WO2015019322A1

WO2015019322A1 - A hypoxic system and method for delivering oxygen depleted breathing gas to a space

Info

Publication number: WO2015019322A1
Application number: PCT/IB2014/063784
Authority: WO
Inventors: Tom FYFE
Original assignee: F.R. Pulford & Son Pty Ltd
Priority date: 2013-08-07
Filing date: 2014-08-07
Publication date: 2015-02-12

Abstract

A hypoxic system 11 and method for delivering depleted oxygen breathing gas to a space 17. The system includes a low pressure blower unit 13 for generating air at very low pressure; and a low pressure membrane unit 15 having sufficient surface area to produce enough nitrogen for delivering hypoxic gas to the space with enough oxygen content to still function as a breathing gas. The very low pressure is in a range of 1 to 3 bar and is ideally 2 bar.

Description

A HYPOXIC SYSTEM AND METHOD FOR DELIVERING OXYGEN DEPLETED

BREATHING GAS TO A SPACE

FIELD OF THE INVENTION

This invention relates to a hypoxic system and method for delivering oxygen depleted breathing gas to a space. The invention has particular, but not exclusive, utility with hypoxic training or therapy facilities which have oxygen depleted air to produce ameliorating effects with the cardiovascular system of persons training or undergoing therapy that are similar to those experienced naturally in high altitude environments. Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. BACKGROUND TO THE INVENTION

The following discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge as at the priority date of the application.

Hypoxic systems and methods for producing hypoxic environments artificially for training and/or therapeutic purposes are well known in the art. A characteristic of these systems is that the membranes required to produce nitrogen in sufficient quantities to deplete the relative oxygen content within a space occupied by a person or persons benefiting from the environment need air to be supplied to them at relatively high pressure. This pressure is generally above 8 bar and is produced by one or more air compressors that require a significant amount of energy to operate.

Consequently, in order to provide such artificially induced environments in commercial establishments operating for profit is quite expensive due to the high energy costs associated with running the compressor or compressors. In a suburban gymnasium for example where the operating profit margin can be quite slight due to the cost consciousness of the clientele, this can make the implementation of such systems commercially unviable.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a hypoxic system and method which can operate at lower pressure levels in order to achieve significant energy savings, thereby making the provision of such systems economically viable for small to medium size businesses such as suburban gymnasiums as well as larger businesses.

In accordance with one aspect of the present invention, there is provided a hypoxic system for delivering depleted oxygen breathing gas to a space including: a low pressure blower unit for generating air at very low pressure; and a low pressure membrane unit having sufficient surface area to produce enough nitrogen for delivering hypoxic gas to the space with enough oxygen content to still function as a breathing gas.

Preferably, the very low pressure is in a range of 1 to 3 bar and ideally is 2 bar.

Preferably, the hypoxic system includes control means to sense the oxygen content within the space and control the operation of the blower and the flow rate of the hypoxic gas as well as the proportion of hypoxic gas to air being delivered to the confined space to maintain the oxygen content therein at a desired set point. In accordance with another aspect of the present invention, there is provided a method for delivering oxygen depleted breathing gas to a space, including: generating air at very low pressure and producing enough nitrogen therefrom to form a hypoxic gas; and delivering the hypoxic gas to the space with enough oxygen content to still function as a breathing gas.

Preferably, the method includes sensing the oxygen content within the space and controlling the pressure and flow rate of the air pressure generation as well as the proportion of hypoxic gas to air being delivered to the confined space to maintain the oxygen content therein at a desired set point.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are referred to in the following description of the preferred embodiments, wherein:

Fig 1 is a perspective view of a blower unit and membrane unit according to the first specific embodiment;

Fig 2 is a plan view of Fig 1 ;

Fig 3 is a side elevation of Fig 1 and 2;

Fig 4A is a rendered view of Fig 2; and Fig 4B is a similar view to Fig 3, but showing the internal fit-out of the blower unit and membrane unit;

Fig 5 is a schematic diagram of the hypoxic system;

Figs 6 and 7 are two sets of orthogonal views of the blower component of the blower unit and some data specifications for different models of the blower shown, whereby:

Fig 6A is a plan view, Fig 6B is a side elevation and Fig 6C is an end elevation all of blower model 1 A; and

