Coal-fired unit peak-shaving power generation system and method coupled with carbon dioxide compression energy storage

Abstract

The present invention discloses a peak-shaving power generation system and method for coal-fired units coupled with carbon dioxide compression energy storage. The method of the present invention for generating electricity using the peak-shaving power generation system of coal-fired units is as follows: when the power grid is in a low-power consumption period, part of the steam generated by the coal-fired unit is extracted to provide energy to the reboiler, and at the same time, part of the power generated by the steam turbine generator is used to provide energy to the CO2 low-pressure compression device or the CO2 multi-stage compression device, so that the actual grid-connected power of the peak-shaving power generation system reaches the target grid-connected power; when the power grid is in a peak power consumption period, the supercritical CO2 stored in the CO2 high-pressure compression tank is sent to the CO2 expander to perform work, so as to increase the grid-connected power of the peak-shaving power generation system, so that the actual grid-connected power of the peak-shaving power generation system reaches the target grid-connected power. The present invention can not only reduce the carbon emissions of coal-fired units, but also provide support for peak-shaving and valley-filling of the power grid.

Description

Technical Field

[0001] The present invention belongs to the technical field of power generation units, and in particular to a peak-shaving power generation system and method for a coal-fired unit coupled with carbon dioxide compression energy storage. Background Art

[0002] Carbon capture technology is currently a key technology that can achieve low-carbon utilization of fossil energy and low-carbon emissions in industrial processes such as thermal power, cement, and steel. Its basic principle is to separate CO2 from industrial process sources and emission sources and then directly utilize or seal it to achieve carbon emission reduction. The large-scale application of carbon capture technology to coal-fired units can not only effectively resolve the contradiction between fossil fuel utilization and carbon emission reduction, but also preserve the rotational inertia of the power system, which helps to ensure the safe and stable operation of the power system.

[0003] When coal-fired units use carbon capture technology to form a power generation system, the flexibility of grid dispatch can generally be improved. After coupling with CO2 compression energy storage, the flexibility of load regulation is further improved. When the grid needs to reduce the system output, energy can be supplied to the carbon capture and CO2 compression energy storage systems to reduce the system's power generation output. When the grid needs to increase the system output, CO2 compression energy storage can be used to expand and do work to increase the system's power generation output. Compared with conventional coal-fired units, the use of carbon capture technology can more flexibly adjust the net output and improve the primary and secondary frequency regulation response speed. The use of coal-fired units using carbon capture technology and coupled with renewable energy such as photovoltaics also provides a new way to improve the utilization rate of renewable energy. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the above-mentioned prior art and provide a peak-shaving power generation system and method for coal-fired units coupled with CO2 compression energy storage, which couples CO2 compression energy storage with coal-fired units for peak-shaving, so as to effectively improve the comprehensive rapid peak-shaving capability of coal-fired units and reduce carbon emissions.

[0005] To this end, the technical solution adopted by the present invention is: a peak-shaving power generation system of a coal-fired unit coupled with carbon dioxide compression energy storage, which comprises:

[0006] Coal-fired boiler, steam turbine, steam turbine generator, main steam pipeline, reheat steam pipeline, first steam pipeline, second steam pipeline, third steam pipeline, fourth steam pipeline, tail flue of coal-fired boiler, flue gas pipeline, reboiler, absorption tower, regeneration tower, rich liquid pump, lean liquid pump, CO2 low-pressure compression device, CO2 multi-stage compression device, CO2 low-pressure storage tank, CO2 high-pressure storage tank, photovoltaic power generation system, energy storage device, photovoltaic generator, CO2 low-pressure compression pipeline, CO2 high-pressure compression pipeline, CO2 high-pressure energy release pipeline, CO2 expander, expander generator and steam generator;

[0007] The first steam pipeline is connected to the main steam pipeline and the reboiler; one end of the main steam pipeline is connected to the coal-fired boiler, and the other end is connected to the steam turbine; the steam turbine generator is driven by the steam turbine; the second steam pipeline is connected to the reheat steam pipeline and the reboiler; the third steam pipeline and the fourth steam pipeline are both connected to the steam turbine and the reboiler; the flue gas pipeline is connected to the tail flue of the coal-fired boiler and the absorption tower, and the tail flue of the coal-fired boiler is arranged at the tail of the coal-fired boiler;

