JPS60161701A - Gas-liquid contact apparatus - Google Patents

Abstract

PURPOSE:To improve the flowing states of gas and a liquid, in a gas-liquid contact apparatus, by arranging at least two sets, each of which consists of a liquid receiving box and a liquid flooding pipe arranged in adjacent relation, at every shelf stage and flowing a liquid to the same direction on the perforated plate of each shelf stage. CONSTITUTION:A rectifying column is constituted of a cylindrical core metal 2 and a large number of shelf stages arranged in a vertical direction. The liquid 1 flowed down to a liquid receiving box 4a from a liquid flooding pipe 3a is flowed onto a perforated plate 6 and contacted with gas rising through small perforations of the perforated plate 6 from below to form a foam layer and revolved toward an outlet edge 8, while receives the action of gas-liquid contact, to be flowed into a liquid receiving box 4b' from a liquid flooding pipe 3b' and flowed down onto the perforated plate 7 of the next shelf stage 7 to be similarly revolved to a clockwise direction. Further, the liquid 12 flowed down onto a liquid receiving box 4a' through a liquid flooding pipe 3a' is flowed onto the perforated plate 6 and revolved clockwise, while receives the action of gas-liquid contact, to be flowed down to a liquid flooding pipe 3b and flowed onto the perforated plate 7 through the liquid receiving box 4b and receives the action of gas- liquid contact while revolved clockwise.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a gas-liquid contacting device having a liquid receiving box and an overflow pipe, and particularly to a gas-liquid contacting device having a liquid receiving box and an overflow pipe, and particularly to a gas-liquid contacting device on a perforated plate to exchange parts. The present invention relates to a suitable gas-liquid contact device.

[Background of the invention]

Plate columns with overflow pipes have low pressure loss, high rectification efficiency, and simple structure, so they are widely applied to gas-liquid contact operations such as rectification, distillation, and absorption. Here, we will explain using a rectification column as an example. In order to fully utilize the capacity of a rectification column with built-in trays equipped with overflow pipes,
In addition to optimizing operating conditions, it is necessary to optimize the flow of gas and liquid on the shelves. In other words, partial foaming of gas and liquid on the shelf 1 eliminates partial liquid stagnation, etc., allows the gas and liquid to flow smoothly on the shelf, and achieves ideal gas-liquid contact. is important.

Therefore, the following two points need to be paid the most attention when designing and operating a rectification column. The first is the weaving phenomenon. This phenomenon occurs when the liquid on the perforated plate directly flows down from the small holes of the perforated plate onto the perforated plate directly below without any gas-liquid contact on the perforated plate, and sufficient gas-liquid contact is not made on the perforated plate. As a result, the rectification efficiency is extremely reduced and sufficient performance cannot be achieved. The direct cause is the insufficient amount of gas rising from below the perforated plate, but there is also a closely related cause such as the diameter and pitch of the small holes provided in the perforated plate. The second is the flooding phenomenon. This is because gas and liquid come into contact with each other on the perforated plate, and the height of the foam layer that is formed becomes larger than the interval between the shelves (stage interval), and the foam layer reaches the perforated plate directly above and is formed. The liquid along with the foam layer flows back through the small holes in the upper perforated plate. When flooding occurs, it causes a decrease in rectification efficiency or an increase in pressure loss due to the accumulation of liquid on the perforated plate, and if this phenomenon continues, the rectification column becomes inoperable, resulting in the worst situation. The cause is that the amount of gas rising from below the perforated plate is too large, contrary to the above-mentioned weaving phenomenon, but there are also other factors such as the above-mentioned step spacing, hole diameter, and pitch of the perforated plate.

The structure of the shelves and the structure of the shelves are also important factors.

As the throughput of gas and liquid increases and the diameter of the rectification column increases, the problem is not only that of the increase in column diameter, but also that the thickness and depth of the liquid on the perforated plate becomes thicker. As the liquid depth increases, pressure loss increases and the height of the foam layer increases.In addition, the length from the liquid receiving box to the overflow pipe, that is, the length of the liquid flowing on the perforated plate (liquid path length) Due to the gradient of the liquid depth due to the increase in the amount of gas or the uneven flow of the rising gas amount, the gas and liquid on the trays will cause an increase in the height of the foam layer, partial foaming, or stagnation in the liquid depth, and the rectification column will be subject to flooding phenomenon. It runs and becomes unstable.

