JPH1054656A - Air liquefying and separating device and method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit re-starting easily within a short period of time after temporarilly stopping a device. SOLUTION: A liquid flowing-down means constituted of a liquid receiver 25, which receives flowing liquid and is provided below respective fractionating units F1-F6 defined by dividing the fractionating unit of a fractionating tower 21 into a plurality of divisions in vertical directions, a liquid flowing-down pipe 26, through which the liquid received by the liquid receiver 25 flows down, and a valve 27 for controlling the flow of liquid of the liquid flowing-down pipe 26, is provided. Upon stopping operation, the valve 27 is closed to retain the flowing-down liquid in the respective liquid flowing-down means.

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, and more particularly, to an industrial field in which the demand for separated product gas such as oxygen fluctuates day and night or weekdays.
Metal melting electric furnace, iron and steel making equipment, oxygen combustion power generation equipment,
The present invention relates to an air liquefaction / separation apparatus for supplying a product gas to a semiconductor manufacturing facility or the like and a method thereof.

[0002]

2. Description of the Related Art When an air liquefaction / separation apparatus is installed for an equipment having a large fluctuation in demand for product gas, the fluctuation in the demand for the product gas is reduced by an air liquefaction / separation apparatus. If there is no demand or there is little demand, reduce the amount of operation and release the excess production.If there is no demand for product gas, shut down the equipment and restart the operation. A method of restarting early according to the time required for startup, or liquefying and storing the excess when the demand for product gas is low, and vaporizing and using the stored liquefied gas when the demand for product gas increases Has been responded by such methods.

[0003] However, in the method of releasing the product gas of the over-produced amount, the amount of the released gas is lost. In the method of performing the restart earlier, the product gas of a predetermined purity is obtained after the restart. Since it takes a long time, the power during that time is lost. Further, in the case of the method of liquefying and storing, there is a problem that additional equipment such as a liquefier and a storage tank is required, and in any case, there is a problem in terms of economy.

Among these demand fluctuation measures, the method of shutting down the apparatus when there is no demand for product gas does not require a power cost during that time, so that there is no demand for product for a relatively long time, This is effective for devices that are small and have a relatively short startup time.However, in the case of large devices that require a long time to start, or in the case of short-term demand fluctuations, the proportion of time required for restarting is large. Was rarely adopted.

Here, the reason why the startup time of the air liquefaction / separation apparatus is long will be described with reference to FIG. FIG. 9 shows an example of a general air liquefaction and separation apparatus using a double rectification column. First, raw material air compressed to a predetermined pressure by an air compressor 1 is passed through an aftercooler 2 to an adsorption facility 3. After the impurities such as moisture and carbon dioxide contained in the raw material air are adsorbed and removed by the adsorption equipment 3 and purified, the impurities are introduced into the main heat exchanger 4 and cooled.

Most of the raw material air which has been cooled to near the liquefaction point by performing heat exchange with the product gas and the like led out in the main heat exchanger 4, is mostly supplied from the pipe 5 to the lower part of the lower column 7 of the double rectification column 6. Will be introduced. From the middle part of the main heat exchanger 4, a part of the raw air cooled to the intermediate temperature is extracted to the pipe 8, adiabatically expanded by the expansion turbine 9 to generate cold, and then passes through the pipe 10. It is introduced into the middle part of the upper column 11 of the double rectification column 6.

The raw air introduced into the lower column 7 is separated into nitrogen gas at the top of the column and oxygen-enriched liquefied air at the bottom of the column by a rectification operation in the lower column. Pipe 1 from bottom of lower tower
The oxygen-enriched liquefied air extracted in 2 is introduced into the middle and upper part of the upper tower 11 via the subcooler 13 and the pressure reducing valve 14,
It becomes the reflux liquid of 1. The nitrogen gas in the upper part of the lower tower is condensed and liquefied in the main condenser evaporator 15 to become liquefied nitrogen, and a part thereof is introduced into the top of the lower tower by a pipe 16 to become a reflux liquid of the lower tower 7, and the remaining liquefied nitrogen Is the supercooler 1 from the pipe 17
3, introduced into the top of the upper tower via the pressure reducing valve 18,
It becomes the reflux liquid of 1.

