JPS6119563B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that stably and efficiently obtains oxygen-rich air from the atmosphere using a selectively permeable membrane that allows oxygen to permeate at a higher rate than nitrogen. This invention relates to an oxygen enricher using a membrane method suitable for use in various applications.

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.

However, when inhaling air with a high oxygen concentration of 60% or more in this oxygen inhalation method, it is known that it can cause pneumonia symptoms and neurological disorders, which can be harmful instead of having a therapeutic effect. 50% or less is generally used as it is safe to use.

On the other hand, most current oxygen sources are obtained by cryogenic separation and supplied into pure oxygen cylinders, or by directly evaporating liquefied oxygen and supplying it through piping. Strict management is required, such as mixing and diluting gas with air to lower the desired oxygen concentration, monitoring oxygen depletion, strict fire control with pure oxygen gas, and handling of high-pressure cylinders. Transportation is complicated. Therefore, this method is difficult to use especially in a general household.

On the other hand, as a method for separating and concentrating oxygen in the atmosphere, an adsorption separation method using an adsorbent such as zeolite that adsorbs nitrogen more selectively than oxygen is known. Medical oxygen enrichers based on this adsorption separation method have recently been developed, but due to the need for air to be adsorbed and released by the adsorbent, the operating pressure is a so-called pressure swing method in which pressurization and/or depressurization are repeated. The noise is loud and the noise repeats getting louder and louder, causing pain to users, especially sick people. Furthermore, the oxygen concentration obtained by this adsorption method is generally high oxygen concentration air of 50 to 90%, and since the adsorbent absorbs more water vapor, the obtained air is dry air, suitable for inhalation therapy. separate humidification is required.

There, oxygen-enriched air is continuously obtained from the air,
Moreover, the enriched air has an oxygen concentration of less than 50%, which is safe for long-term inhalation, and if a small, low-noise, durable oxygen enricher could be developed, it would be useful for the respiratory system over a long period of time. This is extremely desirable for people with the disease.

As an oxygen enricher meeting such requirements, an enricher based on a membrane method using a selective oxygen permeable membrane that can permeate oxygen at a higher rate than nitrogen has been proposed (for example, Japanese Patent Application Laid-Open No. 1989-1999). 6876, Japanese Patent Publication No. 1973-
(See Publication No. 5291).

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 is humidified, so humidification is not required especially when inhaling oxygen-enriched air, and the membrane itself is a super filter, so it does not contain dust. Decompression type membrane oxygen enrichers are suitable for medical use because they provide clean air that is completely free of bacteria and bacteria, and when the operating pressure is reduced only, i.e., when a vacuum pump is used, a low-noise enricher can be created. It can be said to be the most suitable enrichment device.

By the way, as mentioned above, the oxygen-enriched air obtained by the membrane method has a higher water vapor permeation rate, so the water vapor contained in the air is concentrated. To explain this in more detail and quantitatively, in an oxygen selectively permeable membrane made of a general polymer, the water vapor permeation coefficient is usually an order of magnitude larger than the oxygen permeation coefficient. The side in contact with the gas (hereinafter referred to as the source side, high pressure side, or atmospheric side) is under atmospheric pressure (usually 760 Torr), and the side through which gas permeates (hereinafter referred to as the permeation side, low pressure side, or enriched air side) is under reduced pressure. The proportion of water vapor in the enriched air that has passed through the membrane in this state and the concentration rate of water vapor relative to the atmosphere are approximately expressed by the following equation.

t ₁ = RHR・hs/PL t ₀ =RH _R・hs/P _H y=t ₁ /t ₀ =P _H / _PL [Here, t ₁ is the water vapor ratio in enriched air (v/v% ) t ₀ ; Water vapor percentage in the atmosphere (v/v%) RH _R ; Relative humidity on the atmospheric side (%) hs; Saturated water vapor pressure at atmospheric temperature (mmH
g) P _L : Low pressure side pressure (Torr) P _H : Atmospheric side pressure (usually 760) (Torr) y : Water vapor concentration ratio (-) in enriched air relative to the atmosphere.

