Methods and apparatus to generate liquid ambulatory oxygen from an oxygen concentrator

• US 6,681,764 B1
• Filed: 06/29/1999
• Issued: 01/27/2004
• Est. Priority Date: 06/16/1997
• Status: Expired due to Term

• Current Assignee: Respironics Incorporated
• Original Assignee: Sequal Technologies Incorporated (Niterra Co., Ltd.), Teijin Limited
• Inventors: Walker, Graham, Honkonen, Scott C., Hill, Theodore B., Hill, Charles C.
• Primary Examiner(s): Lewis; Aaron J.
• Application Number:
  US09/343,149
• Time in Patent Office: 1,673 Days
• Field of Search: 62/606,615 165/110,174 128/200.24,201.21,204.15,204.17
• US Class Current: 128/201.21
• CPC Class Codes: A61M 2202/0007 introduced into the body
• CPC Class Codes: A61M 2202/0208 Oxygen
• CPC Class Codes: A61M 2202/03 Gases in liquid phase, e.g. cryogenic liquids
• CPC Class Codes: B01D 2253/108 Zeolites
• CPC Class Codes: B01D 2253/116 Molecular sieves other than zeolites
• CPC Class Codes: B01D 2256/12 Oxygen
• CPC Class Codes: B01D 2257/102 Nitrogen
• CPC Class Codes: B01D 2257/404 Nitrogen oxides other than dinitrogen oxide
• CPC Class Codes: B01D 2257/502 Carbon monoxide
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2257/80 Water
• CPC Class Codes: B01D 2259/40001 Methods relating to additional, e.g. intermediate, treatment of process gas
• CPC Class Codes: B01D 2259/40009 using sensors or gas analysers
• CPC Class Codes: B01D 2259/416 involving cryogenic temperature treatment
• CPC Class Codes: B01D 2259/4525 for storage and dispensing systems
• CPC Class Codes: B01D 2259/4533 for medical purposes
• CPC Class Codes: B01D 2259/4541 for portable use, e.g. gas masks
• CPC Class Codes: B01D 2259/455 for transportable use portable devices B01D2259/4541
• CPC Class Codes: B01D 5/0039 Recuperation of heat, e.g. use of heat pump(s), compression
• CPC Class Codes: B01D 53/0454 Controlling adsorption controlling temperature swing adsorption B01D53/0462, controlling pressure swing adsorption B01D53/047
• CPC Class Codes: B01D 53/047 : Pressure swing adsorption
• CPC Class Codes: B01D 53/053 : with storage or buffer vessel
• CPC Class Codes: B01D 53/261 : by adsorption
• CPC Class Codes: F17C 2201/058 : portable (<30 l)
• CPC Class Codes: F17C 2203/0391 : by vacuum
• CPC Class Codes: F17C 2205/0326 : electrically actuated
• CPC Class Codes: F17C 2205/0332 : Safety valves or pressure relief valves
• CPC Class Codes: F17C 2205/0341 : Filters
• CPC Class Codes: F17C 2221/011 : Oxygen
• CPC Class Codes: F17C 2223/0161 : cryogenic, e.g. LNG, GNL, PLNG
• CPC Class Codes: F17C 2227/0353 : using cryocooler
• CPC Class Codes: F17C 2227/04 : Methods for emptying or filling
• CPC Class Codes: F17C 2250/032 : using computers
• CPC Class Codes: F17C 2250/0408 : Level of content in the vessel
• CPC Class Codes: F17C 2250/043 : Pressure
• CPC Class Codes: F17C 2250/0439 : Temperature
• CPC Class Codes: F17C 2250/0452 : Concentration of a product
• CPC Class Codes: F17C 2260/02 : Improving properties related to fluid or fluid transfer
• CPC Class Codes: F17C 2265/015 : by separating
• CPC Class Codes: F17C 2270/025 : Breathing
• CPC Class Codes: F17C 2270/0509 : "Dewar" vessels
• CPC Class Codes: F17C 6/00 : Methods and apparatus for filling vessels not under pressure with liquefied or solidified gases
• CPC Class Codes: F25B 9/006 : the refrigerant containing more than one component F25B9/004 takes precedence
• CPC Class Codes: F25B 9/145 : pulse-tube cycle
• CPC Class Codes: F25J 1/0017 : Oxygen
• CPC Class Codes: F25J 1/0052 : by vaporising a liquid refrigerant stream
• CPC Class Codes: F25J 1/0212 : as a single flow MCR cycle
• CPC Class Codes: F25J 1/0225 : using other external refrigeration means not provided before, e.g. heat driven absorption chillers
• CPC Class Codes: F25J 1/0244 : Operation; Control and regulation; Instrumentation F25J1/0279 takes precedence
• CPC Class Codes: F25J 1/0276 : Laboratory or other miniature devices
• CPC Class Codes: F25J 2205/40 : using hybrid system, i.e. combining cryogenic and non-cryogenic separation techniques
• CPC Class Codes: F25J 2205/60 : using adsorption on solid adsorbents, e.g. by temperature-swing adsorption [TSA] at the hot or cold end
• CPC Class Codes: F25J 2205/80 : using membrane, i.e. including a permeation step
• CPC Class Codes: F25J 2210/40 : Air or oxygen enriched air, i.e. generally less than 30mol% of O2
• CPC Class Codes: F25J 2220/50 : Separating low boiling, i.e. more volatile components from oxygen, e.g. N2, Ar
• CPC Class Codes: F25J 2270/90 : External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
• CPC Class Codes: F25J 2270/91 : using pulse tube refrigeration
• CPC Class Codes: Y02C 20/40 : of CO2
• CPC Class Codes: Y02P 70/10 : Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Abstract

