JP2012045507A - Continuous dehydration method of liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous dehydration method for removing moisture from liquid containing water efficiently and inexpensively.SOLUTION: The continuous dehydration method of raw material liquid containing moisture includes: a process (1) of supplying raw material liquid or vapor originated from the raw material liquid to one end of an adsorption tube filled with a moisture adsorbent and recovering effluent from the other end of the adsorption tube; a process (2) of measuring a moisture concentration in the effluent and calculating a cumulative moisture concentration; a process (3) of stopping the supply of the raw material liquid or vapor originated from the raw material liquid when the cumulative moisture concentration in the effluent has reached the predetermined concentration or higher in the process (2) and liberating the moisture from the adsorbent in the adsorption tube; a process (4) of supplying the vapor remaining in the adsorption tube to a distillation column and recovering concentrated liquid from the overhead of the distillation column; and a further process (5) of returning the concentrated liquid to the process (1).

Description

  The present invention relates to a continuous liquid dehydration method using an adsorbent.

  As a method for removing water from a liquid containing water (hydrous liquid), there are a batch-type dehydration method and a continuous dehydration method.

  The batch-type dehydration method is a method of removing moisture from a water-containing liquid by, for example, putting a molecular sieve and a water-containing liquid into a flask, a test tube, or the like and adsorbing only water to the molecular sieve. The batch-type dehydration method is usually used when a necessary amount of liquid is dehydrated as necessary, and thus is rarely used industrially and frequently used in a laboratory.

  Unlike the batch-type dehydration method, the continuous dehydration method is used to obtain a large amount of liquid from which moisture has been removed on an industrial scale or the like. For example, the method described in Patent Document 1 is a method of dehydrating by pressurizing a water-containing liquid in a vapor state, and requires high temperature and high pressure conditions. A large amount of energy is required to pressurize the hydrated liquid in a vapor state, and a special device and container such as a heating / pressurizing device and a heat-resistant / pressure-resistant vessel are required, leading to an increase in cost.

JP 2008-55386 A

  An object of the present invention is to provide a continuous dehydration method that efficiently removes moisture from a water-containing liquid at low cost.

  The present invention provides a continuous dehydration method for a raw material liquid containing moisture, the method comprising: (1) supplying the raw material liquid or vapor derived from the raw material liquid to one end of an adsorption tube filled with a moisture adsorbent. A step of recovering an effluent from the other end of the adsorption tube, and (2) a method of calculating a cumulative moisture concentration by measuring a moisture concentration in the effluent, and in the step (2), When the accumulated water concentration in the effluent becomes equal to or higher than a predetermined concentration, (3) the supply of the raw material liquid or the vapor derived from the raw material liquid is stopped, and the water is released from the adsorbent in the adsorption pipe. A step, (4) a step in which the vapor remaining in the adsorption pipe is supplied to a distillation column, and a concentrated solution is recovered from the top of the distillation column; and (5) the concentrated solution is mixed with the raw material liquid; The method further includes returning to the step (1).

  In one embodiment, in the step (3), the step of extracting and collecting the staying liquid in the adsorption tube, and the step of supplying the staying liquid to one end of the adsorption tube after the step (4) are further performed. Including.

  In one embodiment, the step (4) is performed by heating the inside of the adsorption tube to a temperature higher than room temperature and reducing the pressure.

  In one embodiment, the step (4) is carried out at atmospheric pressure or reduced pressure after purging the inside of the adsorption tube with gas.

  In another embodiment, two or more adsorption tubes are used.

  In one embodiment, three or more adsorption tubes are used, and in the step (5), the staying liquid is supplied to one end of an adsorption tube different from the adsorption tube from which the staying liquid has been drawn.

  ADVANTAGE OF THE INVENTION According to this invention, the continuous dehydration method which removes a water | moisture content from a water-containing liquid efficiently at low cost can be provided.

It is the schematic which shows one embodiment of the dehydration system used for the dehydration method of this invention. It is the schematic which shows the other embodiment of the dehydration system used for the dehydration method of this invention. It is the schematic which shows the embodiment of the dehydration system used for the conventional dehydration method.