[0008] The raw material air, oxygen-enriched liquefied air and liquefied nitrogen introduced from the pipes 10, 12, and 17, respectively, are subjected to a rectification operation in the upper column to produce nitrogen gas at the top of the column and liquefied oxygen at the bottom of the column. To separate. The nitrogen gas at the top of the tower is
From the subcooler 13 and the main heat exchanger 4. The liquefied oxygen at the bottom of the tower evaporates and evaporates into oxygen gas by heat exchange with the nitrogen gas at the upper part of the lower tower in the main condensing evaporator 15, and a part of the gas rises in the upper tower and rises in the upper tower 11. Then, the remaining oxygen gas is extracted to the pipe 20 and is raised to normal temperature in the main heat exchanger 4 and is led out.

The rectification column of such an air liquefaction separation device is
It has a rectification part F for performing gas-liquid contact inside,
In the rectifying section F, the gas that rises (the rising gas) comes into contact with the liquid that flows down (the reflux liquid), whereby the gas components are rectified. The composition of the gas and liquid in the rectification tower during operation is such that the upper part of the tower is rich in the nitrogen component and the lower part is rich in the oxygen component in both the upper and lower towers.

In this state, when the air compressor 1 is stopped to stop the apparatus, the introduction of air from the pipe 5 in the lower tower 7 is stopped, so that gas rising in the rectification section F disappears, and The liquid that has been condensed in the condensing evaporator 15 and has been returned to the rectification unit F is lost, and the liquid flowing down each rectification unit F flows down to the bottom of the lower tower as it is due to gravity. In addition, in the upper column 11, the evaporation of the liquefied oxygen in the main condensing evaporator 15 is stopped by stopping the lower column 7, and the pressure reducing valves 14, 18 are closed to stop the introduction of the reflux liquid. The liquid flowing down each rectification section flows down to the bottom of the column. That is, when the apparatus is stopped, a liquid rich in the nitrogen component at the top of the column and a liquid rich in the oxygen component at the bottom of the column are mixed and stored at the bottom of each rectification column.

When the air compressor 1 is started to restart the apparatus and the introduction of the raw material air is started, the raw material air introduced into the lower tower 7 rises in the lower tower and moves to the main condensing evaporator 15.
And exchanges heat with the liquid at the bottom of the upper column present in the main condensing evaporator 15 to liquefy and flow down in the lower column.
As a result, the rectification in the lower tower starts, and gas evaporated by heat exchange with the raw material air in the main condensing evaporator 15 rises in the upper tower, and flows from the lower tower 7 via the pipes 12 and 17 to the upper tower 1.
Rectification with the liquid flowing into 1 starts.

However, at the time of this restart, all the liquid in each rectification section F flows down to the bottom of the tower when the apparatus is stopped, and is in a mixed state, and the composition distribution of the entire rectification tower is eliminated. In this case, the composition distribution of each rectifying section F was reformed, and it was necessary to wait until the rectifying operation using the ascending gas having a predetermined composition and the reflux liquid started. For example, since the liquid at the bottom of the upper tower becomes a mixed liquid of liquefied oxygen and liquefied nitrogen when the apparatus is stopped, in order to collect oxygen gas of a predetermined purity as a product, nitrogen contained in the liquid at the bottom of the upper tower is required. It is necessary to wait until the liquid has evaporated almost completely and the flowing liquid contains almost no nitrogen.

Accordingly, in the conventional air liquefaction / separation apparatus, when the apparatus is stopped, a large amount of liquid having a completely different composition flows down and accumulates at the bottom of the rectification column.
This large amount of liquid had to be redistributed to the rectification section and the composition distribution had to be reformed, and this operation required a long time.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an air liquefaction separation apparatus and method capable of easily restarting after temporarily stopping the apparatus in a short time.

[0015]

In order to achieve the above object, an air liquefaction / separation apparatus according to the present invention comprises an air liquefaction / separation column having a rectification column for cryogenic liquefaction / separation of compressed, purified and cooled raw material air. In the apparatus, the rectification section of the rectification tower is divided into a plurality of parts in the vertical direction, and at least one of the divided rectification sections is provided.
A liquid flowing-down means for flowing the flowing liquid down to the lower rectifying section is provided below the rectifying section at a location, and a liquid capable of holding the flowing liquid by preventing the flowing-down liquid from flowing down. It is characterized in that a holding means is provided. The rectification means in each rectification section is characterized in that at least a part thereof is a structured packing material.

