Dual-stage compression oxygen concentrator

Abstract

Title of the Invention: Dual-Stage Compression Oxygen Concentrator. The invention relates to a dual-stage compression oxygen concentrator. Air compression means (10) compress ambient air to obtain compressed air, and air separation means (20) produce a gas stream containing at least 70% vol. oxygen from the compressed ambient air. The air compression means (10) comprise an electric motor (11) including a drive shaft carrying two vanes (14) arranged on either side of the electric motor (11) to provide two compression stages. The electric motor (11) drives the drive shaft and the two vanes (14) in rotation. Abstract Figure: Figure 1

Description

Title of the invention: Dual-stage compression oxygen concentrator

[0001] The invention relates to a two-stage compression oxygen concentrator for producing oxygen in-situ from ambient air.

[0002] There are currently several ways to produce and supply gaseous oxygen, including oxygen used in the field of health.

[0003] When oxygen requirements are high, i.e., when high flow rates are needed, existing solutions include producing oxygen at a production facility and supplying it to the site of use, such as a hospital or similar establishment, either by cylinders or racks, or by tanker truck with distribution via pipeline(s), typically through a network of pipes installed within the hospital. However, pressurized oxygen cylinders are heavy and difficult to move, which complicates their handling by healthcare personnel and can lead to injuries. Furthermore, these solutions generate risks and costs associated with transporting oxygen from its production site to its site(s) of use.

[0004] Conversely, when oxygen requirements are moderate or low, it is known to produce oxygen directly on-site, i.e., in-situ within the hospital, using a device that utilizes ambient air to produce oxygen, commonly referred to as an oxygen concentrator. This technology eliminates some of the aforementioned risks or constraints. However, current concentrators, which generally operate with pistons to compress the air, are typically noisy and provide only a very limited flow rate of oxygen.

[0005] Supply is therefore a significant constraint in the use of oxygen in a hospital setting.

[0006] The problem then becomes one of proposing an improved oxygen concentrator.

[0007] One solution of the invention relates to an oxygen concentrator comprising air compression means for compressing ambient air and obtaining compressed air, and air separation means for producing a gas stream containing at least 70% vol. of oxygen from the compressed ambient air supplied by the air compression means.

[0008] Furthermore, the air compression means comprise an electric motor including a drive shaft carrying two finned wheels arranged on either side of the electric motor, said electric motor being configured to drive the drive shaft and the two finned wheels in rotation, during the operation of the motor, each a finned wheel being arranged in a volute, the two volutes being arranged in series so that the compressed air within one volute supplies the other volute.

[0009] Depending on the embodiment considered, the oxygen concentrator of the invention may comprise one or more of the following features: - in operation, the two finned wheels simultaneously draw in air, so as to ensure two successive levels of air compression. - the two volutes each comprise an internal chamber containing a finned wheel so that the second volute draws compressed air from the internal chamber of the first volute into its internal chamber. - the means of air separation include a PSA (pressure swing adsorption) unit with pressure-modulated adsorption. - it also includes cooling means configured to cool the electric motor. - it also includes means of power supply to provide electric current (at least) to the electric motor. - each finned wheel is arranged individually in the internal compartment of a volute. - each volute includes an air inlet and an air outlet. - the electric motor is arranged between the two finned wheels, i.e. sandwiched. - the two finned wheels constitute successive air compression stages, namely a first stage and a second compression stage. - the motor shaft passes through the electric motor. - the means of power supply include an electrical connection to the mains (110 / 220V) or a rechargeable electric battery. - the engine cooling means include a cooling chamber supplied with a heat transfer fluid. - the engine cooling means comprising a cooling block including a cooling chamber containing the electric motor. - the cooling chamber is arranged in the cooling block and supplied with heat transfer fluid. - the engine is arranged in the cooling chamber and cooled by heat exchange with the heat transfer fluid. - it includes one or more heat exchangers to ensure cooling of the compressed air produced by one and / or the other of the two vane wheels, preferably a heat exchange with the ambient atmosphere. The two volutes containing the finned wheels are arranged in series so that the gas compressed once, within the first volute, feeds the second volute to undergo a second compression. It includes a first gas circuit fluidly connecting the air outlet of the first volute to the air inlet of the second volute. The first gas circuit is arranged between the air outlet of the first volute and the air inlet of the second volute. It also includes a second gas circuit arranged between the air outlet of the second volute and the supply inlet of the air separation means, i.e. of the PSA unit. the second gas circuit fluidly connects the air outlet of the second volute to the supply inlet of the air separation means. The PSA unit comprises at least two adsorbers arranged in parallel. One of the adsorbers is in the adsorption phase, while the other is in the desorption or regeneration phase. Each adsorber contains at least one adsorbent, preferably arranged in an adsorption bed. said adsorbent comprises at least one layer of zeolite particles, preferably a zeolite X exchanged by metallic cations, in particular calcium or lithium, for example a zeolite LSX exchanged at least 88% by Li cations. The layer of zeolite particles is used to preferentially adsorb nitrogen and thus allow oxygen to pass through. said adsorbent comprises at least one layer of activated alumina particles used to remove at least some of the water vapor contained in the supply air. Preferably, the activated alumina particle layer is arranged upstream of the zeolite layer, considering the direction of gas flow in each adsorber. The air separation means are configured to produce a gas stream containing at least 80% vol. oxygen, preferably at least 90% vol. oxygen. It includes air purification means arranged upstream of air compression means to purify the air, that is to say to eliminate dust, aerosols or other pollutants that may be present in it. Air purification means include at least one filter, for example a high efficiency HEPA (High Efficiency Particulate Air) type filter or similar. - before compression, the air is at atmospheric pressure, i.e. approximately 1 bar. - after the first compression carried out within the first volute, we obtains compressed air at a pressure of at least approximately 1.2 bar. - after a second compression carried out within the second volute, compressed air is obtained at least at approximately 1.4 bar.

