JPS6115070A - Production unit for high-purity nitrogen gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a high purity nitrogen gas production apparatus.

[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. In other words, nitrogen gas is
Generally, air is used as a raw material, and after compressing it with a compressor, it is put into an adsorption column to remove carbon dioxide and moisture, and then cooled by exchanging heat with a refrigerant through a heat exchanger, and then deeply cooled in a rectification column. It is manufactured through a process of liquefying and separating product nitrogen gas, and raising the temperature of this gas to near room temperature through the aforementioned 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. Methods for removing impure oxygen include: ■P [method in which a small amount of hydrogen is added to nitrogen gas using a catalyst and reacted with impure oxygen in an atmosphere at a temperature of about 200°C to remove it as water; and ■Using a Ni catalyst. However, 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 N i + 1/202-N i O. 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, the purification device must be installed separately from the nitrogen gas production device, and there is a drawback that the entire device becomes a doll. Furthermore, the 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. There is a problem in that it requires skill to operate, as it becomes impurities. In addition, in the method (2) above, the regeneration of NiO produced by the reaction with impure oxygen (NiO + H2 → N
i+H20), and regeneration H2 gas equipment was required, leading to an increase in refining costs. therefore,
These improvements were strongly desired.

In addition, conventional nitrogen gas production equipment uses a refrigerant for cooling the heat exchanger to cool the compressed air compressed by the compressor.
An expansion turbine is used to convert the liquid air (
The low-boiling point nitrogen is extracted as a gas through cryogenic liquefaction separation, and the remainder becomes oxygen-rich liquid air (which accumulates) and is driven by the pressure of the gas that explodes. However, expansion turbines have extremely high rotational speeds (tens of thousands of revolutions per minute).
Therefore, it is difficult to follow load fluctuations, and specially trained operators are required. Furthermore, since this device rotates at a high speed, it requires high precision in its mechanical structure, is expensive, and has the disadvantage of requiring specially trained personnel due to its complicated mechanism.

That is, since the expansion turbine has a high-speed rotating section, it causes the various problems described above, and there has been a strong desire to eliminate the expansion turbine having such a high-speed rotating section.

In order to meet such demands, the inventor has developed a nitrogen gas production device that removes the expansion turbine and instead supplies cold liquid nitrogen from the outside into a heat exchange means such as a heat exchanger. Already patent ratio 1m (patent application 1984-4)
760). Since this device can produce nitrogen gas of extremely high purity, conventional purification equipment is completely unnecessary. Also, since the expansion turbine has been removed,
There are no harmful effects caused by this. Therefore, it is most suitable for the electronic industry. However, in the electronics industry, oxygen gas is also used in addition to nitrogen gas, and it has been desired to provide a device that can produce not only nitrogen gas but also oxygen gas with one device.

[Purpose of the invention]

An object of the present invention is to provide a high-purity nitrogen gas production apparatus that can produce high-purity nitrogen gas without using an expansion turbine or a purification device, and can also produce oxygen gas at the same time.

[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 water in the compressed air compressed by the air compression means. a removing means for removing; a heat exchange means for cooling the compressed air that has passed through the removing means to an ultra-low temperature;
a liquid nitrogen storage means for storing liquid nitrogen; an introduction path leading the liquid nitrogen in the liquid nitrogen storage means to the heat exchange means so as to serve as a cold source for the heat exchange means; A nitrogen rectification column that liquefies a portion of the compressed air and stores it inside to retain only nitrogen as a gas, and liquid nitrogen that has been vaporized after the heat exchange means has finished functioning as a cold source and the inside of the nitrogen rectification column. A nitrogen gas take-out path takes out both of the vaporized nitrogen held in the nitrogen rectification column as product nitrogen gas from the nitrogen rectification column, and a fluid such as compressed air liquefied product or its vaporized product stored in the nitrogen rectification column is connected to the outside. an adsorption cylinder containing a built-in adsorbent that selectively adsorbs nitrogen is connected to the discharge path, and an extraction path for taking out the fluid after nitrogen removal is connected to the adsorption cylinder. It is something to take.

