Compressed gas generator and method

Abstract

A hydraulic compressed gas generator, comprising a pressure vessel having a peripheral wall, an inlet through which gas is introducible and a perforated tube downwardly extending within an interior of the pressure vessel and through which a liquid is introducible for compressing a volume of introduced gas. A liquid jet is emittable from each aperture of the perforated tube and is impingable upon the peripheral wall to produce an atomized spray that is capable of sufficiently absorbing heat dissipated from the volume of gas being compressed to achieve substantial isothermal compression. The pressure vessel additionally has an outlet through which the compressed gas is deliverable to a gas receiving tank.

Description

[0001] COMPRESSED GAS GENERATOR AND METHOD

[0002] Field of the Invention

[0003] The present invention relates to the field of compressed gas generation. More particularly, the invention relates to a hydraulic compressed gas generator and method.

[0004] Background of the Invention

[0005] Compressed air is of important commercial value, being used for example to provide motive power for power tools, breathing gas for underwater divers and power storage and transmission. Industrial compressors generally comprise two intermeshing helical screws, and air is drawn within pockets between the two screws and is compressed. However, oil is used for sealing, cooling and lubrication, and oil vapor will be introduced into the compressed air as the lubricated oil heats up during operation of the compressor. Compressed air contaminated by oil is not suitable for certain processes such as medical procedures, food processing and electronic manufacturing for which air quality has much significance.

[0006] Other disadvantages of industrial compressors include their low energy efficiency due to heat dissipation, high noise level, limited life span and high maintenance costs due to the complicated construction.

[0007] It is an object of the present invention to provide a compressed air generator that is oil-free.

[0008] It is an additional object of the present invention to provide a compressed air generator that is subjected to a significantly lower level of heat dissipation than a prior art product.

[0009] It is an additional object of the present invention to provide a compressed air generator that is more cost effective than a prior art product.

[0010] Other objects and advantages of the invention will become apparent as the description proceeds.

[0011] Summary of the Invention

[0012] A hydraulic compressed gas generator comprises a pressure vessel having a peripheral wall, an inlet through which gas is introducible and a perforated tube downwardly extending within an interior of the pressure vessel and through which a liquid is introducible for compressing a volume of introduced gas, wherein a liquid jet is emittable from each aperture of the perforated tube and is impingable upon the peripheral wall to produce an atomized spray that is capable of sufficiently absorbing heat dissipated from the volume of gas being compressed to achieve substantial isothermal compression, and wherein the pressure vessel additionally has an outlet through which the compressed gas is deliverable to a gas receiving tank.

[0013] As referred to herein," substantial isothermal compression" means a change in temperature of up to 5%, for example 3.5%.

[0014] In one aspect, the perforated tube has an occluded bottom surface.

[0015] In one aspect, the pressure vessel is cylindrical and the perforated tube extends downwardly from a central region of an upper surface of the pressure vessel, and wherein a radius of the pressure vessel is sufficiently small to ensure that the liquid jet emitted from each aperture of the perforated tube will impinge upon the peripheral wall.

[0016] In one aspect, the perforated tube is formed with vertically spaced apertures arranged such that a vertical spacing of lower adjacent apertures located closer to the bottom surface of the perforated tube than to the upper surface of the pressure vessel is significantly greater than the vertical spacing of upper adjacent apertures located closer to the upper pressure vessel surface than to the bottom perforated tube surface, to increase a density of atomized sprays produced by the liquid jets emitted from the upper apertures relative to the density of atomized sprays produced by the liquid jets emitted from the lower apertures and to thereby enhance heat dissipation when an upper surface of a body of liquid accumulated from each of the emitted liquid jets is located above at least some of the lower apertures.

[0017] In one aspect, the compressed gas generator comprises first and second pressure vessels, wherein a body of liquid is cyclically transferable between the first and second pressure vessels and is introducible through the pressure vessel interior via a corresponding perforated tube to compress a volume of introduced gas without significantly increasing in temperature. In one aspect, the compressed gas generator further comprises a pump for delivering a volume of liquid from a liquid source to the first pressure vessel when the first and second pressure vessels are devoid of liquid and for transferring liquid from the first pressure vessel to the second pressure vessel.

