Supercritical carbon dioxide circulating coal-fired power generation system and operation method

Abstract

The invention relates to the technical field of thermal power generation, in particular to a supercritical carbon dioxide circulating coal-fired power generation system and an operation method. The system comprises a boiler, a high-pressure turbine, a low-pressure turbine, a main compressor, a re-compressor, a low-temperature heat regenerator and a high-temperature heat regenerator. Wherein a shunting economizer, an SCR denitration device and a flue gas cooler are sequentially arranged in a tail flue of the boiler in the flue gas flowing direction, an air inlet of the shunting economizer is connected to a cold side air inlet of the high-temperature heat regenerator through a first shunting valve, and an air outlet of the shunting economizer is connected to an air cooling wall air inlet of the boiler; a gas inlet of the flue gas cooler is connected to a cold side gas inlet of the low-temperature heat regenerator through a second diverter valve, and a gas outlet of the flue gas cooler is connected to a cold side gas inlet of the high-temperature heat regenerator. The system not only can improve the operation efficiency of the unit, but also can realize wide-load efficient denitration of the unit.

Description

Technical Field

[0001] The present application relates to the field of thermal power generation technology, and in particular to a supercritical carbon dioxide cycle coal-fired power generation system and an operation method thereof. Background Art

[0002] In recent years, with the rapid development of new energy sources such as photovoltaics and wind power, in order to cope with the power fluctuations caused by the large-scale grid connection of new energy sources, thermal power units are often in low-load conditions and variable load operation, and the operating efficiency is greatly reduced, especially under low-load conditions, the denitrification efficiency is significantly reduced. Although the addition of technologies such as No. 0 high-pressure heater and flue gas bypass can improve the denitrification efficiency under low load, this is achieved at the expense of reducing the operating efficiency of the unit, and it is impossible to take into account both high efficiency and cleanliness. Compared with steam Rankine cycle power generation technology, supercritical carbon dioxide cycle has higher thermal efficiency. When applied to coal-fired power generation units, it can greatly improve the operating efficiency and has broad prospects. However, how to achieve efficient denitrification of coal-fired units under all operating conditions and wide loads will be one of the key issues in the large-scale application of supercritical carbon dioxide coal-fired power generation technology. Summary of the invention

[0003] The embodiments of the present application at least provide a supercritical carbon dioxide cycle coal-fired power generation system and an operation method, which can not only improve the operating efficiency of the unit, but also achieve high-efficiency denitrification of the unit over a wide load.

[0004] In a first aspect, an embodiment of the present application provides a supercritical carbon dioxide cycle coal-fired power generation system, the system comprising:

[0005] A boiler, a high-pressure turbine, a low-pressure turbine, a main compressor, a recompressor, a low-temperature regenerator, and a high-temperature regenerator, wherein the supercritical carbon dioxide outlet of the boiler is respectively connected to the air inlets of the high-pressure turbine and the low-pressure turbine, the air outlet of the high-pressure turbine is connected to the air inlet of the reheater of the boiler, the air outlet of the low-pressure turbine is connected to the air inlets of the main compressor and the recompressor through the hot side of the high-temperature regenerator and the low-temperature regenerator in sequence, the air outlet of the main compressor is connected to the air inlet of the air-cooled wall of the boiler through the cold side of the low-temperature regenerator and the high-temperature regenerator in sequence, and the air outlet of the recompressor is connected to the hot side air inlet of the high-temperature regenerator;

[0006] Among them, a diverter economizer, an SCR denitrification device and a flue gas cooler are arranged in sequence along the flue gas flow direction in the tail flue of the boiler, the air inlet of the diverter economizer is connected to the cold side air inlet of the high-temperature regenerator through a first diverter valve, the air outlet of the diverter economizer is connected to the air inlet of the air-cooled wall of the boiler, the air inlet of the flue gas cooler is connected to the cold side air inlet of the low-temperature regenerator through a second diverter valve, and the air outlet of the flue gas cooler is connected to the cold side air inlet of the high-temperature regenerator.

