Abstract:
The present invention relates to an apparatus and process for oxygen concentration that makes possible the production of highly purified concentrated oxygen by modifying the structure of the adsorption bed and with various valves coupled thereto, and which can increase purity of the oxygen produced and reduce mechanical energy and consumption of electricity of the air compressor.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of Korean Patent Application No. 10-2006-0046611, filed in the Korean Intellectual Property Office on May 24, 2006 and 10-2006-8516, filed in the Korean Intellectual Property Office on Jan. 26, 2006 the disclosure of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an apparatus and process of oxygen concentration system that makes possible the production of highly purified concentrated oxygen by modifying the structure of the adsorption bed. 
   2. Description of Related Art 
   In general, a conventional oxygen concentration apparatus uses an adsorbent, called Zeolite, which adsorbs gas molecules. Since the nitrogen which constitutes about 80% of the atmospheric air, is easily absorbed with Zeolite, when the air is compressed and infused into an adsorption bed containing the adsorbent, the nitrogen component is absorbed and the air from which the nitrogen component is reduced, is output through the upper outlet of the adsorption bed; this process supplies the output oxygen for the required place and use. 
   The oxygen concentration process in the apparatus, can be distinguished into two processes: an adsorption process in which the compressed air passes through the absorbent and the nitrogen is absorbed, and a process of cleansing the adsorbent used. 
   In the adsorption process, as the compressed air is passed through the absorbent only the nitrogen is absorbed and the remaining gas is passed to separate the oxygen from the compressed air. In continuous use, the efficiency of the absorbent, Zeolite, becomes markedly reduced and the original capacity of the absorbent must be regained by desorbing the absorbed nitrogen from the absorbent. 
   The oxygen produced by the absorption of nitrogen within the absorbent moves into a storage place when it reaches a predetermined pressure and it is maintained in storage in a considerably high pressure. A portion of the stored oxygen is then regurgitated into the absorbent and performs the nitrogen cleansing process so as to regain absorption capacity. 
   However, the conventional oxygen concentration apparatus generally contains complicated inner and outer structures to produce high purity concentrated oxygen and has drawbacks of increased production cost, decreased productivity and failure to function. 
   Also, to produce oxygen, the conventional oxygen concentration apparatus, contains an interior absorption column in which its upper and lower portions are interchanneled mutually. Because only evenness of either the upper portion or the lower portion can be operated at one time, the pressure preparation time, consumption of electricity, purity, pure oxygen enrichment, and its recovery rate can be problematic and unsatisfactory in the event. 
   In Addition, when the air compressor connected to the oxygen concentration apparatus operates, too much mechanical energy is consumed, causing a disadvantage in the management of the oxygen concentration apparatus, and furthermore increasing the noise of the nitrogen output. 
   SUMMARY OF THE INVENTION 
   One object of the present invention is to solve the above mentioned problem in which the structure is altered to have a single absorption bed to be capable of producing highly purified and concentrated oxygen and to provide an oxygen concentration apparatus capable of easily attaching and detaching a solenoid valve on the adsorption bed. During the oxygen concentration process, after the first and second evenness of the adsorption column is performed, serially, the first and second upper/lower evenness is performed, thus the other object of the invention is to provide an oxygen concentration method to produce concentrated oxygen with high purity and while reducing the consumption of electricity by the air compressor as possible as it can be used. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention, and its many advantages can be gained and better understood by referencing the following detailed description and accompanying drawings wherein: 
       FIG. 1  is a disassembled perspective view of an apparatus of the oxygen concentration system according to a preferred embodiment of the present invention. 
       FIG. 2  is a perspective view of an assembled apparatus of the oxygen concentration system according to the preferred embodiment of the present invention. 
       FIG. 3  is a process flow chart of an oxygen concentration method according to one preferred embodiment of the present invention. 
       FIG. 4   a  to  FIG. 4   h  are circuit diagrams showing the air pressure circuits of an operating state of each step of the oxygen concentration method according to the preferred embodiment of the present invention. 
       FIG. 5   a  to  FIG. 5   h  are views illustrating operating states of the oxygen concentration apparatus according to one preferred embodiment of the present invention. 
