CA2266228A1 - A pneumatically controlled oxygen producer by pressure swing adsorption - Google Patents
A pneumatically controlled oxygen producer by pressure swing adsorption Download PDFInfo
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- CA2266228A1 CA2266228A1 CA 2266228 CA2266228A CA2266228A1 CA 2266228 A1 CA2266228 A1 CA 2266228A1 CA 2266228 CA2266228 CA 2266228 CA 2266228 A CA2266228 A CA 2266228A CA 2266228 A1 CA2266228 A1 CA 2266228A1
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Abstract
The present invention discloses a pneumatically controlled oxygen concentrator by pressure swing adsorption method. Its full-pneumatic control device consists of two pilot-pilot two-position five-way valves, a one-way cylinder and a mechanical two-way valve, no electronic and electric components are used. The automatic control is accomplished by the pneumatic components. Two molecular sieve tanks of the oxygen concentrator are charged and discharged with compressed air by a pneumatic control apparatus, and proceed with adsorption process and desorption process alternatively. This oxygen concentrator is simple and compact in structure, low in cost, good in reliability and easy for maintenance and repair.
Description
A Pneumatic Controlled Pressure Swing Adsorption Oxygen Concentrator Background of the Invention The present invention relates to a medical oxygen producing equipment, and more particularly to an automatically controlled oxygen concentrator by pressure swing adsorption method.
A small medical oxygen concentrator by pressure swing adsorption is very popular, which has entered into many families of European and American countries for their medical care. For example, each of the 5-6 largest manufacturers in the United States, manufactures 10,000-30,000 small-sized oxygen concentrators annually.
A small oxygen concentrator with pressure swing adsorption is generally equipped with two tanks filled therein with molecular sieves. The molecular sieves have uniform pores with molecular dimensions. These pores can selectively adsorb nitrogen molecules, but do not adsorb oxygen molecules.
Therefore nitrogen and oxygen can be separated from air by the adsorption process, and yield oxygen gas with high purity.
A typical pressure swing adsorption process for producing oxygen is as follows: Firstly the indoor air is compressed by a medical oilless air compressor to a pressure of 0.15-0.30 MPa. By a pneumatic circuit consisting of pneumatic components, the compressed air is led to the first molecular sieve tank and contacted with the molecular sieves, and the nitrogen molecules in the compressed air are adsorbed in the molecular sieves, the remaining oxygen molecules are discharged from the other end of the tank. The first molecular sieve tank is in an "adsorption process". A part of the discharged pure oxygen enters into an oxygen storage tank, after pressure regulated, filtered and supplied to patients for breathing. Another part of oxygen enters into the second molecular sieve tank. The second molecular sieve tank is controlled by a pneumatic circuit, now it is connected to the atmosphere with no pressure inside. The nitrogen molecules adsorbed in the previous cycle in the molecular sieve of the tank is promptly in a free state. The input pure oxygen "purges" and strips the nitrogen molecules adsorbed into the air and results in the air having low concentration of oxygen, which is discharged from another end of the second molecular sieve tank into the atmosphere. At this stage, the second molecular sieve tank is called a "desorption process".
After about 10-15 seconds, the first molecular sieve tank is "saturated", while the second molecular sieve tank is already "purged" and regenerated. Consequently the air flow controlled automatically by pneumatic circuit is reversed, the compressed air is switched into the second molecular sieve tank, wherein the molecular sieves conduct adsorption processes and produce oxygen. At the same time the first molecular sieve tank is changed into air-discharging with no pressure inside. A part of oxygen discharged from the second molecular sieve tank enters into the first molecular sieve tank to conduct the desorption process. An independent oxygen storage tank receives oxygen coming alternately and uninterruptedly from two molecular sieve tanks, which can be supplied to the oxygen breather. The two molecular sieve tanks adsorb and desorb in endless cycles for separating oxygen continuously from the atmosphere. They consume no other substances but electric power.
There are two kinds of control methods for pneumatic control circuit in the new commercial small oxygen concentrator. One of them is a timing control circuit, i.e., controlling the direction of air flow by switching on and off the valves according to the timing, which is divided into controlling valves mechanically and by electronic components.
The second one is to control the direction of air flow according to the pressure in the circuit by selecting an optimum shifting pressure in the pneumatic circuit. When this given shifting pressure is reached, the direction of the air flow is changed. In the circuit an electronic pressure sensor sends out signals in response to the given pressure, and the signals are magnified via electronic components and then electromagnetic valves are controlled to change the direction of the air flow.
Since the output of the air compressor varies in different circumstances, the mode with pressure controlling can result in steady performance of the oxygen concentrator.
Factors, such as different elevations, thin air, voltage change, compressor ware-and-tear, or greater resistance to inlet air due to unclean air filters result in the output of air compressor reduced, and the control circuit may prolong the working cycle automatically, maintain until the given optimum shifting pressure is approached and then the direction of air flow in the pneumatic circuit is changed. However the first timing control circuit has no such advantage.
Therefore, the pressure control is a tendency of development at present.
