JP6067368B2 - Adsorbent regeneration device, adsorbent regeneration method, carbon dioxide purification device, and carbon dioxide purification method - Google Patents

Description

  The present invention relates to an adsorbent regeneration device, an adsorbent regeneration method, a carbon dioxide purification device, and a carbon dioxide purification method.

Carbon dioxide (CO ₂ ) is used in various states in a gas state, and is used in a liquid state or a supercritical state, for example, in a process such as cleaning or drying. In recent years, it has been proposed to perform a cleaning process in a semiconductor device manufacturing process using liquid CO ₂ or supercritical CO ₂ .

To use the liquid CO ₂ or supercritical CO ₂ in a manufacturing process of semiconductor devices, relative to the point of use (e.g., cleaning device), the amount of impurities is extremely small high purity purified liquid CO ₂ or supercritical CO ₂ need to be supplied continuously. For example, Patent Document 1 discloses a circulation purification type fluid supply system. In this system, the liquid CO ₂ is vaporized, the CO circulatory _{system 2} gas is condensed again into liquid CO ₂ with is used, the CO ₂ by repeating the vaporization and condensation of CO ₂ in the circulation system Purity is increased.

On the other hand, in a semiconductor device manufacturing process, it is also required to collect and purify CO ₂ used at a use point and reuse it in the same manufacturing process. For example, Patent Document 2 discloses a regeneration and recovery apparatus that recovers and regenerates supercritical CO ₂ or liquid CO ₂ used in a cleaning apparatus or a drying apparatus.

By the way, in the circulation system as described above, CO ₂ is supplied as needed from the CO ₂ supply source such as a gas cylinder into the circulation system. However, the CO ₂ from the CO ₂ supply source has moisture, oil, or volatile properties. Impurities are included. Similar impurities are also contained in CO ₂ recovered from a cleaning device or a drying device used in a semiconductor device manufacturing process. In the fluid supply system described in Patent Document 1 and the regeneration and recovery apparatus described in Patent Document 2, CO ₂ is purified by using a gas-liquid separation means, a filtering means such as a filter, and the like. Then, it is difficult to sufficiently remove the above-described impurity.

Accordingly, included in the CO _2, water, oil or reliably remove impure material such as volatile impurities, as a method for purifying a high purity CO _2, the method of using the adsorbent has been proposed (for example, (See Patent Documents 3 and 4). In this method, it is possible to remove various impurity substances by appropriately selecting an adsorbent depending on the substance to be removed, processing conditions, and the like.

However, there is a limit to the adsorption capacity of the adsorbent, and when the adsorption capacity approaches the limit or the amount of adsorption exceeds a certain level, the impurity contained in CO ₂ cannot be sufficiently removed. Therefore, it is necessary to regenerate the adsorbent when the adsorbed amount reaches a certain level. As such an adsorbent regeneration method, for example, Patent Document 5 discloses a method of introducing an inert gas as a regeneration gas into an adsorption tower packed with an adsorbent.

JP 2006-326429 A JP 2005-281016 A Special table 2009-506967 Special table 2009-504383 JP 2003-117339 A

  When the regeneration gas is introduced into the adsorption tower to regenerate the adsorbent as in the regeneration method described above, the regeneration gas (inert gas) remains in the adsorption tower after regeneration of the adsorbent. When the adsorption treatment is resumed in this state, the inert gas remaining in the adsorption tower is contained in the purified gas, and the desired purity cannot be obtained. Therefore, before resuming the adsorption treatment, it is necessary to temporarily replace the inert gas remaining in the adsorption tower with the purified gas. At that time, some adsorbents generate heat when the purified gas is adsorbed. In this case, it is necessary to cool the adsorbent after the adsorbent regeneration process is completed and before the adsorption process is resumed.

  As a method of cooling the adsorbent, it is conceivable that the cooling gas is allowed to flow through the adsorption tower until the adsorbent is sufficiently cooled, but for this purpose, a large amount of cooling gas is consumed, which affects the cost. Becomes larger. In addition, it takes a considerable amount of time to re-cool the adsorbent that has generated heat by heat dissipation, and time loss becomes a problem.

  Accordingly, an object of the present invention is to suppress a decrease in adsorption capacity that may occur when the adsorption process is restarted after regeneration of the adsorbent without causing an increase in cost and time loss.

