JPS61143681A - 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.

[Snowscape technology]

The electronic industry uses extremely large amounts of high purity nitrogen gas. For this reason, supply of inexpensive high-purity nitrogen gas has been desired, and PSA manufacturing equipment has been introduced to meet this demand. This PSA manufacturing equipment has two adsorption tanks containing zeolite for oxygen adsorption, and compressed air is fed into these tanks alternately every minute using a pressure swing method, and the built-in adsorbent absorbs the air. It adsorbs and removes oxygen to produce nitrogen gas. However, this device alternately sends compressed air to the two adsorption tanks every minute, and at the same time vacuum suction regenerates the inside of the adsorption tank to which no air is being sent.
This method requires a large number of valves, complicates valve operation, and is prone to frequent failures. In order to solve these problems, the present inventors developed a manufacturing device whose concept is significantly different from conventional high-purity nitrogen gas manufacturing devices.

This is shown in FIG. In the figure, 1 is an air compressor, 2
is a drain separator, 3 is a freon cooler, and 4 is a set of two adsorption cylinders. The adsorption cylinder 4 is filled with molecular sieve inside and absorbs H in the air compressed by the air compressor 1.
, O, and CO□. 5 is the first
It is a heat exchanger for H2O and Cot by the adsorption column 4.
Compressed air with adsorbed and removed particles is sent in. 6 is a second heat exchanger, into which the compressed air that has passed through the first heat exchanger 5 is sent. 7 is a liquid nitrogen storage tank, and the liquid nitrogen therein is fed into the upper part of the rectification column 10 through a first introduction pipe 8. This rectification column 10 has a dephlegmator section 15 having a condenser 15a at the top, and compressed air is cooled to an ultra-low temperature by first and second heat exchangers 5.6 and sent through a pipe 16. is further cooled, a part of it is liquefied and stored at the bottom as liquid air 16a, and only nitrogen is taken out in a gaseous state. That is, the rectification column 10 has an upper part divided by a partition plate 17 and a demultiplexer section 1.
5, and the part below it is the tower section 18. Liquid nitrogen from the liquid nitrogen storage tank 7 is fed into the upper part of the column section 18 via the first introduction pipe 8, and liquid produced in the condenser 15a of the demultiplexer section 15 is fed into the upper part of the column section 18. Nitrogen passes through the pipe 15c to the liquid nitrogen reservoir 15.
d, flows downward within the tower section 18, contacts countercurrently with the compressed air rising from the bottom of the tower section 18, 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 18, and the low boiling point components, nitrogen gas, accumulate at the top of the column section 18.

Furthermore, the condenser section 15 includes a condenser 1 as described above.
A part of the nitrogen gas accumulated in the upper part of the tower part 18 is sent through the pipe 15e. The inside of this dephlegmator section 15 is in a lower pressure state than the inside of the column section 18,
Liquid air stored at the bottom of the tower section 18 (Nz 50-70%,
0 = 30~50%) 16a is pipe 1 with expansion valve 16b
6c, it is vaporized and cooled to a temperature below the boiling point of the internal temperature. Due to this cooling, the nitrogen gas fed into the condenser 15a is liquefied and flows down into the liquid nitrogen reservoir 15d in the tower section 18 as described above. Reference numeral 8a denotes a liquid level gauge, which controls the pulp 8b and the amount of liquid nitrogen supplied from the liquid nitrogen storage tank 7 according to the liquid level of the liquid air in the partial condenser section 15. 10a is the rectification column section 1
8, the ultra-low temperature nitrogen gas is passed through an adsorption column 11 containing zeolite (which selectively adsorbs oxygen and carbon monoxide at an ultra-low temperature) to the second and first It is guided into the heat exchangers 6, 5, exchanges heat with the compressed air sent there, is brought to room temperature, and is sent into the main pipe 9. In this case, at the top of the rectification column section 18, along with nitrogen gas, hydrogen having a low boiling point is added.
Since e (-269°C), H, (-253°C) tend to accumulate, the outlet pipe 10a is opened slightly below the top of the tower section 18, and pure nitrogen without He, H, is mixed. It is designed to extract only gas. 19 transfers the vaporized liquid air in the dephlegmator section 15 to the second and first heat exchangers 6
It is a pipe for sending air to a temperature of 5°C, exchanging heat, and releasing air as shown by arrow A, and 19a is its pressure holding valve. Reference numeral 12 denotes a backup system line, which transfers liquid nitrogen from the liquid nitrogen storage tank 7 to the evaporator 1 when the air compression system line 13 breaks down.
4 to evaporate it and send it to the main pipe 9, so that the supply of nitrogen gas does not stop.

