Flue gas carbon capture system and peak load regulation method

Abstract

The invention discloses a flue gas carbon capture system and a peak regulation method. The flue gas carbon capture system comprises a power generation module, an energy storage module, a carbon capture module, an electrolysis module and an alcohol production module. The energy storage module is connected to the power generation module, the energy storage module stores the heat energy of the main steam extracted from the power generation module and reduces the temperature of the main steam. The carbon capture module is connected to the energy storage module, the carbon capture module uses the main steam after cooling or the heat stored in the energy storage module as a heat source. The electrolysis module is connected to the power generation module, the electrolysis module uses the electricity generated by the power generation module to electrolyze water to prepare hydrogen and oxygen. The alcohol production module is connected to the carbon capture module and the electrolysis module, and the alcohol production module uses hydrogen and carbon dioxide to prepare methanol.

Description

Technical Field

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

[0002] Peaking power plants are used to assist other types of main power plants to adapt to grid load fluctuations during peak and low electricity consumption periods. For example, carbon capture power plants are not only used to provide power output to help main power plants cope with grid load fluctuations, but also capture carbon dioxide to reduce the greenhouse effect by setting up absorption towers and regeneration towers. The carbon dioxide is captured by using absorbents in the absorption tower, and the carbon dioxide is desorbed by heating the absorbents in the regeneration tower.

[0003] At present, carbon capture power plants operate at full load during peak periods and shut down or operate at low load during low periods. However, when power plants are shut down, there are problems of waste of resources and energy, as well as loss of equipment life and performance. When power plants operate at low load, there are problems of low carbon capture efficiency and poor power generation effect. 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 the carbon capture power plant operates at low load during the off-peak period of electricity consumption, the power plant's production capacity will not be fully utilized, resulting in a drop in electricity prices, which will affect the economic benefits of the power plant. Since the heat source for carbon dioxide desorption comes from the high-temperature steam extracted from the power generation module, the amount of steam generated by the power generation module operating at low load is small. Continuing to extract steam for carbon capture will seriously affect the power generation effect. In addition, since the carbon capture process requires a large amount of heat to promote chemical reactions, low load will lead to a decrease in thermal efficiency, thereby affecting the carbon capture efficiency.

[0008] In addition, the temperature of the steam extracted from the power generation module is relatively high, while the desorption temperature of the absorbent is relatively low, and therefore it cannot be directly used for heating and regenerating the absorbent. In the related art, the extracted steam is firstly 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 waste of the heat energy in the steam, 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 provides a flue gas carbon capture system, which rationally utilizes the production capacity of a carbon capture power plant, has stable operation, and has high energy utilization rate.

[0011] The flue gas carbon capture system of the embodiment of the present invention comprises:

[0012] Power generation module;

[0013] An energy storage module, the energy storage module is connected to the power generation module, the energy storage module is used to store part of the heat energy in the main steam extracted from the power generation module and reduce the temperature of the main steam;

[0014] A carbon capture module, the carbon capture module is connected to the energy storage module, and the carbon capture module is used to use the cooled main steam or the heat stored in the energy storage module as a heat source;

[0015] An electrolysis module, the electrolysis module is connected to the power generation module, and the electrolysis module is used to electrolyze water to produce hydrogen and oxygen using the electric energy generated by the power generation module;

[0016] An alcohol production module, the alcohol production module is connected to the carbon capture module and the electrolysis module, and the alcohol production module is used to produce methanol using the hydrogen produced by the electrolysis module and the carbon dioxide captured by the carbon capture module;

[0017] The flue gas carbon capture system has a full load mode and a low load mode. In the full load mode, the electric energy generated by the power generation module is connected to the power grid, and the carbon capture module uses the cooled main steam as a heat source. In the low load mode, the electric energy generated by the power generation module is supplied to the electrolysis module, and the carbon capture module uses the heat stored in the energy storage module as a heat source.

[0018] The flue gas carbon capture system of the embodiment of the present invention utilizes the energy storage module to store part of the heat energy in the main steam so as to reduce the temperature of the main steam to a temperature suitable for absorbent regeneration, thereby avoiding the problem of thermal degradation of the absorbent caused by the main steam temperature extracted from the power generation module being too high.

