Compressed air and medium-depth geothermal two-way heat coupling energy storage and power supply system

Abstract

The present application relates to a kind of compressed air and middle-deep geothermal two-way heat coupling energy storage power supply system, it is applicable to electric power and heat storage technical field.The system includes: multistage compression module, with multistage centrifugal compressor, interstage heat exchanger and last stage compression waste heat collection unit;Gas storage unit is used to store the high-pressure air generated by the multistage compression module;Multistage expansion module, with multistage expansion unit and expansion machine inlet temperature compensation unit;High-temperature heat storage module, with interstage heat exchanger and multistage expansion module are connected;Middle-low temperature heat storage module, with last stage compression waste heat collection unit and expansion machine inlet temperature compensation unit are connected;Geothermal well module, with district heating pipe network is connected, can be used for district heating pipe network heating;Two-way heat standby control unit, with middle-low temperature heat storage module, geothermal well module and district heating pipe network are connected, can control geothermal well module heating for middle-low temperature heat storage module, or control low-temperature heat storage module heating for district heating pipe network.

Description

Technical Field

[0001] This invention relates to a bidirectional thermally coupled energy storage and supply system using compressed air and medium-deep geothermal energy. It is applicable to the fields of power and thermal storage technology. Background Technology

[0002] With the global energy structure transformation and the increasing awareness of environmental protection, compressed air energy storage (CAES) technology has become one of the important development directions in the field of large-scale energy storage due to its advantages such as high efficiency, environmental protection, and flexibility. However, existing traditional compressed air technologies have the following technical defects in the thermal management stage: Traditional afterburning compressed air energy storage systems require the consumption of fuels such as natural gas in the afterburning process during the energy release and power generation stage, which leads to increased carbon emissions and also results in the dual contradiction of energy waste and dependence on fossil fuels; the high-temperature compression heat generated during the compression process of traditional adiabatic compressed air energy storage systems can be recovered through the heat storage tank, but the low-grade heat generated in the final stage compression is often directly cooled and discharged due to poor temperature stability, resulting in energy loss; although traditional adiabatic compressed air energy storage recovers compression heat through the heat storage tank, the temperature decay of the heat storage medium still reduces the work capacity during the expansion stage.

[0003] Currently, existing technologies combine compressed air energy storage with geothermal energy. However, these existing methods have significant limitations: geothermal energy is only used as a preheating heat source or an independent heating system, failing to establish a two-way backup relationship between compressed heat and geothermal energy, resulting in low system efficiency; geothermal heating systems generate a large amount of idle heat energy during the non-heating season, while traditional compressed air energy storage systems face insufficient supplementary heat sources during peak summer electricity consumption; and a graded coupling mechanism has not been designed to address the temperature-temporal distribution characteristics of compressed heat and geothermal energy, resulting in low-grade compressed heat not being effectively used for heating and medium- and low-temperature geothermal energy not accurately compensating for the expansion process. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a bidirectional thermally coupled energy storage and supply system of compressed air and medium-deep geothermal energy, in view of the above-mentioned problems.

[0005] The technical solution adopted in this invention is: a bidirectional thermal coupling energy storage and supply system for compressed air and medium-deep geothermal energy, comprising:

[0006] A multi-stage compression module is used to compress air into high-pressure air using electrical energy. It has a multi-stage centrifugal compressor, an interstage heat exchanger and a final stage compression waste heat collection unit.

[0007] The air storage unit is used to store the high-pressure air generated by the multi-stage compression module;

[0008] The multi-stage expansion module is used to generate electrical energy by using the high-pressure air stored in the gas storage unit. It has a multi-stage expander unit and an expander inlet temperature compensation unit.

[0009] A high-temperature thermal storage module, connected to the interstage heat exchanger and the multi-stage expansion module, is used to collect and store the high-temperature compression heat generated by the multi-stage compression module, and can be used to supply heat to the multi-stage expansion module.

[0010] The medium-low temperature heat storage module is connected to the final stage compression waste heat collection unit and the expander inlet temperature compensation unit. It is used to collect the low-grade heat generated by the final stage compression of the multi-stage compression module and can be used to supply heat to the expander inlet temperature compensation unit.

[0011] Geothermal well modules are connected to the district heating network and can be used to supply heat to the district heating network.

[0012] The bidirectional thermal backup control unit is connected to the medium-low temperature thermal storage module, the geothermal well module, and the district heating network. It can control the geothermal well module to supply heat to the medium-low temperature thermal storage module, or control the low temperature thermal storage module to supply heat to the district heating network.

