Liquid co2 energy storage system based on waste heat recovery of thermal power generating units

Abstract

The application provides a liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit, comprising: a gas storage tank for storing gaseous carbon dioxide; a liquid storage tank for storing liquid carbon dioxide; a liquefaction assembly capable of obtaining gaseous carbon dioxide from the gas storage tank and converting the gaseous carbon dioxide into liquid carbon dioxide and injecting the liquid carbon dioxide into the liquid storage tank by using electric energy provided by the thermal power unit; a gasification assembly capable of obtaining liquid carbon dioxide from the liquid storage tank and converting the liquid carbon dioxide into gaseous carbon dioxide and injecting the gaseous carbon dioxide into the gas storage tank; and a heat storage assembly for absorbing heat released by the thermal power unit and heat released in the carbon dioxide liquefaction process and capable of providing heat to the gasification assembly to warm up gaseous or liquid carbon dioxide in the gasification assembly. The energy storage system improves energy utilization efficiency by recycling waste heat of the thermal power unit.

Description

Technical Field

[0001] This invention relates to the field of physical energy storage technology, and in particular to a liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units. Background Technology

[0002] Seeking advanced methods to improve energy efficiency has become a primary concern globally. For a major energy producer and consumer like China, there is a need for both energy conservation and emission reduction, as well as energy growth to support economic development. This necessitates the vigorous development of the energy storage industry.

[0003] Thermal power generation is a major method of producing electricity in my country and many other countries around the world. The process of thermal power generation includes: fuel is burned to heat water to generate steam, which converts the chemical energy of the fuel into heat energy. The steam pressure drives the turbine to rotate, converting the heat energy into mechanical energy. Then, the turbine drives the generator to rotate, converting the mechanical energy into electrical energy.

[0004] Current physical energy storage methods primarily utilize physical methods such as water pumping, compressed air, and flywheels to store energy. These methods are environmentally friendly and green, thus gaining wider application. However, in the process of thermal power generation, in addition to the generated electricity, a significant amount of heat energy is lost during the exhaust process of thermal power units. Conventional physical energy storage methods often only convert and store the electricity generated by thermal power generation through a single energy conversion method, neglecting the heat loss from thermal power units, resulting in low energy utilization efficiency. Summary of the Invention

[0005] This invention provides a liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units, which solves the problem of low energy utilization rate in the existing thermal power energy storage process and realizes an energy storage solution that can improve the energy utilization rate of thermal power units.

[0006] This invention provides a liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units, comprising: a gas storage tank for storing gaseous carbon dioxide; a liquid storage tank for storing liquid carbon dioxide; a liquefaction component capable of using electrical energy provided by the thermal power unit to obtain gaseous carbon dioxide from the gas storage tank and convert it into liquid carbon dioxide, which is then injected into the liquid storage tank; a vaporization component capable of obtaining liquid carbon dioxide from the liquid storage tank and converting it into gaseous carbon dioxide, which is then injected into the gas storage tank; and a heat storage component for absorbing heat released by the thermal power unit and heat released during the carbon dioxide liquefaction process, and for providing heat to the vaporization component to raise the temperature of the gaseous or liquid carbon dioxide in the vaporization component.

[0007] According to the present invention, a liquid carbon dioxide energy storage system based on waste heat recovery from a thermal power unit is provided. The heat storage component includes a multi-stream waste heat storage tank, a heat absorption circuit, and a heat release circuit. The heat absorption circuit extends through the multi-stream waste heat storage tank and the liquefaction component to absorb the heat released during the carbon dioxide liquefaction process and raise the temperature of the heat storage medium in the multi-stream waste heat storage tank. The heat release circuit extends through the multi-stream waste heat storage tank and the gasification component to guide the heat of the heat storage medium to the carbon dioxide in the gasification component.

[0008] According to the present invention, a liquid carbon dioxide energy storage system based on waste heat recovery from a thermal power unit is provided. The heat storage component includes a steam circuit connected to the thermal power unit, the steam circuit extending through the multi-stream waste heat storage tank; downstream of the multi-stream waste heat storage tank, the steam circuit is provided with a condenser capable of converting steam into condensate and a feedwater pump capable of supplying the condensate to the thermal power unit.

[0009] According to the present invention, a liquid carbon dioxide energy storage system based on waste heat recovery from a thermal power unit is provided. The heat storage component includes a flue gas pipeline connecting the thermal power unit and the gas storage tank, the flue gas pipeline extending through the multi-flow waste heat storage tank; downstream of the multi-flow waste heat storage tank, the flue gas pipeline is provided with a capture unit capable of recovering gaseous carbon dioxide from the flue gas.

[0010] According to the present invention, a liquid carbon dioxide energy storage system based on waste heat recovery from a thermal power unit is provided. The liquefaction component includes a compressor, a cooler, and a throttle valve. The compressor operates using electrical energy generated by the thermal power unit, and the cooler is used to guide the heat from the gaseous carbon dioxide discharged from the compressor to the heat storage component.

[0011] According to the present invention, a liquid carbon dioxide energy storage system based on waste heat recovery from a thermal power unit is provided, wherein there are multiple compressors and multiple coolers, which are alternately distributed along the carbon dioxide flow direction of the liquefaction component.