[0007] In an optional embodiment, the system further includes a primary air preheater and a secondary air preheater, wherein the primary air preheater is arranged in parallel with the flue gas cooler, and the secondary air preheater is located downstream of the SCR denitrification device and upstream of the flue gas cooler, and the primary air preheater is used to use the flue gas to preheat the primary air and secondary air required by the boiler, and send the preheated primary air into the boiler, and send the preheated secondary air into the secondary air preheater, and the secondary air preheater is used to use the flue gas to heat the preheated secondary air again, and send the preheated secondary air into the boiler.

[0008] In an optional embodiment, the system also includes a primary air preheater and a secondary air preheater, and the primary air preheater and the secondary air preheater are respectively connected between the hot side air outlet of the low-temperature reheater and the air inlet of the main compressor. The primary air preheater is used to preheat the primary air with the working fluid and send the primary air into the primary air preheater, and the secondary air preheater is used to preheat the secondary air with the working fluid and send the secondary air into the primary air preheater.

[0009] In an optional embodiment, two independent first flues and second flues are provided in the tail flue of the boiler, the first flue is provided with the primary air preheater, the second flue is provided with the flue gas cooler, the first flue is provided with a first regulating baffle, the first regulating baffle is used to regulate the flue gas flow of the first flue, and the second flue is provided with a second regulating baffle, the second regulating baffle is used to regulate the flue gas flow of the second flue.

[0010] In a second aspect, the present application also provides an operating method of a supercritical carbon dioxide cycle coal-fired power generation system, the method comprising:

[0011] The supercritical carbon dioxide heated by the boiler is fed into the high-pressure turbine to expand and perform work;

[0012] The supercritical carbon dioxide after expansion and work is sent to the reheater of the boiler to be heated again and then sent to the low-pressure turbine to do work;

[0013] The supercritical carbon dioxide after cooling becomes working fluid exhaust gas, which is divided into two paths through the high-temperature regenerator and the low-temperature regenerator, one path is sent to the main compressor, and the other path is sent to the recompressor;

[0014] The working medium exhaust gas passing through the recompressor becomes high-pressure supercritical carbon dioxide, and the high-pressure supercritical carbon dioxide is fed into the cold side air inlet of the high-temperature regenerator;

[0015] The working medium exhaust gas passing through the main compressor becomes high-pressure supercritical carbon dioxide, which is divided into two paths, one of which passes through the low-temperature regenerator and is sent to the cold side air inlet of the high-temperature regenerator, and the other passes through the flue gas cooler and is heated before returning to the cold side air inlet of the high-temperature regenerator;

[0016] The high-pressure supercritical carbon dioxide is divided into two paths before the cold-side air inlet of the high-temperature regenerator. One path is heated by the high-temperature regenerator and then sent to the boiler, and the other path is heated by the split economizer and then sent to the boiler.

[0017] In an optional embodiment, the method further includes: adjusting the first diverter valve to control the inlet flue gas temperature of the SCR denitration device.

[0018] In an optional embodiment, the system further includes a primary air preheater and a secondary air preheater, the primary air preheater and the flue gas cooler are arranged in parallel, the secondary air preheater is located downstream of the SCR denitrification device and upstream of the flue gas cooler, and the method further includes: the primary air is preheated by the primary air preheater and then sent to the boiler; the secondary air is preheated by the primary air preheater and then sent to the secondary air preheater, and the heated air is heated again by the secondary air preheater and then sent to the boiler.

[0019] In an optional embodiment, the system further includes a primary air preheater and a secondary air preheater, and the primary air preheater and the secondary air preheater are respectively connected between the hot side air outlet of the low-temperature reheater and the air inlet of the main compressor, and the method further includes: the primary air is preheated by the primary air preheater and then sent to the primary air preheater; the secondary air is preheated by the secondary air preheater and then sent to the primary air preheater.

[0020] In an optional embodiment, two independent first flues and second flues are provided in the tail flue of the boiler, the first flue is provided with the primary air preheater, the second flue is provided with the flue gas cooler, the first flue is provided with a first adjusting baffle, the second flue is provided with a second adjusting baffle, and the method further includes: adjusting the first adjusting baffle and the second adjusting baffle to control the temperature of the primary air after preheating by the primary air preheater.

