JP4816590B2 - Method for shutting down oxygen concentrator and oxygen concentrator - Google Patents

Description

  The present invention relates to a method for shutting down an oxygen concentrator for producing oxygen by adsorbing nitrogen from air and an oxygen concentrator.

  The oxygen concentrator uses a plurality of adsorption cylinders filled with an adsorbent that selectively adsorbs nitrogen, and supplies compressed air to one of the adsorption cylinders to produce oxygen, while the other adsorbs nitrogen. It is an apparatus for producing oxygen by desorbing a cylinder and repeating this alternately.

  The oxygen concentrator 41 in FIG. 4 is a PSA oxygen concentrator using a PSA (Pressure Swing Adsorption) method, and has two adsorption cylinders 43 each filled with an adsorbent 42 such as zeolite that selectively adsorbs nitrogen. It is equipped. Nitrogen adsorbents 42 such as zeolite are hydrophilic, and it is known that nitrogen adsorption performance decreases when moisture in the atmosphere is adsorbed by long-term use.

  In the oxygen concentrator 41, a high-pressure air is supplied to one adsorption cylinder 43 by the compressor 44, and an adsorption process in which nitrogen in the air is adsorbed and separated by the adsorbent 42 and the pressure of the other adsorption cylinder 43 is lowered. As a result, the regeneration process (desorption process) in which the adsorbed nitrogen is released and the adsorbent 42 is regenerated is repeated to continuously produce high-concentration oxygen.

  The produced high-concentration oxygen is stored in a buffer tank 45 installed on the downstream side of the adsorption cylinder 43 in order to reduce fluctuations in pressure, flow rate, and concentration.

  Part of the high-concentration oxygen produced in the adsorption process or stored in the buffer tank 45 is introduced into the adsorption cylinder 43 opened to the exhaust side in the regeneration process and purged with the nitrogen adsorbed on the adsorbent 42 Promote.

  Since the compressed air supplied to the adsorption cylinder 43 contains moisture in the atmosphere, a mechanism for removing the condensed moisture by installing a drain pot (not shown) at the outlet of the compressor 45 is employed. (Drain pot may not be installed). Further, the moisture sent to the adsorption cylinder 43 as vapor without being condensed in the drain pot is removed by the moisture absorbent 46 installed upstream of each adsorption cylinder 43.

  The moisture adsorbed by the hygroscopic agent 46 installed upstream of the adsorbent 42 is desorbed by opening it to the atmosphere during the regeneration process, and is purged by introducing a part of dry oxygen that is a product gas.

  The amount of purge gas during normal operation of the oxygen concentrator 41 is determined in consideration of the purge of nitrogen gas adsorbed by the adsorbent 42, so that the moisture adsorbed by the moisture absorbent 46 cannot be completely desorbed.

  Therefore, when the operation is stopped, the dry oxygen stored in the buffer tank 45 is used to flow a purge gas at a flow rate of 1.5 to 4 times the purge gas amount during the normal operation to further promote moisture desorption (for example, patents). Reference 1).

  After the sufficient moisture purge is completed, the entrance of moisture from the outside is prevented by closing the valves on the compressor side line, the exhaust side line, and the buffer tank side line connected to the adsorption cylinder 43.

JP 2003-180837 A

However, it is generally impossible to completely prevent valve leakage. For example, in a process valve for air, depending on the pressure exerted, the maximum ^1cm 3 / min (ANR the maximum 0.2cm ³ / min (ANR), the valve orifice diameter dozen mm orifice diameter in the valve of a few mm ) There is a valve that causes a certain degree of valve seat leakage. Accordingly, during the long-term operation stoppage, infiltration of a slight amount of air (moisture) from the atmosphere side is unavoidable due to changes in the external air pressure.

  Further, it has been found that the longer the operation stop period, the more strongly the zeolite adsorbs moisture, making it difficult to desorb and regenerate. Therefore, when the operation stop period is long, the nitrogen adsorption capacity is reduced even if the amount of moisture entering from the outside air is small.

  Therefore, the object of the present invention is to solve the above-mentioned problems, and even if there is a change in the external air pressure or the like, moisture does not enter the adsorption cylinder due to valve seat leakage, and the adsorption cylinder can be reliably prevented from deteriorating. An object of the present invention is to provide an oxygen concentrator shutdown method and an oxygen concentrator.

