JPS6136961B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a gas-liquid contact column, and relates to a structure of a gas-liquid contact column suitable for separating specific components by distillation and rectification operations. .

[Background of the invention]

In chemical equipment, porous plates have a simple structure, high gas-liquid contact efficiency, and are inexpensive, so they are widely used in various gas-liquid contact operations in the chemical industry, such as distillation, rectification, and absorption.

In addition to gas-liquid contact towers such as swirl flow type or cross-flow type gas-liquid contact towers that have been widely used as gas-liquid contact towers, multi-pass separation type gas-liquid contact towers have been devised. These exhibit the following behavior regarding the flow of liquid on the porous plate. The swirling flow method performs gas-liquid contact operations while the liquid on a perforated plate swirls, and the liquid depth is higher on the outside and lower on the inside because there is a liquid gradient toward the tower wall (outside) due to centrifugal force. (Tower diameter
(about 6mm at 400mm). In the cross-flow method, since gas blow-through has a large effect on the flow direction of the liquid, the liquid depth gradually becomes shallower as the gas-liquid contact progresses. Furthermore, in the multi-pass diversion system, the flow of liquid in the sector is unstable, making it difficult to maintain a uniform liquid depth.

When a gas-liquid contact operation is performed for each of these flow systems, the gas flows unbalanced to a portion where the liquid depth is small, causing partial foaming. On the other hand, in areas where the liquid depth is large, a so-called weeping phenomenon occurs in which the liquid weight on the porous plate and the gas pressure become unbalanced. This is a fundamental problem to be solved in order to obtain a good gas-liquid contact operation. Since there is no fundamental solution to these problems, it is important to select a perforated plate with optimal specifications that suit the conditions of use of the perforated plate. That is, if the weir height is increased and the aperture ratio of the perforated plate is decreased in order to reduce the influence of the liquid depth, the gas-liquid contact time will be increased and the weeping stop speed will also be decreased. On the other hand,
The problem of increased pressure loss in the gas-liquid contact tower arises,
This inevitably causes an increase in operating costs.

For this purpose, each part of the gas-liquid contact tower (upper tower, middle,
Although perforated plates are used depending on the characteristics of the perforated plate in the lower column and the lower column, one of the column efficiency and pressure loss had to be sacrificed. Recently, there has been a trend to use the gas-liquid contact tower mentioned above to process large amounts of liquid and gas, but on the other hand, equipment costs have been reduced by making the gas-liquid contact tower more compact, and operating costs have been reduced by reducing the pressure loss of the equipment. Reducing this has become an important issue. To this end, the challenge is to increase the foaming rate due to gas-liquid contact between the liquid on the porous plate and the gas. By increasing the foaming rate, the gas velocity can be reduced for the same column efficiency, or the column efficiency can be increased for the same pressure drop.

Currently, when designing a perforated plate, the weeping stop speed is dominant, so the gas flow rate is determined to be higher than that speed, but in this state the liquid on the perforated plate does not necessarily reach a fully foamed state. (This was confirmed in a flow experiment in a water-air system.)

[Purpose of the invention]

The present invention was made in view of the problems of the prior art described above, and its purpose is to completely foam the liquid on the perforated plate at the lower limit of the stable operation range of the perforated plate. An object of the present invention is to provide a gas-liquid contact column having higher column efficiency than the perforated plate.

[Summary of the invention]

A feature of the present invention is that a rectifying member in which a large number of gas passages are formed in the vertical direction is installed below the perforated plate at a distance from the liquid level.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. Figure 1 shows the cross-flow type shelves.
FIG. 2 is a diagram showing the installation of the rectifying member of the present invention, and is a diagram showing details and functions of the rectifying member.

The liquid that has completed gas-liquid contact from the upper shelf flows into the overflow pipe 6.
After descending further and flowing into the liquid receiving tray 2 on the perforated plate 1, it crosses the inlet weir 3 and flows out onto the perforated plate 1. On the other hand, the gas rising from the lower shelf passes through a rectifying member 4 installed at the bottom of the perforated plate 1 at a distance from the liquid level, and comes into contact with the liquid on the perforated plate 1. The high-boiling components of the liquid that have come into contact with the gas are separated from the liquid by heat exchange with the gas, and the liquid gradually becomes rich in low-boiling components. The liquid passes over the outlet weir 5 and flows down in the overflow pipe 6, and flows into the liquid receiving tray 2 on the lower shelf. Thereafter, as this operation is repeated, the liquid gradually becomes rich in low boiling point components.