[0012] According to the present invention, a liquid carbon dioxide energy storage system based on waste heat recovery of thermal power units is provided, wherein a gas-liquid separator is provided between the throttling valve and the storage tank; the gas-liquid separator is used to introduce the separated liquid carbon dioxide into the storage tank and to transport the gaseous carbon dioxide back to the cooler.

[0013] According to the present invention, a liquid carbon dioxide energy storage system based on waste heat recovery from a thermal power unit is provided. The gasification component includes a booster pump, a heater, and an expander. The heater is used to absorb the heat provided by the heat storage component to heat the gaseous or liquid carbon dioxide passing through the heater. During the heating and gasification process, the carbon dioxide does work in the expander to drive a generator to generate electricity.

[0014] According to the present invention, a liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit is provided, wherein there are multiple heaters and multiple expanders, and the multiple heaters and multiple expanders are alternately distributed along the carbon dioxide flow direction of the gasification component.

[0015] According to the present invention, a liquid carbon dioxide energy storage system based on waste heat recovery of thermal power units is provided, wherein a buffer tank is provided between the expander and the gas storage tank, and the buffer tank is used to slow down the flow rate of gaseous carbon dioxide before it enters the gas storage tank.

[0016] This invention provides a liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units. A liquefaction component uses the electrical energy generated by the thermal power unit to convert gaseous carbon dioxide stored in a storage tank into liquid carbon dioxide, which is then injected into a liquid storage tank, thus achieving physical energy storage of the electrical energy generated by the thermal power unit. When it is necessary to release the stored energy, a vaporization component converts the liquid carbon dioxide in the liquid storage tank back into gaseous carbon dioxide, utilizing the energy released during the carbon dioxide vaporization phase change to generate electrical energy. A heat storage component recovers the waste heat from the thermal power unit and the heat released during carbon dioxide liquefaction. When it is necessary to release the stored energy, the heat obtained by the heat storage component is used to heat the carbon dioxide during the vaporization process, which not only improves the energy release efficiency of the energy storage system but also enhances the energy utilization rate of the thermal power unit. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a structural block diagram of the liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units provided by the present invention;

[0019] Figure 2 This is a structural block diagram of a multi-stream waste heat storage tank for a liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units, provided by the present invention.

[0020] Figure label:

[0021] 101: Gas storage tank; 102: Liquid storage tank; 103: Buffer tank; 111: Compressor; 112: Cooler; 113: Throttling valve; 114: Gas-liquid separator; 121: Booster pump; 122: Heater; 123: Expander; 132: Heat absorption circuit; 133: Heat release circuit; 134: Steam circuit; 135: Condenser; 136: Feed water pump; 137: Flue gas pipeline; 138: Collection unit; 200: Multi-stream waste heat storage tank; 210: Tank body; 211: Inner cavity; 212: Heat storage medium inlet; 213: Heat storage medium outlet; 214: Agitator; 220: First heat exchange section; 221: Cooling coil; 230: Second heat exchange section; 231: Heating coil; 232: Softened water tank; 241: Steam coil; 242: Flue gas coil. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] In thermal power generation, the heat released from the combustion of coal in the boiler heats water into steam with a certain pressure and temperature. The steam then travels through pipes to the turbine, where it expands and performs work, driving the generator to rotate at high speed and generate electricity. Traditional energy storage methods can typically only store the electrical energy produced by thermal power units. However, during operation, a large amount of heat energy is lost with the exhaust gas, resulting in low energy utilization. This invention utilizes the massive flue gas and waste heat emissions from thermal power units to establish a liquid carbon dioxide energy storage system based on the waste heat recovery from thermal power units. It uses the waste heat from the flue gas of thermal power generation to supplement the energy storage system with sufficient heat, achieving complementary advantages between the systems and thus increasing overall operating efficiency.

[0024] Physical energy storage mainly includes pumped hydro storage, compressed air storage, and flywheel energy storage. This invention uses carbon dioxide physical energy storage, which can capture carbon dioxide from the flue gas of thermal power units and introduce it into the energy storage system, thereby enabling the recovery and utilization of carbon emissions from thermal power units.

[0025] The following is combined Figure 1 This invention describes a liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units, according to a preferred embodiment of the present invention.

[0026] like Figure 1As shown, the liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units includes a gas storage tank 101 for storing gaseous carbon dioxide and a liquid storage tank 102 for storing liquid carbon dioxide.

[0027] The carbon dioxide movement path from the gas storage tank 101 to the liquid storage tank 102 is sequentially equipped with a compressor 111, a cooler 112, a throttle valve 113, and a gas-liquid separator 114. The compressor 111 starts based on the electrical energy provided by the thermal power unit or other electrical energy (such as off-peak electricity or renewable energy generation). The gaseous carbon dioxide in the gas storage tank 101 is compressed by the compressor 111, cooled by the cooler 112, and its flow is regulated by the throttle valve 113. The gas-liquid separator 114 separates the converted liquid carbon dioxide and injects it into the liquid storage tank 102, completing the energy storage process.

