JPH1163809A - Device and method for liquefying separation of air - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method for liquefying separation of air to improve the steadiness of rectification since control rapidly follows up the change of a liquid level of cold in a condenser, by regulating a feed amount of a liquefied product. SOLUTION: An air liquefying separation device comprises a main heat- exchanger 7 to cool compressed raw material air; a fractionating tower 9S having a fractionating part 13 to guide raw material air and separate it into an oxygen enriched component and a nitrogen enriched component, and a condenser 35S to partially condense the latter; and a liquid nitrogen storage tank 31S to feed liquid nitrogen through a feed valve V3. The air liquefying separation device comprises a transfer route 18 through which oxygen enriched liquid flowing from the fractionating part 13 to a bottom is transferred to the condenser 35S without storing the oxygen enriched liquid; a liquid level detecting means to detect the height of a liquid surface of the oxygen enriched liquid stored at the condenser 35S; and a control means LIC to control the opening of a feed valve V3 based on an outoute therefrom, such that the liquid surface of the oxygen enriched liquid stored in the condenser is kept approximately at a set liquid level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air liquefaction separation apparatus and method for separating raw air using a rectification column.

[0002]

2. Description of the Related Art Conventionally, as this type of air liquefaction / separation apparatus, a main heat exchanger that cools compressed, cooled, and impurity-free raw material air to near a liquefaction point, and guides the cooled raw material air are used. A rectification unit having a rectification unit that separates the oxygen-enriched component and the nitrogen component and a condenser that partially condenses the separated nitrogen component to obtain a reflux liquid, and supplies liquid nitrogen to the rectification column via a supply valve. There has been known an air liquefaction / separation apparatus including a liquid nitrogen storage tank for supplying a part of the reflux liquid and a cold source, and a cold supply path for supplying cold to the main heat exchanger.

In such an apparatus, for example, air taken in from the outside is compressed by a compressor, cooled by a refrigerator, and impurities such as carbon dioxide and water are removed by an adsorber or the like. Using a heat exchanger to cool the waste gas, etc. to near the liquefaction point, guide the cooled raw material air to the rectification tower, where the oxygen-enriched components and nitrogen While being separated into components, the separated nitrogen component is partially condensed by a condenser to form a reflux liquid, while liquid nitrogen is supplied from a liquid nitrogen storage tank via a supply valve as a part of the reflux liquid and as a cold source. By supplying the gas to the distillation tower, nitrogen gas was mainly produced.

[0004] In the above apparatus, the oxygen concentrate stored at the bottom of the rectification column is transferred to a condenser as cold, and stored in the condenser. Even in order to keep the rectification stationary in the rectification section,
In order to make the condensation capacity (cooling capacity) of the condenser installed above or outside the rectification tower almost constant, it is necessary to make the level of the oxygen concentrated liquid stored in the condenser almost constant. was there.

[0005] As a method for controlling the level of the cold in the condenser, the following method has been conventionally known. That is, Japanese Patent Publication No. 61-46747 discloses that the amount of liquefied air stored at the bottom of a rectification column is introduced into a condenser without adjusting the amount.
There has been proposed a method of adjusting a supply amount of a part of the reflux liquid and a supply amount of liquid nitrogen supplied as a cold source while detecting a cold liquid level in the condenser.

As a method similar to the above, Japanese Patent Application Laid-Open No. 64-54187 discloses a method of detecting the pressure of product nitrogen gas and condensing liquefied air (oxygen-enriched component) stored at the bottom of a rectification column. A method of adjusting the amount of liquefied air introduced into the condenser and the amount of product nitrogen gas has been proposed. However, such a method is intended to positively fluctuate the cold liquid level in the condenser to reduce the amount of product nitrogen gas consumed. Technology that responds to fluctuations in the
The condenser capacity (cooling capacity) of the condenser cannot be made almost constant.

