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Simulation, Optimization and Scaling up of Simulated Moving Bed Systems for Separations of Citric Acid

Author: LiuJianQi
Tutor: PengQiJun
School: Jiangnan University
Course: Applied Chemistry
Keywords: Simulated moving bed Citric acid Modeling Simulation Optimization
CLC: TQ225.41
Type: Master's thesis
Year: 2008
Downloads: 345
Quote: 3
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Abstract

Citric acid, the chemical name 2 - hydroxy tricarballylates Formula C6H8O7, is an organic compound with three hydroxyl groups, is widely used in food industry, pharmaceutical industry, chemical industry and other fields. In China, citric acid, high pollution and high consumption of traditional crafts, causing more and more attention. To this end has developed a lot of new technology to solve this problem; which developed by Jiangnan University, Wuxi green separation applications Institute of Technology, only hot water source separation promote simulated moving bed chromatography citrate separation technology has a good application prospects. Visible from the simulated moving bed chromatography technology to produce citric acid process, the process is very simple, in addition to hot water without adding any chemicals, so there is no waste generation. These characteristics in terms of environmental protection or in terms of product yield, production costs are very attractive, its success applied to industrial production, for the citric acid industry will be a revolution. Exciting is that a large number of test run results in the Institute 52mmID × 1700mm × 10 Genzhu SMB small pilot plant. Industrial chromatographic techniques separate mixtures embarrassed provides a powerful tool. The simulated moving bed technology to achieve the continuous separation of the mixture, has many advantages, have seen great application prospects in the citric acid chromatography. However, due to the complexity of the simulated moving bed technology itself, the small pilot scale enlarged to large-scale industrial production is a challenging subject. The the traditional zoom back ships experience in this process, due to its own characteristics, is no longer applicable; such a computer simulation technology to become more suitable for amplifying means. To complete the entire analog amplifier engineering, the paper work is mainly focused on the following aspects: 1. Determination of the model parameters, simulation methods and parameters in analytical grade column (4.6mmID × 250mmL), research on the effect of separation. 2. Study to determine the model parameters, and the parameters of the effect of separation on a preparative column, the column size larger process of law. 3 in SMB preparative chromatography on 52mmID × 1700mmL × 10 Genzhu the enlarged simulation and verification to determine compliance simulation mathematical model, citric acid chromatography behavior and preliminary to explore the operation optimization conditions. Optimization Algorithms in the the 52mmID × 1700mmL × 10 Genzhu SMB preparative chromatography. The first step, determined by an experimental method of model parameters for each chromatographic analytical column (4.6mmID × 250mmL): the outer porosity (tracer method): 0.34; citric mass transfer coefficient (van-Deemter curve method): 0.3576 min ^{-1 ; glucose mass transfer coefficient (Van-Deemter curve method): 0.5698min ^{-1 ; citric acid adsorption isotherms (forward analysis): 72.9730 · c _Ca (1 0.4840 · c _CA) 0.3273 · c _CA; the glucose adsorption isotherms (frontal analysis): 1.3066 · c _glucose. Then, using a combination of different methods for solving a variety of chromatographic model to simulate column breakthrough curves of citric acid and glucose. From the computation time (7s) and analog effects (in accordance with the degree of AS = 97%) point of view into account, the online method and diffusion plug flow model is the best choice. Finally, a detailed study of model selection, solution method and model parameters of the simulation results and conclusions are summarized as follows: 1. Chromatography model selection computation time: proliferation of plug flow model> and balanced diffusion model ideal model; simulation effect (with conformity AS characterization): Diffusion plug flow model> and balanced diffusion model> ideal model. Chromatography model solving method of computation time: the finite element method, finite difference method> Online Solving Process; the analog effect: finite element method> Online Solving Process finite difference method. All model parameters, adsorption isotherms of the simulation results. Variation of the porosity of the penetration curve translational, without affecting its penetration time; mass transfer coefficient changes affect the penetration time, without changing its retention time; adsorption isotherm changes that affect the penetration time, affect the retention time. The second step, first of all, the model parameters of the analytical column to zoom back to the preparative column, the experimental method: the outer porosity (retention time of anti-algorithm): 0.35; citric mass transfer coefficient (van-Deemter curve method): 0.3373 min ^{-1 ; glucose mass transfer coefficient: 0.5358min ^{-1 . The inverse method to determine the citric acid / glucose adsorption isotherm model: And then, using adaptive on-line method for solving multi-step preparative column chromatography model (diffusion plug flow model) to solve Simulation results show that test and analog outflow curve the deviation DEV = 0.012, the chromatographic model a good description of the citric acid / glucose separation behavior of a single column in preparative chromatography. The third step is to consider the import and export conversion mechanism between the columns, preparative column chromatography established model (diffusion plug flow model) was established based on the simulated moving bed model. Method of simulated moving bed chromatography model is established on the basis of multi-step adaptive online law. The computer is running results show that the conformity of the test and simulation curve (FIT) was 96.35%, indicating that established simulated moving bed model and its solution a good explanation of citric acid simulated moving bed chromatographic behavior. The fourth step, using the the triangular theory and direct optimization of citric acid simulated moving bed chromatography separation process were optimized. Citric acid / glucose competitive adsorption isotherms based on the establishment of a complete separation of the triangle (below), by a large number of simulation has been the best operating point position S3, the optimal operating conditions: eluent flow rate (5.551L / h), feed flow rate (1.026L / h), the extract flow (2.738L / h) the raffinate flow (3.839L / h), the switching time (0.340h), separation results: extract purity (99.6% ), raffinate purity (94.3%). Then, the minimum separation costs as the goal, to the the four districts flow and switching time as a variable to establish direct optimization model: the optimal operating point of the triangle theory as the initial value of the direct optimization, quadratic optimization method for solving optimization model directly, obtain optimum operating conditions; eluent flow (5.139L / h), the feed flow (1.343L / h), the extract flow (2.939L / h) the raffinate flow (3.543L / h), the switching time (0.356h), the separation effect: extract (99.7%) of purity of the raffinate purity (95.4%). Direct optimization method to get the optimum operating conditions for experimental design, separation results: extract purity (99.7%), the raffinate purity (95.3%).}}}}

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