JPS6244190B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a high-purity nitrogen gas production apparatus that can stably supply extremely high-purity nitrogen gas at low cost.

[Background technology]

Extremely large amounts of nitrogen gas are used in the electronics industry, but strict requirements have been placed on the purity of nitrogen gas from the perspective of maintaining and improving component precision.

Conventionally, nitrogen gas is produced using air as a raw material. After compressing it with a compressor, it is put into an adsorption cylinder to remove carbon dioxide and moisture, and then cooled by exchanging heat with a refrigerant through a heat exchanger, and then rectified. It is produced by a cryogenic liquefaction method in which product nitrogen gas is produced by cryogenic liquefaction separation in a tower, and then heated to near room temperature through the heat exchanger. however,
Since the product nitrogen gas produced in this way contains oxygen as an impurity, it is often inconvenient to use it as it is in the electronic industry. Impure oxygen can be removed by adding a small amount of hydrogen into nitrogen gas using a Pt catalyst and reacting with the impure oxygen in an atmosphere at a temperature of about 200°C to remove it as water, or by using a Ni catalyst. There is a method of removing impure oxygen in nitrogen gas by bringing it into contact with a Ni catalyst in an atmosphere at a temperature of about 200°C to cause a reaction of Ni+1/2O ₂ →NiO. However, in all of these methods, the nitrogen gas must be heated to a high temperature and brought into contact with the catalyst, so the apparatus cannot be incorporated into a nitrogen gas production apparatus that is an ultra-low temperature system. Therefore, it is necessary to install a purification device separately from the nitrogen gas production device, which has the drawback of increasing the overall size. Furthermore, the above method requires high precision in adjusting the amount of hydrogen added, and if the amount of hydrogen that is not added is just enough to react with the amount of impure oxygen, oxygen may remain or the added hydrogen may remain. and become impurities,
There is a problem in that it requires skill to operate. In addition, in the above method, NiO produced by reaction with impure oxygen
It became necessary to regenerate (NiO + H ₂ → Ni + H ₂ O), and H ₂ gas equipment for regeneration was required, leading to an increase in refining costs. Therefore, these improvements have been strongly desired.

In addition, the conventional cryogenic liquefaction method uses an expansion turbine to cool the refrigerant in the heat exchanger that cools the compressed air compressed by the compressor. Through cold liquefaction separation, low-boiling point nitrogen is extracted as a gas, and the remainder becomes oxygen-rich liquid air and accumulates.It is driven by the pressure of the evaporated gas. However, since the expansion turbine has an extremely high rotational speed (tens of thousands of rotations/minute), it is difficult to operate the expansion turbine in a manner that closely follows load fluctuations (changes in the amount of product nitrogen gas taken out).
Therefore, it is difficult to accurately change the amount of evaporated liquid air supplied to the expansion turbine in response to changes in the amount of product nitrogen gas taken out, and to constantly cool the compressed air to a constant temperature. As a result, the purity of the product nitrogen gas obtained varies, and a problem arises in that nitrogen gas with low purity is frequently produced. Furthermore, since this device rotates at high speed, it requires high precision in its mechanical structure, is expensive, and has the disadvantage that specially trained personnel are required because the machine is complex.
That is, since the expansion turbine has a high-speed rotating section, the above-mentioned problems arise, and there has been a strong desire to eliminate the expansion turbine having such a high-speed rotating section.

[Purpose of the invention]

An object of the present invention is to provide an apparatus that can produce high-purity nitrogen gas without using an expansion turbine or purification equipment.

