A low-nitrogen burner

Abstract

The utility model relates to the technical field of combustion equipment, concretely to a low nitrogen combustor, including combustor unit, flue gas recirculation unit, air supply unit, air induction unit, water supply unit and electrical control unit and with hydrogen -fired boiler original hearth intercommunication's flue gas duct, combustor unit includes hydrogen gas special -purpose combustor and supporting safety component, flue gas recirculation unit includes circulating fan, circulating flue gas pipeline and automatic regulating valve, in this low nitrogen combustor, on one hand, combustor adopts high -temperature -resistant antioxidant special alloy material combustion disc, and optimization combustion structure makes hydrogen realize even, fully combustion in hearth, avoids local high temperature area formation, on the other hand, flue gas recirculation unit through circulating fan will introduce boiler tail low temperature flue gas into the air inlet of combustor, and after mixing with combustion air, enters hearth, effectively reduces combustion area temperature and oxygen concentration, reduces thermal type NOx generation from reaction condition.

Description

Technical Field

[0001] This utility model relates to the field of combustion equipment technology, and more specifically, to a low-NOx burner. Background Technology

[0002] With the accelerated global energy structure transformation and increasingly stringent environmental regulations, the industrial sector's demand for efficient and clean combustion technologies is becoming increasingly urgent. Hydrogen, as a zero-carbon fuel, emits no carbon dioxide during combustion, demonstrating significant application potential in industrial boilers and heat supply, and becoming a crucial direction for promoting the low-carbon transformation of traditional high-energy-consuming industries. However, the combustion characteristics of hydrogen differ significantly from those of traditional fossil fuels. Its combustion speed reaches 292 m / s, approximately eight times that of natural gas, and it easily forms localized high-temperature zones during combustion (flame center temperatures can reach over 1500℃), leading to the generation of large amounts of thermal nitrogen oxides (NOx). This type of NOx, produced by the oxidation of nitrogen in the air at high temperatures, dominates NOx emissions from gas-fired boilers, severely restricting the large-scale application of hydrogen in low-emission scenarios.

[0003] Currently, industrial hydrogen-fired boilers generally use ordinary burners, which have two major technical pain points: First, the combustion efficiency is low. Hydrogen is prone to uneven combustion and local overheating in the furnace, which not only wastes fuel but also leads to higher flue gas temperatures, further reducing thermal efficiency. Second, NOx emissions are difficult to meet standards. Under existing conventional combustion technologies, the NOx concentration in the flue gas of hydrogen-fired boilers often exceeds 120 mg / Nm³, which is far higher than the "ultra-low emission index (NOx≤50 mg / Nm³) for gas-fired boilers" in the national "Emission Standard of Air Pollutants for Boilers" (GB 13271-2014). In some areas, non-compliance with emission standards even poses the risk of production restrictions or shutdowns, affecting the normal production and operation of enterprises.

[0004] To address these issues, the industry has attempted to adopt technologies such as low-NOx burners and flue gas recirculation (FGR). However, existing solutions are mostly designed for conventional fuels such as natural gas and liquefied petroleum gas, and are difficult to adapt to the special combustion characteristics of hydrogen. On the one hand, the combustion disc material of ordinary low-NOx burners is not resistant to high temperatures and oxidation, and is prone to deformation and corrosion in the high-temperature combustion environment of hydrogen, leading to decreased combustion stability and even safety hazards. On the other hand, traditional FGR systems have not optimized the flue gas mixing ratio and duct design for the high speed and high temperature characteristics of hydrogen combustion. During flue gas recirculation, problems such as furnace oxygen deficiency and incomplete combustion are prone to occur, which not only fail to effectively reduce NOx generation, but may also increase emissions of byproducts such as carbon monoxide.

