EP3807539A1 - Systèmes et procédés de compression/détente de gaz à étages multiples hybrides - Google Patents

Systèmes et procédés de compression/détente de gaz à étages multiples hybrides

Info

Publication number
EP3807539A1
EP3807539A1 EP17728454.4A EP17728454A EP3807539A1 EP 3807539 A1 EP3807539 A1 EP 3807539A1 EP 17728454 A EP17728454 A EP 17728454A EP 3807539 A1 EP3807539 A1 EP 3807539A1
Authority
EP
European Patent Office
Prior art keywords
gas
liquid
compression
expansion
multistage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP17728454.4A
Other languages
German (de)
English (en)
Inventor
Sylvain Lemofouet
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Enairys Powertech Sa
Original Assignee
Enairys Powertech Sa
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Enairys Powertech Sa filed Critical Enairys Powertech Sa
Publication of EP3807539A1 publication Critical patent/EP3807539A1/fr
Pending legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
    • F04C23/005—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids of dissimilar working principle
    • F04C23/006—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids of dissimilar working principle having complementary function
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
    • F04F1/00—Pumps using positively or negatively pressurised fluid medium acting directly on the liquid to be pumped
    • F04F1/06—Pumps using positively or negatively pressurised fluid medium acting directly on the liquid to be pumped the fluid medium acting on the surface of the liquid to be pumped
    • F04F1/10—Pumps using positively or negatively pressurised fluid medium acting directly on the liquid to be pumped the fluid medium acting on the surface of the liquid to be pumped of multiple type, e.g. with two or more units in parallel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/06—Servomotor systems without provision for follow-up action; Circuits therefor involving features specific to the use of a compressible medium, e.g. air, steam
    • F15B11/072—Combined pneumatic-hydraulic systems
    • F15B11/0725—Combined pneumatic-hydraulic systems with the driving energy being derived from a pneumatic system, a subsequent hydraulic system displacing or controlling the output element

Definitions

  • This invention concerns methods for efficiently producing high pressure gas, and for converting the potential energy of pressurized gas into mechanical work and vice-versa; as well as reversible hybrid systems, which directly convert the pressure energy of a compressed gas, particularly air, into mechanical work and vice-versa, by performing successive nearly isothermal compression/expansion.
  • This invention is related to the production of high pressure gas, such as compressed air for breathing purposes or as power source for various compressed air-powered tools and industrial processes. It is also related to the use of compressed air as energy storage media like in the case of compressed air-powered cars, or to circumvent the intermittency of some renewable energy sources such as solar and wind sources.
  • the potential energy of compressed air is generally exploited by firstly converting it into mechanical work.
  • Two main categories of energy conversion systems have been proposed for that purpose: pure pneumatic conversion systems where the only active fluid is air and hydro- pneumatic conversion systems that use at least one liquid (oil, water) as active fluid. Isothermal compression/expansion of gas will yield the highest energy efficiency if the gas is cooled/heated before or during the compression/expansion process.
  • the standard fixed-displacement hydraulic motor/pump used in the "Second Inventive System (System 2)" requires a “liquid directional control unit” for controlling the flow direction of the active liquid and converting the unidirectional flow in the motor/pump into a bidirectional flow in the compression/expansion modules.
  • This unit which is made of several directional valves increases the complexity of the system and its operation generates a lot of pressure harmer and losses.
  • the motor/pump are operated at constant speed as usual, the mechanical power will fluctuate drastically in relation with the gas pressure which varies all the time, thus the system provides low power flexibility and quality.
  • the efficiency of the proposed hydraulic gas compression/expansion modules depends on the amount of heat exchange surface provided by the heat exchanger integrated in the compression/expansion chambers. In the proposed designs of heat exchangers, this surface is limited to the external surface of the liquid channels which occupied at least half of the volume of the chambers. The useful volume left to the gas is therefore limited which reduces the power density of the compression/expansion modules and therefore that of the system. It would be desirable to provide a reversible conversion system with high power density, flexibility and quality to efficiently convert the potential energy of a high pressure gas, in particular air, into mechanical power and vice-versa.
  • the present invention proposes original solutions to achieve these objectives and overcome the limitations of the solutions proposed in by Lemofouet & Al. in US Patent 8,567,183 B2.
  • This invention provides a hybrid multistage system for converting the potential energy of a pressurized gas, particularly air, into mechanical work of two rotating shafts when operating the system in expansion or discharge mode, and for producing high pressure gas (preferably above 40bar) from the mechanical work of these rotating shafts, when operating the system in compression or charge mode, by performing successive nearly isothermal expansion/compression of the gas.
