JP2906010B2 - Ar recovery device and recovery method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air liquefaction / separation apparatus provided with Ar gas for recovering argon gas from a rectification column.
The present invention relates to a recovery apparatus and a recovery method, and particularly to an improved structure and method of extracting a raw material Ar gas from a rectification column to a crude Ar column.
The present invention relates to a recovery device and a recovery method.

[0002]

2. Description of the Related Art It is well known that air contains three main components, N ₂ , Ar and O ₂ , and a large amount of O ₂ and N ₂ are used in steel works such as steelmaking facilities. To do
O ₂ and N ₂ are recovered by separating air with an air liquefaction separator.

[0003] In this air liquefaction / separation apparatus, as shown in FIG. 3, the compressed raw material air is cooled to near a liquefaction point and then supplied to a lower column 2 of a rectification column 1. after rough rectification to liquefy the feed above the upper tower 3 has been rectification separation between the product N ₂ 4 and product 0 ₂ 5 this upper tower 3.

Incidentally, the boiling point of each component is at atmospheric pressure,
₂ : -196 ° C, Ar: -186 ° C, O ₂ : -183 ° C
It is. Accordingly, in the rectification column 1, the three-component most high boiling point products N ₂ 4 is recovered from the top 3a of the upper tower 3, products 0 ₂ 5 the lowest boiling point is recovered from the bottom 3b of the upper tower 3 .

On the other hand, Ar having a middle boiling point in the three components is Ar
Is concentrated in the intermediate portion 3c of the upper tower 3. Therefore, A
In the recovery of r, the raw material Ar gas is extracted from the intermediate portion 3c of the upper tower 3 and sent to the crude Ar tower 6, the purity of which is improved in the crude Ar tower 6, and the remaining components (hereinafter referred to as crude Ar) are removed from the upper tower 3. Return to 3.
Next, the crude Ar is sent to an Ar purification system including a deoxidizer and a high-purity Ar tower (not shown), and is recovered as product Ar.

That is, in order to efficiently recover Ar, it is necessary to concentrate Ar in the extraction part 3c for the raw material Ar gas. Therefore, at the time of rated operation, A
At the stage where the r concentration distribution has a peak, the Ar extraction portion 3c
Was designed to be located.

[0007]

By the way, the conventional Ar
There were the following problems with the recovery technology. That is,
It is desirable to perform rated operation of the air liquefaction separation device,
0 ₂・ N ₂ according to the production status of steel mills in steelworks
Since the demand amount also fluctuates, the operating load must be fluctuated. As described above, when the operation load of the air liquefaction / separation device is changed in accordance with the fluctuation in the demand amount of O ₂ · N ₂ with respect to the rated operation, the Ar recovery rate equivalent to that during the rated operation cannot be obtained. there were.

This is because the Ar concentration distribution in the upper tower 3 changes due to a change in the operating load, whereas the extraction portion 3c for the raw material Ar gas is fixed at one position during the rated operation. there were.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an Ar recovery apparatus and a recovery method capable of obtaining an Ar recovery rate equivalent to that during rated operation even if the operating load of the air liquefaction separation apparatus fluctuates. It is in.

[0010]

In order to achieve the above-mentioned object, an Ar recovery apparatus according to the present invention uses a raw Ar gas extracted from an intermediate portion of an upper tower of a rectification column provided in an air liquefaction / separation apparatus to obtain a crude Ar gas. In an Ar recovery apparatus for rectifying and separating Ar by introducing into a tower and a device provided on the downstream side of the tower, in a middle portion of the upper tower, a plurality of extraction portions of a raw material Ar gas including a removal portion at the time of rated operation are provided. And an on-off valve is interposed between each extraction part and the crude Ar tower.

In the configuration of the Ar recovery apparatus, preferably, an analysis apparatus for detecting O ₂ and Ar concentration in the internal gas of each extraction section is provided at an intermediate portion of the upper tower.

Preferably, a control device for receiving a detection signal of the analyzer and controlling the opening and closing of the on-off valve is connected to the analyzer and the on-off valve.

On the other hand, in the Ar recovery method according to the present invention, the raw Ar gas is extracted from the middle part of the upper column of the rectification column provided in the air liquefaction separation device and sent to the crude Ar column. In the Ar recovery method in which Ar is rectified and separated by a device provided on the downstream side, O ₂ and A in the internal gas of each extraction portion installed at a plurality of locations in the middle part of the upper tower are described.
The r concentration is analyzed, and based on the analysis result, the amount of nitrogen that hinders the rectification action in the crude Ar tower is small, and the raw material Ar gas is extracted from the extraction portion having a high concentration of Ar.