[0013] The bidirectional thermal backup control unit includes sensors, a controller, and an electric switching valve. The controller controls the geothermal well module to supply heat to the medium-low temperature thermal storage module based on the temperature of the medium-low temperature thermal storage module collected by the sensors, and controls the low temperature thermal storage module to supply heat to the district heating network based on the flow rate of the geothermal well collected by the sensors.

[0014] The multi-stage compression module also has an intake filter.

[0015] The high-temperature thermal storage module uses molten salt thermal storage material, filled with ternary nitrate, with a thermal storage temperature range of 150-350℃ and a thermal storage density of approximately 150-200 kJ / kg.

[0016] The operating temperature of the medium-low temperature thermal storage module is matched with the temperature of the geothermal well module.

[0017] The medium-low temperature thermal storage module adopts a modular phase change thermal storage box group. The thermal storage medium can be selected from stearic acid-graphite composite, glycerol aqueous solution or water. The capacity of a single thermal storage box can be expanded.

[0018] The gas storage unit includes a high-pressure gas storage chamber and a pressure buffer tank.

[0019] In the multi-stage expansion module, the first two stages are heated solely by the high-temperature thermal storage module, while the subsequent stages are supplemented with heat by the medium- and low-temperature thermal storage modules.

[0020] The beneficial effects of this invention are as follows: This invention recovers compression waste heat in temperature-grade stages. Compression heat from the non-final high-temperature stage is recovered to the high-temperature heat storage module via an interstage heat exchanger; the final-stage compression waste heat is directly connected to the medium- and low-temperature heat storage module through the final-stage compression waste heat collection unit, replacing the heat from traditional coolers. The high-temperature heat storage module provides a basic heat source for the multi-stage expansion modules, while the medium- and low-temperature heat storage modules supplement the temperature of the multi-stage expansion modules, thereby improving waste heat utilization and system efficiency; optimizing energy supply costs and reducing investment in traditional coolers.

[0021] In this invention, the low-temperature thermal storage module and the geothermal well heating pipeline form a closed loop, creating a bidirectional backup mechanism. The bidirectional thermal backup control unit can control the geothermal well module to supply heat to the low-temperature thermal storage module, or control the low-temperature thermal storage module to supply heat to the district heating network. This allows the use of geothermal energy collected by the low-temperature thermal storage module to generate a large amount of idle heat energy during the non-heating season, as well as the residual heat from the final stage compression, to perform staged heating of the air before expansion. The intensity of the heat compensation is dynamically adjusted according to the thermal storage parameters. This invention, on the one hand, can compensate for the temperature loss caused by expansion during the energy release process of the gas storage facility, reducing the initial investment in the gas storage facility; on the other hand, it utilizes the large amount of idle heat energy generated by geothermal energy during the non-heating season to improve power generation efficiency.

[0022] This invention achieves the effect of storing heat during the non-heating season and supplementing heat during the heating season by cooperating with a medium-low temperature heat storage module, a two-way heat backup control unit, and a geothermal well module. On the one hand, it can enhance the cross-seasonal regulation capability, and on the other hand, it can improve the reliability of the geothermal heating system's energy supply under extreme conditions.

[0023] This invention achieves the value-added utilization of waste heat from the final stage of compression by bidirectionally coupling the cascade utilization of compressed heat with geothermal expansion enhancement, thereby eliminating dependence on fossil energy and realizing cross-seasonal energy storage and regulation of geothermal resources. It realizes a chain-like energy upgrade utilization of waste heat recovery, geothermal compensation, and expansion enhancement, and constructs a heat source system in which compressed heat and geothermal energy serve as backups for each other, thereby improving the reliability of energy supply under extreme operating conditions.

[0024] This invention achieves refined management and storage of heat at different temperatures through a combination design of high-temperature thermal storage modules and medium- and low-temperature thermal storage modules, effectively solving the problem of reduced work capacity caused by the temperature decay of the thermal storage medium in traditional adiabatic compressed air energy storage systems.

[0025] This invention employs a combined design of a multi-stage expander unit and an expander inlet temperature compensation unit, which achieves precise compensation for the working fluid temperature during the expansion stage, thereby improving the power generation efficiency and stability of the system under different load conditions. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of an embodiment.