Many kinds of oxygen concentrators with high pressure swing adsorption have been disclosed in references;
some patent and patent applications are listed below:
U.S. Patents: 5,183,483; 4,545,790; 3,659,399;
CN Patents and Patent Applications:
95244068.7; 95190507.4;
94115637.0; 91214831.4 872064250 and 872060760.
A part of the above references involves large-size oxygen manufacturing devices with complicated structure, huge volume and high cost, so they are not suitable for use in small-size oxygen concentrators.
In the small-size oxygen concentrators disclosed in the prior art, more valves are used in all pneumatic control circuits, in which electronic components control the pilot-valve and the pilot-valve controls the main valve. The following shortcomings exist in these devices:
a) More pneumatic components, more pressure pipes and joints which increase the possibility of leakage;
b) More electric controlling circuits and joints which lead to disturbances readily;
c) Complicated electronic and electric controlling circuits, which are more difficult for maintenance and repair.
The above said drawbacks enhance the cost of manufacturing and the difficulties for maintenance and repair.
In particular, the reliability of oxygen concentrators decreases.
The commercial oxygen concentrators by three famous companies in the United States are as follows:
Oxygen Concentrator Model 590 (Puritan Bennett Co., US);
Oxygen Concentrator Newlife (Air Sep Co., US); and Oxygen Concentrator Alliance (Healthdyne Technologies Co., US, U.S. Patent 5,183,483).
One of the famous brand names of oxygen concentrators in the market gives high concentration of oxygen with low noise and good appearance. Its pneumatic control circuit contains a Sensym electronic pressure sensor which measures the air pressure in the circuit. When a given pressure is reached, the pressure sensor sends out signals, which are magnified by an electronic integrated circuit board, and result in controlling a pair of clippard electromagnetic pilot-valves controlled in order. The electromagnetic pilot-valve controls two air operated Hamphrey two-position three-way valves, which permit the main air flow into and out of the two molecular sieve tanks for producing oxygen. The following illustration shows the change of working medium for automatic control.
circuit Electronic Electric Controlling System I~Pneumatic Control Valve Components ~ I
The reliability of oxygen concentrator is affected due to using many pneumatic components and complicated pipelines and electric controlling circuits. For example, before delivering the apparatus from Hong Kong, to Tianjin Harbor, 200 of the apparatus were found out of order during routine examination. Having been delivered to Beijing, a further 5% of the apparatus needed repairs after being checked. Due to long distance transportation in China and serious conditions in the Qinghai-Xizang Plateau, etc., it is even more tiresome for agents going back and forth to repair them.
The Durable-Cassia Co., Ltd., from 1994 to 1997, handled more than 50 % of oxygen concentrators imported to China.
After selling and doing maintenance for several years, people realized that a small-size oxygen concentrator is necessary to be developed for China and other developing countries. It shall have high reliability under various unfavorable conditions. Its price should be reasonable and acceptable by common families, and it must also be convenient for maintenance.
The object of the present invention is to overcome the drawbacks in said references and commercial products, and to provide a small-size oxygen concentrator, which is controlled by a new pneumatic device, suitable for use in various unfavorable conditions, simple and compact in structure, few components and pipelines, high in reliability, cheap in price, as well as convenient for maintenance.
SUMMARY OF THE INVENTION
The present invention provides an oxygen concentrator with pressure swing adsorption, comprising a left molecular sieve tank and a right molecular sieve tank with molecular sieves filled inside, an oxygen storage tank connected with the said two molecular sieve tanks, an air compressor, and an automatic control device controlling the direction of air flow and linking pipelines, wherein the said automatic control device is a full-pneumatic pressure control apparatus.
The said full-pneumatic pressure control apparatus is a pneumatic combined valve.
The said pneumatic combined valve consists of two pilot-pilot two-position five-way valves, a one-way cylinder and a mechanical two-way valve, the said pneumatic components connected by drilling holes on the valve body to eliminate pipelines.
One of the said two-position five-way valves is a control valve, used for controlling the air feed to and air discharge from the molecular sieve tanks.
Another of the said two-position five-way valves is a distribution valve, which is connected with the control valve, used for distributing the air flow paths on both sides of the control valve.
The said mechanical two-way valve is connected with the distribution valve, used for supplying air flow to the distribution valve and the control valve during pressure shifting.
The said one-way cylinder plays a role of displacement or pressure sensor, and locates at the same horizontal level as that of the mechanical two-way valve, which sends out signals to the mechanical two-way valve.
The one-way cylinder contains a spring and a piston inside, and the length of rod part of the piston is adjustable.
The said three tanks are connected via pipes, in which two air pipes connected with the said oxygen storage tank are equipped with two one-way valves respectively, and the said connecting pipe connected with the said two molecular sieve tanks is equipped with a throttling orifice in the middle.
The air flow required in the invention is supplied by an air compressor.
