Multi-stream waste heat storage tank

Abstract

The application provides a multi-branch waste heat storage tank, which comprises a tank body, an inner cavity of the tank body is used for containing a heat storage medium, a first heat exchange part, a second heat exchange part and a waste heat recovery part are arranged in the inner cavity, the first heat exchange part is in flow communication with a heat absorption medium, the heat absorption medium is used for absorbing heat released in a carbon dioxide liquefaction process and exchanges heat with the heat storage medium in the first heat exchange part, the second heat exchange part is in flow communication with a heat release medium, the heat release medium is used for absorbing heat in the heat storage medium in the second heat exchange part and heating gaseous or liquid carbon dioxide in a carbon dioxide gasification process, and an exhaust path of a thermal power generating unit extends through the waste heat recovery part so that flue gas and / or steam discharged from the thermal power generating unit exchanges heat with the heat storage medium in the waste heat recovery part. The multi-branch waste heat storage tank is applied to a liquid carbon dioxide energy storage system based on waste heat recovery of the thermal power generating unit, and energy utilization efficiency can be improved through recovery and utilization of waste heat of the thermal power generating unit.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of physical energy storage, in particular to a multi-stream waste heat storage tank for a liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power generating unit. BACKGROUND

[0002] Advanced methods for improving energy utilization have become a top priority for global attention. For a large energy producer and consumer like China, there is a demand for energy saving and emission reduction, and there is a need for energy growth to support economic development, which requires the development of energy storage industry.

[0003] Thermal power generation is the main method of producing electric energy in China and many countries in the world. The process of thermal power generation includes: heating water to generate steam when fuel is burned, converting the chemical energy of fuel into heat energy, steam pressure driving the turbine to rotate, converting heat energy into mechanical energy, and then the turbine drives the generator to rotate, converting mechanical energy into electric energy.

[0004] At the present stage, the main physical energy storage methods include using pumping, compressed air, flywheel and other physical methods to realize energy storage, which has the advantages of environmental protection and green, and therefore is more widely used. However, in the process of thermal power generation, in addition to the generated electric energy, a large amount of heat energy is also lost in the exhaust process of the thermal power generating unit. The conventional physical energy storage method often only converts and stores the electric energy generated by thermal power generation through a single energy conversion means, ignoring the heat energy loss of the thermal power generating unit, resulting in low energy utilization. SUMMARY

[0005] The present application provides a multi-stream waste heat storage tank for a liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power generating unit, which solves the problem of low energy utilization in the process of thermal power energy storage in the prior art, and realizes an energy storage scheme that can improve the energy utilization of the thermal power generating unit.

[0006] The application provides a multi-branch waste heat storage tank for a liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit, which can liquefy gaseous carbon dioxide into liquid carbon dioxide to store energy by consuming electric energy generated by the thermal power unit, and can drive a generator to generate stable electric energy by using expansion work of carbon dioxide during gasification of liquid carbon dioxide into gaseous carbon dioxide; the multi-branch waste heat storage tank comprises a tank body, an inner cavity of the tank body is used for containing a heat storage medium; a first heat exchange part, a second heat exchange part and a waste heat recovery part are arranged in the inner cavity; a heat absorption medium is circulated in the first heat exchange part, the heat absorption medium is used for absorbing heat released during liquefaction of carbon dioxide and exchanges heat with the heat storage medium in the first heat exchange part; a heat release medium is circulated in the second heat exchange part, the heat release medium is used for absorbing heat in the heat storage medium in the second heat exchange part and warming gaseous or liquid carbon dioxide during gasification of liquid carbon dioxide; an exhaust path of the thermal power unit extends through the waste heat recovery part, so that flue gas and / or steam discharged by the thermal power unit exchanges heat with the heat storage medium in the waste heat recovery part.

[0007] According to the multi-branch waste heat storage tank provided by the application, the waste heat recovery part comprises a steam coil; an inlet of the steam coil is communicated with a steam discharge port of the thermal power unit, and an outlet of the steam coil is communicated with a condenser, which is used for phase changing steam into condensed water and supplying the condensed water to the thermal power unit.

