JPH0475841B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention uses a selective oxygen permeable membrane that allows oxygen to permeate at a higher rate than nitrogen. It concerns enrichers. In particular, the present invention provides an improved oxygen enricher using a hollow fiber selective oxygen permeable membrane. [Prior Art] In recent years, many patients have been suffering from respiratory system diseases such as asthma, emphysema, and chronic bronchitis, and oxygen inhalation is one of the most effective treatments for these diseases.
Oxygen inhalation is also effective for recovering physical strength after surgery or sports. However, the oxygen concentration used in this oxygen inhalation method is generally 50% or less, which is safer for long-term inhalation. As a so-called oxygen enricher for supplying oxygen-enriched air with an oxygen concentration of 50% or less for a long time,
A membrane enrichment device using a selective oxygen permeable membrane that allows oxygen to permeate at a higher rate than nitrogen has been proposed. The characteristics of oxygen enrichers using this membrane method are that the oxygen and nitrogen selectivity of the membrane is generally in the range of 2 to 5, so the oxygen concentration obtained by general air separation is 50% or less; Also, since the permeation of water vapor is greater than that of nitrogen, the enriched air obtained by passing through the membrane comes out humidified, so humidification is not required especially when inhaling oxygen-enriched air, and the membrane itself is an ultra-fine filter. The membrane type is a pressure reducing type. Oxygen enrichers can be said to be the best enrichers for medical use. By the way, the amount of oxygen-enriched air inhaled by the membrane method varies depending on the patient, but it is generally relatively large at 2/mm or more, and therefore the surface area of the selective oxygen permeable membrane needs to be large, making the device somewhat large. For ease of use, it is necessary to make the membrane module as compact as possible. In addition, such a membrane-type oxygen enricher usually requires not only air to be supplied to the surface side of the selective oxygen permeable membrane, but also a large amount of cooling air to cool the pressure reducing means such as a vacuum pump. The drawback is that flow resistance tends to increase when a large amount of cooling air flows through the membrane module. In particular, when the membrane module uses a hollow fiber bundle consisting of a hollow fiber selective oxygen permeable membrane, the air flow resistance is extremely large, requiring a large fan, resulting in large energy consumption and noise. Improvement was strongly desired. [Object and Structure of the Invention] The object of the present invention is to solve the above-mentioned drawbacks in membrane-type oxygen enrichers, and in particular, to provide an oxygen enricher using a hollow fiber-like selective oxygen permeable membrane with low energy consumption. The purpose is to provide a product that consumes less, is compact, and has low noise. As a result of intensive research to achieve this purpose, we have found that in addition to providing a bypass that does not pass through the membrane side and creating an air flow on the membrane side, we have also developed a method to at least create an air flow on the bypass. The present invention was achieved by discovering that it is effective to use another blowing means. That is, the present invention provides a membrane module having a plurality of arrays of separation functional parts each equipped with a selective oxygen permeable membrane;
In an oxygen enricher that maintains one side of the membrane in the membrane module at a certain degree of vacuum and is equipped with a depressurizing means for taking out oxygen-enriched air from there, air is placed on the other side of the membrane in the membrane module. Oxygen characterized by comprising a first blowing means for generating a flow, an air bypass means that does not pass through the other side of the membrane, and a second blowing means for generating a flow of air at least in the bypass means. It provides an enricher. Hereinafter, the present invention will be explained in more detail using the drawings. FIGS. 1 to 6 are schematic flow sheets showing embodiments of the oxygen enricher according to the present invention. In FIG. 1, reference numeral 1 schematically shows a membrane module having a large number of arrays of separation function parts equipped with a selective oxygen permeable membrane 10, and 2 represents one side of the selective oxygen permeable membrane in the membrane module. It is connected to the suction side of a pressure reducing means 4 for keeping the space at a certain level of vacuum. Further, 3 indicates a space on the other side of the membrane in the membrane module, and is located downstream of the first air blowing means. Reference numeral 6 denotes a second blowing means, which increases the capacity of the first blowing means by sending the air flowing in from the inlet of the enricher to the first blowing means, and also causes the air to flow into the bypass 7. . Bypass 7
The air that has passed through is combined with the oxygen-depleted air from the membrane module 1, passes around a pressure reducing means such as a vacuum pump in order to cool it, and is then discharged to the outside of the enricher. On the other hand, the oxygen-enriched air that has passed through the selective oxygen permeable membrane 10 is taken out by the pressure reducing means 4 and made available for use. The numbers in FIGS. 2-6 have the same meanings as in FIG. 1. FIG. 2 has a feature in which the second blowing means 6 is used exclusively for blowing air to the bypass 7. Third
The figure is characterized in that the first air blowing means 5 and the second air blowing means 6 are provided on the downstream side and are of a suction type.
