Modeling And Performance Optimization Of Simulated Moving Bed Separation Process

Simulated moving bed(SMB)chromatography is a mature separation and purification technology,which has the advantages of strong separation ability,low eluent consumption and continuous production,so it has been widely used in petrochemical,food,bio-pharmaceutical,fine chemical and other fields.However,the process of the SMB separation process is complex,and its separation performance is affected by several process parameters and operation mode,and there is a strong competitive relationship between different separation performance.Therefore,how to optimize the SMB to improve its separation performance has become one of the main research directions in this field.Although the SMB separation process can be optimized by experimental method,it is time-consuming and costly,so it is necessary that through modeling the SMB separation process to study the separation process by simulation,so that the optimization can be carried out faster and more scientifically,which is also one of the research directions in the field of the SMB.In this paper,the SMB separation process is firstly modeled accurately and its separation characteristics are studied,and then process parameters and operation mode of the SMB are optimized to improve separation performance of the process.The main contents of this paper are summarized as follows:(1)The SMB separation process is modeled and studied by simulation.Firstly,the equilibrium diffusion model is used to describe the adsorption behavior of the chromatographic column,and the orthogonal collocation on finite elements method is used to solve the model to obtain the concentration distribution of each component in the device.Then,the change of component concentration in the SMB separation process is studied.Finally,how the change of process parameters affects the separation performance of the SMB is studied by simulation,so as to provide a theoretical basis for selecting process parameters.(2)Optimize process parameters of the SMB,a optimization method of process parameters of the SMB based on equilibrium theory is proposed to solve the problem of the degradation of separation performance under the initial process parameters caused by the change of model parameters.By analyzing how the model parameters are affected by the uncertain disturbance,the proposed method moves the process point to the parameters region with fewer faults and higher reliability.Taking the separation process of fructose syrup as the research object,it is verified that the proposed method can meet the requirements of fructose purity and recovery at a high confidence level in the case of adsorbent deactivation and chromatographic column blockage.(3)Optimize operation mode of the SMB,an extra-column and binary-partial-discard(EC-Bi PD)strategy is proposed to solve the problem that the productivity is limited due to the selection of process point in the complete separation region of the SMB.In the proposed strategy,firstly,in order to increase the feed flow,the process point is selected in the area of pure extract product and non-pure raffinate product.Then,according to the set integral purity threshold,part of the raffinate product is temporarily discarded and part of the extra product is permanently discarded.Finally,the influence of the integral purity threshold of the extra product on the total separation performance is analyzed,and compared with the conventional SMB process and partial discard strategy,the superiority of the proposed strategy is proved.