JP3417730B2 - Oxygen concentrator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen concentrator for separating and using an oxygen enriched gas from the atmosphere. More particularly, it relates to a pressure swing adsorption type oxygen concentrator, and an oxygen concentrator having an improved adsorbent bed capable of supplying an oxygen enriched gas to a user with a small gas supply amount. It is a thing.

[0002]

2. Description of the Related Art In recent years, the number of patients suffering from diseases of respiratory organs such as asthma, emphysema, and chronic bronchitis has been increasing, and one of the most effective treatments is oxygen inhalation. . The oxygen inhalation method is a method in which a patient inhales oxygen gas or oxygen-enriched air. Oxygen gas cylinders have been used as a supply source for oxygen gas and oxygen-enriched air, but in recent years, an oxygen concentrator that separates oxygen-enriched gas from the air has been developed, making it convenient to use and easy to maintain. Therefore, it is becoming more and more popular.

At present, there are a membrane type oxygen concentrating device using an oxygen selective permeable membrane and an adsorption type oxygen concentrating device using an adsorbent capable of preferentially adsorbing nitrogen, as the oxygen concentrating device. It intends to add improvements to the concentrator.

The main adsorption type oxygen concentrators up to now are pressure fluctuation adsorption type oxygen concentrators using a compressor. Such an apparatus is usually an adsorption step of introducing compressed air compressed by a compressor into an adsorption bed filled with an adsorbent capable of preferentially adsorbing nitrogen, and adsorbing nitrogen in a pressurized state to obtain an oxygen-enriched gas. Then, the pressure inside the adsorption bed is reduced to alternately perform the desorption step of regenerating the adsorption bed to obtain an oxygen-enriched gas. In this case, a surge tank is used to temporarily store the oxygen-enriched gas from the adsorption bed, and the oxygen-enriched gas stored in the surge tank is supplied to the patient, and a part of it is adsorbed on the adsorption bed. It is often used for repressurization of the adsorbent bed or purging for regeneration of the adsorbent bed.

In the adsorption bed of a commonly used adsorption type oxygen concentrator, the separation coefficient in adsorption is 2.0 to 3.0.
The molecular sieve zeolite 5A having the value of or the one filled with 13X alone is widely used. Since the separation performance specific to the adsorbent such as the adsorption amount per unit weight indicating the performance of the adsorbent, the selectivity, or the adsorption rate dominates the performance of the oxygen concentrator as a whole, oxygen is used as long as such adsorbent is used. There is a limit to improvement of problems such as improvement of concentration efficiency, reduction of running cost and downsizing of equipment.

Recently, in the United States, a nitrogen adsorbent having a higher performance than that of the conventional adsorbent disclosed in Japanese Examined Patent Publication No. 5-25527 was developed, and oxygen can be concentrated more efficiently than before with a small amount of air supply. Realized the device. However, there is a problem that the price of the filler is higher than that of the conventional product. Using such a high-performance nitrogen adsorbent, in JP-A-5-269330, a high-performance nitrogen adsorbent is provided on the side of the air supply means in the air flow direction of the adsorption bed, and a conventional low-performance nitrogen adsorbent is provided on the other end. It has been proposed that the separation is efficiently performed by using an adsorption bed in which the agent is arranged. However, a high performance nitrogen adsorbent with a high separation coefficient exerts its performance under high oxygen partial pressure conditions, and in such an arrangement where the feed air with a low oxygen partial pressure first contacts the high performance nitrogen adsorbent, It cannot be said that the advantages of using an adsorbent are fully utilized.