The present invention has been devised to achieve the above object, and the invention of claim 1 is directed to any one of a plurality of adsorption cylinders filled with an adsorbent that selectively adsorbs compressed air from a compressor. To produce oxygen and store it in a buffer tank, while communicating an adsorption cylinder that adsorbs nitrogen to the atmosphere side through a silencer and supplying oxygen from the buffer tank and adsorbing nitrogen In the method for shutting down the oxygen concentrator in which oxygen is desorbed and regenerated and this is repeated alternately to continuously produce oxygen, the compressor is shut down and the shutoff valve connected to the discharge side of the buffer tank is closed. After the oxygen production was stopped, oxygen from the buffer tank was supplied into each adsorption cylinder, and water remaining in each adsorption cylinder was discharged into the atmosphere through the silencer. , Each adsorption column closes the air side of the switching valve of the adsorption column was maintained at above atmospheric pressure, and a shutdown method of the oxygen concentrator for heating and maintaining the adsorption column to a predetermined temperature.

The invention according to claim 2 is a compressor for compressing air, a plurality of adsorption cylinders filled with an adsorbent for selectively adsorbing nitrogen, a buffer tank for storing oxygen concentrated in the adsorption cylinder, and the adsorption cylinder The silencer installed on the atmosphere side of the air and the compressed air from the compressor are alternately supplied to and adsorbed to one of the adsorption cylinders, and the other adsorption cylinder that adsorbs nitrogen is desorbed to remove the desorbed gas via the silencer. in the oxygen concentrator and a switching valve for exhausting Te, connect the closure valve on the discharge side of the buffer tank, the silencer side is constituted by connecting the switching valve so as to be normally closed to the adsorption column together, the heater provided in the adsorption column, and after oxygen production stop, the stop valve is closed to stop the compressor, the adsorbing oxygen in the buffer tank After discharged to the outside of water in each adsorption cylinder to flow into the silencer side through the above switching valve, the switching valve so as to hold each adsorption column above atmospheric pressure are closed and, above the heater It is an oxygen concentrator provided with a control means for heating and holding the adsorption cylinder at a predetermined temperature .

According to a third aspect of the present invention, there is provided the oxygen concentration according to the second aspect, wherein at least one spare buffer tank is provided in parallel with the buffer tank for storing oxygen for purging moisture in each adsorption cylinder after the oxygen production is stopped. It is a vessel.

A fourth aspect of the present invention, the buffer tank is purged each adsorption column after oxygen production stopped and the pressure in the adsorption column after the purge completion to claim 2 which has sufficient capacity to not less than atmospheric pressure The oxygen concentrator as described.

According to a fifth aspect of the present invention, when the operation stop period of the oxygen concentrator is short, the control means holds each adsorption cylinder above atmospheric pressure during the operation stop, and the operation stop period of the oxygen concentrator is long. When the operation is stopped, the oxygen concentrator according to any one of claims 2 to 4 is controlled so as to hold each adsorption cylinder at a higher pressure.

The invention according to claim 6 is the oxygen concentration according to any one of claims 2 to 5, wherein the adsorbent is disposed on the downstream side in the adsorption cylinder and the hygroscopic agent is disposed on the upstream side in the adsorption cylinder. It is a vessel.

  According to the present invention, even if there is a change in the external air pressure or the like, moisture does not enter the adsorption cylinder due to valve seat leakage of the valve, and deterioration of the adsorption cylinder can be prevented.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, the oxygen concentrator used for the operation stop method of the oxygen concentrator will be described.

  The oxygen concentrator used in the first embodiment is a PSA oxygen concentrator that concentrates oxygen by the PSA method, and is applied to, for example, an ozone generator.

  FIG. 1 is a schematic diagram of an oxygen concentrator showing a preferred first embodiment of the present invention.