       FIG. 6  is a graph of the pressure distribution chart of the oxygen concentration system according to one preferred embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Hereinafter, the present invention will be described in detail with reference to the accompanying drawings in which like reference symbols indicate the same or similar components. 
   A first solenoid valve is mounted on the outside of a bed housing to supply and/or discharge compressed air, and an adsorption bed is provided with an oxygen reservoir to store the concentrated oxygen. 
   First and second adsorption columns are disposed in the adsorption bed to separate the nitrogen and oxygen in the compressed air which is supplied through the first solenoid valve. First and second cover assemblies are mounted on the upper and lower parts of the adsorption bed respectively, in which the first cover assembly includes first and second grooves formed at positions corresponding to the first and second adsorption columns on the inside surface of the first cover plate, and first and second check valves are installed to allow movement of the concentrated oxygen through the supplying hole communicating with the oxygen reservoir of the adsorption bed and are formed at the same position of the first and second grooves. 
   A fitting or mounting part is provided on the outside upper part of the first cover plate with an end communicating with the inside of the first and second grooves each other and another end is formed on inside of the first and second communicating hole extending to the outside of the first cover assembly. 
   A second solenoid valve is fixedly mounted on the mounting part and coupled in fluid communication with the first and second communicating holes operable to equalize the pressure of the first and second adsorption columns, and a chamber is installed on the outside of the first cover plate, in fluid communication with the supplying hole with gas supplied through the first and second check valves. 
   The first cover assembly includes, on the lower sides of the first and second check valves, a first and second orifice in fluid communication with the first and second adsorption columns to allow a portion of the concentrate oxygen to flow reversely, when the pressure of any one of the first and second adsorption columns gets higher and the pressure of the other one is lowered, in order to rinse or clean the adsorbed nitrogen in any one of the first and second adsorption columns. 
   The first and second check valves and the supply hole are disposed on the region of chamber, positioned on the same line, and the first and second orifices are disposed, on the lower side of the first and second check valves and supply hole, on the region of chamber while positioned on the same line. 
   The first and second check valves are mounted on a fixing hole formed on the first cover plate, and include a valve hole formed on both sides of the fixing hole in fluid communication, and a valve body of flexible material which is operable with flexibility by the pressure of moving gas via the valve hole. 
   A chamber cover includes the first chamber formed on the inside of the chamber cover body on the chamber of the first cover assembly, which is compartmented with the close sealed region from outside; and the second chamber formed on the lower side of the first chamber, which is compartmented with a close sealed region from the outside and allows the gas supplied through the first orifice and the second orifice to flow. 
   The chamber cover includes a sealing element disposed along the external edge of the first and second chambers formed on the body of chamber cover and positioned with an engaged state on the external peripherals of the chamber. 
   The second cover assembly includes the third and fourth grooves formed corresponding to the first and second adsorption columns on the inside surface of the second cover plate, and a connecting hole is penetratingly formed between the third and fourth grooves and communicating with the oxygen reservoir of the adsorption bed. 
   The first solenoid valve is preferred to use a 5 port 3 way solenoid valve or 3 port 2 way solenoid valves. 
   The second solenoid valve is preferred to use a 2 port 2 way solenoid valve. 
