JP2000074558A - Air liquefaction separating device and air liquefaction separating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air liquefaction separating device and a method for operating this device in which a normal operating state can be reached within a short period of time when the device is restarted. SOLUTION: There is provided an air liquefaction separating device in which a lower tower 14, an upper tower 15, and a crude argon tower 17 are installed to liquefy air, rectify it and recover oxygen, nitrogen and argon or the like. There is provided a crude argon tower condenser bypassing passage 45 for connecting an oxygen enriched liquefied air feeding passage 30 for feeding out oxygen enriched liquefied air from the lower part of the lower tower 14 and feeding it into a condenser 33 in the crude argon tower 17 with a passage 43 for feeding either non-evaporated oxygen enriched liquefied air or evaporated oxygen enriched air fed out of the condenser 33 to the upper tower and then the crude argon tower condenser bypassing passage 45 is provided with a bypass valve 46.

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 a method for stopping / restarting the apparatus, and more particularly to an air liquefaction / separation apparatus having an argon collection system and a method for stopping / restarting the apparatus.

[0002]

2. Description of the Related Art In a method of liquefying and separating air to collect oxygen, nitrogen, argon and the like as a gas or a liquid product, a method for efficiently operating the apparatus or temporarily stopping the apparatus. The efficient way to restart is
Various schemes have been proposed. The air liquefaction / separation apparatus for performing these ordinary oxygen, nitrogen and argon samplings has a configuration as shown in FIGS. 1, 3 and 4. Note that the conventional device shown here does not include the route indicated by the broken line.

In the apparatus of the type shown in FIG. 1, the main parts are a raw material air compressor 2 for compressing raw material air and a molecular sieve adsorber (MS) filled with a molecular sieve for removing moisture, carbon dioxide and the like in the air. Adsorber) 6, a main heat exchanger 8 for cooling the compressed and purified raw air, a lower tower 14 for roughly separating the compressed / purified / cooled air, and a rectifying / separating layer for separating and collecting product oxygen and product nitrogen. Double rectification tower (hereinafter sometimes referred to as main rectification tower) 13 comprising upper tower 15
, And an argon source gas is led out from the upper central portion of the upper column as an argon collecting system to obtain a crude argon column 17.
To collect crude argon.

An apparatus of the type shown in FIG. 3 is an apparatus using a reversing heat exchanger in which the adsorber in the pretreatment step and the main heat exchanger in the cooling step in the apparatus of FIG. 1 are integrated. A reversing heat exchanger (also called a regenerative heat exchanger or a reversible heat exchanger) cools the compressed raw material air by heat exchange with the return gas from the rectification column, and simultaneously removes moisture and carbon dioxide in the air. This is a heat exchanger of the type that is condensed and precipitated in the flow path and removed.

A process using a reversing heat exchanger differs from the conventional case of FIG. 1 having a system using the pretreatment adsorber only in a portion related to the reversing heat exchanger.

The reversing heat exchanger (Rivex)
The raw material air flow path and the exhaust gas flow path are switched at regular intervals and exchanged with each other, and the raw material air flow path in the previous cycle becomes the exhaust gas flow path in the next cycle. Therefore, the raw material air flow path on which moisture and carbon dioxide gas are deposited and adhered in one cycle becomes an exhaust gas flow path in the next cycle, and the moisture and carbon dioxide gas deposited and deposited in the previous cycle are sublimated into the exhaust gas in this cycle to be out of the system. Is discharged to
The flow path cleaned by the exhaust gas becomes the raw air flow path again in the next cycle and repeats this.

Further, the reversing heat exchanger (Rivex) is provided with a reheating circuit, in which a part of the raw material air once cooled almost to the liquefaction temperature is returned to the intermediate temperature (about -10).
A channel for raising the temperature to about 0 ° C.) is provided. At this temperature, the air flowing through the reheat flow path is led out of the ribex and introduced into the expansion turbine, where it expands and decompresses to approximately the pressure of the upper tower, and is introduced into the stage of the air composition of the upper tower. This provides the required refrigeration for the entire system.

Further, the product nitrogen gas and the exhaust gas (the return gas) which are led out from the upper part of the upper tower and introduced into the reversing heat exchanger are first supplied to the oxygen-enriched liquefied air from the lower tower by the subcooler. Heat exchange with liquefied nitrogen -170
The temperature rises to about ° C, and then enters Libex. In this way, the reversing heat exchanger (Rivex) has two functions of cooling air by heat exchange between the raw air and each return gas, and removing impurities in the air. Strict precision of temperature control is required. For this reason, the temperature is controlled by the above-described flow path configuration and the supercooler.

The main components of the air separation device of this type other than the reversing heat exchanger are the same as those of the air separation device employing the pretreatment device using the MS adsorber.
That is, a raw material air compressor for compressing raw air, a double rectification column including a lower tower and an upper tower, and a crude argon column for collecting crude argon are main components, and the process flow is almost the same.

Further, recently, a process has been proposed in which one rectification column is installed next to the crude argon column to purify oxygen in the crude argon to 1 ppm or less. In this process,
Without adopting the hydrogenation catalyst purification process of the argon purification system,
Instead, a deoxygenation column, which is a deoxygenation column with 100 to 140 stages, is used to purify crude argon containing about 1% oxygen derived from the crude argon column to about 1 ppm or less. . Particularly recently, as a gas-liquid contacting means in the rectification column, a packed column using a packing material is used instead of the conventional sieve tray, and the total equivalent number of stages with the crude argon column is set to about 200 stages. As a result, oxygen can be removed up to about 1 ppb.

FIG. 4 shows an example of an air liquefaction / separation apparatus equipped with an argon purification system using this deoxidation tower. This process differs from the conventional one shown in FIG. 1 only in the argon purification system using the deoxidizing tower, and the other parts common to FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

In this type of air separation apparatus, the crude argon column is provided in the same manner as in the conventional process, and the number of stages is 50 to 60 as in the conventional case, or 70 to 80 in the case of using a packed column. Is also possible. Since the condenser is usually provided in the deoxidizing tower, it is not provided in the crude argon column.

