GB2423355A

GB2423355A - Apparatus for providing breathing gas

Info

Publication number: GB2423355A
Application number: GB0425779A
Authority: GB
Inventors: Bernard Ramsay Bligh
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-11-24
Filing date: 2004-11-24
Publication date: 2006-08-23
Anticipated expiration: 2024-11-24
Also published as: GB2423355B; GB0425779D0; GB0426116D0

Abstract

An apparatus for providing breathing gas comprising one or more vessels 1 containing pressurised oxygen, an expansion device 2 for reducing the pressure of the oxygen withdrawn from the vessels 1, the expansion device 2 providing work to operate a compressor 4 to compresses air from a safe location 3, and mixing the compressed air with the oxygen from the expansion device 3 to supply the breathing gas through pipes 16. Oxygen in the one or more vessels 1 may be at a pressure between 100 and 200 bar, may be supplied to the expansion device 2 via a pipe 10, to a pressure reduction valve 11 to reduce the pressure to about 10 bar and to a pipe 12. Expansion device 2 may be a turbine. Compressor 4 may compress air to a pressure of about 1.3 bar, pass the air through a pipe 5 and non-return valve 6, and mix with the oxygen at a pressure of 1.3 bar from the expansion device 2 in a pipe 14 before passing through a control valve 15 and the pipes 16. The breathing gas may be used to supply air to passengers and crew of aircraft in an emergency. A heat exchanger (7, fig 2) may be provided so that at high altitudes when the air from the safe location at about 0.3 bar is compressed, the heat generated in the compression stage is exchanged with oxygen feeding the expansion device 2.

Description

Do(m\FTcTrrlAI ETNT c(TITC'ATTC1J tiJ APP ATH ANn 2prc P( PQ\/TnTNr

R2PATHTNt (A.

I, Bernard Ramsay BHgh, a Brtsh subject, of 4, St. James's Avenue, Hampton HiM, Mdd!esex, do hereby dec!are the!nventon, for which I pray that a patent may be granted to me, and the method by which it s to be performed, to be particularly described and by the foiio''iin; LO L II. - Ths n'enton relates to the supply of breathing air in an emergency; :n particular the supply of breathing oxygen in an emergency in an aircraft. In a known process, if there is a breakdown in the supply of the normal air for the passengers and crew in the cabin of an aircraft, there IS made available a supply of pure oxygen from high pressure vessels via breathing masks.

This process has a number of disadvantages. First the aircraft needs to have a supply of oxygen vessels on permanent standby and these are a considerable weight which is a permanent load for the flying aircraft.

Second, the supply of pure oxygen to the enclosed space of the cabin of an aircraft is a fire hazard; it is well-known that an atmosphere which is enriched in oxygen can support fire very vigorously.

Third, the breathing of pure oxygen may be detrimental for some persons who are adversely susceptib'e to breathing pure oxygen.

The present invention aims to alleviate these disadvantages.

In the present invention there is provided one or more vessels containing high pressure oxygen and means for withdrawing a stream of oxygen and letting down the pressure of the said oxygen by way of an expansion machine, typically a turbine, such that the expansion machine provides work to operate a compressor which compresses a stream of air from a safe location, the said compressed air is mixed with the said let-down oxygen to provide a gas stream for breathing.

The present invention, which is both a process and an apparatus for carrying out this process, is described with reference to the accompanying Figure 1. The operations of control valves and other flow- controlling devices are not described in detail herein because this technology is well understood by those skilled in the art. There are provided one or more vessels, 1, containing high pressure oxygen, typically at 100 to 200 bars. When breathing gas is required, a stream of oxygen is passed from the high pressure vessels via pipe, 10, through valve, 11, such that the pressure of the oxygen is let down to about 10 bars and thence via pipe, 12, to an expansion engine, 2, typically an expansion turbine, where the pressure is let down to about 1.3 bars in pipe 13. In this way the energy derived from the turbine is used to drive a compressor, 4, which compresses air from a safe location, 3, to about 1.3 bars in pipe, 5. The compressed air is passed through the non-return valve, 6, to mix with the oxygen stream, 13, at 1.3 bars already described. From there the mixed gas is passed via pipe, 14, and control valve, 15, to the pipes, 16, which are the distribution pipes for the breathing by personnel. This breathing gas, 16, s typically 60% to 80% oxygen by volume.

It needs to be understood that if the aircraft is going through an emergency at high altitude, the surrounding atmosphere will be at a low pressure, for example 0.3 bar. In an emergency it may be that this low pressure air will be the source of the air at a "safe location" for compression in the compressor, 4, already described. The action of compressing this air will be to heat it up. This heating is utilized in the next variant of this invention.