[Disclosure of the invention]

In order to achieve the above object, the high purity nitrogen gas production apparatus of the present invention includes an air compression means for compressing air taken in from the outside, and carbon dioxide and moisture in the compressed air compressed by the air compression means. a heat exchange means for cooling the compressed air that has passed through the removal means to an ultra-low temperature, and a part of the compressed air cooled to an ultra-low temperature by the heat exchange means to be liquefied and stored at the bottom to produce only nitrogen. In a nitrogen gas production device equipped with a rectification column that extracts gas from the upper side, there is a partial condenser with a built-in condenser installed at the top of the rectification column, and liquid air stored at the bottom of the rectification column is transferred to the condenser. A liquid air introduction pipe that leads into the dephlegmator as cold air for cooling, a discharge pipe that discharges the vaporized liquid air generated in the dephlegmator to the outside, and a portion of the nitrogen gas generated in the rectification column. a first reflux liquid pipe that guides the liquefied nitrogen into the condenser, and a second reflux pipe that returns the liquefied nitrogen produced in the condenser to the rectification column as a reflux liquid.
a reflux liquid pipe, a low-temperature liquefied gas storage means for supplying and storing a low-temperature liquefied gas other than liquefied nitrogen gas from outside the apparatus, a second condenser provided at an upper part inside the rectification column, a first introduction path that continuously introduces the low-temperature liquefied gas in the liquefied gas storage means into the second condenser as cold for compressed air liquefaction instead of the cold heat generated from the cold heat generation expander; a second introduction path that continuously guides the low-temperature liquefied gas in the gas storage means as a cold source to the heat exchange means, exchanges heat with the compressed air passing through it, raises the temperature, and leads it out of the apparatus; control means for controlling the liquid level of liquid air in the condenser to a constant level by controlling the supply amount of low-temperature liquefied gas from the low-temperature liquefied gas storage means to the condenser; The liquid nitrogen that has finished its cooling action and has been vaporized is introduced into the heat exchange means, where it is heated by exchanging heat with the compressed air passing through it, raised in temperature, and then discharged outside the apparatus, and the liquid nitrogen is taken out as a gas from the rectification column. The apparatus is configured to include a nitrogen gas extraction passage for increasing the temperature of nitrogen by exchanging heat with the compressed air passing through the heat exchange means and converting it into a product nitrogen gas.

Next, the present invention will be explained in detail based on examples.

