CN114810238B - Self-pressure enhanced gravity compressed air energy storage system and energy storage method - Google Patents

Self-pressure enhanced gravity compressed air energy storage system and energy storage method Download PDF

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Publication number
CN114810238B
CN114810238B CN202210718852.9A CN202210718852A CN114810238B CN 114810238 B CN114810238 B CN 114810238B CN 202210718852 A CN202210718852 A CN 202210718852A CN 114810238 B CN114810238 B CN 114810238B
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air cavity
air
pipeline
energy storage
cavity
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CN114810238A (en
Inventor
文军
梅生伟
赵瀚辰
姚明宇
薛小代
张学林
李阳
杨成龙
张通
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Tsinghua University
Xian Thermal Power Research Institute Co Ltd
Huaneng Group Technology Innovation Center Co Ltd
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Tsinghua University
Xian Thermal Power Research Institute Co Ltd
Huaneng Group Technology Innovation Center Co Ltd
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01KSTEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K3/00Plants characterised by the use of steam or heat accumulators, or intermediate steam heaters, therein
    • F01K3/006Accumulators and steam compressors
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03GSPRING, WEIGHT, INERTIA OR LIKE MOTORS; MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOT OTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISE PROVIDED FOR
    • F03G3/00Other motors, e.g. gravity or inertia motors
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04BPOSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B35/00Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for
    • F04B35/04Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for the means being electric
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04BPOSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B41/00Pumping installations or systems specially adapted for elastic fluids
    • F04B41/02Pumping installations or systems specially adapted for elastic fluids having reservoirs
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04BPOSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B41/00Pumping installations or systems specially adapted for elastic fluids
    • F04B41/06Combinations of two or more pumps
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/16Mechanical energy storage, e.g. flywheels or pressurised fluids

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)

Abstract

The invention provides a self-pressure enhanced gravity compressed air energy storage system and an energy storage method, wherein the energy storage system comprises a closed air cavity, a communication pipeline, a multistage compressor unit and an air expansion unit which are connected in series, wherein a gravity plunger is movably inserted in the closed air cavity, and the gravity plunger is hermetically connected with the closed air cavity so as to divide the closed air cavity into an upper air cavity and a lower air cavity through the gravity plunger; two ends of the communicating pipeline are respectively connected with the upper air cavity and the lower air cavity, and a valve is arranged on the communicating pipeline; the multistage compressor sets connected in series are connected with the lower air cavity through the energy storage pipeline and used for inflating the lower air cavity, and the middle stage air suction port of the multistage compressor sets connected in series is connected with the upper air cavity; the air expansion unit is connected with the lower air cavity through an energy releasing pipeline. The constant pressure of the air storage device in the air charging and discharging process can be realized, the stability of the outlet pressure of the air compressor and the inlet pressure of the air expander is guaranteed, the operation efficiency of the air compressor and the expander is further improved, and the energy storage efficiency of the system is improved.

Description

Self-pressure enhanced gravity compressed air energy storage system and energy storage method
Technical Field
The invention relates to the technical field of electric energy storage, in particular to a self-pressure enhanced gravity compressed air energy storage system and an energy storage method.
Background
The storage of energy, in particular electrical energy, is of great importance for the optimization of the energy structure and the regulation of the operation of the power grid. The compressed air energy storage system is a novel large-scale energy storage technology, the working principle is similar to that of pumped storage, when the power consumption of a power system is in a valley, electric energy is consumed to drive an air compressor, and energy is stored in an air storage device in a compressed air mode; when the electric load of the power system reaches a peak, the stored compressed air is released by the air storage device, and is expanded in the turboexpander to do work and drive the generator to generate electricity; according to the principle, the compressed air energy storage system can complete the conversion of electric energy-air potential energy-electric energy.
Conventional compressed air energy storage systems generally employ a fixed volumetric air storage device to store compressed air. According to the gas state equation and the common sense, the fixed volume gas storage device can generate the change of gas storage pressure in the process of charging and discharging gas. Specifically, as the inflation process is carried out, the air storage pressure in the air storage device gradually rises, so that the air compressor is required to continuously increase the exhaust pressure to meet the requirement of the intake pressure, the air compressor deviates from the design working condition to operate, the operation efficiency is reduced, the operation power consumption is increased, and the increase of the energy storage efficiency of the system is limited; similarly, as the air discharging process is carried out, the air storage pressure in the air storage device is gradually reduced, so that the air inlet pressure of the air expansion machine is gradually reduced, the air expansion machine deviates from the designed working condition to operate, the operation efficiency is reduced, the output power is reduced, and the improvement of the energy storage efficiency of the system is further limited.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.
