Multi-stage energy storage type multi-energy combined supply Carnot battery energy storage system and method thereof

Abstract

The invention belongs to the technical field of energy storage, and particularly relates to a multi-stage energy storage type multi-energy combined supply Carnot battery energy storage system and a method thereof.The system comprises a first passage, and the first passage is sequentially connected with a second evaporator, a second compressor, a third compressor, a second condenser, a third throttling valve and a second throttling valve; and finally, connecting to a second evaporator to form a main loop, and absorbing heat of the waste heat source through the second evaporator. A first branch and a second branch are connected in parallel to the main loop of the first path; the multi-stage energy storage working unit comprises a second passage, a third passage and a fourth passage, the second passage is used for storing cold energy and absorbing cold energy from the first branch through the first evaporator, the third passage is used for storing medium-temperature heat and absorbing heat energy from the second branch through the first condenser, and the fourth passage is used for storing high-temperature heat and absorbing heat energy through the second condenser. The problem that energy storage and release of multi-stage heat are difficult to achieve based on low-grade waste heat in the prior art is solved.

Description

Technical Field

[0001] This invention belongs to the field of energy storage technology, specifically relating to a multi-level energy storage type Carnot battery energy storage system and its method. Background Technology

[0002] Currently, methods for utilizing low-grade waste heat in industry are still immature, while industrial scenarios present diverse energy demands. Traditional Carnot batteries, which integrate multi-temperature zone heat storage (i.e., the storage and generation of multiple types of heat), rely on high-grade, high-temperature waste heat. However, it is difficult to achieve the energy storage and release of multiple types of low-grade waste heat, making it impossible to supply multiple energy sources simultaneously. Furthermore, existing technologies for combined energy supply (CESP) suffer from issues such as a large number of devices, low integration, and high initial investment costs. Summary of the Invention

[0003] The purpose of this invention is to provide a multi-stage energy storage system and method for Carnot batteries, in order to solve the technical problem in the prior art that it is difficult to achieve multi-stage heat energy storage and release based on low-grade waste heat.

[0004] The aforementioned multi-stage energy storage type Carnot battery energy storage system includes a multi-stage charging working unit and a multi-stage energy storage working unit. The multi-stage charging working unit includes a first passage, which is sequentially connected to a second evaporator, a second compressor, a third compressor, a second condenser, a third throttle valve, and a second throttle valve, and finally connected to the second evaporator to form a main circuit. The charging working medium flows through the first passage and absorbs heat from the waste heat source through the second evaporator. The main circuit of the first passage is also connected in parallel to a first branch and a second branch. The inlet end of the first branch is connected between the second throttle valve and the second evaporator, and the outlet end of the first branch is connected between the second evaporator and the second compressor. The inlet end of the second branch is connected between the second compressor and the third compressor, and the outlet end of the second branch is connected between the third throttle valve and the second throttle valve. The multi-stage energy storage working unit includes a second passage, a third passage, and a fourth passage. The second passage is used for cold storage and absorbs cold energy from the first branch through the first evaporator. The third passage is used for medium-temperature heat storage and absorbs heat energy from the second branch through the first condenser. The fourth passage is used for high-temperature heat storage and absorbs heat energy through the second condenser.

[0005] Preferably, in the first branch, starting from the inlet end of the first branch, it passes sequentially through the first throttle valve, the first evaporator and the first compressor, and finally connects to the main circuit through the outlet end of the first branch.

[0006] Preferably, the second passage circulates the cold storage medium and is connected sequentially from the first evaporator to a low-temperature cold storage tank, a low-temperature cold storage water pump, a cold user applying cold energy, a high-temperature cold storage tank, and a high-temperature cold storage pump, and then connected to the first evaporator to form a loop.

[0007] Preferably, the third passage circulates a medium-temperature thermal storage medium and is sequentially connected to a high-grade medium-temperature thermal storage tank, a high-grade medium-temperature hot water pump, a medium-temperature heat user using medium-temperature thermal energy, a low-grade medium-temperature thermal storage tank, and a low-grade medium-temperature hot water pump, starting from the first condenser, before being connected to the first condenser to form a loop.