[0008] The rich liquid pump is connected to the absorption tower and the regeneration tower; the lean liquid pump is connected to the absorption tower and the regeneration tower;

[0009] The CO2 low-pressure compression pipeline connects the regeneration tower and the CO2 low-pressure storage tank, and a CO2 low-pressure compression device is arranged on the pipeline; the CO2 high-pressure compression pipeline connects the regeneration tower and the CO2 high-pressure storage tank, and a CO2 multi-stage compression device is arranged on the pipeline; the CO2 high-pressure energy release pipeline connects the CO2 low-pressure storage tank and the CO2 high-pressure storage tank, and a CO2 expander is arranged on the pipeline, and the expander generator is driven by the CO2 expander;

[0010] The photovoltaic power generation system is connected to a photovoltaic generator, the photovoltaic generator is connected to an energy storage device and a steam generator, and the steam generator is connected to a reboiler;

[0011] The steam turbine generator is connected to the power grid via a first transmission line, and the expander generator is connected to the power grid via a second transmission line.

[0012] Furthermore, a flue gas flow controller and a CO2 mass fraction detector are arranged on the flue gas pipeline, enthalpy detectors are arranged before and after the CO2 low-pressure compression device, enthalpy detectors are arranged before and after the CO2 multi-stage compression device, and enthalpy detectors are arranged before and after the CO2 expander.

[0013] Furthermore, the first steam pipeline, the second steam pipeline, the third steam pipeline and the fourth steam pipeline are all provided with enthalpy detectors and steam flow controllers, and the exhaust pipeline of the reboiler is provided with an enthalpy detector.

[0014] Furthermore, a CO2 concentration detection device is provided in the absorption tower and the regeneration tower.

[0015] The present invention also provides a peak-shaving power generation method for a coal-fired unit coupled with carbon dioxide compression energy storage, which adopts the above-mentioned peak-shaving power generation system for a coal-fired unit and comprises:

[0016] 1) When it is determined that the power grid is in the off-peak period, according to the theoretical output power of the peak-shaving power generation system and the target grid-connected power, part of the steam generated by the coal-fired unit is extracted to provide energy to the reboiler, and part of the power generated by the steam turbine generator is used to provide energy to the CO2 low-pressure compression device or the CO2 multi-stage compression device, so that the actual grid-connected power of the peak-shaving power generation system reaches the target grid-connected power, so as to quickly reduce the output power of the peak-shaving power generation system;

[0017] According to the real-time output power of the steam turbine generator, it is determined whether to put the first steam pipeline, the second steam pipeline, the third steam pipeline or the fourth steam pipeline into operation;

[0018] According to the difference between the theoretical power generation of the peak-shaving power generation system and the target grid-connected power, it is determined whether to put into operation the CO2 low-pressure compression device or the CO2 multi-stage compression device, and the flue gas flow rate of the flue gas pipeline is controlled by the flue gas flow controller and the CO2 mass fraction detector;

[0019] 2) When it is determined that the power grid is at a peak period of electricity consumption, according to the theoretical output power of the peak-shaving power generation system and the target grid-connected power, the supercritical CO2 stored in the CO2 high-pressure compression tank is sent to the CO2 expander through the CO2 high-pressure energy release pipeline to perform work, thereby increasing the grid-connected power of the expander generator, and then increasing the grid-connected power of the peak-shaving power generation system, so that the actual grid-connected power of the peak-shaving power generation system reaches the target grid-connected power;

[0020] The main steam pipeline, reheat steam pipeline and steam extraction of the steam turbine are cut off, and the power generated by the photovoltaic generator is used to generate steam to provide energy for the reboiler.

[0021] Further, the energy provided to the reboiler and the expression of the decrease value of the output power of the peak-shaving power generation system are P3=α1×(P2-P1); the energy provided to the CO2 low-pressure compression device or the CO2 multi-stage compression device and the expression of the decrease value of the output power of the peak-shaving power generation system are P4=α2×(P2-P1), α1+α2=1;

[0022] Among them, P2 is the theoretical output power of the peak-shaving power generation system, in J / s; P1 is the target grid-connected power of the peak-shaving power generation system, in J / s; α1 is the reboiler energy coefficient; α2 is the energy coefficient of the CO2 low-pressure compression device or the CO2 multi-stage compression device;

[0023] When P2-P1<0.3P2, the CO2 low-pressure compression device is put into operation; when P2-P1≥0.3P2, the CO2 multi-stage compression device is put into operation.

