A CO2 capture system coupled with energy storage and peak load regulation method

Abstract

The present invention discloses a carbon dioxide capture system coupled with energy storage and a peak-shaving method. The carbon dioxide capture system coupled with energy storage includes a power generation unit, a heat storage unit and a carbon capture unit. The power generation unit is connected to the heat storage unit. The power generation unit provides main steam to the heat storage unit. The heat storage unit stores part of the heat energy in the main steam and cools the main steam. The heat storage unit is connected to the carbon capture unit. The carbon capture unit uses the heat energy in the cooled main steam or the heat energy stored in the heat storage unit as a heat source. The system has a peak-shaving mode and an economic mode. In the peak-shaving mode, the power generation unit is used to incorporate the electricity it generates into the power grid, and the carbon capture unit is used to use the heat energy in the cooled main steam as a heat source. In the economic mode, the power generation unit is used to supply the electricity it generates to the distribution system of the carbon capture power plant, and the carbon capture unit is used to use the heat energy stored in the heat storage unit as a heat source, thereby improving the economic benefits of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas purification, and in particular to a carbon dioxide capture system coupled with energy storage and a peak regulation method. Background Art

[0002] A carbon capture power plant is a power plant that uses carbon capture technology to capture and process the carbon dioxide it emits, which helps achieve low-carbon electricity production and reduce the impact of climate change. These power plants are usually equipped with special equipment, such as absorption towers and regeneration towers, to achieve the capture, transportation and storage of carbon dioxide. Since the carbon capture unit needs to extract part of the high-temperature steam in the power generation unit to drive the desorption and regeneration of the absorbent, the power generation of the carbon capture power plant fluctuates. Therefore, carbon capture power plants are usually used to assist other types of main power plants in peak load regulation, reducing greenhouse gas emissions by capturing and storing carbon dioxide. At the same time, they can provide a certain amount of power output to help the main power plant cope with load fluctuations and improve the peak load regulation capacity of the power system.

[0003] Peak load regulation of power plants is an important part of the power system. It refers to adjusting the operation mode of power plants during peak and trough periods of power demand so that power plants can quickly adapt to changes in grid load and meet the requirements of stable and safe operation of the grid. However, at present, carbon capture power plants participating in peak load regulation services have problems of waste of resources and energy, as well as loss of equipment life and performance. Summary of the invention

[0004] The present invention is based on the inventor's discovery and understanding of the following facts and problems:

[0005] In summer and winter, due to the high demand for electricity, the load on the power grid during the day and at night is not much different, and the carbon capture power plant is used in coordination. However, in spring and autumn, the load on the power grid is higher during the day, and the carbon capture power plant provides additional power supply during this period to help the main power plant cope with load fluctuations. At night, the load on the power grid is lower, and the operation of the carbon capture power plant is no longer a priority energy source for the power grid.

[0006] Therefore, if the carbon capture power plant is operated during the peak electricity consumption period (daytime) and shut down during the low electricity consumption period (nighttime), the equipment will be repeatedly started and stopped, and the temperature of the equipment will rise and fall, which will have an adverse effect on the life and performance of the equipment. In addition, the shutdown will also cause the carbon capture power plant to stop generating electricity, resulting in a waste of resources such as fuel, personnel and equipment, and thus bring economic losses.

[0007] If a carbon capture power plant operates at low load during the off-peak period of electricity consumption, the following problems will arise: the power plant's production capacity is not fully utilized, resulting in a drop in electricity prices, affecting the power plant's economic benefits; since the carbon capture process requires a large amount of heat to promote chemical reactions, low load will cause thermal efficiency to decrease, thereby affecting carbon capture efficiency; continuing to extract high-temperature steam for carbon capture from power generation units operating at low load will seriously affect the power generation effect.

[0008] In addition, the high-temperature steam in the power generation unit extracted from the carbon capture unit cannot be directly used to heat and regenerate the absorbent. The steam temperature is high and the desorption temperature of the absorbent is low. In the related art, the extracted steam is first reduced in pressure by a pressure reducing valve to achieve the purpose of cooling, and then used to heat the absorbent, resulting in a great deal of heat energy in the steam being wasted, causing unnecessary economic losses.

[0009] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0010] To this end, an embodiment of the present invention proposes a carbon dioxide capture system coupled with energy storage, which rationally utilizes the production capacity of a carbon capture power plant, and has stable system operation and high energy utilization rate.

