JPS6149594B2 - - Google Patents

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 generally uses air as a raw material,
After compressing this in a compressor, it is put into an adsorption cylinder to remove carbon dioxide and moisture, and then passed through a heat exchanger to cool it by exchanging heat with a refrigerant, and then cryogenically liquefied and separated in a rectification tower to produce nitrogen gas. It is manufactured through the process of producing a liquid and raising the temperature to near room temperature through the heat exchanger described above. however,
Since the fine nitrogen gas produced in this way contains oxygen as an impurity, it is often inconvenient to use it as it is. Impure oxygen can be removed by adding a small amount of hydrogen into nitrogen gas using a PT catalyst and reacting with impure oxygen in an atmosphere at a temperature of about 200°C to remove it as water, or by using a Ni catalyst to remove nitrogen gas. There is a method of removing impure oxygen in a 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 + 1/20 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. Moreover, in the above method,
High precision is required to adjust the amount of hydrogen added, and if you do not add just enough hydrogen to react with the amount of impure oxygen, oxygen may remain or the added hydrogen may remain and become an impurity. Therefore, there is a problem in that the operation requires skill. In addition, in the above method, regeneration of NiO produced by reaction with impure oxygen (NiO
＋H ₂ →Ni＋H ₂ O), H ₂ for regeneration
Gas equipment was required, leading to an increase in refining costs. Therefore, these improvements have been strongly desired.

In addition, conventional nitrogen gas production equipment 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, the rotation speed of the expansion turpin is extremely high (tens of thousands of times per minute).
However, it is difficult to follow load fluctuations, and specially trained operators are required. Also,
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. In other words, since the expansion turbine has a high-speed rotating part, it causes the problems mentioned above.
There has been a strong desire to eliminate expansion turbines having such high-speed rotating parts.

In order to meet such demands, this inventor
We have developed a nitrogen gas production device that eliminates the expansion turbine and instead supplies externally cooled liquid nitrogen into a heat exchanger such as a heat exchanger, and has already applied for a patent (patent application 1986-4760). There is. This equipment can produce extremely high purity nitrogen gas, so
The conventional purification equipment is completely unnecessary. Furthermore, 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.
It has been desired to provide an apparatus that can produce not only nitrogen gas but also oxygen gas with one apparatus.

[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 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 liquid nitrogen storage means for receiving and storing liquid nitrogen from outside the apparatus, and a liquid nitrogen storage means for replacing the liquid nitrogen in the liquid nitrogen storage means with the cold heat generated from the cold heat generation expander and continuously supplying the above liquid nitrogen. an inlet passage leading to the heat exchange means; a nitrogen gas take-out passage for taking out the nitrogen gas produced in the rectification column as product nitrogen gas; Controlling the temperature of the nitrogen gas passing through the derivation path to a constant level by controlling the supply amount of liquid nitrogen from the liquid nitrogen storage means to the heat exchange means and the derivation path that leads to the gas take-out path and joins the product nitrogen gas. a plurality of adsorption cylinders having a nitrogen gas selective adsorption capacity; a plurality of inlet pipes that communicate the inlets of the plurality of adsorption cylinders with the outlet of the discharge pipe in the demultiplexer; a plurality of first on-off valves respectively provided in the inlet pipes of the plurality of adsorption cylinders; an oxygen gas extraction path extending from the outlet of the plurality of adsorption cylinders; a regeneration means for the adsorption cylinder; and the regeneration means and the plurality of adsorption cylinders. a plurality of regeneration paths each communicating with the plurality of regeneration paths, a plurality of second on-off valves provided in each of the plurality of regeneration paths, and an adsorption cylinder remaining after the adsorption operation of any one of the plurality of adsorption cylinders. The apparatus is configured to include an on-off valve control means for controlling the opening and closing of the first and second on-off valves so that the cylinder is regenerated or stopped.