In the range of practical vacuum pumps that can be used in medical oxygen enrichers, the low pressure side pressure P _L is usually 100 to 200 Torr.
Then, by applying the above formula, the high pressure side pressure P _H is
Calculating the water vapor concentration factor y as 760Torr is 3.8~
The water vapor contained in enriched air does not condense under reduced pressure or high temperature, but when it moves to normal pressure and/or the temperature drops, the water vapor condenses easily and the water vapor in the conduit section is reduced. It forms water droplets and adheres to the surface.

Such water droplets generated in the conduit do not become a breeding ground for bacteria in a sterile atmosphere, such as immediately after membrane permeation, but they may come into contact with the atmosphere when not in use, such as in the conduit coming out of an enricher. In areas where there is a possibility of condensation, bacteria may infiltrate or adhere to the air, making it unsuitable for inhalation air during subsequent use.Moreover, even if the air is sterile, moisture adhering to the inside of the conduit may reach the patient's enriched air inhalation area. Not only does it cause discomfort to the patient when it is transported, but it can also cause coughing and sneezing.
For this reason, in oxygen enrichers that employ the membrane method, means have been devised to actively remove excess water inside the enricher. In general, a conduit through which the oxygen-enriched air coming out of a vacuum pump passes is configured in the form of a heat exchanger that efficiently contacts the incoming air, and the heat exchanger-like conduit (hereinafter abbreviated as cooling means) is used to enrich oxygen. Means for cooling enriched air to a temperature close to that of the intake air, condensing excess moisture, and separating the condensed excess moisture from enriched air containing non-condensed water vapor and oxygen-enriched air (hereinafter abbreviated as moisture separation means) is installed to remove excess moisture.

However, even with such a configuration of the cooling means and water separation means, the temperature of the enriched air cooled by the cooling means cannot drop below the intake air temperature, and is generally about 0.5 to 2 degrees Celsius higher. Although the rate of generation of water droplets in the conduit exiting from the enrichment device is slow, they form on the conduit wall and eventually grow, moving towards the patient due to the viscous force associated with the movement of enriched air. Then, the problems seen in the patient described above occur. This phenomenon is noticeable when a cooler is used during high temperature and humidity such as in the summer, or when doors are opened and closed or windows are opened and closed for ventilation in the winter. In other words, when using a cooler in the summer, there are fluctuations in the room temperature due to the temperature control of the cooler, and the conduit (abbreviated as transport conduit) that exits the enricher is small in size and has a small heat capacity, so the outer wall of the conduit is is rapidly cooled by cold air (meaning indoor circulating air with a temperature lower than the average room temperature) to a temperature below the average room temperature.On the other hand, the enricher itself has a large heat capacity, and the enriched air discharged from the enricher has a temperature lower than the average room temperature. Since the temperature does not drop much below room temperature, as a result, water droplets are rapidly generated within the transport conduit, and once generated, the water droplets are not easily re-evaporated, resulting in accumulation of water droplets within the transport conduit. On the other hand, in the winter, when cold air enters when a door or window is opened or closed, the cold air flows near the floor, and the air temperature near the floor becomes much closer to the average room temperature. Generally, the above-mentioned transport conduit is often placed on the floor from the enricher to the patient's inhalation site, and when such cold air enters, the outer wall of the transport conduit is cooled to below the average room temperature, making it easy to This induces the generation of water droplets, resulting in the same problem as when using a cooler in the summer described above.

As a countermeasure for this, measures have been taken, such as installing a trap just before the patient's inhalation site to remove moisture generated within the transport conduit, or using a conduit with a heater to keep the transport conduit warm or to place a heating means along the transport conduit. However, the former method can become a breeding ground for bacteria if special care is not taken, and the latter method, in which conduits are modified, becomes larger and more expensive, and reduces the flexibility of the conduit, making it inconvenient to handle.

