WO2016001919A1

WO2016001919A1 - Boosting in hydraulic and pneumatic devices

Info

Publication number: WO2016001919A1
Application number: PCT/IL2015/050671
Authority: WO
Inventors: Nitzan Eliyahu
Original assignee: Therma Sphera Ltd.
Priority date: 2014-06-30
Filing date: 2015-06-30
Publication date: 2016-01-07
Also published as: IL249635A0

Abstract

A system and method of integral, pressure boosting in hydraulic and pneumatic devices though the use of a series of pistons having differing head surface areas arranged such that each subsequent piston has a reduced head surface area relative to the immediately preceding piston so as to initiate driving of each subsequent piston at a later stage of depressurization of a pressurized fluid fed into the cylinder.

Description

BOOSTING IN HYDRAULIC AND PNEUMATIC

DEVICES

BACKGROUND OF THE INVENTION

[001] It is a known that in many hydraulic and pneumatic applications, minimum operating pressures are required to ensure such proper performance. Typically, shortfalls in needed output pressures are remedied by supplying external boosting to ensure proper performance.

[002] However, there are environments in which external boosting is unavailable, or it is available at great expense and inconvenience, or when readily available constitutes an added operating expense.

[003] Therefore, there is a need for hydraulic and pneumatic systems having integral boosting capabilities.

[004] Examples of such systems include heat pumps, heat engines, and hydraulic/pneumatic energy storage systems. Without diminishing in scope, the present document will first discuss boosted hydraulic/pneumatic energy storage systems and then boosting cylinders equipped with multiple pistons.

SUMMARY OF THE INVENTION

[005] According to the teachings of the present invention there is provided a boosting cylinder including a cylinder housing; a series of pistons in slideably mounted inside the cylinder housing, each subsequent piston of the series of pistons having a reduced head area relative to that of an immediately preceding piston in the series of pistons such that driving of each subsequent piston is initiated at a later stage of depressurization of pressurized fluid fed into the cylinder housing.

[006] According to a further feature of the present invention the series of pistons is implemented as a series of nested cylindrical pistons.

[007] According to a further feature of the present invention, there is also provided a telescopic flow line configured to receive driven fluid propelled by each of the pistons.

[008] According to a further feature of the present invention the driven fluid includes pressurized gas. [009] According to a further feature of the present invention the driven fluid includes hydraulic fluid.

[0010] According to a further feature of the present invention the pressurized fluid includes pressurized gas.

[0011 ] According to a further feature of the present invention the pressurized fluid includes hydraulic oil.

[0012] According to a further feature of the present invention the two of the series of pistons are implemented as opposed, double-acting pistons.

[0013] According to a further feature of the present invention there is also provided a heat exchanger configured to extract heat from compressed gas or supply heat to the expanding gas, the heat including heat of compression of the gas.

[0014] According to a further feature of the present invention the heat exchanger includes phase change material (PCM).

[0015] According to a further feature of the present invention there is also provided an electric generator driven by fluid ejected from the boosting cylinder.

[0016] There is also provided according to the teachings of the present invention, a method for boosting output pressure of a booster cylinder including expanding a pressurized fluid into cylinder housing; and driving each of a series of pistons slideably mounted inside the cylinder housing at later stage of depressurization of pressurized fluid fed into the cylinder housing, wherein each subsequent piston of the series of pistons has a reduced head area relative to that of an immediately preceding piston in the series of pistons.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention in regards to is objects, features, method of operation, and advantages may best be understood is set forth in the following detailed description in view of the accompanying drawings in which:

[0018] FIG. 1 is schematic view of a general layout of a hydraulic-pneumatic, energy- storage system, according to an embodiment; [0019] FIG. 2 is schematic view of process flow during a charging state of a first accumulators set of the hydraulic-pneumatic, energy- storage system, according to an embodiment;

[0020] FIG. 3 is schematic view of process flow during a charging state of a second accumulator set of the hydraulic-pneumatic energy- storage system, according to an embodiment;

[0021] FIG. 4 is schematic view of process flow during a charging state of a third accumulator set of the hydraulic-pneumatic energy- storage system, according to an embodiment;

[0022] FIG. 5 is schematic view of process flow during a discharge state of the hydraulic- pneumatic energy-storage system, according to an embodiment;

[0023] FIG. 6 is schematic view of process flow during a discharge state of a variant embodiment of the hydraulic-pneumatic energy-storage system,

[0024] FIG. 7 is schematic view of a heat management system implemented in line heat exchanger, according to an embodiment;

[0025] FIG. 7 A is schematic view of a heat management system implemented as an auxiliary, heat-transfer system, according to an embodiment;

[0026] FIG. 7B depicts graphs of hydraulic oil pressure and gas pressure as a function of time, according to the embodiment of FIG. 1 ;

[0027] FIG. 8 is schematic view of a high pressure gas storage tank loaded with phase change material and adsorbent material, according to an embodiment;

[0028] FIG. 8 A depicts two time variable plots of gas injection pressure and gas volume injected for the embodiments of pneumatic-hydraulic system of FIGS. 1-7;

[0029] FIG. 8B is schematic view of a high pressure gas storage tank loaded with phase change material and adsorbent material fitted with a gas injection system, according to an embodiment;

[0030] FIG. 8C depicts two time variable plots of gas injection pressure and gas volume injected for various embodiments of a pneumatic-hydraulic system driven by constant pressure gas injections, according to an embodiment; [0031] FIG. 9 is a schematic view of an accumulator implemented with three boosting cylinders, according to an embodiment;