The deoxidizing tower is provided with a condenser at the top, and the cooling source is oxygen-enriched liquefied air from the lower part of the lower tower as in the case of the ordinary crude argon tower. The oxygen-enriched liquefied air may be a liquid at the bottom of the column, but the liquid extracted from one to several stages above the bottom of the column is much safer for operation because the content of carbon dioxide or hydrocarbon is significantly reduced. It is preferable for measures.

Before being introduced into the condenser, the oxygen-enriched liquefied air of the cold source of the deoxidizing tower condenser passes through a reboiler provided at the bottom of the deoxidizing tower to vaporize the liquefied crude argon at the bottom of the deoxidizing tower. Then, it is expanded by the expansion valve and enters the condenser. A reboiler provided at the bottom of the deoxidization tower evaporates the liquid crude argon at the bottom to increase the amount of gas rising in the deoxidation tower and increase the gas-liquid contact amount.

[0015]

However, in the air liquefaction / separation apparatus, for example, when product oxygen is blown into a blast furnace and used for oxygen scouring by a converter, the oxygen demand depends on the operating conditions of the steelmaking and scouring furnaces. It fluctuates greatly. Various air liquefaction / separation apparatuses have been proposed that can change the operating conditions in response to the fluctuations in the demand amount of product oxygen, adjust the supply oxygen amount, and change the production amounts of product oxygen and product nitrogen.

In the case where a plurality of separation apparatuses other than the demand-variation-type air liquefaction separation apparatus are installed, for example, one of them is suspended once or twice a month, and after one to several days, the operation is temporarily stopped. It restarts and supplies product gas.

When the air liquefaction / separation device is temporarily stopped as described above, all the liquefied gas held in each rectification stage such as each rectification falls to the bottom of the column and is stored. That is,
In the lower tower when the apparatus is stopped, all the liquid held in the tower falls to the bottom of the tower, so that liquid air having a higher nitrogen concentration than in normal operation is stored in the bottom of the tower. In the upper tower, due to the same phenomenon, liquefied oxygen having a lower oxygen concentration than in the normal operation is stored at the bottom (main condenser).

In particular, when the apparatus is provided with an argon sampling system, the liquid in the crude argon column falls to the bottom of the crude argon column due to the stoppage of the apparatus, and the composition becomes higher in argon concentration than the raw argon gas. It will return to the upper tower as it is. Then, the liquefied gas having this composition is stored at the bottom of the upper tower. That is, when the liquid from the crude argon column returns to the bottom of the upper column, the liquid oxygen of the double rectification column main condenser is enriched with argon, and the purity is greatly reduced. Therefore, when the restart is performed, it takes a long time for the purity of the liquid oxygen stored in the main condenser to reach a steady operation state.

In particular, in a large-sized air liquefaction / separation apparatus, the time required for the temporary stop and restart is long, which contributes to an increase in the price of product gas.

Therefore, according to the present invention, when the apparatus is temporarily stopped and restarted, the operation of the argon purification system is substantially stopped in advance when the apparatus is stopped, and the operation in the crude argon column is returned to the upper column while the operation is continued for a while. The liquid in the crude argon column is discharged while almost maintaining the purity of the liquefied oxygen in the main condenser, and after the discharge is completed, the operation of the main rectification column alone is performed for a while, and the oxygen purity is equal to or higher than a certain value. The present invention provides an air liquefaction / separation apparatus and an operation method thereof, in which the operation of the entire apparatus is stopped at the time of confirming that the state of the main rectification tower can reach a steady operation state in a short time at the next start. The purpose is to: In addition, in an air liquefaction / separation device using a reversing heat exchanger, an air liquefaction / separation device and a method thereof that facilitate temperature control of the reversing heat exchanger and facilitate operation of the device are provided.

[0021]

In order to achieve the above-mentioned object, an apparatus according to the present invention comprises a lower tower, an upper tower and a crude argon tower, and liquefies air to remove oxygen, nitrogen and argon. A path for extracting oxygen-enriched liquid air from the lower part of the lower column and introducing it to the crude argon column condenser; A coarse argon column condenser bypass path connecting a path for introducing liquefied air or vaporized oxygen-enriched air to the upper tower or a path for extracting oxygen-enriched liquefied air from the lower tower lower part and introducing it to the upper tower upper part; , An air liquefaction / separation apparatus characterized in that a bypass valve is provided in the path. Further, the apparatus configuration of the present invention is an air liquefaction / separation apparatus that includes a lower tower, an upper tower, and a crude argon tower, and liquefies air to collect oxygen, nitrogen, argon, and the like. A route for extracting liquid air and introducing it to the crude argon column condenser, and a crude argon column condenser bypass route for branching the oxygen-enriched liquefied air introduction route and introducing oxygen-enriched liquefied air to the upper column upper part. An air liquefaction / separation device having a bypass valve provided in the bypass path.

The apparatus of the present invention is an air liquefaction / separation apparatus comprising a lower tower and an upper tower, a crude argon tower and a deoxidizing tower, wherein the air is liquefied and rectified to collect oxygen, nitrogen and argon. A path for drawing out the oxygen-enriched liquid air from the lower part of the lower tower and introducing it to the deoxidizing tower condenser, and for converting the unevaporated oxygen-enriched liquefied air or evaporated oxygen-enriched air derived from the deoxidizing tower condenser. A deoxidation tower condenser bypass path connecting a path for introduction to the upper tower or a path for extracting oxygen-enriched liquefied air from the lower part of the lower tower and introducing it to the upper part of the upper tower was provided, and a bypass valve was provided in the path. It is an air liquefaction separation device characterized by the above-mentioned.