In order to prevent this flooding phenomenon, the depth of the liquid on the perforated plate is made small and uniform. It is also possible to widen the gap between the trays, but the former would complicate the structure of the trays, and the latter would result in an increase in the size of the rectification column, so both are not advisable. Although it cannot be said, the problem was avoided by unavoidably increasing the stage spacing.

As described above, the conventional technology has a problem in that a flooding phenomenon tends to occur as the amount of gas and liquid processed increases.

As is well known, shelves equipped with overflow pipes are used, and for shelves with a swirling flow system in which the liquid on the shelves flows in an arc, there is a special method depending on the throughput.

Two-way flow: There is a multi-way flow, but here we will explain the structure of the two-way flow tray.

FIG. 1 and FIG. 2 show the structure of a tray using a two-way swirling flow system, and will be described as a conventional technique. FIG. 1 shows the structure of the shelf in the vertical direction, and FIG. 2 shows the structure in the horizontal direction, which is a cross section taken along line A--A in FIG. The swirling flow type rectification column is composed of a cylindrical outer wall 1, a cylindrical mandrel 2, and several dozen trays installed at regular intervals in the vertical direction. Each shelf, for example the second shelf in FIG. 1, is comprised of a liquid receiving box 4b, an overflow pipe 3c, and a perforated plate 7 having many small holes 5. Overflow pipe 3c and liquid receiving box 4b
are located on the left and right sides of the cylindrical mandrel 2, and the perforated plate 7 is divided into left and right parts and installed with respect to the overflow pipe 3c, the liquid receiving box 4b, and the mandrel 2. Note that 6 and 9 are perforated plates, which are similar to the perforated plate 7 described above.

Liquid 1 flowing down from the top of the rectification column through the overflow pipe 3b
1 flows into the liquid receiving box 4b. Liquid receiving box 4b and overflow pipe 3
After liquid-sealing the pressure loss of the perforated plate in b, the liquid flows into the perforated plate 7. While flowing toward the outlet edge 8, the liquid flowing onto the porous plate 7 comes into contact with the gas rising from below the porous plate through the small holes 5, forming a foam layer and bringing about gas-liquid contact.

After the gas-liquid contact, the liquid passes through the outlet edge 8 and flows into the overflow pipe 3.
flows into c. As shown in FIG. 2, the flow of liquid on the perforated plate 7 is such that the liquid that has entered the liquid receiving box 4b is divided into left and right parts and flows onto the perforated plate, each drawing an arc while flowing into the overflow pipe 3C.
is flowing into the country. Next, looking at the flow of liquid in the next stage, the positions of the liquid receiving box 4c and the overflow pipe 3d are reversed in the next stage, so the flow direction of the liquid is also reversed. In other words, the flow directions of the liquid in the odd-numbered stages and the even-numbered stages are opposite. As explained above, gas-liquid contact is carried out on each shelf to exchange substances, and rectification is carried out by repeating several dozen stages.

FIG. 3 is a diagram illustrating the state of the liquid on the porous plate.

As the throughput increases and the column diameter increases, the liquid depth on the perforated plate of each tray increases, and as shown in the figure, the liquid depth near the inlet of the liquid to the perforated plate is smaller than that near the outlet. It tends to get bigger. That is, when a liquid crosses the porous plate, a difference occurs in the depth of the liquid on the porous plate due to the flow resistance of the liquid or the resistance of the foam layer. -The pressure loss of a perforated blade plate is given by the sum of dry pressure loss, pressure loss due to liquid depth, and pressure loss due to surface tension, and is constant for the same perforated plate. In other words, the drying pressure loss will be small at locations on the perforated plate where the liquid depth is large, and the opposite will occur at locations where the liquid depth is small. In other words, in areas where the liquid is deep on the perforated plate, the amount of gas rising through the small holes of the perforated plate is small, which reduces the factor that causes non-foaming (a state where there is liquid on the perforated plate and no foaming occurs). It probably contains a lot.

In the figure, the rate of gas application rising up the perforated plate 7 is greater in the downstream portion of the perforated plate than in the upstream portion.

