Direct burner and combustion system

Abstract

The present application relates to the technical field of boiler combustion, and discloses a direct combustion burner and a combustion system, wherein the combustion system directly sends hydrogen-oxygen mixed gas obtained by electrolysis of water into the combustion burner, thereby eliminating investment in purification equipment and energy consumption. The direct combustion burner is provided with a first nozzle and a second nozzle, the first nozzle converges towards the axis of the pulverized coal channel, can heat the core area of the pulverized coal jet, and is favorable for improving the ignition condition; the second nozzle is parallel to the axis of the pulverized coal conveying pipe, forms a wake flow at the periphery of the pulverized coal jet, plays a stable combustion and wrapping heating role, and is helpful to enhance the flame stability. Multiple small-aperture nozzles disperse the hydrogen-oxygen mixed gas into numerous small jets, form a small flame group which is independent and mutually supported, are helpful to control the size of the local high-temperature area and shorten the residence time of the high-temperature flue gas, thereby inhibiting the generation of nitrogen oxides. The hydrogen-oxygen mixed gas is self-provided with oxygen, the combustion process does not consume additional oxygen in the combustion-supporting air, and is helpful to reduce the carbon content of fly ash.

Description

Technical Field

[0001] This invention relates to the field of boiler combustion technology, and in particular to a direct burner and combustion system. Background Technology

[0002] Coal-fired power plants account for a significant portion of my country's total carbon dioxide emissions, making the reduction of these emissions a key pathway to achieving carbon peaking and carbon neutrality. Blending zero-carbon fuels (such as hydrogen) into coal-fired boilers is an effective method for carbon reduction. Complete combustion of hydrogen produces only water, without carbon dioxide or dust. Electrolysis of water is an important way to obtain "green hydrogen," a process that simultaneously produces a mixture of hydrogen and oxygen. Further purifying this hydrogen-oxygen mixture into pure hydrogen requires additional purification equipment, increasing investment costs and reducing overall system efficiency. Therefore, directly utilizing the hydrogen-oxygen mixture for combustion without purification is attractive in terms of both economics and energy efficiency.

[0003] However, directly introducing a hydrogen-oxygen mixture into a coal-fired boiler introduces several new technical challenges. Hydrogen has a high theoretical combustion temperature, easily creating localized high-temperature zones within the furnace. In these high-temperature environments, nitrogen and oxygen in the air may react to produce significant amounts of nitrogen oxides (NOx), necessitating control of NOx emission concentrations. Furthermore, the hydrogen-oxygen mixture alters the airflow distribution upon entering the furnace. Improper timing or location of mixing with the pulverized coal jet can lead to insufficient oxygen supply around the pulverized coal, resulting in increased carbon content in fly ash and reduced boiler combustion efficiency. Existing burners typically place auxiliary gas or fuel nozzles around the main pulverized coal jet, making it difficult to effectively transfer the heat released from hydrogen-oxygen combustion to the ignition root of the pulverized coal, thus limiting its effectiveness in enhancing the ignition process. Moreover, mismatches between the velocity and direction of the hydrogen-oxygen jet and the pulverized coal jet can interfere with primary air flow, affecting flame stability. Summary of the Invention

[0004] The purpose of this invention is to provide a direct burner and combustion system that can improve the ignition performance and combustion stability of pulverized coal while controlling the amount of nitrogen oxides generated.

[0005] To achieve the above objectives, the present invention provides a direct burner, comprising: The pulverized coal conveying pipe has an internal pulverized coal channel. A hydrogen-oxygen delivery pipe is coaxially sleeved on the pulverized coal delivery pipe. A hydrogen-oxygen channel is formed between the inner side of the hydrogen-oxygen delivery pipe and the outer side of the pulverized coal delivery pipe. The output end sidewall of the pulverized coal delivery pipe is provided with a plurality of first nozzles evenly distributed around the axis of the pulverized coal delivery pipe. The axes of the plurality of first nozzles intersect with the axis of the pulverized coal delivery pipe at a first focal point. A sealing plate is provided between the output end of the hydrogen-oxygen conveying pipe and the output end of the pulverized coal conveying pipe. The end of the sealing plate is provided with a plurality of second nozzles evenly distributed around the axis of the pulverized coal conveying pipe. The axis of the second nozzles is parallel to the axis of the pulverized coal conveying pipe. And a combustion-supporting air delivery pipe, coaxially sleeved on the hydrogen-oxygen delivery pipe, forming a combustion-supporting air channel between the inner side of the combustion-supporting air delivery pipe and the outer side of the hydrogen-oxygen delivery pipe.

