution ,switching time and flow-rate in section Ⅱand Ⅲ on the separation efficiency were investigated.

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在以偏微分方程形式的单柱色谱分离模型基础上,结合SMB的各区流量和质量守恒关系,建立了模拟移动床色谱分离过程的数学模型。与通常的真实移动床模型相比,所建模型明确考虑进出料口的周期性切换,因此可以反映SMB的真实情况。基于有限差分法对模拟移动床模型数值进行了求解,并分析了操作参数的变化对其操作性能的影响。
Based on the single column partial differential equation model for the industry chromatographic separation, the mathematical model of the Simulated Moving Bed chromatographic separation process is established from the flow and mass conservation relations of the SMB process. Compared with the true moving bed model, the established model takes into consideration the periodic switch at the feed inlets and outlets, hence reflects the conditions in a true SMB process. Method of line is used for the numeric model computations, and the influence of changing operation parameters on the operation performance is analyzed.

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应用计算颗粒流体力学(CPFD)方法对矩形与楔形结构径向移动床内气固两相流动规律进行数值模拟。考察了型结构、料封高度等关键结构参数对径向移动床内气固两相流场分布的影响。通过优化移动床关键结构参数,改善径向移动床中出现的贴壁、空腔问题。结果表明,模拟结果与相应工况下的实验数据吻合较好,模型可以定性描述径向移动床内气固两相流动规律。楔形结构不但能够提高贴壁临界气速,减小贴壁区域厚度,缓解贴壁现象;而且能够有效减小窜气量,明显提高临界空腔气速,避免或者缓解空腔现象。料封高度是影响空腔现象形成的关键性因素之一,适当增加料封高度可以有效消除空腔现象,提高装置操作弹性和操作稳定性。
The computational particle fluid dynamics (CPFD) method was used to simulate the gas-solid flow rules in both rectangular and wedge radial flow moving beds. The influences of bed type and solid-seal height on two-phase flow field distribution were investigated in moving bed. In this research, the key structure parameters were optimized to minimize the effects of “pinning" and “cavity”. Results show that the computed values are qualitatively similar to those of experiment, and the gas-solid flow rules can be predicted by using numerical simulation. Moreover, it also shows that there are a rise of the critical gas velocity for “pinning” and a drop of the “pinning” thickness in the wedge-shaped bed compared with the rectangular-shaped bed, which relieves the “pinning" effectively. Thus wedge structure helps to reduce the amount of gas leakage, and it increases the critical gas velocity for “cavity” significantly to avoid or weaken the “cavity". Besides, the solid-seal

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针对非均质移动颗粒的换热过程,建立了其渗流换热的数学模型,提出了COADI-GS算法,采用此算法对移动颗粒的气固换热过程进行流热耦合数值模拟。通过对均质与非均质这两种不同移动颗粒换热模型的仿真结果进行比较,发现两者的内温度分布有较大差异,非均质移动颗粒模型能更为准确地描述层内的渗流换热过程。计算结果表明,供风压力的增加虽有利于熟料颗粒的冷却,但会降低回收风的温度;颗粒温度随移动速度的增加而升高,近似为线性关系。
For heat transfer process in a heterogeneous moving particulate bed, a mathematical model for the seepage heat transfer process was established. The COADI-GS algorithm was proposed to solve thermally coupled flow of gas-solid heat transfer process numerically. The comparison for the simulation results on the heat transfer models for homogeneous and heterogeneous moving beds demonstrates that the temperature distributions in the two beds are quite different and the model for the heterogeneous moving particulate bed is more accurate for the seepage and heat transfer process in the bed. The results show that the increase of wind pressure is conducive to the cooling of clinker particles, but it may reduce the temperature of recovered wind. The particle temperature increases with the moving speed almost linearly.

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为获得移动荷载引起的加速度的空间分布,基于多尺度和精细化建模技术,建立了350 km/h的双线高速铁路轨道–扣件–轨枕–轨道板–CA 砂浆层–底座板–基表层–基底层–路基本体–地基为一体的耦合大系统非线性真三维数值分析模型。采用动接触算法模拟底座板底面和基表层表面之间的动力相互作用,采用三维黏弹性静–动力统一人工边界技术模拟无限地基的辐射阻尼和弹性恢复性能,考虑移动荷载作用前路基中客观的静应力状态对后续动力计算的影响和地基土、路基填筑材料的非线性,借助于大规模并行计算技术,模拟了地基的初始应力场生成、轨道系统和路基的施工过程和随后8辆编组高速动车组的运行过程。基于分析结果,总结了轨道–路基–地基系统各部分的振动加速度在时间和空间上的分布特征,验证了实体单元模拟轨道空间振动响应的优势。
To obtain the spatial distribution of accelerations induced by moving loads, a coupled nonlinearly true three-dimensional numerical model for high-speed railways with a design speed of 350 km/h is established based on the multi-scale and precisely modeling technology. The model is composed of rails, fasteners, cement-asphalt (CA) mortar, reinforced concrete roadbed, upper layer of roadbed, lower layer of roadbed, embankment and foundation. The dynamic interaction between bottom of the reinforced concrete base and surface of the upper layer of roadbed is simulated using the dynamic contact algorithm. The radiation damping and elastic recovery of infinite foundation are simulated using the three-dimensional viscoelastic static-dynamic unified artificial boundary. Considering the objective influence of static stress state in the embankment before action of the moving loads on the subsequent dynamic computation and the nonlinearities of foundation soils and backfilling materials
在牛顿流体中,对颗粒在4种不同边界的垂直通道中的沉降运动进行了直接数值模拟.计算结果表明:通过计算区域随颗粒运动而移动构建的无限长通道能准确模拟颗粒自由下落到稳定沉降的发展过程;周期性边界条件由于流场变化,对颗粒沉降产生了影响,不能模拟颗粒的自由沉降过程;底部封闭边界适合模拟封闭容器内颗粒与固壁的相互作用过程,若颗粒达到稳定沉降,也能模拟无限长通道内的沉降过程;流化边界适合模拟流化内气固两相流动.计算结果有助于更好地理解和使用不同边界条件.
@@@@In this paper, we present a direct numerical simulation of particle sedimentation in two-phase flow with four different boundary conditions. We demonstrate that different boundary conditions can result in quite different flow behaviors. Some interesting results are obtained. By redefining the computational domain at each time step according to the position of the particle, we construct an infinite channel, which can simulate the particle sedimentation accurately; the flow pattern of periodic boundary is quite different from the infinite channel because of the disturbed flow field;if the settlement is reached steadily before the closed bottom, the closed channel can also simulate the particle settled in the infinite channel;the fluidized condition slows down the particle sedimentation, which is very helpful for better using the boundary conditions.

