|Publication number||USRE43398 E1|
|Application number||US 11/366,986|
|Publication date||May 22, 2012|
|Filing date||Mar 1, 2006|
|Priority date||Jun 16, 1997|
|Publication number||11366986, 366986, US RE43398 E1, US RE43398E1, US-E1-RE43398, USRE43398 E1, USRE43398E1|
|Inventors||Scott C. Honkonen, Theodore B. Hill, Charles C. Hill, Graham Walker|
|Original Assignee||Respironics, Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (227), Non-Patent Citations (3), Referenced by (17), Classifications (55), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a continuation-in-part of U.S. patent application Ser. No. 08/876,970, filed Jun. 16, 1997 now U.S. Pat. No. 5,979,440.
The field of this invention relates to using an oxygen concentrator to create a portable supply of supplementary oxygen for ambulatory respiratory patients so that they can lead normal and productive lives—as the typical primary oxygen sources are too bulky to carry or require excessive power to operate.
There is a burgeoning need for home and ambulatory oxygen. Supplemental oxygen is necessary for patients suffering from lung disorders; for example, pulmonary fibrosis, sarcoidosis, or occupational lung disease. For such patients, oxygen therapy is an increasingly beneficial, life-giving development. While not a cure for lung disease, supplemental oxygen increases blood oxygenation, which reverses hypoxemia. This therapy prevents long-term effects of oxygen deficiency on organ systems—in particular, the heart, brain and kidneys. Oxygen treatment is also prescribed for Chronic Obstructive Pulmonary Disease (COPD), which afflicts about 25 million people in the U.S., and for other ailments that weaken the respiratory system, such as heart disease and AIDS. Supplemental oxygen therapy is also prescribed for asthma and emphysema.
The normal prescription for COPD patients requires supplemental oxygen flow via nasal cannula or mask twenty four hours per day. The average patient prescription is two liters per minute of high concentration oxygen to increase the oxygen level of the total air inspired by the patient from the normal 21% to about 40%. While the average oxygen flow requirement is two liters per minute, the average oxygen concentrator has a capacity of four to six liters of oxygen per minute. This extra capacity is occasionally necessary for certain patients who have developed more severe problems but they are not generally able to leave the home (as ambulatory patients) and do not require a portable oxygen supply.
There are currently three modalities for supplemental medical oxygen: high pressure gas cylinders, cryogenic liquid in vacuum insulated containers or thermos bottles commonly called “dewars,” and oxygen concentrators. Some patients require in-home oxygen only while others require in-home as well as ambulatory oxygen depending on their prescription. All three modalities are used for in-home use, although oxygen concentrators are preferred because they do not require dewar refilling or exchange of empty cylinders with full ones.
Only small high pressure gas bottles and small liquid dewars are portable enough to be used for ambulatory needs (outside the home). Either modality may be used for both in-home and ambulatory use or may be combined with an oxygen concentrator which would provide in-home use.
As we describe below, the above-described current methods and apparatus have proven cumbersome and unwieldy and there has been a long-felt need for improved means to supply the demand for portable/ambulatory oxygen.
For people who need to have oxygen but who need to operate away from an oxygen-generating or oxygen-storage source such as a stationary oxygen system (or even a portable system which cannot be easily carried), the two most prescribed options generally available to patients are: (a) to carry with them small cylinders typically in a wheeled stroller; and (b) to carry portable containers typically on a shoulder sling. Both these gaseous oxygen and liquid oxygen options have substantial drawbacks. But from a medical view, both have the ability to increase the productive life of a patient.
The major drawback of the gaseous oxygen option is that the small cylinders of gaseous oxygen can only provide gas for a short duration. Oxygen conserving devices that limit the flow of oxygen to the time of inhalation may be used. However, the conserving devices add to the cost of the service and providers have been reluctant to add it because there often is no health insurance reimbursement. Indeed, the insurance reimbursement for medical oxygen treatment appears to be shrinking.
Another drawback of the gaseous oxygen option is the source of or refill requirement for oxygen once the oxygen has been depleted from the cylinder. These small gas cylinders must be picked up and refilled by the home care provider at a specialized facility. This requires regular visits to a patient's home by a provider and a substantial investment in small cylinders for the provider because so many are left at the patient's home and refilling facility. Although it is technically possible to refill these cylinders in the patient's home using a commercial oxygen concentrator that extracts oxygen from the air, this task would typically require an on-site oxygen compressor to boost the output pressure of the concentrator to a high level in order to fill the cylinders. Additionally, attempting to compress the oxygen in pressurized canisters in the home is dangerous, especially for untrained people. This approach of course presents several safety concerns for in-home use. For example, in order to put enough of this gas in a portable container, it must typically be compressed to high pressure (˜2000 psi). Compressing oxygen from 5 psi (the typical output of an oxygen concentrator) to 2000 psi will produce a large amount of heat. (Enough to raise the temperature 165° C. per stage based on three adiabatic compression stages with intercooling.) This heat, combined with the oxygen which becomes more reactive at higher pressures, sets up a potential combustion hazard in the compressor in the patient's home. Thus, utilizing and storing a high pressure gas system in the patient's home is dangerous and not a practical solution.
The convenience and safety issues are not the only drawbacks of this compressed oxygen approach. Another drawback is that the compressors or pressure boosters needed are costly because they require special care and materials needed for high pressure oxygen compatibility. For example, a Rix Industries, Benicia, Calif., ⅓ hp unit costs about $10,000 while a Haskel International, Burbank, Calif., air-powered booster costs about $2200 in addition to requiring a compressed air supply to drive it. Litton Industries and others also make oxygen pressure boosters.
Turning now to the liquid oxygen storage option, its main drawback is that it requires a base reservoir—a stationary reservoir base unit about the size of a standard beer keg—which has to be refilled about once a week. The liquid oxygen can then be obtained from a base unit and transferred to portable dewars which can be used by ambulatory patients. Also, with the liquid oxygen option, there is substantial waste, as a certain amount of oxygen is lost during the transfer to the portable containers and from evaporation. It is estimated that 20% of the entire contents of the base cylinder will be lost in the course of two weeks because of losses in transfer and normal evaporation. These units will typically boil dry over a period of 30 to 60 days even if no oxygen is withdrawn.
There are other complications. Typically, supplemental oxygen is supplied to the patient by a home care provider, in exchange for which it receives a fixed monetary payment from insurance companies or Medicare regardless of the modality. Oxygen concentrators for use in the home are preferred and are the least expensive option for the home care provider. For outside the home use however, only small high pressure gas bottles and small liquid dewars are portable enough to be used for ambulatory needs. One of these two modalities may be used for both in-home and ambulatory use or may be combined with an oxygen concentrator which would provide in-home use. In either case, the home care provider must make costly weekly or biweekly trips to the patient's home to replenish the oxygen. One of the objects of this invention is to eliminate these costly “milk runs.”
Portable oxygen concentrators are commercially available for providing patients with gaseous oxygen. These devices are “portable” solely in the sense that they can be carried to another point of use such as in an automobile or in an airplane. At present, there are no home oxygen concentrators commercially available that can provide liquid oxygen. One type of medical oxygen concentrator takes in air and passes it through a molecular sieve bed, operating on a pressure swing adsorption cycle, which strips most of the nitrogen out, producing a stream of ˜90% oxygen, for example, as shown in U.S. Pat. Nos. 4,826,510 and 4,971,609 (which are incorporated herein by reference). While, as set out in the Information Disclosure Statement, complex oxygen liquefaction systems have been disclosed for use by the military in jet aircraft, and while large-scale commercial plants have been disclosed, this technology has not yet found its way into the home to help individual patients and to benefit the general public. A truly portable oxygen concentrator has not yet been perfected and this event is unlikely, at least in the near future, because the power requirements are too large to be provided by a lightweight battery pack.
Since liquid oxygen requires periodic delivery and home oxygen concentrators are not commercially available that would create liquid oxygen, there has existed a long-felt need for a device or method having the capability to concentrate oxygen from the air, liquefy it, and transfer it into portable dewars in a home environment, and for a home oxygen concentrator unit which allows excess flow capacity from the concentrator to be stored by either compression or liquefaction for later use.
An aspect of the present invention involves a home liquid oxygen ambulatory system for supplying a portable supply of oxygen, where a portion of the gaseous oxygen output obtained from an oxygen concentrator is condensed into liquid oxygen. The system includes an oxygen concentrator which separates oxygen gas from the ambient air, a condenser in communication with the oxygen concentrator for receiving and liquefying the oxygen gas flow, a cryocooler associated with the condenser, and a first storage dewar in fluid communication with the condenser and adapted to store the oxygen liquefied by the condenser, the first storage dewar including means for transferring liquid oxygen from the first dewar to a second dewar for storing a quantity of oxygen suitable for moveable oxygen treatment.
