Detailed Description
Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the application.
In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present application and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present application. Furthermore, features defining "first", "second" may include one or more such features, either explicitly or implicitly. In the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.
In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present application will be understood in specific cases by those of ordinary skill in the art.
An energy storage power generation circulation system according to an embodiment of the present application is described below with reference to fig. 1 to 2.
The energy storage power generation circulation system provided by the embodiment of the application can be applied to the renewable energy power storage fields such as peak shaving, low-valley power utilization, wind power, photovoltaic and the like of a thermal power plant.
As shown in fig. 1, the energy storage power generation cycle system according to one embodiment of the present application includes: the heat storage device, the cold storage device, the driving mechanism 1, the compressor 2, the first reversing valve 3, the first heat exchanger 4, the intermediate heat exchanger 5, the turbine 6, the generator 7, the second reversing valve 8 and the second heat exchanger 9.
Wherein the driving mechanism 1 is in power coupling connection with the compressor 2, and in the energy storage and power generation circulation system in an energy storage working mode, the driving mechanism 1 is used for driving the compressor 2 to work, and in actual implementation, the driving mechanism 1 may comprise an electric motor, or the driving mechanism 1 may comprise a turbine of a wind driven generator, or the like.
The turbine 6 is in power coupling connection with the generator 7, the turbine 6 is used for rotating under the driving of the working medium so as to enable the working medium to expand and do work, and in a power generation working mode, the turbine 6 is used for driving the generator 7 to generate power.
In actual implementation, the compressor 2 is coupled in power-driven connection with the turbine 6 and rotates synchronously.
The compressor 2, the first reversing valve 3, the first heat exchanger 4, the intermediate heat exchanger 5, the turbine 6, the second reversing valve 8 and the second heat exchanger 9 are connected to form a brayton cycle (forward cycle and reverse cycle), and working substances in the brayton cycle can be gaseous working substances, and the gaseous working substances can be air, nitrogen, argon, helium, hydrogen, carbon dioxide and the like.
As shown in fig. 1, an air outlet end of the compressor 2, a first path of the first heat exchanger 4, an air inlet end of the turbine 6 and a first path of the intermediate heat exchanger 5 are respectively connected with four valve ports of the first reversing valve 3, and the first path of the first heat exchanger 4 is connected with the first path of the intermediate heat exchanger 5; the air outlet end of the turbine 6, the first path of the second heat exchanger 9, the air inlet end of the compressor 2 and the second path of the intermediate heat exchanger 5 are respectively connected with four valve ports of the second reversing valve 8, and the first path of the second heat exchanger 9 is connected with the second path of the intermediate heat exchanger 5; the heat storage device is connected with the second path of the first heat exchanger 4, and the cold storage device is connected with the second path of the second heat exchanger 9.
In actual implementation, as shown in fig. 1, the air outlet end of the compressor 2 is connected to the first valve port 3a of the first reversing valve 3, the second valve port 3b of the first reversing valve 3 is connected to one end (left end in fig. 1) of the first path of the first heat exchanger 4, the other end (right end in fig. 1) of the first path of the first heat exchanger 4 is connected to one end (right end in fig. 1) of the first path of the intermediate heat exchanger 5, the other end (left end in fig. 1) of the first path of the intermediate heat exchanger 5 is connected to the fourth valve port 3d of the first reversing valve 3, and the third valve port 3c of the first reversing valve 3 is connected to the air inlet end of the turbine 6; the outlet end of the turbine 6 is connected to the first port 8a of the second reversing valve 8, the second port 8b of the second reversing valve 8 is connected to one end (right end in fig. 1) of the first path of the second heat exchanger 9, the other end (left end in fig. 1) of the first path of the second heat exchanger 9 is connected to one end (left end in fig. 1) of the second path of the intermediate heat exchanger 5, the other end (right end in fig. 1) of the second path of the intermediate heat exchanger 5 is connected to the fourth port 8d of the second reversing valve 8, and the third port 8c of the second reversing valve 8 is connected to the inlet end of the compressor 2.
The high temperature end heat storage medium in the heat storage device can exchange heat with working medium in the brayton cycle in the first heat exchanger 4, and the low temperature end cold storage medium in the cold storage device can exchange heat with working medium in the brayton cycle in the second heat exchanger 9.
The energy storage power generation circulation system has an energy storage working mode and a power generation working mode, and particularly an intermediate heat exchanger 5 for recovering intermediate heat is arranged in the Brayton cycle, so that the compression ratio of the compressor 2 and the expansion ratio of the turbine 6 can be effectively reduced.
In the energy storage operating mode, the first port 3a of the first directional valve 3 is connected to the second port 3b of the first directional valve 3, the third port 3c of the first directional valve 3 is connected to the fourth port 3d of the first directional valve 3, the first port 8a of the second directional valve 8 is connected to the second port 8b of the second directional valve 8, and the third port 8c of the second directional valve 8 is connected to the fourth port 8d of the second directional valve 8.