Fig 7A is a plan view, Fig 7B is a side elevation and Fig 7C is an end elevation all of blower model 1 B;

Fig 8 is a side view of the blower unit in Figs 1 to 5 showing the naming of the major components; Fig 9 is a top perspective view of a membrane unit in accordance with another embodiment;

Fig 10 is a block diagram showing the main components of the air treatment system as connected in circuit with the blower unit 12 and the membrane unit 15;

Fig 1 1 is a set of orthogonal views of a single membrane of a membrane unit, were Fig 1 1 A is a side elevation, Fig 1 1 B is an outlet end elevation, and Fig 1 1 C is an inlet end elevation; and

Fig 12 is a schematic diagram showing the various components of a single membrane.

DESCRIPTION OF PREFERRED EMBODIMENT

The invention will be described according to two specific embodiments. The first embodiment is shown in Figs 1 to 8 and Figs 10 and 1 1 , and the difference with the second embodiment is shown in Fig 9.

The first embodiment is directed towards a hypoxic system 1 1 generally comprising: a blower unit 13, a membrane unit 15, a confined space 17 within a room 19 sufficiently large for persons to exercise in a gymnasium environment, and a control means in the form of a control circuit 20 for sensing the oxygen content within the confined space and controlling the operation of the blower unit and membrane unit. The blower unit 13 is housed within a blower cabinet 21 having two doors

23 along each side of the cabinet to enable the components of the blower unit housed within to be accessed for service or maintenance and an open bottom elevated from the ground to allow the unimpeded ingress of air into the confines of the blower cabinet. The components of the blower unit 13 include a blower 1 equipped with blower inlet filter 2, a safety relief valve 3, a cooler 4, a receiver 5 equipped with a safety relief valve 3' and a pressure transducer 6. In the present embodiment, the type of blower 1 used in the blower unit 13 can be of the type 1 A shown in Fig. 6 of the drawings or the type 1 B as shown in Fig 7 and includes an air suction inlet A, a pressure connection B, a safety valve D being the safety relief valve 3, a cooling air entry E for the blower motor, a cooling exit F from the blower motor and an inlet air silencer Z.

The particular blower used depends upon the size of the room, and in the embodiment can be one of three different types configured in one of the two arrangements shown in Figs 6 and 7. The design specifications of each type are included in Tables A and B.

TABLE A where: Capacity

ps¾ Excess pressure

3 - otor version ZHZ ton return leaf kw ftp Motor rating ZDR Pressure resssiisting

A Fuil toad am erage ZAF Suction mw

Π3ΪΪΪ ZPD Pulsation siterjcsr im Average noise isvsS Z^S otor starter lbs ZAD Soft starter

qt Osi capacity (Ges r) ZBZ Sound box

The first blower that is used for small room applications is the 150 model 1 A shown in Fig 6 with a specification in Table A. It operates at the lowest kilowatt/horsepower power range (7.5 kW/ 10 hp). The capacity v excess pressure responses for different power ratings and frequencies of the 150 model 1 A is shown in Graph A. In these specifications:

Capacity refers to free air at 1 standard atmosphere and 20°C (68°F); and

Curves and tables are in respect of responses with a blower operating at normal operating temperature.

GRAPH A The second blower that is used in a variety of small to medium size room applications is the 300 model 1 B shown in Fig 7 with a specification in Table B. This blower can operate across three low to medium power ranges (7.5, 1 1 or 15 kW/ 15, 20 or 25 hp). The third blower that is used in a variety of medium to large size room applications is the 400 model 1 B, which is of the same design configuration as the 300 model being shown in Fig 7 but with a different specification in Table B. The third blower 1 B can operate across four medium to high power ranges at 50 Hz, and three medium to high power ranges at 60 Hz (1 1 , 15, 18.5 or 22 kW/ 20, 25, or 30 hp). Depending upon the frequency of operation of the blower, either being 50 Hz (where the power rating is measured in kilowatts) or 60 Hz (where the power rating is measured in horsepower), the different types of blower can blow air at different capacities measured in cubic feet per minute from 85 to 227 cubic feet per minute (cfm) across a pressure range of up to 2 bar at 50 Hz, and 100 to 272 cfm across a pressure range of up to 2 bar at 60 Hz.

r ZRZ/ZDR 50/ 40 50/40 ec7* a7*

. ZAF/ZPD 50ίβ!¾/300 so o¾;aoo 8ΰ·ϋΟ)/400 so ;oo 1/500

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TABLE B

The capacity v excess pressure responses for different power ratings and frequencies of the 300 model 1 B and 400 model 1 B is shown in Graph B.