In an embodiment of the above aspect of the invention, the liquid oxygen transferring means is adapted to increase the pressure in the first dewar.
In a further embodiment of the above aspect of the invention, the liquid transferring means includes a heater immersed within the liquid oxygen in the first dewar.
In a still further embodiment of the above aspect of the invention, the first dewar includes an inner vessel in which the liquid oxygen reside, and liquid transferring means includes a heater attached to the outer surface of inner vessel.
In another embodiment of the above aspect of the invention, the condenser is in communication with the concentrator through a line, and the liquid transferring means includes a compressor located in the line between the condenser and the concentrator.
In an additional embodiment of the above aspect of the invention, the liquid transferring means includes a high-pressure compressor in communication with the concentrator for delivering high-pressure air thereto.
In another embodiment of the above aspect of the invention, the liquid transferring means includes a vaporizer loop associated with the first dewar.
In a further embodiment of the above aspect of the invention, the liquid transferring means includes a controllable heat leak associated with the first dewar.
In a still further embodiment of the above aspect of the invention, the liquid transferring means includes a gravity-assisted dispensing mechanism.
In an additional embodiment of the above aspect of the invention, the system further includes the second storage dewar and the second storage dewar is adapted to be filled at a pressure below 20 psig.
An additional aspect of the invention involves a home liquid oxygen ambulatory system for supplying a portable supply of oxygen, where a portion of the gaseous oxygen output obtained from an oxygen concentrator is condensed into liquid oxygen. The system includes an oxygen concentrator which separates oxygen gas from the ambient air, a condenser in communication with the oxygen concentrator for receiving and liquefying the oxygen gas flow, a cryocooler associated with the condenser, and a portable dewar adapted to interface with the condenser and adapted to store the oxygen liquefied by the condenser.
Another aspect of the present invention involves a method for generating liquid oxygen in a home from a home liquid oxygen ambulatory system having an oxygen concentrator, a condenser, and cryocooler, a storage dewar and means for transferring liquid oxygen from the first dewar to a second dewar. The method includes generating a gaseous supply of oxygen using the oxygen concentrator; splitting off at least a portion of the gaseous supply to be liquefied; cooling the supply of oxygen using the condenser and cryocooler to transform the gaseous oxygen to liquid oxygen; storing the liquid oxygen in the storage dewar; and transferring the liquid oxygen in the storage dewar with the liquid oxygen transferring means to a second dewar for storing a quantity of liquid oxygen from which smaller quantities can be transferred for moveable oxygen treatment.
In an embodiment of the above aspect of the invention, transferring the liquid oxygen includes increasing the pressure in the first dewar.
In an additional embodiment of the above aspect of the invention, the liquid transferring means includes a heater immersed within the liquid oxygen in the first dewar and transferring the liquid oxygen includes heating the liquid oxygen in the first dewar so that the pressure is increased in the first dewar.
In another embodiment of the above aspect of the invention, the first dewar includes an inner vessel in which the liquid oxygen reside, the liquid transferring means includes a heater attached to the outer surface of inner vessel, and transferring the liquid oxygen includes heating the liquid oxygen in the first dewar so that the pressure is increased in the first dewar.
In a further embodiment of the above aspect of the invention, the condenser is in communication with the concentrator through a line, and the liquid transferring means includes a compressor located in the line between the condenser and the concentrator, and transferring the liquid oxygen includes increasing the pressure of gaseous oxygen entering the condenser and the dewar with the compressor.
In a still further embodiment of the above aspect of the invention, the liquid transferring means includes a high-pressure compressor in communication with the concentrator for delivering high-pressure air thereto, and transferring the liquid oxygen includes increasing the pressure of gaseous oxygen entering the condenser and the dewar with the compressor.
In an additional embodiment of the above aspect of the invention, the liquid transferring means includes a vaporizer loop associated with the first dewar, and transferring the liquid oxygen includes heating the liquid oxygen in the first dewar with the vaporizer loop so that the pressure is increased in the first dewar.
In another embodiment of the above aspect of the invention, the liquid transferring means includes a controllable heat leak associated with the first dewar, and transferring the liquid oxygen includes heating the liquid oxygen in the first dewar so that the pressure is increased in the first dewar.
In a further embodiment of the above aspect of the invention, the liquid transferring means includes a gravity-assisted dispensing mechanism.
In a still further embodiment of the above aspect of the invention, the system further includes the second storage dewar, the second storage dewar is adapted to filled at a pressure below 20 psig.
Another aspect of the present invention involves a liquefier for a home liquid oxygen ambulatory system that is resistant to plugging. The home liquid oxygen ambulatory system includes an oxygen concentrator for delivering gaseous flow to the liquefier and a storage dewar having an inner vessel for storing liquid oxygen produced by the liquefier. The liquefier includes a condenser, a refrigerating device associated with the condenser, means for communicating incoming gaseous flow from the oxygen concentrator to the condenser, the communicating means having an inner surface with a dimension D, means for venting gaseous flow not condensed from the inner vessel, the venting means having an outer surface with an dimension d, and whereby the dimension D of the inner surface of the communicating means is significantly larger than the dimension d of the outer surface of the venting means to allow for the build-up of solid contaminants on the outer surface of the venting means without plugging up the communicating means.
In an embodiment of the above aspect of the invention, the venting means includes a recuperator comprised of a helical coil of tubing, the tubing having the outer surface with a diameter of the dimension d, whereby the incoming gas stream flows over the outer surface of the helical coil of tubing and a vent stream flows inside the helical coil of tubing.
In another embodiment of the above aspect of the invention, the outer surface of the helical coil of tubing has a cold surface to freeze out trace impurities of solid contaminants such as H2O, CO2 and hydrocarbons.
In a further embodiment of the above aspect of the invention, the communicating means is comprised of a neck tube having the inner surface with a diameter of the dimension D.
In a still further embodiment of the above aspect of the invention, the liquefier further includes a liquid withdrawal tube located central to the refrigerating device, recuperator and condenser for removing liquid oxygen from the storage dewar.
In an additional embodiment of the above aspect of the invention, the refrigerating device is integral with the condenser.
In another embodiment of the above aspect of the invention, the refrigerating device, condenser and recuperator are integral with the storage dewar.
Another aspect of the invention involves a method for generating liquid oxygen in a home from a home liquid oxygen ambulatory system having an oxygen concentrator, a condenser, a cryocooler, a recuperator and a storage dewar. The method includes generating a gaseous supply of oxygen, which includes some trace impurities, using the oxygen concentrator; splitting off at least a portion of the gaseous supply to be liquefied; cooling the supply of oxygen using the condenser and cryocooler to transform the gaseous oxygen to liquid oxygen; condensing less than all of the gaseous oxygen supply flowing into the condenser; freezing out the trace impurities of the gaseous supply of oxygen and venting the non-condensed nitrogen, argon and oxygen with the recuperator; storing the liquid oxygen in the storage dewar; and periodically removing accumulated frozen impurities on the recuperator by boiling-off any stored liquid oxygen and then flow purging the system until the system has reached room temperature.
Another aspect of the invention involves a generally vertically oriented, gravity assisted condenser for use with a refrigerating device to liquefy gaseous oxygen in a home liquid oxygen ambulatory system. The condenser includes a generally vertically oriented tubular member adapted to conduct heat axially to the refrigerating device, the tubular member having outer and inner surfaces, at least one of the outer and inner surfaces having a plurality of generally vertically oriented flutes and convex fins adapted to increase the condensation rate per unit area by thinning the liquid film and drain the condensate to keep the condensate from flooding the condensation surfaces.
In an embodiment of the above aspect of the invention, the fins have a hyperbolic cosine profile.
In an additional embodiment of the above aspect of the invention, the flutes have a profile selected from the group consisting of concave, generally V-shaped, generally rectilinear.
In another embodiment of the above aspect of the invention, the plurality of generally vertically oriented flutes and convex fins are located on both the outer and inner surfaces.
Another aspect of the invention involves a generally vertically oriented, gravity assisted condenser for use with a refrigerating device to liquefy gaseous oxygen in a home liquid oxygen ambulatory system. The condenser includes a generally vertically oriented tubular member adapted to conduct heat axially to the refrigerating device, the tubular member having outer and inner surfaces, at least one of the outer and inner surfaces includes means for enhancing the condensation rate per unit area by maintaining a small liquid film thickness on the condensation surfaces.
