Heat bypass pressure of the stabilizer tower
Thread Content
Currently, the pressure in the thermal bypass of the stabilizer is starting to fluctuate; as shown in the graph, these fluctuations are regular in pattern. Adjusting the PID settings has no effect. The reflux ratio is currently around 2.0, the bottom temperature is 173 degrees, and the temperature of the sensitive plate is 95 degrees (this value has increased from 75 due to a higher amount of diesel being reprocessed; it’s not clear whether foam formation or liquid slugging could occur). The top pressure also fluctuates in this manner. I seek detailed explanations from experts
Do you think this range of fluctuations is large? Fluctuations within the 0.9 range are considered normal, and it’s clear that after adjusting the PID, the amplitude of these fluctuations has decreased significantly; from the perspective of adjustments alone, this is quite good! But remember that the control criterion for liquid hydrocarbons here is that C5 should not exceed 1%; your level is on the high side. Generally, increasing the reflux slightly within the acceptable range will suffice. If the situation doesn’t improve, it will be necessary to consider reducing the temperature of the bottom reboiler, thereby reducing the drive for heavier components to move upward.
Keep the flow rate stable, move the valve to the manual position, and check whether there are any pressure fluctuations; if so, it indicates a process issue