   The process of oxygen concentration according to the preferred embodiment of the present invention includes a step of compressing the external air supplied to the first adsorption column of the adsorption bed through the air compressor; a step of production of the concentrated oxygen in the time of same pressure in both the inside of the adsorption bed and the first adsorption column as the nitrogen substance included in the compressed air is adsorbed in the first adsorption column; a step of the first upper part equalization to equalize the upper part pressure of the first and second adsorption columns, by supplying the compressed gas supplied on the first adsorption column to the second adsorption column, which is included in inside of the adsorption bed, after production of the concentrated oxygen on the first adsorption column; a step of the first upper/lower part equalization accomplished with the first and second adsorption columns to equalize with the first upper part equalization and lower part equalization concurrently, by supplying the external air supplied with the step of first upper part equalization through the lower part of the first adsorption column through the lower part of the second adsorption column; 
   The process further includes a step of decompression in which the first adsorption column reduces the pressure without supplying the compressed external air to the first adsorption column while supplying the compressed external air to the second adsorption column inside of the adsorption bed and elevating the internal pressure through the air compressor; a step of cleansing, accomplished with desorption and rinsing with the pressure of the first adsorption column in the state of decompressed nearly to the atmospheric pressure, wherein the nitrogen substance containing in the compressed air is adsorbed on the second adsorption column and a high concentrated oxygen is produced in the time of same pressure in both the adsorption bed and the second adsorption column; a step of equalization of the second upper part, wherein the supplied compressed gas on the second adsorption column is supplied to the first adsorption column installed inside the adsorption bed after the producing of concentrated oxygen at the second adsorption column to equalize the upper part pressure of the first and second adsorption column; and a step of second upper/lower part equalization accomplished concurrently with the lower part equalization and the second upper part equalization of the first and second adsorption columns with the second upper equalization step, by supplying external air supplied through the lower part of the second adsorption column through the lower part of the first adsorption column. 
   The step of production of the concentrated oxygen includes a step of storing concentrated oxygen where the high concentrated oxygen produced on the first adsorption column is stored within the adsorption bed. 
   The step of the first and the second upper/lower part equalization is carried as the pressure of the first adsorption column is lowered rapidly and the pressure of the second adsorption column is elevated rapidly and thus, the pressure of the first and second adsorption columns reaches to the same pressure. 
   The step of the first upper/lower part equalization is accomplished concurrently and continuously when the step of the first upper part equalization is established. 
   The step of the second upper/lower part equalization is accomplished concurrently and continuously when the step of the second upper part equalization is established. 
   Next, the present invention will be described in more detail in connection with several examples, however, the present invention is not limited by the examples. 
   As illustrated in  FIG. 1  to  FIG. 6 , the apparatus of oxygen concentration system according to the present invention includes a first solenoid valve  10  mounted on the outside of bed housing  21  which is able to supply and/or discharge the compressed air, the first and second adsorption columns  22  and  24  disposed in the adsorption bed  20  to separate the nitrogen and oxygen in the compressed air supplying through the first solenoid valve  10  and the adsorption bed  20  is provided with an oxygen reservoir  26  to store the concentrated oxygen. 
   The adsorption bed  20  is a single adsorption bed and the first and second adsorption columns  22  and  24  are disposed in parallel position and formed as a tube type in the inside in a lengthwise direction, then, the oxygen reservoir  26  is provided to store the concentrated oxygen in the inner of the bed housing  21 . 
   The first solenoid valve  10 , mounted on the external upper part of the adsorption bed  20 , is preferred to use a 5 port 3 way solenoid valve or plural 3 port 2 way solenoid valves and configured to operate to supply and discharge the compressed air produced by the air compressor  9  compressing the air to a pressure over the atmospheric pressure. 
   An exhaust silencer  2  is mounted on the outside of the adsorption bed  20  to prevent noise produced from the nitrogen gas exhausting from the first adsorption column  22  and second adsorption column  24 . 
   First and second cover assemblies  100  and  400  are mounted to the upper and lower parts of the adsorption bed  20  respectively. The first cover assembly  100  includes first and second grooves  112  and  114  which are formed on the inside surface of the first cover plate  110  corresponding to the locations of the first and second adsorption column  22 ,  24 . 
   First and second check valves  120  and  130  are mounted to the first groove  112  and second groove  114 , in order to allow the concentrated oxygen produced in the first adsorption column  22  a with the oxygen reservoir  26  of the adsorption bed  20 . An oxygen exhaust hole  118  is formed on the upper side of the supply hole  116  to connect with a tube (not shown) to a tube line (not shown) for supplying the concentrated oxygen. 
   The first and second check valves  120  and  130  are installed on the fixing holes  121  and  131  formed on the first cover plate  110 , while, valve holes  122  and  132  are formed on both side of the fixing holes  121  and  131  isolating each other to allow the flow of gas. 
   The first and second check valves  120  and  130  include the valve body  124  and  134  which operate flexibly by the pressure of gas through the valve holes  122  and  132 . 