  As shown in FIG. 1, the oxygen concentrator 1 according to the first embodiment includes a compressor 2 that compresses air and two adsorption cylinders 4 and 5 that are filled with an adsorbent 3 that selectively adsorbs nitrogen. A buffer tank (first buffer tank) 6 for storing high-concentration oxygen concentrated in the adsorption cylinders 4 and 5, a reserve buffer tank (second buffer tank) 7 arranged in parallel with the buffer tank 6, and an adsorption cylinder Silencer 8 installed on the open side (exhaust side) of 4 and 5 and the other adsorbing cylinder that adsorbs nitrogen by alternately supplying the compressed air from the compressor 2 to any adsorbing cylinder and adsorbing it. And a controller 10 as control means for performing opening / closing control of the switching valve 9 and the like.

  The compressor 2 is a positive displacement compressor including, for example, an electric diaphragm compressor. The compressor 2 and the switching valve 9 are connected, and the switching valve 9 and the adsorption cylinders 4 and 5 are connected by an air supply line 11 such as a pipe serving as a flow path.

  The air supply line 11 is provided with a compressor shutoff valve 12 as an upstream shutoff valve that shuts off outside air. A pressure gauge 13 is connected to the air supply line 11 on the downstream side of the compressor stop valve 12 via a branch pipe 21 branched from the air supply line 11.

  The switching valve 9 switches between a flow path for supplying compressed air from the compressor 2 to the adsorption cylinder 4 (or 5) and a flow path for exhausting desorption gas from the adsorption cylinder 5 (or 4).

  The switching valve 9 includes two three-way valves 9a and 9b. The three-way valve 9a is installed so that the compressor 2 side is normally open (NO), the exhaust side is normally closed (NC), and the adsorption cylinder 4 side is common (C). The same applies to the three-way valve 9b.

  The NO of the three-way valve 9 a is connected to the air supply line 11 branched on the downstream side of the compressor stop valve 12, and the NO of the three-way valve 9 b is connected to the downstream end of the air supply line 11.

  A common exhaust line 14 is connected to the NCs of the three-way valves 9a and 9b, and a silencer 8 that silences the exhaust sound is connected to an exhaust port of the exhaust line 14.

  The hygroscopic agent 15 is disposed upstream of the adsorption cylinders 4 and 5, and the adsorbent 3 is disposed downstream. The adsorbent 3 is made of zeolite, and the hygroscopic agent 15 is made of activated alumina.

  In addition, a heater 16 for heating and holding the adsorption cylinders 4 and 5 while the operation of the oxygen concentrator 1 is stopped is installed on the outer periphery of the adsorption cylinders 4 and 5.

  The adsorption cylinders 4 and 5 are connected to an ozone generator (not shown) or the like via a common oxygen supply line 22.

  A buffer tank 6 is provided in the middle of the oxygen supply line 22. A branch pipe 23 bypassing the buffer tank 6 is connected to the oxygen supply lines 22 at both ends of the buffer tank 6, and the spare buffer tank 7 is provided in the branch pipe 23.

  An upstream tank closing valve 17 a is provided in the upstream branch pipe 23 of the spare buffer tank 7, and a downstream tank closing valve 17 b is provided in the downstream branch pipe 23.

  In the oxygen supply line 22 on the downstream side of the adsorption cylinders 4 and 5, orifices 18 a and 18 b are provided as pressure adjusting means for adjusting the pressure in the adsorption cylinders 4 and 5.

  A regulator 19 for adjusting the flow rate of high-concentration oxygen supplied to an ozone generator or the like is connected to the oxygen supply line 22 on the downstream side of the buffer tank 6, and a downstream side closing for shutting off outside air is connected to the downstream side thereof. An ozonizer closing valve 20 is provided as a valve.

  The controller 10 is connected to each valve of the compressor shutoff valve 12, the three-way valves 9a and 9b, the upstream tank shutoff valve 17a, the downstream tank shutoff valve 17b, and the ozonizer shutoff valve 20, and the pressure gauge 13, and each valve Open / close control is performed.

  Furthermore, the controller 10 includes a storage mode setting unit 10a. When the operation stop period of the oxygen concentrator 1 is short, the storage mode setting device 10a is used when the pressure in each adsorption cylinder 4, 5 during operation stop is over atmospheric pressure and the operation stop period of the oxygen concentrator 1 is long. Controls to keep the pressure in each of the adsorption cylinders 4 and 5 being stopped higher.

  Next, a method for stopping the operation of the oxygen concentrator 1 will be described together with the operation of the oxygen concentrator 1.