The apparatus of the present invention is an air liquefaction / separation apparatus comprising a lower tower and an upper tower, a crude argon tower, and a deoxidizing tower, wherein the air is liquefied and rectified to collect oxygen, nitrogen, argon and the like. A path for leading out the oxygen-enriched liquid air from the lower part of the lower tower and introducing it to the deoxidizing tower condenser, and a path for branching the oxygen-enriched liquefied air introduction path and introducing the oxygen-enriched liquefied air to the upper part of the upper tower An air liquefaction / separation apparatus having an acid tower condenser bypass path and a bypass valve provided in the bypass path.

Further, the present invention is the air liquefaction / separation apparatus described above, wherein the main heat exchanger of the air liquefaction / separation apparatus is a reversing heat exchanger (reversible heat exchanger). Further, the present invention is characterized in that a bypass path and a bypass valve of the oxygen-enriched liquefied air outlet path are provided on a low-temperature side outlet side of a supercooler provided in the oxygen-enriched liquefied air outlet path. Is an air liquefaction separation device.

Further, the air liquefaction / separation apparatus described above is characterized in that the air liquefaction / separation apparatus is provided with a pretreatment apparatus for removing water, carbon dioxide, and the like in the raw material air. Further, the air liquefaction / separation apparatus as described above, wherein at least one of the lower tower, the upper tower, the crude argon tower and the like is a packed tower. The air liquefaction / separation apparatus as described above, wherein at least one of the lower tower, the upper tower, the crude argon tower, the deoxygenation tower and the like is a packed tower. The air liquefaction / separation apparatus according to the above description, wherein the position of the lower part of the lower tower from which the oxygen-enriched liquid air is led out is the bottom of the lower tower. Further, the air liquefaction / separation apparatus according to the above, wherein the position of the lower portion of the lower tower from which the oxygen-enriched liquid air is led is one stage to several stages above the bottom of the lower column.

Further, the present invention is directed to an air liquefaction in which air is compressed, purified, cooled, and sequentially introduced into a double rectification column, a crude argon column, etc., and liquefied and rectified to separate at least oxygen and argon as products. A separation method, in which the argon raw material gas derived from the upper part of the double rectification tower is introduced into the lower part of the crude argon tower, and the oxygen-enriched liquefied air derived from the lower part of the lower part of the double rectification tower is supplied to the crude argon column condenser. In the air liquefaction and separation method for introducing and purifying argon, the air liquefaction and separation apparatus is temporarily stopped and, upon restarting, the oxygen-enriched liquefied air derived from the lower part of the lower column of the double rectification column is converted into a crude argon column condenser. First, supply of oxygen-enriched liquefied air to be introduced into the reactor is stopped, and after temporarily operating only the double rectification column, supply of compressed raw material air is stopped, and when restarting, liquefied oxygen is stored at the bottom of the upper tower Starting operation from A cryogenic air separation process, characterized in that the start.

Further, the invention of the present application is to compress, purify, cool and introduce air into a double rectification column, a crude argon column, a deoxidization column and the like in order to liquefy and separate, and to convert at least oxygen and argon as products. An air liquefaction separation method for sampling, in which the argon raw material gas derived from the middle part of the upper tower of the double rectification tower is introduced into the lower part of the crude argon tower, and the oxygen-enriched liquefied air derived from the lower part of the lower tower of the double rectification tower is deoxygenated. In the air liquefaction separation method of introducing argon into the column condenser and purifying argon, the air liquefaction separation device is temporarily stopped, and upon restarting, the oxygen-enriched liquefied air derived from the lower part of the double rectification column lower column is subjected to the First, the supply of oxygen-enriched liquefied air to be introduced into the deoxygenation tower condenser was stopped, and the supply of crude argon from the bottom of the deoxidation tower was stopped. Stop supply of raw air and restart During movement, the the upper column bottom impure liquid oxygen is stored, and the a cryogenic air separation process, characterized in that liquefied crude argon deoxygenated bottoms starts startup operation from a state that is stored.

The position of the lower part of the lower tower from which the oxygen-enriched liquid air is led out is at least one column from the bottom of the lower tower and / or from the bottom.
The air liquefaction separation method according to any one of the above methods, wherein the air liquefaction separation method is a stage from a stage to several stages.

According to the above configuration, when the apparatus of the present invention is temporarily stopped and restarted, the operation of the argon purification system is substantially stopped in advance when the apparatus is stopped, and the liquid in the crude argon column is transferred to the upper column. The operation is continued for a while while returning, the liquid in the crude argon column is discharged while maintaining the purity of the liquefied oxygen in the main condenser substantially, and when the discharge is completed and the above oxygen concentration reaches a predetermined value, the operation of the entire apparatus is started. Is stopped, the state of the main rectification column can reach a steady operation state in a short time at the next start.

Further, in the air liquefaction / separation apparatus using the reversing heat exchanger, the temperature control of the reversing heat exchanger is facilitated, and the operation of the apparatus is facilitated.

Also in an air liquefaction / separation apparatus having an argon purification system provided with a deoxidation tower, when the apparatus is temporarily stopped, the supply of oxygen-enriched liquefied air to the deoxidation tower condenser is similarly bypass-supplied. By doing so, the operation state around the crude argon column is performed in the same manner as described above, and all the argon sampling systems can be stopped by stopping the liquid pump that returns the liquid crude argon from the deoxidation column to the crude argon column. it can. As a result, the operation of only the main rectification column can be performed for a while, the reduction of the purity of the main condenser can be minimized, and the entire apparatus can be stopped. .

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Three typical types of air liquefaction / separation apparatuses for carrying out the present invention will be described below. In the following description, FIGS. 1 to 4 used in the description of the related art will be used. However, the air liquefaction / separation apparatus according to the embodiment of the present invention described below has at least one of the paths indicated by broken lines in the figure. Shall be included. FIG. 1 and FIG. 2 show the most usual types of apparatuses, in which pretreatment is performed using an MS adsorber. The argon purification system is shown up to the crude argon column. The example of FIG. 3 is an example of an apparatus using a reversing heat exchanger that simultaneously removes and cools impurities in the raw air with a heat exchanger. FIG. 4 shows a system in which a deoxidizing column is provided next to the crude argon column, and the catalyst hydrogenation step is omitted.