[0008] Preferably, the system further includes a high-temperature energy release application unit, in which a high-temperature heat storage medium circulates, and is sequentially connected from the second condenser to an advanced high-temperature heat storage tank, an advanced high-temperature heat storage water pump, a third evaporator, a low-temperature heat storage tank, and a low-temperature heat storage water pump, and then connected to the second condenser to form a loop; the high-temperature energy release application unit absorbs the high-temperature heat energy stored in the fourth passage through the third evaporator.

[0009] Preferably, the high-temperature energy release application unit is a power generation working unit, including a fifth passage, in which the power generation and energy release working medium flows, and starting from the third evaporator, it is sequentially connected to an expansion generator set, a regenerator and a preheater, and then connected to the third evaporator to form a loop. The preheater absorbs heat from the waste heat source to preheat the power generation and energy release working medium.

[0010] Preferably, the power generation unit also includes a sixth passage, which connects the third condenser and the working medium pump in sequence from the regenerator, and then connects to the regenerator to form a loop.

[0011] This invention also provides a multi-level energy storage method for Carnot battery combined heat and power, which applies a multi-level energy storage system for Carnot battery combined heat and power as described above, and includes a charging stage and an energy release stage. The charging stage includes: Cold energy charging: The charging working medium is depressurized and cooled by the second throttle valve and enters the fourth three-way valve for diversion: one path enters the second evaporator; the other path is depressurized by the first throttle valve and then enters the first evaporator to release cold energy into the second path; in the second path, the cold storage medium in the high temperature cold storage tank is pressurized by the high temperature cold storage pump, absorbs cold energy from the first evaporator and then enters the low temperature cold storage tank for storage. Medium-temperature thermal energy charging: The charging working medium enters the second compressor for pressurization and heating, and then enters the second three-way valve for diversion: one path enters the second branch, and the other path enters the third compressor; the charging working medium in the second branch enters the second condenser to release medium-temperature thermal energy into the third passage; in the third passage, the medium-temperature thermal energy storage medium in the low-level medium-temperature thermal energy storage tank is pressurized by the low-level medium-temperature thermal energy storage pump, absorbs medium-temperature thermal energy from the second condenser, and then enters the high-level medium-temperature thermal energy storage tank for storage; High-temperature thermal energy charging: The charging working medium is pressurized and heated by the third compressor, and then enters the third condenser to release high-temperature thermal energy to the fourth passage; in the fourth passage, the high-temperature thermal energy storage medium of the low-level high-temperature thermal energy storage tank is pressurized by the low-level high-temperature thermal energy storage pump, absorbs high-temperature thermal energy from the third condenser, and then enters the high-level high-temperature thermal energy storage tank for storage. The energy release phase includes: Cold energy release: The cold storage medium in the second channel starts from the low-temperature cold storage tank, is pressurized by the low-temperature cold storage pump and supplied to cold users for cold energy utilization. The cold storage medium that has been utilized and heated is returned to the high-temperature cold storage tank for storage. Medium-temperature thermal energy release: The medium-temperature thermal storage medium in the third channel starts from the advanced medium-temperature thermal storage tank, is pressurized by the advanced medium-temperature thermal storage pump and supplied to medium-temperature thermal users for the use of medium-temperature thermal energy. The medium-temperature thermal storage medium that has been used and cooled down is returned to the low-level medium-temperature thermal storage tank for storage. High-temperature thermal energy release: The high-temperature thermal storage medium in the fourth channel starts from the advanced high-temperature thermal storage tank, is pressurized by the advanced high-temperature thermal storage pump and then transported to the third condenser to provide high-temperature thermal energy to the power generation unit. The high-temperature thermal storage medium that has been utilized and cooled down is returned to the low-temperature thermal storage tank for storage.

[0012] Preferably, in the power generation unit, the power generation and energy release working medium in the fifth channel absorbs the energy stored at high temperature in the third evaporator, reaching a high temperature and high pressure state, and then enters the expansion generator set to do work. The expansion generator set converts mechanical energy into electrical energy output. After the power generation and energy release working medium has its temperature and pressure reduced after being worked by the expansion generator set, it enters the regenerator to provide heat to the other side of the regenerator and further cools down. Afterwards, it absorbs the low-grade waste heat energy from the waste heat source in the preheater and then enters the third evaporator to complete the work process of the energy release stage.