  • the inventive system comprises:
  • a low pressure multistage compression/expansion unit made of several stages of positive displacement rotary compressor/expander, such as a scroll or screw compressor/expander, mounted on one common driving/driven rotatable shaft and specially designed to allow the injection of a substantial amount of liquid (particularly water) inside the working chambers; which compress a low pressure gas (atmospheric air or gas below lObar) up to a medium pressure (preferably in the range 10 to 40bar) when rotating the shaft in one direction; or which convert pressure energy of a medium pressure gas (preferably in the range 10 to 40bar) into mechanical power when rotating the shaft in the opposite direction, by performing an essentially isothermal compression/expansion of the said gas thanks to the injection of liquid inside the working chambers.
  • a low pressure gas atmospheric air or gas below lObar
  • a medium pressure preferably in the range 10 to 40bar
  • a high pressure multistage hydraulic compression/expansion unit comprising mainly: ⁇ A multistage of hydraulic compression/expansion module having an even number of enclosures of different volume, each one integrating a special gas/liquid heat exchanger, designed to convert the high pressure (preferably above 40bar) gas power into hydraulic power and vice-versa, by performing an essentially isothermal compression/ expansion of the gas.
  • the hydraulic motor/pump has several circuits or stages in correspondence with the number of enclosures of the compression/expansion module, each stage being of different displacement range and being directly connected to the compression/expansion enclosure of corresponding displacement or volume.
  • a multistage gas directional control module • A multistage gas directional control module. - An intermediate buffer storage tank, for the temporary storage of the medium pressure gas (preferably in the range 10 to 40bar) so as to interface the continuous mass flow of the low pressure compression-expansion unit with the intermittent mass flow of the high pressure compression-expansion unit.
  • a low pressure (below lObar) liquid conditioning unit for supplying, cleaning and maintaining the active liquid at ambient temperature thanks to heat exchange with external heat sink or/and heat source.
  • a method for producing a high pressure gas, particularly air, from the mechanical work of two rotating shafts by performing a sequence of transformations comprises the steps of:
  • pre-compressing low pressure gas in particular below lObar, in particular atmospheric air
  • a dedicated multistage low pressure gas compression unit made of several stages of a positive displacement rotary compressor, using the mechanical power of a first rotating shaft to force said gas to flow inside a continuously decreasing working chamber of one stage of the said unit, and then into that of the next smaller stage, while continuously cooling said gas by means of injecting a liquid in particular water in said working chambers, thus compressing said gas in a nearly isothermal manner up to a medium pressure, preferably in the range 10- 40bar.
  • a method for converting the potential energy of a high pressure gas, preferably above 40bar, particularly air, into mechanical work of two rotating shafts by performing a sequence of transformations comprises the steps of:
  • a dedicated multistage gas expansion unit made of several stages of a positive displacement rotary expander, operating from medium to low pressure preferably from 40bar down to atmospheric pressure, by forcing said gas to flow inside a continuously increasing working chamber of one stage of the said unit and then into a bigger continuously increasing working chamber of a next stage, while continuously heating said gas by means of liquid injection in said working chambers, thus decreasing the pressure of said gas in a nearly isothermal manner down to atmospheric pressure.
  • Figures la and lb present one embodiment of the inventive hybrid multistage gas compression/expansion system, using a pressurised liquid reservoir as active liquid source, scroll compression/expansion stages in the low pressure conversion, and hydraulic compression/expansion modules with hydraulic ports on the top cover.
  • Figures 2a and 2b illustrate general embodiments of the active liquid conditioning unit, with different possibilities for liquid supply and heat exchanges with external heat sinks/sources.
  • Figure 3a presents the flow characteristic of one stage of the multistage variable- displacement bidirectional flow hydraulic motor/pump used in the inventive hybrid system
  • Figure3b illustrates an example of pump technology which allows achieving the flow characteristics.
  • Figure 4 depicts the layout of one compression/expansion enclosure of the inventive hybrid multistage gas compression/expansion system, using an innovative design of the integrated heat exchanger.
  • Figure 5 a, 5b and 5 c present respectively an isometric view, a cut-away isometric view and a bottom view of a new design of the heat exchanger integrated in the hydraulic gas compression/expansion enclosure presented in Figure 4.
