A hydrogen-based fuel low-load combustion-supporting system suitable for a tangentially-fired pulverized coal boiler and a method for operating the same

Abstract

The present application belongs to the field of coal combustion stabilization and low-carbon clean power generation technology, and discloses a hydrogen-based fuel low-load combustion-supporting system suitable for a four-corner tangentially cut coal powder boiler and an operation method thereof. The four corners of the four-corner tangentially cut coal powder boiler are each provided with a plurality of coal powder burners. At each corner of the boiler, the plurality of coal powder burners are distributed at intervals from top to bottom. An ammonia gas nozzle and / or a hydrogen gas nozzle are arranged at positions between the coal powder burners. The boiler is provided with an ammonia gas nozzle at a SOFA air nozzle. When the positions between the coal powder burners are simultaneously provided with the ammonia gas nozzle and the hydrogen gas nozzle, the ammonia gas nozzle is arranged above the hydrogen gas nozzle. An ammonia gas outlet of a liquid ammonia gasification and storage supply system is connected with the ammonia gas nozzle, and a hydrogen gas outlet of a hydrogen gas production, storage and supply system is connected with the hydrogen gas nozzle. The present application can realize hydrogen-ammonia blending combustion and combustion support under low-load working conditions of a coal-fired unit, so as to maximize the carbon and nitrogen reduction level of the unit while stabilizing the operation of the boiler.

Description

Technical Field

[0001] This invention belongs to the field of stable coal combustion and low-carbon clean power generation technology, specifically relating to a hydrogen-based fuel low-load combustion assist system and its operation method suitable for a four-corner tangential pulverized coal boiler. Background Technology

[0002] The goal of "peak carbon and carbon neutrality" poses a severe challenge to traditional major carbon emitters like coal-fired power plant boilers. To accelerate energy-saving upgrades and flexibility modifications of existing units, coal-fired power plants face urgent pressure regarding carbon dioxide emissions and the need for flexible peak-shaving. On the other hand, to fully absorb the increasing amount of renewable energy generated, using surplus renewable energy to produce "green hydrogen" or synthesize "green ammonia" has become a new energy storage trend.

[0003] As the cleanest fuel on Earth, hydrogen's direct co-firing in coal-fired boilers is still immature due to its wide explosion limits and rapid combustion speed. Currently, it is only used in small quantities in gas turbines to replace natural gas for carbon reduction. Ammonia, as a hydrogen-based fuel, has a more mature synthesis and supporting processes, lower storage and transportation costs, and higher safety compared to hydrogen. It can achieve zero carbon emissions throughout its entire life cycle, making it an effective carrier of hydrogen and energy. However, ammonia has problems such as high ignition energy and difficulty in ignition. While there is considerable research on ammonia co-firing for carbon reduction in coal-fired boilers, it has not yet addressed carbon reduction and stable combustion during the deep peak-shaving phase of coal-fired power units. Therefore, how to achieve carbon emission reduction in coal-fired boilers while ensuring the safe and stable operation of units during deep peak-shaving is a problem that needs to be considered in the future intelligent, efficient, and flexible upgrading of coal-fired power units. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a hydrogen-based fuel low-load combustion assist system and its operation method suitable for a four-corner tangential pulverized coal boiler. This invention can achieve hydrogen-ammonia co-firing combustion assist under low-load conditions of coal-fired units, so as to maximize the carbon and nitrogen reduction level of the unit while ensuring stable boiler operation.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A hydrogen-based fuel low-load combustion assist system suitable for a tangentially shaped pulverized coal boiler includes a coal-fired boiler hydrogen-ammonia combustion assist system, a liquid ammonia gasification and storage supply system, a hydrogen production, storage and supply system, and a power supply system.

[0007] Among them, the hydrogen-ammonia combustion-supporting system for coal-fired boilers includes a four-cornered tangential pulverized coal boiler, with several pulverized coal burners installed at each of the four corners of the four-cornered tangential pulverized coal boiler.

[0008] In each corner of the tangential pulverized coal boiler, several pulverized coal burners are distributed at intervals from top to bottom. Ammonia and / or hydrogen nozzles are arranged between the pulverized coal burners. The tangential pulverized coal boiler has an ammonia nozzle at the SOFA air nozzle. When both ammonia and hydrogen nozzles are arranged between the pulverized coal burners, the ammonia nozzle is located above the hydrogen nozzle.

[0009] The ammonia outlet of the liquid ammonia vaporization and storage supply system is connected to the ammonia nozzle, and the hydrogen outlet of the hydrogen production, storage and supply system is connected to the hydrogen nozzle. Both the liquid ammonia vaporization and storage supply system and the hydrogen production, storage and supply system are connected to the power supply system.

