Carbon dioxide capture utilization system for energy storage and working method thereof

Abstract

This invention discloses a carbon dioxide capture and utilization system and its operating method for energy storage, belonging to the technical field of carbon dioxide capture and utilization from coal-fired flue gas. The boiler flue gas purification system is connected to the hot flue gas inlet of an integrated heat storage and heat exchange device. The hot flue gas outlet of the integrated heat storage and heat exchange device is connected to the low-temperature flue gas inlet of a carbon dioxide hydraulic device. The demineralized water inlet of the carbon dioxide hydraulic device is connected to a normal-temperature demineralized water inlet pipe. The high-pressure flue gas outlet of the carbon dioxide hydraulic device is connected to the cold flue gas inlet of the integrated heat storage and heat exchange device. The cold flue gas outlet of the integrated heat storage and heat exchange device is connected to a turbine expander, which is connected to a second generator. The liquid phase outlet of the integrated heat storage and heat exchange device is connected to a neutralization reactor, which is connected to a compound fertilizer production section. The system of this invention has a reasonable structure, simple operation and maintenance, energy saving and emission reduction, and can effectively improve power generation efficiency and the power plant's frequency regulation and peak shaving capabilities, while also possessing good social and economic benefits.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of carbon dioxide capture and utilization of coal-fired flue gas, and particularly relates to a carbon dioxide capture and utilization system for energy storage and a working method thereof. BACKGROUND

[0002] At present, how to effectively reduce and control the emission of carbon dioxide has become one of the hot issues of research in various countries, and the CO2 capture technology is considered as a key technology for realizing the reduction of CO2 emission of centralized emission sources in the short term.

[0003] The coal-fired power plant is one of the main sources of CO2 emission, and about 2.5 tons of carbon dioxide are generated for each ton of coal burned. Taking a 300 MW unit as an example, 1.2 million tons of CO2 can be generated per year, and the carbon reduction task is severe. The existing carbon dioxide capture and purification technology of the coal-fired power plant mainly adopts the chemical absorption method, and the absorbent commonly used is organic amine, but the technology has the problems of high energy consumption and high cost of absorbent regeneration, and the application prospect is poor. SUMMARY

[0004] In order to solve the above problems, the purpose of the present application is to provide a carbon dioxide capture and utilization system for energy storage and a working method thereof, which has reasonable system construction, simple operation and maintenance, energy saving and emission reduction, can effectively improve the power generation efficiency of the system, improve the frequency modulation and peak regulation capacity of the power plant, and has good social and economic benefits.

[0005] The present application is realized by the following technical solutions:

[0006] The present application discloses a carbon dioxide capture and utilization system for energy storage, which comprises a boiler flue gas purification system, a heat storage and exchange integrated device, a turbine expander, a carbon dioxide hydraulic device, a neutralization reactor, a compound fertilizer production section and a second generator.

[0007] The boiler flue gas purification system is connected with the hot flue gas side inlet of the heat storage and exchange integrated device, the hot flue gas side outlet of the heat storage and exchange integrated device is connected with the low-temperature flue gas inlet of the carbon dioxide hydraulic device, the desalted water inlet of the carbon dioxide hydraulic device is connected with a normal-temperature desalted water inlet pipe, the high-pressure flue gas outlet of the carbon dioxide hydraulic device is connected with the cold flue gas side inlet of the heat storage and exchange integrated device, the cold flue gas side outlet of the heat storage and exchange integrated device is connected with the turbine expander, and the turbine expander is connected with the second generator; the liquid phase outlet of the heat storage and exchange integrated device is connected with the neutralization reactor, and the neutralization reactor is connected with the compound fertilizer production section.

[0008] Preferably, the heat storage and exchange integrated device is a double-channel shell-and-tube type, and the two ends of the first tube side are respectively connected with the hot flue gas side inlet and the hot flue gas side outlet, and the two ends of the second tube side are respectively connected with the cold flue gas side inlet and the cold flue gas side outlet.

[0009] Further preferably, the hot flue gas side inlet and the cold flue gas side outlet are arranged at the top of the heat storage and exchange integrated device, and the hot flue gas side outlet and the cold flue gas side inlet are arranged at the bottom of the heat storage and exchange integrated device.