GRAPH B

In these specifications, again: • Capacity refers to free air at 1 standard atmosphere and 20°C (68°F); and

• Curves and tables are in respect of responses with a blower operating at normal operating temperature.

Importantly, the blower 1 is operating at a low pressure of up to 2 bar and at most 3 bar, which in this specification is deemed to be a very low pressure range for operating a hypoxic system relative to prior art systems, whereas in the prior, art hypoxic systems operating from 6 to 13 bar are considered to be low pressure.

The blower 1 produces air at a pressure of up to 2 bar and feeds it via the pressure connection B up through the cooler 4, which is embodied in the form of an intercooler functioning not only to cool the air under pressure from the blower, but also to cool the blower itself.

Moreover, the intercooler cools the air coming from the blower motor by having two external cooler fans 25 suck air from the open bottom of the blower cabinet 21 over all components within the cabinet and then pump the hot air out of the top of the blower cabinet. In this process, the blower 1 sucks air within the blower cabinet through the cooling air entries E at either end of the blower and expels it from the cooling air exits F medially of the blower to help cool the blower motor and the air generated by the blower. The pressurized air produced by the blower is outlet through the pressure connection B and is passed through the cooler 3 to then be fed into the receiver 5, which is in the form of an air tank 27. The air tank 27 is located at the bottom of the blower cabinet 21 to receive the coolest air passing through the blower unit 13. The air tank 27 is equipped with a safety release valve 3' and a pressure transducer 6 for sensing the pressure of air within the air tank 27. The outlet of the air tank 27 is piped through to the membrane unit 15 and is then split between two duct circuits 29a and 29b and then merged to enter the room 19 via a common duct 31 . Each of these duct circuits 29a and 29b are controlled by solenoid valves, a normally open solenoid valve 7 in the duct circuit 29a and a normally closed solenoid valve 8 in the duct circuit 29b.

The duct circuit 29a delivers air directly from the air tank 27 to the confined space 17 of the room 19; and the duct circuit 29b delivers air from the air tank 27 via a membrane treatment system to the confined space 17 of the room 19.

The membrane treatment system of the membrane unit 15 comprises: a two-stage dryer 9; a filter 10; a pair of nitrogen membrane modules 33 housed within a membrane cabinet 35; a flow control valve 37; and a check valve 39. The membrane cabinet 35 is similar to the blower cabinet 21 , having doors 23' either side to access the contents of the membrane unit 15, and is disposed adjacent to the blower cabinet. The nitrogen membrane modules 33 are disposed vertically and are connected in parallel within the duct circuit 29a.

As shown in Figs 5 and 1 1 , each module: has a compressed air inlet 41 , which is connected to the outlet of the air pump 27 via the solenoid valve 8, flow two-stage dryer 9 and filter 10, which form the components of an air treatment system prior to delivery of the air to the modules 33. The air treatment system is disposed at the base end of the membrane cabinet 35. The membrane modules 33 also comprise a nitrogen outlet 43 that is disposed at the top end of the membrane cabinet; and a permeate vent 45 to evacuate oxygen enriched air from the membrane module. The nitrogen membrane modules 33 are of the type based on hollow fibre membrane technology, which makes it possible to separate air into nitrogen and an oxygen enriched stream. Thus, the membrane modules 33 are able to produce nitrogen from the compressed air that is delivered to them. The particular form of nitrogen membrane modules 33 used in the present embodiment are particularly designed with hollow fibres to make it possible to generate nitrogen from low compressed air pressures. Generally, it is known to operate these membrane modules at low pressures down to 6 bar, however, by using a number of membranes in a parallel configuration, it is possible to increase the surface area in contact with the incoming air flow and produce nitrogen in sufficient volumes at very low pressures such as 2 bar as in the case of the present embodiment.

