Solid-liquid coupling type two-stage piston type expansion system
Through the solid-liquid coupled two-stage piston expansion system, the compressed air that is not completely expanded is discharged into the water gas co-capacity system, and the water pump and turbine are used to recover the exhaust energy, which solves the problems of strong exhaust fluctuation and large energy loss of the single-stage piston expansion machine, and improves the energy utilization efficiency.
Patent Information
- Application Number
- CN202510339487.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-21
- Publication Date
- 2025-04-25
AI Technical Summary
The existing single-stage piston expanders have strong pressure fluctuations and large energy losses during the exhaust process, which affects the energy utilization efficiency.
A solid-liquid coupled two-stage piston expansion system is adopted. By discharging the compressed air that has not been completely expanded into the water-gas co-capacity system, the pressure energy of the gas is converted into the kinetic energy of water, and the water pump turbine is driven to do work.
It effectively reduces the volatility during exhaust, improves the energy utilization rate of compressed air, and improves the output power and energy utilization efficiency of the expander.
Smart Images
Figure CN119878312A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of air energy storage, and in particular to a solid-liquid coupled two-stage piston expansion system. Background Art
[0002] Compressed air energy storage system (CAES), as a type of energy storage technology, has received widespread attention and in-depth research from all over the world due to its significant advantages of low cost, long life and zero emissions. The working principle of this system is based on using excess electricity to drive the compressor to compress the air and store it in a high-pressure container when the power demand is low, and releasing the high-pressure air to drive the expander to do work when the power demand is peak, and then convert it into electricity or other forms of usable energy, thereby realizing the time and space transfer and efficient utilization of electricity. Among them, the expander is the output link of the air energy storage system. Its efficiency, operating characteristics and adaptability to various working conditions have a decisive influence on the overall operating performance of the air energy storage system; research has shown that piston expanders are more suitable for small CAES systems.
[0003] At present, in actual use, single-stage piston expanders (SSPE) are usually used. Figure 1 , Figure 1 The figure shows a schematic diagram of the three-dimensional structure of SSPE. It can be seen from the figure that SSPE includes a cylinder 1, an intake valve and an exhaust valve are connected to the top of the cylinder 1, a piston 5 is arranged in the cylinder 1, a connecting rod 7 is connected to the bottom of the piston 5, and the other end of the connecting rod 7 is connected to the crankshaft 8, which is driven by the flywheel 6; the working principle of the single-stage piston expander: when air is inhaled, the intake valve is opened, and the exhaust valve is closed at the same time, the working medium (air gas) enters the chamber of the cylinder 1, and the working medium pushes the piston 5 downward to move; after the intake is completed, the intake valve is closed, at this time, the working medium continues to expand and do work, and continues to push the piston 5 to move. When exhausting, the exhaust valve is opened, and the intake valve is closed at the same time, the working medium is discharged from the exhaust valve, and then drives the piston 5 to move upward.
[0004] In order to obtain the characteristics of the gas work process in SSPE, the research team established a mathematical model of SSPE and manufactured a prototype. The simulation and experimental results show that when the intake pressure is 2MPa and the speed is 420r / min, the output power of SSPE is 1.93kW and the energy utilization efficiency is 25%. This performance is difficult to meet the requirements of small CAES systems. In order to improve the energy utilization efficiency, the research team proposed a new two-stage piston expander (TSPE) with a check valve. TSPE consists of two cylinders with a phase angle difference of 180°, in which the diameter of the first-stage cylinder is smaller than that of the second-stage cylinder, and the check valve is located on the side wall at the bottom dead center of the first-stage cylinder. The characteristics of the expander were obtained by simulation technology. The simulation results show that under the same gas supply pressure, the energy utilization efficiency of TSPE is about 15% higher than that of a single-stage piston expander, which is 1.31-1.56 times that of a single-stage expansion air engine. However, the high expansion ratio will inevitably lead to a lower temperature in the cylinder of the two-stage piston expander, resulting in a decrease in the output power and energy utilization efficiency of the piston expander. In order to further improve the output power and energy utilization efficiency of piston expanders and solve the adverse effects of ice blockage and lubricating oil freezing caused by low exhaust temperature of piston expanders, the research team proposed a method of spraying micron-level high-temperature fine water mist into the cylinder of a single-stage piston expander and established a mathematical model. Through full-process simulation and experimental testing of the system, the results showed that under given boundary conditions, the average temperature in the cylinder increased by 24.7%, and the output power and energy utilization efficiency decreased by 7.7% and 12.3% respectively.
