Boiler equipment and combustion mode for reducing oxides through staged air distribution low-ammonia combustion

Abstract

The invention relates to the technical field of boiler combustion, and discloses boiler equipment and a combustion mode for reducing oxides through staged air distribution low-ammonia combustion, the boiler equipment comprises a boiler combustion mechanism, a fuel supply mechanism is arranged outside the boiler combustion mechanism, and a gasification air supply mechanism is arranged at the bottom of the boiler combustion mechanism; a recycling and cleaning mechanism is arranged at the bottom of the boiler combustion mechanism. The combustion mode comprises the following steps that fuel feeding and material layer control are conducted; preparing gasified air and introducing hydrogen; carrying out fuel thermal cracking and gasification; grading gasification products and supplementing oxygen; mixing and burnout in a main combustion area; and waste heat recovery and on-line ash removal are carried out. Biomass fuel is subjected to thermal cracking gasification by adopting the in-furnace front micro-negative pressure gasification combustion chamber combined with the heat accumulator adiabatic combustion technology, rotary mixed combustion is formed by arranging a gasification chamber outlet oxygen supplementing air device at an outlet of the gasification chamber and arranging a secondary air device in a main combustion area, and it is ensured that gasification products and coke are fully burnt out.

Description

Technical Field

[0001] This invention relates to the field of boiler combustion technology, specifically to a boiler device and a combustion method for reducing oxides through staged air distribution and low-ammonia combustion. Background Technology

[0002] Energy is a crucial cornerstone of modern societal development. With increasing global focus on sustainable development and environmental protection, seeking clean and renewable energy alternatives to traditional fossil fuels has become an inevitable trend. Biomass energy, as a widely available and carbon-neutral renewable energy source, occupies a vital position in energy structure transformation due to its abundant sources and environmentally friendly characteristics. Boiler equipment is a key device for achieving efficient utilization of biomass energy, converting the chemical energy of biomass fuel into thermal energy, and is widely used in industrial production, district heating, and other fields.

[0003] In the practical application of biomass boilers, existing combustion technologies typically employ direct combustion. This includes chain grate boilers and circulating fluidized bed boilers. These boilers directly feed biomass fuel into the furnace for combustion, controlling the combustion process by adjusting the air supply and fuel feed rate. The heat carried by the flue gas is transferred through the furnace and convective heating surfaces to heat water, producing steam or hot water. Some boilers introduce a small amount of secondary air to improve in-furnace mixing and promote complete fuel combustion.

[0004] However, existing biomass boiler technologies suffer from poor fuel adaptability. Different biomass fuels exhibit significant differences in calorific value, ash content, and moisture content, making it difficult for a single boiler type to effectively address these issues. This results in low combustion efficiency. Existing combustion methods readily generate thermal nitrogen oxides (NOx) in the high-temperature zone, while nitrogen in the fuel is directly converted into fuel-type NOx. Current technologies struggle to coordinate and efficiently control both types of emissions. Furthermore, the low melting point of biomass ash easily leads to viscous deposits on heating surfaces, causing decreased heat transfer efficiency and increased corrosion and wear. Therefore, this invention provides a boiler device and a staged air distribution, low-ammonia combustion method to reduce oxide emissions, addressing the shortcomings of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a boiler device and a combustion method that reduces oxides through staged air distribution and low ammonia combustion, solving the problems of poor fuel adaptability, difficulty in controlling nitrogen oxide emissions, and severe ash and slagging in existing biomass boilers.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a boiler device, comprising a boiler combustion mechanism, a fuel supply mechanism externally disposed on the boiler combustion mechanism, a gasification air supply mechanism at the bottom of the boiler combustion mechanism, and a recycling and cleaning mechanism at the bottom of the boiler combustion mechanism; the boiler combustion mechanism includes: A micro-negative pressure gasification combustion chamber is used for the gasification and combustion of biomass; The central arch wall is located at the top of the outlet of the micro-negative pressure gasification combustion chamber to separate the combustion zone and guide the airflow; An oxygen supply air device is installed at the outlet of the gasification chamber to supplement the oxygen required for combustion. A secondary air device is installed at the top of the outlet of the micro-negative pressure gasification combustion chamber, and the gasification outlet of the central arch wall cooperates with the secondary air device to form a rotary combustion.

[0007] Preferably, the gasification air supply mechanism includes: A high-pressure, high-temperature gasification blower is provided, the outlet of which is connected to the bottom of the micro-negative pressure gasification combustion chamber. An oxygen generator is installed outside the high-pressure, high-temperature gasification blower to supply gasification air to the micro-negative pressure gasification combustion chamber. A flue gas recirculation pipe is provided, with its outlet end connected to the inlet end of the high-pressure, high-temperature gasification blower. An air conditioning regulating valve is installed on the outside of the flue gas recirculation pipe.

[0008] Preferably, the fuel supply mechanism includes: A dual-feed device is installed outside the micro-negative pressure gasification combustion chamber and is used to feed biomass fuel into the micro-negative pressure gasification combustion chamber. A feed lock is located at the bottom of the dual-feed device, and the feed lock can adjust the feed rate and the material layer height; A permanent cooling gate is located at the bottom of the feed lock to prevent fuel backfire.