As shown in Fig. 12 of the drawings, a nitrogen membrane module 33 essentially comprises a coarse coalescing filter F1 , a fine coalescing filter F2, a bed type carbon adsorber C and a dust carry-over filter F3. As shown in Fig. 5 of the drawings, the nitrogen outlets 43 of each of the modules are conjoined into a single outlet duct of the duct circuit 29b, which is passed through a flow control valve 37 and a check valve 39 to regulate flow before entering the confined space 17 of the room 19. In operation, essentially once the air leaves the air tank 27 and passes through the membrane unit 15, it is directed via the duct circuit 29a directly into the confined space 17 via the valve 7 and the common duct 31 , and via the duct circuit 29b in a controlled manner at a very low pressure, typically at 2 bar pressure, via the valve 8. The membrane modules 33 in the duct circuit 29b separate the air at very low pressure to produce nitrogen at a minimum rate of 1000 litres per minute per membrane with a maximum of three membranes at 90 % purity.

Importantly, air received from the air pump 27 and passed along the duct circuit 29b, passes through the air treatment system including the two-stage dryer 9 and filter 10. The dryer 9 includes a primary cooling stage 9a that typically cools the air down from at or near 120°C from when it leaves the air pump 27 to at or near 30°C, and a secondary dryer stage 9b that works by cooling the air further down to at or near 3°C. It then uses incoming air to reheat the air on the way out, passing through the filter 10, to provide a pressure dewpoint of between 3-8°C. This provides two stage cooling and filtering of the air prior to passing through the membrane modules 33, which is critical to limit all moisture carried in the air from entering the membrane modules. This is necessary as bulk water/hydrocarbons over time will reduce the efficiency of the membrane function.

The reason behind adopting a two stage cooling process is that the secondary dryer is of the refrigerated type to get the temperature down to 3°C, but refrigerated air dryers cannot work with inlet temperatures above 60°C. To ensure system efficiency the first stage cooler 9a was devised to initially reduce the pump outlet temperature from 120°C to 30°C with no pressure drop. The secondary refrigerated dryer 9b is then capable of working within specifications and reduce pressure dewpoint to between 3-8°C.

After leaving the dryer 9, the air with an air pressure dewpoint of 3-8°C is filtered by passing through the filter 10, which is of the activated carbon type, to remove all hydrocarbons which in turn would cause efficiency losses in the membrane modules 33 if left untreated, and then input into the membrane modules 33.

The outgoing nitrogen gas produced by the membrane modules 33 is then entered into the common duct 31 in a controlled manner via the flow control valve 37 and the check valve 39 and directed into the confined space 17 of the room 19.

As shown in Fig. 5, control of the hypoxic system is effected by the control circuit 20, which includes an oxygen and carbon dioxide sensor 47 connected directly to the confined space 17 of the room 19 for measuring the oxygen and carbon dioxide content within the confined space. The control circuit 20 also includes a programmable logic controller (PLC) 49 to which the oxygen and carbon dioxide sensor 47 is connected. The PLC 49 in turn is connected to the blower 1 . The PLC 49 thus effectively controls and varies operation of the blower 1 . The PLC 49 is connected as part of an electrical board 51 that is housed within the blower unit 13. The PLC 49 is also connected to the solenoid valves 7 and 8 and the flow control valve 37 to control the operation of each of these devices in a negative feedback loop according to a control program designed for the hypoxic system 1 1 . This control program is designed to deliver either nitrogen at 90 percent purity or normal air at 20.9 percent nitrogen purity to the confined space 17, depending on the level of oxygen in the confined space as measured by the oxygen and carbon dioxide sensor 47.

Operation of the control circuit 20 is built around the design of a set point corresponding to the desired level of oxygen content in the confined space. This oxygen level corresponds to the amount of oxygen that would be absorbed by a person at a particular altitude due to the effects of the partial pressure of the atmosphere at that altitude. A table and graph of the corresponding sea level oxygen content to equate to the oxygen absorbed at increasing altitudes as a percentage of oxygen in the air is shown at Table 3 and pictorially depicted in Graph 3.

The set point of oxygen content for the particular altitude level being simulated is selected by an operator externally and is stored within the PLC 49. The PLC 49 can be used in situ or can be monitored remotely to control the nitrogen percentage content being delivered into the confined space 17 within the room 19 and thus control the level of oxygen with the room.

