Air separation device

Abstract

To provide an air separation device capable of making a cold box compact by reducing a diameter of an argon tower without reducing a recovery rate of argon.SOLUTION: An air separation device 100 comprises an argon tower for refining argon from air. The air separation device includes a low pressure tower 600, the low pressure tower 600 is a plate tower, and the argon tower is a regularly filled tower. A regular filler filling the regularly filled tower is a structure in which a metallic wave plate piece 81 on which wave plate processing is performed is overlapped and bundled in such a manner that a surface is in a tower axis direction of the argon tower. A specific surface area is 750 m2 / m3 or more, and a wave tilt angle which is an angle formed from a line connecting peaks of waves on the surface of the wave plate piece and a vertical line to the tower axis of the argon tower is 40° or less. In a cross-sectional view in a thickness direction of the wave plate piece, a curvature circle diameter of the peak of each wave is 60% or more of a crest height that is a distance between the peak of the wave and a bottom of the wave.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an air separation device having an argon column, and more particularly to an air separation device that directly collects argon without adding hydrogen.

Background Art

[0002] In a relatively small-scale air separation device that collects argon without adding hydrogen, a plate column is used for both the high-pressure column and the low-pressure column, and a combination of a plate column and a packed column is used for the argon column. The use of a plate column in the argon column is to lower the pressure by utilizing the high pressure loss caused by the plates, and increase the relative volatility of argon with respect to oxygen in the packed column provided downstream thereof, in order to increase the recovery rate of argon.

[0003] Patent Documents 1 and 2 disclose air separation devices using such a plate column as an argon column. FIG. 6 shows an example of an air separation device disclosed in Patent Documents 1 and 2. The air separation device 101 includes a high-pressure column 500, a low-pressure column 600, and an argon column composed of a crude argon column 711 and a deoxidation column 721. A plate column is used for both the high-pressure column 500 and the low-pressure column 600. A combination of a plate column and a structured packed column (a packed column filled with structured packing) is used for the crude argon column 711.

[0004] Part of the compressed and purified raw air is supplied to the heat exchanger 201 through the pipeline 21. The purified raw air is cooled by heat exchange with the nitrogen gas supplied from the top of the low-pressure column 600 through the pipeline 2, the exhaust gas supplied from the heat exchanger 202 through the pipeline 3, and the liquid oxygen supplied from the main condenser 300 through the pipeline 1 in the heat exchanger 201. Then, it is supplied to the bottom of the high-pressure column 500 through the pipeline 22. Another part of the purified raw air is pressurized and then supplied to the heat exchanger 201 through the pipeline 11, liquefied, and supplied to the lower part of the high-pressure column 500 through the pipeline 12.

[0005] The air supplied through pipeline 22 to the bottom of the high-pressure column 500 comes into gas-liquid contact with the reflux liquid flowing down inside the high-pressure column 500. While rising, nitrogen, which is a low-boiling component, is concentrated, and nitrogen gas is generated at the top of the column. Also, the reflux liquid flowing down inside the high-pressure column 500, which includes the liquid air supplied from pipeline 12 below the high-pressure column 500, becomes enriched with oxygen, which is a high-boiling component, while descending, and oxygen-enriched liquid air is generated at the bottom of the column. The generated liquid air is withdrawn through pipeline 51 from the lower part of the high-pressure column 500.

[0006] The nitrogen gas generated in the high-pressure column is liquefied in the main condenser 300. A part of it is supplied through pipeline 61 to the heat exchanger 202, cooled, decompressed through pipeline 62, and then supplied as reflux liquid to the top of the low-pressure column 600.