In an embodiment of the above aspect of the invention, the condensation enhancing means includes a plurality of generally vertically oriented flutes and convex fins.
In an additional embodiment of the above aspect of the invention, the fins have a hyperbolic cosine profile.
In a further embodiment of the above aspect of the invention, the flutes have a profile selected from the group consisting of concave, generally V-shaped, generally rectilinear.
In a still further embodiment of the above aspect of the invention, the plurality of generally vertically oriented flutes and convex fins are located on both the outer and inner surfaces.
A flow chart of the preferred embodiment of the invention is set out in
Controller 16 may be equipped with a microprocessor, adequate memory, software and ancillary equipment comprising a computer which can be used to monitor and control the operation of the system. The controller 16 may be provided with signals from liquid level sensor 17, oxygen sensor 18, pressure transducer 9, and temperature sensor 10 via lines 53, 59, 55 and 56, respectively. These signals are sensed and processed by the computer, with the controller operating valve 19, valve 25, heater 21, and cryocooler 12, in accordance with predetermined programs.
The controller also provides output indicators for the patient. The liquid level in the dewar is continuously displayed and the patient is alerted when the oxygen concentration is low and when the system is ready for them to transfer liquid to a portable dewar. A modem or wireless link may be included to enable remote monitoring of the key parameters of the system by the home care provider as well as information which is useful for repair, maintenance, billing, and statistical studies of patients for the medical oxygenation market. Key system parameters of interest include the number of liquid transfers performed, the oxygen concentration history, number of run hours on the cryocooler, and time of the last boil-dry as well as number of boil dries performed. The controller may include a computer and/or a microprocessor located either integrally with the liquefaction system claimed herein or remotely therefrom but in communication therewith using either a modem and telephone lines or with a wireless interface. The computer and/or microprocessor may include memory having a database, or may be remotely connected to a memory or database using a network. An Optimal Liquefaction Schedule for optimal operation of the liquefaction system is set out in
Dewar 14 is equipped with a dip tube 20 and heater 21. Heater 21 is used to build pressure in the dewar in order to expel liquid out the dip tube 20 when so desired. A quick disconnect valve 22 or other flow control means is located on the end of the dip tube. This allows connection of a portable LOX dewar 23, which can then be carried by the patient requiring a mobile/ambulatory supply of oxygen.
In another embodiment of this system shown in
In operation, in the preferred embodiment of
Even though 88% oxygen is adequate as supplemental oxygen therapy, if this was liquefied, as will be described below, the initial revaporized stream may have a reduced oxygen content because of the close boiling points of the components of the mixture. The temperature of the split gas stream entering the recuperator 15 is about room temperature. It is cooled to about 270 K (or colder) by the vent gas from the dewar flowing through the other side of the recuperator via line 52. The recuperator 15 reduces the load on the cryocooler by using the cold vent gas to pre-cool the oxygen-rich gas stream flowing into the condenser 13. From the recuperator 15 the high oxygen concentration stream flows through a line 57 to the condenser 13, which is cooled to ˜90 K by the cryocooler 12.
The condenser 13 provides cold surfaces to further cool and condense the flow. It is important to note that the gas passing through the condenser 13 is a mixture of oxygen, argon, and nitrogen. The normal boiling points of these components are: 90.18 K, 87.28 K, and 77.36 K respectively. Because of the close boiling points of the components of this mixture, there was initial skepticism because of the concern that all the nitrogen and argon would condense along with the oxygen. If this concern was realized, when this liquid mixture was revaporized, the lower boiling point components; i.e., nitrogen and argon, would boil off first, resulting in flow with high concentrations of nitrogen, argon and a much lower oxygen concentration than that which was supplied to the condenser—which would make the process of oxygen treatment ineffective or a failure.
This concern is explained in
Because of the aforementioned mixture problem, it is important and even critical not to let the amount of argon and nitrogen in the liquid become too high or when it is revaporized, the oxygen concentration will initially be much lower than that conventionally used in supplemental oxygen therapy (>85%). This can be accomplished by selecting the proper condenser temperature, which is a function of pressure, and by not condensing all of the incoming flow. If only part of the incoming flow (20-99%) is liquefied, the remainder of the flow will purge the vapor with higher impurity concentration from the system. A condenser temperature of about 90 K (for ˜17 psia) minimizes the amount of argon and nitrogen liquefied without overly diminishing the yield of oxygen. Hence there will be both liquid and vapor leaving the condenser. The liquid will fall into the dewar 14 and collect. The vapor which has not condensed is vented to the atmosphere through line 52 and the recuperator 15.
The amount of incoming flow liquefied is controlled by setting the mass flow rate relative to the cooling capacity of the cryocooler. The parameters of the condenser and/or cryocooler can be stored in the memory of the controller and/or computer and the controller regulating the incoming flow depending on the parameters stored and/or sensed. Having a mass flow rate which exceeds the cooling capacity of the cryocooler/condenser combination, prevents the incoming flow from being completely liquefied. The mass flow rate is controlled by the amount of flow restriction between inlet valve 19 and flow control valve 25. This includes the flow losses of the valves themselves as well as those in the recuperator, condenser, and all of the interconnecting plumbing.
The pressure in the dewar 14 is maintained slightly above ambient pressure while the cryocooler is operating by valve 25. It is desirable to keep the pressure in the condenser as high as possible because this increases the condensation temperature (as shown in
This pressure regulating function of the solenoid on-off valve 25 is accomplished by the pressure transducer 9 and controller 16. Alternately, a back pressure regulating valve (such as a Tescom BB-3 series) or a suitable servomechanism may be used in lieu of the actively controlled solenoid. Liquid keeps accumulating in the dewar 14 until the liquid level sensor 17 signals the controller that the dewar is full or until the oxygen sensor 18 signals that the oxygen concentration of fluid exiting the oxygen concentrator 11 is too low.
In the best mode, operating parameters for optimal operation of the system for the condenser should be that the condenser surface temperature should be in the range from 69.2-109.7 K and pressure should be in the range from 5-65 psia. The gas concentrations into the condenser for medical use should have oxygen in the range of 80-100%, nitrogen from 0-20%, and argon from 0-7%.
In order to transfer liquid from the dewar 14; e.g. to fill a portable LOX dewar 23, the pressure in the dewar 14 must be increased so that liquid can be forced up the dip tube 20. As shown in
With reference to
An alternative means for transferring liquid by raising the pressure in the dewar 14 includes adding a compressor 300 between the oxygen concentrator 11 and the condenser 13. The compressor 300 is preferably added in line 51, either before or after valve 19. The compressor 300 increases the pressure in the storage dewar 14 so that when the portable dewar 23 is engaged, liquid is forced up the dip tube 20 and into the portable dewar 23. An additional benefit of adding a compressor 300 at this location is that it increases the pressure during liquefication in the dewar 14, which increases the saturation temperature. An increased saturation temperature eases the cooling requirements on the cryocooler 12.
A further means for transferring liquid by raising the pressure in the dewar 14 includes using a high-pressure compressor 302 within the oxygen concentrator 11 instead of the typical low-pressure compressor. The high-pressure compressor 302 has the effect of increasing the pressure in the storage dewar 14 so that when the portable dewar 23 is engaged, liquid is forced up the dip tube 20. In addition to easing the cooling requirements on the cryocooler 12, a compressor 302 at this location slightly enhances the PSA cycle.
A still further means for transferring liquid by raising the pressure in the dewar 14 includes using a vaporizer loop 304. In this embodiment, the dewar 14 preferably remains at low pressure while liquid is being produced. When transfer of liquid out of the dewar 14 is desired, a valve 306 is opened to allow some liquid to flow into a coil 308 to be vaporized. This would increase the pressure in the dewar 14 so that liquid could be transferred to the portable dewar 23.
Another means for transferring liquid by raising the pressure in the dewar 14 includes a controllable heat leak such as a conductive strap 310 between ambient and the inner vessel of the dewar 14. When transfer of liquid out of the dewar 14 is desired, the heat leak is controlled so that heat from the ambient is transferred to the liquid, causing it to vaporize. This would increase the pressure in the dewar 14 so that liquid could be transferred to the portable dewar 23.
Another means for transferring liquid by raising the pressure in the dewar 14 includes a controllable pump 312 that is actuated when transfer of liquid out of the dewar 14 is desired.
