Non-convergence problem in the atmospheric pressure side-line stripping tower simulation

Thread Content

I’m having trouble with simulating a side-stream stripping tower at atmospheric pressure; the simulation does not converge. I am using the Multifrac model. *** SEVERE ERROR: VAPOR OR LIQUID FLOW ON STAGE 21 IS TENDING TO DISAPPEAR. PLEASE REVIEW THE REFLUX/BOILUP SPECIFICATIONS, AS WELL AS THE SPECIFICATIONS RELATING TO THE HEATERS AND/OR PUMPS. The feed consists of aviation fuel and light oil in a 2:1 ratio; the temperature is 250 degrees. There are 21 theoretical trays in Tower 1, with 18 of them used for feeding; complete condensation occurs, with no reboiler used. Saturation steam is used for stripping, at a pressure of 0.5 BAR. Tower 2 has 4 trays; again, complete condensation occurs, with no reboiler used, and saturation steam is used for stripping at 0.5 BAR. How much can be extracted from the bottom of the towers? How much diesel can the side-line tower extract? Thank you