[0024] Furthermore, the expression of the steam extraction flow rate q1 of the first steam pipeline is:

[0025] Among them, h1 is the extraction enthalpy of the first steam pipeline, in J / g; h0 is the exhaust enthalpy of the steam turbine, in J / g; η1 is the extraction efficiency of the first steam pipeline, in %;

[0026] The expression of the second steam pipeline extraction steam flow rate q2 is:

[0027] Wherein, h2 is the extraction enthalpy of the second steam pipeline, in J / g; η2 is the extraction efficiency of the second steam pipeline, in %;

[0028] The expression of the extraction steam flow rate q3 of the third steam pipeline is:

[0029] Wherein, h3 is the extraction enthalpy of the third steam pipeline, in J / g; η3 is the extraction efficiency of the third steam pipeline, in %;

[0030] The expression of the fourth steam pipeline extraction steam flow rate q4 is:

[0031] Wherein, h4 is the extraction enthalpy of the fourth steam pipeline, in J / g; η4 is the extraction efficiency of the fourth steam pipeline, in %.

[0032] Furthermore, the expression of the flue gas flow rate q5 of the flue gas pipeline is:

[0033] Among them, η5 is the efficiency of the carbon capture device, in %; β is the CO2 mass fraction of the flue gas in the flue gas pipeline, in %; γ is the energy consumed by the carbon capture device to process unit mass of CO2, in J / g.

[0034] Furthermore, the expression of the CO2 low-pressure compression pipeline flow q6 is:

[0035] Among them, η6 is the efficiency of the CO2 low-pressure compression device, in %; h5 is the CO2 enthalpy value at the outlet of the CO2 low-pressure compression device, in J / g; h6 is the CO2 enthalpy value at the inlet of the CO2 low-pressure compression device, in J / g;

[0036] The expression of CO2 high pressure compression pipeline flow q7 is:

[0037] Among them, η7 is the efficiency of the CO2 multi-stage compression device, in %; h7 is the CO2 enthalpy value at the outlet of the CO2 multi-stage compression device, in J / g; h8 is the CO2 enthalpy value at the inlet of the CO2 multi-stage compression device, in J / g.

[0038] Furthermore, the expression of the CO2 high-pressure energy release pipeline flow rate q8 is:

[0039] Wherein, η8 is the efficiency of CO2 expander, in %; h9 is the CO2 enthalpy at the inlet of CO2 expander, in J / g; h 10 It is the enthalpy of CO2 at the outlet of CO2 expander, in J / g.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1) Coal-fired units have always been a major source of carbon emissions. The present invention couples coal-fired units with carbon capture and CO2 compression energy storage, which can effectively reduce CO2 emissions from coal-fired units and provide a new way for CO2 utilization.

[0042] 2) In the past, the peak-shaving capacity of coal-fired units was restricted by their own performance, and their lower limit and rate of peak-shaving may be difficult to meet the requirements of the power grid. After the coal-fired units are coupled with carbon capture and CO2 compression energy storage, when the power grid needs to reduce the system output, they can supply energy to the carbon capture and CO2 compression energy storage system to reduce its power generation output. When the power grid needs to increase the system output, the CO2 compression energy storage expansion work can be used to increase the system output, further improving the peak-shaving flexibility.

[0043] 3) In the past, coal-fired units used carbon capture technology and consumed a large amount of energy. After the present invention is coupled with a photovoltaic power generation system, it can effectively reduce the energy consumption of the coal-fired units themselves and improve the utilization rate of renewable energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a structural schematic diagram of the peak-shaving power generation system of a coal-fired unit coupled with CO2 compression energy storage according to the present invention;

[0045] Among them, 1-coal-fired boiler, 2-steam turbine, 3-steam turbine generator, 4-main steam pipeline, 5-reheat steam pipeline, 6-first steam pipeline, 7-second steam pipeline, 8-third steam pipeline, 9-fourth steam pipeline, 10-coal-fired boiler tail flue, 11-flue gas pipeline, 12-reboiler, 13-absorption tower, 14-regeneration tower, 15-rich liquid pump, 16-lean liquid pump, 17-CO2 low-pressure compression device, 18-CO2 multi-stage compression device, 19-CO2 low-pressure storage tank, 20-CO2 high-pressure storage tank, 21-photovoltaic power generation system, 22-energy storage device, 23-photovoltaic generator, 24-CO2 low-pressure pressure compression pipeline, 25-CO2 high-pressure compression pipeline, 26-CO2 high-pressure energy release pipeline, 27-CO2 expander, 28-expander generator, 29-flue gas flow controller, 30-CO2 mass fraction detector, 31-enthalpy detector, 32-steam flow controller, 33-CO2 concentration detection device, 34-steam generator, 35-first transmission line, 36-second transmission line, 37-first isolating switch, 38-second isolating switch, 39-isolating valve, 40-grid, 41-reboiler exhaust pipeline, 42-rich liquid pump pipeline, 43-lean liquid pump pipeline, 44-third isolating switch, 45-steam generation pipeline.