FIG. 1 shows an embodiment of the invention. In the figure, 9 is an air compressor, 10 is a drain separator, 11 is a fluorocarbon cooler, and 12 is a set of two adsorption cylinders. The adsorption cylinder 12 is filled with molecular sieve inside and functions to adsorb and remove H ₂ O and CO ₂ in the air compressed by the air compressor 9. 13 is a first heat exchanger, into which compressed air from which H ₂ O and CO ₂ have been adsorbed and removed by the adsorption column 12 is sent. 14 is a second heat exchanger, into which the compressed air that has passed through the first heat exchanger 13 is sent. 15 is a rectification column equipped with a demultiplexer 21 having a built-in first condenser 21a at the top of the column;
The compressed air cooled to an extremely low temperature is further cooled by the heat exchangers 13 and 14, a part of which is liquefied and stored at the bottom, and only nitrogen in a gaseous state is taken out from the top. That is, the ultra-low temperature (approximately -170
Compressed air, which has been cooled to a temperature of 0.degree. 23 is a liquid oxygen storage tank that receives liquid oxygen from outside the device and stores it;
is passed through the first introduction pipe 24a to the rectification column 15.
The compressed air is sent to the second condenser 22a in the rectifier 15 to cool the compressed air supplied to the rectifier 15, and is then passed through the second inlet pipe 24b to the second and first heat exchangers 14, 13, heat exchanger 14,
It is designed to exchange heat with the compressed air sent into 13 and cool it to an ultra-low temperature. In this case, the liquid oxygen itself is transferred to the condenser 22a or the heat exchanger 1.
4 and 13, it is vaporized and becomes a room temperature gas, and the first and second outlet pipes 24'a, 2
It is released outside the system via 4'b. The vaporized liquid oxygen released outside the system is used as an oxygen source for other systems. To explain the rectification column 15 in more detail, the second condenser 22a is disposed inside the rectification column 15 as described above, and the second condenser 22a is connected to the liquid oxygen storage tank 23 through the introduction pipe 24a. The liquid oxygen sent in is used as a cold source, and the compressed air taken in from the bottom of the rectification column 15 and rising inside the rectification column 15 is cooled to liquefy high boiling point components such as oxygen and cooled to the bottom of the rectification column 15. Nitrogen gas with a low boiling point is stored in the upper part of the rectification column 15. 24'a
is the outlet pipe described above, which allows the vaporized liquid nitrogen that has finished its cooling action and been vaporized in the second condenser 22a to be distilled through the second and first heat exchangers 14 and 13. After exchanging heat and raising the temperature to room temperature or near room temperature, it is led out of the device. The demultiplexer 21 containing the first condenser 21 a is provided above the ceiling plate 20 and is in a lower pressure state than the inside of the rectification column 15 . The liquid air (N ₂ 50-70%, O ₂ 30-50%) stored at the bottom of the rectification column 15 is fed into the dephlegmator 21 through a pipe 19 with an expansion valve 19a, and is vaporized to reduce the internal temperature. is cooled to a temperature below the boiling point of liquid nitrogen. Nitrogen gas accumulated in the upper part of the rectification column 15 is sent to the condenser 21a in the demultiplexer 21 via the first reflux liquid pipe 21b, is cooled and liquefied, and is transferred to the second reflux liquid pipe 2.
1c and flows down into the liquid nitrogen reservoir 21d of the rectification column 15. This flowing down nitrogen contacts the compressed air rising from the bottom of the rectification column 15 in a countercurrent manner, and together with the cooling effect of the second condenser 22a, high boiling point components in the compressed air are liquefied and dropped. Reference numeral 25 denotes a liquid level gauge, which controls a valve 26 according to the liquid level of the liquid air in the decentralizer 21 to maintain a constant level, thereby controlling the amount of liquid oxygen supplied from the liquid oxygen storage tank 7. . Reference numeral 27 denotes an extraction pipe for taking out the nitrogen gas accumulated in the upper part of the rectification column 15 as a product nitrogen gas, and the extremely low temperature nitrogen gas is transferred to the second and first heat exchangers 1
4, 13, heat exchanges with the compressed air sent there to bring the temperature to room temperature, and sends it into the main pipe 28. In this case, He (-269
℃), H ₂ (-253℃) accumulates, so the extraction pipe 2
7 opens below the top of the rectification column 15, and is designed to take out only pure nitrogen gas that does not contain He or _H2 . 29 transfers the vaporized liquid air in the dephlegmator 21 to the second and first heat exchangers 14 and 1.
3, and 29a is its pressure holding valve. The vaporized liquid air that has undergone heat exchange (cooling of compressed air) in the second and first heat exchangers 14 and 13 is discharged from the first heat exchanger 13 as shown by arrow A. In addition, 30 is a backup system line, and when the air compression system line breaks down, liquid nitrogen in the liquid nitrogen storage tank 23 is transferred to the evaporator 3.
1 to evaporate it and send it to the main pipe 28, so that the supply of nitrogen gas does not stop. 32 is an impurity analyzer that analyzes the purity of the product nitrogen gas sent to the main pipe 28, and when the purity is low, operates valves 34, 34a to release the product nitrogen gas to the outside as shown by arrow B. have the effect of