[0013] Preferably, when the cooling demand increases / decreases: the speed of the first compressor is increased / decreased to increase / decrease the flow rate of the energizing working medium in the first branch, and the opening of the first throttle valve is increased / decreased to increase / decrease the flow rate of the energizing working medium in the first branch; according to the actual situation, the speed of the remaining compressors and the valve openings are adjusted to make the system reach a balanced state; When the heating demand increases / decreases: increase / decrease the speed of the second compressor to increase / decrease the flow rate of the charging working medium in the second branch, and simultaneously increase / decrease the opening of the second throttle valve to increase / decrease the flow rate of the charging working medium in the second branch; adjust the speed of the remaining compressors and the valve openings according to the actual situation to bring the system into a balanced state; When the high-temperature heat demand increases / decreases: increase / decrease the speed of the third compressor to increase / decrease the flow rate of the charging working medium flowing through the third evaporator, and at the same time increase / decrease the opening of the third throttle valve to increase / decrease the flow rate of the charging working medium flowing through the third evaporator; adjust the speed of the remaining compressors and the valve openings according to the actual situation to make the system reach a balanced state.

[0014] The technical advantages of this invention are as follows: This invention couples the cold energy, medium-temperature thermal energy, and high-temperature thermal energy storage pathways in a multi-stage energy storage unit into the same system through a first pathway and its branches. It utilizes the heat source of a Carnot battery and achieves charging through a second and third compressor on the first pathway, thereby increasing the thermal energy of the charging working medium in the pathway. This allows for the application of low-grade industrial waste heat to multi-stage energy storage, improving the efficiency of the multi-stage energy storage-type Carnot battery. This invention satisfies the requirement of simultaneously using multiple energy conversion devices to achieve multi-energy supply, improving system integration, reducing the number of devices, lowering the initial system cost, and solving the problem of existing technologies' difficulty in achieving multi-stage heat energy storage and release based on low-grade waste heat. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a multi-level energy storage type Carnot battery energy storage system according to the present invention. Detailed Implementation

[0016] The following detailed description of the embodiments, with reference to the accompanying drawings, will further illustrate the specific implementation of the present invention, in order to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solution of the present invention.

[0017] like Figure 1As shown, this invention provides a multi-stage energy storage type Carnot battery energy storage system, including a multi-stage charging working unit and a multi-stage energy storage working unit. The multi-stage charging working unit includes a first passage, which is sequentially connected to a second evaporator, a second compressor, a third compressor, a second condenser, a third throttle valve, and a second throttle valve, and finally connected to the second evaporator to form a main circuit. The charging working medium flows through the first passage and absorbs heat from the waste heat source through the second evaporator. A first branch and a second branch are also connected in parallel on the main circuit of the first passage. The inlet end of the first branch is connected to... The system connects the second throttle valve to the second evaporator, the outlet of the first branch connects to the second evaporator and the second compressor, the inlet of the second branch connects to the second compressor and the third compressor, and the outlet of the second branch connects to the third throttle valve and the second throttle valve. The multi-stage energy storage unit includes a second, third, and fourth passage. The second passage is used for cold storage and absorbs cold energy from the first branch through the first evaporator. The third passage is used for medium-temperature heat storage and absorbs heat energy from the second branch through the first condenser. The fourth passage is used for high-temperature heat storage and absorbs heat energy from the second condenser. The system couples the multi-stage energy storage unit through the first passage and achieves multi-stage energy storage using the Carnot battery heat source. The second and third compressors enhance the working fluid's thermal energy, converting low-grade industrial waste heat into multi-stage thermal energy storage. This system achieves coordinated charging and discharging of cold, medium, and high-temperature multi-stage thermal energy, supports multi-energy supply, has high integration, simplified equipment, and reduced costs, solving the problem of inefficient storage and release of low-grade waste heat.

[0018] The second passage circulates the cold storage medium and is sequentially connected to the low-temperature cold storage tank, the low-temperature cold storage water pump, the user applying cold energy, the high-temperature cold storage tank, and the high-temperature cold storage pump, starting from the first evaporator, before connecting back to the first evaporator to form a loop. The inlet and outlet of the first branch are connected to the main loop of the first passage via the fourth three-way valve and the first three-way valve, respectively.

