JPH0419163B2 - - 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. Because it also functions as a vacuum pump, it can provide clean air with no dust or bacteria, and if the operation pressure is reduced only, i.e., a vacuum pump is used, a low-noise enrichment device can be created. The enrichment device can be said to be the best enrichment device 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 membrane-type oxygen enrichers usually require 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 was that flow resistance tends to increase when the cooling air flow 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 flow resistance of this air flow 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 of membrane-type oxygen enrichers, and in particular, to provide an oxygen enricher using a hollow fiber selective oxygen permeable membrane, which has 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 objective, we discovered that it is effective to provide not only an air path to generate air flow on the membrane side, but also a bypass that does not pass through the membrane side. The invention has been achieved. 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;
A decompression means for maintaining one side of the membrane in the membrane module at a certain level of vacuum and extracting oxygen-enriched air therefrom, and a blowing means for generating air flow on the other side of the membrane in the module. an oxygen enricher having a bypass means that does not pass through the surface side of the membrane in order to allow a part of the air flow generated from the blowing means to flow;
The present invention provides an oxygen enricher characterized in that the decompression means is cooled by the oxygen-depleted air flowing through the surface side of the membrane and the atmospheric flow flowing through the bypass means. As a reference example, there is a module having a large number of arrays of separation functional parts equipped with a selective oxygen permeable membrane, and a module for maintaining a certain degree of vacuum on the back side of the membrane in the module and extracting oxygen-enriched air from there. In an oxygen enricher having a pressure reducing means and a blowing means for generating an air flow on the other side of the membrane in the module, in order to circulate a part of the air flow generated from the blowing means. A bypass means that does not pass through the surface side of the membrane is provided, and a part of the atmospheric flow after passing around the pressure reducing means to cool the pressure reducing means is directed to the bypass means, and the remainder of the atmospheric flow is directed to the bypass means. On the surface side of the membrane,
An example of an oxygen enricher is that the oxygen enricher is configured to supply oxygen to both oxygen and oxygen. Hereinafter, the present invention will be explained in more detail using the drawings. FIGS. 1 to 3 are schematic flow sheets showing embodiments of the oxygen enricher according to the present invention. Incidentally, FIG. 4 shows a reference example. In these figures, 1 schematically shows a membrane module having a large number of arrays of separation functional parts equipped with a selective oxygen permeable membrane 10,
Reference numeral 2 designates a space on the back side of the selective oxygen permeable membrane in the membrane module, which 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 surface side of the membrane in the membrane module, and an air blowing means 5 is provided on the upstream or downstream side thereof. In addition to the air flow path passing through the space 3 on the membrane surface side, there is also a bypass means 6 as an air flow path.
is equipped. In Figures 1 to 3, the air that has passed through the bypass means 6 is combined with the oxygen-depleted air obtained by passing through the membrane surface side of the membrane module, and is supplied to the surroundings of the pressure reduction means in order to cool them. After passing through there, it is discharged outside the enricher. FIG. 4 shows an arrangement in which the pressure reducing means is first cooled by air flowing in from the intake port of the enricher. Furthermore, in these figures, the permselective membrane 10
The oxygen-enriched air obtained by permeation is taken out by the pressure reduction means 4 via the conduit means and made available for use. Furthermore, as shown in these figures,
Flow rate regulating means 7, 8 may be provided in the bypass means and/or in the air flow path connected to the air on the membrane surface side. Further, as shown in FIGS. 1 to 3, it is desirable that filter means 9 be provided for passing only the air flowing into the membrane module. As described above, the oxygen enricher of the present invention, in addition to introducing air into the space on the raw material gas distribution side (i.e., the membrane surface side) in the separation function part housed in the membrane module,
It is characterized by having air bypass means. 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 of V _B to the total flow rate Vt of the amount of air flowing on the surface side of the membrane and the amount of air flowing through the _bypass means is preferably 0.3 to 0.95, more preferably in the range of 0.5 to 0.90, and particularly 0.65 or more is good. Note that V _B /Vt means the ratio of the respective flow rates at the same pressure and temperature. In the oxygen enricher of the present invention, by setting V _B /Vt in such a range, it is easy to supply appropriate air to the membrane surface side, and it is also very easy to control the cooling air volume of the pressure reducing means. This is something that can be realized. Furthermore, the oxygen enricher of the present invention has such a V _B /Vt
In order to ensure an air flow rate in the range of , a flow rate adjusting means is provided in either or both of the air flow path connected to the space on the membrane surface side and the flow path of the bypass means. Examples of the flow rate adjusting means include a shielding plate opening/closing mechanism, a valve, an orifice, etc. Among them, a shielding plate opening/closing mechanism, that is, a so-called damper mechanism is preferred because it is easy to adjust. Such an opening/closing mechanism may be a manual type, but it may also be automatically opened/closed by, for example, an electric motor such as a small pulse motor. The flow rate regulating means may be used for both the flow path of the bypass means and the air flow path connected to the space on the membrane surface side, but it is preferable to use it only for the bypass means, and especially for the downstream part of the bypass means. It is preferable to provide one. 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 entrance 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. 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 in order 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・ 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 surface thereof may have the permselective performance. In particular, in the case of an inner surface film that has selective properties on its 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 portion in this way, the inner diameter is preferably in the range of 100 μ or more, more preferably 300 μ or more, in order to keep the pressure loss in the hollow portion low. 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 air blowing means used in the enrichment device is not particularly limited, and examples thereof include fans such as white pepper turbo fans and axial flow fans, and blowers. Further, the oxygen enricher of the present invention preferably includes 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 and bad odors such as NOx and SOx, 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 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. Each of the flow path of incoming air to the air inlet and the flow path of exhaust air from the air outlet of the soundproof box to the outlet provided in the outer shell of the enricher is inspected at least once, more preferably. In order to prevent the generation of noise, 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 heat pump to warm the air, or some of the warmed air that should be exhausted can be recirculated and introduced 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. 1, a membrane module containing a bundle of 7,300 oxygen selectively permeable hollow fiber membranes with an inner diameter of 700μ, an outer diameter of 1000μ, and a length of approximately 25cm, a Sirotsko Turbo, and a vacuum were used. An oxygen enricher with pump and filter was assembled. At that time, the fans of Example 1 and the fans of Example 2 with different capacities were used, operated under the conditions shown in Table 1, and the power consumption of the fans was evaluated. The results shown in the table were obtained. Further, as a comparative example, an evaluation was performed for the case in which the flow path was blocked without using the bypass in Example 2, and the results obtained are also 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, the present invention makes it possible to easily obtain oxygen-enriched air at a high flow rate, requires relatively little power consumption during operation, makes it easy to prevent noise generation, and makes it easy to make the entire enrichment device compact. Effects can be obtained.