[0007] The oxygen-enriched liquid air generated at the bottom of the high-pressure column 500 is supplied through pipeline 41 to the heat exchanger 202, cooled, decompressed through pipeline 42, and then introduced into the argon condenser 400, which is the top condenser of the deoxidation column 721. The introduced oxygen-enriched liquid air evaporates and is supplied to the low-pressure column 600. On the other hand, the liquid air withdrawn through pipeline 51 from below the high-pressure column 500 is supplied to the heat exchanger 202, cooled, decompressed through pipeline 52, and then supplied to the low-pressure column 600 to become reflux liquid. The reflux liquid supplied to the low-pressure column 600 comes into gas-liquid contact with the rising gas inside the column. While flowing down, oxygen, which is a high-boiling component, is concentrated, and liquid oxygen is generated at the bottom of the column. Also, while rising, the rising gas becomes enriched with nitrogen, which is a low-boiling component, and nitrogen gas is generated at the top of the column.

[0008] Also, from the middle part of the low-pressure column 600, argon column feed gas with an argon concentration of 5% to 15% (the remaining components are mostly oxygen) is withdrawn through the pipeline 31 and supplied to the bottom of the crude argon column 711. The supplied argon column feed gas rises while concentrating the low-boiling component argon. Then, it is introduced from the crude argon column 711 to the bottom of the deoxidation column 721 and rises in the deoxidation column 721. During the rise, oxygen is removed, and at the top of the deoxidation column 721, the oxygen is removed to 0.1 ppm to 10 ppm. The gas taken out from the top of the deoxidation column 721 is liquefied in the argon condenser 400, a part of which is collected as product argon, and the rest is returned to the deoxidation column 721 as reflux liquid.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] As the deoxidation column 721, a structured packing column with a small pressure loss is used. A structured packing column is used in the upper part of the crude argon column 711, and a tray column with a large pressure loss is used in the lower part. Since a tray column is used in the lower part of the crude argon column 711, the pressure of the argon column feed gas supplied to the bottom has a large loss, and even in the low tray column, its pressure decreases. The feed gas supplied to the argon column rises while the pressure decreases in the tray column, and then, in the upper part of the crude argon column 711, which is a structured packing column, and in the deoxidation column 721, the relative volatility of argon is increased, and argon is concentrated with high separation efficiency. Compared with a structured packing column, the tray column has a larger column diameter for treating the same gas-liquid load. As shown in Fig. 6, only the lower part of the crude argon column 711 becomes thick, and there is a problem that the cold box for housing these columns and preventing heat input from the outside becomes inefficiently large.

[0011] The present invention provides an air separation apparatus capable of reducing the diameter of an argon column and making the cold box compact without reducing the recovery rate of argon.

Means for Solving the Problems

[0012] To solve such problems, the present invention provides the following air separation apparatus. [1] An air separation apparatus including an argon column for purifying argon from air, having a low-pressure column, wherein the low-pressure column is a tray column, the argon column is a structured packing column, the structured packing filled in the structured packing column is a structure in which corrugated metal corrugated sheets are stacked such that their surfaces are along the column axis direction of the argon column, and the specific surface area thereof is 750 m 2 / m 3 or more, a wave inclination angle, which is an angle formed by a line connecting the peaks of the waves on the surface of the corrugated sheet and a perpendicular line to the column axis of the argon column, is 40° or less, in a cross-sectional view in the thickness direction of the corrugated sheet, the diameter of the curvature circle at the top of each wave is 60% or more of the mountain height, which is the distance between the top of the wave and the bottom of the wave, the air separation apparatus. [2] The argon column is divided into a first column and a second column, the first column is a crude argon column for concentrating argon in the argon column raw material gas from the low-pressure column, the second column is a deoxidation column for removing oxygen from the gas in which the argon obtained in the crude argon column is concentrated, further having a pipeline for supplying gas from the crude argon column to the deoxidation column, the first and second columns are each the structured packing column according to [1] described air separation apparatus. [3] A pressure reducing valve is provided in the pipeline for supplying the gas in which argon is concentrated from the crude argon column to the deoxidation column according to [2] described air separation apparatus.