   First orifice  140  and second orifice  150  are formed at lower sides of the first and second check valves  120  and  130  on the first and second grooves  112  and  114  of the cover plate  110 , thus, when the pressure of either the first and second adsorption columns  22  or  24  is increased and the pressure of the other one is decreased, the absorbed nitrogen of one of the first and second adsorption columns  22  and  24  is able to be cleansed with a portion of the concentrated oxygen reversely flowed to the first and second adsorption columns  22  and  24 . 
   A fitting or mounting part  160  is incorporated on an upper outside portion of the first cover plate  110  in which the mounting part  160  includes first and second through holes  162  and  164  which extend from inside of the first and second grooves  112  and  114  to the outside of the first cover assembly  100 . 
   Second solenoid valve  170  is coupled in fluid communication with the first and second through holes  162  and  164  and mounted on the fitting part  160  to enable a (partial) pressure equalization of the first and second adsorption columns  22  and  24 . The second solenoid valve  170  preferably a 2 port 2 way type solenoid valve. 
   The solenoid valve  170  is fixed by fixing screws to the screw holes formed on the fitting part  160 . 
   Chamber part  200  is constructed on the outside of the first cover plate  110  to compart separately the first and second check valves  120  and  130  and the first and second orifices  140  and  150 . 
   The first and second check valves  120  and  130  and supply hole  116  are disposed on the same line in the chamber part  200 . The first and second orifices  140  and  150  are positioned on the lower sides of the check valves  120  and  130  and the supply hole  116  and are disposed on the same line in the chamber part  200 . 
   A chamber cover  300  is mounted on the chamber part  200  of the first cover assembly  100  and a first chamber  312  is formed on the inside of the chamber cover body  310  with a compartment to separate a closely sealed region from the outside, so that the supplied gas from the first check valve  120  or second check valve  130  can flow to the supply hole  116 . 
   A second chamber  314  is formed on a lower side of the first chamber  312  with compartment to separate a closely sealed region the outside and the gas supplied through the first orifice  140  or second orifice  150  can communicate there-through. 
   A sealing element  320  is fitted along the outer edge of the first and second chambers  312  and  314  formed on the chamber cover body  310  and engaged with the outer peripheries of the chamber part  200 . 
   A cap plate  4  having multiple through holes is mounted on each upper and lower end of the first and second adsorption columns  22  and  24  which are installed inside of the adsorption bed  20 , to make the concentrated oxygen produced from the first adsorption member  22  or second adsorption member  24  flow evenly with the same flow velocity due to the through holes formed on the cap plate  4 . 
   A filter (not shown) is fitted between the cap plate  4  and the first and second adsorption columns  22  and  24  to prevent leakage of zeolite grain contained inside of the first and second adsorption columns  22  and  24  and to filter the compressed air supplied from the air compressor  9 . 
   The packing elements  6  are fitted on the inside of both the first cover assembly  100  and second cover assembly  400 . The spring  8  is interposed between the first cover assembly  100  and the cap plate  4 . Because the volume of zeolite contained in the first and second adsorption columns  22  and  24  reduces over time, the spring  8  is installed to press the first and second adsorption columns  22  and  24 . 
   The second cover assembly  400  includes the third and fourth grooves  410  and  420 , which are formed displacedly on the inner surface of the second cover plate  400  and correspond to the first and second adsorption columns  22  and  24 , and also includes connecting hole  430 , which is formed between the third and fourth grooves  410  and  420 , and is in fluid communication with the oxygen reservoir  26  of the adsorption bed  20 . 
   The second cover assembly  400  is constructed to allow the compressed air, supplied via the first solenoid valve  10  to the inside of the second cover plate  400 , to be supplied to the first adsorption column  22  or second adsorption column  24 . 
