Decrease in reboiler temperature?
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The ethanol-water mixture is fed into the tower at 70 degrees, while the extractant is fed at 80 degrees. The recovery rate and reflux ratio have been set, and there are no errors or warnings in the process. The temperature readings inside the tower show a gradual increase from the top to the bottom; the temperature rises on the last few trays, reaching its highest value on the second-to-last tray. However, the temperature of the reboiler decreases instead. What could be the reason? Urgent help needed!
This post was last edited by gcl219 on 2012-4-6 at 15:06. The temperature distribution is available in the attachment; it’s being uploaded for the first time, so it might not succeed: L:L:Q:Q:'(:'( Documents in DOCX format cannot be uploaded
It can be seen by uploading a screenshot; if it’s not the original file, then don’t attach it.
First, has your simulation converged? If convergence is achieved, there must be reasons as to whether the calculated value is reasonable or not. Second, regarding the temperature response and composition, one can examine the composition of the boards where issues are suspected.
There is only a small amount of water and extractant in the bottom of the tower; I tried increasing the amount of water, and indeed the temperature rose a bit. But personally, I feel that the reboiler should have a relatively high temperature in order to provide sufficient heat
I’m not sure what temperature you mean by heat and temperature It’s better to get a BKP. . .
This post was last edited by gcl219 on 2012-4-7 at 20:54; two items were added. I’m not sure if they were uploaded successfully – they were added through the attachment button. It still can’t be transferred; the extractant at the bottom of the tower does not volatilize. The feed consists of 95% ethanol and 5% water, so there is only water and the extractant in the bottom of the tower. In theory, the temperature should be highest in the reboiler. The temperature distribution I obtained is quite uniform; only the temperatures of the last 3 plates increase rapidly. The temperature is highest on the second-to-last plate, which corresponds to the bottom of the tower. The last plate is likely the reboiler, where the temperature drops
Are you using ASPEN to calculate ethanol salt extraction distillation for dehydration? Can anhydrous ethanol be obtained from the top of the tower? ASPEN’s own library seems unable to handle the phase equilibrium with salt. Good luck to you.