[0005] Based on the analysis of the above results, the research team proposed an improved two-stage piston expander (M-TSPE) based on spray heat exchange. Figure 2 . Figure 2The figure shows a schematic diagram of the three-dimensional structure of M-TSPE. The two cylinders of M-TSPE are connected in series on the same crankshaft and have the same connecting rod ratio and piston stroke. The two stages of the cylinder complete the intake, expansion and exhaust. The I-stage piston expander 21 and the II-stage piston expander 22 have the same parts as the above-mentioned SSPE. However, the phase difference between the I-stage and the II-stage is 180°, and the bore ratio of the II-stage cylinder to the I-stage cylinder is about 1.4. A small hole is opened at the top dead center of the I-stage cylinder to lead to the intake valve channel of the II-stage cylinder, and an exhaust valve channel is opened at the top position of the I-stage cylinder to the atmosphere. To ensure rapid response, M-TSPE uses a cam mechanism with dual intake and exhaust valves to control the on and off of the airflow. The detailed working process is shown below. During the I-stage intake stroke, the I-stage intake valve is opened. The gas source gas flows into the I-stage cylinder through the I-stage intake valve, pushing the I-stage piston to move from the top dead center to the bottom dead center. At this time, the exhaust valve of the II-stage cylinder is opened. The II-stage piston moves from the bottom dead center to the top dead center, exhausting the residual air in the II-stage cylinder into the atmosphere. During the I-stage expansion stroke, the I-stage intake valve is closed. The air in the I-stage cylinder expands and does work, pushing the piston to move toward the bottom dead center until it reaches the bottom dead center. At this time, the II-stage piston still moves toward the top dead center until it reaches the top dead center, and all the residual air in the II-stage cylinder is exhausted into the atmosphere. During the I-stage intake and expansion strokes, the water mist nozzle continuously sprays micron-level water mist into the cylinder to exchange heat with the I-stage gas in the cylinder. During the I-stage exhaust utilization stroke, the II-stage intake valve is opened. The water mist and residual air in the I-stage cylinder are first separated by the water mist filter, and the residual air flows into the II-stage cylinder to push the II-stage piston to work. The function of the water mist filter is to prevent water mist from entering the II cylinder, avoid heat exchange between water mist and air in the II-stage cylinder, and prevent the temperature of water mist from dropping to freezing point. During the I-stage exhaust stroke, when the piston of the I-stage cylinder rises to a certain position, the I-stage exhaust valve opens and the II-stage intake valve closes. The residual air and water mist are discharged into the atmosphere through the movement of the I-stage piston and directly reach the top dead center. At this time, the air in the II-stage cylinder expands and does work, pushing the II-stage piston to the bottom dead center. The M-TSPE completes a working cycle. Under given boundary conditions, compared with the two-stage piston expander without spray heat exchange, the output power and energy utilization efficiency of the M-TSPE are increased by 57.58% and 13.28%, respectively.
[0006] However, the problem with the M-TSPE disclosed above is that when the stage II pushes the piston to do positive work, the stage I piston will be acted upon by a reverse force, resulting in strong fluctuations and large energy losses when exhausting from stage I to stage II, thus affecting the energy utilization efficiency of the expander. Therefore, there is an urgent need for a solid-liquid coupled two-stage piston expansion system with small exhaust fluctuations and small energy losses. Summary of the invention
[0007] The purpose of the present invention is to provide a solid-liquid coupled two-stage piston expansion system to solve the problems of high exhaust pressure, strong exhaust volatility and large energy loss of the existing single-stage piston expander mentioned in the above background technology.
[0008] The technical solution adopted by the present invention is as follows: a single-stage piston expansion unit, including a cylinder, a first intake valve and a first exhaust valve are provided on the cylinder, and a control module is provided on the cylinder, and the control module controls the opening or closing of the first intake valve and the first exhaust valve; a branch pipe is provided on one side of the cylinder, and the branch pipe is located below the first exhaust valve. The branch pipe is connected to a water-gas co-containment system, and the water-gas co-containment system is connected to the control module.
[0009] As a further definition of the cylinder: a piston is arranged in the cylinder, one end of the piston is connected to a connecting rod, the other end of the connecting rod is connected to a crankshaft, and the crankshaft is used to be connected to an output device.