[0019] The flue gas carbon capture system of the embodiment of the present invention switches between full load mode and low load mode during peak power consumption period and off power consumption period respectively, thereby avoiding the adverse effects caused by system shutdown.

[0020] In addition, the heat stored when the system is running at full load is used as the heat source for absorbent regeneration when the system is running at low load. This not only reduces energy waste and improves the economic benefits of the system, but also avoids the impact of extracting main steam on the power generation effect when the system is running at low load, thereby improving the stability of the system's low load operation.

[0021] The flue gas carbon capture system of 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.

[0022] In some embodiments, the power generation module includes a connected main boiler, a steam turbine unit and a generator, and the generator is used to transmit electrical energy to the power grid or the electrolysis module;

[0023] The energy storage module includes a waste heat boiler and a steam storage tank connected to each other, wherein the waste heat boiler is connected to the steam turbine unit, and the waste heat boiler utilizes the main steam extracted from the steam turbine unit to store heat and generate auxiliary steam, and the auxiliary steam is used to be transported to the steam storage tank for storage;

[0024] The carbon capture module includes 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 utilizes the cooled main steam or auxiliary steam to heat and regenerate the absorbent transported by the regeneration tower.

[0025] 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 from the intermediate-pressure cylinder and transmit it to the waste heat boiler.

[0026] In some embodiments, the carbon capture module further includes an absorption tower and a lean-rich liquid heat exchanger, wherein the lean-rich liquid heat exchanger is connected to the absorption tower and the regeneration tower so that the absorbent flowing out of the absorption tower and the absorbent flowing out of the regeneration tower can exchange heat in the lean-rich liquid heat exchanger.

[0027] In some embodiments, the electrolysis module includes an electrolysis cell and a hydrogen storage tank and an oxygen storage tank connected to the electrolysis cell. The electrolysis cell is electrically connected to the generator. When the flue gas carbon capture system is in the low load mode, the electric energy generated by the generator is transmitted to the electrolysis cell. The electrolysis cell generates hydrogen and oxygen by electrolyzing water, and the hydrogen and oxygen are respectively transmitted to the hydrogen storage tank and the oxygen storage tank for storage.

[0028] In some embodiments, the oxygen storage tank is connected to the main boiler, and the oxygen storage tank is used to transport stored oxygen to the main boiler to assist combustion.

[0029] In some embodiments, the alcohol production module includes a compressor, a preheater, a reactor, a cooler and a methanol storage tank connected in sequence, and the compressor is connected to the regeneration tower and the hydrogen storage tank so that the carbon dioxide desorbed in the regeneration tower and the hydrogen stored in the hydrogen storage tank are transported to the compressor for compression.

[0030] In some embodiments, the alcohol production module also includes an absorption refrigerator, which is connected to the steam storage tank, and is used to use the auxiliary steam stored in the steam storage tank as a heat source for refrigeration. The absorption refrigerator is connected to the cooler, and the cold energy prepared by the absorption refrigerator is used for the cooler. The preheater is connected to the steam storage tank, and is used to preheat the mixed gas after the compressor compresses hydrogen and carbon dioxide using the auxiliary steam stored in the steam storage tank.

[0031] In some embodiments, a regulating component is provided on the pipeline connecting the power generation module, the energy storage module, the carbon capture module, the electrolysis module and the alcohol production module, and the regulating component is used to control the on-off of the pipeline and the flow of the fluid medium in the pipeline.

[0032] The embodiment of the present invention further provides a peak regulation method.

[0033] The peak shaving method of the embodiment of the present invention is used for the flue gas carbon capture system described in any of the above embodiments, and the peak shaving method includes:

[0034] When the flue gas carbon capture system is running at full load, the electric energy generated by the power generation module is connected to the power grid, the main steam is extracted from the power generation module and transmitted to the energy storage module, the energy storage module stores part of the heat energy in the main steam and reduces the temperature of the main steam, and the cooled main steam is used as the heat source of the carbon capture module;

[0035] When the flue gas carbon capture system operates at low load, the electric energy generated by the power generation module is supplied to the electrolysis module, and the electrolysis module uses the electric energy to electrolyze water to prepare hydrogen and oxygen, and the heat stored in the energy storage module is used as the heat source of the carbon capture module.