  • Figures 6a and 6b present another embodiment of the inventive hybrid multistage gas compression/expansion system, using an unpressurised boosted liquid reservoir as active liquid supply, screw compression/expansion stages in low pressure conversion, and hydraulic compression/expansion modules with hydraulic ports on the bottom cover.
  • Figure 7 illustrates the layout of another compression/expansion enclosure using another new design of the integrated heat exchanger.
  • Figures 8a, 8b and 8c present respectively an isometric view, a cut-away isometric view and a bottom view of another new design of the heat exchanger integrated in the hydraulic gas compression/expansion enclosure presented in Figure 7.
  • Figures 9a and 9b present respectively a top view and an isometric view of another shape of a base honeycomb structure with square shape, that can be used to build the integrated heat exchangers presented in Figures 5 and 8.
  • a low pressure multistage gas compression/expansion unit (L) A low pressure multistage gas compression/expansion unit (L);
  • a high pressure multistage hydraulic gas compression/expansion unit (H) A high pressure multistage hydraulic gas compression/expansion unit (H).
  • the low pressure active liquid conditioning unit (W) may have one or several different possible configurations as explained below.
  • the low pressure active liquid conditioning unit (W) may have one or several different possible configurations as explained below.
  • the present inventive system exploits the incompressibility and heat capacity of an active liquid, in particular water or water emulsion, to compress and/or maintain a gas at almost constant temperature during the compression/expansion processes.
  • the role of the active liquid conditioning unit (W) is to supply, clean and maintain the active liquid at constant temperature.
  • FIG. 2a presents a possible layout of the active liquid conditioning unit, which uses a pressurised reservoir (W.l) serving as boosted liquid source for the conversion units and in the supply line a heat exchanger (W.9) connected to an external heat source (W.10) allowing, particularly during the expansion mode where the liquid is cooled down by the expanding gas, to reheat the active liquid before supplying it again to the conversion units.
  • a check valve (W.12) and 3-way/2-positon valve (W. l l) allow connecting the heat exchanger (W.9) to the supply line or bypassing it when needed.
  • the heat source (W.10) could be any available waste heat from another application or a specific heat source in the form of a solar thermal system for instance.
  • the return line of this layout includes a liquid filter (W.2) which extracts the impurities from the liquid flowing back from the conversion units and, another heat exchanger (W.5') connected to a heat sink/source (W.6) allowing to regulate the temperature of the active liquid flowing back from the conversion units before feeding it back into the reservoir (W. l).
  • a check valve (W.8) and 3-way/2-position valve (W.7) allow connecting the heat exchanger (W.5') to the return line or bypassing it when needed.
  • the heat sink/source (W.6) could be any heat application providing an important heat capacity or the ambient environment as illustrated in the systems of Figure 1 and Figure 6. In that case, the heat exchanger (W.5') is simply an ambient air/liquid radiator (W.5) used to regulate the liquid temperature.
  • the active liquid conditioning unit (W) provides one connection port D on the supply line for the liquid injection pumps of the low pressure conversion unit, one connection port C on the return line for liquid/gas separators of the whole system and, one connection port (A, or B) for each stage of the high pressure conversion unit (H).
  • a set of check valves W.3a and W.3b, or W.4a and W.4b is used to automatically convert each bidirectional liquid flow from high pressure conversion unit (H) into the unidirectional liquid flow of the active liquid conditioning unit (W).
  • FIG. 2b Another possible layout of the active liquid conditioning unit (W) is presented in Figure 2b.
  • the main difference with the previous layout is the use of an unpressurised liquid source (W.1 '), which could be a reservoir at atmospheric pressure or a natural water source like a river or a lake.
  • a variable boost pump (W.13) driven by the electric motor (W.14) could be necessary to supply the active liquid to the high pressure conversion unit (H).
  • a quick exhaust valve W.3'a or W.3'b is used to automatically convert each bidirectional liquid flow from high pressure conversion unit (H) into the unidirectional liquid flow in the active liquid conditioning unit (W).
  • the low pressure multistage gas compression/expansion unit (L) The low pressure multistage gas compression/expansion unit (L)
  • the low pressure multistage compression/expansion unit (L) is intended to efficiently compress a low pressure gas (preferably atmospheric air or gas below lObar) up to a medium pressure (preferably in the range 10 to 40bar), and to efficiently convert back the pressure energy of a medium pressure gas into mechanical power by performing an essentially isothermal compression/expansion of the said gas.