[0011] The carbon dioxide capture system coupled with energy storage according to the embodiment of the present invention comprises a power generation unit, a heat storage unit and a carbon capture unit, wherein the power generation unit is connected to the heat storage unit, and the power generation unit is used to provide main steam at a first temperature to the heat storage unit, so that the heat storage unit stores part of the heat energy in the main steam at the first temperature and reduces the main steam to a second temperature, and the heat storage unit is connected to the carbon capture unit, and the carbon capture unit is used to use the heat energy in the main steam at the second temperature or the heat energy stored in the heat storage unit as a heat source;

[0012] The carbon dioxide capture system coupled with energy storage has a peak shaving mode and an economic mode. In the peak shaving mode, the power generation unit is used to connect the electric energy generated by it to the power grid, and the carbon capture unit is used to use the thermal energy in the main steam at the second temperature as a heat source. In the economic mode, the power generation unit is used to supply the electric energy generated by it to the distribution system of the carbon capture power plant, and the carbon capture unit is used to use the thermal energy stored in the heat storage unit as a heat source.

[0013] Therefore, the carbon dioxide capture system coupled with energy storage in the embodiment of the present invention utilizes the heat storage unit to store part of the heat energy in the main steam at the first temperature so as to reduce the temperature of the main steam to a temperature suitable for regeneration of the absorbent, thereby avoiding the problem of thermal degradation of the absorbent caused by the main steam extracted from the power generation unit being too high.

[0014] In addition, the heat energy stored in the heat storage unit can also be used as a heat source for regenerating the absorbent in the carbon capture unit, rationally utilizing the heat energy in the main steam extracted from the power generation unit, thereby reducing energy waste and improving the economic benefits of the system.

[0015] In addition, the carbon dioxide capture system coupled with energy storage in the embodiment of the present invention switches to different operating modes during peak and off-peak periods of electricity consumption, thereby avoiding the adverse effects of system shutdown and rationally utilizing the electricity generated by the carbon capture power plant during different electricity consumption periods.

[0016] In addition, the heat energy stored when the system operates in peak-shaving mode is used as a heat source for absorbent regeneration when the system operates in economic mode, avoiding affecting the power generation effect when the system operates in economic mode, thereby improving the stability of the system's low-load operation and ensuring production capacity while improving economy.

[0017] The carbon dioxide capture system coupled with energy storage in the embodiment of the present invention can not only adapt to peak load regulation with longer periodic changes such as summer and winter peaks and spring and autumn troughs, but also adapt to peak load regulation with shorter periodic changes such as daytime peaks and nighttime troughs. It has strong adaptability and high economic value.

[0018] In some embodiments, the power generation unit includes a main boiler, a steam turbine unit, and a generator connected to each other, and the generator is used to transmit electrical energy to a power grid or a distribution system of a carbon capture power plant;

[0019] The heat storage unit comprises a connected waste heat boiler and a steam storage tank, wherein the waste heat boiler is connected to the steam turbine unit, and the steam turbine unit is used to provide main steam of a first temperature to the waste heat boiler, and use the main steam of the first temperature to heat water in the waste heat boiler to generate auxiliary steam, and the main steam of the first temperature is cooled by heat exchange to main steam of a second temperature, and the temperature of the auxiliary steam is similar to the temperature of the main steam after heat exchange and cooling, and the auxiliary steam is used to be transported to the steam storage tank for storage;

[0020] The carbon capture unit comprises a connected regeneration tower and a reboiler, wherein the reboiler is connected to the waste heat boiler and the steam storage tank, and the reboiler is used for heating and regenerating the absorbent transported by the regeneration tower by using main steam or auxiliary steam at a second temperature.

[0021] In some embodiments, the steam turbine unit includes a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder connected in sequence, and the intermediate-pressure cylinder is connected to the waste heat boiler to extract main steam of a first temperature from the intermediate-pressure cylinder and transmit it to the waste heat boiler.

[0022] In some embodiments, the carbon capture unit also includes an absorption tower and a steam waste heat recovery heat exchanger. The absorption tower, the steam waste heat recovery heat exchanger and the regeneration tower are cyclically connected so that the absorbent in the absorption tower is preheated by the steam waste heat recovery heat exchanger and then flows into the regeneration tower for heating and regeneration. The absorbent heated and regenerated in the regeneration tower flows back to the absorption tower. The steam waste heat recovery heat exchanger is connected to the reboiler, and the main steam or auxiliary steam after heating and regenerating the absorbent through the reboiler is used as the heat source of the steam waste heat recovery heat exchanger.

[0023] In some embodiments, the steam waste heat recovery heat exchanger is connected to the main boiler and the waste heat boiler so that the main steam after preheating the absorbent through the steam waste heat recovery heat exchanger flows back to the main boiler, and the auxiliary steam after preheating the absorbent through the steam waste heat recovery heat exchanger flows back to the waste heat boiler.