  The dehydration method of the present invention includes (1) a step of supplying a raw material liquid or vapor derived from a raw material liquid to one end of an adsorption tube filled with a moisture adsorbent, and collecting an effluent from the other end of the adsorption tube; ) A method including a step of periodically sampling the effluent and measuring a water concentration in the effluent to calculate a cumulative water concentration. In step (2), the cumulative water concentration in the effluent is a predetermined concentration or more. (3) a step of stopping the supply of the raw material liquid or the vapor derived from the raw material liquid to release moisture from the adsorbent in the adsorption tube, and (4) the vapor remaining in the adsorption tube is supplied to the distillation column. A step of recovering the concentrate from the top of the distillation column, and (5) a step of mixing the concentrate with the raw material liquid and returning to the step (1).

(Process (1))
In the step (1), a raw material liquid containing moisture or vapor derived from the raw material liquid (hereinafter sometimes simply referred to as “raw material liquid”) may be referred to as a moisture adsorbent (hereinafter simply referred to as “adsorbent”). Is supplied to one end of an adsorption tube filled with a), and the effluent is recovered from the other end of the adsorption tube.

  It does not specifically limit as a raw material liquid containing a water | moisture content, For example, the liquid mixture of an organic solvent and water is mentioned. Preferably, an azeotropic mixture in which water cannot be completely removed by distillation is exemplified. Examples of the organic solvent include lower alcohols such as methanol, ethanol and isopropanol; aldehydes such as acetaldehyde and propionaldehyde; ketones such as acetone and methyl ethyl ketone; organic acids such as formic acid and acetic acid.

  The water concentration in the raw material liquid is not particularly limited, and is preferably 1% by mass to 15% by mass. When the dehydration method of the present invention is used, an effluent (product) that is efficiently anhydrous (for example, the water concentration is less than 0.5% by mass) is obtained from the raw material liquid.

  The adsorbent is not particularly limited as long as it can adsorb moisture, and examples thereof include zeolite (molecular sieve) and silica gel. A honeycomb-shaped adsorbent described in Patent Document 1 can also be used. Commercially available adsorbents include, for example, molecular sieve 13X (manufactured by Union Showa Co., Ltd.), molecular sieve 3A pellet 1.6 (manufactured by Union Showa Co., Ltd.), Hanicle MSX and MSA (manufactured by NICHIAS Corporation), and the like. It is done.

  The adsorption tube is filled with an adsorbent so that the raw material liquid and the adsorbent can come into contact with each other. The adsorption tube has, for example, a hollow columnar structure such as a cylindrical shape.

  The method for supplying the raw material liquid to one end of the adsorption tube is not particularly limited. For example, it can be supplied using a pump, a valve or the like. When the adsorption tube is installed perpendicular to the ground and used, the raw material liquid is preferably supplied from the lower end of the adsorption tube.

  The supply speed of the raw material liquid can be appropriately set according to the moisture concentration in the raw material liquid, the size of the adsorption tube, and the like. When supplying in a liquid state, it is preferably supplied to the adsorption tube at a flow rate of 0.5 mL / h to 4 mL / h per 1 g of the adsorbent. When supplying in the state of steam, it is preferably supplied to the adsorption tube at a flow rate of 0.1 mL / h to 4 mL / h per 1 g of the adsorbent. For example, when dehydrating hydrous ethanol, a flow rate of about 1 mL / h per 1 g of adsorbent (liquid state) or a flow rate of about 0.19 mL / h per 1 g of adsorbent (vapor state) is preferable.

  The supply of the raw material is performed at room temperature in the liquid state, and is performed at a temperature equal to or higher than the boiling point of the supplied raw material in the vapor state. In order to make a raw material into a vapor | steam state, the full evaporator as shown, for example in FIG. 1 is used. When the raw material is supplied in a liquid state, moisture adsorption may be performed at room temperature or may be performed by heating. Preferably, it is performed at about 20 ° C to 98 ° C.

  The effluent (product) from which moisture has been removed by the adsorbent in the adsorption tube flows out from the other end of the adsorption tube and is collected.

(Process (2))
In step (2), the water concentration in the effluent flowing out from the other end of the adsorption tube in step (1) is measured to calculate the cumulative water concentration. As a method of measuring the moisture concentration, for example, a density meter (sensor) is installed at the outlet and the density of the effluent is continuously measured to determine the moisture concentration. The effluent is periodically sampled and curled. Examples include a method using a Fischer moisture meter and a portable density / specific gravity meter. Cumulative moisture concentration is calculated from the measured value of moisture concentration. The cumulative water concentration is a value obtained by dividing the integrated value of the measured water concentration by the time elapsed from the start of measurement. When the effluent is sampled periodically to measure the water concentration, it is the average value of the measured values from the start of sampling.