[0032] FIG. 9A is a schematic view of accumulator of FIG. 9 in three expansion states, according to an embodiment;

[0033] FIG. 9B is a schematic view of complementary accumulator to accumulator of FIG. 9 in three compression states, according to an embodiment;

[0034] FIG. 9C are graphs depicting system and cylinder oil flow rate as a function of time for the embodiment of FIG. 9, according to an embodiment;

[0035] FIG. 10 is a variant embodiment of the accumulator with integral boosting cylinders of FIG. 9, according to an embodiment;

[0036] FIG. 10A is a schematic view of the accumulator of FIG. 10 at three expansion states, according to an embodiment;

[0037] FIG. 11 is a schematic view of a single -cylinder accumulator with integral boosting and unidirectional oil ejection according to an embodiment;

[0038] FIGS. 12 and 12A are expanded views of a valve mechanism of the accumulator embodiment of FIG. 11 in closed and opened states, respectively, according to an embodiment;

[0039] FIGS. 13 and 14 are schematic views of the accumulator of FIG. 11 in advanced expansion states, according to an embodiment;

[0040] FIG. 15 is a schematic view of the accumulator of FIG. 11 in an advanced compression states, according to an embodiment;

[0041] FIG. 16 is a schematic view of a variant embodiment of the single-cylinder accumulator with integral boosting of FIG. 11, according to an embodiment;

[0042] FIG. 17 is a schematic view of the accumulator of FIG. 16 in an expansion state, according to an embodiment;

[0043] FIG. 18 is a schematic view of a second variant embodiment of the single-cylinder accumulator with integral boosting of FIG. 11, according to an embodiment;

[0044] FIG. 19 is a schematic view of a single -cylinder accumulator with integral boosting and bidirectional oil ejection according to an embodiment; [0045] FIGS. 20 and 20A are schematic views of the accumulator of FIG. 19 in various expansion states, according to an embodiment;

[0046] FIGS. 21 and 21A depict reciprocative synchronization of complementary accumulators in an accumulator set during compression and expansion stages, respective, according to an embodiment;

[0047] FIGS. 22 and 23 are flow charts of processing steps involved in charging and discharging the hydraulic-pneumatic system, respectively, according to an embodiment; and

[0048] FIG. 24 is a schematic, cut- away view of the hydraulic-pneumatic, energy-storage system loaded in transportable container, according to an embodiment.

[0049] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures are not necessarily drawn to scale and reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0050] In the following description it should be understood that features illustrated and described herein are set forth as examples and therefore modifications, substitutions, changes, and equivalents known to those skilled in the art are included within the scope of the invention. Furthermore, well-known methods, procedures, and components have been omitted for the sake of clarity

[0051] The present invention is a hydraulic or pneumatic system having integral boosting capabilities. It should be appreciated that in a certain embodiment pressure boosting is accomplished separately from the work extraction of the accumulators whereas in other embodiments the boosting is executed simultaneously with the work extraction by way of accumulators implemented with integrated boosting cylinders or with nested pistons disposed in a single housing, as will be further discussed.

[0052] The system includes provisions for gas compression and storage, electricity generation, and pressure boosting with heat management to increase system efficiency, as will be further discussed

[0053] It should be noted that for the purposes of this document the following terms will be use: [0054] "Accumulator" refers to hydraulic-pneumatic device in which the expansion of compressed gas drives hydraulic oil. This includes accumulator implementations having a plurality of pistons disposed within single housing or disposed in plurality of housing units or boosting cylinders.

[0055] "Booster" refers to a pressure intensifier even at the expense of fluid flow rate.

[0056] "Integral boosting" refers to a mechanical boosting arrangement without external power supply from outside the system and may be implemented either externally or internally to a hydraulic or pneumatic cylinder.

[0057] "Boosting cylinder" refers to a cylinder having a series of slideably mounted pistons of different head surface areas, according to an embodiment.

[0058] "Piston" refers to an element through which pressure is transferred from one medium to another; either from gas to gas, gas to oil, from oil to gas, or oil to oil. Pistons refer to either cylindrical or non-cylindrical implementations of various cross-sectional areas.

[0059] "Hydraulic fluid" refers to a driven liquid whereas "hydraulic oil" refers to driving liquid.

[0060] "Thermoplastic Vulcanizate in Rubber (TPVR)", refers to a blend of thermoplastic and soft rubber in which thermoplastic particles formed around a respective rubber nuclei are dispersed within a rubber matrix.

[0061 ] "In communication" refers to both direct and indirect communication.

[0062] Turning now to the figures, FIG. 1 is a schematic view of a hydraulic-pneumatic, energy- storage system 100 including a plurality of heat-regulated, accumulator sets 1-3 in communication with a low-pressure, gas source 5, a high-pressure, gas storage 5A, a hydraulic-driven, electric-generation unit 6 and an electric-powered, compression unit 7. For the purposes of this discussion, accumulator set 1 and accumulators 1A and IB will be discussed with the understanding that the same configuration applies for accumulator assemblies 2-3 and their accumulators also. Furthermore, it should be appreciated that a various number of accumulator sets having a various number of accumulators are included within the scope of the present invention, without diminishing in scope, a three-stage embodiment of three accumulator sets of two accumulators each will be discussed. [0063] Specifically, heat regulated accumulator set 1 includes two complementary accumulators 1A-1B reciprocatively synchronized with each other so that gas expansion in either of them is matched with a corresponding gas compression in the complementary accumulator, according to an embodiment. Accumulator set 1 also includes an in-line heat exchanger 1C employing a phase change material (PCM) configured to absorb heat of compression and return it into the gas during decompression as will also be further discussed.

