JPH078737A - Oxygen enriched air producing apparatus - Google Patents

Abstract

PURPOSE:To efficiently perform enrichment of oxygen (adsorption of nitrogen) and the adsorption of carbon dioxide by one adsorption tower. CONSTITUTION:A low pressure circuit 13 having a solenoid valve EV3 and a high pressure circuit 15 having a solenoid valve EV4 and an orifice 14 are formed in parallel on the outlet side of an adsorption tower 12. At the time of an oxygen enriching mode, air is allowed to pass through the high pressure circuit 15 to increase passage resistance and the pressure in the adsorption tower 12 is raised to the pressure suitable for the adsorption of nitrogen. At the time of a carbon dioxide removing mode, passage resistance is lowered by passing air through the low pressure circuit 13 to lower the pressure in the adsorption tower 12 to the pressure suitable for the adsorption of carbon dioxide. Further, the cycle ratio R[=adsorption time/(adsorption time + regeneration time)] of the carbon dioxide removing mode is set to 0.5<R<=about 0.75 and the removal of carbon dioxide and the enrichment of oxygen are efficiently performed only by one adsorption tower 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen-enriched air generator for sending air into an adsorption tower containing an adsorbent for adsorbing nitrogen and carbon dioxide in the air to produce oxygen-enriched air. is there.

[0002]

2. Description of the Related Art In recent years, an oxygen-enriched air generator for removing oxygen in the air to produce oxygen-enriched air in order to prevent a decrease in the oxygen concentration in the room and maintain the comfort of a living space. (PSA) has been developed. This is disclosed in JP-A-2-
As described in Japanese Patent No. 174913, an adsorption tower containing an adsorbent such as zeolite that adsorbs nitrogen in the air is provided, and air is sent by a compressor into the adsorption tower to generate oxygen-enriched air, This oxygen-enriched air is sent to the room through a pipeline.

[0003]

By the way, as an air environment that affects comfort, there is a carbon dioxide concentration in addition to an oxygen concentration. In order to confirm this, when the relationship between the air environment (oxygen concentration, carbon dioxide concentration) and the human fatigue reduction rate was examined, the results shown in FIG. 9 were obtained. In FIG. 9, region I is a region where the fatigue reduction rate is high and the user feels comfortable due to the high oxygen concentration and low carbon dioxide concentration.
Is a region in which the oxygen concentration is slightly low, but the fatigue reduction rate (comfort) that is almost the same as in region I can be secured by reducing the carbon dioxide concentration. It is an area of low comfort.

As is clear from this relationship, even if the oxygen concentration is high, if the carbon dioxide concentration is high, the fatigue reduction rate (comfort) will be significantly reduced. Therefore, in order to maintain comfort, it is also necessary to lower the carbon dioxide concentration in addition to oxygen enrichment.

However, the above-mentioned conventional ones aim to improve the air environment only by enriching oxygen,
Since it is not configured to control the carbon dioxide concentration, sufficient comfort cannot be ensured. Incidentally, an adsorbent such as zeolite has an ability to adsorb carbon dioxide as well as nitrogen, but as described later, carbon dioxide has a stronger selective adsorption property than nitrogen, and carbon dioxide in the air is converted to nitrogen. Since the concentration is extremely low in comparison, when normal air is used as the raw material air, both nitrogen adsorption and carbon dioxide adsorption cannot be achieved at the same time, and carbon dioxide adsorption cannot be performed efficiently.

Recently, in order to solve this problem, a multi-tower PSA has been developed in which a plurality of adsorption towers are provided so that carbon dioxide can be selectively adsorbed, but the whole system becomes complicated, It has the drawback of increasing the size and cost of the system.

The present invention has been made in consideration of such circumstances, and an object thereof is to efficiently perform oxygen enrichment (adsorption of nitrogen) and adsorption of carbon dioxide by one adsorption tower. Accordingly, it is an object of the present invention to provide an oxygen-enriched air generator capable of properly controlling both the oxygen concentration and the carbon dioxide concentration in the air and realizing an extremely comfortable air environment.