In the energy storage working mode, electric energy is utilized to drive gaseous working medium to circulate, and the electric energy is converted into heat energy for storage. And in the energy storage stage, the gaseous working medium is subjected to Brayton cycle reverse circulation. The driving mechanism 1 is started, and the loop of the brayton cycle reverse circulation is as follows: the compressor 2-the first reversing valve 3-the first heat exchanger 4-the intermediate heat exchanger 5-the first reversing valve 3-the turbine 6-the second reversing valve 8-the second heat exchanger 9-the intermediate heat exchanger 5-the second reversing valve 8-the compressor 2, and the driving mechanism 1 (or the driving mechanism 1 moves under the driving of wind energy or tidal energy) is driven by electric power to drive the compressor 2, so that the compressor 2 works to convert electric energy into energy of high-temperature gaseous working medium; the high-temperature gaseous working medium passes through the first reversing valve 3, and firstly flows into the first heat exchanger 4 to heat the low-temperature working medium of the heat storage device to become a medium-temperature gaseous working medium, and then passes through the intermediate heat exchanger 5 to heat the low-temperature gaseous working medium at the inlet of the compressor 2, so that the compression ratio of the compressor 2 and the expansion ratio of the turbine 6 are effectively reduced, the efficiency of heat exchange equipment is ensured, and the design and manufacturing difficulty of the heat exchange equipment is reduced; meanwhile, outlet temperature deviation caused by the reduction of heat exchange efficiency of the heat storage and cold storage devices is reduced, and the operation stability of the system in the energy storage stage is maintained. The medium-temperature gaseous working medium flows out of the intermediate heat exchanger 5, flows to the turbine 6 after passing through the first reversing valve 3, is cooled to be low-temperature gaseous working medium after being expanded by the turbine 6, flows into the second heat exchanger 9 through the second reversing valve 8 at first, is used for cooling high-temperature antifreeze fluid of the cold storage device, flows into the intermediate heat exchanger 5 to be heated, flows to the compressor 2 after passing through the second reversing valve 8, and completes an energy storage cycle.
In the energy storage working mode, the gaseous working medium performs the cycle process of compression, heat release, expansion work and heat absorption, the work of the compressor 2 is larger than the work of the turbine 6, and the outside inputs electric energy to the system. The gaseous working medium absorbs heat from the working medium of the cold storage device and releases heat to the working medium of the heat storage device.
In the power generation operation mode, the first port 3a of the first directional valve 3 is connected to the fourth port 3d of the first directional valve 3, the second port 3b of the first directional valve 3 is connected to the third port 3c of the first directional valve 3, the first port 8a of the second directional valve 8 is connected to the fourth port 8d of the second directional valve 8, and the second port 8b of the second directional valve 8 is connected to the third port 8c of the second directional valve 8.
In the power generation working mode, the heat energy is utilized to drive the gaseous working medium to circulate, and the heat energy is converted into electric energy to be released. When the system discharges, the circuit of the brayton cycle reverse circulation is as follows: the method comprises the steps of starting a power cycle of heat-electricity conversion by a compressor 2, a first reversing valve 3, an intermediate heat exchanger 5, a first heat exchanger 4, a first reversing valve 3, a turbine 6, a second reversing valve 8, an intermediate heat exchanger 5, a second heat exchanger 9, a second reversing valve 8 and the compressor 2, wherein the process is an inverse process of the electricity-heat conversion, at the moment, the turbine 6 works more than the compressor 2, so as to drive a generator 7 to generate electricity, and the system outputs the power to the outside for supplying electricity. The low-temperature gaseous working medium is compressed into normal temperature by the compressor 2, enters the first reversing valve 3, flows through the intermediate heat exchanger 5 to become the medium-temperature gaseous working medium, flows through the first heat exchanger 4 to be heated, and flows into the turbine 6 to do expansion work after becoming the high-temperature gaseous working medium. The medium-temperature gaseous working medium after the turbine 6 performs work enters the second reversing valve 8, firstly flows through the intermediate heat exchanger 5, heats the low-temperature gaseous working medium at the outlet of the compressor 2, becomes the medium-temperature low-temperature gaseous working medium, then flows through the second heat exchanger 9 to be cooled, and the cooled low-temperature gaseous working medium flows through the second reversing valve 8 and enters the inlet of the compressor 2 to complete a power generation cycle. In the power generation stage, the intermediate heat exchanger 5 is used for expanding the intermediate gas state working medium after acting to heat the low-temperature gas state working medium at the outlet of the compressor 2, so that the compression ratio of the compressor 2 and the expansion ratio of the turbine 6 are effectively reduced, and the efficiency and the reliability of heat exchange equipment are ensured; meanwhile, the inlet temperature stability of the heat storage and cold storage device is ensured, and the operation stability of the system in the power generation stage is maintained.
In the power generation working mode, the gaseous working medium performs the cycle process of compression, heat absorption, expansion work and heat release, the gaseous working medium absorbs heat from the working medium of the heat storage device and releases heat to the working medium of the cold storage device, at the moment, the turbine 6 does work more than the compressor 2 does work, the generator 7 is driven to generate power, and the system outputs net power to the outside for supplying power.
