JP2001029718A - Gas-liquid separator and evaporator using the same - Google Patents

Abstract

(57) [Problem] To provide a gas-liquid separation device in which the gas-liquid separation efficiency is improved and the entrainment of liquid droplets into discharged gas is reduced, and an evaporator using the same. A bottomed cylindrical container (4) having a gas-liquid mixture inlet (1) at an upper portion, a liquid reservoir (2) at a lower portion, and a gas outlet (3) on a side wall. Within
A baffle plate 5 is provided, which shields the gas outlet 3 from the gas-liquid mixture inlet 1 and has an opening 12 for introducing gas at a lower portion. The baffle plate 5 has an area of the lower opening 12. Is a gas-liquid separation device 10 having an inclined portion 5b so as to increase the size of the evaporator and having a gutter 6 attached to the outer lower end thereof along the lower end. I do.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas-liquid separator suitably used for a cocurrent wet-wall evaporator and the like, and an evaporator using the same.

[Prior art]

[0002] An evaporator for evaporating a raw material liquid, particularly a wet wall evaporator, is often used for preparing a raw material gas used in a gas phase reaction. Further, when a gas obtained by evaporating a raw material liquid and a carrier gas or another raw material gas having a low boiling point are used at the same time in a gas phase reaction (for example, when aniline is produced by a gas phase catalytic reaction, the vaporized gas of nitrobenzene may be used). In the case of using hydrogen gas), the raw material liquid and the carrier gas or another raw material gas having a low boiling point are flowed in countercurrent or cocurrent in the evaporator so as to equalize the vaporized gas and the carrier gas. I have. At that time, in the counter-current evaporator, the downstream portion of the wet wall may be dried by a carrier gas or the like, and the heat transfer area may be reduced. An evaporator may be used.

FIG. 5 shows an example of such a cocurrent wet-wall evaporator. The evaporator includes a liquid supply unit 30, a multi-tube evaporator body 31, and a gas-liquid separator 32 in this order from the top.
Is provided. The liquid supply unit 30 is provided with a gas supply pipe 33 for introducing a carrier gas or a raw material gas having a low boiling point at an upper part thereof, and a liquid supply pipe 34 for supplying a raw material liquid at a lower part thereof.

The evaporator main body 31 is composed of a cylindrical container 35 whose upper and lower parts are shielded by an upper plate 36 and a lower plate 37. Inside the container 35, a large number of tubes penetrating the upper plate 36 and the lower plate 37 are provided. A tube body 38 is provided vertically. The liquid supply unit 30 and the gas-liquid separator 32 are attached to the upper plate 36 and the lower plate 37 in a liquid-tight and air-tight state, respectively.
Further, a lower portion and an upper portion of the container 35 are provided with a heat medium inlet 39 and a heat medium outlet 40 for a heating fluid or the like, respectively. It should be noted that a large number of tubes 38 are provided at predetermined intervals in the container 35.
In the figure, for convenience, several pipes 38 are accommodated.
Only shows.

[0005] The gas-liquid separator 32 is provided with the lower plate 37 on the upper part.
It has a bottomed cylindrical container 43 having a gas-liquid mixture inlet 41 in close contact with the container, and a liquid reservoir 42 provided at the lower part, and a gas outlet 44 provided on the side wall. This bottomed cylindrical container 43
Inside, a baffle plate 45 that shields the gas outlet 44 from the gas-liquid mixture inlet 41 is attached.

In the ordinary wet-wall evaporator thus configured, a carrier gas or a low-boiling source gas is introduced from a gas inlet 33 (indicated by an arrow A), and a liquid supply pipe 34 is provided.
More raw material liquid is introduced into the liquid supply unit 30 (indicated by an arrow B). These gases and raw material liquid flow down into the gas-liquid separation device 32 through the inside of each tube 38. At this time, the raw material liquid flowing down along the inner wall surface of the tube 38 is heated by the heat medium (indicated by the arrow C) sent into the evaporator main body 31 and a part thereof is evaporated. A partition plate 48 is provided in the evaporator main body 31 to increase thermal efficiency, and sends the heat medium to the heat medium outlet 40 while meandering.