[0019] In the first branch, the energizing working medium in the first passage passes through the second branch and the second condenser, where its heat energy is absorbed by the third and fourth passages, causing its temperature to drop. It then passes through the third, second, and first throttling valves for further pressure and temperature reduction, forming a low-temperature energizing working medium with cold energy. In the second passage, the cold storage medium absorbs cold energy from the first branch through the first evaporator, stores it in a low-temperature cold storage tank, and then supplies it to users via a low-temperature cold storage pump. After utilizing the cold energy, the temperature of the cold storage medium rises, and it is then stored in a high-temperature cold storage tank. It is then pumped back to the first evaporator by the high-temperature cold storage pump to absorb cold energy from the first branch again, forming a cycle of cold energy absorption-storage-release-reabsorption.

[0020] Since the temperature of the charging working medium after absorbing cold energy in the first branch is still not as high as the temperature of the charging working medium after absorbing heat energy from the low-grade heat source, in order to reduce the temperature drop of the charging working medium in the main circuit, the first branch, starting from its inlet, sequentially passes through the first throttle valve, the first evaporator, and the first compressor, and finally connects to the main circuit through its outlet. In this way, the first throttle valve can further reduce the temperature and pressure of the charging working medium, increasing the cold energy. After releasing the cold energy, the first compressor can then raise the temperature and pressure, making the temperature of the charging working medium entering the main circuit close to the temperature of the charging working medium after absorbing heat energy from the low-grade heat source, thus improving the system's stability and operating efficiency.

[0021] The third circuit circulates a medium-temperature thermal storage medium and, starting from the first condenser, sequentially connects to a high-grade medium-temperature thermal storage tank, a high-grade medium-temperature hot water pump, a medium-temperature heat user utilizing medium-temperature thermal energy, a low-grade medium-temperature thermal storage tank, and a low-grade medium-temperature hot water pump, before connecting back to the first condenser to form a loop. The inlet and outlet of the second branch are connected to the main circuit of the first circuit via a second three-way valve and a third three-way valve, respectively.

[0022] In the second branch, the charging working medium in the first passage is heated and pressurized by the second compressor to meet the requirements for medium-temperature energy storage and then enters the first condenser. In the third passage, after absorbing medium-temperature thermal energy from the second branch through the first condenser, it is stored in an advanced medium-temperature thermal energy storage tank. Then, it is supplied to medium-temperature users via an advanced medium-temperature hot water pump. The temperature of the utilized medium-temperature thermal energy storage medium decreases, and it is then stored again in a low-grade medium-temperature thermal energy storage tank. It is then pumped back to the first condenser by the low-grade medium-temperature hot water pump to absorb medium-temperature thermal energy from the second branch again, forming a cycle of absorption-storage-release-reabsorption of medium-temperature thermal energy.

[0023] The fourth passage circulates a high-temperature thermal storage medium and, starting from the second condenser, sequentially connects to an advanced high-temperature thermal storage tank, an advanced high-temperature hot water pump, a third evaporator, a low-temperature thermal storage tank, and a low-temperature hot water pump, before connecting back to the second condenser to form a loop. The multi-stage energy storage type Carnot battery energy storage system also includes a high-temperature energy release application unit, which absorbs and utilizes the high-temperature thermal energy stored in the fourth passage through the third evaporator.

[0024] In the main circuit of the first path, the charging working medium is heated and pressurized twice by the second and third compressors until it reaches the required temperature for high-temperature energy storage and then enters the second condenser. In the fourth path, after absorbing high-temperature heat energy from the main circuit through the second condenser, the high-temperature heat energy is stored in the advanced high-temperature heat storage tank. Then, a high-temperature heat storage medium with high-temperature heat energy is pumped to the third evaporator via an advanced high-temperature heat storage water pump. The high-temperature energy release application unit absorbs the high-temperature heat energy stored in the fourth path through the third evaporator for application. After being utilized, the temperature of the high-temperature heat storage medium decreases, and it is then stored again in the low-temperature heat storage tank. It is then pumped to the second condenser via a low-temperature heat storage water pump to absorb high-temperature heat energy from the main circuit again, forming a cycle of high-temperature heat energy absorption-storage-release-reabsorption.