An additional means for transferring liquid without raising the pressure in the dewar 14 includes incorporating a gravity-assisted dispensing mechanism 314 such as a controllable spigot (analogous to those used to dispense liquids from a large insulated cooler) near the bottom of the dewar 14. Unlike the alternative means for transferring liquid from the storage dewar 14 described above, which expel liquid out of the dip tube 20, the gravity-assisted dispensing mechanism eliminates the need for the dip tube 20. The gravity-assisted dispensing mechanism 314 preferably includes a quick disconnect valve 316 or other flow control means, similar to disconnect valve 22 described above, located on the end of the mechanism 314 to allow for connection of a portable dewar 23.
An additional means for transferring liquid without raising the pressure in the dewar 14 includes incorporating a portable dewar 23 adapted to be filled from a pressure less than 20 psig, which is the standard for currently available home stationary liquid dewars. For example, the portable dewar 23 may be adapted to be filled from a pressure such as 5 psig.
A further means for transferring liquid without raising the pressure in the dewar 14 involves replacing the storage dewar 14 with a specially designed portable dewar 23 such as that described above with respect to
In order to eliminate accumulation of solid water and hydrocarbons which may be supplied in trace amounts from the oxygen concentrator, the dewar 14, recuperator 15, and condenser 13 will be warmed to room temperature periodically (preferably after about 30 fillings of a portable dewar, or every two months). This procedure is accomplished most economically when the inventory of liquid in the storage dewar is low; e.g. shortly after liquid transfer and a portable dewar has been filled. In this “boil-dry” mode, valve 19 will be closed, the cryocooler 12 is turned-off, valve 25 is open, and heater 21 is energized until all the liquid has boiled-off as evidenced by, for example, the temperature sensor 10 being above 125 K. The heater will boil-off the remaining liquid in the dewar 14 and with it any trace amounts of water and hydrocarbons which are condensed and solidified in the liquid oxygen or on the cold surfaces. Once valve 19 is re-opened, the flow of concentrated oxygen gas purges and removes most of the water vapor and hydrocarbons from the liquefier. The heater 21 will remain turned on until the dewar temperature, measured by temperature sensor 10, has warmed to about 300 K. Any remaining water vapor will be flushed out by gaseous oxygen during the subsequent cooldown.
The dewpoint/frostpoint of the gas stream provided by the oxygen concentrator is below −55° C. Although the mass of water flowing into the liquefier is quite small, the ice/frost formed at such a cold temperature has a very low density and hence, can take a appreciable volume of space that can lead to plugging of the liquefier. Therefore, the design of the recuperator 15 and/or condenser 13 must be able to allow for accumulation of frost without plugging.
With reference to
Oxygen from the gaseous flow condenses into liquid oxygen at the condenser 74. The condenser 74 is shown in conjunction with a vapor compression cycle cryocooler 86 (evaporator 88, tube-in-tube heat exchanger 90, compressor 92) as its associated refrigerating mechanism. It will be readily understood by those skilled in the art that other refrigerating mechanisms may be used in conjunction with the condenser such as, but not by way of limitation, pulse tube, Stirling, etc. For example, with reference to
Excess gaseous flow not condensed becomes vent gas that is removed from the liquefier 70 via the recuperator 76. Vent gas enters the recuperator 76 through inlet 112, as shown by the arrows, flows through the helical recuperator 76 (providing the aforementioned pre-cooling) and preferably exits to the atmosphere through outlet 114.
The dewar 14 may include a central liquid withdrawal tube 116 for withdrawing liquid oxygen from the dewar 14. The central liquid withdrawal tube 116 may include an integral liquid level sensor 118 for monitoring the level of the liquid oxygen in the dewar 14. A heater 21 may be attached to the outer surface of the inner vessel of the dewar 14 to assist in transferring liquid oxygen from the dewar 14.
A getter cup 120 such as those used in commercial cryogenic dewars may be attached to the inner vessel of the dewar 14 to maintain a high vacuum in the dewar 14.
At initial start-up or after a periodic boil-dry phase, the dewar, condenser, recuperator, and all associated hardware are at room temperature and must be cooled down. This is accomplished in the “start-up” mode, where valve 19 (see
The higher density gas will have better heat transfer with the dewar walls and associated hardware. It is noted that higher flow rates will enhance the convection heat transfer but may exceed the cooling capacity. Based on the cooling characteristics of the cryocooler between room temperature and 90 K, the flow rate can be changed to minimize the cool-down time.
The dewar 14 is equipped with at least one relief valve 26 as a safety feature. Another relief valve 29 is provided and in communication with the inlet gas stream 51, before flowing into the recuperator 15. This serves as a back-up for relief valve 26 as well as providing a means to eliminate accumulated water from the recuperator 15 during periods when the cryocooler 12 is off, if valve 25 is closed. A check valve 27 is also provided to prevent backflow into the oxygen concentrator in the event of a malfunction.
Once the system attains a cool enough temperature, steady state or normal operational condense mode is used. As shown in
The transfer mode in
The double inlet pulse tube refrigerator as shown in
It is noted that with this type of cryocooler, it may be possible to remove some of the heat from the oxygen stream at a temperature warmer than Tc.
One possible geometry of the generally vertically oriented, gravity assisted condenser 13 in
In an alternative embodiment of the invention, the flutes 114 may have a profile that is other than convex such as, but not by way of limitation, generally rectilinear or generally V-shaped.
In a further embodiment of the invention, the fins 112 and flutes 114 may exist on only the exterior side 116 or interior side 118 of the condenser 110. Alternatively, the condenser 110 may have fins 112 and flutes 114 on the interior and/or the exterior and the condenser 110 is used in conjunction with another condensing device such as another condenser located within the interior 118 and/or around the exterior 116 of the condenser 110.
Prior art (U.S. Pat. Nos. 4,253,519, 4,216,819) has been limited to horizontal externally fluted tubes with purely radial conduction through the tube wall. In contrast, the condenser 110 of the present invention may include fins 112 and flutes 114 on both sides 116, 118. Also, heat is conducted axially in the condenser 110 of the present invention.