A control system for a home ambulatory liquid oxygen system having an oxygen concentrator, condenser, cryocooler, a heater and a storage dewar, includes an oxygen concentration sensor which senses the concentration of oxygen gas generated by the oxygen concentrator and generates a first signal in response thereto; a liquid level sensor which senses the liquid level in the dewar and generates a second signal in response thereto; a temperature sensor which senses the temperature in the dewar and generates a third signal in response thereto; and a microprocessor for receiving the first, second and third signals for computing the flow concentration of gaseous oxygen out of the concentrator and into the condenser, the level of liquid oxygen in the dewar, the temperature in the dewar and for controlling the transfer of liquid oxygen from the storage dewar.

Claims

1. A control system for a home ambulatory liquid oxygen system having an oxygen concentrator, condenser, cryocooler, a heater and a storage dewar, the control system comprising:

(a) an oxygen concentration sensor which senses the concentration of oxygen gas generated by the oxygen concentrator and generates a first signal in response thereto;

(b) a liquid level sensor which senses the liquid level in the dewar and generates a second signal in response thereto;

(c) a temperature sensor which senses the temperature in the dewar and generates a third signal in response thereto;

(d) a microprocessor for receiving the first, second and third signals for computing the flow concentration of gaseous oxygen out of the concentrator and into the condenser, the level of liquid oxygen in the dewar, the temperature in the dewar and for controlling the transfer of liquid oxygen from said storage dewar.

2. The control system in claim 1 wherein the microprocessor is located remotely from the home ambulatory system and connected to the sensors and controllers using a modem.

3. The control system in claim 1 wherein the microprocessor is located remotely from the home ambulatory system and connected to the sensors and controllers using a wireless interface.

4. The control system in claim 1 wherein the actual flow rate into the condenser is chosen to exceed the designed flow capacity of the condenser allowing the excess flow to purge the system.

5. The liquid oxygen system of claim 1 wherein only 20 to 90% of the incoming flow into the condenser is condensed to minimize the liquefaction of argon, nitrogen and trace gases.

6. The apparatus of claim 1 wherein the controller controls condenser parameters so that the condenser temperature varies in the range from approximately 69.2 to 109.7 K, the condenser pressure varies from approximately 5 to 65 psia, and the concentrations of gas into the condenser varies approximately as follows:

oxygen;

80 to 100%

nitrogen;

0 to 20%

argon;

0 to 7%.