[0008] According to the multi-branch waste heat storage tank provided by the application, the waste heat recovery part comprises a flue gas coil; an inlet of the flue gas coil is communicated with a flue gas discharge port of the thermal power unit, and an outlet of the flue gas coil is communicated with a capture unit, which is used for recovering gaseous carbon dioxide in flue gas.

[0009] According to the multi-branch waste heat storage tank provided by the application, the first heat exchange part is provided with a cooling coil for circulating the heat absorption medium, and the heat absorption medium exchanges heat with the heat storage medium through a tube wall of the cooling coil; and / or the second heat exchange part is provided with a heating coil for circulating the heat release medium, and the heat release medium exchanges heat with the heat storage medium through a tube wall of the heating coil.

[0010] According to the multi-branch waste heat storage tank provided by the application, a plurality of heat conduction fins are fixed on an outer surface of the cooling coil and / or the heating coil.

[0011] According to the multi-branch waste heat storage tank provided by the application, the heat release medium is water, and the second heat exchange part comprises a water pipeline, one end of the water pipeline is communicated with a water source, and the other end of the water pipeline is communicated with a water using system.

[0012] According to the multi-branch waste heat storage tank provided by the application, the heating coil is arranged in parallel with the water pipeline; or the heating coil is part of the water pipeline, the water pipeline is provided with a softened water tank capable of softening water quality upstream of the heating coil, the inlet of the softened water tank is selectively communicated with the water source or the outlet of the heating coil, and the outlet of the heating coil is selectively communicated with the inlet of the softened water tank or the water using system.

[0013] According to the multi-branch waste heat storage tank provided by the application, the tank body is provided with an openable and closable heat storage medium inlet and heat storage medium outlet.

[0014] According to the multi-branch waste heat storage tank provided by the application, the inner cavity is provided with a stirrer capable of stirring the heat storage medium in the inner cavity.

[0015] According to the multi-branch waste heat storage tank provided by the application, the outer surface of the tank body and / or the inner wall surface of the inner cavity is covered with a heat preservation layer.

[0016] The multi-branch waste heat storage tank provided by the application can absorb the heat released in the carbon dioxide liquefaction process by the heat absorbing medium, exchange heat with the heat storage medium in the first heat exchange part, recover the waste heat in the flue gas and / or steam discharged by the thermal power generating unit to the heat storage medium through the waste heat recovery part, absorb the heat in the heat storage medium in the second heat exchange part through the heat releasing medium, and warm the gaseous or liquid carbon dioxide in the carbon dioxide gasification process. The application of the multi-branch waste heat storage tank to the liquid carbon dioxide energy storage system of the thermal power generating unit can improve the energy release efficiency of the energy storage system and improve the energy utilization rate of the energy storage system to the thermal power generating unit. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0018] Figure 1 is a structural block diagram of the liquid carbon dioxide energy storage system based on waste heat recovery of the thermal power generating unit provided by the application;

[0019] Figure 2 is a structural block diagram of the multi-branch waste heat storage tank of the liquid carbon dioxide energy storage system based on waste heat recovery of the thermal power generating unit provided by the application.

[0020] Reference signs:

[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 with 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 1 As 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 further comprises a steam loop 134 and a flue gas pipeline 137. At least part of the steam discharged by the thermal power unit passes through the inside of the multi-stream waste heat storage tank 200 along the steam loop 134, so that the heat storage medium absorbs the waste heat in the steam, and the cooled steam forms condensed water in the condenser, which can be supplied back to the thermal power unit, reducing the waste of water resources of the thermal power unit. At least part of the flue gas discharged by the thermal power unit passes through the inside of the multi-stream waste heat storage tank 200 along the flue gas pipeline 137, so that the heat storage medium absorbs the waste heat in the flue gas, and the cooled flue gas enters the capture unit 138 to capture and recover carbon dioxide in the flue gas. The recovered carbon dioxide can be injected into the gas storage tank 101 for carbon dioxide circulation of the energy storage system, thereby not only obtaining a supplementary source of carbon dioxide, but also alleviating the carbon emission problem of the thermal power unit.