  First, the operation of the oxygen concentrator 1 during normal operation will be described.

(During normal operation)
Prior to normal operation of the oxygen concentrator 1, the compressor closing valve 12, the ozonizer closing valve 20, the upstream tank closing valve 17a, and the downstream tank closing valve 17b are opened.

  In the oxygen concentrator 1, the compressed air from the compressor 2 is supplied to one adsorption cylinder to produce high-concentration oxygen (adsorption process), and the other adsorption cylinder that has adsorbed nitrogen is desorbed to silence the desorbed gas. Exhaust to the 8 side (regeneration process) and repeat this alternately to produce high concentration oxygen.

  More specifically, in the adsorption step, compressed air from the compressor 2 is introduced into one of the adsorption cylinders 4, where nitrogen in the compressed air is adsorbed by the adsorbent 3 to generate high-concentration oxygen. At this time, the compressed air is supplied to the adsorption cylinder 4 after condensed water is collected by a drain pot (not shown), further dehumidified by the moisture absorbent 15 of the adsorption cylinder 4, and adsorbed by the adsorption cylinder 4 in an almost completely dry state. The agent 3 is supplied. This prevents the adsorbent 3 from adsorbing moisture and deteriorating.

  At the same time, in the regeneration process, the adsorbing cylinder 5 and the silencer 8 are communicated by the three-way valve 9b, so that the product gas (high-concentration oxygen) is adsorbed from the adsorbing cylinder 4, the buffer tank 6 and the spare buffer tank 7 in the adsorption process. ) Is introduced into the adsorption cylinder 5 as a purge gas.

  Thereby, the nitrogen adsorbed by the adsorbent 3 of the adsorption cylinder 5 is desorbed, and the desorbed nitrogen is discharged to the silencer 8 side together with the purge gas, and the adsorbent 3 of the adsorption cylinder 5 is regenerated. Further, the supplied purge gas (high concentration oxygen) is almost completely dry, and the moisture adsorbed by the moisture absorbent 15 is also desorbed.

  The above adsorption process and regeneration process are alternately repeated to continuously produce high concentration oxygen.

  During this normal operation or when the operation is stopped, water in the adsorption cylinders 4 and 5 is purged, and a sufficient amount of high-concentration oxygen is stored in the reserve buffer tank 7 to keep the adsorption cylinders 4 and 5 at atmospheric pressure or higher. Keep it. After a sufficient amount of high-concentration oxygen is stored in the reserve buffer tank 7, the controller 10 closes the upstream reserve tank closing valve 17a and the downstream reserve tank closing valve 17b.

  When switching between the adsorption process and the regeneration process, a pressure equalization process for averaging the pressures in the adsorption cylinders 4 and 5 may be performed.

(During shutdown and during shutdown)
When the operation is stopped, first, the operation of the compressor 2 is stopped. At the same time, the controller 10 closes the ozonizer stop valve 20 and stops oxygen production.

  Thereafter, the controller 10 opens the upstream side auxiliary tank closing valve 17a and the downstream side auxiliary tank closing valve 17b, and switches the three-way valves 9a, 9b to connect the respective suction cylinders 4, 5 and the silencer 8.

  As a result, the high concentration oxygen stored in the buffer tank 6 and the reserve buffer tank 7 is exhausted to the outside as a purge gas through the oxygen supply line 22, the adsorption cylinders 4 and 5, the three-way valves 9 a and 9 b, the exhaust line 14, and the silencer 8. Then, nitrogen and moisture remaining in the adsorption cylinders 4 and 5 are purged (dotted arrows A and B in FIG. 1).

  At this time, the purge amount may be adjusted by setting a time (purge time) from the start of the purge to the completion of the purge in a timer provided in the controller 10.

  In the first embodiment, by appropriately setting the purge time for completing the purge, the adsorption cylinders 4 and 5 are held at atmospheric pressure or higher after the purge is completed.

  After the purge is completed, the controller 10 closes the air release side (exhaust side) of the three-way valves 9a and 9b and closes the compressor stop valve 12.

  Thereby, each adsorption cylinder 4 and 5 will be hold | maintained more than atmospheric pressure, and will be in the state interrupted | blocked completely from the external air, and the oxygen concentrator 1 will be stopped.