[0010] As a further limitation of the control module: the control module includes a controller, which is connected to an intake control unit and an exhaust control unit of a single-stage piston expansion unit, and the exhaust control unit is connected to a water-gas co-capacity system; the intake control unit and the exhaust control unit are used to inflate and deflate the cylinder respectively.
[0011] As an optimization scheme of the present invention: a connecting pipe between the branch pipe and the air inlet end of the water-gas co-capacity system is provided with a water mist filter, and the outflow direction of the water mist filter is consistent with that of the working medium in the branch pipe.
[0012] In the second aspect, the present invention discloses a solid-liquid coupled two-stage piston expansion system, including a single-stage piston expansion unit and a water-gas co-containment system, wherein the branch pipe of the single-stage piston expansion unit is connected to the second air inlet valve of the water-gas co-containment tank through a pipeline, the inlet (outlet) water pipe of the water-gas co-containment tank is connected to one port of a water pump turbine, and the other port of the water pump turbine is connected to a water storage tank; the controller is also connected to an air intake control unit, an exhaust control unit, and an inlet (outlet) water control unit of the water-gas co-containment system, the air intake control unit, the exhaust control unit, and the inlet (outlet) water control unit are connected to the water-gas co-containment tank, and the air intake control unit, the exhaust control unit, and the inlet (outlet) water control unit are respectively used for inflating, exhausting, and inlet (outlet) water to the water-gas co-containment tank.
[0013] As a further limitation of the solid-liquid coupled two-stage piston expansion system: the water-gas co-containment system includes a water-gas co-containment tank, a water pump-turbine, and a water storage tank; the water-gas co-containment tank, the water pump-turbine, and the water storage tank are connected in series.
[0014] The beneficial effects of the present invention are as follows: First, the present invention solves the problem of pressure fluctuation in the exhaust process by organically combining the compressibility of air with the high efficiency of the water pump turbine.
[0015] Secondly, the present invention converts the exhausted gas pressure into the kinetic energy of water through the water-gas co-container to drive the water pump turbine to do work, thereby recovering the exhaust energy and improving the energy utilization efficiency of the expander. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a structural schematic diagram of a single-stage piston expansion unit.
[0017] Figure 2 This is a schematic diagram of the structure of an improved two-stage piston expander.
[0018] Figure 3 It is a schematic diagram of the overall structure of a solid-liquid coupled two-stage piston expansion system.
[0019] Figure 4 This is a schematic diagram of the structure of the water-gas co-containment system.
[0020] Figure 5 This is a schematic diagram of the state of the intake process of a solid-liquid coupled two-stage piston expansion system.
[0021] Figure 6 This is a state diagram of the expansion process of a solid-liquid coupled two-stage piston expansion system.
[0022] Figure 7 This is a state diagram of the exhaust process of a solid-liquid coupled two-stage piston expansion system.
[0023] In the figure: 1. cylinder; 2. first intake valve; 3. water mist nozzle; 4. first exhaust valve; 5. piston; 6. flywheel; 7. connecting rod; 8. crankshaft; 9. branch pipe; 10. water-gas co-container tank; 11. water pump turbine; 12. water storage tank; 13. second intake valve; 14. second exhaust valve; 15. liquid water; 16. valve body; 17. first water inlet; 18. second water inlet; 19. water mist filter; 20. control module; 21. stage I piston expander; 22. stage II piston expander. DETAILED DESCRIPTION
[0024] Embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0025] The terms used in the following embodiments are only for the purpose of describing specific embodiments, and are not intended to be used as limitations to the present application. As used in the specification and the appended claims of the present application, the singular expressions "one", "a kind of", "above", "the" and "this" are intended to also include expressions such as "one or more", unless there is a clear indication to the contrary in the context. It should also be understood that in the following embodiments of the present application, "at least one", "one or more" refer to one, two or more than two.
[0026] The terms "include", "comprising", "having" and variations thereof all mean "including but not limited to", unless specifically emphasized otherwise.
[0027] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0028] A solid-liquid coupled two-stage piston expansion system comprises a single-stage piston expansion unit and a water-gas co-capacity system.