In order to achieve the above-described object, the adsorbent regeneration apparatus of the present invention includes at least one of zeolite, silica gel, activated alumina, and activated carbon that adsorbs impurities contained in carbon dioxide as a gas to be purified. An adsorbent regeneration apparatus, a regeneration gas supply means for supplying a regeneration gas to an adsorption tower packed with an adsorbent, a heating means for heating either the regeneration gas supplied to the adsorption tower or the adsorption tower, Replacement gas supply means for supplying carbon dioxide as a replacement gas to the adsorption tower, gas circulation means for circulating the replacement gas supplied to the adsorption tower along a circulation path including the adsorption tower, and circulation along the circulation path A cooling means for cooling the replacement gas, a gas discharge line connected to the adsorption tower via a gas discharge valve, for discharging the regeneration gas or replacement gas supplied to the adsorption tower, and a gas return The gas return line is connected to the adsorption tower via the gas supply line, and the regeneration gas heated by the heating means is supplied to the adsorption tower, or the regeneration gas is supplied to the adsorption tower heated by the heating means. The regeneration gas supplied to the adsorption tower is discharged from the gas discharge line to regenerate the adsorbent, and then the replacement gas is supplied to the adsorption tower to cool at least a part of the replacement gas along the circulation path. And control means for circulating while.

The adsorbent regeneration method of the present invention is an adsorbent regeneration method containing at least one of zeolite, silica gel, activated alumina, and activated carbon that adsorbs impurities contained in carbon dioxide as a gas to be purified. Then, the regeneration gas is heated and supplied to the adsorption tower filled with the adsorbent, and the heated regeneration gas is circulated through the adsorption tower, or the adsorption tower is heated and the regeneration gas is circulated through the heated adsorption tower. However, the regeneration gas that has flowed through the adsorption tower is discharged to the outside, and the adsorbent is regenerated, and after the adsorbent is regenerated, carbon dioxide as a replacement gas is supplied to the adsorption tower and remains in the adsorption tower. Replacing the regeneration gas with a replacement gas, and circulating at least a portion of the replacement gas while cooling along a circulation path including an adsorption tower.

Further, the carbon dioxide purification apparatus of the present invention is an adsorption tower packed with an adsorbent containing at least one of zeolite, silica gel, activated alumina, and activated carbon, which adsorbs impurities contained in carbon dioxide as a gas to be purified. And a regenerator for regenerating the adsorbent, wherein the regenerator includes a regenerative gas supply means for supplying a regenerative gas to the adsorption tower, a regenerative gas supplied to the adsorption tower, and an adsorption tower Heating means for heating one of them, a replacement gas supply means for supplying carbon dioxide as a replacement gas to the adsorption tower, and a gas circulation for circulating the replacement gas supplied to the adsorption tower along a circulation path including the adsorption tower Means, a cooling means for cooling the replacement gas circulating along the circulation path, and a gas discharge valve connected to the adsorption tower to discharge the regeneration gas or replacement gas supplied to the adsorption tower. A gas return line connected to the adsorption tower through a gas return valve and supplying a regeneration gas heated by the heating means to the adsorption tower, or heated by the heating means The regeneration gas supplied to the adsorption tower is discharged from the gas discharge line while supplying the regeneration gas to the adsorption tower, and after regenerating the adsorbent, the replacement gas is supplied to the adsorption tower, and at least the replacement gas is supplied. And control means for circulating a part while cooling.

The carbon dioxide purification method of the present invention includes a method for regenerating an adsorbent containing at least one of zeolite, silica gel, activated alumina, and activated carbon, which adsorbs impurities contained in carbon dioxide as a gas to be purified. In the regeneration method, the regeneration gas is heated and supplied to the adsorption tower filled with the adsorbent, and the heated regeneration gas is circulated through the adsorption tower, or the adsorption tower is heated and the regeneration gas is supplied to the heated adsorption tower. The regeneration gas that has flowed through the adsorption tower is exhausted to the outside while being recirculated, and after the adsorbent is regenerated, carbon dioxide as a replacement gas is supplied to the adsorption tower, And a step of replacing the remaining regeneration gas with a replacement gas and a step of circulating at least a part of the replacement gas while cooling along a circulation path including the adsorption tower.

  In such an apparatus and method, the replacement gas can be circulated while cooling along the circulation path including the adsorption tower. Thereby, even if it is a case where heat is generated when the replacement gas is adsorbed to the adsorbent, the adsorbent can be quickly cooled. In addition, the replacement gas for cooling is not wasted, so there is no risk of cost increase.

  As described above, according to the present invention, it is possible to suppress a decrease in adsorption capacity that may occur when the adsorption process is restarted after regeneration of the adsorbent, without incurring cost increase or time loss.

