JPH05237303A - Gas-liquid contacting device - Google Patents

Abstract

PURPOSE:To provide a gas-liquid contacting device where vapor-liquid contact is properly maintained and pressure drop is small and it is hard for weeping to happen and which has a wide operating range by providing a structure where small holes are opened along the flow direction of liquid of a perforated plate and the small holes having a slant hole to the plate thickness direction is provided. CONSTITUTION:Since the small holes 6 are opened along the flow direction of liquid 3 on a perforated plate 2, the flow of an ascending gas 4 from below the perforated plate 2 turns in the direction along the flow direction of the liquid 3 on the way of pass through the perforated plate 2 and comes into contact with the liquid 3 and ascends. At this time, by small holes 6 in the shape of a slant hole, kinematic energy of the gas effectively acts force for the liquid 3 on the perforated plate to smoothly flow to prevent more residence of the liquid 3 than required, causing the thickness of liquid seal on the perforated plate 3 to be decreased. Therefore pressure drop is reduced, good gas-liquid contact is performed, weeping become unlikely to happen and a operating range is widened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION A gas-liquid contactor (perforated plate) having an overflow pipe has a simple structure and is widely used in a gas-liquid contactor in the chemical industry such as distillation, rectification and absorption. The present invention is
In particular, it relates to a device for liquefying air and separating nitrogen, oxygen and argon from the air by a rectification operation.

[0002]

2. Description of the Related Art Conventional techniques of gas-liquid contactors include, for example, "a gas-liquid contactor" described in JP-A-56-33005 and "a liquid and a vapor" described in JP-B-42-4568. There is a shelf to contact. " Since the liquid flowing on the perforated plate while contacting with the gas is a free flow due to gravity, the liquid height on the perforated plate has a distribution depending on the position of the perforated plate. In these inventions, in order to make this distribution constant, the perforated plate is inclined according to the difference in liquid height and attached to the rectification column to keep the liquid height distribution almost constant and to achieve good gas-liquid contact. It is something to do. Alternatively, a part of the upstream side of the perforated plate is inclined so that the vapor is blown out to the downstream side of the perforated plate to perform gas-liquid contact. The small holes of these conventional perforated plates have a structure that is opened at a right angle to the horizontal direction of the perforated plate and the ascending gas rises in the direction perpendicular to the perforated plate.

[0003]

In the air separation device, since air is liquefied for rectification, it is necessary to compress the air at atmospheric pressure to about 0.5 MPa with an air compressor or the like. On the other hand, the oxygen gas or liquid oxygen that is recovered as a product outside is at about atmospheric pressure, so the pressure loss of the perforated plate that is installed in the rectification column in order to perform the rectification action remains unchanged. Since it affects the power consumption of the air compressor, it is no exaggeration to say that the discharge pressure of the air compressor represents the performance of the air separation device. It is necessary to optimize the flow of gas and liquid on the perforated plate in order to fully exhibit the capability of the rectification column having the perforated plate. Further, the pressure loss of the rectification tower has a great influence on the power consumption of the air compressor and the like, and therefore it is desirable to minimize the pressure loss. The small holes of the perforated plate are opened by punching or the like. The pressure loss at this time is, for example,
It is estimated by the sum of the dry pressure loss, the pressure loss due to the liquid seal, and the pressure loss due to the surface tension, as described in the document "Distillation Engineering Handbook". In order to reduce each pressure loss, there are a method of increasing the diameter of the small holes of the perforated plate, a method of inclining the perforated plate to reduce the thickness of the liquid seal, and the like. However, since a perforated plate used in an air separation device or the like is required to have high rectification efficiency, increasing the pore size causes weeping, partial foaming of gas and liquid, and lowers rectification efficiency. If the perforated plate is tilted and incorporated into the rectification column, its structure is difficult, and there is a possibility that the cost of the device will increase.

An object of the present invention is to provide a gas-liquid contactor which maintains good gas-liquid contact on a perforated plate, has a small pressure loss, is less likely to cause weeping, and has a wide operating range of the rectification column. Is.

