Dynamic column model also requires to consider downcomer dynamics in order to correctlyChemEngineering 2021, five,4 ofChemEngineering 2021, five,Considering that we wish to simulate the start-up not simply of a single segment or maybe a regular four of develcolumn, but in addition of extra segments that are connected by means of the downcomer, the17 oped dynamic column model also needs to think about downcomer dynamics in an effort to correctly predict downcomer backup throughout start-up. This connection among each downcomer on every tray, which is Carbazochrome accounted for connection betweenmajordowncomer from predict downcomer backup in the course of start-up. This inside the model, is actually a every single difference typical column models. Because of the truth that liquid is main difference from regular on every tray, that is accounted for within the model, is usually a supposed to flow from one downcolumn models. Due 1, reality that liquid is supposed to flow from a single downcomer to correct comer for the adjacent towards the flow equations need to be developed that predict thethe adjacent the liquid in the need to be created that each and every the correct tray. Additionally, behavior ofone, flow equations downcomer, but also onpredictconnected behavior of the theliquidbalance must be thought of for each downcomer, since the effects ofbalance the heat within the downcomer, but in addition on every single connected tray. In addition, the heat heating must be considered for every single downcomer, since the effects of heating the adjacent segment adjacent segment by the side stream must be accounted for. by the side stream has to be accounted for. The model was implemented in Aspen Custom Modelerand the the properties for the in Aspen Custom Modelerand properties for the The model was implemented elements were Pirepemat Purity & Documentation retrieved from an Aspen Propertiessubroutine. ForFor a better undercomponents had been retrieved from an Aspen Properties subroutine. a much better understanding, a tray inin thesegmented distillation column is is depicted Figure 2. The tray is standing, a tray the segmented distillation column depicted in in Figure 2. The tray is divided into separate manage volumesfor the equilibrium stage and the the downcomer. divided into separate control volumes for the equilibrium stage and downcomer.Distillate -1 , ,-1 , -i, , ,-1 , ,-1 , -iDowncomer jStage j,, , ,Feedi ,,,i,i , , ,,Bottom solution, ,+1 , +1 +, , ,i, , ,iFigure two. Schematic representation of a tray Figure 2. Schematic representation of a tray inin the segmented column,divided into downcomer andand equilibrium stage. the segmented column, divided into downcomer equilibrium stage.Within the following, the equations for the equilibrium stage plus the downcomer of every In are described. the equations for for equilibrium downcomer for the equilibrium stagethe following, Then, the method theconnecting thestage plus the downcomer of each stage are described. Then, the column is presented. stage as well as the segment from the approach for connecting the downcomer to the equilibriumstage and also the segment from the column is presented.two.1. Equilibrium Stage The MESH equations for the equilibrium stage are presented beneath. Index i indicates two.1. Equilibrium StageThe MESH equations for the equilibrium stage are presented under. Index i indicates the elements and index j indicates the theoretical stage. liq vapd HUj xi,j + HUj yi,j liq dt vap ( , + , ) weep tostage dc feed z + L = Fj xi,j + Vj+1 yi,j+1 – Ldc xi,j i,j j j-1 xi,j-1 + L j weep todc x weep V y tostage dc xi,j – – L j = feed L j + i,j – j i,j + , + ,+1 – , +1 -1 ,-1 weep todc ,.