Thus, an improved home/ambulatory liquid oxygen system is disclosed. While the embodiments and applications of this invention have been shown and described, and while the best mode contemplated at the present time by the inventors has been described, it should be apparent to those skilled in the art that many more modifications are possible, including with regard to scaled-up industrial applications, without departing from the inventive concepts therein. Both product and process claims have been included and in the process claims it is understood that the sequence of some of the claims can vary and still be within the scope of this invention. The invention therefore can be expanded, and is not to be restricted except as defined in the appended claims and reasonable equivalence departing therefrom.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US609499 *||Dec 28, 1897||Aug 23, 1898||chatwood|
|US621536 *||Aug 11, 1897||Mar 21, 1899||Apparatus for liquefying air|
|US621537 *||Oct 13, 1898||Mar 21, 1899||Apparatus for liquefying gas|
|US665912 *||Jan 3, 1900||Jan 15, 1901||Emile Jolicard||Boiler.|
|US707633 *||Feb 15, 1901||Aug 26, 1902||James F Place||Art or process of liquefying air or other gases and cooling by means thereof.|
|US718572 *||Feb 17, 1902||Jan 13, 1903||Edwin Joseph Richardson||Apparatus for the liquefaction of air or other aeriform fluids.|
|US879302 *||Apr 3, 1905||Feb 18, 1908||Colorado Iron Works Co||Blast-heating apparatus.|
|US881176 *||Feb 23, 1906||Mar 10, 1908||Georges Claude||Apparatus for the liquefaction of air.|
|US948835 *||Feb 8, 1910||Bruce Walter||Ammonia-condenser.|
|US1454053 *||Feb 18, 1920||May 8, 1923||Griscom Russell Co||Oil cooler|
|US1782409 *||Dec 19, 1927||Nov 25, 1930||Griscom Russell Co||Heat exchanger|
|US1796510 *||Jan 24, 1930||Mar 17, 1931||Delas Francois Xavier J Albert||Surface condenser and the like|
|US1821080 *||Oct 15, 1930||Sep 1, 1931||Engineering Products Corp Inc||Radiator|
|US1867163 *||Jan 26, 1925||Jul 12, 1932||Louis Chavanne J||Heat recuperation|
|US1957006 *||Jun 5, 1929||May 1, 1934||Sulphide Corp||Method of and apparatus for condensing sulphur|
|US2017676 *||Mar 8, 1934||Oct 15, 1935||American Lurgi Corp||Method of and apparatus for condensing sulphuric acid|
|US2194654 *||Feb 19, 1938||Mar 26, 1940||Hadamovsky Paul||Apparatus for liquefying gases|
|US2210031 *||Aug 28, 1936||Aug 6, 1940||Pfaudler Co Inc||Refrigerating apparatus and method|
|US2318206 *||Jun 17, 1940||May 4, 1943||M Werk Company||Apparatus for treating liquids flowing through heated tubes|
|US2384714 *||Feb 29, 1944||Sep 11, 1945||Tech Studien Ag||Tubular heat exchanger|
|US2434519 *||Apr 18, 1942||Jan 13, 1948||Raskin Walter||Heat exchange conduit with a spiral fin having a capillary groove|
|US2440245 *||Mar 13, 1944||Apr 27, 1948||Standard Telephones Cables Ltd||Cooling of high-temperature bodies|
|US2751199 *||Apr 18, 1951||Jun 19, 1956||Taco Heaters Inc||Heat exchanger|
|US2797554 *||Jan 6, 1954||Jul 2, 1957||Donovan William J||Heat exchanger in refrigeration system|
|US2905447 *||Apr 22, 1957||Sep 22, 1959||Huet Andre||Tubular heat-exchanger|
|US2909903||Nov 7, 1956||Oct 27, 1959||Little Inc A||Liquefaction of low-boiling gases|
|US2919555||Jul 28, 1955||Jan 5, 1960||Joy Mfg Co||Apparatus for and method of separating gases|
|US2937079 *||Aug 6, 1956||May 17, 1960||Phillips Petroleum Co||Apparatus for contacting and subsequently separating immiscible liquids|
|US2943454 *||Jun 30, 1958||Jul 5, 1960||Mine Safety Appliances Co||Liquid oxygen converter|
|US2944627||Feb 12, 1958||Jul 12, 1960||Exxon Research Engineering Co||Method and apparatus for fractionating gaseous mixtures by adsorption|
|US2945354 *||Mar 18, 1957||Jul 19, 1960||North American Aviation Inc||Liquid oxygen conversion system|
|US2958204 *||Aug 13, 1956||Nov 1, 1960||Aro Equipment Corp||Liquid oxygen converter|
|US2960834 *||Nov 22, 1954||Nov 22, 1960||Garrett Corp||Production of liquid oxygen from atmospheric air|
|US2964919 *||Jul 6, 1959||Dec 20, 1960||British Oxygen Co Ltd||Converter system for liquefied gases|
|US2969957 *||Jan 10, 1956||Jan 31, 1961||Thomson Houston Comp Francaise||Electric discharge device cooling systems|
|US2970452 *||Apr 1, 1959||Feb 7, 1961||Union Carbide Corp||Method and apparatus for supplying liquefied gas|
|US2993682 *||Feb 24, 1958||Jul 25, 1961||Huet Andre||Heat exchanger tubes|
|US3055643 *||Aug 1, 1957||Sep 25, 1962||Thomson Houston Comp Francaise||Heat exchangers|
|US3097497||Aug 10, 1960||Jul 16, 1963||Normalair Ltd||Oxygen supply systems|
|US3117426 *||Nov 23, 1960||Jan 14, 1964||Garrett Corp||Environmental system for protective suit|
|US3152589 *||Apr 15, 1960||Oct 13, 1964||British Oxygen Co Ltd||Liquid oxygen system for passenger aircraft|
|US3183678 *||Apr 29, 1963||May 18, 1965||Bendix Corp||Liquid to gas conversion system|
|US3186406 *||Feb 5, 1960||Jun 1, 1965||Normalair Ltd||Breathing apparatus|
|US3199303 *||May 9, 1963||Aug 10, 1965||Union Carbide Corp||Oxygen therapy system|
|US3205670 *||Sep 24, 1962||Sep 14, 1965||Puritan Compressed Gas Corp||Oxygen supply system|
|US3313091||Nov 4, 1963||Apr 11, 1967||Exxon Research Engineering Co||Vacuum cycle adsorption|
|US3318307||Aug 3, 1964||May 9, 1967||Firewel Company Inc||Breathing pack for converting liquid air or oxygen into breathable gas|
|US3354664 *||Apr 1, 1965||Nov 28, 1967||Philips Corp||Transferring condensed liquids to a storage container|
|US3400758 *||May 16, 1966||Sep 10, 1968||United Aircraft Prod||Helical baffle means in a tubular heat exchanger|
|US3552392||Jul 1, 1968||Jan 5, 1971||Gen Electric||Aircraft closed circuit breathing system|
|US3570481||Oct 23, 1968||Mar 16, 1971||Cryogenic Systems Inc||Cryogenic underwater breathing apparatus|
|US3572048 *||Oct 14, 1968||Mar 23, 1971||Wiremold Co||Ominpositional cryogenic underwater breathind apparatus|
|US3707078||Feb 10, 1971||Dec 26, 1972||Bendix Corp||Fail-safe liquid oxygen to gaseous oxygen conversion system|
|US3710854 *||Feb 17, 1971||Jan 16, 1973||Gen Electric||Condenser|
|US3714942||Feb 3, 1969||Feb 6, 1973||Sub Marine Syst Inc||Cryogenic gas processing system|
|US3730178||Sep 22, 1971||May 1, 1973||Moreland F||Deep-sea dive suit and life support system|
|US3749155 *||Jul 13, 1971||Jul 31, 1973||Georges Claude Sa||Exchange process|
|US3797262 *||Dec 1, 1972||Mar 19, 1974||Union Carbide Corp||Cryogenic fluid supply system|
|US3807396||Mar 16, 1967||Apr 30, 1974||E & M Labor||Life support system and method|
|US3831594||Mar 5, 1973||Aug 27, 1974||Us Navy||Life support system|
|US3837396 *||Oct 4, 1972||Sep 24, 1974||Borg Warner||Vertical surface vapor condensers|
|US3864928 *||Mar 18, 1974||Feb 11, 1975||Union Carbide Corp||All-attitude cryogenic vapor vent system|
|US3898047||Jul 17, 1973||Aug 5, 1975||Bendix Corp||Oxygen generation system|
|US3903962 *||Jun 26, 1974||Sep 9, 1975||Borg Warner||Condensate guiding apparatus for vertical condensing tubes of vapor condenser|
|US3924968||Nov 19, 1973||Dec 9, 1975||Gen Motors Corp||Radial compressor with muffled gas chambers and short stable piston skirts and method of assembling same|
|US3935715 *||Jun 26, 1974||Feb 3, 1976||Borg-Warner Corporation||Vapor condenser for a refrigeration system|
|US3964866||Sep 13, 1974||Jun 22, 1976||William Barney Shelby||Helium reclamation|
|US3983861 *||Aug 21, 1975||Oct 5, 1976||Westman Manufacturing Company||Solar energy conversion device|
|US4013429||Jun 4, 1975||Mar 22, 1977||Air Products And Chemicals, Inc.||Fractionation of air by adsorption|
|US4017284||Dec 6, 1974||Apr 12, 1977||Cryox Corporation||Air distillation apparatus comprising regenerator means for producing oxygen|
|US4098303 *||Sep 17, 1976||Jul 4, 1978||Robert Brown Associates||Vapor recovery system for loading backs and storage tanks|
|US4181126||Jan 23, 1978||Jan 1, 1980||Hendry Stephen M||Cryogenic, underwater-breathing apparatus|