When using a high performance nitrogen adsorbent, it is necessary to consider the cost increase of the adsorbent.
In such an arrangement, water adsorption of the adsorbent occurs from the side of the high-performance nitrogen adsorbent, which deteriorates the expensive adsorbent and leads to deterioration of the performance of the oxygen concentrator itself. Most of the adsorption-type oxygen concentrators currently used do not have a dehumidifier because there is also a problem of downsizing the equipment. Therefore, the moisture absorption of the high-performance nitrogen adsorbent causes a problem that the oxygen concentration performance is deteriorated and a problem that the running cost is newly increased.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the amount of supply air by improving the oxygen concentration efficiency of the adsorption bed in such a pressure fluctuation adsorption type oxygen concentration device, and to reduce the size of the air supply means. The purpose is to reduce the power consumption of the device. Furthermore, the influence of moisture absorption of the adsorbent due to the moisture in the air is limited to a part of the adsorption bed to prevent the performance of the oxygen concentrator from deteriorating and to minimize the increase in running cost.

[0009]

As a result of intensive studies aimed at solving the problems in the oxygen concentrator, the present inventor has used two or more different adsorbents in the adsorbent bed and A low-performance nitrogen adsorbent is arranged on the side of the air supply means in the air flow direction, and a high-performance nitrogen adsorbent having a separation coefficient based on a two-component system adsorption equilibrium that is 2 or more higher than that of the low-performance nitrogen adsorbent is arranged at the other end. The present inventors have found that the oxygen concentrating device having the above-mentioned laminated packed adsorption bed is very effective in terms of oxygen concentrating performance and cost, and have reached the present invention.

That is, the present invention comprises at least one adsorbent bed filled with an adsorbent capable of preferentially adsorbing nitrogen over oxygen, and an air supply means for supplying air to the adsorbent bed.
In a pressure fluctuation adsorption type oxygen concentrator having a surge tank for storing the oxygen-enriched gas concentrated in the adsorption bed, the adsorption bed is filled with at least two different adsorbents layer by layer, A low-performance nitrogen adsorbent is arranged on the side of the air supply means in the air flow direction of the adsorption bed, and the separation coefficient based on the two-component system adsorption equilibrium is 2 at the other end as compared with the low-performance nitrogen adsorbent.
The present invention proposes an oxygen concentrator having a layered packed adsorption bed in which a high-performance nitrogen adsorbent is arranged.

The separation coefficient is a scale showing the degree of difficulty in separating nitrogen and oxygen in the air, and represents the ratio of the adsorption amount ratio to the partial pressure ratio at the adsorption equilibrium.

The high-performance nitrogen adsorbent is X-type zeolite having a SiO ₂ / Al ₂ O ₃ ratio of 2.0 to 3.0, and
Included are crystalline zeolites in which at least 88% of the AlO ₄ tetrahedral units are associated with lithium cations. The low performance nitrogen adsorbent includes 5A type zeolite or 13X type zeolite. The present invention also includes an oxygen concentrator in which the high-performance nitrogen adsorbent accounts for 25 to 75% of the entire adsorption bed.

Further, in the present invention, a 5A type zeolite adsorbent is arranged on the side of the air supply means in the direction of air flow of the laminated packed adsorption bed, and the high performance nitrogen adsorbent is arranged on the other end. An oxygen concentrator is included that has a layered packed adsorbent bed constructed by placing a 13X zeolite adsorbent between the seed adsorbent layers. The high performance nitrogen adsorbent contains SiO ₂ / A
An X-type zeolite having an l ₂ O ₃ ratio of 2.0 to 3.0,
And a crystalline zeolite in which at least 88% of its AlO ₄ tetrahedral units are associated with lithium cations.
Further, the amount of the high-performance nitrogen adsorbent is 25 to 50% of the whole adsorbent bed.
An oxygen concentrator that includes a stacked packed bed.

In the present invention, the air supplied to the laminated packed adsorption bed is pressurized air, and nitrogen adsorption is carried out at atmospheric pressure or higher,
An oxygen concentrator characterized by performing nitrogen desorption at or below atmospheric pressure, or characterized in that the nitrogen adsorption process in the laminated packed adsorption bed is carried out near atmospheric pressure and the desorption process is carried out below atmospheric pressure. An oxygen concentrator is included.

The present invention will be described in more detail with reference to the drawings as necessary.