7. An ambulatory liquid oxygen system where liquid oxygen is formed from gaseous oxygen obtained from an oxygen concentrator comprising:

(a) an oxygen concentrator which separates oxygen gas from the air line;

(b) a first output line from said oxygen concentrator for delivering oxygen gas from said concentrator;

(c) a first valve placed in said first output line to control the output flow of oxygen;

(d) a condenser in cooperation with a cryocooler for providing cooling for said condenser;

(e) a second output line in communication between the first valve and the condenser for delivering the oxygen gas from the concentrator output to the condenser for cooling to form liquid oxygen;

(f) a storage dewar for storing liquid oxygen liquefied by the condenser;

(g) a third output line in communication between said condenser and storage dewar for delivering liquid oxygen from the condenser to the storage dewar;

(h) a heater for heating liquid oxygen in said dewar;

(i) an oxygen sensor to measure the oxygen concentration of flow from said concentrator;

(j) a liquid level sensor in said dewar;

(k) a temperature sensor in said dewar;

(l) a pressure sensor in communication with said dewar; and

(m) a controller for receiving output from the oxygen sensor, liquid level sensor, temperature sensor and pressure sensor, and for controlling the flow of input gaseous oxygen to the condenser and for controlling liquefaction and transfer from the storage dewar in accordance with the sensed conditions.

8. The system of claim 7 wherein the oxygen concentrator is of the Pressure Swing Adsorption (“

PSA”

) type.

9. The system of claim 7 wherein the condenser parameters are maintained as follows:

temperature from approximately 69.2 to 109.7 K;

pressure from approximately 5 to 65 psia;

gas concentrations into condenser;

oxygen from approximately 80 to 100%,

nitrogen from approximately 0 to 20%, and

argon from approximately 0 to 7%.

10. The system of claim 7 further comprising a recuperator between the oxygen concentrator and condenser for pre-cooling the flow of gas into the condenser.

11. The liquid oxygen system of claim 7 wherein the flow rate into the condenser is chosen to exceed the designated capacity of the condenser.

12. The liquid oxygen system of claim 7 wherein only 20 to 90% of the incoming flow to the condenser is condensed to minimize the liquefaction argon, nitrogen and trace gases.

13. The liquid oxygen system of claim 7 wherein the generally vertically oriented, gravity assisted condenser is in contact with the cryocooler and comprises:

(a) an inlet for receiving gaseous oxygen;

(b) an outer tubular member;

(c) an inner member;

(d) a passage defined by said outer and inner members;

(e) said inner member having axial slots cut into its outer surface;

(f) means for circulating said oxygen in said passage; and

(g) an outlet for releasing liquid oxygen,

wherein when said oxygen gas enters said condenser at said inlet and passes through said passage, condensation takes place causing a transition from gas to liquid phase.

14. The liquid oxygen system of claim 7 where the generally vertically oriented, gravity assisted, condenser comprises:

(a) an inlet for receiving a stream of oxygen;

(b) an outer member;

(c) an inner member;

(d) passage defined by said inner and outer members;

(e) the inner member having axial slots to enhance heat transfer and to avoid liquid film build-up; and

(f) an outlet for the oxygen which is liquefied.

15. The liquid oxygen system in claim 7 wherein the controller is located remotely from the oxygen generator.

16. The liquid oxygen system in claim 7 wherein the controller monitors the oxygen concentration and amount of liquid oxygen and controls the parameters of liquid oxygen generation and transfer remotely using a modem.

17. The liquid oxygen system in claim 7 wherein the controller monitors the oxygen concentration and amount of liquid oxygen and controls the parameters of liquid oxygen generation and transfer remotely using a wireless interface.

18. A method for controlling an ambulatory oxygen generator and oxygen liquefier having an oxygen concentrator, a condenser, a storage dewar and a controller comprising the following steps:

(a) generating a gaseous supply of oxygen using the oxygen concentrator for supplying oxygen to a patient;

(b) splitting off a portion of the gaseous supply to be liquefied;

(c) cooling said split-off supply of oxygen using the condenser to transform the oxygen from gaseous phase to liquid phase;

(d) storing the liquid oxygen in the storage dewar;

(e) sensing a concentration of oxygen being supplied by the oxygen concentrator, the level of liquid oxygen in said dewar and the temperature and pressure in said dewar; and

(f) the controller calculating conditions and controlling the operation of the above system to allow for liquefaction and operative transfer of liquid oxygen to a portable dewar.