The inventors of the present invention have arrived at the present invention as a result of extensive research aimed at solving the above-mentioned problems during use by taking advantage of the feature of membrane-based oxygen enrichers that do not require humidification.

That is, the present invention provides an oxygen enricher for obtaining oxygen-enriched air from the atmosphere, which comprises a module containing a large number of arrays of elements made of selective oxygen permeable membranes, the inside of each element of the module being reduced in pressure, and a vacuum pump for removing oxygen-enriched air, means for creating an atmospheric flow through said arrangement, reducing the temperature of the oxygen-enriched air exiting the vacuum pump in contact with the atmospheric flow introduced from outside the vessel; It mainly consists of a cooling means for condensing water vapor contained in excess in the enriched air, a moisture separation means for separating the condensed moisture from the oxygen-enriched air, and a means for taking out the oxygen-enriched air for use, the cooling arrangement being At least a part of the part that is installed in the flow of air toward the arrangement and comes into contact with the flow of air has a member or portion that has a function of retaining the moisture separated by the moisture separation means. It is an oxygen enricher.

Such an oxygen enricher of the present invention is capable of efficiently supplying oxygen-enriched air without the generation of water droplets in the transport conduit toward the patient using the oxygen enricher.

The enricher of the present invention will be explained in more detail with reference to the drawings, but the drawings merely show one embodiment of the present invention, and the present invention is not limited by the drawings.

Figure 1 schematically shows the configuration of an oxygen enricher using the membrane method, and the broken lines indicate the air flow on the atmospheric side.
The solid line indicates the flow on the oxygen-enriched air side. As shown by the broken line, indoor air around the oxygen enricher is introduced into the oxygen enricher through the air intake port 1, contacts the cooling means 2, and is then sent into the module 4 by the fan 3. The air with reduced oxygen concentration (depleted air) is discharged from the air outlet 6 to the outside of the oxygen enricher after cooling the vacuum pump 5. Such an air flow path is generally formed by devising the internal casing structure of the oxygen enricher.

A large number of elements (not shown) made of selective oxygen permeable membranes are arranged in the module 4. On one side of the permeable membrane of the element, there is a flow path through which room air is swept by the fan 3, and on the other side there is a flow path through which the indoor air is swept by the fan 3. A flow path is provided for the enriched air that has permeated through the membrane, and when the permeable membrane is formed in the form of a hollow fiber, the hollow fiber itself constitutes the flow path; In the case where there is a structure (generally called frame lamination or spiral), consideration is usually given to providing a flow path forming member on the permeation side to ensure a smooth flow of oxygen-enriched air. When there is a pressure difference on both sides of a permeable membrane having such a structure, air with a high oxygen concentration can be obtained on the permeate side depending on the pressure ratio on both sides. By the way, when the pressure on the high pressure side is 760 Torr (atmospheric pressure), the pressure on the low pressure side is 160 Torr, and the selectivity of the permeable membrane is 4 (oxygen permeation rate is 4 times that of nitrogen), when normal air is supplied. The oxygen concentration in oxygen-enriched air is approximately 40%.

When the pressure ratio generating means, that is, the high pressure side is atmospheric pressure, a vacuum pump 5 is provided as a reduced pressure generating means, and the suction port 7 of the vacuum pump 5 is connected to a conduit means 8 for collecting enriched air generated in the element. 9, the enriched air is compressed in the vacuum pump 5, and is discharged from the discharge port 10 into the conduit 1 at a pressure higher than atmospheric pressure.
1.