[0010] Preferably, the desalted water inlet, the low-temperature flue gas inlet and the high-pressure flue gas outlet are arranged at the top of the carbon dioxide hydraulic device, and the liquid phase outlet is arranged at the bottom of the carbon dioxide hydraulic device.

[0011] Preferably, a low-temperature flue gas inlet valve is arranged on the pipeline between the low-temperature flue gas inlet and the hot flue gas side outlet of the heat storage and exchange integrated device; a high-pressure flue gas outlet valve and a pressure gauge are arranged on the pipeline between the high-pressure flue gas outlet and the cold flue gas side inlet of the heat storage and exchange integrated device; and a liquid phase outlet valve is arranged on the pipeline between the liquid phase outlet and the neutralization reactor.

[0012] Preferably, the heat storage medium in the heat storage and exchange integrated device is a solid heat storage medium, water, a heat-conducting oil, a low-melting-point molten salt or a phase-change heat storage material.

[0013] Preferably, the carbon dioxide hydraulic device comprises a plurality of compression tanks made of corrosion-resistant materials.

[0014] Preferably, a desalted water pump is arranged on the normal-temperature desalted water inlet pipe.

[0015] The working method of the carbon dioxide capture and utilization system for energy storage disclosed in the present application comprises the following steps:

[0016] S1, the tail flue gas generated by the boiler of the thermal power plant is subjected to denitration-dedusting-desulfurization treatment through a boiler flue gas purification system;

[0017] S2, the treated flue gas enters the hot flue gas side inlet of a heat storage and exchange integrated device and exchanges heat with a heat storage medium;

[0018] S3, the high-pressure flue gas outlet and the liquid phase outlet of a carbon dioxide hydraulic device are closed, the low-temperature flue gas inlet is opened, the heat-exchanged flue gas enters the carbon dioxide hydraulic device until the carbon dioxide hydraulic device is filled, the low-temperature flue gas inlet is closed, the desalted water inlet is opened, the normal-temperature desalted water enters the carbon dioxide hydraulic device, the flue gas is continuously subjected to isothermal compression, the carbon dioxide in the flue gas is dissolved and liquefied by the desalted water, NH3, NO2 and SO2 in the flue gas are absorbed into the mixture of the desalted water and the liquid-phase carbon dioxide, and finally a liquid-phase mixture containing liquid carbon dioxide, carbohydrates, ammonia water, nitric acid and sulfuric acid is formed;

[0019] S4, the high-pressure flue gas outlet is opened, the low-temperature high-pressure flue gas enters the heat storage and exchange integrated device, is heated and warmed up, is sent into a turbine expander, and drives the turbine expander to rotate and further drives a second generator to generate electricity;

[0020] S5, open the liquid phase outlet valve, send the liquid phase mixture containing liquid carbon dioxide, carbohydrates, ammonia, nitric acid and sulfuric acid in the carbon dioxide hydraulic device into the neutralization reactor, add potassium hydroxide slurry to the neutralization reactor, neutralize the acidic substances in the liquid phase mixture, and then enter the compound fertilizer production section to produce compound fertilizer.

[0021] Preferably, in S1, the tail flue gas is treated by the boiler flue gas purification system, and the flue gas temperature is reduced to 50-60 DEG C; in S2, the flue gas is heat-exchanged with the heat storage medium, and the temperature is reduced to below 31 DEG C; the pressure of the flue gas after isothermal compression in the carbon dioxide hydraulic device is greater than 10 MPa.

[0022] Compared with the prior art, the present application has the following beneficial technical effects:

[0023] The disclosed carbon dioxide capture and utilization system for energy storage can utilize normal-temperature desalted water in a power plant to isothermally compress flue gas after denitrification, dust removal and desulfurization, so that carbon dioxide in the flue gas is absorbed by the desalted water and liquefied, and then a mixture containing liquid carbon dioxide, carbohydrates, desalted water and the like is used to produce compound fertilizer, thereby realizing capture and utilization of carbon dioxide in coal-fired flue gas, reducing carbon emission of the power plant, producing agricultural by-products, and having good economic and social benefits. The coal-fired flue gas decarburization process adopts carbon dioxide hydraulic absorption and liquefaction, and the carbon dioxide hydraulic absorbent used is normal-temperature desalted water widely existing in the power plant. Compared with the commonly used amine alcohol method for absorbing carbon dioxide, the present application does not need to consider the regeneration of the absorbent, and the energy consumption required for the regeneration of the absorbent is eliminated, so that the energy consumption is lower and the economic efficiency is higher. The desalted water after absorbing carbon by isothermal compression can be used to produce chemical products such as compound fertilizer, thereby generating certain economic benefits. In addition, a turbo expander is added to the system, the high-pressure flue gas (mainly composed of N2, O2, NO and the like) after decarburization is sent into the turbo expander to generate power, thereby making up for the power consumption in the hydraulic process and improving the system efficiency; a heat storage and exchange integrated device is designed, the flue gas waste heat is recycled and reused, and the power generation capacity of the compressed flue gas is improved, thereby effectively improving the power generation efficiency of the system. At the same time, the system can also be used for energy storage and peak regulation, and the desalted water pump is driven by the power plant deep peak regulation surplus power to store the high-pressure flue gas in the carbon dioxide hydraulic device after decarburization and compression of the tail flue gas of the boiler; when the power plant needs to increase the load, the high-pressure flue gas is heated and sent into the turbo expander to expand and work, thereby driving the generator to generate power. Through the above process, the frequency modulation and peak regulation capacity of the power plant is improved, the amount of abandoned power is reduced, and the fuel consumption is reduced, thereby further reducing the emission of carbon dioxide, and having good social and economic benefits.

[0024] Further, the heat storage and exchange integrated device adopts a double-channel shell-and-tube type, has high heat exchange efficiency, and has simple structure and is easy to operate and maintain.

[0025] Further, the hot flue gas side inlet and the cold flue gas side outlet are arranged at the top of the heat storage and exchange integrated device, and the hot flue gas side outlet and the cold flue gas side inlet are arranged at the bottom of the heat storage and exchange integrated device, so that the two media are arranged in countercurrent, and the heat exchange efficiency is high.

[0026] The working method of the carbon dioxide capture and utilization system for energy storage disclosed by the application has high automation degree, simple operation and maintenance, energy saving and emission reduction, and good social and economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the application.

[0028] In the figure: 1-boiler; 2-high-temperature heat exchange surface; 3-turbine; 4-first generator; 5-SCR denitration reactor; 6-dust removal device; 7-desulfurization tower; 8-heat storage and exchange integrated device; 9-turbine expander; 10-demineralized water inlet; 11-low-temperature flue gas inlet; 12-high-pressure flue gas outlet; 13-carbon dioxide hydraulic device; 14-low-temperature flue gas inlet valve; 15-high-pressure flue gas outlet valve; 16-liquid phase outlet valve; 17-neutralization reactor; 18-complex fertilizer production section; 19-demineralized water pump; 20-second generator. DETAILED DESCRIPTION

[0029] The application will be further described in detail below with reference to the accompanying drawings, which are an explanation rather than a limitation of the application:

[0030] As Figure 1 The carbon dioxide capture and utilization system for energy storage of the application comprises a boiler flue gas purification system, a heat storage and exchange integrated device 8, a turbine expander 9, a carbon dioxide hydraulic device 13, a neutralization reactor 17, a complex fertilizer production section 18 and a second generator 20.

[0031] The boiler flue gas purification system is connected with the hot flue gas side inlet of the heat storage and exchange integrated device 8, the hot flue gas side outlet of the heat storage and exchange integrated device 8 is connected with the low-temperature flue gas inlet 11 of the carbon dioxide hydraulic device 13, the demineralized water inlet 10 of the carbon dioxide hydraulic device 13 is connected with a normal-temperature demineralized water inlet pipe, the high-pressure flue gas outlet 12 of the carbon dioxide hydraulic device 13 is connected with the cold flue gas side inlet of the heat storage and exchange integrated device 8, the cold flue gas side outlet of the heat storage and exchange integrated device 8 is connected with the turbine expander 9, the turbine expander 9 is connected with the second generator 20; the liquid phase outlet of the heat storage and exchange integrated device 8 is connected with the neutralization reactor 17, and the neutralization reactor 17 is connected with the complex fertilizer production section 18.