That is, since the intermediate heat exchanger 5 is designed, the medium-temperature gaseous working medium of the heat storage outlet is used for heating the low-temperature gaseous working medium of the inlet of the compressor 2 in the energy storage stage; in the power generation stage, the high-temperature gaseous working medium at the outlet of the turbine 6 is commutated through a reversing valve, and the low-temperature gaseous working medium at the outlet of the compressor 2 is heated through the reversing valve. The design reduces the compression ratio of the compressor 2 and the expansion ratio of the turbine 6, ensures the efficiency of thermal equipment and reduces the manufacturing difficulty; the outlet temperature deviation caused by the reduction of the heat exchange efficiency of the heat storage and cold storage device is reduced in the energy storage stage; the inlet temperature of the heat storage and cold storage device is ensured to be stable in the power generation stage, so that the operation stability of the system in the energy storage and power generation stage is maintained.
The energy storage power generation circulation system adopts the main device of the gaseous working medium circulation formed by the compressor 2-heat exchanger-reversing valve-intermediate heat exchanger 5-turbine 6, the gaseous working medium in the system is in closed circulation in the energy storage and power generation stages, no emission and pollution are caused, a clean, low-carbon, efficient and energy-saving energy storage mode is realized, the reversing valve design is adopted, the reciprocal electric-thermal conversion circulation and the thermal-electric conversion circulation of the same set of device are realized, the system structure is simplified, the intermediate heat exchanger 5 is designed, the compression ratio of the compressor 2 and the expansion ratio of the turbine 6 can be helped to be reduced, the efficiency of thermal equipment is ensured, the manufacturing difficulty is reduced, and the running stability of the system in the energy storage and power generation stages is maintained.
As shown in fig. 1, the heat storage device includes a molten salt tank 10 with an inclined temperature layer, high-temperature molten salt is arranged above a molten salt inclined temperature layer 11 of the molten salt tank 10, and low-temperature molten salt is arranged below the molten salt inclined temperature layer 11 of the molten salt tank 10. The single-tank heat storage can be realized by utilizing the inclined temperature layer salt melting tank 10 for heat storage, the heat storage temperature of the molten salt tank 10 is high, electric energy can be converted into high-grade high-temperature heat source for storage, and the heat storage efficiency and the power generation efficiency are convenient to improve. At the moment of energy storage completion, the molten salt tank 10 is fully filled with high-temperature molten salt from top to bottom and the low-temperature molten salt at the bottom is completely emptied. At the time of system discharge completion, the molten salt tank 10 is fully emptied from the bottom up with low temperature molten salt and the upper high temperature molten salt.
The upper end of the molten salt tank 10 is provided with a molten salt upper distributor 14, the lower end of the molten salt tank 10 is provided with a molten salt lower distributor 12, the molten salt upper distributor 14 and the molten salt lower distributor 12 are respectively connected with two ends of a second path of the first heat exchanger 4, a molten salt pump 30a is arranged between the molten salt tank 10 and the second path of the first heat exchanger 4, and the molten salt pump 30a is arranged to enable molten salt to flow into the second path of the first heat exchanger 4 from the molten salt lower distributor 12 or flow into the second path of the first heat exchanger 4 from the molten salt upper distributor 14.
Since the molten salt pump 30a is provided to flow the molten salt from the lower molten salt distributor 12 into the second path of the first heat exchanger 4 or to flow the molten salt from the upper molten salt distributor 14 into the second path of the first heat exchanger 4, the molten salt tank 10 can realize heat storage and heat release.
Through the design of the upper molten salt distributor 14 and the lower molten salt distributor, the upper high-temperature molten salt and the lower low-temperature molten salt are effectively isolated by the molten salt inclined temperature layer 11, and heat storage at the high-temperature end of the system is completed after the molten salt tank 10 is filled with the high-temperature molten salt. The design of the lower molten salt distributor 12 and the upper molten salt distributor 14 reduces the mixing of the high/low temperature energy storage medium and the thickening of the inclined temperature layer during the operation of the inclined temperature layer; the heat storage is completed in a single molten salt tank 10, so that the energy storage density is improved, and the cost is reduced. By the design of the lower molten salt distributor 12 and the upper molten salt distributor 14, the temperature of the high-temperature end of the thermal-electric conversion system is kept constant, and the temperature stability and the working point stability of the high-temperature end of the whole system are ensured.
As shown in fig. 1, the cold storage device includes an antifreeze fluid tank 16 with an inclined temperature layer, wherein high-temperature antifreeze fluid is above an antifreeze fluid inclined temperature layer 17 of the antifreeze fluid tank 16, and low-temperature antifreeze fluid is below the antifreeze fluid inclined temperature layer 17 of the antifreeze fluid tank 16. The cold storage of the single-tank can be realized by utilizing the cold storage of the anti-freezing liquid tank 16 of the inclined temperature layer, and the cold storage temperature of the anti-freezing liquid tank 16 is very low. At the moment of energy storage completion, the antifreeze tank 16 is full of low-temperature antifreeze from bottom to top, and the upper high-temperature antifreeze is completely emptied. At the time of system discharge completion, the antifreeze fluid tank 16 is filled with high-temperature antifreeze fluid from top to bottom, and the lower low-temperature antifreeze fluid is completely emptied.
The upper end of the antifreeze tank 16 is provided with an antifreeze upper distributor 18, the lower end of the antifreeze tank 16 is provided with an antifreeze lower distributor 20, the antifreeze upper distributor 18 and the antifreeze lower distributor 20 are respectively connected with two ends of the second path of the second heat exchanger 9, an antifreeze pump 30b is arranged between the antifreeze tank 16 and the second path of the second heat exchanger 9, and the antifreeze pump 30b is arranged to enable antifreeze to flow from the antifreeze lower distributor 20 into the second path of the second heat exchanger 9 or enable antifreeze to flow from the antifreeze upper distributor 18 into the second path of the second heat exchanger 9.