[0024] In some embodiments, the carbon capture unit further includes a rich liquid storage tank and a lean liquid storage tank, the absorption tower is connected to the rich liquid storage tank so that the absorbent in the absorption tower flows to the rich liquid storage tank for storage, the rich liquid storage tank is connected to the steam waste heat recovery heat exchanger so that the absorbent stored in the rich liquid storage tank is preheated by the steam waste heat recovery heat exchanger and then flows into the regeneration tower for heating and regeneration, the lean liquid storage tank is connected to the regeneration tower so that the absorbent in the regeneration tower flows to the lean liquid storage tank for storage, and the lean liquid storage tank is connected to the absorption tower so that the absorbent stored in the lean liquid storage tank flows to the absorption tower to capture carbon dioxide.

[0025] In some embodiments, in the peak load mode of the carbon dioxide capture system coupled with energy storage, a portion of the absorbent flowing out of the absorption tower flows into the regeneration tower through the steam waste heat recovery heat exchanger, and another portion flows into the rich liquid storage tank, and the absorbent flowing out of the regeneration tower and the absorbent stored in the lean liquid storage tank flow into the absorption tower;

[0026] In the economic mode of the coupled energy storage carbon dioxide capture system, the absorbent flowing out of the absorption tower and the absorbent stored in the rich liquid storage tank flow into the regeneration tower through the steam waste heat recovery heat exchanger, and a part of the absorbent flowing out of the regeneration tower flows into the absorption tower, and the other part flows into the lean liquid storage tank.

[0027] In some embodiments, the carbon capture unit further comprises a lean and rich liquid heat exchanger, which is connected to the absorption tower, the rich liquid storage tank, the regeneration tower and the lean liquid storage tank, so that the absorbent flowing from the regeneration tower and / or the lean liquid storage tank to the absorption tower can be heat exchanged with the absorbent flowing from the absorption tower to the rich liquid storage tank in the lean and rich liquid heat exchanger.

[0028] In some embodiments, the power generation unit, the heat storage unit and the carbon capture unit are connected via a pipeline, and a regulating component is provided on the pipeline, and the regulating component is used to control the on-off of the pipeline and the flow of the fluid medium in the pipeline.

[0029] The embodiment of the present invention further provides a peak regulation method.

[0030] The peak shaving method of the embodiment of the present invention is used for the carbon dioxide capture system coupled with energy storage described in any of the above embodiments, and the peak shaving method includes:

[0031] When the carbon dioxide capture system coupled with energy storage operates in the peak load mode, the electric energy generated by the power generation unit is connected to the power grid, main steam at a first temperature is extracted from the power generation unit and transmitted to the heat storage unit, the heat storage unit stores part of the heat energy in the main steam at the first temperature, so that the temperature of the main steam is reduced from the first temperature to the second temperature, and the heat energy in the main steam at the second temperature is used as the heat source of the carbon capture unit;

[0032] When the energy storage coupled carbon dioxide capture system operates in the economic mode, the electric energy generated by the power generation unit is supplied to the carbon capture power plant, and the heat energy stored in the heat storage unit is used as the heat source of the carbon capture unit.

[0033] The peak load regulation method of the embodiment of the present invention reduces the temperature of the main steam by heat storage, thereby avoiding the problem of thermal degradation of the absorbent caused by excessive main steam temperature. In addition, by switching different operation modes during the peak load regulation process, the adverse effects caused by system shutdown are avoided. The stored thermal energy is used as the heat source of the carbon capture unit during the low electricity consumption period, thereby avoiding the influence of steam extraction from the power generation unit on the power generation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of a carbon dioxide capture system coupled with energy storage according to an embodiment of the present invention.

[0035] Reference numerals:

[0036] Power grid 100, power distribution system 200,

[0037] Main boiler 11, high pressure cylinder 12, medium pressure cylinder 13, low pressure cylinder 14, generator 15,

[0038] Waste heat boiler 21, steam storage tank 22,

[0039] Regeneration tower 31 , reboiler 32 , absorption tower 33 , steam waste heat recovery heat exchanger 34 , rich liquid storage tank 35 , lean liquid storage tank 36 , lean-rich liquid heat exchanger 37 . DETAILED DESCRIPTION

[0040] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0041] The following describes the carbon dioxide capture system coupled with energy storage according to an embodiment of the present invention in conjunction with the accompanying drawings.

[0042] like Figure 1 As shown, the carbon dioxide capture system coupled with energy storage according to an embodiment of the present invention includes a power generation unit, a heat storage unit and a carbon capture unit.

[0043] The power generation unit is connected to the heat storage unit, and the main steam at the first temperature is extracted from the power generation unit, and the main steam at the first temperature is first transported to the heat storage unit, and the heat storage unit is used to store part of the heat energy in the main steam at the first temperature, so that the main steam is reduced from the first temperature to the second temperature. The heat storage unit is connected to the carbon capture unit, and the heat energy in the main steam reduced to the second temperature by the heat storage unit is used as the heat source of the carbon capture unit, or the heat energy stored in the heat storage unit is used as the heat source of the carbon capture unit.