Therefore, the invention aims to provide an autogenous pressure enhanced gravity compressed air energy storage system, which can realize constant pressure of an air storage device in the process of air charging and discharging, ensure the stability of the outlet pressure of an air compressor and the inlet pressure of an air expander, further improve the operation efficiency of the air compressor and the expander and improve the energy storage efficiency of the system; in addition, because the pressure working condition is stable, the design difficulty and the production cost of the air compressor and the air expander can be reduced.
In order to achieve the above object, the present invention provides a self-pressure-enhanced gravity compressed air energy storage system, comprising:
the device comprises a closed air cavity, wherein a gravity plunger is movably inserted in the closed air cavity, and the gravity plunger is hermetically connected with the closed air cavity so as to divide the closed air cavity into an upper air cavity and a lower air cavity through the gravity plunger;
the two ends of the communicating pipeline are respectively connected with the upper air cavity and the lower air cavity, and a valve is arranged on the communicating pipeline;
the multistage compressor units are connected in series, connected with the lower air cavity through an energy storage pipeline and used for inflating the lower air cavity, and a middle-stage air suction port of each multistage compressor unit is connected with the upper air cavity through an air suction pipeline;
and the air expansion unit is connected with the lower air cavity through an energy release pipeline.
Further, an air inlet sealing valve is arranged at an air inlet of the lower air cavity, one end of an energy storage pipeline is connected to the air inlet sealing valve, and the other end of the energy storage pipeline is connected with an air outlet of the series-connected multi-stage compressor unit;
and a first air outlet sealing valve is arranged at an air outlet of the lower air cavity, one end of the energy release pipeline is connected to the first air outlet sealing valve, and the other end of the energy release pipeline is connected with an air inlet of the air expansion unit.
Furthermore, an air outlet is formed in the upper air cavity, a second air outlet sealing valve is arranged at the air outlet, and one end of the air suction pipeline is connected to the second air outlet sealing valve.
Furthermore, a sealing film is arranged between the outer wall of the gravity plunger and the inner wall of the closed air cavity, the sealing film is sleeved outside the gravity plunger, and the sealing film is respectively connected with the outer wall of the gravity plunger and the inner wall of the closed air cavity in a sealing manner.
Further, the closed air cavity is of a cylindrical structure;
a plurality of smooth grooves which are vertically distributed are arranged on the periphery of the outer wall surface of the gravity plunger;
the seal membrane is established for the cover the outside annular tubular structure of gravity plunger, the external diameter of seal membrane equals the internal diameter of airtight air cavity, the seal membrane turns over the annular saddle face structure that forms with the inner ring after turning over upper portion inwards from the centre, turns over the back and obtains the inner ring week side forms the fold arch, the bottom of outer ring with airtight air cavity inner wall sealing connection, the bottom of inner ring with the outer wall sealing connection of gravity plunger, the fold arch with level and smooth groove laminating.
Furthermore, the annular cylindrical structure of the sealing membrane is a cylindrical surface structure with the upper diameter and the lower diameter being equal.
Further, the circumferential perimeter of the section of the gravity plunger at the smooth groove is equal to the outer circumferential perimeter of the circular section of the sealing membrane tubular structure.