In addition, 20 is an impurity analyzer, which analyzes the purity of the product nitrogen gas sent out from the main pipe 9, and when the purity is low, operates valves 21 and 22 to send the product nitrogen gas to the arrow B.
It acts to release air to the outside like this. Furthermore, the dashed line indicates a vacuum cooling box, which acts to block heat from entering from the outside and further improve purification efficiency.

This device produces product nitrogen gas in the following manner. That is, air is compressed by an air compressor 1, water in the compressed air is removed by a drain separator 2, and cooled by a fluorocarbon cooler 3. In this state, the air is sent to an adsorption column 4, and the Hz O in the air is and adsorbs and removes Co2. Next, HzO.

The compressed air from which COz has been adsorbed and removed is sent into the first and second heat exchangers 5.6 to be cooled to a low temperature, and in that state is introduced into the lower part of the rectification column section 18.

Next, this input compressed air is cooled by contacting with the liquid nitrogen sent into the rectification column section 18 from the liquid nitrogen storage tank 7 and the overflowing liquid nitrogen from the liquid nitrogen reservoir 15d, and a part of it is liquefied. The air is stored at the bottom of the tower section 18 as liquid air 16a. In this process, due to the difference in the boiling points of nitrogen and oxygen (boiling point of oxygen -183℃, boiling point of nitrogen -196℃),
Oxygen, a high-boiling component in compressed air, liquefies, leaving nitrogen as a gas. Next, the remaining gaseous nitrogen is taken out from the extraction pipe 16c and passed through the adsorption column 11 to improve its purity, and then transferred to the first and second heat exchangers 5,
6, the nitrogen gas is heated to near room temperature, and then sent out from the main pipe 9 as a product nitrogen gas. In this case, the liquid nitrogen from the liquid nitrogen storage tank 7 acts as a cold source for liquefying the compressed air, and is itself vaporized and taken out from the take-out pipe 10a as part of the product nitrogen gas.

This device can produce extremely high purity nitrogen gas in normal operating state B (state in which the air compression system line 13 is in operation). Further, during its manufacture, it does not require complicated valve operations unlike conventional PSA manufacturing apparatuses, and is therefore easy to operate. However, once the air compression system line 1
3 is out of order and the backup system line 12 is activated, there is a problem that the purity of the product nitrogen gas obtained from the main pipe 9 tends to decrease. In the air compression system line 13, this applies to the rectification column 10 and the adsorption column 1.
1, the product nitrogen gas is extremely purified, whereas in the backup system line 12, the liquid nitrogen storage tank 7
This is due to the fact that liquid nitrogen is directly vaporized and extracted as product nitrogen gas.

[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 not only in an air compression system line but also in a backup system line.