[0005] Furthermore, as continuously operating equipment, the safety and reliability of the combustion system of industrial boilers are of paramount importance. Hydrogen is a flammable and explosive gas, and the safety protection design of existing hydrogen combustion systems (such as explosion-proof rating, leak detection, and flameout protection) often has shortcomings. Problems such as insufficient explosion-proof rating of hydrogen pipelines and lack of multiple interlocking protections in the ignition procedure can easily lead to safety accidents such as furnace deflagration and hydrogen leakage, further limiting the application and promotion of low-NOx combustion technology in hydrogen boilers. Summary of the Invention

[0006] The purpose of this invention is to provide a low-NOx burner to solve the problems mentioned in the background art, such as low combustion efficiency, uneven combustion of hydrogen in the furnace, and local overheating, which not only waste fuel but also lead to high boiler flue gas temperature and further reduce thermal efficiency.

[0007] To achieve the above objectives, this utility model provides a low-NOx burner, including a burner unit, a flue gas recirculation unit, an air supply unit, an induced draft unit, a water supply unit, and an electrical control unit; The burner unit includes a hydrogen-specific burner and supporting safety components; the flue gas recirculation unit includes a circulating fan, a circulating flue gas duct, and an automatic regulating valve. One end of the circulating flue gas duct is connected to the tail flue of the hydrogen-fired boiler, and the other end is connected to the air inlet of the burner unit. The automatic regulating valve is installed on the circulating flue gas duct. A set of hydrogen regulating valves is installed at the gas inlet of the hydrogen-specific burner.

[0008] This setup integrates core modules such as the burner unit and the flue gas recirculation unit to construct a complete combustion system adapted to hydrogen-fired boilers. The dedicated hydrogen burner serves as the core of the combustion process, simultaneously receiving combustion air and recirculated flue gas through the air inlet. The flue gas recirculation unit introduces low-temperature flue gas from the boiler tail into the combustion system, utilizing the inert components in the flue gas to reduce the oxygen concentration and temperature in the combustion zone, thus suppressing the formation of nitrogen oxides. An automatic regulating valve adjusts the amount of recirculated flue gas to adapt to combustion requirements under different operating conditions.

[0009] Preferably, the combustion disc of the hydrogen-specific burner is made of a high-temperature resistant and oxidation-resistant special alloy material, and the supporting safety components include a hydrogen pipeline. Furthermore, the hydrogen-specific burner integrates an FGR low-NOx combustion module.

[0010] This design addresses the characteristics of hydrogen combustion equipment, which has high combustion temperatures (up to 1500℃ and above) and is prone to oxidation. It uses a high-temperature resistant and oxidation-resistant special alloy material to make the combustion disc, improving the weather resistance of the combustion components. It integrates an FGR low-NOx combustion module to optimize the mixing ratio of hydrogen with air and circulating flue gas, achieving staged combustion. It is equipped with safety components (such as hydrogen pipelines) to meet the explosion-proof requirements for hydrogen transportation.

[0011] Preferably, the power distribution control panel integrates a PLC controller and a frequency converter. The PLC controller adopts the Siemens S71200 series. The electrical control system includes RTGW-20 type field explosion-proof instruments and DⅡCT4 level local explosion-proof boxes. There are 4 pressure transmitters, which are used to collect steam pressure, hydrogen pressure, air supply pressure and flue gas pressure signals respectively. The PLC controller is electrically connected to the motors and valves in the burner unit, flue gas recirculation unit, air supply unit, induced draft unit and water supply unit to realize automatic control.

[0012] This setup constructs a multi-level control and monitoring system, with the power distribution control panel serving as the control core, the electrical control system responsible for driving field equipment, the local pneumatic control box enabling local operation, and the pressure transmitter collecting key parameters in real time, forming a closed loop of "monitoring-control-execution".

[0013] Preferably, the air supply unit includes a blower, and the air outlet of the blower is connected to the air inlet of the burner unit through an air duct.

[0014] This setup uses a Siemens S71200 series PLC controller as its core, and adjusts the speed of each unit's motor through a frequency converter; four pressure transmitters collect steam, hydrogen, air supply, and flue gas pressure signals respectively, and the PLC automatically adjusts parameters such as fuel supply and air volume according to preset logic to achieve coordinated operation of each unit; explosion-proof instruments and explosion-proof enclosures meet the safety requirements of hydrogen environments.

[0015] Preferably, the induced draft unit includes an induced draft fan, the air inlet of which is connected to the tail flue of the hydrogen-fired boiler.

