Nitrogen gas purification device

Abstract

The purpose of the present invention is to provide a nitrogen gas purification device which enables the removal of impurity gases which are difficult to remove at ordinary temperature. This nitrogen gas purification device includes an adsorption part, an introduction path to the adsorption part, and a discharge path from the adsorption part. In the nitrogen gas purification device, impurity gases contained in nitrogen gas introduced into the adsorption part through the introduction path are adsorbed in the adsorption part and the thus-purified nitrogen gas is discharged from the adsorption part to the discharge path. The introduction path has a heat exchanger for cooling the nitrogen gas by heat exchange with liquefied nitrogen.

Description

Nitrogen Gas Purification Equipment

[0001] The present invention relates to a nitrogen gas purification device.

[0002] A nitrogen gas purification apparatus is known that includes an adsorption device that adsorbs impurity gases in introduced nitrogen gas at room temperature (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2003-146628

[0004] The nitrogen gas purification device as described above can remove impurity gases such as moisture, but it is difficult to remove impurity gases such as hydrocarbons.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a nitrogen gas purification apparatus capable of removing impurity gases that are difficult to remove at room temperature.

[0006] One aspect of the present invention is as follows.

[0007] [1] A nitrogen gas purification device having an adsorption unit, an inlet path to the adsorption unit, and an outlet path from the adsorption unit, in which impurity gases in nitrogen gas introduced from the inlet path into the adsorption unit are adsorbed by the adsorption unit, and the purified nitrogen gas is discharged from the adsorption unit to the outlet path, wherein the inlet path has a heat exchanger that cools the nitrogen gas by heat exchange with liquefied nitrogen.

[0008] [2] The nitrogen gas purification apparatus according to [1], wherein the inlet path has a secondary heat exchanger located upstream of the heat exchanger, which cools the nitrogen gas flowing through the inlet path by heat exchange with the nitrogen gas flowing through the exhaust path.

[0009] [3] The nitrogen gas purification apparatus according to [2], further comprising a thermostatic chamber having a thermostatic chamber surrounded by a vacuum insulation unit, wherein the adsorption unit and the heat exchanger are provided in the thermostatic chamber, and the auxiliary heat exchanger is provided in the vacuum insulation unit.

[0010] [4] The nitrogen gas purifying apparatus according to [3], further comprising a control unit that adjusts the flow rate and temperature of the liquefied nitrogen introduced into the heat exchanger so that the temperature of a predetermined portion in the temperature-controlled chamber is −160° C. or higher and −100° C. or lower.

[0011] [5] A nitrogen gas purification system comprising: the nitrogen gas purification device (A) according to any one of [1] to [4]; the nitrogen gas purification device (B) according to any one of [1] to [4]; a common inlet path branching into an inlet path (A) of the nitrogen gas purification device (A) and an inlet path (B) of the nitrogen gas purification device (B); and a common exhaust path where the exhaust path (A) of the nitrogen gas purification device (A) and the exhaust path (B) of the nitrogen gas purification device (B) join together, wherein the nitrogen gas introduced from the common inlet path and discharged to the common exhaust path is purified by alternately using the nitrogen gas purification device (A) and the nitrogen gas purification device (B).

[0012] According to the present invention, it is possible to provide a nitrogen gas purification device capable of removing impurity gases that are difficult to remove at room temperature.

[0013] 1 is a schematic diagram illustrating a nitrogen gas purification system according to an embodiment of the present invention.

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] As shown in Figure 1, in one embodiment of the present invention, the nitrogen gas purification apparatus 1 has an adsorption section 2, an inlet path 3 to the adsorption section 2, and an outlet path 4 from the adsorption section 2. The nitrogen gas purification apparatus 1 adsorbs impurity gases (e.g., oxygen, carbon monoxide, carbon dioxide, hydrogen, hydrocarbons, moisture, etc.) in nitrogen gas introduced into the adsorption section 2 from the inlet path 3, and then discharges the purified nitrogen gas from the adsorption section 2 to the outlet path 4. The inlet path 3 has a heat exchanger 5 that cools the nitrogen gas by heat exchange with liquefied nitrogen. The flow direction of the nitrogen gas is indicated by a thick arrow in Figure 1.

[0016] According to the above configuration, the nitrogen gas is cooled by heat exchange using liquefied nitrogen in the heat exchanger 5 provided in the introduction path 3 to the adsorption unit 2, and the nitrogen gas can be easily brought to a low temperature, for example, not lower than -160°C and not higher than -100°C, without liquefying. This makes it possible to adsorb impurity gases such as hydrocarbons that are difficult to remove at room temperature in the adsorption unit 2.