[0021] In an optional embodiment, during the process of adjusting the first adjusting baffle and the second adjusting baffle, the method further includes: adjusting the second diverter valve to control the high-pressure supercritical carbon dioxide flow of the flue gas cooler.

[0022] The above technical solution of the present application has the following beneficial technical effects:

[0023] The supercritical carbon dioxide cycle coal-fired power generation system and operation method of the embodiment of the present application can fully utilize the waste heat of flue gas to preheat supercritical carbon dioxide, and can ensure the inlet flue gas temperature of the SCR denitrification device by adjusting the flow rate of supercritical carbon dioxide. The system can not only improve the operating efficiency of the unit, but also realize high-efficiency denitrification of the unit under wide load.

[0024] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present application and are used together with the specification to illustrate the technical solutions of the present application. It should be understood that the following drawings only illustrate certain embodiments of the present application and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can also be obtained based on these drawings without creative work.

[0026] Figure 1 A schematic diagram of a supercritical carbon dioxide cycle coal-fired power generation system provided in an embodiment of the present application is shown;

[0027] Reference numerals:

[0028] 1. Diverter economizer; 2. SCR denitrification device; 3. Flue gas cooler; 4. First diverter valve; 5. Second diverter valve; 6. Primary air preheater; 7. Secondary air preheater; 8. Primary air preheater; 9. Secondary air preheater; 10. First regulating damper; 11. Second regulating damper. DETAILED DESCRIPTION

[0029] The present application is further described below in conjunction with the accompanying drawings and embodiments.

[0030] Improving the initial parameters of power plant steam can improve the power generation efficiency of thermal power units. However, due to limitations such as metal materials, the steam temperature of existing thermal power units is difficult to further increase and cannot continue to support the improvement of unit operating efficiency. Compared with the steam Rankine cycle used in thermal power plants, the supercritical carbon dioxide cycle has a higher cycle thermal efficiency. If this cycle is applied to 600℃ coal-fired units, the power generation efficiency of 700℃ coal-fired units using steam cycles can be achieved, with huge energy-saving potential.

[0031] In the supercritical carbon dioxide cycle coal-fired power generation system, due to the high temperature of the carbon dioxide working fluid at the boiler inlet, which can generally reach 400℃ or even 500℃, the high boiler inlet temperature will cause the boiler exhaust temperature to rise significantly, and a large amount of flue gas preheating will be discharged and wasted. In addition, like the steam unit coal-fired boiler, the supercritical carbon dioxide coal-fired boiler also has the problem of low SCR denitrification efficiency under low load conditions.

[0032] To this end, the present application embodiment proposes an efficient and clean supercritical carbon dioxide cycle coal-fired power generation system and operation method, which can not only improve the unit operation efficiency, but also achieve efficient denitrification of the unit over a wide load. The structure and working process of the present application are described in detail below.

[0033] like Figure 1 As shown, the supercritical carbon dioxide cycle coal-fired power generation system of the embodiment of the present application includes: a boiler, a high-pressure turbine, a low-pressure turbine, a main compressor, a recompressor, a low-temperature regenerator, and a high-temperature regenerator. The supercritical carbon dioxide outlet of the boiler is respectively connected to the air inlets of the high-pressure turbine and the low-pressure turbine, the air outlet of the high-pressure turbine is connected to the air inlet of the boiler's reheater, the air outlet of the low-pressure turbine is connected to the air inlet of the main compressor and the recompressor through the hot side of the high-temperature regenerator and the low-temperature regenerator in sequence, the air outlet of the main compressor is connected to the air inlet of the air-cooled wall of the boiler through the cold side of the low-temperature regenerator and the high-temperature regenerator in sequence, and the air outlet of the recompressor is connected to the hot side air inlet of the high-temperature regenerator. During use, the supercritical carbon dioxide heated by the boiler is sent to the high-pressure turbine for expansion to do work. The supercritical carbon dioxide after expansion is sent to the reheater of the boiler for reheating and then sent to the low-pressure turbine to do work. The supercritical carbon dioxide after cooling becomes working fluid exhaust gas. The working fluid exhaust gas passes through the hot side of the high-temperature regenerator and the low-temperature regenerator and is divided into two paths. One path is sent to the main compressor after being cooled by the precooler, and the other path is sent to the recompressor. The working fluid exhaust gas compressed by the recompressor becomes high-pressure supercritical carbon dioxide and is sent to the cold side air inlet of the high-temperature regenerator. The working fluid exhaust gas compressed by the main compressor becomes high-pressure supercritical carbon dioxide and is heated by the low-temperature regenerator and then sent to the cold side air inlet of the high-temperature regenerator. The two paths of high-pressure supercritical carbon dioxide converge in front of the cold side air inlet of the high-temperature regenerator and are heated by the high-temperature regenerator and then sent to the gas-cooled wall of the boiler.