  Further, by changing the purge time for completing the purge, the pressure for holding the adsorption cylinders 4 and 5 can be changed after the purge is completed. Therefore, the pressure for holding the suction cylinders 4 and 5 may be changed according to the valve seat leakage characteristics of the employed valves (the ozonizer closing valve 20, the compressor closing valve 12, and the three-way valves 9a and 9b).

  The method for stopping the operation of the oxygen concentrator according to the first embodiment (the method for preventing external water inflow when the operation is stopped) stops the operation of the compressor 2, closes the ozonizer stop valve 20, stops oxygen production, After supplying high concentration oxygen from the tank 6 and the reserve buffer tank 7 into the adsorption cylinders 4 and 5 and discharging the water remaining in the adsorption cylinders 4 and 5 to the atmosphere, the atmosphere of the three-way valves 9a and 9b is obtained. The open side (exhaust side) is closed and the inside of each adsorption cylinder 4 and 5 is kept at atmospheric pressure or higher.

  As a result, the adsorption cylinders 4 and 5 that are not in operation are held at atmospheric pressure or higher, and even if there is a change in the external air pressure, outside air (moisture) enters the adsorption cylinders 4 and 5 due to valve seat leakage. And the deterioration of the adsorbent 3 of the adsorption cylinders 4 and 5 can be reliably prevented.

  In the first embodiment, the purge amount is set by the timer provided in the controller 10, but the present invention is not limited to this, and a pressure gauge (in the first embodiment, in the closed space that is shut off from the outside air during operation stop). A pressure gauge 13) may be added, and the purge amount may be set based on the pressure value.

  At this time, the value indicated by the pressure gauge 13 during the purge may be different from the pressure reached by the closed space after the purge is completed, and the purge is performed with the in-exhaust pressure that becomes a necessary pressure during the operation stop measured in advance. It may be completed.

  Further, the adsorption cylinders 4 and 5 that are not in operation may be heated and held at about 100 to 200 ° C. by the heater 16 or may be heated by another heat source.

  The adsorbent 3 and the hygroscopic agent 15 have a property that the adsorbing ability decreases (becomes easy to desorb) when the temperature is increased. Therefore, by heating the adsorption cylinders 4 and 5 while the operation of the oxygen concentrator 1 is stopped by the heater 16, nitrogen and moisture remaining in the adsorption cylinders 4 and 5 are adsorbed by the adsorbent 3 and the moisture absorbent 15. And the deterioration of the adsorbent 3 can be prevented.

  Furthermore, the adsorption cylinders 4 and 5 are heated by the heater 16 when the adsorbent 3 and the hygroscopic agent 15 are reduced in adsorption capability at a high temperature and the purge is performed after the oxygen production is stopped. The desorption of 15 moisture may be further promoted.

  According to the oxygen concentrator 1 which concerns on 1st Embodiment, the operation stop method of the oxygen concentrator which concerns on 1st Embodiment can be implemented easily.

  In the oxygen concentrator 1, when the operation stop period of the oxygen concentrator 1 is short by the storage mode setting device 10 a of the controller 10, the adsorption cylinders 4, 5 are held at atmospheric pressure or higher during the operation stop to concentrate the oxygen. When the operation stop period of the container 1 is long, the suction cylinders 4 and 5 are controlled to be held at a higher pressure during the operation stop.

  As a result, even if the operation stop period is long and the pressure in the adsorption cylinders 4 and 5 is reduced due to valve seat leakage, the adsorption cylinders 4 and 5 are always maintained at atmospheric pressure or higher during the operation stop. Regardless of the deterioration of the adsorbent 3 can be prevented.

  Furthermore, in order to set the pressure for holding the adsorption cylinders 4 and 5 according to the operation stop period of the oxygen concentrator 1, the moisture in the adsorption cylinders 4 and 5 is purged after the oxygen production is stopped, There is no need to wastefully produce high-concentration oxygen for pressurization.

  Here, the relationship between the operation stop period and the amount of residual moisture in the adsorption cylinders 4 and 5 will be described.

  FIG. 2 shows the number of operation days and adsorption cylinders 4, 5 for high-frequency operation indicated by ◆ (15 minutes 10 times / day) and low-frequency operation indicated by ◇ (15 minutes operation once / day). It is a graph which shows the weight increase by the moisture residue of.