[0017] The inlet path 3 has a secondary heat exchanger 6 located upstream of the heat exchanger 5, which cools the nitrogen gas flowing through the inlet path 3 by heat exchange with the nitrogen gas flowing through the discharge path 4. According to the above configuration, the secondary heat exchanger 6 can efficiently cool the nitrogen gas flowing through the inlet path 3 by utilizing the low-temperature nitrogen gas discharged from the adsorption unit 2 and flowing through the discharge path 4.

[0018] The auxiliary heat exchanger 6 has one or more (five in this embodiment) multi-tube structures 6a each having a first tubular body 6a1 and a second tubular body 6a2 surrounding the first tubular body 6a1, and the nitrogen gas in one of the inlet path 3 and the outlet path 4 (the outlet path 4 in this embodiment) flows radially inside the first tubular body 6a1, while the nitrogen gas in the other of the inlet path 3 and the outlet path 4 (the inlet path 3 in this embodiment) flows radially outside the first tubular body 6a1 and radially inside the second tubular body 6a2. With this configuration, the multi-tube structure 6a can improve the thermal efficiency of heat exchange.

[0019] The multi-pipe structure 6a allows the nitrogen gas in the inlet path 3 and the nitrogen gas in the outlet path 4 to flow in opposite directions. According to the above configuration, the thermal efficiency of heat exchange can be further improved.

[0020] The inlet path 3 and the outlet path 4 (multi-pipe structure portion 6a) in the auxiliary heat exchanger 6 may be configured to extend linearly, but may also be configured to extend in a curved shape, such as a coil, taking into consideration space efficiency, etc.

[0021] The auxiliary heat exchanger 6 is not limited to the above configuration, but may have any configuration as long as it cools the nitrogen gas flowing through the inlet path 3 by heat exchange with the nitrogen gas flowing through the outlet path 4. The heat exchanger 5 is not particularly limited as long as it cools the nitrogen gas by heat exchange with liquefied nitrogen, and may have the same configuration as the auxiliary heat exchanger 6 or another configuration.

[0022] The nitrogen gas purification apparatus 1 includes a thermostatic chamber 7 having a thermostatic chamber 7b surrounded by a vacuum insulation section 7a. The adsorption section 2 and heat exchanger 5 are provided within the thermostatic chamber 7b, and the auxiliary heat exchanger 6 is provided within the vacuum insulation section 7a. According to the above configuration, the thermostatic chamber 7b can maintain the adsorption section 2 and the heat exchanger 5 at temperatures suitable for adsorption of impurity gases. Furthermore, by providing the auxiliary heat exchanger 6 within the vacuum insulation section 7a, the auxiliary heat exchanger 6 prevents the low-temperature nitrogen gas flowing through the discharge path 4 from being heated by the outside air, thereby more efficiently cooling the nitrogen gas flowing through the introduction path 3. The thermostatic chamber 7 includes an exterior material 7c and an interior material 7d, and a vacuum insulation section 7a is defined between the exterior material 7c and the interior material 7d. A heat insulating material such as perlite may be provided within the vacuum insulation section 7a. The liquefied nitrogen passes through the outer casing 7c and the inner casing 7d in a liquid state toward the temperature-controlled chamber 7b as shown by the white arrows in FIG. 1 and is supplied to the heat exchanger 5, and then is discharged from the temperature-controlled chamber 7b to the outside as shown by the white arrows in FIG. 1.

[0023] The nitrogen gas purification device 1 has a control unit 8 that adjusts the flow rate and temperature of the liquefied nitrogen introduced into the heat exchanger 5 so that the temperature of a predetermined portion within the temperature-controlled chamber 7b is −160° C. or higher and −100° C. or lower (preferably −145° C. or higher and −110° C. or lower, and more preferably −130° C. or higher and −120° C. or lower). With the above configuration, the temperature of the temperature-controlled chamber 7b can be easily adjusted using the control unit 8 configured by a computer.

[0024] The adsorption unit 2 has an adsorbent, such as activated carbon or zeolite, that adsorbs impurity gases in the nitrogen gas within the adsorption unit 2. More specifically, the adsorption unit 2 has a plurality of adsorption devices 2a (three in this embodiment) each having a housing with an inlet and an outlet and an adsorbent filled in the housing. In this embodiment, the plurality of adsorption devices 2a are fluidly connected in series, but this is not limiting and they may also be fluidly connected in parallel, for example. The adsorption unit 2 may also be configured to have a single adsorption device 2a.