By using the said technical solution of the present invention, the full-pneumatic control device sends out signals to various pneumatic components according to the pressure variation of the pneumatic circuit itself, and then the automatic operation of the pneumatic device is controlled by all pneumatic components. It may be shown as follows:
pneumatic device ~ pneumatic components The operation and control of the full-pneumatic device is from pneumatic to pneumatic. There is no transformation of other media, and the goal of automatic control is attained similarly. In this manner it prevents addition of electronic and electric components as that in the pneumatic control circuit of the prior art leading to increase of transformation of medium among pneumatic, electronic and electric components.
Therefore, the pneumatic control is greatly simplified, the reliability increased, the manufacturing cost lowered and the daily maintenance easier, and the object of the invention is accomplished.
Meanwhile, in the present invention, the two two-position five-way valves, the one-way cylinder and the two-way valve comprise a very compact pneumatic combined valve, resulting in the integrated, simple and compact internal structure of oxygen concentrator, less components, less pipelines and less electric wires. The detail advantages are the following:
Reliability improved - The full-pneumatic control has neither electronic nor electric components, the structure is simple, shockproof, resistant to temperature, few pipes and no electric wiring, and disturbance reduced. It has been proved that the reliability is good after long distance transportation test for sample apparatus by bus from the coast to Qinghai-Xizang Plateau.
Manufacturing cost reduced - Without electronic components, only one combined valve is used, cost for parts decreased, labor saved for assembly, allowing the price of product to be reasonable and competitive, and readily entering into families.
Maintenance easy - Internal structure may be 10 understood directly through viewing. Technicians can carry out maintenance work after a short term of training.
The specifications of the small-sized oxygen concentrator in accordance with the present invention are as follows:
Oxygen flow 1-5 liters/minute, adjustable Oxygen purity 1-3 liters/minute, 95~3%
4-5 liters/minute, 90~3%
Power Required <500 watts The performance of the prototype is the same as those products of said three U.S. companies.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows that the left molecular sieve tank is in the adsorption process, the right molecular sieve tank is in the desorption process, and the device is at low pressure stage (0.05 MPa) ;
Fig. 2 shows that the device is at the intermediate pressure stage (0.08 MPa-0.12 MPa);
Fig. 3 shows that the device is at the moment when air flow is shifting (0.15-0.18 MPa);
Fig. 4 shows the completion of air flow shifting, the next cycle starts, the left molecular sieve tank is in the desorption process, whereas the right molecular sieve tank becomes in adsorption process, and the device returns to a low pressure stage (0.05 MPa).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described in more detail below in combination with the drawings.
Fig. 1 is the beginning of a cycle. The compressed air is carried out of an oilless air compressor 19, passed through pipe 24, five-way valve 11 and pipe 3 to left molecular sieve tank 1. Under the pressure, the molecular sieve in the tank 1 adsorbs nitrogen molecules from the air, the remaining oxygen is discharged out of the upper pipe 2 of the molecular sieve tank 1. At this time the tank 1 is in the adsorption process.
A part of oxygen gas discharged from pipe 2 is passed through the check valve 4 to the oxygen storage tank 7 for use of oxygen breather. Another part of oxygen is passed through the throttling orifice 5 and pipe 9 to the top of the right molecular sieve tank 10, while the bottom of the right molecular sieve tank 10 is vented to the atmosphere via pipe 8 and five-way valve 11, the tank has no pressure inside. The nitrogen molecules adsorbed on the surface of the molecular sieve of tank 10 in the previous cycle become in a free state under no pressure. Rinsed and stripped by input oxygen gas, the nitrogen is mixed and returned to the air with low oxygen content (oxygen content: 16-18%, close to the content in the air exhaled by man), which is discharged via pipe 8 and five-way valve 11 into the atmosphere. The molecular sieve tank 10 is in a desorption process.
Meanwhile, the compressed air is passed through pipe 25, exerts pressure on the left cavity of five-way valve 14, and tends to push the valve spool to shift rightwards.
However, as it is at a low pressure stage, the air pressure is 0.05 MPa only, the thrust is not enough to overcome the internal friction of valve 14, unable to push the valve core to move rightwards.
Another compressed air is passed through pipe 23 to the one-way cylinder 22, and starts to push the piston 20 to shift rightwards gradually. The mechanical two-way valve 16 is in a closed position, whereas the compressed air in pipe 18 is cut off by valve 16.
Fig. 2 is a continuation of Fig. 1. Because the air compressor l9 supplies compressed air continuously, and the throttling orifice 5 restricts the passing of oxygen, the pressure in the pneumatic device is increased gradually. The thrust of compressed air acted upon the left cavity of valve 14 via pipe 25 is increased gradually as well. When the air pressure is raised to 0.08-0.12 MPa, the thrust acted upon the left cavity of valve 14 is enough to overcome the internal friction of valve 14, and it pushes the valve spool to the right side immediately, thereupon the valve 14 is reversing.
Pipe 15 and pipe 13 are connected, while pipe 26 is directed to the atmosphere.