   The Operation process of the oxygen concentration system according to the preferred embodiments of the present invention includes: 
   A step (ST 100 ) of compressing the external air supplied to the first adsorption column  22  of the adsorption bed  20  by the air compressor  9 ; a step (ST 200 ) of producing the concentrated oxygen in the time of same pressure in both the insides of the adsorption bed  20  and the first adsorption column  22  as the nitrogen, included in the compressed air is adsorbed in the first adsorption column  22 ; a step (ST 300 ) of equalization for the first upper part to equalize the upper part pressure of the first and second adsorption columns  22  and  24 , by supplying the compressed gas supplied on the first adsorption column  22  to the second adsorption column  24  of the adsorption bed  20  after production of the concentrated oxygen in the first adsorption column  22 ; a step (ST 400 ) of equalization for the first upper/lower parts, which is accomplished with the first and second adsorption column  22 ,  24  to equalize with the first upper part equalization (ST 300 ) and lower part equalization concurrently, as the external air supplied by the step of first upper part equalization (ST 300 ) through the lower part of the first adsorption column  22  is supplied to the lower part of the second adsorption column  24 . 
   The process further includes: a step (ST 500 ) of decompression in which the first adsorption column  22  reduces the pressure by not supplying the compressed external air to the first adsorption column  22  while supplying the compressed external air to the second adsorption column  24  of the adsorption bed  20  and elevating the internal pressure of the second adsorption column  24 ; a step of cleansing (ST 600 ) accomplished with desorption and rinsing with the pressure of the first adsorption column  22  in the state of decompressed nearly to the atmospheric pressure, wherein the nitrogen substance containing in the compressed air is adsorbed in the second adsorption column  24  and producing a high concentrated oxygen in the time of same pressure in both the adsorption bed  20  and the second adsorption column  24 ; a step of equalization of the second upper part (ST 700 ), wherein the supplied compressed gas on the second adsorption column  24  is supplied to the first adsorption column  22  installed inside the adsorption bed  20  after the producing of concentrated oxygen at the second adsorption column  24  to equalize the upper part pressure of the first and second adsorption columns  22  and  24 ; and a step of second upper/lower part equalization (ST 800 ) accomplished concurrently with the lower part equalization and the second upper part equalization of the first and second adsorption columns  22  and  24  as the eternal air supplied by the second upper equalization step (ST 700 ) through the lower part of the second adsorption column  24  is supplied through the lower part of the first adsorption column  22 . 
   The step of production of the concentrated oxygen (ST 200 ) can include a step of storing of concentrated oxygen (ST 210 ) where the high concentrated oxygen produced on the first adsorption column  22  is stored within adsorption bed  20 . 
   The step of the first and the second upper/lower part equalizations (ST 400 , ST 800 ) are accomplished with the pressure of the first adsorption column  22  lowered rapidly and the pressure of the second adsorption column  24  elevated rapidly, and thus first and second adsorption columns  22  and  24  reach the same pressure at any second. 
   The first upper/lower part equalization (ST 400 ) is accomplished concurrently and continuously when the step of the first upper part equalization (ST 300 ) is established. 
   The step of the second upper/lower part equalization (ST 800 ) is accomplished concurrently and continuously when the step of the second upper part equalization (ST 700 ) is established. 
   The operating state according to the present invention is described with reference to the drawings; 
   As illustrated in  FIG. 1  to  FIG. 5   h , the apparatus of oxygen concentration system according to the present invention, the purity of concentrated oxygen is increased, and reciprocated the 8 steps of pressurization of air: a step of air compressing (ST 100 ), production of concentrated oxygen: a step of production of the concentrated oxygen (ST 200 ), the first upper part equalization: a step of the first upper part equalization (ST 300 ), the first upper/lower part equalization: a step of the first upper/lower part equalization (ST 400 ), depressurize: a step of decompression (ST 500 ), cleansing: a step of cleansing (ST 600 ), the second upper part equalization: a step of equalization of the second upper part (ST 700 ), the second upper/lower part equalization, a step of second upper/lower part equalization (ST 800 ) to improve the purity of concentrated oxygen, recovery of the mechanical energy of the air compressor simultaneously with decreasing the electric power consumption. 
     FIG. 5   a  illustrates the operating state of an apparatus of the oxygen concentration system according to the preferred embodiment of the present invention, in which  FIG. 5   a ( a ) illustrates the air pressure circuit line showing the compressed air flow in the oxygen concentration system, and  FIG. 5   a ( b ) is a view illustrating the gas flow in the oxygen concentration system. 