In the apparatus of the type shown in FIG. 1, a raw material air compressor 2 for compressing raw air, an MS adsorber 6 which is a pretreatment device for removing moisture and carbon dioxide in the air, and a compressed and purified raw air are cooled. A main heat exchanger 8, a lower column 14 of a double rectification column 13 for roughly separating the compressed, purified and cooled air; an upper column 15 for separating and collecting product oxygen and product nitrogen by further rectification and separation; The main component is a crude argon column 17 which takes out an argon source gas from the center of the column and collects crude argon.

The atmospheric air introduced from the pipe 1 is compressed to a pressure of 0.7 MPa by the air compressor 2 and introduced into the adsorber 6 through the conduit 3, the after cooler 4, and the conduit 5. The compressed air introduced into one of the paired adsorbers 6a used for switching is adsorbed and removed from the water and carbon dioxide contained therein, and the carbon dioxide content is 1 ppm or less, and the dew point is -70 ° C.
It is purified as follows, and is supplied to the pipe 7 as purified air. At this time, the other adsorber 6b switched and used is in the regeneration step.

The compressed purified air from which the carbon dioxide gas and moisture contained in the MS adsorber 6 have been removed enters the main heat exchanger 8 through the conduit 7 and exchanges heat with oxygen, nitrogen and other gases returned from the main rectification column 13. The main heat exchanger 8 is cooled at a liquefaction temperature (−172 ° C.) at the pressure from the cold end side of the main heat exchanger 8, and the main rectification column is supplied through a conduit 9. 13 is introduced into the lower part of the lower tower 14 and becomes ascending gas in the tower.

The part of the main heat exchanger 8 branched from the conduit 7 at the intermediate temperature is led out from the main heat exchanger 8 to the conduit 10,
The gas enters the expansion turbine 11 and is adiabatically expanded to reduce the pressure and temperature down to about 0.04 MPa.

The raw material air introduced into the lower tower 14 rises in the tower, comes into contact with the reflux liquid descending from the top of the tower in a countercurrent gas-liquid manner to perform rectification, and separates nitrogen into the upper part of the tower. At the bottom of the lower column, oxygen-enriched liquefied air distills.

The nitrogen gas separated at the top of the lower tower 14 enters a main condensing evaporator 16 which exchanges heat with liquefied oxygen at the bottom of the upper tower via a conduit 18 and is distilled at the bottom of the upper tower 15. It exchanges heat with liquefied oxygen, thereby condensing into liquefied nitrogen to be led out to conduit 19 and divided into three parts.
Further, it is again introduced into the top of the lower tower 14 and becomes a reflux liquid of the lower tower 14 and flows down in the tower. The gas rising in the tower is brought into gas-liquid contact and rectification proceeds. Further, the second liquefied nitrogen, which has been divided into three, is expanded and depressurized by the expansion valve 22 through the flow path 21, and then introduced into the top of the upper tower 15, becomes a reflux liquid of the upper tower 15, and flows down in the tower. The third branch is introduced into the liquefied nitrogen storage tank 24 via the flow path 23 and stored therein.

The nitrogen gas separated at the top of the lower tower 14 is
In some cases, part of the gas is taken out as product gas, the cold is recovered through the main heat exchanger 8, and is led out of the system at room temperature.

The oxygen-enriched liquefied air distilled at the bottom of the lower tower 14 is drawn out from a flow path (tube) 25, is supercooled by a supercooler 26, is expanded and depressurized by an expansion valve 27, and has a pressure of about 0.1 mm. After the pressure reaches 04 MPa, the gas is introduced into the middle part of the upper column 15 through a conduit 28 and is subjected to rectification in the column.

In the upper tower 15, the oxygen gas evaporated in the main condensing evaporator 16 rises in the upper tower 15, and the liquefied nitrogen reflux liquid introduced to the top of the tower 13, and the oxygen gas introduced to the middle section The rectification proceeds by making gas-liquid contact with the descending liquid of the enriched liquefied air to separate high-purity nitrogen gas at the top of the column and oxygen gas and liquefied oxygen at the bottom of the column. Waste gas is route 8
7 and 88, heat is recovered in the main heat exchanger 7, and is drawn out of the system through a route 90.

The nitrogen gas separated at the top of the upper tower 15 is led out from the conduit 60 and passes through the oxygen-enriched liquefied air in the pipe 25 flowing countercurrently in the supercooler 26 and the liquefied nitrogen in the pipe 21. After cooling, the temperature rises itself, enters the main heat exchanger 8 via a conduit 61, and exchanges heat with the raw material air to become almost normal temperature, is taken out as a product nitrogen gas from a conduit 62, and is blown under pressure (not shown). And then sent to the destination. Further, the exhaust gas taken out from the upper part in the upper tower is led out through almost the same path (not shown) as the above product nitrogen gas, heat is recovered in the main heat exchanger 8, and is drawn out of the system.

Similarly, the oxygen gas separated at the bottom of the upper tower 15 is led out from the conduit 63, the cold is recovered through the main heat exchanger 8, and is taken out as the product oxygen gas from the flow path 64 to the destination. Sent. The product liquefied oxygen is supplied to the flow path 65
Through the liquefied oxygen storage tank 66 and stored.

Next, an argon raw material gas (feed argon) is led to a conduit 34 from the vicinity of the stage having the highest argon concentration in the lower part of the upper column 15 and the crude argon column 17
Where argon / oxygen rectification takes place. That is, as the feed argon introduced into the lower part of the crude argon column 17 rises in the column, the argon concentration increases due to rectification, and the argon concentration near the top of the column is 98%.
From the conduit 36 to the crude argon condenser 3
3 is introduced.

The crude argon condensed by heat exchange with the oxygen-enriched liquefied air in the crude argon condenser 33 is supplied to the conduit 3.
7, a part of which is supplied from the conduit 38 to the crude argon column 1
At the top of 7 is introduced again as reflux. A part branched from the conduit 37 is sent as crude argon from the conduit 39 to the next deoxygenation step.