[0028] The carbon dioxide movement path from the liquid storage tank 102 to the gas storage tank 101 is sequentially equipped with a booster pump 121, a heater 122, and an expander 123. The booster pump 121, powered by electricity from a thermal power unit or other sources, pumps the liquid carbon dioxide from the liquid storage tank 102 to the heater 122. The heater 122 heats the liquid carbon dioxide, causing its temperature to rise and resulting in a vaporization phase change. The carbon dioxide then expands and performs work in the expander 123, releasing the internal energy stored in the liquid carbon dioxide. Electrical energy is generated using a power generation device linked to the expander 123. The gaseous carbon dioxide after the phase change is buffered by the buffer tank 103 and returns to the gas storage tank 101, completing the energy release process.

[0029] The energy storage and release processes described above in the energy storage system form a complete carbon dioxide cycle system. For example... Figure 1 As shown, the thermal storage components of the energy storage system include a multi-stream waste heat storage tank 200, a heat absorption circuit 132, and a heat release circuit 133. The heat absorption circuit 132 extends through the cooler 112 and the interior of the multi-stream waste heat storage tank 200, allowing the heat-absorbing medium in the heat absorption circuit 132 to conduct the heat released during the liquefaction of carbon dioxide obtained from the cooler 112 to the heat storage medium within the multi-stream waste heat storage tank 200. The heat release circuit 133 extends through the interior of the multi-stream waste heat storage tank 200 and the heater 122, allowing the heat-release medium in the heat release circuit 133 to conduct the heat obtained from the heat storage medium to the heater 122, thereby improving the vaporization efficiency of liquid carbon dioxide. Through heat conduction by the thermal storage components, heat waste during the energy storage process of the energy storage system is reduced, and the energy release efficiency during the energy release process is improved.

[0030] On the other hand, the heat storage assembly also includes a steam circuit 134 and a flue gas pipeline 137. At least a portion of the steam emitted by the thermal power unit passes through the interior of the multi-flow waste heat storage tank 200 along the steam circuit 134, thereby allowing the heat storage medium to absorb the waste heat in the steam. The cooled steam forms condensate in the condenser, which can be supplied back to the thermal power unit, reducing water waste. At least a portion of the flue gas emitted by the thermal power unit passes through the interior of the multi-flow waste heat storage tank 200 along the flue gas pipeline 137, thereby allowing the heat storage medium to absorb the waste heat in the flue gas. The cooled flue gas enters the collection unit 138 to collect and recover carbon dioxide from the flue gas. The recovered carbon dioxide can be injected into the gas storage tank 101 for carbon dioxide recycling in the energy storage system, thus not only obtaining a supplementary source of carbon dioxide but also alleviating the carbon emission problem of the thermal power unit.

[0031] like Figure 1 As shown, the storage tank 102 may be additionally provided with an outlet for discharging liquid carbon dioxide. This allows for the discharge of liquid carbon dioxide to maintain system balance when the carbon dioxide content in the system is too high; or, when additional physical energy storage is required, the liquid carbon dioxide can be exported and stored in other containers; or it can be used as a liquid carbon dioxide production source for other industrial applications.

[0032] The liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units of the present invention can realize multiple working modes such as carbon dioxide energy storage, waste heat recovery from flue gas and steam of thermal power units, liquid carbon dioxide production, and hot water supply, and can achieve a high energy utilization rate.

[0033] To better understand the above technical solutions, the following will describe them in detail with reference to the accompanying drawings and various specific embodiments of the present invention.

[0034] According to the present invention, a liquid carbon dioxide energy storage system based on waste heat recovery from a thermal power unit includes: a gas storage tank 101 for storing gaseous carbon dioxide; a liquid storage tank 102 for storing liquid carbon dioxide; a liquefaction component capable of using electrical energy provided by the thermal power unit to obtain gaseous carbon dioxide from the gas storage tank 101 and convert it into liquid carbon dioxide, which is then injected into the liquid storage tank 102; and a vaporization component capable of obtaining liquid carbon dioxide from the liquid storage tank 102 and converting it into gaseous carbon dioxide, which is then injected into the gas storage tank 101. By using the liquefaction component to convert the gaseous carbon dioxide stored in the gas storage tank 101 into liquid carbon dioxide using electrical energy generated by the thermal power unit and injecting it into the liquid storage tank 102, physical energy storage of the electrical energy generated by the thermal power unit is achieved. When it is necessary to release the physical energy storage, the vaporization component converts the liquid carbon dioxide in the liquid storage tank 102 back into gaseous carbon dioxide, which can then be combined with a power generation device to generate electricity using the energy released during the carbon dioxide vaporization phase change.

[0035] The liquid storage tank 102 is preferably a steel pressure vessel with an external insulation device to maintain a low internal temperature environment. The gas storage tank 101 can be a steel spherical tank or a container with an air bladder.

[0036] The energy storage system also includes thermal storage components to absorb heat released by the thermal power unit and the heat released during carbon dioxide liquefaction. This heat can then be supplied to the gasification components to raise the temperature of the gaseous or liquid carbon dioxide within them. The thermal storage components can recover waste heat from the thermal power unit (such as heat from exhaust gas and steam) and the heat released during carbon dioxide liquefaction. When physical energy storage needs to be released, the heat obtained from the thermal storage components can be used to heat the carbon dioxide during the gasification process. This not only improves the energy release efficiency of the energy storage system but also enhances its energy utilization rate from the thermal power unit.