Further, the self-pressure enhanced gravity compressed air energy storage method comprises the following steps:
the gravity plunger is hermetically connected with the closed air cavity, so that the closed air cavity is divided into an upper air cavity and a lower air cavity through the gravity plunger;
during energy storage, an energy storage pipeline connected between the multistage compressor set and the lower air cavity in series and an air suction pipeline connected between a middle-stage air suction port of the multistage compressor set and the upper air cavity in series are opened, an energy release pipeline connected between the air expansion unit and the lower air cavity and a communication pipeline connected between the upper air cavity and the lower air cavity are closed, the motor drives the multistage compressor set in series to compress air to form compressed air by utilizing electric energy, the compressed air is inflated to the lower air cavity through the energy storage pipeline, the compressed air pushes the gravity plunger to move upwards to compress air in the upper air cavity, the compressed air in the upper air cavity enters the middle-stage air suction port of the multistage compressor set in series through the air suction pipeline to be compressed and then is introduced into the lower air cavity through the energy storage pipeline, and the pressure difference between the upper air cavity and the lower air cavity is constant in the inflation process;
when releasing energy, open the energy release pipeline, close the energy storage pipeline, the pipeline of breathing in, the intercommunication pipeline, the lower part air cavity is to the gassing of air expander group, gravity plunger downstream, the valve on the intercommunication pipeline is opened when the pressure differential between upper portion air cavity and lower part air cavity reaches a definite value, make the compressed gas in the lower part air cavity get into the upper portion air cavity with controlled state, in order to keep upper portion air cavity and lower part air cavity pressure differential invariable, maintain lower part air cavity pressure invariable simultaneously, compressed air gets into the air expander group and does work, drive the generator electricity generation.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The foregoing and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic structural diagram of a self-pressure-enhanced gravity compressed air energy storage system according to an embodiment of the present invention;
FIG. 2 is a schematic view of the gravity plunger of the present invention;
fig. 3 is a partial structural schematic view of fig. 1.
In the figure, 1, a closed air cavity; 11. an upper air cavity; 12. a lower air cavity; 2. a communicating pipeline; 3. a plurality of compressor units connected in series; 31. an energy storage pipeline; 4. an air expander set; 41. an energy release pipeline; 5. a gravity plunger; 51. smoothing the groove; 6. a valve; 7. an air intake pipeline; 8. a sealing film; 81. an outer ring; 82. an inner ring.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention. On the contrary, the embodiments of the invention include all changes, modifications and equivalents coming within the spirit and terms of the claims appended hereto.
Fig. 1 is a schematic structural diagram of a self-pressure-enhanced gravity compressed air energy storage system according to an embodiment of the present invention.
Referring to fig. 1, a self-pressure enhanced gravity compressed air energy storage system comprises a closed air cavity 1, a communication pipeline 2, a multistage compressor unit 3 and an air expansion unit 4 which are connected in series, wherein a gravity plunger 5 is movably inserted into the closed air cavity 1, the gravity plunger 5 is connected with the closed air cavity 1 in a sealing manner, so that the closed air cavity 1 is divided into an upper air cavity 11 and a lower air cavity 12 through the gravity plunger 5, that is, a piston-cylinder structure is formed between the gravity plunger 5 and the closed air cavity 1, and the gravity plunger 5 can move up and down in the closed air cavity 1.
The both ends of the communicating pipe 2 are connected with the upper air chamber 11 and the lower air chamber 12 respectively, and the valve 6 is provided on the communicating pipe 2, that is, the upper air chamber 11 and the lower air chamber 12 are communicated through the communicating pipe 2, so that ventilation can be performed between the two, and simultaneously, the communication between the upper air chamber 11 and the lower air chamber 12 can be controlled by controlling the opening and closing of the valve 6.