[0007] The gas-liquid mixture that has exited the pipe 38 is introduced into the gas-liquid separator 32 through a gas-liquid mixture inlet 41 as a mist. In the gas-liquid separation device 32, the liquid 46 that has not evaporated drops as droplets into the lower liquid reservoir 42, and the gas passes through the opening 47 below the baffle plate 45 and is blocked by the baffle plate 45 in the space. And is discharged from the gas discharge port 44. The liquid 46 in the liquid reservoir 42 passes through the circulation path 49 from the liquid discharge pipe 50 and is again sent from the liquid supply pipe 34 into the evaporator and is circulated and used.

[0008]

As shown in FIG. 5, evaporation of a co-current type in which a gas and a liquid flow downward, and a structure in which a liquid reservoir 42 is provided at the bottom for circulating a raw material liquid 46 is provided. Vessel has a problem that the gas-liquid separation efficiency is poor.
That is, as a result of various studies by the inventors of the present invention,
In the gas-liquid separation device 32, a baffle plate 45 is attached to the gas discharge port 44 in order to prevent entrainment of droplets into the discharged gas.
However, since the liquid flowing out of the tube 38 of the evaporator main body 31 falls along the baffle plate 45 as a liquid film, droplets are formed in the gas passing through the lower opening 47 of the baffle plate 45. It was found that it was involved and made the gas-liquid separation efficiency worse.

In the evaporator, if the gas-liquid separation is not sufficiently performed, and the amount of entrained liquid droplets in the gas is increased, the post-process is adversely affected. For example, (1) reduction of catalyst life due to adsorption of droplets to the catalyst in the gas phase catalytic reaction, (2) increase in load on the droplet separator in the post-process, (3) increase in pressure loss of the gas heater in the post-process And the like. Accordingly, it is an object of the present invention to provide a gas-liquid separation device having improved gas-liquid separation efficiency and an evaporator using the same.

[0010]

The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, the area of the opening formed in the lower portion of the baffle plate has a great effect on the entrainment of the droplets in the lower portion of the baffle plate. If the area of the lower opening is large, the flow velocity (rising speed) of the gas discharged through this opening is
Droplets, which are heavier than the gas, fall before being entrained in the gas, and find a new fact that the amount of the entrained droplets is reduced, leading to the completion of the present invention. Was.

That is, the gas-liquid separation device of the present invention comprises a bottomed cylindrical container having a gas-liquid mixture inlet at an upper portion, a liquid reservoir at a lower portion, and a gas outlet at a side wall. In a bottomed cylindrical container, provided with a baffle plate that shields the gas outlet from the gas-liquid mixture introduction port and has an opening for introducing gas at the bottom,
The baffle plate may include an inclined portion that is inclined downward from the gas outlet so as to increase the area of the lower opening.

In the present invention, a gutter may be provided along the lower end on the outer lower end of the baffle plate in addition to or separately from the above-described configuration of the baffle plate. As a result, it is possible to prevent the liquid flowing down the baffle plate from falling as a liquid film from the lower end of the baffle plate,
Gas-liquid separation efficiency can be improved. That is, another gas-liquid separation device of the present invention comprises a bottomed cylindrical container having a gas-liquid mixture inlet at an upper portion, a liquid reservoir at a lower portion, and a gas outlet at a side wall. In a bottom cylindrical container, a baffle plate which shields the gas outlet from the gas-liquid mixture introduction port and has an opening for introducing gas at a lower portion is provided, and a baffle plate outside the baffle plate is provided. A gutter is attached to the lower end along the lower end.