  • a low pressure gas preferably atmospheric air or gas below lObar
  • a medium pressure preferably in the range 10 to 40bar
  • Positive displacement rotary compressor technologies are able to achieve this objective and some of them like scroll or screw technologies are reversible, e. g.
  • the low pressure compression/expansion unit (L) of the current inventive system is therefore made of several stages of positive displacement rotary compressor/expander, such as a scroll (orbiting or co-rotating) compressor/expander like in Figure l a (L.
  • Each stage has a liquid injection circuit composed of an injection variable pump (L.5a, L.5b), a 3-way/2-positon directional valve (L.7a, L.7b) which allows directing the liquid either on the intake spray nozzle (L.6a, L.6b) during the gas compression mode or on the exhaust spray nozzle (L.8a, L.8b) during the gas expansion mode.
  • L.7a, L.7b 3-way/2-positon directional valve
  • other liquid injection nozzles can be mounted on the casing of the unit to directly access intermediate working chambers.
  • Intake (L.3a), exhaust (L.3b) and inter-stage (L.4) gas/liquid separators are provided to extract the liquid from the gas at the end of each compression/expansion stage.
  • Each pressurised separator has a liquid discharge circuit including a discharge valve (L.10; L.12) and a pressure relief valve (L.l l; L.13) allowing to return the liquid back into the liquid conditioning unit (W) without causing a gas pressure drop.
  • An exhaust 2-way/2-positon valve with integrated check (L.14) is used to control the reverse flow of the gas and thus avoid and uncontrolled operation of the unit in discharge (expansion) mode.
  • the buffer gas tank is a storage unit connected at the junction of the two multistage gas compression/expansion units for the temporary storage of the medium pressure gas flowing from one unit to the other.
  • the buffer gas tank therefore acts like a damper that regulates the average gas mass flow and allows an appropriate interconnection of the two units.
  • the multistage hydraulic gas compression/expansion unit (H) according to this inventive system comprises three key parts: a) A multistage bidirectional flow, variable displacement hydraulic motor/pump b) A multistage hydraulic gas compression/expansion module
  • a multistage gas directional control module a) The multistage, variable displacement, bidirectional flow hydraulic motor/pump
  • the multistage, variable displacement bidirectional flow hydraulic motor/pump (H. la, H.2b) is intended to convert hydraulic power into mechanical power and vice-versa.
  • the multistage hydraulic motor/pump has several stages mounted on a common driving/driven shaft (H.10), in correspondence with the number of stages of the multistage compression/expansion module, each circuit being of different displacement range and being directly connected, on the high pressure side to a compression/expansion enclosure of corresponding volume and, on the low pressure side to the liquid conditioning unit.
  • Figure 3 a presents the flow characteristic of one stage of such a multistage variable- displacement bidirectional flow motor/pump
  • Figure 3b depicts the operation of a variable displacement axial piston motor/pump with a swash plate rotating over the centre; as an example of pump technology which achieves such flow characteristics.
  • By varying the angle of the swash plate over its rotation centre it is possible to vary the flow rate and moreover to reverse the flow direction without changing the rotational direction of the shaft.
  • This feature of the motor/pump provides two key advantages to this inventive system compared to the standard fixed-displacement motor/pump used in the "Second Inventive System" of US Patent 8 567 183 B2:
  • Liquid directional control unit for controlling the flow direction of the active liquid.
  • This unit is made of several hydraulic valves which increases the complexity of the system and its operation generates a lot of pressure harmers and losses. In addition, it allows switching the connections between high circuit and low pressure circuit, and in case of failure, high pressure could be accidentally applied on low pressure components and destroy them. With the current variable-displacement bidirectional flow motor/pump, the operation of the unit is simpler, smoother and safer.
  • the bidirectional variable flow rate allows regulating and varying the mechanical power in a wide range even at constant speed operation, which drastically increases the power flexibility and quality of this conversion unit.
  • the continuous change in pressure during the compression and expansion processes is compensated by an equivalent opposite change in flow rate, thus a constant (over one stroke) and variable power can be generated even at constant speed operation.
  • This multistage module comprises several hydraulic gas compression/expansion enclosures (H.2a, H.2b) of different volume, which contains a special gas/liquid heat exchanger (H.2.2a, H.2.2b).