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

FIG. 3 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 a molecular sieve and functions to adsorb and remove H ₂ O and CO ₂ from the air compressed by the air compressor 9. 13 is a heat exchanger, and the adsorption cylinder 12
The compressed air from which H ₂ O and CO ₂ have been adsorbed and removed is sent through the compressed air supply pipe 8 . 23 is a liquid nitrogen storage tank that receives liquid nitrogen from outside the apparatus and stores it. This liquid nitrogen storage tank 23 is
The liquid nitrogen inside is sent to the heat exchanger 13 through the inlet pipe 24a, where it is heat exchanged with the compressed air sent into the heat exchanger 13, cooling the compressed air to an ultra-low temperature, while the liquid nitrogen is transferred to the heat exchanger 13. It is supposed to be vaporized at 13. The liquid nitrogen vaporized by the heat exchanger 13 is sent into the main pipe 28 for delivering product nitrogen gas via the outlet pipe 24b. 15 is a nitrogen rectification column equipped with a demultiplexer 21 with a built-in condenser 21a at the top of the column, which further cools the compressed air cooled to an ultra-low temperature by the heat exchanger 13 and sent through the pipe 17, and a part of it is is liquefied and stored in the bottom as liquid air 18, while only nitrogen is stored in a gaseous state in the upper ceiling. 20 is a ceiling board. To explain in more detail, the condenser 21 in the demultiplexer 21
A part of the nitrogen gas accumulated in the upper part of the rectification column 15 is fed into the column a through the first reflux pipe 21b. The inside of this dephlegmator 21 is in a lower pressure state than the inside of the rectification column 15, and the liquid air (N ₂ 50-70%, O ₂ 30-50%) 18 stored at the bottom of the rectification column 15 expands. It is fed through a pipe 19 with a 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. The liquid nitrogen generated in the condenser 21a of the demultiplexer 21 is supplied to the upper part of the rectification column 15 through a second reflux pipe 21c, and is supplied to the rectification column via the liquid nitrogen reservoir 21d. The air flows downward in the rectification column 15, contacts the compressed air rising from the bottom of the rectification column 15 in a countercurrent manner, cools it, and partially liquefies it. In this process, the high boiling point component (oxygen component) in the compressed air is liquefied and accumulates at the bottom of the rectification column 15, and the low boiling point component, nitrogen, accumulates in the upper part of the rectification column 15 in a gaseous state. Reference numeral 27 denotes an extraction pipe for taking out the nitrogen gas accumulated in the upper ceiling of the rectification column 15, 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. 28. In this case, He (-269°C) and H ₂ (-253°C), which have low boiling points, tend to accumulate at the top of the rectifying column 15 along with nitrogen gas.
The opening is opened below the top of the tank, and only pure nitrogen gas without He or H ₂ mixed therein can be taken out as product nitrogen gas. 29 is a discharge path pipe that sends the waste vaporized liquid air in the dephlegmator 21 to the heat exchanger 13, and 29a is its pressure holding valve. 4
0, 41, and 42 are adsorption cylinders each filled with an adsorbent (synthetic zeolite: molecular sieve) that selectively adsorbs _N2 , and each inlet thereof is equipped with valves 40b, 41b, and 42b. It is connected to the outlet of the discharge pipe 29 via inflow channels 40a, 41a, and 42a. 44 is a vacuum pump, which includes a suction path 43 and valves 40c, 41c,
It is connected to the inlets of the adsorption cylinders 40, 41, and 42 via 42c. 40d, 41d, 42d
are take-out passages connected to the outlets of the adsorption cylinders 40, 41, 42, respectively, and valves 40e, 40, respectively.
41e and 42e. These outlets 4
0d, 41d, 42d are product oxygen gas extraction passages 4
5 to a buffer tank 46. One of the adsorption cylinders 40, 41, 42 is used for adsorption, and the remaining one is the vacuum pump 4.
4, one of the regenerated pieces is used for adsorption, and the one that was previously performing the adsorption operation is subjected to the regeneration effect. Each of the above valves 40b, 40c, 40e, 41b, 41c, 41
e, 42b, 42c, and 42e are controlled to open and close by known valve control means (not shown), and the adsorption cylinder 40
The above operations of ~42 are realized. The above adsorption cylinder 40
42 repeats the above operation and performs 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, thereby preventing the supply of nitrogen gas from being interrupted. Make sure not to. 3
2 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 and 34a to release the product nitrogen gas to the outside as shown by arrow B. have the effect of Reference numeral 50 denotes a temperature sensor provided in the outlet pipe 24b, which detects the temperature of the nitrogen gas passing through the outlet pipe 24b, and controls the valve 51 provided in the inlet pipe 24a based on the detected temperature to perform heat exchange. The amount of liquid nitrogen supplied to the vessel 13 is controlled to keep the temperature of the nitrogen gas passing through the outlet pipe 24b constant. As a result, the temperature of the raw material compressed air introduced into the rectification column 15 via the heat exchanger 13 is kept constant, and stable rectification is performed at all times, resulting in a stabilizing effect on the purity of the product nitrogen gas. In addition, the effect of increasing the efficiency of liquid nitrogen consumption can be obtained. 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 cylinder 12, and the H ₂ in the air is removed. Adsorbs and removes O and _CO2 . Next, the compressed air from which H ₂ O and CO ₂ have been adsorbed and removed is sent to the heat exchanger 13 and transferred to the liquid nitrogen storage tank 23.
It is cooled to an ultra-low temperature by the cold heat of liquid nitrogen supplied from the reactor, and in that state is charged into the lower part of the rectification column 15. Then, this input compressed air is sent to the condenser 21a.
It is supplied to the liquid nitrogen reservoir 21d from the liquid nitrogen reservoir 21d and is cooled by contacting with the liquid nitrogen overflowing therefrom, and a part of it is liquefied and stored at the bottom of the rectification column 15. In this process, the difference between the boiling points of nitrogen and oxygen (boiling point of oxygen - 183
℃, the 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 27 and sent to the heat exchanger 13, 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 cold source for the heat exchanger 13, and is vaporized and taken out from the take-out pipe 27 as part of the product nitrogen gas via the outlet pipe 24b. On the other hand, the rectification column 15
The liquid air 18 accumulated in the lower part of the air is sent into the demultiplexer 21 to cool the condenser 21a, and then vaporized to become waste vaporized liquid air, which is then sent into the heat exchanger 13 through the discharge pipe 29. The temperature is raised, and in that state, the gas is sent to any one of the adsorption cylinders 40, 41, and 42, where the nitrogen gas is adsorbed and removed, and the gas is turned into oxygen gas and sent to the buffer tank 46.
In this case, any one of the adsorption cylinders 40, 41, and 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 Each valve 40b~
42b, 40c to 42c, and 40e to 42e are controlled by valve control means. 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 approximately 10:1.