Now the valve 14 has already connected with the control air flow path, which pushes the spool of valve 11 leftwards. However, the mechanical two-way valve 16 is still in a closed position, no pressure is in pipe 15 and pipe 13, the right cavity of valve 11 obtains no pressure, and the valve spool still maintains its original position. Valve 14 has only distributed in advance the air flow path of control valve 11, the reversing of valve 11 does not occur yet. The molecular sieve tank 1 is still in the adsorption process, and the molecular sieve tank 10 remains in its desorption process.
The one-way cylinder 22 is exerted by the gradually increased air pressure via pipe 23, the piston 20 compresses gradually the spring 21 to shift rightwards. The rod part of piston 20 is approaching little by little to the two-way valve 16, but does not touch it yet.
In Fig. 3 the pressure of the pneumatic device is increased continuously, the compressed air via pipe 23 pushes piston 21 to shift rightwards. When the pressure reaches 0.15-0.18 MPa, the rod end of piston 21 touches the two-way valve 16 and pushes its valve spool, so the valve 16 opens immediately. At this moment, the compressed air via pipe 18 is passed through the two-way valve 16, and again via the air flow path where the control valve 11 is already distributed in advance by valve 14 (Fig. 2), i.e. passing through pipe 15, valve 14 and pipe 13. The right cavity of valve 11 is exerted by the air pressure via pipe 13, its valve spool is pushed at once to the left, consequently the valve 11 shifts the direction of main air flow.
As shown in the figure, the main air flow is passed through pipe 24, valve 11 and pipe 8 into the right molecular sieve tank 10 through the bottom. The molecular sieve in the tank 10 has undertaken a thorough desorption process and restored its capacity of adsorbing nitrogen molecules, and it begins to adsorb nitrogen molecules under pressure. The molecular sieve tank 10 is changed to conduct adsorption process. After the nitrogen molecules are adsorbed, the remaining oxygen is discharged out of pipe 9 from the upper of the tank 10. A part of discharged oxygen is passed through check valve 6 into oxygen storage tank 7, for use of oxygen breather. Another part of oxygen is passed through the throttling orifice 5 and pipe 2 into the top of the left molecular sieve tank 1. Now the molecular sieve tank 1 is connected to the atmosphere via pipe 3 and valve 11, with no pressure inside. The molecular sieve is rinsed and stripped by oxygen with no pressure, thus the nitrogen molecules adsorbed on it surface are desorbed. The molecular sieve tank 1 is changed to conduct the desorption process. The oxygen entered into the tank 1 is mixed with the nitrogen molecules desorbed, resulting in low oxygen air. It is discharged from the bottom of the tank 1 and vented to the atmosphere via pipe 3 and valve 11.
The stable and precise optimum shifting pressure may be obtained by adjusting the strength of the spring 21 and the length of the rod of the piston.
In the Fig. 4, as shown above in Fig. 3, the compressed air enters instantly into the right molecular sieve tank 10. The tank 10 with no pressure originally, suddenly intakes a great deal of compressed air, and the pressure of the pneumatic device is dropped back immediately to a low pressure of 0.05 MPa. As soon as the pressure of the device 10 falls, the spring 21 in the one-way cylinder 22 pushes the piston 20 leftwards to its original position. The spring 17 of the mechanical two-way valve 16 also moves the valve spool to the left side. Valve 16 is closed, while the air flow of pipe 18 is cut off.
The operation in Fig. 4 is similar to that in Fig.
1, but the direction of main air flow is reversed. The molecular sieve tank 10 is in the adsorption process, and the molecular sieve tank 1 is in the desoption process. Hereafter the pressure in the device increases gradually, when it approaches the shifting pressure, the air flow is shifted again. Thus oxygen is produced in endless cycles.
In combination with figures shown as above, a detailed description is given to the structure and working process of oxygen concentrator according to the present invention, and the connection between various components as a specific embodiment is also disclosed. The specific linkage embodiments of any forms or any further variations or modifications, so long as the technical solution of the present is concerned, fall within the scope of the present invention.
A small medical oxygen concentrator by pressure swing adsorption is very popular, which has entered into many families of European and American countries for their medical care. For example, each of the 5-6 largest manufacturers in the United States, manufactures 10,000-30,000 small-sized oxygen concentrators annually.
A small oxygen concentrator with pressure swing adsorption is generally equipped with two tanks filled therein with molecular sieves. The molecular sieves have uniform pores with molecular dimensions. These pores can selectively adsorb nitrogen molecules, but do not adsorb oxygen molecules.
Therefore nitrogen and oxygen can be separated from air by the adsorption process, and yield oxygen gas with high purity.
A typical pressure swing adsorption process for producing oxygen is as follows: Firstly the indoor air is compressed by a medical oilless air compressor to a pressure of 0.15-0.30 MPa. By a pneumatic circuit consisting of pneumatic components, the compressed air is led to the first molecular sieve tank and contacted with the molecular sieves, and the nitrogen molecules in the compressed air are adsorbed in the molecular sieves, the remaining oxygen molecules are discharged from the other end of the tank. The first molecular sieve tank is in an "adsorption process". A part of the discharged pure oxygen enters into an oxygen storage tank, after pressure regulated, filtered and supplied to patients for breathing. Another part of oxygen enters into the second molecular sieve tank. The second molecular sieve tank is controlled by a pneumatic circuit, now it is connected to the atmosphere with no pressure inside. The nitrogen molecules adsorbed in the previous cycle in the molecular sieve of the tank is promptly in a free state. The input pure oxygen "purges" and strips the nitrogen molecules adsorbed into the air and results in the air having low concentration of oxygen, which is discharged from another end of the second molecular sieve tank into the atmosphere. At this stage, the second molecular sieve tank is called a "desorption process".