[0034] Furthermore, a diverter economizer 1, an SCR denitrification device 2 and a flue gas cooler 3 are sequentially arranged in the tail flue of the boiler along the flue gas flow direction, the air inlet of the diverter economizer 1 is connected to the cold side air inlet of the high-temperature regenerator through a first diverter valve 4, the air outlet of the diverter economizer 1 is connected to the air inlet of the air-cooled wall of the boiler, the air inlet of the flue gas cooler 3 is connected to the cold side air inlet of the low-temperature regenerator through a second diverter valve 5, and the air outlet of the flue gas cooler 3 is connected to the cold side air inlet of the high-temperature regenerator. During use, the second diverter valve 5 can divert part of the high-pressure supercritical carbon dioxide from the cold side air inlet of the low-temperature regenerator to the flue gas cooler 3, absorb the flue gas waste heat in the downstream flue of the SCR denitration device and return to the cold side air inlet of the high-temperature regenerator. The first diverter valve 4 can divert part of the high-pressure supercritical carbon dioxide from the cold side air inlet of the high-temperature regenerator to the diverter economizer 1, absorb the flue gas waste heat in the upstream flue of the SCR denitration device and send it to the boiler air-cooled wall. In addition, by adjusting the first diverter valve 4, the flow rate of high-pressure supercritical carbon dioxide can also be controlled to ensure that the inlet flue gas temperature of the SCR denitration device 2 meets the SCR denitration working temperature range (300℃~400℃). For example, if the inlet flue gas temperature of the SCR denitration device 2 is lower than the lower limit of the denitration working temperature, the opening of the first diverter valve 4 is reduced. If the inlet flue gas temperature of the SCR denitration device 2 is higher than the lower limit of the denitration working temperature, the opening of the first diverter valve 4 is increased. This arrangement can fully utilize the waste heat of flue gas to preheat supercritical carbon dioxide, and can ensure the inlet flue gas temperature of the SCR denitrification device 2 by adjusting the flow rate of supercritical carbon dioxide. The system can not only improve the operating efficiency of the unit, but also achieve high-efficiency denitrification of the unit under wide load.

[0035] In some embodiments, the system further includes a primary air preheater 6 and a secondary air preheater 7. The primary air preheater 6 is arranged in parallel with the flue gas cooler 3. The secondary air preheater 7 is located downstream of the SCR denitrification device 2 and upstream of the flue gas cooler 3. The primary air preheater 6 is used to use the flue gas to preheat the primary air and secondary air required by the boiler, and send the preheated primary air into the boiler, and send the preheated secondary air into the secondary air preheater 7. The secondary air preheater 7 is used to use the flue gas to reheat the preheated secondary air, and send the preheated secondary air into the boiler. During use, the primary air is preheated by the primary air preheater 6 and then sent to the boiler, and the secondary air is preheated by the primary air preheater 6 and then sent to the secondary air preheater 7. The heated air is reheated by the secondary air preheater 7 and then sent to the boiler. Specifically, in this way, the waste heat of the flue gas in the flue downstream of the SCR denitrification device can be used to obtain the primary air and secondary air required by the boiler.