[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 removal means for removing liquid nitrogen; a liquid nitrogen storage means for storing liquid nitrogen; a heat exchange means for cooling the compressed air to an ultra-low temperature; a rectification column that retains only nitrogen as a gas; a first introduction path that leads the liquid nitrogen in the liquid nitrogen storage means to at least one of the rectification column and the heat exchange means as a cold source; A first extraction path that takes out both the liquid nitrogen vaporized after the action of the liquid nitrogen and the vaporized nitrogen held in the rectification column as product nitrogen gas, and the liquid nitrogen that vaporizes the liquid nitrogen by exchanging heat with the atmosphere. an evaporator, a second introduction path for guiding the liquid nitrogen in the liquid nitrogen storage means to the liquid nitrogen evaporator, and a second extraction path for taking out the liquid nitrogen vaporized in the liquid nitrogen evaporator as product nitrogen gas. , comprising an opening/closing means for opening and closing the first and second introduction passages so that liquid nitrogen flows into either the first or second introduction passage, the liquid nitrogen evaporation apparatus comprising a plurality of liquid nitrogen evaporators each having an adsorption device. A plurality of the liquid nitrogen evaporators are connected to the second introduction path through an inflow path with an absorber and a shutoff valve, respectively, and the liquid nitrogen inlet of each liquid nitrogen evaporator is is provided with a discharge passageway with a relief valve to the atmosphere, and the outlet passageway of each liquid nitrogen evaporator is configured such that a portion of the vaporized liquid nitrogen in the outlet passageway of one liquid nitrogen evaporator is transferred to the outlet passageway of another liquid nitrogen evaporator. The configuration is such that the connection is made via a connection path leading to the inlet of the adsorber.

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

FIG. 2 shows an embodiment of the invention. This high-purity nitrogen gas production apparatus has the same air compression system line 13 as the high-purity nitrogen gas production apparatus shown in FIG. 1, but the backup system line 12 is significantly different.
High purity nitrogen gas can also be produced in the backup system line 12. To explain this backup system line 12 in detail, 7 is a liquid nitrogen storage tank consisting of a vacuum insulated double tank similar to the device shown in FIG. First and second adsorbers 2 each containing a synthetic zeolite adsorbent housed in a vacuum insulation shell are installed at the branch parts 8x and 8y.
7.28 is provided. The synthetic zeolite adsorbent has the property of selectively adsorbing oxygen, carbon monoxide, etc. at extremely low temperatures, and Molecular Sheep 3A, 4A, 5A, etc. manufactured by Union Carbide Co., Ltd. are usually used. A cooling pipe is wound around the outer peripheral surface of each of the adsorbers 27 and 28 for constant cooling so that the low-temperature characteristics of the built-in adsorbent can be exhibited at any time. These cooling pipes form part of the branch portions 8x and 8y of the first introduction pipe 8. 3o to 33 are cutoff valves provided at the branch portions ax and sy of the first introduction pipe 8. Reference numeral 36 denotes a second introduction path pipe, which functions to take out liquid nitrogen from the liquid nitrogen storage tank 7 when the backup system line 12 is activated. This second introduction path vibe 36
from the tips of the first and second inlet pipes 38.40
is branching out. That is, the first inlet pipe 38 transfers the liquid nitrogen in the liquid nitrogen storage tank 7 to the first adsorber 27.
The liquid nitrogen is guided to the first liquid nitrogen evaporator 34 via the liquid nitrogen evaporator 34 and is vaporized. 38a is a portion of the first inflow pipe 38 on the inlet side of the first adsorber 27, 38b is a portion of the outlet thereof, and 38c is a portion of the first inflow pipe 38 on the inlet side of the liquid nitrogen evaporator 34. The part 38d is the part on the outlet side (the outlet flow path). 37 is a cutoff valve provided on the second inlet pipe 36; 39 is a cutoff valve provided on the first inflow pipe 38; 49 is a discharge pipe 4.
The check valve 43, which is provided as a set with the cutoff valve 50, is provided in the portion 38c of the first inflow pipe 38 on the inlet side of the liquid nitrogen evaporator 34 in the first inflow pipe 38. The cutoff valve 56 is a cutoff valve provided in the portion 38d of the inlet pipe on the outlet side thereof. The second inflow pipe 40 is similar to the first inflow pipe 38,
The liquid nitrogen in the liquid nitrogen storage tank 7 is guided to the second liquid nitrogen evaporator 35 via the second adsorber 28 and vaporized. 40a is a portion of the second inflow pipe 40 on the inlet side of the second adsorber 28, 40b is a portion of the outlet thereof, and 40c is a portion of the second inflow pipe 40 on the inlet side of the liquid nitrogen evaporator 35. The part 40d is the part on the outlet side (the outlet flow path). 41 is a shutoff valve provided in the second inflow pipe 40, and 52 is a discharge pipe 5.
A check valve 46 is provided in a portion 40C of the second inflow pipe 40 on the inlet side of the liquid nitrogen evaporator 35 in the second inflow pipe 40. A cutoff valve 58 is a cutoff valve provided at a portion 40d of the second inflow pipe 40 on the outlet side thereof. A first connection path 59 connects a portion 38d of the first inlet pipe 38 on the outlet side of the first liquid nitrogen evaporator 34 and a portion 40a on the inlet side of the second adsorber 28.