   As illustrated in  FIG. 5   a ( a ), compressed air produced from the air compressor  9  is supplied to the first solenoid valve  10  with the first and second check valves  120  and  130  closed (see  FIG. 1 ). 
   As illustrated in  FIG. 5   a  (b), the air produced from the air compressor  9  through the stage (A) of solenoid valve  10 , compresses (ST 100 ) in the first adsorption column  22 , and does not supply to the second adsorption column  24  (by off state of the stage (C) side of the first solenoid valve  10 ) and is depressurized step by step, with the second solenoid valve  170  maintained the state of closing in this time. 
   As illustrated in  FIG. 5   b , the compressed air from the air compressor  9  is supplied the first adsorption column  22  continuously, while the nitrogen substance contained in the compressed air is adsorbed by zeolite in the first adsorption column  22 , and thus, the concentrated oxygen is produced (ST 200 ) and supplied through the tube (not shown) connecting with the oxygen exhaust hole  118  separately. 
   The first check valve  120  in the first cover plate  110  (see  FIG. 1 ) is opened by the pressure of concentrated oxygen, in the time of the pressure of first adsorption column  22  is same as the inside pressure of the oxygen reservoir  26  and high purity concentrated oxygen flows to in the first chamber  312  of chamber part  200  (see  FIG. 1 ) via the valve hole  122  (see  FIG. 1 ) of the first check valve  120 . 
   The concentrated oxygen in the first chamber  312  is stored (ST 210 ) in the oxygen reservoir  26  of the adsorption bed  20  via the supply hole  116  without leakage by the sealing element  320  (see  FIG. 1 ) of the chamber cover  300 , while a part of the concentrated oxygen, produced in the first adsorption part  22 , flows via the first orifice  140  formed on the first groove  112  (see  FIG. 1 ) of the first cover plate  110  and is supplied to the second chamber  314  of the chamber part  200  (see  FIG. 1 ). 
   A portion of concentrated oxygen supplied to the second chamber  314  is supplied to the second adsorption column  24  via the second orifice  150 . 
   As described above, the concentrated oxygen, supplied to the second adsorption column  24 , cleanses the nitrogen substance adsorbed in zeolite included in the second adsorption column  24  while exhausting the nitrogen through the exhaust silencer  2  connecting with first solenoid valve  10 . 
     FIG. 5   c  illustrates the actuating state of the first upper part equalization of the oxygen concentration system according to the present invention. 
   As illustrated in  FIG. 5   c , the adsorption proceeding in a constant time followed by compressing of first adsorption column  22  by the compressed air produced by the air compressor  9  and producing the concentrated oxygen, the second solenoid valve  170  is open to communicate the first adsorption column  22  and second adsorption column  24 , concurrently. 
   That is, as the second solenoid valve  170  actuating ON, the 2 port formed inside of the second solenoid valve  170  is opened, the concentrated oxygen of the first adsorption column  22  is moved to the fitting part  160  equipped with the second solenoid valve  170  and supplied to a port of the second solenoid valve  170  and moves to another port, then flows to the second communication hole  164  (see  FIG. 1 ) of the second groove  114 . 
   The concentrated oxygen flowing in the second communication hole  164  is reversal flow to second adsorption column  24  instantly, as the pressure in the first and second adsorption columns  22  and  24  become equal on a portion, and become the first upper equalization (ST 300 ), and thus, the compressed concentrated oxygen can be reused in compressing and adsorption of the second adsorption column  24 . 
     FIG. 5   d  illustrates the operating state of the first upper/lower part complex equalization of the oxygen concentration system according to the present invention. By the first upper/lower part complex equalization the first upper equalization and the lower equalization are accomplished at the same time. 