[0018] In one aspect, the compressed gas generator further comprises a plurality of pumps for cyclically transferring liquid between the first and second pressure vessels, wherein each of said plurality of pumps has a different capacity and only one of said plurality of pumps that delivers liquid at a greater pressure than the pressure of the generated compressed gas is in operation at any given time.

[0019] In one aspect, the outlet of the first and second pressure vessels through which the compressed gas is deliverable to the gas receiving tank is selectively occludable and openable by a gas outlet valve.

[0020] In one aspect, the compressed gas generator is multi-stage, wherein each stage of the multi-stage compressed gas generator comprises the first and second pressure vessels, and wherein the compressed gas generated by a first stage of the multi-stage compressed gas generator is deliverable to a second stage of the multi-stage compressed gas generator and is increasingly compressed.

[0021] In one aspect, the compressed gas generator further comprises a plurality of selectively interconnectable gas receiving tanks.

[0022] A method of generating compressed gas comprises the steps of introducing gas from a gas source into a pressure vessel having a peripheral wall; introducing liquid through a perforated tube having an occluded bottom surface that extends downwardly from an upper surface of the pressure vessel; and emitting a liquid jet from each aperture of the perforated tube to cool a volume of gas present within an interior of the pressure vessel and to provide an accumulated body of liquid that displaces and compresses the volume of gas, wherein one or more of the emitted liquid jets produce an atomized spray following impingement upon the peripheral wall that is capable of sufficiently absorbing heat dissipated from the volume of gas being compressed to achieve substantial isothermal compression. In one aspect, the method further comprises the steps of opening a gas outlet provided in the pressure vessel and delivering the compressed gas to one or more gas receiving tanks.

[0023] In one aspect, the method further comprises the steps of providing first and second pressure vessels and cyclically transferring the body of liquid between the first and second pressure vessels while introducing the transferred body of liquid through the pressure vessel interior via a corresponding perforated tube to compress the volume of gas without significantly increasing in temperature.

[0024] In one aspect, a residual volume of compressed gas at a same pressure as the pressure within the one or more gas receiving tanks remains within the interior of the pressure vessel to which the body of liquid was transferred following the compressed gas delivering step, the method further comprising the step of opening a recirculation valve at a bottom region of each of the first and second pressure vessels, allowing the residual volume of compressed gas to apply a force onto the accumulated body of liquid and to cause a portion of the accumulated body of liquid to flow through a flow path that includes recirculation conduits passing through the recirculation valves and that extends to the interior of the other pressure vessel due to the pressure differential between the first and second pressure vessels until the pressure within the interior of the first and second pressure vessels equalizes.

[0025] In one aspect, the method further comprises the step of operating a pump to deliver a remaining portion of the accumulated body of liquid from a bottom portion of the pressure vessel within which the body of liquid accumulated to a top portion of the other pressure vessel.

[0026] In one aspect, the liquid is water and the gas is air.

[0027] In one aspect, the liquid is an ionic liquid and the gas is hydrogen.

[0028] The method according to claim 11, wherein the gas is compressed at a temperature below 0°C.

[0029] In one aspect, the gas is delivered to the one or more gas receiving tanks at a temperature close to an ambient temperature and a dryer operates between the ambient temperature and a condensing temperature of the liquid to discharge condensed liquid from the compressed gas stored in the one or more gas receiving tanks.

