JP2004344735A - Oxygen concentration device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a PSA system oxygen concentration device capable of further prolonging a life of the device by preventing deterioration caused by adsorption of the moisture content onto an adsorbent even if it is used for a long period of time and further avoiding various problems caused by drain water generated by previously removing the moisture content contained in air taken-in from the outside. <P>SOLUTION: In the oxygen concentration device adopting a pressure swing adsorption system, a pressurization/adsorption step for feeding the pressurized external air to an adsorption bed filled with the adsorbent for selectively adsorbing a nitrogen gas; and a pressure reduction/desorption step for pressure-reducing the adsorption bed and desorbing the nitrogen gas adsorbed onto the adsorbent are alternately repeated to produce oxygen-rich air. A dehumidification means for removing the moisture content contained in the external air in the state of water vapor is provided in series to the adsorption bed and independently at a front step part as compared with an entrance side of the adsorption bed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a pressurized adsorption step of pressurizing and supplying air taken in from the outside to an adsorbent bed filled with an adsorbent capable of selectively adsorbing nitrogen rather than oxygen to adsorb nitrogen gas to the adsorbent. The present invention relates to an oxygen concentrating apparatus that employs a pressure fluctuation adsorption method in which oxygen-enriched air is generated by alternately repeating a vacuum desorption step of depressurizing an adsorption bed to desorb nitrogen gas adsorbed on the adsorbent.
[0002]
[Prior art]
In recent years, the number of patients suffering from respiratory diseases such as asthma, emphysema and chronic bronchitis has been increasing.One of the most effective treatments is oxygen inhalation therapy. Oxygen concentrators that separate directly have been developed and are becoming increasingly popular as therapeutic devices for oxygen inhalation therapy because of their convenience in use and ease of maintenance.
[0003]
Devices for use in such oxygen inhalation therapy include a method in which concentrated oxygen supplied to a user is extracted from oxygen contained in air and supplied as oxygen-enriched air, and a method in which oxygen gas that has already been concentrated is filled. There is a method of supplying from a high-pressure vessel that has been used. Among these devices, the system that supplies the concentrated gas filled in the high-pressure container to the user has a simple structure, and is easy to reduce in weight and size. Excellent as a mold device.
[0004]
However, when the concentrated oxygen gas supplied to the user is consumed, it is necessary to refill the high-pressure container or to replace the high-pressure container with an already-filled high-pressure container, which is troublesome for the user. On the other hand, if the oxygen gas contained in the air can be concentrated and used, the complicated work as described above is not required, which is very convenient for the user.
[0005]
By the way, as the apparatus for concentrating the oxygen gas contained in the air, in addition to the apparatus using a gas separation membrane that selectively allows oxygen gas to pass, pressure swing adsorption (Pressure Swing) using an adsorbent such as zeolite is used. Adoption (hereinafter, abbreviated as “PSA”).
[0006]
Here, the PSA method will be briefly described. First, in order to selectively adsorb nitrogen gas to the adsorbent onto the adsorbent made of zeolite or the like, the introduced air is pressurized into compressed air, and the compressed air is used as the compressed air. A pressurizing step of contacting the adsorbent to remove nitrogen gas and generate oxygen-enriched air is performed. When the pressurizing step is completed, a depressurizing step is next performed to perform a depressurizing step of desorbing nitrogen gas from the adsorbent, whereby a state in which the adsorbent can selectively adsorb nitrogen gas again appears. Let it. In this manner, a method of generating oxygen-enriched air by repeating the pressurizing step and the depressurizing step is described. In addition, nitrogen gas is selectively removed from the air by using this PSA method, and oxygen-enriched air having an oxygen concentration of 90%, for example, is temporarily stored in a container, and the oxygen-enriched air stored in the container is temporarily stored in the container. It is supplied to the user as breathing gas.