[0008]

In order to achieve the above object, the oxygen-enriched air generator of the present invention is provided with an adsorption tower containing an adsorbent for adsorbing nitrogen and carbon dioxide in the air, and the adsorption tower is provided. In a device for generating oxygen-enriched air by sending air into the tower by an air supply means, an oxygen-enriched mode is selected by switching so as to reduce the flow path resistance of the air circulation path inside the adsorption tower or on the outlet side thereof. From the carbon dioxide removal mode to the carbon dioxide removal mode, and in any of the oxygen enrichment mode and the carbon dioxide removal mode, while adhering to the adsorbent in the adsorption tower during the operation of the mode. And a control means for intermittently executing a regeneration mode operation for removing nitrogen and carbon dioxide, wherein the control means has a cycle ratio R during operation of the carbon dioxide removal mode. 0.5 <R ≦ 0.75 [where, R = adsorption time / (adsorption time + playback time) and controls so as to.

[0009]

[Function] When the pressure in the adsorption tower (hereinafter referred to as "swing pressure") is reduced by lowering the flow path resistance of the air flow path inside the adsorption tower or on the outlet side thereof, the flow rate of the air flowing in the adsorption tower Will increase. However, due to the characteristics of the adsorbent (for example, zeolite), as shown in FIG. 10, the saturated adsorption amount of nitrogen and carbon dioxide decreases as the swing pressure decreases, so that the optimum swing pressure for nitrogen adsorption exists. A peak point appears in the oxygen enrichment amount. On the other hand, carbon dioxide has a stronger selective adsorption property to polar molecules of the adsorbent (for example, zeolite) than nitrogen, so that the adsorption amount of carbon dioxide per unit time increases as the air flow rate increases. There is.

Therefore, in the present invention, in the oxygen enrichment (removal of nitrogen) mode, the mode switching means switches the flow path resistance of the air flow path inside the adsorption tower or at the outlet side thereof to the high pressure side to change the swing pressure to nitrogen. Set a pressure suitable for adsorption of. As a result, nitrogen in the air is efficiently adsorbed and the oxygen concentration in the air is increased.

On the other hand, in the carbon dioxide removal mode, the mode switching means switches the flow path resistance of the air flow path inside or at the outlet side of the adsorption tower to the low pressure side to set the swing pressure to a low pressure suitable for adsorption of carbon dioxide. Set to. As a result, carbon dioxide in the air is efficiently adsorbed, and the carbon dioxide concentration in the air is reduced.

In any of the above-described oxygen enrichment mode and carbon dioxide removal mode, the operation of the regeneration mode is intermittently executed during the operation of the mode, and the adsorption in the adsorption tower is performed during the operation of the regeneration mode. The nitrogen and carbon dioxide molecules adsorbed on the agent are removed to restore the adsorption ability.

By the way, as shown in FIG. 4, in order to increase the carbon dioxide removal amount, the cycle ratio R may be increased to lengthen the adsorption time (carbon dioxide removal mode operation time). The longer the time, the shorter the reproduction time (the operation time in the reproduction mode) and the smaller the reproduction amount. If the regeneration amount is small, the nitrogen regeneration rate (= regeneration amount / adsorption amount × 100) is reduced and the oxygen enrichment capability is reduced.

In consideration of this relationship, in the present invention, the cycle ratio R in the carbon dioxide removal mode is set to 0.5 <R ≦ about 0.
It is set to 75, and both the carbon dioxide removal capability and the oxygen enrichment (nitrogen removal) capability are made compatible by one adsorption tower, and both carbon dioxide removal and oxygen enrichment are efficiently performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, in both the oxygen enrichment mode and the carbon dioxide removal mode, the room air is sucked into the vacuum pump 11 serving as an air feeding means through the electromagnetic valve EV1. The air discharged from the vacuum pump 11 flows into the adsorption tower 12 through the electromagnetic valve EV2. This adsorption tower 1
An adsorbent (not shown) such as zeolite that adsorbs nitrogen and carbon dioxide in the air is housed in the inside of the chamber 2.