[0046] Figure 2 The figure is a schematic flow chart of the peak load regulation power generation method of a coal-fired unit coupled with CO2 compression energy storage according to the present invention. DETAILED DESCRIPTION

[0047] The following will further describe the specific implementation of the present invention in combination with the accompanying drawings of the embodiments of the present invention, so that the technical solution of the present invention is easier to understand and grasp. It should be understood that the specific embodiments described here are only used to explain part of the embodiments of the invention, rather than all the embodiments. Other embodiments obtained by ordinary technicians in this field without making creative work are all within the scope of protection of the present invention.

[0048] Example 1

[0049] Please see attached Figure 1The schematic diagram of a peak-shaving power generation system of a coal-fired unit coupled with CO2 compression energy storage of the present invention. The system includes: a coal-fired boiler 1, a steam turbine 2, a steam turbine generator 3, a main steam pipeline 4, a reheat steam pipeline 5, a first steam pipeline 6, a second steam pipeline 7, a third steam pipeline 8, a fourth steam pipeline 9, a tail flue 10 of a coal-fired boiler, a flue gas pipeline 11, a reboiler 12, an absorption tower 13, a regeneration tower 14, a rich liquid pump 15, a lean liquid pump 16, a CO2 low-pressure compression device 17, a CO2 multi-stage compression device 18, a CO2 low-pressure storage tank 19, a CO2 high-pressure storage tank 20, a photovoltaic power generation system 21, an energy storage device 22, a photovoltaic generator 23, a CO2 low-pressure compression pipe Line 24, CO2 high-pressure compression pipeline 25, CO2 high-pressure energy release pipeline 26, CO2 expander 27, expander generator 28, flue gas flow controller 29, CO2 mass fraction detector 30, enthalpy detector 31, steam flow controller 32, CO2 concentration detection device 33, steam generator 34, first transmission line 35, second transmission line 36, first isolating switch 37, second isolating switch 38, isolating valve 39, power grid 40, reboiler exhaust pipeline 41, rich liquid pump pipeline 42, lean liquid pump pipeline 43, third isolating switch 44 and steam generation pipeline 45.

[0050] The steam turbine generator 3 is connected to the power grid 40 via a first transmission line 35 on which a first isolating switch 37 is provided. The expander generator 28 is connected to the power grid 40 via a second transmission line 36 on which a second isolating switch 38 is provided.

[0051] The first steam pipeline 6 connects the main steam pipeline 4 and the reboiler 12. One end of the main steam pipeline 4 is connected to the coal-fired boiler 1, and the other end is connected to the steam turbine 2; the steam turbine generator 3 is driven by the steam turbine 2.

[0052] The second steam line 7 connects the reheat steam line 5 and the reboiler 12 .

[0053] The third steam pipeline 8 and the fourth steam pipeline 9 connect the steam turbine 2 and the reboiler 12 .

[0054] The flue gas pipeline 11 connects the coal-fired boiler tail flue 10 and the absorption tower 13 . The coal-fired boiler tail flue 10 is arranged at the tail of the coal-fired boiler 1 .

[0055] The rich liquid pump 15 connects the absorption tower 13 and the regeneration tower 14 .

[0056] The lean liquid pump 16 connects the absorption tower 13 and the regeneration tower 14 .

[0057] The CO2 low-pressure compression pipeline 24 connects the regeneration tower 14 and the CO2 low-pressure storage tank 19, and a CO2 low-pressure compression device 17 and an isolation valve 39 are arranged on the pipeline.

[0058] The CO2 high-pressure compression pipeline 25 connects the regeneration tower 14 and the CO2 high-pressure storage tank 20, and a CO2 multi-stage compression device 18 and an isolation valve 39 are arranged on the pipeline.