[0037] According to a liquid carbon dioxide energy storage system based on waste heat recovery from a thermal power unit according to the present invention, the heat storage component includes a multi-stream waste heat storage tank 200, a heat absorption circuit 132, and a heat release circuit 133; the heat absorption circuit 132 extends through the multi-stream waste heat storage tank 200 and the liquefaction component to absorb the heat released during the carbon dioxide liquefaction process and raise the temperature of the heat storage medium in the multi-stream waste heat storage tank 200; the heat release circuit 133 extends through the multi-stream waste heat storage tank 200 and the gasification component to guide the heat of the heat storage medium to the carbon dioxide in the gasification component.

[0038] The heat absorption circuit 132 contains a flowing heat-absorbing medium. As the heat-absorbing medium flows through the liquefaction component, it absorbs the heat released during the carbon dioxide liquefaction process, thus cooling the liquefaction component. Simultaneously, as the heat-absorbing medium flows through the multi-stream waste heat storage tank 200, it transfers heat to the storage medium. The heat release circuit 133 contains a flowing heat-releasing medium. As the heat-releasing medium flows through the multi-stream waste heat storage tank 200, it absorbs heat from the storage medium. The heated heat-releasing medium then exchanges heat with the carbon dioxide as it flows through the gasification component, accelerating the carbon dioxide gasification efficiency.

[0039] The heat-absorbing medium, heat-releasing medium, and heat-storing medium can be any one or more of water, heat transfer oil, methanol, or other medium- and low-temperature heat exchange liquids. Preferably, the specific heat capacity of the heat-absorbing medium is less than or equal to the specific heat capacity of the heat-storing medium, which in turn is less than or equal to the specific heat capacity of the heat-releasing medium. Therefore, under the same heat acquisition, the temperature rise of the heat-absorbing medium is greater than or equal to the temperature rise of the heat-storing medium, which in turn is greater than or equal to the temperature rise of the heat-releasing medium, thus making the heat transfer process more reliable. When the heat-storing medium is water, the energy storage system can also be equipped with a pressurization device for the heat-storing medium to increase its upper temperature limit.

[0040] According to a liquid carbon dioxide energy storage system based on waste heat recovery from a thermal power unit according to the present invention, the heat storage component includes a steam circuit 134 connected to the thermal power unit, the steam circuit 134 extending through a multi-stream waste heat storage tank 200; downstream of the multi-stream waste heat storage tank 200, the steam circuit 134 is provided with a condenser 135 capable of converting steam into condensate and a feedwater pump 136 capable of supplying condensate to the thermal power unit.

[0041] During operation, thermal power units release excess steam into the environment, which contains a large amount of heat energy. In the energy storage system of this invention, the steam can move along the steam circuit 134. When the steam passes through the multi-stream waste heat storage tank 200, the heat can be conducted to the heat storage medium through the pipe wall of the steam circuit 134. After cooling, the steam enters the condenser 135 and changes phase to condensate. The water pump 136 can then supply the condensate back to the thermal power unit, thereby realizing the recovery and utilization of the released steam and the waste heat in the steam.

[0042] The pipe sections of the steam circuit 134 outside the multi-stream waste heat storage tank 200 can be insulated, such as by covering the outer surface with an insulation layer, to reduce heat loss and prevent burns from the exposed steam circuit 134. The condenser 135 can be a water-cooled condenser, an air-cooled condenser, or a hybrid condenser. A water level sensor can be installed in the condenser 135 to automatically trigger the water pump 136 to start when the condensate in the condenser 135 accumulates to a certain amount. A valve can be installed on the steam circuit 134 to shut it off when waste heat recovery is not required. For example, if the temperature of the heat storage medium in the multi-stream waste heat storage tank 200 is high, continued waste heat recovery may cause the temperature of the heat storage medium to exceed the temperature of the heat absorption medium, affecting the energy storage effect of the energy storage system.

[0043] According to a liquid carbon dioxide energy storage system based on waste heat recovery from a thermal power unit, the heat storage component includes a flue gas pipeline 137 connecting the thermal power unit and the gas storage tank 101, and the flue gas pipeline 137 extends through a multi-flow waste heat storage tank 200.

[0044] During operation, thermal power units release flue gas containing a significant amount of heat energy. In the energy storage system of this invention, the flue gas can move along the flue gas pipeline 137. When the flue gas passes through the multi-flow waste heat storage tank 200, heat can be transferred to the heat storage medium through the pipe wall of the flue gas pipeline 137. The section of the flue gas pipeline 137 outside the multi-flow waste heat storage tank 200 can be insulated, such as by covering the outer surface with an insulation layer, to reduce heat loss and prevent burns from the exposed flue gas pipeline 137.

[0045] Considering that the flue gas emitted by thermal power units contains a large amount of carbon dioxide, the energy storage system of the present invention mainly uses the phase change of carbon dioxide for physical energy storage. Therefore, downstream of the multi-stream waste heat storage tank 200, the flue gas pipeline 137 is preferably equipped with a capture unit 138 that can recover gaseous carbon dioxide from the flue gas.