The liquid flowing down in the crude argon column 17 is returned from the bottom of the column to the lower portion of the upper column 15 via a conduit 35.

The oxygen-enriched liquefied air discharged from the bottom of the lower column is also supplied to a crude argon column condenser as a refrigeration source for producing a reflux liquid of the crude argon column. That is, the conduit 25
Into the conduit 30 (FIG. 2) from one or several stages above the bottom of the lower tower 14 and into the crude argon condenser 33 after expansion and pressure reduction by the expansion valve 31. Is done.

The oxygen-enriched liquefied air introduced into the crude argon condenser 33 here rises in the crude argon column 17 and exchanges heat with the crude argon in which the argon is concentrated, thereby providing cooling, and evaporates itself to form a conduit. From 42, it is introduced into the upper part of the upper tower 15. At this time, the excess portion that has not evaporated is introduced into the middle and upper part of the upper tower 15 through the conduit 43 in the same manner.

The above is a general process of the main rectification column and the crude argon column. The present invention further organically connects the route for organically connecting the main rectification column and the crude argon column. , Shortening the restart time or facilitating the temperature control of REVEX. That is, a bypass is provided in a path for supplying the oxygen-enriched liquefied air to the crude argon column condenser, and a bypass valve provided in the path is appropriately operated.

That is, the conduit 30 for introducing the oxygen-enriched liquefied air derived from the bottom of the lower column 14 into the crude argon column condenser 33 and the oxygen-enriched liquefied air derived from the crude argon condenser 33 are supplied to the upper column 15. A bypass path 45 connecting the introduction conduit 43 and a bypass valve 46 are provided in the path 45. This makes it possible to supply the oxygen-enriched liquefied oxygen to the upper column 15 by bypassing the condenser 33 of the crude argon column 17. You can drive.

That is, when the operation of the entire air liquefaction / separation apparatus is stopped, first, the bypass valve 46 that has been completely closed is opened. At the same time, the expansion valve 31 provided on the path for introducing the oxygen-enriched liquefied air into the crude argon column condenser 33 is gradually closed. Thereby, the cooling function of the crude argon tower 17 condenser 33 is stopped, the condensation of the crude argon gas is stopped, and the crude argon tower 1 is passed from the upper tower 15 via the conduit 34.
The supply of the argon source gas sucked into 7 stops.

At the same time, in the case of the sieve tray type crude argon column, the liquid retained on the trays at each stage in the column flows down the column, passes through the liquid reservoir at the bottom of the column, passes through the conduit 35, and passes through the upper column 1
It returns to a position almost the same as that of the extraction part of the argon source gas of No. 5. Even when the crude argon column 17 is a packed column, all the liquid held on the surface of the packed material flows down in the column and behaves similarly.
The operation of the upper tower 15 is continued in almost the same state as the steady operation, but the purity of the liquefied oxygen accumulated in the main condensing evaporator 16 at the bottom of the upper tower 15 decreases, and the argon concentration in the exhaust gas slightly increases. Continue driving for a while in the state. Eventually, the concentration of liquefied oxygen reaches a predetermined value, and an equilibrium state is established.

When this state is reached, the feed pressure of the raw material air compressor is stopped. When the operation of the main rectification column 13 is stopped, all the liquid held in the trays of the upper tower 15 and the lower tower 14 flows down and accumulates at the bottom of each tower. At this time, the upper tower 1
5 The composition of the liquid collected at the bottom of the column is almost the same as the liquid stored at the bottom of the column when the air liquefaction / separation apparatus without the coarse argon column 17 is stopped because there is no inflow of liquid from the bottom of the crude argon column 17. It has the same composition. At this time, before the stop, the route 21, 2
By closing the valves 22 and 27 of No. 5 and continuing the operation for a while, the concentration of liquefied oxygen can reach the predetermined value in a short time. The liquid collected at the bottom of the lower column 14 has the same composition regardless of the presence or absence of the crude argon column.

Therefore, at the time of restarting, the operation can be started from a state in which a liquid having a composition close to the stored liquid at the time of steady operation is stored at the bottom of the upper tower 15. With a device of 100,000 Nm ³ / h, the time is reduced by 4 to 5 hours. In addition, by stopping the argon collection system and operating only the main rectification column, it is easy to increase or decrease the amount of oxygen and nitrogen to be collected, and the amount of reduction can be increased.

The bypass path 45 and the bypass valve 4
Paths and valves that perform the same function as 6 can be provided in other paths. That is, by providing the bypass path 47 and the bypass valve 48 between the path 30 for oxygen-enriched liquefied air and the path 42 for vaporized oxygen-enriched air, the same function as in the above case can be obtained. Also, as shown in FIG. 2, a bypass path 49 and a bypass valve 50 are provided in the conduit 40 of the oxygen-enriched liquefied air, and the oxygen-enriched liquefied air is directly introduced into the upper column 15 by bypassing the crude argon condenser 33. Thus, the same functions as those of the bypass path 45 and the bypass valve 46 are obtained. The bypass path 49 of the path 40 is not directly introduced into the upper tower 15 but is joined to the other oxygen-enriched liquefied air introduction paths 25 and 28 (bypass valve 5).
A route 49 ′) having 0 ′ may be used. The route 40,
The same result can be obtained by connecting the bypass passage 49 of 30 to the oxygen-enriched liquefied air passage 43 or the vaporized air passage 42 as in FIG. Range.

In the example of FIG. 2, the outlet (path 40) for the oxygen-enriched liquefied air is not located at the bottom of the lower tower, but is set at a position one to several steps above the bottom of the lower tower. The reason for this is to reduce the contents of trace amounts of carbon dioxide and hydrocarbons which are mixed and concentrated in the oxygen-enriched liquefied air. That is, by extracting the liquefied air from the upper stage from the bottom of the column, the content of the trace impurities can be significantly reduced,
This is because the possibility of further concentration and precipitation in the crude argon column condenser to cause danger can be prevented.