[0010] Preferably, at each corner of the pulverized coal boiler with a tangential shape, the pulverized coal burner includes a first layer of pulverized coal burners, a second layer of pulverized coal burners, a third layer of pulverized coal burners, a fourth layer of pulverized coal burners, and a fifth layer of pulverized coal burners spaced apart from bottom to top. A first layer of hydrogen nozzles is provided between the first layer of pulverized coal burners and the second layer of pulverized coal burners; a second layer of hydrogen nozzles and a first layer of ammonia nozzles are provided between the second layer of pulverized coal burners and the third layer of pulverized coal burners, wherein the second layer of hydrogen nozzles is located below the first layer of ammonia nozzles; a third layer of hydrogen nozzles and a second layer of ammonia nozzles are provided between the third layer of pulverized coal burners and the fourth layer of pulverized coal burners, wherein the third layer of hydrogen nozzles is located below the second layer of ammonia nozzles.

[0011] Preferably, each ammonia nozzle is equipped with an ammonia flow regulating valve on its inlet pipe.

[0012] Preferably, each hydrogen nozzle is equipped with a hydrogen flow regulating valve on its inlet pipe.

[0013] Preferably, the liquid ammonia vaporization and storage supply system includes a liquid ammonia storage tank, a liquid ammonia evaporator, and an ammonia gas storage tank. The outlet of the liquid ammonia storage tank is connected to the inlet of the liquid ammonia evaporator, the power interface of the liquid ammonia evaporator is connected to the power supply system, the ammonia gas outlet of the liquid ammonia evaporator is connected to the inlet of the ammonia gas storage tank, and the ammonia gas outlet of the ammonia gas storage tank is connected to an ammonia gas nozzle. The liquid ammonia storage tank outlet is equipped with a liquid ammonia storage tank outlet flow regulating valve, the liquid ammonia evaporator inlet is equipped with a liquid ammonia evaporator inlet flow regulating valve, and the ammonia gas storage tank outlet is equipped with an ammonia gas storage tank outlet flow regulating valve.

[0014] Preferably, the hydrogen production, storage and supply system includes an electrolytic hydrogen production cell and a hydrogen storage tank. The power interface of the electrolytic hydrogen production cell is connected to the power supply system. The hydrogen outlet of the electrolytic hydrogen production cell is connected to the hydrogen inlet of the hydrogen storage tank. The hydrogen outlet of the hydrogen storage tank is connected to a hydrogen nozzle. The hydrogen outlet of the hydrogen storage tank is equipped with a hydrogen storage tank outlet flow regulating valve.

[0015] Preferably, the power supply system includes a DC power supply, an AC power supply, a solar photovoltaic panel, and a wind turbine. The solar photovoltaic panel is connected to the DC power supply, the DC power supply is connected to the power interface of the hydrogen production, storage, and supply system, the wind turbine is connected to the AC power supply, and the AC power supply is connected to the liquid ammonia vaporization, storage, and supply system. The DC power supply is connected to the AC power supply.

[0016] The present invention also provides a method for operating the hydrogen-based fuel low-load combustion-supporting system applicable to a tangential pulverized coal boiler, comprising the following processes:

[0017] During the gradual reduction of load, the four-corner tangential pulverized coal boiler first injects hydrogen into the boiler through the hydrogen nozzle located at the bottom for combustion. After the load stabilizes, hydrogen is injected into the boiler through the ammonia nozzle, and ammonia is injected into the boiler through the hydrogen nozzle. The injected ammonia and hydrogen participate in combustion in the furnace. The ammonia injected through the ammonia nozzle at the SOFA air nozzle is used to reduce some of the nitrogen oxides produced by combustion.

[0018] Preferably, the low-load operating condition of the tangential pulverized coal boiler is the operating condition at or below the 40% heat rate acceptance load. Under the low-load condition, the total blending ratio of ammonia and hydrogen is no more than 30% of the equivalent calorific value of the designed coal consumption under this load, and the total blending ratio of hydrogen accounts for 10% to 40% of the total blending calorific value under this load.

[0019] Preferably, at each corner of the pulverized coal boiler with a tangential shape, the pulverized coal burner includes a first layer of pulverized coal burners, a second layer of pulverized coal burners, a third layer of pulverized coal burners, a fourth layer of pulverized coal burners, and a fifth layer of pulverized coal burners spaced apart from bottom to top. A first layer of hydrogen nozzles is provided between the first layer of pulverized coal burners and the second layer of pulverized coal burners; a second layer of hydrogen nozzles and a first layer of ammonia nozzles are provided between the second layer of pulverized coal burners and the third layer of pulverized coal burners, wherein the second layer of hydrogen nozzles is located below the first layer of ammonia nozzles; a third layer of hydrogen nozzles and a second layer of ammonia nozzles are provided between the third layer of pulverized coal burners and the fourth layer of pulverized coal burners, wherein the third layer of hydrogen nozzles is located below the second layer of ammonia nozzles.

[0020] The proportions of ammonia injected into the first, second, and third ammonia nozzles are 40%±2%, 50%±2%, and 10%±2% of the total ammonia co-firing amount, respectively.

