A green hydrogen blending combustion system suitable for a pulverized coal boiler

Abstract

The utility model discloses a kind of combustion systems of green hydrogen blending combustion suitable for pulverized coal boiler, divide boiler furnace into main combustion zone, reduction zone and burn-out zone, the reduction zone is located above main combustion zone, burn-out zone is located above reduction zone;For four corners tangential circle pulverized coal boiler: multiple groups of burner nozzles are arranged in main combustion zone, each group includes pulverized coal nozzle, hydrogen burner nozzle and combustion air nozzle, the hydrogen burner nozzle is arranged between two layers of pulverized coal nozzle;Multiple layers of hydrogen burner nozzles are arranged in reduction zone;Multiple layers of burn-out air nozzles are arranged in burn-out zone;In addition, there is also the combustion system of wall type head-on pulverized coal boiler.Effectively avoid coking and burning loss of water-cooled wall and pulverized coal nozzle area, and the adverse effects brought by a large number of blending hydrogen on boiler heat exchange distribution, low-temperature corrosion, boiler efficiency and nitrogen oxide emission.

Description

Technical Field

[0001] This utility model belongs to the field of pulverized coal boiler combustion technology, specifically relating to a green hydrogen co-firing combustion system suitable for pulverized coal boilers. It achieves efficient and clean co-firing of green hydrogen through a layered and zoned design for two mainstream boiler types: tangential round boilers and wall-mounted counter-flow boilers. Background Technology

[0002] With the national emphasis on dual-carbon development, low-carbon and even negative-carbon technologies in the energy utilization industry are gaining increasing popularity. Replacing traditional fossil fuels with "zero-carbon" fuels is one of the most effective ways to reduce carbon emissions.

[0003] Hydrogen, recognized globally as a clean energy source, boasts high energy density, zero pollution, low ignition energy, and high combustion efficiency. However, in recent years, my country's use of green energy sources such as photovoltaics and wind power has been significantly impacted by inherent volatility and intermittency, severely affecting grid stability and leading to widespread curtailment of wind and solar power, resulting in a massive waste of green energy resources. Producing hydrogen from wind and solar power is an effective way to utilize these green energy sources; however, current hydrogen energy technologies face bottlenecks such as high storage and transportation costs, limiting the widespread adoption of this technology.

[0004] With the construction of large-scale wind and solar power bases and the continuous increase in the proportion of renewable energy in my country's electricity generation, large-scale coal-fired power units play a crucial role in maintaining the safety, stability, and stabilization of the national power grid. For example, constructing large-scale coal-fired power units in wind and solar power bases and areas rich in renewable energy, while simultaneously co-firing renewable hydrogen into boilers nearby, can solve the problem of green electricity consumption in the current context of wind and solar power curtailment, while avoiding the cost pressure of large-scale hydrogen storage. Furthermore, co-firing hydrogen into coal-fired boilers, due to its high energy density, fast combustion speed, and zero pollution, can enhance pulverized coal combustion, improve combustion efficiency, and effectively reduce boiler carbon emissions.

[0005] However, the rapid combustion speed and high flame temperature of hydrogen may lead to adverse effects such as coking and increased nitrogen oxide emissions in pulverized coal boilers. At the same time, as the proportion of hydrogen co-firing increases, it may also have adverse effects on the heat exchange distribution of the heating surface and the increase in flue gas temperature.

[0006] In summary, the technical problems to be solved by this utility model are as follows.

[0007] 1. Combustion stability and pollution control issues. Hydrogen combustion is fast and the flame temperature is high, which can easily lead to coking on the water-cooled walls near the pulverized coal nozzle and a surge in nitrogen oxide (NOx) emissions; the lack of a zoned air distribution strategy for hydrogen-coal co-combustion exacerbates the risk of coking due to local heat load runaway.

[0008] 2. System compatibility and energy efficiency issues. High proportions of hydrogen blending can easily alter the heat exchange distribution within the furnace, leading to increased flue gas temperature, low-temperature corrosion, and decreased boiler efficiency; existing technologies have not resolved the balance between the upper limit of green hydrogen blending ratio and safe boiler operation.