[0030] Brief Description of the Drawings

[0031] In the drawings:

[0032] Fig. 1 schematically illustrates hydraulic compressed air generator, according to an embodiment of the invention;

[0033] Fig. 2 schematically illustrates a water jet issuing from each aperture provided in a perforated tube of a pressure vessel, according to an embodiment of the invention;

[0034] Fig. 3 schematically illustrates hydraulic compressed air generator, which comprises three pumps, each operating with a different capacity, according to an embodiment of the invention;

[0035] Fig. 4 schematically illustrates two-stage hydraulic compressed air generator, according to an embodiment of the invention;

[0036] Fig. 5 schematically illustrates the selective interconnection of air receiving tanks, according to an embodiment of the invention;

[0037] Fig. 6 is a graph of three compression curves for different heat capacity ratios, plotted as a function of gauge pressure vs. time; and

[0038] Fig. 7 shows a graph of the air temperature over time in a compression cycle for one of the curves of Fig. 6.

[0039] Detailed Description of the Invention

[0040] In conjunction with the novel hydraulic compressor, ambient air and a supply of water are introduced into a closed pressure vessel. As an additional amount of water is supplied to the pressure vessel, the air becomes additionally compressed. Upon achieving a pressure threshold, the compressed air is discharged from the pressure vessel to one or more air receiving tanks adapted to supply compressed air at a predetermined pressure to desired equipment. Despite the significantly great heat of compression to which air is subjected upon being compressed, the hydraulic compressor is advantageously configured to isothermally compress the enclosed air with the introduced water supply, thereby increasing energy efficiency and reducing costs.

[0041] Although the following description refers to the compression of air by means of an introduced volume of water, it will be appreciated that the invention is suitable for the compression of other gases supplied from a gas source by means of another type of introduced liquid supplied from a liquid source.

[0042] Fig. 1 schematically illustrates hydraulic compressed air generator 10 according to one embodiment. Hydraulic compressed air generator 10 comprises two pressure vessels 6 and 7, into each of which a compression-inducing supply of water from a water source 2 is cyclically introduced and discharged. The supply of water is delivered by a single pump 4, e.g. a centrifugal pump, via water intake conduit 1 and discharge conduit 3. Discharge conduit 3 branches into injection conduits 11 and 12 for introduction of water from source 2 into pressure vessels 6 and 7, respectively. Supplementary water is also introducible via supplementary water source 42 to one of the pressure vessels, for example pressure vessel 6. Each of pressure vessels 6 and 7 is equipped with a pressure gauge 14 that senses the pressure within the interior of the pressure vessel. Pressure gauge 14 may be a differential pressure gauge that comprises a first pressuresensing element A for sensing the hydrostatic pressure of water introduced within a lower region of the pressure vessel interior and a second pressure-sensing element B for sensing the pressure of a volume of air located at an upper region of the pressure vessel interior. The difference between the pressure readings provided by first element A and second element B is indicative of the current water level. Alternatively, a different type of pressure gauge or pressure sensor, such as an absolute pressure gauge, may be used. Pressure vessels 6 and 7 may be made of a metallic material such as stainless steel, or any other structurally strong material.

[0043] The water introduced into one of the pressure vessels is transferable to the other pressure vessel through recirculation conduits 44-46. Recirculation conduit 46 extends for example from pressure vessel 6 to water intake conduit 1.

[0044] Ambient air is filtered by air filter 22 and is introduced to one or more of pressure vessels 6 and 7 after flowing through inlet conduits 23 and 24, respectively, extending from the outlet side of air filter 22. The generated compressed air is discharged from pressure vessels 6 and 7 via outlet conduits 26 and 27, respectively, and common conduit 28 until being received by the one or more air receiving tanks 33. The one or more air receiving tanks 33 provide temporary storage for the generated compressed air at a constant pressure which is generally greater than an anticipated peak demand required by desired equipment. When two or more air receiving tanks 33 are employed, they may be interconnected in order to maintain a large-volume constant pressure that is suppliable to the desired equipment.