Further, since the flow direction of the liquid in the perforated plate 6 is exactly opposite to that in the perforated plate 7, the liquid depth distribution in the perforated plate 6 and the perforated plate 7 is opposite. As the gas ascends through the perforated plate 7, it tends to flow more toward the downstream portion of the perforated plate 6 where the liquid depth is smaller. Therefore, the gas rising through the perforated plate 7 has a velocity distribution in the direction opposite to the flow direction of the liquid in the perforated plate 7. This velocity distribution provides a large resistance to flowing the foam layer formed by the perforated plate 7 into the overflow pipe. As mentioned above, unfoamed areas easily occur in the upstream part of the perforated plate, but if the unfoamed part 200 occurs in the perforated plate 7 due to operating conditions etc., the above phenomenon will become more and more severe, and the rectification column will be flooded. This may cause the vehicle to become inoperable.

As mentioned above, in the conventional technology, the drift of rising gas from below impedes the flow of the foam layer, making it difficult to maintain good gas-liquid flow. I was avoiding the problem.

[Purpose of the invention]

The present invention has been made in view of the problems of the prior art described above, and an object thereof is to provide a gas-liquid contacting device that improves the flow state of gas and liquid on a porous plate.

[Summary of the invention]

The present invention installs at least two sets of a liquid receiving box and an overflow pipe next to the liquid receiving box whose tip extends to the vicinity of the perforated plate in the lower stage in a swirling flow type shelf, and in each shelf. is characterized in that a pair of liquid receiving boxes and overflow pipes are installed offset in the same direction, so that the liquid flows on the perforated plates of each shelf in the same direction. do.

[Embodiments of the invention]

Examples of the gas-liquid contact device according to the present invention are shown in FIG.
This will be explained with reference to FIGS. 5 and 6.

Figure 4 is a vertical cross section of the rectification column, and Figure 5 is B-B in Figure 4.
The B sectional view and FIG. 6 are three-dimensional representations of the structure of the present invention. This embodiment will also be explained by taking the swirling flow two-way flow system as an example.

The rectification column is constructed by incorporating several dozen vertical stages into a cylindrical outer wall 1 and a cylindrical mandrel 2. The intermediate shelf is made of perforated plate,
It is equipped with two pairs of liquid receiving boxes and overflow pipes. That is, the - pair is the overflow pipe 3b' which is installed next to the liquid receiving box 4a' and whose tip extends to the vicinity of the perforated plate of the next shelf, and the other pair is the overflow pipe 3b' which is provided next to the liquid receiving box 4a'. This is an overflow pipe 3b similar to that described above. A perforated plate 7 having a large number of small holes is provided between these.

Thus, each shelf is provided with two liquid receiving boxes and two overflow pipes. The paired liquid receiving box and overflow pipe are installed on the left and right sides of the mandrel 2, and the liquid receiving box of the next shelf is installed directly below the overflow pipe. One side plate 6d forming each overflow pipe is installed at approximately the same position in the circumferential direction as one side plate 7d forming the overflow pipe of the next shelf. Further, the perforated plate 6 is installed so as to be divided into left and right parts with respect to the liquid receiving box 4a/and overflow pipe 3b' which are paired with the mandrel 2, and the liquid receiving box 4a and the overflow pipe 3b.

The gas-liquid contact device having such a configuration has the following functions.

The liquid 11 flowing down into the liquid receiving box 4a from the overflow pipe 3a above the rectification column performs four-liquid sealing by the liquid receiving box 4a and the overflow pipe 3a to cope with the pressure loss of the perforated plate 6.

The liquid flowing out of the liquid receiving box 4a flows onto the perforated plate 6. The liquid flowing onto the perforated plate 6 comes into contact with the gas rising from below through the small holes 5 of the perforated plate, forms a foam layer, and swirls toward the outlet edge 8 while making contact with the gas and liquid. In the embodiment, it flows clockwise) and flows into the overflow pipe 3b'. Overflow pipe 3b
The liquid 11 that has flowed into the liquid receiving box 4b' flows onto the perforated plate 7 of the next shelf, and through the same process as above, the liquid 11 flows clockwise on the perforated plate in the same manner as the previous shelf. It flows while making gas-liquid contact.