[0014]

The rectification tower provided in the air liquefaction / separation apparatus comprises an upper tower and a lower tower. Product nitrogen is recovered from the upper part of the upper tower, and product oxygen is recovered from the lower part of the upper tower. In such an air liquefaction / separation apparatus, the Ar recovery apparatus extracts the raw material Ar gas from the middle part of the upper tower, and introduces the raw material Ar gas into the crude Ar tower and a device provided downstream thereof to purify Ar. It is separated.

According to the configuration of the above-mentioned Ar recovery apparatus, the raw material Ar gas extraction parts are provided at a plurality of locations including the extraction part at the time of rated operation in the middle part of the upper tower. Further, an on-off valve is interposed between each extraction part and the crude Ar tower, respectively. Therefore, even if the Ar concentration distribution changes in the upper tower due to the fluctuation of the operation load of the air liquefaction separation device,
By selectively opening the on-off valve of the extraction part provided at the place where the Ar concentration distribution in the upper tower becomes a peak,
The raw Ar gas containing a high concentration of Ar can be sent to the crude Ar tower, and the same Ar recovery rate as in the rated operation can be secured.

Further, if an analyzer for detecting the concentration of O ₂ and Ar in the internal gas of each extraction section is provided in the middle part of the upper tower, the Ar in the upper tower due to the fluctuation of the operating load is provided. The change in the concentration distribution is accurately grasped by the analyzer.

Further, if a control device that receives a detection signal of the analyzer and controls the opening and closing of the on-off valve is connected to the analyzer and the on-off valve, based on the analysis result of the analyzer,
The on-off valve of the extraction portion provided at the location where the Ar concentration distribution peaks in the upper tower is selectively and automatically opened by the control device.

On the other hand, in the Ar recovery method, the concentration of O ₂ and Ar in the internal gas of each of the extraction sections installed at a plurality of locations in the middle of the upper tower is analyzed. This is because the distribution of Ar concentration in the upper tower changes due to the change in the operating conditions.

Therefore, of the internal gas of each extraction part, 0
By analyzing ₂ and the Ar concentration, the location where the Ar concentration distribution in the upper tower has a peak can be accurately grasped.

Then, based on the analysis results, the amount of nitrogen that hinders the rectification action in the crude Ar tower is small, and the raw material Ar gas is extracted from the extraction part with a high concentration of Ar and sent to the crude Ar tower. An Ar recovery rate equivalent to that at the time of the rated operation is secured, and automatic operation of Ar recovery can be achieved in response to a change in the operation load of the air liquefaction / separation apparatus.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an Ar recovery apparatus and a recovery method according to the present invention will be described below in detail with reference to the accompanying drawings. As shown in FIG. 3, the Ar recovery device 20 extracts the raw material Ar gas from the intermediate part 3 c of the upper tower 3 of the rectification tower 1 to improve the purity of Ar and return the remaining components to the upper tower 3. Ar column 6 and an Ar purification system (not shown) downstream thereof for increasing the purity of the crude Ar from the crude Ar column 6
It is composed of

As shown in FIG. 1, a plurality of extraction portions 21 are provided in the middle of the upper tower 3 along the vertical direction. These extraction portions 21 are provided for extracting the Ar raw material gas from the intermediate portion of the upper tower 3 and sending it to the crude argon column 6. In the present embodiment, three different extraction portions 21 a are provided. , 21b, 21
c is provided. And these extraction parts 21
One of a, 21b, and 21c is set at the same position as the extraction unit 3c at the time of the rated operation of the air liquefaction / separation apparatus 1, and in the present embodiment, the extraction unit located at the center. 21b corresponds to the extraction portion 3c at the time of rated operation.

Branch pipes 22a, 22b, and 22c are connected to the extraction portions 21a, 21b, and 21c, respectively. The branch pipes 22a, 22b, and 22c are integrated by a collecting pipe 23. It is connected to the lower part of the tower 6. On-off valves 24a, 24b, 24c are interposed in the branch pipes 22a, 22b, 22c, respectively. In the present embodiment, each of the on-off valves 24a, 24
b and 24c are formed by, for example, a control valve such as a solenoid valve.

A return pipe 25 is connected between the bottom of the crude Ar tower 6 and the upper tower 7, and after the raw Ar gas is converted into high-purity crude Ar in the crude Ar tower 6, the return pipe 25 is used. The remaining components are returned to the upper tower 3. On the other hand, the transfer pipe 26 connected to the top of the crude Ar tower 6 is connected to an argon purification system for increasing the purity of the crude Ar.

Further, in the middle part of the upper tower 3, there is provided an analyzer 27 for detecting the component concentration of the internal gas. In this embodiment, three different analyzers are provided. 27a, 27b and 27c are provided. Specifically, each of the analyzers 27a, 27b, 27c
Are provided at positions corresponding to the positions where the extraction portions 21a, 21b, and 21c are installed, with their respective detection ends facing.