[0021] The proportions of hydrogen injected into the first, second, and third hydrogen nozzles are 40%±2%, 30%±2%, and 30%±2% of the total hydrogen co-firing amount, respectively.

[0022] The present invention has the following beneficial effects:

[0023] This invention arranges ammonia and / or hydrogen nozzles between the pulverized coal burners on a tangentially circular pulverized coal boiler. These nozzles enable stratified blending of hydrogen and ammonia, achieving both ammonia-based carbon reduction under low load conditions and stable combustion within the furnace using hydrogen, ensuring safe and efficient operation of the unit during deep peak shaving. By coupling a renewable energy power supply system (i.e., a liquid ammonia vaporization and storage supply system, and a hydrogen production, storage, and supply system), it not only reduces carbon emissions from the coal-fired boiler but also provides system redundancy, improving the stability of the hydrogen-ammonia combustion-supporting system, the liquid ammonia vaporization and storage supply system, and the hydrogen production, storage, and supply system. Furthermore, by arranging ammonia nozzles at the SOFA (Solar Air Facilitator) airflow, some nitrogen oxides generated in the main combustion zone can be reduced, eliminating the impact of increased nitrogen oxide concentrations caused by ammonia blending and reducing the difficulty of achieving pollutant emission standards for coal-fired boilers during deep peak shaving. In summary, this invention reduces carbon emissions and controls nitrogen oxide emissions within limits during the deep peak-shaving phase of coal-fired power units by co-firing hydrogen-based fuels at low loads in coal-fired boilers. This is of great significance for coal-fired power units to achieve carbon emission reduction and improve their intelligent, efficient, and flexible peak-shaving capabilities under dual carbon targets. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a hydrogen-based fuel low-load combustion-supporting system applicable to a tangential pulverized coal boiler in an embodiment of the present invention.

[0025] Among them, 1 is a tangentially shaped pulverized coal boiler, 2-1 is the first layer of pulverized coal burners, 2-2 is the second layer of pulverized coal burners, 2-3 is the third layer of pulverized coal burners, 2-4 is the fourth layer of pulverized coal burners, 2-5 is the fifth layer of pulverized coal burners, 3-1 is the first layer of ammonia nozzles, 3-2 is the second layer of ammonia nozzles, 3-3 is the third layer of ammonia nozzles, 4-1 is the first layer of hydrogen nozzles, 4-2 is the second layer of hydrogen nozzles, 4-3 is the third layer of hydrogen nozzles, 5-1 is the first layer of ammonia flow regulating valves, 5-2 is the second layer of ammonia flow regulating valves, and 5-3 is the third layer of ammonia flow... 6-1 is the first-layer hydrogen flow regulating valve, 6-2 is the second-layer hydrogen flow regulating valve, 6-3 is the third-layer hydrogen flow regulating valve, 7 is the liquid ammonia storage tank, 8 is the liquid ammonia evaporator, 9 is the ammonia storage tank, 10-1 is the liquid ammonia storage tank outlet flow regulating valve, 10-2 is the liquid ammonia evaporator inlet flow regulating valve, 10-3 is the ammonia storage tank outlet flow regulating valve, 11 is the electrolytic hydrogen production cell, 12 is the hydrogen storage tank, 13 is the hydrogen storage tank outlet flow regulating valve, 14 is the DC power supply, 15 is the AC power supply, 16 is the solar photovoltaic panel, and 17 is the wind turbine generator. Detailed Implementation

[0026] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The embodiments described in the drawings are merely exemplary and are only used to explain the invention, and should not be construed as limiting the invention.

[0027] See Figure 1 This embodiment applies to a low-load hydrogen-based fuel combustion system for a tangentially shaped pulverized coal boiler, including a coal-fired boiler hydrogen-ammonia combustion system, a liquid ammonia gasification and storage supply system, a hydrogen production, storage and supply system, and a power supply system. The coal-fired boiler hydrogen-ammonia combustion system includes a tangentially shaped pulverized coal boiler 1, with several pulverized coal burners at each of its four corners. At each corner of the tangentially shaped pulverized coal boiler 1, several pulverized coal burners are spaced apart from top to bottom, with ammonia and / or hydrogen nozzles arranged between them. The tangentially shaped pulverized coal boiler 1 has an ammonia nozzle at the SOFA air nozzle. When the pulverized coal... When both ammonia and hydrogen nozzles are arranged between burners, the ammonia nozzle is positioned above the hydrogen nozzle. The ammonia outlet of the liquid ammonia vaporization and storage supply system is connected to the ammonia nozzle, and the liquid ammonia vaporization and storage supply system supplies ammonia to the ammonia outlet. The hydrogen outlet of the hydrogen production, storage, and supply system is connected to the hydrogen nozzle, and the hydrogen production, storage, and supply system supplies hydrogen to the hydrogen nozzle. Both the liquid ammonia vaporization and storage supply system and the hydrogen production, storage, and supply system are connected to a power supply system, which supplies power to both systems.