[0009] 3. Bottlenecks in green electricity consumption and storage. Due to high storage and transportation costs, hydrogen production from wind and solar power is difficult to apply on a large scale. It needs to be consumed locally, but there is a lack of combustion systems that can work in conjunction with coal-fired power units. Utility Model Content

[0010] To overcome the aforementioned problems in existing technologies for co-firing green hydrogen in pulverized coal boilers, this utility model addresses two combustion system arrangements: tangentially shaped pulverized coal boilers and wall-mounted opposed-flow pulverized coal boilers. It provides a green hydrogen co-firing combustion system suitable for pulverized coal boilers, comprising: (1) The boiler furnace is divided into a main combustion zone, a reduction zone and a burnout zone, wherein the reduction zone is located above the main combustion zone and the burnout zone is located above the reduction zone; (2) For pulverized coal boilers with tangential corners: Multiple sets of burner nozzles are arranged in the main combustion zone. Each set includes a pulverized coal nozzle, a hydrogen burner nozzle, and a combustion air nozzle. The hydrogen burner nozzle is arranged between two layers of pulverized coal nozzles. Multiple hydrogen burner nozzles are arranged in the reduction zone; Multiple layers of burnout air nozzles are arranged in the burnout zone; (3) For wall-mounted opposed pulverized coal boilers: Multi-layer pulverized coal burners are arranged opposite each other on the front and rear walls or left and right walls of the main combustion zone. Each pulverized coal burner includes a primary air duct, a secondary air duct, and a hydrogen spray gun. A multi-layer swirling hydrogen burner is arranged in the reduction zone in a counter-current configuration. Multi-layered swirling burnout air nozzles are arranged in the burnout zone.

[0011] Preferably, the hydrogen burner nozzles of the tangentially rounded pulverized coal boiler have independent air distribution, and the excess air coefficient is 1.05–1.1; The hydrogen injection lance of the wall-mounted counter-coupling pulverized coal boiler has independent air distribution, and the excess air coefficient is 1.05–1.1.

[0012] Preferably, the hydrogen injector of the wall-mounted counter-current pulverized coal boiler is located at the center of the pulverized coal burner, and hydrogen is injected through the porous structure at the front end of the injector.

[0013] Preferably, the amount of hydrogen co-firing in the main combustion zone is evenly distributed, and the total heat content is ≤5% of the boiler's rated load; The amount of hydrogen co-firing in the reduction zone is evenly distributed, and the total heat content is ≤20% of the boiler's rated load.

[0014] Preferably, the air volume in the burnout zone accounts for 30–40% of the total air volume of the boiler.

[0015] Preferably, the air distribution system of the hydrogen burner nozzle and hydrogen spray gun is independent of the pulverized coal combustion air supply system.

[0016] Preferably, the front end of the hydrogen burner nozzle adopts a porous structure with a nozzle diameter of 6-12mm and an angle along the original secondary air injection direction to promote hydrogen-coal mixing.

[0017] Preferably, when the hydrogen co-firing amount increases to 3%, the combustion air pressure is increased to 1.5-2 kPa by the damper actuator to ensure that the excess coefficient is maintained in the range of 1.05-1.1.

[0018] Preferably, a wall temperature monitoring thermocouple is added to the pulverized coal nozzle adjacent to the hydrogen nozzle. When the monitored temperature is >1100℃, the output of the adjacent hydrogen nozzle is automatically reduced by 10%.

[0019] Preferably, the maximum hydrogen blending ratio in the boiler is 25%, and the sum of the hydrogen blending ratios in the main combustion zone and the reduction zone does not exceed this limit.