Next, a second embodiment will be described with reference to FIG. As described above, a reversing heat exchanger 8 'different from the type shown in FIGS. 1 and 2 is used as the main heat exchanger. The compressed air from the conduit 5 is introduced through the four-way switching valve 70 into one of the flow paths 81a and 81b that are used for switching, and is returned gas from the rectification tower flowing through the adjacent flow paths 81c and 81d, ie, product nitrogen. It exchanges heat with gas and product oxygen gas and is cooled. At the same time, moisture and carbon dioxide contained in the wall surface of the flow path 81a are precipitated and removed, and are led out from the cold end, and are introduced into the lower part of the lower tower 14 through the conduit 9 via the return valve 82.

A part of the air passing through the return valve 82 flows from the conduit 84 through the valve 85 through the reheating passage 86 of the reversing heat exchanger 8 ', and is heated to the intermediate temperature to be extracted. It is introduced into the turbine 11, expanded and depressurized, cooled down to almost the liquefaction temperature, and introduced into the upper tower 15.

98% of nitrogen derived from the upper part of the upper tower 15
Waste gas enters the flow passage 81b of the reversing heat exchanger 8 'through the conduit 87, the subcooler 26, the conduit 88, the check valve 83, and the conduit 88', and exchanges heat with the raw air in the flow passage 81a. As the temperature rises, the water and carbon dioxide adhering to the wall surface of the flow path 81b in the previous cycle are volatilized, and the vaporized water and carbon dioxide are led out of the system through the conduit 89.

Since the respective channels of the reversing heat exchanger 8 'perform both the functions of heat exchange and the removal of impurities as described above, precision in controlling the temperature distribution in the channels during operation is strictly required. ing. The exhausted nitrogen gas is supplied to the subcooler 2
After applying the refrigeration to the oxygen-enriched liquefied air via 6 and being introduced into the reversing heat exchanger 8 ', the balance of the flow rates of these fluids directly affects the temperature balance. Therefore, it is essential that the flow rates and temperatures of these fluids are always stable during operation of the apparatus.

The operation of the crude argon column 17 is performed while monitoring the purity of the produced crude argon, and the amount of the oxygen-enriched liquefied air supplied is adjusted by the valve 31. When the apparatus is temporarily stopped and restarted as described above, when the supply of the oxygen-enriched liquefied air is stopped in order to first stop the operation of the crude argon column 17, the supercooler 26, the reversing heat exchange The temperature balance of the vessel 8 'is lost, and it becomes difficult to operate the whole apparatus stably.

Therefore, also in this type of air separation device, it is possible to improve the above disadvantages by providing the bypass path and the bypass valve as in the first embodiment. That is, a bypass flow path 45a and a bypass valve 46a connecting the flow path 30 of the oxygen-enriched liquefied air to the crude argon condenser 33 and the conduit 28 to the upper tower 15, or the oxygen-enriched liquefied air to the crude argon condenser 33 Of the unvaporized oxygen-enriched liquefied air from the crude argon condenser 33 to the flow path 43 and the bypass valve 46a 'or the bypass to the flow path 42 of the vaporized oxygen-enriched liquefied air. Channel 47a
And the bypass valve 48a. Furthermore, a bypass flow path 49a and a bypass valve 50a from the oxygen-enriched liquefied air flow path 30 directly to the upper tower 15 are provided.

By providing any one of these bypass paths and bypass valves, even when the supply of oxygen-enriched liquefied air to the crude argon condenser is stopped when the apparatus is temporarily stopped, the function of the subcooler is substantially reduced. The same state can be maintained, and the maintenance of the temperature balance of the reversing heat exchanger 8 'and the reduction of the time required for the apparatus to temporarily stop and restart can be achieved.

Next, a third embodiment in which the present invention is applied to an air liquefaction / separation apparatus having an argon purification system provided with a deacidification tower will be described with reference to FIG. The processes from the main rectification column 13 to the crude argon column 17 are the same as those in FIG. The crude argon column 17 has no condenser, and the liquid crude argon from the bottom of the deoxidizing column 90 flows down from the top of the column as a reflux liquid and gas-liquid contact is performed.

From the top of the crude argon column 17, 98% to 99% of argon is supplied to the deoxidizing column 90 through a path 97.
At the bottom of the tower. The argon gas that has risen while rectifying the gas in the deoxidation tower 90 by gas-liquid contact with the descending liquid reaches the top of the tower and the oxygen content decreases from about 1 ppm to about 1 ppb. The deoxygenated argon flowing from the top to the conduit 98 is supplied to the condenser 9
4, liquefied and led out to a conduit 99 to be divided into two parts, one of which is sent from a conduit 100 to a high-purity argon column (not shown) in the next step. The other of the two parts enters the deoxidation tower 90 again through the conduit 101, becomes a reflux liquid, and descends in the tower. The liquid that has descended to the bottom of the column is evaporated in the reboiler 91 and rises in the column together with the crude argon gas from the conduit 97. The liquid crude argon at the bottom of the column is led out from the conduit 102 and is supplied to the conduit 1 by the liquid pump 103.
The liquid is sent to the top of the crude argon column 17 via the liquid crystal 04 and becomes a reflux liquid of the crude argon column 17 as described above.

The cooling source of the condenser 94 of the deoxidizing tower 90 is connected to the bottom of the lower tower 14 or the first through several stages from the bottom of the conduit 4.
Oxygen-enriched liquefied air derived via 0 or 40 '. The liquefied air enters a reboiler 91 provided at the bottom of the deoxidizing tower 90, exchanges heat with the bottom liquid of the deoxidizing tower 90, becomes a supercooled state, and is led to a conduit 92. Next, the gas is expanded by the valve 93, and the temperature is lowered and introduced into the condenser 94, which exchanges heat with the deoxidized argon at the top of the deoxidizing column, vaporizes and leads to the conduit 95, and is introduced into the upper part of the upper column. .

