The temperature of the reflux gas from the constant-pressure reboiler to the stripping tower fluctuates and cannot be stabilized! Seeking help from friends in Sichuan
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As shown in the figure, the two control valves A and B fail to reach an equilibrium point; the temperature of tc16307 fluctuates between 218 degrees and 240 degrees. When it reaches 240 degrees, the level of T211 suddenly reaches its maximum value, before dropping rapidly to 10 percent. The temperature of 16307 also drops to 218 degrees, and the temperature inside the tower changes as well. How to adjust to stabilize the operation of the reboiler? Urgent!
There may be abnormalities in the TI 16109 temperature and the LC16301 liquid control valve position. Changing to manual mode “M” can provide some relief.
I personally also think that manual control requires gaining experience through trial and error
Change valves A and B to manual mode to stabilize the three-line flow rate, then gradually adjust the reboiler outlet temperature until it is stable, and afterward switch back to automatic mode; if that doesn’t work, adjust the PID parameters.
In our company’s 5-million-ton atmospheric pressure plant, the flash point of Line 1 fluctuates; we mainly use Line 3 as a heat source, and there are fluctuations in the temperature at the outlet of the reboiler. This leads to unstable liquid levels in the stripping tower, so we control the liquid level at around 80-90% to keep the flash point of Line 1 stable. It is recommended to try raising the liquid level in the primary stripping tower.
Adjust the PID; when controlling temperature, the appropriate D value must be taken into consideration
Is the normal primary line level control a bit too low? When the liquid level is low, a certain gas resistance is generated after the material from the primary line enters the reboiler and vaporizes; this leads to fluctuations in the amount of material entering the reboiler via the primary line, and as a result, significant fluctuations in the temperature returning to the tower occur
It is recommended to use a slightly lower heat source but keep it steady, and adjust the liquid level to maintain it at a high level.