[0064] High-pressure storage (HPS) 5A in certain embodiments is implemented as a tank pressurized to about 100 bar and is loaded with one or more types of adsorbent material configured to adsorb non-liquefied, compressed gas like air or nitrogen, for example. Low pressure storage 5 (LPS) in certain embodiments is implemented as tank pressurized to about 4 bar or less and is also loaded with an adsorbent material to maximum gas capacity when system 100 is charged with CO₂ or other liquefiable gasses.

[0065] Typical examples of an adsorbent material are zeolites and activated carbon. It should be appreciated that other materials exhibiting such adsorbent functionality are also included within the scope of the present invention.

[0066] Electric-generation unit 6 includes a pressure booster or intensifier 10 in communication with a hydraulic motor 8 and linked to electric generator 9, according to an embodiment. Electric-powered, compression unit 7 includes an electric motor 13 configured to drive a hydraulic pump 10 in communication with an oil reservoir 12, according to an embodiment.

[0067] FIGS. 2-5 depict system 100 in various stages of operation. In most general terms, operation primarily involves compressing gas into high pressure storage (HPS) 5A by way of accumulator sets 1-3 driven by an electric hydraulic pump 11 and releasing pulses of the high pressure gas into accumulator sets 1-3 so that ejected hydraulic oil drives hydraulic motor 8 linked to electric generators 9 to produce electricity, according to an embodiment. It should be appreciated that system 100 may be implemented as an open system drawing low pressure gas from the atmosphere. Without diminishing in scope, this document will discuss a closed system in which low pressure gas is stored and retrieved from a low pressure storage facility 5. [0068] FIG. 2 depicts a first charge stage of system 100 in which hydraulic oil 1H is drawn from accumulator IB by electric-powered hydraulic pump 11 causing low pressure gas 1G to be drawn from low pressure storage 5. Oil 1H is recycled to accumulator 1A, either directly or indirectly through oil reservoir 12, and drives a piston that compresses gas previously drawn into accumulator 1A, according to an embodiment.

[0069] The compressed gas ICG is then cooled as it passes through in-line heat exchanger 1C and fed into high pressure storage (HPS) 5A until a first stage pressure of about 20 bar is achieved, for example.

[0070] FIG. 3 depicts a second charge stage commencing after the achievement of the first threshold pressure in HPS 5A. Gas 1G having been compressed and cooled into gas ICC as previously described is now drawn into accumulator 2B and oil 2H is drawn out by electric-powered hydraulic pump 11. Oil 2H is also recycled, either directly or indirectly through oil reservoir 12, into accumulator 2A where oil 2H drives a piston to recompress gas ICC previously fed into accumulator 2A, according to an embodiment. Recompressed gas 2CG is then cooled as it passes through in-line heat exchanger 2C and the recompressed and re-cooled gas 2CC is fed into HPS 5A until a second stage pressure of about 50 bar is achieved, for example.

[0071] FIG. 4 depicts a third- stage charge state commencing after the achievement of a second threshold pressure in HPS 5A. In a manner analogous to the above-described first and second stage charges, compressed gas 2CC is now drawn into accumulator 3B into accumulator 2A and oil 3H drawn out by electric-powered hydraulic pump 11. Again, oil 3H is also recycled, either directly or indirectly through oil reservoir 12, into accumulator 3A where oil 3H drives a piston to recompresses gas 2CC fed into accumulator 3A of a previous cycle, according to an embodiment. Recompressed gas 3CG is then cooled as it passes through heat exchanger 3C and the triply compressed and cooled gas 3CC is fed into HPS 5A until a pressure of between about 80 to 200 bar is achieved, for example.

[0072] FIG. 5 depicts a discharge state of system 100 in which high pressure gas HCG discharged in pulses from HPS 55 is directed through heat exchangers 1C, 2C, and 3C, respectively, and absorbs heat of compression stored in the PCM during charging; exchanger 1C heats gas HPG, exchanger 2C heats gas 1HPG, and exchanger 3C heats gas 2HPG, according to an embodiment. The resulting heated, high pressure gas 3HPG is directed into accumulator 1A where it expands against a piston thereby expelling hydraulic oil HPH and drives hydraulic motor 8 linked electric generator 9 to produce electricity, according to an embodiment. As noted above, accumulators 1A and IB are reciprocally synchronized so that residual gas disposed in complementary accumulator IB is expelled into LPS 5 by hydraulic oil recycled into accumulator IB from an exit port of hydraulic motor 8, according to an embodiment.

[0073] Pressure booster or intensifier 10 is configured to augment the feed pressure of hydraulic oil HPH in accordance with its diminishing oil pressure to ensure sufficient pressure to drive hydraulic motor 8, according to an embodiment. In a certain embodiment, booster 10 is driven by an auxiliary electric motor. (Not shown.)

[0074] FIG. 6 depicts a discharge stage of a variant embodiment of the previously depicted pneumatic-hydraulic system 100. This embodiment employs multi-stage discharge in which gas HPG is heated prior to each expansion.

[0075] Specifically, high pressure gas HPG is discharged from HPS 5A and heated in exchanger 1C and directed into accumulator 1A where it expands and expels HPH that drives hydraulic motor ID linked to electric generator 1G to produce electricity.