It is the schematic which shows the structural example of the carbon dioxide circulation supply system provided with the carbon dioxide refinement | purification apparatus with which this invention is applied. It is the schematic which shows the adsorption | suction apparatus in one Embodiment of this invention. It is a flowchart which shows the 1st regeneration method of the adsorbent in the adsorbent reproduction apparatus of this embodiment. It is a flowchart which shows the 2nd regeneration method of the adsorbent in the adsorbent reproduction apparatus of this embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

The present invention is suitable for an adsorption device for adsorbing and removing impurities contained in carbon dioxide (CO ₂ ), in particular, moisture, oil, or volatile impurities, and a carbon dioxide purification device equipped with the adsorption device. Applied. Such carbon dioxide purification unit, the carbon dioxide purification unit in a manufacturing process of a semiconductor device, in particular, purified while circulating CO _2, the purified CO ₂ circulation purification device for supplying the point of use, the point of use Examples include a recovery and purification apparatus that recovers the used CO ₂ and performs crude purification.

FIG. 1 is a schematic diagram illustrating a configuration example of a CO ₂ supply system of a semiconductor device manufacturing process including a carbon dioxide purification apparatus to which the present invention is applied. In the following, a semiconductor device cleaning apparatus will be described as an example of a use point, but the present invention is not limited to this, and a semiconductor device drying apparatus may be used.

CO ₂ supply system 1 is a system for supplying high purity CO ₂ in the cleaning device 2 as a point of use, purified while circulating CO _2, circulating purified apparatus for supplying purified CO ₂ in the cleaning apparatus 2 3 and a recovery and purification device 4 that recovers CO ₂ used in the cleaning device 2 and performs crude purification. The CO ₂ roughly purified by the recovery and purification device 4 is sent to the circulation purification device 3 where it is finally purified to high-purity CO ₂ that can be supplied to the cleaning device 2. Further, the CO ₂ supply system 1 is provided with a CO ₂ supply source 5 such as a gas cylinder for supplying CO ₂ to the circulation purification device 3.

The circulation purification apparatus 3 is composed of an evaporator that vaporizes liquid CO ₂ , a condenser that liquefies the vaporized CO ₂ gas again, a storage tank (none of which is shown) that stores the liquefied liquid CO _2, and the like. It has a line 3a. The circulation line 3a is provided with a plurality of filters (not shown) for removing fine particles contained in the liquid CO ₂ or CO ₂ gas. The cleaning device (use point) 2 is supplied with the liquid CO ₂ that has passed through the filter branched from the circulation line 3a. Moreover, CO ₂ from the CO ₂ supply source 5 are supplied to the condenser circulation line. Instead of the evaporator, other means for vaporizing the liquid CO ₂ may be provided.

On the other hand, the recovery and purification device 4 is a gas-liquid separator that separates and removes some of the impurities in the CO ₂ recovered from the cleaning device 2 in some cases and a condensation that separates and separates the separated CO ₂ gas. And a recovery line 4a composed of a storage tank (both not shown) for storing the liquefied liquid CO ₂ . The recovery line 4a is provided with a plurality of filters (not shown) for removing fine particles contained in the liquid CO ₂ or CO ₂ gas. The recovery line 4 a is connected to the front stage of the evaporator of the circulation purification device 3 so that the liquid CO ₂ after passing through the filter is supplied to the evaporator of the circulation purification device 3.

Further, in order to adsorb and remove impurities contained in CO ₂ , particularly moisture, oil, or volatile impurities, in the circulation line 3a of the circulation purification apparatus 3 and the collection line 4a of the collection purification apparatus 4 respectively. Adsorption devices 6 and 7 are provided. The adsorption devices 6 and 7 are provided in the subsequent stage of the evaporator in the circulation purification apparatus 3 and in the subsequent stage of the gas-liquid separator in the recovery and purification apparatus 4, and are vaporized by the evaporator or roughly purified by the gas-liquid separator. The impurities contained in the CO ₂ gas are adsorbed on the adsorbent and purified. The present invention is applied to these adsorption devices 6 and 7.

  FIG. 2 is a schematic view showing an embodiment of an adsorption apparatus to which the present invention is applied. The basic configurations of the adsorption devices 6 and 7 of the purification device 3 and the recovery and purification device 4 are the same, and the configuration shown in FIG. 2 is included in any of the adsorption devices 6 and 7.

Referring to FIG. 2, the adsorption device 10 includes an adsorption tower 11 filled with an adsorbent that adsorbs impurities contained in CO ₂ , and introduction of a gas to be refined for introducing CO ₂ gas to be purified into the adsorption tower. A line 12 and a purified gas discharge line 13 for discharging the CO ₂ gas purified by the adsorption tower 11 are provided. The to-be-purified gas introduction line 12 is connected to an evaporator or a gas-liquid separator (not shown) on the upstream side, and introduces the CO ₂ gas to be purified into the adsorption tower. The purified gas discharge line 13 is connected to a filter (not shown) on the downstream side, and purified CO ₂ gas is supplied to the condenser through the filter.