In the air flow path on the outlet side of the adsorption tower 12, a low pressure circuit 13 having a solenoid valve EV3 and a solenoid valve EV are provided.
4 and an orifice 14 are connected in parallel to each other, and the low voltage circuit 13 and the high voltage circuit 15 constitute a mode switching means 16. In this case, in the oxygen enrichment mode, by closing the solenoid valve EV3 of the low pressure circuit 13 and opening the solenoid valve EV4 of the high pressure circuit 15,
By increasing the flow path resistance of the air flow path on the outlet side of the adsorption tower 12, the pressure inside the adsorption tower 12 (swing pressure) is switched to a high pressure suitable for nitrogen adsorption (for example, 0.5 kgf / cm 2 G), The oxygen-enriched air flowing out from the adsorption tower 12 is supplied into the room through the route of the high pressure circuit 15 (electromagnetic valve EV4 → orifice 14) → check valve 24, as shown by the solid arrow in FIG.

On the other hand, in the carbon dioxide removal mode, the solenoid valve EV4 of the high pressure circuit 15 is closed to close the low pressure circuit 1.
By opening the solenoid valve EV3 of No. 3, the flow path resistance of the air circulation path on the outlet side of the adsorption tower 12 is reduced, the swing pressure is switched to a low pressure suitable for adsorption of carbon dioxide, and the outflow from the adsorption tower 12 is performed. The oxygen-enriched air to be supplied is supplied into the room through the route of the low pressure circuit 13 → the check valve 24 as shown by the one-dot chain line arrow in FIG.

On the other hand, in the regeneration mode, the air remaining in the adsorption tower 12 is shown by a dotted arrow in FIG. 1 with both the solenoid valve EV3 of the low pressure circuit 13 and the solenoid valve EV4 of the high pressure circuit 15 closed. In this way, the adsorption tower 12 is discharged to the outside through the path of the solenoid valve EV5 → the vacuum pump 11 → the solenoid valve EV6.
By vacuuming the inside, nitrogen and carbon dioxide molecules adsorbed by the adsorbent in the adsorption tower 12 are removed to restore the adsorption capacity. ON (open) / OFF (close) of the solenoid valves EV1 to EV6 in each mode described above
2 is switched as shown in FIG.

Next, the structure of the control circuit 17, which is the control means, will be described with reference to FIG. The mode switch 18 is
It switches between the oxygen enrichment mode and the carbon dioxide removal mode, and the first relay coil RL1 is connected to the mode changeover switch 18 in series. When the mode selector switch 18 is off, the oxygen enrichment mode is set, and the solenoid valve E is set via the normally closed relay switch RL1b.
V4 is energized and this solenoid valve EV4 is turned on (open). Thereafter, when the mode switch 18 is turned on, the first relay coil RL1 is energized, the normally closed relay switch RL1b is turned off, and the solenoid valve EV4 is turned off (closed). Relay switch RL1
a is turned on, the solenoid valve EV3 is turned on, and the mode is switched to the carbon dioxide removal mode.

On the other hand, the main switch 19 is connected to the second relay coil RL2. When the main switch 19 is turned on, the second relay coil RL2 is energized and the relay switch RL2a is turned on. As a result, the operation of the vacuum pump 11 is started and the first relay timer RLT1 and the solenoid valves EV1 and EV2 are energized via the normally closed relay switch RL3a. The first relay timer RLT1 starts timing operation at the same time as energization, and after a predetermined time elapses, the relay switch RLT1.
Switch a on. This relay switch RLT1a
Is turned on, the third relay coil RL3 is energized via the normally closed relay switch RLT2a, the normally closed relay switch RL3a is turned off, and the solenoid valves EV1 and E1 are connected.
When V2 is turned off and the relay switch RL3b is turned on, the solenoid valves EV5 and EV6 are energized via the relay switch RL3b and the normally closed relay switch RLT2a to start the operation in the regeneration mode.

During operation in this regeneration mode, the second relay timer RLT2 is energized via the relay switch RL3b. The second relay timer RLT2 counts the operation time (reproduction time) in the regeneration mode, and turns off the normally closed relay switch RLT2a after a predetermined time has elapsed. As a result, the third relay coil RL3 and the solenoid valves EV5, EV6 are turned off, and the normally closed relay switch RL3a is returned to the on state, so that the solenoid valves EV1, EV
V2 is turned on, and the operation is performed in either the carbon dioxide removal mode or the oxygen enrichment mode set by the mode changeover switch 18.