[0031] As shown in Figure 1 The liquid storage tank 102 can be additionally provided with an outlet for discharging liquid carbon dioxide. Thus, when the carbon dioxide content in the system is too high, the liquid carbon dioxide is discharged to maintain the balance of the system; or when additional physical energy storage is needed, the liquid carbon dioxide is exported and stored in other containers; or as liquid carbon dioxide output for application in other industrial production.

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

[0033] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in combination with the drawings of the specification and various specific embodiments of the present application.

[0034] According to the liquid carbon dioxide energy storage system based on waste heat recovery of the thermal power unit of the present application, it comprises: a gas storage tank 101 for storing gaseous carbon dioxide; a liquid storage tank 102 for storing liquid carbon dioxide; a liquefaction assembly capable of obtaining gaseous carbon dioxide from the gas storage tank 101 and converting it into liquid carbon dioxide and injecting it into the liquid storage tank 102 using the electric energy provided by the thermal power unit; and a gasification assembly capable of obtaining liquid carbon dioxide from the liquid storage tank 102 and converting it into gaseous carbon dioxide and injecting it into the gas storage tank 101. The liquefaction assembly converts the gaseous carbon dioxide stored in the gas storage tank 101 into liquid carbon dioxide using the electric energy generated by the thermal power unit and injects it into the liquid storage tank 102, thereby realizing physical energy storage of the electric energy generated by the thermal power unit. When physical energy storage needs to be released, the liquid carbon dioxide in the liquid storage tank 102 is converted into gaseous carbon dioxide by the gasification assembly, which can be combined with a power generation device to generate electric energy using the energy released during the carbon dioxide gasification phase change.

[0035] The liquid storage tank 102 is preferably a steel pressure container with heat preservation device to maintain a low temperature environment inside. The gas storage tank 101 can be a steel spherical tank or a container with air bag.

[0036] The energy storage system further comprises a heat storage assembly for absorbing heat released by the thermal power unit and heat released during the carbon dioxide liquefaction process, and capable of providing heat to the gasification assembly to warm up the gaseous or liquid carbon dioxide in the gasification assembly. The heat storage assembly can recover waste heat of the thermal power unit (such as heat in the discharged flue gas and steam) and heat released during the carbon dioxide liquefaction process, and when physical energy storage needs to be released, the heat obtained by the heat storage assembly is used to heat the carbon dioxide in the gasification process, which not only improves the energy release efficiency of the energy storage system, but also improves the energy utilization rate of the thermal power unit by the energy storage system.

[0037] According to the liquid carbon dioxide energy storage system based on waste heat recovery of the thermal power unit, the heat storage assembly comprises 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 assembly to absorb heat released during the carbon dioxide liquefaction process to warm up 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 guide the heat of the heat storage medium to the carbon dioxide in the gasification assembly.

[0038] The heat absorption circuit 132 has a heat absorption medium flowing therein, and the heat absorption medium absorbs heat released during the carbon dioxide liquefaction process when flowing through the liquefaction assembly, i.e. the liquefaction assembly is cooled, and the heat absorption medium can transfer heat to the heat storage medium when flowing through the multi-stream waste heat storage tank 200. The heat release circuit 133 has a heat release medium flowing therein, and the heat release medium obtains heat from the heat storage medium when flowing through the multi-stream waste heat storage tank 200, and the heated heat release medium exchanges heat with the carbon dioxide when flowing through the gasification assembly to accelerate the gasification efficiency of the carbon dioxide.

[0039] The heat absorption medium, the heat release medium and the heat storage medium can be any one or more of water, heat conducting oil, methanol and other medium and low temperature heat exchange liquid working substances. Preferably, the specific heat capacity of the heat absorption medium is less than or equal to the specific heat capacity of the heat storage medium, which is less than or equal to the specific heat capacity of the heat release medium, so that the temperature rise of the heat absorption medium is greater than or equal to the temperature rise of the heat storage medium, which is greater than or equal to the temperature rise of the heat release medium under the same heat acquisition, and the heat transfer process is more reliable. When the heat storage medium is water, the energy storage system can further be provided with a pressurizing device for the heat storage medium to increase the upper limit of its temperature.