  • H.2a, H.2b a hydraulic gas compression/expansion enclosure
  • H.2.2a, H.2.2b a special gas/liquid heat exchanger
  • Figure 4 A simplified cutaway drawing of a hydraulic gas compression/expansion enclosure is represented in Figure 4. It is mainly made of a vertical compression/expansion cylinder (H.2.1) that integrates the special heat exchanger (H.2.2a or H.2.2b). Its inner cavity is accessible through a central gas port (H.2.3) on the top cover and, one or several hydraulic ports (H.2.4) on the top cover ( Figure 4).
  • Figure 5a, 5b and 5c present different views of a new design of the heat exchanger integrated in the presented hydraulic gas compression/expansion enclosures, which is the key element to achieve nearly isothermal compression/expansion processes. It is made of a thin corrugated metal sheet (H.2.2.2) placed on another thin flat metal sheet (H.2.2.1), both wound to form a "spiral honeycomb" structure. A number of thin metal tubes (H.2.2.5) are threaded through holes of the honeycomb structure which they match almost perfectly the shape. These tubes form water channels and are uniformly distributed over the entire section of the structure to ensure good distribution of water flow and heat transfer.
  • a distribution plate H.2.2.3
  • a space H.2.2.4 between the upper edge of the honeycomb structure and the underside face of the distribution plate as can be seen on Figure 5b.
  • the space (H.2.2.4) ensures a good distribution/collection of the gas during its entry/exit into/from the compression/expansion chamber.
  • the whole assembly is then brazed or welded for instance to ensure good metallic contacts and therefore good mechanical strength and thermal conduction of the heat exchanger.
  • the underside face of the distribution plate H.2.2.3) may also have a conical shape to facilitate gas expulsion from inside the compression/expansion chamber.
  • the heat exchanger is mounted so as to provide a liquid distribution chamber (H.2.5) under the top cover of the compression/expansion enclosure (H.2.1).
  • the liquid ports are disposed and configured so as to ease a uniform distribution of liquid inside this chamber.
  • the enclosure's top cover provides an isolating central channel (H.2.3) through which gas flow into/out of the compression-expansion chamber
  • the metallic heat exchange surface provided to the gas is separated from the liquid channels whose total section is defined according to the liquid flow rate and not heat exchange surface.
  • the new heat exchanger occupied less than 20% of the total inner volume of the compression/expansion chamber, which is very low compared to at least 50% for the previous designs. This affects the power density of the compression/expansion unit and therefore the size of whole system.
  • the new heat exchangers need only a small amount of pieces and are mainly assembled by winding 2 metal sheets together.
  • the manufacturing process is therefore highly simplified which drastically reduces the production cost.
  • FIG. 7 A simplified cutaway drawing of another embodiment of hydraulic gas compression/expansion chamber, based on another design of the integrated heat exchanger is represented in Figure 7.
  • the hydraulic port (H.2.4') is placed on the bottom cover of the compression/expansion enclosure.
  • the drawings of the corresponding integrated heat exchanger are presented in Figures 8a, 8b and 8c.
  • This heat exchanger is limited to the "spiral honeycomb" structure formed by a thin corrugated metal sheet (H.2.2.2') placed on another thin flat metal sheet (H.2.2.1 ') and wound together.
  • the multistage gas directional control module is made of several directional valves for controlling the gas flow direction.
  • each stage is made of a pair of 2-way/2-position valves (H.3a and H.4a; H.3b and H.4b, Figure lb) with integrated check valves that allow connecting the gas port (H.2.3) of the corresponding compression/expansion chamber to that of the next stage (on the left or in the right).
  • These valves are connected in such a way that the integrated check valves are placed in series in the gas circuit, allowing an automatic control of the gas flow during the compression mode.
  • the intake valve (H.3a) of the lowest pressure stage is connected to the buffer storage tank (Tl) through a gas/liquid separator (H.5a), which removes the residual liquid from the gas mainly during discharge mode (downstream flow).
  • the exhaust valve (H.4b) of the highest pressure stage is connected to the high pressure exhaust port (S) through a gas/liquid separator (H.5b), which removes the residual liquid from the gas mainly during compression mode (upstream flow).
  • a pre-compression phase performed by the low pressure compression/expansion unit which aims at compressing the low pressure gas (atmospheric air or gas below lObar) up to a medium pressure (pb preferably in the range 10 to 40bar) and temporary storing it in the buffer tank (T.l).
  • a final compression phase performed by the high pressure compression/expansion unit which aims at further compressing the medium pressure gas (pb) up to the final high pressure (p f above 40bar) and storing it in a high pressure tank (not represented on the drawings) connected on the exhaust port (S).