[0007]

However, in the above-mentioned method, since the liquefied air is stored at the bottom of the rectification column, the supply amounts of a part of the reflux liquid and the liquid nitrogen supplied as the cold source are adjusted. However, the flow rate in the path leading from the bottom of the rectification column to the condenser hardly changes, and as a result, control cannot follow the change in the cold liquid level in the condenser, and the cold liquid in the condenser cannot be controlled. It was not possible to keep the rectification stationary by keeping the position almost constant. That is, the flow rate in the path for guiding the liquefied air from the bottom of the rectification tower to the condenser is determined by the pressure at the bottom of the rectification tower, the pressure in the condenser, the opening degree of a valve provided in the path therebetween, and the like. Therefore, according to the above control, the supply amount of liquid nitrogen is adjusted, and even if the amount of liquid air flowing down to the bottom of the rectification column changes due to the adjustment, the liquid air is stored at the bottom of the rectification column. Only the amount of stored liquefied air changes, and the flow rate in the path hardly changes, so that the refrigeration is not supplied enough to compensate for the change in the refrigeration level in the condenser. As a result, the control cannot follow the change in the liquid level of the cold inside the condenser, and in extreme cases, the cold inside the condenser may become empty or full.

On the other hand, in the case of producing oxygen gas, an apparatus using a double rectification column, that is, a medium pressure rectifier for conducting cooled raw material air similar to that described above to separate it into an oxygen-enriched component and a nitrogen component. Medium-pressure rectification column having a condenser and a condenser that condenses the separated nitrogen component to obtain a reflux liquid, and a part of the reflux liquid of the medium-pressure rectification tower is guided through an expansion valve to obtain a reflux liquid. A low-pressure rectification section that conducts an oxygen-enriched component from the bottom of the medium-pressure rectification column to separate it into an oxygen component and a nitrogen component while cooling the condenser that permits the inflow of the oxygen component from the low-pressure rectification portion An air having a low-pressure rectification column having a storage section, a liquid oxygen storage tank for supplying liquid oxygen to the cold storage section via a supply valve, and a cold supply path for supplying cold to the main heat exchanger. A liquefaction separation device is mainly used, but regarding the condenser of the medium pressure rectification column , Said the same problem is likely to occur.

Accordingly, an object of the present invention is to control the supply of liquefied products and the like in view of the above-mentioned drawbacks, so that the control can quickly follow the change in the cold liquid level in the condenser. An object of the present invention is to provide an air liquefaction / separation apparatus and an air liquefaction / separation method that can enhance the stationarity.

[0010]

A first feature of the present invention to achieve this object is to provide a main heat exchanger for cooling compressed, cooled, and impurity-free raw material air to near a liquefaction point, A rectification unit having a condenser that guides the cooled raw material air to separate it into an oxygen-enriched component and a nitrogen component and a condenser that partially condenses the separated nitrogen component to obtain a reflux liquid,
Air liquefaction comprising a liquid nitrogen storage tank for supplying liquid nitrogen to the rectification column via a supply valve as a part of the reflux liquid and a cold source, and a cold supply path for supplying cold to the main heat exchanger. In the separation device, the oxygen-concentrated liquid flowing down from the rectifying section to the bottom of the rectification tower is stored in the condenser without being stored in the bottom of the rectification tower, and is transferred to the condenser in a cold state. Liquid level detecting means for detecting the level of the liquid level of the oxygen-concentrated liquid, and the liquid level of the oxygen-concentrated liquid stored in the condenser is substantially set based on the output from the liquid level detecting means. Control means for controlling the opening of the liquid nitrogen supply valve so that the liquid level is maintained.

[0011] A second feature of the present invention is compression,
Cooling and cooling the raw material air from which impurities have been removed to near the liquefaction point in the main heat exchanger, guide the cooled raw material air to the rectification column, and oxygen concentration components in the rectification section in the rectification column. While being separated into a nitrogen component, the separated nitrogen component is partially condensed by a condenser to obtain a reflux liquid, while liquid nitrogen is supplied as a part of the reflux liquid and a cold source from a liquid nitrogen storage tank via a supply valve. By supplying to the rectification column, in the air liquefaction and separation method for producing product nitrogen gas, without storing the oxygen concentrate flowing down from the rectification section to the bottom of the rectification column at the bottom of the rectification column, While transferring to the condenser as cold,
While detecting the level of the liquid level of the oxygen concentrated liquid stored in the condenser with a liquid level detecting means, based on the output from the liquid level detecting means, the oxygen concentrated liquid stored in the condenser is detected. Is to control the opening of the liquid nitrogen supply valve so that the liquid level of the liquid nitrogen is kept substantially at the set liquid level.