[0028] The above embodiments of the present invention are applicable to the working method of a hydrogen-based fuel low-load combustion-supporting system for a tangential pulverized coal boiler, comprising the following processes:

[0029] During the gradual reduction of load, hydrogen gas is first injected into the four-corner tangential pulverized coal boiler 1 through the hydrogen nozzle located at the bottom for combustion. After the load stabilizes, hydrogen gas is injected into the four-corner tangential pulverized coal boiler 1 through the ammonia nozzle, and ammonia gas is injected into the four-corner tangential pulverized coal boiler 1 through the hydrogen nozzle. The injected ammonia gas and hydrogen gas participate in combustion in the furnace. Among them, the ammonia gas injected through the SOFA air nozzle (i.e., the third layer ammonia gas nozzle 3-3) is used to reduce part of the nitrogen oxides produced by combustion.

[0030] In the above scheme, the low-load operating condition of the four-corner tangential pulverized coal boiler 1 is the operating condition of 40% heat rate acceptance load and below. Under the low-load condition, the total blending ratio of ammonia and hydrogen is no more than 30% of the equivalent calorific value of the designed coal consumption under this load, and the total blending ratio of hydrogen accounts for 10% to 40% of the total blending calorific value under this load.

[0031] In a preferred embodiment of the present invention, at each corner of the pulverized coal boiler 1, the pulverized coal burners include a first layer of pulverized coal burners 2-1, a second layer of pulverized coal burners 2-2, a third layer of pulverized coal burners 2-3, a fourth layer of pulverized coal burners 2-4, and a fifth layer of pulverized coal burners 2-5, spaced from bottom to top. A first layer of hydrogen nozzles 4-1 is provided between the first layer of pulverized coal burners 2-1 and the second layer of pulverized coal burners 2-2; a second layer of hydrogen nozzles 4-2 and a first layer of ammonia nozzles 3-1 are provided between the second layer of pulverized coal burners 2-2 and the third layer of pulverized coal burners 2-3, wherein the second layer of hydrogen nozzles 4-2 is located below the first layer of ammonia nozzles 3-1; a third layer of hydrogen nozzles 4-3 and a second layer of ammonia nozzles 3-2 are provided between the third layer of pulverized coal burners 2-3 and the fourth layer of pulverized coal burners 2-4, wherein the third layer of hydrogen nozzles 4-3 is located below the second layer of ammonia nozzles 3-2. This embodiment applies to the low-load combustion system of hydrogen-based fuel in a tangential pulverized coal boiler. When in operation, the proportions of ammonia injected into the first layer ammonia nozzle 3-1, the second layer ammonia nozzle 3-2, and the third layer ammonia nozzle 3-3 are 38%~42%, 48%~52%, and 8%~12% of the total ammonia co-firing, respectively; the proportions of hydrogen injected into the first layer hydrogen nozzle 4-1, the second layer hydrogen nozzle 4-2, and the third layer hydrogen nozzle 4-3 are 38%~42%, 28%~32%, and 28%~32% of the total hydrogen co-firing, respectively.

[0032] In a preferred embodiment of the present invention, an ammonia flow regulating valve is provided on the inlet pipe of each ammonia nozzle. Specifically, a first-layer ammonia flow regulating valve 5-1 is provided on the inlet pipe of the first-layer ammonia nozzle 3-1, a second-layer ammonia flow regulating valve 5-2 is provided on the inlet pipe of the second-layer ammonia nozzle 3-2, and a third-layer ammonia flow regulating valve 5-3 is provided on the inlet pipe of the third-layer ammonia nozzle 3-3. These ammonia flow regulating valves allow for precise adjustment of the ammonia flow rate emitted from each ammonia nozzle.

[0033] In a preferred embodiment of the present invention, a hydrogen flow regulating valve is provided on the inlet pipe of each hydrogen nozzle. Specifically, a first-layer hydrogen flow regulating valve 6-1 is provided on the inlet pipe of the first-layer hydrogen nozzle 4-1, a second-layer hydrogen flow regulating valve 6-2 is provided on the inlet pipe of the second-layer hydrogen nozzle 4-2, and a third-layer hydrogen flow regulating valve 6-3 is provided on the inlet pipe of the third-layer hydrogen nozzle 4-2. These hydrogen flow regulating valves can precisely control the hydrogen flow rate emitted from each hydrogen nozzle.