  • the first expansion phase is performed by the high pressure compression/expansion unit, which aims at expanding the high pressure gas down to a medium pressure (pb) and temporary storing it in the buffer tank (T .1 ) .
  • the post-expansion phase performed by the low pressure compression/expansion unit, which aims at further expanding the medium pressure gas down to the initial pressure (p a ).
  • the two compression/expansion (or conversion) units are connected in series on the gas circuit as can be seen on Figures la, lb and Figures 6a, 6b, and a buffer gas tank (T.l) is connected on their junction point to ensure a proper interface of the two units.
  • a buffer gas tank T.l
  • the conversion units use an active liquid which plays two important roles in the system:
  • the high pressure conversion unit serves as "Power transmitter” (liquid piston) between the gas in each compression/expansion chamber and the corresponding stage of the multistage hydraulic motor/pump.
  • the inventive system needs that the temperature of the active liquid remains constant and close to ambient temperature all the time.
  • This temperature regulation is performed by the active liquid conditioning unit (W) which is designed in such a way that the active liquid always flows in the same time direction, from the return line to the reservoir and then to the supply line.
  • the heat exchanger (W.5) located on the return line is used to compensate the temperature gradient undergone by the active liquid in the conversion units:
  • the temperature of the liquid coming from the conversion units through the port A, B or C is slightly higher than that of the liquid in the reservoir (W. l).
  • the heat exchanger (W.5) cools the active liquid down before feeding it back to the reservoir (W. l) through the filter (W.2) ( Figure la).
  • the temperature of the liquid coming from the conversion units through the port A, B or C is slightly lower than that of the liquid in reservoir (W. l).
  • the heat exchanger (W.5) heats the active liquid up before feeding it back to the reservoir (W.1) through the filter (W.2).
  • the low pressure conversion unit is made of several stages of reversible, positive displacement rotary technologies like scroll or screw compressor/expander stages mounted on a common shaft.
  • the volume of the internal working chamber of these machines continuously decreases when rotating the shaft in one direction to achieve the gas compression function, and it continuously increases when rotating the shaft in the opposite direction to achieve the gas expansion function.
  • the machine is specially designed to tolerate the presence of a substantial amount of active liquid (mainly water) that will keep the gas at constant temperature thanks to its higher heat capacity.
  • the gas By driving the common shaft (L.16) through the electric motor (L.2) in the appropriate direction, the gas is sucked in the first stage (L. la) through the gas filter/silencer (L.15), is compressed and transferred in the second stage (L.lb) for further compression and finally discharged in the buffer storage tank (T.l).
  • the directional valves (L.7a and L.7b) are kept at the illustrated position, thus the injection pump (L.5a) and the spray nozzle (L.6a) are used to inject the liquid inside the first stage to cool the gas being compressed.
  • the injection pump (L.5b) and the spray nozzle (L.6b) do the same thing for the second stage.
  • the inter-stage gas/liquid separator (L.4) and the exhaust gas/liquid separator (L.3b) are used to separate the active liquid from the gas at the end of each compression stage.
  • these separators are full of liquid, their liquid discharge circuit made of the valves (L.10 and L.12) and the pressure relief (L. l 1 and L.13) respectively are activated to discharge the liquid without causing a pressure drop in the main line.
  • the check valve integrated in the exhaust valve (L.14) always allow the discharge of the compressed gas inside the buffer tank (T. l).
  • the directional valves (L.7a and L.7b) are switched to the second position, thus the injection pumps (L.5a and L.5b) and the spray nozzle (L.8a and L.8b) are used to inject liquid inside the working chambers to heat the gas being expanded.
  • the inter-stage gas/liquid separator (L.4) and the intake gas/liquid separator (L.3a) are used to separate the active liquid from the gas at the end of each expansion stage.
  • the liquid in separator (L.4) is discharged in the same way like in pre-compression mode, whereas the intake separator (L.3a) is continuously discharged through its drain port as it isn't pressurised.
  • Compression/expansion phase in the high pressure conversion unit is composed of an even number of hydraulic gas compression/expansion stages, each stage operating as a reciprocating engine in two strokes:
  • An exhaust (or transfer) stroke when the gas is exhausted from the compression/expansion enclosure (H.2a and H.2b). This stroke is active during compression operation mode and passive during expansion operation mode.
