JP2000005502A - Tray type gas-liquid containing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To narrow the gap the trays and to improve space utilization factor by placing a number of trays each of which has no perforated hole, but provided with a cutout in the edge part, within a column so that the cutouts of every adjacent two of the trays are positioned on the opposite sides to each other and the space between every adjacent two of the trays is a specified value. SOLUTION: This vapor-liquid contact equipment such as distillation column or gas absorption column is provided with a number of trays each of which, for example, each of arbitrary adjacent two trays 1 and 2 of which has only a cutout 3 formed in an edge part of the tray 1 or 2, wherein the cutouts 3 of the trays 1 and 2 are positioned alternately on the opposite sides to each other and also the space between the trays 1 and 2 is set to 10 to 150 mm. Thus, by providing each of the trays 1 and 2 with no downcomer, breakage of a liquid film is promoted and a gas is passed through the broken parts of the liquid film. Also, at the time of causing any back mixing or flooding due to entrainment in the cutout 3 of each of the trays 1 and 2, the liquid film breakage is promoted by setting a means such as formation of recessed and projecting parts, notches or downward projections in the cutout 3 of each of the trays 1 and 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel plate-type gas-liquid contacting device in a plate-type gas-liquid contacting device, in which the distance between the plates can be made much smaller.

[0002]

2. Description of the Related Art Conventionally, in order to increase the separation capacity of a gas-liquid contacting device such as a distillation tower, a gas absorption tower, a gas stripping tower, etc., in the case of a tray type, the number of stages is increased, and in the case of a packed type. Have responded by increasing the height of the filling portion.

However, when this apparatus must be installed indoors, its height is naturally limited, and the number of shelves can be increased, and the height of the filling portion can be set to a desired height. Disappears. For this reason, the height can be suppressed by means such as dividing the tower, but there have been problems such as an increase in additional facilities and complicated piping.

[0004] In the case of a conventional shelf system having a cross-flow gas-liquid contact, if the number of shelf stages is increased within a certain limit height and the stage interval is simply reduced, flooding (flowing liquid drops due to rising steam pressure). However, such a means cannot be adopted because the droplet entrainment rate (a phenomenon in which droplets are entrained in the rising steam and the separation ability is reduced) increases.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel shelf in which the gap between the shelves in the shelf type gas-liquid contact device can be reduced to a narrow space which has been impossible in the past. Another object of the present invention is to provide a gas-liquid contact device.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a shelf having no cutout at the end without a hole, wherein the cutouts are alternately arranged on the left and right and the step interval is preferably 10 to 150 mm. The present invention relates to a plate-type gas-liquid contact device, which is installed in a tower so as to have a thickness of 10 to 100 mm.

[0007] The conventional shelf is provided with a large number of holes for allowing gas to pass through, regardless of the type, but the shelf of the present invention does not have such holes. Therefore, in the conventional type, the liquid moves in a substantially horizontal direction on the plate, and the gas passes through the liquid through the hole of the plate and rises due to the rising orifice effect. (See FIG. 4). However, in the present invention, since no holes are provided in the shelf, the gas only passes through the opening through which the liquid flows down from the end of the shelf, so that the gas and the liquid come into contact with each other horizontally. Countercurrent is the main. Therefore,
The pressure loss per shelf is extremely small.

In the present invention, as the area of the shelf increases, the liquid flow on the shelf may become non-uniform. In this case, it is desirable to install a straightening plate parallel to the liquid flow direction. . FIG. 2 shows an example of this mode.

Conventional shelves are provided with a weir, and the weir holds the liquid on the shelves, and gas passes through the liquid to make gas-liquid contact. The invention does not adopt a method in which a gas passes through a liquid, but adopts a form in which the liquid is formed into a film and the gas passes over the film surface. Therefore, if necessary, a wire mesh is stuck on the shelf (see FIG. 3), or the surface of the shelf is provided with irregularities or projections in a direction perpendicular or slightly oblique to the flow of the liquid. It is desirable to promote mass transfer on the shelf by increasing the gas-liquid contact area without causing a turbulent flow state, that is, a break portion in the liquid film.

The above-mentioned means is a means for promoting the mass transfer on the shelf by the treatment on the liquid side, but such a concept is not limited to the liquid side but can also be applied to the gas side. . For this purpose, a gas flow can be disturbed by installing an appropriately arranged baffle plate or the like in the gas flow path portion on the shelf. In this specific example, a baffle plate such as a downwardly facing triangular plate may be provided at an appropriate direction and at an interval below the upper shelf to disturb the gas flow. As the means for disturbing the gas-liquid flow in this manner, any means other than the above-described means can be adopted as long as flooding and entrainment do not occur.

In the conventional tray system, the descending liquid flows to the lower stage through an overflow pipe (downcomer) provided at the end of the shelf. In the present invention, such an overflow pipe (downcomer) is used. Without a downcomer), only a cutout is provided at the end of the shelf. By not providing an overflow pipe (downcomer) in this manner, the breakage of the liquid film is promoted, and the gas passes through the broken portion of the liquid. If back mixing or flooding due to entrainment occurs in the cutout, the cutout of the shelf is provided with (1) unevenness (see FIG. 1 (a)) and (2) cutout. Put in,
(3) It is preferable to provide a mechanism for promoting the breakage of the liquid film by attaching a projection downward (see FIG. 1B) so that the gas-liquid flows smoothly. Conversely, in the case where the liquid flows unevenly in the notch portion and the flow is localized, a drift preventing mechanism such as making the above-described cut or attaching a projection downward can be provided.