[0036] 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, during the peak load regulation process, the system switches to different operation modes to avoid the adverse effects caused by system shutdown. The stored heat is used as the heat source of the carbon capture module during the low electricity consumption period, thereby avoiding the impact of steam extraction from the power generation module on the power generation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of a flue gas carbon capture system according to an embodiment of the present invention.

[0038] Reference numerals:

[0039] Grid 100,

[0040] Main boiler 11, high pressure cylinder 12, medium pressure cylinder 13, low pressure cylinder 14, generator 15,

[0041] Waste heat boiler 21, steam storage tank 22,

[0042] Regeneration tower 31, reboiler 32, absorption tower 33, lean and rich liquid heat exchanger 34,

[0043] Electrolytic cell 41, hydrogen storage tank 42, oxygen storage tank 43,

[0044] Compressor 51 , preheater 52 , reactor 53 , cooler 54 , methanol storage tank 55 , absorption refrigerator 56 . DETAILED DESCRIPTION

[0045] 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.

[0046] The flue gas carbon capture system according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0047] like Figure 1 As shown, the flue gas carbon capture system of the embodiment of the present invention includes: a power generation module, an energy storage module, a carbon capture module, an electrolysis module and an alcohol production module.

[0048] The energy storage module is connected to the power generation module, extracts main steam at a first temperature from the power generation module, and first transmits the main steam at the first temperature to the energy storage module, and uses the energy storage module to store part of the heat energy in the main steam extracted from the power generation module, so that the temperature of the main steam is reduced from the first temperature to the second temperature. The carbon capture module is connected to the energy storage module, and uses the main steam reduced to the second temperature through the energy storage module as the heat source of the carbon capture module, or uses the heat stored in the energy storage module as the heat source of the carbon capture system.

[0049] It can be understood that the heat stored in the energy storage module and the main steam at the second temperature both meet the temperature requirements for heating and regenerating the absorbent in the carbon capture system. Therefore, the energy storage module 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 module being too high.

[0050] The electrolysis module is connected to the power generation module, and the electrolysis module is used to electrolyze water to produce hydrogen and oxygen using the electricity generated by the power generation module. The alcohol production module is connected to the carbon capture module and the electrolysis module, and the alcohol production module is used to produce methanol using the hydrogen produced by the electrolysis module and the carbon dioxide captured by the carbon capture module.

[0051] The flue gas carbon capture system according to the embodiment of the present invention has a full load mode and a low load mode.

[0052] When the load of the grid 100 is high (for example, during the day), the system operates at full load, and the electricity generated by the power generation module is incorporated into the grid 100 to help the main power plant cope with the load fluctuation of the grid 100. The main steam is extracted from the power generation module, and the energy storage system stores part of the heat energy in the main steam. The main steam is cooled by the energy storage system and then used as a heat source for the carbon capture system.

[0053] When the load of the power grid 100 is low (for example, at night), the system operates at low load, and the electric energy generated by the power generation module is supplied to the electrolysis module. The electrolysis module uses the electric energy generated by the power generation module to electrolyze water to produce hydrogen and oxygen. The alcohol production module uses hydrogen and carbon dioxide to produce methanol. The carbon capture module uses the heat stored in the energy storage module as a heat source.

[0054] Therefore, the flue gas carbon capture system of the embodiment of the present invention switches between full load mode and low load mode during peak power consumption period and off power consumption period respectively, thereby avoiding the adverse effects caused by system shutdown.

[0055] In addition, the heat stored when the system is running at full load is used as the heat source for absorbent regeneration when the system is running at low load. This not only reduces energy waste and improves the economic benefits of the system, but also avoids the impact of extracting main steam on the power generation effect when the system is running at low load, thereby improving the stability of the system's low load operation.

[0056] In addition, the flue gas carbon capture system of 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.