[0006] As a preferred embodiment of the present invention, the distance between the first focal point and the end face of the output end of the pulverized coal conveying pipe is 100mm-500mm.

[0007] As a preferred embodiment of the present invention, the output end sidewall of the pulverized coal conveying pipe is provided with a plurality of first nozzle groups, each first nozzle group including a plurality of first nozzles evenly distributed around the axis of the pulverized coal conveying pipe, and the plurality of first nozzle groups are arranged at intervals along the axial direction of the pulverized coal conveying pipe.

[0008] As a preferred embodiment of the present invention, along the conveying direction of the pulverized coal conveying pipe, the distance between the first focal point corresponding to the plurality of first nozzle groups and the end face of the output end of the pulverized coal conveying pipe increases sequentially.

[0009] As a preferred embodiment of the present invention, the end of the sealing plate is provided with a plurality of second nozzle groups, the second nozzle groups including a plurality of second nozzles evenly distributed around the axis of the pulverized coal conveying pipe, and the plurality of second nozzle groups are arranged at radial intervals along the pulverized coal conveying pipe.

[0010] As a preferred embodiment of the present invention, the output end of the pulverized coal conveying pipe is provided with an expansion portion, which gradually expands outward along the conveying direction of the pulverized coal conveying pipe.

[0011] The present invention also provides a combustion system, including the above-mentioned direct burner and water electrolysis device, wherein the hydrogen and oxygen output end of the water electrolysis device is connected to the input end of the hydrogen and oxygen delivery pipe through a gas delivery pipe.

[0012] As a preferred embodiment of the present invention, it further includes a nitrogen blowing device, wherein the output end of the gas delivery pipe is provided with a first shut-off valve, the input end of the gas delivery pipe is provided with a second shut-off valve, the nitrogen blowing device is provided with a first blowing pipe and a second blowing pipe, the output ends of the first blowing pipe and the output ends of the second blowing pipe are respectively connected to the gas delivery pipe, the connection point of the first blowing pipe and the gas delivery pipe is located at the gas outlet end of the first shut-off valve, and the connection point of the second blowing pipe and the gas delivery pipe is located at the gas outlet end of the second shut-off valve.

[0013] As a preferred embodiment of the present invention, the gas delivery pipe is provided with at least two first flame arresters, and the input end and the output end of the gas delivery pipe are respectively provided with the first flame arresters.

[0014] As a preferred embodiment of the present invention, the gas delivery pipe is connected to a vent pipe, and the vent pipe is provided with a switch valve, a check valve and a second flame arrester.

[0015] This invention discloses a direct burner and combustion system. Compared with existing technologies, its advantages are as follows: This invention can directly feed the hydrogen-oxygen mixture generated by water electrolysis into the burner for combustion without purification and separation, thus eliminating the investment in purification equipment and the corresponding energy consumption. The first nozzle of the direct burner converges towards the axis of the pulverized coal channel, which can heat the core area of ​​the pulverized coal jet and improve ignition conditions. The second nozzle is parallel to the axis of the pulverized coal conveying pipe, forming a co-flow around the pulverized coal jet, which plays a role in stabilizing combustion and enveloping heating, thus helping to enhance flame stability. Multiple small-diameter nozzles disperse the hydrogen-oxygen mixture into numerous fine jets, forming a group of small flames that are independent and mutually supportive, which helps to control the scale of local high-temperature areas and shorten the residence time of high-temperature flue gas, thereby inhibiting the formation of nitrogen oxides. The hydrogen-oxygen mixture contains oxygen, and its combustion process does not consume additional oxygen from the combustion air. The combustion air can be used more for the complete combustion of pulverized coal and coke, which helps to reduce the carbon content of fly ash. By setting multiple sets of nozzles and adjusting their positions, the spatial distribution of flame heating can be optimized, thereby enhancing the burner's adaptability to different coal types and load conditions. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the direct burner of the present invention; Figure 2 This is a partially enlarged schematic diagram of the direct burner of the present invention; Figure 3 This is a side view of the direct burner of the present invention. Figure 4 This is a schematic diagram of the combustion system of the present invention; In the figure, the components are: direct burner 1; pulverized coal conveying pipe 11; pulverized coal channel 111; first nozzle 112; first nozzle group 113; expansion section 114; hydrogen-oxygen conveying pipe 12; hydrogen-oxygen channel 121; sealing plate 122; second nozzle 123; second nozzle group 124; combustion air conveying pipe 13; combustion air channel 131; water electrolysis device 2; gas conveying pipe 3; first shut-off valve 31; second shut-off valve 32; first flame arrester 33; nitrogen blowing device 4; first blowing pipe 41; second blowing pipe 42; vent pipe 5; switch valve 51; check valve 52; second flame arrester 53. Detailed Implementation