60 and 63 are cutoff valves provided in the connection path 59. A second connection path 61 connects a portion 40d of the first inlet pipe 40 on the outlet side of the second liquid nitrogen evaporator 35 and a portion 38a on the inlet side of the first adsorber 27.

62.62a is a cutoff valve provided in the connection path 61, and 54 is a second extraction path pipe, which connects the liquid nitrogen evaporator 34.
．． It functions to take out the liquid nitrogen vaporized in step 35 as a product nitrogen gas and send it to the main pipe 9.

In this configuration, in a normal state in which the air compression system line 13 operates, the cutoff valve 37 of the second introduction pipe 36 is closed, and the branch portions 8x, 8y of the first introduction pipe 8 are closed.
One of the shutoff valves 30, 31 is open and the other is closed. For example, when the valve 30 is open and the valve 31 is closed, the liquid nitrogen in the liquid nitrogen storage tank 7 passes through the first introduction pipe 8 and the branch part 8x and reaches the first adsorber 27. After cooling the adsorber 27, the rectifying column 1
0 into the tower section 18 as a cold source. In this case, since the first adsorber 27 is cooled with liquid nitrogen, its built-in adsorbent can be used at any time to exhibit its characteristics (selective adsorption of oxygen and carbon monoxide at extremely low temperatures). is in a state. On the other hand, the second adsorber 28
Since no liquid nitrogen flows from the liquid nitrogen storage tank 7, the temperature is at room temperature, and the built-in adsorbent can be regenerated. Next, when the air compression system line 13 breaks down, the shutoff valve 30, which had been open until then, immediately closes.

Therefore, the branch portion 8x of the first introduction pipe 8, By
Both of the shutoff valves 30 and 31 will be closed. At this time, at the same time, the cutoff valve 37 of the second introduction path pipe 36 opens, and the backup system line 12 comes into operation. In this case, the backup system line 12 does not directly send the liquid nitrogen in the liquid nitrogen storage tank 7 to one of the liquid nitrogen evaporators 34, 35, but cools it to a low temperature in the normal state in which the air compression system line 13 operates. Since impure oxygen and the like are removed through the absorber 27 or 28, which has an enhanced adsorption capacity, and then evaporated, a highly pure product nitrogen gas can be obtained. In this embodiment, since the adsorber 27 is cooled in the normal state, liquid nitrogen is fed into the adsorber 27. however,
Since the adsorbent in adsorbers 27 and 28 has a limited adsorption capacity,
Operate while playing alternately. For example, when performing adsorption with one adsorber 27 as described above, the other adsorber 2
8 is at room temperature as described above, so the adsorbent is regenerated.