[0027] 1. Multi-stage compression module; 2. Gas storage unit; 3. Multi-stage expansion module; 4. High-temperature thermal storage module; 5. Medium and low-temperature thermal storage module; 6. Geothermal well module; 7. District heating network; 8. Two-way thermal backup control unit. Detailed Implementation

[0028] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0029] like Figure 1 As shown, this embodiment is a bidirectional thermal coupling energy storage and supply system for compressed air and medium-deep geothermal energy, including: a multi-stage compression module, an air storage unit, a multi-stage expansion module, a high-temperature thermal storage module, a medium-low temperature thermal storage module, a geothermal well module, and a bidirectional thermal backup control unit, etc.

[0030] In this embodiment, the multi-stage compression module includes a multi-stage centrifugal compressor, an interstage heat exchanger, an intake filter, and a final-stage compression waste heat collection unit. Each compressor in the multi-stage centrifugal compressor can use electrical energy to compress air into high-pressure air. The interstage heat exchanger is located between two adjacent centrifugal compressors and is used to recover the high-temperature compression heat generated during the compression process. The final-stage compression waste heat collector adopts a fluoroplastic surface-modified stainless steel plate-fin heat exchanger, which increases the heat transfer coefficient to 500 W / (m²·K) under operating conditions of 40-80℃. The final-stage compression waste heat collection unit is located at the outlet end of the multi-stage compression module and is used to collect the low-grade heat at 40-80℃ at the end of the multi-stage compression module.

[0031] In this example, the air inlet of the air storage unit is connected to the outlet of the multi-stage compression unit. The air storage unit consists of a high-pressure air storage chamber and a pressure buffer tank. The high-pressure air storage chamber is used to store the high-pressure air generated by the multi-stage compression module, and the pressure buffer tank is used to stabilize the system pressure.

[0032] In this embodiment, the multi-stage expansion module includes a multi-stage expander unit and an expander inlet temperature compensation module. The multi-stage expander unit adopts an axial flow structure with three or more stages. Each stage of the expander unit can use the high-pressure air stored in the gas storage unit to generate electrical energy.

[0033] In this embodiment, the high-temperature thermal storage module is connected to the interstage heat exchanger and the multi-stage expansion module. It collects and stores the high-temperature compression heat generated by the multi-stage compression module via the interstage heat exchanger and provides a basic heat source for the multi-stage expansion module. In this example, the high-temperature thermal storage module uses a molten salt thermal storage body filled with ternary nitrate (NaNO3-KNO3-LiNO3), with a thermal storage temperature range of 150-350℃ and a thermal storage density of approximately 150-200 kJ / kg.

[0034] In this example, the low-temperature thermal energy storage module is connected to the waste heat collection unit of the final compression stage in the multi-stage compression module and the expander inlet temperature compensation unit in the multi-stage expansion module. It is used to collect the low-grade heat generated by the final compression stage of the multi-stage compression module and to provide heat to the expander inlet temperature compensation unit.

[0035] In this embodiment, the operating temperature of the medium-low temperature thermal storage module is matched with the geothermal well temperature of the geothermal well module. The medium-low temperature thermal storage module adopts a modular phase change thermal storage box group. The thermal storage medium can be selected from stearic acid-graphite composite, glycerol aqueous solution or water. The capacity of a single thermal storage box can be expanded.

[0036] In this embodiment, the temperature-pressure change of the air working fluid in the multi-stage expander unit exhibits a step-like attenuation characteristic. The first two stages are heated solely by high-temperature thermal storage modules, while the subsequent stages are supplemented by medium- and low-temperature thermal storage modules, with the temperature difference between stages controlled within ±15℃. The expander inlet temperature compensation unit dynamically adjusts the compensation intensity based on the thermal storage parameters. By monitoring the temperature of the high-temperature thermal storage module in real time, it utilizes the energy collected by the medium- and low-temperature thermal storage modules to increase or supplement the inlet air temperature of the subsequent expander stages. This compensates for the drop in expander inlet temperature caused by the decrease in temperature and energy of the high-temperature thermal storage module, ensuring that the expander operates under optimal design conditions and maximizing energy conversion efficiency within the safety boundary.

[0037] In this embodiment, the geothermal well module is connected to the district heating network and, together with the heating water circulation pump, can provide heat to the district heating network.

[0038] In this example, the bidirectional thermal standby control unit is connected to the low-temperature thermal storage module, the geothermal well module, and the district heating network. The bidirectional thermal standby control unit includes sensors, controllers, and electric switching valves. The controller controls the geothermal well module to supply heat to the low-temperature thermal storage module based on the temperature of the low-temperature thermal storage module collected by the sensors, and controls the low-temperature thermal storage module to supply heat to the district heating network based on the flow rate of the geothermal well collected by the sensors.