[0007]
However, an adsorbent such as zeolite has an excellent property of selectively adsorbing nitrogen gas, but also has an unfavorable property of adsorbing moisture contained in air. In other words, especially when zeolite is used as an adsorbent, zeolite adsorbs water molecules most strongly, then nitrogen gas molecules strongly, and also slightly adsorbs oxygen molecules in the crystal structure of the molecules. Has the property of In addition, the amount of adsorption increases as the pressure increases, and decreases as the pressure decreases. However, when the zeolite adsorbs moisture, unlike nitrogen gas, it is not easy to desorb it, and the function of selectively adsorbing and removing nitrogen gas is lost, and oxygen-enriched air is lost. Cannot achieve its original purpose of obtaining
[0008]
Then, in order to solve such a problem, a method of removing moisture from the external air supplied to the step of generating oxygen-enriched air in advance can be considered. However, in such a case, a new problem occurs that the water removed from the air before the oxygen-enriched air is generated is discharged as drain water this time. Then, if the drain water thus generated is erroneously discharged to the floor in the room, there is also a problem that the floor is flooded.
[0009]
For this reason, a method of temporarily storing the removed drain water in a container such as a bread and evaporating the drain water by natural drying has been considered. However, if the water removed from the air is temporarily stored as drain water, there arises a problem that bacteria and fungi floating in the air grow in the container storing the drain water and become unsanitary. Moreover, when such a condition occurs, for patients suffering from respiratory diseases such as breathing, emphysema, chronic bronchitis, etc., a new health-impairing factor is added, which is preferable from the viewpoint of health. Absent.
[0010]
Furthermore, when air containing a large amount of water is supplied to the adsorption bed as it is, the water may condense, and the water generated by the dew will flow into piping such as a pressure sensor, and the pressure sensor will detect the water. Problems such as deterioration in sensitivity and instability of the nitrogen gas adsorption process also occur.
[0011]
[Patent Document 1]
JP-A-61-86923
[Patent Document 2]
JP 01-47422 A
[Patent Document 3]
Japanese Patent Application Laid-Open No. 08-141087
[Patent Document 4]
JP-A-02-95413
[Patent Document 5]
JP 2000-135287 A
[Patent Document 6]
JP 08-24558 A
[Patent Document 7]
Japanese Patent Publication No. 07-83818
[Problems to be solved by the invention]
In order to use the oxygen concentrator for medical applications, it is essential to use it stably for a long period of time. However, in the oxygen concentrator using the PSA method, An adsorbent such as zeolite, which selectively adsorbs and removes nitrogen gas, adsorbs moisture in the air, and there is an essential problem that its function cannot be sufficiently exhibited and the life of the apparatus is shortened. Moreover, in the PSA method, the taken-in air is compressed by a compressor and sent to an adsorbent bed filled with an adsorbent, so that moisture contained in the air is condensed on a pipe for sending air on the adsorbent bed. Things often happen. Then, the condensed moisture reaches the adsorbent and adheres thereto, thereby causing a problem that the adsorbent is deteriorated and the life of the oxygen concentrator is shortened.
[0019]
Therefore, the present invention can prevent the deterioration caused by the adsorption of moisture to the adsorbent even if it is used for a long period of time, thereby further extending the life of the apparatus. It is intended to provide a device. Still another object of the present invention is to provide a PSA-type oxygen concentrator capable of avoiding various problems caused by drain water generated by previously removing moisture contained in air taken in from the outside.
[0020]
[Means for Solving the Problems]
Here, as the present invention for solving the above-mentioned problem, the present invention relates to "Pressure adsorption for supplying pressurized external air to an adsorption bed filled with an adsorbent for selectively adsorbing nitrogen gas." In an oxygen concentrator employing a pressure-fluctuation adsorption method in which a step and a vacuum desorption step of depressurizing the adsorption bed and desorbing the nitrogen gas adsorbed on the adsorbent are alternately repeated to generate oxygen-enriched air,
An oxygen concentrator, wherein a dehumidifying means for removing water contained in the external air in the form of water vapor is provided in series with the adsorbent bed and independently at a stage preceding the adsorbent bed from the inlet side. Is done.
[0021]
At this time, the present invention preferably provides an "oxygen concentrator according to claim 1, characterized in that the external air supplied to the dehumidifying means is preheated," as described in claim 2. .