[0036] In some embodiments, the system further includes a primary air preheater 8 and a secondary air preheater 9, which are respectively connected between the hot side air outlet of the low-temperature regenerator and the air inlet of the main compressor. The primary air preheater 8 is used to preheat the primary air with the working fluid and send the primary air into the primary air preheater 6, and the secondary air preheater 9 is used to preheat the secondary air with the working fluid and send the secondary air into the primary air preheater 6. During use, the primary air is preheated by the primary air preheater 8 and then sent to the primary air preheater 6, and the secondary air is preheated by the secondary air preheater 9 and then sent to the primary air preheater 6. Specifically, the waste heat of the working fluid exhaust gas can be used to preheat the primary air and the secondary air.

[0037] In some embodiments, two independent first flues and second flues are provided in the tail flue of the boiler, a primary air preheater 6 is provided in the first flue, a flue gas cooler 3 is provided in the second flue, a first regulating damper 10 is provided in the first flue, and the first regulating damper 10 is used to regulate the flue gas flow rate of the first flue, and a second regulating damper 11 is provided in the second flue, and the second regulating damper 11 is used to regulate the flue gas flow rate of the second flue. During use, the opening of the first regulating damper 10 and the second regulating damper 11 can be adjusted to increase or decrease the flue gas flow rate of the first flue, thereby controlling the temperature of the primary air after preheating by the primary air preheater 6. For example, when the temperature of the primary air is lower than the set value (about 110°C), the opening of the first regulating damper 10 is increased and the opening of the first regulating damper 10 is decreased. When the temperature of the primary air is higher than the set value, the opening of the first regulating damper 10 is decreased and the opening of the first regulating damper 10 is increased. It should be understood that in the process of adjusting the first adjusting baffle 10 and the second adjusting baffle 11, the flue gas flow rate of the second flue changes, and the flow rate of high-pressure supercritical carbon dioxide can be controlled by adjusting the second diverter valve 5 to ensure the temperature of the high-pressure supercritical carbon dioxide after heating in the flue gas cooler 3.

[0038] The present application also provides an operation method of a supercritical carbon dioxide cycle coal-fired power generation system, the method comprising:

[0039] The supercritical carbon dioxide heated by the boiler is sent to the high-pressure turbine to expand and do work;

[0040] After the expansion and work, the supercritical carbon dioxide is sent to the reheater of the boiler to be heated again and then sent to the low-pressure turbine to do work;

[0041] The supercritical carbon dioxide after cooling becomes the working fluid exhaust gas, which is divided into two paths through the high-temperature regenerator and the low-temperature regenerator, one path is sent to the main compressor, and the other path is sent to the recompressor;

[0042] The working medium exhaust gas after the recompressor becomes high-pressure supercritical carbon dioxide, which is fed into the cold side air inlet of the high-temperature regenerator;

[0043] The working medium exhaust gas after the main compressor becomes high-pressure supercritical carbon dioxide, which is divided into two paths. One path is sent to the cold side air inlet of the high-temperature regenerator through the low-temperature regenerator, and the other path is heated by the flue gas cooler 3 and then returns to the cold side air inlet of the high-temperature regenerator.

[0044] The high-pressure supercritical carbon dioxide is divided into two paths before the cold-side air inlet of the high-temperature regenerator. One path is heated by the high-temperature regenerator and then sent to the boiler, and the other path is heated by the split economizer 1 and then sent to the boiler.

[0045] In some embodiments, the method further comprises:

[0046] The first diverter valve 4 is adjusted to control the inlet flue gas temperature of the SCR denitration device 2 .

[0047] Specifically, the flow rate of high-pressure supercritical carbon dioxide can also be controlled by adjusting the first diverter valve 4 to ensure that the inlet flue gas temperature of the SCR denitrification device 2 meets the SCR denitrification operating temperature range (300°C~400°C). For example, if the inlet flue gas temperature of the SCR denitrification device 2 is lower than the lower limit of the denitrification operating temperature, the opening of the first diverter valve 4 is reduced; if the inlet flue gas temperature of the SCR denitrification device 2 is higher than the lower limit of the denitrification operating temperature, the opening of the first diverter valve 4 is increased.

[0048] In some embodiments, the method further comprises:

[0049] The primary air is preheated by the primary air preheater 6 and then sent to the boiler;

[0050] The secondary air is preheated by the primary air preheater 6 and then sent to the secondary air preheater 7. The heated secondary air is heated again by the secondary air preheater 7 and then sent to the boiler.