[0025] The high-temperature energy release application unit includes a power generation unit, which includes a fifth passage through which the power generation and energy release working medium flows. Starting from the third evaporator, it is sequentially connected to an expansion generator set, a regenerator, and a preheater, before reconnecting to the third evaporator to form a loop. The preheater absorbs heat from the waste heat source to preheat the power generation and energy release working medium. The power generation unit employs an organic Rankine cycle. Because this invention utilizes low-grade waste heat, the heat energy provided by the waste heat source is insufficient to directly provide high-temperature heat energy; it can only preheat the power generation and energy release working medium, but the temperature is still higher than the temperature of the working medium after the high-temperature heat energy has been utilized, thus reducing energy consumption.

[0026] The power generation unit also includes a sixth passage, which connects sequentially from the regenerator to the third condenser and the working medium pump, and then back to the regenerator to form a loop. The sixth passage absorbs the waste heat from the working medium released during power generation in the fifth passage through the regenerator, and dissipates it through the third condenser. This allows for secondary utilization of waste heat and further cooling of the working medium, thereby more effectively absorbing low-grade waste heat and improving waste heat utilization efficiency.

[0027] The high-temperature energy release application unit can also be used for other applications, such as industrial process heating units, district heating units, steam supply units, and high-temperature material processing units. Industrial process heating units include molten salt furnaces or pyrolysis furnaces in the fifth passage; district heating units include boilers in the fifth passage, or connect the fifth passage to a heating network system; steam supply units include steam generators in the fifth passage; and high-temperature material processing units include rotary kilns, sintering machines, fluidized bed dryers, and other processing equipment in the fifth passage.

[0028] In the aforementioned system, valves including the first three-way valve, the second three-way valve, the third three-way valve, and the fourth three-way valve are used for the diversion and merging of the working medium. When the demand for cold (cold energy), heat (medium-temperature heat energy), or electricity (high-temperature heat energy used for power generation) changes, the flow rate of the working medium and the system pressure can be precisely adjusted by regulating the valve openings and compressor speed to meet the changing demands.

[0029] The present invention also provides a multi-stage energy storage method for Carnot battery energy storage, which adopts the above-mentioned multi-stage energy storage system for Carnot battery energy storage. The method includes a charging stage and an energy release stage, specifically including the following contents.

[0030] The charging phase includes cold energy charging, medium-temperature thermal energy charging, and high-temperature thermal energy charging. Details are as follows: Cold energy charging: The charging working medium is depressurized and cooled by the second throttle valve, and then enters the fourth three-way valve for diversion: one path enters the second evaporator to absorb heat from the low-grade waste heat source and heats up, and then enters the first three-way valve; the other path is depressurized by the first throttle valve and then enters the first evaporator to release cold energy into the second path; in the second path, the cold storage medium (cold storage water) in the high-temperature cold storage tank is pressurized by the high-temperature cold storage pump, absorbs cold energy from the first evaporator, and then enters the low-temperature cold storage tank for storage. During the cold energy charging process, the charging working medium in the first branch absorbs the heat released by the cold storage medium and heats up, then enters the first branch compressor for pressurization and heating, and then merges with the charging working medium in the main circuit through the first three-way valve.

[0031] Medium-temperature thermal energy charging: The charging working medium, after absorbing low-grade waste heat from the waste heat source, merges with the charging working medium in the first branch and enters the second compressor for pressurization and heating. It then enters the second three-way valve for branching: one branch enters the second branch, and the other enters the third compressor. The charging working medium in the second branch enters the second condenser and releases medium-temperature thermal energy into the third passage. In the third passage, the medium-temperature thermal storage medium (medium-temperature hot water) in the low-grade medium-temperature thermal storage tank is pressurized by the low-grade medium-temperature thermal storage pump, absorbs medium-temperature thermal energy from the second condenser, and then enters the high-grade medium-temperature thermal storage tank for storage. During the medium-temperature thermal energy charging process, the temperature of the charging working medium in the second branch decreases, and it enters the main circuit through the third three-way valve, merging with the charging working medium output from the third throttle valve.