Since the antifreeze pump 30b is provided to flow the antifreeze from the antifreeze lower distributor 20 into the second path of the second heat exchanger 9 or to flow the antifreeze from the antifreeze upper distributor 18 into the second path of the second heat exchanger 9, the antifreeze tank 16 can realize the cooling storage and the cooling release.
Through the design of the upper and lower distributors 18 and 17 of the antifreeze liquid, the antifreeze liquid inclined temperature layer 17 is ensured to effectively isolate the upper high-temperature antifreeze liquid and the lower low-temperature antifreeze liquid, and the cold storage at the low-temperature end of the system is completed after the antifreeze liquid tank 16 is full of the low-temperature antifreeze liquid. The design of the upper antifreeze distributor 18 and the lower antifreeze distributor 20 reduces the mixing of the high/low temperature energy storage medium and the thickening of the inclined temperature layer during the operation of the inclined temperature layer; the cold storage is completed in the single antifreeze fluid reservoir 16, which improves the energy storage density and reduces the cost. By the design of the upper antifreezing solution distributor 18 and the lower antifreezing solution distributor 20, the temperature of the low-temperature end of the thermal-electric conversion system is kept constant, and the temperature stability and the working condition point stability of the low-temperature end of the whole system are ensured.
That is, the energy storage device comprises a heat storage device and a cold storage device, wherein the heat storage device and the cold storage device are single heat insulation tanks with high heat insulation performance, and comprise a molten salt tank 10, an antifreezing solution tank 16, an auxiliary upper and lower distributor and a pump. Thermal energy is stored in the molten salt tank 10 in the form of high temperature molten salt thermal energy and in the antifreeze tank 16 in the form of low temperature antifreeze liquid thermal energy.
In the energy storage working mode, the gaseous working medium performs the cycle process of compression, heat release, expansion work and heat absorption, the work of the compressor 2 is larger than the work of the turbine 6, and the outside inputs electric energy to the system. The gaseous working medium absorbs heat from the antifreeze fluid and releases heat to the molten salt. The high-temperature gaseous working medium compressed by the compressor 2 is heated by the first heat exchanger 4 to be low-temperature molten salt to become high-temperature molten salt, and the high-temperature gaseous working medium becomes medium-temperature gaseous working medium; the medium-temperature gaseous working medium passes through the intermediate heat exchanger 5 to heat the low-temperature gaseous working medium at the inlet of the compressor 2, so that the compression ratio of the compressor 2 and the expansion ratio of the turbine 6 are effectively reduced, the efficiency of heat exchange equipment is ensured, and the design and manufacturing difficulty of the heat exchange equipment is reduced; the outlet temperature deviation caused by the reduction of the heat exchange efficiency of the heat storage and cold storage devices is reduced, and the operation stability of the system in the energy storage stage is maintained. The medium-temperature gaseous working medium is cooled to be low-temperature gaseous working medium after being expanded by the turbine 6, and the low-temperature gaseous working medium flows into the intermediate heat exchanger 5 after being cooled by the heat exchanger to be heated and flows into the compressor 2 to complete an energy storage cycle.
In the energy storage mode of operation, the energy storage device operates as follows:
The molten salt pump 30a drives low-temperature molten salt to flow out from the bottom of the molten salt tank 10 through the lower molten salt distributor 12, flows through the first heat exchanger 4, is heated to be high-temperature molten salt, flows into the upper space of the molten salt tank 10 through the upper molten salt distributor 14, and ensures that the upper high-temperature molten salt and the lower low-temperature molten salt are effectively isolated by the inclined molten salt temperature layer 11 through the upper molten salt distributor 14 and the lower molten salt distributor 12, and the heat storage of the high-temperature end of the system is completed after the molten salt tank 10 is fully filled with the high-temperature molten salt.
The antifreeze liquid pump 30b drives the antifreeze liquid to flow out of the upper space of the antifreeze liquid tank 16 from the upper distributor 18 of the antifreeze liquid, flows through the second heat exchanger 9, is cooled to be low-temperature antifreeze liquid, flows to the lower space of the antifreeze liquid tank 16 after passing through the lower distributor 20 of the antifreeze liquid, and by the design of the upper distributor 18 of the antifreeze liquid and the lower distributor 20 of the antifreeze liquid, the antifreeze liquid inclined temperature layer 17 is ensured to effectively isolate the upper high-temperature antifreeze liquid and the lower low-temperature antifreeze liquid, and the cold storage at the low-temperature end of the system is completed after the antifreeze liquid tank 16 is full of the low-temperature antifreeze liquid.