After about 10-15 seconds, the first molecular sieve tank is "saturated", while the second molecular sieve tank is already "purged" and regenerated. Consequently the air flow controlled automatically by pneumatic circuit is reversed, the compressed air is switched into the second molecular sieve tank, wherein the molecular sieves conduct adsorption processes and produce oxygen. At the same time the first molecular sieve tank is changed into air-discharging with no pressure inside. A part of oxygen discharged from the second molecular sieve tank enters into the first molecular sieve tank to conduct the desorption process. An independent oxygen storage tank receives oxygen coming alternately and uninterruptedly from two molecular sieve tanks, which can be supplied to the oxygen breather. The two molecular sieve tanks adsorb and desorb in endless cycles for separating oxygen continuously from the atmosphere. They consume no other substances but electric power.
There are two kinds of control methods for pneumatic control circuit in the new commercial small oxygen concentrator. One of them is a timing control circuit, i.e., controlling the direction of air flow by switching on and off the valves according to the timing, which is divided into controlling valves mechanically and by electronic components.
The second one is to control the direction of air flow according to the pressure in the circuit by selecting an optimum shifting pressure in the pneumatic circuit. When this given shifting pressure is reached, the direction of the air flow is changed. In the circuit an electronic pressure sensor sends out signals in response to the given pressure, and the signals are magnified via electronic components and then electromagnetic valves are controlled to change the direction of the air flow.
Since the output of the air compressor varies in different circumstances, the mode with pressure controlling can result in steady performance of the oxygen concentrator.
Factors, such as different elevations, thin air, voltage change, compressor ware-and-tear, or greater resistance to inlet air due to unclean air filters result in the output of air compressor reduced, and the control circuit may prolong the working cycle automatically, maintain until the given optimum shifting pressure is approached and then the direction of air flow in the pneumatic circuit is changed. However the first timing control circuit has no such advantage.
Therefore, the pressure control is a tendency of development at present.
Many kinds of oxygen concentrators with high pressure swing adsorption have been disclosed in references;
some patent and patent applications are listed below:
U.S. Patents: 5,183,483; 4,545,790; 3,659,399;
CN Patents and Patent Applications:
95244068.7; 95190507.4;
94115637.0; 91214831.4 872064250 and 872060760.
A part of the above references involves large-size oxygen manufacturing devices with complicated structure, huge volume and high cost, so they are not suitable for use in small-size oxygen concentrators.
In the small-size oxygen concentrators disclosed in the prior art, more valves are used in all pneumatic control circuits, in which electronic components control the pilot-valve and the pilot-valve controls the main valve. The following shortcomings exist in these devices:
a) More pneumatic components, more pressure pipes and joints which increase the possibility of leakage;
b) More electric controlling circuits and joints which lead to disturbances readily;
c) Complicated electronic and electric controlling circuits, which are more difficult for maintenance and repair.
The above said drawbacks enhance the cost of manufacturing and the difficulties for maintenance and repair.
In particular, the reliability of oxygen concentrators decreases.
The commercial oxygen concentrators by three famous companies in the United States are as follows:
Oxygen Concentrator Model 590 (Puritan Bennett Co., US);
Oxygen Concentrator Newlife (Air Sep Co., US); and Oxygen Concentrator Alliance (Healthdyne Technologies Co., US, U.S. Patent 5,183,483).
One of the famous brand names of oxygen concentrators in the market gives high concentration of oxygen with low noise and good appearance. Its pneumatic control circuit contains a Sensym electronic pressure sensor which measures the air pressure in the circuit. When a given pressure is reached, the pressure sensor sends out signals, which are magnified by an electronic integrated circuit board, and result in controlling a pair of clippard electromagnetic pilot-valves controlled in order. The electromagnetic pilot-valve controls two air operated Hamphrey two-position three-way valves, which permit the main air flow into and out of the two molecular sieve tanks for producing oxygen. The following illustration shows the change of working medium for automatic control.
circuit Electronic Electric Controlling System I~Pneumatic Control Valve Components ~ I
The reliability of oxygen concentrator is affected due to using many pneumatic components and complicated pipelines and electric controlling circuits. For example, before delivering the apparatus from Hong Kong, to Tianjin Harbor, 200 of the apparatus were found out of order during routine examination. Having been delivered to Beijing, a further 5% of the apparatus needed repairs after being checked. Due to long distance transportation in China and serious conditions in the Qinghai-Xizang Plateau, etc., it is even more tiresome for agents going back and forth to repair them.