Further, in order to prevent the gas from colliding with the liquid surface of the liquid reservoir and lifting up the liquid, the inner surface of the container between the gas discharge port and the liquid reservoir has an obstruction for preventing liquid droplets from rising. A plate may be protruded. The evaporator according to the present invention is characterized in that an evaporator main body is installed above the gas-liquid separation device, and a liquid supply unit is provided above the evaporator main body. It is preferable that the liquid supply unit and a liquid reservoir provided below the gas-liquid separator are connected by a liquid circulation path.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is shown in FIGS.
It will be described based on. 1 is a longitudinal sectional view showing a gas-liquid separator according to this embodiment, FIG. 2 is a plan view of the gas-liquid separator, and FIG. 3 is a bottomed cylindrical container taken along line III-III shown in FIG. It is a longitudinal cross-sectional view showing a cutout state. As shown in FIG. 1, this gas-liquid separation device 10 has a bottomed cylindrical container 4 having a gas-liquid mixture inlet 1 at an upper portion, a liquid reservoir 2 at a lower portion, and a gas outlet 3 on a side wall. It is composed of A baffle plate 5 for shielding the gas outlet 3 from the gas-liquid mixture inlet 1 is provided in the bottomed cylindrical container 4.
Is provided. An opening 12 for introducing exhaust gas is formed at a lower portion of the baffle plate 5. Liquid pool 2
Is provided with a liquid discharge pipe 11.

As shown in FIGS. 1 to 3, the baffle plate 5 comprises an upper flat portion 5a, an inclined portion 5b inclined downward from the flat portion 5a, and both side plate portions 5c, 5c. The outlet 3 is completely shielded from the inside of the bottomed cylindrical container 4 except for the lower opening 12. In addition, a gutter 6 is attached to the outer lower end of the baffle plate 5 along the lower end.

As shown in FIG. 1, a baffle plate 7 for preventing a liquid drop from rising is provided on the inner surface of the container 4 between the gas discharge port 3 and the liquid reservoir 2. This baffle plate 7 is a gas outlet 3
And a substantially semicircular band-shaped plate as shown in FIG. A mounting flange 8 is provided on the periphery of the gas-liquid mixture inlet 1 at the top of the container 4. This flange 8
Is provided with a mounting hole 9 along the circumferential direction.

The gas-liquid separation device 10 according to this embodiment
By using the mounting flange 8, for example, an evaporator main body 31 and a liquid supply unit 30 as shown in FIG. Hereinafter, the operation when the gas-liquid separation device 10 according to this embodiment is applied to an evaporator as shown in FIG. 5 will be described. The gas-liquid mixture that has flowed down from the evaporator body 31 enters the gas-liquid separator 10 from the gas-liquid mixture inlet 1 at the top. A part of the liquid in the gas-liquid mixture is supplied to the flat portion 5a of the baffle plate 5.
The water flows down along the inclined portion 5 b from the bottom and is collected by the gutter 6.
Next, the liquid flows along both sides of the gutter 6 along the gutter 6, and flows down to the liquid pool 2 along the inner wall surface of the container 4.

Thus, by providing the gutter 6 at the lower end of the baffle plate 5, it is possible to prevent the liquid from falling from the lower end of the baffle plate 5 like a waterfall to form a liquid film. Therefore, it is possible to prevent the gas from passing through the liquid film and entraining the droplet as in the related art. On the other hand, many gas-liquid mixtures are sent downward through the gap 13 between the lower end of the baffle plate 5 and the inner wall surface of the container 4 facing the lower end. Then, as indicated by the arrow in FIG. 1, the gas rises into the baffle plate 5 through the lower opening 12 of the baffle plate 5, is discharged from the gas discharge port 3, and is sent to a subsequent process. On the other hand, the droplet that has passed through the gap 13 falls into the liquid reservoir 2 due to its weight. The liquid 14 in the liquid reservoir 2 is extracted from the liquid discharge pipe 11.