This device produces product nitrogen gas in the following manner. That is, air is compressed by an air compressor 9, moisture in the compressed air is removed by a drain separator 10, and cooled by a fluorocarbon cooler 11. In this state, the air is sent to an adsorption cylinder 12 to remove moisture from the compressed air.
Adsorbs and removes H ₂ O and CO ₂ . Then, _H2O ,
The compressed air from which CO ₂ has been adsorbed and removed is sent to the first heat exchanger 13 and the second heat exchanger 14 to be cooled to an ultra-low temperature, and in this state is introduced into the lower part of the rectification column 15 . Then, the input compressed air is transferred to the overflow liquid nitrogen from the liquid nitrogen reservoir 21d and the second condenser 2.
2a, the boiling point difference between nitrogen and oxygen (boiling point of oxygen -183℃, boiling point of nitrogen -196℃) is used to liquefy oxygen, which is a high boiling point component in compressed air, and convert it into nitrogen. The nitrogen gas is taken out from the extraction pipe 27 as a gas, fed into the heat exchangers 13 and 14, heated to near room temperature, and sent out from the main pipe 28 as a product nitrogen gas. In this case, the liquid oxygen in the liquid oxygen storage tank 23 acts as a cooling source for the second condenser 22a and the first and second heat exchangers 13 and 14,
itself is vaporized and the outlet pipes 24'a, 2
From 4'b, it is released into the atmosphere or sent to other equipment such as semiconductor manufacturing equipment and used as raw material oxygen.

As mentioned above, this nitrogen gas production device can produce high-purity product nitrogen gas without using an expansion turbine, and does not have any of the above-mentioned disadvantages caused by expansion turbines, and can eliminate the need for a purification device. . In particular, this high-purity nitrogen gas production apparatus is provided with a demultiplexer 21 having a built-in first condenser 21a in the upper part of the rectification column 15, and nitrogen in the rectification column 15 is supplied into the first condenser 21a. In order to constantly guide and liquefy a part of the gas, after a predetermined amount of liquefied nitrogen has accumulated in the first condenser 21a, the liquefied nitrogen generated from then on is always returned to the rectification column 15 as a reflux liquid. become.
Therefore, variations in product purity due to intermittent supply of the reflux liquid from the first condenser 21a (interruption of the flow of the reflux liquid causes the liquid to run out in the upper rectifying shelf, causing a gas blow-by phenomenon, resulting in product purity Product nitrogen gas of stable purity can be supplied at all times without causing the purity to drop and return to a constant purity when the flow resumes. However, in this device, even if the demand for product nitrogen gas fluctuates, the control means such as the liquid level gauge 25 controls the opening degree of the valve 26, etc., and controls the amount of liquid oxygen supplied to the second condenser 22a. By doing so, the liquid level of the liquid air in the dephlegmator 21 is controlled to be constant, so that fluctuations in demand can be quickly responded to, and also at this time, variations in purity do not occur for the reasons described above. That is, when the demand for product nitrogen gas increases, most of the produced nitrogen gas is taken out from the take-out pipe 27, and the first condenser 21a
As the amount of nitrogen gas sent to the first condenser 21a decreases, the amount of reflux liquid generated in the first condenser 21a decreases,
As a result, the amount of liquid air 18 stored at the bottom of the rectification column decreases, and the amount of liquid air sent therefrom decreases, so the level of liquid air in the dephlegmator 21 decreases. This causes the liquid level gauge 25 to operate, increasing the amount of liquid oxygen supplied to the second condenser 22a and increasing the amount of reflux liquid (liquefied nitrogen), which is then fed into the rectification column 15. The amount of liquefied feed air is increased to increase the amount of liquid air stored at the bottom of the rectification column. Then, when the amount of stored liquid air increases and the liquid level in the dephlegmator 21 recovers, the liquid level gauge 25 operates again and the amount of liquid oxygen supplied to the rectification column 15 is controlled to decrease appropriately. When the demand for product nitrogen gas decreases, contrary to the above, the liquid level in the dephlegmator 21 rises, so the liquid level gauge 25 operates to reduce the amount of liquid oxygen supplied to the rectification column 15. Eliminate the absurdity based on oversupply of liquid oxygen.
In this way, this device can quickly and rationally respond to changes in demand without causing variations in purity. Moreover, the liquid oxygen in the liquid oxygen storage tank 23 is supplied to the second condenser 22a, acts as a cold source, and then is vaporized and used for other purposes, so it is possible to achieve effective use of cold energy, and the product gas It is possible to reduce costs. In particular, this device can supply liquid oxygen from the liquid oxygen storage tank 23 to both the second condenser 22a and the heat exchangers 13 and 14, and when the device is operated, valves etc. are operated to supply liquid oxygen from the liquid oxygen storage tank. By supplying liquid oxygen to the maximum capacity to both of the above, it becomes possible to significantly shorten the start-up time.