  • the compression/expansion process is always performed simultaneously with the gas transfer from one stage to the next one, except for the first and the last stages of the chain that can perform gas transfer with the external tanks (buffer tank or high pressure tank). In that case, the gas transfer from or into the chamber may last only part of the stroke time depending on the pressure level in the related tank. Due to this simultaneity of the compression/expansion and transfer operations, two consecutive stages always operate in opposite stroke, one performing an intake stroke and receiving the gas from the other (or from the external tank) which is performing an exhaust stroke and supplying the gas. Thus, in a 2-stage system as illustrated in Figure lb and 6b, stage A and stage B always operate in opposite stroke.
  • the number of stages depends on the desired maximum final pressure (p f ). For a given desired pressure, the higher this number is, the lower the inter-stage compression ratio "Cr" will be and the higher the thermodynamic efficiency will be also.
  • the ratio between the water capacities of two consecutive compression/expansion chambers is equal to the ratio of the maximum displacements of the related motor/pump stages and corresponds to the interstate compression ratio "Cr".
  • An even number of stages will ensure a more constant mechanical torque all over the cycle, as the number of active stages will be the same during the two strokes (intake and exhaust). With an "N" stages conversion unit, a given mass of gas will flow all over the unit in (N+l) strokes.
  • the compressor operation is described on the basis of the 2-stage conversion unit (H) illustrated in Figures lb and 6b.
  • the 2-way/2-position valves (H.3a, H.4a, H.3b and H.4b) of the multistage gas directional control module are kept in the position illustrated on these Figures; therefore the gas flow is automatically controlled by their integrated check valves.
  • the compression process consists in cycles of two intake/exhaust strokes over the two stages, from the buffer tank pressure (p b ) to the maximum admissible pressure (p f ) of the storage tank connected on port (S).
  • the resulting pressure variation causes the check valves integrated in (H.4a) and (H.3b) to open and allow a continuous transfer of the gas from chamber (H.2a) to chamber (H.2b).
  • the difference in the water capacity of the two chambers causes the pressure in the two chambers to increase almost equally.
  • the displacement of motor/pump (H. la) is controlled to reduce the liquid flow rate as the pressure increases in order to regulate the power and the displacement of motor/pump (H. lb) is adapted to that of motor/pump (H. la) in order to synchronise the operation of both stages.
  • the end of this stroke the initial conditions where the low pressure chamber (H.2a) is full of liquid and the high pressure chamber (H.2b) is full of gas previously compressed from chamber (H.2a) are recreated and a new cycle can start again.
  • the system operates in expansion (or motor) mode in a similar way to the compression mode, but with a reverse gas flow.
  • the motor operation process consists in a series of intake/expansion-exhaust cycles over the sequential stages, from the high pressure tank pressure (p f ) to the medium pressure (p b ).
  • the valve (H.4b) is forced to the "open" position for a determined duration, allowing the right amount of gas from the high pressure tank (not represented) connected to port (S) to enter the high pressure chamber (H.2b) where it pressurises the active liquid.
  • the displacement of the hydraulic motor/pump stage (H. lb) is controlled to generate a negative flow, thus the pressurised liquid drives this stage in motor mode which generates a driving torque on the common shaft (H.10) while the gas expands in chamber (H.2b).
  • the valve (H.3a) is forced to the "open" position during the whole stroke time and the displacement of the hydraulic motor/pump stage (H.la) is controlled to generate a positive flow in order to fill the chamber (H.2a) with liquid and therefore force the previously expanded gas to flow out towards the buffer tank (Tl).
  • the gas contained in chamber (H.2b) can further expand while being continuously transferred into chamber (H.2a) where it pressurises the out flowing liquid that drives in turn the hydraulic stage (H.la) in motor mode.
  • the difference in the water capacity of the two chambers causes the pressure in both chambers to decrease almost equally.
  • the HP stage A is the active one during this stroke.
  • the displacement of motor/pump (H. la) is controlled to increase its flow rate as the pressure decreases in order to regulate the power and the displacement of motor/pump (H.lb) is adapted to that of motor/pump (H.la) in order to synchronise the operation of both stages.
  • the initial conditions where the low pressure chamber (H.2a) is full of gas previously expanded from chamber (H.2b) and the high pressure chamber (H.2b) is full of liquid are recreated and a new cycle can restart.
  • the heat exchange process during the expansion mode is performed in a similar way as for compression mode; e. g. indirectly through the honeycomb structure of the integrated heat exchanger.
  • the liquid reheats the inflowing and expanding gas indirectly through thin wall of the heat exchanger's honeycomb structure, so as to maintain its temperature almost constant.
  • the liquid will be further reheated in the external active liquid conditioning unit.