  When the accumulated water concentration exceeds the predetermined concentration in step (2), the process proceeds to steps (3) to (5) described later.

  The predetermined concentration of the cumulative moisture concentration for determining whether or not to proceed to steps (3) to (5) described later is not particularly limited, and can be set as appropriate according to the use of the effluent (product). For example, when the liquid is used as an anhydrous product, the predetermined concentration of the cumulative moisture concentration is preferably set to less than 0.5% by mass.

(Process (3))
In the step (3), the supply of the raw material liquid or the vapor derived from the raw material liquid is stopped, and moisture is desorbed from the adsorbent in the adsorption tube. As the supply of the raw material liquid proceeds, the moisture adsorbed on the adsorbent increases, and the moisture adsorbing ability of the adsorbent decreases. As a result, the water concentration in the effluent recovered in step (1) increases.

  A method for releasing moisture from the adsorbent is not particularly limited. For example, a method in which the inside of the adsorption tube is heated to a temperature higher than room temperature (for example, 100 ° C. to 140 ° C.) and finally depressurized to about 50 mmHg to desorb moisture from the adsorbent; And a method of releasing moisture from the adsorbent by purging with an inert gas such as nitrogen) and then reducing the pressure to atmospheric pressure or finally about 50 mmHg.

  In order to heat the inside of the adsorption tube, a heating device (jacket) or the like that can supply a heat medium such as steam to the outer wall surface of the adsorption tube can be used.

  In order to reduce the pressure in the adsorption tube, a vacuum pump, a blower or the like is used. When the apparatus is small, a vacuum pump is preferably used. When the apparatus is large, several blowers arranged in series are preferably used.

  As described above, the moisture absorbing ability of the adsorbent can be recovered by releasing the moisture from the adsorbent.

  Preferably, when the accumulated water concentration in the recovered effluent exceeds a predetermined concentration, the supply of the raw material liquid to the adsorption tube is stopped, and the remaining liquid remaining in the adsorption tube is extracted and collected. The method for extracting and collecting the staying liquid is not particularly limited. For example, it can be extracted and collected using a pump, a valve or the like. Further, nitrogen gas may be introduced into the adsorption tube, and the staying liquid remaining in the adsorption tube may be pushed out by the pressure of the nitrogen gas.

(Process (4))
In step (4), the vapor remaining in the adsorption pipe is supplied to the distillation column, and the concentrated liquid is recovered from the top of the distillation column.

  The vapor remaining in the adsorption pipe (raw material liquid vapor and water vapor) is supplied to the distillation column. The vapor is supplied to the bottom of the distillation column (column bottom) and distilled, and the vapor mainly containing the raw material vapor is liquefied by a condenser (for example, a cooler) at the top (top) of the distillation column. The steam mainly containing water vapor is liquefied and stays at the bottom of the tower.

  As described above, the vapor mainly containing the raw material liquid vapor is liquefied by a condenser (for example, a cooler or the like) and refluxed to a distillation column to be concentrated and recovered as a concentrated liquid. This concentrated liquid is again used as a raw material liquid.

  Thus, an anhydride can be obtained in high yield from a water-containing liquid by using the concentrated liquid again as a raw material liquid.

(Process (5))
In step (5), the concentrated liquid is mixed with the raw material liquid, and the process returns to step (1).

  Preferably, the staying liquid recovered in step (3) is supplied to one end of the adsorption tube, and after the staying liquid is supplied, the process returns to step (1) and the raw material liquid mixed with the concentrated solution is supplied to one end of the adsorption tube. To do. As with the raw material liquid, the staying liquid is preferably supplied by adjusting the supply rate (flow rate) with a valve or the like.

  In the dehydration method of the present invention, the raw material liquid can be continuously dehydrated by the above steps (1) to (5).

  The dehydration method of the present invention preferably uses two or more adsorption tubes as shown in FIG. In particular, the method using two adsorption tubes as shown in FIG. 1 is preferably used when the raw material liquid is used as vapor.

  More preferably, the dehydration method of the present invention uses three or more adsorption tubes. In this case, in step (5), the staying liquid is supplied to one end of an adsorption pipe different from the adsorption pipe from which the staying liquid has been extracted.