[0032] High-temperature thermal energy charging: The charging working medium, which remains flowing in the main circuit after being diverted by the second three-way valve, enters the third compressor for pressurization and heating, and then enters the third condenser to release high-temperature thermal energy into the fourth passage. In the fourth passage, the high-temperature thermal storage medium (high-temperature hot water) in the low-level high-temperature thermal storage tank is pressurized by the low-level high-temperature thermal storage pump, absorbs high-temperature thermal energy from the third condenser, and then enters the high-level high-temperature thermal storage tank for storage. During the high-temperature thermal energy charging process, the temperature of the charging working medium decreases after passing through the third condenser, flows through the third throttle valve, and merges with the charging working medium output from the third three-way valve.

[0033] Afterwards, the combined charging working medium flows through the second throttle valve and returns to the second evaporator in the main circuit to absorb the low-grade heat energy from the waste heat source again, completing the charging stage process.

[0034] Energy release stages include cold energy release, intermediate-temperature thermal energy release, and high-temperature thermal energy release. Details are as follows: Cold energy release: The cold storage medium in the second channel starts from the low-temperature cold storage tank, is pressurized by the low-temperature cold storage pump and supplied to cold users for cold energy utilization. The cold storage medium that has been utilized and heated is returned to the high-temperature cold storage tank for storage.

[0035] Medium-temperature thermal energy release: The medium-temperature thermal storage medium in the third channel starts from the advanced medium-temperature thermal storage tank, is pressurized by the advanced medium-temperature thermal storage pump, and is supplied to medium-temperature heat users for use. The medium-temperature thermal storage medium that has been used and cooled is returned to the low-level medium-temperature thermal storage tank for storage.

[0036] High-temperature thermal energy release: The high-temperature thermal storage medium in the fourth path originates from the advanced high-temperature thermal storage tank, is pressurized by the advanced high-temperature thermal storage pump, and then transported to the third condenser to provide high-temperature thermal energy to the power generation unit. After being utilized and cooled, the high-temperature thermal storage medium returns to the low-temperature thermal storage tank for storage. In the power generation unit, the power generation energy release working medium in the fifth path absorbs the energy of the high-temperature thermal storage in the third evaporator, reaching a high-temperature and high-pressure state. It then enters the expansion generator set to perform work, converting mechanical energy into electrical energy output. After the power generation energy release working medium performs work on the expansion generator set, its temperature and pressure decrease. It then enters the regenerator to provide heat to the other side of the regenerator (i.e., the cold side, corresponding to the sixth path) and further cools down. At the same time, the liquid working medium in the sixth path absorbs the waste heat from the power generation energy release working medium and vaporizes. It then enters the third condenser to release heat and become liquid again. The liquid working medium is then circulated back to the regenerator by the working medium pump to absorb waste heat. Afterwards, the working medium that generates electricity and releases energy through the regenerator absorbs the low-grade waste heat energy from the waste heat source through the preheater, and then enters the third evaporator to complete the energy release stage.

[0037] This method precisely regulates the working fluid flow and system pressure by adjusting valve openings and compressor speed when cooling, heating, and electricity demands change, thereby meeting the changing needs. Specifically, it includes the following:

[0038] When the cooling demand increases / decreases: In order to meet the cooling capacity requirements, the speed of the first compressor is increased / decreased to increase / decrease the flow rate of the energizing working medium in the first branch, and the opening of the first throttle valve is increased / decreased to increase / decrease the flow rate of the energizing working medium in the first branch, thereby increasing / decreasing the cooling capacity; at the same time, the speed of the other compressors and the valve opening are adjusted according to the actual situation to make the system reach a balanced state.

[0039] When the heating demand increases / decreases: increase / decrease the speed of the second compressor to increase / decrease the flow rate of the charging working medium in the second branch, and at the same time increase / decrease the opening of the second throttle valve to increase / decrease the flow rate of the charging working medium in the second branch, thereby increasing / decrease the heating capacity; adjust the speed of the remaining compressors and the valve opening according to the actual situation to make the system reach a balanced state.

[0040] When the high-temperature heat demand increases / decreases: increase / decrease the speed of the third compressor to increase / decrease the flow rate of the charging working medium flowing through the third evaporator, and at the same time increase / decrease the opening of the third throttle valve to increase / decrease the flow rate of the charging working medium flowing through the third evaporator, thereby increasing or decreasing the heating capacity; adjust the speed of the remaining compressors and the valve opening according to the actual situation to make the system reach a balanced state.