That is, in the inflow pipe 38.40, the valve 39 is opened, the valve 41.62a is closed, the valve 50 of the discharge pipe 48 is closed, and the valves 43.56 on the inlet side and the outlet side of the liquid nitrogen evaporator 34 are closed. As a result, liquid nitrogen passes through the second inlet pipe 36 and enters one adsorber 27, where it is adsorbed and purified, and then vaporized in the liquid nitrogen evaporator 34 and sent to the second take-out pipe. 54 as a high-purity product nitrogen gas. At this time, the valve 60 of the first connection path 59 is kept open, the valve 62 of the second connection path 61 is closed, and the first connection path 59 is opened. Open the valve 63, open the valve 53 of the other discharge pipe 51, and close the valve 46. As a result, a part of the high-purity nitrogen gas obtained by vaporizing in the liquid nitrogen evaporator 34 is 1 connection path 59
After passing through the other adsorbent 28 and regenerating the adsorbent, the valve 53. It passes through the check valve 52 and is released into the atmosphere. In this case, before the adsorption capacity of one adsorber 27 decreases, the regeneration of the other adsorber 28 is completely completed, and the valve 37
．． 41 and close the valve 63 to transfer liquid nitrogen from the liquid nitrogen storage tank 7 to the adsorber 28 via the pipe 36.40.
The other adsorber 28 must be pre-cooled. The liquid nitrogen that has been precooled and vaporized is discharged into the atmosphere from the discharge path pipe 51. After sufficiently precooling the other adsorber 28 in this way, the answer is changed, and this time, the other adsorber 28 adsorbs and purifies the liquid nitrogen supplied from the liquid nitrogen storage tank 7, and during that time A portion of the obtained high-purity nitrogen gas is used to regenerate the adsorbent in one of the adsorbers 27. In this way, by alternately regenerating and using the adsorbers 27 and 28 on the other side, nitrogen gas having the same purity as the product nitrogen gas obtained in the air compression system line 13 can also be produced in the backup system line 12. You will be able to get it.

FIG. 4 shows another embodiment. That is, liquid nitrogen is once vaporized in the evaporator 34.35, turned into ultra-low-temperature vaporized liquid nitrogen, and sent to the adsorber 27.28 for vapor phase adsorption of impurities, and then sent to the heat exchangers 34a and 35b. I put it in and let it warm up to room temperature. Since the other parts are substantially the same as the apparatus shown in FIG. 3, the same or corresponding parts are given the same reference numerals.

In addition, in the above embodiments, the air compression system line 1
3 is provided with an adsorption cylinder 11, but it is not necessarily necessary to provide it. The same applies to the vacuum cooler box shown by the dashed line.

〔Effect of the invention〕

As described above, the high-purity nitrogen gas production apparatus of the present invention has the following features:
Multiple sets of liquid nitrogen evaporators and absorbers are installed in the backup system line used in emergencies, and any one of the multiple sets of liquid nitrogen evaporators/adsorbers can be used to evaporate liquid nitrogen. At the same time as purification, a part of the high-purity nitrogen gas obtained by that set is sent into the other set of adsorbers to automatically regenerate the adsorbent, so the equipment is stopped each time and this equipment is regenerated. The liquid nitrogen in the liquid nitrogen storage tank 7 is not introduced into the rectification column 10, but is introduced into the heat exchangers 5 and 6.

Since the other parts are substantially the same as those of the apparatus shown in FIG. 2, the same or corresponding parts are given the same reference numerals and repeated explanation will be omitted. In this device, in the air compression system line 13, the liquid nitrogen supplied from the liquid nitrogen storage tank 7 and vaporized by the heat exchangers 5 and 6 as a cold source is directly guided to the main pipe 9 and is used as a product nitrogen gas. parts, but the amount is small (1710 parts of the product nitrogen gas).
This does not significantly reduce the purity of the product nitrogen gas.

FIG. 5 shows yet another embodiment. This device is
A liquid nitrogen evaporator 34 is provided between the first inlet pipe 38 and the inlet portion 38a of one of the adsorbers 27,
A liquid nitrogen evaporator 35 is provided between the second inlet pipe 4o and the inlet portion 40a of the other adsorber 28, and vaporized gas temperature raising heat exchangers 343. 35b, the liquid nitrogen in the liquid nitrogen storage tank can be directly purified and converted into product nitrogen gas without requiring the trouble of regenerating the adsorbent supplied from the liquid nitrogen storage tank 7. Therefore, even in an emergency, it is possible to continuously produce product nitrogen gas with the same high purity as during normal operation.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a high-purity nitrogen gas production device that is the basis of this invention, FIG. 2 is a block diagram of an embodiment of this invention, and FIG.
The figure is an enlarged explanatory view of the main part, and FIGS. 4 and 5 are configuration diagrams of other embodiments.