[0020] This utility model discloses a green hydrogen co-firing combustion system suitable for pulverized coal boilers. The maximum co-firing ratio at the boiler's rated load is 25%, while the maximum co-firing ratio in the main combustion zone is 5%. By limiting the co-firing ratio, the system achieves new energy consumption and effective carbon reduction in the boiler. It also comprehensively considers the effects of excessive local heat load, increased flue gas moisture, and reduced flue gas volume caused by hydrogen co-firing. This effectively avoids coking and burn-off in the water-cooled walls and pulverized coal nozzle area, as well as the adverse effects of large amounts of hydrogen co-firing on boiler heat exchange distribution, low-temperature corrosion, boiler efficiency, and nitrogen oxide emissions.

[0021] The beneficial effects of this utility model are as follows: Stratified combustion suppresses pollution Main combustion zone (hydrogen blend ≤5%): Hydrogen nozzles are placed between pulverized coal nozzles (corner tangential) or in the center of the burner (wall-mounted counter-current type), with independent air distribution (excess coefficient 1.05–1.1) to avoid localized high-temperature coking and NOx generation. Reduction zone (hydrogen doping ≤20%): Uniformly arranged swirl hydrogen burners enhance the reducing atmosphere and further reduce NOx.

[0022] Burnout optimization ensures energy efficiency The air volume in the burnout zone accounts for 30-40%: to supplement the oxygen content of the pulverized coal after combustion, alleviate the heat exchange imbalance caused by the reduction of flue gas volume, and control the exhaust gas temperature.

[0023] Proportional control enables safe co-firing The total blending rate of the main combustion zone (≤5%) + reduction zone (≤20%) is capped at ≤25%, balancing green electricity consumption with boiler anti-coking, anti-corrosion, and efficiency stability.

[0024] Multi-hole hydrogen injection improves mixing efficiency The hydrogen spray gun uses a porous structure at the front end to promote uniform mixing of hydrogen, coal, and air, and avoid air leakage.

[0025] For example, in a 660MW tangential boiler, when this utility model system is used, with 20% hydrogen added to the reduction zone, nitrogen oxides decrease by 5% compared to pure coal combustion, and flue gas temperature fluctuation is <5℃. Attached Figure Description

[0026] Figure 1 : Schematic diagram of the hydrogen co-firing combustion system of the four-corner tangential pulverized coal boiler of this utility model.

[0027] Figure 2 : Schematic diagram of the hydrogen co-firing combustion system of the wall-mounted counter-pressure pulverized coal boiler of this utility model.

[0028] Explanation of reference numerals in the attached diagram: Pulverized coal nozzle 1-1, Hydrogen burner nozzle 1-2, Combustion air nozzle 1-3, Combustion air nozzle 1-4; Pulverized coal burner 2-1, primary air duct 2-1-1, secondary air duct 2-1-2, hydrogen spray gun 2-1-3; Swirling hydrogen burner 2-2, swirling burnout air nozzle 2-3. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to the following embodiments.

[0030] This invention addresses two combustion system arrangements for pulverized coal boilers: a four-corner tangential pulverized coal boiler and a wall-mounted opposed-flow pulverized coal boiler. It provides a green hydrogen co-firing combustion system suitable for pulverized coal boilers.

[0031] The green hydrogen co-firing combustion system of the tangentially circular pulverized coal boiler divides the boiler furnace combustion zone into a main combustion zone, a reduction zone, and a burnout zone. Multiple sets of burner nozzles are arranged in the main combustion zone. Each set consists of multiple layers of pulverized coal nozzles 1-1, hydrogen co-firing burner nozzles 1-2, and combustion air nozzles 1-3. Hydrogen burner nozzles 1-2 are arranged between adjacent layers of pulverized coal nozzles 1-1. Each hydrogen burner nozzle includes a hydrogen spray gun and a combustion air channel. The combustion air nozzles 1-3 are positioned above and below the pulverized coal nozzles to provide oxygen for pulverized coal combustion. The amount of hydrogen co-firing from the multiple layers of hydrogen burner nozzles in the main combustion zone is evenly distributed, and the total output of the hydrogen co-firing burners does not exceed 5% of the boiler's rated load. Multiple layers of hydrogen burner nozzles are arranged in a tangentially circular pattern in the reduction zone above the main combustion zone, with an even distribution of hydrogen co-firing. The total output of the hydrogen co-firing burners in the reduction zone does not exceed 20% of the boiler's rated load. The hydrogen burners in the aforementioned boiler combustion system employ hydrogen injection guns and a porous structure to inject hydrogen. The excess air coefficient of the hydrogen burners themselves is designed to be 1.05-1.1, meeting the requirements for hydrogen combustion and preventing air rushing. Simultaneously, by controlling the output of the hydrogen burners in the main combustion zone, excessive local heat load and combustion temperature are avoided, thus preventing coking at the pulverized coal nozzles and nearby water-cooled wall areas, and effectively suppressing the large-scale generation of nitrogen oxides. Above the reduction zone of the combustion system is the burnout zone, which is equipped with multiple layers of burnout air nozzles 1-4 to supplement the oxygen required for pulverized coal combustion. The air volume in the burnout zone accounts for 30-40% of the total furnace air volume.