[0034] In a preferred embodiment of the present invention, the liquid ammonia vaporization and storage supply system includes a liquid ammonia storage tank 7, a liquid ammonia evaporator 8, and an ammonia storage tank 9. The outlet of the liquid ammonia storage tank 7 is connected to the inlet of the liquid ammonia evaporator 8, the power interface of the liquid ammonia evaporator 8 is connected to the power supply system, the ammonia outlet of the liquid ammonia evaporator 8 is connected to the inlet of the ammonia storage tank 9, and the ammonia outlet of the ammonia storage tank 9 is connected to the ammonia nozzle. The liquid ammonia storage tank 7 is used to store liquid ammonia, the power supply system supplies power to the liquid ammonia evaporator 8, the liquid ammonia evaporator 8 processes the liquid ammonia in the liquid ammonia storage tank 7 into gaseous ammonia (i.e., ammonia gas), and then stores it in the ammonia storage tank 9. The ammonia gas in the ammonia storage tank 9 is finally delivered to each ammonia nozzle. The outlet of the liquid ammonia storage tank 7 is equipped with a liquid ammonia storage tank outlet flow regulating valve 10-1, the inlet of the liquid ammonia evaporator 8 is equipped with a liquid ammonia evaporator inlet flow regulating valve 10-2, and the ammonia outlet of the ammonia storage tank 9 is equipped with an ammonia storage tank outlet flow regulating valve 1-3.

[0035] Furthermore, based on the above embodiments, the liquid ammonia storage tank 7 can be configured in a parallel configuration of multiple tanks, with a liquid ammonia storage tank outlet flow regulating valve 10-1 installed at the outlet of each liquid ammonia storage tank 7. In addition, the liquid ammonia evaporators 8 can also be configured in a parallel configuration, with each liquid ammonia evaporator 8 corresponding to a liquid ammonia evaporator inlet flow regulating valve 10-2, or multiple liquid ammonia evaporators 8 sharing a single liquid ammonia evaporator inlet flow regulating valve 10-2. Furthermore, the ammonia storage tanks 9 can also be configured in a parallel configuration, with each ammonia storage tank 9 corresponding to a single ammonia storage tank outlet flow regulating valve 1-3, or multiple ammonia storage tanks 9 sharing a single ammonia storage tank outlet flow regulating valve 1-3.

[0036] In a preferred embodiment of the present invention, the hydrogen production, storage, and supply system includes an electrolytic hydrogen production tank 11 and a hydrogen storage tank 12. The power interface of the electrolytic hydrogen production tank 11 is connected to the power supply system, the hydrogen outlet of the electrolytic hydrogen production tank 11 is connected to the hydrogen inlet of the hydrogen storage tank 12, the hydrogen outlet of the hydrogen storage tank 12 is connected to a hydrogen nozzle, and the hydrogen outlet of the hydrogen storage tank 12 is equipped with a hydrogen storage tank outlet flow regulating valve 13. The electrolytic hydrogen production tank 11 uses electrical energy provided by the power supply system to electrolyze hydrogen. The hydrogen produced by the electrolytic hydrogen production tank 11 is stored in the hydrogen storage tank 12, which can supply hydrogen to the connected hydrogen nozzle. The hydrogen storage tank outlet flow regulating valve 13 can precisely regulate the hydrogen flow rate.

[0037] Furthermore, based on the above embodiments, multiple electrolytic hydrogen production cells 11 can be connected in parallel to produce hydrogen; multiple hydrogen storage tanks 12 can also be connected in parallel to store hydrogen. The multiple hydrogen storage tanks 12 can share a single hydrogen storage tank outlet flow regulating valve 13, or each can be equipped with a corresponding hydrogen storage tank outlet flow regulating valve 13.

[0038] Furthermore, in the above scheme, the types of electrolytic hydrogen production cells include, but are not limited to, alkaline electrolysis (ALK), proton exchange membrane electrolysis (PEM), solid oxide electrolysis (SOEC), and anion exchange membrane (AEM).

[0039] In a preferred embodiment of the present invention, the power supply system includes a DC power supply 14, an AC power supply 15, a solar photovoltaic panel 16, and a wind turbine 17. The solar photovoltaic panel 16 is connected to the DC power supply 14, which is connected to the power interface of the hydrogen production, storage, and supply system. The wind turbine 17 is connected to the AC power supply 15, which is connected to the liquid ammonia vaporization, storage, and supply system. Furthermore, the AC power supply 15 can be connected to the power grid. This allows excess electricity from the solar photovoltaic panel 16 and the wind turbine 17 to be transmitted to the grid. Additionally, when the solar photovoltaic panel 16 and the wind turbine 17 are not in operation, the grid's electricity can be used to produce hydrogen and vaporize ammonia.