A variant of the present invention is described with reference to Figure 2. There are provided one or more vessels, 1, contaitling high pressure oxygen, typically at 100 to 200 bars. When breathing gas is required, a stream of oxygen is passed from the high pressure vessels via pipe, 10, through valve, 11, such that the pressure of the oxygen is let down to about 10 bars and thence via pipe, 12, to a heat exchanger, 7, where the oxygen is warmed up by a stream of warm air to be described. The warmed oxygen, 17, goes to an expansion engine, 2, typically an expansion turbine, where the pressure is let down to about 1.3 bars in pipe 13. In this way the energy derived from the turbine is used to drive a compressor, 4, which compresses air from a safe location, 3, to about 1.3 bars in pipe, 5. The compressed air, which has a higher temperature than ambient temperature, is passed through the non-return valve, 6, to the heat exchanger, 7, already described where the warm air raises the temperature of the oxygen already described. The air leaving the heat exchanger, 7, is in pipe 8 and mixes with the oxygen stream, 13, at 1.3 bars already described. From there the mixed gas is passed via pipe, 14, and control valve, 15, to the pipes, 16, which are the distribution pipes for the breathing by personnel. This breathing gas, 16, is typically 60 h to 80% oxygen by volume.

The advantage of the variant, described with reference to Figure 2, is that the heat in the compressed air stream, 5, is used to warm up the oxygen stream, 12, before it enters the expansion turbine, 2. This makes more energy available in the turbine for compressing the air, and therefore a greater proportion of air can be used to make the breathing gas.

It is standard practice for passenger aircraft to have air- conditioning equipment which is employed during virtually all flights.

As an optional additional feature to any variant of the present invention the temperature control for the breathing air may be derived indirectly from the air-conditioning equipment. This temperature control would be applied at pipe 14 on Figures 1 and 2.

Both of the variants of this invention produce the advantages claimed for this invention, namely that (1) the proportion of oxygen in the breathing gas is reduced from 100 h oxygen, (2) the weight of the high pressure vessels is reduced, (3) the risk of a fire in the cabin of an aircraft is reduced, (4) the breathing gas is more nearly appropriate for persons who are adversely susceptible to breathing pure oxygen.

Claims

CLAIMS.

What I claim is (1) An apparatus for providing breathing gas comprising one or more vessels containing high pressure oxygen and means for withdrawing a stream of oxygen and the means for letting down the pressure of the said oxygen by way of an expansion machine, such that the expansion machine provides work to operate a compressor which compresses a stream of air from a safe location, and the said compressed air is mixed with the said let-down oxygen to provide a gas stream suitable for breathing.

(2) An apparatus substantially as claimed in Claim 1, with the additional feature that the oxygen which enters the said expansion machine has been warmed in a heat exchanger by means of the said stream of air from the said compressor.

(3) An apparatus as claimed in Claim 1 or 2, in which the said expansion machine is a turbine.

(4) An apparatus as claimed in any of the previous claims in which the high pressure oxygen is at a pressure in the range 10 to 300 bars.

(5) An apparatus as claimed in any of the previous claims in which the oxygen entering the expansion machine is in the range 4 to 14 bars.

(6) An apparatus as claimed in any of the previous claims in which the oxygen leaving the expansion machine is at a pressure in the range 0.5 to
2.0 bars.

(7) An apparatus as claimed ri any of the previous claims in which the air from a safe location is compressed in the said compressor to a pressure in the range 0.5 to 2.0 bars.

(8) An apparatus substantially as depicted in either Figure 1 or Figure 2.

(9) Gas for breathing produced substantially by apparatus as claimed in any of the previous claims.

* * * * Amendments to the claims have been filed as follows What I claim is (1) An apparatus for providing breathing gas comprising one or more vessels containing high pressure oxygen and means for withdrawing a stream of oxygen and the means for letting down the pressure of the said oxygen by way of an expansion machine, such that the expansion machine provides work to operate a compressor which compresses a stream of air from a safe location, and the said compressed air is mixed with the said let-down oxygen to provide a gas stream suitable for breathing, (2) An apparatus substantially as claimed in Claim 1, with the additional feature that the oxygen which enters the said expansion machine has been warmed in a heat exchanger by means of the said stream of air from the said compressor.

(3) An apparatus as claimed in Claim 1 or 2, in which the said expansion machine is a turbine.

(4) An apparatus as claimed in any of the previous claims in which the high pressure oxygen is at a pressure in the range 100 to 200 bars.

(5) An apparatus as claimed in any of the previous claims in which the air from a safe location is compressed in the said compressor to a pressure of about 1.3 bars.

(6) An apparatus substantially as depicted in Figure 1.

(7) An apparatus substantially as depicted in Figure 2.

(9) Gas for breathing produced substantially by apparatus as claimed in any of the previous claims.

* * * *