In the power generation working mode, the gaseous working medium performs the cycle process of compression, heat absorption, expansion work and heat release, the gaseous working medium absorbs heat from the high-temperature molten salt and releases heat to the antifreeze, at the moment, the turbine 6 works more than the compressor 2, the generator 7 is driven to generate power, and the system outputs net power to the outside. The low-temperature gaseous working medium enters the first reversing valve 3 after being compressed by the compressor 2, flows through the intermediate heat exchanger 5 to become the medium-temperature gaseous working medium, flows through the first heat exchanger 4 to be heated, and flows into the turbine 6 to do expansion work after becoming the high-temperature gaseous working medium. The medium-temperature gaseous working medium after the turbine 6 performs work enters the second reversing valve 8, flows through the intermediate heat exchanger 5 at first, heats the low-temperature gaseous working medium at the outlet of the compressor 2, becomes the medium-temperature low-temperature gaseous working medium, flows through the second heat exchanger 9 and is cooled, and a power generation cycle is completed. In the power generation stage, the intermediate heat exchanger 5 is used for expanding the intermediate gas state working medium after acting to heat the low-temperature gas state working medium at the outlet of the compressor 2, so that the compression ratio of the compressor 2 and the expansion ratio of the turbine 6 are effectively reduced, and the efficiency and the reliability of heat exchange equipment are ensured; meanwhile, the inlet temperature stability of the heat storage and cold storage device is ensured, and the operation stability of the system in the power generation stage is maintained.
In the power generation mode of operation, the energy storage device operates as follows:
The second molten salt pump 15 drives the high-temperature molten salt to flow out from the upper part of the molten salt tank 10 through the upper molten salt distributor 14, flows through the first heat exchanger 4, becomes low-temperature molten salt after the high-temperature molten salt heats gaseous working medium, flows into the lower space of the molten salt tank 10 through the lower molten salt distributor 12, ensures that the upper high-temperature molten salt and the lower low-temperature molten salt are effectively isolated by the molten salt inclined temperature layer 11 through the upper molten salt distributor 14 and the lower molten salt, and completes the system power generation process after the molten salt tank 10 is fully filled with the low-temperature molten salt.
The antifreeze liquid pump 30b drives the antifreeze liquid to flow out of the lower space antifreeze liquid lower distributor 20 of the antifreeze liquid tank 16, flows through the second heat exchanger 9, and the low-temperature antifreeze liquid cools the gaseous working medium, flows to the upper space of the antifreeze liquid tank 16 after passing through the upper distributor 18 of the antifreeze liquid, and through the design of the upper distributor 18 and the lower distributor of the antifreeze liquid, the antifreeze liquid inclined temperature layer 17 is ensured to effectively isolate the upper high-temperature antifreeze liquid and the lower low-temperature antifreeze liquid, and the system power generation process is completed after the antifreeze liquid tank 16 is full of the high-temperature antifreeze liquid.
In order to achieve the second path of the molten salt pump 30a being arranged to flow molten salt from the lower molten salt distributor 12 into the first heat exchanger 4 or the second path of the molten salt from the upper molten salt distributor 14 into the first heat exchanger 4, the antifreeze liquid pump 30b is arranged to flow antifreeze liquid from the lower antifreeze distributor 20 into the second path of the second heat exchanger 9 or the second path of the antifreeze liquid from the upper antifreeze distributor 18 into the second heat exchanger 9, an embodiment is given in fig. 1.
As shown in fig. 1, the molten salt pump 30a includes: a first molten salt pump 13 and a second molten salt pump 15.
A first molten salt pump 13 and a first molten salt main valve 22 are arranged between the lower molten salt distributor 12 and the second path of the first heat exchanger 4, and a first molten salt bypass valve 23 is connected in parallel outside the first molten salt pump 13 and the first molten salt main valve 22; a second molten salt pump 15 and a second molten salt main valve 24 are arranged between the molten salt upper distributor 14 and the second path of the first heat exchanger 4, and a second molten salt bypass valve 25 is connected in parallel outside the second molten salt pump 15 and the second molten salt main valve 24.
In the energy storage working mode, the first molten salt pump 13 and the first molten salt main valve 22 are opened, the first molten salt bypass valve 23 is closed, the second molten salt pump 15 and the second molten salt main valve 24 are closed, the second molten salt bypass valve 25 is opened, and the first molten salt pump 13 extracts low-temperature molten salt from the lower part of the molten salt tank 10 through the molten salt lower distributor 12 to enter the first heat exchanger 4.
In the power generation operation mode, the first molten salt pump 13 and the first molten salt main valve 22 are closed, the first molten salt bypass valve 23 is opened, the second molten salt pump 15 and the second molten salt main valve 24 are opened, the second molten salt bypass valve 25 is closed, and the second molten salt pump 15 extracts high-temperature molten salt from the upper part of the molten salt tank 10 through the molten salt upper distributor 14 to enter the first heat exchanger 4.
The first molten salt pump 13, the second molten salt pump 15 and the related valve structures can not only realize the second way of flowing low-temperature molten salt or high-temperature molten salt into the first heat exchanger 4, but also form better protection effect on the first molten salt pump 13 and the second molten salt pump 15.
As shown in fig. 1, the antifreeze liquid pump 30b includes: a first antifreeze pump 21 and a second antifreeze pump 19.