In addition, the liquid n flowing down from the upper part of the rectification column through the overflow pipe 3a' flows into the perforated plate 6 through the liquid receiving box 4a/, and is brought into contact with the liquid on the perforated plate in the same manner as described above. It swirls around and flows down into the overflow pipe 3b. The liquid flowing down into the overflow pipe 3b flows through the liquid receiving box 4b onto the perforated plate 7, flows on the perforated plate 7 while rotating clockwise as described above, and brings about gas-liquid contact.

That is, the liquid 11 and the ridges that have been divided into two parts from the top of the rectification column and flowed down to the trays are always flowing in the same direction (clockwise in this example) on the built-in perforated plate, and are brought into gas-liquid contact. .

In this example, since it is configured and operates as described above, the following effects can be achieved.

The effects of this embodiment will be explained using FIG. 7. As mentioned above, in the conventional technology, the flow direction of the liquid flowing on the perforated plate is opposite between the odd-numbered and even-numbered shelves, resulting in an increase in liquid depth due to an increase in throughput, an increase in liquid path length, etc. Increase in liquid depth upstream of the perforated plate.

In other words, due to the liquid depth distribution, etc., a biased flow of rising gas occurs from below, and a force is applied in the opposite direction to the flow direction of the foamed gas and liquid, which obstructs smooth flow and causes a biased flow of the liquid. Partial foaming and flooding of the gas and liquid above may occur, making the rectification column inoperable. On the other hand, in this example, by installing an overflow pipe next to the liquid receiving box, the flow direction of the liquid flowing on the perforated plate of each shelf can always be made in the same direction. For this reason, even if there is some liquid depth distribution on the perforated plate, the gas that rises from below through the small holes in the perforated plate will not be affected regardless of whether the liquid depth is small or large on the perforated plate. , there is no drift in the direction of its velocity, and it can always rise in a uniform direction. Therefore, the foamed liquid on the perforated plate can smoothly cross over the perforated plate.

In addition, if for some reason the area on the perforated plate where the liquid depth is high on the upstream side of the perforated plate, which is most likely to become unfoamed, becomes unfoamed,
The velocity distribution of the rising gas from below is in the direction of the overflow pipe. This velocity distribution acts as a force in the direction that promotes the flow of the liquid on the porous plate, so that the partially foamed liquid on the porous plate can be made to flow more. Therefore, partial foaming on the perforated plate can be eliminated and partial foaming is less likely to occur.

In this way, the problems of partial foaming and flooding on a perforated plate, which were problems of the prior art, can be solved, and a compact, highly reliable gas-liquid contacting device with a wide operating range can be provided.

In the above embodiment, the part that receives the liquid flowing down from the upper overflow pipe is described as a liquid receiving box, but this structure is on the same surface as the perforated plate, or an inlet weir is provided. Even if the structure is different, it is a difference in expression and is naturally included in the present invention.

〔Effect of the invention〕

According to the present invention, the flow direction of the liquid (foam layer) flowing on the perforated plate of each shelf can be made the same, so that the uneven flow of rising gas from below or the uneven flow of liquid flowing on the perforated plate It becomes possible to make noiseless noise, and the flow condition of gas and liquid becomes good. Therefore, it is possible to provide a highly reliable gas-liquid contacting device that is unlikely to cause partial foaming or flooding of the gas-liquid on the porous plate and can have a wide stable operation range.

[Brief explanation of the drawing]

FIGS. 1 to 3 are diagrams for explaining a conventional gas-liquid contact device. FIGS. 4 to 6 are diagrams showing embodiments of the present invention. FIG. 7 is a diagram for explaining the effects of the embodiment of the present invention.

Claims (1)

[Claims] 1. A tower consisting of a core metal and an outer wall covering the core metal is equipped with a plurality of trays inside, and each tray has a perforated plate with many small holes, and the liquid on the perforated plate flows into the lower stage. It consists of an overflow pipe that receives the liquid flowing down from the upper overflow pipe and supplies it to the perforated plate, and brings the rising gas into gas-liquid contact with the liquid on the perforated plate of the shelf. , a gas-liquid contact device for causing the liquid to flow while swirling, characterized in that at least two sets of the liquid receiving box and the overflow pipe are arranged adjacently to each other are installed on each shelf. Device.