[0076] Similarly, in the second stage expansion, high pressure gas 1HPG discharged from accumulator IB is heated in exchanger 2C and directed into accumulator 2A where it expands and expels high pressure hydraulic oil 2HPH that drives hydraulic motor 2D linked to electric generator 2G to produce electricity.

[0077] The process is repeated for a third stage expansion. High pressure gas 2HPG discharged from accumulator 2B is heated in exchanger 3C and directed into accumulator 3A where it expands and expels high pressure hydraulic oil 3HPH that drives hydraulic motor 3D linked to electric generator 3G to produce electricity. The resulting low pressure gas 3HPG is fed from accumulator 3B into LPS 5, according to an embodiment.

[0078] FIGS. 7-7A depict two embodiments of heat management systems configured to absorb heat during compression and contribute that heat during expansion.

[0079] FIG. 7 depicts in-line heat exchanger 1C of FIGS. 1-6 and a detail view of tube array 16 formed from a phase change material like thermoplastic vulcanizate in rubber (TPVR), for example. In a certain embodiment, tubes 17 are implemented with a hexagonal cross-sectional area 17a, however, it should be noted that tubes having other cross-sectional shapes are include with the scope of the present invention.

[0080] PCM manufacturing methods and materials are found in international application PCT/IL2013/050323 and is incorporated here within by reference.

[0081] It should be appreciated that various PCM materials and other heat storage materials having high heat capacity of around 300-400 joules/gram in the thermal working range, high melting temperatures also within the thermal working range, relatively high modulus of elasticity substantially maintaining surface area, chemically stable between temperatures ranging between 30°C to 450°C, non-toxic, non-corrosive, and not prone to bacterial infection, are all included within the scope of the present invention.

[0082] FIG. 7A depicts a heat management system implemented as auxiliary heat transfer system 18 including PCM 15 unit in communication in with heat exchanger 20 disposed inside the gas chamber of accumulator 1A, according to an embodiment. Heat exchanger is charged with a suitable heat transfer agent in the form of gas or liquid as known to those skilled in the art. Pump 19 circulates the heat transfer agent through heat exchanger 20 and PCM unit 15 in accordance with heat management requirements.

[0083] It should be appreciated that in certain embodiments analogous auxiliary heat transfer system are provided for high and/or low gas storage facilities 5 and 5A, accumulators or any other point in the system deemed appropriate. Furthmore, it should be appreciated that external heat sources employed independently or in combination with heat of compression are also included within the scope of the present invention. Examples of external heat sources include, inter alia, solar or industrial waste heat.

[0084] In operation, heat is absorbed from the working gas during or after compression operations and heat is applied to the working gas during decompression operations, whether executed in accumulators or gas storage facilities.

[0085] FIG. 7B depicts graphs of hydraulic oil pressure and gas pressure as a function of time, according to the embodiments depicted in FIGS.1-6.

[0086] Graph 67 depicts pressure drop between each gas feed cycle to accumulator 1A. Gas is provided at a peak pressure 67a and drops to a minimum threshold pressure 67b prior to a new feed cycle at peak pressure 67a, according to an embodiment. [0087] Graph 65 depicts pressure changes of hydraulic oil fed to hydraulic motor as a result of boosting operations. As shown, pressure dwindles from peak pressure 65a until the next boosting operation executed when the hydraulic oil pressure reaches a low threshold pressure 65b. As shown, there are three boosting operations for each gas feed cycle, according to an embodiment.

[0088] Graph 66 depicts a pressure drop of gas at the injection point from high pressure storage for an embodiment employing a non-constant pressure feed.

[0089] FIG. 8 depicts high pressure storage tank 5A loaded with PCM 15 for heat management, adsorbent material 16 to increase storage capacity, and high pressure gas 17, according to an embodiment. When the working gas is non-liquefiable at the operating pressure at which the gas is stored, additional storage capacity is achieved by adsorbing the gas into adsorbent 16. For example, air or nitrogen is non-liquefiable at the operating temperatures and pressures in high pressure storage and therefore adsorption is needed; however, CO₂ is liquefiable at high pressure storage and therefore no adsorption is required. However, when decompressed CO₂ is fed into low pressure storage adsorption is required to increase storage capacity.

[0090] Appropriate adsorbents include, inter alia, activated carbon and zeolites.

[0091] FIG. 8A depicts two time-variable plots for pneumatic-hydraulic system 100 of FIGS. 1-7 employing the high pressure storage arrangement depicted in FIG. 8. Injection volume as a function of time is depicted in plot 20 and gas pressure at the injection point from HPS 5 A also as a function of time is depicted in plot 19.

[0092] As shown, injection volume increases as injection pressure drops to a constant mass input without additional working gas intake.

[0093] FIG. 8B depicts an embodiment of high-pressure, storage tank 5A configured to inject pulses of liquefied gas 17 into system 100 at constant pressure when employing gas liquefiable at the high storage pressure, according to an embodiment.

[0094] Specifically, HPS 5A is fitted with a hydraulic system 21 configured to change ejection pressure applied to gas 17 in accordance with diminishing gas pressure inside HPS 5A. Pressure sensor 21A detects diminishing pressure and is linked to a pressure-injection controller 21B configured to maintain constant injection pressure, according to an embodiment. As shown, HPS 5A is also fitted with a heat exchanger 20 to extract heat during compression operations, according to an embodiment. It should be appreciated that embodiments, employing any one or combination of spring, pneumatic, or hydraulic driven piston, are included within the scope of the present invention.