The Durable-Cassia Co., Ltd., from 1994 to 1997, handled more than 50 % of oxygen concentrators imported to China.
After selling and doing maintenance for several years, people realized that a small-size oxygen concentrator is necessary to be developed for China and other developing countries. It shall have high reliability under various unfavorable conditions. Its price should be reasonable and acceptable by common families, and it must also be convenient for maintenance.
The object of the present invention is to overcome the drawbacks in said references and commercial products, and to provide a small-size oxygen concentrator, which is controlled by a new pneumatic device, suitable for use in various unfavorable conditions, simple and compact in structure, few components and pipelines, high in reliability, cheap in price, as well as convenient for maintenance.
SUMMARY OF THE INVENTION
The present invention provides an oxygen concentrator with pressure swing adsorption, comprising a left molecular sieve tank and a right molecular sieve tank with molecular sieves filled inside, an oxygen storage tank connected with the said two molecular sieve tanks, an air compressor, and an automatic control device controlling the direction of air flow and linking pipelines, wherein the said automatic control device is a full-pneumatic pressure control apparatus.
The said full-pneumatic pressure control apparatus is a pneumatic combined valve.
The said pneumatic combined valve consists of two pilot-pilot two-position five-way valves, a one-way cylinder and a mechanical two-way valve, the said pneumatic components connected by drilling holes on the valve body to eliminate pipelines.
One of the said two-position five-way valves is a control valve, used for controlling the air feed to and air discharge from the molecular sieve tanks.
Another of the said two-position five-way valves is a distribution valve, which is connected with the control valve, used for distributing the air flow paths on both sides of the control valve.
The said mechanical two-way valve is connected with the distribution valve, used for supplying air flow to the distribution valve and the control valve during pressure shifting.
The said one-way cylinder plays a role of displacement or pressure sensor, and locates at the same horizontal level as that of the mechanical two-way valve, which sends out signals to the mechanical two-way valve.
The one-way cylinder contains a spring and a piston inside, and the length of rod part of the piston is adjustable.
The said three tanks are connected via pipes, in which two air pipes connected with the said oxygen storage tank are equipped with two one-way valves respectively, and the said connecting pipe connected with the said two molecular sieve tanks is equipped with a throttling orifice in the middle.
The air flow required in the invention is supplied by an air compressor.
By using the said technical solution of the present invention, the full-pneumatic control device sends out signals to various pneumatic components according to the pressure variation of the pneumatic circuit itself, and then the automatic operation of the pneumatic device is controlled by all pneumatic components. It may be shown as follows:
pneumatic device ~ pneumatic components The operation and control of the full-pneumatic device is from pneumatic to pneumatic. There is no transformation of other media, and the goal of automatic control is attained similarly. In this manner it prevents addition of electronic and electric components as that in the pneumatic control circuit of the prior art leading to increase of transformation of medium among pneumatic, electronic and electric components.
Therefore, the pneumatic control is greatly simplified, the reliability increased, the manufacturing cost lowered and the daily maintenance easier, and the object of the invention is accomplished.
Meanwhile, in the present invention, the two two-position five-way valves, the one-way cylinder and the two-way valve comprise a very compact pneumatic combined valve, resulting in the integrated, simple and compact internal structure of oxygen concentrator, less components, less pipelines and less electric wires. The detail advantages are the following:
Reliability improved - The full-pneumatic control has neither electronic nor electric components, the structure is simple, shockproof, resistant to temperature, few pipes and no electric wiring, and disturbance reduced. It has been proved that the reliability is good after long distance transportation test for sample apparatus by bus from the coast to Qinghai-Xizang Plateau.
Manufacturing cost reduced - Without electronic components, only one combined valve is used, cost for parts decreased, labor saved for assembly, allowing the price of product to be reasonable and competitive, and readily entering into families.
Maintenance easy - Internal structure may be 10 understood directly through viewing. Technicians can carry out maintenance work after a short term of training.
The specifications of the small-sized oxygen concentrator in accordance with the present invention are as follows:
Oxygen flow 1-5 liters/minute, adjustable Oxygen purity 1-3 liters/minute, 95~3%
4-5 liters/minute, 90~3%
Power Required <500 watts The performance of the prototype is the same as those products of said three U.S. companies.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows that the left molecular sieve tank is in the adsorption process, the right molecular sieve tank is in the desorption process, and the device is at low pressure stage (0.05 MPa) ;
Fig. 2 shows that the device is at the intermediate pressure stage (0.08 MPa-0.12 MPa);
Fig. 3 shows that the device is at the moment when air flow is shifting (0.15-0.18 MPa);
Fig. 4 shows the completion of air flow shifting, the next cycle starts, the left molecular sieve tank is in the desorption process, whereas the right molecular sieve tank becomes in adsorption process, and the device returns to a low pressure stage (0.05 MPa).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described in more detail below in combination with the drawings.