[0010] The invention will now be better understood with reference to the following detailed description, given by way of illustration but not limitation, with reference to the accompanying figures, among which:

[0011] [Fig-1] schematically represents an oxygen concentrator according to the invention.

[0012] [Fig.2] schematically shows a cooling block for the electric motor of the concentrator of [Fig.1],

[0013] [Fig.3] schematically shows the cooling block of [Fig.2] arranged around the electric motor.

[0014] [Fig.1] schematically represents an oxygen concentrator 1 according to the invention comprising air compression means 10 for compressing ambient air and obtaining compressed air, and air separation means 20 for producing a gas stream containing at least 70% vol. of oxygen from the compressed ambient air supplied by the air compression means 10.

[0015] The air compression means 10 comprise an electric motor 11 including a motor shaft 11.1 carrying two finned wheels 14 arranged on either side of the electric motor 11, i.e. taking the electric motor 11 in a “sandwich”.

[0016] The two finned wheels are themselves arranged in the internal compartment of two volutes 12, 13 which each include an air inlet and an air outlet.

[0017] In operation, the electric motor 11 is configured to drive the motor shaft in rotation and therefore the two finned wheels 14, which generates an air intake by the finned wheels 14.

[0018] The ambient air, which can be pre-filtered by a HEPA or similar type filter 30, first enters the first volute 12, via an air inlet fitting 12.1 and then exits through an air outlet fitting 12.2 after having been compressed once (first compression stage El) within the first volute 12 due to the rotations applied to the first vane wheel 14 located there.

[0019] Next, the compressed air is drawn in by the second vane wheel 14 which is located in the second volute 13 where it enters via an air inlet fitting 13.1 and undergoes a second compression (second compression stage E2), before exiting through an air outlet fitting 13.2 and being conveyed to the air separation means 20.

[0020] A first gas circuit 15, such as a conduit or the like, fluidly connects the air outlet 12.2 of the first volute 12 to the air inlet 13.1 of the second volute 13, and allows compressed air to be conveyed from the first compression stage El to the second compression stage E2, that is to say from the first to the second volute 12, 13.

[0021] Each of the wheels can have a diameter of approximately 35 to 60 mm. Preferably, they are driven at a rotational speed of at least 50,000 rpm, preferably at least 80,000 rpm. They carry fins or blades on one of their two faces, preferably the blades are inclined or angled.

[0022] Similarly, a second gas circuit 16, such as a conduit or the like, fluidly connects the air outlet 13.2 of the second volute 13 to the supply inlet 21 of the air separation means 20, such as a PSA unit.

[0023] Heat exchangers 35 are preferably arranged on the first and second gas circuits 15, 16 in order to cool the compressed air circulating there, for example by operating a heat exchange with the ambient atmosphere.

[0024] The air separation means 20 preferably comprise a PSA unit with two adsorbers 22.1, 22.2 arranged in parallel. Advantageously, one 22.1 of the adsorbers is in the adsorption phase, while the other 22.2 is in the desorption or regeneration phase, and vice versa.

[0025] Each adsorber 22.1, 22.2 contains one or more adsorbents, preferably arranged in an adsorption bed.