[0029] like Figure 1 and Figure 3 As shown, a single-stage piston expansion unit comprises a cylinder 1, wherein the left and right sides of the top of the cylinder 1 are respectively provided with a first intake valve 2 and a first exhaust valve 4; a water mist nozzle 3 is installed in the cylinder 1; a piston 5 is slidably connected in the cylinder 1, one end of the piston 5 is connected to a connecting rod 7, the other end of the connecting rod 7 is connected to a crankshaft 8, and the other end of the crankshaft 8 is connected to a power output device, and the power output device may select a flywheel 6; a control module 20 is installed on the cylinder 1, and the intake of the first intake valve 2 and the exhaust of the first exhaust valve 4 are both controlled by the control module 20; a branch pipe 9 is provided on one side of the cylinder 1, and the branch pipe 9 is located below the first exhaust valve 4, and the branch pipe 9 is connected to a water-gas co-containment system, and the intake end of the water-gas co-containment tank 10 is connected to the control module 20, and the air discharged from the cylinder 1 is used to provide starting power to the water-gas co-containment system.
[0030] like Figure 3 As shown, the control module 20 is respectively connected to the single-stage piston expansion unit intake control unit and the single-stage piston expansion unit exhaust control unit, and the exhaust control unit is connected to the water-gas co-containment system; the intake control unit has the same structure as the exhaust control unit.
[0031] like Figure 3 and Figure 4As shown, the water-gas co-containment system includes a water-gas co-containment tank 10, a water pump turbine 11 is provided on one side of the water-gas co-containment tank 10, and a water storage tank 12 is provided on one side of the water pump turbine 11; a second air intake valve 13 and a second air exhaust valve 14 are provided on the left and right sides of the top of the water-gas co-containment tank 10, respectively, and a control module 20 controls the air intake of the second air intake valve 13 and the air exhaust of the second air exhaust valve 14; a first water inlet 17 is provided at the bottom of the water-gas co-containment tank 10, and a valve body 16 is installed on the first water inlet 17, and the first water inlet 17 is used The liquid water 15 in the water-gas co-containment tank 10 is discharged into the water pump turbine 11, which is used to drive the water pump turbine 11 to do work. The water pump turbine 11 is used to convert the pressure energy of the gas into the kinetic energy of water to do work. A second water inlet 18 is provided at the bottom of the water storage tank 12. A valve body 16 is installed on the second water inlet 18. The second water inlet 18 is used to provide liquid water 15 for the water-gas co-containment tank 10; the second air inlet valve 13, the second exhaust valve 14 and the first water inlet 17 of the water-gas co-containment tank 10 are all connected to the control module 20.
[0032] Furthermore, when the air inlet end of the water-gas co-container 10, the branch pipe 9 of the single-stage piston expansion unit, and the water pump turbine 11 are in turbine working condition, the outflow direction of the working medium remains consistent.
[0033] Furthermore, a connecting pipe between the branch pipe 9 and the air inlet end of the water-gas co-containment system is provided with a water mist filter 19 , and the outflow direction of the working medium in the water mist filter 19 is consistent with that in the branch pipe 9 .
[0034] Working principle of solid-liquid coupled two-stage piston expansion system: like Figure 5 As shown, it is a state diagram of the air intake process of the solid-liquid coupled two-stage piston expansion system. In the first step, the first air intake valve 2 of the single-stage piston expansion unit is opened through the controller of the control module 20, and the bottom water inlet of the water-gas co-containment tank 10 is opened. At this time, the water pump turbine 11 is in the water pump working condition, and the liquid water 15 level in the water-gas co-containment tank 10 rises; the first exhaust valve 4 of the single-stage piston expansion unit is closed; the piston 5 in the cylinder 1 moves from the top dead center to the bottom dead center.
[0035] like Figure 6 As shown, it is a state diagram of the expansion process of the solid-liquid coupled two-stage piston expansion system. In the second step, when the intake stage is completed, the first intake valve 2 of the single-stage piston expansion unit is closed through the controller of the control module 20, and the cylinder 1 is in a closed state. The air in the cylinder 1 expands and does work, pushing the piston 5 in the cylinder 1 to continue to move downward until the piston 5 reaches the bottom dead center; at this time, the water pump turbine 11 is still in the water pump working condition, and the liquid water 15 level in the water-gas co-containment tank 10 continues to rise until the expansion of the single-stage piston expansion unit is completed.