[0046] Specifically, the capture unit 138 can pre-treat the flue gas through denitrification, dust removal, and desulfurization to remove substances harmful to subsequent processes. Then, in the absorption tower, the composite solution reacts with the carbon dioxide in the flue gas to separate the carbon dioxide from the flue gas. Subsequently, under certain conditions, the products are decomposed in the regeneration tower to release carbon dioxide. After purification, the carbon dioxide can be sent to the storage tank 101 to replenish the energy storage medium. In addition, since the thermal power unit continuously emits flue gas, the carbon dioxide storage capacity of the energy storage system is limited. The storage tank 101 can be additionally equipped with an exhaust port capable of discharging gaseous carbon dioxide for the production of high-concentration carbon dioxide for other industrial applications.

[0047] According to a liquid carbon dioxide energy storage system based on waste heat recovery from a thermal power unit according to the present invention, the heat storage component preferably includes a water pipe extending through a multi-flow waste heat storage tank 200. One end of the water pipe is connected to a water source, and the other end is connected to a water system. The water source can be a water storage tank or a tap water pipe. The water supplied by the water source flows along the water pipe through the multi-flow waste heat storage tank 200, thereby exchanging heat between the water and the heat storage medium, and then obtaining hot water using the water system. The water system can be water facilities such as toilets, bathrooms, kitchens, and heating pipes.

[0048] Furthermore, the heat release circuit 133 is preferably a part of the water supply pipeline, that is, a part of the water in the water supply pipeline is used for the water supply system, and the other part is used as the heat release medium in the heat release circuit 133, which can form a circulation pipeline between the multi-stream waste heat storage tank 200 and the gasification component.

[0049] According to a liquid carbon dioxide energy storage system based on waste heat recovery from a thermal power unit, the liquefaction component converts gaseous carbon dioxide into liquid carbon dioxide by creating a high-pressure, low-temperature environment. For example... Figure 1 As shown, the liquefaction assembly preferably includes: a compressor 111, a cooler 112, and a throttle valve 113; the compressor 111 operates using electrical energy generated by the thermal power unit, and the cooler 112 is used to direct the heat of the gaseous carbon dioxide discharged from the compressor 111 to the heat storage assembly.

[0050] Gaseous carbon dioxide from storage tank 101 first enters compressor 111 for compression. The compressed high-temperature and high-pressure gaseous carbon dioxide enters cooler 112, where it exchanges heat with the heat absorption medium in heat storage circuit 132 of heat storage component. Finally, it passes through throttle valve 113 to generate liquid carbon dioxide.

[0051] In the aforementioned liquefaction components, the power level of the compressor 111 can be designed according to the size of the energy storage system. The compressor can be centrifugal (radial), screw, reciprocating, etc. The compressor 111 can be driven by renewable energy curtailment, surplus electricity from thermal power generation, off-peak electricity from the grid, etc. The cooler 112 can be a shell-and-tube heat exchanger, or preferably a plate heat exchanger.

[0052] According to the present invention, a liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit, the number of the compressors 111 and coolers 112 is preferably multiple, and the multiple compressors 111 and multiple coolers 112 are alternately distributed along the carbon dioxide flow direction of the liquefaction component.

[0053] For example Figure 1 As shown, there are two compressors 111 and two coolers 112. Gaseous carbon dioxide from the gas storage tank 101 first enters the first-stage compressor 111 for compression. The compressed high-temperature and high-pressure gaseous carbon dioxide enters the first-stage cooler 112, where it exchanges heat with the heat absorption medium in the heat absorption circuit 132 of the heat storage component. The cooled high-pressure gaseous carbon dioxide then passes through the second-stage compressor 111 and cooler 112 in sequence, repeating the compression and cooling steps. Finally, it passes through the throttle valve 113 to generate liquid carbon dioxide.

[0054] Through multi-stage compression and cooling, the degree of liquefaction phase change of gaseous carbon dioxide by the liquefaction component can be improved, enabling more gaseous carbon dioxide to be successfully converted into liquid carbon dioxide. On the other hand, the multi-stage cooler 112 not only increases the cooling effect on gaseous carbon dioxide, but also improves the efficiency of heat acquisition by the heat storage component.

[0055] According to the liquid carbon dioxide energy storage system based on waste heat recovery from a thermal power unit of the present invention, a gas-liquid separator 114 may also be provided between the throttle valve 113 and the storage tank 102; the gas-liquid separator 114 is used to guide the separated liquid carbon dioxide into the storage tank 102 and to transport the gaseous carbon dioxide back to the cooler 112. In practical applications, the cooler 112, the throttle valve 113 and the gas-liquid separator 114 can be configured as an integrated equipment cold box to reduce the space occupied by the pipeline.

[0056] After the liquefaction component is processed, it is often unavoidable that some carbon dioxide is not completely liquefied. At this time, the gas-liquid separator 114 is used to separate the incompletely liquefied carbon dioxide. The separated liquid carbon dioxide enters the storage tank, while the low-temperature gaseous carbon dioxide can be transferred to the cooler 112 again for cooling through a transmission pipeline provided between the gas-liquid separator 114 and any cooler 112.

[0057] According to a liquid carbon dioxide energy storage system based on waste heat recovery from a thermal power unit according to the present invention, the gasification component includes a booster pump 121, a heater 122, and an expander 123; the heater 122 is used to absorb heat provided by the heat storage component to heat the gaseous or liquid carbon dioxide passing through the heater 122; during the heating and gasification process, the carbon dioxide does work in the expander 123, and the expander 123 can be connected to a generator to drive the generator to generate electricity.