The adsorbent filled in the adsorption tower 11 may be anything that adsorbs moisture, oil, or volatile impurities contained in CO _2, and examples thereof include zeolite, silica gel, activated alumina, and activated carbon. For example, when used in the adsorption device 7 of the recovery and purification device 4, the CO ₂ recovered from the cleaning device 2 contains alcohols such as isopropyl alcohol (IPA) in particular. In that case, as the adsorbent, zeolite, activated alumina, and activated carbon are preferably used.

  Furthermore, the adsorption device 10 has an adsorbent regeneration device 20 for regenerating the adsorbent.

  An adsorbent regenerator (hereinafter also simply referred to as “regenerator”) 20 includes a gas introduction line 21 for introducing a regeneration gas or a replacement gas, which will be described later, into the adsorption tower 11, and a regeneration gas introduced into the adsorption tower or And a gas discharge line 22 for discharging the replacement gas. The gas discharge line 22 is provided with a gas discharge valve 22a.

  The regenerator 20 also has a regenerative gas supply line 23 for supplying a regenerative gas and a replacement gas supply line 24 for supplying a replacement gas. The regeneration gas supply line 23 and the replacement gas supply line 24 are connected to the gas introduction line 21 via the regeneration gas supply valve 23a and the replacement gas supply valve 24a, respectively. By switching the opening and closing of the regeneration gas supply valve 23a and the replacement gas supply valve 24a, either the regeneration gas or the replacement gas can be selectively introduced into the adsorption tower 11.

The regeneration gas supply line 23 supplies regeneration gas from a regeneration gas supply source (not shown) such as a cylinder. In the present embodiment, nitrogen (N ₂ ) gas is used as the regeneration gas. However, the present invention is not limited to this, and other inert gases such as argon gas can be used. The regeneration gas supply line 23 is provided with a heater (heating means) 25 for heating the regeneration gas.

On the other hand, the introduction of the replacement gas restarts the CO ₂ purification step (adsorption process) by the adsorption tower 11 in order to replace the regeneration gas introduced into the adsorption tower 11 in order to regenerate the adsorbent, as will be described later. Done before. Therefore, in this embodiment, the gas purified by the adsorption tower 11, that is, CO ₂ gas is used as the replacement gas. For the same reason, the purity of the replacement gas (CO ₂ gas) is preferably as high as possible. For example, high-purity CO ₂ gas obtained by normal operation after restarting the adsorption process, that is, purified gas discharge The purity is preferably equal to or higher than the purity of the CO ₂ gas discharged from the line 13. Therefore, the replacement gas supply line 24 may be connected to the purified gas discharge line 13 or may be connected to a supply source of higher purity CO ₂ gas.

  The regenerator 20 also has a gas return line 26 for returning the regeneration gas or replacement gas discharged from the adsorption tower 11 to the adsorption tower 11. The gas return line 26 connects the gas discharge line 22 upstream of the gas discharge valve 22 a and the gas introduction line 21, thereby forming a closed circulation path 30 including the adsorption tower 11. Furthermore, the regenerator 20 is provided in the gas return line 26, and is provided in the gas return line 26 in the same manner as a circulation pump (gas circulation means) 27 that circulates the regeneration gas or the replacement gas along the circulation path 30. And a cooling device (cooling means) 28 for cooling the regeneration gas or the replacement gas circulating in the passage 30. Although the cooling device 28 is provided on the upstream side of the circulation pump 27, the cooling device 28 may be provided on the downstream side of the circulation pump 27 as long as the circulating gas is cooled. The gas return line 26 is provided with a gas return valve 26a.

  Furthermore, the reproducing apparatus 20 has a controller (control means) 29 that controls the regeneration operation of the adsorbent by the reproducing apparatus 20 in accordance with the following reproducing method.

  Next, two adsorbent regeneration methods implemented in the adsorbent regeneration apparatus of the present embodiment will be described.

(First playback method)
FIG. 3 is a flowchart showing a first adsorbent regeneration method in the adsorbent regeneration apparatus of the present embodiment.

The first regeneration method is started after the supply of the gas to be purified (CO ₂ gas) from the gas to be purified introduction line 12 to the adsorption tower 11 is stopped and the CO ₂ purification step by the adsorption tower 11 is stopped. At this time, all the valves 22a, 23a, 24a, and 26a of the regeneration device 20 are closed.

First, the adsorbent regeneration process is performed. Specifically, the regeneration gas supply valve 23a is opened, the gas discharge valve 22a is opened, and regeneration gas (N ₂ gas) is supplied from the regeneration gas supply line 23 to the adsorption tower 11 (step S1). At the same time, the heater 25 is activated to heat the regeneration gas to 230 ° C. (step S2). That is, by circulating the heated regeneration gas through the adsorption tower 11, the adsorbent is heated and the impurities adsorbed on the adsorbent are desorbed. The impurity desorbed at this time is discharged to the outside through the gas discharge line 22 together with the regeneration gas.