[0045] One sequence of water and air transfer to and from pressure vessels 6 and 7 will now be described. A controller 5 commands selective operation of the pump and control valves. It will be appreciated that other sequences as well are suitable to be initiated in conjunction with hydraulic compressor 10. Each of the sequences may be initiated by manually operating the pump and valves which are each a substitute for a control valve. While all valves are closed, filter isolation valve 21 and valves 16 and 17 operatively connected to inlet air conduits 23 and 24, respectively, are momentarily opened to ensure that an adequate volume of ambient air is introduced into the interior of pressure vessels 6 and 7. Valves 8 and 9 operatively connected to intake water conduit 1, valve 13 operatively connected to pump discharge conduit 3, and valve 19 operatively connected to water injection conduit 12 are opened. Pump 4 is then activated to facilitate introduction of water into pressure vessel 7. Since the openings of pressure vessel 7 are closed with the exception of water injection conduit 12, the volume of air within pressure vessel 7 is increasingly compressed by the continuously flowing injected water that causes the volume of air to become displaced and eventually reduced in volume. When the compressed air within pressure vessel 7 achieves a predefined pressure threshold, for example 10 bar, pump 4 is deactivated and valves 8, 9 and 19 are closed. Also, valve 37 operatively connected to air outlet conduit 1 is opened so that substantially all of the compressed air volume within pressure vessel 7 flows to the one or more air receiving tanks 33, with the exception of a residual volume of compressed air that remains at the same pressure as the one or more air receiving tanks. Valve 37 is then closed. The residual volume of compressed air remaining in pressure vessel 7 is advantageously used to reduce pumping costs. Valves 51 and 53 operatively connected to recirculation conduits 44 and 46, respectively, are opened, to provide a flow path through conduits 44-46 for the body of water in pressure vessel 7. The residual volume of compressed air applies a force onto the body of water within pressure vessel 7 and causes a portion of the latter to flow through conduits 44-46 to the interior of pressure vessel 6 due to the pressure differential therebetween until the pressure within the interior of pressure vessels 6 and 7 equalizes. Valve 53 is then closed. Both isolation valve 9 operatively connected to intake water conduit 1 between recirculation conduit 46 and pump 4 and valve 18 operatively connected to water injection conduit 11 are opened. A flow path is now established through recirculation conduits 44-45, the portion of recirculation conduit 46 between conduits 1 and 45, the portion of water intake conduit 1 between conduit 45 and pump 4, pump discharge conduit 3, and water injection conduit 11. Upon activating pump 4, the remaining volume of the body of water within pressure vessel 7 is suctioned by the pump and delivered through this newly established flow path to pressure volume 6. To prevent the generation of a vacuum within the interior of pressure vessel 7 while the body of water is being transferring to pressure vessel 6, filter isolation valve 21 and valve 17 operatively connected to inlet air conduit 24 are opened to ensure that an adequate volume of ambient air is introduced into the interior of pressure vessel 7. After the water introduced into pressure vessel 6 compressed the volume of air within its interior to the predefined pressure threshold, valve 36 operatively connected to air outlet conduit 26 is opened so that substantially all of the compressed air volume within pressure vessel 6, with the exception of a residual volume of compressed air, flows to the one or more air receiving tanks 33. After all water has been transferred from pressure vessel to pressure vessel 6, pump 4 is deactivated and valves 9, 17, 18, 21 and 51 are closed. These steps are cyclically repeated whereby a volume of water is transferred from one pressure vessel to the other during each cycle while a volume of compressed air is correspondingly generated and delivered to the one or more air receiving tanks, until the pressure within the one or more air receiving tanks achieves the predetermined pressure.

[0046] In one embodiment, each of pressure vessels 6 and 7 is configured with a perforated tube 56 extending downwardly from a central region of an upper pressure vessel surface 54 and that has an occluded bottom surface 59. The central region of upper pressure vessel surface 54 is configured with an opening with which a corresponding injection conduit interfaces in order to introduce a suitable amount of water into the pressure vessel. A plurality of apertures 57 are formed throughout the length and along the periphery of tube 56. During injection of water into each pressure vessel, a water jet issues from each aperture 57 and absorbs the heat dissipated from the volume of air being compressed, assisting the hydraulic compressor to isothermally compress the volume of air retained within the interior of the pressure vessel.