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 has a demultiplexer 21 with a built-in condenser 21a in the upper part of the rectification column 15.
A part of the nitrogen gas generated in the rectification column 15 is constantly guided into the condenser 21a and liquefied, so that after a predetermined amount of liquefied nitrogen has accumulated in the condenser 21a, it is no longer produced. The liquefied nitrogen constantly returns to the rectification column 15 as a reflux liquid. Therefore, variations in product purity due to intermittent supply of reflux liquid from the condenser 21a (interruption of flow of reflux liquid causes liquid to run out in the upper rectifying shelf, causing gas blow-by phenomenon and reducing product purity). , the purity returns to a constant level when the flow resumes), and product nitrogen gas of stable purity can be supplied at all times. Furthermore, in this device, the pipe 51 is controlled by a temperature sensor 50 provided on the outlet pipe 24b, and the amount of liquid nitrogen supplied into the heat exchanger 13 is controlled, so that the amount of nitrogen gas passing through the outlet pipe 24b is controlled. In order to keep the temperature constant, the rectification column 1 is passed through a heat exchanger 13.
The temperature of the raw material compressed air introduced into 5 is kept constant at all times, making it possible to achieve stable rectification, which also greatly contributes to stabilizing the purity of the product nitrogen gas. Furthermore, this device produces oxygen gas from waste oxygen-rich liquid air that has passed through the rectification column 15 and has extremely low impurities, and can produce high-purity oxygen gas with one device. Nitrogen gas can be efficiently produced.

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. 3. That is,
This rectification column 15 has a partition plate 20 in which a large number of pipes 20a are installed, so that a dephlegmator section 21 is connected to a column section 22.
Liquid nitrogen is supplied from the liquid nitrogen storage tank 23 into this decentralizer section 21, and the pipe 19
The compressed air supplied into the rectification column 15 is cooled in the pipe 20a of the partition plate 20 to liquefy the oxygen content, and nitrogen is taken out in a gaseous state from the top of the dephlegmator section 21. There is. In this case, unlike the embodiment described above, the liquid air 18 accumulated at the bottom of the column section 22 of the rectification column 15 is used as a raw material for oxygen gas, heated in the heat exchanger 13, and vaporized into any desired state. It is supplied to adsorption cylinders 40, 41, and 42.