[Brief explanation of drawings]

1 to 3 are schematic flow sheets showing embodiments of the oxygen enricher according to the present invention. FIG. 4 shows a schematic flow sheet of an oxygen enricher as a reference example. In the figure, 1 is a membrane module, 4 is a pressure reducing means, 5 is a blower means, and 9 is a filter means.

Claims (1)

[Claims] 1. A module having a plurality of arrays of separation functional parts equipped with selective oxygen permeable membranes, and maintaining a certain degree of vacuum on the back side of the membrane in the module and extracting oxygen-enriched air from there. In an oxygen enricher having a depressurizing means for generating air flow, and a blowing means for generating an air flow on the other side of the membrane in the module, a part of the air flow generated from the blowing means is circulated. is provided with a bypass means that does not pass through the back side of the membrane, and the depressurizing means is cooled by the oxygen-depleted air flowing through the front side of the membrane and the atmospheric flow flowing through the bypass means. An oxygen enricher featuring: 2 Ratio of the air flow V _B flowing through the bypass means to the total flow rate Vt of the air flow flowing on the surface side of the membrane and the air flow flowing through the bypass means
The oxygen enricher according to claim 1, wherein V _B /Vt is 0.3 to 0.95. 3. Oxygen enrichment according to claim 1, characterized by comprising means for adjusting the flow rate of air flowing on the surface side of the membrane and/or means for adjusting the flow rate of air flowing through the bypass means. vessel. 4. The oxygen enricher according to claim 1, wherein the separation function section uses a selective oxygen permeable membrane in the form of a flat membrane, a tube, or a hollow fiber. 5. The oxygen enricher according to claim 1, comprising a filter means through which only air flowing into the surface side of the membrane module passes.