[0051] Specifically, the primary air and the secondary air can utilize the waste heat of the flue gas to achieve the temperature required for the use of the boiler.

[0052] In some embodiments, the method further comprises:

[0053] The primary air is preheated by the primary air preheater 8 and then sent to the primary air preheater 6;

[0054] The secondary air is preheated by the secondary air preheater 9 and then sent to the primary air preheater 6.

[0055] Specifically, before utilizing the waste heat of the flue gas for waste heat recovery, the primary air and the secondary air may be preheated using the waste heat of the working medium exhaust gas.

[0056] In some embodiments, the method further comprises:

[0057] The first regulating damper 10 and the second regulating damper 11 are adjusted to control the temperature of the primary air after being preheated by the primary air preheater 6 .

[0058] Specifically, when the temperature of the primary air is lower than the set value (about 110°C), the opening of the first adjusting damper 10 is increased and the opening of the first adjusting damper 10 is decreased; when the temperature of the primary air is higher than the set value, the opening of the first adjusting damper 10 is decreased and the opening of the first adjusting damper 10 is increased.

[0059] In some embodiments, during the process of adjusting the first adjustment baffle 10 and the second adjustment baffle 11, the method further includes:

[0060] The second diverter valve 5 is adjusted to control the flow rate of high-pressure supercritical carbon dioxide in the flue gas cooler 3 .

[0061] Specifically, in the process of adjusting the first adjustment baffle 10 and the second adjustment baffle 11, the flue gas flow rate of the second flue changes, and the flow rate of high-pressure supercritical carbon dioxide can be controlled by adjusting the second diverter valve 5 to ensure the temperature of the high-pressure supercritical carbon dioxide after heating in the flue gas cooler 3.

[0062] The term "first" or "second" in the specification and claims of this application may include one or more of the features explicitly or implicitly. In the description of this application, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the objects connected before and after are in an "or" relationship.

[0063] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" 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 application 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 a limitation on the present application.

[0064] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0065] One or more embodiments of this specification are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification should be included in the scope of protection of this application.

[0066] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A supercritical carbon dioxide cycle coal-fired power generation system, characterized in that: The system comprises: A boiler, a high-pressure turbine, a low-pressure turbine, a main compressor, a recompressor, a low-temperature regenerator, and a high-temperature regenerator, wherein the supercritical carbon dioxide outlet of the boiler is respectively connected to the air inlets of the high-pressure turbine and the low-pressure turbine, the air outlet of the high-pressure turbine is connected to the air inlet of the reheater of the boiler, the air outlet of the low-pressure turbine is connected to the air inlets of the main compressor and the recompressor through the hot side of the high-temperature regenerator and the low-temperature regenerator in sequence, the air outlet of the main compressor is connected to the air inlet of the air-cooled wall of the boiler through the cold side of the low-temperature regenerator and the high-temperature regenerator in sequence, and the air outlet of the recompressor is connected to the hot side air inlet of the high-temperature regenerator; Among them, a diverter economizer, an SCR denitrification device and a flue gas cooler are arranged in sequence along the flue gas flow direction in the tail flue of the boiler, the air inlet of the diverter economizer is connected to the cold side air inlet of the high-temperature regenerator through a first diverter valve, the air outlet of the diverter economizer is connected to the air inlet of the air-cooled wall of the boiler, the air inlet of the flue gas cooler is connected to the cold side air inlet of the low-temperature regenerator through a second diverter valve, and the air outlet of the flue gas cooler is connected to the cold side air inlet of the high-temperature regenerator.

2. The supercritical carbon dioxide cycle coal-fired power generation system according to claim 1, characterized in that: The system also includes a primary air preheater and a secondary air preheater. The primary air preheater is arranged in parallel with the flue gas cooler. The secondary air preheater is located downstream of the SCR denitrification device and upstream of the flue gas cooler. The primary air preheater is used to use flue gas to preheat the primary air and secondary air required by the boiler, and send the preheated primary air into the boiler, and send the preheated secondary air into the secondary air preheater. The secondary air preheater is used to use flue gas to heat the preheated secondary air again, and send the preheated secondary air into the boiler.