At this time, when the liquid droplets passing through the gap 13 do not fall and are partially discharged along with the gas and discharged from the gas discharge port 3 through the lower opening 12 of the baffle plate 5, Thus, there is a possibility that the post-process will be adversely affected. Whether or not the droplet entrains gas is theoretically determined by the rising speed V1 of the gas passing through the lower opening 12 of the baffle plate 5 and the droplet settling speed V2 at the lower end of the baffle plate 5. You. If V1> V2, the droplets are entrained in the gas before settling and the entrainment rate with the gas is high. On the other hand, when V1 <V2, the rate of sedimentation of the droplet without being entrained in the gas increases. Therefore, in order to increase the gas-liquid separation efficiency, it is necessary to satisfy the following relation: the gas rising speed V1 <the droplet sedimentation speed V2.

The rising speed V1 of the gas passing through the lower opening 12 of the baffle plate 5 is determined by the area of the opening 12. That is, when the area of the opening 12 is small, the rising speed V1 of the gas increases, and when the area of the opening 12 is large, the rising speed V1 of the gas decreases. Therefore, in this embodiment, the inclined portion 5b of the baffle plate 5 is extended downward and the area of the opening 12 is increased to increase the gas-liquid separation efficiency.

On the other hand, when the area of the opening 12 becomes large,
As shown in FIG. 1, the gap 13 between the lower end of the baffle plate 5 and the inner surface of the container opposed thereto becomes relatively small, so that the flow rate of the gas-liquid mixture passing through the gap 13 increases. At this time, the gas that has passed through the gap 13 turns upward to advance to the opening 12, but heavy droplets cannot be entrained with the gas due to a large inertial force and collide with the inner wall surface of the container 4. Since it falls, gas-liquid separation efficiency can be further improved. If the gap 13 is excessively small, a pressure loss occurs, which is not preferable.

The area A1 of the opening 12 and the area A of the gap 13
The ratio (A1: A2) to 2 is not particularly limited. Basically, it is preferable to make the area A1 of the opening 12 as large as possible if it is within the allowable range of the pressure loss caused by the gas flow rate. : 1: 3: 2 is preferred. As shown in FIGS. 1 and 4, a baffle plate 7 for preventing a liquid drop from rising is provided on the inner wall surface of the container between the gas discharge port 3 and the liquid reservoir 2, so that a gap 13 is provided.
Can be prevented from hitting the liquid surface of the liquid reservoir 2 and rising toward the gas outlet 3 while rolling up the liquid.

Although the diameter of the gas-liquid separation device 10 is not particularly limited, it is preferable to make the diameter larger than the diameter of the evaporator body in order to increase the gas-liquid separation efficiency (see Examples 1 and 2 described later). This is because, by making the diameter of the gas-liquid separation device 10 larger than the diameter of the evaporator main body, the liquid flowing down from the evaporator main body can be reduced from hitting the baffle plate 5, and the larger diameter increases the gas flow rate. It is presumed that this is because it can be kept low.

It is preferable that the distance from the liquid surface of the liquid reservoir 2 to the gas outlet 3 is large. This makes it possible to suppress the liquid droplets from rising from the liquid surface. In addition,
The gas-liquid separation device of the present invention is applicable not only to an evaporator as shown in FIG. 5 but also to various devices that require separation of a gas and a liquid from a gas-liquid mixture, such as a heat exchanger and a drying device. It is also applicable to vessels and the like.

[0025]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to only the following Examples.

Example 1 Instead of the gas-liquid separator 32 shown in FIG. 5, a cocurrent wet-wall evaporator equipped with the gas-liquid separator 10 shown in FIGS. 1 to 4 was used. This evaporator has an evaporator body 3 having a diameter of 1600 mm.
And the gas-liquid separation device 10 has the same diameter as the evaporator main body 32 and a height of 2600 mm. The baffle plate 5 provided in the gas-liquid separator 10 has a gutter 6 at the outer lower end, and has a length (vertical length) from the center to the lower end of the gas outlet 3 of 600.
mm, and the area of the lower opening 7 is 1.14 × 10 ⁶ m
m ² . A hydrogen gas is supplied from a gas inlet pipe 33 as a raw material gas, nitrobenzene is supplied as a raw material liquid, nitrobenzene is evaporated in the hydrogen gas, and a liquid is removed from the gas-liquid mixture by the gas-liquid separator 10 to remove the gas from the gas outlet. The gas was discharged from No. 3 and sent to a gas heater in a subsequent process. Here, the main operating conditions of the wet wall evaporator are as follows.

