JP2009089777A - Oxygen concentrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure variable adsorbing type oxygen concentrator promoting nitrogen gas desorption from an adsorbent and enhancing oxygen generating efficiency. <P>SOLUTION: The pressure variable adsorbing type oxygen concentrator includes two or more of adsorbing beds accommodating at least the adsorbent adsorbing nitrogen more than oxygen, a compressing means, a switching means, and a purge gas communication path for communicating the adsorbing beds and is characterized by heating purge gas flowing through the purge gas communication path using the heat released from the compressing means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an oxygen concentrator for separating oxygen in air and supplying it to a user.

  In recent years, the number of patients suffering from chronic respiratory diseases such as pulmonary emphysema, pulmonary tuberculosis sequelae and chronic bronchitis tends to increase. As a treatment method for such patients, oxygen inhalation therapy for inhaling high concentration oxygen is performed. The oxygen inhalation therapy is a treatment method for inhaling oxygen gas or oxygen enriched gas to the diseased patient. Examples of the supply source of therapeutic oxygen gas or concentrated oxygen gas include the use of high-pressure oxygen cylinders, liquid oxygen cylinders, oxygen concentrators, etc., which can withstand long-term continuous use and are easy to use. For this reason, cases of using oxygen concentrators are increasing.

  The oxygen concentrator is an apparatus that can separate and concentrate oxygen in the air. As an apparatus for separating and concentrating oxygen, one or a plurality of adsorbent beds are packed with an adsorbent capable of selectively adsorbing nitrogen in the air from the viewpoint that high concentration oxygen of 90% or more can be obtained. Adsorption type oxygen concentrators are widely known and used. The concentration method of the adsorption-type oxygen concentrator is roughly classified into two methods, a pressure swing adsorption method and a temperature swing adsorption method, depending on the difference in the adsorption method. The pressure swing adsorption method is a method of taking out the target product gas by utilizing the fact that the amount of gas adsorbed on the adsorbent increases as the partial pressure of the target gas increases, while the temperature swing adsorption method is applied to the adsorbent. This is a method of taking out the target product gas by utilizing the fact that the adsorption amount of the gas increases as the temperature decreases. In medical oxygen concentrators, pressure swing adsorption type oxygen concentrators using a pressure swing adsorption method (hereinafter referred to as PSA) and using a compressor as a compression means are widely used in the world. That is, the pressure fluctuation adsorption type oxygen concentrator usually supplies at least compressed air from a compressor to one or a plurality of adsorption beds filled with an adsorbent that selectively adsorbs nitrogen, and the nitrogen in the adsorption bed Adsorption process to increase the partial pressure to adsorb nitrogen to the adsorbent and obtain high concentration of unadsorbed oxygen, and desorb nitrogen from the adsorbent by reducing the pressure in the adsorbent bed and lowering the partial pressure of nitrogen This is a device that has a desorption step that is repeated, and repeats this in a constant cycle to continuously obtain a high concentration of oxygen. PSA includes a PSA (Pressure Swing Adsorption) method in which a desorption process for regenerating an adsorbent is performed at atmospheric pressure, and a VPSA (Vacuum Pressure Swing Adsorption) method in which the adsorption bed is depressurized to a vacuum with a vacuum pump.

  Here, as a method of lowering the partial pressure of nitrogen in the desorption step, there is a method of lowering the nitrogen concentration in the gas phase in addition to the method of reducing the pressure in the adsorption bed. As an industrial means for lowering the nitrogen concentration, a part of the concentrated oxygen gas is refluxed to the adsorption bed during the desorption regeneration process, and the nitrogen partial pressure is lowered by lowering the nitrogen concentration in the gas phase. Promoting methods are widely adopted. This method is called a purge method, and the adsorbent on the outlet side of the adsorption bed is more desorbed and regenerated. Therefore, this method is very effective in improving the purity of the product oxygen gas separated and concentrated in the adsorption bed. (JP-A-4-363110). Attempts to improve the purge method have been made in several ways.

  For example, in Japanese Patent Laid-Open No. 4-363110, in this purge method, if the concentration of oxygen gas toward the adsorption bed is high, the adsorbent on the adsorption bed outlet side can be regenerated as intended. In the case of a low concentration, the oxygen concentration in the adsorption bed deteriorates as a problem that the conventional technology cannot solve, and the purge method is improved. The technology described in the publication discloses that the adsorption bed to be desorbed and the adsorption bed pressure is controlled so that the pressure of the gas sent to the adsorption bed becomes a low pressure, so that the nitrogen from the adsorption bed to be desorbed and regenerated It has the feature of improving the desorption efficiency.