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

FIG. 1 shows an embodiment I of the present 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. Adsorption tube 12
The inside is filled with a molecular sieve, which functions to adsorb and remove H80 and CO2 in the air compressed by the air compressor 9. Reference numeral 13 denotes a heat exchanger, into which compressed air from which H, O, and COI have been adsorbed and removed by the adsorption column 12 is sent through the compressed air supply pipe 8 .

24a is a pipe extending from the liquid nitrogen storage tank 23. This liquid nitrogen storage tank 23 is connected to a pipe 24a for discharging the liquid nitrogen inside.
The liquid nitrogen is sent to the heat exchanger 13 through the heat exchanger 13, where it exchanges heat with the compressed air sent into the heat exchanger 13, cooling the compressed air to an ultra-low temperature, and vaporizing the liquid nitrogen.

The liquid nitrogen vaporized by the heat exchanger 13 is transferred to the pipe 2
4b and into the main pipe 28 for delivering the product nitrogen gas. Reference numeral 15 denotes a nitrogen rectification column whose top part is a dephlegmator part 21 having a condenser 21a, and the part below it is a column part 22.
3, the compressed air cooled to an ultra-low temperature and sent through the pipe 17 is further cooled, a part of which is liquefied and stored at the bottom of the tower section 22 as liquid air 18, and only nitrogen is in a gaseous state at the upper ceiling of the tower section 22. It is designed to be stored in 2
0 is a partition plate that partitions the dephlegmator section 21 and the tower section 22.

To explain in more detail, the condenser 21 in the demultiplexer section 21
A part of the nitrogen gas accumulated in the upper part of the column section 22 is fed into the column a through the pipe 21b. The pressure inside this dephlegmator section 21 is lower than that inside the column section 22, and the liquid air (N) is stored at the bottom of the column section 22.

50-70%, 0.30-50%) 18 is the expansion valve 19a
The liquid nitrogen is fed through a pipe 19, and is vaporized to cool the internal temperature to a temperature below the boiling point of liquid nitrogen. Due to this cooling, the nitrogen gas fed into the condenser 21a is liquefied. The liquid nitrogen produced in the condenser 21a of the demultiplexer section 21 is supplied to the upper part of the column section 22 of the rectification column 15 through a pipe 21c, and is supplied to the column section 22 through the liquid nitrogen reservoir 21d. The air flows downward through the tower section 22, contacts countercurrently with the compressed air rising from the bottom of the tower section 22, cools it, and partially liquefies it. In this process, the high boiling point components in the compressed air are liquefied and accumulate at the bottom of the column section 22, and the low boiling point components, nitrogen gas, accumulate at the top of the column section 22. Reference numeral 27 is a take-out pipe for taking out the nitrogen gas accumulated in the upper ceiling of the rectification column section 22, which guides the ultra-low temperature nitrogen gas into the heat exchanger 13 and exchanges heat with the compressed air sent there to bring it to room temperature. It acts to feed the water into the main pipe 28.

In this case, at the top of the rectification column section 22, along with nitrogen gas, He (-269°C), which has a low boiling point, H,
(-253°C) tends to accumulate, so the extraction pipe 27 is
It opens considerably below the top of the tower section 22 and is heated to
Only pure nitrogen gas without any mixture of e, H, etc. is taken out as product nitrogen gas. Reference numeral 29 is a discharge path pipe that sends the waste vaporized liquid air in the dephlegmator section 21 to the heat exchanger 13, and 29a is its pressure holding valve. 40.41°42 is an adsorbent that selectively adsorbs N2 (
It is an adsorption cylinder filled with synthetic zeolite (molecular sieve), and its inlets are connected to valves 40b, 41b,
It is connected to the discharge pipe 29 through inflow passages 40a, 41a, and 42a provided with 42b. A vacuum pump 44 is connected to the inlets of the adsorption cylinders 40, 41, and 42 via a suction path 43 and valves 40c, 41c, and 42C. 40d, 41d, and 42d are take-out passages connected to the outlets of the adsorption cylinders 40, 41, and 42, respectively, and are provided with valves 40e, 41e, and 42e, respectively. These take-out paths 40d, 41d, and 42d are connected to a buffer tank 46 via a product oxygen gas take-out path 45. One of the adsorption cylinders 40, 41, 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 acting as an adsorbent undergoes a regeneration action. This process is repeated for continuous suction operation. In addition, 30 is a backup line,
When the air compression line breaks down, the liquid nitrogen in the liquid nitrogen storage tank 23 is evaporated by the generator 31 and the main pipe 2
8 to ensure that the supply of nitrogen gas does not stop. 32 is an impurity analyzer, and main pipe 2
The purity of the product nitrogen gas sent to step 8 is analyzed, and if the purity is low, the valves 34 and 34a are operated to release the product nitrogen gas to the outside as shown by arrow B. Moreover, one point &] 11jl is a vacuum cold storage box, which accommodates a rectification column 15 and the like to improve purification efficiency.