A first antifreeze liquid pump 21 and a first antifreeze liquid main valve 26 are arranged between the antifreeze liquid lower distributor 20 and the second path of the second heat exchanger 9, and a first antifreeze liquid bypass valve 27 is connected in parallel outside the first antifreeze liquid pump 21 and the first antifreeze liquid main valve 26; a second antifreeze liquid pump 19 and a second antifreeze liquid main valve 28 are arranged between the antifreeze liquid upper distributor 18 and the second path of the second heat exchanger 9, and a second antifreeze liquid bypass valve 29 is connected in parallel outside the second antifreeze liquid pump 19 and the second antifreeze liquid main valve 28.
In the energy storage operation mode, the first antifreeze pump 21 and the first antifreeze main valve 26 are closed, the first antifreeze bypass valve 27 is opened, the second antifreeze pump 19 and the second antifreeze main valve 28 are opened, the second antifreeze bypass valve 29 is closed, and the second antifreeze pump 19 draws high-temperature antifreeze from the upper portion of the antifreeze tank 16 through the antifreeze upper distributor 18 into the second heat exchanger 9.
In the power generation operation mode, the first antifreeze pump 21 and the first antifreeze main valve 26 are opened, the first antifreeze bypass valve 27 is closed, the second antifreeze pump 19 and the second antifreeze main valve 28 are closed, the second antifreeze bypass valve 29 is opened, and the first antifreeze pump 21 draws low-temperature antifreeze from the lower portion of the antifreeze tank 16 through the antifreeze lower distributor 20 into the second heat exchanger 9.
Of course, the solution pump and the antifreeze pump 30b can also be designed in other ways.
As shown in fig. 2, the inlet end of the molten salt pump 30a or the antifreeze pump 30b is connected with a first inlet valve 31 and a second inlet valve 32, the outlet end of the molten salt pump 30a or the antifreeze pump 30b is connected with a first outlet valve 33 and a second outlet valve 34, one end of the first outlet valve 33 facing away from the outlet end of the antifreeze pump 30b is connected with one end of the second inlet valve 32 facing away from the inlet end of the antifreeze pump 30b, one end of the second outlet valve 34 facing away from the outlet end of the antifreeze pump 30b is connected with one end of the first inlet valve 31 facing away from the inlet end of the antifreeze pump 30b, and the outlet end of the molten salt pump 30a or the antifreeze pump 30b may be further provided with a check valve.
For the molten salt tank 10, a first inlet valve 31 and a second inlet valve 32 are connected between the molten salt upper distributor 14 and the second path of the first heat exchanger 4, or the first inlet valve 31 and the second inlet valve 32 are connected between the molten salt lower distributor 12 and the second path of the first heat exchanger 4.
For the antifreeze tank 16, the first inlet valve 31 and the second inlet valve 32 are connected between the antifreeze upper distributor 18 and the second path of the first heat exchanger 4, or the first inlet valve 31 and the second inlet valve 32 are connected between the antifreeze lower distributor 20 and the second path of the first heat exchanger 4.
Through the design of above-mentioned structure, can adjust the flow direction of fused salt and antifreeze through the state of adjusting each valve, can realize the effect of double pump promptly through single pump.
For example, opening the first inlet valve 31 and the first outlet valve 33, closing the second inlet valve 32 and the second outlet valve 34 may enable the energy storage medium to flow from the right-hand port to the left-hand port in fig. 2; closing the first inlet valve 31 and the first outlet valve 33 and opening the second inlet valve 32 and the second outlet valve 34 allows the energy storage medium to flow from the left end interface to the right end interface in fig. 2.
Taking the embodiment shown in fig. 1 as an example, the energy storage power generation circulation system has an energy storage operation mode and a power generation operation mode. In an energy storage working mode, the energy storage power generation circulation system can realize electric-heat conversion; in the power generation operation mode, the energy storage power generation circulation system can realize heat-electricity conversion.
The energy storage device (a heat storage device and a cold storage device) in the energy storage power generation circulation system is an adiabatic tank with high heat preservation performance, the tank body is made of stainless steel or other high temperature resistant steel and low temperature resistant steel, and the outside of the tank body is covered with a heat preservation layer, and the heat preservation layer comprises a molten salt tank 10 and an antifreezing solution tank 16. Thermal energy is stored in the molten salt tank 10 in the form of high temperature molten salt thermal energy and in the antifreeze fluid tank 16 in the form of low temperature antifreeze fluid thermal energy. At the moment of energy storage completion, the molten salt tank 10 is fully filled with high-temperature molten salt from top to bottom, and the low-temperature molten salt at the bottom is completely emptied; the antifreeze tank 16 is filled with low-temperature antifreeze solution from bottom to top, and the upper high-temperature antifreeze solution is completely emptied. An antifreezing solution with the freezing point lower than 0 ℃ is adopted as a cold storage medium at a low temperature end, the working temperature range of the antifreezing solution can be-100 ℃ to 10 ℃, and the antifreezing solution can be methanol aqueous solution, ethanol aqueous solution, glycol aqueous solution, glycerol aqueous solution and saline solution (calcium chloride, magnesium chloride, sodium nitrate and sodium nitrite); the low-melting-point salt (nitrate and chloride) is adopted as a high-temperature-end heat storage medium, so that the risk of molten salt solidification is reduced, and the requirement of the system on molten salt solidification prevention is met. The working temperature of the antifreeze is reduced, so that the energy conversion efficiency of the system is ensured, the temperature of the high-temperature end of the system is reduced, and the requirement of the system for expensive high-temperature resistant materials is reduced.