[0044] It can be understood that the heat energy stored in the heat storage unit and the heat energy in the main steam at the second temperature both meet the temperature requirement for heating and regenerating the absorbent in the carbon capture unit. Therefore, the heat storage unit is used to store part of the heat energy in the main steam at the first temperature, so that the temperature of the main steam is reduced to a temperature suitable for regeneration of the absorbent, thereby avoiding the problem of thermal degradation of the absorbent caused by the main steam extracted from the power generation unit being too high.

[0045] In addition, the heat energy stored in the heat storage unit can also be used as a heat source for regenerating the absorbent in the carbon capture unit, rationally utilizing the heat energy in the main steam extracted from the power generation unit, thereby reducing energy waste and improving the economic benefits of the system.

[0046] The energy storage coupled carbon dioxide capture system of the embodiment of the present invention has a peak shaving mode and an economic mode.

[0047] When the load of the power grid 100 is high (during the day), the carbon dioxide capture system coupled with energy storage in the embodiment of the present invention operates in peak load regulation mode, that is, the system operates at full load. At this time, the electric energy generated by the power generation unit is incorporated into the power grid 100 to help the main power plant cope with the load fluctuation of the power grid 100. The main steam is extracted from the power generation unit, and the heat storage unit stores part of the heat energy in the main steam. The main steam is cooled by the heat storage unit and then used as the heat source of the carbon capture unit.

[0048] When the load of the power grid 100 is low (at night), the carbon dioxide capture system coupled with energy storage in the embodiment of the present invention operates in economic mode, that is, the system operates at low load. At this time, the electric energy generated by the power generation unit is supplied to the power distribution system 200 of the carbon capture power plant, and is distributed to the power-consuming equipment in the plant through the power distribution system 200, such as pumps, electric heaters, compressors and other power-consuming equipment of the carbon capture power plant, so as to reduce the external consumption of the carbon capture power plant and improve the economy. In addition, the main steam is no longer extracted from the power generation unit to avoid affecting the power generation effect, and the heat energy stored in the heat storage unit is used as the heat source of the carbon capture unit.

[0049] Therefore, the carbon dioxide capture system coupled with energy storage in the embodiment of the present invention switches to different operating modes during peak and off-peak periods of electricity consumption, thereby avoiding the adverse effects of system shutdown and rationally utilizing the electricity generated by the carbon capture power plant during different electricity consumption periods.

[0050] In addition, the heat energy stored when the system operates in peak-shaving mode is used as a heat source for absorbent regeneration when the system operates in economic mode, avoiding affecting the power generation effect when the system operates in economic mode, thereby improving the stability of the system's low-load operation and ensuring production capacity while improving economy.

[0051] In addition, the carbon dioxide capture system coupled with energy storage in the embodiment of the present invention can not only adapt to peak-shaving with longer cycles such as summer and winter peaks and spring and autumn troughs, but also adapt to peak-shaving with shorter cycles such as daytime peaks and nighttime troughs. It has strong adaptability and high economic value.

[0052] In some embodiments, Figure 1 As shown, the power generation unit includes a connected main boiler 11, a steam turbine unit and a generator 15. The main steam generated by the main boiler 11 is fed into the steam turbine unit to convert the thermal energy of the main steam into mechanical energy to drive the generator 15 to generate electricity. The electricity generated by the generator 15 is transmitted to the power grid 100 during peak power consumption, or to the power distribution system 200 of the carbon capture power plant during off-peak power consumption.

[0053] The heat storage unit includes a waste heat boiler 21 and a steam storage tank 22 connected to each other. The waste heat boiler 21 is connected to the steam turbine unit. The main steam of the first temperature is extracted from the steam turbine unit and transported to the waste heat boiler 21. The main steam of the first temperature is used to heat the water in the waste heat boiler 21 to generate auxiliary steam. The main steam is cooled from the first temperature to the second temperature by heat exchange in the waste heat boiler 21. The temperature of the auxiliary steam generated by the waste heat boiler 21 is similar to the temperature of the main steam after heat exchange and cooling, and both meet the regeneration temperature of the absorbent. The auxiliary steam is transported to the steam storage tank 22 for storage.

[0054] The carbon capture unit includes a connected regeneration tower 31 and a reboiler 32, and the reboiler 32 is connected to the waste heat boiler 21 and the steam storage tank 22. When the carbon dioxide capture system coupled with energy storage in the embodiment of the present invention operates in the peak-shaving mode, the main steam at the second temperature is used to heat and regenerate the absorbent transported from the regeneration tower 31 to the reboiler 32. When the carbon dioxide capture system coupled with energy storage in the embodiment of the present invention operates in the economic mode, the auxiliary steam is used to heat and regenerate the absorbent transported from the regeneration tower 31 to the reboiler 32.