Further, FIG. 4 is characterized in that the first air blowing means 5 is placed on the upstream side of the membrane module to be a push-in type, and the second air blowing means 6 is placed on the downstream side to be a suction type. In FIG. 5, the first blowing means is a suction type and the second blowing means 6 is a push type. Furthermore, FIG. 6 is characterized in that the air after passing around the pressure reducing means 4 is made to flow through the first blowing means 5 and the second blowing means 6. It goes without saying that the oxygen enricher of the present invention is not limited to those shown in FIGS. 1 to 6. As described above, the oxygen enricher of the present invention has an air bypass means in addition to introducing air into the space on the raw material gas distribution side (hereinafter referred to as the membrane surface side) in the separation function section housed in the membrane module. It is characterized by Note that the bypass means can also be provided in a part of the space within the membrane module. In addition, in the oxygen enricher of the present invention, the entire gas flow (i.e., the oxygen-depleted air and the air that has passed through the bypass from the membrane module) excluding the oxygen-enriched air or the entire gas flow discharged outside the enricher, excluding the oxygen-enriched air, It is characterized in that the entire flow of incoming air is used to cool the pressure reducing means. In the oxygen enricher of the present invention, in order to minimize concentration polarization on the membrane surface and increase separation efficiency, it is preferable that the amount of air fed to the membrane surface side is large.
A compact membrane module with a small space on the membrane surface side, especially a membrane module that uses hollow fibers as a selective permeation membrane, has a large flow resistance on the membrane surface side such as inside the hollow fibers, so it is difficult to use as a means of blowing air. This has the disadvantage that a large amount of noise is required, resulting in increased noise and power consumption. In that case, the amount of air supplied to the membrane surface side should be at least three times the amount of oxygen-enriched air50
It is preferably 4 times or more and 40 times or less, more preferably 5 times to 30 times. In addition, in such an oxygen enricher, it is necessary that the air volume for cooling the depressurizing means be larger than the air volume supplied to the membrane surface side, and in order to secure a flow path for the large amount of cooling air volume, a bypass is required. This means that a means has been established. Air flow rate through the bypass means
The ratio V _B /V _C between V _B and the cooling air volume V _C of the pressure reducing means is preferably 0.3 to 0.95, more preferably 0.5 to 0.90, and particularly preferably 0.65 or more. Incidentally, V _B /V _C means the ratio of the respective flow rates at the same pressure and temperature. By setting V _B /V _C within such a range, the oxygen enricher of the present invention can easily supply an appropriate amount of air to the membrane surface side, and the cooling air volume of the pressure reducing means is also very large. This is something that can be easily achieved. Furthermore, the oxygen enricher of the present invention has such a V _B /V _C
In order to ensure an air flow rate in the range of , in addition to the first blowing means for generating an air flow on the membrane surface side, a second blowing means capable of generating an air flow at least in the bypass means is provided. It is characterized by The second blowing means may be one that generates an air flow only in the bypass means, or may also be one that generates an air flow on the membrane surface side in order to supplement the first air flow. good. The first blowing means and the second blowing means may be positioned in any manner as long as they perform their respective functions, but in particular, one of them may be positioned in a push-in type as shown in FIG. 4 or FIG. The other type having the suction type has the advantage that it is easier to increase the flow of air on the membrane surface side, and the entire enrichment device can be made more compact, making it easier to reduce noise. The blowing means may be a fan, a blower, etc., and specific examples include a sirotsko turbo fan, an axial flow fan, and the like. Furthermore, a feature of the oxygen enricher of the present invention is that only the air flowing into the space on the membrane surface side passes through a filter means to remove dust, etc. contained in the air flowing into the space on the membrane surface side of the membrane module. That's what it's all about. A preferred location for such filter means is near the inlet of the module. As for the performance of such a filter, it is preferable to have a high dust collection rate in order to remove as much dust from the atmosphere as possible, but generally speaking, the higher the collection rate, the greater the pressure drop, so it is necessary to increase the capacity of the fan described above. This is undesirable because the noise and power consumption increase unavoidably. The performance of the filter is rated 2nd by the Japan Air Cleaning Association.
In accordance with the performance test method, tests were conducted using eight types of dust specified in JISZ8901, and the collection efficiency was evaluated.