[0040] Example

[0041] To improve the combustion stability of a tangentially shaped coal-fired boiler under deep peak shaving conditions, while reducing carbon and nitrogen emissions, this embodiment proposes a hydrogen-based fuel low-load combustion assistance system suitable for tangentially shaped pulverized coal boilers. This system is for low-load co-firing and combustion assistance of hydrogen-based fuels in tangentially shaped coal-fired boilers. (Refer to...) Figure 1The system includes a coal-fired boiler hydrogen-ammonia combustion-supporting system, a liquid ammonia gasification and storage supply system, a hydrogen production, storage and supply system, and a power supply system. The coal-fired boiler hydrogen-ammonia combustion-supporting system includes a four-cornered pulverized coal boiler 1, a first-layer pulverized coal burner 2-1, a second-layer pulverized coal burner 2-2, a third-layer pulverized coal burner 2-3, a fourth-layer pulverized coal burner 2-4, a fifth-layer pulverized coal burner 2-5, a first-layer ammonia nozzle 3-1, a second-layer ammonia nozzle 3-2, a third-layer ammonia nozzle 3-3, a first-layer hydrogen nozzle 4-1, a second-layer hydrogen nozzle 4-2, a third-layer hydrogen nozzle 4-3, a first-layer ammonia flow regulating valve 5-1, a second-layer ammonia flow regulating valve 5-2, a third-layer ammonia flow regulating valve 5-3, a first-layer hydrogen flow regulating valve 6-1, a second-layer hydrogen flow regulating valve 6-2, and a third-layer hydrogen flow regulating valve 6-3. The liquid ammonia vaporization and storage supply system includes a liquid ammonia storage tank 7, a liquid ammonia evaporator 8, an ammonia storage tank 9, a liquid ammonia storage tank outlet flow regulating valve 10-1, a liquid ammonia evaporator inlet flow regulating valve 10-2, and an ammonia storage tank outlet flow regulating valve 10-3. Liquid ammonia enters the liquid ammonia evaporator 8 for heating and vaporization via the liquid ammonia storage tank outlet flow regulating valve 10-1, and then enters the ammonia storage tank 9. The hydrogen production, storage, and supply system includes an electrolytic hydrogen production cell 11, a hydrogen storage tank 12, and a hydrogen storage tank outlet flow regulating valve 13. Hydrogen produced by the electrolytic hydrogen production cell 11 enters the hydrogen storage tank 12. The power supply system includes a DC power supply 14, an AC power supply 15, a solar photovoltaic panel 16, and a wind turbine 17. The solar photovoltaic panel 16 and the wind turbine 17 provide renewable electricity, while the power grid provides backup power.

[0042] Specifically, the first layer hydrogen nozzle 4-1 is located at the secondary air nozzle between the first layer pulverized coal burner 2-1 and the second layer pulverized coal burner 2-2; the first layer ammonia nozzle 3-1 and the second layer hydrogen nozzle 4-2 are located at the secondary air nozzle between the second layer pulverized coal burner 2-2 and the third layer pulverized coal burner 2-3; the second layer ammonia nozzle 3-2 and the third layer hydrogen nozzle 4-3 are located at the secondary air nozzle between the third layer pulverized coal burner 2-3 and the fourth layer pulverized coal burner 2-4; and the third layer ammonia nozzle 3-3 is located at the SOFA (i.e., burnout air duct) nozzle in the middle of the furnace. Each layer has four nozzles.

[0043] Specifically, the low-load operating condition of the four-corner tangential pulverized coal boiler 1 is the 40% THA load condition (i.e., the heat rate acceptance condition). Under this condition, the total blending ratio of ammonia and hydrogen is 20% of the design coal consumption with the same calorific value at this load, and the total blending ratio of hydrogen accounts for 20% of the total blending calorific value at this load. The ammonia injection ratios at the first to third layer ammonia nozzles 3-1 to 3-3 are 40%, 50%, and 10% of the total ammonia blending ratio, respectively. The hydrogen injection ratios at the first to third layer hydrogen nozzles 4-1 to 4-3 are 40%, 30%, and 30% of the total hydrogen blending ratio, respectively. The flow rate of each nozzle can be dynamically adjusted and distributed through a flow regulating valve, with an adjustment range of ±10%.

[0044] Specifically, four liquid ammonia storage tanks (7), liquid ammonia evaporators (8), and ammonia storage tanks (9) are configured according to the unit capacity, and all are connected in parallel. The liquid ammonia evaporator (8) is electrically driven, and liquid ammonia is heated and vaporized in the liquid ammonia evaporator (8) and stored in the ammonia storage tank (9). Sixteen electrolytic hydrogen production cells (11) are configured, and four hydrogen storage tanks (12) are configured according to the unit capacity, and all are connected in parallel. The electrolytic hydrogen production cells (11) are alkaline electrolyzers (ALK).

[0045] Specifically, the DC power 14 generated by the solar photovoltaic panel 16 can directly power the electrolytic hydrogen production tank 11, or it can be converted into AC power 15 to power the liquid ammonia evaporator 8. The AC power 15 generated by the wind turbine 17 can directly power the liquid ammonia evaporator 8, or it can be converted into DC power 14 to power the electrolytic hydrogen production tank 11. When the coal-fired boiler hydrogen-ammonia combustion-supporting system is not in operation and both the ammonia and hydrogen storage tanks have reached their rated capacity, the surplus renewable electricity can be fed into the grid. When neither the solar photovoltaic panel 16 nor the wind turbine 17 can provide power, the liquid ammonia evaporator 8 and the electrolytic hydrogen production tank 11 can be powered by plant power or grid power to meet the system's needs.