The third feature of the present invention is that compression, cooling,
A main heat exchanger that cools the raw material air from which impurities have been removed to near the liquefaction point, a medium-pressure rectification section that guides the cooled raw material air to separate it into an oxygen-enriched component and a nitrogen component, and a separated nitrogen component And a medium-pressure rectification column having a condenser that is used as a reflux liquid by condensing the medium-pressure rectification tower. A low-pressure rectification column having a low-pressure rectification unit that guides an oxygen-enriched component from the bottom to separate it into an oxygen component and a nitrogen component, and a cold storage unit of the condenser that allows the inflow of the oxygen component from the low-pressure rectification unit A liquid oxygen storage tank for supplying liquid oxygen to the cold storage unit via a supply valve, and a cold supply path for supplying cold to the main heat exchanger. Guide oxygen-enriched components from the bottom of the rectification column to the low-pressure rectification column A feed path, a transfer path for transferring the oxygen-concentrated liquid flowing down to the bottom without being stored in the bottom, and a liquid level detecting means for detecting the height of the cold liquid level stored in the cold storage unit; Controlling the opening degree of the liquid oxygen supply valve based on the output from the liquid level detecting means so that the level of the cold liquid stored in the cold storage section is maintained substantially at the set liquid level. Control means.

A fourth feature of the present invention is that compression, cooling,
The raw material air from which impurities have been removed is cooled to near the liquefaction point in the main heat exchanger, and the cooled raw material air is guided to a medium-pressure rectification column, where it is passed through a medium-pressure rectification section. While separating the oxygen-enriched component and the nitrogen component, the separated nitrogen component is condensed in a condenser to obtain a reflux liquid, and a part of the reflux liquid is used as a reflux liquid in a low-pressure rectification section via an expansion valve. While conducting, the oxygen-enriched component is guided from the bottom of the medium-pressure rectification column and separated into an oxygen component and a nitrogen component in the low-pressure rectification unit. In the air liquefaction separation method for producing product oxygen gas by supplying liquid oxygen from a liquid oxygen storage tank to a cold storage unit via a supply valve while flowing into the storage unit, the intermediate pressure rectification unit The oxygen concentrate flowing down to the bottom of the rectification column is stored at the bottom of the medium-pressure rectification column. Instead, after being transferred to the low-pressure rectification section and rectified and introduced into the cold storage section of the condenser as cold, the height of the cold liquid level stored in the cold storage section is measured by liquid level detection means. While detecting, based on the output from the liquid level detecting means, the opening degree of the liquid oxygen supply valve is adjusted so that the cold liquid level stored in the cold storage section is maintained at substantially the set liquid level. The point is to control.

According to the first feature of the present invention, the oxygen concentrate flowing down from the rectification section to the bottom of the rectification tower is not stored at the bottom of the rectification tower.
Since the condenser is provided with a transfer path for transferring the liquid in a cold state, the control unit controls the liquid based on the output from the liquid level detection unit that detects the height of the liquid level of the oxygen concentrated liquid stored in the condenser. By controlling the opening degree of the liquid nitrogen supply valve, the amount of the oxygen-enriched component flowing down to the bottom of the rectification column is adjusted by the control, and it is immediately transferred to the condenser. The cold liquid level can be adjusted quickly. As a result, by adjusting the supply amount of liquefied products, etc., the control can quickly follow the change in the cold liquid level in the condenser, so that an air liquefaction separation device capable of improving the rectification steadiness is provided. We were able to.