19. A method for controlling a home ambulatory liquid oxygen system comprised of an oxygen generator, a controller having a microprocessor, a condenser, a cryocooler and a storage dewar, where all or only a portion of the oxygen flow is utilized for liquefaction, comprising:

(a) providing the microprocessor with a database and control functions;

(b) sensing the parameters relating to the concentration and supply of gaseous oxygen, the level of liquid oxygen in the dewar, and the pressure of the condenser;

(c) providing the microprocessor with these sensed parameters and having the microprocessor calculate optimal conditions;

(d) controlling servomechanisms to regulate the system so that optimal conditions are realized as a function of said calculations.

20. A controller for a home ambulatory liquid oxygen system having a computer, an oxygen concentrator, condenser, and storage dewar comprising:

(a) means for sensing the oxygen pressure of flow out of the concentrator;

(b) means for sensing the oxygen concentration of flow out of the concentrator;

(c) means for sensing the liquid level in the dewar;

(d) means for sensing flow parameters at the condenser;

(e) means for sensing the temperature at the dewar;

(f) means for controlling input of gaseous oxygen to the condenser;

(g) means for initiating and controlling the output of liquid oxygen from the storage dewar;

(h) a programmable control means coupled to each means for sensing, said programmable control means to be used for storing at least one required input/output control schedule, for processing the inputted signals and for actuating one or more control means.

21. A system for liquefying oxygen utilizing an oxygen concentrator, condenser, cryocooler and storage dewar comprising:

(a) a first flow control means for channeling off gaseous fluid flow from an oxygen concentrator;

(b) a second flow control means for advancing said gaseous fluid to a condenser;

(c) means for cooling said condenser to change the phase of said oxygen flow from gas to liquid;

(d) a conduit for transferring the liquid oxygen from the condenser to a storage dewar;

(e) a third flow control means for advancing the flow of liquid oxygen out of the storage dewar;

(f) a controller for sensing the oxygen concentration of flow into the condenser, for sensing the liquid level in the storage dewar, and for controlling said first, second, and third flow control means;

(g) programmable control means in said controller coupled to each of said flow control means, for storing flow delivery and liquefaction parameters for use by the controller in optimizing liquefaction of oxygen.

22. The liquid oxygen system of claim 21 wherein the flow rate into the condenser is controlled to exceed the capacity of the condenser.

23. The liquid oxygen system of claim 21 wherein only 20 to 90% of the incoming flow to the condenser is condensed to minimize the liquefaction argon, nitrogen and trace gases.

24. The liquid oxygen system of claim 21 wherein contact with a cryocooler for use in liquefying oxygen comprises:

(a) an inlet for receiving gaseous oxygen;

(b) an outer tubular member;

(c) a generally vertically oriented inner member;

(d) a passage defined by said outer and inner members;

(e) said generally vertically oriented inner member having axial slots cut into its outer surface;

(f) means for circulating said oxygen in said passage; and

(g) an outlet for releasing liquid oxygen;

wherein when said oxygen gas enters said condenser at said inlet and passes through said passage, condensation takes place causing a transition from gas to liquid phase.

25. The liquid oxygen system of claim 21 where the generally vertically oriented, gravity assisted condenser for use in liquefaction of oxygen from its gaseous to its liquid phase and for use with a cryocooler comprises:

(a) an inlet for receiving a stream of oxygen;

(b) an outer member;

(c) an inner member;

(d) passage defined by said inner and outer members;

(e) the inner member having axial slots to enhance heat transfer and to avoid liquid film build-up

(f) an outlet for the oxygen which is liquefied.

26. A home liquefaction system including an oxygen concentrator, controller with a programmable control means, condenser, cryocooler and storage dewar comprising:

(a) an oxygen concentrator which separates oxygen gas from the air;

(b) a first flow line from said oxygen concentrator for delivering oxygen gas from said concentrator;

(c) a first valve placed in said first flow line to control the output flow of oxygen;

(d) a condenser in cooperation with a cryocooler for providing cooling for said condenser;

(e) a second flow line in communication between the first valve and the condenser for delivering the oxygen gas from the concentrator output to the condenser for cooling to form liquid oxygen;

(f) a storage dewar for storing liquid oxygen liquefied by the condenser;

(g) a third flow line in communication between said condenser and storage dewar for delivering liquid oxygen from the condenser to the storage dewar;