.¾ft¾sde Sestevei Air

H588S 21%

8SS

2i¾G 7Sfi%

3SSG 7¾SS ;s¾

43£S2

S330 il¾

i

s¾

&30S3 37S* &%

SSSG %

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TABLE 3 % 02 In Air

GRAPH 3

When the oxygen and carbon dioxide sensor 47 senses oxygen content higher than the set point, the hypoxic system 1 1 will deliver nitrogen to the confined space 17 at a rate of 100 litres per minute at 90 percent nitrogen purity. When the oxygen and carbon dioxide sensor 47 senses oxygen content lower than the set point, then the hypoxic system will deliver normal air into the confined space at a rate of 1000 litres per minute at 20.9 percent nitrogen purity.

The blower 1 is controlled to operate at full capacity for delivering nitrogen into the confined space 17, but only half capacity when normal air is being directed into the confined space. The second embodiment is substantially similar to the first embodiment except rather than having two nitrogen membrane modules connected in parallel to form the membrane unit 15 and be connected to the blower unit, there are four nitrogen membrane modules 33' that are connected in parallel. This arrangement provides four times the surface area of the hollow fibre membranes for the purposes of generating a larger volume of nitrogen necessary for a larger room.

It should be noted that with respect to both embodiments of the invention, a larger surface area of membrane is required than would otherwise be the case when operating a hypoxic system at very low air pressure ranges in the order of 2 bar. An important advantage of the invention is that by using very lower pressures in the order of 2 bar pressure, power consumption of the hypoxic system can be reduced by up to 70 percent compared to hypoxic systems of known design. The huge commercial advantage of this is that the system will be able to be installed in most public gymnasium applications, where the weight and size of the system is less than half of that of prior art systems, with the additional benefit of offering energy running costs in the order of 70 percent less than those that can be provided by prior art systems. It should be appreciated that the scope of the present invention is not limited to the particular embodiments described and that variations or modifications to the system can be made without departing from the spirit or scope of the invention.

Claims

CLAIMS:

1 . A hypoxic system for delivering depleted oxygen breathing gas to a space including: a low pressure blower unit for generating air at very low pressure; and a low pressure membrane unit having sufficient surface area to produce enough nitrogen for delivering hypoxic gas to the space with enough oxygen content to still function as a breathing gas.

2. A hypoxic system as claimed in claim 1 , wherein the very low pressure is in a range of 1 to 3 bar and is ideally 2 bar.

3. A hypoxic system as claimed in claim 1 or 2, including control means to sense the oxygen content within the space and control the operation of the blower and the flow rate of the hypoxic gas as well as the proportion of hypoxic gas to air being delivered to the confined space to maintain the oxygen content therein at a desired set point.

4. A hypoxic system as claimed in any one of the preceding claims, wherein the low pressure membrane unit includes an air treatment system prior to delivering air to a membrane module for producing the nitrogen for delivering the hypoxic gas, the air treatment system including a dryer and a filter.

5. A hypoxic system as claimed in claim 4, wherein the dryer is a two-stage dryer comprising a primary cooling stage to cool the air down to a temperature near or at 30°C, and a secondary refrigerated dryer stage that cools air down to at or near 3°C.

6. A hypoxic system as claimed in claim 4 or 5, wherein the filter is an activated carbon filter to limit moisture and hydrocarbons from being passed through to the membrane module.

7. A method for delivering depleted oxygen breathing gas to a space including: generating air at very low pressure and producing enough nitrogen therefrom to form a hypoxic gas; and delivering the hypoxic gas to the space with enough oxygen content to still function as a breathing gas.

8. A method as claimed in claim 7, including sensing the oxygen content within the space and controlling the pressure and flow rate of the air pressure generation as well as the proportion of hypoxic gas to air being delivered to the confined space to maintain the oxygen content therein at a desired set point.

9. A method as claimed in claim 7 or 8, including cooling and drying the air in two stages prior to producing nitrogen therefrom.

10. A method as claimed in claim 9, including filtering the air prior to producing nitrogen therefrom.

F.R. PULFORD AND SON PTY LTD

KROUZER IP

P1041 PCAU