[0047] Even though a volume of water is cyclically transferred from one pressure vessel to the other and is instrumental in contacting and displacing the retained volume of air during a compression operation to absorb the heat of compression, the temperature of the cyclically transferred water advantageously does not substantially increase.

[0048] Fig. 2 schematically illustrates a water jet 62 issuing from each aperture 57 provided in perforated tube 56 of a pressure vessel, for example the illustrated pressure vessel 6. Pressure vessel 6 has a radius R, generally measured from the axis of perforated tube 56 to the peripheral wall 58 of pressure vessel 6, which is sufficiently small to ensure that water jet 62 will impinge upon peripheral wall 58. In response to the impingement of water jet 62 upon peripheral wall 58, an atomized spray 64 with a sufficiently small liquid particle size for increasing heat flux is produced.

[0049] Without being bound to theory, atomized spray 64 facilitates mass, momentum, and energy transfers between the liquid particles and the air being compressed to enhance heat dissipation in the vicinity of peripheral wall 58. Additional heat absorption is made possible by the increasingly rising body of water 67 within pressure vessel 6 and by the emitted water jets 62 located below upper water surface 68 that also serve to minimize thermal gradients within body of water 67 and to provide a substantially uniform water temperature. Furthermore, the absorbed heat of compression is able to be radiated outwardly from the pressure vessel, particularly when the pressure vessel is made from metallic material. To further increase the ability to absorb the heat of compression, adjacent apertures 57 may be variably spaced. That is, the vertical spacing of lower adjacent apertures located close to bottom surface 59 of perforated tube 56 is significantly greater than the vertical spacing of upper adjacent apertures located close to upper pressure vessel surface 54. The relatively small spacing between adjacent upper apertures increases the density of atomized sprays 64 within the compressed air volume and enhances heat dissipation when the upper water surface 68 is relatively high and the number of apertures located above the water surface is reduced.

[0050] Fig. 3 schematically illustrates hydraulic compressed air generator 70, which is similar to hydraulic compressed air generator 10 of Fig. 1 but which comprises three pumps 71-73, each operating with a different capacity.

[0051] Fig. 4 schematically illustrates two-stage hydraulic compressed air generator 90. Generator 90 comprises the first stage generator 10, and the compressed air generated thereby is delivered to the second-stage generator 110, which is identical to first stage generator 10 with the exception of air filter 22, to further increase the pressure of the generated compressed air, for example achieving a predefined pressure threshold of 40 bar. The generated second-stage compressed air is stored within the one or more air receiving tanks 33.

[0052] Fig. 5 schematically illustrates the selective interconnection of air receiving tanks 33a-e. The air inlet of each of air receiving tanks 33a-e is in fluid communication with air outlet conduit 127 of the second-stage generator, or alternatively with the air outlet conduit of a one-stage generator, by parallel conduits 181a-e and by corresponding isolation valves 183a-e, respectively. The air outlet of each of air receiving tanks 33a-e is in fluid communication with conduit 187 leading to desired equipment 199 by parallel conduits 191a-e and by corresponding isolation valves 193a-e, respectively. A water discharge system dryer 194 is provided to discharge condensed water from the stored compressed air. The energy efficiency of dryer 194 is significantly less the energy consumption of a dryer needed by the prior art by virtue of the lower air temperature achieved by the compressed air generator of the present invention.

[0053] Figs. 6-7 demonstrate that air is isothermally compressed by the hydraulic compressed air generator of the present invention. Two identical cylindrical pressure vessels were used, each having a volume of 1 m3, a height of 2.4 m and a diameter of 0.57 m, although any other height to diameter ratio of 4-5 is also suitable. The perforated tube had a height equal to a product ranging from 0.8-0.9 of the height of the pressure vessel and a diameter of 2 inches. Each aperture formed in the perforated tube had a diameter ranging from 1 mm - 10 mm. 60 apertures were formed in the perforated tube, and were arranged in 10 vertically spaced rows such that the 6 apertures in each row were equidistantly spaced around the periphery of the tube. The bottom three rows were used for emitting water jets at the bottom of the pressure vessel, and the upper 7 rows were used for emitting water jets at the upper region of the pressure vessel. The vertical spacing between adjacent upper rows was less than the vertical spacing between adjacent bottom rows.