In addition, the multistage compressor set 3 connected in series is connected with the lower air cavity 12 through the energy storage pipeline 31 and used for inflating the lower air cavity 12, a middle-stage air suction port of the multistage compressor set 3 connected in series is connected with the upper air cavity 11 through the air suction pipeline 7, meanwhile, the air expansion unit 4 is connected with the lower air cavity 12 through the energy release pipeline 41, the air expansion unit 4 is connected with a generator, in the compression process, a valve 6 on the communication pipeline 2 is closed, at the moment, the upper air cavity 11 and the lower air cavity 12 are separated and not inflated, the multistage compressor set 3 connected in series inflates the lower air cavity 12, the gravity plunger 5 moves upwards to compress the upper air cavity 11, so that the gas in the upper air cavity 11 has certain pressure, the gas with certain pressure in the upper air cavity 11 is introduced into the middle-stage air suction port of the multistage compressor set 3 connected in series, the gas with certain pressure can be compressed and then introduced into the lower air cavity 12 for cyclic utilization, the gas with certain pressure is directly discharged out of the atmosphere, the energy loss is reduced, the pressure difference between the upper air cavity 11 and the lower air cavity 12 is kept constant in the inflation process, and the self weight of the pressure plunger 5 is kept at the higher pressure level. In the expansion process, the lower air cavity 12 deflates the air expander set 4, when the pressure difference between the upper air cavity 11 and the lower air cavity 12 reaches a certain value, the valve 6 on the communicating pipeline 2 is controlled to be opened, so that high-pressure air in the lower air cavity 12 enters the upper air cavity 11 in a controlled state, the pressure difference between the upper air cavity and the lower air cavity is kept constant, and the pressure of the lower air cavity 12 is kept constant, so that the constant pressure of the closed air cavity 1 in the inflation and deflation process can be realized, the stability of the outlet pressure of the air compressor and the inlet pressure of the air expander can be ensured, the operating efficiency of the air compressor and the expander can be further improved, and the energy storage efficiency of the system can be further improved; similarly, for the air expander, the actual operation efficiency under the designed working condition is highest, if the air inlet pressure changes, the operation efficiency is reduced, the air outlet is reduced, and the energy storage efficiency of the system is reduced; in addition, if compressor and expander need deal with the operating condition of great pressure fluctuation, need carry out special design, lead to the design degree of difficulty and manufacturing cost to rise, equipment structure is complicated, and skew operating condition operation also can lead to the operation life-span to shorten to a certain extent, consequently, through the control pressure operating mode stable in this application for air compressor and air expander design degree of difficulty and manufacturing cost all can reduce. Meanwhile, the weight and the height of the gravity plunger 5 can be reduced and the cost is reduced by applying pressure to the gravity plunger 5 through the upper cavity 11; by reasonably setting the upper and lower pressure difference of the gravity plunger 5, the requirement of sealing between the gravity plunger 5 and the wall surface of the closed air cavity 1 can be reduced, so that the technical difficulty and the cost of high-pressure air sealing are reduced; in addition, because the system is in a fully sealed state, under the state that the position of the gravity plunger 5 is locked, if high-pressure gas in the lower air cavity 12 leaks from the wall surface of the closed air cavity 1 through the gravity plunger 5, the leaked gas can enter the upper air cavity 11, so that the pressure of the upper air cavity 11 is increased, the pressure difference between the upper air cavity 11 and the lower air cavity 12 is reduced, the sealing effect is further enhanced, and the air leakage is reduced; even if air leakage occurs, the air leaked into the upper air cavity of the low pressure is still maintained at a certain pressure and is directly utilized by the compressor in the next compression process, so that the total energy loss of the system is reduced. In addition, in order to ensure that the gravity plunger 5 is in an initial state, enough space can be filled with compressed gas in the lower air cavity 12, the gravity plunger 5 can be pushed to move upwards, at the moment, a supporting device can be arranged at the bottom of the lower air cavity 12, the gravity plunger 5 can be supported through the supporting device, so that when the gravity plunger 5 descends to the lowest limit position, after the gravity plunger 5 is supported by the supporting device, a certain space still remains in the lower air cavity 12 at the lower part of the closed air cavity 1, the compressed air introduced into the lower air cavity 12 is enough to push the gravity plunger 5 to move upwards, wherein the supporting device can be an existing device capable of supporting the gravity plunger 5, and detailed description is omitted.
In some embodiments, the air inlet of the lower air cavity 12 is provided with an air inlet sealing valve, and one end of the energy storage pipeline 31 is connected to the air inlet sealing valve, and the other end is connected to the air outlet of the series multi-stage compressor unit 3; the air outlet of the lower air cavity 12 is provided with a first air outlet sealing valve, one end of the energy releasing pipeline 41 is connected to the first air outlet sealing valve, and the other end of the energy releasing pipeline is connected to the air inlet of the air expansion unit 4, so that during energy storage, the first air outlet sealing valve is closed, at the moment, the energy storage pipeline 31 is communicated with the lower air cavity 12, during energy release, the air inlet sealing valve is closed, and at the moment, the energy releasing pipeline 41 is communicated with the lower air cavity 12.
In addition, an air outlet is formed in the upper air cavity 11, a second air outlet sealing valve is arranged at the air outlet, an air suction pipeline 7 is connected to a middle-stage air suction port of the serially connected multi-stage compressor set 3, and one end of the air suction pipeline 7 is connected to the second air outlet sealing valve.