[0040] According to the liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit of the present application, the heat storage assembly comprises a steam circuit 134 connected to the thermal power unit and 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 provided with a condenser 135 capable of phase changing steam into condensed water and a feed water pump 136 capable of supplying the condensed water to the thermal power unit.

[0041] During the operation of the thermal power unit, excess steam is discharged to the outside, and the discharged steam contains a large amount of heat energy. In the energy storage system of the present application, steam can move along the steam circuit 134. When the steam passes through the multi-stream waste heat storage tank 200, heat can be transferred to the heat storage medium through the pipe wall of the steam circuit 134, and the cooled steam is phase changed into condensed water in the condenser 135, and the water pump 136 can provide the condensed water to the thermal power unit again, thereby realizing the recovery and utilization of the discharged steam and the waste heat in the steam.

[0042] The pipe section of the steam circuit 134 outside the multi-stream waste heat storage tank 200 can be heat insulated, such as being coated with a heat preservation layer on the outer surface, to reduce heat loss and prevent the naked steam circuit 134 from scalding personnel. The condenser 135 can be a water-cooled condenser or an air-cooled condenser or a hybrid condenser. A water level sensing device can be arranged in the condenser 135, and when the condensed water in the condenser 135 accumulates to a certain amount, the water pump 136 is automatically triggered to start. Valves can be arranged on the steam circuit 134 to shut off the steam circuit 134 when the steam waste heat does not need to be recovered. For example, when the temperature of the heat storage medium in the multi-stream waste heat storage tank 200 is relatively high, continuing to recover the steam waste heat may cause the temperature of the heat storage medium to exceed the temperature of the heat absorbing medium, affecting the energy storage effect of the energy storage system.

[0043] According to the liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit of the present application, the heat storage assembly comprises a flue gas pipeline 137 connected between the thermal power unit and the gas storage tank 101, and the flue gas pipeline 137 extends through the multi-stream waste heat storage tank 200.

[0044] During the operation of the thermal power unit, flue gas is discharged to the outside, and the discharged flue gas contains a large amount of heat energy. In the energy storage system of the present application, flue gas can move along the flue gas pipeline 137. When the flue gas passes through the multi-stream 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 pipe section of the flue gas pipeline 137 outside the multi-stream waste heat storage tank 200 can be heat insulated, such as being coated with a heat preservation layer on the outer surface, to reduce heat loss and prevent the naked flue gas pipeline 137 from scalding personnel.

[0045] In view of the fact that the flue gas emitted by the thermal power generating unit contains a large amount of carbon dioxide, the energy storage system of the present application mainly performs physical energy storage through phase change of carbon dioxide, and therefore, the flue gas pipeline 137 is preferably provided with a capture unit 138 capable of recovering gaseous carbon dioxide in the flue gas at a position downstream of the multi-stream waste heat storage tank 200.

[0046] Specifically, the capture unit 138 can perform pretreatment such as denitration, dust removal, desulfurization, etc. on the flue gas to remove harmful substances in the flue gas, and then the carbon dioxide in the flue gas is separated from the flue gas by reaction of the absorbent solution in the absorption tower with the carbon dioxide in the flue gas; thereafter, the product is decomposed in the regeneration tower under certain conditions, thereby releasing carbon dioxide, which can be sent to the gas storage tank 101 after purification treatment to supplement the energy storage medium. In addition, since the thermal power generating unit continuously emits flue gas, the storage capacity of carbon dioxide in the energy storage system is limited, and the gas storage tank 101 can be additionally provided with a discharge port capable of discharging gaseous carbon dioxide to produce high-concentration carbon dioxide for other industrial applications.

[0047] According to the liquid carbon dioxide energy storage system based on waste heat recovery of the thermal power generating unit of the present application, the heat storage assembly preferably comprises a water pipeline extending through the multi-stream waste heat storage tank 200, one end of the water pipeline being connected to a water source and the other end being connected to a water using system. The water source can be a water storage tank or a tap water pipeline, and the water provided by the water source flows through the multi-stream waste heat storage tank 200 along the water pipeline, so that the water exchanges heat with the heat storage medium, and hot water is obtained by using the water using system. The water using system can be a water using facility such as a bathroom, a bathroom, a kitchen, a heating pipeline, etc.