[0032] In a preferred embodiment of the present application, the heat storage and exchange integrated device 8 is a double-channel shell-and-tube type, the two ends of the first tube side are connected with the hot flue gas side inlet and the hot flue gas side outlet respectively, and the two ends of the second tube side are connected with the cold flue gas side inlet and the cold flue gas side outlet respectively. During heat storage, the hot side is the first tube side, the medium is the hot flue gas, the cold side is the shell side, and the medium is the heat storage medium; during heat release, the hot side is the shell side, the cold side is the second tube side, and the medium is the cold flue gas after decarburization. Preferably, the hot flue gas side inlet and the cold flue gas side outlet are arranged at the top of the heat storage and exchange integrated device 8, and the hot flue gas side outlet and the cold flue gas side inlet are arranged at the bottom of the heat storage and exchange integrated device 8.

[0033] In a preferred embodiment of the present application, the desalted water inlet 10, the low-temperature flue gas inlet 11 and the high-pressure flue gas outlet 12 are arranged at the top of the carbon dioxide hydraulic device 13, and the liquid phase outlet is arranged at the bottom of the carbon dioxide hydraulic device 13.

[0034] In a preferred embodiment of the present application, a low-temperature flue gas inlet valve 14 is arranged on the pipeline between the low-temperature flue gas inlet 11 and the hot flue gas side outlet of the heat storage and exchange integrated device 8; a high-pressure flue gas outlet valve 15 and a pressure gauge are arranged on the pipeline between the high-pressure flue gas outlet 12 and the cold flue gas side inlet of the heat storage and exchange integrated device 8; and a liquid phase outlet valve 16 is arranged on the pipeline between the liquid phase outlet and the neutralization reactor 17.

[0035] In a preferred embodiment of the present application, the heat storage medium in the heat storage and exchange integrated device 8 is a solid heat storage medium, water, a heat-conducting oil, a low-melting-point molten salt or a phase-change heat storage material.

[0036] In a preferred embodiment of the present application, a desalted water pump 19 is arranged on the normal-temperature desalted water inlet pipe.

[0037] The high-temperature heating surface 2 is arranged at the top of the boiler 1, the outlet of the high-temperature heating surface 2 is connected with the inlet of the steam turbine 3, and the steam turbine 3 is connected with the first generator 4. The boiler flue gas purification system comprises, in sequence from the tail of the boiler 1, the SCR denitration device 5, the dust removal device 6 and the desulfurization tower 7.

[0038] The carbon dioxide hydraulic device 13 comprises a plurality of compression tanks made of corrosion-resistant materials such as 316L stainless steel, and the compression stages and the volume of the compression tank can be set according to the actual flue gas amount.

[0039] The working method of the above-mentioned carbon dioxide capture and utilization system for energy storage comprises the following steps:

[0040] S1, the working medium in the high-temperature heat exchange surface 2 in the boiler 1 of the thermal power plant is heated and then enters the steam turbine 3 to do work, thereby driving the first generator 4 to generate electricity; the flue gas at the tail of the boiler 1 is first subjected to denitration-dust removal-desulfurization treatment by the SCR denitration reactor 5, the dust removal device 6 and the desulfurization tower 7, and the flue gas temperature is reduced to about 50-60°C;

[0041] S2, the flue gas after denitration-dedusting-desulfurization is sent to the heat storage and heat exchange integrated device 8 to exchange heat with the heat storage medium, and the temperature of the flue gas is reduced to below 31°C;

[0042] S3, close the high-pressure flue gas outlet valve 15 at the top of the carbon dioxide hydraulic device 13 and the liquid phase outlet valve 16 at the bottom, open the low-temperature flue gas inlet valve 14, and the cooled flue gas enters from the top of the carbon dioxide hydraulic device 13 until it is full. Close the low-temperature flue gas inlet valve 14, open the desalted water inlet valve, start the desalted water pump 19, and the desalted water enters from the top of the carbon dioxide hydraulic device 13 to continuously isothermal compress the flue gas, and the pressure is compressed to above 10 MPa. At this time, the carbon dioxide in the flue gas is dissolved and liquefied by the desalted water, in addition, a small amount of NH3, NO2, SO2 in the flue gas is also absorbed into the mixture of desalted water and liquid phase carbon dioxide, and finally forms a liquid phase mixture containing liquid carbon dioxide, carbohydrates, ammonia water, nitric acid, sulfuric acid, etc.