According to a second feature of the present invention,
The oxygen concentrated liquid flowing down from the rectification section to the bottom of the rectification tower without being stored at the bottom of the rectification tower, is transferred to the condenser as cold, and the oxygen concentrated liquid stored in the condenser is stored. While detecting the liquid level height by the liquid level detection means,
The opening degree of the liquid nitrogen supply valve is controlled based on the output from the liquid level detecting means so that the liquid level of the oxygen concentrated liquid stored in the condenser is kept substantially at the set liquid level. Therefore, the same operation as described above can be obtained. as a result,
It is possible to provide an air liquefaction / separation method capable of improving the rectification steadiness because the control can quickly follow the change in the cold liquid level in the condenser by adjusting the supply amount of the liquefied product or the like. did it.

According to a third feature of the present invention,
Since the transfer path for guiding the oxygen-enriched component from the bottom of the medium-pressure rectification tower to the low-pressure rectification tower is a transfer path for transferring the oxygen-concentrated liquid flowing down to the bottom without storing it in the bottom, Similarly, since the oxygen concentrate flowing down to the bottom can be immediately led to the low-pressure rectification column, the amount of the cold supply into the double rectification column can be controlled by controlling the opening of the liquid oxygen supply valve by the control means. Rectification, the rectification can be made more consistent. As a result, by adjusting the supply amount of liquid oxygen, control can quickly follow a change in the liquid level of the cold in the condenser, and therefore, an air liquefaction / separation apparatus capable of improving the rectification steadiness is provided. I was able to.

According to a fourth feature of the present invention,
The oxygen-concentrated liquid flowing down from the intermediate-pressure rectification section to the bottom of the medium-pressure rectification tower is not stored in the bottom of the medium-pressure rectification tower, but is transferred to the low-pressure rectification section and the rectifier after the rectification. While being introduced into the cold storage section as cold, while detecting the height of the cold liquid level stored in the cold storage section with liquid level detection means, based on the output from the liquid level detection means, Since the opening of the liquid oxygen supply valve is controlled so that the level of the cold liquid stored in the cold storage unit is maintained substantially at the set liquid level, the same effect as described above can be obtained. As a result, by adjusting the supply amount of liquid oxygen, the control can quickly follow the change in the liquid level of the cold inside the condenser, and therefore, an air liquefaction separation method capable of improving the rectification steadiness is provided. I was able to.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. Since the present invention has the first to fourth feature configurations as described above, the first embodiment corresponding to the first and second feature configurations, and the third feature configuration And the second embodiment corresponding to the fourth characteristic configuration will be described separately.

[First Embodiment] As shown in FIG. 1, air in the atmosphere is taken into a compressor 1 through a filter (not shown) and compressed by a compressor 1 to 9 kg / cm ² G. After passing through a refrigerator (Freon refrigerator) 3 and preliminarily cooled to about 5 ° C. by the refrigerator 3, it is introduced into one adsorption column 5 a of a pre-purifier 5 through a pipe 4. In the adsorption cylinder 5a, carbon dioxide, water, and the like in the compressed raw material air are removed (depending on the apparatus, hydrocarbons can be removed), and introduced into the main heat exchanger 7 through the pipe 6. At this time, regeneration of the other adsorption column 5b of the pre-purifier is performed by waste gas introduced through the pipe 27 as described later.
The switching of b is performed by the switching valve VC.

The raw air introduced into the main heat exchanger 7 exchanges heat with nitrogen gas and waste gas, which will be described later, and is cooled to near the liquefaction point. Then, the cooled raw material air is supplied to the pipe 8
, Is introduced into the lower space 11S of the rectification tower 9S and rises.

On the other hand, above the rectification section 13 of the rectification tower 9S, liquid nitrogen is introduced as described later, and the gas which has risen in the rectification tower 9S is liquefied in a condenser 35S, and is condensed with a reflux liquid. The rectification unit 13 flows down to the rectification unit 13 and is rectified in gas-liquid contact with the ascending gas. Fractionation of nitrogen component).