|US4194890||Feb 1, 1978||Mar 25, 1980||Greene & Kellogg, Inc.||Pressure swing adsorption process and system for gas separation|
|US4194891 *||Dec 27, 1978||Mar 25, 1980||Union Carbide Corporation||Multiple bed rapid pressure swing adsorption for oxygen|
|US4198213||Jan 26, 1978||Apr 15, 1980||The Garrett Corporation||Self adjusting oxygen enrichment system|
|US4211086 *||Mar 12, 1979||Jul 8, 1980||Beatrice Foods Company||Cryogenic breathing system|
|US4222750||Aug 16, 1976||Sep 16, 1980||Champion Spark Plug Company||Oxygen enrichment system for medical use|
|US4253519 *||Jun 22, 1979||Mar 3, 1981||Union Carbide Corporation||Enhancement for film condensation apparatus|
|US4263018||Aug 3, 1979||Apr 21, 1981||Greene & Kellogg||Pressure swing adsorption process and system for gas separation|
|US4279127||Mar 3, 1980||Jul 21, 1981||Air Products And Chemicals, Inc.||Removable refrigerator for maintaining liquefied gas inventory|
|US4331455||May 9, 1980||May 25, 1982||Osaka Oxygen Industries, Ltd.||Method of producing oxygen rich gas utilizing an oxygen concentrator having good start-up characteristics|
|US4349357||Jun 23, 1980||Sep 14, 1982||Stanley Aviation Corporation||Apparatus and method for fractionating air and other gaseous mixtures|
|US4360059 *||Apr 6, 1981||Nov 23, 1982||Funke Warmeaustauscher Apparatebau Kg||Tube type heat exchanger|
|US4404005 *||Aug 18, 1981||Sep 13, 1983||Normalair-Garrett (Holdings) Limited||Molecular sieve type gas separation systems|
|US4428372||Jul 31, 1981||Jan 31, 1984||Linde Aktiengesellschaft||Process and apparatus for providing breathing gas|
|US4449990||Sep 10, 1982||May 22, 1984||Invacare Respiratory Corp.||Method and apparatus for fractioning oxygen|
|US4465436||May 18, 1982||Aug 14, 1984||Siemens Aktiengesellschaft||Radial piston compressor|
|US4493368 *||Jun 8, 1982||Jan 15, 1985||Norsk Hydro A.S.||Helical flow heat exchanger having individually adjustable baffles|
|US4510760||Mar 2, 1984||Apr 16, 1985||Messer Griesheim Industries, Inc.||Compact integrated gas phase separator and subcooler and process|
|US4513587 *||Nov 22, 1983||Apr 30, 1985||Sueddeutsche Kuehlerfabrik Julius Fr. Behr Gmbh & Co., Kg||Evaporator particularly suitable for air conditioners in automotive vehicles|
|US4516424||Jul 9, 1982||May 14, 1985||Hudson Oxygen Therapy Sales Company||Oxygen concentrator monitor and regulation assembly|
|US4529411||Apr 30, 1984||Jul 16, 1985||Standard Oil Company||CO2 Removal from high CO2 content hydrocarbon containing streams|
|US4542010||Jun 30, 1982||Sep 17, 1985||Bend Research, Inc.||Method and apparatus for producing oxygen and nitrogen and membrane therefor|
|US4545790 *||Aug 11, 1983||Oct 8, 1985||Bio-Care, Incorporated||Oxygen concentrator|
|US4552571||Apr 5, 1984||Nov 12, 1985||Vbm Corporation||Oxygen generator with two compressor stages|
|US4561287||Jul 26, 1984||Dec 31, 1985||Hudson Oxygen Therapy Sales Company||Oxygen concentrator|
|US4575386||Sep 17, 1984||Mar 11, 1986||U.S. Philips Corporation||Method of liquefying a gas and liquefier for carrying out the method|
|US4576616||Sep 4, 1984||Mar 18, 1986||Proto-Med. Inc.||Method and apparatus for concentrating oxygen|
|US4583364||Aug 19, 1985||Apr 22, 1986||Sunpower, Inc.||Piston centering method and apparatus for free-piston Stirling engines|
|US4587967||Jul 9, 1985||May 13, 1986||Lifecare Services, Inc.||Oxygen enriched reciprocating piston respirator|
|US4591365||Oct 15, 1984||May 27, 1986||Linde Aktiengesellschaft||Semipermeable membrane gas separation system|
|US4602174||Apr 4, 1985||Jul 22, 1986||Sunpower, Inc.||Electromechanical transducer particularly suitable for a linear alternator driven by a free-piston stirling engine|
|US4610700||Oct 4, 1984||Sep 9, 1986||Union Carbide Corporation||Adsorbent composition useful in retarding corrosion in mufflers|
|US4627860||Mar 18, 1985||Dec 9, 1986||Hudson Oxygen Therapy Sales Company||Oxygen concentrator and test apparatus|
|US4636226||Aug 26, 1985||Jan 13, 1987||Vbm Corporation||High pressure oxygen production system|
|US4640031||Nov 10, 1983||Feb 3, 1987||N.V. W.A. Hoek's Machine||Gas cylinder identification device|
|US4670223||Jan 19, 1984||Jun 2, 1987||Le Masne S.A.||Apparatus for producing sterile air for medical use|
|US4673415||May 22, 1986||Jun 16, 1987||Vbm Corporation||Oxygen production system with two stage oxygen pressurization|
|US4698075||Jun 5, 1986||Oct 6, 1987||International Oxygen Company, Inc.||Control system for fluid absorption systems and the like|
|US4701187||Nov 3, 1986||Oct 20, 1987||Air Products And Chemicals, Inc.||Process for separating components of a gas stream|
|US4704146 *||Jul 31, 1986||Nov 3, 1987||Kryos Energy Inc.||Liquid carbon dioxide recovery from gas mixtures with methane|
|US4706664||Apr 11, 1986||Nov 17, 1987||Puritan-Bennett Corporation||Inspiration oxygen saver|
|US4717406||Jul 7, 1986||Jan 5, 1988||Liquid Air Corporation||Cryogenic liquified gas purification method and apparatus|
|US4765804||Sep 17, 1987||Aug 23, 1988||The Boc Group, Inc.||PSA process and apparatus employing gaseous diffusion barriers|
|US4822394 *||Sep 14, 1987||Apr 18, 1989||Vertech Treatment Systems, Inc.||Method and apparatus for the production and liquefaction of gases|
|US4826510||Jan 13, 1988||May 2, 1989||The John Bunn Company||Portable low profile DC oxygen concentrator|
|US4827643||Dec 5, 1985||May 9, 1989||Aga Gas Central, Inc.||Identification device for a container|
|US4841732||Dec 28, 1987||Jun 27, 1989||Sarcia Domenico S||System and apparatus for producing and storing liquid gases|
|US4844059||Jan 20, 1987||Jul 4, 1989||Draegerwerk Ag||Method and apparatus for enriching respiratory gas with oxygen and delivering it to a patient|
|US4848447 *||Apr 10, 1989||Jul 18, 1989||Sladky Hans||Tube-type heat exchanger and liquid distributor head therefor|
|US4850426 *||Oct 27, 1988||Jul 25, 1989||Vicarb||Gas/liquid heat exchanger with condensation|
|US4867766||Sep 12, 1988||Sep 19, 1989||Union Carbide Corporation||Oxygen enriched air system|
|US4869733||Jun 24, 1988||Sep 26, 1989||Vbm Corporation||Super-enriched oxygen generator|
|US4870960||Jun 12, 1987||Oct 3, 1989||Litton Systems, Inc.||Backup breathing gas supply for an oxygen concentrator system|
|US4880443 *||Dec 22, 1988||Nov 14, 1989||The United States Of America As Represented By The Secretary Of The Air Force||Molecular sieve oxygen concentrator with secondary oxygen purifier|
|US4899810 *||Oct 22, 1987||Feb 13, 1990||General Electric Company||Low pressure drop condenser/heat pipe heat exchanger|
|US4905685||Apr 13, 1988||Mar 6, 1990||Siemens Aktiengesellschaft||Inhalation anaesthesia equipment|
|US4922900||May 16, 1989||May 8, 1990||Dragerwerk Aktiengesellschaft||Pumping arrangement for supplying a ventilating apparatus with breathing gas|
|US4948391||May 12, 1989||Aug 14, 1990||Vacuum Optics Corporation Of Japan||Pressure swing adsorption process for gas separation|
|US4957107||May 10, 1988||Sep 18, 1990||Sipin Anatole J||Gas delivery means|
|US4971609||Feb 5, 1990||Nov 20, 1990||Pawlos Robert A||Portable oxygen concentrator|
|US4979882||Mar 13, 1989||Dec 25, 1990||Wisconsin Alumni Research Foundation||Spherical rotary machine having six rotary pistons|
|US4983190||May 21, 1985||Jan 8, 1991||Pall Corporation||Pressure-swing adsorption system and method for NBC collective protection|
|US4991616||Jan 11, 1989||Feb 12, 1991||Desarrollos, Estudios Y Patentes, S.A.||Installation for the supply of oxygen in hospitals and the like|
