Dynamic Control And Performance Analysis Of Dividing-wall Distillation Columns

The distillation process is able to achieve the separation of complex systems,which is used in chemical production process frequently.However,the distillation process is always accompanied by a huge energy consumption,and this leads to the existence of many constraints of rectifying in the actual production process.It has even influenced the development of chemical industry.Aiming at the defects of large energy consumption in the distillation process,the scholars put forward a variety of schemes to improve the design structure and operation mode of distillation column in order to enhance the thermal efficiency of distillation equipment.Then the design scheme of the dividing wall distillation column(DWDC)has made great contributions to the improvement of the thermal efficiency of the distillation process.As a fully thermally coupled structure,DWDC not only can reduce the cost of equipment investment,but also can greatly reduce energy consumption,which makes that there are unparalleled advantages of the dividing wall distillation column in the chemical production process.Although the thermal coupling brings the advantages of saving energy for DWDC,it also brings many difficulties to the design and operation of DWDC.When the DWDC is designed according to the conventional design,the DWDC operating area is strictly limited.In addition,even under extreme operating conditions,it has been found that the concentration of the three products cannot be significantly improved.The research group three years ago,according to the formation mechanism of the problem,put forward the over design scheme used as a solution to expand the operating area of DWDC.It solves the problem of limited DWDC operating domain in the steady state.However,the research only stays on the steady state,and does not analyze the dynamic performance of the over design scheme.Nevertheless,the dynamic performance usually determines the performance of the chemical equipment in the actual production.In order to fill the blank of the dynamic performance and analysis of the over design scheme,the dynamic performance evaluation of the design scheme is carried out from two aspects of the separation of the ideal system of the three elements and the practical system of the three elements.Firstly,the steady state of the structure design was reproduced,to obtain the dynamic model based on the over design scheme.According to the relevant knowledge of the control system,the control loop is built on the basis of the dynamic model.Finally,comparative analysis of improved design and initial design from the two aspects of the closed-loop dynamic performance was carried out.In the completion of a number of case analysis,it can be concluded that the over design scheme can indeed improve the flexibility of system control,improve the dynamic performance of DWDC.In view of the advantages of extending the DWDC operation area and improving the dynamic performance of the DWDC,the over design scheme should be regarded as the key step in the DWDC design process.