However, in this case, at least three or more adsorption beds are provided, and two or more adsorption beds including a highly oxygen-concentrated adsorption bed need to be in a low pressure state in a certain adsorption bed purge step. . That is, this method has a drawback that it cannot be applied to a PSA oxygen concentration process using an adsorption bed of 2 beds or less.
In JP-A-7-155526, vacuum pressure swing adsorption separation (Vacuum Pressure Swing Adsorption) in which the pressure is reduced to a vacuum at the time of desorption does not use a normal purge method. The problem is that the adsorbent deteriorates quickly.

  Therefore, the technique described in this publication discloses a method of performing a purge by sending a constant amount of high-concentration oxygen from a product tank that stores the product gas when the adsorption bed internal pressure in the desorption process becomes a constant pressure. . However, according to this method, there is a problem that it is necessary to perform a flow path or control to flow backward from the product side to the adsorption bed, and the process and operation control become complicated.

  Japanese Patent Application Laid-Open No. 7-267612 discloses a technique related to an apparatus that obtains high concentration oxygen of 99.5% or more using a PSA process. Although there is a method for obtaining a high concentration of oxygen by roughly dividing the concentrating portion into a coarse concentrating portion and a high concentrating portion, the problem is that the disclosed contents of the prior art are not concrete. In this publication, a technique for using the gas obtained in the roughly desorbed and desorbed recovery step and the gas obtained in the highly concentrated portion regeneration step as the purge gas is disclosed, and the purge gas acquisition means is described more specifically. . However, the fact that there are two series of concentrating parts and each is composed of different adsorbents has problems in that the process control is complicated and the number of parts increases.

  By the way, as already mentioned above, there is a temperature swing adsorption method (hereinafter referred to as TSA) as a technique similar to PSA. In TSA, the adsorption bed is set to a low temperature at the time of adsorption and the adsorption bed is set to a high temperature at the time of desorption, and further, the purge gas is generally heated. However, the purge gas used in TSA is heated using another heat source such as an electric heater. Japanese Patent Laid-Open No. 2005-104740 proposes a solution for this problem, taking this point as a problem. The technology described in the publication uses the exhaust gas of combustion equipment such as an incinerator as a purge gas. However, the technology of this method is a technology used in the field where highly heated exhaust gas is generated, such as a boiler and a combustion device, and it is not practically installed in a concentrated oxygen generator without a combustion device. Have difficulty. Moreover, it is a premise to use the gas heated up with the combustion apparatus to the last, and the point that a separate heating source is required is a problem like the prior art.

  Here, a compressor is mentioned as a heat source in the pressure fluctuation adsorption type oxygen concentrator. The temperature of the compressor rises due to the heat generated when compressing the gas. However, as the temperature rises, the efficiency is reduced and the service life is shortened, so cooling means are provided to lower the temperature. In general, an efficient cooling method has been proposed (Japanese Patent Laid-Open No. 2005-304861).

JP-A-4-363110 JP-A-7-155526 JP-A-7-267612 JP 2005-104740 A JP 2005-304861 A

  As described above, it is not yet a sufficient technique for efficient use of the purge gas in the PSA from the viewpoint of complicated equipment and control. On the other hand, in TSA, it is common to heat the adsorption bed and purge gas in the process of desorbing and regenerating the adsorbent, and it is known that desorption is promoted by heating, but a heat source for heating is required. Therefore, the required power of the heat source becomes a problem. In addition, it is difficult within the scope of the prior art to increase the purge efficiency by mounting the TSA configuration in a pressure fluctuation adsorption type oxygen concentrator.

  The present invention solves the above-mentioned problem, and the nitrogen gas from the adsorbent in the desorption process is heated by heating the purge gas using the heat generated from the compression means serving as a heat source in the pressure fluctuation adsorption type oxygen concentrator. By promoting desorption, a pressure fluctuation adsorption type oxygen concentrating device with better oxygen generation efficiency is provided.