[0016] This setup involves a blower delivering combustion air to the burner's air inlet via a duct. The air mixes with the circulating flue gas at the air inlet before entering the combustion zone, providing sufficient oxygen for hydrogen combustion. At the same time, the combustion intensity is controlled by adjusting the airflow.

[0017] Preferably, the water supply unit includes a water supply pump, a deaerator pump, and an energy saver. The number of water supply pumps is two, and they operate in a one-on-one standby mode. The number of deaerator pumps is two. The energy saver is connected in series with the water supply circuit of the hydrogen-fired boiler.

[0018] This setup uses an induced draft fan to create negative pressure in the furnace through the tail flue, drawing out the flue gas generated during combustion. This maintains normal furnace pressure (avoiding positive pressure that could cause flue gas to overflow) and provides a source of flue gas for the flue gas recirculation unit.

[0019] Preferably, the electrical control unit includes a power distribution control panel, an electrical control system, a local pneumatic control box, and a pressure transmitter.

[0020] This setup includes a feedwater pump (one operational and one standby) to ensure a continuous supply of feedwater to the boiler, a deaerator to remove dissolved oxygen from the water (to prevent boiler corrosion), and an economizer to use waste heat from the tail flue gas to heat the feedwater, reducing the boiler's heating load.

[0021] Compared with the prior art, the beneficial effects of this utility model are as follows: This low-NOx burner utilizes a synergistic design of a dedicated hydrogen burner and FGR (Flue Gas Recirculation) to suppress thermal NOx formation at its source. Firstly, the burner employs a high-temperature resistant, oxidation-resistant special alloy combustion disc, optimizing the combustion structure to ensure uniform and complete hydrogen combustion within the furnace, preventing the formation of localized high-temperature zones. Secondly, the flue gas recirculation unit uses a circulating fan to introduce low-temperature flue gas from the boiler's tail end into the burner's air inlet, mixing it with combustion air before it enters the furnace. This effectively reduces the temperature in the combustion zone (preventing local temperatures from exceeding 1500℃) and oxygen concentration, thus decreasing thermal NOx formation from the reaction conditions. In practical applications, the NOx concentration in hydrogen-fired boiler flue gas can be reduced from 120 mg / Nm³ to below 50 mg / Nm³, fully complying with national ultra-low emission standards for gas-fired boilers. This addresses the risks of production restrictions and shutdowns faced by enterprises due to non-compliance with emission standards, facilitating compliant production for businesses.

[0022] This burner improves energy efficiency through multiple design features: First, the optimized structure and full combustion mode of the dedicated hydrogen burner reduce hydrogen waste caused by incomplete combustion; second, the low-temperature flue gas introduced by the flue gas recirculation unit recovers waste heat from the tail flue gas, reducing exhaust gas temperature (by approximately 10%) and minimizing heat loss; third, the economizer in the feedwater unit is connected in series with the boiler feedwater circuit to further recover waste heat from the flue gas to heat the feedwater, reducing the boiler heating load. Under these combined effects, the boiler thermal efficiency can be increased by approximately 4.1%, significantly reducing the enterprise's energy costs and operating burden.

[0023] To address the flammable and explosive nature of hydrogen, this burner incorporates comprehensive safety protection throughout the entire process: First, the hydrogen pipeline adopts a DIICT4 explosion-proof rating, and the burner is equipped with dedicated safety components to prevent the risk of explosion caused by hydrogen leakage; second, in the electrical control unit, the RTGW-20 type field explosion-proof instrument is compatible with the DIICT4 level local explosion-proof box, meeting the explosion-proof requirements in a hydrogen environment; third, the PLC control system has complete safety interlock logic, requiring at least 3 minutes of furnace purging before ignition and at least 2 minutes of post-ignition purging, and the hydrogen valve is only opened after the flame detector detects the ignition flame. If ignition fails, the hydrogen supply is immediately cut off and an audible and visual alarm is triggered, eliminating the risk of furnace deflagration from the operational procedures. Simultaneously, the air supply, induced draft, and circulating air units all use variable frequency explosion-proof motors to ensure stable operation of the equipment in a hydrogen environment, significantly reducing the incidence of safety accidents and ensuring continuous and reliable production of the hydrogen-fired boiler.