[0046] Specifically, during the gradual reduction of load in the coal-fired boiler, the outlet flow regulating valve 13 of the hydrogen storage tank is first opened, followed by the opening of the first-layer hydrogen flow regulating valve 6-1, allowing hydrogen to be injected into the furnace through the first-layer hydrogen nozzle 4-1. After the load stabilizes, the outlet flow regulating valve 10-3 of the ammonia storage tank, the second and third-layer hydrogen flow regulating valves 6-1 to 6-2, and the first to third-layer ammonia flow regulating valves 5-1 to 5-3 are opened. Simultaneously, the first-layer ammonia nozzle 3-1 and the second-layer hydrogen nozzle 4-2, and the second-layer ammonia nozzle 3-2 and the third-layer hydrogen nozzle 4-3 are sequentially and synchronously engaged to participate in combustion within the furnace. Gas nozzle 3-3 reduces some nitrogen oxides, enabling low-load combustion and low-NOx and low-carbon combustion of hydrogen-based fuel in coal-fired boilers. The renewable electricity generated by solar photovoltaic panels 16 and wind turbine 17 can be used in liquid ammonia evaporator 8 to vaporize liquid ammonia, or in electrolytic hydrogen production tank 11 to produce hydrogen. When the coal-fired boiler hydrogen-ammonia combustion system is not in operation and both ammonia storage tank 9 and hydrogen storage tank 12 have reached their rated capacity, the surplus renewable electricity can be fed into the grid. When the coal-fired boiler hydrogen-ammonia combustion system is in operation and there is no renewable electricity, the liquid ammonia evaporator 8 and electrolytic hydrogen production tank 11 need to be powered by plant power or grid power to meet the system requirements.

[0047] This invention achieves reduced carbon emissions and safe operation of boilers during deep peak shaving by introducing hydrogen and ammonia into the furnace through multiple layers and burners, while simultaneously reducing the difficulty of controlling nitrogen oxide emissions. In practical implementation, this invention provides a technical route for coal-fired power units to meet flexible peak shaving requirements while controlling carbon and nitrogen emissions, effectively ensuring the safe, stable, low-carbon, and low-nitrogen operation of boilers during deep peak shaving. The hydrogen-based fuel low-load combustion assist system for the four-corner tangential coal-fired boiler described in this invention achieves dynamic matching between stable in-furnace combustion conditions and low nitrogen oxide emissions under low load, effectively ensuring the safety and stability of coal-fired power units participating in deep peak shaving, and further reducing carbon emissions, contributing to the achievement of the "3060" target.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A hydrogen-based fuel low-load combustion assist system suitable for a tangential pulverized coal boiler, characterized in that, This includes a coal-fired boiler hydrogen-ammonia combustion-supporting system, a liquid ammonia gasification and storage supply system, a hydrogen production, storage and supply system, and a power supply system; Among them, the hydrogen-ammonia combustion-supporting system for coal-fired boilers includes a four-cornered pulverized coal boiler (1), and several pulverized coal burners are provided at each of the four corners of the four-cornered pulverized coal boiler (1). In each corner of the tangential pulverized coal boiler (1), several pulverized coal burners are distributed from top to bottom at intervals. Ammonia and / or hydrogen nozzles are arranged between the pulverized coal burners. The tangential pulverized coal boiler (1) is provided with an ammonia nozzle at the SOFA air nozzle. When both ammonia and hydrogen nozzles are arranged between the pulverized coal burners, the ammonia nozzle is located above the hydrogen nozzle. The ammonia outlet of the liquid ammonia vaporization and storage supply system is connected to the ammonia nozzle, the hydrogen outlet of the hydrogen production, storage and supply system is connected to the hydrogen nozzle, and both the liquid ammonia vaporization and storage supply system and the hydrogen production, storage and supply system are connected to the power supply system. At each corner of the four-corner pulverized coal boiler (1), the pulverized coal burners include a first layer of pulverized coal burners (2-1), a second layer of pulverized coal burners (2-2), a third layer of pulverized coal burners (2-3), a fourth layer of pulverized coal burners (2-4), and a fifth layer of pulverized coal burners (2-5) spaced apart from bottom to top. A first layer of hydrogen nozzles (4-1) is provided between the first layer of pulverized coal burners (2-1) and the second layer of pulverized coal burners (2-2). The second layer of pulverized coal burners (2-2) and the fifth layer of pulverized coal burners (2-5) are arranged in a tangential circular pattern. Between the three-layer pulverized coal burners (2-3), there is a second layer of hydrogen nozzle (4-2) and a first layer of ammonia nozzle (3-1), wherein the second layer of hydrogen nozzle (4-2) is located below the first layer of ammonia nozzle (3-1); between the third layer of pulverized coal burners (2-3) and the fourth layer of pulverized coal burners (2-4), there is a third layer of hydrogen nozzle (4-3) and a second layer of ammonia nozzle (3-2), wherein the third layer of hydrogen nozzle (4-3) is located below the second layer of ammonia nozzle (3-2).