Effects of the Invention

[0013] According to the air separation device of the present invention, it is possible to reduce the diameter of the argon column and make the cold box compact without reducing the recovery rate of argon. Furthermore, since the air separation device of the present invention uses a tray column as the low-pressure column, the pressure of the argon column raw material gas supplied to the argon column is not greatly reduced. Therefore, in the argon condenser, a sufficient temperature difference can be ensured to generate the reflux liquid of the argon column.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0015] Hereinafter, an air separation device which is an embodiment to which the present invention is applied will be described in detail with reference to the drawings. Note that the drawings used in the following description may show the characteristic parts enlarged for the sake of easy understanding of the characteristics, and the dimensional ratios of the respective components are not necessarily the same as the actual ones. In this specification, the numerical range represented by "~" means a numerical range with the numerical values before and after "~" as the lower limit value and the upper limit value, respectively.

[0016] FIG. 1 shows an air separation apparatus using an argon column equipped with structured packings. The air separation apparatus 100 shown in FIG. 1 includes an argon column having a high-pressure column 500, a low-pressure column 600, a crude argon column (first column) 710, and a deoxidation column (second column) 720. In the air separation apparatus 100 of the present embodiment, a tray column is used as the low-pressure column 600. In the air separation apparatus 100 of the present embodiment, the argon column is divided into a crude argon column 710 and a deoxidation column 720 and has two columns, but the argon column is not separated into two columns and may be composed of one column. In the case of being composed of one column, the crude argon column 710 and the deoxidation column 720 are integrated as a single cylinder without passing through pipelines 73 and 74. However, in order to reduce the height of the cold box for holding these devices operated at extremely low temperatures, it is preferable that the argon column is divided into two columns.

[0017] In the present embodiment, it is preferable that the argon column does not include a tray column which is a cause of the increase in the column diameter. When the argon column does not include a tray column, the column diameter of the argon column can be reduced. Generally, sieve trays are used in a tray column, and gas contacts the liquid flowing vertically with respect to the column axis on the tray in a cross shape to separate argon, which is a low-boiling component.

[0018] In the air separation apparatus 100 of the present embodiment, the same structured packings are filled in the crude argon column 710 and the deoxidation column 720 that constitute the argon column, but different structured packings can also be filled. In that case, the structured packings may be selected so that the argon column and the cold box become compact in consideration of the separation performance and the pressure loss.

[0019] The configuration of the air separation apparatus 100 using the above argon column will be described in detail below. Part of the compressed and purified raw air is supplied to the heat exchanger 201 through the pipeline 21. In the heat exchanger 201, the purified raw air is cooled by heat exchange with the nitrogen gas supplied from the top of the low-pressure column 600 through the pipeline 2, the exhaust gas supplied from the pipeline 3, and the liquid oxygen supplied from the main condenser 300 through the pipeline 1. Then, it is supplied to the bottom of the high-pressure column 500 through the pipeline 22. Another part of the purified raw air is pressurized and then supplied to the heat exchanger 201 through the pipeline 11, liquefied, and supplied to the lower part of the high-pressure column 500 through the pipeline 12.

[0020] The air supplied to the bottom of the high-pressure column 500 through the pipeline 22 undergoes gas-liquid contact with the reflux liquid flowing down inside the high-pressure column 500, and while rising, nitrogen, which is a low-boiling component, is concentrated, and nitrogen gas is generated at the top of the column. Also, the reflux liquid flowing down inside the high-pressure column 500, including the liquid air supplied from the pipeline 12 to the lower part of the high-pressure column 500, is enriched with oxygen, which is a high-boiling component while descending, and oxygen-enriched liquid air is generated at the bottom of the column. The generated liquid air is withdrawn from the lower part of the high-pressure column 500 through the pipeline 51.

[0021] The nitrogen gas generated in the high-pressure column 500 is liquefied in the main condenser 300. A part of it is supplied to the heat exchanger 202 through the pipeline 61, cooled, and then supplied as reflux liquid to the top of the low-pressure column 600 after being depressurized through the pipeline 62.