[0048] Further, the heat release circuit 133 is preferably a part of the above-mentioned water pipeline, i.e. a part of the water in the water pipeline is used for the above-mentioned water using system, and the other part serves as a heat release medium in the heat release circuit 133, and a circulating pipeline can be formed between the multi-stream waste heat storage tank 200 and the gasification assembly.

[0049] According to the liquid carbon dioxide energy storage system based on waste heat recovery of the thermal power generating unit of the present application, the liquefaction assembly converts gaseous carbon dioxide into liquid carbon dioxide by creating a high-pressure and low-temperature environment. Figure 1 As shown in FIG. 1, the liquefaction assembly preferably comprises a compressor 111, a cooler 112 and a throttle valve 113; the compressor 111 is operated by using the electric energy generated by the thermal power generating unit, and the cooler 112 is used to guide the heat of the gaseous carbon dioxide discharged from the compressor 111 to the heat storage assembly.

[0050] The gaseous carbon dioxide from the gas storage tank 101 first enters the compressor 111 for compression, the high-temperature and high-pressure gaseous carbon dioxide after compression enters the cooler 112, exchanges heat with the heat absorbing medium in the heat absorbing circuit 132 of the heat storage assembly in the cooler 112, and finally passes through the throttle valve 113 to generate liquid carbon dioxide.

[0051] The power level of the compressor 111 can be designed according to the size of the energy storage system. The compressor 111 can be centrifugal, screw, piston, etc. The compressor 111 can be driven by renewable energy, thermal power generation, and grid valley electricity. The cooler 112 can be a double-pipe heat exchanger, or preferably a plate heat exchanger.

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

[0053] For example Figure 1 As shown, the number of compressors 111 and coolers 112 is two respectively. The gaseous carbon dioxide from the gas tank 101 first enters the first-stage compressor 111 for compression. The high-temperature and high-pressure gaseous carbon dioxide after compression enters the first-stage cooler 112 for heat exchange with the heat-absorbing medium in the heat-absorbing circuit 132 of the heat storage assembly. The high-pressure gaseous carbon dioxide after cooling successively passes through the second-stage compressor 111 and cooler 112, and repeats the compression and cooling steps. Finally, the throttling valve 113 generates liquid carbon dioxide.

[0054] After multi-stage compression and cooling, the liquefaction assembly can improve the degree of phase change of gaseous carbon dioxide to liquid carbon dioxide, so that more gaseous carbon dioxide can be smoothly converted into liquid carbon dioxide. On the other hand, the multi-stage coolers 112 not only increase the cooling effect of gaseous carbon dioxide, but also improve the efficiency of heat absorption of the heat storage assembly.

[0055] According to the liquid carbon dioxide energy storage system based on waste heat recovery of thermal power generating units, a gas-liquid separator 114 can be further arranged between the throttling valve 113 and the liquid storage tank 102. The gas-liquid separator 114 is used to guide the separated liquid carbon dioxide into the liquid storage tank 102, and to transport gaseous carbon dioxide back to the cooler 112. In actual application, the cooler 112, the throttling valve 113, and the gas-liquid separator 114 can be set as an integrated equipment cold box to reduce the space occupation of the pipeline.

[0056] After the liquefaction assembly, part of the carbon dioxide cannot be completely liquefied, at which time the gas-liquid separator 114 is used to separate the carbon dioxide that is not completely liquefied. The separated liquid carbon dioxide enters the liquid storage tank, and the low-temperature gaseous carbon dioxide can be transported to the cooler 112 again through the transmission pipeline arranged between the gas-liquid separator 114 and any cooler 112.

[0057] According to the liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit, the gasification assembly comprises a booster pump 121, a heater 122 and an expander 123; the heater 122 is used for absorbing heat provided by the heat storage assembly to heat gaseous or liquid carbon dioxide passing through the heater 122; the carbon dioxide is expanded in the expander 123 to do work in the process of heating and gasification, and the expander 123 can be connected with a generator to drive the generator to generate electricity through the expander 123.