[0059] The CO2 high-pressure energy release pipeline 26 connects the CO2 low-pressure storage tank 19 and the CO2 high-pressure storage tank 20, and a CO2 expander 27 and an isolation valve 39 are arranged on the pipeline.

[0060] A flue gas flow controller 29 and a CO2 mass fraction detector 30 are arranged on the flue gas pipeline 11, enthalpy detectors 31 are arranged before and after the CO2 low-pressure compression device 17, enthalpy detectors 31 are arranged before and after the CO2 multi-stage compression device 18, and enthalpy detectors 31 are arranged before and after the CO2 expander 27.

[0061] An enthalpy detector 31 and a steam flow controller 32 are provided on the first steam pipeline 6 , the second steam pipeline 7 , the third steam pipeline 8 , and the fourth steam pipeline 9 , and an enthalpy detector 31 is provided on the reboiler exhaust pipeline 41 .

[0062] A CO2 concentration detection device 33 is provided in the absorption tower 13 and the regeneration tower 14 .

[0063] The absorption tower 13 and the regeneration tower 14 are connected via a rich liquid pump pipeline 42 and a lean liquid pump pipeline 43 , respectively. A rich liquid pump 15 is provided on the rich liquid pump pipeline 42 , and a lean liquid pump 16 is provided on the lean liquid pump pipeline 43 .

[0064] The photovoltaic power generation system 21 is connected to the photovoltaic generator 23 , the photovoltaic generator 23 is connected to the energy storage device 22 and the steam generator 34 via a third isolating switch 44 , and the steam generator 34 is connected to the reboiler 12 via a steam generation pipeline 45 .

[0065] Example 2

[0066] The coal-fired unit peak load generation system described in Example 1 is used to generate electricity, such as Figure 2 As shown, the operation process is as follows:

[0067] When it is determined that the power grid 40 is in a low-power consumption period, according to the theoretical output power of the peak-shaving power generation system and the target grid-connected power, part of the steam generated by the coal-fired unit is extracted to provide energy for the reboiler 12, and according to the real-time output power of the steam turbine generator 3, it is determined to put the first steam pipeline 6 or the second steam pipeline 7 or the third steam pipeline 8 or the fourth steam pipeline 9 into operation. When the real-time output power of the steam turbine generator 3 is ≥70% of the rated load of the steam turbine generator 3, the third steam pipeline 8 or the fourth steam pipeline 9 is put into operation. At this time, the isolation valve 39 on the third steam pipeline 8 or the fourth steam pipeline 9 is opened, and the first steam pipeline 6, the second steam pipeline 7, the third steam pipeline 8, and the fourth steam pipeline 9 are closed. The isolation valve 39 on the pipeline 7; when 70% of the rated load of the steam turbine generator 3 ≥ the real-time output power of the steam turbine generator 3 ≥ 40% of the rated load of the steam turbine generator 3, the second steam pipeline 7 is put into operation, and the isolation valve 39 on the second steam pipeline 7 is opened, and the isolation valves 39 on the first steam pipeline 6, the third steam pipeline 8, and the fourth steam pipeline 9 are closed; when 40% of the rated load of the steam turbine generator 3 ≥ the real-time output power of the steam turbine generator 3, the first steam pipeline 6 is put into operation, and the isolation valve 39 on the first steam pipeline 6 is opened, and the isolation valves 39 on the second steam pipeline 7, the third steam pipeline 8, and the fourth steam pipeline 9 are closed. According to the steam enthalpy detected by the enthalpy detector 31 on the steam pipeline in operation and the steam enthalpy detected by the enthalpy detector 31 on the reboiler exhaust pipeline 41, the steam flow rate of the steam pipeline in operation is controlled by the steam flow controller 32.

[0068] The isolation valve 39 on the CO2 high-pressure energy release pipeline 26 is closed, the CO2 expander 27 is in a shutdown state, and the second isolation switch 38 is disconnected.

[0069] Part of the power generated by the steam turbine generator 3 is used to provide energy to the CO2 low-pressure compression device 17 or the CO2 multi-stage compression device 18, so that the actual grid-connected power of the peak-shaving power generation system reaches the target grid-connected power, so as to quickly reduce the output power of the peak-shaving power generation system.