[0022] The oxygen-enriched liquid air generated at the bottom of the high-pressure column 500 is supplied to the heat exchanger 202 through the pipeline 41, cooled, depressurized through the pipeline 42, and then introduced into the argon condenser 400, which is the top condenser of the argon column. The introduced oxygen-enriched liquid air evaporates and is supplied to the low-pressure column 600. On the other hand, the liquid air withdrawn from below the high-pressure column 500 through the pipeline 51 is supplied to the heat exchanger 202, cooled, depressurized through the pipeline 52, and then supplied to the low-pressure column 600 to become the reflux liquid. The reflux liquid supplied to the low-pressure column 600 flows down while coming into gas-liquid contact with the rising gas in the column, and oxygen, which is a high-boiling component, is concentrated, and liquid oxygen is generated at the bottom of the column. Also, the rising gas rises while nitrogen, which is a low-boiling component, is concentrated, and nitrogen gas is generated at the top of the column.

[0023] Also, an argon column feed gas with an argon concentration of 5% to 15% (the remaining components are mostly oxygen) is withdrawn from the middle part of the low-pressure column 600 through the pipeline 31 and supplied to the bottom of the crude argon column 710. The supplied argon column feed gas rises while concentrating the low-boiling component argon. Then, it is introduced from the top of the crude argon column 710 to the bottom of the deoxidation column 720 and rises in the deoxidation column 720. During the rise, oxygen is removed, and at the top of the deoxidation column 720, the oxygen is removed to 0.1 ppm to 10 ppm. The gas taken out from the top of the deoxidation column 720 is liquefied in the argon condenser 400, a part of which is collected as product argon, and the rest is returned to the deoxidation column 720 as reflux liquid.

[0024] When the argon column is divided into a crude argon column 710 and a deoxidation column 720, it is preferable that a pressure reducing valve 70 is provided in the pipeline 73 that introduces the gas obtained by concentrating argon in the crude argon column 710 from the top of the crude argon column 710 to the bottom of the deoxidation column 720. By providing the pressure reducing valve 70 in the pipeline 73, even when the pressure loss of the crude argon column 710 decreases during reduced load operation or the like, the pressure of the deoxidation column 720 can be adjusted, and the argon recovery rate can be increased.

[0025] Hereinafter, the structured packings filled in the crude argon column 710 and the deoxidation column 720 will be described. FIG. 2 shows an example of the structured packing used in the argon column of the air separation apparatus of the present invention. FIGS. 3A and 3B show the corrugated sheet pieces forming the structured packing provided in the argon column of the air separation apparatus of the present invention, and are diagrams for explaining the wave inclination angle. FIG. 4 is a cross-sectional view of the corrugated sheet piece along the line A-A' shown in FIG. 3, and is a diagram for explaining the top curvature circle diameter ratio.

[0026] The structured packing is a structure obtained by laminating a plurality of corrugated sheet pieces 81 as shown in FIGS. 3A and 3B. The corrugated sheet piece 81 may be a metal sheet formed with a waveform. Here, "laminating" means a state in which the corrugated sheet pieces 81 are bundled with their front and back surfaces alternating in the orientation of the wave inclination angle α. Specifically, it means a state in which a plurality of corrugated sheet pieces 81 having the same wave inclination angle α are bundled with their front and back surfaces alternating so as not to overlap each other. The corrugated sheet pieces 81 to be bundled may not all have the same size, and corrugated sheet pieces 81 having different sizes may be overlapped and bundled. When the argon column is cylindrical, as shown in FIG. 2, a plurality of corrugated sheet pieces 81 having different sizes may be overlapped, and the periphery of the overlapped corrugated sheet pieces 81 may be bundled with a frame to form a cylindrical shape. The shape is not limited to a cylindrical shape. It is preferable that a plurality of corrugated sheet pieces 81 can be overlapped and treated as a lump. Note that the method of bundling each corrugated sheet piece 81 is not particularly limited, and in this embodiment, a metal band is used as a frame for bundling. As the material of the corrugated sheet piece 81, a metal is preferable. Among metals, aluminum is preferable.

