JPS6115068A - 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. As methods for removing impure oxygen, there is a method in which a trace amount of hydrogen is added to nitrogen gas using a PT catalyst, which is reacted with impure oxygen in an atmosphere at a temperature of about 200°C, and removed as water, and a method using a Ni catalyst. There is a method of removing impure oxygen in nitrogen gas by bringing it into contact with an Nl catalyst in an atmosphere at a temperature of about 200° C. to cause a Ni+1/20□-NiO reaction. However, these methods
In either case, the nitrogen gas must be brought into contact with the catalyst at a high temperature, so the device cannot be incorporated into a nitrogen gas production device 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 method (2) 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,
There is a problem in that oxygen remains or added hydrogen remains and becomes impurities, which requires skill in operation. In addition, in the method (2) above, it became necessary to regenerate NiO produced by the reaction with impure oxygen (NiO + H, → Ni + H20), which required H2 gas equipment for regeneration, leading to an increase in refining costs. . Therefore, these improvements have been 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 (
Through cryogenic liquefaction separation, low-boiling point nitrogen is extracted as a gas, and the remainder accumulates as oxygen-rich liquid air.It is driven by the pressure of the evaporated gas. 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 these demands, the inventor has developed a nitrogen gas production device that removes the expansion turbine and instead supplies chilled liquid nitrogen from outside into the rectification column, and has already filed a patent application (patent application) for this device. 1983-38050) L,

Since this device can produce nitrogen gas of extremely high purity, conventional purification equipment is completely unnecessary. Also,
Since the expansion turbine is removed, there are no adverse effects caused by it. 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 iron manufacturing 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 a carbon dioxide in the compressed air compressed by the air compression means. A removal means for removing gas and water, a liquid nitrogen storage means for storing liquid nitrogen, a heat exchange means for cooling the compressed air that has passed through the removal means to an ultra-low temperature, and a compressed air cooled to an ultra-low temperature by the heat exchange means. A nitrogen rectification column that liquefies a part of the air and stores it inside to hold only nitrogen as a gas, and a nitrogen rectification column that uses the liquid nitrogen in the liquid nitrogen storage means as a cold source for liquefying compressed air. and a nitrogen gas intake path for taking out both the liquid nitrogen vaporized after its role as a cooling source and the vaporized nitrogen held in the nitrogen rectification tower as product nitrogen gas from the nitrogen rectification tower. and a discharge path for discharging fluid such as compressed air liquefied product or its vaporized product stored in the nitrogen rectification column to the outside, and an adsorption cylinder with a built-in adsorbent that selectively adsorbs nitrogen is provided in the discharge channel. , and a take-out passage for taking out the fluid after nitrogen removal is connected to the adsorption cylinder.

Next, the present invention will be explained 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 column 12 is filled with molecular sieve and functions to adsorb and remove H, O, and CO□ in the air compressed by the air compressor 9. 13 is a heat exchanger, and adsorption cylinder 1
The compressed air from which H, O, and Co2 have been adsorbed and removed by the compressed air supply pipe 8 is sent through the compressed air supply pipe 8.

The compressed air sent here is cooled to an extremely low temperature by the heat exchange action of the heat exchanger 13. Reference numeral 15 designates a nitrogen rectification column whose top part is a condenser section 21 having a condenser 21a, which is cooled to an ultra-low temperature by a heat exchanger 13 and passed through a pipe 17.
The compressed air sent through the tank is further cooled, a part of which is liquefied and stored at the bottom as liquid air 18, and only nitrogen is taken out in a gaseous state. - That is, the rectifying column 15 is divided at the upper part by a partition plate 20 to form a dephlegmator part 21, and the part below it is a column part 22. In the upper part of this tower part 22,
Liquid nitrogen is directly fed from the liquid nitrogen storage tank 23 through the introduction pipe 24a, and the liquid nitrogen produced in the condenser 21a of the demultiplexer section 21 is stored in the liquid nitrogen reservoir 21d provided in the upper part of the liquid nitrogen storage tank 23. Liquid nitrogen is supplied flowing down through the pipe 21C, and both of the liquid nitrogens flow downward in the column section 22, contact countercurrently with the compressed air rising from the bottom of the column section 22, cool it, and cool it down. It is designed to liquefy some parts. 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, are liquefied and accumulated at the bottom of the column section 22.
It collects at the top of the. Further, the condenser 21a is disposed in the demultiplexer section 21 as described above, and a part of the nitrogen gas accumulated in the upper part of the column section 22 is sent to this condenser 21a through the pipe 21b. The inside of the dephlegmator section 21 is in a lower pressure state than the inside of the column section 22, and the liquid air (N, 5
0 to 70%, 30 to 50%) 18 is fed through a pipe 19 with an expansion valve 19a, 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, and the liquid nitrogen reservoir 21 in the tower section 22 is heated as described above.
It flows down into d. Reference numeral 25 denotes a liquid level gauge, which controls a valve 26 according to the liquid level of liquid air in the partial condenser section 21 to control the amount of liquid nitrogen supplied from the liquid nitrogen storage tank 23.

Reference numeral 27 is a take-out pipe for taking out the nitrogen gas accumulated in the upper part of the rectification column section 22, which guides the extremely low-temperature nitrogen gas into the heat exchanger 13, and exchanges heat with the compressed air sent there to bring it to room temperature. 28. In this case, at the top of the rectification column section 22, along with nitrogen gas,
He with a low boiling point (-269℃), N2 (-253℃
) is likely to accumulate, so the extraction pipe 27 is opened considerably below the top of the tower section 22 to extract only pure nitrogen gas that does not contain He or N2.