[0017] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0018] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and for simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. like Figure 1-3 As shown, a preferred embodiment of the present invention provides a direct burner 1, comprising: a pulverized coal conveying pipe 11, a hydrogen-oxygen conveying pipe 12, and a combustion air conveying pipe 13. The output ends of the pulverized coal conveying pipe 11, the hydrogen-oxygen conveying pipe 12, and the combustion air conveying pipe 13 extend into the furnace. The output end of the pulverized coal conveying pipe 11 is open, and a pulverized coal channel 111 is formed inside the pulverized coal conveying pipe 11. Primary air from the coal mill carries pulverized coal into the pulverized coal channel 111, and the pulverized coal is conveyed to the furnace through the pulverized coal conveying pipe 11. The pulverized coal conveying pipe 11 is made of stainless steel and high-temperature resistant castable, capable of withstanding the high-temperature flame of hydrogen-oxygen combustion and the abrasion of the pulverized coal airflow.

[0019] A hydrogen-oxygen delivery pipe 12 is coaxially sleeved on a pulverized coal delivery pipe 11. A hydrogen-oxygen channel 121 is formed between the inner side of the hydrogen-oxygen delivery pipe 12 and the outer side of the pulverized coal delivery pipe 11. Multiple first nozzles 112 are evenly distributed around the axis of the pulverized coal delivery pipe 11 on the side wall of the output end of the pulverized coal delivery pipe 11. The axes of the multiple first nozzles 112 intersect the axis of the pulverized coal delivery pipe 11 at a first focal point. A sealing plate 122 is provided between the output end of the hydrogen-oxygen delivery pipe 12 and the output end of the pulverized coal delivery pipe 11. The sealing plate 122 is annular and blocks the output end of the hydrogen-oxygen channel 121. The unit is equipped with multiple second nozzles 123 evenly distributed around the axis of the pulverized coal conveying pipe 11. The diameters of the first nozzles 112 and the second nozzles 123 are less than 1 mm. The axis of the second nozzles 123 is parallel to the axis of the pulverized coal conveying pipe 11, which can delay the mixing of hydrogen gas ejected from the second nozzles 123 with the pulverized coal gas flow. It can be understood that the first nozzles 112 and the second nozzles 123 are respectively connected to the hydrogen-oxygen channel 121. The hydrogen-oxygen mixture (a mixture of hydrogen and oxygen) is conveyed through the hydrogen-oxygen channel 121, and the hydrogen-oxygen mixture is ejected into the furnace through the first nozzles 112 and the second nozzles 123 for combustion. The first nozzles 112 are located on the side wall of the pulverized coal conveying pipe 11. These nozzles penetrate the pipe wall, connecting the hydrogen-oxygen channel 121 with the furnace space outside the pulverized coal channel 111. When the hydrogen-oxygen mixture is ejected from the first nozzles 112, its jet direction points towards the first focal point, which is located at a certain position on the axis of the pulverized coal conveying pipe 11. The second nozzle 123 is located on the end face of the sealing plate 122, which closes the annular outlet of the hydrogen-oxygen channel 121, allowing the hydrogen-oxygen mixture to exit only through the first nozzle 112 and the second nozzle 123. The axis of the second nozzle 123 is parallel to the axis of the pulverized coal conveying pipe 11, so the direction of the jet ejected from the second nozzle 123 is consistent with the direction of the main pulverized coal jet. The diameters of both the first nozzle 112 and the second nozzle 123 are less than 1 mm. This small-aperture structure helps to refine the hydrogen-oxygen jet, enabling it to form numerous small flames within the furnace. In actual operation, the hydrogen-oxygen mixture is ejected from two different angles and positions, forming two sets of jets: one converging towards the center, and the other advancing parallel to the axial direction.