[0055] It is understandable that the heat storage unit adopts steam heat storage to facilitate heat storage and reuse, thereby reducing energy loss. For example, if molten salt heat storage is adopted, since the molten salt is directly introduced into the reboiler 32, there will be a problem that the molten salt remains in the reboiler 32, and the reboiler 32 is inconvenient to clean. When the heat energy stored in the molten salt is used, the heat energy stored in the molten salt needs to be transferred to water to generate water vapor, and then introduced into the reboiler 32 to heat the regenerated absorbent, resulting in two heat exchanges when the heat energy is reused, and each additional heat exchange will increase the heat energy loss.

[0056] In some embodiments, Figure 1 As shown, the steam turbine unit includes a high-pressure cylinder 12, an intermediate-pressure cylinder 13 and a low-pressure cylinder 14 connected in sequence, and the high-pressure cylinder 12 and the low-pressure cylinder 14 are respectively connected to the main boiler 11 to form a circulation loop. The intermediate-pressure cylinder 13 is connected to the waste heat boiler 21 to extract the main steam of the first temperature from the intermediate-pressure cylinder 13 and transmit it to the waste heat boiler 21.

[0057] It is understandable that the advantage of extracting steam from the medium pressure cylinder 13 is balanced stability. The steam temperature of the high pressure cylinder 12 is too high, and the main function of the high pressure cylinder 12 is to use the expansion of high pressure steam to do work. Extracting steam from the high pressure cylinder 12 will affect the power generation effect. The steam quality of the low pressure cylinder 14 is low, and the effect of heating and regenerating the absorbent in the reboiler 32 is poor.

[0058] Optionally, main steam of a first temperature of 280° C. is extracted from the medium pressure cylinder 13. The auxiliary steam generated by heating water in the waste heat boiler 21 with the main steam of the first temperature has a temperature of 132° C. The main steam is cooled to 130° C. by heat exchange.

[0059] It should be noted that the appropriate regeneration temperature of the absorbent is 130° C. Since heat loss occurs during the process of the auxiliary steam being transported to the steam storage tank 22 for storage, the temperature of the auxiliary steam transported from the steam storage tank 22 to the reboiler 32 is also 130° C.

[0060] In some embodiments, Figure 1 As shown, the carbon capture unit further includes an absorption tower 33 and a steam waste heat recovery heat exchanger 34 , and the absorption tower 33 , the steam waste heat recovery heat exchanger 34 are cyclically connected to the regeneration tower 31 .

[0061] The absorbent flowing out of the absorption tower 33 is the rich liquid after capturing carbon dioxide, and the absorbent flowing out of the regeneration tower 31 is the lean liquid after desorbing carbon dioxide. The rich liquid flowing out of the absorption tower 33 is preheated by the steam waste heat recovery heat exchanger 34 and then flows into the regeneration tower 31 for heating and regeneration, and the lean liquid flowing out of the regeneration tower 31 flows back to the absorption tower 33 to capture carbon dioxide.

[0062] The steam waste heat recovery heat exchanger 34 is connected to the reboiler 32. When the carbon dioxide capture system coupled with energy storage in the embodiment of the present invention operates in the peak load mode, the main steam after heating and regenerating the absorbent flowing out of the reboiler 32 flows to the steam waste heat recovery heat exchanger 34, which is used to preheat the rich liquid flowing out of the absorption tower 33. When the carbon dioxide capture system coupled with energy storage in the embodiment of the present invention operates in the economic mode, the auxiliary steam after heating and regenerating the absorbent flowing out of the reboiler 32 flows to the steam waste heat recovery heat exchanger 34, which is used to preheat the rich liquid flowing out of the absorption tower 33.

[0063] It is understandable that since the temperature at which the absorbent captures carbon dioxide in the absorption tower 33 is lower than the regeneration temperature of the absorbent, the waste heat of the main steam and the auxiliary steam is used to preheat the rich liquid before it is transported to the regeneration tower 31, thereby improving the regeneration efficiency of the absorbent, while reducing the regeneration energy consumption and energy loss.

[0064] In some embodiments, Figure 1 As shown, the steam waste heat recovery heat exchanger 34 is connected to the main boiler 11 and the waste heat boiler 21, so that the main steam after preheating the absorbent through the steam waste heat recovery heat exchanger 34 flows back to the main boiler 11, and the auxiliary steam after preheating the absorbent through the steam waste heat recovery heat exchanger 34 flows back to the waste heat boiler 21.