FIG. 2 shows another embodiment. That is,
In this embodiment, an oxygen adsorption cylinder 40 with a built-in adsorbent that selectively adsorbs oxygen and carbon monoxide at extremely low temperatures is installed in the take-out pipe 27 for taking out the product nitrogen gas.
and a first and second heat exchanger 1
3 and 14 as well as the rectification column 15 are housed in a vacuum insulated box shown by a dashed line and are vacuum insulated. Since the other parts are substantially the same as the apparatus shown in FIG. 1, the corresponding parts are given the same reference numerals and the explanation thereof will be omitted.

As the adsorbent, for example, synthetic zeolite 3A, 4A having a pore diameter of 3 Å, 4 Å or 5 Å is used.
Or 5A (Molecular Sieve 3A, 4A,
5A, manufactured by Union Carbide Co.) is used.
As shown in FIG. 3, these synthetic zeolites 3A, 4A, and 5A each have excellent selective adsorption properties for oxygen and carbon monoxide at extremely low temperatures. Therefore, the impurities in the nitrogen gas discharged from the upper space of the rectification column section 15 are removed. Moreover, since this apparatus has vacuum insulation for the rectification column 15, the effect of improving rectification accuracy can be obtained. Therefore, due to the synergistic effect of this effect and the adsorption effect of the adsorbent, the purity of the product nitrogen gas is further improved.

FIG. 3 shows an embodiment in which an oxygen rectification column is added to the apparatus shown in FIG. In the figure, reference numeral 40 denotes an oxygen rectification column, which communicates with the bottom of the partial condenser 21 of the nitrogen rectification column 15 through a liquid air supply pipe 41, and the liquid air sent into the partial condenser 21 is The nitrogen content is taken in by using the difference in the head, and the nitrogen content is vaporized and removed due to the difference in boiling point, and the oxygen is stored in a liquid state at the bottom. Reference numeral 42 denotes a discharge pipe that sends waste liquid nitrogen in a vaporized state into the pipe 29, mixes it with vaporized liquid air, and discharges it. Reference numeral 43 denotes a take-out pipe for taking out the liquid oxygen accumulated at the bottom of the oxygen rectification column 40, which passes through the second heat exchanger 14, where it exchanges heat with compressed air sent in from the branch pipe 9' and converts it into a heated gas. Product nitrogen gas extraction pipe 4
It is designed to be sent within 4 days. 45 is a compressed air transfer pipe extending from the second heat exchanger 14 to the pipe 17, the middle part of which is the oxygen rectification column 4.
The liquid oxygen stored at the bottom of the column 40 is heated to vaporize a part of it, and brought into countercurrent contact with the liquid air flowing down from the pipe 41 into the column 40 to improve the rectification efficiency. It's summery. The other parts are the same as the apparatus shown in FIG.

This device supplies oxygen-rich liquid air 18 after nitrogen gas collection to an oxygen rectification column 40 via the partial condenser section 21 of the nitrogen rectification column 15, and vaporizes and removes residual nitrogen in the liquid air 18. Since liquid oxygen is produced in the heat exchanger 14 and then vaporized in the heat exchanger 14 to produce product oxygen gas, highly purified product oxygen gas can be obtained efficiently. That is, this device can efficiently obtain not only high-purity nitrogen gas but also high-purity oxygen gas.

In the apparatus shown in FIG. 3, the oxygen rectification column 40 and the partial condenser 21 of the nitrogen rectification column 15 are connected to each other by connecting the discharge pipe 42 to the pipe 29. As shown, the discharge pipe 42 may be independent without being connected to the pipe 29. By doing so, the oxygen rectification column 40 and the nitrogen rectification column 15 become independent from each other, so that oxygen gas can be produced almost unaffected by the amount of nitrogen gas produced by the nitrogen rectification column 15. You will be able to increase or decrease the amount.