[0058] The liquid carbon dioxide in the storage tank 102 is pressurized by the booster pump 121 and directed to the heater 122. The heater 122 heats the liquid carbon dioxide to vaporize it. The high-pressure carbon dioxide after vaporization is expanded by the expander 123 to do work, thereby driving the generator associated with the expander 123 to produce electrical energy.

[0059] In the aforementioned vaporization components, the power level of the expander 123 can be designed according to the size of the energy storage system. The expander 123 can be centrifugal (radial), screw, piston, etc. The heater 122 can be a conventional vaporizer, preferably a shell-and-tube heat exchanger.

[0060] According to the present invention, a liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit is provided, wherein the number of heaters 122 and expanders 123 is preferably multiple, and the multiple heaters 122 and multiple expanders 123 are alternately distributed along the carbon dioxide flow direction of the gasification component.

[0061] For example Figure 1 As shown, there are two heaters 122 and two expanders 123. Liquid carbon dioxide from the storage tank 102 first enters the first-stage heater 122 for heating. The carbon dioxide that is not fully vaporized enters the first-stage expander 123, where it expands and does work. Then it passes through the second-stage heater 122 and expander 123 in sequence, and repeats the heating and work steps to fully convert it into gaseous carbon dioxide.

[0062] The liquid carbon dioxide in the storage tank 102 is pressurized by the booster pump 121 and directed to the heater 122. The heater 122 heats the liquid carbon dioxide to vaporize it. The high-pressure carbon dioxide after vaporization is expanded by the expander 123 to do work, thereby driving the generator associated with the expander 123 to produce electrical energy.

[0063] According to a liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit according to the present invention, a buffer tank 103 is preferably provided between the expander 123 and the gas storage tank 101. The buffer tank 103 is used to slow down the flow rate of gaseous carbon dioxide before it enters the gas storage tank 101, prevent large pressure fluctuations in the gas storage tank 101, and improve the stability of the system.

[0064] According to the liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units described above, the energy storage system captures carbon dioxide from the flue gas of thermal power units and introduces it into a compressed carbon dioxide energy storage system. This system offers advantages such as high energy density and small footprint, effectively reducing carbon emissions from thermal power units, increasing their peak-shaving capacity, and allowing renewable energy generation to drive the energy storage system, thus reducing the risks associated with grid connection of renewable energy generation. Furthermore, a multi-stream waste heat storage tank 200 recovers waste heat from flue gas and steam, as well as the compression heat from the compressor 111, for carbon dioxide vaporization during energy release and for heating the carbon dioxide at the expander inlet. In cases of excess heat, hot water can also be supplied to the outside, reducing heat loss and significantly improving the overall efficiency of the energy storage system.

[0065] The aforementioned technical effects rely on the heat storage components for the conduction and recovery of heat from various parts of the energy storage system. As an important component of the heat storage components, this invention also provides a multi-stream waste heat storage tank for use in energy storage systems. The following is in conjunction with... Figure 2 The specific implementation of the multi-stream waste heat storage tank provided by the present invention is described below. The multi-stream waste heat storage tank described below can be referred to in correspondence with the liquid carbon dioxide energy storage system based on waste heat recovery of thermal power units described above.

[0066] According to the present invention, a multi-stream waste heat storage tank is used in a liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units. The energy storage system can liquefy gaseous carbon dioxide into liquid carbon dioxide by consuming the electrical energy generated by the thermal power unit for energy storage, and can use the expansion of carbon dioxide to drive a generator to produce stable electrical energy during the process of liquid carbon dioxide being vaporized into gaseous carbon dioxide.

[0067] like Figure 2 As shown, the multi-stream waste heat storage tank includes a tank body 210, with an inner cavity 211 for containing a heat storage medium. The inner cavity 211 is equipped with a first heat exchange section 220, a second heat exchange section 230, and a waste heat recovery section. The first heat exchange section 220 carries an endothermic medium that absorbs the heat released during carbon dioxide liquefaction and exchanges heat with the heat storage medium within the first heat exchange section 220. The second heat exchange section 230 carries an exothermic medium that absorbs heat from the heat storage medium within the second heat exchange section 230 and raises the temperature of the gaseous or liquid carbon dioxide during its vaporization. The exhaust path of the thermal power unit extends through the waste heat recovery section so that the flue gas and / or steam discharged from the thermal power unit exchanges heat with the heat storage medium within the waste heat recovery section.

[0068] The tank body 210 is preferably made of metal, and different thicknesses can be used depending on the actual pressure resistance requirements. The heat storage medium can be heat transfer oil, or water, methanol, or other medium- and low-temperature heat storage media, but the internal pressure of the multi-stream waste heat storage tank needs to be adjusted to meet the heat storage temperature. The inlet and outlet of each pipeline connected to the tank body 210 are preferably connected by flanges. Valves can be added for control switches, or sensors, instruments, and other monitoring devices can be added to monitor the flow rate, temperature, pressure, and other parameters of each medium in real time, thereby improving safety.