[0058] The liquid carbon dioxide in the liquid storage tank 102 is pressurized by the booster pump 121 and guided to the heater 122, the heater 122 heats the liquid carbon dioxide to make it gasify, the high-pressure carbon dioxide after gasification is expanded in the expander 123 to do work, and then drives the generator associated with the expander 123 to generate electric energy.

[0059] In the above gasification assembly, the power level of the expander 123 can be designed according to the size of the energy storage system, and the expander 123 can be a centrifugal (centripetal) type, a screw type or a piston type. The heater 122 can be a conventional vaporizer, and is preferably a tube-shell heat exchanger.

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

[0061] For example Figure 1 As shown in the figure, the number of the heater 122 and the expander 123 is two respectively, the liquid carbon dioxide from the liquid storage tank 102 first enters the first-stage heater 122 to be heated, the carbon dioxide not fully gasified enters the first-stage expander 123 to do work in the first-stage expander 123, and then sequentially passes through the second-stage heater 122 and the second-stage expander 123, and the steps of heating and doing work are repeated to fully convert into gaseous carbon dioxide.

[0062] The liquid carbon dioxide in the liquid storage tank 102 is pressurized by the booster pump 121 and guided to the heater 122, the heater 122 heats the liquid carbon dioxide to make it gasify, the high-pressure carbon dioxide after gasification is expanded in the expander 123 to do work, and then drives the generator associated with the expander 123 to generate electric energy.

[0063] According to the liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit, a buffer tank 103 is preferably arranged between the expander 123 and the gas storage tank 101, the buffer tank 103 is used for slowing down the flow rate of gaseous carbon dioxide before the gaseous carbon dioxide enters the gas storage tank 101, preventing large pressure fluctuations in the gas storage tank 101, and improving the stability of the system.

[0064] The liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit according to the foregoing of the present application. The energy storage system captures carbon dioxide in flue gas of the thermal power unit and introduces the carbon dioxide into the carbon dioxide energy storage system, has the advantages of high energy storage density and small equipment footprint, effectively reduces carbon emissions of the thermal power unit, increases peak shaving capacity of the thermal power unit, and simultaneously can utilize renewable energy power generation to drive the energy storage system, reduces renewable energy power generation grid connection risk. In addition, the multi-stream waste heat storage tank 200 is adopted to recover flue gas and steam waste heat, and the compressor 111 compression heat is used for carbon dioxide gasification and carbon dioxide heating at an inlet of an expander in the energy releasing process, and in the case of heat surplus, hot water can also be delivered to the outside, reducing heat loss and greatly improving overall efficiency of the energy storage system.

[0065] To achieve the above technical effects, the heat conduction and recovery of the heat storage assembly to each part of the energy storage system are relied on. As an important component of the heat storage assembly, the present application further provides a multi-stream waste heat storage tank applied to the energy storage system. The specific implementation of the multi-stream waste heat storage tank provided by the present application is described below, and the multi-stream waste heat storage tank described below can be correspondingly referred to the liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit described above. Figure 2 The specific implementation of the multi-stream waste heat storage tank provided by the present application is described below, and the multi-stream waste heat storage tank described below can be correspondingly referred to the liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit described above.

[0066] The multi-stream waste heat storage tank according to the present application is used in the liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit. The energy storage system can liquefy gaseous carbon dioxide into liquid carbon dioxide by consuming electric energy generated by the thermal power unit to store energy, and can utilize expansion work of the carbon dioxide to drive a generator to generate stable electric energy in the process of gasifying the liquid carbon dioxide into gaseous carbon dioxide.

[0067] As shown in Figure 2 The multi-stream waste heat storage tank includes a tank body 210, and an inner cavity 211 of the tank body 210 is used to contain heat storage medium. The inner cavity 211 is provided with a first heat exchange part 220, a second heat exchange part 230 and a waste heat recovery part. The first heat exchange part 220 is flowed through with heat absorption medium, the heat absorption medium is used to absorb heat released in the process of liquefying carbon dioxide and exchange heat with the heat storage medium in the first heat exchange part 220; the second heat exchange part 230 is flowed through with heat release medium, the heat release medium is used to absorb heat in the heat storage medium in the second heat exchange part 230 and warm gaseous or liquid carbon dioxide in the process of gasifying the liquid carbon dioxide. An exhaust path of the thermal power unit extends through the waste heat recovery part, so that flue gas and / or steam discharged by the thermal power unit exchanges heat with the heat storage medium in the waste heat recovery part.