[0065] It should be noted that the steam flowing out of the low pressure cylinder 14 and the steam flowing out of the steam waste heat recovery heat exchanger 34 are returned to the boiler after condensation. For example, a condenser is installed on the transmission pipeline, and the refluxed steam is condensed into water using the cooling water of the power plant.

[0066] In some embodiments, Figure 1 As shown, the carbon capture unit further includes a rich liquid storage tank 35 and a lean liquid storage tank 36 .

[0067] The absorption tower 33 is connected to the rich liquid storage tank 35, and the rich liquid flowing out of the absorption tower 33 flows to the rich liquid storage tank 35 for storage. The rich liquid storage tank 35 is connected to the steam waste heat recovery heat exchanger 34, and the rich liquid stored in the rich liquid storage tank 35 is preheated by the steam waste heat recovery heat exchanger 34 and then flows into the regeneration tower 31 for heating and regeneration. That is, the rich liquid flowing out of the absorption tower 33 can not only be directly transported to the regeneration tower 31 for heating and regeneration, but also can be transported to the rich liquid storage tank 35 for storage to adapt to different carbon capture working conditions.

[0068] The lean liquid storage tank 36 is connected to the regeneration tower 31, and the lean liquid flowing out of the regeneration tower 31 flows to the lean liquid storage tank 36 for storage. The lean liquid storage tank 36 is connected to the absorption tower 33, and the absorbent stored in the lean liquid storage tank 36 flows to the absorption tower 33 to capture carbon dioxide. That is, the lean liquid flowing out of the regeneration tower 31 can not only be directly transported to the absorption tower 33 to capture carbon dioxide, but also the surplus lean liquid can be transported to the lean liquid storage tank 36 for storage to adapt to different carbon capture conditions.

[0069] It should be noted that, in the initial condition, both the lean liquid storage tank 36 and the rich liquid storage tank 35 have absorbent in the corresponding state pre-stored therein.

[0070] For example, during peak electricity consumption, the carbon dioxide capture system coupled with energy storage in an embodiment of the present invention operates in a peak-shaving mode, and a portion of the rich liquid flowing out of the absorption tower 33 is preheated through the steam waste heat recovery heat exchanger 34 and then flows to the regeneration tower 31 for heating and regeneration, and the other portion flows to the rich liquid storage tank 35 for storage, and the lean liquid flowing out of the regeneration tower 31 and the lean liquid stored in the lean liquid storage tank 36 flow together to the absorption tower 33 to capture carbon dioxide.

[0071] During the period of low electricity consumption, the coupled energy storage carbon dioxide capture system of the embodiment of the present invention operates in an economic mode. The rich liquid flowing out of the absorption tower 33 and the rich liquid stored in the rich liquid storage tank 35 are preheated by the steam waste heat recovery heat exchanger 34 and then flow to the regeneration tower 31 for heating and regeneration. A part of the lean liquid flowing out of the regeneration tower 31 flows to the absorption tower 33 to capture carbon dioxide, and the other part flows to the lean liquid storage tank 36 for storage.

[0072] It is understandable that if all the rich liquid flowing out of the absorption tower 33 is sent to the regeneration tower 31 for heating and regeneration during the peak period of electricity consumption, the amount of main steam extracted from the power generation unit will be large, affecting the power generation effect. Therefore, through the cooperation of the rich liquid storage tank 35 and the lean liquid storage tank 36, only a part of the absorbent is heated and regenerated during the peak period of electricity consumption to reduce the amount of main steam extracted from the power generation unit and reduce the impact on the power generation effect. When the electricity consumption is low, the surplus auxiliary steam is used to heat the regenerated stored rich liquid to achieve efficient use of energy.

[0073] In some embodiments, Figure 1 As shown, the carbon capture unit further includes a lean-rich liquid heat exchanger 37. The lean-rich liquid heat exchanger 37 is connected to the absorption tower 33, the rich liquid storage tank 35, the regeneration tower 31 and the lean liquid storage tank 36, so that the absorbent flowing from the regeneration tower 31 and / or the lean liquid storage tank 36 to the absorption tower 33 exchanges heat with the absorbent flowing from the absorption tower 33 to the rich liquid storage tank 35 in the lean-rich liquid heat exchanger 37.

[0074] That is, the lean liquid flowing out of the regeneration tower 31 and the lean liquid storage tank 36 is heat exchanged with the rich liquid flowing from the absorption tower 33 to the rich liquid storage tank 35 through the lean-rich heat exchanger, which not only preheats the rich liquid, but also precools the lean liquid, thereby improving energy utilization and reducing system operation energy consumption.

