Liquid level control problem of the tower
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This post was last edited by liuguogang29 on 2009-8-23 at 19:45. I have just started working in the oil refining industry and would like to ask about level control in towers: the difference between level control based on feed rate and level control based on draw rate. Additionally, in some of our units, the liquid level control for certain towers is based on the feed rate, while it is controlled by the withdrawal rate in others. How can this be explained? ? Additional note: It is a lubricating oil hydrogenation unit. For the tower from which kerosene and diesel are extracted, the liquid level is controlled based on the feed rate; for the tower from which lubricating oil is extracted, the level is controlled based on the extraction rate. The main product of this unit is lubricating oil.
Controlling the liquid level by the extraction volume results in stability, while controlling it by the feed volume leads to instability in the liquid level, which can affect the operation of the tower and the quality of the product.
In our plant, the liquid level control of some towers is based on the feed rate, while that of others is controlled by the withdrawal rate. How can this be explained? ? 2# 735552612
It’s my personal understanding: some towers are controlled based on the feed rate; perhaps their function is to act as a buffer tank. Those that are controlled by the withdrawal rate, on the other hand, are part of the output system and are related to product quality issues.
The liquid level in the tower is usually controlled by the discharge rate. To ensure stable operation of the tower, its feed rate should be relatively constant; this makes it easier to maintain stability in the temperatures at the bottom and top of the tower as well as in the reflux rate. Additionally, it is convenient to keep the tower’s feed rate consistent with that of previous production processes. Using the tower’s feed rate to control the liquid level may be necessary due to specific requirements of your process.
Generally, the feed flow is controlled, while the discharge level is controlled. Feeding control using level regulation is relatively rare; this type of control may be employed in some less critical applications where the upstream equipment has less stringent requirements regarding the amount of material.
Generally speaking, controlling the liquid level using the extraction rate of a tower equipped with a product outlet is beneficial for regulating product quality. Towers that control the level using feed volume generally serve as a feed pre-treatment or buffering mechanism.
When it’s unstable, use manual stabilization; otherwise use automatic mode. Generally, keep the liquid level between 30% and 60%. 1# liuguogang29
I’ve never seen feed rate used to control the liquid level; it’s probably employed in liquid closed-loop systems. Given the losses that occur during such closed-loop circulation, it’s necessary to replenish the liquid level. Level is generally controlled by the extraction volume.
Please state on the first floor exactly what devices they are, which ones are for feed control and which ones for discharge control, so that an analysis can be carried out! The liquid levels of the coking and catalytic feed tanks are controlled based on feed rates, while those of the other tanks are controlled based on discharge rates.
1. Using the extraction volume to control the liquid level has many advantages: the liquid level is maintained more stably, it has little impact on the operation of the tower, and it facilitates the control of product quality. 2. Towers that use feed rate to control the liquid level are relatively rare; they are more commonly used in raw material buffer tanks. The disadvantage is that the liquid level is difficult to stabilize, and it also has a significant impact on the operation of the tower.