As an example of the embodiment of the laminated packed adsorbent bed used in the present invention, as shown in FIG. 1, a low-performance nitrogen adsorbent and a nitrogen adsorbent having a higher performance than the adsorbent, that is, a separation coefficient of 2 or more are stratified. A packed laminated packed adsorbent bed is used.
Each adsorbent is filled with a conventional low-performance nitrogen adsorbent on the air supply side and a high-performance nitrogen adsorbent on the other end side.

The present adsorbent bed includes an adsorbent bed in which the low-performance nitrogen adsorbent and the high-performance nitrogen adsorbent are unitized, and these are combined into one adsorber. Further, the low-performance nitrogen adsorbent and the high-performance nitrogen adsorbent are respectively packed in different adsorption towers, the low-performance nitrogen adsorbent packed tower is arranged on the side of the air supply means in the air flow direction, and then the high-performance nitrogen adsorbent is installed. Performance Includes an adsorption bed with nitrogen adsorbent packed columns arranged in series. Such a device facilitates replacement of the high performance nitrogen adsorbent and the low performance nitrogen adsorbent.

The adsorbent disposed on the air supply means side of the adsorption bed in the present invention may be any adsorbent capable of preferentially adsorbing nitrogen over oxygen, such as molecular sieve zeolite 5A. 13X and the thing which modified these etc. are mentioned.

Further, as the adsorbent to be disposed on the discharge side of the oxygen-enriched air which is the other end, a high performance nitrogen adsorbent having a separation coefficient of 2 or more higher than that of the adsorbent disposed on the air supply side is disposed. For example, a crystalline zeolite that is an X-type zeolite having a SiO ₂ / Al ₂ O ₃ ratio of 2.0 to 3.0 and in which at least 88% of its AlO ₄ tetrahedral units are associated with lithium cations is included. . Conventionally used low-performance nitrogen adsorbents have a separation factor of 2.0-
On the other hand, the separation coefficient of the high-performance nitrogen adsorbent is as high as 6.0 or more from the value of the single component adsorption equilibrium, while the adsorption amount of nitrogen is much higher than that of the low-performance nitrogen adsorbent. It showed a high adsorption capacity, and confirmed this fact from the evaluation results of the oxygen concentrator.

In particular, the adsorption bed, which is a feature of the present invention, is filled with at least two different adsorbents layer by layer, and a low-performance nitrogen adsorbent is arranged on the side of the air supply means in the air flow direction of the adsorption bed, The arrangement in which a high-performance nitrogen adsorbent is arranged at the other end as compared with the low-performance nitrogen adsorbent is that the low-performance nitrogen adsorbent is used to roughly purify air as a raw material gas, and then the high-performance nitrogen adsorbent is used. This makes use of the characteristic of the adsorbent that the amount of oxygen remaining in the gas phase can be increased more than before, that is, the recovery rate of oxygen can be increased.

Therefore, as an example of the laminated packed adsorption bed of the present invention, a combination of the molecular sieve zeolite 5A: the high performance nitrogen adsorbent described above from the air supply means side, or the molecular sieve zeolite 13X: the high performance nitrogen adsorbent described above is used. Is preferred.

The ratio of the high-performance nitrogen adsorbent to the whole adsorbent is determined by the product gas flow rate of the oxygen concentrator and the adsorbent filling amount,
It also changes depending on the operating conditions of the device, and preferably the high-performance nitrogen adsorbent occupies 25 to 75% of the whole adsorbent.

FIG. 2 shows another embodiment of the stacked packed adsorption bed.
As shown in FIG. 3, a low performance nitrogen adsorbent 5A type zeolite is arranged on the side of the air supply means of the laminated packed adsorption bed, and a high performance nitrogen adsorbent is arranged on the other end, and the two types of adsorbent layers An adsorption bed with a 13X zeolite as a low performance nitrogen adsorbent in between is used. At the other end of the air supply means, it is very preferable to shorten the length of the nitrogen adsorption zone. For that purpose, a low-performance nitrogen adsorbent is admixed with 13X type zeolite having a good adsorption rate before the high-performance nitrogen adsorbent. Ideally it should be placed in

The number of adsorption beds in the present invention may be one or two or more, but in the case of a small-sized oxygen concentrator for medical use, two or less are preferable, and in the case of one, the whole apparatus is preferable. It is excellent in that it can be miniaturized.