In some embodiments, the air expander train 4 comprises multiple stages of series connected expanders.
It should be noted that the gravity plunger 5 and the sealed air cavity 1 are hermetically connected, and the sealing connection mode can be various.
Referring to fig. 2 and 3, as a possible case, a sealing film 8 is disposed between the outer wall of the gravity plunger 5 and the inner wall of the closed air cavity 1, the sealing film 8 is sleeved outside the gravity plunger 5, and the sealing film 8 is respectively connected with the outer wall of the gravity plunger 5 and the inner wall of the closed air cavity 1 in a sealing manner, so that the closed air cavity 1 is divided into an upper air cavity 11 and a lower air cavity 12 which are respectively sealed.
In detail, the closed air cavity 1 is a cylindrical tubular structure, a plurality of smooth grooves 51 which are vertically distributed are arranged on the peripheral side of the outer wall surface of the gravity plunger 5, wherein the vertical direction is consistent with the axial direction of the gravity plunger 5, the sealing membrane 8 is an annular tubular structure which is sleeved outside the gravity plunger 5, the outer diameter of the sealing membrane 8 is equal to the inner diameter of the closed air cavity 1, the upper part of the sealing membrane 8 is turned inwards from the middle to form an annular saddle surface structure which is formed by connecting an outer ring 81 and an inner ring 82, a folded bulge is formed on the peripheral side of the inner ring 82 obtained after turning, the top end of the outer ring 81 is connected with the top end of the inner ring 82, the bottom end of the outer ring 81 is connected with the inner wall of the closed air cavity 1 in a sealing manner, the bottom end of the inner ring 82 is connected with the outer wall of the gravity plunger 5 in a sealing manner, the folded bulge is attached to the smooth grooves 51, and through the arrangement, allow seal membrane 8 to cave in smooth groove 51, thereby increase the length that the outer wall meets with seal membrane 8 to the ring of gravity plunger 5, make seal membrane 8 fix the length increase in gravity plunger 5 week side, outer loop 81 and inner ring 82 that reciprocate in-process seal membrane 8 at gravity plunger 5 remain all the time with airtight air cavity 1 inner wall, the good laminating of gravity plunger 5 outer wall, the direct laminating point of gravity plunger 5 and seal membrane 8 has been increased, and because the external diameter of seal membrane 8 is the same with the internal diameter of airtight air cavity 1, and then make seal membrane 8's outer loop 81 can laminate on airtight air cavity 1 inner wall completely, provide the support for seal membrane 8 by airtight air cavity 1 and gravity plunger 5 rigid wall, counteract the hoop tension because pressure causes, seal membrane 8 safety in utilization, reliability and life-span have been improved.
In detail, because the inner ring 82 that the sealing membrane 8 formed after being turned over is located the inside of outer ring 81, the sealing membrane 8 is the tubular structure, the inner ring 82 after being turned over is in order to adapt to the size of the circumferential space, fold bulge can appear, fold bulge is not met with the lateral wall of gravity plunger 5, through set up a plurality of smooth grooves 51 that are vertical distribution in the week side of gravity plunger 5, make the fold bulge can arrange smooth groove 51 in, and then can ensure that fold bulge also can laminate with gravity plunger 5, make the sealing membrane 8 hoop and the area that gravity plunger 5 combines increase, support sealing membrane 8 fold bulge through smooth groove 51 in gravity plunger 5, can improve the support stability of sealing membrane 8, and then offset the hoop tension that sealing membrane 8 produced under the pressure condition through the solid wall, promote sealing membrane 8 safety in use, reliability and life, and fix fold bulge in smooth groove 51 and make fold bulge sealing performance reinforcing.
In some embodiments, the annular cylindrical structure of the sealing membrane 8 is a cylindrical structure with an equal diameter at the upper and lower parts, so that the processing is easier.
It should be noted that, the circumferential length of the gravity plunger 5 in the circumferential direction of the cross section at the smooth groove 51 is equal to the circumferential length of the sealing membrane 8 in the circumferential direction of the tubular structure, and the depth and number of the smooth grooves 51 are controlled to increase the circumferential length of the gravity plunger 5 in the circumferential direction at the smooth groove 51 (to the extent that the smooth groove 51 penetrates the bottom end of the gravity plunger 5, the circumferential length of the gravity plunger 5 in the circumferential direction at the smooth groove 51 is the circumferential length at the bottom end face side of the gravity plunger 5, and the circumferential length of the outer wall of the sealing membrane 8 in the circumferential direction is the circumferential length at the outer barrel end face side of the sealing membrane annular tubular structure), the part of the fold protrusion of the inner ring 82 can be fitted in the smooth groove 51, and the gravity plunger 5 can support the sealing membrane 8, thereby improving the safety, reliability and the service life of the sealing membrane 8.