[0024] The electrical control unit adopts a Siemens S71200 series PLC controller, integrating a frequency converter and multi-parameter acquisition functions: four pressure transmitters respectively collect steam pressure, hydrogen pressure, air supply pressure, and flue gas pressure signals. The PLC controller automatically adjusts the burner fuel supply and the air volume of the forced draft / induced draft / circulating air according to the signals, realizing adaptive control "based on steam pressure"—when the hydrogen output is insufficient, it can automatically complete the fuel ratio adjustment and air volume matching without manual intervention; at the same time, the control system reserves an Ethernet communication interface, and reserves 10% of the switch and analog points, which simplifies the on-site operation process, reduces human operation errors, facilitates subsequent system expansion and maintenance, reduces equipment failure points and operation and maintenance difficulty, and improves the overall operational stability and intelligence level of the combustion system. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a schematic diagram of the burner unit in this utility model; Figure 3 This is a schematic diagram of the flue gas recirculation unit in this utility model; Figure 4 This is a schematic diagram of the air supply unit in this utility model; Figure 5 This is a schematic diagram of the air intake unit in this utility model; Figure 6 This is a schematic diagram of the water supply unit in this utility model; Figure 7 This is a schematic diagram of the electrical control unit in this utility model; The meanings of the labels in the diagram are as follows: 1. Burner unit; 11. Hydrogen-specific burner; 12. Air inlet; 13. Combustion port; 14. Hydrogen regulating valve assembly; 2. Flue gas recirculation unit; 21. Circulating fan; 22. Circulating flue gas duct; 23. Automatic regulating valve; 3. Air supply unit; 31. Blower; 32. Air duct; 4. Induced draft unit; 41. Induced draft fan; 42. Air inlet; 5. Water supply unit; 51. Water supply pump; 52. Deaerator pump; 53. Energy saver; 6. Electrical control unit; 61. Power distribution control panel; 62. Electrical control system; 63. Local gas control box; 64. Pressure transmitter; 8. Hydrogen-fired boiler. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0027] This invention provides a low-NOx burner, such as... Figures 1-7 As shown, it includes a burner unit 1, a flue gas recirculation unit 2, an air supply unit 3, an induced draft unit 4, a water supply unit 5, an electrical control unit 6, and a flue gas duct connected to the original furnace of the hydrogen-fired boiler 8. Burner unit 1 includes a dedicated hydrogen burner 11 and supporting safety components; flue gas recirculation unit 2 includes a circulating fan 21, a circulating flue gas duct 22, and an automatic regulating valve 23. One end of the circulating flue gas duct 22 is connected to the tail flue of the hydrogen-fired boiler 8, and the other end is connected to the air inlet 12 of burner unit 1. The automatic regulating valve 23 is installed on the circulating flue gas duct 22. A hydrogen regulating valve assembly 14 is installed at the gas inlet of the dedicated hydrogen burner 11. The functions of the hydrogen regulating valve assembly 14 are: first, to automatically cut off the hydrogen supply in an emergency to ensure boiler safety; and second, to automatically regulate the boiler load.

[0028] By integrating six core modules—burner unit 1, flue gas recirculation unit 2, air supply unit 3, induced draft unit 4, water supply unit 5, and electrical control unit 6—a complete combustion system adapted to the hydrogen-fired boiler 8 is constructed. Specifically, the hydrogen-dedicated burner 11 in burner unit 1 serves as the core of the combustion process. Its air inlet 12 simultaneously receives combustion air supplied by air supply unit 3 and recirculated flue gas introduced by flue gas recirculation unit 2. The circulating fan 21 of flue gas recirculation unit 2 drives the low-temperature flue gas at the boiler tail, which is then transported to the air inlet 12 via circulating flue gas duct 22. The inert components in the flue gas reduce the oxygen concentration and temperature in the combustion zone, suppressing nitrogen oxide generation. Furthermore, the automatic regulating valve 23 on the circulating flue gas duct 22 can flexibly adjust the circulating flue gas volume to adapt to combustion requirements under different loads. The combustion port 13 of the hydrogen-dedicated burner 11 is directly connected to the furnace of the hydrogen-fired boiler 8, ensuring a stable combustion flame acting on the furnace.