Fig. 1 is the beginning of a cycle. The compressed air is carried out of an oilless air compressor 19, passed through pipe 24, five-way valve 11 and pipe 3 to left molecular sieve tank 1. Under the pressure, the molecular sieve in the tank 1 adsorbs nitrogen molecules from the air, the remaining oxygen is discharged out of the upper pipe 2 of the molecular sieve tank 1. At this time the tank 1 is in the adsorption process.
A part of oxygen gas discharged from pipe 2 is passed through the check valve 4 to the oxygen storage tank 7 for use of oxygen breather. Another part of oxygen is passed through the throttling orifice 5 and pipe 9 to the top of the right molecular sieve tank 10, while the bottom of the right molecular sieve tank 10 is vented to the atmosphere via pipe 8 and five-way valve 11, the tank has no pressure inside. The nitrogen molecules adsorbed on the surface of the molecular sieve of tank 10 in the previous cycle become in a free state under no pressure. Rinsed and stripped by input oxygen gas, the nitrogen is mixed and returned to the air with low oxygen content (oxygen content: 16-18%, close to the content in the air exhaled by man), which is discharged via pipe 8 and five-way valve 11 into the atmosphere. The molecular sieve tank 10 is in a desorption process.
Meanwhile, the compressed air is passed through pipe 25, exerts pressure on the left cavity of five-way valve 14, and tends to push the valve spool to shift rightwards.
However, as it is at a low pressure stage, the air pressure is 0.05 MPa only, the thrust is not enough to overcome the internal friction of valve 14, unable to push the valve core to move rightwards.
Another compressed air is passed through pipe 23 to the one-way cylinder 22, and starts to push the piston 20 to shift rightwards gradually. The mechanical two-way valve 16 is in a closed position, whereas the compressed air in pipe 18 is cut off by valve 16.
Fig. 2 is a continuation of Fig. 1. Because the air compressor l9 supplies compressed air continuously, and the throttling orifice 5 restricts the passing of oxygen, the pressure in the pneumatic device is increased gradually. The thrust of compressed air acted upon the left cavity of valve 14 via pipe 25 is increased gradually as well. When the air pressure is raised to 0.08-0.12 MPa, the thrust acted upon the left cavity of valve 14 is enough to overcome the internal friction of valve 14, and it pushes the valve spool to the right side immediately, thereupon the valve 14 is reversing.
Pipe 15 and pipe 13 are connected, while pipe 26 is directed to the atmosphere.
Now the valve 14 has already connected with the control air flow path, which pushes the spool of valve 11 leftwards. However, the mechanical two-way valve 16 is still in a closed position, no pressure is in pipe 15 and pipe 13, the right cavity of valve 11 obtains no pressure, and the valve spool still maintains its original position. Valve 14 has only distributed in advance the air flow path of control valve 11, the reversing of valve 11 does not occur yet. The molecular sieve tank 1 is still in the adsorption process, and the molecular sieve tank 10 remains in its desorption process.
The one-way cylinder 22 is exerted by the gradually increased air pressure via pipe 23, the piston 20 compresses gradually the spring 21 to shift rightwards. The rod part of piston 20 is approaching little by little to the two-way valve 16, but does not touch it yet.
In Fig. 3 the pressure of the pneumatic device is increased continuously, the compressed air via pipe 23 pushes piston 21 to shift rightwards. When the pressure reaches 0.15-0.18 MPa, the rod end of piston 21 touches the two-way valve 16 and pushes its valve spool, so the valve 16 opens immediately. At this moment, the compressed air via pipe 18 is passed through the two-way valve 16, and again via the air flow path where the control valve 11 is already distributed in advance by valve 14 (Fig. 2), i.e. passing through pipe 15, valve 14 and pipe 13. The right cavity of valve 11 is exerted by the air pressure via pipe 13, its valve spool is pushed at once to the left, consequently the valve 11 shifts the direction of main air flow.
As shown in the figure, the main air flow is passed through pipe 24, valve 11 and pipe 8 into the right molecular sieve tank 10 through the bottom. The molecular sieve in the tank 10 has undertaken a thorough desorption process and restored its capacity of adsorbing nitrogen molecules, and it begins to adsorb nitrogen molecules under pressure. The molecular sieve tank 10 is changed to conduct adsorption process. After the nitrogen molecules are adsorbed, the remaining oxygen is discharged out of pipe 9 from the upper of the tank 10. A part of discharged oxygen is passed through check valve 6 into oxygen storage tank 7, for use of oxygen breather. Another part of oxygen is passed through the throttling orifice 5 and pipe 2 into the top of the left molecular sieve tank 1. Now the molecular sieve tank 1 is connected to the atmosphere via pipe 3 and valve 11, with no pressure inside. The molecular sieve is rinsed and stripped by oxygen with no pressure, thus the nitrogen molecules adsorbed on it surface are desorbed. The molecular sieve tank 1 is changed to conduct the desorption process. The oxygen entered into the tank 1 is mixed with the nitrogen molecules desorbed, resulting in low oxygen air. It is discharged from the bottom of the tank 1 and vented to the atmosphere via pipe 3 and valve 11.
The stable and precise optimum shifting pressure may be obtained by adjusting the strength of the spring 21 and the length of the rod of the piston.