Also in this type of air separation device, it is possible to improve the above disadvantages by providing a path for bypassing the condenser 94 and a bypass valve as in the first embodiment. That is, a bypass path 45b and a bypass valve 46b connecting the conduits 40 and 40 'of the oxygen-enriched liquefied air to the condenser 94 and the conduit 28 to the upper tower 15 can be provided. Further, a bypass passage 4 connecting the conduit 40 of the oxygen-enriched liquefied air to the deoxidizing tower condenser 94 and the flow path 96 of the non-evaporated oxygen-enriched liquefied air derived from the deoxidizing tower condenser 94.
5b 'and a bypass valve 46b' can also be provided. Further, the conduit 40 and the flow path 95 of the vaporized oxygen-enriched liquefied air
A bypass path 47b and a bypass valve 48b may be provided. Furthermore, a bypass path 49b from the conduit 40 for the oxygen-enriched liquefied air directly to the upper tower 15
And its bypass valve 50b.

By providing any one of these bypass paths and bypass valves, exactly the same effects as in the case of the first embodiment shown in FIG. 1 can be obtained. That is, when suspending / restarting the entire apparatus, the restarting time can be significantly reduced.

Embodiment 1 The air amount 185,00 employing the process of Embodiment 1 (FIG. 1, provided with a bypass route 45 and a bypass valve 46).
In the apparatus of 0 Nm ³ / h, when the whole apparatus is temporarily stopped and restarted, the bypass valve 46 is opened, the valve 31 is gradually closed, and the operation is performed for 2 hours. Stopped the whole. After 8 to 24 hours, restarting of the apparatus was started, and the time required to reach a steady state of operation, that is, the time required to generate the rated amount of product oxygen having the rated purity (99.6%) was about 1 hour. This is equivalent to about one-fifth of the time required for the temporary stop / restart in the normal device that does not perform the stopping method using the above-described bypass valve according to the present invention. became.

Embodiment 2 The air amount 185 employing the process of Embodiment 2 (FIG. 3, provided with a bypass passage 45a and a bypass valve 46a)
In the apparatus of 000 Nm ³ / h, when the whole apparatus is temporarily stopped and restarted, the bypass valve 46 a is opened, the valve 31 is closed, and the operation is performed for 2 hours. Stopped. After 7 days, restart the device,
The time required to reach the steady operating state (the time required to generate the rated purity of product oxygen and the rated amount, as described above) was about 2 hours. This is equivalent to about one third of the time required for the temporary stop / restart in the normal device that does not perform the stop method using the above-described bypass valve according to the present invention. became.

[0071] Example 3 embodiment 3 of a process air volume employing a packed column to the upper column and the crude argon column (Fig. 4, the bypass passage 45b, and that a bypass valve 46b) 185,000Nm ³ /
In the apparatus of h, when the entire apparatus is temporarily stopped and restarted, the bypass valve 46b is opened and the valve 93 is gradually closed,
After the operation of the liquid crude argon pump 103 was stopped and the operation was performed for 2 hours, the raw air compressor 2 was stopped to stop the entire apparatus. After about 24 hours, restarting of the apparatus was started, and the time required for the main rectification column to reach a steady operation state (the time until the rated purity of product oxygen and the time until the generation of the rated amount as described above) was about 3 hours. This corresponds to about three-fifths to four-fourths of the time required for the suspension / restart in the apparatus using the packed tower that does not perform the stopping method using the bypass valve according to the present invention.

[0072]

As described above, according to the present invention, the oxygen-enriched liquefied air supplied to the crude argon column condenser or the deoxidation column condenser can be bypassed and sent to the upper column. The time required for stop / restart can be reduced. In addition, the operation of the main rectification column alone can be easily performed by stopping the operation of the argon purification system, and the increase / decrease amount operation is easy and the increase / decrease amount width is large. In the apparatus using the reversing heat exchanger, the operation of the argon collection system and the operation of the main rectification column, particularly the temperature control of the reversing heat exchanger, can be performed without mutual influence. Become.

[Brief description of the drawings]

FIG. 1 is a system diagram of an embodiment of an air liquefaction / separation apparatus provided with a bypass path and a bypass valve for carrying out the method of the present invention.

FIG. 2 is a system diagram of another embodiment of the air liquefaction / separation apparatus provided with a bypass path and a bypass valve for carrying out the method of the present invention.

FIG. 3 is a system diagram of another embodiment of the air liquefaction / separation apparatus provided with a bypass path and a bypass valve for carrying out the method of the present invention.

FIG. 4 is a system diagram of another embodiment of an air liquefaction / separation apparatus provided with a bypass path and a bypass valve for carrying out the method of the present invention.

[Explanation of symbols]

2 ... air compressor 4 ... aftercooler 6 ... MS adsorber (pretreatment device) 8 ... main heat exchanger 8 '... reversible heat exchanger 13 ... main rectification tower (double rectification tower) 14 ... lower tower 1
5: Upper tower 17: Crude argon tower 90: Deoxidizer tower 33
... crude argon condenser 94 ... deoxidation tower condenser 91 ... deoxidation tower reboiler 11 ... expansion turbine 16 ... main condensing evaporator 26 ... supercooler 24 ... liquefied nitrogen storage tank 66 ... liquefied oxygen storage tank 103 ... liquefied crude argon pump 22 , 27,
31, 93 ... expansion valves 45, 45a, 45a ', 45b, 4
5b ', 47, 47a, 47b, 49, 49a, 49b ... bypass paths 46, 46a, 46a', 46b, 46b ', 4
8, 48a, 48b, 50, 50a, 50b ... bypass valve
1, 3, 5, 7, 9, 10, 12, 18, 19, 20,
21, 23, 25, 28, 30, 32, 36, 37, 3,
8, 39, 40, 42, 43, 60, 61, 62, 6
3, 64, 65, 87, 84, 87, 88, 88 ', 8
9, 92, 95, 96, 97, 98, 99, 100, 1
01, 102, 104, ... conduit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiaki Matsuo 1 Nishinosu, Oita, Oita City, Nippon Steel Corporation Oita Steel Works Co., Ltd. Oita Sanso Center Co., Ltd. F term (reference) 4D047 AA08 AB01 AB02 AB04 BB01 BB03 DA06 DA12 EA01