[0020] Combustion air supply pipe 13 is coaxially sleeved on hydrogen-oxygen supply pipe 12, forming a combustion air channel 131 between the inner side of combustion air supply pipe 13 and the outer side of hydrogen-oxygen supply pipe 12. Combustion air is supplied by a blower and enters the combustion air channel 131 after being heated by an air preheater. The combustion air enters the furnace from the output end of combustion air channel 131, which is located outside the outlet of hydrogen-oxygen supply pipe 12. During burner operation, the combustion air serves as a later-added oxygen source, participating in the combustion process of pulverized coal and coke. Generally, the direct burner 1 is also equipped with a gas igniter. The gas igniter is usually arranged on the outer wall of hydrogen-oxygen supply pipe 12 or combustion air supply pipe 13, with its ignition end extending into the furnace, near the second nozzle 123, to ignite the initially injected hydrogen-oxygen mixture.

[0021] The working principle of this embodiment is as follows: pulverized coal is transported to the furnace through pulverized coal channel 111, combustion air is transported to the furnace through combustion air channel 131, and hydrogen-oxygen mixture is transported through hydrogen-oxygen channel and injected into the furnace through first nozzle 112 and second nozzle 123 for combustion. This avoids the formation of nitrogen oxides due to uneven distribution of hydrogen-oxygen mixture in localized flame temperatures. Simultaneously, the hydrogen-oxygen mixtures ejected from each nozzle form small flames that support each other for stable combustion, while also independently avoiding the formation of large, high-temperature zones of flames. This achieves the purpose of staged combustion to reduce NOx formation, reducing the range of high-temperature hydrogen-oxygen flames and shortening the residence time of high-temperature flue gas in the peak temperature zone, thereby reducing NOx formation. Furthermore, the hydrogen-oxygen mixture contains oxygen, eliminating the need for competition with pulverized coal combustion for oxygen in the combustion air. The hydrogen-oxygen combustion also provides high-temperature flue gas, which can reduce the carbon content of fly ash from pulverized coal combustion and improve combustion efficiency. The hydrogen-oxygen mixture has good flame stability, which can enhance the combustion stability of the direct burner 1, enhance the combustion stability of the boiler under low load operation, and improve the peak-shaving operation and wide coal type adaptability of the coal-fired boiler.

[0022] The direct burner 1 of this invention spatially divides and transports pulverized coal, a hydrogen-oxygen mixture, and combustion air into zones, and releases them in stages through a first nozzle 112 and a second nozzle 123. The axis of the first nozzle 112 converges with the axis of the pulverized coal channel 111, allowing the hydrogen-oxygen flame to directly act on the core area of ​​the pulverized coal jet, which is beneficial for improving the ignition conditions of the pulverized coal. The axis of the second nozzle 123 is parallel to the axis of the pulverized coal conveying pipe 11, causing the hydrogen-oxygen flame to form a co-flow around the pulverized coal jet, which plays a role in stabilizing combustion and enveloping heating. The coordinated arrangement of the two sets of nozzles ensures that the heat released by the hydrogen-oxygen combustion is distributed in both the radial and axial directions of the pulverized coal jet, which helps to improve the rigidity and stability of the flame. At the same time, multiple small-diameter nozzles disperse the hydrogen-oxygen mixture into numerous fine jets, which form a group of small flames that are independent and mutually supportive after combustion. This dispersed combustion method helps to control the size and peak temperature of local high-temperature areas, shortens the residence time of high-temperature flue gas in the peak temperature zone, and has an inhibitory effect on the generation of nitrogen oxides. In addition, the hydrogen-oxygen mixture contains oxygen, and its combustion process does not consume additional oxygen from the combustion air. Therefore, the combustion air can be used more for the combustion process of pulverized coal and coke, which helps to reduce the carbon content of fly ash.