[0075] It can be understood that since the operating temperature of the absorption tower 33 is lower than the temperature of the lean liquid passing through the lean-rich liquid heat exchanger 37, a water cooler is provided after the lean-rich liquid heat exchanger 37, and the power plant cooling water is used to reduce the lean liquid temperature to the operating temperature of the absorption tower 33 to ensure the carbon capture effect.

[0076] In some embodiments, the power generation unit, the heat storage unit and the carbon capture unit are connected via pipelines, that is, the steam and the absorbent are transported via pipelines. In addition, a regulating component (not shown in the figure) is provided on the pipeline, which is used to control the on-off of the pipeline and the flow of the fluid medium in the pipeline.

[0077] For example, control components include pumps and valves. Pumps are used to transport fluids (liquids or gases), which can increase the pressure of the fluid and transport it to where it is needed. Valves are devices used to control the flow of fluids, realizing functions such as starting, stopping, switching, and regulating the flow of the system.

[0078] The peak shaving method according to an embodiment of the present invention is described below.

[0079] The peak shaving method of the embodiment of the present invention is used in the carbon dioxide capture system coupled with energy storage in any of the above embodiments, and the peak shaving method includes:

[0080] During the peak period of electricity consumption, the carbon dioxide capture system coupled with energy storage operates in a peak load regulation mode, and the electricity generated by the power generation unit is connected to the power grid 100 to help the main power plant cope with the load fluctuation of the power grid 100. The main steam at a first temperature is extracted from the power generation unit and transported to the heat storage unit. The heat storage unit stores part of the heat energy in the main steam at the first temperature, and reduces the temperature of the main steam from the first temperature to the second temperature, and then uses the heat energy in the main steam at the second temperature as a heat source for heating the regenerated absorbent in the carbon capture unit.

[0081] During the period of low electricity consumption, the carbon dioxide capture system coupled with energy storage operates in economic mode. The electricity generated by the power generation unit is supplied to the carbon capture power plant. At this time, the heat energy stored in the heat storage unit is used as the heat source for heating the regenerated absorbent in the carbon capture unit.

[0082] Therefore, the peak load regulation method of the embodiment of the present invention reduces the temperature of the main steam by heat storage, thereby avoiding the problem of thermal degradation of the absorbent caused by excessive main steam temperature. In addition, by switching different operation modes during the peak load regulation process, the adverse effects caused by system shutdown are avoided. The stored thermal energy is used as the heat source of the carbon capture unit during the low electricity consumption period, thereby avoiding the influence of steam extraction from the power generation unit on the power generation effect.

[0083] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0084] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0085] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0086] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0087] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0088] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A carbon dioxide capture system coupled with energy storage, characterized in that: The invention comprises a power generation unit, a heat storage unit and a carbon capture unit, wherein the power generation unit is connected to the heat storage unit, and the power generation unit is used to provide main steam of a first temperature to the heat storage unit, so that the heat storage unit uses part of the heat energy in the main steam of the first temperature to generate auxiliary steam and reduce the main steam to a second temperature, the power generation unit comprises a connected main boiler, a steam turbine unit and a generator, the generator is used to transmit electric energy to a power grid or a power distribution system of a carbon capture power plant, the heat storage unit comprises a connected waste heat boiler and a steam storage tank, the waste heat boiler is connected to the steam turbine unit, the steam turbine unit is used to provide main steam of a first temperature to the waste heat boiler, and uses the main steam of the first temperature to heat the auxiliary steam. heating water in the waste heat boiler to generate auxiliary steam, and heat-exchange cooling the main steam at a first temperature to the main steam at a second temperature, the temperature of the auxiliary steam being close to the temperature of the main steam after heat exchange and cooling, the auxiliary steam being used to be transported to the steam storage tank for storage, the heat storage unit being connected to the carbon capture unit, the carbon capture unit being used to utilize the heat energy in the main steam at the second temperature or the heat energy in the auxiliary steam stored in the heat storage unit as a heat source, the carbon capture unit comprising a connected regeneration tower and a reboiler, the reboiler being connected to the waste heat boiler and the steam storage tank, the reboiler being used to utilize the main steam at the second temperature or the auxiliary steam to heat and regenerate the absorbent transported by the regeneration tower; The carbon dioxide capture system coupled with energy storage has a peak shaving mode and an economic mode. In the peak shaving mode, the power generation unit is used to connect the electric energy generated by it to the power grid, and the carbon capture unit is used to use the thermal energy in the main steam at the second temperature as a heat source. In the economic mode, the power generation unit is used to supply the electric energy generated by it to the distribution system of the carbon capture power plant, and the carbon capture unit is used to use the thermal energy stored in the heat storage unit as a heat source.