70% or more, preferably 80% or more, more preferably
95% or more is used. When the collection efficiency is less than 70%, the flow rate of the membrane decreases rapidly. In addition to this filter means, a relatively coarse filter means may also be provided at the air intake port of the enricher. FIG. 7 schematically illustrates a preferred embodiment of the oxygen enricher of the present invention, which has the features described above. That is, a bundle of hollow fiber-like permselective properties 21 is housed, and both ends thereof are covered with an adhesive layer 22.
The membrane module 23 is adhesively sealed and has hollow fibers opened. Air is supplied to the hollow part of this hollow fiber membrane, and the outer gap part of the hollow fiber is maintained at a certain degree of vacuum by the pressure reducing means 24, so that a part of the air permeates through the membrane wall and becomes oxygen. Enriched air is removed via conduit means 25 or the like from which it is obtained. A first blowing means 26 is provided downstream of the membrane module for sucking oxygen-depleted air from the hollow part of the hollow fiber bundle, and the oxygen-depleted air can be used for cooling the pressure reducing means. I'm starting to be able to do it. Further, a filter means 27 is provided on the upstream side of the membrane module, and a second blowing means 28 is further provided upstream thereof. A part of the air from this second blowing means is introduced into the membrane module after passing through a filter means 27, and the other air passes through a bypass means 29 and is used for cooling the pressure reducing means. The selective oxygen permeable membrane used in the oxygen enricher of the present invention may have any shape such as hollow fiber, tubular, or flat membrane, and hollow fiber membranes are particularly preferred. The forms of membrane modules using these membranes include, for example, hollow fiber type, tubular type, flat plate laminated type, spiral type, etc. Among them, hollow fiber type and spiral type are suitable for the present invention. Thread type is preferred. For example, for medical purposes, it is preferably 30% or more, more preferably 35%.
Enriched air with a higher oxygen concentration is required, and the membrane's oxygen/nitrogen selectivity (oxygen permeation rate/
nitrogen permeation rate) of at least 3, preferably 3.5
above, more preferably 3.8 or above. The enricher of the present invention is characterized by its compactness, and to achieve this, the permeability of the membrane is important. That is, the oxygen permeation rate of the membrane of the present invention is 20
At least 2×10 ^-5 cc/cm ²・sec・cm measured in °C
Hg, preferably 5×10 ^-5 cc/cm ²・sec・cmHg or more, more preferably 1×10 ⁻⁴ cc/cm ²・sec・cmHg
It is. If the oxygen permeation rate is less than 2×10 ^-5 cc/cm ²・sec・cmHg, the permeability is low, so in order to obtain the amount of enriched air necessary for an enricher, the membrane area must be increased. Even if the membrane is in the form of a hollow fiber, the volume of the module will be large and it will not be compact. In the case of a hollow fiber membrane, the entire membrane wall of the hollow fiber may have selective permeation performance, or the inner surface or the surface may have the function. In particular, in the case of an inner surface film that has selective properties on the inner surface, it has the advantage of being able to form a high performance film, such as an interfacial polymerized film, and being less likely to be damaged. If the material air is allowed to flow through the hollow part in this way, the inner diameter should be 100μ or more, or even 300μ, since the pressure loss in the hollow part can be kept low.