[0068] The tank body 210 is preferably made of metal material, and different thicknesses can be used according to actual pressure strength requirements. The heat storage medium can be heat-conducting oil, or water, methanol or other medium for medium and low temperature heat storage, but the internal pressure of the multi-flow waste heat storage tank needs to be adjusted to meet the heat storage temperature. The inlets and outlets of the pipelines connected to the tank body 210 are preferably connected by flanges, and valves can be added for control switching, and sensors, instruments and other monitoring devices can also be added to monitor the flow, temperature, pressure and other parameters of each medium in real time, thereby improving safety.

[0069] According to the multi-flow waste heat storage tank, the waste heat recovery part includes a steam coil 241, and the inlet of the steam coil 241 is connected to the steam discharge port of the thermal power generating unit.

[0070] At least part of the high-temperature steam discharged by the thermal power generating unit enters the inlet of the steam coil 241, and the heat of the high-temperature steam is conducted to the heat storage medium through the pipe wall of the steam coil 241, so that the heat storage medium is heated. Subsequently, the steam is discharged from the outlet of the steam coil 241. The outlet of the steam coil 241 is preferably connected to the condenser 135 as shown in the figure, which is used to phase change the steam into condensed water and supply the condensed water to the thermal power generating unit. Figure 1

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

[0072] At least part of the high-temperature flue gas discharged by the thermal power generating unit enters the inlet of the flue gas coil 242, and the heat of the high-temperature flue gas is conducted to the heat storage medium through the pipe wall of the flue gas coil 242, so that the heat storage medium is heated. Subsequently, the flue gas is discharged from the outlet of the flue gas coil 242. The outlet of the flue gas coil 242 is preferably connected to the capture unit 138 as shown in the figure, which is used to recover gaseous carbon dioxide in the flue gas. Figure 1

[0073] According to the multi-flow waste heat storage tank, the first heat exchange part 220 is provided with a cooling coil 221 for flowing through the heat absorbing medium, and the heat absorbing medium exchanges heat with the heat storage medium through the pipe wall of the cooling coil 221; and / or the second heat exchange part 230 is provided with a heating coil 231 for flowing through the heat releasing medium, and the heat releasing medium exchanges heat with the heat storage medium through the pipe 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] The heat storage medium inlet 212 and the heat storage medium outlet 213 are preferably provided with switchable valves, respectively. When the heat storage medium is insufficient, the heat storage medium can be injected into the inner cavity 211 through the heat storage medium inlet 212, and when the pressure in the inner cavity 211 of the multi-stream waste heat storage tank is too high, the heat storage medium outlet 213 can be opened to discharge the heat storage medium to release the pressure. When the heat storage medium needs to be replaced, the new heat storage medium can be injected through the heat storage medium inlet 212 and the old heat storage medium can be discharged through the heat storage medium outlet 213.

[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, and during the operation of the energy storage system, the heat storage medium in the circulation loop flows, so that the heat storage medium in the inner cavity 211 can be kept in a flowing state, and the temperature rising speed of the heat storage medium can be slowed down to prevent the heat storage medium from rising too fast.

[0082] According to the multi-stream waste heat storage tank of the present application, the inner cavity 211 is preferably provided with a stirrer 214, as shown in the figure. Figure 2 The stirrer 214 can consume the electric energy generated by the thermal power generating unit, or be driven by renewable energy abandoned electricity, thermal power generation residual electricity, and valley electricity of the power grid, to stir the heat storage medium in the inner cavity 211, so that the heat storage medium can be kept in a flowing state in the inner cavity 211, so that the heat can be uniformly distributed at all times. The stirrer 214 can adopt a propeller type, a turbine type, an anchor type, etc.