The oxygen-enriched liquefied air that flows down to the bottom of the rectification column 9S is not stored at the bottom of the rectification column.
With a small amount of air (i.e., with less than twice the volume of oxygen-enriched liquefied air, preferably less than 10%), it is drawn into line 18 and about 1.9 kg / cm ² G by orifice V2. After being inflated to
It is introduced into the cold storage part of the condenser 35S. That is, without storing the oxygen concentrated liquid flowing down from the rectifying section 13 to the bottom of the rectification tower 9S at the bottom of the rectification tower, the condenser 35
Although the transfer path for transferring the cold to S is constituted by the pipe 18 and the orifice V2, the transfer path may be constituted by a valve which is sufficiently opened or by adjusting the pressure loss of the pipe 18 itself.

Then, the nitrogen gas at the top of the rectification tower 9S is introduced into the main heat exchanger 7 through the pipe 29, and is vaporized by the nitrogen gas of the rectification tower 9S in the oxygen concentrated liquid stored in the condenser 35S. The oxygen-enriched air (waste gas) thus collected is introduced into the main heat exchanger 7 through the pipe 24. The nitrogen gas and the waste gas are heat-exchanged with the compressed raw air in the main heat exchanger 7, respectively. Then, the nitrogen gas is taken out as a product nitrogen gas (GN ₂ ) at room temperature at a pressure of about 8.7 kg / cm ² G through the pipe 30, and the waste gas is passed through the pipe 27 at about 1.7 kg / cm 2 ^{At a} normal temperature at a pressure of ² G, the temperature is sent to the adsorption column 5b of the pre-purifier 5 to be regenerated, and as described above, it is used for extracting carbon dioxide, water, etc. as the regeneration gas of the adsorption column 5b.

Further, the total cooling heat required in the cool box 36 including the rectification tower is introduced from the outside into the liquid nitrogen storage tank 31S and is supplied by the stored liquid nitrogen (LN ₂ ). , Is taken out through the pipe 32, and the liquid level of the condenser 35S of the rectification column 9S is maintained at a set liquid level.
The liquid is introduced above the rectification section 13 of the rectification tower 9S while the opening of the valve V3 is adjusted by the liquid level display control device LIC as a control means. That is, a liquid level detecting means (not shown) for detecting the level of the liquid level of the oxygen concentrated liquid stored in the condenser 35S is provided, and the condensation is performed based on the output from the liquid level detecting means. The opening degree of the liquid nitrogen supply valve V3 is controlled so that the liquid level of the oxygen concentrated liquid stored in the vessel 35S is kept substantially at the set liquid level.

Further, when the nitrogen demand exceeds the production capacity of the rectification column 9S, the liquid nitrogen is led out through the pipe 34 extending from the lower part in the liquid nitrogen storage tank 31S, and is vaporized by the evaporator 33a. 8.5kg / with valve V4
The pressure is adjusted to cm ² G and introduced into the pipe 30.

A pipe 37 branched from the pipe 34 has an evaporator 33b and a pressure control valve V5 inserted therein, and is returned to the top of the liquid nitrogen storage tank 31S.
The pressure of S is maintained at a predetermined pressure.

The pipe 40 and the valve V6 are provided for discharging the oxygen concentrate in the condenser 35S if necessary, and when hydrocarbons are concentrated in the oxygen concentrate by continuing operation of the apparatus. Part or all of such oxygen concentrate can be drained. In addition, the cool box 36 shown by the dotted line is the main heat exchanger 7 and the rectification tower 9 constituting the low-temperature equipment.
S, a cold box (insulated container) for storing the liquid nitrogen storage tank 31S and the like.

[Second Embodiment] As shown in FIG. 2, air in the atmosphere is introduced into a compressor 1 through a filter (not shown) and compressed by the compressor 1 to 9 kg / cm ² G. After passing through a refrigerator (Freon refrigerator) 3 and preliminarily cooled to about 5 ° C. by the refrigerator 3, it is introduced into one adsorption column 5 a of a pre-purifier 5 through a pipe 4. In the adsorption cylinder 5a, carbon dioxide, water, and the like in the compressed raw material air are removed (depending on the apparatus, hydrocarbons can be removed), and introduced into the main heat exchanger 7 through the pipe 6. At this time, regeneration of the other adsorption column 5b of the pre-purifier is performed by waste gas introduced through the pipe 27 as described later.