[0022]
Further, in the present invention, as described in claim 3, it is preferable that the "oxygen concentrating device according to claim 1 or 2 characterized by keeping the dehumidifying means warm".
[0023]
According to the present invention, as set forth in claim 4, "the dehumidifying means is a pressure-variation adsorption type dehumidifier having an adsorption bed filled with an adsorbent for absorbing moisture. Preferably, the oxygen concentrator according to any one of 1 to 3 is used.
[0024]
Then, according to the present invention, as described in claim 5, "the adsorbent filled with an adsorbent for selectively adsorbing nitrogen gas and the adsorbent bed filled with an adsorbent for moisture absorption, The oxygen concentrating device according to any one of claims 1 to 4, wherein the oxygen-enriched air flows as a purge gas in a direction opposite to the flow direction of the air.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
As a result of intensive studies on such problems, the present invention dehumidifies the inflow air of the compressor of the conventional oxygen concentrator with a dehumidifying mechanism in advance, and is filled with an adsorbent for selectively adsorbing nitrogen gas. The main feature of this method is that compressed air is sent to the adsorbed bed. As described above, in the oxygen concentrating apparatus of the PSA type of the present invention, since the moisture is removed by the dehumidifying mechanism and the apparatus is in a substantially dry state, the pressure adsorption step for the air in such a dry state is performed. No dew condensation occurs in an adsorbent bed in which the pressure and desorption steps are alternately repeated. For this reason, the adsorbent such as zeolite filled in the adsorbent bed does not suffer from the deterioration caused by the adsorption of moisture, and the life of the apparatus can be extended.
[0026]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0027]
FIG. 1 is a configuration diagram schematically showing an embodiment of an oxygen concentrator employing a PSA system according to the present invention, wherein reference numeral 1 denotes an oxygen concentrator main body, and reference numeral 2 denotes humidification. Are shown.
[0028]
In FIG. 1, first, the oxygen concentrator main body 1 will be briefly described. This oxygen concentrator main body 1 includes a dehumidifier 10, an adsorbent bed 11, a compressor 12, a filter 13, a switching valve 14, a check valve 15, a product tank. 16, a pressure regulating valve 17, a flow setting device 18, and a product filter 19. The adsorbent bed 11 is filled with an adsorbent for selectively adsorbing nitrogen gas molecules rather than oxygen gas molecules in the air. The compressor 12 pressurizes the external air and compresses the compressed air into the dehumidifying means 10. The filter 13 plays a role of removing foreign matter such as minute dust from the external air supplied to the compressor 12.
[0029]
At this time, as the adsorbent bed 11 filled with an adsorbent that selectively adsorbs nitrogen rather than oxygen, a multi-tube adsorbent bed having three or more cylinders in addition to a one-tube type, a two-tube type, and the like (FIG. A two-cylinder type is used, and as the compressor 12, an oscillating air compressor may be used, and a rotary air compressor such as a screw type, a rotary type, or a scroll type may be used.
[0030]
In the oxygen concentrating apparatus 1 configured as described above, the air supplied to the compressor 12 as the external air introducing means through the filter 13 is compressed and supplied to the dehumidifying means 10 through the switching valve 14. 10 removes moisture in the air. In addition, as an example of embodiment of such a dehumidifying means 10, there is a dehumidifying apparatus adopting a PSA method using zeolite for adsorbing moisture as an adsorbent. Then, this dehumidifier is explained below.
[0031]
Zeolites have the property of strongly adsorbing water molecules in the crystal structure of the molecules, then strongly adsorbing nitrogen gas and the above-mentioned impurity gas molecules, and adsorbing a small amount of oxygen molecules. As described above. At this time, the amount of zeolite adsorbed has a property that the higher the pressure is, the larger the pressure is, and the lower the pressure is, the smaller the property is. If the pressure is fluctuated so as to perform the desorption step by reducing the pressure, gas separation is performed, and if the water contained in the air can be treated as a gas called water vapor, on the same principle as the oxygen concentrator of the PSA system, Moisture in the air can be removed.