|US5002591 *||Jan 12, 1990||Mar 26, 1991||Vbm Corporation||High efficiency PSA gas concentrator|
|US5048600 *||Oct 10, 1990||Sep 17, 1991||T & G Technologies, Inc.||Condensor using both film-wise and drop-wise condensation|
|US5060480||Oct 30, 1990||Oct 29, 1991||L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude||Process and apparatus for the liquefaction of a flow of gaseous oxygen|
|US5071453||Oct 19, 1990||Dec 10, 1991||Litton Systems, Inc.||Oxygen concentrator with pressure booster and oxygen concentration monitoring|
|US5076823||Mar 20, 1990||Dec 31, 1991||Air Products And Chemicals, Inc.||Process for cryogenic air separation|
|US5078757||May 18, 1990||Jan 7, 1992||L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude||Process for the production of gaseous oxygen under pressure|
|US5144945||Apr 17, 1990||Sep 8, 1992||Nippon Sanso Kabushiki Kaisha||Portable oxygen-enriching air inhaler|
|US5154737||Apr 24, 1991||Oct 13, 1992||Vbm Corporation||System for eliminating air leakage and high purity oxygen of a PSA oxygen concentrator|
|US5158584||Mar 1, 1991||Oct 27, 1992||Teijin Limited||Oxygen enriching module and oxygen enriching apparatus using same|
|US5163297||Jan 15, 1991||Nov 17, 1992||Iwatani International Corporation||Device for preventing evaporation of liquefied gas in a liquefied gas reservoir|
|US5163978||Oct 8, 1991||Nov 17, 1992||Praxair Technology, Inc.||Dual product pressure swing adsorption process and system|
|US5195874||Jun 10, 1991||Mar 23, 1993||Tokico Ltd.||Multistage compressor|
|US5199423||Feb 6, 1991||Apr 6, 1993||Normalair-Garrett (Holdings) Ltd.||Oxygen-rich gas breathing systems for passenger carrying aircraft|
|US5207806||Oct 8, 1991||May 4, 1993||Praxair Technology, Inc.||Dual product pressure swing adsorption and membrane operations|
|US5231835 *||Jun 5, 1992||Aug 3, 1993||Praxair Technology, Inc.||Liquefier process|
|US5237987||Jun 7, 1990||Aug 24, 1993||Infrasonics, Inc.||Human lung ventilator system|
|US5248320||Nov 12, 1992||Sep 28, 1993||The Boc Group Plc||Compressing oxygen|
|US5271231 *||Aug 10, 1992||Dec 21, 1993||L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude||Method and apparatus for gas liquefaction with plural work expansion of feed as refrigerant and air separation cycle embodying the same|
|US5342176||Apr 5, 1993||Aug 30, 1994||Sunpower, Inc.||Method and apparatus for measuring piston position in a free piston compressor|
|US5354361||May 28, 1993||Oct 11, 1994||Litton Industries, Inc.||Energy recovering pressure balance scheme for a combination pressure swing absorber with a boost compressor|
|US5388413||Jan 22, 1993||Feb 14, 1995||Major; Thomas O.||Portable nitrogen source|
|US5405249||Nov 10, 1993||Apr 11, 1995||Ultra Electronics Limited||Gas supply apparatus|
|US5454429 *||May 18, 1993||Oct 3, 1995||Neurauter; Peter||Rods and mandrel turbulators for heat exchanger|
|US5458190 *||Nov 14, 1994||Oct 17, 1995||Showa Aluminum Corporation||Condenser|
|US5461859||Sep 8, 1994||Oct 31, 1995||Sunpower, Inc.||Centering system with one way valve for free piston machine|
|US5474595||Apr 25, 1994||Dec 12, 1995||Airsep Corporation||Capacity control system for pressure swing adsorption apparatus and associated method|
|US5477689 *||Aug 29, 1994||Dec 26, 1995||L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude||Process and installation for the production of gaseous oxygen and/or gaseous nitrogen under pressure|
|US5490871||Jan 28, 1994||Feb 13, 1996||The Boc Group Plc||Gas separation|
|US5496153||Jul 29, 1994||Mar 5, 1996||Sunpower, Inc.||Method and apparatus for measuring piston position in a free piston compressor|
|US5499623||Jan 7, 1993||Mar 19, 1996||Dragerwerk Ag||Gas mask and breathing equipment with liquefied respiration gas|
|US5525845||Mar 21, 1994||Jun 11, 1996||Sunpower, Inc.||Fluid bearing with compliant linkage for centering reciprocating bodies|
|US5531807 *||Nov 30, 1994||Jul 2, 1996||Airsep Corporation||Apparatus and method for supplying oxygen to passengers on board aircraft|
|US5539188||Dec 16, 1992||Jul 23, 1996||Gemplus Card International||System for the identification of containers, notably gas cylinders|
|US5555655||Sep 26, 1994||Sep 17, 1996||Aga Ab||Identification device for a container|
|US5558086||Nov 23, 1994||Sep 24, 1996||Freedom Air Services||Method and apparatus for the intermittent delivery of oxygen therapy to a person|
|US5558139||Feb 13, 1995||Sep 24, 1996||Essex Cryogenics Of Missouri||Liquid oxygen system|
|US5572880||Apr 21, 1995||Nov 12, 1996||Figgie International Inc.||Apparatus for providing a conditioned airflow inside a microenvironment and method|
|US5584194||Oct 31, 1995||Dec 17, 1996||Gardner; Thomas W.||Method and apparatus for producing liquid nitrogen|
|US5584669||Jan 24, 1995||Dec 17, 1996||Knf Neuberger Gmbh||Two-stage positive displacement pump|
|US5593291||Jul 25, 1995||Jan 14, 1997||Thomas Industries Inc.||Fluid pumping apparatus|
|US5593478||Sep 28, 1994||Jan 14, 1997||Sequal Technologies, Inc.||Fluid fractionator|
|US5634517 *||Jan 24, 1995||Jun 3, 1997||Siemens-Elema Ab||Device for reducing the relative humidity of a flowing gas|
|US5678536||Sep 5, 1995||Oct 21, 1997||The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration||Liquid air mixing system|
|US5689968||Oct 2, 1996||Nov 25, 1997||Figgie International Inc.||Apparatus for providing a conditioned airflow inside a microenvironment and method|
|US5697228 *||Nov 12, 1996||Dec 16, 1997||The Boc Group Plc||Gas manufacture|
|US5704964||Dec 26, 1995||Jan 6, 1998||Nippon Sanso Corporation||Pressure swing adsorption process|
|US5709203||Nov 22, 1996||Jan 20, 1998||Aerospace Design And Development, Inc.||Self contained, cryogenic mixed gas single phase storage and delivery system and method for body cooling, gas conditioning and utilization|
|US5726908||Mar 20, 1995||Mar 10, 1998||Figgie International Inc.||Liquid quantity sensor and method|
|US5730778||Oct 21, 1996||Mar 24, 1998||Sequal Technologies, Inc.||Fluid fractionator|
|US5823186||Feb 6, 1997||Oct 20, 1998||Dragerwerk Ag||Respirator|
|US5827358 *||Nov 8, 1996||Oct 27, 1998||Impact Mst, Incorporation||Rapid cycle pressure swing adsorption oxygen concentration method and apparatus|
|US5858062||Feb 10, 1997||Jan 12, 1999||Litton Systems, Inc.||Oxygen concentrator|
|US5875783||Nov 6, 1997||Mar 2, 1999||Dragerwerk Ag||Gas delivery means for respirators and anesthesia apparatus|
|US5893275 *||Sep 4, 1997||Apr 13, 1999||In-X Corporation||Compact small volume liquid oxygen production system|
|US5893944||Nov 7, 1997||Apr 13, 1999||Dong; Jung Hyi||Portable PSA oxygen generator|
|US5901758||Apr 30, 1997||May 11, 1999||The Boc Group, Inc.||Method of filling gas containers|
|US5979182||Oct 31, 1997||Nov 9, 1999||Kabushiki Kaisha Kobe Seiko Sho||Method of and apparatus for air separation|
|US5979440||Jun 16, 1997||Nov 9, 1999||Sequal Technologies, Inc.||Methods and apparatus to generate liquid ambulatory oxygen from an oxygen concentrator|
|US5988165||Oct 1, 1997||Nov 23, 1999||Invacare Corporation||Apparatus and method for forming oxygen-enriched gas and compression thereof for high-pressure mobile storage utilization|
|US6004378||Feb 24, 1992||Dec 21, 1999||Bayer Aktiengesellschaft||Oxygen enrichment process|
|US6012453||Oct 15, 1997||Jan 11, 2000||Figgie Inernational Inc.||Apparatus for withdrawal of liquid from a container and method|