That is, the present invention is a flow for switching between at least two adsorbent beds containing adsorbents that adsorb nitrogen from oxygen, air compression means for supplying pressurized air to the adsorbent beds, and adsorption / desorption processes in the adsorbent beds. A path switching means and a purge gas communication line for connecting the adsorption beds to each other and flowing a part of oxygen gas to the other adsorption bed, and further, heat generated by the air compression means flows through the purge gas communication line. Provided is a pressure fluctuation adsorption type oxygen concentrating device comprising a heat conduction means for transmitting to a purge gas and heating.
The present invention includes a pressure fluctuation adsorption type oxygen concentrator characterized in that heat generated from the compression means is sent to the purge gas communication line by a blower means to warm the purge gas.

  Furthermore, the present invention provides a pressure fluctuation adsorption type oxygen concentrator using the heat generated from the compression means and warming the purge gas when the compression means and the purge gas communication line are in close contact with each other.

  The present invention also provides a method for operating an oxygen concentrator for pressure swing adsorption, wherein the cooling means operates in conjunction with the switching means at the start of operation. At the start of operation, the temperature of the compression means that serves as a heat source for heating the purge gas has not increased. Therefore, by delaying the operation of the cooling means, the utility value of the compression means as the heat source can be increased.

The present invention provides a pressure fluctuation adsorption-type oxygen concentrator with good oxygen generation efficiency because the purge gas is heated using the heat generated by the compression means to promote the desorption of nitrogen gas from the adsorbent by the purge. be able to.
In addition, since the operation for increasing the purge efficiency is performed at the start of the operation, the oxygen concentration in the initial operation is stabilized at a high concentration early.

  An embodiment of the oxygen concentrator of the present invention will be described by taking a two-cylinder pressure fluctuation adsorption type oxygen concentrator as an example. The pressure fluctuation adsorption type oxygen concentrator includes an external air intake filter, a compressor having a compression function, a solenoid valve that is a flow path switching valve, an adsorption cylinder, a product tank, a pressure regulating valve, a flow rate setting means, and a filter. Thus, an oxygen-enriched gas is produced by concentrating oxygen gas from the raw material air taken in from the outside.

  First, the raw material air taken in from the outside is taken in from an air intake port provided with an external air intake filter for removing foreign matters such as dust. At this time, the normal air contains 1.2% of about 21% oxygen gas, about 77% nitrogen gas, 0.8% argon gas, water vapor and other gases. In such an apparatus, only oxygen gas necessary as a breathing gas is concentrated and extracted.

  The oxygen gas is taken out from the adsorption cylinder filled with an adsorbent made of zeolite or the like that selectively adsorbs nitrogen gas molecules rather than oxygen gas molecules. While switching, the source air is pressurized and supplied by a compressor, and approximately 77% of nitrogen gas contained in the source air is selectively adsorbed and removed in the adsorption cylinder.

  The adsorption cylinder is formed of a cylindrical container filled with the adsorbent, and usually a multi-cylinder type of three or more cylinders is used in addition to the one-cylinder type and the two-cylinder type. In order to produce oxygen-enriched air from raw material air, it is preferable to use a two-cylinder or multi-cylinder type adsorption cylinder.

  Further, the compressor may be a compressor having not only a compression function but also a vacuum function. In this case, the vacuum function side is attached to a flow path for discharging the desorbed nitrogen-enriched gas outside the apparatus. When providing such a vacuum function, the compressor may be equipped with one compressor each having a compression function and a vacuum function.

For example, as a compressor to be used, a rotary air compressor such as a screw type, a rotary type, or a scroll type may be used in addition to a swing type air compressor. Further, the power source of the electric motor that drives the compressor may be alternating current or direct current. Usually, an inverter is mounted to control the rotation speed and to control the discharge amount of pressurized air from the compressor.
Oxygen-enriched air mainly composed of oxygen gas that has not been adsorbed by the adsorption cylinder flows into the product tank via a check valve provided so as not to flow backward to the adsorption cylinder.

  The nitrogen gas adsorbed by the adsorbent filled in the adsorption cylinder needs to be desorbed from the adsorbent in order to adsorb nitrogen gas again from the newly introduced raw material air. For this purpose, the pressurized state realized by the compressor is connected to the decompression line by an electromagnetic valve, and the state is switched to the decompressed state, and the adsorbent is regenerated by desorbing the adsorbed nitrogen gas. Further, in this desorption process, in order to increase the desorption efficiency, the oxygen-enriched gas may be caused to flow back as a purge gas from the product end side of the adsorption cylinder during the adsorption process via a pressure equalizing valve.

  Oxygen-enriched air is produced from the raw air and stored in the product tank. The oxygen-enriched air stored in this product tank contains high-concentration oxygen gas, for example 95%, and is supplied to the humidifier while its supply flow rate and pressure are controlled by a pressure regulating valve, flow rate setting means, etc. And humidified oxygen-enriched air is supplied to the patient.