[0095] In contrast to the time-variable injection volume and pressure plots depicted in FIG. 8A, FIG. 8C depicts analogous plots for high-pressure storage facility HPS 5A implemented with constant-pressure injection as depicted in FIG 8B. As shown in plots 23 and 22, respectively, injection pressure is constant, at about 75-80 bar for C(¾ and around the condensation pressure of other gasses, and injection volume is also constant with time. Constant injection volume and pressure advantageously simplifies system synchronization operations.

[0096] FIG. 9 depicts an accumulator embodiment implemented with a plurality of boosting cylinders. As shown, accumulator 1A has a primary gas chamber PGC1 in communication with secondary gas chambers SGC1, SGC2, and SGC3 implemented in separate boosting cylinders CI, C2, and C3, respectively, according to an embodiment. Cylinder CI also includes liquid chamber LCI separated by piston PCI and, analogously, each of cylinders C2, and C3 includes its respective liquid chamber LC2-LC3 and piston PC2-PC3. In a certain embodiment, each of cylinders C1-C3 pistons PC1-PC3, have a progressively reduced diameter such that the diameter of PC2 is less than the diameter of PCI and the diameter of PC3 is less than that of PC2. As shown, each of cylinders C1-C3 are connected to primary gas chamber PGC1 through a series valve arrangements V1-V2 configured to direct expanding gas into the cylinder of reduced diameter responsively to the achievement of threshold pressure drop of the expanding gas 17.

[0097] It should be appreciated that accumulators having various pluralities of secondary cylinders and/or cylinders of various cross-sectional shapes are included with the scope of the present invention as noted above. Without diminishing in scope, the present document will discuss accumulators implemented with three secondary gas chambers and cylinders having a circular cross-sectional area.

[0098] FIG. 9 A depicts accumulator 1A of FIG. 9 in various stages of expansion, according to an embodiment. Compressed gas 17 of about 70 bar disposed in primary gas chamber PGC1 expands into first cylinder CI of maximum diameter against piston PCI. When the pressure drops to a threshold pressure, pressure-activated valve VI directs the gas into a second cylinder C2 of reduced diameter where the gas continues to expand against piston PC2. Again, when the pressure drops to a second threshold pressure, a second pressure- activated valve V2 opens and redirects the gas into a third cylinder C3 of further reduced diameter. Gas expansions directed to pistons of reduced diameters preserves a constant ejection pressure applied to hydraulic fluid IH even during diminishing gas pressure of the expanding gas 17, thereby advantageously enhancing work extraction.

[0099] FIG. 9B depicts complementary accumulator IB of accumulator 1A of FIG. 9A. Specifically, complementary accumulator IB is reciprocatively synchronized with accumulator 1A so that each gas expansion stage of accumulator 1A is matched with a corresponding gas compression of gas remaining in complementary accumulator IB from the previous expansion, according to an embodiment. For example, as gas expands into cylinder C3 of accumulator 1A gas remaining in cylinder C3' of complementary accumulator IB is compressed by recycled hydraulic oil injected into the cylinder C3 ', according to an embodiment.

[00100] Similarly, cylinder C2 and CI expansions are synchronized with compressions of cylinders C2' and CI ' of complementary accumulator IB, according to an embodiment.

[00101] Examples of operation pressures are about 70 bar in primary gas chamber PGC1, expansion in cylinder CI down to about 50 bar and entry into second cylinder C2, continued expansion down to about 20 bar and entry into cylinder C3, continued expansion down to about 2 bar. Remaining gas at a pressure of less than 2 bar in each cylinder C3-C1 is expelled by hydraulic oil 1H injected into each of cylinders C3-C1 at about 2 bar, according to an embodiment. In a certain embodiment, the recycled hydraulic oil is redirected from the exit port of the hydraulic motor as noted above.

[00102] It should be appreciated that various synchronization schemes between gas expansion and compression between accumulators 1A and IB are included within the scope of the present invention.

[00103] FIG. 9C depicts total system oil flow fluctuation as a function of time, according to the embodiments depicted in FIGS. 9 and 10. As shown by flow lines 70, system oil flow is implemented as a series of flow pulses that taper off in accordance with the pressure drop of expanding gas pulsed into the system. It should be appreciated that the total oil flow represents the cumulative oil flow in all accumulators and the number of accumulators is defined by the number of boosters associated with each accumulator, according to an embodiment.

[00104] FIG. 9D depicts oil flow fluctuation as a function of time for an accumulator implemented with three boosters like those depicted in FIGS. 9 and 10.

[00105] As shown, each flow line 71 begins at peak flow volume corresponding to the gas pulse at its peak pressure in the accumulator. Oil flow tapers off in segment 71a until it abruptly drops to second flow volume as gas is diverted to booster C₂. As depicted in segment 71b flow volume in booster C₂ also tapers off and again abruptly drops as gas is redirected to booster C3. As depicted in segment 71c oil flow volume again tapers off to a minimum flow volume.

[00106] It should be appreciated that there is a synchronization of respective flow volume of corresponding boosters in each of the accumulators to ensure a constant system flow volume, according to an embodiment.

[00107] FIG. 10 is an alternative embodiment of the multi-cylinder accumulator 1A depicted in FIG. 9. As shown, the gas chamber is housed in three separate cylinders Cl- C3, each of increasing diameter to compensate for pressure drop during gas expansion. Cylinder CI is fitted with a gas chamber piston GCPl having a mechanical linkage to a fluid or liquid chamber piston LCP disposed in a liquid chamber LG, according to an embodiment. Similarly, cylinders CI and C2 are also equipped with analogous gas chamber pistons GCP2 and GCP3 mechanically linked to liquid chamber piston LCP disposed in liquid chamber LC.