[0027] Hereinafter, the corrugated sheet piece 81 will be described in detail. As shown in FIGS. 3A and 3B, a waveform is formed on the surface of the corrugated sheet piece 81, and further, through holes 82 are provided. The waveform is formed such that the wave inclination angle α, which is the angle formed by the line connecting the tops of the waveforms and the perpendicular line to the column axis of the argon column, is 40° or less. That is, the line connecting the tops of the waves provided on the corrugated sheet piece 81 is perpendicular to the column axis of the argon column or is inclined at an angle of 50° or more with respect to the column axis. FIG. 3A shows the corrugated plate 81 having a wave inclination angle α of 40° or less counterclockwise with respect to the vertical line to the tower axis of the argon column, and FIG. 3B shows the corrugated plate 81 having an inclination angle α of 40° or less clockwise with respect to the vertical line to the tower axis of the argon column. The reflux liquid descending the argon column flows down along the corrugated plate 81, and the ascending gas flows between the corrugated plates 81 where the reflux liquid flows down, and the gas and liquid come into contact. The through-hole 82 enables the gas-liquid movement in the tower radius direction and suppresses the uneven flow. Here, if the wave inclination angle α provided on the corrugated plate 81 is 40° or less, the flow resistance of the gas ascending between the corrugated plates 81 of the argon column is increased, and a sufficiently high pressure loss is obtained to increase the relative volatility of argon, and the argon column can be reduced in diameter without reducing the argon recovery rate.

[0028] Further, when viewing the thickness direction of the corrugated plate 81 in cross section, if the distance between the wave top and the wave bottom is defined as the mountain height, the ratio of the diameter of the curvature circle of each wave top in the cross-sectional view in the thickness direction of the corrugated plate 81 to the mountain height (hereinafter, may be referred to as the "top curvature circle diameter ratio") is 60% or more. That the top curvature circle diameter ratio is 100% means that the inclination of the wave in the corrugated plate 81 is zero. Therefore, for the wave shape, the top curvature circle diameter ratio must be less than 100%. If the top curvature circle diameter ratio is 60% or more, high separation performance can be obtained even if a high pressure loss occurs, so the argon column can be reduced in diameter without increasing the height of the argon column.

[0029] The specific surface area of the corrugated plate 81 is 750 m 2 / m 3 or more. If the specific surface area is 750 m 2 / m 3 or more, the separation efficiency in the argon column can be improved. More preferably, it is 920 m 2 / m 3 The specific surface area of the corrugated plate 81 is 750 m 2 / m 3 or more, the gas ascending the argon column and the fluid descending the argon column come into sufficient contact, and thus the argon column can be reduced in diameter without reducing the argon recovery rate. Note that by adjusting the above-mentioned top curvature circle diameter ratio, the specific surface area of the corrugated plate piece 81 can be adjusted. By setting each top curvature circle diameter ratio to 60% or more, the specific surface area of the corrugated plate piece 81 can be easily made 750 m 2 / m 3 or more.

[0030] In this embodiment, any corrugated plate piece 81 with a wave inclination angle α and a top curvature circle diameter ratio within the above ranges can be used.

Example

[0031] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples.

[0032] Reference Example 1 Table 1 shows the results of an argon-oxygen system total reflux distillation test using a regular packing tower with a tower diameter of 300 mm, a packing height of 1500 mm, a specific surface area of 750 m 2 / m 3 , a wave inclination angle α of 40°, and a top curvature circle diameter ratio of 80%, that is, a regular packing a750_α40D80. The HETP and the pressure loss obtained at different gas loads (factor based on the superficial velocity: fs) are shown. In Table 1, the measurement results of the comparative packing a750_α45D50 (specific surface area: 750 m 2 / m 3 , wave inclination angle: 45°, top curvature circle diameter ratio: 50%) are also shown. HETP is the packing height per theoretical stage, and was obtained by dividing the packing height by the number of theoretical stages calculated from the measured oxygen concentrations at the top and bottom of the tower. The values in the table are the measured HETP normalized by the HETP at fs = 1.7 m / s (kf / m 3 ) 0.5 of the comparative packing. The pressure loss is the pressure difference per unit packing height, and was obtained by dividing the measured value of the differential pressure between the top and bottom of the tower by the packing height. The values in the table are the pressure loss normalized by the pressure loss at fs = 1.7 m / s (kf / m 3 ) 0.5 of the comparative packing.