An oxygen concentrator as shown in FIG. 3 is preferable as the oxygen concentrator incorporating the laminated packed adsorption bed of the present invention.

The air supplied to the laminated packed adsorption bed of the oxygen concentrator is pressurized air, and adsorbs at atmospheric pressure or higher, and performs desorption under reduced pressure at or below atmospheric pressure. Alternatively, there is a pressure fluctuation type oxygen concentrating device in which an adsorption process in a stacked packed adsorption bed is performed near atmospheric pressure and decompression / desorption is performed at atmospheric pressure or lower.

The oxygen concentrator of the present invention has a surge tank for temporarily storing the concentrated oxygen-enriched air, and the oxygen-concentrated air is continuously supplied to the user through the tank at the same time. , The process in which the oxygen-enriched gas stored in the surge tank means flows back to the adsorption bed is pressure fluctuation adsorption.
An example is a pressure fluctuation type oxygen concentrator included in the desorption process. In order to exert the effect of the invention, the oxygen-enriched gas in the surge tank means is configured to flow back into the adsorption bed due to the repressurization step of the adsorption bed and the purge in the desorption step by such a step. Is preferred.

Further, in the oxygen concentrating device using the laminated packed adsorption bed in which the high performance nitrogen adsorbent of the present invention is layered and packed,
It is desirable that the oxygen-concentrated gas supply means be provided with a flow rate setting means for setting the supply amount of the oxygen-concentrated gas in accordance with the user's request or the doctor's prescription. In this case, the flow rate setting means includes a needle valve combined with a commonly used rotor meter and a plurality of openings with different gas flow resistances, and the flow rate can be set by selecting the opening that matches the desired flow rate. It is possible to use such a valve.

With the oxygen concentrator having a laminated packed adsorbent bed of the present invention, the high nitrogen adsorption capacity and oxygen separation performance exhibited by the high performance nitrogen adsorbent were confirmed, and the performance made possible to downsize the device and reduce power consumption. It was realized. Further, the adsorbent that is affected by moisture in the atmosphere can be limited to the low-performance nitrogen adsorbent, and the expensive high-performance nitrogen adsorbent needs to be replaced during long-term use without being affected by moisture. It was confirmed that the laminated packed adsorbent bed has durability against moisture absorption and cost reduction.

The use of the oxygen concentrator having the laminated packed adsorption bed of the present invention is not particularly limited,
For example, it is suitable for medical purposes such as home use.

[0031]

【Example】

[Example 1] The molecular sieve zeolite 5A (separation coefficient 2.4) was placed in an adsorption tower having a diameter of 85 mm and a height of 320 mm.
A high performance nitrogen adsorbent that is an X-type zeolite with a SiO ₂ / Al ₂ O ₃ ratio of 2.5 and crystalline zeolite with 90% of its AlO ₄ tetrahedral units associated with lithium cations (separation factor 6. 4) is stacked and filled in a volume ratio of 2: 3,
An adsorption bed was prepared in which the molecular sieve zeolite 5A was arranged on the air supply means side and the high-performance nitrogen adsorbent was arranged on the surge tank side at the other end. An oxygen concentrator having a compressor and a surge tank was manufactured using such an adsorption bed.

[Comparative Example 1] A molecular sieve zeolite 5A (separation coefficient 2.4) and a molecular sieve zeolite 13X (separation coefficient 2.7) having a separation coefficient of 2.4 were placed in an adsorption tower having a diameter of 85 mm and a height of 320 mm in a ratio of 2: Laminated and packed in a volume ratio of 3, the molecular sieve zeolite 5A is provided on the air supply means side, and the molecular sieve zeolite 13 is provided.
An adsorption bed was prepared in which X was placed on the other end, the surge tank side. An oxygen concentrator having a compressor and a surge tank was manufactured using such an adsorption bed.