[0054] One pump was used to transfer water from one pressure vessel to the other, and was suitable to deliver water at a pressure of 7 bar and at a capacity of 15 kW, so that the emitted water jets were capable of impinging upon the peripheral wall of a pressure vessel and producing an atomized spray.

[0055] In Fig. 6, three compression curves F, G and H were plotted as a function of gauge pressure vs. time. The compression curves are plotted for a reversible adiabatic process during which air was compressed and are represented by the equation PV = constant, where P is pressure, V is volume and k is heat capacity ratio, or the ratio of heat capacity at constant volume to the heat capacity at constant pressure.

[0056] As a comparison, curve F was plotted when a conventional compressor having a heat capacity ratio of 1.4 was operated. The air was compressed to 7 bar within 1.8 min. Curve G was plotted in conjunction with a heat capacity ratio of 1.2, and air was compressed to 6.05 bar within 1.85 min.

[0057] Curve H was plotted in conjunction with the hydraulic air generator of the present invention. In an initial stage when water is introduced to the ambient pressure air, the air was compressed to 6 bar within 1.93 min. In an intermediate stage, the pressure of the compressed air remained substantially constant at 6 bar for another 0.4 min. In a discharge stage, the pressure of the compressed air was rapidly reduced to a substantially constant pressure of 1 bar. It follows from the intermediate stage that the heat capacity ratio is 1, thereby providing isothermal compression.

[0058] Fig. 7 shows a graph of the air temperature during the intermediate stage of a compression cycle using the hydraulic air generator of the present invention. It can be seen that there is no significant rise in the temperature of the compressed air, rising only from 21°C to 22.5°C within 2 min, a change of only 3.5%. In contrast, the compressed air would rise to a temperature of 180°C if compressed by an uncooled conventional compressor.

[0059] While some embodiments of the invention have been described by way of illustration, it will be apparent that the invention can be carried out with many modifications, variations and adaptations, and with the use of numerous equivalents or alternative solutions that are within the scope of persons skilled in the art, without exceeding the scope of the claims.

Claims

CLAIMS1. A hydraulic compressed gas generator, comprising a pressure vessel having a peripheral wall, an inlet through which gas is introducible and a perforated tube downwardly extending within an interior of the pressure vessel and through which a liquid is introducible for compressing a volume of introduced gas, wherein a liquid jet is emittable from each aperture of the perforated tube and is impingable upon the peripheral wall to produce an atomized spray that is capable of sufficiently absorbing heat dissipated from the volume of gas being compressed to achieve substantial isothermal compression, and wherein the pressure vessel additionally has an outlet through which the compressed gas is deliverable to a gas receiving tank.

2. The compressed gas generator according to claim 1, wherein the perforated tube has an occluded bottom surface.

3. The compressed gas generator according to claim 2, wherein the pressure vessel is cylindrical and the perforated tube extends downwardly from a central region of an upper surface of the pressure vessel, and wherein a radius of the pressure vessel is sufficiently small to ensure that the liquid jet emitted from each aperture of the perforated tube will impinge upon the peripheral wall.

4. The compressed gas generator according to claim 3, wherein the perforated tube is formed with vertically spaced apertures arranged such that a vertical spacing of lower adjacent apertures located closer to the bottom surface of the perforated tube than to the upper surface of the pressure vessel is significantly greater than the vertical spacing of upper adjacent apertures located closer to the upper pressure vessel surface than to the bottom perforated tube surface, to increase a density of atomized sprays produced by the liquid jets emitted from the upper apertures relative to the density of atomized sprays produced by the liquid jets emitted from the lower apertures and to thereby enhance heat dissipation when an upper surface of a body of liquid accumulated from each of the emitted liquid jets is located above at least some of the lower apertures.