[0029] The basic framework for stable hydrogen combustion and nitrogen oxide emission reduction is established. The temperature of the combustion zone is initially reduced through the flue gas recirculation unit 2, laying the core framework for subsequent low-NOx emission optimization. The modular design allows each module, such as burner unit 1 and flue gas recirculation unit 2, to be independently debugged and maintained. The precise connection between the circulating flue gas pipeline 22 and the air inlet 12 reduces the risk of flue gas leakage, ensures stable combustion conditions, and meets the basic operating requirements of the hydrogen-fired boiler 8.

[0030] In this embodiment, the combustion disc of the hydrogen-dedicated burner 11 is made of a high-temperature resistant and oxidation-resistant special alloy material, and the supporting safety components include hydrogen pipelines. The hydrogen-dedicated burner 11 also integrates an FGR low-NOx combustion module.

[0031] In response to the characteristics of hydrogen combustion temperatures reaching over 1500℃ and the ease with which it oxidizes equipment, the combustion disc of the hydrogen-dedicated burner 11 is made of a high-temperature resistant and oxidation-resistant special alloy material, enhancing its resistance to deformation and corrosion in high-temperature combustion environments. The hydrogen pipeline in the supporting safety components is designed according to explosion-proof standards to prevent safety accidents caused by leaks during hydrogen transportation. At the same time, the hydrogen-dedicated burner 11 integrates an FGR low-NOx combustion module, which optimizes the mixing ratio of hydrogen with the combustion air and circulating flue gas supplied from the air inlet 12, achieving staged combustion and further suppressing the generation of thermal nitrogen oxides.

[0032] The special alloy combustion disc has a service life 3-5 times longer than that of ordinary materials, completely solving the problem of traditional combustion discs being easily damaged in the high-temperature hydrogen environment and reducing the frequency of equipment replacement; the FGR low-NOx combustion module works in synergy with the burner unit 1 to reduce nitrogen oxide emissions; the hydrogen pipeline with matching safety components meets explosion-proof requirements, reducing the risk of accidents caused by hydrogen leakage to a minimum and improving the overall safety of the combustion system.

[0033] Specifically, the power distribution control panel 61 integrates a PLC controller and a frequency converter. The PLC controller adopts the Siemens S71200 series. The electrical control system 62 includes RTGW-20 type field explosion-proof instruments and DⅡCT4 level local explosion-proof boxes. There are 4 pressure transmitters 64, which are used to collect steam pressure, hydrogen pressure, air supply pressure and flue gas pressure signals respectively. The PLC controller is electrically connected to the motors and valves in the burner unit 1, flue gas recirculation unit 2, air supply unit 3, induced draft unit 4 and water supply unit 5 to realize automatic control.

[0034] Furthermore, the electrical control unit 6 includes a power distribution control panel 61, an electrical control system 62, a local gas control box 63, and a pressure transmitter 64. The electrical control unit 6 constructs a multi-layered system of "core control - field execution - local operation - parameter monitoring": the power distribution control panel 61 serves as the control core, responsible for command calculation and output; the electrical control system 62 connects to field equipment to realize the execution of control commands; the local gas control box 63 provides a local operation interface, facilitating on-site debugging and emergency operation by maintenance personnel; the pressure transmitter 64 collects key parameters of the combustion system in real time and feeds the data back to the power distribution control panel 61, forming a complete "monitoring - control - execution" closed loop.

[0035] Through the collaboration of the power distribution control panel 61, the electrical control system 62, the local gas control box 63, and the pressure transmitter 64, the combustion system can achieve full-state monitoring and multi-scenario operation control, adapting to the on-site management mode of industrial boilers; the real-time monitoring of the pressure transmitter 64 allows maintenance personnel to grasp the system's operating status in a timely manner, reducing troubleshooting time and improving system operation and maintenance efficiency.

[0036] Furthermore, the air supply unit 3 includes a blower 31, and the air outlet of the blower 31 is connected to the air inlet 12 of the burner unit 1 through the air duct 32.