In the energy storage working mode, the energy storage power generation circulating system utilizes electric energy to drive gaseous working medium to circulate, and converts the electric energy into heat energy for storage. And in the energy storage stage, the gaseous working medium is subjected to Brayton cycle reverse circulation. The gaseous working medium can be air, nitrogen, argon, helium, hydrogen or carbon dioxide.
Starting a loop of the compressor 2, the first reversing valve 3, the first heat exchanger 4, the intermediate heat exchanger 5, the first reversing valve 3, the turbine 6, the second reversing valve 8, the second heat exchanger 9, the intermediate heat exchanger 5, the second reversing valve 8 and the compressor 2, driving the compressor 2 by an electric driving motor (driving mechanism 1), and converting electric energy into energy of high-temperature gaseous working medium by the work of the compressor 2; the high-temperature gaseous working medium passes through the first reversing valve 3, and heats low-temperature molten salt when flowing into the first heat exchanger 4 to become a medium-temperature gaseous working medium, and then the medium-temperature gaseous working medium passes through the intermediate heat exchanger 5 to heat the low-temperature gaseous working medium at the inlet of the compressor 2, so that the compression ratio of the compressor 2 and the expansion ratio of the turbine 6 can be effectively reduced, the efficiency of thermodynamic equipment is ensured, and the design and manufacturing difficulty of the thermodynamic equipment is reduced; the outlet temperature deviation caused by the reduction of the heat exchange efficiency of the heat storage and cold storage devices is reduced, and the operation stability of the system in the energy storage stage is maintained.
The medium-temperature gaseous working medium flows out of the intermediate heat exchanger 5, flows to the turbine 6 after passing through the first reversing valve 3, is cooled to be low-temperature gaseous working medium after being expanded by the turbine 6, flows into the second heat exchanger 9 through the second reversing valve 8 at first for cooling the antifreeze fluid, flows into the intermediate heat exchanger 5 to be heated, flows to the compressor 2 after passing through the second reversing valve 8, and completes an energy storage cycle.
In the energy storage circulation stage, the energy storage device operates as follows:
The first molten salt pump 13 drives low-temperature molten salt to flow out from the bottom of the molten salt tank 10 through the lower molten salt distributor 12, flows through the first heat exchanger 4, is heated to be high-temperature molten salt, flows into the upper space of the molten salt tank 10 through the upper molten salt distributor 14, and ensures that the upper high-temperature molten salt and the lower low-temperature molten salt are effectively isolated by the inclined molten salt temperature layer 11 through the upper molten salt distributor 14 and the lower molten salt distributor 12, and the heat storage of the high-temperature end of the system is completed after the molten salt tank 10 is fully filled with the high-temperature molten salt.
The second antifreeze pump 19 drives the antifreeze to flow out from the upper space of the antifreeze tank 16, the antifreeze flows out from the upper distributor 18 of the antifreeze, flows through the second heat exchanger 9, the high-temperature antifreeze is cooled into low-temperature antifreeze, flows to the lower space of the antifreeze tank 16 after flowing through the lower distributor 20 of the antifreeze, and by the design of the upper distributor 18 of the antifreeze and the lower distributor 12 of molten salt, the antifreeze inclined temperature layer 17 is ensured to effectively isolate the upper high-temperature antifreeze and the lower low-temperature antifreeze, and the cold storage at the low-temperature end of the system is completed after the antifreeze tank 16 is full of the low-temperature antifreeze.
In the power generation working mode, when the system discharges, a loop of the compressor 2-the first reversing valve 3-the intermediate heat exchanger 5-the first heat exchanger 4-the first reversing valve 3-the turbine 6-the second reversing valve 8-the intermediate heat exchanger 5-the second heat exchanger 9-the second reversing valve 8-the compressor 2 is started, the power cycle of the heat-electricity conversion is started, the process is the reverse process of the electricity-heat conversion, at the moment, the turbine 6 does work larger than the compressor 2 does work, the generator 7 is driven to generate power, and the system outputs power to the outside for supplying power. The low-temperature gaseous working medium is compressed by the compressor 2, enters the first reversing valve 3, flows through the intermediate heat exchanger 5 to become the medium-temperature gaseous working medium, flows through the first heat exchanger 4 to be heated, and flows into the turbine 6 to do expansion work after becoming the high-temperature gaseous working medium. The medium-temperature gaseous working medium after the turbine 6 performs work enters the second reversing valve 8, flows through the intermediate heat exchanger 5 at first, heats the low-temperature gaseous working medium at the outlet of the compressor 2, becomes the medium-temperature low-temperature gaseous working medium, flows through the second heat exchanger 9 and is cooled, and a power generation cycle is completed. In the power generation stage, the intermediate heat exchanger 5 is used for expanding the intermediate gas state working medium after acting to heat the low-temperature gas state working medium at the outlet of the compressor 2, so that the compression ratio of the compressor 2 and the expansion ratio of the turbine 6 are effectively reduced, and the efficiency and the reliability of the thermodynamic equipment are ensured; meanwhile, the inlet temperature stability of the heat storage and cold storage device is ensured, and the operation stability of the system in the power generation stage is maintained.