The other end of the conduit 11 is connected to a cooling means 2, in which the high temperature enriched air discharged from the discharge port 10 of the vacuum pump 5 and the swept room air exchange heat, and the high temperature The enriched air is cooled to a temperature close to room temperature, and excess water vapor contained in the enriched air is cooled and condensed. The enriched air mixed with water droplets that has been cooled in this way is led to the moisture separation means 14 through the conduit 13, and is separated into enriched air containing condensed water and saturated water vapor. 15, the air is led to a pressure reducing means 16 for moisture adjustment, and a conduit 17, and is put into use by monitoring the flow rate with a flow meter 19 and adjusting the flow rate with a flow rate control valve 18 to obtain the enriched air flow rate necessary for suction therapy. , while the moisture separated by the moisture separation means 14 is discharged via the conduit 20. At this time, when the cooling means 2 is simply brought into contact with the indoor air, the temperature of the enriched air to be cooled cannot be lower than the temperature of the indoor air, and is usually lower than the indoor air temperature.
The temperature is about 0.5 to 2 degrees Celsius higher, and as mentioned above, the problem of water droplets adhering to the transport pipe from the oxygen enricher occurs. For this purpose, a depressurizing means 16 for regulating moisture is provided downstream of the oxygen-enriched air from the moisture separating means 14, and the pressure when moisture is condensed in the cooling means 2 is made higher than the atmospheric pressure, so that the water vapor partial pressure of the enriched air is adjusted to the indoor air temperature. Measures are taken to keep the partial pressure of saturated water vapor below the equivalent of . If such a measure is taken, the above-mentioned problem of water droplet adhesion in the transport conduit can be solved by increasing the pressure during condensation, but the conduit 20
If there is no way to generate a considerably large pressure drop inside the pipe, the leakage of oxygen-enriched air from the conduit 20 will increase, the amount of oxygen-enriched air led to the conduit 15 will decrease, and the discharge side of the vacuum pump will be pressurized considerably. Due to this condition, new problems occur such as a decrease in the discharge flow rate and an increase in the required power, and the pressure drop cannot be unnecessarily increased by the pressure reducing means 16.

However, in the present invention, the moisture separated by the moisture separation means 14 is led to the outer surface 21 of the cooling means 2 (i.e., the part that comes into contact with indoor air) via the conduit 20,
Since moisture and indoor air are in contact with the outer surface portion 21, the moisture adhering to the outer surface portion 21 evaporates depending on the relative humidity of the indoor air, and the temperature of the outer surface portion 21 is lower than the indoor air temperature by a temperature corresponding to the latent heat of evaporation of this evaporated moisture. is supercooled, and the surface temperature of the heat exchange part of the cooling means 2 is cooled to substantially below the indoor air temperature. In the configuration and structure of a normal oxygen enricher, this supercooling temperature is 1 to 4 degrees Celsius, depending on the relative humidity of the indoor air, and the temperature of the enriched air generated is the same as or lower than room temperature, as mentioned above. The problem of moisture adhesion in transport conduits is eliminated. In a room with a constant temperature, the function of the oxygen enricher can be fully demonstrated with this configuration alone without using the above-mentioned decompression means, but the temperature in the room is generally constantly fluctuating locally, and these small In order to cope with wide but steep temperature changes, it is desirable to use the above-mentioned pressure reduction means in combination, especially when the cold air temperature changes due to the cold air when opening and closing the door during indoor relaxation in winter, or when the cooler is turned on and off during air conditioning in summer. Valid in certain cases.
Therefore, a more preferable configuration of the oxygen enricher is one in which the degree of pressure reduction of the pressure reduction means can be adjusted.
In hospitals and the like that employ general air conditioning systems, temperature changes due to cold air and the like are small throughout the year, and the pressure reduction means described above is not necessarily necessary.

An efficient method for supercooling oxygen-enriched air according to the present invention is to supercool the oxygen-enriched air all around the cooling means, but if the indoor relative humidity is low, In addition, when a configuration with a high moisture evaporation rate is provided, the temperature of the oxygen-enriched air may drop too much due to supercooling. must be carried out. Naturally, in an embodiment where the water evaporation rate is slow, the area of the supercooling part in the heat exchange area of the cooling means increases.

Various embodiments of supercooling will be described in further detail below. In order to ensure that the moisture separated by the moisture separation means is retained in the cooling means, the supercooling section (hereinafter referred to as supercooling section) of the cooling means must have hygroscopicity or a moisture retention function. In addition, in order to efficiently evaporate adhering moisture, it is necessary to adopt a configuration in which the rate of heat transfer between indoor air and oxygen-enriched air is high.