[0023] For example, see Figure 1The distance L1 between the first focal point and the end face of the output end of the pulverized coal conveying pipe 11 is 100mm-500mm. When L1 is 100mm, the convergence point of the flame at the first nozzle 112 is close to the outlet of the pulverized coal conveying pipe 11. At this time, the flame heats the root of the pulverized coal jet faster, which is suitable for coal types that are difficult to ignite. When L1 is 500mm, the convergence point is far from the outlet, and the position of the flame heating the pulverized coal is moved backward, which is suitable for coal types with high volatile matter and can prevent premature ignition leading to nozzle slagging. The specific value of L1 can also be adjusted according to the actual installation position of the burner and the furnace size. For example, when the furnace space is large, a larger L1 value can be selected to allow the flame to develop fully in the furnace. The flame length at the second nozzle 123 is about 300mm. This length, in conjunction with the value of L1, ensures that the flames at the first nozzle 112 and the second nozzle 123 are staggered in axial position. If L1 is less than 100 mm, the flames from the first nozzle 112 and the second nozzle 123 are likely to merge near the exit, potentially leading to flame merging. If L1 is greater than 500 mm, the flames from the first nozzle 112 will extend a considerable distance before converging, weakening their initial heating effect on the pulverized coal jet and potentially prolonging the ignition time. Therefore, this spacing effectively prevents the flames from the first nozzle 112 and the second nozzle 123 from merging while ensuring proper ignition of the pulverized coal gas flow.

[0024] For example, see Figure 1 and 3 The output end sidewall of the pulverized coal conveying pipe 11 is provided with multiple first nozzle groups 113. Each first nozzle group 113 includes multiple first nozzles 112 evenly distributed around the axis of the pulverized coal conveying pipe 11, and these first nozzle groups 113 are arranged at intervals along the axial direction of the pulverized coal conveying pipe 11. The first nozzle groups 113 are divided into multiple rows along the axial direction, with each row of nozzles corresponding to a first focal point, and these focal points are located at different positions along the axial direction. During operation, the first nozzles 112 in different rows spray hydrogen-oxygen flames towards the center at their respective axial positions, forming multiple heating zones. These heating zones are distributed sequentially along the pulverized coal jet path. As the pulverized coal jet advances, it passes through each heating zone sequentially, and its temperature rises in a stepped manner. This segmented heating method helps control the heating rate of the pulverized coal, avoiding excessively high heat flux density on the pulverized coal particles in a short period of time, thereby reducing the risk of particle bursting or melting. Meanwhile, the multi-row nozzle configuration increases the flow area between the hydrogen-oxygen channel 121 and the furnace. Under the same hydrogen-oxygen supply, the injection speed of each row of nozzles can be appropriately reduced, which is beneficial to the stability of the jet.

[0025] For example, along the conveying direction of the pulverized coal conveying pipe 11, the distance between the first focal point corresponding to the multiple sets of first nozzle groups 113 and the end face of the output end of the pulverized coal conveying pipe 11 increases sequentially. Since the L1 value corresponding to the first nozzle group 113 closer to the output end of the pulverized coal conveying pipe 11 is smaller, and the L1 value corresponding to the first nozzle group 113 farther from the output end is larger, the flames of the upstream nozzles converge earlier, heating the front section of the pulverized coal jet; the flames of the downstream nozzles converge later, heating the rear section of the pulverized coal jet. The convergence points of the flames of each row of nozzles are arranged sequentially from front to back, forming a continuous heating zone along the pulverized coal jet direction. This allows the pulverized coal to continuously receive heat replenishment throughout the ignition area. Even if the flame of one row of nozzles is affected by fluctuations in pulverized coal concentration, the flames of other rows of nozzles still maintain a heating effect, thereby improving the adaptability of the combustion process to changes in operating conditions.