Claims (4)

[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 for cooling the compressed air to an ultra-low temperature; a rectification column for liquefying a part of the compressed air cooled to an ultra-low temperature by the heat exchange means and storing it therein to retain only nitrogen as a gas; a first introduction path that leads the liquid nitrogen in the liquid nitrogen storage means as a cooling source to at least one of the rectification column and the heat exchange means, and the liquid nitrogen vaporized after functioning as a cooling source and the rectification column; a first extraction path for taking out both of the vaporized nitrogen held in the liquid nitrogen storage means as product nitrogen gas; a liquid nitrogen evaporator for vaporizing the liquid nitrogen by exchanging heat with the atmosphere; A second introduction path leads to the liquid nitrogen evaporator, a second take-out path takes out the liquid nitrogen vaporized in the liquid nitrogen evaporator as product nitrogen gas, and the liquid nitrogen is connected to the first or second introduction path. The liquid nitrogen evaporator comprises a plurality of liquid nitrogen evaporators each having an adsorption device, and includes an opening/closing means for opening and closing the first and second introduction passages so that the flow flows to either one of the liquid nitrogen evaporators. A plurality of liquid nitrogen evaporators are connected to the second introduction path via an absorber and an inflow path with a shutoff valve, respectively, and a discharge path with a relief valve to the atmosphere is provided at the liquid nitrogen inlet of each liquid nitrogen evaporator, and The outlet channels of each liquid nitrogen evaporator were connected via a connecting channel that led a portion of the vaporized liquid nitrogen in the outlet channel of one liquid nitrogen evaporator to the inlet of the adsorber of the other liquid nitrogen evaporator. A high-purity nitrogen gas production device characterized by: (2) The adsorbent in the adsorber is an adsorbent whose adsorption capacity increases at ultra-low temperatures, and the adsorber is cooled to an ultra-low temperature using the cold heat of liquid nitrogen flowing in the first introduction path. A high-purity nitrogen gas production apparatus according to claim 1. (3) The high-purity nitrogen gas production apparatus according to claim 1 or 2, wherein the adsorbent is a synthetic zeolite with a pore diameter of about 3 Å, 4 Å or 5 Å. (4) 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 for cooling the compressed air to an ultra-low temperature; a rectification column for liquefying a part of the compressed air cooled to an ultra-low temperature by the heat exchange means and storing it therein to retain only nitrogen as a gas; a first introduction path that leads the liquid nitrogen in the liquid nitrogen storage means as a cooling source to at least one of the rectification column and the heat exchange means, and the liquid nitrogen vaporized after functioning as a cooling source and the rectification column; a first extraction path for taking out both of the vaporized nitrogen held in the liquid nitrogen storage means as product nitrogen gas; a liquid nitrogen evaporator for vaporizing the liquid nitrogen by exchanging heat with the atmosphere; A second introduction path leads to the liquid nitrogen evaporator, a second take-out path takes out the liquid nitrogen vaporized in the liquid nitrogen evaporator as product nitrogen gas, and the liquid nitrogen is connected to the first or second introduction path. The liquid nitrogen evaporator is equipped with an opening/closing means for opening and closing the first and second introduction passages so that the flow flows in either direction, and the liquid nitrogen evaporator has a plurality of liquid nitrogen gases each having an adsorber and a heat exchanger for raising the temperature of the vaporized gas on the downstream side. A plurality of the liquid nitrogen evaporators are connected to the second introduction path through an adsorption device, a heat exchanger for raising the temperature of vaporized gas, and an inflow path with a shutoff valve, respectively, and each liquid nitrogen evaporator is A discharge path with a relief valve to the atmosphere is provided at the inlet of the heat exchanger for heating the vaporized gas in each liquid nitrogen evaporator, and the outlet flow path of the heat exchanger for heating the vaporized gas in each liquid nitrogen evaporator is A part of the vaporized liquid nitrogen in the outlet flow path of the heat exchanger for heating vaporized gas in the evaporator is connected via a connection path that leads to the inlet of the heat exchanger for heating vaporized gas in another liquid nitrogen evaporator. High purity nitrogen gas production equipment.