FIG. 2 shows a cross section of the rectifying member 4 of the present invention, in which the hexagonal cylinder core 4A constituting the rectifying member 4 is divided into small pieces by walls, and a large number of perpendicular directions are arranged adjacent to each other in parallel. It forms a gas passage. The flow regulating member 4, which is constituted by an assembly of the cores 4A, is installed at the bottom of each shelf integrally with a perforated plate at a distance from the liquid level.

Next, its function will be explained. As mentioned above, the liquid on the porous plate 1 generates a liquid gradient peculiar to each flow method, which induces uneven flow of gas. In other words, the gas passing through the sub-holes 4B of the porous plate 1 easily flows to areas where the liquid depth is small, and becomes difficult to flow to areas where the liquid depth is large. The liquid gradient can be eliminated by tilting the perforated plate 1, but this is difficult in practice because the exact value of the gradient is not clear due to the relationship between each flow system, liquid amount, and column diameter.

Another problem revealed by the flow experiments in the water-air system is that the foamed portion constantly moves on the perforated plate 1, resulting in a lack of reproducibility. This phenomenon occurs when the gas flow rate and liquid volume are set constant in a partially foamed state, and the cause is unknown. If we speculate about this phenomenon, it is thought that the flow state of the gas within the tray is extremely unstable and is flowing in a kind of turbulent state.

As the gas flow rate is gradually increased, the liquid on the perforated plate becomes completely foamy, but if the gas flow rate at that time (velocity through the holes) is approximately 8 m/s, conversely, the gas speed should be increased to 8 m/s. If you gradually lower it from
It has been confirmed through experiments that the entire surface is foamed even at speeds of about 5 m/s. This means that once the gas flow state is stabilized, the entire surface can be foamed even at a lower gas flow rate. To this end, it is important to stabilize the gas flow state between the trays at a low gas flow rate.

As can be seen from the above, in order to stabilize the flow state of gas at the bottom of the perforated plate 1, if the rectifying member 4 is installed at the bottom of the perforated plate 1 with a distance from the liquid level, the rising gas will be After gas-liquid contact on the lower perforated plate 1, the liquid is merged and is rectified by the rectifying member 4 before passing through the upper perforated plate 1, so that it can pass through the subholes 4B of the perforated plate 1 in a stable flow state. Full foaming can occur at lower gas flow rates.

According to this embodiment, the liquid on the perforated plate is completely foamed at a lower gas velocity, so that the column efficiency is increased. Therefore, the number of trays is reduced and the manufacturing cost of the contact tower can be reduced. Furthermore, since the gas flow rate during operation is low, the operating cost (power consumption of the compressor) is reduced.

In the above-mentioned embodiment, the flow regulating member 4 is made up of an assembly of hexagonal cylinder cores 4A, but it is also possible to form a large number of vertical gas passages using a cylinder of any shape or a partition plate. Even if a rectifying member is configured, the same effects as described above can be obtained.

〔Effect of the invention〕

According to the present invention, the liquid on the perforated plate can be completely foamed at a lower gas velocity when passing through the perforated plate, so that pressure loss in the contact tower can be reduced. Furthermore, since higher column efficiency can be obtained at the same gas velocity, the manufacturing and operating costs of the column can be reduced. That is, a low pressure loss type, highly efficient gas-liquid contact tower can be provided at low cost.

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment of the gas-liquid contact tower according to the present invention. Figure 1 is a longitudinal cross-sectional view, and Figure 2 is a detailed view of a tray in which a perforated plate and a rectifying member are integrated. FIG. 1... Perforated plate, 2... Liquid receiver, 3... Inlet weir,
4... Rectifying member, 4A... Core, 4B... Child hole,
5... Outlet weir, 6... Overflow pipe.

Claims (1)

[Claims] 1 Each of the plurality of trays installed inside the gas-liquid contact tower is composed of a perforated plate having a large number of holes, and the liquid is sequentially introduced onto the perforated plate from the top to the bottom, and the gas is introduced from the bottom. In a gas-liquid contact tower that is raised above the holes of the perforated plate to perform gas-liquid contact on each perforated plate, a rectifying member having a large number of gas passages vertically formed in the lower part of the perforated plate is placed at a distance from the liquid level. A gas-liquid contact tower characterized in that it is installed with.