[0070] According to the difference between the theoretical output power of the peak-shaving power generation system and the target grid-connected power, it is determined whether to put the CO2 low-pressure compression device 17 or the CO2 multi-stage compression device 18 into operation. When P2-P1<0.3P2, the CO2 low-pressure compression device is put into operation, and the isolation valve 39 on the CO2 low-pressure compression pipeline 24 is disconnected; when P2-P1≥0.3P2, the CO2 multi-stage compression device 18 is put into operation, and the isolation valve 39 on the CO2 high-pressure compression pipeline 25 is disconnected.

[0071] The flue gas flow rate of the flue gas pipeline 11 is controlled by the flue gas flow controller 29 according to the energy provided to the reboiler 12 and the CO2 mass fraction of the flue gas in the flue gas pipeline 11 detected by the CO2 mass fraction detector 30.

[0072] The rich liquid pump 15 and the lean liquid pump 16 are used to control the CO2 concentration in the absorption tower 13 and the regeneration tower 14. The CO2 concentration in the absorption tower 13 and the regeneration tower 14 is detected by the CO2 concentration detection device 33. When the CO2 concentration in the absorption tower 13 is higher than the critical value or the CO2 concentration in the regeneration tower 14 is lower than the critical value, the speed of the rich liquid pump 15 is reduced and the speed of the lean liquid pump 16 is increased. When the CO2 concentration in the absorption tower 13 is lower than the critical value or the CO2 concentration in the regeneration tower 14 is higher than the critical value, the speed of the rich liquid pump 15 is increased and the speed of the lean liquid pump 16 is reduced.

[0073] The third isolating switch 44 is closed, the isolating valve 39 on the steam generating pipeline 45 is disconnected, the photovoltaic generator 23 is connected to the energy storage device 22, and all the electricity generated by the photovoltaic generator 23 is stored.

[0074] When it is determined that the power grid 40 is in the peak period of electricity consumption, the isolation valve 39 on the CO2 high-pressure energy release pipeline 26 is closed according to the theoretical output power of the peak-shaving power generation system and the target grid-connected power, and the supercritical CO2 stored in the CO2 high-pressure compression tank 20 is sent to the CO2 expander 27 through the CO2 high-pressure energy release pipeline 26 to perform work, and the CO2 after doing work is sent to the CO2 low-pressure compression tank 19.

[0075] According to the difference between the theoretical output power of the peak-shaving power generation system and the target grid-connected power, the flow of the CO2 high-pressure energy release pipeline 26 is controlled, and the second isolating switch 38 on the second transmission line 36 is closed to increase the grid-connected power of the expander generator 28, thereby increasing the grid-connected power of the peak-shaving power generation system, so that the actual grid-connected power of the peak-shaving power generation system reaches the target grid-connected power.

[0076] Disconnect the isolation valves 39 on the first steam pipeline 6, the second steam pipeline 7, the third steam pipeline 8, and the fourth steam pipeline 9, and cut off the main steam pipeline 4, the reheat steam pipeline 5, and the steam extraction of the steam turbine 2. Close the isolation valve 39 on the steam generation pipeline 45, use the power generated by the photovoltaic generator 23 to generate steam through the steam generator 34, and provide energy to the reboiler 12; at the same time, the photovoltaic generator 23 uses the energy storage device 22 to store the remaining electricity generated. When the power generated by the photovoltaic generator 23 is insufficient, disconnect the third isolation switch 44, use the energy storage device 22 to generate steam through the steam generator 34, and provide energy to the reboiler 12.