[0036] like Figure 7As shown, it is a state diagram of the exhaust process of the solid-liquid coupled two-stage piston expansion system. In the third step, the branch pipe 9 of the single-stage piston expansion unit is opened through the controller of the control module 20, and the second intake valve 13 of the water-gas co-container 10 is opened. The gas that has not been fully expanded in the cylinder 1 enters the water-gas co-container 10 to continue to expand, and the gas pressure energy is converted into the kinetic energy of water, driving the water pump turbine 11 to do work. At this time, the water pump turbine 11 is in the turbine working condition; the piston 5 in the cylinder 1 moves from the lower dead center to the upper dead center. When the exhaust utilization is completed, the first exhaust valve 4 of the single-stage piston expansion unit is opened, and the remaining gas is discharged into the atmosphere. At this time, the piston 5 reaches the upper dead center.
[0037] The present invention can discharge the compressed air that is not fully expanded in the single-stage piston expansion unit into the water-gas co-capacity system for reuse, and convert the pressure energy of the gas into the kinetic energy of water. Compared with the output power and energy utilization efficiency of the prior art, the present invention can effectively reduce the volatility of the single-stage piston expansion unit during exhaust, and effectively improve the energy utilization rate of the compressed air, ultimately saving costs.
[0038] Although the present invention has been described in detail with reference to the aforementioned examples, it is still possible for those skilled in the art to make and modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A solid-liquid coupled two-stage piston expansion system, comprising a single-stage piston expansion unit and a water-gas co-containment system, characterized in that: A single-stage piston expansion unit comprises a cylinder (1), wherein the cylinder (1) is provided with a first air intake valve (2), a first exhaust valve (4), and a water mist nozzle (3); a control module (20) is provided on the cylinder (1), and the control module (20) controls the opening or closing of the first air intake valve (2), the first exhaust valve (4), and the water mist nozzle (3); a branch pipe (9) is provided on one side of the cylinder (1), and the branch pipe (9) is connected to a water-gas co-containment system, wherein the water-gas co-containment system comprises a water-gas co-containment system A water storage tank (10), a water pump turbine (11), and a water storage tank (12); the water-gas co-container tank (10) is provided with a second air intake valve (13), a second air exhaust valve (14), and a first water inlet (17); the second air intake valve (13) is connected to a branch pipe (9); the water storage tank (12) is provided with a second water inlet (18); and a control module (20) controls the opening or closing of the second air intake valve (13), the second air exhaust valve (14), the first water inlet (17), and the second water inlet (18).
2. A solid-liquid coupled two-stage piston expansion system according to claim 1, characterized in that: A piston (5) is arranged in the cylinder (1), one end of the piston (5) is connected to a connecting rod (7), the other end of the connecting rod (7) is connected to a crankshaft (8), and the crankshaft (8) is used to be connected to an output device.
3. A solid-liquid coupled two-stage piston expansion system according to claim 1, characterized in that: A water mist nozzle (3) for spraying heat exchange is provided on the cylinder (1), and a control module (20) controls the injection or stopping of micrometer-level water mist.
4. The solid-liquid coupled two-stage piston expansion system according to claim 1, characterized in that: The control module (20) comprises a controller, the controller being connected to an intake control unit and an exhaust control unit of a single-stage piston expansion unit, the intake control unit and the exhaust control unit being connected to the water-gas co-container system; the intake control unit and the exhaust control unit are used to inflate and deflate the cylinder (1), respectively.
5. A solid-liquid coupled two-stage piston expansion system according to claim 4, characterized in that: The controller is also connected to an air intake control unit, an exhaust control unit, and an inlet and outlet water control unit of the water-gas co-containment system. The air intake control unit, the exhaust control unit, and the inlet and outlet water control unit are connected to the water-gas co-containment tank (10). The air intake control unit, the exhaust control unit, and the inlet and outlet water control unit are used to inflate, exhaust, and inlet and outlet water to the water-gas co-containment tank (10), respectively.
6. The solid-liquid coupled two-stage piston expansion system according to claim 1, characterized in that: The water-gas co-container tank (10) is connected to the water pump turbine (11); the water pump turbine (11) is connected in series with the water storage tank (12).
7. The solid-liquid coupled two-stage piston expansion system according to claim 1, characterized in that: A water mist filter (19) is provided on the connecting pipe between the branch pipe (9) and the water-gas co-container tank (10), and the working medium in the water mist filter (19) and the branch pipe (9) flows out in the same direction.