  • the proposed inventive system and methods provide many technological improvements compared to the state-of-the art compressed gas energy conversion, particularly the system proposed in the US Patent 8 567 183 B2; the most relevant ones are the following:
  • This invention is mainly intended to the production of high pressure gas, particularly air, and use of its potential energy, for the purpose of power transmission and energy storage.
  • One potential application of this invention would be the production of compressed air for industrial applications or for medical and breathing purpose like diving, and fire-fighting.
  • Another potential application would be Pneumatic Energy Storage (or Fuel-free Compressed Air Energy Storage) for renewable energy sources support.
  • Pneumatic Energy Storage or Fuel-free Compressed Air Energy Storage
  • renewable energy sources support In association with an electrical machine and power electronic converters it can be used to circumvent the intermittency of some renewable energy sources such as solar or wind sources.
  • the proposed engine can be used like any classical compressor to condition any gas under high pressure, but with high efficiency.
  • a gas treatment (or purifying) device would be necessary.

Abstract

L'invention concerne des systèmes et des procédés à étages multiples hybrides pour convertir l'énergie potentielle d'un gaz sous pression, en particulier de l'air, en un travail mécanique de deux arbres rotatifs (L.16 et H.10) lors du fonctionnement en mode de détente, et pour produire un gaz comprimé à partir du travail mécanique des deux arbres lors du fonctionnement en mode de compression, par la réalisation d'une détente/compression successive dudit gaz. Le système comprend : une unité de compression/détente à étages multiples basse pression (L) constituée par plusieurs étages de compresseur/détenteur rotatifs volumétriques (L1a, L1b) montés sur un arbre commun (L.16), une unité de compression/détente hydraulique à étages multiples haute pression (H) constituée par plusieurs étages d'enceintes de compression/détente hydrauliques (H.2a, H.2b) combinés à des étages de moteur/pompe à écoulement bidirectionnel volumétriques (H.1a, H 1b), un réservoir de stockage de gaz tampon (T.1) pour le stockage temporaire du gaz à moyenne pression jouant le rôle d'interface des deux unités de compression/détente, et une unité de conditionnement de liquide (W), pour fournir, nettoyer et maintenir un liquide actif à température ambiante.
EP17728454.4A 2016-05-17 2017-05-17 Systèmes et procédés de compression/détente de gaz à étages multiples hybrides Pending EP3807539A1 (fr)

Applications Claiming Priority (2)

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CH6322016 2016-05-17
PCT/EP2017/061862 WO2017198725A1 (fr) 2016-05-17 2017-05-17 Systèmes et procédés de compression/détente de gaz à étages multiples hybrides

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BE1026652B1 (nl) * 2018-09-25 2020-04-28 Atlas Copco Airpower Nv Oliegeïnjecteerde meertraps compressorinrichting en werkwijze om een dergelijke compressorinrichting aan te sturen
EP4001196A1 (fr) 2020-11-13 2022-05-25 Philippe Henneau Système et procédés d'élévateur pneumatique durables

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US1929350A (en) 1930-04-08 1933-10-03 Niels C Christensen Method and apparatus for compressing gases
DE59601569D1 (de) 1995-11-03 1999-05-06 Cyphelly Ivan J Pneumo-hydraulischer wandler für energiespeicherung
US8378521B2 (en) * 2007-05-09 2013-02-19 Ecole Polytechnique Federale de Lausanna (EPFL) Energy storage systems
WO2009034421A1 (fr) 2007-09-13 2009-03-19 Ecole polytechnique fédérale de Lausanne (EPFL) Motocompresseur hydropneumatique à plusieurs étages
US8448433B2 (en) 2008-04-09 2013-05-28 Sustainx, Inc. Systems and methods for energy storage and recovery using gas expansion and compression
ATE528508T1 (de) 2009-06-02 2011-10-15 Ago Ag En & Anlagen Flüssigkolbenwandler
US8196395B2 (en) 2009-06-29 2012-06-12 Lightsail Energy, Inc. Compressed air energy storage system utilizing two-phase flow to facilitate heat exchange
WO2011069015A2 (fr) 2009-12-02 2011-06-09 The Regents Of The University Of Colorado, A Body Corporate Échangeur de chaleur à détente à microcanaux
DE102012003288B3 (de) * 2012-02-20 2013-03-14 Iván Cyphelly Flüssigkolbenanordnung mit Plattentauscher für die quasi-isotherme Verdichtung und Entspannung von Gasen
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