  For example, when using three adsorption tubes (a first adsorption tube, a second adsorption tube, and a third adsorption tube), the staying liquid recovered from the first adsorption tube is supplied to the second adsorption tube, It is preferable that the staying liquid recovered from the second adsorption tube is supplied to the third adsorption tube, and the staying liquid recovered from the third adsorption tube is supplied to the first adsorption tube. Thus, by supplying the collected staying liquid to an adsorption tube different from the collected adsorption tube, it becomes possible to dehydrate more continuously.

Example 1
Hereinafter, one embodiment of the dehydration method of the present invention will be described with reference to the dehydration system shown in FIG.

  The dehydration system shown in FIG. 2 is a system using three adsorption towers, and is composed of adsorption towers 21, 31, 41, raw material tank 11, intermediate tank 12, effluent tank 13, vacuum pump 14, condenser 15, and condensate tank. 16. A distillation column 17 and a water tank are provided.

  The adsorption towers 21, 31, and 41 have a double tube structure including an inner cylindrical tube filled with an adsorbent and an outer cylindrical tube covering the inner cylindrical tube. The inner cylindrical tube has an inner diameter of 200 mm and a length of 700 mm. The outer cylindrical tube has an inner diameter of 250 mm and a length of 700 mm. A heat medium such as steam or hot water can be supplied to the gap between the inner cylindrical tube and the outer cylindrical tube, and the inner cylindrical tube can be heated.

  A net was installed in the lower part of the cylindrical tube inside the adsorption towers 21, 31, 41, and about 3500 g of adsorbent (manufactured by Union Showa Co., Ltd .: Molecular Sieve 3A pellet 1.6) was packed thereon. After filling with the adsorbent, the inside cylindrical tube was filled with nitrogen.

(Preprocessing)
Before dehydrating the raw material liquid, the moisture adsorbed on the adsorbent was released. The valve 285 was opened and the valve 286 was closed, and 0.45 Mpa of steam was supplied to the gap between the inner cylindrical tube and the outer cylindrical tube of the adsorption tower 21 to heat the adsorption tower 21. Then, the valve 281 was opened in the ac direction, the valve 282 was opened in the ba direction, the valve 283 was closed, and the valve 284 was opened, and the vacuum pump 14 was operated. The vacuum pump 14 is provided between the distillation column 17 and the valve 282. Water vapor was sucked together with nitrogen gas by the vacuum pump 14 and supplied to the distillation tower 17, and the condensed water was stored in a water tank.

  The distillation column 17 has a cylindrical shape with an inner diameter of 50 mm and a height of 1000 mm, and is filled with a McMahon packing made of stainless steel to a height of 500 mm from the bottom.

  In addition, the internal temperature of the adsorption tower 21 changed from 100 ° C. to 120 ° C., and the temperature at the end of the desorption of water was about 100 ° C. near the upper portion of the adsorption tower 21 and about 20 ° C. near the lower portion.

  Also for the adsorption towers 31 and 41, the moisture adsorbed on the adsorbent was released in the same procedure as the adsorption tower 21.

(Operation of adsorption tower 21)
Next, the valve 284 was closed, the pressure in the adsorption tower 21 was reduced, and the raw material liquid was supplied. Further, the valve 285 was closed, the valve 286 was opened, and the supply of steam was stopped. As the raw material liquid, hydrous ethanol containing 90% by mass of ethanol and 10% by mass of water was used.

  The valve 281 was opened in the ab direction, and water-containing ethanol was supplied from the raw material tank 11 to the adsorption tower 21 using the pump 191.

  When the pressure in the adsorption tower 21 reached normal pressure, the valve 283 was opened to collect the effluent. Before the effluent is collected in the effluent tank 13, sampling is performed 3 to 5 mL several times, and the moisture concentration in the effluent is measured by a Karl Fischer moisture meter (AQV-2100S, manufactured by Hiranuma Sangyo Co., Ltd.). The cumulative water concentration was calculated. Moreover, the ethanol concentration was monitored with a portable density specific gravity meter (manufactured by Kyoto Electronics Co., Ltd., DA-130N) that can measure the ethanol concentration instantaneously. The predetermined concentration of the cumulative moisture concentration for determining whether or not to collect the effluent in the effluent tank 13 was set to be less than 0.5% by mass.

  When the cumulative water concentration exceeded 0.5% by mass, the recovery of the effluent was stopped, the valve 283 was closed, and the supply of hydrous ethanol was stopped.

  Next, the valve 289 was opened in the ac direction, the valve 282 was opened in the bc direction, and the staying liquid in the adsorption tower 21 was extracted and collected in the intermediate tank 12.