Further, the air liquefaction separation method of the present invention is directed to an air liquefaction separation method in which compressed, purified and cooled raw material air is introduced into a rectification column to perform cryogenic liquefaction rectification and separation. Is divided into a plurality of parts in the vertical direction, and at the time of operation, in at least one of the divided rectification sections, the flowing liquid flows down to the lower rectification section via the liquid flow-down means. At the time of stoppage, the downflow of the downflow liquid is prevented by each of the downflow means, and the downflow liquid is held in each of the downflow means.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings. First, FIG. 1 shows a first embodiment of the air liquefaction / separation apparatus of the present invention. In the air liquefaction / separation apparatus according to the present embodiment, the configuration other than the rectification column can be the same as that of the conventional apparatus shown in FIG. 9, and illustration of parts other than the rectification column is omitted. Also, the same components as those of the above-described conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted.

The rectification column 21 shown in this embodiment is a lower column 2
2, a double rectification column having an upper tower 23 and a main condensing evaporator 24, wherein the lower tower 22 and the upper tower 23 have rectification sections F1 to F6 in six stages divided vertically. Is provided. Below each of the rectifying sections F1 to F6, a liquid receiver 25 for receiving a flowing liquid (reflux liquid) flowing down from the rectifying section, and the flowing liquid received by the liquid receiver 25 is placed in the lower rectifying section or the bottom of the tower. A liquid flow-down means comprising a liquid flow-down pipe 26 to flow down and a valve 27 for controlling the liquid flow through the liquid flow-down pipe 26 is provided. In addition, it is desirable that at least a part of the rectification means in each of the rectification units F1 to F6 is made of a structured filler. It is desirable to use a sieve tray other than the structured filler, but other rectification means, for example, an irregular filler can also be used.

The liquid flowing down means has a function of flowing down the flowing liquid flowing down from the upper rectifying section to the lower rectifying section during normal operation of the apparatus, and also has a function as liquid holding means. By closing the valve 27 at the time of the primary stop of the apparatus, the liquid flowing down from the upper
It is formed so as to be able to be held in a range from to the liquid receiver 25.

The position where the liquid flow-down means is provided can be arbitrarily set depending on conditions such as the structure of the rectification column. The more divisions, the more effective, but the equipment becomes complicated. As shown in the figure, a portion where liquid enters and exits, that is, a position where the raw material air introduction pipe 10 and the oxygen-enriched liquefied air introduction pipe 12 in the upper tower 23 are connected, and a middle part of a rectification section having many stages, for example, as shown in the figure Between the upper rectification section F5 and the lower rectification section F6 in the lower tower 22,
3 may be provided between the middle rectifying section F3 and the lower rectifying section F4.

During normal operation, the feed air introduced into the lower part of the lower tower 22 from the pipe 5 is supplied to the lower tower 2 as in the conventional case.
2 and the upper tower 23 are separated by the rectification operation, and nitrogen gas is led out from the pipe 19 at the top of the upper tower, and oxygen gas is led out from the pipe 20 at the lower part of the upper tower. At this time,
The liquid flowing down from each rectification section flows down to the lower rectification section or the bottom of the tower via the liquid receiver 25, the liquid downflow pipe 26, and the valve 27.

When the operation of the apparatus is temporarily stopped and the valves 27 of the liquid flow-down means are closed, the flow-down liquid flowing downward from each rectification section by gravity is applied to each rectification section F1-F6. The valve 27 is received by the liquid receivers 25 respectively provided below.
Is prevented from flowing downward, so that the pressure is maintained between the valve 27 and the liquid receiver 25.

When the apparatus is stopped, for example, the upper tower 2
In 3, the liquid flowing-down means provided below the uppermost rectifying section F1 has a composition of flowing liquid in the rectifying section F1 during operation of 1% to 35% of oxygen. %
Will be retained. Similarly, a liquid of about 40% oxygen is supplied to the liquid flow-down means below the rectification section F2.
A liquid with about 70% oxygen is held in the liquid flow-down means portion below 3 and a liquid with about 99% oxygen is held in the liquid flow-down means portion below the rectification section F3.

Also in the lower tower 22, a liquid of about 5% oxygen is supplied to the liquid flow-down means below the upper rectification section F5, and oxygen is supplied to the liquid flow-down means below the rectification section F6. 22
% Of the liquid is held.