[0032]
At this time, the crystal lattice and the size of its pores can be adjusted by adding cations (cations) to the zeolite used as a water vapor adsorbent. For example, zeolite types include 4A, 5A, 13X, etc., each having a different performance as a molecular sieve. Water molecules show strong adsorption to zeolite of any of the above sizes, but the 4A type zeolite does not adsorb nitrogen gas or oxygen gas, but the 5A type or 13X type adsorbs nitrogen gas well. However, among them, it is known that the 13X type has better adsorption ability. Therefore, in constructing the dehumidifier by the PSA method, the above-mentioned 4A-type zeolite may be used. However, since the 4A-type zeolite has small pores, it is difficult for water molecules once adsorbed to be desorbed. There is a problem, and from this point, it is preferable to use 5A type or 13X type (preferably 13X type) zeolite.
[0033]
By the way, the amount of moisture (humidity) contained in the air varies depending on environmental conditions such as season, weather, temperature, etc. For example, when the temperature is 30 ° C. and the relative humidity is 100%, 35 g is contained in 1 m ^{3 of} air. Since the weight of one mole of water (H ₂ O) is 18 g, when it is converted to steam, it becomes 22.4 liters under the atmospheric pressure of 0 ° C. The same) gas concentration. On the other hand, the composition of air is 78% nitrogen gas, 21% oxygen gas, 0.9% argon gas, and the like. Therefore, as compared with the case where 78% of nitrogen gas contained in air is selectively adsorbed on zeolite and nitrogen gas is removed, 5A type and 13X type zeolite used for removing moisture in air are used. This part can be designed compact because less volume is required.
[0034]
Therefore, when a PSA-type dehumidifier is used, a moisture-absorbing bed is provided in series in the upstream of the adsorbing bed 11 which is also used for the PSA-type oxygen concentrator, before the inlet side. It only needs to be provided. When the external air containing moisture is taken in and compressed by the compressor 12, the temperature of the taken-in air is increased by pressurization, and is converted into steam. In addition, heat is generated by driving the compressor 12. For this reason, by keeping the moisture absorption bed for removing moisture from the air warm or installing it near the compressor 12 having heat, the moisture swelling into the air taken in was converted to water vapor. In this state, it is introduced into the adsorption bed for absorbing moisture.
[0035]
In this way, when the moisture in the air is adsorbed as water vapor by the dehumidifying means 10, substantially dry air is introduced into the adsorption bed 11 which generates oxygen-enriched air. Therefore, it is possible to substantially solve the problem that moisture adheres and the nitrogen gas adsorption ability is reduced. In addition, since the dehumidifying means 10 having such an action is provided independently, maintenance is improved when the apparatus breaks down or the adsorbent for water vapor is replaced.
[0036]
However, in the PSA type dehumidifier, it is necessary to repeatedly use a moisture absorbing adsorbent composed of zeolite or the like that adsorbs water vapor. Therefore, once adsorbed water vapor has to be desorbed from the moisture absorbing adsorbent, it must be regenerated. Must. For this purpose, in the vacuum desorption step, a purge gas in a substantially absolutely dry state is caused to flow countercurrently from the adsorption bed 11 to the moisture absorption bed to desorb water vapor from the adsorbent filled in the moisture absorption bed, Discharge outside the system.
[0037]
At this time, it is preferable to use oxygen-enriched air stored in the product tank 16 as a gas used as the purge gas. This is because the oxygen-enriched air desorbs the nitrogen gas adsorbed on the adsorption bed 11 because the nitrogen gas partial pressure and the water vapor partial pressure are extremely low, as is apparent from the production process. This is because it is very convenient for desorbing water vapor from the adsorption bed for moisture absorption connected in series to the adsorption bed 11. In addition, since the water vapor desorbed from the adsorption bed for absorbing moisture does not take the form of drain water, it does not become flooded even if it is discharged to the outside. In addition, since there is no method to dispose of drain water by natural evaporation, there is no need to temporarily store it in a container, so bacteria and fungi such as bacteria floating in the air essentially multiply. Not even.