2. The hydrogen-based fuel low-load combustion assist system for a tangential pulverized coal boiler according to claim 1, characterized in that, Each ammonia nozzle is equipped with an ammonia flow regulating valve on its inlet pipe.

3. A hydrogen-based fuel low-load combustion assist system for a tangential pulverized coal boiler according to claim 1, characterized in that, Each hydrogen nozzle is equipped with a hydrogen flow regulating valve on its inlet pipe.

4. A hydrogen-based fuel low-load combustion assist system for a tangential pulverized coal boiler according to claim 1, characterized in that, The liquid ammonia vaporization and storage supply system includes a liquid ammonia storage tank (7), a liquid ammonia evaporator (8), and an ammonia storage tank (9). The outlet of the liquid ammonia storage tank (7) is connected to the inlet of the liquid ammonia evaporator (8). The power interface of the liquid ammonia evaporator (8) is connected to the power supply system. The ammonia outlet of the liquid ammonia evaporator (8) is connected to the inlet of the ammonia storage tank (9). The ammonia outlet of the ammonia storage tank (9) is connected to the ammonia nozzle. The outlet of the liquid ammonia storage tank (7) is equipped with a liquid ammonia storage tank outlet flow regulating valve (10-1). The inlet of the liquid ammonia evaporator (8) is equipped with a liquid ammonia evaporator inlet flow regulating valve (10-2). The ammonia outlet of the ammonia storage tank (9) is equipped with an ammonia storage tank outlet flow regulating valve (1-3).

5. A hydrogen-based fuel low-load combustion assist system for a tangential pulverized coal boiler according to claim 1, characterized in that, The hydrogen production, storage and supply system includes an electrolytic hydrogen production tank (11) and a hydrogen storage tank (12). The power interface of the electrolytic hydrogen production tank (11) is connected to the power supply system. The hydrogen outlet of the electrolytic hydrogen production tank (11) is connected to the hydrogen inlet of the hydrogen storage tank (12). The hydrogen outlet of the hydrogen storage tank (12) is connected to the hydrogen nozzle. The hydrogen outlet of the hydrogen storage tank (12) is connected to a hydrogen storage tank outlet flow regulating valve (13).

6. A hydrogen-based fuel low-load combustion assist system for a tangential pulverized coal boiler according to claim 1, characterized in that, The power supply system includes a DC power supply (14), an AC power supply (15), a solar photovoltaic panel (16), and a wind turbine (17). The solar photovoltaic panel (16) is connected to the DC power supply (14), the DC power supply (14) is connected to the power interface of the hydrogen production, storage and supply system, the wind turbine (17) is connected to the AC power supply (15), and the AC power supply (15) is connected to the liquid ammonia vaporization and storage supply system. The DC power supply (14) is connected to the AC power supply (15).

7. The operating method of a hydrogen-based fuel low-load combustion-supporting system for a tangential pulverized coal boiler as described in any one of claims 1-6, characterized in that, The process includes the following: During the gradual reduction of load, hydrogen gas is first injected into the four-corner tangential pulverized coal boiler (1) through the hydrogen nozzle located at the bottom for combustion. After the load stabilizes, hydrogen gas is injected into the four-corner tangential pulverized coal boiler (1) through the ammonia nozzle and ammonia gas is injected into the four-corner tangential pulverized coal boiler (1) through the hydrogen nozzle. The injected ammonia gas and hydrogen gas participate in the combustion in the furnace. Among them, the ammonia gas injected into the SOFA air nozzle is used to reduce part of the nitrogen oxides produced by combustion. Among them, the proportions of ammonia injected into the first layer ammonia nozzle (3-1), the second layer ammonia nozzle (3-2), and the third layer ammonia nozzle (3-3) are 38%~42%, 48%~52%, and 8%~12% of the total ammonia co-firing amount, respectively; The hydrogen injection ratios of the first hydrogen nozzle (4-1), the second hydrogen nozzle (4-2), and the third hydrogen nozzle (4-3) are 38%~42%, 28%~32%, and 28%~32% of the total hydrogen co-firing amount, respectively.

8. The operating method of a low-load combustion-supporting system for hydrogen-based fuel suitable for a tangential pulverized coal boiler according to claim 7, characterized in that, The low-load condition of the four-corner tangential pulverized coal boiler (1) is the acceptance condition of 40% heat consumption rate and below. Under the low-load condition, the total blending ratio of ammonia and hydrogen is not greater than 30% of the equivalent calorific value of the designed coal consumption under this load, and the total blending ratio of hydrogen accounts for 10% to 40% of the total blending calorific value under this load.

Images