[0032] The green hydrogen co-firing combustion system of the wall-mounted opposed pulverized coal boiler divides the boiler furnace combustion zone into a main combustion zone, a reduction zone, and a burnout zone. Multiple layers of pulverized coal burners 2-1 are arranged opposed to each other on the front and rear walls (or left and right side walls) of the main combustion zone. Each layer contains multiple pulverized coal burners, and each burner consists of a primary air duct 2-1-1, a secondary air duct 2-1-2, and a hydrogen injector 2-1-3. The hydrogen injector is positioned at the center of the nozzle of each burner, and hydrogen is injected into the furnace through the injector and a small hole at the front end. The output of the hydrogen injector in a single burner does not exceed 5% of the total pulverized coal fuel output. Multiple layers of swirling hydrogen burners 2-2 are arranged opposed to each other on the front and rear walls (or left and right side walls) of the reduction zone above the main combustion zone. Each layer contains multiple hydrogen burners evenly distributed, and the number is not limited by the number of pulverized coal burners in a single layer of the main combustion zone. All hydrogen burners in the reduction zone have the same output, and the total output of the hydrogen-coated burners in the reduction zone does not exceed 20% of the boiler's rated load. The aforementioned boiler combustion system employs hydrogen injection lances and a porous structure for hydrogen injection. The hydrogen burner's own excess air coefficient is designed to be 1.05-1.1, meeting the requirements for hydrogen combustion and preventing air rushing. Simultaneously, by controlling the output of the hydrogen burner in the main combustion zone, excessive local heat load and combustion temperature are avoided, thus preventing coking at the pulverized coal nozzle and nearby water-cooled wall areas, and effectively suppressing the large-scale formation of nitrogen oxides. Above the reduction zone of the combustion system is the burnout zone, with 2-3 multi-layered swirl burnout air nozzles arranged opposite each other on the front and rear walls (or left and right side walls) to supplement the oxygen required for pulverized coal burnout. The air volume in the burnout zone accounts for 30-40% of the total furnace air volume.

[0033] This utility model can be further improved in the following details: 1. Refine the nozzle structure parameters.

[0034] For example, the front end of the hydrogen spray gun adopts a porous structure, with the nozzle diameter preferably being 6-12mm and the angle being along the original secondary air injection direction to promote hydrogen-coal mixing.

[0035] 2. Linkage control of the air distribution system (to solve the hidden danger of "air grabbing"), dynamic adjustment of the combustion air and hydrogen distribution air in the main combustion zone.

[0036] For example, when the hydrogen co-firing amount increases to 3%, the combustion air pressure is increased to 1.5-2 kPa by the damper actuator to ensure that the excess coefficient is maintained in the range of 1.05-1.1.

[0037] 3. Temperature monitoring and anti-coking mechanism (strengthen problem-solving methods), increase the layout scheme of temperature monitoring points and control thresholds.

[0038] For example, by adding a wall temperature monitoring thermocouple to the pulverized coal nozzle adjacent to the hydrogen nozzle, the output of the adjacent hydrogen nozzle can be automatically reduced by 10% when the monitored temperature is >1100℃.

