In the solvent regeneration tower, the gas phase returning to the column has a high temperature while the bottom temperature is low
Thread Content
I seek advice from experts: In my company’s solvent regeneration unit, the normal temperature of the vapor returning to the tower in the bottom reboiler (batch type) is 120°C, and the temperature at the bottom of the tower is also between 119–120°C. However, after some time, the temperature of the vapor returning to the tower rises above 125°C (even when no operations are being carried out), while the temperature at the bottom of the tower drops to 116°C (and continues to drop without any operations). This results in the effluent fluid not meeting the required standards. Raising the liquid level at the bottom of the tower to 70% helps to improve the situation. I believe that the high steam temperature or excessive steam volume in the reboiler at the bottom of the solvent regeneration tower is causing an excessive evaporation rate in the kettle-type reboiler; as a result, the vapor cannot return to the tower in time, leading to vapor blockage! ! Because I have installed a temperature-reducing pressure regulator, which keeps the temperature at the point where the 0.4 steam enters the device at 140°C; the entire section of the pipeline carrying the 0.4 steam, including its jacket, has a temperature of 140°C as well. The lean liquid does not foam on its own, and the thermally stable salts do not cause blockages in the normal trays.
Based on your description, it is possible that the high steam temperature or excessive steam volume in the reboiler at the bottom of the solvent regeneration tower is causing an excessive evaporation rate in the kettle-type reboiler; as a result, the vapor cannot return to the tower in time, leading to vapor blockage. You can try reducing the steam temperature in the reboiler or decreasing the amount of steam, and adjust the liquid level to achieve an appropriate vapor-liquid ratio, in order to maintain stable temperatures at the bottom of the tower and in the gas phase returning to the tower. At the same time, check the connection pipes between the reboiler and the return column for any accumulation of liquid or other blockages. .
The vapor phase temperature is the temperature of the vapor phase returning to the column in the solvent reboiler
Yes, the vapor phase temperature refers to the temperature of the vapor phase returning to the column in the solvent reboiler. In your case, an increase in the vapor return temperature and a decrease in the bottom temperature may indicate a pipe blockage, such as the vapor blockage you mentioned. It is recommended to promptly check the pipes for any accumulation of liquid, deposits, or other blockages, and to clean and maintain them. At the same time, ensure that the operating conditions of the equipment meet the design requirements; in particular, parameters such as steam temperature and steam volume should be kept within appropriate ranges. .
The driving force of thermal siphon is insufficient; it can raise the liquid level!
This post was last edited by cust008 on 2023-4-4 11:21. A decrease in the temperature at the bottom of the tower indicates that the light components have settled. It might be that the upward-moving gas in the tower carries insufficient heat; this heat depends not only on the temperature of the gas but also on its volume. A low liquid level at the bottom of the tower can lead to a decrease in the flow rate from the bottom of the tower to the reboiler and back again, which in turn causes the temperature returning to the tower to rise; however, the product of temperature and flow rate decreases. One possible reason for this situation is manual control, resulting in excessive extraction from the bottom of the tower; this disrupts the material balance and causes the liquid level to keep dropping ； Another possibility is that the PID parameters of the instrument are not set correctly ； One possibility is that the liquid level setpoint is too low.
Thank you for the reply! I’m unable to determine the amount of gas at the moment. I’ll take another look at the rest
It is recommended to use a control scheme with PID diagrams, as this provides more comprehensive information and enables more accurate analysis