This device produces product nitrogen gas and oxygen gas as follows. That is, air is compressed by the air compressor 9, water in the compressed air is removed by the drain separator 10, and cooled by the fluorocarbon cooler 11. In this state, the air is sent to the adsorption column 12 to remove H2O and CO2
is removed by adsorption. Next, the compressed air from which +(, O, and CO2 have been adsorbed and removed) is sent to the heat exchanger 13 and cooled to an ultra-low temperature by the cold heat of the liquid nitrogen supplied from the liquid nitrogen storage tank 23. Then, this input compressed air is supplied from the condenser 21a to the liquid nitrogen reservoir 21d, and is cooled by contacting with the liquid nitrogen overflowing therefrom. The difference between the boiling points of nitrogen and oxygen (
The boiling point of oxygen is -183°C and the boiling point of nitrogen is -196°C), so oxygen, which is a high boiling point component in compressed air, liquefies, and nitrogen remains as a gas. Next, the remaining gaseous nitrogen is taken out from the extraction pipe 27 and sent to the heat exchanger 134, where it is heated to near normal temperature and sent out from the main pipe 28 as a product nitrogen gas. In this case, the liquid nitrogen from the liquid nitrogen storage tank 23 acts as a cooling source for the heat exchanger 13,
The nitrogen gas itself is vaporized and taken out from the take-out pipe 27 as part of the product nitrogen gas. On the other hand, the liquid air 18 accumulated at the lower part of the rectification column section 22 is sent into the dephlegmator section 21 to cool the condensate 121a, and then vaporized to become waste vaporized liquid air, which is then passed through the pipe 29 to the heat exchanger. 13, the temperature rises, and in that state it is sent to any of the adsorption cylinders 40, 41, and 42, where the nitrogen gas is adsorbed and removed, and it becomes oxygen gas and is sent to the buffer tank 46. .

In this case, any one of the adsorption cylinders 40, 41, 42 is activated for adsorption, and the remaining ones are subjected to the vacuum regeneration action of the vacuum pump 44 during that time, and then the adsorption cylinder that is activated for adsorption starts regeneration, and the regenerated adsorption cylinder is Each of the valves 40b to 42b, 40c to 42c, and 40e enters the suction operation.
~42e are controlled. In this way, high purity nitrogen gas and oxygen gas can be obtained simultaneously using one device. In this case, the ratio (volume ratio) of the product nitrogen gas to the product oxygen gas obtained is about 10:1.

Note that a rectification column having a structure as shown in FIG. 2 may be used instead of the nitrogen rectification column shown in FIG. 1. That is, this rectification column 1
5, a dephlegmator part 21 is separated from a tower part 22 by a partition plate 20 in which a large number of pipes 20a are installed, and liquid nitrogen is supplied from a liquid nitrogen storage tank 23 into the dephlegmator part 21. The compressed air supplied from the pipe 19 into the column section 22 is cooled in the pipe 20a of the partition plate 20 to liquefy the oxygen content, and the nitrogen is taken out in a gaseous state from the top of the dephlegmator section 21. It has become. In this case, unlike the previous embodiment, the liquid air 1 accumulated at the bottom of the column section 22 of the rectification column 15
8 is used as a raw material for oxygen gas, and in the heated and vaporized state in the heat exchanger 13, any adsorption M40.41.42
supplied to

Furthermore, as shown in FIG. 3, a temperature sensor 50 is provided at the point where the liquid nitrogen supply pipe 24a extending from the liquid nitrogen storage tank 23 exits the heat exchanger 13.
0, the valve 51 provided at the starting end of the liquid nitrogen supply pipe 24a may be controlled so that the amount of product nitrogen gas taken out is constant.