The amount of circulating nitrobenzene from the liquid reservoir 2: 10 tons / hour Average gas velocity at the gas-liquid mixture inlet 1: 1.2 m / sec At this time, the average gas rise at the lower opening 12 of the baffle plate 5 The speed was 1.57 m / sec. The drop sedimentation velocity at the lower end of the baffle plate 5 was as follows. (Droplet diameter) (Terminal sedimentation velocity) 50 μm 1.3 m / sec 100 μm 1.8 m / sec 200 μm 2.5 m / sec 500 μm 4.0 m / sec 1000 μm 5.7 m / sec As a result, the gas is discharged from the gas-liquid separation device 10. Although 4.0% of the obtained nitrobenzene was entrained in the gas as droplets, no increase in pressure loss was observed in the gas heater in the subsequent process after 70 days of operation.

Comparative Example 1 A wet wall evaporator equipped with a gas-liquid separator 32 shown in FIG. 5 was used. This evaporator has an evaporator body 3 having a diameter of 1600 mm.
1 and the gas-liquid separator 32 has the same diameter and height as the gas-liquid separator 10 of the first embodiment. Gas-liquid separator 3
The length (vertical length) from the center to the lower end of the gas outlet 44 of the baffle plate 45 provided in the inside 2 was 400 mm, and the area of the lower opening 47 was 0.32 × 10 ⁶ mm ² .

Then, hydrogen gas and nitrobenzene were supplied in the same manner as in Example 1, nitrobenzene was evaporated in the hydrogen gas, and sent to a gas heater in a later step. Here, the main operating conditions of the evaporator (the amount of circulating nitrobenzene from the liquid reservoir 2 and the average gas velocity at the gas-liquid mixture inlet 1 of the gas-liquid separator 10) are the same as in Example 1. At this time, the average gas rising speed at the lower opening 47 of the baffle plate 45 was 5.58 m / sec. As a result, 6.0% of the nitrobenzene discharged from the gas-liquid separator 32 was entrained in the gas as droplets, and an increase in pressure loss was observed in the gas heater in the post-process after 40 days of operation.

As described above, even if the evaporator is operated under the same conditions using a gas-liquid separator of the same size, the gutter 6 is provided at the outer lower end of the baffle plate 5 as in the first embodiment, and the baffle When the area of the lower opening 12 of the baffle plate 5 is increased by providing the inclined portion 5 b on the plate 5, the gas rising speed at the lower opening of the baffle plate is lower than that of the comparative example 1, so that the gas is entrained. It can be seen that the amount of droplets to be dropped is small.

Example 2 A 2400 mm diameter having a structure as shown in FIGS.
The length (vertical length) from the center to the lower end of the gas outlet 3 is 1 using a gas-liquid separator 10 having a height of 5500 mm.
100 mm, the area of the lower opening 7 is 1.29 × 10 ⁶ m
Using the same wet wall evaporator as in Example 1 except that the baffle plate 5 of m ² was used, the amount of circulating nitrobenzene from the liquid reservoir 2 was 10 tons / hour, and the gas-liquid mixture was introduced into the gas-liquid separator 10. The wet wall evaporator was operated at an average gas velocity of 0.81 m / sec at the mouth 1. At this time, the baffle plate 5
The average gas rising velocity at the lower opening 12 of the slab is 1.45 m /
Seconds. As a result, only 1.0% of the nitrobenzene discharged from the gas-liquid separator 10 was entrained in the gas as droplets.