FIG. 5 shows a plurality of nitrogen adsorption cylinders 4 installed at the open end of the pipe 29 for discharging vaporized liquid air in the apparatus shown in FIG.
0' to 42' are provided to obtain oxygen gas from vaporized liquid air. In the figure, 40',
41' and 42' are adsorption cylinders each filled with an adsorbent (synthetic zeolite: molecular sieve) that selectively adsorbs _N2 , and the inlet thereof is equipped with valves 40b, 41b, and 42b, respectively. It is connected to the discharge pipe 29 through inflow channels 40a, 41a, and 42a. 44' is a vacuum pump, which has a suction path 43' and valves 40c, 41c, 42.
It is connected to the inlets of the adsorption cylinders 40', 41', and 42' via c. 40d, 41d, 42d
are take-out passages connected to the outlets of the adsorption cylinders 40', 41', and 42', respectively;
e, 41e, and 42e. These outlet passages 40d, 41d, and 42d are connected to a buffer tank 46' via a product nitrogen gas outlet line 45'. One of the adsorption cylinders 40', 41', and 42' is used for adsorption, while the remaining one is subjected to the regeneration action by vacuum suction of the vacuum pump 44', and then one of the regenerated cylinders is used for adsorption. What was previously used for adsorption is now regenerated. This process is repeated for continuous suction operation. In addition, 25 is a liquid level gauge, and 26 is a valve controlled by it. The other parts are substantially the same as the first device.

This device supplies oxygen-rich liquid air 18 after nitrogen gas collection to the demultiplexer 21 of the nitrogen rectification column 15, cools the condenser 21a, and then vaporizes the oxygen-rich liquid air directly into the atmosphere. Instead of being released, the residual nitrogen is adsorbed and removed by being placed in the adsorption cylinders 40', 41', and 42' to produce product oxygen gas, so that highly pure product oxygen gas can be efficiently obtained. That is, this device can also efficiently obtain not only high-purity nitrogen gas but also high-purity oxygen gas.

In the above embodiment, the liquid oxygen in the liquid oxygen storage tank 23 is used to clean the condenser 22a in the rectification column 15.
Although the heat exchangers 13 and 14 are cooled, liquid argon or liquid helium may be used instead of liquid oxygen. Alternatively, liquid hydrogen may be used. Furthermore, the same effects as in the above embodiments can be obtained by using liquefied petroleum gas such as liquefied propane, liquefied methane, liquefied ethane, and liquefied butane.