Furthermore, the liquid accumulated at the bottoms of the two towers 22 and 23 is such that the liquid flowing down from the rectification sections F6 and F4 above the liquids is held by the liquid flow-down means and does not flow down to the bottoms of the towers. At the bottom of the lower tower 22, oxygen-enriched liquefied air of 35% oxygen having the same composition as during operation is held.
, Ie, the main condensing evaporator 24 portion, is in a state where liquefied oxygen of 99.7% oxygen same as the composition at the time of operation is held.

At the time of restart, when the introduction of the raw material air from the pipe 5 is started and the valves 27 of the liquid flow-down means below the rectification sections F5 and F6 of the lower tower 22 are opened, the rectification section F6
Rectification immediately begins, nitrogen gas of about 2% oxygen is introduced into the main condensing evaporator 24 from the top of the lower column, evaporates liquefied oxygen at the bottom of the upper column and liquefies itself, and a part of the gas flows from the pipe 16. The liquid is returned to the lower tower 22 and becomes the reflux liquid of the lower tower 22, and the remainder is introduced into the upper tower 23 via the pipe 17 as the reflux liquid.

In the upper tower 23, the reflux liquid introduced from the pipes 12 and 17 and the liquid flowing down to the lower rectification section by opening the valves 27 of the respective liquid flow-down means are separated by the main condensing evaporator 24.
The rectification is started by contact with the oxygen gas (ascending gas) evaporated in the above.

At this time, the valve 27 of the liquid flow-down means provided below the rectification section F4 at the bottom of the upper tower is connected to the rectification section F4.
By opening after the liquid of about 90% of oxygen flows down by the rectification, the concentration change of the liquefied oxygen accumulated in the main condensing evaporator 24 can be reduced.

In particular, at the beginning of the operation, the oxygen gas having a specified purity is vaporized in the main condensing evaporator 24 until the flow of the liquid from the rectifying section F4 starts. By adjusting the amount of oxygen gas withdrawn or the like, it is considered possible to derive and supply oxygen gas of a predetermined purity immediately after startup. Further, before stopping the apparatus, the oxygen concentration is increased by reducing the sampling amount of oxygen gas and the composition distribution in the upper tower is kept in an oxygen-enriched state, so that the lower part of the rectification sections F3 and F4 below the upper tower can be obtained. , The oxygen concentration of the liquid held can be increased, and the oxygen gas concentration at the time of restart can be recovered more quickly.

In this embodiment, the valve 27 for stopping the liquid flowing down from the lowermost rectification sections F4 and F6 of each rectification column can provide a considerable effect even if it is omitted. The effect can be obtained without providing the valve 27 in the portion.

FIG. 2 shows a rectification column in which the type of rectification section is a packed rectification section, and FIG. 2 (A) shows a configuration between rectification sections in a conventional packed rectification section. FIG. 2B shows an example of the liquid flow-down means of the present invention provided between the rectification sections.

First, in the conventional packed-type rectification tower 31 shown in FIG. 2A, an upper packed-type rectifying section 32 and a lower packed-type rectifying section 33 are provided with an upper packed-type rectifying section 33. A collector 34 for collecting the liquid flowing down from the rectifying section 32, a collecting pipe 35, and a distributor 36 for dispersing the liquid in the lower filling rectifying section 33 are provided. Therefore, the liquid flowing down from the filling rectification section 32 joins the collecting pipe 35 from the collector 34, and then flows down from the distributor 36 to the filling rectification section 33.

The liquid flow-down means shown in FIG. 2 (B) is provided with a valve 37 in the collecting pipe 35, and holds the flow-down liquid flowing down the liquid pool of the collector 34 from the upper filling rectification section 32 when the apparatus is stopped. It is formed in a size that is possible.

FIG. 3 shows a structure similar to the liquid flow-down means shown in FIG. 2 (B), in which a vessel 38 serving as a liquid holding means is provided outside the rectification column 31 and the lower part thereof is connected to the collecting pipe 3.
5 and the upper part thereof is filled with a rectifying section 32.
In the tower below. By providing the container 38 in this manner, it is possible to hold a large amount of flowing liquid while suppressing the height of the rectification column 31.

FIG. 4 shows a rectification column in which the type of rectification section is a plate-type rectification column. FIG. 4 (A) shows a configuration between rectification sections in a conventional plate-type rectification section. FIG. 4B shows an example of the liquid flow-down means of the present invention provided between the rectification sections.