2. The carbon dioxide capture system coupled with energy storage according to claim 1, characterized in that: The steam turbine unit comprises a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder connected in sequence, and the intermediate-pressure cylinder is connected to the waste heat boiler to extract main steam at a first temperature from the intermediate-pressure cylinder and transmit it to the waste heat boiler.

3. The energy storage coupled carbon dioxide capture system according to claim 1, characterized in that: The carbon capture unit also includes an absorption tower and a steam waste heat recovery heat exchanger. The absorption tower, the steam waste heat recovery heat exchanger and the regeneration tower are cyclically connected so that the absorbent in the absorption tower is preheated by the steam waste heat recovery heat exchanger and then flows into the regeneration tower for heating and regeneration. The absorbent heated and regenerated in the regeneration tower flows back to the absorption tower. The steam waste heat recovery heat exchanger is connected to the reboiler, and the main steam or auxiliary steam after heating and regenerating the absorbent through the reboiler is used as the heat source of the steam waste heat recovery heat exchanger.

4. The carbon dioxide capture system coupled with energy storage according to claim 3, characterized in that: The steam waste heat recovery heat exchanger is connected to the main boiler and the waste heat boiler so that the main steam after preheating the absorbent through the steam waste heat recovery heat exchanger flows back to the main boiler, and the auxiliary steam after preheating the absorbent through the steam waste heat recovery heat exchanger flows back to the waste heat boiler.

5. The carbon dioxide capture system coupled with energy storage according to claim 3, characterized in that: The carbon capture unit also includes a rich liquid storage tank and a lean liquid storage tank. The absorption tower is connected to the rich liquid storage tank so that the absorbent in the absorption tower flows to the rich liquid storage tank for storage. The rich liquid storage tank is connected to the steam waste heat recovery heat exchanger so that the absorbent stored in the rich liquid storage tank is preheated by the steam waste heat recovery heat exchanger and then flows into the regeneration tower for heating and regeneration. The lean liquid storage tank is connected to the regeneration tower so that the absorbent in the regeneration tower flows to the lean liquid storage tank for storage. The lean liquid storage tank is connected to the absorption tower so that the absorbent stored in the lean liquid storage tank flows to the absorption tower to capture carbon dioxide.

6. The carbon dioxide capture system coupled with energy storage according to claim 5, characterized in that: In the peak load mode of the carbon dioxide capture system coupled with energy storage, part of the absorbent flowing out of the absorption tower flows into the regeneration tower through the steam waste heat recovery heat exchanger, and the other part flows into the rich liquid storage tank, and the absorbent flowing out of the regeneration tower and the absorbent stored in the lean liquid storage tank flow into the absorption tower; In the economic mode of the coupled energy storage carbon dioxide capture system, the absorbent flowing out of the absorption tower and the absorbent stored in the rich liquid storage tank flow into the regeneration tower through the steam waste heat recovery heat exchanger, and a part of the absorbent flowing out of the regeneration tower flows into the absorption tower, and the other part flows into the lean liquid storage tank.

7. The energy storage coupled carbon dioxide capture system according to claim 6, characterized in that: The carbon capture unit also includes a lean and rich liquid heat exchanger, which is connected to the absorption tower, the rich liquid storage tank, the regeneration tower and the lean liquid storage tank, so that the absorbent flowing from the regeneration tower and / or the lean liquid storage tank to the absorption tower can exchange heat with the absorbent flowing from the absorption tower to the rich liquid storage tank in the lean and rich liquid heat exchanger.

8. The carbon dioxide capture system coupled with energy storage according to any one of claims 1 to 7, characterized in that: The power generation unit, the heat storage unit and the carbon capture unit are connected via a pipeline, and a regulating component is provided on the pipeline, and the regulating component is used to control the on-off of the pipeline and the flow of the fluid medium in the pipeline.

9. A peak shaving method, characterized in that: The peak shaving method is used in a carbon dioxide capture system coupled with energy storage according to any one of claims 1 to 8, and the peak shaving method comprises: When the carbon dioxide capture system coupled with energy storage operates in the peak load mode, the electric energy generated by the power generation unit is connected to the power grid, main steam at a first temperature is extracted from the steam turbine unit of the power generation unit and transmitted to the waste heat boiler of the heat storage unit, the main steam at the first temperature is used to heat water in the waste heat boiler to generate auxiliary steam, so that the temperature of the main steam is reduced from the first temperature to the second temperature, the auxiliary steam is used to be transmitted to the steam storage tank of the heat storage unit for storage, and the heat energy in the main steam at the second temperature is used as the heat source of the carbon capture unit; When the energy storage coupled carbon dioxide capture system operates in the economic mode, the electric energy generated by the power generation unit is supplied to the carbon capture power plant, and the thermal energy in the auxiliary steam stored in the thermal storage unit is used as the heat source of the carbon capture unit.

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