How to stabilize the diesel reforming and fractionation system?
Thread Content
I have just started working in a position related to the operation of a distillation unit that has been modified for diesel processing. I’m having trouble getting the liquid level in this distillation tower under control; in winter, the level gauges sometimes don’t give accurate readings. I would like some advice: 1. If the liquid level at the bottom of the distillation tower increases, should I increase the frequency of the pump used to transfer diesel out, or adjust the valve used to control the liquid level there, or both? 2. If the amount of diesel transferred out remains unchanged but the liquid level at the bottom of the tower decreases, should I close the valve used to control that liquid level? If I reduce the amount of material sent for delivery, it will lead to further decreases, which in turn affects the balance of the stabilizer system; once this vicious cycle starts, I won’t be able to make many adjustments. 3. If the liquid level in the reflux tank at the top of the distillation tower drops, what is my main approach? If the reflux control valve is closed, the low temperature in the distillation column will rise again. If the stabilizing control valve is closed, the gasoline output will decrease by 4 units again. What is the main method used to control the level of the liquid in the reflux tank at the top of the fractionation tower? 5- What is the relationship between the temperature after cooling at the top of the fractionation tower and the liquid level in the fractionation reflux tank? Does an increase in the temperature after cooling lead to an increase or decrease in the liquid level? Thank you everyone; the alarms in the control room have been going off non-stop these past couple of days, which has left me very confused
This is a typical level-flow cascade control system, with the liquid level serving as the primary control parameter. In actual operation, the level valve should be kept fully open, and the frequency of the pump should be adjusted to maintain a stable liquid level.
However, the frequency conversion of the pump affects the efficiency of diesel delivery, which in turn impacts the anti-wear agent
Bro, it seems like most of your questions are about liquid levels. The tower liquid level is primarily adjusted automatically by control valves; to prevent excessive valve opening angles that could cause pressure buildup in the heat exchanger, variable frequency control is also used. The liquid level in the reflux tank is also mainly adjusted using control valves. The top of the tower temperature is used to adjust product quality; it has an impact on the liquid level in the reflux tank, but the liquid level cannot be adjusted using the top of the tower temperature. All indicators, including the liquid level, are part of a dynamic balance; when the flow rate increases, the liquid level naturally rises, and in that case valves need to be opened to lower the liquid level. However, there are many reasons for an increase in flow rate, such as the processing volume, the properties of the raw materials, as well as the temperature and pressure at the top of the tower. These are merely factors that influence the situation and cannot be used as means to control the liquid level; ultimately, it is still necessary to rely on control valves. An unstable liquid level may also be due to poor tracking by the control valve, and it is necessary to adjust the PID parameters.
I understand your answer, but the liquid level control valve in this distillation tower sometimes doesn’t work properly in winter; the liquid level cannot be reflected in real time. Sometimes the response is slow, and when the liquid level drops, the amount of diesel sent out also decreases. As a result, I adjust the liquid level valve, which in turn leads to an even lower amount of diesel being sent out, creating a vicious cycle. Eventually, the distillation system breaks down, and it’s really frustrating
Is there variation in the weight of your feed components? Adjust the PID of the control valve
Under theoretical subcooling, the temperature is low, the liquid level rises, and less gas is discharged
Okay, I’ve also noticed recently that the liquid level in the reflux tank fluctuates. I’ll check the pressure from time to time; this is too complicated
Adjust Pid gradually; internal operations still need to be learned! Master the fundamentals; don’t be afraid to be active – know exactly what changes occur when you take action
Having heard you say so much, during the adjustment process, have you observed any changes in stress? Compare the liquid level at the bottom of the tower with the tower pressure; first stabilize the tower pressure, as if the tower pressure cannot be stabilized, the liquid level will fluctuate along with it. Once the tower pressure is stabilized, adjusting the material balance will also lead to stability.