1. Operation of Divided Wall (Petlyuk) Column at energy lower than minimum energy
Ambari Khanam Supervisor: Sigurd Skogestad
Department of Chemical Engineering
Norwegian University of Science and Technology (NTNU)
November 7, 2012

2. Outline
Introduction to DWC
Operation at lower enery
Motivation
Around more than100 Divided Wall columns already in use.
Growing Economy,personal usage of energy increasing day by day,limted energy resources, CO2 Reduction compliances.
Divided wall column can save upto 20-30% of energy (for 3 products and even more in other cases)
Also saves Capital Costs

3. Schematic diagram of 3-product Petlyuk Column and Divided Wall Column
Background
The project work is related to most likely situations in Industrial practice.
- The column is designed for optimal operation
- Optimal Energy/close to Vmin for the given product specifications
- Actual avialable energy lesser (in the range of 70-95%)
- Effect on product purities in all three streams
- Minimize the impurities (the objective function)
Operation
Assignments
Mode 2
J=min. impurity
Mode1
J=V
Mode 2,With fixed boilup rate V (close to Vmin)
U = RL, RV,L,S and V(fixed)
U= RL,L, S, RV(fixed,+-20%) and V(fixed)
Fmincon in Matlab for optimization

4. Results and remaining job
Mole fraction of B versus V(Boilup)
Mole fraction of A versus V(Boilup)
Plot the compositions profile keeping one U varying at a time
U = RL, RV,L,S and V(fixed),
U= RL,L, S, RV(fixed,+-20%) and V(fixed)
Run the model for DWC in matlab and following optimal values are obtained (Model prepared by Dwivedi)
XA and XB for different prices