   As illustrated in  FIG. 5   d , the lower equalization actuating is carried out in OFF state without electric power input on the solenoid valve on (A) and (C) of the first solenoid valve  10  while, both (A) and (C) are closed, and the first adsorption column  22  with the second adsorption column  24  are in fluid communication, the compressed air of the first adsorption column  22  in a high pressure state is moved to the lower part of the second adsorption column  24  in a flash, the pressure of the first and second adsorption column  22 ,  24  is become equal, and the lower equalization is achieved. 
   The upper part equalization operating is proceeded with the lower part equalization, concurrently, the pressure of first adsorption column  22  is decreased rapidly and the pressure of second adsorption column  24  is increased rapidly, thus, the pressure of the first and second adsorption columns  22  and  24  become equal (ST 400 ), finally. 
   As the compressed air moves to the first adsorption column  22  or the second adsorption column  24  and is carried out the recovery and reproduction of concentrated oxygen through the upper equalization operation, simultaneously, it can minimize the mechanical loss and improve the efficiency by reducing the operating time of air compressor  9 . 
     FIG. 5   e  illustrates the operating state of decompression of the oxygen concentration system according to the present invention. 
   As illustrated in  FIG. 5   e , the air pressurized by the air compressor  9  is supplied to the second adsorption column  24  through (C), with the solenoid valve of stage (A) of the first solenoid valve  10  in OFF state, the second adsorption column  24  is pressurized, and the continued supply of the compressed air increases the inside pressure of the second adsorption column  24 , steadily, before the open operation of the second check valve  130  (see  FIG. 1 ). 
   As the first adsorption column  22  is not supplied gradually with the compressed air from the air compressor,  9  thus, the first adsorption column  22  is gradually depressurized (ST 500 ), but the second adsorption column  24  is pressurized to the state of same pressure of the oxygen reservoir  26 , continuously. 
   As the same moment, the first adsorption column  22  connected with (C) of the first solenoid valve  10  is communicated to exhaust silencer  2 , the pressure is dropped near to the atmospheric pressure. 
     FIG. 5   f  illustrates the state of cleansing operation of the oxygen concentration system according to the present invention. 
   As illustrated in  FIG. 5   f , the compressed air from the air compressor  9  supplied to the second adsorption column  24  continuously, the nitrogen component is absorbed by zeolite of the second adsorption column  24  and produces the concentrated oxygen, and is supplied through the tube (not shown) and communicates with oxygen exhaust hole  118 . 
   As the pressure of the second adsorption column  24  becomes equal to the pressure of the inside of the oxygen reservoir  26 , the second check valve  130  is opened to external by the pressure of the concentrated oxygen, and the high purity concentrated oxygen flows into the first chamber  312  of the chamber part  200  ( FIG. 1 ) through the valve hole  132 . 
   The concentrated oxygen influx into the first chamber  312  is supplied to the oxygen reservoir  26  of the adsorption bed  20  through the supply hole  116  without leakage to outside by the sealing element  320  ( FIG. 1 ) fitted on the chamber cover  300 . At this time, a portion of the concentrated oxygen produced on the first adsorption column  22  is supplied to the second chamber  314  of the chamber part  200  through the second orifice  150  formed on the second groove  114  of the first cover plate  110  ( FIG. 1 ). 
   A portion of the concentrated oxygen supplied to the second chamber  314  is supplied to the first adsorption column  22  through the first orifice  140 . 
   As above, the concentrated oxygen supplied to the first adsorption column  22  is washing (ST 600 ) the adsorbed nitrogen in the zeolite of the first adsorption column  22  while, the nitrogen exits through the silencer connected to the first solenoid valve  10 . 
   The first adsorption column  22  is desorbed and washed while depressed nearly to the atmospheric pressure. 
     FIG. 5   g  illustrates the operation state of the second upper part equalization according to the present invention. 
   As illustrated in  FIG. 5   g , the concentrated oxygen produced by adsorption is proceeded constantly, followed with compressing of the second adsorption column  24  by the compressed air produced by the air compressor  9  and the second solenoid valve  170  is opened to communicate with the first adsorption column  22  and second adsorption column  24  concurrently. 