[0005]

The above object can be achieved by providing a perforated plate which has a small pressure loss and is less likely to cause weeping. In the present invention,
The small holes of the perforated plate, which are opened in the thin plate by means such as punching or plastic working, are installed along the flow direction of the liquid with respect to at least the plate thickness of the perforated plate, or the same small holes form the perforated plate. The lower surface and the upper surface have a positional difference in the vertical direction of the perforated plate, and at least the openings of the small holes of the perforated plate have a structure along the flow direction of the liquid. That is, small holes are opened in the plate thickness direction of the perforated plate at least along the flow direction of the liquid, and the small holes of the perforated plate are substantially perpendicular to the perforated plate, that is, with respect to the plate thickness direction. This is a perforated plate having a structure having small holes.

[0006]

As described in the previous section, there are methods of reducing the pressure loss of the perforated plate, such as a method of enlarging the small holes of the perforated plate and a method of reducing the thickness of the liquid seal on the perforated plate. In particular, it relates to a method for reducing the thickness of the liquid seal on the porous plate. When gas and liquid are in gas-liquid contact on the perforated plate, the rising gas from below the perforated plate has energy given by an air compressor or the like, that is, kinetic energy, and vertically crosses the perforated plate and rises upward. On the other hand, the liquid flowing into the perforated plate flows into the perforated plate from the overflow pipe of the upper perforated plate, crosses the perforated plate by the natural flow due to gravity, that is, the liquid gradient generated on the perforated plate, and overflows. It flows into the perforated plate below the flow tube. Gas-liquid contact is made with this gas and liquid on the perforated plate. That is, gas-liquid contact is performed between the gas having kinetic energy and the liquid that naturally flows due to gravity. In this case, the flow of the liquid on the perforated plate is a free flow due to the gravity of the liquid, so when it comes into gas-liquid contact with the rising gas from below, the upward flow of this rising gas causes the gas to become a screen on the liquid flow. , Is an obstacle for the liquid to smoothly flow through the perforated plate. In other words, due to the obstruction of the gas that rises up the small holes of the perforated plate, the liquid cannot flow smoothly through the perforated plate, the liquid stays on the perforated plate more than necessary, and the liquid seal on the perforated plate becomes thicker, resulting in pressure loss. As a result, the kinetic energy of gas is not effectively acted on the perforated plate. In Japanese Patent Publication No. 42-4568, a part of the upstream side of the perforated plate is installed so as to be inclined, and a part of vapor from below is blown out toward the downstream side of the perforated plate for gas-liquid contact. The small holes opened in the perforated plate have a structure in which they are opened vertically to the perforated plate which has been conventionally performed. Further, in the invention, a part of the upstream side of the perforated plate is inclined together with the perforated plate to blow out the vapor toward the downstream side of the perforated plate, and the flow of the liquid in the part is taken into consideration. No consideration is given to flow.

In the present invention, the flow of liquid on the perforated plate is considered for the entire perforated plate. Part of the action of reducing the pressure loss by opening small holes along the flow direction of the liquid on the perforated plate and substantially raising the rising gas along the flow direction of the liquid is, for example, a pipeline. This is possible by considering the resistance coefficient of the elements, that is, the energy characteristics of the fluid branching and merging pipes, while the force that causes the liquid to flow due to part of the kinetic energy of the gas is the action that pushes the liquid downstream of the perforated plate. I will provide a. By effectively applying this kinetic energy to the entire porous plate, the pressure loss can be reduced. The small holes of the perforated plate in the present invention are opened along the flow direction of the liquid, and the portion having the small holes substantially in the shape of the oblique hole has the effect of effectively acting this kinetic energy. Due to the small holes in the shape of the oblique holes, the kinetic energy of the gas effectively acts on the force for the liquid on the perforated plate to smoothly flow, and it is possible to prevent the liquid from staying more than necessary. It has the effect of reducing the thickness of the seal. That is, the small holes in the shape of oblique holes have the effect of effectively changing the kinetic energy of the rising gas into the smooth flow of liquid and the energy of contact between gas and liquid, with a small pressure loss and good gas-liquid flow. With this, it is possible to provide a gas-liquid contact device capable of performing gas-liquid contact. Moreover, the weeping in which the liquid descending from the perforated plate falls directly from the small holes of the perforated plate onto the lower perforated plate without passing through the overflow pipe, has a bad influence on the rectification efficiency. The fact that the operating range of the rectification column can be widened is to provide a perforated plate in which weeping does not easily occur. The presence or absence of weeping is determined by the shape of the small holes and the thickness of the liquid seal on the perforated plate. According to the present invention, since the thickness of the liquid seal can be reduced, weeping is less likely to occur and the operation range can be widened.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