The amount of air supplied from the compressor to the adsorption bed so that the product gas flow rate of the oxygen-enriched gas from the adsorption tower of the oxygen concentrator described in Example 1 and Comparative Example 1 to the surge tank is 3.0 L / min. Table 1 shows the results of the supply air amount of both, the oxygen concentration in the product gas, the oxygen yield (product oxygen amount / supply oxygen amount), and the power consumption of the oxygen concentrator.

[0034]

[Table 1]

By using the oxygen concentrator having the adsorption bed described in Example 1, it was possible to reduce the supply air amount by 1.5 L / cycle by 7.5% as compared with Comparative Example 1. Further, the oxygen concentration in the product gas increased to 90%, which was 6% higher than that of Comparative Example 1. As a result, the oxygen yield was improved and the power consumption of the oxygen concentrator was reduced.

[0036]

In the oxygen concentrator of the present invention, the high-performance nitrogen adsorbent is arranged in the adsorption bed to enhance the adsorption efficiency of nitrogen in the adsorption step and increase the amount of oxygen remaining in the gas phase. Is improved so as to increase the yield of oxygen-enriched gas.

Due to the improvement in yield brought about by this improvement, the amount of air supplied can be reduced, so that the air supply means can be miniaturized and the power consumption can be reduced.

Further, by arranging the adsorbent of the present invention for adsorption of moisture existing in the air, the stability of long-term performance is improved and the cost is reduced due to the decrease in the frequency of replacement of the high-performance nitrogen adsorbent. Also has an effect.

[Brief description of drawings]

FIG. 1 is a schematic view schematically showing an example of a preferred embodiment of the adsorption bed of the present invention.

FIG. 2 is a schematic view schematically showing an example of a preferred embodiment of the adsorption bed of the present invention.

FIG. 3 is a schematic diagram showing a preferred embodiment of an oxygen concentrator using the adsorption bed of the present invention.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C01B 13/02 A61M 16/10 B01D 53/04

Claims (6)

(57) [Claims] 1. At least one adsorption bed packed with an adsorbent capable of preferentially adsorbing nitrogen over oxygen, and the adsorption bed
And air supply means for supplying pressurized air, the pressure swing adsorption-type oxygen concentrator of having a surge tank to keep storing the concentrated oxygen enriched gas in adsorber bed,
At least two different adsorbents are packed in layers in the adsorption bed, a low-performance nitrogen adsorbent is arranged on the air supply means side in the air flow direction of the adsorption bed, and the low-performance nitrogen adsorbent is provided at the other end. separation factor based on two-component adsorption equilibrium compared to having a layered packed adsorbent bed arranged more high performance nitrogen adsorbents, low performance
Adsorbent is 5A type zeolite and / or 13X type Zeoli
And the high-performance nitrogen adsorbent has a SiO ₂ / Al ₂ O ₃ ratio of
X-type zeolite of 2.0 to 3.0, and
At least 88% of the AlO ₄ tetrahedral units are lithium cations
An oxygen concentrator , which is a crystalline zeolite associated with . 2. The high-performance nitrogen adsorbent is 25
Oxygen concentrator according to claim 1 Symbol mounting and having an adsorbent bed that occupies 75%. 3. A 5A type zeolite adsorbent is disposed on the side of the air supply means in the direction of air flow of a laminated packed adsorption bed, and the high performance nitrogen adsorbent is disposed on the other end, and these two types of adsorbent layers are provided. The oxygen concentrator according to claim 1, further comprising a layered packed adsorption bed constituted by disposing a 13X type zeolite adsorbent between the two. 4. The high performance nitrogen adsorbent comprises 25% of the total adsorbent bed.
The oxygen concentrator according to claim 3 , occupying -50%. Wherein the air supplied to the adsorption bed is pressurized air, subjected to adsorption at atmospheric pressure or higher, according to claim 1-4, characterized in that performing the vacuum desorption below atmospheric or ambient pressure, Any of the oxygen concentrators described. 6. The oxygen concentrator according to any one of claims 1 to 4 , wherein adsorption is carried out near atmospheric pressure and desorption under reduced pressure is carried out under atmospheric pressure.