[0083] According to the multi-stream waste heat storage tank of the present application, the outer surface of the tank body 210 and / or the inner wall surface of the inner cavity 211 is covered with a heat preservation layer to reduce the loss of heat dissipation heat. The heat preservation and 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 examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A multi-stream waste heat storage tank, characterized by, The multi-stream waste heat storage tank is used in a liquid carbon dioxide energy storage system based on waste heat recovery of a thermal power unit, the energy storage system can liquefy gaseous carbon dioxide into liquid carbon dioxide to store energy by consuming electric energy generated by the thermal power unit, and can drive a generator to generate stable electric energy by using expansion work of carbon dioxide during gasification of the liquid carbon dioxide into gaseous carbon dioxide; The multi-stream waste heat storage tank comprises a tank body (210), an inner cavity (211) of the tank body (210) is used for containing a heat storage medium; the inner cavity (211) is provided with a first heat exchange part (220), a second heat exchange part (230) and a waste heat recovery part; The first heat exchange part (220) is circulated with a heat absorption medium, the heat absorption medium is used for absorbing heat released during liquefaction of carbon dioxide, and exchanges heat with the heat storage medium in the first heat exchange part (220); the second heat exchange part (230) is circulated with a heat release medium, the heat release medium is used for absorbing heat in the heat storage medium in the second heat exchange part (230), and warming gaseous or liquid carbon dioxide during gasification of the liquid carbon dioxide; An exhaust path of the thermal power unit extends through the waste heat recovery part, so that flue gas and / or steam discharged by the thermal power unit exchanges heat with the heat storage medium in the waste heat recovery part; The waste heat recovery part comprises a steam coil (241); An inlet of the steam coil (241) is communicated with a steam discharge port of the thermal power unit, and an outlet of the steam coil (241) is communicated with a condenser (135), the condenser (135) is used for phase changing steam into condensed water, and supplying the condensed water to the thermal power unit; The waste heat recovery part comprises a flue gas coil (242); An inlet of the flue gas coil (242) is communicated with a flue gas discharge port of the thermal power unit, and an outlet of the flue gas coil (242) is communicated with a capture unit (138), the capture unit (138) is used for recovering gaseous carbon dioxide in flue gas.

2. The multi-stream waste heat reservoir tank of claim 1, wherein, The first heat exchange part (220) is provided with a cooling coil (221) for circulating the heat absorption medium, the heat absorption medium exchanges heat with the heat storage medium through a pipe wall of the cooling coil (221); And / or the second heat exchange part (230) is provided with a heating coil (231) for circulating the heat release medium, the heat release medium exchanges heat with the heat storage medium through a pipe wall of the heating coil (231).

3. The multi-stream waste heat reservoir tank of claim 2, wherein, A plurality of heat conduction fins are fixed on an outer surface of the cooling coil (221) and / or the heating coil (231).

4. A multi-stream waste heat reservoir tank according to claim 2 or 3, characterised in that, The heat release medium is water, and the second heat exchange part (230) comprises a water pipeline, one end of the water pipeline is communicated with a water source, and the other end of the water pipeline is communicated with a water using system.

5. The multi-stream waste heat reservoir tank of claim 4, wherein, The heating coil (231) is arranged in parallel with the water pipeline; Alternatively, the heating coil (231) is a part of the water pipeline, the water pipeline is provided with a softened water tank (232) capable of softening water quality upstream of the heating coil (231), the inlet of the softened water tank (232) is selectively communicated with the water source or the outlet of the heating coil (231), and the outlet of the heating coil (231) is selectively communicated with the inlet of the softened water tank (232) or the water using system.

6. The multi-stream waste heat reservoir tank of any one of claims 1-3, wherein, The tank body (210) has an openable and closable heat storage medium inlet (212) and a heat storage medium outlet (213).

7. The multi-stream waste heat reservoir tank of any one of claims 1-3, wherein, A stirrer (214) is arranged in the inner cavity (211), and the stirrer (214) can stir the heat storage medium in the inner cavity (211).

8. The multi-stream waste heat reservoir tank of any one of claims 1-3, wherein, The outer surface of the tank body (210) and / or the inner wall surface of the inner cavity (211) is covered with a heat preservation layer.

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