[0077] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A peak-shaving power generation system of coal-fired units coupled with carbon dioxide compression energy storage, characterized in that: include: Coal-fired boiler (1), steam turbine (2), steam turbine generator (3), main steam pipeline (4), reheat steam pipeline (5), first steam pipeline (6), second steam pipeline (7), third steam pipeline (8), fourth steam pipeline (9), tail flue of coal-fired boiler (10), flue gas pipeline (11), reboiler (12), absorption tower (13), regeneration tower (14), rich liquid pump (15), lean liquid pump (16), CO2 low-pressure compression device (17), CO2 multi-stage compression device (18), CO2 low-pressure storage tank (19), CO2 high-pressure storage tank (20), photovoltaic power generation system (21), energy storage device (22), photovoltaic generator (23), CO2 low-pressure compression pipeline (24), CO2 high-pressure compression pipeline (25), CO2 high-pressure energy release pipeline (26), CO2 expander (27), expander generator (28) and steam generator (34); The first steam pipeline (6) is connected to the main steam pipeline (4) and the reboiler (12); one end of the main steam pipeline (4) is connected to the coal-fired boiler (1), and the other end is connected to the steam turbine (2); the steam turbine generator (3) is driven by the steam turbine (2); the second steam pipeline (7) is connected to the reheat steam pipeline (5) and the reboiler (12); the third steam pipeline (8) and the fourth steam pipeline (9) are both connected to the steam turbine (2) and the reboiler (12), the third steam pipeline and the fourth steam pipeline are connected downstream of the reheat steam inlet of the intermediate pressure cylinder of the steam turbine, and the fourth steam pipeline is located downstream of the third steam pipeline; the flue gas pipeline (11) is connected to the tail flue (10) of the coal-fired boiler and the absorption tower (13), and the tail flue (10) of the coal-fired boiler is arranged at the tail of the coal-fired boiler (1); The rich liquid pump (15) is connected to the absorption tower (13) and the regeneration tower (14); the lean liquid pump (16) is connected to the absorption tower (13) and the regeneration tower (14); The CO2 low-pressure compression pipeline (24) connects the regeneration tower (14) and the CO2 low-pressure storage tank (19), and a CO2 low-pressure compression device (17) is arranged on the pipeline; the CO2 high-pressure compression pipeline (25) connects the regeneration tower (14) and the CO2 high-pressure storage tank (20), and a CO2 multi-stage compression device (18) is arranged on the pipeline; the CO2 high-pressure energy release pipeline (26) connects the CO2 low-pressure storage tank (19) and the CO2 high-pressure storage tank (20), and a CO2 expander (27) is arranged on the pipeline, and the expander generator (28) is driven by the CO2 expander (27); The photovoltaic power generation system (21) is connected to a photovoltaic generator (23), the photovoltaic generator (23) is connected to an energy storage device (22) and a steam generator (34), and the steam generator (34) is connected to a reboiler (12); The steam turbine generator (3) is connected to the power grid (40) via a first power transmission line (35), and the expander generator (28) is connected to the power grid (40) via a second power transmission line (36).

2. The peak-shaving power generation system of coal-fired units coupled with carbon dioxide compression energy storage according to claim 1 is characterized in that: A flue gas flow controller (29) and a CO2 mass fraction detector (30) are arranged on the flue gas pipeline (11), an enthalpy detector (31) is arranged before and after the CO2 low-pressure compression device (17), an enthalpy detector (31) is arranged before and after the CO2 multi-stage compression device (18), and an enthalpy detector (31) is arranged before and after the CO2 expander (27).

3. The peak-shaving power generation system of coal-fired units coupled with carbon dioxide compression energy storage according to claim 1 is characterized in that: An enthalpy detector (31) and a steam flow controller (32) are provided on the first steam pipeline (6), the second steam pipeline (7), the third steam pipeline (8) and the fourth steam pipeline (9), and an enthalpy detector (31) is provided on the exhaust steam pipeline of the reboiler (12).

4. The peak-shaving power generation system of coal-fired units coupled with carbon dioxide compression energy storage according to claim 1 is characterized in that: A CO2 concentration detection device (33) is provided in the absorption tower (13) and the regeneration tower (14).

5. A method for peak-shaving power generation of a coal-fired unit coupled with carbon dioxide compression energy storage, using the peak-shaving power generation system of a coal-fired unit according to any one of claims 1 to 4, characterized in that: include: 1) When it is determined that the power grid is in the off-peak period, according to the theoretical output power of the peak-shaving power generation system and the target grid-connected power, part of the steam generated by the coal-fired unit is extracted to provide energy to the reboiler, and part of the power generated by the steam turbine generator is used to provide energy to the CO2 low-pressure compression device or the CO2 multi-stage compression device, so that the actual grid-connected power of the peak-shaving power generation system reaches the target grid-connected power, so as to quickly reduce the output power of the peak-shaving power generation system; According to the real-time output power of the steam turbine generator, it is determined whether to put the first steam pipeline, the second steam pipeline, the third steam pipeline or the fourth steam pipeline into operation; According to the difference between the theoretical power generation of the peak-shaving power generation system and the target grid-connected power, it is determined whether to put into operation the CO2 low-pressure compression device or the CO2 multi-stage compression device, and the flue gas flow rate of the flue gas pipeline is controlled by the flue gas flow controller and the CO2 mass fraction detector; 2) When it is determined that the power grid is at a peak period of electricity consumption, according to the theoretical output power of the peak-shaving power generation system and the target grid-connected power, the supercritical CO2 stored in the CO2 high-pressure compression tank is sent to the CO2 expander through the CO2 high-pressure energy release pipeline to perform work, thereby increasing the grid-connected power of the expander generator, and then increasing the grid-connected power of the peak-shaving power generation system, so that the actual grid-connected power of the peak-shaving power generation system reaches the target grid-connected power; The main steam pipeline, reheat steam pipeline and steam extraction of the steam turbine are cut off, and the power generated by the photovoltaic generator is used to generate steam to provide energy for the reboiler.