The raw material air introduced into the main heat exchanger 7 exchanges heat with oxygen gas, nitrogen gas and waste gas, which will be described later, and is cooled to near the liquefaction point. Then, the cooled raw material air is introduced into the lower space 10 of the intermediate pressure rectification tower 11 of the double rectification tower 9 via the pipe 8 and rises.

On the other hand, liquid oxygen is introduced from the liquid oxygen storage tank 31 to the bottom of the low-pressure rectification tower 12 of the double rectification tower 9 through the pipe 32 and the pressure reducing valve V3, and the gas (the gas) ascending the medium-pressure rectification tower 11 The nitrogen component) is liquefied in the main condenser 35, flows down to the rectification section 13 as a reflux liquid, is rectified by gas-liquid contact with the ascending gas, and is oxygen-enriched in the lower part of the medium pressure rectification column 11. Liquefied air (oxygen-enriched component) is caused to flow down, and nitrogen gas is rectified and separated at the top.

The oxygen-enriched liquefied air (oxygen-enriched component) that flows down to the bottom of the intermediate-pressure rectification column 11 is not stored at the bottom of the medium-pressure rectification column, but with a small amount of air (ie, oxygen-enriched component). Less than twice the volume of liquid air,
Line 18 (preferably with less than 10% air)
And about 1.9 kg / by the orifice V2
After being expanded to cm ² G, it is introduced into the space 23 between the first upper rectification section 14A and the second upper rectification section 14B of the low-pressure rectification column 12. That is, the oxygen-concentrated liquid flowing down to the bottom is stored in the bottom through the pipe 18 and the orifice V2 through the transfer path for guiding the oxygen-enriched component from the bottom of the medium-pressure rectification column 11 to the low-pressure rectification column 12. It is a transfer route to transfer without. However, similarly to the first embodiment, the transfer path may be configured by a valve that is sufficiently opened or by adjusting the pressure loss of the pipe 18 itself.

At the top of the intermediate pressure rectification column 11, nitrogen gas which is rectified through the rectification section 13 of the medium pressure rectification column 11 and rises is stored. At the top, a part of the nitrogen gas is liquefied in the main condenser 35 and a part thereof is used as a reflux liquid in the medium pressure rectification column 1.
3, the reflux liquid is rectified by gas-liquid contact with the air rising in the medium pressure rectification section 13. On the other hand, the remainder of the liquid nitrogen is stored in the liquid nitrogen storage unit 20 of the medium pressure rectification column 11, passes through the pipe 21, and is supplied to the expansion valve V1 at about 1.8 kg / c.
After being expanded to m ² G, it is led to the space 22 above the first upper rectification section 14A of the low-pressure rectification tower 12.

The waste gas (nitrogen component) at the top of the low-pressure rectification tower 12 was introduced into the main heat exchanger 7 through the pipe 24 and stored in the main condenser 35 at the bottom of the low-pressure rectification tower 12. Among the liquid oxygen (cold), the oxygen gas vaporized by the nitrogen gas in the medium pressure rectification column 11 is introduced into the main heat exchanger 7 through the pipe 25. The oxygen gas and the waste gas are heat-exchanged with the compressed raw material air in the main heat exchanger 7, respectively. Then, the oxygen gas passes through the pipe 26 to about 2 kg /
At a pressure of ² cm ² G, it is taken out as product oxygen gas (GO ₂ ) at room temperature, and the waste gas passes through a pipe 27 to about 1.8 kg /
The temperature becomes room temperature at a pressure of ² cm ² G and is sent to the adsorption column 5b of the pre-purifier 5 to be regenerated, as described above.
It is used to take out carbon dioxide, water, etc. as a regenerated gas.

When nitrogen gas is required at the same time, nitrogen gas is supplied from the upper part of the rectification section 13 of the medium pressure rectification column 11 to the pipe 2.
9, after being taken out at a pressure of about 8.7 kg / cm ² G and subjected to heat exchange with the raw air in the main heat exchanger 7,
The product is extracted through a pipe 30 as a product nitrogen gas (GN ₂ ) at room temperature.