  After circulating the heated regeneration gas through the adsorption tower 11 for a certain time, heating of the regeneration gas by the heater 25 is stopped (step S3), and the regeneration process of the adsorbent is completed. This end point can also be determined by measuring the concentration of the removal target substance contained in the regenerated gas discharged by a concentration meter or the like provided in the gas discharge line 22. Thereafter, the supply of the regeneration gas to the adsorption tower 11 is continued, and the adsorbent is cooled by ventilating the adsorption tower 11 with the regeneration gas gradually cooled.

  Thereafter, the gas discharge valve 22a and the regeneration gas supply valve 23a are closed, and the supply of the regeneration gas to the adsorption tower 11 is stopped (step S4). Then, after opening the gas return valve 26a, the circulation pump 27 is operated to circulate the regeneration gas along the circulation path 30 including the adsorption tower 11 (step S5). At the same time, the cooling device 28 is operated to cool the regeneration gas (step S6), and the regeneration material is circulated while cooling, thereby further cooling the adsorbent.

  When the adsorbent is lowered to a predetermined temperature, the circulation and cooling of the regeneration gas are stopped (step S7). Specifically, after the cooled regeneration gas is circulated for a certain time, or when the temperature of the adsorbent is measured by a thermometer provided in the adsorption tower 11, and the measured value falls below a predetermined value, The operation of the circulation pump 27 and the cooling device 28 is stopped, and the gas return valve 26a is closed.

Even after the circulation of the regeneration gas is stopped, the regeneration gas remains in the adsorption tower 11. When the CO ₂ purification step by the adsorption tower 11 is resumed in this state, the regeneration gas remaining in the adsorption tower 11 is contained in the purified gas (CO ₂ gas), and the desired purity cannot be obtained. Therefore, a replacement step for replacing the regeneration gas remaining in the adsorption tower 11 with high-purity CO ₂ gas is required before the CO ₂ purification step is resumed.

For this purpose, the replacement gas supply valve 24a and the gas discharge valve 22a are opened, and the replacement gas (high-purity CO ₂ gas) is supplied from the replacement gas supply line 24 to the adsorption tower 11 (step S8). As a result, the regeneration gas (N ₂ gas) adsorbed on the adsorbent is replaced with high-purity CO ₂ gas and discharged to the outside through the gas discharge line 22. As a result, it is possible to prevent the regeneration gas from being included in the purified gas after the CO ₂ purification process is resumed.

  After almost all of the regeneration gas in the adsorption tower 11 has been replaced by the flow of the replacement gas, the replacement gas supply valve 24a and the gas discharge valve 22a are closed to stop the supply of the replacement gas to the adsorption tower 11 (step). S9). Specifically, after the replacement gas is circulated for a certain period of time, or the concentration of the regeneration gas contained in the discharged replacement gas measured by a concentration meter or the like provided in the gas discharge line 22 falls below a predetermined concentration. In this case, the supply of the replacement gas to the adsorption tower 11 is stopped.

Thus, the first regeneration method is completed, the supply of the gas to be purified (CO ₂ gas) from the gas to be purified introduction line 12 to the adsorption tower 11 is resumed, and the CO ₂ purification step by the adsorption tower 11 is resumed.

  As described above, according to the first regeneration method, the adsorbent that has been brought to a high temperature state by the regeneration process can be rapidly cooled by cooling and circulating the regeneration gas. At this time, regeneration gas for cooling is not wasted, so there is no risk of cost increase.

(Second playback method)
Some adsorbents generate heat when the CO ₂ gas itself is adsorbed. For example, if the adsorbent is packed in the adsorption tower, depending on the size and structure of the adsorption tower and the amount of CO ₂ gas supplied to the adsorption tower, about 50 to 130 ° C. when the adsorbent is zeolite. When the adsorbent is activated carbon, the temperature in the tower may rise to about 40 to 60 ° C. When such an adsorbent is used, the following problems may occur. That is, for example, when the regeneration gas is replaced with CO ₂ gas as in the replacement step of the first regeneration method, the CO ₂ gas itself is adsorbed on the adsorbent, and the cooled adsorbent is brought into a high temperature state again. In order to solve this problem, it is conceivable that the replacement gas is circulated through the adsorption tower until the adsorbent is sufficiently cooled. For this purpose, a large amount of the replacement gas, that is, a large amount of high-purity CO ₂ gas is consumed. , The impact on costs will be greater. In addition, it takes a considerable amount of time to re-cool the adsorbent that has generated heat by heat dissipation, and time loss becomes a problem.

  The second regeneration method is for coping with such a problem, and is particularly effective when the above adsorbent is used.

  Hereinafter, the second regeneration method of the adsorbent in the adsorbent regeneration apparatus of the present embodiment will be described along the flowchart shown in FIG.