The most common method is to attach a thin layer of moisture-absorbing material such as gauze, nonwoven fabric, or cotton to the supercooled part, and to retain moisture between the fibers and meshes of these materials. In this case, since the amount of moisture retained per unit area of the moisture absorbing member is large and the heat transfer rate is also high, a supercooled portion of about 1/5 to 1/3 of the entire surface of the cooling means is usually sufficient.

When providing a partial supercooling section like this, it is desirable to do it in a place where the temperature of the indoor air is as low as possible and the oxygen-enriched air is also as low as possible, so the cooling means are arranged countercurrently. It is preferable to make the room air into an upward air current in view of the internal structure of the vessel. Therefore, it is preferable to install the supercooling section from the bottom of the cooling means.

On the other hand, if you want to use the surface tension of water to retain moisture in the supercooled area, you can use porous sponge, wire mesh, etc.
Plastic nets, etc. can be used. At this time, the water retention function is relatively small and the heat transfer rate depends on the thermal properties of the water, so care must be taken when implementing this method.
According to the study results of the present inventors, it is preferable that the moisture retention amount is 10 v/v % or more based on the volume of the member, and the total thickness of the member is 2 mm or less.

2 or 3 is preferable as a supercooling section structure that utilizes surface tension and increases the heat transfer rate. In Figure 2, thin fins, ie, fins 30a and 30b, are provided around the cooling means to retain water on the fin surface and evaporate the water one after another or while flowing over the fins. Heat transfer occurs primarily through the fins.
The fins may be of any shape as long as they are plate-shaped and have excellent thermal conductivity, but metal wire mesh is preferred because it improves moisture retention, and the fins can also be formed in a spiral shape. suitable.

FIG. 3 shows a structure in which water is retained on the surface of the supercooled part itself, and unevenness 32 is provided on the surface of the cooling means. Although the area of the supercooled part is large, the structure is simple, and if the concavities and convexities are formed in a spiral shape, the performance will be even better.

[Brief explanation of the drawing]

Figure 1 is an overall configuration diagram showing the flow of air in the oxygen enricher and the effects of each part.
Each figure is a diagram showing an example of a partially enlarged view of the cooling means used in the oxygen enricher of the present invention.

Claims (1)

[Scope of Claims] 1. An oxygen enricher for obtaining oxygen-enriched air from the atmosphere, which comprises a module containing a large number of arrays of elements made of selective oxygen permeable membranes, the inside of each element of the module being reduced in pressure. , and a vacuum pump for removing oxygen-enriched air, means for creating an atmospheric flow through said arrangement, reducing the temperature of the oxygen-enriched air exiting the vacuum pump in contact with the atmospheric flow introduced from outside the vessel; and mainly comprises a cooling means for condensing water vapor contained in excess in the oxygen-enriched air, a moisture separation means for separating the condensed moisture from the oxygen-enriched air, and a means for taking out the oxygen-enriched air for use, and the cooling means is installed in the flow of air toward the arrangement, and at least a part of the part that comes into contact with the flow of air has a member or portion that has a function of retaining the moisture separated by the moisture separation means. Oxygen enricher. 2. An oxygen enricher according to claim 1, comprising a pressure reduction means between the moisture separation means and the means for removing the oxygen-enriched air for use. 3. The oxygen enricher according to item 1 or 2, which has a moisture absorption member such as gauze, nonwoven fabric, or cotton surrounding a part or all of the outside of the cooling means for retaining the water separated by the water separation means. . 4. A porous sponge, wire mesh, or plastic net with a moisture retention capacity of 10 v/v% or more and a thickness of 2 mm or less that surrounds part or all of the outside of the cooling means for retaining the moisture separated by the moisture separation means. 2. The oxygen enricher according to claim 1 or 2, having a moisture retaining member such as. 5. Part or all of the outer surface of the cooling means is
3. The oxygen enricher according to item 1 or 2, which has an uneven surface and the uneven surface has a function of retaining moisture.