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

Abstract

The present invention is directed to a much safer and less expensive way of providing portable oxygen from a gas concentrator for patients who do not want to be tied to a stationary machine or restricted by present oxygen technology. 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.

Description

PRIOR APPLICATIONS[0001]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.BACKGROUND OF THE INVENTION[0002]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.[0003]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—...

AI Technical Summary

Benefits of technology

[0045]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.

[0049]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.

Problems solved by technology

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.

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.

Both these gaseous oxygen and liquid oxygen options have substantial drawbacks.

The major drawback of the gaseous oxygen option is that the small cylinders of gaseous oxygen can only provide gas for a short duration.

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.

Additionally, attempting to compress the oxygen in pressurized canisters in the home is dangerous, especially for untrained people.

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.

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.

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.

In either case, the home care provider must make costly weekly or biweekly trips to the patient's home to replenish the oxygen.

At present, there are no home oxygen concentrators commercially available that can provide liquid oxygen.

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.

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