3. The supercritical carbon dioxide cycle coal-fired power generation system according to claim 2, characterized in that: The system also includes a primary air preheater and a secondary air preheater, wherein the primary air preheater and the secondary air preheater are respectively connected between the hot side air outlet of the low-temperature regenerator and the air inlet of the main compressor, the primary air preheater is used to preheat the primary air with the working fluid and send the primary air into the primary air preheater, and the secondary air preheater is used to preheat the secondary air with the working fluid and send the secondary air into the primary air preheater.

4. The supercritical carbon dioxide cycle coal-fired power generation system according to claim 2, characterized in that: Two independent first flues and second flues are arranged in the tail flue of the boiler, the first flue is provided with the primary air preheater, the second flue is provided with the flue gas cooler, the first flue is provided with a first regulating baffle, the first regulating baffle is used to regulate the flue gas flow of the first flue, and the second flue is provided with a second regulating baffle, the second regulating baffle is used to regulate the flue gas flow of the second flue.

5. An operation method, applicable to the supercritical carbon dioxide cycle coal-fired power generation system according to any one of claims 1 to 4, characterized in that: The method comprises: The supercritical carbon dioxide heated by the boiler is fed into the high-pressure turbine to expand and perform work; The supercritical carbon dioxide after expansion and work is sent to the reheater of the boiler to be heated again and then sent to the low-pressure turbine to do work; The supercritical carbon dioxide after cooling becomes working fluid exhaust gas, which is divided into two paths through the high-temperature regenerator and the low-temperature regenerator, one path is sent to the main compressor, and the other path is sent to the recompressor; The working medium exhaust gas passing through the recompressor becomes high-pressure supercritical carbon dioxide, and the high-pressure supercritical carbon dioxide is fed into the cold side air inlet of the high-temperature regenerator; The working medium exhaust gas passing through the main compressor becomes high-pressure supercritical carbon dioxide, which is divided into two paths, one of which passes through the low-temperature regenerator and is sent to the cold side air inlet of the high-temperature regenerator, and the other passes through the flue gas cooler and is heated before returning to the cold side air inlet of the high-temperature regenerator; The high-pressure supercritical carbon dioxide is divided into two paths before the cold-side air inlet of the high-temperature regenerator. One path is heated by the high-temperature regenerator and then sent to the boiler, and the other path is heated by the split economizer and then sent to the boiler.

6. The method according to claim 5, characterized in that The method further comprises: The first diverter valve is adjusted to control the inlet flue gas temperature of the SCR denitration device.

7. The method according to claim 5, characterized in that The system further includes a primary air preheater and a secondary air preheater, wherein the primary air preheater is arranged in parallel with the flue gas cooler, and the secondary air preheater is located downstream of the SCR denitration device and upstream of the flue gas cooler. The method further includes: The primary air is preheated by the primary air preheater and then sent to the boiler; The secondary air is preheated by the primary air preheater and then sent to the secondary air preheater. The heated secondary air is heated again by the secondary air preheater and then sent to the boiler.

8. The method according to claim 7, characterized in that The system further includes a primary air preheater and a secondary air preheater, wherein the primary air preheater and the secondary air preheater are respectively connected between a hot side air outlet of the low temperature regenerator and an air inlet of the main compressor, and the method further includes: The primary air is preheated by the primary air preheater and then sent to the primary air preheater; The secondary air is preheated by the secondary air preheater and then sent to the primary air preheater.

9. The method according to claim 7, characterized in that: The tail flue of the boiler is provided with two independent first flues and second flues, the first flue is provided with the primary air preheater, the second flue is provided with the flue gas cooler, the first flue is provided with a first regulating baffle, the second flue is provided with a second regulating baffle, and the method further includes: The first regulating damper and the second regulating damper are adjusted to control the temperature of the primary air after being preheated by the primary air preheater.

10. The method according to claim 9, characterized in that During the process of adjusting the first adjustment baffle and the second adjustment baffle, the method further includes: The second diverter valve is adjusted to control the high-pressure supercritical carbon dioxide flow rate of the flue gas cooler.

Images