[0069] According to a multi-stream waste heat storage tank of the present invention, the waste heat recovery section includes a steam coil 241; the inlet of the steam coil 241 is connected to the steam discharge port of the thermal power unit.

[0070] At least a portion of the high-temperature steam emitted from the thermal power unit enters the inlet of steam coil 241. Through heat conduction via the coil wall, the heat of the high-temperature steam is transferred to the heat storage medium, raising its temperature. The steam then exits from the outlet of steam coil 241. The outlet of steam coil 241 is preferably connected to, for example... Figure 1 The condenser 135 shown is used to convert steam into condensate and supply the condensate to the thermal power unit.

[0071] According to a multi-flow waste heat storage tank of the present invention, the waste heat recovery section includes a flue gas coil 242; the inlet of the flue gas coil 242 is connected to the flue gas discharge port of the thermal power unit.

[0072] At least a portion of the high-temperature flue gas emitted from the thermal power unit enters through the inlet of the flue gas coil 242. Within the flue gas coil 242, the heat from the flue gas is conducted to the heat storage medium through the tube wall, raising the temperature of the heat storage medium. The flue gas is then discharged from the outlet of the flue gas coil 242. The outlet of the flue gas coil 242 is preferably connected to... Figure 1 The capture unit 138 shown is used to recover gaseous carbon dioxide from flue gas.

[0073] According to a multi-flow waste heat storage tank of the present invention, a first heat exchange section 220 is provided with a cooling coil 221 for flowing heat-absorbing medium, and the heat-absorbing medium exchanges heat with the heat storage medium through the tube wall of the cooling coil 221; and / or a second heat exchange section 230 is provided with a heating coil 231 for flowing heat-releasing medium, and the heat-releasing medium exchanges heat with the heat storage medium through the tube wall of the heating coil 231.

[0074] In a liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units, the compressor 111 of the liquefaction component generates heat during the compression of gaseous carbon dioxide. After the heat-absorbing medium exchanges heat with the high-temperature and high-pressure gaseous carbon dioxide in the liquefaction component, the heat-absorbing medium can transfer the obtained heat to the heat storage medium in the cooling coil 221, so as to raise the temperature of the heat storage medium and realize the recovery of the heat generated during the compression of gaseous carbon dioxide.

[0075] After recovering the waste heat from the flue gas and steam of the thermal power unit and the compression heat from the energy storage system, the heat storage medium can transfer the heat to the heat medium in the heating coil 231, so that the heating medium can provide heat to the outside. The cooling coil 221, heating coil 231, steam coil 241 and flue gas coil 242 are preferably made of the same or different metal materials with good thermal conductivity, and steel coils are preferred.

[0076] According to a multi-flow waste heat storage tank of the present invention, a plurality of heat-conducting fins are preferably fixed on the outer surface of the cooling coil 221 and / or the heating coil 231. The heat-conducting fins can be made of the same heat-conducting metal material as the cooling coil 221 and / or the heating coil 231, such as steel fins. The heat-conducting fins can increase the heat exchange area between the cooling coil 221 and / or the heating coil 231 and the heat storage medium, thereby improving the heat exchange efficiency.

[0077] According to a multi-stream waste heat storage tank of the present invention, the heat release medium is preferably water, and the second heat exchange section 230 includes a water pipe, one end of which is connected to a water source and the other end of which is connected to a water system.

[0078] Furthermore, the heating coil 231 and the water supply line can be connected in parallel. Alternatively, preferably, the heating coil 231 is part of the water supply line, such as... Figure 2 As shown, a water softening tank 232 capable of softening water is installed upstream of the heating coil 231 in the water supply pipeline. The inlet of the water softening tank 232 can be selectively connected to a water source or the outlet of the heating coil 231, and the outlet of the heating coil 231 can be selectively connected to the inlet of the water softening tank 232 or the water supply system. According to this preferred configuration, a portion of the hot water in the water supply pipeline can be used in the aforementioned water supply system, while another portion can serve as the heat release medium in the heat release circuit 133, forming a circulating heat release pipeline between the tank 210 and the vaporization assembly.

[0079] According to a multi-stream waste heat storage tank of the present invention, the tank body 210 has a heat storage medium inlet 212 and a heat storage medium outlet 213 that can be opened and closed.

[0080] Preferably, the heat storage medium inlet 212 and the heat storage medium outlet 213 are each equipped with a switchable valve. When the heat storage medium is insufficient, it can be injected into the inner cavity 211 through the heat storage medium inlet 212. When the pressure in the inner cavity 211 of the multi-flow waste heat storage tank is too high, the heat storage medium outlet 213 can be opened to discharge the heat storage medium and release the pressure. When the heat storage medium needs to be replaced, new heat storage medium can be injected and old heat storage medium can be discharged through the heat storage medium inlet 212 and the heat storage medium outlet 213, respectively.

[0081] Preferably, the heat storage medium inlet 212 and the heat storage medium outlet 213 can be connected to the same heat storage medium circulation loop. During the operation of the energy storage system, the heat storage medium in the circulation loop flows, thereby driving the heat storage medium in the inner cavity 211 to maintain a flowing state, which can slow down the heating rate of the heat storage medium and prevent the heat storage medium from heating up too quickly.