[0037] After the blower 31 of the air supply unit 3 is started, it delivers combustion air to the air inlet 12 of the burner unit 1 through the air duct 32. The combustion air is fully mixed with the circulating flue gas delivered by the flue gas recirculation unit 2 at the air inlet 12. After forming a mixed airflow, it enters the combustion zone of the hydrogen-specific burner 11 to provide sufficient and stable oxygen for hydrogen combustion. At the same time, the air supply volume can be controlled by adjusting the speed of the blower 31, thereby regulating the combustion intensity and adapting to the different steam requirements of the hydrogen boiler 8.

[0038] A stable supply of combustion air ensures that hydrogen is fully combusted in the hydrogen-specific burner 11, avoiding incomplete combustion caused by lack of oxygen and keeping carbon monoxide emissions below 50 ppm. The air duct 32 adopts a low-resistance design, reducing energy loss during air transport. Compared with ordinary air ducts, the blower 31 consumes less energy, achieving energy-saving operation.

[0039] Furthermore, the induced draft unit 4 includes an induced draft fan 41, the air inlet 42 of which is connected to the tail flue of the hydrogen-fired boiler 8.

[0040] After the induced draft fan 41 of the induced draft unit 4 is started, it is connected to the tail flue of the hydrogen boiler 8 through its air inlet 42, forming a stable negative pressure in the furnace, usually controlled between -5Pa and -10Pa. On the one hand, it extracts the flue gas generated by the combustion of hydrogen in the furnace in a timely manner, preventing the positive pressure in the furnace from causing the flue gas to overflow and ensuring the safety of the on-site operating environment. On the other hand, part of the extracted flue gas provides a stable flue gas source for the circulating flue gas pipeline 22 of the flue gas recirculation unit 2, and the other part is discharged through the tail flue, maintaining the flow balance of the entire flue gas system.

[0041] The furnace pressure control accuracy reaches ±5Pa, effectively avoiding boiler overpressure or flue gas leakage accidents caused by abnormal pressure, and ensuring the safe operation of hydrogen boiler 8; the stable flue gas flow driven by induced draft fan 41 accelerates heat exchange in the furnace, reduces the exhaust gas temperature at the tail flue of hydrogen boiler 8, reduces heat loss, and indirectly improves boiler thermal efficiency.

[0042] Furthermore, the water supply unit 5 includes a water supply pump 51, a deaerator pump 52, and an energy saver 53. There are two water supply pumps 51, which operate in a one-on-one standby mode. There are two deaerator pumps 52. The energy saver 53 is connected in series with the water supply circuit of the hydrogen-fired boiler 8.

[0043] In the feedwater unit 5, two feedwater pumps 51 operate in a one-on-one standby mode to ensure a continuous supply of feedwater that meets the water quality requirements to the hydrogen-fired boiler 8, avoiding water outages and boiler shutdowns caused by single pump failures. Two deaerator pumps 52 are responsible for removing dissolved oxygen from the feedwater to prevent oxygen from corroding the boiler's inner wall metal and extending the boiler's service life. The energy-saving device 53 is connected in series with the feedwater circuit of the hydrogen-fired boiler 8, using the waste heat of the high-temperature flue gas discharged from the tail flue of the hydrogen-fired boiler 8 to heat the feedwater, reducing the heating load after the feedwater enters the boiler and realizing energy recovery and utilization.

[0044] The design of one standby and one operational feedwater pump 51 increases the reliability of the feedwater system to 99.9%, completely eliminating the possibility of boiler shutdown due to water shortage and ensuring continuous production. The deaerator pump 52 can reduce the dissolved oxygen content in the feedwater to below 0.05 mg / L, effectively slowing down the internal corrosion rate of the boiler and extending the boiler maintenance cycle. The economizer 53 can recover the waste heat from the flue gas at the tail end of the hydrogen boiler 8, increasing the feedwater temperature and thus improving the overall thermal efficiency of the hydrogen boiler 8, achieving significant energy-saving effects.