  In such a humidifier, a moisture permeable membrane module having a moisture permeable membrane takes in moisture from external air and supplies it to dry oxygen-enriched air, a bubbling humidifier using water, Alternatively, a surface evaporation humidifier can be used.

In a two-cylinder type oxygen concentrator, when one adsorption cylinder is performing a pressure adsorption process, the other adsorption cylinder performs a vacuum desorption process, and sequentially switches the adsorption and desorption processes in reverse phase, Oxygen is continuously generated.
Since the above-described compressor generates heat during operation, it is necessary to cool the inside of the apparatus. Generally, cooling is performed using a dedicated fan for cooling.

  As one embodiment of the present apparatus, in order to particularly effectively heat the purge gas, the compressor as the maximum heat source is first cooled by a cooling fan, and a purge line is installed so that the heated cooling air is applied. (FIG. 1). By adopting such a design, it is possible to heat the purge line without having any new heating source.

  In another embodiment, the compressor and the purge line are brought into close contact (FIG. 2). In this case, the heat of the compressor warms the purge gas in the purge line by heat conduction, and the nitrogen gas desorption from the adsorbent in the purge is promoted.

In addition, it is assumed that the compressor is not sufficiently warm at the start of operation of the pressure fluctuation adsorption device. By delaying the start-up of the cooling fan from the start-up of the device, the temperature of the compressor is raised in a short time after the start-up of the device, and the start-up of the cooling fan after reaching a temperature at which the purge gas can be heated This is desirable from the viewpoint of promoting nitrogen gas desorption. As an indication of the operation of the cooling fan, the compressor surface temperature may be measured, and the cooling fan may be started when the temperature reaches a predetermined temperature.
The surface temperature of the compressor may be measured by a thermocouple or other temperature measuring elements.

The schematic block diagram of the pressure fluctuation adsorption type oxygen concentrator of this invention. The schematic block diagram of the pressure fluctuation adsorption type oxygen concentrator of this invention.

Explanation of symbols

1 Compressor 2a, 2b, 3a, 3b selector valve
4a, 4b Adsorption bed 5a, 5b Check valve 6 Pressure equalizing valve 7 Cooling fan

Claims (8)

  Two or more adsorbent beds containing adsorbents that adsorb nitrogen from oxygen, air compression means for supplying pressurized air to the adsorbent beds, flow path switching means for switching the adsorption / desorption process in the adsorption beds, A purge gas communication line that allows the adsorbent beds to communicate with each other and allows a portion of oxygen gas to flow to the other adsorption bed; and further, heat generated by the air compression means is transmitted to the purge gas flowing through the purge gas communication line. A pressure fluctuation adsorption type oxygen concentrating device comprising a heat conducting means for heating.   2. The pressure fluctuation adsorption type oxygen concentrator according to claim 1, wherein the heat conducting means is a blowing means for blowing heat generated from the air compression means to the surface of the purge gas communication pipe line.   2. The pressure fluctuation adsorption type oxygen concentrator according to claim 1, wherein the heat conducting means is a structure in which the purge gas communication pipe line is in close contact with the air compressing means.   2. The pressure fluctuation according to claim 1, further comprising box means for accommodating the air compressing means therein, wherein the heat conducting means is a structure that passes through the purge gas communication line inside the box means. Adsorption type oxygen concentrator.   5. The pressure fluctuation adsorption type according to claim 3, further comprising a cooling unit that cools the air compression unit, and further includes a control unit that starts the cooling unit after a predetermined time has elapsed after the oxygen concentrator is started. Oxygen concentrator.   Temperature detecting means for detecting the temperature of the air compressing means; cooling means for cooling the air compressing means; and control means for starting the cooling means at a predetermined temperature or higher based on a detection result of the temperature detecting means. The pressure fluctuation adsorption type oxygen concentrator according to claim 3 or 4, characterized by the above.   The pressure fluctuation adsorption type oxygen concentrator according to claim 2, further comprising a control unit that activates the blowing unit after a predetermined time has elapsed after the oxygen concentrator is activated.   The temperature detecting means for detecting the temperature of the air compressing means is further provided, and control means for starting the air blowing means at a predetermined temperature or higher based on the detection result of the temperature detecting means is provided. Pressure fluctuation adsorption type oxygen concentrator.

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