   That is, the electric signal is input on the second solenoid valve  170  mounted on the fitting member  160 , operating to ON state and opens the 2 port, through the second communication hole  164  ( FIG. 1 ) of the second groove  114 , the concentrated oxygen of the second adsorption column  24  moves to the fitting member  160  mounting the second solenoid valve  170 , supplied to another port of the second solenoid valve  170 , moves to one side port and to the first communication hole  162  of the first groove  112 . 
   The concentrated oxygen moved on the first funnel hole  162  is regurgitated into the first adsorption column  22  to become equal a part of the pressure of the first and second adsorption columns  22  and  24  as proceeds to equalization of the second upper part (ST 700 ). 
     FIG. 5   h  illustrates the operation state of the second upper/lower part complex equalization according to the present invention. 
   The second upper/lower part complex equalization operation (ST 800 ) means that the second upper equalization operation and lower equalization operations are proceeded concurrently in the state of changed the adsorption action of the first adsorption column  22  and the second adsorption column  24  described in  FIG. 5   d.    
   As illustrated in  FIG. 5   h , the lower part equalization operation is proceeded in the state of OFF without electric input on the solenoid valve mounted on (A) and (C) of the first solenoid valve  10 , with both (A) and (C) closed, and through the position (B) the first adsorption column  22  and second adsorption column  24  are in fluid communication, and the compressed air of the second adsorption column  24  in a high pressure state moves into the direction of the lower part of the first adsorption column  22  instantly and becomes equal to the pressure of the first adsorption column  22  and second adsorption column  24  to achieve the lower part equalization. 
   With it, the second upper part equalization operation is proceeded simultaneously with the pressure of the second adsorption column  24  lowered rapidly and the pressure of the first adsorption column  22  elevated rapidly, the pressure of the first adsorption column  22  and second adsorption column  24  becomes equal, finally. 
   As described above, a part of produced gas is used to recompress through the upper part equalize operating, and the compressed air is used to recompress another adsorption column through the lower part equalization operation; thus the mechanical energy can be recovered. 
     FIG. 6  illustrates a graph of pressure distribution chart according to the operation of the oxygen concentration system according to the preferred embodiment of the present invention. 
   As illustrated in  FIG. 6 , as the pressurized air followed by the operation of the air compressor  9  is supplied to the first adsorption column  22  of the oxygen container  20 , the first adsorption column  22  is pressurized to a higher pressure, and the second adsorption column  24  is not supplied with the compressed air, thus the pressure is lowered slowly, and the first adsorption column  22  is pressurized continuously then, the concentrated oxygen produced in the time of the first adsorption column  22  and oxygen container  20  become an equal pressure. 
   The internal pressure of the first adsorption column  22  is lowered a little through the first upper part equalization after the concentrated oxygen produced in the first adsorption column  22  as above, the first and second adsorption columns  22  and  24  are communicated through the first upper/lower part equalization, and the pressure of the first adsorption column  22  is lowered rapidly and the pressure of the second adsorption column  24  is elevated higher, the pressure of the first adsorption column  22  and the pressure of the second adsorption column  24  become equal at once. 
   The concentrated oxygen produced in the first adsorption column  22  communicates with the silencer, and the pressure drops to the atmospheric pressure and the compressed air from the air compressor is supplied to the second adsorption column  24 , and the pressure is elevated. 
   At the same time, the pressure of the first adsorption column  22  is lowered to near atmospheric pressure and accomplishes the desorption and cleansing, and the high purity concentrated oxygen is produced in the second adsorption column  24 . 
   After, the high purity concentrated oxygen is produced in the second adsorption column  24 , as above, the supplied compressed air on second adsorption column  24  is supplied to the first adsorption column  22 , and thus, the second upper part equalization is accomplished and the upper part pressure of the first adsorption column  22  and second adsorption column  24  become equal. 
   As the same time, external air supplied through the lower part of the second adsorption column  24  is supplied through the lower part of the first adsorption column  22  and the second upper/lower part equalization is accomplished and the pressure of the first adsorption column  22  and second adsorption column  24  become equal. 
   As described above, the first and second upper/lower part evenness is accomplished, the time of compressing operation of the air compressor is shortened and the efficiency is improved while decreasing the mechanical loss. 
   Although preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will be appreciated that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.