[0025] In this embodiment, the nitrogen gas purification system 9 includes a nitrogen gas purification device (A) 1A, a nitrogen gas purification device (B) 1B, a common inlet path 10 that branches into an inlet path (A) 3A of the nitrogen gas purification device (A) 1A and an inlet path (B) 3B of the nitrogen gas purification device (B) 1B, and a common exhaust path 11 where an exhaust path (A) 4A of the nitrogen gas purification device (A) 1A and an exhaust path (B) 4B of the nitrogen gas purification device (B) 1B converge, and the nitrogen gas introduced from the common inlet path 10 and exhausted to the common exhaust path 11 is purified by alternately using the nitrogen gas purification device (A) 1A and the nitrogen gas purification device (B) 1B. According to the above configuration, the nitrogen gas purifiers (A) 1A and (B) 1B can be alternately used for purification (adsorption of impurity gases) by simply switching whether the nitrogen gas flows through the inlet path (A) 3A or the inlet path (B) 3B from the common inlet path 10. Therefore, while nitrogen gas is being purified in one of the nitrogen gas purifiers (A) 1A and (B) 1B, regeneration (desorption of impurity gases) can be performed in the other of the nitrogen gas purifiers (A) 1A and (B) 1B by, for example, raising the temperature of the adsorption section 2. Therefore, purified nitrogen gas can be continuously obtained through the common exhaust path 11.

[0026] The nitrogen gas purification system 9 includes an inlet path switching unit 12 that switches whether nitrogen gas flows from the common inlet path 10 to an inlet path (A) 3A or an inlet path (B) 3B, and an outlet path switching unit 13 that switches whether nitrogen gas flows from an outlet path (A) 4A or an outlet path (B) 4B to the common outlet path 11. Each of the inlet path switching unit 12 and the outlet path switching unit 13 can be configured, for example, by one or more valve bodies provided in the flow path. The flow path switching operation by these valve bodies (inlet path switching unit 12 and outlet path switching unit 13) can be controlled, for example, by the control unit 8.

[0027] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the above-described embodiments can be modified in various ways without departing from the gist of the present invention.

[0028] REFERENCE SIGNS LIST 1 Nitrogen gas purification device 1A Nitrogen gas purification device (A) 1B Nitrogen gas purification device (B) 2 Adsorption section 2a Adsorption device 3 Inlet path 3A Inlet path (A) 3B Inlet path (B) 4 Exhaust path 4A Exhaust path (A) 4B Exhaust path (B) 5 Heat exchanger 6 Sub-heat exchanger 6a Multi-tube structure section 6a1 First tube body 6a2 Second tube body 7 Constant temperature bath 7a Vacuum insulation section 7b Constant temperature chamber 7c Exterior material 7d Interior material 8 Control section 9 Nitrogen gas purification system 10 Common inlet path 11 Common exhaust path 12 Inlet path switching section 13 Exhaust path switching section

Claims

1. A nitrogen gas purification device having an adsorption section, an inlet path to the adsorption section, and an exhaust path from the adsorption section, and which discharges the nitrogen gas purified by adsorbing impurity gases in nitrogen gas introduced into the adsorption section from the inlet path from the adsorption section to the exhaust path, wherein the inlet path has a heat exchanger that cools the nitrogen gas by heat exchange with liquefied nitrogen.

2. A nitrogen gas purification apparatus as described in claim 1, wherein the inlet path has a secondary heat exchanger upstream of the heat exchanger for cooling the nitrogen gas flowing through the inlet path by heat exchange with the nitrogen gas flowing through the exhaust path.

3. A nitrogen gas purification apparatus as described in claim 2, further comprising a thermostatic chamber having a thermostatic chamber surrounded by a vacuum insulation section, the adsorption section and the heat exchanger being provided within the thermostatic chamber, and the auxiliary heat exchanger being provided within the vacuum insulation section.

4. A nitrogen gas purification device as described in claim 3, further comprising a control unit that adjusts the flow rate and temperature of the liquefied nitrogen introduced into the heat exchanger so that the temperature of a specified portion of the temperature-controlled chamber is not lower than -160°C and not higher than -100°C.

5. A nitrogen gas purification system comprising: a nitrogen gas purification apparatus (A) as defined in claim 1; a nitrogen gas purification apparatus (B) as defined in claim 1; a common inlet path which branches into an inlet path (A) of the nitrogen gas purification apparatus (A) and an inlet path (B) of the nitrogen gas purification apparatus (B); and a common exhaust path where an exhaust path (A) of the nitrogen gas purification apparatus (A) and an exhaust path (B) of the nitrogen gas purification apparatus (B) join together, wherein the nitrogen gas introduced from the common inlet path and exhausted to the common exhaust path is purified by alternately using the nitrogen gas purification apparatus (A) and the nitrogen gas purification apparatus (B).

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