In the second regeneration method, as in the first regeneration method, the supply of the gas to be purified (CO ₂ gas) from the gas to be purified introduction line 12 to the adsorption tower 11 is stopped, and the CO ₂ purification step by the adsorption tower 11 is performed. Will be started after stopping. At this time, all the valves 22a, 23a, 24a, and 26a of the regeneration device 20 are closed.

First, the adsorbent regeneration process is performed. Specifically, the regeneration gas supply valve 23a is opened, the gas discharge valve 22a is opened, and regeneration gas (N ₂ gas) is supplied from the regeneration gas supply line 23 to the adsorption tower 11 (step S11). At the same time, the heater 25 is operated to heat the regeneration gas to 230 ° C. (step S12).
That is, by circulating the heated regeneration gas through the adsorption tower 11, the adsorbent is heated and the impurities adsorbed on the adsorbent are desorbed. The impurity desorbed at this time is discharged to the outside through the gas discharge line 22 together with the regeneration gas.

  After circulating the heated regeneration gas through the adsorption tower 11 for a fixed time, heating of the regeneration gas by the heater 25 is stopped (step S13), and the regeneration process of the adsorbent is completed. This end point can also be determined by measuring the concentration of the removal target substance contained in the regenerated gas discharged by a concentration meter or the like provided in the gas discharge line 22. Thereafter, the supply of the regeneration gas to the adsorption tower 11 is continued, and the adsorbent is cooled by ventilating the adsorption tower 11 with the regeneration gas gradually cooled.

Thereafter, the regeneration gas supply valve 23a is closed, and the supply of the regeneration gas to the adsorption tower 11 is stopped (step S14). Next, the replacement gas supply valve 24a is opened, and the replacement gas (high purity CO ₂ gas) is supplied from the replacement gas supply line 24 to the adsorption tower 11 (step S15). At this time, the gas discharge valve 22 a is opened, and the regeneration gas (N ₂ gas) remaining inside the adsorption tower 11 is replaced with high-purity CO ₂ gas and discharged to the outside through the gas discharge line 22. The

After almost all of the regeneration gas in the adsorption tower 11 has been replaced by the flow of the high purity CO ₂ gas, the gas discharge valve 22a and the replacement gas supply valve 24a are closed to supply the high purity CO ₂ gas to the adsorption tower 11. Supply is stopped (step S16). Specifically, after supplying high-purity CO ₂ gas for a certain period of time, the supply of the replacement gas to the adsorption tower 11 is stopped. Alternatively, the concentration of the regeneration gas contained in the exhausted high-purity CO ₂ gas is measured by a densitometer provided in the gas discharge line 22, and when the concentration falls below a predetermined concentration, or the exhausted high-purity When the concentration of the CO ₂ gas exceeds a predetermined concentration, the supply of the replacement gas to the adsorption tower 11 is stopped.

At this time, the adsorbent in the adsorption tower 11 is in a state in which the high-purity CO ₂ gas that is the replacement gas is adsorbed. Therefore, when the adsorbent described above is used as the adsorbent, the adsorbent generates heat. In order to suppress this heat generation, cooling circulation of the replacement gas (high purity CO ₂ gas) is performed. Specifically, after opening the gas return valve 26a, the circulation pump 27 is operated to circulate the high-purity CO ₂ gas along the circulation path 30 including the adsorption tower 11 (step S17). At the same time, the cooling device 28 is operated to cool the high purity CO ₂ gas (step S18), and the high purity CO ₂ gas is circulated while cooling. Thus, high-purity CO ₂ gas in a substitution process can remove heat generated by the adsorbent described above that occurs by adsorption.

After the high-purity CO ₂ gas is cooled and circulated for a certain period of time, or when the temperature of the adsorbent is measured by a thermometer provided in the adsorption tower 11 and the measured value falls below a predetermined value for a certain period of time. The operation of the pump 27 and the cooling device 28 is stopped. Thereafter, the gas return valve 26a is closed, and the circulation and cooling of the high-purity CO ₂ gas are stopped (step S19).

  In step S15, there is a possibility that the regeneration gas is not completely replaced due to the reason that a part of the regeneration gas adsorbed on the adsorbent is not discharged. In that case, even after executing up to step S19, There is a possibility that the regeneration gas remains inside the adsorption tower 11. Therefore, steps S15 to S19 can be repeatedly executed in order to reliably discharge the regeneration gas in the adsorption tower 11 to the outside.

Thus, the second regeneration method ends, the supply of the gas to be purified (CO ₂ gas) from the gas to be purified introduction line 12 to the adsorption tower 11 is resumed, and the CO ₂ purification process by the adsorption tower 11 is resumed.