[0057] In some embodiments, Figure 1As shown, the power generation module 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 the peak period of electricity consumption, or is transmitted to the electrolysis module during the off-peak period of electricity consumption.

[0058] The energy storage module 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.

[0059] The carbon capture module 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 system is running at full load, 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 system is running at low load, the auxiliary steam is used to heat and regenerate the absorbent transported from the regeneration tower 31 to the reboiler 32.

[0060] It is understandable that the heat storage system uses steam heat storage to facilitate heat storage and reuse, thereby reducing energy loss. For example, if the molten salt heat storage method is used, since the molten salt is directly introduced into the reboiler 32, the problem of molten salt remaining in the reboiler 32 will occur, 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.

[0061] Alternatively, if 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.

[0062] The advantage of extracting steam from the medium pressure cylinder 13 is that it is balanced and stable. 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.

[0063] For example, main steam with a first temperature of 280° C. is extracted from the intermediate pressure cylinder 13. The auxiliary steam with the first temperature is sent to the waste heat boiler 21 to heat water and generate an auxiliary steam with a temperature of 132° C. The main steam is cooled to 130° C. by heat exchange.

[0064] 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.

[0065] Furthermore, if Figure 1 As shown, the carbon capture module also includes an absorption tower 33 and a lean-rich liquid heat exchanger 34, and the lean-rich liquid heat exchanger 34 is connected to the absorption tower 33 and the regeneration tower 31. The absorbent flowing out of the absorption tower 33 is a rich liquid with a lower temperature, and the absorbent flowing out of the regeneration tower 31 is a lean liquid with a higher temperature. The two are heat exchanged in the lean-rich liquid heat exchanger 34, which not only preheats the rich liquid, but also precools the lean liquid, thereby improving energy utilization and reducing system operation energy consumption.

[0066] In some embodiments, Figure 1 As shown, the electrolysis module includes an electrolysis cell 41 and a hydrogen storage tank 42 and an oxygen storage tank 43 connected to the electrolysis cell 41 . The electrolysis cell 41 is electrically connected to the generator 15 .

[0067] When the flue gas carbon capture system of the embodiment of the present invention operates at low load, the electric energy generated by the generator 15 is transmitted to the electrolytic cell 41, and the electrolytic cell 41 generates hydrogen and oxygen by electrolyzing water, and transmits the hydrogen and oxygen to the hydrogen storage tank 42 and the oxygen storage tank 43 for storage respectively.

[0068] Therefore, the off-peak electricity of the carbon capture power plant is used to prepare chemical energy, so that the production capacity of the power plant can be fully utilized and the economic benefits of the power plant can be improved.

[0069] Alternatively, if Figure 1 As shown, the oxygen storage tank 43 is connected to the main boiler 11, and the oxygen storage tank 43 is used to transport the stored oxygen to the main boiler 11 to assist combustion, thereby improving the combustion stability of the main boiler 11 when the system is running at low load.

[0070] In some embodiments, Figure 1 As shown, the alcohol production module includes a compressor 51, a preheater 52, a reactor 53, a cooler 54 and a methanol storage tank 55 which are connected in sequence. The compressor 51 is connected to the regeneration tower 31 and the hydrogen storage tank 42 so that the carbon dioxide desorbed in the regeneration tower 31 and the hydrogen stored in the hydrogen storage tank 42 are transported to the compressor 51 for compression.

[0071] Carbon dioxide and hydrogen are compressed and pressurized to obtain a mixed gas, which is preheated in a preheater 52 and then sent to a reactor 53 equipped with a catalyst for reaction to generate methanol. The methanol is sent to a cooler 54 for cooling to obtain a liquid product and a gas product. The liquid product is mainly methanol and water, and the liquid product is sent to a methanol storage tank 55 for storage. The gas product is mainly unreacted carbon dioxide, hydrogen, carbon monoxide produced by the reaction, and a small amount of methane, dimethyl ether, etc. A part of the gas product is discharged as a purge gas, and the other part is circulated back to the compressor 51.