It is preferable to fall within the above range. The depressurizing means used in the present invention depressurizes the space on the back side of the separation function section and serves as the driving force for separation, and also takes out oxygen-enriched air through the outlet and the conduit means, and uses the enriched air as the discharge gas of the depressurizing means. It has the function of sending out. As the pressure reducing means, a vacuum pump with an electric motor is usually preferred, but a blower or the like may be used in some cases. As for the type of pump, it is preferable to use one that does not contain fine particles such as oil since it is used for human inhalation, and it is preferable to use an oil-less type pump that is low in noise and durable. The capacity of the pump varies greatly depending on the required amount of enriched air, oxygen concentration, and performance of the separation membrane. When the selectivity of oxygen and nitrogen is 3.5, a pump with a performance that can produce a flow rate of 6/min at an absolute pressure of 270 mmHg is required. Further, the oxygen enricher of the present invention preferably includes a means for cooling the enriched air coming out through the warm pump, and a heat exchanger can be used as the cooling means. Intake air can be used as a cooling medium in a heat exchanger, and in order to cool the enriched air to a temperature close to that of the intake air, the heat exchanger, such as a coiled pipe, should be placed right next to the intake air intake. It is preferable that the surrounding area is not easily heated by the heat of the vacuum pump. Furthermore, the oxygen enricher has a water separation means, such as a circular pipe, for separating water generated by condensation of excess moisture in the oxygen-enriched air cooled by the cooling means. is desirable. The water separated here is preferably supplied to a moisture retention function such as gauze attached to the surface of the above-mentioned coiled heat exchanger for cooling, and is evaporated there to enhance the cooling effect. . Furthermore, in the oxygen enricher,
For example, a column filled with activated carbon may be installed to remove harmful gases such as NOx and SOx and bad odors, or a sterilization filter may be installed to remove bacteria from the enriched air. It also has the effect of preventing bacteria from entering the air conduit. Further, accessory parts such as an alarm device, a time meter, a flow meter, a pressure gauge, etc., may be installed to detect and notify abnormalities during operation. Further, in the oxygen enricher of the present invention, the pressure reducing means and the first and second air blowing means are housed in one soundproof box, and the air intake port provided in the outer shell of the enricher is connected to the soundproof box. More preferably, at least once in each of the inflow air flow path to the air inlet and the discharge air flow path from the air outlet of the soundproof box to the outlet provided in the outer shell of the enricher. In order to prevent noise generation, it is desirable to bend the tube three or more times, particularly preferably five or more times, and to affix a sound-absorbing material or the like to the inner surface of the channel. In addition, if the temperature of the air being taken in is low, you can install a heater or use the exhaust heat of the pump to warm the air, or recirculate and reuse part of the warmed air that should be exhausted before introducing it into the membrane module. The temperature of the air used may be kept above a certain temperature. The oxygen enricher of the present invention is used for medical purposes or for human inhalation to recover physical strength, but is not limited to this, and can also be used for purposes such as supplying oxygen to fish tanks that can be used for ornamental purposes. It has a wide range of uses. [Example] As shown in Fig. 7, a membrane module containing a bundle of 7300 oxygen selectively permeable hollow fiber membranes each having an inner diameter of 700μ, an outer diameter of 1000μ, and a length of about 25cm, and the first and second An oxygen enricher was assembled with a fan, a vacuum pump and a filter. In addition, the first fan and the second fan have different capacities, and are operated under the conditions shown in Table 1.
The power consumption of the two fans as a whole was evaluated and the results shown in Table 1 were obtained. Furthermore, as a comparative example, we evaluated the case where the flow path was blocked without using a bypass and only the second fan was used in a push-in type without using the first fan, and the results obtained are shown in Table 1. .

[Table] [Effects of the Invention] The oxygen enricher of the present invention can reliably cool the pressure reducing means such as a vacuum pump, so there is very little risk of the pressure reducing means being heated, and it is highly safe. There is. In addition, in the present invention, a high flow rate of oxygen-enriched air can be easily obtained, the power consumption during operation is small, and the generation of noise can be easily prevented.
Furthermore, an excellent effect can be obtained in which the entire enrichment device can be easily made compact.

[Brief explanation of the drawing]

1 to 6 are schematic flow sheets illustrating embodiments of the oxygen enricher according to the present invention, and FIG. 7 shows an example of a particularly preferred embodiment of the oxygen enricher according to the present invention. It is shown schematically.

Claims (1)

[Claims] 1. A membrane module having a large number of arrays of separation functional parts each equipped with a selective oxygen permeable membrane, and one side of the membrane in the membrane module maintained at a certain degree of vacuum, and oxygen-enriched air is supplied from there. In an oxygen enricher equipped with a depressurizing means for taking out the membrane, a first blowing means for generating an air flow on the other side of the membrane in the membrane module, and a first air blowing means for generating an air flow on the other side of the membrane in the membrane module; An oxygen enricher comprising a bypass means and a second blowing means for producing an air flow at least in the bypass means. 2. Claim 1, wherein the pressure reducing means is cooled by the oxygen-enriched air flowing through the other side of the membrane and the air flowing through the bypass means.
Oxygen enricher as described in section. 3. The oxygen enricher according to claim 1, wherein the pressure reducing means is cooled by the air flow that should flow into the other side of the membrane and the air flow that should flow into the bypass means. 4 Flow rate of air for cooling the pressure reducing means V _C
The air flow rate flowing through the bypass means for V _B
The oxygen enricher according to claim 1, wherein the ratio V _B /V _C is 0.3 to 0.95. 5. An oxygen enricher according to claim 1, comprising filter means near the inlet of said membrane module. 6. The oxygen enricher according to claim 1, wherein the separation function section uses a selective oxygen permeable hollow fiber membrane.