In some cases, as shown in Figure 1,
Temperature sensor 50 may be omitted.

〔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 does not have any 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 (removal of product nitrogen gas) It is difficult to perform fine-grained follow-up operation for changes in quantity. Therefore,
Accurately changes the amount of liquid air supplied to the expansion turbine according to changes in the amount of product nitrogen gas extracted,
It is difficult to constantly cool the compressed air, which is the raw material for nitrogen gas production, to a constant temperature, and as a result, the purity of the product nitrogen gas obtained varies, and low-purity products are frequently produced, resulting in the overall production of nitrogen gas purity was decreasing. 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 heat exchanger, making it possible to closely follow load fluctuations and maintain stable purity. It becomes possible to produce extremely strong nitrogen gas. Therefore, conventional purification equipment is not required. In particular, this equipment is equipped with a fractionator with a built-in condenser at the top of the fractionator, and a portion of the nitrogen gas generated in the fractionator is constantly introduced into the condenser inside the fractionator to liquefy it. The reflux liquid is liquefied, and the reflux liquid is constantly returned to the rectification column, and at the same time, the amount of liquid nitrogen supplied from the liquid nitrogen storage means to the heat exchange means is controlled by the control means, so that the nitrogen passing through the derivation path is controlled by the control means. In order to keep the gas temperature constant,
There is no variation in the purity of the product nitrogen gas. Moreover, this device is a device that collects nitrogen gas and then passes it through a rectification column, etc. to remove CO ₂ ,
Oxygen gas is produced by supplying oxygen-rich waste gas (waste vaporized liquid air) from which impurities such as H ₂ O have been removed from the nitrogen rectification column to the adsorption column, making it possible to efficiently obtain oxygen gas. can. As described above, the device of the present invention can efficiently produce high-purity nitrogen gas and oxygen gas with one device, so
Ideal for the electronic industry.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention without the temperature sensor, Fig. 2 is an explanatory diagram of a modification of the rectification column, and Fig. 3 is a block diagram of an embodiment of the present invention. be. 9... Air compressor, 12... Adsorption cylinder, 13...
Heat exchanger, 15...Nitrogen rectification column, 17...Pipe, 18...Liquid air, 21...Different condenser section, 21
a... Condenser, 21b... First reflux pipe,
21c... Second reflux liquid pipe, 21d... Liquid nitrogen reservoir, 23... Liquid nitrogen storage tank, 24a... Inlet pipe, 24b... Outlet pipe, 27...
Take-out pipe, 28...Main pipe, 29...Discharge path pipe, 40, 41, 42...Adsorption cylinder, 44
...Vacuum pump, 45...Product oxygen gas extraction path,
50...Temperature sensor, 51...Valve.

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 the liquefied nitrogen produced in the vessel as a reflux liquid into the rectification column, a liquid nitrogen storage means for receiving and storing liquid nitrogen from outside the apparatus, and a liquid nitrogen storage means inside the liquid nitrogen storage means. an introduction path that continuously leads the liquid nitrogen into the heat exchange means to replace the cold heat generated from the cold heat generating expander;
A nitrogen gas take-off passage for taking out the nitrogen gas generated in the rectification column as product nitrogen gas; and a nitrogen gas take-off passage for guiding the liquid nitrogen that has finished cooling and vaporized in the heat exchange means to the nitrogen gas take-off passage and converting it into product nitrogen gas. a control means for controlling the temperature of the nitrogen gas passing through the outlet path to a constant level by controlling the amount of liquid nitrogen supplied from the liquid nitrogen storage means to the heat exchange means; and a nitrogen gas selective adsorption device. a plurality of inlet pipes that communicate the inlets of the plurality of adsorption columns and the outlet of the discharge pipe in the demultiplexer, respectively;
A plurality of first on-off valves provided in each of the plurality of inlet pipes, an oxygen gas extraction path extending from the outlet of the plurality of adsorption cylinders, a regeneration means for the adsorption cylinder, a regeneration means and the plurality of A plurality of regeneration paths each communicating with the adsorption cylinders, a plurality of second on-off valves provided in each of the plurality of regeneration paths, and an arbitrary adsorption cylinder among the plurality of adsorption cylinders are activated to adsorb and A high-purity nitrogen gas production apparatus comprising an on-off valve control means for controlling the opening and closing of the first and second on-off valves so that the ivy adsorption column is regenerated or stopped.