With the circuit configuration as described above, in any of the oxygen enrichment mode and the carbon dioxide removal mode,
During the operation of the mode, the operation of the regeneration mode is intermittently performed to remove nitrogen and carbon dioxide adhering to the adsorbent in the adsorption tower 12 to recover the adsorption capacity.

By the way, as shown in FIG. 4, in order to increase the amount of carbon dioxide removed, the cycle ratio R defined by the following equation is increased to increase the adsorption time (the operating time of the carbon dioxide removal mode). Good. Cycle ratio R = adsorption time / (adsorption time + regeneration time) Here, when the cycle ratio R is increased, not only the adsorption time becomes longer but also the inflow amount per unit time increases as shown in FIG. There is a relationship that the amount of carbon dioxide removed increases.

However, as the adsorption time becomes longer, the regeneration time (the operation time of the regeneration mode) becomes shorter,
Regeneration amount decreases, nitrogen regeneration rate (= regeneration amount / adsorption amount x
100) will decrease. According to the experimental results of the present inventor, as shown in FIG. 4, when the cycle ratio R becomes 0.6 or more, the decrease width of the nitrogen regeneration rate gradually increases, and the cycle ratio R is about 0.75. The reproduction rate reaches the lower limit of the practical range. Below this lower limit, the oxygen enrichment capacity will fall below the practical minimum level, and it will not be possible to achieve both a carbon dioxide removal capacity and an oxygen enrichment capacity.

In consideration of this relationship, in the present embodiment, the cycle ratio R in the carbon dioxide removal mode is 0.5 <R ≦ about 0.
It is set to 75. This makes it possible to achieve both carbon dioxide removal capability and oxygen enrichment capability by one adsorption tower 12 and efficiently perform both carbon dioxide removal and oxygen enrichment. Further, in the present embodiment, the cycle ratio S in the oxygen enrichment mode is also set to be larger than 0.5, for example, S = 0.5.
By setting it to 7, the oxygen enrichment capacity is further enhanced.

According to the experimental results of the present inventor, when the carbon dioxide removal mode is operated at a cycle ratio R of 0.75, as shown in FIG. 40% improvement and
The oxygen enrichment capacity can be improved by about 3%. As a result, the indoor air environment can be maintained within the range of the region I or the region II having a high fatigue reduction rate (comfort) shown in FIG. 9, and the comfort of the indoor living space can be kept good. it can.

The oxygen-enriched air generator 20 of the present embodiment described above may be installed in a room 25 and used as shown in FIG. Alternatively, as shown in FIG. 8, the oxygen-enriched air generator 20 is installed outdoors together with the air conditioner outdoor unit 21, and the air pipe 2 derived from the oxygen-enriched air generator 20 is installed.
2 is connected to the air conditioner indoor unit 23, and the air conditioner indoor unit 23
Alternatively, oxygen-enriched air may be blown out together with the cool air, or the air in the room 25 may be sucked in through the air conditioner indoor unit 23.

In this embodiment, the oxygen enrichment mode and the carbon dioxide removal mode are switched by the manual operation of the mode changeover switch 18, but the oxygen concentration (or the carbon dioxide sensor) is changed by the oxygen sensor (or the carbon dioxide sensor). The carbon dioxide concentration) may be detected, and the switching between the oxygen enrichment mode and the carbon dioxide removal mode may be automatically switched based on the detection result.

Further, in the present embodiment, the vacuum pump 11 is used as the air supply means, and the inside of the adsorption tower 12 is evacuated in the regeneration mode, so that the nitrogen or carbon dioxide adsorbed by the adsorbent in the adsorption tower 12 is absorbed. The molecule was removed to recover the adsorption capacity, but a surge tank for storing a part of the oxygen-enriched air was provided in the latter stage of the adsorption tower 12, and the oxygen-enriched air was adsorbed from the surge tank during the regeneration mode. The nitrogen and carbon dioxide molecules adsorbed by the adsorbent in the adsorption tower 12 may be removed by flowing the adsorbent in the adsorption tower 12.