[00108] FIG. 10A depicts accumulator 1A of FIG. 10 in various stages of expansion, according to an embodiment. At cylinder CI expansion, compressed gas 17 of about 70 bar expands against gas chamber piston GCPl. The resulting piston motion is translated into a corresponding movement of liquid chamber piston LCP resulting in expulsion of a portion of the hydraulic oil 1H from the liquid chamber LC. When gas pressure drops to a threshold pressure, pressure-activated valve VI opens and directs gas 17 into a second cylinder C2 of increased diameter where gas 17 continues to expand against piston GCP2, and similarly, the motion is translated into a corresponding motion of liquid chamber piston LCP resulting in the expulsion of additional oil 1H from the liquid chamber LC at the same pressure of the first portion of oil expelled. [00109] Again, when the pressure drops to a second threshold pressure, a second pressure-activated valve V2 redirects gas 17 into a third cylinder C3 of further increased diameter. Analogously, additional oil 1H is expelled from liquid chamber LC at the same pressure as the previous oil expulsions, according to an embodiment.

[00110] FIG. 11 is a schematic, cross-sectional view of accumulator 1A implemented as a cylinder having integral pressure boosting capability through a series of nested, cylindrical pistons of progressively smaller head surface areas, according to an embodiment.

[00111] Specifically, accumulator 1A includes housing 25, with gas exit port 32A and gas input port 32 and an oil exit port 30. Outer piston 26 is slideably seated in housing 25, a secondary piston 27 of a reduced diameter is slideably seated within outer piston 26, and a tertiary piston 28 of a further reduced diameter is in turn slideably seated in secondary piston 27, and a static reservoir wall 29 is slideably nested within the cavity of tertiary piston 28, according to an embodiment. A non-cylindrical oil ejection piston 33 is slideably mounted within static reservoir 37. Seals 40 are disposed between sliding surfaces and are constructed of a material like silicon enabling motion and preventing leakage of gas or hydraulic oil.

[00112] A variable- volume, gas reservoir 44 is formed between housing 25 and primary piston 26 (More clearly seen in FIGS. 13-15), and similarly, variable-volume hydraulic oil reservoirs 34 and 35 are formed between primary piston 26 and secondary piston 27 plus secondary piston 27 and tertiary piston 28, respectively, according to an embodiment.

[00113] A telescopic flow tube 31 and associated flow ducts 43 and valve arrangements 41 are configured to enable oil flow between reservoirs 34 to 35, 35 to 36, and 36 to 37 responsively to gas expansion as will be explained in regards to detail "A".

[00114] FIGS. 12 and 12A are expanded views of detail "A" depicting oil flow duct 43 in closed and opened states, respectively.

[00115] As shown, primary piston 26 is fitted with pin 38 in alignment with valve 42 embedded in secondary piston 27, according to an embodiment. When valve 42 is closed hydraulic oil 1H flows from primary oil reservoir 34 into telescopic flow line 31 without flowing into oil reservoir 36. When primary piston 26 is in proximity to secondary piston 27 after the vast majority of oil 1H has been expelled from variable reservoir 34, pin 38 presses valve 42 into an open position thereby enabling oil 1H disposed in variable reservoir 36 to flow through duct 43 into telescopic flow line 31 as shown. [00116] FIGS. 13-15 depict accumulator 1A and integrated booster of FIG. 11 in various stages during gas expansion and compression, according to an embodiment.

[00117] Specifically, FIG.13 depicts accumulator 1A after pressurized gas 17 fed through gas inlet 32 has expanded in gas reservoir 44 against primary piston 26 and expelled oil IH from reservoir 34 shown in FIG. 11. Oil IH travels though telescopic flow tube 31 and advances piston 33 to expel oil IH out of reservoir 37 through oil outlet 30.

[00118] As shown, one-way valves 41 are closed during gas expansion thereby preventing oil backwash upon constriction of oil reservoirs 34, 35, and 36 whereas valves 42 are in an opened state so as to enable passage through ducts 43 to telescopic flow line as oil reservoirs 35, and 36 collapse, according to an embodiment.

[00119] FIG. 14 depicts accumulator 1A after complete gas expansion into gas reservoir 44, according to an embodiment.

[00120] As shown, cylindrical pistons 26, 27, and 28 have been driven by gas 17 into a fully nested state in which the volume of each of the variable-volume reservoirs formed between cylindrical pistons 26, 27, and 28 has been reduced to substantially zero. Substantially all oil IH has been expelled from variable-volume reservoirs 34, 35, and 36, shown in FIG. 11, through telescopic flow line and has driven piston 33 to a state of proximity with housing 25, thereby expelling oil IH from accumulator 1A through oil port 30. Expelled oil IH may drive a wide variety of hydraulic or combination hydraulic- pneumatic driven devices.

[00121] FIG. 15 depicts accumulator 1A during a compression stage in which oil IH fed though oil port 30, fills static oil chamber 37, drives oil piston 33 to refill collapsed variable- volume reservoirs 34, 35, and 36 formed between cylindrical pistons 26, 27, and 28 and expels gas 17 from gas reservoir 44 out of gas exit valve 31 in preparation for the next expansion, according to and embodiment. As shown one way valves 41 are disposed in an opened state whereas valves 42 are disposed in a closed state.