  After the accumulated liquid was extracted, the valve 285 was opened and the valve 286 was closed, and 0.45 Mpa of steam was supplied to the gap between the inner cylindrical tube and the outer cylindrical tube of the adsorption tower 21 to heat the adsorption tower 21. . Then, the valve 281 was opened in the ac direction, the valve 282 was opened in the ba direction, and the valve 284 was opened, and the vacuum pump 14 was operated. Distillation was performed by supplying the vapor and water vapor of ethanol remaining in the adsorption tower 21 to the distillation tower 17 by the vacuum pump 14.

  The vapor staying at the top of the distillation column 17 was cooled by a condenser 15 (cooling water at 5 ° C.), and the collected liquid was returned to the distillation column 17 as a reflux liquid while collecting the condensate in the condensate tank 16. When the ethanol concentration of the collected condensate was measured with a portable density specific gravity meter, it was about 90% by mass. In order to reuse this condensate as a raw material, it was returned to the raw material tank 11.

  The vapor condensate staying at the bottom of the distillation column 17 was collected in a water tank. The ethanol concentration of the collected condensate was about 30% by mass.

(Operation of adsorption tower 31)
The valve 384 was closed and the pressure in the adsorption tower 31 was reduced. Further, the valve 385 was closed, the valve 386 was opened, and the supply of steam was stopped. The valve 381 was opened in the ac direction, the valves 382 and 389 were opened in the bc direction, and the staying liquid extracted from the adsorption tower 21 and collected in the intermediate tank 12 was supplied to the adsorption tower 31 using the pump 192.

  When all the staying liquid was supplied to the adsorption tower 31, the valve 389 was opened in the ab direction. Next, the valve 381 was opened in the ab direction, and water-containing ethanol was supplied from the raw material tank 11 to the adsorption tower 31 using the pump 191.

  When the pressure in the adsorption tower 31 reached normal pressure, the valve 383 was opened to collect the effluent. Before the effluent was collected in the effluent tank 13, sampling was performed 3 to 5 mL several times, and the moisture concentration in the effluent was measured with a Karl Fischer moisture meter to calculate the cumulative moisture concentration. The predetermined concentration of the cumulative moisture concentration for determining whether or not to collect the effluent in the effluent tank 13 was set to be less than 0.5% by mass.

  When the cumulative moisture concentration exceeded 0.5% by mass, the recovery of the effluent was stopped, the valve 381 was opened in the ac direction, and the valve 383 was closed to stop the supply of hydrous ethanol.

  Subsequently, the valve 389 was opened in the ac direction, the valve 382 was opened in the bc direction, and the staying liquid in the adsorption tower 31 was extracted and collected in the intermediate tank 12.

  After extracting the staying liquid, the steam remaining in the adsorption tower 31 was supplied to the distillation tower 17 and distilled as in the case of the adsorption tower 21 described above. The ethanol concentration in the condensate recovered from the top of the distillation column 17 was about 90% by mass. This condensate was returned to the raw material tank 11. The ethanol concentration in the condensate recovered from the bottom of the distillation column 17 was 30% by mass.

(Operation of adsorption tower 41)
The valve 484 was closed and the pressure in the adsorption tower 41 was reduced. Further, the valve 485 was closed, the valve 486 was opened, and the supply of steam was stopped. The valve 481 was opened in the ac direction, the valves 482 and 489 were opened in the bc direction, and the staying liquid extracted from the adsorption tower 31 and collected in the intermediate tank 12 was supplied to the adsorption tower 41 using the pump 192.

  When all the staying liquid was supplied to the adsorption tower 41, the valve 489 was opened in the ab direction. Next, the valve 481 was opened in the ab direction, and water-containing ethanol was supplied from the raw material tank 11 to the adsorption tower 41 using the pump 191.

  When the pressure in the adsorption tower 41 reached normal pressure, the valve 483 was opened to collect the effluent. Before the effluent was collected in the effluent tank 13, sampling was performed 3 to 5 mL several times, and the moisture concentration in the effluent was measured with a Karl Fischer moisture meter to calculate the cumulative moisture concentration. The predetermined concentration of the cumulative moisture concentration for determining whether or not to collect the effluent in the effluent tank 13 was set to be less than 0.5% by mass.

  When the cumulative water concentration exceeded 0.5% by mass, the recovery of the effluent was stopped, the valve 483 was closed, and the supply of hydrous ethanol was stopped.