[0039] In this embodiment, the controller can collect real-time temperature and load data from key system nodes using temperature sensors and power meters. Combined with acquired weather forecasts and grid dispatch data, it analyzes the correlation between historical data and real-time input using machine learning algorithms (such as LSTM or random forest) to predict the heating / power generation demand curve for the next 12 hours. Based on the prediction results and the current status of the thermal storage unit (such as temperature and remaining storage capacity), it calculates the target temperature adjustment value and generates phased heating / cooling commands. For example, if an increase in heating demand is predicted, the thermal storage unit's heating program is initiated in advance, utilizing high thermal conductivity thermal storage materials to quickly respond to demand. When a 20% decrease in geothermal well flow is detected, it automatically switches to compressed heat standby mode and triggers the release of heat from the medium- and low-temperature thermal storage modules. The controller can automatically adjust the operating status of each module according to real-time temperature and load conditions, achieving system self-adaptation and energy optimization.

[0040] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A bidirectional thermal coupling energy storage and supply system for compressed air and medium-deep geothermal energy, characterized in that, include: A multi-stage compression module is used to compress air into high-pressure air using electrical energy. It has a multi-stage centrifugal compressor, an interstage heat exchanger and a final stage compression waste heat collection unit. The air storage unit is used to store the high-pressure air generated by the multi-stage compression module; The multi-stage expansion module is used to generate electrical energy by using the high-pressure air stored in the gas storage unit. It has a multi-stage expander unit and an expander inlet temperature compensation unit. A high-temperature thermal storage module, connected to the interstage heat exchanger and the multi-stage expansion module, is used to collect and store the high-temperature compression heat generated by the multi-stage compression module, and can be used to supply heat to the multi-stage expansion module. The medium-low temperature heat storage module is connected to the final stage compression waste heat collection unit and the expander inlet temperature compensation unit. It is used to collect the low-grade heat generated by the final stage compression of the multi-stage compression module and can be used to supply heat to the expander inlet temperature compensation unit. Geothermal well modules are connected to the district heating network and can be used to supply heat to the district heating network. The bidirectional thermal backup control unit is connected to the medium-low temperature thermal storage module, the geothermal well module, and the district heating network. It can control the geothermal well module to supply heat to the medium-low temperature thermal storage module, or control the medium-low temperature thermal storage module to supply heat to the district heating network.

2. The compressed air and medium-deep geothermal bidirectional thermal coupling energy storage and supply system according to claim 1, characterized in that, The bidirectional thermal backup control unit includes sensors, a controller, and an electric switching valve. The controller controls the geothermal well module to supply heat to the medium-low temperature thermal storage module based on the temperature of the medium-low temperature thermal storage module collected by the sensor, or the controller controls the medium-low temperature thermal storage module to supply heat to the district heating network based on the flow rate of the geothermal well collected by the sensor.

3. The compressed air and medium-deep geothermal bidirectional thermal coupling energy storage and supply system according to claim 1, characterized in that, The multi-stage compression module also has an intake filter.

4. The compressed air and medium-deep geothermal bidirectional thermal coupling energy storage and supply system according to claim 1, characterized in that, The high-temperature thermal storage module uses molten salt thermal storage material, filled with ternary nitrate, with a thermal storage temperature range of 150-350℃ and a thermal storage density of 150-200kJ / kg.

5. The compressed air and medium-deep geothermal bidirectional thermal coupling energy storage and supply system according to claim 1, characterized in that, The operating temperature of the medium-low temperature thermal storage module is matched with the temperature of the geothermal well module.

6. The compressed air and medium-deep geothermal bidirectional thermal coupling energy storage and supply system according to claim 1, characterized in that, The medium- and low-temperature thermal storage module adopts a modular phase change thermal storage box assembly. The thermal storage medium can be selected from stearic acid-graphite composite material, glycerol aqueous solution or water, and the capacity of a single thermal storage box can be expanded.

7. The compressed air and medium-deep geothermal bidirectional thermal coupling energy storage and supply system according to claim 1, characterized in that, The gas storage unit includes a high-pressure gas storage chamber and a pressure buffer tank.

8. The compressed air and medium-deep geothermal bidirectional thermal coupling energy storage and supply system according to claim 1, characterized in that, In the multi-stage expansion module, the first two stages are heated solely by the high-temperature thermal storage module, while the subsequent stages are supplemented with heat by the medium- and low-temperature thermal storage modules.

Images