First, in the conventional tray-type rectification column 41 shown in FIG. 4 (A), the flow-down liquid flows down from the outlet 43 provided in each rectification shelf 42 to the rectification shelf 42 below. It is formed so that. The liquid flow-down means shown in FIG. 4 (B) is an upper rectification unit 4 comprising a plurality of rectification racks 42.
4 is formed between the rectifying section 45 and the lower rectifying section 45 to have a size necessary for holding the flowing liquid, and
6 and the lower rectification shelf 42 are connected by a pipe 48 having a valve 47. Therefore, by closing the valve 47 when the apparatus is stopped, the flowing liquid can be held in the portion from the outlet 46 to the pipe 48.

FIG. 5 shows a structure similar to the liquid flow-down means shown in FIG. 4B, in which a vessel 49 serving as liquid holding means is provided outside the rectification column 41, and the lower part thereof is connected to the pipe 48. The upper part of the tower is connected to the tower. As described above, by providing the container 49, it becomes possible to hold a large amount of the flowing liquid in the same manner as described above.

FIG. 6 shows a second embodiment of the air liquefaction / separation apparatus of the present invention.
This shows an example of the form, in which a lower tower 51 and an upper tower 5 of a double rectification column are shown.
2 is shown separately. In this case, the rectification section F4 at the bottom of the upper tower and the main condensing evaporator 53 are connected to a liquid down pipe 54 through which the flowing liquid flows and a gas rising pipe 5 through which the rising gas flows.
5 and a valve 56 for holding the flowing liquid when stopped is provided in the liquid flowing down pipe 54.
By forming in this way, the storage volume at the bottom of the tower serving as the liquid holding means below the rectifying section F4 can be made sufficiently large, so that an optimal structure for collecting oxygen gas immediately after startup is obtained. . The same components as those in the rectification column shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 7 shows a third embodiment of the air liquefaction / separation apparatus of the present invention.
1 shows an embodiment and shows an example of an air liquefaction / separation apparatus provided with a crude argon column 61. FIG. The same components as those of the rectification column shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The crude argon column 61 rectifies the argon raw material gas introduced through the pipe 62 from between the rectification section F3 and the rectification section F4 below the upper tower 23, and rectifies the pipe 63 at the top of the tower.
From which crude argon is derived. The rectification section in the column of the crude argon column 61 is divided into an upper rectification section F7 and a lower rectification section F8, and below both rectification sections F7 and F8, a liquid similar to the above is provided. Receiver 64, liquid downcomer 65 and valve 66
Are provided respectively.

This liquid flow-down means can also hold a liquid having an appropriate composition on the primary side of the valve 66 by closing the valve 66 when the apparatus is stopped, so that gas is introduced from the pipe 62 when the apparatus is restarted. When the valve 66 is opened at the same time as the start, the rectification in a state close to the normal operation can be started in each of the rectification sections F7 and F8, and the derivation of the crude argon of a predetermined concentration can be started in a short time. Can be.

In the figure, reference numeral 67 denotes a heat exchange between the oxygen-enriched liquefied air derived from the bottom of the lower tower 22 and the crude argon gas at the upper part of the crude argon tower 61 to vaporize the oxygen-enriched liquefied air. This is a condenser for liquefying the crude argon to obtain a reflux liquid of the crude argon column 61.

FIG. 8 shows a fourth embodiment of the air liquefaction / separation apparatus of the present invention.
1 shows an embodiment, in which the present invention is applied to an air liquefaction / separation apparatus having a single rectification column. The air liquefaction / separation apparatus purifies air compressed by an air compressor 71 through an after-cooler 72 in an adsorption facility 73, cools it in a main heat exchanger 74, and introduces it into a single rectification column 75. By rectification in the rectification column 75, nitrogen gas at the top of the column and oxygen-enriched liquefied air at the bottom of the column are separated, and nitrogen gas is obtained from the top of the column via pipes 76 and 77.

The oxygen-enriched liquefied air led from the bottom of the tower to the pipe 78 is introduced into the condenser 80 via the pressure reducing valve 79, and is introduced into the condenser 80 from the top of the tower via the pipes 76 and 81. The liquefied nitrogen gas is liquefied to generate a reflux liquid, which itself is vaporized and becomes oxygen-enriched air, which is led out to the pipe 82. After the oxygen-enriched air is heated to the intermediate temperature in the main heat exchanger 74, it is led out of the expansion turbine 83 through the main heat exchanger 74 again.