[0026] For example, see Figure 1 and 3 The end of the sealing plate 122 is provided with multiple second nozzle groups 124. Each second nozzle group 124 includes multiple second nozzles 123 evenly distributed around the axis of the pulverized coal conveying pipe 11, and these groups are arranged radially at intervals along the pulverized coal conveying pipe 11. The second nozzle groups 124 are arranged in multiple rings radially on the end face of the sealing plate 122, with each ring of nozzles distributed on a circumference of different diameters. The second nozzles 123 in the inner ring are close to the axis of the pulverized coal conveying pipe 11, while those in the outer ring are close to the inner wall of the hydrogen-oxygen conveying pipe 12. During operation, the flames of the inner ring nozzles are close to the boundary of the pulverized coal jet, directly heating the outer layer of the pulverized coal particles; the flames of the outer ring nozzles are slightly further away from the pulverized coal jet, mainly serving as a peripheral flow guide and stabilizing agent. The accompanying flame layer formed by the multiple ring nozzles has a certain thickness, which more completely envelops the pulverized coal jet, helping to reduce the dilution effect of the surrounding cold flue gas on the pulverized coal jet and maintain the temperature of the core area of ​​the pulverized coal jet.

[0027] For example, see Figure 1 The output end of the pulverized coal conveying pipe 11 is provided with an expansion section 114, which gradually expands outward along the conveying direction of the pulverized coal conveying pipe 11. When the pulverized coal gas flows through the expansion section 114, the flow cross-sectional area gradually increases, and the gas velocity decreases accordingly. After the velocity decreases, the residence time of pulverized coal particles in the furnace is prolonged, which is beneficial to the combustion process. At the same time, the inclined wall of the expansion section 114 guides the pulverized coal gas flow to diffuse outward, increasing the diameter of the pulverized coal jet, which is beneficial to forming a larger contact area with the surrounding hydrogen-oxygen flame and combustion air.

[0028] like Figure 4As shown, a preferred embodiment of the combustion system of the present invention includes the aforementioned direct burner 1 and an electrolytic water device 2. The hydrogen-oxygen output end of the electrolytic water device 2 is connected to the input end of the hydrogen-oxygen delivery pipe 12 via a gas delivery pipe 3. Each boiler can be equipped with multiple electrolytic water devices 2, and each electrolytic water device 2 provides a hydrogen-oxygen mixture to at least one direct burner 1. The input end of the pulverized coal delivery pipe 11 is connected to the outlet of the coal mill. The pulverized coal ground by the coal mill is carried by primary air and enters the pulverized coal channel 111 along the pipe. The input end of the combustion air delivery pipe 13 is connected to the outlet of the blower. The air supplied by the blower is heated by an air preheater and then enters the combustion air channel 131. The water electrolysis device 2 uses electrical energy to decompose water into hydrogen and oxygen. These two gases mix naturally inside the device to form a hydrogen-oxygen mixture. The hydrogen-oxygen mixture flows out from the output end of the water electrolysis device 2 and enters the gas delivery pipe 3. The gas delivery pipe 3 transports the hydrogen-oxygen mixture from the water electrolysis device 2 to the hydrogen-oxygen channel 121 inlet of the direct burner 1. Pulverized coal, the hydrogen-oxygen mixture, and the combustion-supporting air are supplied independently, and combustion is organized in the burner outlet area.

[0029] The gas delivery pipeline 3 is equipped with a flow regulating valve, a pressure regulating valve, a pressure sensor, and a temperature sensor. The flow regulating valve adjusts the flow rate of the hydrogen-oxygen mixture in the pipeline 3 to ensure a stable flow rate. The pressure regulating valve adjusts the pressure of the hydrogen-oxygen mixture in the pipeline 3 to ensure a stable pressure. The pressure sensor uses a pressure transmitter to measure and record the pressure of the hydrogen-oxygen mixture in the pipeline in real time; multiple pressure sensors can be set. The temperature sensor is used to detect the temperature of the gas in the pipeline 3. At least three temperature sensors are installed, with at least one installed at the input end of the pipeline 3. The pipeline 3 is also equipped with a local pressure gauge, a local thermometer, and a flow meter to detect the pressure, temperature, and flow rate of the gas in the pipeline. This facilitates data observation and recording by on-site personnel. A remote flow meter can be selected for personnel in the control room, allowing them to monitor the gas flow rate remotely.