  As shown in FIG. 2, in the operation days 1 to 62, the high frequency operation with a large number of operations increases the weight of the adsorption cylinders 4 and 5 more than the low frequency operation, but the operation days 62 to 80 On a day, the weight increase of the adsorption cylinders 4 and 5 is greater in the low frequency operation than in the high frequency operation.

  Since the horizontal axis is not the number of operations, it is not a graph showing the increasing tendency per operation, but the weight (equilibrium weight) of the adsorption cylinders 4 and 5 that finally reach is larger in the low frequency operation I understand that

  Compared to high-frequency operation, the reason why the equilibrium weight of low-frequency operation becomes larger is that the low-frequency operation has a longer operation stop period, and the moisture remaining in the adsorption cylinders 4 and 5 is strongly adsorbed by the adsorbent 3. This is thought to be because it is difficult to regenerate the next driving. Therefore, it is considered that the moisture that was not discharged remains in the adsorption cylinders 4 and 5 and the weight of the adsorption cylinders 4 and 5 is increased.

  Furthermore, it is also conceivable that moisture enters the adsorption cylinders 4 and 5 due to valve seat leakage while the operation of the oxygen concentrator 1 is stopped.

  Therefore, in the oxygen concentrator 1 according to the first embodiment, when the operation stop period of the oxygen concentrator 1 is short by the storage mode setting device 10a of the controller 10, the adsorption cylinders 4 and 5 are stopped during the operation stop. When the oxygen concentrator 1 is held at a pressure higher than the atmospheric pressure and the operation stop period is long, the adsorption cylinders 4 and 5 are controlled to be held at a higher pressure during the operation stop.

  In the first embodiment, the reserve buffer tank 7 is provided to purge the moisture in the adsorption cylinders 4 and 5 after stopping the oxygen production, and the high concentration oxygen for pressurizing the adsorption cylinders 4 and 5 is stored. Sufficient capacity to increase the capacity of the buffer tank 6, purge the moisture in the adsorption cylinders 4, 5 after oxygen production is stopped, and set the pressure in the adsorption cylinders 4, 5 to atmospheric pressure or higher after the purge is completed You may make it have.

  Further, the capacity of the buffer tank 6 may be supplemented by giving a capacity to the piping of the oxygen supply line 22 between the ozonizer closing valve 20 and each of the adsorption cylinders 4 and 5.

  Further, a plurality of spare buffer tanks 7 may be provided in parallel with the buffer tank 6. At that time, the holding pressure of the adsorption cylinders 4 and 5 required from a preset operation stop period is set, and high concentration oxygen is stored in the required number of reserve buffer tanks 7 during normal operation according to the holding pressure. The production amount of the product gas for storage (high concentration oxygen) may be optimized by purging to a necessary time or pressure after stopping the oxygen production.

  The switching valve 9 and the compressor shut-off valve 12 are configured to shut off the outside air while the operation of the oxygen concentrator 1 is stopped. However, the compressor shut-off valve 12 is not required by using four two-way valves for the switching valve 9. It can also be.

  If the compressor 2 is configured to be closed with outside air when the operation is stopped, the compressor closing valve 12 can be eliminated.

  In addition, each system (air supply line 11, exhaust line 14, oxygen supply line 22) communicating with outside air is provided with two or more valves, and a closed space is formed between the two valves, and only the narrow closed space is pressurized. It may be held. Thereby, infiltration of outside air (moisture) can be prevented with a small amount of product gas.

  Next, a second embodiment will be described.

  FIG. 3 is a schematic view of an oxygen concentrator 31 according to the second embodiment.

  As shown in FIG. 3, the oxygen concentrator 31 has basically the same configuration as the oxygen concentrator 1 of FIG. 1, and a moisture absorbing cylinder 32 upstream of the adsorption cylinder 4 and a moisture absorption cylinder 33 upstream of the adsorption cylinder 5. And the hygroscopic agent 15 is filled in the upstream side of each of the hygroscopic cylinders 32 and 33, and the absorbent 34 in the hygroscopic cylinder is filled as a hygroscopic agent for precise dehumidification on the downstream side. The adsorption cylinders 4 and 5 are not filled with the hygroscopic agent 15, but only the adsorbent 3 is filled.