[0033]

Table 1

[0034] In the conventional argon column, the comparative packing a750_α45D50 is used. As shown in Table 1, compared with the comparative packing, it can be seen that the implemented packing has a high pressure loss and high separation performance. Also, when the load is increased with the comparative packing, it can be seen that the pressure loss increases, but the separation performance remains unchanged and does not reach the separation performance of the implemented packing.

[0035] (Example 1) To calculate the separation behavior of a structured packing column using the structured packing a750_α40D80 (specific surface area: 750 m 2 / m 3 , wave tilt angle: 40°, top curvature circle diameter ratio: 80%), the simulator used in the design of the structured packing column of the air separation device was used. The simulator calculates the separation behavior from the heat through the gas-liquid interface and the mass transfer rate, and can be applied even when changing the structured packing (specific surface area, wave tilt angle, and top curvature circle diameter ratio) by incorporating the separation performance obtained in the test. Also, a pressure loss calculation formula based on the test is incorporated. Figure 5 shows the simulation results of the separation behavior of the crude argon column and the deoxidation column using the structured packing a750_α40D80 in the air separation device of Figure 1.

[0036] (Comparative Example 1) In the air separation device of Figure 6, a simulation of the separation behavior of an argon column having a tray column at the lower part and a crude argon column using the aforementioned comparative packing a750_α45D50 (specific surface area: 750 m 2 / m 3 , wave tilt angle: 45°, top curvature circle diameter ratio: 50%) and a deoxidation column also using the comparative packing a750_α45D50 was performed. The results are shown in Figure 5.

[0037] The vertical axis in Fig. 5 is the vapor-phase oxygen concentration, and the horizontal axis is the packing height (with the top of the column being 0) when the packing height of the argon column in Comparative Example 1 is taken as 1. For the sieve tray column, the horizontal axis (packing height) is the value obtained by dividing the tray spacing by the tray efficiency and integrating up to the number of theoretical trays.

[0038] In Fig. 5, the solid line represents the oxygen concentration distribution in the argon column of Example 1, and the dashed line represents the oxygen concentration distribution in the argon column of Comparative Example 1. As shown in Fig. 5, it was found that argon containing 1 ppm of oxygen can be obtained at approximately the same packing height in the argon column of Example 1 and the argon column of Comparative Example 1. This indicates that the argon recovery rate in Example 1 has not decreased compared to Comparative Example 1.

[0039] Also, Fig. 5 shows the column diameter of the crude argon column (with the sieve tray column diameter taken as 1). It was found that the column diameter of the crude argon column in Example 1 could be reduced by 25% or more compared to the column diameter of the sieve tray column part in Comparative Example 1. This enables the cold box to be made more compact.

[0040] (Example 2) The argon column consists of a deoxidation column and a crude argon column, and is filled with regular packing a750_α35D80 (specific surface area: 750 m 2 / m 3 , wave tilt angle: 35°, top curvature circle diameter ratio: 80%). A pressure reducing valve 70 is provided in the pipeline 73 connecting the two columns. A simulation of the separation behavior of the argon column was carried out in the same manner as in Example 1, except that the air separation device shown in Fig. 1 was used. The results are shown in Table 2 below.

[0041] (Example 3) The argon column consists of a deoxidation column and a crude argon column, and is filled with regular packing a920_α40D80 (specific surface area: 920 m 2 / m 3, the wave tilt angle: 40°, the top curvature circle diameter ratio: 80%) was filled, and a pressure reducing valve 70 was provided in the pipeline 73 connecting the two towers. Except for using the air separation device shown in Fig. 1, the separation behavior of the argon tower was simulated in the same manner as in Example 1. The results are shown in Table 2 below. In addition, the results of Example 1 are also shown in Table 2 below.