Then, the analyzers 27a, 27b, 2
The control device 28 for receiving the detection signal of each analyzer 27a, 27b, 27c and controlling the opening and closing of each of the on-off valves 24a, 24b, 24c is connected to 7c and the on-off valves 24a, 24b, 24c. The control device 28 is formed by a microcomputer or the like, for example.
Based on the analysis results of the analyzers 27a, 27b, and 27c, the extraction units 21a, 21b, and ₂ with a small amount of N2 and a high concentration of Ar that hinder the rectification action in the crude Ar tower 6 are provided.
1c, the on-off valve 24
a, 24b and 24c are controlled to be selectively opened.

Next, the operation of the above embodiment will be described while explaining the Ar recovery method according to the present invention. Usually, Ar
As shown in FIG. 3, the raw material Ar gas is extracted from the middle part of the upper tower 3 of the rectification column 1 provided in the air liquefaction / separation apparatus and sent to the crude Ar column 6. The purity of Ar is increased by an Ar purification system provided downstream thereof, and the Ar is recovered as product Ar.

FIG. 3 is a boiling point diagram of N ₂ and O ₂ . As shown in the figure, the liquid phase region is above the line connecting L ₁ , L ₂ , and L ₃ . V ₁ , V ₂ , V ₃
Below the line connecting is the gas phase region. Further, between these lines is a gas-liquid mixing region.

As shown in FIG. 2, the upper column 3 of the double rectification column 1
Inside, the temperature is lower at the upper part and higher at the lower part. For example, if the gas V ₁ is in contact with the liquid L ₁ of lower than this elevated temperature, it is condensed as the temperature decreases. However, N ₂ of the low boiling point is not condensed, as it rises, as rises to V ₁ ~V ₂ ~V _3, so that the N ₂ concentration increases. At that time, the gas V ₂ rising liquid L ₁ and from this, the gas V ₃ rising liquid L ₂ and from which, in equilibrium. On the other hand, L _{1 to} L ₂
As it descends to ~L _3, it will become a high-boiling liquid,
As a result, the O ₂ concentration increases toward the bottom.

Therefore, in the upper tower 3, N ₂ having the highest boiling point among the three components is recovered from the upper part, and O ₂ having the lowest boiling point is recovered from the lower part. On the other hand, Ar having a middle boiling point in the three components is concentrated in the middle part of the upper tower 3, so that
The raw material Ar gas is extracted from the middle part of the upper tower 3.

As described above, the Ar recovery apparatus 20 of the present embodiment has three locations including the source Ar gas extraction section 21 at the middle part of the upper tower 3 including the extraction section during rated operation.
a, 21b and 21c are provided. Further, the branch pipe 22 connected to each of the extraction portions 21a, 21b, 21c.
a, 22b, and 22c include on-off valves 24a, 24b, and 24, respectively.
c are interposed.

Thus, in accordance with a change in the Ar concentration distribution due to a change in the operation load of the air liquefaction / separation apparatus 1, each of the extraction sections 21a,
The opening / closing valves 24a, 24b, 24c of 21b, 21c are selectively opened. In FIG. 1, for example, during rated operation (A
The r concentration distribution B) opens only the on-off valve 24b of the extraction part 21b. On the other hand, when the operating load is increased (for example, Ar concentration distribution A), only the on-off valve 24a of the extraction unit 21a is opened, and when the operating load is decreased (for example, Ar concentration distribution C), only the on-off valve 24c of the extraction unit 21c is opened. Is what you do.

Therefore, even if the Ar concentration distribution changes as A, B, and C in the upper tower 3 due to a change in operating conditions, the upper tower 3
Opening / closing valves 24a, 24a of the extraction portions 21a, 21b, 21c provided at locations where the Ar concentration distribution peaks in the inside.
b and 24c are selectively opened to provide a high concentration of A
The raw Ar gas containing r can be sent to the crude Ar tower 6 and an Ar recovery rate equivalent to that during the rated operation can be secured.

In the middle part of the upper tower 3, the respective detection ends are located at positions corresponding to the positions where the respective extraction parts 21a, 21b, 21c are installed. Analyzers 27a, 27b, 2 for detecting
7c is provided. That is, these analyzers 27a,
With 27b and 27c, a change in the Ar concentration distribution in the upper tower 3 due to a change in the operation load of the air liquefaction / separation device can be accurately grasped.

Therefore, when the manual operation is performed, if the analysis results of the analyzers 27a, 27b, 27c are displayed, the operator can selectively select the on-off valves 24a, 24b, 24c based on the analysis results. Can be opened to the public.