  In the second embodiment, the moisture absorbing cylinders 32 and 33 are provided separately from the adsorption cylinders 4 and 5, so that the adsorbent 3 and the moisture absorbent 15 are not in direct contact with each other.

  Thereby, it is possible to prevent moisture remaining in the hygroscopic agent 15 from diffusing into the adsorbent 3, and more reliably prevent the adsorbent 3 from deteriorating during normal operation and during operation stop.

  In the second embodiment, the moisture absorbent cylinders 32 and 33 are filled with the moisture absorbent 15 and the moisture absorbent cylinder adsorbent 34, but only the moisture absorbent 15 may be filled.

It is the schematic of the oxygen concentrator which shows suitable 1st Embodiment of this invention. It is a figure which shows the relationship between an operation stop period and a residual water | moisture content when the operation frequency of an oxygen concentrator is changed. It is the schematic of the oxygen concentrator which shows 2nd Embodiment. It is the schematic of the conventional oxygen concentrator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oxygen concentrator 2 Compressor 3 Adsorbent 4, 5 Adsorption cylinder 6 Buffer tank 8 Silencer 9 Switching valve 20 Ozonizer closing valve

Claims (6)

Compressed air from the compressor is supplied to one of a plurality of adsorption cylinders filled with an adsorbent that selectively adsorbs nitrogen to produce oxygen, and this is stored in a buffer tank, while the other adsorbs nitrogen. The adsorption cylinder is connected to the atmosphere side through a silencer, and oxygen is supplied from the buffer tank to desorb and regenerate the adsorbed nitrogen, and this is alternately repeated to continuously produce oxygen. In the shutdown method,
After stopping the operation of the compressor and closing the stop valve connected to the discharge side of the buffer tank, after stopping the oxygen production,
Oxygen from the buffer tank is supplied into each adsorption cylinder, and water remaining in each adsorption cylinder is discharged into the atmosphere through the silencer.
A method of stopping the operation of an oxygen concentrator, characterized in that the adsorption valve is closed at the atmospheric side, each adsorption cylinder is held at atmospheric pressure or higher , and the adsorption cylinder is heated and held at a predetermined temperature . A compressor that compresses air, a plurality of adsorption cylinders filled with an adsorbent that selectively adsorbs nitrogen, a buffer tank that stores oxygen concentrated in the adsorption cylinder, and an atmosphere side of the adsorption cylinder Silencer and switching valve for alternately supplying compressed air from the compressor to one of the adsorption cylinders for adsorption, and desorbing other adsorption cylinders that have adsorbed nitrogen to exhaust the desorbed gas through the silencer In an oxygen concentrator with
A shutoff valve is connected to the discharge side of the buffer tank, the switching valve is connected to the adsorption cylinder so that the silencer side is normally closed , a heater is provided in the adsorption cylinder, and after oxygen production is stopped, After stopping the compressor and closing the shut-off valve, the oxygen in the buffer tank flows to the silencer side through each adsorption cylinder and the switching valve, and the moisture in each adsorption cylinder is discharged to the outside. An oxygen concentrator comprising control means for closing the switching valve so as to hold each adsorption cylinder at atmospheric pressure or higher and heating and holding the adsorption cylinder at a predetermined temperature with the heater. 3. The oxygen concentrator according to claim 2 , wherein at least one spare buffer tank is provided in parallel with the buffer tank to store oxygen for purging moisture in each adsorption cylinder after oxygen production is stopped. 3. The oxygen concentrator according to claim 2 , wherein the buffer tank has a capacity sufficient to purge each adsorption cylinder after the stop of oxygen production and to set the pressure in each adsorption cylinder to atmospheric pressure or higher after the purge is completed. When the operation stop period of the oxygen concentrator is short, the control means holds each adsorption cylinder at atmospheric pressure or higher during the operation stop, and when the operation stop period of the oxygen concentrator is long, The oxygen concentrator according to any one of claims 2 to 4, wherein each of the adsorption cylinders is controlled to be held at a higher pressure. The oxygen concentrator according to any one of claims 2 to 5, wherein the adsorbent is arranged on the downstream side in the adsorption cylinder and the hygroscopic agent is arranged on the upstream side in the adsorption cylinder.

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