[0045] The low-NOx burner of this utility model is used in the following steps: (a) Start-up preparation phase The operator starts the system through the local gas control box 63 of the electrical control unit 6 or the power distribution program control panel 61. The PLC controller first performs a self-test, and the pressure transmitter 64 collects the steam pressure of the hydrogen boiler 8, the hydrogen pressure of the hydrogen-dedicated burner 11, the air supply pressure of the air supply unit 3, and the flue gas pressure of the tail flue of the hydrogen boiler 8 to confirm that each parameter is within a safe range (such as stable hydrogen pressure and no leakage signal).

[0046] The induced draft fan 41 of the induced draft unit 4 starts and connects to the tail flue of the hydrogen-fired boiler 8 through the air inlet 42, establishing a stable negative pressure of -5Pa to -10Pa in the furnace to prevent flue gas from overflowing during subsequent combustion. At the same time, the feed water pump 51 (main pump) and the deaerator pump 52 (main pump) of the feed water unit 5 start. The deaerator pump 52 removes dissolved oxygen from the feed water (to below 0.05mg / L), and the feed water pump 51 delivers the treated feed water to the economizer 53. The economizer 53 uses the residual heat at the tail of the hydrogen-fired boiler 8 to preheat the feed water. The preheated feed water enters the hydrogen-fired boiler 8, completing the boiler water replenishment preparation.

[0047] (II) Combustion Start-up and Low-NOx Regulation Stage When the blower 31 of the air supply unit 3 starts, it delivers combustion air to the air inlet 12 of the burner unit 1 through the air duct 32. The PLC controller adjusts the frequency of the frequency converter of the blower 31 according to the air supply pressure signal fed back by the pressure transmitter 64 to control the air supply volume. At the same time, the circulating fan 21 of the flue gas recirculation unit 2 starts, and delivers the low-temperature flue gas at the tail of the hydrogen boiler 8 to the air inlet 12 through the circulating flue gas pipeline 22 to mix with the combustion air. The operator can adjust the circulating flue gas volume through the automatic regulating valve 23 to adapt to the current combustion load.

[0048] The hydrogen-dedicated burner 11 starts the ignition procedure: The PLC controller first controls the furnace to purge (duration ≥ 3 minutes) to remove residual combustible gases; after the purging is completed, the ignition device is started. After the flame detector detects the ignition flame, the hydrogen valve of the hydrogen-dedicated burner 11 is opened, and hydrogen enters the combustion zone through the explosion-proof hydrogen pipeline. The mixed airflow (combustion air + circulating flue gas) with the air inlet 12 is ignited at the combustion port 13 to form a stable flame. The flame directly acts on the original furnace of the hydrogen boiler 8 to start heating the feedwater to generate steam.

[0049] During combustion, the FGR low-NOx combustion module continuously optimizes the mixing ratio of hydrogen and mixed gas flow to achieve staged combustion; the pressure transmitter 64 monitors the steam pressure in real time. If the steam pressure is lower than the set value, the PLC controller automatically increases the hydrogen supply and blower volume, while adjusting the speed of the circulating fan 21 to maintain a balance between combustion intensity and low-NOx effect; if ignition fails, the PLC controller immediately closes the hydrogen valve, triggers an audible and visual alarm, and enters the fault handling mode.

[0050] (III) Stable Operation Phase Each unit enters a coordinated and stable operating state: the induced draft fan 41 continuously maintains the negative pressure in the furnace to ensure the orderly flow of flue gas generated by combustion—part of the flue gas enters the flue gas recirculation unit 2 through the circulating flue gas pipe 22, and part of the flue gas carrying waste heat is discharged after passing through the economizer 53 (heating feedwater); in the feedwater unit 5, if the main feedwater pump 51 or the main deaerator pump 52 fails, the standby pump automatically switches to ensure continuous feedwater supply, and the economizer 53 continuously recovers 3%-5% of the waste heat from the flue gas, thereby increasing the feedwater temperature and improving the overall thermal efficiency of the hydrogen-fired boiler 8.

[0051] The electrical control unit 6 monitors the system status in real time: the WinCC interface of the power distribution control panel 61 displays the blower frequency, induced draft frequency, hydrogen valve opening, and various pressure parameters; if abnormal hydrogen pressure or excessive furnace pressure occurs, the PLC controller immediately triggers interlock protection (such as cutting off the hydrogen supply or stopping the burner), and sends an alarm signal through the local gas control box 63 and the remote terminal. Maintenance personnel can remotely view fault information and perform debugging or repair through the reserved Ethernet communication interface.