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模拟移动床技术已经成为手性化合物拆分的重要手段。以Chiralcel OD为固定相、乙醇/正己烷混合物为流动相,采用一种先进的模拟移动床技术(Varicol工艺)分离愈创木酚甘油醚对映体。针对进出料口位置异步切换模式建立了Varicol工艺数学模型,采用有限元正交配置法对模型进行求解。从初始循环内愈创木酚甘油醚对映体内部浓度的时间进程曲线分析了Varicol工艺的分离过程。并且设计了5柱(1-1.5-1.5-1)构态的Varicol工艺分离愈创木酚甘油醚操作区,确定了获得单一对映体产品纯度99%的分离条件,通过实验数据进行了验证。理论和实验研究可以为Varicol工艺的工业应用提供基础依据。
Chiral separation by simulated moving bed technology has become an important process. In this work, an advanced simulated moving bed technology (Varicol process) was investigated to separate guaifenesin enantiomers on Chrialcel OD stationary phase using a mixture of ethanol and n-hexane as mobile phase. Based on asynchronous shift of inlet and outlet lines, a mathematical model was established and solved using the finite element model of orthogonal collocation. The evolution of axial internal concentration profile inside the columns was presented to analyze the influence of discrete switch on separation of guaifenesin enantiomers. The separation region of guaifenesin enantiomers by the 5-column (1-1.5-1.5-1) Varicol process was designed, the operating condition of single enantiomer with 99% purities was determined and its feasibility was validated by Varicol experiment. Both experimental and simulated results would facilitate operation and design of the Varicol process.

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针对复合移动床反应器内固体颗粒运动,采用离散单元法模型(DEM)考察布料器分别为扇形开口和矩形开口时,布料器转速和开口对颗粒运动的影响,并基于文献结果论证了本文模型的准确性。模拟结果表明:①对于不同布料器,颗粒在移动床中呈现平推流和汇聚流两种流动形态。②随布料器转速及开口的增加,颗粒质量通量非线性增加。③随布料器转速的增加,下落径向上颗粒分布更均匀;随布料器开口的增大,下落径向上颗粒分布范围变大,颗粒分布更均匀;对下落径向上颗粒分布,布料器扇形开口时分布呈 U 形、矩形开口时分布呈M形。④沿反应器轴向向下,颗粒分布有均匀化趋势;扇形开口布料器对颗粒分布的离散系数大于1,矩形开口布料器对颗粒分布的离散系数约为0.5。
In this paper,the particle flow in a combined-moving bed reactor was simulated using the discrete element method(DEM),and the accuracy of DEM simulation was verified by a comparison with the literature results. The effects of rotational speed and open-hole size of two kinds of distributing devices were analyzed. The results showed that:①There are two kinds of flow patterns for the two distributing devices,i.e.,plug flow and funnel flow;②particle mass fluxes increased non-linearly with the increase of rotational speed and open-hole size of the distributing devices;③along the radial direction,particles were distributed more uniformly with increasing the rotational speed and open-hole size,and the distribution showed U and M shapes for the two kinds of distributing devices;④the radial distribution of particles were more uniformly downwardly along the axial direction,with values of the variance coefficient exceeding 1.0 for the fan-shaped hole distributing plate,and 0.5 for a

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抗性糊精具有低甜度、低热量、耐热、耐酸、难发酵等特点,能调节人体肠道菌群,改善血糖和脂肪代谢,降低血清胆固醇,促进矿物质吸收,在食品工业应用广泛。分离纯化是制备高纯度抗性糊精的重要工序,介绍了微生物发酵、纳滤、离子交换色谱、模拟移动床以及酶法分离纯化抗性糊精的方法及其原理,为制备高纯度抗性糊精提供了技术指导。
Characterized with low quantity of heat,heat-resisting,anti-acid,anti-fermentation and other excellent physico-chemical properties,resistant dextrin could adjust the human intestinal flora,improve blood sugar and fat metabolism,reduce serum cholesterol and promote mineral absorption,which was widely used in food industry.Separation and purification was an important process to prepare high-purity resistant dextrin.The method and principles of microbial fermentation,nano filtration, ion-exchange chromatography,simulated moving bed and enzymatic purification were introduced,which could provide theoretical guidanceforthepreparationofhighpurityresistantdextrin.

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