[0041] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A multi-stage energy storage type Carnot battery energy storage system, characterized in that, The system includes a multi-stage energy charging unit and a multi-stage energy storage unit. The multi-stage energy charging unit includes a first passage, which sequentially connects to a second evaporator, a second compressor, a third compressor, a second condenser, a third throttle valve, and a second throttle valve, finally connecting to the second evaporator to form a main circuit. The energy charging medium flows through the first passage and absorbs heat from the waste heat source through the second evaporator. The main circuit of the first passage also has a first branch and a second branch connected in parallel. The inlet end of the first branch is connected between the second throttle valve and the second evaporator, and the outlet end of the first branch is connected between the second evaporator and the second compressor. The inlet end of the second branch is connected between the second compressor and the third compressor, and the outlet end of the second branch is connected between the third throttle valve and the second throttle valve. The multi-stage energy storage unit includes a second passage, a third passage, and a fourth passage. The second passage is used for cold storage and absorbs cold energy from the first branch through the first evaporator. The third passage is used for medium-temperature heat storage and absorbs heat energy from the second branch through the first condenser. The fourth passage is used for high-temperature heat storage and absorbs heat energy from the second condenser.

2. The Carnot battery energy storage system with multi-stage energy storage and combined heat and power generation according to claim 1, characterized in that, In the first branch, starting from the inlet end of the first branch, it passes through the first throttle valve, the first evaporator and the first compressor in sequence, and finally connects to the main circuit through the outlet end of the first branch.

3. The Carnot battery energy storage system for multi-stage energy storage and combined heat and power generation according to claim 2, characterized in that, The second passage circulates the cold storage medium and is connected in sequence from the first evaporator to the low-temperature cold storage tank, the low-temperature cold storage water pump, the cold user applying cold energy, the high-temperature cold storage tank and the high-temperature cold storage pump, and then connected to the first evaporator to form a loop.

4. The Carnot battery energy storage system for multi-stage energy storage and combined heat and power generation according to claim 1, characterized in that, The third passage circulates a medium-temperature thermal storage medium and is connected sequentially from the first condenser to a high-grade medium-temperature thermal storage tank, a high-grade medium-temperature hot water pump, a medium-temperature heat user using medium-temperature thermal energy, a low-grade medium-temperature thermal storage tank, and a low-grade medium-temperature hot water pump, before being connected to the first condenser to form a loop.

5. The Carnot battery energy storage system for multi-stage energy storage and combined heat and power generation according to claim 1, characterized in that, It also includes a high-temperature energy release application unit, in which a high-temperature heat storage medium flows, and from the second condenser, it is sequentially connected to an advanced high-temperature heat storage tank, an advanced high-temperature heat storage water pump, a third evaporator, a low-temperature heat storage tank, and a low-temperature heat storage water pump, and then connected to the second condenser to form a loop; the high-temperature energy release application unit absorbs the high-temperature heat energy stored in the fourth passage through the third evaporator.

6. The Carnot battery energy storage system for multi-stage energy storage and combined heat and power generation according to claim 5, characterized in that, The high-temperature energy release application unit is a power generation working unit, including a fifth passage. The power generation and energy release working medium flows through the fifth passage, and it is connected in sequence from the third evaporator to the expansion generator set, the regenerator and the preheater, and then connected to the third evaporator to form a loop. The preheater absorbs the heat from the waste heat source to preheat the power generation and energy release working medium.

7. A multi-stage energy storage type Carnot battery energy storage system according to claim 6, characterized in that, The power generation unit also includes a sixth passage, which connects the third condenser and the working medium pump in sequence from the regenerator, and then connects to the regenerator to form a loop.