[0030] The combustion system directly couples the water electrolysis device 2 with the direct burner 1. The hydrogen-oxygen mixture generated by water electrolysis is sent to the hydrogen-oxygen channel 121 through the gas delivery pipe 3. It can be used directly for combustion without purification and separation, thus saving the investment in purification equipment and the corresponding energy consumption, which is conducive to improving the economy and energy efficiency of the overall process. The direct burner 1 uses a three-layer coaxial nested structure to deliver pulverized coal, hydrogen-oxygen mixture and combustion air in separate zones. The hydrogen-oxygen mixture converges towards the center of the pulverized coal jet through the first nozzle 112, which can directly heat the ignition area, which helps to shorten the ignition distance and improve the ignition performance of low volatile coal types. The second nozzle 123 forms a co-current flame around the pulverized coal jet, which plays a role in stabilizing combustion and wrapping heating, which helps to enhance flame stability and improve the adaptability of the boiler under low load operation and coal type change conditions. Multiple small-diameter nozzles disperse the hydrogen-oxygen mixture into fine jets, forming small, independent yet mutually supporting flame clusters. This helps control the size of localized high-temperature zones and shortens the residence time of high-temperature flue gas in the peak temperature zone, thus inhibiting the formation of nitrogen oxides. The hydrogen-oxygen mixture contains its own oxygen, and its combustion process does not consume additional oxygen from the combustion air. Therefore, the combustion air can be used more effectively for the complete combustion of pulverized coal and coke, helping to reduce the carbon content of fly ash and preventing a decrease in boiler efficiency.

[0031] For example, see Figure 4 The combustion system also includes a nitrogen blowing device 4. The output end of the gas delivery pipe 3 is provided with a first shut-off valve 31, and the input end of the gas delivery pipe 3 is provided with a second shut-off valve 32. The nitrogen blowing device 4 is provided with a first blowing pipe 41 and a second blowing pipe 42. The output ends of the first blowing pipe 41 and the second blowing pipe 42 are respectively connected to the gas delivery pipe 3. The connection point between the first blowing pipe 41 and the gas delivery pipe 3 is located at the outlet end of the first shut-off valve 31, and the connection point between the second blowing pipe 42 and the gas delivery pipe 3 is located at the outlet end of the second shut-off valve 32.

[0032] In this embodiment, pneumatic switching valves are respectively provided on the first purge pipe 41 and the second purge pipe 42. The temperature detector, the first shut-off valve 31, the second shut-off valve 32, the nitrogen purge device 4, and the pneumatic switching valves are electrically connected to the controller. When the temperature detected by the temperature detector is greater than the set value (e.g., 60°C), it is determined that there is a risk of backfire in the pipeline. The controller controls the first shut-off valve 31 and the second shut-off valve 32 to close. At the same time, the controller controls the nitrogen purge device 4 to deliver nitrogen to the gas delivery pipe 3 through the first purge pipe 41 to extinguish the flame at the nozzle of the direct burner 1. In addition, before the direct burner 1 stops operating, the controller controls the second shut-off valve 32 to close. The nitrogen purge device 4 delivers nitrogen to the gas delivery pipe 3 through the second purge pipe 42 to discharge the residual hydrogen-oxygen mixture in the gas delivery pipe 3 and gradually extinguish the flame at the nozzle of the direct burner 1.

[0033] For example, see Figure 4At least two first flame arresters 33 are provided on the gas delivery pipe 3, with one flame arrester 33 at both the inlet and outlet ends. The flame arrester at the inlet end is located near the water electrolysis device 2 to prevent flames from flowing back from the delivery pipe into the water electrolysis device 2; the flame arrester at the outlet end is located near the direct combustion unit to prevent flames in the burner area from propagating backward along the gas delivery pipe 3. The two flame arresters form two layers of protection along the gas delivery path, which helps to improve the safety of the hydrogen-oxygen mixture delivery process.

[0034] For example, see Figure 4 The gas delivery pipe 3 is connected to a vent pipe 5, which is equipped with a switch valve 51, a check valve 52, and a second flame arrester 53. When the direct burner 1 stops operating, but the water electrolysis unit 2 continues operating, the switch valve 51 is opened, allowing the generated hydrogen-oxygen mixture to be released into the atmosphere through the vent system. The vent pipe 5 extends from the gas delivery pipe 3, and its specific location is determined according to system safety requirements. The switch valve 51 is normally closed, but opens when venting is required, allowing the hydrogen-oxygen mixture to be discharged into the atmosphere through the vent pipe 5. The check valve 52 is installed downstream of the switch valve 51, and its function is to prevent air or external gases from flowing back into the gas delivery pipe 3 through the vent pipe 5, as backflow of air may introduce oxygen, altering the hydrogen-oxygen mixture ratio, or forming an explosive mixture within the pipeline. The flame arrester is located at the outlet end of the vent pipe 5 or downstream of the check valve 52 to prevent external ignition sources or flames from burning at the end of the pipeline from entering the gas delivery pipe 3.