[0082] According to a multi-flow waste heat storage tank of the present invention, a stirrer 214 is preferably further provided in the inner cavity 211, such as... Figure 2 As shown, the agitator 214 can consume electrical energy generated by the thermal power unit, or be driven by renewable energy waste, surplus electricity from thermal power generation, off-peak electricity from the grid, etc., to agitate the heat storage medium in the inner cavity 211, thereby keeping the heat storage medium in a flowing state in the inner cavity 211 so that the heat is always evenly distributed. The agitator 214 can adopt a propeller type, turbine type, anchor type, or other structural forms.

[0083] According to a multi-flow waste heat storage tank of the present invention, the outer surface of the tank body 210 and / or the inner wall surface of the inner cavity 211 are covered with an insulation layer to reduce heat loss due to heat storage. The insulation layer material can be glass wool, rock wool, aerogel felt, expanded perlite, and foamed cement, etc.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units, characterized in that, include: Gas storage tank (101) is used to store gaseous carbon dioxide; Storage tank (102) is used to store liquid carbon dioxide; The liquefaction component is able to use the electrical energy provided by the thermal power unit to obtain gaseous carbon dioxide from the gas storage tank (101) and convert it into liquid carbon dioxide and inject it into the liquid storage tank (102); The vaporization component is capable of obtaining liquid carbon dioxide from the liquid storage tank (102) and converting it into gaseous carbon dioxide, which is then injected into the gas storage tank (101). A heat storage component is used to absorb the heat released by the thermal power unit and the heat released during the carbon dioxide liquefaction process, and can provide the heat to the gasification component to raise the temperature of the gaseous or liquid carbon dioxide in the gasification component. The heat storage component includes a multi-stream waste heat storage tank (200), which includes a tank body (210). The inner cavity (211) of the tank body (210) is used to contain the heat storage medium. The inner cavity (211) is provided with a first heat exchange section (220), a second heat exchange section (230), and a waste heat recovery section. The waste heat recovery section includes a steam coil (241) and a flue gas coil (242). The inlet of the steam coil (241) is connected to the steam outlet of the thermal power unit. The inlet of the flue gas coil (242) is connected to the flue gas outlet of the thermal power unit.

2. The liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units according to claim 1, characterized in that, The heat storage component includes a heat absorption circuit (132) and a heat release circuit (133). The heat absorption circuit (132) extends through the multi-stream waste heat storage tank (200) and the liquefaction component to absorb the heat released during the carbon dioxide liquefaction process and raise the temperature of the heat storage medium in the multi-stream waste heat storage tank (200). The heat release circuit (133) extends through the multi-stream waste heat storage tank (200) and the gasification assembly to direct the heat of the heat storage medium to carbon dioxide in the gasification assembly.

3. The liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units according to claim 2, characterized in that, The heat storage component includes a steam circuit (134) connected to the thermal power unit, the steam circuit (134) extending through the multi-stream waste heat storage tank (200); Downstream of the multi-stream waste heat storage tank (200), the steam circuit (134) is equipped with a condenser (135) capable of converting steam into condensate and a feedwater pump (136) capable of supplying the condensate to the thermal power unit.

4. The liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units according to claim 2, characterized in that, The heat storage component includes a flue gas pipeline (137) connecting the thermal power unit and the gas storage tank (101), and the flue gas pipeline (137) extends through the multi-flow waste heat storage tank (200); Downstream of the multi-stream waste heat storage tank (200), the flue gas pipeline (137) is equipped with a capture unit (138) capable of recovering gaseous carbon dioxide from the flue gas.

5. The liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units according to any one of claims 1-4, characterized in that, The liquefaction assembly includes: a compressor (111), a cooler (112), and a throttle valve (113). The compressor (111) operates using electrical energy generated by the thermal power unit, and the cooler (112) is used to direct the heat from the gaseous carbon dioxide discharged from the compressor (111) to the heat storage component.

6. The liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units according to claim 5, characterized in that, The number of compressors (111) and coolers (112) is multiple, and the multiple compressors (111) and multiple coolers (112) are alternately distributed along the carbon dioxide flow direction of the liquefaction component.

7. The liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units according to claim 5, characterized in that, A gas-liquid separator (114) is provided between the throttle valve (113) and the liquid storage tank (102). The gas-liquid separator (114) is used to introduce the separated liquid carbon dioxide into the storage tank (102) and to transport the gaseous carbon dioxide back to the cooler (112).

8. The liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units according to any one of claims 1-4, characterized in that, The gasification assembly includes a booster pump (121), a heater (122), and an expander (123). The heater (122) is used to absorb the heat provided by the heat storage component to heat the gaseous or liquid carbon dioxide passing through the heater (122); During the heating and vaporization process, carbon dioxide does work in the expander (123) to drive the generator to generate electricity.

9. The liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units according to claim 8, characterized in that, The number of heaters (122) and expanders (123) is multiple, and the multiple heaters (122) and multiple expanders (123) are alternately distributed along the carbon dioxide flow direction of the gasification assembly.

10. The liquid carbon dioxide energy storage system based on waste heat recovery from thermal power units according to claim 8, characterized in that, A buffer tank (103) is provided between the expander (123) and the gas storage tank (101). The buffer tank (103) is used to slow down the flow rate of gaseous carbon dioxide before it enters the gas storage tank (101).

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