[0072] Furthermore, if Figure 1 As shown, the alcohol production module further includes an absorption refrigerator 56 , the preheater 52 and the absorption refrigerator 56 are respectively connected to the steam storage tank 22 , and the absorption refrigerator 56 is connected to the cooler 54 .

[0073] When the flue gas carbon capture system of the embodiment of the present invention operates at low load, the absorption refrigeration machine 56 uses the auxiliary steam stored in the steam storage tank 22 as a heat source for refrigeration, and the prepared cold capacity is used for the cooler 54. The preheater 52 uses the auxiliary steam stored in the steam storage tank 22 to preheat the mixed gas compressed by the compressor 51 after hydrogen and carbon dioxide.

[0074] It should be noted that the temperature of the auxiliary steam is a fixed value, that is, the regeneration temperature of the absorbent, and the amount of auxiliary steam generated is determined by the temperature difference of the main steam before and after the waste heat boiler 21. The larger the difference, the more auxiliary steam is generated, and the smaller the difference, the smaller the auxiliary steam is generated. During the off-peak period of electricity consumption, the system operates at low load, the amount of flue gas that needs to be captured is small, and the amount of auxiliary steam required for heating and regenerating the absorbent is also small.

[0075] The main steam of the waste heat boiler 21 is reduced from 280°C to 130°C, and the amount of auxiliary steam generated is much larger than the amount of auxiliary steam required for heating the regenerated absorbent, so the auxiliary steam has a surplus. The surplus auxiliary steam is used for cooling in the absorption refrigerator 56 and preheating in the preheater 52, thereby reducing the energy consumption of the alcohol production process and improving the energy utilization rate.

[0076] In some embodiments, a control component (not shown in the figure) is provided on the pipeline connecting the power generation module, the energy storage module, the carbon capture module, the electrolysis module and the alcohol production module, and the control component 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 for the flue gas carbon capture system in any of the above embodiments, and the peak shaving method includes:

[0080] During the peak period of electricity consumption, the flue gas carbon capture system operates at full load, and the electricity generated by the power generation module 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 module and transported to the energy storage module, which stores part of the heat energy in the main steam to reduce the temperature of the main steam. The cooled main steam is used as a heat source for heating the regenerated absorbent in the carbon capture module.

[0081] During the off-peak period of electricity consumption, the flue gas carbon capture system operates at low load, and the electricity generated by the power generation module is supplied to the electrolysis module. The electrolysis module uses electricity to electrolyze water to produce hydrogen and oxygen, and the alcohol production module uses hydrogen and carbon dioxide to produce methanol. The heat stored in the energy storage module is used as a heat source for the carbon capture module to heat the regenerated absorbent.

[0082] Therefore, the peak-shaving 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, during the peak-shaving process, the system switches to different operation modes to avoid the adverse effects caused by system shutdown. The stored heat is used as the heat source of the carbon capture module during the low-power period to avoid the impact of steam extraction from the power generation module on the power generation effect.

[0083] Furthermore, since the energy storage module stores a large amount of heat, when the system operates at low load, part of the excess heat is used to preheat the mixed gas (compressed hydrogen and oxygen) in the alcohol production process, and the other part is used for refrigeration. The prepared cold is used to cool the alcohol production product, thereby reducing the energy consumption of alcohol production and improving energy utilization.

