The pressure difference in the distillation tower increases

At atmospheric pressure? ? Reduce pressure? ? ? When the pressure difference is large, a positive pressure indicates an excess amount of gas, resulting in an increase in pressure. In the case of negative pressure, a large pressure difference means there is less gas present. Think for yourself which one it is!

Based on the increase in differential pressure you mentioned, it is likely caused by poor airflow, an excess of liquid phase, a blocked downcomer, a blocked distillation hole, or insufficient air supply

A pressure difference can be considered to have increased only when the liquid phase expands while the gas phase remains unchanged; if the gas phase expands while the liquid phase stays the same, the pressure difference increases. Therefore, it is not possible to determine whether it is the liquid phase or the gas phase that has expanded based on just the pressure difference parameter

There is too much liquid phase, and flooding may occur

1. A large pressure difference is usually caused by poor flow in the downcomer, which leads to liquid accumulation and an increase in the liquid layer thickness on the tray, thereby raising the pressure difference. Or the liquid falling area of the tower is insufficient, leading to material accumulation. 2. Excessive feed, which exceeds the tower’s capacity, leads to severe accumulation of material inside the tower, and this as well can cause an increase in pressure difference.

The pressure drop across the plates of a plate tower is divided into two parts: Hc + Hl. Hc represents the pressure drop due to the dry plates, while Hl represents the resistance encountered by the gas as it passes through the liquid layer. For detailed calculations of Hc and Hl, refer to the book \"Tower Equipment\" authored by Lu Xiulin et al., or Henry Kister’s \"Distillation Design\". What Teacher Lu and the others are compiling is much more detailed. For the pressure drop in packed towers, correlation equations are still primarily used; these equations vary significantly from one another, and their underlying assumptions also differ. For more details, see Kister or Wang Shuying’s \"Guide to Modern Packing Tower Technology.\" Ultimately, whether it is tray towers or packing towers, the fundamental reason for changes in pressure drop lies in the flow behavior of the vapor-liquid phases within a certain geometric structure; this constitutes a type of two-phase flow under specific conditions. Due to the complexity of two-phase flow problems themselves, it is conceivable that the pressure drop under the vapor-liquid flow conditions in tray packings is also difficult to describe completely and rigorously from a theoretical perspective. But qualitatively, it can be said that within the normal operating range of the tower, under certain flow conditions, as the gas velocity increases, the pressure drop also increases ； Under certain gas flow rates, an increase in liquid flow rate leads to an increase in pressure difference. In recent years, thanks to the rapid development of computational fluid dynamics (CFD), it has become possible to use CFD methods to simulate fluid flow in trays or packing. However, this is only the beginning; much work still needs to be done to determine whether it can ultimately be utilized in the development of new types of trays and packing. Due to space constraints, only a brief discussion can be provided; this is for reference only.

Which specific tower is it? Packed tower or plate tower?

There are various reasons that can cause an increase in the pressure drop in a distillation column; it cannot be simply attributed to an increase in the liquid phase or an increase in the gas phase. Generally, the reasons for an increase in the pressure drop in a distillation column are as follows: 1. An increase in the feed rate, which exceeds the separation capacity of the distillation column. 2. The reflux flow rate of the distillation column is too high. 3. The vapor-liquid flow channel is obstructed or blocked. 4. Liquid flooding.

Let’s see how the distillation efficiency of the distillation column changes after the differential pressure increases If the performance deteriorates, it indicates that flooding has occurred; in such a case, it is necessary to reduce the processing load of the distillation tower, and then determine the cause of the flooding – whether it is due to a clogged downcomer or an instrument failure that has led to overloading. If the distillation efficiency remains unchanged after the differential pressure increases, it indicates that there is a problem with the pressure gauge; replacing the pressure gauge will resolve the issue.

Under normal circumstances, if the pressure difference increases, it means that both the gas phase and the liquid phase should experience a corresponding increase

This question is quite general; if the material tends to coking, for example, then blockages in the filler can lead to a decrease in steam velocity and an increase in pressure difference. The specific situation needs to be analyzed on a case-by-case basis!

The pressure difference increases, the liquid phase increases, and the solution overflows