In the Fig. 4, as shown above in Fig. 3, the compressed air enters instantly into the right molecular sieve tank 10. The tank 10 with no pressure originally, suddenly intakes a great deal of compressed air, and the pressure of the pneumatic device is dropped back immediately to a low pressure of 0.05 MPa. As soon as the pressure of the device 10 falls, the spring 21 in the one-way cylinder 22 pushes the piston 20 leftwards to its original position. The spring 17 of the mechanical two-way valve 16 also moves the valve spool to the left side. Valve 16 is closed, while the air flow of pipe 18 is cut off.
The operation in Fig. 4 is similar to that in Fig.
1, but the direction of main air flow is reversed. The molecular sieve tank 10 is in the adsorption process, and the molecular sieve tank 1 is in the desoption process. Hereafter the pressure in the device increases gradually, when it approaches the shifting pressure, the air flow is shifted again. Thus oxygen is produced in endless cycles.
In combination with figures shown as above, a detailed description is given to the structure and working process of oxygen concentrator according to the present invention, and the connection between various components as a specific embodiment is also disclosed. The specific linkage embodiments of any forms or any further variations or modifications, so long as the technical solution of the present is concerned, fall within the scope of the present invention.
Claims (10)
1. An oxygen concentrator with pressure swing adsorption, comprising a left molecular sieve tank and a right molecular sieve tank with molecular sieves filled inside, an oxygen storage tank connected with the said two molecular sieve tanks, an air compressor, and an automatic control device controlling the direction of air flow and linking pipelines, wherein the said automatic control device is a full-pneumatic pressure control apparatus.
2. An oxygen concentrator according to claim 1, wherein the said full-pneumatic pressure control apparatus is a pmeumatic combined valve.
3. An oxygen concentrator according to claim 2, wherein the said pneumatic combined valve consists of two pilot-pilot two-position five-way valves, a one-way cylinder and a mechanical two-way valve, the said pneumatic components connected by drilling holes on the valve body.
4. An oxygen concentrator according to claim 3, wherein one of the said two-position five-way valves is a control valve, used for controlling the air feed to and air discharge from the molecular sieve tanks.
5. An oxygen concentrator according to claim 3, wherein the other of said two-position five-way valves is a distribution valve, which is connected with the control valve, used for distributing the air flow to both sides of the control valve.
6. An oxygen concentrator according to claim 3, wherein the said mechanical two-way valve is connected with the distribution valve, used for supplying air flow to the distribution valve and the control valve during pressure shifting.
7. An oxygen concentrator according to claim 3, wherein the said one-way cylinder plays a role of displacement or pressure sensor, and locates at the same horizontal level as that of the mechanical two-way valve, which sends out signals to the mechanical two-way valve.
8. An oxygen concentrator according to claim 7, wherein the said one-way cylinder contains a spring and a piston inside, and the length of rod part of the piston is adjustable.
9. An oxygen concentrator according to claim 1, wherein the two air pipes connected with the said oxygen storage tank are equipped with two check valves respectively.
10. An oxygen concentrator according to claim 1, wherein the connecting pipes connected with the said two molecular sieve tanks is equipped with a throttling orifice in the middle.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN98205049.6 | 1998-06-01 | ||
| CN 98205049 CN2345234Y (en) | 1998-06-01 | 1998-06-01 | Oxygenerator with pneumatic control chang-pressure adsorptive process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2266228A1 true CA2266228A1 (en) | 1999-12-01 |
Family
ID=5233780
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2266228 Abandoned CA2266228A1 (en) | 1998-06-01 | 1999-03-19 | A pneumatically controlled oxygen producer by pressure swing adsorption |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN2345234Y (en) |
| CA (1) | CA2266228A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107308529A (en) * | 2017-05-20 | 2017-11-03 | 广东欧格斯科技有限公司 | A kind of pulsed vacuum pressure swing adsorption machine and pulsed method for supplying oxygen |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1990086A (en) * | 2005-12-26 | 2007-07-04 | 肖永初 | Electric physical oxygen-making device |
| WO2021223154A1 (en) * | 2020-05-07 | 2021-11-11 | 雷激 | Ventilator |
| CN113694689A (en) * | 2021-08-28 | 2021-11-26 | 合肥雅美娜环境医疗设备有限公司 | Oxygenerator solenoid valve control structure and control system thereof |
| CN113877373B (en) * | 2021-09-14 | 2023-10-03 | 浙江凯斯泰克制造科技有限公司 | Modularized nitrogen making machine |
-
1998
- 1998-06-01 CN CN 98205049 patent/CN2345234Y/en not_active Expired - Lifetime
-
1999
- 1999-03-19 CA CA 2266228 patent/CA2266228A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107308529A (en) * | 2017-05-20 | 2017-11-03 | 广东欧格斯科技有限公司 | A kind of pulsed vacuum pressure swing adsorption machine and pulsed method for supplying oxygen |
Also Published As
| Publication number | Publication date |
|---|---|
| CN2345234Y (en) | 1999-10-27 |
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