Further, a cool box 36 containing the double rectification column 9
The total cooling energy required inside is introduced into the liquid oxygen storage tank 31 from the outside, and is covered by the stored liquid oxygen (LO ₂ ). The liquid oxygen is taken out through a pipe 32 and is supplied to the low-pressure rectification column 12. In order to keep the liquid level at the bottom at the set liquid level, the valve V is controlled by a liquid level display control device LIC which is a control means.
3 is introduced into the bottom of the low-pressure rectification column 12 while the opening degree is adjusted. That is, a liquid level detecting means (not shown) for detecting the level of the cold liquid stored in the cold storing section is provided, and the cold storing section is provided with the output from the liquid level detecting means. The opening of the liquid oxygen supply valve V3 is controlled so that the level of the stored cold liquid is substantially maintained at the set liquid level.

Further, when the oxygen demand exceeds the production capacity of the double rectification column 9, the liquid oxygen is led out through the pipe 34 extending from the lower part in the liquid oxygen storage tank 31 and is vaporized by the evaporator 33a. 2kg / cm ² G by valve V4
, And introduced into the pipe 26. In addition, piping 3
The pipe 37 branched from 4 is connected to the evaporator 33b and the pressure control valve V
5 is inserted and returned to the top of the liquid oxygen storage tank 31 to maintain the pressure of the liquid oxygen storage tank 31 at a predetermined pressure.

[Another Embodiment] Another embodiment will be described below. (1) In the above embodiment, the example in which the condenser is arranged inside the tower is shown, but the condenser may be arranged outside the tower.

(2) In the above embodiment, an example is shown in which the control means is constituted by an LIC integrated with the liquid level detection means. However, the control means is constituted separately from the liquid level detection means. It may be.

(3) The temperature and the temperature shown in the above description
The pressure and the like are examples in the case of carrying out the present invention, and are not limited to the above numerical values because they vary depending on the design and operating conditions of various device parts.

(4) In the above embodiment, an example was shown in which the liquefied product storage tank was arranged in a cool box in which the rectification tower was arranged. However, the liquefied product storage tank was arranged outside the cool box in which the rectification tower was arranged. In that case, it is arranged in another cool box.

(5) In the above embodiment, the oxygen concentrate flowing down the bottom of the rectification column is easily flowed toward the pipe.
Although the bottom is formed in an inverted conical shape, a guide groove capable of forming a flow path may be provided in order to further enhance the fluidity of the oxygen concentrated liquid.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of an air liquefaction separation device according to a first embodiment.

FIG. 2 is a schematic configuration diagram illustrating an example of an air liquefaction separation device according to a second embodiment.

[Explanation of symbols]

 7 Main heat exchanger 9 Double rectification tower 9S rectification tower 11 Medium pressure rectification tower 12 Low pressure rectification tower 13 Rectification section 18 Piping (transfer route) 31 Liquid oxygen storage tank 31S Liquid nitrogen storage tank 35 Main condenser 35S Condenser V1 Expansion valve V2 Orifice (transfer path) V3 Supply valve LIC Liquid level display control device (control means)

Claims (4)