The shape of the rectification column incorporating the perforated plate differs depending on the flow direction of the liquid on the perforated plate. Here, the rectification column has a structure in which the liquid flows across the perforated plate. Describes the composition of air. Figure 1
The perspective view of the rectification column which incorporated the perforated plate of one Example of this invention is shown. FIG. 2 shows a cross-sectional view of a perforated plate according to one embodiment of the present invention. In FIG. 1, several tens of stages of the perforated plate 2 are incorporated in the rectification column 1. On the perforated plate 2, the liquid 3 flows from above, and on the perforated plate 2 from upstream to downstream, while the gas 4 rises from below, and the gas 4 and the liquid 3 come into gas-liquid contact with each other on the perforated plate 2. , Air components are separated. The gas contacted with gas and liquid rises and flows into the upper porous plate 2.
The liquid 3 passes through the weir 5, the overflow pipe 6, and the lower porous plate 2
Flow into. This operation is repeated for several tens of stages to finally separate nitrogen above the rectification column and oxygen below. When the gas passes through the perforated plate one step, a pressure loss occurs, and this pressure loss leads to a load on the air compressor, which affects the performance of the air separation device. FIG. 2 shows a sectional view of the perforated plate of the first embodiment of the present invention. In FIG. 2, the liquid 3 flows from the upstream side of the perforated plate 2 onto the perforated plate, and the gas 4 flows into the perforated plate from below. Small holes 6 are regularly opened in the perforated plate 2, and the gas 4 and the liquid 3 make gas-liquid contact on the perforated plate. Small hole 6
Has a structure that is opened along the flow direction of the liquid on the perforated plate 2, so that the flow of the rising gas from below the perforated plate is along the flow direction of the liquid while passing through the perforated plate. And comes into contact with the liquid and rises. For this reason,
A part of the kinetic energy of the rising gas is converted into a force that causes the liquid 3 on the porous plate to flow from the upstream side to the downstream side of the porous plate. Therefore, the liquid 3 which is a natural flow due to gravity
Since a force that pushes the liquid toward the downstream side of the perforated plate acts on the perforated plate, the liquid cannot be retained more than necessary on the perforated plate, and stable gas-liquid contact is possible with less pressure loss. FIG. 3 shows a detailed view of the small holes of the perforated plate of the first embodiment of the present invention. Opening 7
Has a substantially triangular shape, the direction of which is along the flow direction of the liquid. There is a protrusion 10 on the upper part of the small hole 6,
These small holes are manufactured by, for example, plastic working. The ascending gas 4 from below the perforated plate flows into the perforated plate through the small holes 6,
It rises along the inner surface 11 of the protrusion 10 and flows out of the opening 7 to make gas-liquid contact. FIG. 4 shows a plan view of the perforated plate according to the first embodiment of the present invention. In this embodiment, the small holes having the openings shown in FIG. 3 are regularly opened, and the openings are always arranged along the flow direction 3 of the liquid on the perforated plate.
FIG. 5 shows a sectional view of a perforated plate according to the second embodiment of the present invention. In this embodiment, the cross section of the small holes 6 of the porous plate 2 perpendicular to the longitudinal direction is circular, and the opening direction is at least along the liquid flow direction. Therefore, liquid 3
The cross section of the small hole at the gas-liquid contact portion is of an elliptical shape. That is, the circular small holes are opened in the plate thickness direction of the perforated plate along the flow direction of the liquid. The effect of this embodiment is equivalent to that of the first embodiment of the present invention, but according to this embodiment, since there is no protrusion on the upper surface of the porous plate, the liquid can be smoothly flowed, Further, pressure loss can be reduced, and good gas-liquid contact can be achieved. FIG. 6 shows a plan view of a perforated plate according to the second embodiment of the present invention. Also in this embodiment, the small holes 6 are regularly opened, and the opening direction is always along the flow direction of the liquid on the perforated plate. The opening is elliptical. The small holes in this embodiment can be opened by punching or the like. FIG. 7 shows a sectional view of a perforated plate according to the third embodiment of the present invention. In the perforated plate 2 in this embodiment, at least two perforated plates 9 each having a small hole 6 opened perpendicularly to the perforated plate and at least two perforated plates 10 having the small holes 8 are displaced in the liquid flow direction. It has a structure in which the small holes of the perforated plate are opened substantially along the flow direction of the liquid. The effect of this embodiment is
This is equivalent to the first and second embodiments of the present invention. Although the present embodiment has a structure in which perforated plates having the same small holes are stacked, the same effect can be obtained by stacking perforated plates having different small holes. Further, it is also possible to install the perforated plate and the perforated plate through a gap, and these structures are no different from those of the present patent. It is also possible to construct a perforated plate by combining the perforated plates of the first to third embodiments of the present invention. FIG. 8 shows a plan view of a perforated plate according to the third embodiment of the present invention. Also in this embodiment, the small holes 6 are regularly opened, and the opening direction is always along the flow direction of the liquid on the perforated plate.