5. The compressed gas generator according to claim 1, which comprises first and second pressure vessels, wherein a body of liquid is cyclically transferable between the first and second pressure vessels and is introducible through the pressure vessel interior via a correspondingperforated tube to compress a volume of introduced gas without significantly increasing in temperature.

6. The compressed gas generator according to claim 5, further comprising a pump for delivering a volume of liquid from a liquid source to the first pressure vessel when the first and second pressure vessels are devoid of liquid and for transferring liquid from the first pressure vessel to the second pressure vessel.

7. The compressed gas generator according to claim 6, further comprising a plurality of pumps for cyclically transferring liquid between the first and second pressure vessels, wherein each of said plurality of pumps has a different capacity and only one of said plurality of pumps that delivers liquid at a greater pressure than the pressure of the generated compressed gas is in operation at any given time.

8. The compressed gas generator according to claim 5, wherein the outlet of the first and second pressure vessels through which the compressed gas is deliverable to the gas receiving tank is selectively occludable and openable by a gas outlet valve.

9. The compressed gas generator according to claim 5, which is multi-stage, wherein each stage of the multi-stage compressed gas generator comprises the first and second pressure vessels, and wherein the compressed gas generated by a first stage of the multi-stage compressed gas generator is deliverable to a second stage of the multi-stage compressed gas generator and is increasingly compressed.

10. The compressed gas generator according to claim 1, further comprising a plurality of selectively interconnectable gas receiving tanks.

11. A method of generating compressed gas, comprising the steps of introducing gas from a gas source into a pressure vessel having a peripheral wall; introducing liquid through a perforated tube having an occluded bottom surface that extends downwardly from an upper surface of the pressure vessel; and emitting a liquid jet from each aperture of the perforated tube to cool a volume of gas present within an interior of the pressure vessel and to provide an accumulated body of liquid that displaces and compresses the volume of gas, wherein one or more of theemitted liquid jets produce an atomized spray following impingement upon the peripheral wall that is capable of sufficiently absorbing heat dissipated from the volume of gas being compressed to achieve substantial isothermal compression.

12. The method according to claim 11, further comprising the steps of opening a gas outlet provided in the pressure vessel and delivering the compressed gas to one or more gas receiving tanks.

13. The method according to claim 12, further comprising the steps of providing first and second pressure vessels and cyclically transferring the body of liquid between the first and second pressure vessels while introducing the transferred body of liquid through the pressure vessel interior via a corresponding perforated tube to compress the volume of gas without significantly increasing in temperature.

14. The method according to claim 13, wherein a residual volume of compressed gas at a same pressure as the pressure within the one or more gas receiving tanks remains within the interior of the pressure vessel to which the body of liquid was transferred following the compressed gas delivering step, the method further comprising the step of opening a recirculation valve at a bottom region of each of the first and second pressure vessels, allowing the residual volume of compressed gas to apply a force onto the accumulated body of liquid and to cause a portion of the accumulated body of liquid to flow through a flow path that includes recirculation conduits passing through the recirculation valves and that extends to the interior of the other pressure vessel due to the pressure differential between the first and second pressure vessels until the pressure within the interior of the first and second pressure vessels equalizes.

15. The method according to claim 14, further comprising the step of operating a pump to deliver a remaining portion of the accumulated body of liquid from a bottom portion of the pressure vessel within which the body of liquid accumulated to a top portion of the other pressure vessel.

16. The method according to claim 11, wherein the liquid is water and the gas is air.

17. The method according to claim 11, wherein the liquid is an ionic liquid and the gas is hydrogen.

18. The method according to claim 11, wherein the gas is compressed at a temperature below 0°C.

19. The method according to claim 12, wherein the gas is delivered to the one or more gas receiving tanks at a temperature close to an ambient temperature and a dryer operates between the ambient temperature and a condensing temperature of the liquid to discharge condensed liquid from the compressed gas stored in the one or more gas receiving tanks.

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