Team,
I am working within a petrochemical project where there is a propylene-propane splitter. The suggested control loops by one engineering party are shown in the attached file with some preliminary values. I have some doubts about some loops and these in particular are:
- The feed flow control is adjusted according to the level in the overhead accumulator. It is usually set as either a simple flow control or cascaded with the level in the feed tank.
- The tower pressure is adjusted via split range control: hot vapor bypass and throttling the off gas. Isn't one enough (preferably the throttling of off gas)?
- The level in the tower bottom is adjusted according to the heat duty of the reboiler via the low pressure steam flow control valve. Isn't it better to control the tower bottom level via the flow of the propane flow? also, isn't it better to control the bottom temperature via the steam flow (I don't see any control of the tower temperature in the scheme)? what about the control of steam condensate level in the reboiler shell?
- Is it a good idea to have a pressure throttling valve at the motive stream of the ejector? is it going to be able to reach the fuel header pressure of the boiler?
- I heard once that it is not a good idea to put a throttling valve against a positive displacement pump. Here, there are three flow control valves against the propylene supply pump to the reactors. Aren't these valves redundant as each reactor is supposed to receive an equal flow and the shall have similar operating pressure (more or less)?
I appreciate any exchange of ideas, feedbacks, and suggestions.
If you need any additional information, please let me know.
Regards,
Attached Files
Edited by Vegeta, 02 September 2022 - 12:34 PM.