  Subsequently, the valve 489 was opened in the ac direction, the valve 482 was opened in the bc direction, and the staying liquid in the adsorption tower 41 was extracted and collected in the intermediate tank 12.

  After the staying liquid was extracted, the vapor remaining in the adsorption tower 41 was supplied to the distillation tower 17 in the same manner as in the case of the adsorption tower 21 to perform distillation. The ethanol concentration in the condensate recovered from the top of the distillation column 17 was about 90% by mass. This condensate was returned to the raw material tank 11. The ethanol concentration in the condensate recovered from the bottom of the distillation column 17 was 30% by mass.

(Operation of adsorption tower 21)
The valve 284 was closed and the pressure in the adsorption tower 21 was reduced. Further, the valve 285 was closed, the valve 286 was opened, and the supply of steam was stopped. The valve 281 was opened in the ac direction, the valves 282 and 289 were opened in the bc direction, and the staying liquid extracted from the adsorption tower 41 and collected in the intermediate tank 12 was supplied to the adsorption tower 21 using the pump 192.

  When all the staying liquid was supplied to the adsorption tower 21, the valve 289 was opened in the ab direction. Next, the valve 281 was opened in the ab direction, and water-containing ethanol was supplied from the raw material tank 11 to the adsorption tower 21 using the pump 191.

  Subsequently, the recovery of the effluent, measurement of the water concentration in the effluent, calculation of the cumulative water concentration, extraction and collection of the staying liquid were repeated.

  By using the three adsorption towers 21, 31, 41, the raw material supply process, the effluent recovery process, the moisture desorption process, the concentrated liquid recovery process, and the raw material resupply process are performed with a time difference in each adsorption tower. Yielded 99.5% by weight absolute ethanol with a recovery of about 90%. Thus, by using the method of the present invention, liquid can be dehydrated efficiently and continuously.

(Comparative Example 1)
Except for using the conventional dehydration method, that is, the dehydration system of FIG. 3 without the distillation column 17, dehydration of water-containing ethanol of 90% by mass of ethanol and 10% by mass of water was performed in the same procedure as in Example 1. It was. The recovery rate of absolute ethanol was about 60%.

  ADVANTAGE OF THE INVENTION According to this invention, the continuous dehydration method which removes a water | moisture content from a water-containing liquid efficiently at low cost can be provided. Therefore, the method of the present invention is useful in fields such as solvent purification.

DESCRIPTION OF SYMBOLS 11 Raw material tank 12 Intermediate tank 13 Outflow liquid tank 14 Vacuum pump 15 Condenser 16 Condensate tank 17 Distillation tower 191, 192 Pump 21 Adsorption tower 281-286, 289 Valve 31 Adsorption tower 381-386, 389 Valve 41 Adsorption tower 481-486 , 489 Valve

Claims (6)

A continuous dehydration method for a raw material liquid containing moisture,
(1) supplying the raw material liquid or the vapor derived from the raw material liquid to one end of an adsorption tube filled with a moisture adsorbent, and collecting the effluent from the other end of the adsorption tube; and (2) the effluent. Measuring the water concentration in the water and calculating the cumulative water concentration,
Including
In the step (2), when the accumulated water concentration in the effluent becomes a predetermined concentration or more,
(3) a step of stopping the supply of the raw material liquid or the vapor derived from the raw material liquid to release moisture from the adsorbent in the adsorption pipe;
(4) a step in which steam remaining in the adsorption pipe is supplied to a distillation column, and a concentrated liquid is recovered from the top of the distillation column; and (5) the concentrated liquid is mixed with the raw material liquid, and the step Returning to (1),
Further comprising a method.   The step (3) further includes a step of extracting and collecting the staying liquid in the adsorption tube, and a step of supplying the staying liquid to one end of the adsorption tube after the step (4). The method described.   The method according to claim 1 or 2, wherein the step (4) is performed by heating the inside of the adsorption tube to a temperature higher than room temperature and reducing the pressure.   The method according to claim 1 or 2, wherein the step (4) is performed at atmospheric pressure or reduced pressure after purging the inside of the adsorption tube with a gas.   The method according to claim 1, wherein two or more adsorption tubes are used.   5. The method according to claim 1, wherein three or more adsorption tubes are used, and in the step (5), the staying liquid is supplied to one end of an adsorption tube different from the suction tube from which the staying liquid has been extracted. The method according to any of the above sections.

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