[0039] The above description is a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model. These improvements and modifications are also considered to be within the protection scope of the present utility model, and the protection scope of the present utility model shall be defined by the claims.

Claims

1. A green hydrogen blending combustion system suitable for a pulverized coal boiler, characterized in that The system includes: (1) The boiler furnace is divided into a main combustion zone, a reduction zone and a burnout zone, wherein the reduction zone is located above the main combustion zone and the burnout zone is located above the reduction zone; (2) For pulverized coal boilers with tangential corners: Multiple sets of burner nozzles are arranged in the main combustion zone. Each set includes a pulverized coal nozzle (1-1), a hydrogen burner nozzle (1-2), and a combustion air nozzle (1-3). The hydrogen burner nozzle (1-2) is arranged between two layers of pulverized coal nozzles (1-1). Multi-layer hydrogen burner nozzles (1-2) are arranged in the reduction zone; Multiple layers of burnout air nozzles (1-4) are arranged in the burnout zone; (3) For wall-mounted opposed pulverized coal boilers: Multi-layer pulverized coal burners (2-1) are arranged opposite each other on the front and rear walls or left and right walls of the main combustion zone. Each pulverized coal burner includes a primary air duct (2-1-1), a secondary air duct (2-1-2), and a hydrogen spray gun (2-1-3). A multi-layer swirl hydrogen burner (2-2) is arranged in the reduction zone. Multi-layered swirling burnout air nozzles (2-3) are arranged in opposite directions in the burnout zone.

2. The green hydrogen co-firing combustion system according to claim 1, characterized in that: The hydrogen burner nozzles (1-2) of the four-corner tangential pulverized coal boiler have independent air distribution, with an excess air coefficient of 1.05–1.1; The hydrogen injection lance (2-1-3) of the wall-mounted counter-coupling pulverized coal boiler has independent air distribution, with an excess air coefficient of 1.05–1.

1.

3. The green hydrogen co-firing combustion system according to claim 1, characterized in that: The hydrogen spray gun (2-1-3) of the wall-mounted counter-pressure pulverized coal boiler is located at the center of the pulverized coal burner (2-1), and hydrogen is injected through the porous structure at the front end of the spray gun.

4. The green hydrogen co-firing combustion system according to claim 1, characterized in that: The amount of hydrogen co-firing in the main combustion zone is evenly distributed, and the total heat content is ≤5% of the boiler's rated load; The amount of hydrogen co-firing in the reduction zone is evenly distributed, and the total heat content is ≤20% of the boiler's rated load.

5. The green hydrogen co-firing combustion system according to claim 1, characterized in that: The air volume in the burnout zone accounts for 30–40% of the total air volume of the boiler.

6. The green hydrogen co-firing combustion system according to claim 1, characterized in that: The air distribution system of the hydrogen burner nozzle (1-2) and hydrogen spray gun (2-1-3) is independent of the pulverized coal combustion air supply system.

7. The green hydrogen co-firing combustion system according to claim 1, characterized in that: The hydrogen burner nozzle front end adopts a porous structure with a nozzle diameter of 6-12mm and an angle along the original secondary air injection direction to promote hydrogen-coal mixing.

8. The green hydrogen co-firing combustion system according to claim 1, characterized in that: When the hydrogen co-firing amount increases to 3%, the combustion air pressure is increased to 1.5-2 kPa by the damper actuator to ensure that the excess coefficient is maintained in the range of 1.05-1.

1.

9. The green hydrogen co-firing combustion system according to claim 1, characterized in that: Add a wall temperature monitoring thermocouple to the pulverized coal nozzle adjacent to the hydrogen nozzle. When the monitored temperature is >1100℃, automatically reduce the output of the adjacent hydrogen nozzle by 10%.

10. The green hydrogen co-firing combustion system according to any one of claims 1–9, characterized in that: The maximum hydrogen blending ratio for the boiler is 25%, and the sum of the hydrogen blending ratios in the main combustion zone and the reduction zone shall not exceed this limit.

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