6. The peak-shaving power generation method of a coal-fired unit coupled with carbon dioxide compression energy storage according to claim 5, characterized in that: The energy provided to the reboiler and the power reduction value of the peak-shaving power generation system are expressed as P3=α1×(P2-P1); the energy provided to the CO2 low-pressure compression device or the CO2 multi-stage compression device and the power reduction value of the peak-shaving power generation system are expressed as P4=α2×(P2-P1), α 1+ α2=1; Among them, P2 is the theoretical output power of the peak-shaving power generation system, in J / s; P1 is the target grid-connected power of the peak-shaving power generation system, in J / s; α1 is the reboiler energy coefficient; α2 is the energy coefficient of the CO2 low-pressure compression device or the CO2 multi-stage compression device; When P2-P1<0.3P2, the CO2 low-pressure compression device is put into operation; when P2-P1≥0.3P2, the CO2 multi-stage compression device is put into operation.

7. According to the method for peak-shaving power generation of coal-fired units coupled with carbon dioxide compression energy storage according to claim 6, the expression of the steam extraction flow rate q1 of the first steam pipeline is: in, h1 is the extraction enthalpy of the first steam pipeline, in J / g; h0 is the exhaust enthalpy of the steam turbine, in J / g; η1 is the steam extraction efficiency of the first steam pipeline, in %; The expression of the second steam pipeline extraction steam flow rate q2 is: Wherein, h2 is the extraction enthalpy of the second steam pipeline, in J / g; η2 is the extraction efficiency of the second steam pipeline, in %; The expression of the extraction steam flow rate q3 of the third steam pipeline is: Wherein, h3 is the extraction enthalpy of the third steam pipeline, in J / g; η3 is the extraction efficiency of the third steam pipeline, in %; The expression of the fourth steam pipeline extraction steam flow rate q4 is: Wherein, h4 is the extraction enthalpy of the fourth steam pipeline, in J / g; η4 is the extraction efficiency of the fourth steam pipeline, in %.

8. The peak-shaving power generation method of coal-fired units coupled with carbon dioxide compression energy storage according to claim 6, characterized in that: The expression of the flue gas flow rate q5 of the flue gas pipeline is: Among them, η5 is the efficiency of the carbon capture device, in %; β is the CO2 mass fraction of the flue gas in the flue gas pipeline, in %; γ is the energy consumed by the carbon capture device to process unit mass of CO2, in J / g.

9. The method for peak load regulation power generation of coal-fired units coupled with carbon dioxide compression energy storage according to claim 6, characterized in that: The expression of the CO2 low-pressure compression pipeline flow rate q6 is: Among them, η6 is the efficiency of the CO2 low-pressure compression device, in %; h5 is the CO2 enthalpy value at the outlet of the CO2 low-pressure compression device, in J / g; h6 is the CO2 enthalpy value at the inlet of the CO2 low-pressure compression device, in J / g; the expression of the CO2 high-pressure compression pipeline flow q7 is: Among them, η7 is the efficiency of the CO2 multi-stage compression device, in %; h7 is the CO2 enthalpy value at the outlet of the CO2 multi-stage compression device, in J / g; h8 is the CO2 enthalpy value at the inlet of the CO2 multi-stage compression device, in J / g.

10. The peak-shaving power generation method of a coal-fired unit coupled with carbon dioxide compression energy storage according to claim 6, characterized in that: The expression of the CO2 high-pressure energy release pipeline flow rate q8 is: Wherein, η8 is the efficiency of CO2 expander, in %; h9 is the CO2 enthalpy at the inlet of CO2 expander, in J / g; h 10 It is the enthalpy of CO2 at the outlet of CO2 expander, in J / g.

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