In the conventional tray system, since the gas passes through the liquid, the mass transfer coefficient per unit area is large. On the other hand, in the case of the present invention, since the gas-liquid contact is only on the liquid film surface, the mass transfer coefficient per unit area is small. However, this point can be sufficiently compensated for by (a) increasing the tower diameter and increasing the gas-liquid contact area, and (b) reducing the step interval to increase the total number of steps within a certain limit height. did it.

In the present invention, since the liquid flow velocity is smaller than that of the conventional tray system, Re (Reynolds number) is small and the mass transfer coefficient is small. The surface of the liquid can be ruffled by attaching a wire net or the like to the surface to form a pseudo-turbulent state, thereby improving the gas-liquid contact efficiency and the mass transfer speed.

[0014]

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1 and Comparative Examples 1-2 Table 1 shows the apparatus specifications of a distillation column corresponding to Example 1 of the present invention. For comparison, Table 1 also shows the device specifications of a conventional tray-type distillation column, a sieve tray distillation column (Comparative Example 1), and the device specifications of an ordered metal packed column (Comparative Example 2). The composition of the stock solution and the operating conditions are as follows. Stock solution: toluene 45.0 wt% m-xylene 55.0 wt% Operating conditions: reflux ratio 1.0 Operating pressure 760 mmHg Distillation rate 45.0%

[0016]

[Table 1] The metal packed tower has a liquid disperser at the top and a redispersor at the feed position of the undiluted solution.

The operation results of Example 1 and Comparative Examples 1 and 2 are shown in Table 2 below.

[Table 2] * 1: Total number of transfer units based on steam-side membrane (Number of Transfer Unit) * 2: Height of Transfer Unit based on steam-side membrane reference (Height of Transfer Unit) The smaller this value is, the higher the separation capacity per height. Tower height = NTU _OG × HTU _OG * 3: Ratio of HTU of Comparative Example to HTU of Example 1

(Discussion) (1) Looking at the items of HTU, Comparative Example 1 is 4.34 and Comparative Example 2 is 2.
Since it is 47, the height required to obtain the same separation efficiency as in Example 1 of the present invention is 4.34 times in Comparative Example 1 and 2.47 times in Comparative Example 2. (2) In the first embodiment, the distillation column having a height of 1040 mm
Two shelves can be provided, and the distance between the shelves is only 20 mm, whereas that of Comparative Example 1 is 33
It can be seen that only 22 trays are provided in a distillation column having a height of 00 mm, and the interval between the trays needs to be 150 mm.

[0019]

(1) According to the present invention, the interval between trays in a conventional tray-type distillation column can be greatly reduced. (2) This eliminates the necessity of dividing and arranging the towers even in an indoor installation with height restrictions, thereby achieving high economic efficiency and increasing the utilization rate of the indoor area. .

[Brief description of the drawings]

1 (a) and 1 (b) are partial perspective views showing only two upper and lower shelves of the present invention, and FIG. 1 (a) shows a case where a notch in a shelf is provided with irregularities; (B) shows a case where a vertically downward projection is attached to the notch of the shelf.
(C) is a top view schematically showing a state in which a liquid film flowing on the shelf surface in (a) or (b) is broken.

FIG. 2 is a model perspective view showing a mode in which a current plate is provided on the surface of a shelf in the present invention.

FIG. 3 is a model perspective view showing a mode of attaching a wire net on a shelf in the present invention.

FIG. 4 is a cross-sectional view schematically showing a gas-liquid flow of a conventional tray type distillation column.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 shelf 2 shelf 3 notch of shelf 4 distillation column wall 5 unevenness of notch 6 protrusion vertically below notch 7 boundary between shelf and notch 8 provided on shelf Rectifying plate 9 wire mesh provided on a shelf 11 conventional perforated shelf 12 conventional perforated shelf 13 holes 14 wall of distillation column

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yukiyoshi Takahashi 1-3-9, Nihonbashi-Muromachi, Chuo-ku, Tokyo Ichikoshi Building 7th Floor Inside Nippon Refine Co., Ltd. (72) Inventor Liu Yoshiba Nihonbashi Muromachi, Chuo-ku, Tokyo 1-3-9-1 Ichikoshi Building 7F Nippon Refine Co., Ltd. (72) Inventor Akimasa Oda 1-3-9 Nihonbashi Muromachi 1-chome, Nihonbashi, Chuo-ku, Tokyo Nippon Refine Co., Ltd. (72) Inventor Chitako Aida 1-3-9, Nihonbashi-Muromachi, Chuo-ku, Tokyo F-term (reference) 4F020 AA08 BA15 BB04 CB19 CC08 CC13 DB13 4D076 AA13 AA22 AA24 BB05 CA13 CA15 CA16 CC07 FA31 FA37 JA03

Claims (4)

[Claims] 1. A large number of shelves having a notch at the end without a hole are provided in a tower such that the positions of the notches are alternately left and right and the step interval is 10 to 150 mm. A shelf type gas-liquid contact device characterized by the above-mentioned. 2. The plate-type gas-liquid contact device according to claim 1, wherein the surface structure of the plate is such that a liquid film surface on the plate can form a pseudo-turbulent state. 3. The plate-type gas-liquid contact device according to claim 1, wherein a baffle plate is provided in the gas flow path of the plate. 4. A mechanism for facilitating breakage of a liquid film and / or a mechanism for preventing drift of a liquid is provided in a notch of a shelf.
4. The tray-type gas-liquid contact device according to any one of items 1 to 3.