On the other hand, when the automatic operation is performed, the following is performed. That is, the analyzers 27a, 27b, 2
7c and the opening / closing valves 24a, 24b, 24c receive a detection signal of each analyzer 27a, 27b, 27c and control the opening / closing of each opening / closing valve 24a, 24b, 24c.
Is connected.

Accordingly, based on the analysis results of the analyzers 27a, 27b and 27c, the controller 28 controls the extraction section 21 where the Ar concentration distribution in the upper tower 3 has a peak.
The opening / closing valves 24a, 24b, 24c of a, 21b, 21c can be selectively and automatically opened.

That is, the Ar recovery method of the present embodiment
Each extraction part 21 installed at three places in the middle part of the upper tower 3
a, 21b, and 21c, of the internal gas at locations corresponding to
₂ and the Ar concentration were determined by the analyzers 27a, 27b, 27
Analyze by c. Next, each of the analyzers 27a, 27b,
The detection signal of 27c is transmitted to the control device 28. Then, based on the analysis result received, the control device 28 reduces the N2 that hinders the rectification action in the crude Ar tower 6 and removes the extraction portions 21a, 21b, 2 with a high concentration of Ar.
This is achieved by selectively opening the on-off valves 24a, 24b, 24c of 1c.

Therefore, the location where the Ar concentration distribution peaks in the upper tower 3 is accurately grasped, and the raw material Ar gas is extracted from the extraction sections 21a, 21b and 21c installed at the location, and the raw Ar gas is supplied to the crude Ar tower 6. Therefore, an Ar recovery rate equivalent to that at the time of rated operation can be secured, and automatic operation of Ar recovery can be achieved in response to fluctuations in the operation load of the air liquefaction / separation apparatus.

As described above, since the source Ar gas was extracted only at one point in accordance with the rated operation in the related art, the Ar recovery rate was reduced when the operation load of the air liquefaction / separation apparatus fluctuated. In addition, even when the operating load fluctuates, the active Ar collection can be performed, and the collection rate can be improved.

[0041]

As described above, according to the Ar recovery apparatus and the recovery method according to the present invention, even if the operating load of the air liquefaction / separation apparatus fluctuates, an Ar recovery rate equivalent to that during rated operation can be obtained. The effect is excellent.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of an Ar recovery apparatus according to the present invention.

FIG. 2 is a boiling point diagram of N ₂ and O ₂ .

FIG. 3 is an explanatory diagram showing a rectification part of an air liquefaction / separation apparatus provided with a conventional Ar recovery apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rectification tower 2 Lower tower 3 Upper tower 6 Cr-Ar tower 20 Ar recovery device 21a, 21b, 21c Extraction part 24a, 24b, 24c On-off valve 26 Cr-Ar

Continuation of front page (72) Inventor Toshio Ota 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Central Research Division (56) References JP-A-54-39396 (JP, A) JP-A-3 −244990 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F25J 1/00-5/00 C01B 23/00

Claims (4)

(57) [Claims] 1. An apparatus provided with a crude Ar tower and a downstream side of the crude Ar tower, the oxygen gas having a high argon content (referred to as raw material Ar gas) extracted from the middle part of the upper tower of the rectification tower provided in the air liquefaction separation apparatus. In the Ar recovery apparatus for rectifying and separating Ar by introducing into the upper tower, at a middle portion of the upper tower, a plurality of extraction portions for the raw material Ar gas including the extraction portion at the time of rated operation are provided, and each extraction portion and the crude Ar gas are provided. An Ar recovery device, wherein an on-off valve is interposed between the tower and the tower. _2. The Ar according to claim 1, further comprising: an analyzer for detecting the concentration of oxygen (hereinafter referred to as O ₂ ) and Ar in the internal gas of each of the extraction sections, at an intermediate portion of the upper tower.
Collection device. 3. The Ar recovery device according to claim 2, wherein a controller that receives a detection signal of the analyzer and controls opening and closing of the on-off valve is connected to the analyzer and the on-off valve. 4. A raw Ar gas is extracted from an intermediate portion of an upper column of a rectification column provided in an air liquefaction / separation apparatus and sent to a crude Ar column, and Ar gas is supplied to the crude Ar column and a device provided downstream thereof. In the Ar recovery method of rectifying and separating the gas, O ₂ and Ar concentration of the internal gas of each of the extraction sections installed at a plurality of locations in the middle part of the upper tower are analyzed, and the crude Ar tower is analyzed based on the analysis result. An Ar recovery method, characterized in that the raw material Ar gas is extracted from an extraction portion having a small amount of nitrogen and a high concentration of Ar which hinders the rectification of the Ar.