In the power generation cycle stage, the energy storage device operates as follows:
The second molten salt pump 15 drives the high-temperature molten salt to flow out from the upper part of the molten salt tank 10 through the upper molten salt distributor 14, flows through the first heat exchanger 4, becomes low-temperature molten salt after the high-temperature molten salt heats gaseous working medium, flows into the lower space of the molten salt tank 10 through the lower molten salt distributor 12, ensures that the upper high-temperature molten salt and the lower low-temperature molten salt are effectively isolated by the molten salt inclined temperature layer 11 through the upper molten salt distributor 14 and the lower molten salt, and completes the system power generation process after the molten salt tank 10 is fully filled with the low-temperature molten salt.
The antifreeze liquid pump 30b drives the antifreeze liquid to flow out of the lower space antifreeze liquid lower distributor 20 of the antifreeze liquid tank 16, flows through the second heat exchanger 9, and the low-temperature antifreeze liquid cools the gaseous working medium, flows to the upper space of the antifreeze liquid tank 16 after passing through the upper distributor 18 of the antifreeze liquid, and through the design of the upper distributor 18 and the lower distributor of the antifreeze liquid, the antifreeze liquid inclined temperature layer 17 is ensured to effectively isolate the upper high-temperature antifreeze liquid and the lower low-temperature antifreeze liquid, and the system power generation process is completed after the antifreeze liquid tank 16 is full of the high-temperature antifreeze liquid.
At the time of system discharge completion, the molten salt tank 10 is fully filled with low-temperature molten salt from bottom to top, and the high-temperature molten salt at the upper part is completely emptied; the antifreeze tank 16 is filled with high-temperature antifreeze from top to bottom and the lower part of the antifreeze tank is completely emptied. And starting the next energy storage power generation cycle.
It should be noted that, in the energy storage and power generation circulation system, the medium-temperature gaseous working medium at the heat storage outlet is used for heating the low-temperature gaseous working medium at the inlet of the compressor 2 in the energy storage stage through the intermediate heat exchanger 5; in the power generation stage, the high-temperature gaseous working medium at the outlet of the turbine 6 is commutated through a reversing valve, and the low-temperature gaseous working medium at the outlet of the compressor 2 is heated through the reversing valve. The design reduces the compression ratio of the compressor 2 and the expansion ratio of the turbine 6, ensures the efficiency of thermal equipment and reduces the manufacturing difficulty; the outlet temperature deviation caused by the reduction of the heat exchange efficiency of the heat storage and cold storage device is reduced in the energy storage stage; the inlet temperature of the heat storage and cold storage device is ensured to be stable in the power generation stage, so that the operation stability of the system in the energy storage and power generation stage is maintained.
The melting point molten salt of the energy storage power generation circulation system is used as a heat storage medium at a high temperature end, and the antifreeze solution with a low freezing point is used as a cold storage medium at a low temperature end. The low-melting-point molten salt reduces the risk of solidification of the molten salt and the requirement of the system on the solidification prevention of the molten salt. The low-temperature end of the system adopts low-freezing point antifreeze, so that the temperature (-100 ℃ -10 ℃) of the low-temperature end of the energy storage power generation system is reduced, the power storage efficiency is ensured, the temperature of the high-temperature end of the system is reduced, the requirements of the system for high-temperature resistant equipment and materials are reduced, and the cost of the system is reduced.
The energy storage power generation circulation system provides a power storage mode which is generally applicable to instability, peak shifting and valley filling of renewable energy power generation such as thermal power peak shaving, stabilizing wind power or photovoltaic power generation and the like and can relieve the problems of wind discarding and light discarding.
In summary, the energy storage power generation circulation system provided by the application aims at the limitation of the existing molten salt energy storage technology, and provides an energy storage power generation circulation system with middle heat recovery capability, wherein the single-tank molten salt is utilized to store heat, the single-tank antifreeze fluid is utilized to store cold, the middle heat exchanger 5 is utilized to stabilize the temperature of the high-temperature end and the low-temperature end of the system, the energy conversion efficiency is higher, the energy storage power generation circulation system is safe and economical, and clean and low-carbon; the temperature difference between the high temperature end and the low temperature end of the thermal power cycle is effectively maintained by utilizing a single-tank inclined temperature layer technology, so that the energy storage density is improved; the same set of heat exchange device and the circulation in opposite directions are adopted to realize efficient heat exchange in the energy storage circulation and the power generation circulation; the direction of flow is changed by the reversing valve, and the intermediate heat exchanger 5 stabilizes the temperature of the high temperature end and the low temperature end of the system, properly reduces the compression ratio, maintains the stable operation of the system and improves the efficiency of the system. Through the positive-negative circulation of the same set of thermodynamic device, single-tank heat storage/cooling device and heat exchange device, the system structure is simplified, the energy storage density is improved, the energy conversion efficiency is ensured, and meanwhile, the thermodynamic equipment cost and the energy storage device cost are reduced. Through the energy storage power generation circulation system with the middle heat recovery capability, the instability of renewable energy power generation such as wind power generation or photovoltaic power generation is stabilized, the stable output of renewable energy power is realized, the problem of abandoned wind and abandoned light is relieved, the peak regulation, the off-peak power utilization and the like of a thermal power plant are realized.
In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means 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 application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the application, the scope of which is defined by the claims and their equivalents.