In some embodiments, a self-pressure-enhanced gravity compressed air energy storage method includes the following steps:
the gravity plunger 5 is hermetically connected with the closed air cavity 1, so that the closed air cavity 1 is divided into an upper air cavity 11 and a lower air cavity 12 through the gravity plunger 5;
during energy storage, an energy storage pipeline 31 connected between the multistage compressor set 3 and the lower air cavity 12 in series and an air suction pipeline 7 connected between a middle-stage air suction port of the multistage compressor set 3 and the upper air cavity 11 in series are opened, an energy release pipeline 41 connected between the air expansion unit 4 and the lower air cavity 12 and a communication pipeline 2 connected between the upper air cavity 11 and the lower air cavity 12 are closed, the motor drives the multistage compressor set 3 in series to compress gas by utilizing electric energy to form compressed gas, the compressed gas is inflated to the lower air cavity 12 through the energy storage pipeline 31, the compressed gas pushes the gravity plunger 5 to move upwards to compress the gas in the upper air cavity 11, the compressed gas in the upper air cavity 11 enters the middle-stage air suction port of the multistage compressor set 3 in series through the air suction pipeline 7 to be compressed and then is introduced into the lower air cavity 12 through the energy storage pipeline 31, and the pressure difference between the upper air cavity 11 and the lower air cavity 12 in the inflation process is constant;
when releasing energy, the energy releasing pipeline 41 is opened, the energy storage pipeline 31, the air suction pipeline 7 and the communication pipeline 2 are closed, the lower air cavity 12 discharges air to the air expansion unit 4, the gravity plunger 5 moves downwards, a valve on the communication pipeline 2 is opened when the pressure difference between the upper air cavity 11 and the lower air cavity 12 reaches a certain value, namely the valve is opened under the control of a pressure difference signal, so that compressed air in the lower air cavity 12 enters the upper air cavity 11 in a controlled state, the pressure difference between the upper air cavity 11 and the lower air cavity 12 is kept constant, meanwhile, the pressure of the lower air cavity 12 is kept constant, the compressed air enters the air expansion unit 4 to do work, a generator is driven to generate electricity, and the gravitational potential energy of the gravity plunger 5 is also converted into partial electric energy.
It should be noted that, in the description of the present invention, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (6)

1. A self-pressure enhanced gravity compressed air energy storage system, comprising:
the device comprises a closed air cavity, wherein a gravity plunger is movably inserted in the closed air cavity, and the gravity plunger is hermetically connected with the closed air cavity so as to divide the closed air cavity into an upper air cavity and a lower air cavity through the gravity plunger;
the two ends of the communicating pipeline are respectively connected with the upper air cavity and the lower air cavity, and a valve is arranged on the communicating pipeline;
the multistage compressor units are connected in series, connected with the lower air cavity through an energy storage pipeline and used for inflating the lower air cavity, and a middle-stage air suction port of each multistage compressor unit is connected with the upper air cavity through an air suction pipeline;
the air expansion unit is connected with the lower air cavity through an energy releasing pipeline, a valve on a communication pipeline is closed in the compression process, the upper air cavity and the lower air cavity are separated and not ventilated, the serially connected multistage compressor units inflate the lower air cavity, a gravity plunger moves upwards to compress the upper air cavity, so that the air in the upper air cavity has certain pressure, the air with certain pressure in the upper air cavity is introduced into a middle-stage air inlet of the serially connected multistage compressor units, the air with certain pressure can be compressed and then introduced into the lower air cavity for cyclic utilization, the pressure difference between the upper air cavity and the lower air cavity in the inflation process is kept constant, the lower air cavity deflates the air expansion unit in the expansion process, when the pressure difference between the upper air cavity and the lower air cavity reaches a certain value, the valve on the communication pipeline is controlled to be opened, the high-pressure air in the lower air cavity 1 enters the upper air cavity in a controlled state, so that the pressure difference between the upper air cavity and the lower air cavity is kept constant, and the pressure of the lower air cavity is kept constant, and further the constant pressure of the closed air cavity in the inflation and deflation process can be realized;
a sealing film is arranged between the outer wall of the gravity plunger and the inner wall of the closed air cavity, the sealing film is sleeved outside the gravity plunger, and the sealing film is respectively connected with the outer wall of the gravity plunger and the inner wall of the closed air cavity in a sealing manner;
the closed air cavity is of a cylindrical structure;
a plurality of smooth grooves which are vertically distributed are arranged on the periphery of the outer wall surface of the gravity plunger;
the seal membrane is established for the cover the outside annular tubular structure of gravity plunger, the external diameter of seal membrane equals the internal diameter of airtight air cavity, the seal membrane turns over the annular saddle face structure that forms with the inner ring is connected to upper portion after turning over inwards from the centre, turns over the back and obtains the inner ring week side forms the fold arch, the bottom of outer ring with airtight air cavity inner wall sealing connection, the bottom of inner ring with the outer wall sealing connection of gravity plunger, the fold arch with level and smooth groove laminating.