[0043] S4, open the high-pressure flue gas outlet valve 15 at the top of the carbon dioxide hydraulic device 13, and the low-temperature high-pressure flue gas enters the heat storage and heat exchange integrated device 8, is heated and warmed up, and then is sent to the turbine expander 9. The high-pressure flue gas drives the turbine expander 9 to rotate and in turn drives the second generator 20 to generate electricity.

[0044] S5, open the liquid phase outlet valve 16, and send the liquid phase mixture containing liquid carbon dioxide, carbohydrates, ammonia water, nitric acid, sulfuric acid, etc. in the carbon dioxide hydraulic device 13 to the neutralization reactor 17. Add potassium hydroxide slurry to the neutralization reactor 17 to neutralize the acidic substances such as nitric acid, sulfuric acid, carbonic acid, etc. in the liquid phase mixture, and then produce compound fertilizer through the compound fertilizer production section 18.

[0045] Under different operation modes of the system:

[0046] a. Non-energy storage mode operation: The power of the desalted water pump 19 is taken from the plant power, which reduces the power supply load of the generator set, but the compressed flue gas after decarburization is sent to the turbine expander 9 to do work and generate electricity, which makes up for part of the power loss, and finally the entire system has almost no effect on the power supply load.

[0047] b. Energy storage mode operation:

[0048] Energy storage stage: When the parameters of the thermal power generating unit are deeply adjusted for peak load, and the depth of peak load adjustment is lower than the minimum stable combustion load of the boiler 1, the boiler 1 still operates at the minimum stable combustion load. The excess peak load abandoned electricity drives the desalted water pump 19 to compress the tail flue gas and store the high-pressure flue gas in the carbon dioxide hydraulic device 13.

[0049] Energy release stage: When the unit needs to increase the load, execute S4.

[0050] Through the above process, the electric energy is stored in the form of high-pressure flue gas internal energy, and the electric energy is released through the turbine expander-generator in the energy release stage, so that the energy storage function of the whole system is realized.

[0051] The above is only part of the embodiments of the present application, although some terms are used in the present application, but the possibility of using other terms is not excluded. The use of these terms is only for the convenience of describing and explaining the essence of the present application, and any additional limitation is contrary to the spirit of the present application. The above is only used to further illustrate the content of the present application in order to make it easier to understand, but it does not mean that the embodiments of the present application are limited to this. Any technical extension or re-creation made according to the present application is protected by the present application.

Claims

1. A method of operating a carbon dioxide capture utilization system for energy storage, characterized by, The system for carbon dioxide capture and storage for energy storage comprises a boiler flue gas purification system, a heat storage and exchange integrated device (8), a turbine expander (9), a carbon dioxide hydraulic device (13), a neutralization reactor (17), a compound fertilizer production section (18), and a second generator (20); The boiler flue gas purification system is connected with the hot flue gas side inlet of the heat storage and exchange integrated device (8), the hot flue gas side outlet of the heat storage and exchange integrated device (8) is connected with the low-temperature flue gas inlet (11) of the carbon dioxide hydraulic device (13), the desalted water inlet (10) of the carbon dioxide hydraulic device (13) is connected with a normal-temperature desalted water inlet pipe, the high-pressure flue gas outlet (12) of the carbon dioxide hydraulic device (13) is connected with the cold flue gas side inlet of the heat storage and exchange integrated device (8), the cold flue gas side outlet of the heat storage and exchange integrated device (8) is connected with the turbine expander (9), and the turbine expander (9) is connected with the second generator (20); the liquid phase outlet of the heat storage and exchange integrated device (8) is connected with the neutralization reactor (17), and the neutralization reactor (17) is connected with the compound fertilizer production section (18). The working method comprises: S1, the tail flue gas generated by the boiler (1) of the thermal power plant is treated by denitration-dust removal-desulfurization of the boiler flue gas purification system; S2, the treated flue gas enters the hot flue gas side inlet of the heat storage and exchange integrated device (8) and exchanges heat with the heat storage medium; S3, the high-pressure flue gas outlet (12) and the liquid phase outlet of the carbon dioxide hydraulic device (13) are closed, the low-temperature flue gas inlet (11) is opened, the heat-exchanged flue gas enters the carbon dioxide hydraulic device (13) until it is filled, the low-temperature flue gas inlet (11) is closed, the desalted water inlet (10) is opened, the normal-temperature desalted water enters the carbon dioxide hydraulic device (13), the flue gas is continuously isothermally compressed, the carbon dioxide in the flue gas is dissolved and liquefied by the desalted water, NH3, NO2 and SO2 in the flue gas are absorbed into the mixture of the desalted water and the liquid-phase carbon dioxide, and finally the liquid-phase mixture containing liquid carbon dioxide, carbohydrate, ammonia water, nitric acid and sulfuric acid is formed; S4, the high-pressure flue gas outlet (12) is opened, the low-temperature high-pressure flue gas enters the heat storage and exchange integrated device (8), is heated and warmed up, is sent into the turbine expander (9), and drives the second generator (20) to generate electricity through the rotation of the turbine expander (9) caused by the high-pressure flue gas; S5, the liquid phase outlet valve is opened, the liquid-phase mixture containing liquid carbon dioxide, carbohydrate, ammonia water, nitric acid and sulfuric acid in the carbon dioxide hydraulic device (13) is sent into the neutralization reactor (17), the hydrogen potassium slurry is added to the neutralization reactor (17), the acidic substances in the liquid-phase mixture are neutralized, and then the neutralized liquid-phase mixture enters the compound fertilizer production section (18) to produce compound fertilizer.