|US6029473 *||Apr 30, 1998||Feb 29, 2000||L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude||Process and installation for filling a reservoir under pressure|
|US6035894||Jul 30, 1997||Mar 14, 2000||Weh Gmbh Verbindungstechnik||Coupling device for rapid connection|
|US6079459||Feb 11, 1998||Jun 27, 2000||Welding Company Of America||Controller for tank-filling system|
|US6089226||Jan 16, 1998||Jul 18, 2000||Aerospace Design & Development, Inc.||Self contained, cryogenic mixed gas single phase storage and delivery|
|US6132177||Aug 13, 1998||Oct 17, 2000||Bristol Compressors, Inc.||Two stage reciprocating compressors and associated HVAC systems and methods|
|US6212904||Nov 1, 1999||Apr 10, 2001||In-X Corporation||Liquid oxygen production|
|US6230516||Feb 4, 2000||May 15, 2001||Andonian Family Nominee Trust||Apparatus for mixing a multiple constituent liquid into a container and method|
|US6230518||Sep 23, 1999||May 15, 2001||Linde Aktiengesellschaft||Process and liquefier for the production of liquid air|
|US6289981 *||Oct 18, 1999||Sep 18, 2001||Showa Denko K.K.||Multi-bored flat tube for use in a heat exchanger and heat exchanger including said tubes|
|US6302107||Sep 16, 1998||Oct 16, 2001||Invacare Corporation||Apparatus and method for forming oxygen-enriched gas and compression thereof for high-pressure mobile storage utilization|
|US6314957||Apr 16, 1999||Nov 13, 2001||Air Liquide Sante (International)||Portable home oxygen therapy medical equipment|
|US6342090||May 16, 2000||Jan 29, 2002||Litton Systems, Inc.||Gas generating system with multi-rate charging feature|
|US6393802||Dec 22, 1999||May 28, 2002||Sunrise Medical Hhg, Inc.||Cylinder filler for use with an oxygen concentrator|
|US6422237||Dec 27, 1999||Jul 23, 2002||DRäGER MEDIZINTECHNIK GMBH||Respirator with a breathing circuit|
|US6446630||Feb 7, 2000||Sep 10, 2002||Sunrise Medical Hhg Inc||Cylinder filling medical oxygen concentrator|
|US6513521||Jul 17, 2000||Feb 4, 2003||Aerospace Design & Development, Inc.||Cryogenic mixed gas single phase storage and delivery|
|US6520176||Jun 30, 2000||Feb 18, 2003||L'air Liquide, Societe Anonyme A Directoire Et Conseil De Surveillance Pour L'etude Et L'exploitation Des Procedes Georges Claude||Portable oxygen concentrator|
|US6530421 *||Mar 31, 2000||Mar 11, 2003||York International Corporation||Counterflow evaporator for refrigerants|
|US6651658||Aug 3, 2000||Nov 25, 2003||Sequal Technologies, Inc.||Portable oxygen concentration system and method of using the same|
|US6681764 *||Jun 29, 1999||Jan 27, 2004||Sequal Technologies, Inc.||Methods and apparatus to generate liquid ambulatory oxygen from an oxygen concentrator|
|US6719019||Jun 28, 2002||Apr 13, 2004||Litton Systems, Inc.||Deployable oxygen charging system|
|US6805122||Sep 14, 2001||Oct 19, 2004||Invacare Corporation||Oxygen conserving device utilizing a radial multi-stage compressor for high-pressure mobile storage|
|US6889726||Oct 25, 2002||May 10, 2005||Invacare Corporation||Method and apparatus for filling portable high pressure cylinders with respiratory oxygen|
|US6904913||Aug 7, 2003||Jun 14, 2005||Acoba, Llc||Method and system for delivery of therapeutic gas to a patient and for filling a cylinder|
|US6923180||Oct 23, 2003||Aug 2, 2005||Invacare Corporation||Oxygen conserving device utilizing a radial multi-stage compressor for high-pressure mobile storage|
|US20050072423||Oct 7, 2003||Apr 7, 2005||Deane Geoffrey Frank||Portable gas fractionalization system|
|US20050115630||Oct 8, 2004||Jun 2, 2005||Richey Joseph B.Ii||Method and apparatus for filling portable high pressure cylinders with respiratory oxygen|
|US20050136299||Dec 17, 2004||Jun 23, 2005||Richey Joseph B.Ii||Oxygen supply system|
|US20050274142||Jun 13, 2005||Dec 15, 2005||Corey John A||Cryogenically producing oxygen-enriched liquid and/or gaseous oxygen from atmospheric air|
|US20060000474||Jul 13, 2005||Jan 5, 2006||Richey Joseph B Ii||Oxygen conserving device utilizing a radial multi-stage compressor for high-pressure mobile storage|
|USRE19031||Nov 29, 1927||Dec 19, 1933||Process and apparatus for the|
|EP0247365A2||Apr 24, 1987||Dec 2, 1987||Körber Ag||Filling apparatus for oxygen bottles for use in the medicinal oxygen therapy|
|1||"Design Manual for Two-Phase Components of Spacecraft Thermal Management Systems"; PL-TR-92-3002, Crowley et al, Phillips Laboratory, Sep. 1992.|
|2||"Hautkondensation an feingewelten Oberflachen bei Beruckischtigun der Obrflachenspannungen"; Von Romano Gregoric, vol. V, 1954 (in German).|
|3||USPTO Reexam Control No. 90/008,167.|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US8418691||Mar 20, 2009||Apr 16, 2013||Covidien Lp||Leak-compensated pressure regulated volume control ventilation|
|US8424521||Feb 27, 2009||Apr 23, 2013||Covidien Lp||Leak-compensated respiratory mechanics estimation in medical ventilators|
|US8434480||Mar 30, 2009||May 7, 2013||Covidien Lp||Ventilator leak compensation|
|US8448641||Aug 2, 2012||May 28, 2013||Covidien Lp||Leak-compensated proportional assist ventilation|
|US8746248||Dec 12, 2008||Jun 10, 2014||Covidien Lp||Determination of patient circuit disconnect in leak-compensated ventilatory support|
|US8770199||Dec 4, 2013||Jul 8, 2014||Ino Therapeutics Llc||Cannula for minimizing dilution of dosing during nitric oxide delivery|
|US8973577||Mar 11, 2013||Mar 10, 2015||Covidien Lp||Leak-compensated pressure regulated volume control ventilation|
|US8978650||Apr 26, 2013||Mar 17, 2015||Covidien Lp||Leak-compensated proportional assist ventilation|
|US9032959||Dec 4, 2013||May 19, 2015||Ino Therapeutics Llc||Cannula for minimizing dilution of dosing during nitric oxide delivery|
|US9421338||Mar 12, 2013||Aug 23, 2016||Covidien Lp||Ventilator leak compensation|
|US9550039||Jun 23, 2014||Jan 24, 2017||Mallinckrodt Hospital Products IP Limited||Cannula for minimizing dilution of dosing during nitric oxide delivery|
|US9556029 *||Nov 21, 2009||Jan 31, 2017||Koninklijke Philips N.V.||Liquid oxygen production device and method|
|US9675771||Oct 18, 2013||Jun 13, 2017||Covidien Lp||Methods and systems for leak estimation|
|US9795756||Dec 4, 2013||Oct 24, 2017||Mallinckrodt Hospital Products IP Limited||Cannula for minimizing dilution of dosing during nitric oxide delivery|
|US20110239698 *||Nov 21, 2009||Oct 6, 2011||Koninklijke Philips Electronics, N.V.||Liquid oxygen production device and method|
|US20130068220 *||Aug 28, 2009||Mar 21, 2013||Ravikumar V. Kudaravalli||Systems and methods for generating liquid oxygen for portable use|
|US20160003525 *||Sep 18, 2015||Jan 7, 2016||Koninklijke Philips N.V.||System and method for liquefying a fluid and storing the liquefied fluid|
|U.S. Classification||128/201.21, 128/200.24, 128/204.17, 128/204.15|
|International Classification||A62B7/00, A62B7/06|
|Cooperative Classification||Y02P70/34, F17C2265/015, F17C2270/0509, F17C2223/0161, F17C2221/011, F17C2227/0353, F25J1/0276, F25J2205/80, F25J2205/40, F25J1/0244, F25J1/0212, F25J2220/50, F25J1/0052, F25J1/0017, F25J1/0225, B01D2257/102, B01D2257/504, B01D2259/40001, B01D5/0039, B01D2259/4533, F17C6/00, F25J2205/60, B01D2257/404, B01D2253/116, B01D2257/80, B01D2259/4525, B01D2257/502, F25B9/145, B01D2259/416, B01D2253/108, B01D53/261, F25J2210/40, Y02C10/08, B01D53/047, B01D2259/455, F25B9/006, B01D2256/12, B01D53/053, B01D2259/40009, B01D2259/4541, F25J2270/90, F25J2270/91|
|European Classification||F25J3/04M, F25J3/04Z4U, F17C6/00, F25J1/02Z4U2, F25J3/04C4, B01D5/00F12, B01D53/047|