[0035] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A direct burner, characterized in that: include: The pulverized coal conveying pipe has an internal pulverized coal channel. A hydrogen-oxygen delivery pipe is coaxially sleeved on the pulverized coal delivery pipe. A hydrogen-oxygen channel is formed between the inner side of the hydrogen-oxygen delivery pipe and the outer side of the pulverized coal delivery pipe. The output end sidewall of the pulverized coal delivery pipe is provided with a plurality of first nozzles evenly distributed around the axis of the pulverized coal delivery pipe. The axes of the plurality of first nozzles intersect with the axis of the pulverized coal delivery pipe at a first focal point. A sealing plate is provided between the output end of the hydrogen-oxygen conveying pipe and the output end of the pulverized coal conveying pipe. The end of the sealing plate is provided with a plurality of second nozzles evenly distributed around the axis of the pulverized coal conveying pipe. The axis of the second nozzles is parallel to the axis of the pulverized coal conveying pipe. And a combustion-supporting air delivery pipe, coaxially sleeved on the hydrogen-oxygen delivery pipe, forming a combustion-supporting air channel between the inner side of the combustion-supporting air delivery pipe and the outer side of the hydrogen-oxygen delivery pipe.

2. The direct burner according to claim 1, characterized in that: The distance between the first focal point and the end face of the output end of the pulverized coal conveying pipe is 100mm-500mm.

3. The direct burner according to claim 1, characterized in that: The output end sidewall of the pulverized coal conveying pipe is provided with a plurality of first nozzle groups. Each first nozzle group includes a plurality of first nozzles evenly distributed around the axis of the pulverized coal conveying pipe. The plurality of first nozzle groups are arranged at intervals along the axial direction of the pulverized coal conveying pipe.

4. The direct burner according to claim 3, characterized in that: Along the conveying direction of the pulverized coal conveying pipe, the distance between the first focal point corresponding to the multiple sets of first nozzle groups and the end face of the output end of the pulverized coal conveying pipe increases sequentially.

5. The direct burner according to claim 1, characterized in that: The end of the sealing plate is provided with a plurality of second nozzle groups, each of which includes a plurality of second nozzles evenly distributed around the axis of the pulverized coal conveying pipe, and the plurality of second nozzle groups are arranged at radial intervals along the pulverized coal conveying pipe.

6. The direct burner according to claim 1, characterized in that: The output end of the pulverized coal conveying pipe is provided with an expansion section, which gradually expands outward along the conveying direction of the pulverized coal conveying pipe.

7. A combustion system, characterized in that: Includes the direct burner as described in any one of claims 1-6 and the water electrolysis device, wherein the hydrogen and oxygen output end of the water electrolysis device is connected to the input end of the hydrogen and oxygen delivery pipe via a gas delivery pipe.

8. The combustion system according to claim 7, characterized in that: It also includes a nitrogen blowing device, wherein the output end of the gas delivery pipe is provided with a first shut-off valve, the input end of the gas delivery pipe is provided with a second shut-off valve, the nitrogen blowing device is provided with a first blowing pipe and a second blowing pipe, the output ends of the first blowing pipe and the output ends of the second blowing pipe are respectively connected to the gas delivery pipe, the connection point of the first blowing pipe and the gas delivery pipe is located at the gas outlet end of the first shut-off valve, and the connection point of the second blowing pipe and the gas delivery pipe is located at the gas outlet end of the second shut-off valve.

9. The combustion system according to claim 7, characterized in that: The gas delivery pipe is provided with at least two first flame arresters, and the input end and output end of the gas delivery pipe are respectively provided with the first flame arresters.

10. The combustion system according to claim 7, characterized in that: The gas delivery pipe is connected to a vent pipe, and the vent pipe is equipped with a switch valve, a check valve, and a second flame arrester.

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