In the present invention, the small holes have a structure opened along the flow direction of the liquid, and the angle is at least 0 ° to 90 ° with respect to the perforated plate, and preferably 3
It is 0 ° to 60 °. On the other hand, on at least one of the upper surface, the lower surface, or the upper and lower surfaces of the perforated plate, by providing an opening with a hole diameter different from that of the small hole at the end of the small hole,
By rounding or chamfering the ends of the small holes, a smoother gas-liquid flow can be achieved.

FIG. 9 shows a sectional view of a rectification column according to a fourth embodiment of the present invention. The present embodiment is an invention relating to the incorporation of the perforated plate of the first to third embodiments of the present invention into the rectification column.
In FIG. 9, the liquid flows into the perforated plate 2 from the overflow pipe 5, comes into gas-liquid contact with the rising gas 4 from below, and flows into the perforated plate below the overflow pipe 5. The small holes of the perforated plate 2 in the present embodiment are oblique holes with respect to the perforated plate, and the openings are opened at least along the flow direction of the liquid. The oblique porosity, that is, the inclination of the perforated plate with respect to the horizontal direction is characterized in that the upstream part of the perforated plate is smaller and the downstream part is larger, and is composed of at least two kinds of small holes with oblique porosity. .. According to the present embodiment, since the small holes having different obliqueness are combined, the force for flowing the liquid is large in the upstream part of the perforated plate having the largest thickness of the liquid seal on the perforated plate and small in the downstream part. can do. Therefore, since the thickness of the liquid seal on the perforated plate can be made more uniform, the pressure loss is small and good gas-liquid contact can be provided.
FIG. 10 shows a sectional view of a rectification column according to a fifth embodiment of the present invention. The flow of rising gas and liquid is the same as in the fourth embodiment. The present embodiment is characterized in that it is constituted by at least two kinds of small holes having oblique porosity in the direction from the upstream part to the downstream part of the perforated plate and in the direction perpendicular to the direction. In this embodiment, since it is possible to provide a perforated plate in which small holes with different oblique porosity are installed at optimal positions, it is possible to make the thickness of the liquid seal on the perforated plate more uniform and to provide optimum gas-liquid contact. can do. In the fourth and fifth embodiments, at least one kind of perforated plates composed of at least two kinds of small pores with oblique porosity is the same as the perforated plates of the first to third embodiments of the present invention. In addition, at least one kind of perforated plate having no inclination with respect to the horizontal direction of the perforated plate, that is, a perforated plate that is opened perpendicularly to the horizontal direction of the conventionally used perforated plate can be used.

According to this embodiment, since the porous plate has the structure having the small holes opened along the flow direction of the liquid on the porous plate, the pressure loss is particularly small, and good gas-liquid contact can be obtained. In addition, it is possible to provide a perforated plate which has a wide driving operation. The effect of the present invention will be described with reference to FIG. 11 by taking an example of pressure loss. The present invention is the result of a water-air system using air as the rising gas and water as the liquid. The horizontal axis shows the air flow rate and the vertical axis shows the pressure loss. The conventional perforated plate has a structure in which small holes are opened at right angles to the horizontal direction of the perforated plate, and the ascending gas rises in the direction perpendicular to the perforated plate. The perforated plate of the present invention of Example 1 and Example 2. The structure has small holes with different obliqueness. From this example, it is understood that the reduction of pressure loss is remarkable in the porous plate according to the present invention. Further, the foaming state by visual observation was also good, and good gas-liquid contact was obtained.