[0038]
It should be noted that, here, it should be further noted that the substantially air-free external air from which water has been removed by the dehumidifying means 10 is supplied to the adsorption bed 11, where nitrogen gas molecules are selectively removed. Oxygen-enriched air that is adsorbed and contains a large amount of oxygen gas molecules remaining without being adsorbed is generated, and the generated oxygen-enriched air flows into the product tank 16 via the check valve 15 so as not to flow back. And stored here. In this way, the oxygen-enriched air stored in the product tank 16 is supplied through the product filter 19 while the supply flow rate and the pressure are controlled by the pressure regulating valve 17 and the flow rate setting device 18 while the user ( It is supplied to the patient) as breathing gas.
[0039]
As for regeneration of the adsorbent bed 11 filled with the adsorbent having adsorbed nitrogen gas molecules, first, the switching valve 14 is switched to shut off the pressurized air supplied to the adsorbent bed 11 by the compressor 12. Then, the pressure in the adsorption bed 11 is reduced, so that the nitrogen gas molecules adsorbed by the adsorbent are desorbed from the adsorbent. Then, the air containing a large amount of desorbed nitrogen gas molecules is released from the oxygen concentrator 1 to the outside, and the adsorbent 11 regains the activity for adsorbing the nitrogen gas molecules. In the step of desorbing the nitrogen gas molecules from the adsorbent, since the pressure upstream of the check valve 17 is higher than the pressure in the adsorbent bed 11, the air rich in the nitrogen gas molecules is not discharged. There is no supply to the upstream side from the 17.
[0040]
【The invention's effect】
According to the present invention described above, even if the PSA-type oxygen concentrator is used for a long period of time, moisture is removed from the external air supplied to the adsorbent for generating oxygen-enriched air in advance. Therefore, it is possible to prevent deterioration caused by the adsorption of moisture to the adsorbent, and to further extend the life of the device.
[0041]
Furthermore, in the present invention, since water is not removed in advance from the external air supplied to the adsorbent for producing oxygen-enriched air as drain water, it is necessary to dispose this drain water by natural drying. In addition, since it is not necessary to temporarily store them in a container or the like, bacteria such as bacteria floating in the air and mold do not grow.
[Brief description of the drawings]
FIG. 1 is a block diagram schematically showing a preferred embodiment of an oxygen concentrator according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Oxygen concentrating apparatus 10 Dehumidifying means 11 Adsorption bed 12 Compressor 13 Filter 14 Switching valve 15 Check valve 16 Product tank 17 Pressure regulating valve 18 Flow rate setting device 19 Product filter 21 Water permeable membrane 22 Oxygen flow path 23 Air purifying means (filter)
24 External air introduction means (fan)
25 Introduction direction of external air

Claims (5)

A pressurized adsorption step of supplying pressurized external air to an adsorbent bed filled with an adsorbent for selectively adsorbing nitrogen gas, and depressurizing the adsorbent bed to desorb the nitrogen gas adsorbed on the adsorbent In an oxygen concentrator that employs a pressure fluctuation adsorption system that alternately repeats a vacuum desorption process and generates oxygen-enriched air,
An oxygen concentrating device, wherein a dehumidifying means for removing water contained in the external air in the form of water vapor is provided in series with the adsorbent bed and independently at a stage preceding the adsorbent bed from the inlet side. The oxygen concentrator according to claim 1, wherein the external air supplied to the dehumidifying unit is preheated. The oxygen concentrator according to claim 1, wherein the dehumidifier is kept warm. The oxygen concentrator according to any one of claims 1 to 3, wherein the dehumidifier is a pressure fluctuation adsorption type dehumidifier including an adsorption bed filled with an adsorbent for absorbing moisture. The oxygen-enriched air flows in a direction opposite to the flow direction of the external air with respect to the adsorbent bed filled with an adsorbent for selectively adsorbing nitrogen gas and the adsorbent bed filled with an adsorbent for moisture absorption. The oxygen concentrator according to any one of claims 1 to 4, wherein the oxygen is supplied as a purge gas.

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