[00122] FIGS. 16 and 17 depict a generally analogous embodiment to the accumulator of FIGS 11-15 with the exception of the pressure-based flow path arrangement enabling oil IH to flow from variable-volume reservoirs 35 and 36 responsively to piston position. Accordingly, other depicted features have been labeled as shown in FIG. 15. [00123] Under pressure of pressurized gas 17 supplied at gas inlet port 32, hydraulic oil 1H disposed in reservoir 35 is forced into low pressure telescopic flow line 31 either through flow ducts 43 and ports 45 or both.

[00124] Gas expansion forces primary piston 26 into a state of abutment or near abutment with piston 27 so as to align ports 45 with flow ducts 43 embedded in piston 27 thereby enabling pressurized hydraulic oil 1H disposed in reservoir 36 to be forced into telescopic flow line 31 through ducts 43 and ports 45 where it drives piston 33. Additional expansion and compression operations are analogous to those described above in regards to the embodiment depicted in FIGS. 11-15.

[00125] FIG. 18 depicts a second variant embodiment of the accumulator of FIG. 11-15 in which each of telescopic segments 45, 46, and 47 is vented with vents 45a, 46a, and 47a, respectively.

[00126] In operation, primary piston 26 under pressure from pressurized gas 17 supplied to gas inlet 32 forces oil 1H disposed in variable-volume reservoir 34 into segment 45 though vent 45a. Primary piston 26 is driven towards secondary piston 27 bringing vent 45a into alignment with vent 46a of segment 46 thereby providing a flow path through segment 46 for oil 1H disposed in variable-volume reservoir 35. Similarly, secondary piston 27 is driven to a state of abutment with tertiary piston 28 and vent 46a is brought into alignment with vent 47a of segment 47. Analogously, upon further gas expansion, oil 1H disposed in reservoir 36 is forced into segment 48 and fed into static reservoir 37 where it drives piston 33 disposed near the downstream end of housing 25. In this embodiment, piston shaft 33a is linked mechanically, either directly or indirectly, to a generator implemented as either a linear generator or a non-linear generator, according to an embodiment

[00127] FIG. 19 is an alternative embodiment of an accumulator with integrated boosting implemented as opposed, dual-action piston sets disposed in a single housing in which each of the piston sets is driven in opposite directions during expansion, according to an embodiment.

[00128] Specifically, cylindrical piston 52 and non-cylindrical piston 50 are disposed in housing 75 and define a variable-capacity gas chamber 56 in between them. Cylindrical piston 53 nests in cylindrical piston 52 so as to form a first variable-capacity oil reservoir 60. Static block 54 nests in cylindrical piston 53 so as to form a second variable-capacity oil reservoir 57, according to an embodiment. Non-cylindrical piston 50 and piston 51 form a variable capacity oil reservoir 58 and static block 54a nests in cylindrical piston 51 so as to form a third variable capacity oil reservoir 58, according to and embodiment.

[00129] Gas chamber 56 is loaded with PCM 15 to provide heat management capability during compression and decompression operations. PCM lining 15 is also disposed along an outer wall of housing 75 opposite a wall length defining maximum volume of variable- capacity gas chamber 56. It should be appreciated that a heat exchanger (Not shown.) may also be disposed within gas chamber 56 in communication with an auxiliary heat management system. Gas chamber 56 is also loaded with adsorbent material to increase storage capacity.

[00130] Housing 75 includes a valve-regulated gas inlet 12 through which gas 17 is fed during expansion or discharged during compression.

[00131] Variable-capacity oil reservoir 60 in is communication with flow control- valve and, similarly, oil reservoirs 57, 58 and 59 are in communication with their respective flow control- valves 57a, 58a, and 59a, according to an embodiment.

[00132] FIGS. 20 and 20A depicts the embodiment of FIG. 19 at various stage of expansion during an expansion operation, according to an embodiment.

[00133] Specifically, in FIG. 20 gas 17 is fed though inlet 12 expands in variable capacity gas chamber 56 pushing pistons 52 and 50 in opposite directions. Oil disposed in variable- capacity-oil reservoirs 60 and 58 is injected through flow paths in communication with control valves 60a and 59a, respectively, in accordance to the control-valve configurations. As shown, at first stage expansion both control valves 60a and 59a are open whereas control valves 57a and 58a are closed.

[00134] FIG. 20A depicts the embodiment of FIG. 19 at a further stage of expansion in which gas 17 continues to drive pistons 52 and 50 and expel substantially all oil 1H from reservoirs 60 and 59 and also eject oil 1H from reservoirs 59 and 57 through their respective flow paths in accordance to configurations of flow-valves 59a and 57a, according to an embodiment. [00135] FIGS. 21 and 21A depicts the reciprocative synchronization between complementary accumulators 1A and IB of accumulator set 1 during compression and discharge stages, respectively, according to an embodiment.

[00136] As shown in FIG. 21, accumulator set 1 includes complementary accumulators 1A and IB driven by hydraulic motor 8 in turn driven by electric motor 9, according to an embodiment. Complementary accumulators 1A and IB both include integrated booster pistons 62 as described in any of the above embodiments.

[00137] As shown in FIG. 21A, during the discharge stage, expanding gas 17a in complementary accumulator 1A drives booster pistons 62 to eject oil 1H and drive hydraulic motor 8 which in turn drives electric generator 9. Residual pressure remaining in oil 1H is directed from the exit port (Exit port during the discharge state) from hydraulic motor 8 and drives booster pistons 62 to eject remaining gas 17 from in complementary accumulator IB, according to an embodiment.