Further, in the present embodiment, the low pressure circuit 13 and the high pressure circuit 15 are provided in parallel in the air flow path on the outlet side of the adsorption tower 12, and the air flow path is changed from the high pressure circuit 15 in the carbon dioxide removal mode. By switching to the low-pressure circuit 13, the flow path resistance is reduced, the pressure in the adsorption tower 12 is reduced, and the inflow amount of air is increased. However, a bypass circuit is provided on the side wall of the adsorption tower 12, By allowing air to flow into the adsorption tower 12 through this bypass circuit in the removal mode, the air flow path in the adsorption tower 12 is shortened, the flow path resistance (pressure loss) in the adsorption tower 12 is reduced, and the inflow of air is reduced. The amount may be increased.

In addition, the present invention is not limited to the above-mentioned embodiments, and for example, the air feeding means may be the vacuum pump 11.
It goes without saying that various modifications can be made without departing from the scope, such as changing the (compressor) to a blower or changing the swing pressure appropriately according to the size and structure of the adsorption tower 12.

[0032]

As is apparent from the above description, according to the present invention, in the carbon dioxide removal mode, the flow path resistance of the air flow path inside the adsorption tower or at the outlet side thereof is set to the low pressure side by the mode switching means. By switching the pressure (swing pressure) in the adsorption tower to a low pressure suitable for adsorption of carbon dioxide, the cycle ratio R in the carbon dioxide removal mode is set.
Is set to 0.5 <R ≦ about 0.75, so that both oxygen enrichment (removal of nitrogen) and removal of carbon dioxide can be efficiently performed by one adsorption tower, and oxygen concentration in the air can be reduced. Both carbon dioxide concentration can be controlled appropriately, and an extremely comfortable air environment can be realized.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between each mode and ON / OFF of each solenoid valve.

FIG. 3 is an electric circuit diagram showing details of a control circuit.

FIG. 4 is a diagram showing a relationship between a cycle ratio, a nitrogen regeneration rate, and a carbon dioxide removal amount.

FIG. 5 is a diagram showing a relationship between a cycle ratio and an inflow amount of air.

FIG. 6 is a diagram for explaining the carbon dioxide removal capacity and oxygen enrichment capacity of this example in comparison with a conventional PSA.

FIG. 7 is a conceptual diagram when the oxygen-enriched air generator of this embodiment is used as an indoor installation type.

FIG. 8 is a conceptual diagram when the oxygen-enriched air generator of this embodiment is used as an outdoor installation type.

FIG. 9 is a diagram showing a relationship between an air environment and a fatigue reduction rate.

FIG. 10 is a graph showing the relationship between swing pressure, oxygen concentration (a), and carbon dioxide removal amount (b).

[Explanation of symbols]

11 ... Vacuum pump (air supply means), 12 ... Adsorption tower, 13 ...
Low voltage circuit, 14 ... Orifice, 15 ... High voltage circuit, 16 ...
Mode switching means, 17 ... Control circuit (control means), 18 ...
Mode switch, 19 ... Main switch, EV1
EV6 ... Solenoid valve.

Claims (1)

[Claims] 1. An oxygen-enriched air production system, wherein an adsorption tower containing an adsorbent for adsorbing nitrogen and carbon dioxide in air is provided, and air is sent into the adsorption tower by an air supply means to produce oxygen-enriched air. In the apparatus, mode switching means for switching the operation from the oxygen enrichment mode to the carbon dioxide removal mode by switching so as to reduce the flow path resistance of the air circulation path inside the adsorption tower or on the outlet side thereof, and the oxygen enrichment. In any of the mode and the carbon dioxide removal mode, a control means for intermittently executing a regeneration mode operation for removing nitrogen and carbon dioxide adhering to the adsorbent in the adsorption tower during the operation of the mode. The control means has a cycle ratio R of 0.5 <R ≦ about 0.75 [where R = adsorption time / (in adsorption) during the operation in the carbon dioxide removal mode. + Duration) be controlled to be oxygen-enriched air producing apparatus according to claim.