8. A multi-stage energy storage method for Carnot battery energy storage, characterized in that, The system utilizes a multi-level energy storage type Carnot battery energy storage system according to any one of claims 1-7, comprising a charging stage and an energy release stage, wherein the charging stage includes: Cold energy charging: The charging working medium is depressurized and cooled by the second throttle valve and enters the fourth three-way valve for diversion: one path enters the second evaporator; the other path is depressurized by the first throttle valve and then enters the first evaporator to release cold energy into the second path; in the second path, the cold storage medium in the high temperature cold storage tank is pressurized by the high temperature cold storage pump, absorbs cold energy from the first evaporator and then enters the low temperature cold storage tank for storage. Medium-temperature thermal energy charging: The charging working medium enters the second compressor for pressurization and heating, and then enters the second three-way valve for diversion: one path enters the second branch, and the other path enters the third compressor; the charging working medium in the second branch enters the second condenser to release medium-temperature thermal energy into the third passage; in the third passage, the medium-temperature thermal energy storage medium in the low-level medium-temperature thermal energy storage tank is pressurized by the low-level medium-temperature thermal energy storage pump, absorbs medium-temperature thermal energy from the second condenser, and then enters the high-level medium-temperature thermal energy storage tank for storage; High-temperature thermal energy charging: The charging working medium is pressurized and heated by the third compressor, and then enters the third condenser to release high-temperature thermal energy to the fourth passage; in the fourth passage, the high-temperature thermal energy storage medium of the low-level high-temperature thermal energy storage tank is pressurized by the low-level high-temperature thermal energy storage pump, absorbs high-temperature thermal energy from the third condenser, and then enters the high-level high-temperature thermal energy storage tank for storage. The energy release phase includes: Cold energy release: The cold storage medium in the second channel starts from the low-temperature cold storage tank, is pressurized by the low-temperature cold storage pump and supplied to cold users for cold energy utilization. The cold storage medium that has been utilized and heated is returned to the high-temperature cold storage tank for storage. Medium-temperature thermal energy release: The medium-temperature thermal storage medium in the third channel starts from the advanced medium-temperature thermal storage tank, is pressurized by the advanced medium-temperature thermal storage pump and supplied to medium-temperature thermal users for the use of medium-temperature thermal energy. The medium-temperature thermal storage medium that has been used and cooled down is returned to the low-level medium-temperature thermal storage tank for storage. High-temperature thermal energy release: The high-temperature thermal storage medium in the fourth channel starts from the advanced high-temperature thermal storage tank, is pressurized by the advanced high-temperature thermal storage pump and then transported to the third condenser to provide high-temperature thermal energy to the power generation unit. The high-temperature thermal storage medium that has been utilized and cooled down is returned to the low-temperature thermal storage tank for storage.

9. A multi-stage energy storage method for Carnot battery energy storage according to claim 8, characterized in that, In the power generation unit, the power generation and energy release working medium in the fifth channel absorbs the energy stored in the high-temperature heat in the third evaporator, reaching a high-temperature and high-pressure state, and then enters the expansion generator set to do work. The expansion generator set converts mechanical energy into electrical energy output. After the power generation and energy release working medium has its temperature and pressure reduced after being worked by the expansion generator set, it enters the regenerator to provide heat to the other side of the regenerator and further cools down. After that, it absorbs the low-grade waste heat energy from the waste heat source in the preheater and then enters the third evaporator to complete the work process of the energy release stage.

10. A multi-stage energy storage method for Carnot battery energy storage according to claim 8, characterized in that, When the cooling demand increases / decreases: increase / decrease the speed of the first compressor to increase / decrease the flow rate of the energizing working medium in the first branch, and simultaneously increase / decrease the opening of the first throttle valve to increase / decrease the flow rate of the energizing working medium in the first branch; adjust the speed of the remaining compressors and the valve openings according to the actual situation to bring the system to a balanced state. When the heating demand increases / decreases: increase / decrease the speed of the second compressor to increase / decrease the flow rate of the charging working medium in the second branch, and simultaneously increase / decrease the opening of the second throttle valve to increase / decrease the flow rate of the charging working medium in the second branch; adjust the speed of the remaining compressors and the valve openings according to the actual situation to bring the system into a balanced state; When the high-temperature heat demand increases / decreases: increase / decrease the speed of the third compressor to increase / decrease the flow rate of the charging working medium flowing through the third evaporator, and at the same time increase / decrease the opening of the third throttle valve to increase / decrease the flow rate of the charging working medium flowing through the third evaporator; Adjust the speed of the remaining compressors and the valve openings according to the actual situation to bring the system into a balanced state.

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