As described above, according to the second regeneration method, even when the replacement gas (high-purity CO ₂ gas) generates heat when adsorbed on the adsorbent, the replacement gas is cooled and circulated to quickly remove the adsorbent. Can be cooled to. At this time, the replacement gas for cooling is not wasted, so there is no risk of cost increase.

  In the above-described embodiment, the adsorption device is provided with one adsorption tower, but a plurality of adsorption towers may be provided. In that case, the adsorption towers may be connected in series, in parallel, or any combination thereof. In addition, an adsorbent regeneration device may be provided in each adsorption tower, or one adsorbent regeneration device may be provided for a plurality of adsorption towers.

  In the above-described embodiment, both the regeneration gas supply line and the replacement gas supply line are connected to the gas introduction line and connected to the adsorption tower via the gas introduction line, but are directly connected to the adsorption tower. May be. Similarly, the gas return line only needs to form a closed circulation path including the adsorption tower, and may be directly connected to the adsorption tower instead of being connected to the gas introduction line and the gas discharge line. Good.

  In addition, a purified gas discharge line connected to the upper part of the adsorption tower can be used for supplying the regeneration gas and the replacement gas to the adsorption tower. That is, the gas introduction line may be connected to the purified gas discharge line instead of the adsorption tower, or the regenerative gas supply line and the replacement gas supply line are each connected to the purified gas instead of being connected to the gas introduction line. It may be connected to a discharge line. In this case, the gas return line can be connected to the purified gas discharge line. Similarly, a purified gas introduction line connected to the lower part of the adsorption tower can be used to discharge the regeneration gas and the replacement gas to the outside. That is, the gas discharge line may be connected not to the adsorption tower but to the refined gas introduction line, and in this case, the gas return line may also be connected to the refined gas introduction line.

  Furthermore, in the embodiment described above, the regeneration process of the adsorbent is performed by circulating the heated regeneration gas to the adsorption tower. Instead of heating the regeneration gas, the adsorption tower is heated and heated. Alternatively, the adsorbent may be regenerated by circulating a regeneration gas. In this case, the heating means such as a heater is only required to heat the adsorption tower itself, and may be provided so as to cover the outer surface of the adsorption tower, for example. In addition, after the regeneration process of the adsorbent is completed, after the heating of the adsorption tower is stopped, the supply of the regeneration gas to the adsorption tower is continued as in the case of heating the regeneration gas.

1 CO ₂ supply system 2 cleaning apparatus 3 circulating purification device 4 recovery and purification device 5 CO ₂ supply source 10 adsorption device 11 adsorption tower 12 to be purified gas inlet line 13 the purified gas discharge line 20 adsorbent reproducing apparatus 21 gas inlet line 22 gas discharge Line 22a Gas discharge valve 23 Regeneration gas supply line 23a Regeneration gas supply valve 24 Replacement gas supply line 24a Replacement gas supply valve 25 Heater 26 Gas return line 26 Gas return valve 27 Circulation pump 28 Cooling device 30 Circulation path

Claims (13)