2. The self-pressure enhanced gravity compressed air energy storage system according to claim 1, wherein the air inlet of the lower air cavity is provided with an air inlet sealing valve, one end of the energy storage pipeline is connected to the air inlet sealing valve, and the other end of the energy storage pipeline is connected with the air outlet of the series multistage compressor set;
and a first air outlet sealing valve is arranged at an air outlet of the lower air cavity, one end of the energy release pipeline is connected to the first air outlet sealing valve, and the other end of the energy release pipeline is connected with an air inlet of the air expansion unit.
3. The self-pressure enhanced gravity compressed air energy storage system according to claim 1, wherein an air outlet is provided on the upper air cavity, a second air outlet sealing valve is provided at the air outlet, and one end of the air suction pipeline is connected to the second air outlet sealing valve.
4. The self-pressure enhanced gravity compressed air energy storage system according to claim 1, wherein the annular cylindrical structure of the sealing membrane is a cylindrical structure with an upper diameter and a lower diameter.
5. The self-pressurizing enhanced gravity compressed air energy storage system of claim 4 wherein the circumferential cross-sectional circumference of the gravity plunger at the smooth groove is equal to the outer circumferential circumference of the sealing membrane cylinder cross-sectional circle.
6. An energy storage method based on the self-pressure-enhanced gravity compressed air energy storage system as claimed in any one of claims 1 to 5, characterized by comprising the following steps:
the gravity plunger is hermetically connected with the closed air cavity, so that the closed air cavity is divided into an upper air cavity and a lower air cavity through the gravity plunger;
during energy storage, an energy storage pipeline connected between the serially connected multistage compressor set and the lower air cavity and an air suction pipeline connected between a middle-stage air suction port of the serially connected multistage compressor set and the upper air cavity are opened, an energy release pipeline connected between the air expansion unit and the lower air cavity and a communication pipeline connected between the upper air cavity and the lower air cavity are closed, the motor drives the serially connected multistage compressor set to compress air to form compressed air by utilizing electric energy, the compressed air is inflated to the lower air cavity through the energy storage pipeline, the compressed air pushes the gravity plunger to move upwards to compress the air in the upper air cavity, the compressed air in the upper air cavity enters the middle-stage air suction port of the serially connected multistage compressor set through the air suction pipeline to be compressed and then is introduced into the lower air cavity through the energy storage pipeline, and the pressure difference between the upper air cavity and the lower air cavity is constant in the inflation process;
when releasing energy, the energy release pipeline is opened, the energy storage pipeline is closed, the air suction pipeline and the communication pipeline are closed, the lower air cavity discharges air to the air expansion unit, the gravity plunger moves downwards, the valve on the communication pipeline is opened when the pressure difference between the upper air cavity and the lower air cavity reaches a certain value, compressed air in the lower air cavity enters the upper air cavity in a controlled state, so that the pressure difference between the upper air cavity and the lower air cavity is constant, meanwhile, the pressure of the lower air cavity is constant, and the compressed air enters the air expansion unit to do work, so that the generator is driven to generate electricity.
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