Comparative Example 2 Example 2 has a structure as shown in FIG.
And the length (vertical length) from the center to the lower end of the gas discharge port 3 is 900 m.
m and the area of the lower opening 7 was 0.36 × 10 ⁶ mm ² , except that the baffle plate 45 was used and the same wet wall evaporator was used as in Example 2 using the same wet wall evaporator as in Example 2. The vessel was operated. At this time, the average gas rising speed at the lower opening 12 of the baffle plate 5 was 5.19 m / sec. As a result, 2.5% of the nitrobenzene discharged from the gas-liquid separator 10 was entrained in the gas as droplets.

As described above, similarly to the first embodiment, the inclined portion 5b is provided on the baffle plate 5 to increase the area of the lower opening of the baffle plate 5 to reduce the gas rising speed at the lower opening of the baffle plate. In the evaporator according to the second embodiment in which the baffle plate 5 is provided at the lower end of the baffle plate 5, the amount of droplets accompanying the gas is reduced. Further, when comparing the first embodiment and the second embodiment, the second embodiment has a smaller droplet entrainment amount than the first embodiment. The reason for this is that the second embodiment is based on the fact that the diameter and length of the gas-liquid separation device 10 and the length of the baffle plate (therefore, the area of the lower opening) are larger than those of the first embodiment. Guessed.

[0034]

According to the present invention, the gas-liquid separation efficiency is improved, and it is possible to reduce the entrainment of liquid droplets in the gas discharged from the gas discharge port. Therefore, the gas-liquid separation device of the present invention can be suitably used for an evaporator used for a gas phase reaction and other uses requiring gas-liquid separation.

[0035]

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a gas-liquid separation device of the present invention.

FIG. 2 is a plan view of the gas-liquid separation device shown in FIG.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 1;

FIG. 5 is a longitudinal sectional view showing a conventional wet wall evaporator.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 gas-liquid mixture inlet 2 liquid reservoir 3 gas outlet 4 bottomed cylindrical container 5 baffle plate 5 a inclined portion 6 gutter 7 baffle plate 10 gas-liquid separator 12 opening 14 liquid 30 liquid supply unit 31 evaporator main body 32 Gas-liquid separation device

Continued on the front page (72) Inventor Hiromi Takahashi 5-1 Anesaki Kaigan, Ichihara-shi, Chiba F-term (reference) in Sumitomo Chemical Co., Ltd. 4D031 AB02 AB11 AB12 BA04 EA01 4D076 BA09 BA13 CA11 CA13 CB03 DA03 JA02 4G068 DA10 DB03 DC04 DD11

Claims (5)

[Claims] 1. A bottomed cylindrical container having a gas-liquid mixture inlet at an upper portion, a liquid reservoir at a lower portion, and a gas outlet at a side wall. A gas-liquid separator provided with a baffle plate that shields a gas outlet from the gas-liquid mixture inlet and has an opening for introducing gas at a lower portion, wherein the baffle plate has an area of a lower opening. A gas-liquid separation device characterized by having an inclined portion extending downwardly from the gas outlet so as to increase the size of the gas outlet. 2. A bottomed cylindrical container having a gas-liquid mixture inlet at an upper portion, a liquid reservoir at a lower portion, and a gas outlet at a side wall. A gas-liquid separator provided with a baffle plate that shields a gas outlet from the gas-liquid mixture inlet and has an opening for introducing gas at a lower portion, wherein the lower end is formed at an outer lower end of the baffle plate. A gas-liquid separation device having a gutter provided along the same. 3. A baffle plate for preventing a liquid droplet from rising is provided on an inner surface of the container between the gas discharge port and the liquid reservoir.
Or the gas-liquid separator according to 2. 4. An evaporator, wherein an evaporator main body is installed on the upper part of the gas-liquid separator according to claim 1, and a liquid supply section is provided on the upper part of the evaporator main body. . 5. The evaporator according to claim 4, wherein the liquid supply unit and a liquid reservoir provided below the gas-liquid separator are connected by a liquid circulation path.