[0026] For example, at the inlet, a layer of activated alumina particles can be arranged to remove at least part of the water vapor contained in the feed air, followed by a layer of zeolite particles, such as a zeolite X exchanged by metallic cations, in particular calcium or lithium, for example a zeolite LSX exchanged at least 88% by Li cations, serving to preferentially adsorb nitrogen, and thus to allow oxygen to pass through in order to produce the desired oxygen-rich gas flow, typically at least 80% vol. oxygen, preferably at least 90% vol. oxygen.

[0027] The oxygen produced exits the PSA unit through an oxygen outlet 23. It can then be used within the hospital to supply a patient in need.

[0028] Of course, the PSA unit and / or the gas lines connected to it can be equipped with flow control means, such as valves, typically piloted solenoid valves.

[0029] According to one embodiment, in order to ensure better cooling of the electric motor 11, the latter can be arranged in a cooling chamber 42 fitted in a sealed block 40, for example made of metal, containing a heat transfer fluid (e.g. liquid) which bathes the contours of the electric motor 11, as illustrated in [Fig.2].

[0030] The heat transfer fluid is conveyed by conduits 41 arranged in the block 40, allowing the fluid to be brought into the cooling chamber 42, i.e. that is to say in contact with the motor 11, then to evacuate it after it has been heated by heat exchange (of calories) with the motor 11 within the cooling chamber 42. Sealing gaskets 43 ensure the sealing of the assembly.

[0031] A convenient passage or drilling in the block 40 allows the electrical power supply and control cables of the motor 11 to pass through.

[0032] Power is supplied by the 110 / 220V mains supply or a rechargeable battery.

[0033] As illustrated in [Fig.3], in order to make the cooling chamber 42 and insert the motor 11 carrying the volutes 12, 13 containing the finned wheels 14, the block 40 is advantageously formed of several sub-parts assembled to each other, for example of a first half-block 40.1 fixed by screwing to a second half-block 40.2.

[0034] The concentrator 1 of the invention also includes control means for controlling the operation of the motor 11 or for performing other functions, such as opening or closing valves or other things, such as controlled solenoid valves.

[0035] The elements forming the concentrator 1 of the invention can be incorporated within a housing.

[0036] Tests carried out have shown that if the ambient air drawn in at the inlet is at 23°C and atmospheric pressure (1 bar), then: - after the first compression El, we obtain air at 1.2 bar, and - after second compression E2, we obtain air at 1.4 bar.

[0037] The air temperature is cooled within the two exchangers 35, to approximately 32°C after the first compression El, then to approximately 40°C after the second compression E2.

[0038] It is recommended to cool the air, particularly between the two compression stages El, E2, because the air heats up when compressed, especially in the first stage El, and this heating reduces the compression performance of the following stage, i.e. the second stage E2. Indeed, more energy is required to compress a "cold" gas than to compress a "warmer" gas.

[0039] According to one embodiment, the heat exchanger(s) 35 have an elongated body, preferably with a square or rectangular cross-section. Their body may comprise a plurality of juxtaposed channels with a square or rectangular cross-section, for example, 5 mm x 6 mm, for a length of approximately 325 mm. Such dimensions ensure efficient heat exchange. Thus, it has been measured that each heat exchanger 35 allows for a cooling of approximately 25 to 30°C of the air passing through it.

[0040] Preferably, in order to limit the noise generated by the air intake, a noise attenuating device, i.e. a "silencer", can be arranged at the air inlet, typically upstream of the filter 30.

[0041] A concentrator 1 according to the invention can be used to produce oxygen from ambient air directly on a hospital or other site.

Claims

Demands

1. Oxygen concentrator comprising: - air compression means (10) for compressing ambient air and obtaining compressed air, and - air separation means (20) for producing a gas stream containing at least 70% vol. of oxygen from the compressed ambient air supplied by the air compression means (10), characterized in that the air compression means (10) comprise an electric motor (11) comprising a motor shaft carrying two vane wheels (14) arranged on either side of the electric motor (11), said electric motor (11) being configured to drive the motor shaft and the two vane wheels (14) in rotation, during the operation of the motor (11), each vane wheel (14) being arranged in a volute (12, 13), the two volutes (12, 13) being arranged in series so that the compressed air within one volute (12) supplies the other volute (13).

2. Oxygen concentrator according to claim 1, characterized in that the air separation means (20) comprise a pressure modulated adsorption PSA unit.

3. Oxygen concentrator according to claim 1, characterized in that it further comprises motor cooling means (40, 41, 42) comprising a cooling block (40) comprising a cooling chamber (42) containing the electric motor (H).

4. Oxygen concentrator according to claim 1, characterized in that it comprises a first gas circuit (15) fluidically connecting the air outlet (12.2) of the first volute (12) to the air inlet (13.1) of the second volute (13).

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