[0042] (Example 4) The argon tower consists of a deoxidation tower and a crude argon tower. The deoxidation tower is filled with structured packing a750_α40D60 (specific surface area: 750 m 2 / m 3 , the wave tilt angle: 40°, the top curvature circle diameter ratio: 60%), and the crude argon tower is filled with structured packing a750_α35D80 (specific surface area: 750 m 2 / m 3 , the wave tilt angle: 35°, the top curvature circle diameter ratio: 80%). Except for using the air separation device shown in Fig. 1, the separation behavior of the argon tower was simulated in the same manner as in Example 1. The results are shown in Table 2 below.

[0043] (Example 5) The argon tower consists of a deoxidation tower and a crude argon tower. The deoxidation tower is filled with structured packing a750_α40D70 (specific surface area: 750 m 2 / m 3 , the wave tilt angle: 40°, the top curvature circle diameter ratio: 70%), and the crude argon tower is filled with structured packing a920_α40D80 (specific surface area: 920 m 2 / m 3 , the wave tilt angle: 40°, the top curvature circle diameter ratio: 80%). Except for using the air separation device shown in Fig. 1, the separation behavior of the argon tower was simulated in the same manner as in Example 1. The results are shown in Table 2 below.

[0044]

Table 2

[0045] As shown in Table 2 above, it was found that, compared with Comparative Example 1, argon containing 1 ppm of oxygen can be obtained at a filling height almost equal to or lower than that of any of the Examples. Also, it was found that in Examples 2, 3, 4, and 5, the diameter of the argon column can be reduced to the same extent as in Example 1. It was also found that the larger the specific surface area and the smaller the wave inclination angle α, the lower the filling height can be. However, since the pressure loss increases, the temperature difference of the argon condenser becomes smaller and the heat transfer area increases. Therefore, the regular packing is selected so that the cold box becomes compact in consideration of the equipment layout in the cold box.

Industrial Applicability

[0046] According to the air separation apparatus of the present invention, it is possible to reduce the diameter of the argon column and make the cold box compact without reducing the recovery rate of argon. As a relatively small-scale air separation apparatus, the air separation apparatus of the present invention is useful.

Explanation of Symbols

[0047] 1, 2, 3, 11, 12, 21, 22, 31, 51, 61, 73 pipelines 70 pressure reducing valve 81 corrugated plate piece 82 through hole 100, 101 air separation apparatus 201 heat exchanger 300 main condenser 400 (argon column) top condenser 500 high pressure column 600 low pressure column 710, 711 crude argon column 720, 721 deoxidation column

Claims

1. An air separation apparatus comprising an argon column for purifying argon from air, having a low-pressure column, wherein the low-pressure column is a plate column, the argon column is a structured packing column, The structured packing filled in the structured packing column is a structure formed by stacking corrugated metal sheets processed by corrugation so that their surfaces are along the column axis direction of the argon column, and its specific surface area is 750 m ２ / m ３ or more, the wave inclination angle, which is the angle formed by a line connecting the peaks of the waves on the surface of the corrugated sheet and a perpendicular line to the column axis of the argon column, is 40° or less, when the thickness direction of the corrugated sheet is viewed in cross section, the diameter of the curvature circle at the peak of each wave is 60% or more of the mountain height, which is the distance between the peak and the bottom of the wave, the air separation apparatus.

2. the argon column is divided into a first column and a second column, the first column is a crude argon column for concentrating argon in the argon column raw material gas from the low-pressure column, the second column is a deoxidation column for removing oxygen from the gas in which argon obtained in the crude argon column is concentrated, further having a gas supply line for supplying gas from the crude argon column to the deoxidation column, the air separation apparatus according to claim 1, wherein the first and second columns are each the structured packing column.

3. The air separation apparatus according to claim 2, wherein a pressure reducing valve is provided in the gas supply line for supplying the gas in which argon is concentrated from the crude argon column to the deoxidation column.

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