Control And Energy Saving Of Vertical Double Wall Dividing-wall Column For Separating A Quaternary System

Compared with the conventional column sequences,the DWC can separation of multicomponent systems and reduce energy consumption,so it has become a hot research topic.Separation of three components of DWC is relatively common,while separation of four components of DWC is relatively rare.In this paper,the VDWDWC has a relatively good separation effect of the intermediate components and can effectively reduce the height of the main column section.Compared with the conventional distillation sequence,a reboiler and a condenser are reduced,so the energy consumption and equipment costs are reduced.In this paper,the VDWDWC for the separation of the proposed four-component mixture is mainly studied as follows:(1)For the process of separating the four-component alkane mixture with the vertical double wall divided-wall column(VDWDWC),the five-column model was established by Aspen Plus,and single factor optimization was performed,using BP neural network and RSM for the process.(2)The VDWDWC dynamic model for the separation process of a quaternary alkane system was established.The TC-CC cascade control SPL of VDWDWC is proposed to control the whole VDWDWC process.The control effects of TC control、TC-CC cascade control、TC-CC cascade control and TDC-CC cascade control with feed-forward control are compared and analyzed.The results suggested that the TDC-CC cascade control with feedforward control structure has good controllability for VDWDWC when the feed composition and feed flow disturbance occurs.After adding feed-forward control,the control effect has been significantly improved,the stable time is shortened,and the product purity residual error were slightly decreased,the maximum overshoot was reduced.(4)The energy-saving principle of VDWDWC was studied by the method of concentration analysis.The heat transfer cross the wall of the VDWDWC was studied.The process of heat pump combine with VDWDWC is studied.(4)Finally,the feasibility of VDWDWC separation of alcohol system was verified by experiments and simulation,and the effects of SPL and reflux ratio on the separation efficiency were studied.