[0013]

According to the present invention, a porous plate having a structure having small holes opened along the flow direction of the liquid on the porous plate can achieve good gas-liquid contact with less pressure loss. In addition, there is an effect that it is possible to provide a perforated plate that can be widely operated.

[Brief description of drawings]

FIG. 1 is a perspective view of a rectification column incorporating a perforated plate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a perforated plate according to an embodiment of the present invention.

FIG. 3 is a detailed view of small holes of a perforated plate according to an embodiment of the present invention.

FIG. 4 is a plan view of a perforated plate according to an embodiment of the present invention.

FIG. 5 is a sectional view of a perforated plate according to a second embodiment of the present invention.

FIG. 6 is a plan view of a perforated plate according to a second embodiment of the present invention.

FIG. 7 is a cross-sectional view of a perforated plate according to a third embodiment of the present invention.

FIG. 8 is a plan view of a perforated plate according to a third embodiment of the present invention.

FIG. 9 is a sectional view of a rectification column according to a fourth embodiment of the present invention.

FIG. 10 is a sectional view of a rectification column according to a fifth embodiment of the present invention.

FIG. 11 is an explanatory diagram showing the effect of the present invention.

[Explanation of symbols]

1 ... rectification column, 2 ... perforated plate, 3 ... liquid, 4 ... gas, 6 ... small holes, 7 ... openings.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Yamamoto 794 Azuma Higashitoyo, Shimomatsu City, Yamaguchi Prefecture Inside the Kasado Plant, Hitachi Ltd. Company Hitachi Ltd. Kasado factory

Claims (8)

[Claims] 1. A rectifying process in which a liquid is lowered from above and a gas is raised from below to form an ascending gas in a perforated plate having an overflow pipe and having a large number of small holes, and the liquid and gas are brought into contact with each other to carry out rectification. In the gas-liquid contactor for performing operation to separate gas components, small holes are regularly formed in the porous plate, and the small holes are provided at least along the flow direction of the liquid on the porous plate. A gas-liquid contact device characterized in that 2. The small holes of the perforated plate are composed of small holes and projections on the upper surface of the perforated plate which are deformed parts of the perforated plate itself, and the small holes have substantially triangular openings on the upper surface of the perforated plate. The gas-liquid contact device according to claim 1, wherein the gas-liquid contact device has a shape of. 3. The small holes of the perforated plate are circular in a cross section perpendicular to the longitudinal direction of the small holes, the same small hole has a positional change between the upper surface and the lower surface, and the opening is an ellipse. The gas-liquid contactor according to claim 1. 4. A perforated plate having an overflow pipe and having a large number of small holes, in which liquid is lowered from above and gas is raised from below to form an ascending gas, and the liquid and gas are brought into contact with each other to carry out rectification. In the gas-liquid contactor for separating gas components by performing an operation, the perforated plate has at least two perforated plates having small holes opened at right angles to the horizontal direction of the perforated plate and installed in the vertical direction. A gas-liquid contactor characterized in that the opening of the plate is displaced in the flow direction of the liquid on the perforated plate. 5. The perforated plate is characterized in that at least two perforated plates having different shapes of small holes are installed in the vertical direction, and a gap is provided between the perforated plates. The gas-liquid contact device described. 6. The perforated plate is a perforated plate having small holes opened at right angles to the horizontal direction of the perforated plate in the upstream part to the downstream part of the perforated plate or in the direction perpendicular to the part, or small holes having different oblique porosity. 7. The gas-liquid contactor according to claim 1, wherein at least two kinds of perforated plates having holes are combined. 7. The gas-liquid contactor according to claim 6, wherein the perforated plate has a smaller degree of oblique porosity toward the upstream portion of the perforated plate. 8. The gas-liquid contactor according to claim 1, wherein the rising gas and the liquid are components of air, and the components of air such as oxygen, nitrogen and argon are separated.