2. The working method of a carbon dioxide capture utilization system for energy storage according to claim 1, characterized in that, The heat storage and exchange integrated device (8) is a double-channel shell-and-tube type, the two ends of the first tube side are connected with the hot flue gas side inlet and the hot flue gas side outlet respectively, and the two ends of the second tube side are connected with the cold flue gas side inlet and the cold flue gas side outlet respectively.

3. The working method of a carbon dioxide capture utilization system for energy storage according to claim 2, characterized in that, The hot flue gas side inlet and the cold flue gas side outlet are arranged at the top of the heat storage and exchange integrated device (8), and the hot flue gas side outlet and the cold flue gas side inlet are arranged at the bottom of the heat storage and exchange integrated device (8).

4. The working method of a carbon dioxide capture utilization system for energy storage according to claim 1, wherein, In addition to the salt water inlet (10), low temperature flue gas inlet (11) and high pressure flue gas outlet (12) are provided at the top of the carbon dioxide hydraulic device (13), and the liquid phase outlet is provided at the bottom of the carbon dioxide hydraulic device (13).

5. The working method of a carbon dioxide capture utilization system for energy storage according to claim 1, wherein, A low temperature flue gas inlet valve (14) is arranged on the pipeline between the low temperature flue gas inlet (11) and the hot flue gas side outlet of the heat storage and exchange integrated device (8); a high pressure flue gas outlet valve (15) and a pressure gauge are arranged on the pipeline between the high pressure flue gas outlet (12) and the cold flue gas side inlet of the heat storage and exchange integrated device (8); and a liquid phase outlet valve (16) is arranged on the pipeline between the liquid phase outlet and the neutralization reactor (17).

6. The working method of a carbon dioxide capture utilization system for energy storage according to claim 1, wherein, The heat storage medium in the heat storage and exchange integrated device (8) is solid heat storage medium, water, heat conducting oil, low melting point molten salt or phase change heat storage material.

7. The working method of a carbon dioxide capture utilization system for energy storage according to claim 1, wherein, The carbon dioxide hydraulic device (13) comprises several compression tanks made of corrosion-resistant materials.

8. The working method of a carbon dioxide capture utilization system for energy storage according to claim 1, wherein, A desalted water pump (19) is arranged on the normal temperature desalted water inlet pipe.

9. The working method of a carbon dioxide capture utilization system for energy storage according to claim 1, wherein, In S1, the tail flue gas is treated by the boiler flue gas purification system, and the flue gas temperature is reduced to 50-60℃; in S2, the flue gas is heat exchanged with the heat storage medium, and the temperature is reduced to below 31℃; and the pressure of the flue gas after isothermal compression in the carbon dioxide hydraulic device (13) is greater than 10MPa.

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