〔Effect of the invention〕

The high-purity nitrogen gas production apparatus of the present invention does not use an expansion turbine and instead uses a liquid nitrogen storage tank that does not have any rotating parts, so the apparatus as a whole has no rotating parts and does not have any trouble. Furthermore, while expansion turbines are expensive, liquid nitrogen storage tanks are inexpensive and do not require special personnel. Furthermore, the expansion turbine (which is driven by the pressure of the gas evaporated from the liquid air accumulated in the nitrogen rectification column) has an extremely high rotational speed (tens of thousands of rotations/minute), so load fluctuations (the removal of product nitrogen gas) It is difficult to perform fine-grained follow-up operation for changes in quantity. Therefore, it is difficult to accurately change the amount of liquid air supplied to the expansion turbine in accordance with changes in the amount of product nitrogen gas taken out, and to constantly cool compressed air, which is the raw material for nitrogen gas production, to a constant temperature. However, the purity of the product nitrogen gas obtained varied, and low-purity products were frequently produced, resulting in an overall low purity product nitrogen gas. Instead, this device uses a night body nitrogen storage tank and uses liquid nitrogen, whose supply amount can be finely adjusted, as the cooling source for the heat exchanger, making it possible to closely follow load fluctuations and maintain stable purity. This makes it possible to produce extremely high nitrogen gas. therefore,
Conventional purification equipment is not required. Furthermore, this device does not use liquid nitrogen for cooling and release it after use, but rather uses it as a product nitrogen gas with nitrogen gas produced using air as a raw material, so no resources are wasted. In addition, this device is equipped with an adsorption column with a built-in adsorbent that selectively adsorbs nitrogen, and the oxygen-rich waste vaporized liquid air after nitrogen gas collection is supplied from the nitrogen rectification column to the adsorption column to produce oxygen gas. Oxygen gas can be obtained efficiently. As described above, the apparatus of the present invention is ideal for use in the electronics industry because it can efficiently produce high-purity nitrogen gas and oxygen gas with one apparatus.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIGS. 2 and 3 are block diagrams of modified examples thereof. 9...Air compressor 12...Adsorption cylinder 13. ...
Heat exchanger 15... Nitrogen rectification column 17... Vibrator
]8...Liquid air 21...Decentralizer section 21a...
・Condenser 21d...Liquid nitrogen reservoir 22...Tower part 23...Liquid nitrogen storage tank 24a...Inlet pipe 27...Takeout vibe 28...Main pipe 2
9...Discharge path vibrator 40.41.42...Adsorption cylinder
44...Vacuum pump 45...Product oxygen gas extraction path

Claims (3)

[Claims] (1) An air compression means that compresses air taken in from the outside, a removal means that removes carbon dioxide and water from the compressed air compressed by the air compression means, and a removal means that removes the compressed air that has passed through the removal means. A heat exchange means for cooling to an ultra-low temperature, a liquid nitrogen storage means for storing liquid nitrogen, and an introduction path leading the liquid nitrogen in the liquid nitrogen storage means to the heat exchange means so as to serve as a cold source for the heat exchange means; A nitrogen rectification column that liquefies a portion of the compressed air that has been cooled to an ultra-low temperature by the heat exchange means and stores it internally to retain only nitrogen as a gas, and a nitrogen rectification column that liquefies a portion of the compressed air that has been cooled to an ultra-low temperature by the heat exchange means and vaporizes the air after the heat exchange means has finished its function as a cold source. a nitrogen gas extraction path for extracting both liquid nitrogen and vaporized nitrogen held in the nitrogen rectification column from the nitrogen rectification column as product nitrogen gas; and a compressed air liquefied product stored in the nitrogen rectification column. Or, an adsorption cylinder equipped with a discharge path for releasing fluid such as the vaporized product to the outside, and a built-in adsorbent that selectively adsorbs nitrogen is connected to the discharge path, and an extraction path for taking out the fluid after nitrogen removal is connected to the adsorption column. A high-purity nitrogen gas production device characterized by being connected to a cylinder. (2) A plurality of adsorption cylinders are each connected to a discharge path via a flow path with a valve, and any one of the adsorption cylinders can be used by switching the valve.
High-purity nitrogen gas production equipment as described in . (3) The high-purity nitrogen gas production apparatus according to claim 1 or 2, wherein the adsorbent is synthetic zeolite.