An adsorbent regeneration apparatus containing at least one of zeolite, silica gel, activated alumina, and activated carbon, which adsorbs impurities contained in carbon dioxide as a gas to be purified,
A regeneration gas supply means for supplying regeneration gas to the adsorption tower filled with the adsorbent;
Heating means for heating either the regeneration gas supplied to the adsorption tower or the adsorption tower;
A replacement gas supply means for supplying carbon dioxide as a replacement gas to the adsorption tower;
A gas circulation means for circulating the replacement gas supplied to the adsorption tower along a circulation path including the adsorption tower;
Cooling means for cooling the replacement gas circulating along the circulation path;
A gas discharge line connected to the adsorption tower via a gas discharge valve for discharging the regeneration gas or the replacement gas supplied to the adsorption tower;
A gas return line connected to the adsorption tower via a gas return valve and forming the circulation path;
The regeneration gas heated by the heating means is supplied to the adsorption tower, or the regeneration gas supplied to the adsorption tower is supplied to the adsorption tower heated by the heating means. Control of supplying the replacement gas to the adsorption tower after exhausting the adsorbent by discharging from the gas discharge line and circulating at least a part of the replacement gas along the circulation path Means,
An adsorbent regenerator.   2. The control unit according to claim 1, wherein the control unit operates the heating unit to supply the regeneration gas to the adsorption tower, and then stops the operation of the heating unit to supply the regeneration gas to the adsorption tower. Adsorbent recycling device.   The adsorbent regeneration apparatus according to claim 1 or 2, wherein the impurity substance includes at least one of moisture, oil, and volatile impurities. Carbon dioxide obtained by treating carbon dioxide as the gas to be purified with the adsorbent is used in a semiconductor device manufacturing process, or carbon dioxide used in a semiconductor device manufacturing process is the gas to be purified. The adsorbent regeneration device according to any one of claims 1 to 3 , wherein the adsorbent regeneration device is supplied to the adsorption tower. The purity of the carbon dioxide as the replacement gas is equal to or higher than the purity of carbon dioxide obtained by treating the carbon dioxide as the gas to be purified with the adsorbent, according to any one of claims 1 to 4. The adsorbent recycling apparatus described. A method for regenerating an adsorbent comprising at least one of zeolite, silica gel, activated alumina, and activated carbon, which adsorbs impurities contained in carbon dioxide as a gas to be purified,
The regeneration gas is heated and supplied to the adsorption tower filled with the adsorbent, and the heated regeneration gas is circulated through the adsorption tower, or the adsorption tower is heated and the regeneration is conducted to the heated adsorption tower. Regenerating the adsorbent by discharging the regeneration gas that has circulated through the adsorption tower to the outside while circulating the gas;
After regenerating the adsorbent, supplying carbon dioxide as a replacement gas to the adsorption tower, and replacing the regeneration gas remaining in the adsorption tower with the replacement gas;
Circulating at least a portion of the replacement gas along a circulation path including the adsorption tower while cooling;
A method for regenerating an adsorbent, comprising: The adsorption according to claim 6 , further comprising the step of stopping the heating of the regeneration gas or the adsorption tower while supplying the regeneration gas to the adsorption tower before replacing the regeneration gas with the replacement gas. How to recycle the material. Carbon dioxide obtained by treating carbon dioxide as the gas to be purified with the adsorbent is used in a semiconductor device manufacturing process, or carbon dioxide used in a semiconductor device manufacturing process is the gas to be purified. The method for regenerating an adsorbent according to claim 6 or 7 , wherein the adsorbent is supplied to the adsorption tower. The step of substituting with the replacement gas includes supplying carbon dioxide having a purity equal to or higher than that of carbon dioxide obtained by treating carbon dioxide as the gas to be purified with the adsorbent to the adsorption tower. The method for regenerating an adsorbent according to any one of claims 6 to 8 . An adsorption tower filled with an adsorbent containing at least one of zeolite, silica gel, activated alumina, and activated carbon that adsorbs impurities contained in carbon dioxide, which is a gas to be purified , and regeneration for regenerating the adsorbent A carbon dioxide purification device comprising an adsorption device comprising:
The playback device is
Regeneration gas supply means for supplying regeneration gas to the adsorption tower;
Heating means for heating either the regeneration gas supplied to the adsorption tower or the adsorption tower;
A replacement gas supply means for supplying carbon dioxide as a replacement gas to the adsorption tower;
A gas circulation means for circulating the replacement gas supplied to the adsorption tower along a circulation path including the adsorption tower;
Cooling means for cooling the replacement gas circulating along the circulation path;
A gas discharge line connected to the adsorption tower via a gas discharge valve for discharging the regeneration gas or the replacement gas supplied to the adsorption tower;
A gas return line connected to the adsorption tower via a gas return valve and forming the circulation path;
The regeneration gas heated by the heating means is supplied to the adsorption tower, or the regeneration gas supplied to the adsorption tower is supplied to the adsorption tower heated by the heating means. Control of supplying the replacement gas to the adsorption tower after exhausting the adsorbent by discharging from the gas discharge line and circulating at least a part of the replacement gas along the circulation path Means,
A carbon dioxide purification apparatus. It said control means, after the regeneration gas by actuating the heating means is supplied to the adsorption tower, supplying the regeneration gas to the adsorption tower to stop the operation of the heating means, according to claim 1 0 Carbon dioxide purification equipment. A carbon dioxide purification method comprising a method for regenerating an adsorbent containing at least one of zeolite, silica gel, activated alumina, and activated carbon, which adsorbs impurities contained in carbon dioxide as a gas to be purified,
The reproduction method is
The regeneration gas is heated and supplied to the adsorption tower filled with the adsorbent, and the heated regeneration gas is circulated through the adsorption tower, or the adsorption tower is heated and the regeneration is conducted to the heated adsorption tower. Circulating the gas and discharging the circulated regeneration gas to the outside, thereby regenerating the adsorbent;
After regenerating the adsorbent, supplying carbon dioxide as a replacement gas to the adsorption tower, and replacing the regeneration gas remaining in the adsorption tower with the replacement gas;
Circulating at least a portion of the replacement gas along a circulation path including the adsorption tower while cooling;
A carbon dioxide purification method comprising: The step of substituting with the replacement gas includes supplying carbon dioxide having a purity equal to or higher than that of carbon dioxide obtained by treating carbon dioxide as the gas to be purified with the adsorbent to the adsorption tower. carbon dioxide purification process according to claim 1 2.

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