29 transfers the waste vaporized liquid air in the dephlegmator section 21 to the heat exchanger 1
3, and 29a is its pressure holding valve. 40, 41, and 42 are adsorption cylinders each filled with an adsorbent (synthetic zeolite: molecular sieve) that selectively adsorbs N2, and each inlet has an inflow channel equipped with valves 40b, 41b, and 42b. 40a, 4
It is connected to the discharge path pipe 29 via 1a and 42a. 44 is a vacuum pump, which includes a suction path 43 and a valve 40.
c, 41c, 42c to the adsorption cylinders 40, 41.4.
It is connected to the second entrance. 40d, 41d, and 42d are take-out passages connected to the outlets of the adsorption cylinders 40, 41, and 42, respectively, and valves 40e, 41e, and 42e, respectively.
It is equipped with These extraction paths 40d, 41d, 42d
is connected to a buffer tank 46 via a product oxygen gas extraction 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 system line, and when the air compression line breaks down, the liquid nitrogen in the liquid nitrogen storage tank 23 is evaporated by the evaporator 31 and sent to the main pipe 28, so that the supply of nitrogen gas is interrupted. Make sure not to. 32 is an impurity analysis needle that analyzes the purity of the product nitrogen gas sent to the main pipe 28, and when the purity is low, operates valves 34 and 342 to release the product nitrogen gas to the outside as shown by arrow B. have the effect of Furthermore, the dashed line indicates a vacuum cooling box, which accommodates the 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 H2C and CO2
is removed by adsorption. Then, the compressed air from which H, O, and CO2 have been adsorbed and removed is sent to the heat exchanger 13 and cooled to an ultra-low temperature, and in that state is introduced into the lower part of the rectification column section 22. Next, this input compressed air is cooled by contacting with the liquid nitrogen sent into the rectification column section 22 from the liquid nitrogen storage tank 23 and the overflowing liquid nitrogen from the liquid nitrogen reservoir 21d, and a part of it is liquefied. The air is stored as liquid air 18 at the bottom of the tower section 22. In this process, due to the difference in boiling point between nitrogen and oxygen (boiling point of oxygen = 183°C, boiling point of nitrogen -196°C), 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 513, 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 supplied from the liquid nitrogen storage tank 23 acts as a cold source for liquefying the compressed air, and is itself 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 in the lower part of the rectification column section 22 is sent into the partial condenser section 21 to cool the condenser 21a, and then vaporized to become waste vaporized liquid air, which is then heat exchanged through the pipe 29. The gas is fed into the vessel 13 and heated up, and in that state is sent to any adsorption cylinder among the adsorption cylinders 40, 41, and 42, where nitrogen gas is adsorbed and removed, and it becomes oxygen gas and is sent to the buffer tank 46. It will be done. In this case, any one of the suction ffs 140, 41.42 is activated for suction, and the remaining ones are used for the vacuum pump 4.
Each valve 40b to 42b, 40c to 42 receives the vacuum regeneration action of step 4, and then the adsorption column that is activated for adsorption goes into regeneration, and one of the regenerated cylinders goes into adsorption operation, and so on.
c, 40e to 42e are controlled. In this way,
High purity nitrogen gas and oxygen gas can now be obtained simultaneously with one device. In this case, the ratio (volume ratio) of the product nitrogen gas and product oxygen gas obtained is approximately 1 oll.

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. In other words, this rectification column]
5 is separated from a partial condenser section 21 (tower section 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 this partial condenser section 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. 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
Oxygen gas is used as a raw material for oxygen gas, heated in the heat exchanger 13, and vaporized into any adsorption column 40.41.42.
supplied to

〔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. This device uses a liquid nitrogen storage tank instead, and uses liquid nitrogen, whose supply amount can be finely adjusted, as the cooling source for the compressed air, making it possible to closely follow load fluctuations, and with extremely stable purity. It becomes possible to produce 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 an embodiment of the present invention, and FIG. 2 is a block diagram of a modification thereof. 9...Air compression v&】2...Adsorption cylinder 13. ...
Heat exchanger 15...Nitrogen rectification column 17...Pipe
18...Liquid air 21...Decentralizer part 21a...
・Condenser 21d...Liquid nitrogen reservoir 22...Tower section 23...Liquid nitrogen storage tank 24a...Inlet pipe 27...Outlet pipe 28...Main pipe 2
9...Discharge pipe 40.41.42...Adsorption cylinder
44...Vacuum pump 45...Product oxygen gas extraction path

Claims (3)

[Claims] (1) Air compression means for compressing air taken in from the outside, removal means for removing carbon dioxide and water from the compressed air compressed by the air compression means, and liquid nitrogen storage for storing liquid nitrogen. a heat exchange means that cools the compressed air that has passed through the removal means to an ultra-low temperature; and a nitrogen liquefier 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 inside to retain only nitrogen as a gas. a rectification column, an introduction path for introducing liquid nitrogen in the liquid nitrogen storage means into the nitrogen rectification column as a cold source for liquefying compressed air, and liquid nitrogen that has been vaporized after its role as a cold source and the nitrogen A nitrogen gas extraction path for taking out both of the vaporized nitrogen held in the rectification column as product nitrogen gas from the nitrogen rectification column, and a compressed air liquefied product or its vaporized product stored in the nitrogen rectification column, etc. 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. High purity nitrogen gas production equipment. (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.