〔Effect of the invention〕

As described above, the high-purity nitrogen gas production apparatus of the present invention utilizes the cold heat generated during evaporation of liquid argon, liquid helium, liquid hydrogen, liquid oxygen, or chlorinated petroleum gas to create a condenser built into a rectification column and a heat exchanger. part of the compressed raw air (mainly acid components)
Liquid argon,
It is possible to realize the effective use of cold energy such as liquid helium, and reduce the cost of product nitrogen gas.
In addition, according to the device of the present invention, an expansion turbine is not used, and liquid oxygen, etc., which is in liquid form and whose supply amount can be finely adjusted, is used as a cooling source for compressed air. ), it becomes possible to closely follow the flow rate, and it becomes possible to produce nitrogen gas with stable and high purity.
That is, according to the apparatus of this invention, high purity nitrogen gas with an impure oxygen content of 0.1 ppm or less can be obtained, whereas with the conventional cryogenic liquefaction method, the impure oxygen content is low.
Only 2 ppm is obtained. Therefore, the apparatus of the present invention eliminates the need for conventional purification equipment. Additionally, the device of the present invention does not require expensive expansion turbines that are difficult to maintain, thus eliminating the need for security personnel and reducing costs. In particular, the apparatus of this invention is provided with a fractionator with a built-in condenser in the upper part of the rectification column, and a part of the nitrogen gas in the rectification column is constantly introduced into this condenser to liquefy and reflux the reflux liquid. At the same time, the control means controls the amount of low-temperature liquefied gas supplied from the low-temperature liquefied gas storage means to the second condenser to maintain a constant liquid level in the fractionator. Because of this control, it is possible to respond extremely quickly to load fluctuations, and in this case, there is no variation in the purity of the product nitrogen gas. Furthermore, since a second condenser is provided inside the rectification column and low-temperature liquefied gas is supplied thereto from a low-temperature liquefied gas storage tank, the pressure of the low-temperature liquefied gas can be lowered and the amount used can be reduced.
Moreover, since this device supplies low-temperature liquefied gas to both the second condenser and the heat exchanger for cooling, it is possible to significantly shorten the start-up time when the device is running, which is extremely useful in actual operation. Useful.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a block diagram of another embodiment, FIG. 3 is a block diagram of yet another cooling system, and FIG. 4 is an explanatory diagram of a modification thereof. Fifth
The figure is a configuration diagram of another embodiment. 9...Air compressor, 12...Adsorption cylinder, 13,1
4... Heat exchanger, 15... Rectification column, 17... Pipe, 18... Liquid air, 21... Decentralizer, 21a
...First condenser, 21b...First reflux pipe, 21c...Second reflux pipe, 21d...
Liquid nitrogen reservoir, 22a...Second condenser, 23...
...Liquid oxygen storage tank, 24a...First inlet pipe, 24b...Second inlet pipe, 27...Takeout pipe, 28...Main pipe.

Claims (1)

[Claims] 1. Air compression means for compressing air taken in from the outside, removal means for removing carbon dioxide and moisture from the compressed air compressed by this air compression means, and cooling the compressed air that has passed through this removal means to an ultra-low temperature. In a nitrogen gas production device equipped with a cooling heat exchange means and a rectification column that liquefies a part of the compressed air cooled to an ultra-low temperature by the heat exchange means and stores it at the bottom and extracts only nitrogen as a gas from the upper side, a condenser with a built-in condenser installed in the upper part of the rectification column; a liquid air introduction pipe that guides the liquid air stored at the bottom of the rectification column into the condenser as cold air for cooling the condenser; a discharge pipe for discharging the vaporized liquid air produced in the fractionator to the outside; a first reflux pipe for guiding a portion of the nitrogen gas produced in the rectification column into the condenser; a second reflux liquid pipe that returns liquefied nitrogen generated in the vessel as a reflux liquid into the rectification column; a low-temperature liquefied gas storage means for supplying and storing a low-temperature liquefied gas other than liquefied nitrogen gas from outside the apparatus; A second condenser installed in the upper part of the rectification column and the low-temperature liquefied gas in the low-temperature liquefied gas storage means are continuously used as cold for compressed air liquefaction in place of cold heat generated from the cold heat generation expander. a first introduction path leading into the second condenser; and a first introduction path that continuously leads the low temperature liquefied gas in the low temperature liquefied gas storage means to the heat exchange means as a cold source and exchanges heat with the compressed air passing through the inside thereof. By controlling the supply amount of low-temperature liquefied gas from the low-temperature liquefied gas storage means to the second condenser and the second condenser, the liquid in the dephlegmator is a control means for controlling the liquid level of the air to a constant level; and a control means for controlling the liquid level of the air to a constant level, and introducing the liquid nitrogen that has finished its cooling action and vaporized in the second condenser to the heat exchange means and exchanges heat with the compressed air passing through the heat exchange means to raise the temperature. Nitrogen, which is taken out as a gas from the rectification column, passes through the heat exchange means and exchanges heat with the compressed air passing through the heat exchange means, thereby raising the temperature of the nitrogen to produce a product nitrogen gas. A high-purity nitrogen gas production device characterized by being equipped with a gas extraction path.