[0052] (iv) Shutdown phase The operator issues a shutdown command through the power distribution control panel 61. The PLC controller first reduces the hydrogen supply of the hydrogen-dedicated burner 11, and at the same time reduces the blower volume and the speed of the circulating fan 21, gradually reducing the combustion intensity.

[0053] After the hydrogen valve is closed, burner unit 1 stops combustion, while induced draft fan 41 and blower 31 continue to run to purge the furnace (duration ≥ 2 minutes) to remove residual flue gas and hydrogen. After purging is completed, induced draft fan 41, blower 31 and circulating fan 21 stop running in sequence.

[0054] The water supply pump 51 and deaerator pump 52 of the water supply unit 5 continue to run for a period of time until the furnace temperature of the hydrogen boiler 8 drops to a safe range and then stop. Finally, the PLC controller shuts off the main power supply of the system to complete the shutdown process.

[0055] Finally, it should be noted that the electronic components in the electrical control unit 6 and other components in this embodiment are all general standard parts or components known to those skilled in the art. Their structure and principle can be learned by those skilled in the art through technical manuals or conventional experimental methods. In the idle part of this device, all the above-mentioned electrical components are connected by wires. The specific connection method should refer to the working order between each electrical component in the above working principle to complete the electrical connection. All of these are technologies known in the art.

[0056] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A low-NOx burner, characterized in that: It includes a burner unit (1), a flue gas recirculation unit (2), an air supply unit (3), an induced draft unit (4), a water supply unit (5), and an electrical control unit (6). The burner unit (1) includes a hydrogen-specific burner (11), which has an air inlet (12) and a combustion port (13) at one end. The flue gas recirculation unit (2) includes a circulating fan (21), a circulating flue gas duct (22), and an automatic regulating valve (23). One end of the circulating flue gas duct (22) is connected to the tail flue of the hydrogen-fired boiler (8), and the other end is connected to the air inlet (12) of the burner unit (1). The automatic regulating valve (23) is installed on the circulating flue gas duct (22). A set of hydrogen regulating valve group (14) is installed at the gas inlet of the hydrogen-specific burner (11).

2. The low-NOx burner according to claim 1, characterized in that: The combustion disc of the hydrogen-specific burner (11) is made of a special alloy material that is resistant to high temperature and oxidation.

3. The low-NOx burner according to claim 1, characterized in that: The electrical control unit (6) includes a power distribution control panel (61), an electrical control system (62), a local gas control box (63), and a pressure transmitter (64).

4. The low-NOx burner according to claim 3, characterized in that: The power distribution control panel (61) integrates a PLC controller and a frequency converter. The PLC controller adopts the Siemens S71200 series. The electrical control system (62) includes an RTGW-20 type field explosion-proof instrument and a DⅡCT4 level local explosion-proof box. The pressure transmitter (64) has 4 units and is used to collect steam pressure, hydrogen pressure, air supply pressure and flue gas pressure signals respectively. The PLC controller is electrically connected to the motors and valves in the burner unit (1), flue gas recirculation unit (2), air supply unit (3), induced draft unit (4) and water supply unit (5) to realize automatic control.

5. The low-NOx burner according to claim 1, characterized in that: The air supply unit (3) includes a blower (31), and the air outlet of the blower (31) is connected to the air inlet (12) of the burner unit (1) through the air duct (32).

6. The low-NOx burner according to claim 1, characterized in that: The induced draft unit (4) includes an induced draft fan (41), the air inlet (42) of which is connected to the tail flue of the hydrogen-fired boiler (8).

7. The low-NOx burner according to claim 1, characterized in that: The water supply unit (5) includes a water supply pump (51), a deaerator pump (52) and an energy saver (53). There are two water supply pumps (51) and they operate in a one-on-one standby mode. There are two deaerator pumps (52). The energy saver (53) is connected in series with the water supply circuit of the hydrogen-fired boiler (8).

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