[00138] It should be appreciated that embodiments having integral booster capacity a gas chamber implemented as a combustion chamber in which gas expansion is achieved through combustion of fuel is also included in the scope the present invention.

[00139] As noted above, the integral boosting arrangement also has application in heat pumps and heat engines. Internally-boosted cylinders in heat pumps advantageously enable work extraction in addition to the transfer of heat load. Similarly, in regards to heat engines, internally-boosted cylinder advantageously enable great work extraction than normally possible with cylinders not boosted in such a manner.

[00140] FIGS. 22 and 23 are flow diagrams of process steps during charging and discharging, respectively.

[00141] As shown in FIG. 22 in step 85 pressure gas is compressed, in step 86, the compressed gas is cooled using a PCM material either in-line or in an auxiliary heat management system, in step 87 the compressed gas is stored in a high pressure storage tank or facility, and in step 88 compressed gas is adsorbed by an adsorbent disposed in the high pressure gas storage.

[00142] As shown in FIG. 23 in step 91 compressed gas is discharged from high pressure storage in pulses, in step 92 the discharge gas is heated from heat captured during compression, in step 93 the discharged gas expands in accumulators, in step 94 expanding gas or ejected oil is pressure boosted, and in step 95 an electric generator is driven by the ejected hydraulic oil in conjunction with a hydraulic motor linked to an electric generator, according to the embodiment.

[00143] FIG. 24 is a schematic, cut-way view of hydraulic-pneumatic energy- storage system 100 disposed inside a shipping container 80 mounted on a skid 82 to facilitate transport to desirable deployment sites. It should be appreciated that system 100 includes a skid mount 82 or other transport accessories facilitating transport are also included with the scope of the present invention.

[00144] In a certain embodiment, hydraulic-pneumatic energy-storage system 100 the high and low pressure tanks, accumulators, heat exchangers are ISO compliant and constructed from materials like, inter alia, steel, ceramics, polymer, and other traditional construction materials known to those skilled in the art.

[00145] As noted above, hydraulic-pneumatic energy- storage system 100 is non- geographical dependent and compact to facilitate shipping. Furthermore, the above described system components are modular, thereby facilitating scalability and deployment directed to site- specific needs.

[00146] Hydraulic-pneumatic energy-storage system 100 advantageously has no pollution emissions, facilitates power grid management, enables electricity suppliers to build infrastructures in accordance with average load instead of maximum load. System 100 can also supply electric energy storage for wind turbines and solar farms. Furthermore, system 100 can be deployed to drive pneumatic or hydraulically devices.

[00147] Hydraulic-pneumatic energy- storage system 100 has 450 kilowatt hours electricity production capacity at 90% efficiency and thermal storage capacity of about 3.3 megawatt hours heat recovery efficiency of about 90%, in a certain embodiment.

[00148] It should be appreciated that undisclosed combinations of features described in various embodiments are also within the scope of the present invention.

Claims

CLAIMS What is claimed is:

1. A boosting cylinder comprising:

a cylinder housing; and

a series of pistons in slideably mounted inside the cylinder housing, each

subsequent piston of the series of pistons having a reduced head area relative to that of an immediately preceding piston in the series of pistons such that driving of each subsequent piston is initiated at a later stage of

depressurization of pressurized fluid fed into the cylinder housing.

2. The boosting cylinder claim 1, wherein the series of pistons is implemented as a series of nested cylindrical pistons.

3. The boosting cylinder 2, further comprising a telescopic flow line configured to receive driven fluid propelled by each of the pistons.

4. The boosting cylinder of claim 3, wherein the driven fluid includes pressurized gas.

5. The boosting cylinder of claim 3, wherein the driven fluid includes hydraulic fluid.

6. The boosting cylinder of claim 2, wherein the pressurized fluid includes pressurized gas.

7. The boosting cylinder of claim 2, wherein the pressurized fluid includes hydraulic oil.

8. The boosting cylinder of claim 2, wherein two of the series of pistons are implemented as opposed, double-acting pistons.

9. The boosting cylinder of claim 7, further including a heat exchanger configured to extract heat from compressed gas or supply heat to the expanding gas, the heat including heat of compression of the gas.

The boosting cylinder of claim 8, wherein the heat exchanger includes ph; change material (PCM).

The boosting cylinder of claim 1, further including an electric generator driven by fluid ejected from the boosting cylinder.

A method for boosting output pressure of a booster cylinder comprising:

expanding a pressurized fluid into cylinder housing; and

driving each of a series of pistons slideably mounted inside the cylinder

housing at later stage of depressurization of pressurized fluid fed into the cylinder housing,

wherein each subsequent piston of the series of pistons has a reduced head area relative to that of an immediately preceding piston in the series of

pistons.

The method of claim 12, wherein the series of pistons is implemented as a series nested cylindrical pistons.

The method of claim 12, further comprising a telescopic flow line configured to receive driven fluid propelled by each of the pistons.

The method of claim 14, wherein the driven fluid includes pressurized gas.

The method of claim 14, wherein the driven fluid includes hydraulic fluid.

The method of claim 12, wherein two of the series of pistons are implemented opposed, double-acting pistons.

The method of claim 17, further including a heat exchanger configured to extract heat from compressed gas or supply heat to the expanding gas, the heat including heat of compression of the gas.

19. The method of claim 18, wherein the heat exchanger includes phase change material (PCM).

20. The method of claim 12, further driving an electric generator driven by fluid ejected from the boosting cylinder.