(h) a heater for heating liquid oxygen in said dewar;

(i) an oxygen sensor to measure the oxygen concentration of flow from said concentrator;

(j) a liquid level sensor in said dewar;

(k) a temperature sensor in said dewar;

(l) a pressure sensor for sensing pressure in said dewar;

(m) a second valve for regulating flow of liquid oxygen from said dewar;

(n) a controller for receiving output from the oxygen sensor, liquid level sensor, temperature sensor and pressure sensor, and having means for storing at least one parameter from the Optimum Liquefaction Schedule, for controlling the flow of input gaseous oxygen to the condenser, and for optimizing liquefaction and transfer from the storage dewar in accordance with the sensed conditions.

27. The apparatus of claim 26 wherein said programmable control means including means for storing information relating to optimum condenser parameters and for displaying an indicium of the modes of operation prior to activating any of said flow control means.

28. A system as in claim 26 wherein said programmable control means includes means for scheduling intermittent actuation of one or more of said valves so as to permit the system to be operated in accordance with the Optimum Liquefaction Schedule.

29. A system as in claim 26 including means for adjusting actuation of selected flows and conditions so as to optimize condenser parameters in response to said programmable control means and Optimum Liquefaction Schedule.

30. A system as in claim 26 including means for visually displaying controller parameters.

31. A system in claim 26 including means for transferring said liquid oxygen from said storage dewar to the delivery port at a controllable rate and including means to actuate said means in accordance with a predetermined Optimum Liquefaction Schedule.

32. An oxygen liquefaction system utilizing a concentrator to increase the oxygen concentration of an oxygen enriched product gas comprising:

(a) a first output line for transporting said product gas from said concentrator;

(b) a first valve for selectively withdrawing all or a portion of said product gas from said conduit to be liquefied;

(c) flow rate sensor independent of said first valve for sensing the rate of withdrawal of the product gas from said conduit to be liquefied and for communicating the sensed rate of withdrawal of said product gas to a modem;

(d) an oxygen sensor for sensing the oxygen concentration in said oxygen enriched product gas selectively withdrawn for liquefaction and for communicating the sensed oxygen concentration in said product gas to a first modem;

(e) a condenser for receiving the product gas withdrawn from said first flow control means;

(f) a second output line from said first flow control means oxygen concentrator for delivering oxygen gas from said concentrator for a first use;

(g) a second flow rate sensor in said second output line;

(h) a second oxygen sensor in said second output line;

(i) a cryocooler for providing cooling for said condenser;

(j) a storage dewar for storing liquid oxygen liquefied by the condenser;

(k) a third output line in communication between said condenser and storage dewar for delivering liquid oxygen from the condenser to the storage dewar;

(l) a heater for heating liquid oxygen in said dewar;

(m) a liquid level sensor for sensing the level in said dewar;

(n) a temperature sensor for sensing the temperature in said dewar;

(o) a pressure sensor for sensing the pressure in said dewar;

(p) a second modem for receiving quantitative signals communicated from said flow rate sensing means and said oxygen sensing means and for transmitting said signals to a remote controller; and

(q) a remote controller in telephonic communication with said first and second modems for receiving transmitted signals from said modems and having means for displaying the liquefaction parameters in the liquefaction process.

33. The oxygen liquefaction system of claim 32 wherein the concentrator increases the oxygen concentration of an oxygen enriched product gas recovered therefrom using a plurality of molecular sieve beds for receiving atmospheric air for selectively adsorbing nitrogen therefrom, an electric motor driven compressor including means for providing line voltage for operating said compressor, and a valve cooperating with said compressor for alternately charging said sieve beds with atmospheric air and timing means for switching said valve to alternately charge said sieve beds according to a timing cycle.

34. The oxygen liquefaction system of claim 32 wherein said flow rate sensors comprise a pressure transducer for measuring product gas pressure therein.

35. The system of claim 34 including a microprocessor cooperating with said pressure transducers and having means for determining the rate of flow of product gas into the condenser in response to pressure sensings therein.

36. The system of claim 35 wherein said test apparatus includes visual display means for displaying the product gas flow rate and the oxygen concentration into the condenser and the pressure and temperature in the storage dewar.