[0084] In the description of the present invention, it is necessary to understand 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" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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 flue gas carbon capture system, characterized in that: include: Power generation module; An energy storage module, the energy storage module is connected to the power generation module, the energy storage module is used to store part of the heat energy in the main steam extracted from the power generation module and reduce the temperature of the main steam; A carbon capture module, the carbon capture module is connected to the energy storage module, and the carbon capture module is used to use the cooled main steam or the heat stored in the energy storage module as a heat source; An electrolysis module, the electrolysis module is connected to the power generation module, and the electrolysis module is used to electrolyze water to produce hydrogen and oxygen using the electric energy generated by the power generation module; An alcohol production module, the alcohol production module is connected to the carbon capture module and the electrolysis module, and the alcohol production module is used to produce methanol using the hydrogen produced by the electrolysis module and the carbon dioxide captured by the carbon capture module; The flue gas carbon capture system has a full load mode and a low load mode. In the full load mode, the electric energy generated by the power generation module is connected to the power grid, and the carbon capture module uses the cooled main steam as a heat source. In the low load mode, the electric energy generated by the power generation module is supplied to the electrolysis module, and the carbon capture module uses the heat stored in the energy storage module as a heat source. The power generation module 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 the power grid or the electrolysis module; The energy storage module includes a waste heat boiler and a steam storage tank connected to each other, wherein the waste heat boiler is connected to the steam turbine unit, and the waste heat boiler utilizes the main steam extracted from the steam turbine unit to store heat and generate auxiliary steam, and the auxiliary steam is used to be transported to the steam storage tank for storage; The carbon capture module includes 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 utilizes the cooled main steam or auxiliary steam to heat and regenerate the absorbent transported by the regeneration tower.

2. The flue gas carbon capture system according to claim 1, characterized in that: The steam turbine unit comprises a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder which are connected in sequence. The medium-pressure cylinder is connected to the waste heat boiler so as to extract main steam from the medium-pressure cylinder and transmit it to the waste heat boiler.

3. The flue gas carbon capture system according to claim 1, characterized in that: The carbon capture module further includes an absorption tower and a lean-rich liquid heat exchanger, wherein the lean-rich liquid heat exchanger is connected to the absorption tower and the regeneration tower so that the absorbent flowing out of the absorption tower and the absorbent flowing out of the regeneration tower exchange heat in the lean-rich liquid heat exchanger.

4. The flue gas carbon capture system according to any one of claims 1 to 3, characterized in that: The electrolysis module includes an electrolytic cell and a hydrogen storage tank and an oxygen storage tank connected to the electrolytic cell. The electrolytic cell is electrically connected to the generator. When the flue gas carbon capture system is in the low load mode, the electric energy generated by the generator is transmitted to the electrolytic cell. The electrolytic cell generates hydrogen and oxygen by electrolyzing water, and the hydrogen and oxygen are respectively transmitted to the hydrogen storage tank and the oxygen storage tank for storage.

5. The flue gas carbon capture system according to claim 4, characterized in that: The oxygen storage tank is connected to the main boiler, and is used to transport stored oxygen to the main boiler for auxiliary combustion.

6. The flue gas carbon capture system according to claim 4, characterized in that: The alcohol production module includes a compressor, a preheater, a reactor, a cooler and a methanol storage tank which are connected in sequence. The compressor is connected to the regeneration tower and the hydrogen storage tank so that the carbon dioxide desorbed in the regeneration tower and the hydrogen stored in the hydrogen storage tank are transported to the compressor for compression.

7. The flue gas carbon capture system according to claim 6, characterized in that: The alcohol production module also includes an absorption refrigerator, which is connected to the steam storage tank and is used to use the auxiliary steam stored in the steam storage tank as a heat source for refrigeration. The absorption refrigerator is connected to the cooler, and the cold energy prepared by the absorption refrigerator is used for the cooler. The preheater is connected to the steam storage tank and is used to preheat the mixed gas after the compressor compresses the hydrogen and carbon dioxide using the auxiliary steam stored in the steam storage tank.

8. The flue gas carbon capture system according to claim 7, characterized in that: A regulating component is provided on the pipelines connecting the power generation module, the energy storage module, the carbon capture module, the electrolysis module and the alcohol production module, 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 for the flue gas carbon capture system according to any one of claims 1 to 8, and the peak shaving method comprises: When the flue gas carbon capture system is running at full load, the electric energy generated by the power generation module is connected to the power grid, the main steam is extracted from the power generation module and transmitted to the energy storage module, the energy storage module stores part of the heat energy in the main steam and reduces the temperature of the main steam, and the cooled main steam is used as the heat source of the carbon capture module; When the flue gas carbon capture system operates at low load, the electric energy generated by the power generation module is supplied to the electrolysis module, and the electrolysis module uses the electric energy to electrolyze water to prepare hydrogen and oxygen, and the heat stored in the energy storage module is used as the heat source of the carbon capture module.

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