Also in such a single rectification column 75, the rectification section in the tower is divided into an upper rectification section F9 and a lower rectification section F10, and below the rectification sections F9 and F10, By providing the same liquid receiver 84, liquid downflow pipe 85, and liquid downflow means as described above, the time required for restart can be greatly reduced for the same reason as above.

In the present invention, the concentration distribution in the rectification column is
It is characterized in that it is roughly divided and held at the time of stoppage, and from this point, it is not necessarily limited to preventing the entire amount of the flowing liquid from flowing down.

[0047]

As described above, according to the present invention,
Not only can the time required for restarting be greatly reduced to reduce power loss, but also the equipment can be stopped even during short-time demand reductions that could not be stopped in the past. This is ideal for equipment with large fluctuations in the demand for separated product gas. Further, power and labor costs can be saved, and small maintenance can be performed using the opportunity for shutdown.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a first embodiment of an air liquefaction / separation apparatus of the present invention.

FIG. 2 is an explanatory view showing an example of a mode between rectification sections in a packed rectification section.

FIG. 3 is an explanatory view showing another embodiment.

FIG. 4 is an explanatory diagram showing an example of a mode between rectification units in a tray type rectification unit.

FIG. 5 is an explanatory view showing another embodiment.

FIG. 6 is a system diagram showing a second embodiment of the air liquefaction / separation device of the present invention.

FIG. 7 is a system diagram showing a third embodiment of the air liquefaction / separation apparatus of the present invention.

FIG. 8 is a system diagram showing a third embodiment of the air liquefaction / separation apparatus of the present invention.

FIG. 9 is a system diagram showing an example of a conventional air liquefaction / separation apparatus.

[Explanation of symbols]

21 rectification tower, 22 lower tower, 23 upper tower, 24 main condensing evaporator, 25 liquid receiver, 26 liquid downcomer, 27 valve
31: packed rectification tower, 32, 33 ... packed rectification unit, 3
4 ... collector, 35 ... collecting piping, 36 ... distributor, 37 ... valve, 38 ... container, 41 ... tray-column rectification tower, 42 ... rectification shelf, 43 ... fall, 44,45 ... rectification section ,
46 ... drop, 47 ... valve, 48 ... pipe, 49 ... container, 51 ...
Lower tower, 52: Upper tower, 53: Main condensing evaporator, 54: Liquid downcomer, 55: Gas riser, 56: Valve, 61: Crude argon tower, 62, 63 ... Tube, 64: Liquid receiver, 65 ... Liquid down pipe,
66 ... valve, 67 ... condenser, 71 ... air compressor, 72 ... after cooler, 73 ... adsorption equipment, 74 ... main heat exchanger,
75 ... single rectification tower, 76, 77, 78 ... pipe, 79 ... pressure reducing valve, 80 ... condenser, 81, 82 ... pipe, 83 ... expansion turbine, 84 ... liquid receiver, 85 ... liquid down pipe, 86 ... valve , F1 to F
10 ... rectification department

Claims (2)

[Claims] 1. An air liquefaction / separation apparatus provided with a rectification column for performing cryogenic liquefaction rectification of compressed, purified and cooled raw material air, wherein the rectification section of the rectification column is divided into a plurality of parts in a vertical direction, At least one of the divided rectification sections is provided below at least one rectification section with a liquid flow-down means for flowing the flow-down liquid to the lower rectification section, and the liquid flow-down means prevents the flow of the flow-down liquid. An air liquefaction / separation apparatus, characterized in that a liquid holding means capable of holding the flowing liquid is provided. 2. An air liquefaction separation method in which compressed, purified and cooled raw material air is introduced into a rectification column to perform cryogenic liquefaction rectification, wherein the rectification section of the rectification column is divided into a plurality of parts in the vertical direction. ,
At the time of operation, the flow-down liquid flows down to the lower rectification section via the liquid flow-down means in at least one of the divided rectification sections, and when the operation is stopped, the flow-down liquid flows at each liquid flow-down means. Air liquefaction / separation method, characterized in that the flow-down is prevented and the flow-down liquid is held in each liquid flow-down means.