37. The system of claim 32 wherein said remote control apparatus includes means for selectively signaling said modem to transmit said signals from said liquefaction apparatus.

38. The system of claim 32 including a microprocessor having means for receiving the sensed rate of product gas withdrawal and oxygen concentration in said product gas from said oxygen sensor, the pressure, temperature, and liquid level in the storage dewar, and having memory means provided with minimum selected parameters at different conditions, means for comparing the sensed parameters with the minimum selected parameters, and means for signaling said modem to transmit said signals to said controller when said sensed parameters fall below said minimum selected parameters.

39. The oxygen concentrator of claim 38 wherein said first modem is connected to said microprocessor and said second remote modem is connected to said controller at a remote location, and wherein said modems are in telephonic communication.

40. The concentrator of claim 37 wherein said microprocessor includes means for signaling said first modem to transmit said signals to said controller when said sensed oxygen concentration or liquefaction falls below said minimum selected parameters.

41. The apparatus of claim 40 wherein said microprocessor cooperates with said first means and said second means and wherein said controller includes selective digital display means for displaying liquefaction parameters.

42. The system in claim 40 wherein the entry system not including the oxygen concentrator weighs no more than about 60 pounds and takes up less than about six cubic feet of volume.

43. An ambulatory liquid oxygen system where liquid oxygen is formed from gaseous oxygen obtained from an oxygen concentrator comprising:

(a) an oxygen concentrator which separates oxygen gas from the air;

(b) a first output means from said oxygen concentrator for delivering oxygen gas from said concentrator;

(c) a first valve placed in said first output means to control the output flow of oxygen;

(d) a condenser in cooperation with a cryocooler for providing cooling for said condenser;

(e) a second output line in communication between the first valve and the condenser for delivering the oxygen gas from the concentrator output to the condenser for cooling to form liquid oxygen;

(f) a storage dewar for storing liquid oxygen liquefied by the condenser;

(g) a third output line in communication between said condenser and storage dewar for delivering liquid oxygen from the condenser to the storage dewar;

(h) a heater for heating liquid oxygen in said dewar;

(i) an oxygen sensor to measure the oxygen concentration of flow from said concentrator;

(j) a liquid level sensor in said dewar;

(k) a temperature sensor in said dewar;

(l) a pressure sensor in communication with said dewar;

(m) a controller for receiving output from the oxygen sensor, liquid level sensor, temperature sensor and pressure sensor, and for controlling the flow of input gaseous oxygen to the condenser and for optimizing liquefaction and transfer from the storage dewar in accordance with the sensed conditions.

44. An ambulatory home oxygen concentrator liquefaction system comprising:

(a) an oxygen concentrator which can isolate oxygen gas from the air;

(b) a first output means from the concentrator to channel the oxygen which is isolated;

(c) a second means to split off all or a portion of the gaseous oxygen from the output means of said concentrator for liquefaction;

(d) a condenser which can cause gaseous oxygen to change phase into liquid oxygen;

(e) means to channel the oxygen stream from said output means to a condenser;

(f) means to liquefy said oxygen stream in said condenser using a cryocooler;

(g) means to collect the condensed liquid oxygen using a dewar;

(h) wherein said dewar includes a heater which can be used to effectuate the transfer of liquid oxygen from the dewar for storing a quantity of liquid oxygen from which smaller quantities can be transferred for moveable oxygen treatment.

45. A system for liquefying oxygen utilizing an oxygen concentrator, condenser, cryocooler and storage dewar comprising:

(a) a first flow control means for channeling off gaseous fluid flow from an oxygen concentrator;

(b) a second flow control means for advancing said gaseous fluid to a condenser;

(c) means for cooling said condenser to change the phase of said oxygen flow from gas to liquid;

(d) a conduit for transferring the liquid oxygen from the condenser to a storage dewar;

(e) a third flow control means for advancing the flow of liquid oxygen out of the storage dewar;

(f) a controller for sensing the oxygen concentration of flow into the condenser, for sensing the liquid level in the storage dewar, and for controlling said first, second, and third flow control means;

(g) programmable control means in said controller coupled to each of said flow control means, for storing flow delivery and liquefaction parameters for use by the controller in optimizing liquefaction of oxygen.