Claims (14)

[Claims] 1. An air liquefaction / separation apparatus comprising a lower tower, an upper tower, and a crude argon tower, wherein the air is liquefied and rectified to collect oxygen, nitrogen, argon and the like. An oxygen-enriched liquefied air introduction path to be led out and introduced into the crude argon column condenser; and the unevaporated oxygen-enriched liquefied air or evaporated oxygen-enriched air derived from the crude argon column condenser to the upper tower. A coarse argon column condenser bypass path connecting an introduction path or a path for extracting oxygen-enriched liquefied air from the lower tower lower part and introducing the oxygen-enriched liquefied air to the upper tower upper part, wherein a bypass valve is provided in the path. Air liquefaction separator. 2. An air liquefaction / separation apparatus comprising a lower tower, an upper tower, and a crude argon tower, wherein the air is liquefied and rectified to collect oxygen, nitrogen, argon and the like. A route for leading out and introducing the crude argon column condenser, a crude argon column condenser bypass route for branching the oxygen-enriched liquefied air introduction route and introducing the oxygen-enriched liquefied air to the upper column upper part, An air liquefaction / separation device, wherein a bypass valve is provided in the path. 3. An air liquefaction / separation apparatus comprising a lower tower and an upper tower, a crude argon tower and a deoxidizing tower, which liquefies air to collect oxygen, nitrogen, argon and the like. An oxygen-enriched liquefied air introduction path for deriving the deoxidizing liquid air and introducing it to the deoxidizing tower condenser; and converting the unevaporated oxygen-enriched liquefied air or evaporated oxygen enriched air derived from the deoxidizing tower condenser. A deoxidation tower condenser bypass path connecting a path for introduction to the upper tower or a path for extracting oxygen-enriched liquefied air from the lower part of the lower tower and introducing it to the upper part of the upper tower was provided, and a bypass valve was provided in the path. An air liquefaction separation device characterized by the above-mentioned. 4. An air liquefaction / separation apparatus comprising a lower tower and an upper tower, a crude argon tower, and a deoxidizing tower, wherein the air is liquefied and rectified to collect oxygen, nitrogen, argon and the like. A deoxygenator condenser bypass path for branching off the oxygen-enriched liquefied air introduction path and introducing oxygen-enriched liquefied air to the upper part of the upper tower; And a bypass valve is provided in the bypass path. 5. The air liquefaction / separation apparatus according to claim 1, wherein the main heat exchanger is a reversing heat exchanger (reversible heat exchanger). Air liquefaction separator. 6. A low-temperature outlet side of a supercooler provided in the oxygen-enriched liquefied air outlet path, wherein a bypass path and a bypass valve for the oxygen-enriched liquefied air outlet path are provided. Item 6. The air liquefaction separation device according to Item 5. 7. The air liquefaction / separation apparatus according to claim 1, further comprising a pretreatment apparatus for removing water, carbon dioxide, and the like in the raw air. Air liquefaction separator. 8. The air liquefaction / separation apparatus according to claim 1, wherein at least one of the lower tower, the upper tower, the crude argon tower and the like is a packed tower. 9. The air liquefaction / separation apparatus according to claim 3, wherein at least one of the lower tower, the upper tower, the crude argon tower, the deoxygenation tower and the like is a packed tower. 10. The air liquefaction / separation apparatus according to claim 1, wherein a position of a lower portion of the lower column from which the oxygen-enriched liquid air is led is a bottom of the lower column. 11. The lower tower from which the oxygen-enriched liquid air is led out is located one to several stages above the bottom of the lower tower. 2. The air liquefaction separation device according to claim 1. 12. Air is compressed, purified, cooled, and sequentially introduced into a double rectification column, a crude argon column, etc., for liquefied rectification and separation.
An air liquefaction separation method of collecting at least oxygen and argon as products, wherein an argon raw material gas derived from the middle part of the upper column of the double rectification column is introduced into the lower portion of the crude argon column, and the oxygen derived from the lower portion of the lower column of the double rectification column. In an air liquefaction method for purifying argon by introducing enriched liquefied air into a crude argon column condenser, the air liquefaction and separation apparatus is temporarily stopped and restarted.
The supply of oxygen-enriched liquefied air introduced into the crude argon column condenser with oxygen-enriched liquefied air derived from the lower part of the double rectification column is first stopped, and after temporarily operating only with the double rectification column, the compressed raw material An air liquefaction / separation method, wherein the supply of air is stopped, and a restarting operation is started from a state in which liquefied oxygen is stored at the bottom of the upper tower when restarting. 13. Air which compresses, purifies, cools, introduces air into a double rectification column, a crude argon column, a deoxidization column, etc., sequentially performs liquefaction rectification and collects at least oxygen and argon as products. A liquefaction separation method, in which the argon raw material gas derived from the upper part of the double rectification tower is introduced into the lower part of the crude argon column, and the oxygen-enriched liquefied air derived from the lower part of the double rectification tower is removed from the deoxygenation tower condenser. In the air liquefaction separation method of purifying with argon by introducing to the deliquefaction tower, when the air liquefaction separation apparatus is temporarily stopped and restarted, First, the supply of oxygen-enriched liquefied air to be introduced into the condenser was stopped, and the supply of liquid crude argon from the bottom of the deoxidation tower was stopped. Stop supply and restart Liquefied oxygen stored in the upper column bottom, and the air liquefaction separation method characterized by liquefying crude argon deoxygenated bottoms starts startup operation from a state of being 貯流. 14. The method according to claim 12, wherein a position of a lower portion of the lower tower from which the oxygen-enriched liquid air is led is a stage one to several stages higher than a bottom of the lower tower.
The air liquefaction separation method according to the above paragraph.