[Claims] 1. A main heat exchanger for cooling compressed, cooled, and impurity-free raw material air to near a liquefaction point, and a rectifier for guiding the cooled raw material air to separate it into an oxygen-enriched component and a nitrogen component. Column and a condenser having a condenser that partially condenses the separated nitrogen component to obtain a reflux liquid, and supplies liquid nitrogen to the rectification tower as a part of the reflux liquid and a cold source via a supply valve A liquid nitrogen storage tank, and an air liquefaction / separation device including a cold supply path for supplying cold to the main heat exchanger, wherein the oxygen-concentrated liquid flowing down from the rectifying section to the bottom of the rectifying tower is provided. A transfer path for transferring to the condenser as cold without storing at the bottom of the rectification column, and a liquid level detecting means for detecting a liquid level of the oxygen concentrated liquid stored in the condenser, Based on the output from the liquid level detecting means, it is stored in the condenser. An air liquefaction / separation apparatus comprising: control means for controlling an opening degree of the liquid nitrogen supply valve so that the liquid level of the oxygen concentrated liquid to be retained is substantially maintained at a set liquid level. 2. The raw material air from which compression, cooling, and impurities have been removed is cooled by a main heat exchanger to near a liquefaction point, and the cooled raw material air is guided to a rectification column, and the rectification in the rectification column is performed. While separating the oxygen-enriched component and the nitrogen component in the distillation section, the separated nitrogen component is partially condensed by a condenser to obtain a reflux liquid,
An air liquefaction separation method for producing product nitrogen gas by supplying liquid nitrogen to the rectification tower as a part of the reflux liquid and a cold source from a liquid nitrogen storage tank via a supply valve, and comprising: The oxygen concentrated liquid flowing down to the bottom of the rectification tower is transferred to the condenser as cold without storing in the bottom of the rectification tower, and the level of the liquid level of the oxygen concentrated liquid stored in the condenser is increased. While detecting the liquid level by the liquid level detecting means, based on the output from the liquid level detecting means, so that the liquid level of the oxygen concentrated liquid stored in the condenser is kept substantially at the set liquid level. An air liquefaction separation method for controlling the opening of a liquid nitrogen supply valve. 3. A main heat exchanger for cooling the compressed, cooled, and impurity-removed raw material air to near a liquefaction point, and a medium pressure for guiding the cooled raw material air to separate it into an oxygen-enriched component and a nitrogen component. A medium-pressure rectification column having a rectifying section and a condenser for condensing the separated nitrogen component to obtain a reflux liquid, and a part of the reflux liquid of the medium-pressure rectification tower being led through an expansion valve to obtain a reflux liquid A low-pressure rectification section that guides an oxygen-enriched component from the bottom of the medium-pressure rectification column to separate it into an oxygen component and a nitrogen component, and the condenser that allows the inflow of the oxygen component from the low-pressure rectification portion. A low-pressure rectification column having a cold storage unit, a liquid oxygen storage tank that supplies liquid oxygen to the cold storage unit via a supply valve, and a cold supply path for supplying cold to the main heat exchanger are provided. An air liquefaction / separation apparatus, wherein the low pressure is applied from the bottom of the medium pressure rectification column. A transfer path that guides the oxygen-enriched component to the distillation tower, a transfer path that transfers the oxygen-concentrated liquid flowing down to the bottom without storing it in the bottom, and the height of the cold liquid level stored in the cold storage unit. Liquid level detection means for detecting the liquid level of the liquid oxygen based on an output from the liquid level detection means so that the cold liquid level stored in the cold storage section is maintained at a substantially set liquid level. Control means for controlling the opening of the supply valve. 4. The raw material air from which compression, cooling and impurities have been removed is cooled by a main heat exchanger to near a liquefaction point, and the cooled raw material air is guided to a medium-pressure rectification column, where the medium-pressure rectification is performed. While separating the oxygen-enriched component and the nitrogen component in the medium-pressure rectification section in the column, the separated nitrogen component is condensed by a condenser to obtain a reflux liquid, and a part of the reflux liquid is passed through an expansion valve. While conducting as a reflux of the low-pressure rectification section, the oxygen-enriched component is guided from the bottom of the medium-pressure rectification column to separate the oxygen component and the nitrogen component in the low-pressure rectification section, and from the low-pressure rectification section An air liquefaction separation method for producing product oxygen gas by supplying liquid oxygen from a liquid oxygen storage tank to a cold storage unit via a supply valve while flowing the oxygen component into the cold storage unit of the condenser. The oxygen concentrate flowing down from the medium pressure rectification section to the bottom of the medium pressure rectification column is Without being stored at the bottom of the pressure rectification tower, it is transferred to the low-pressure rectification section, and after rectification, introduced into the cold storage section of the condenser as cold, and the cold liquid level stored in the cold storage section While detecting the height of the liquid level detection means, based on the output from the liquid level detection means, so that the cold liquid level stored in the cold storage unit is maintained at substantially the set liquid level, An air liquefaction separation method for controlling an opening of a supply valve of the liquid oxygen.