[0009] Preferably, the recycling and cleaning mechanism includes: An energy-saving device, wherein the air inlet of the energy-saving device is located at the air outlet of the micro-negative pressure gasification combustion chamber; An ultrasonic dust blower is arranged in the convection tube bundle area of ​​the energy-saving device, and the ultrasonic dust blower is used to clean dust.

[0010] A combustion method for reducing oxides in boiler equipment with staged air distribution and low ammonia combustion is also provided, including the following steps: S1. Biomass fuel is metered and the feed rate is adjusted through a dual-feed device and a locking device, and then fed into the bottom of the micro-negative pressure gasification combustion chamber through a permanent cooling gate to form a fuel layer with controllable thickness. S2. Using a high-pressure high-temperature gasification blower, the high-temperature flue gas returned from the tail of the boiler through the flue gas recirculation pipe is mixed with the fresh air controlled by the air conditioning regulating valve. After adjusting the ratio, the hydrogen output from the hydrogen-oxygen generator is introduced to the outlet of the high-pressure high-temperature gasification blower and sent into the bottom of the micro-negative pressure gasification combustion chamber together with the mixed gasification air. S3. The fuel inside the micro-negative pressure gasification combustion chamber undergoes thermal cracking and gasification with the support of the heat storage body adiabatic combustion technology to produce combustible gas and coke. S4. The combustible gas after being vaporized in the micro-negative pressure gasification combustion chamber is led out from the outlet and the gasification outlet hole in the middle arch wall, and oxygen is supplemented at the outlet of the micro-negative pressure gasification combustion chamber through the gasification chamber outlet oxygen supplementation air device. S5. The airflow guided by the gasification outlet of the central arch wall cooperates with at least two sets of cross secondary air supplied by the secondary air device to form a rotating mixed combustion in the main combustion zone of the furnace, burning off the coke and the remaining combustible gas. S6. The high-temperature flue gas after combustion is subjected to waste heat recovery by an energy-saving device, and the heated surface is cleaned by the ultrasonic soot blower.

[0011] Preferably, in step S1, forming a fuel layer with controllable thickness includes the following steps: The feeding rate and material layer height are adjusted by the locking device, and the material layer thickness is controlled within 300mm-500mm; The Yongleng material gate uses water-cooled anti-backburning technology to prevent the flame from spreading upwards during fuel transportation.

[0012] Preferably, in step S2, the temperature range of the high-temperature flue gas is 150℃-200℃, and the hydrogen output from the hydrogen-oxygen generator participates in catalytic gasification combustion to control the conversion of fuel nitrogen to nitrogen oxides.

[0013] Preferably, in step S3, the front furnace of the micro-negative pressure gasification combustion chamber and the middle arch wall both adopt regenerable thermal insulation combustion technology. The thermal cracking gasification enables the combustion temperature to be stably controlled at 900℃, and the high-temperature flue gas has a short residence time in the insulation zone.

[0014] Preferably, in step S4, the combustible gas after being gasified in the micro-negative pressure gasification combustion chamber is drawn out from the outlet and the gasification outlet hole of the middle arch wall, and forms a rotating combustion with the flame in the main combustion zone of the furnace.

[0015] Preferably, in step S5, the formation of rotary mixing combustion in the main combustion zone of the furnace includes the following steps: The airflow guided by the gasification outlet of the central arch wall is used as the main combustible gas flow to enter the main combustion zone of the furnace. At least two sets of cross secondary air with specific directions and velocities are introduced through the central arch wall and the secondary air device. The cross secondary air interacts with the combustible gas flow to form a vortex in the main combustion zone of the furnace.

[0016] This invention provides a boiler device and a combustion method that reduces oxides through staged air distribution and low-ammonia combustion. It has the following beneficial effects: 1. This invention employs an in-furnace pre-positioned micro-negative pressure gasification combustion chamber combined with regenerator adiabatic combustion technology to thermally pyrolyze biomass fuel, enabling the combustion process to better adapt to different types and forms of biomass. By arranging a gasification chamber outlet oxygen supplementation air device at the gasification chamber outlet and setting a secondary air device in the main combustion zone to form a rotary mixing combustion, the complete combustion of gasification products and coke is ensured. Combined with efficient combustion, fuel consumption is reduced, thereby significantly lowering the overall operating cost of the boiler.

[0017] 2. This invention utilizes the synergistic effect of multiple low-NOx technologies, including sending high-temperature flue gas back to the gasification air system via a flue gas recirculation pipe to reduce oxygen concentration and combustion temperature; adding hydrogen from the hydrogen-oxygen generator at the outlet of the high-pressure high-temperature gasification air fan to participate in catalytic gasification combustion to effectively control the conversion of fuel nitrogen to nitrogen oxides; and optimizing the furnace temperature field through staged air distribution and rotary mixing combustion formed by the central arch wall and secondary air device, thereby reducing the generation of thermal and fuel-type nitrogen oxides and improving operational stability and flexibility.

[0018] 3. This invention utilizes a micro-negative pressure gasification combustion chamber design, enabling some ash to be processed during the gasification stage. Combined with a central arch wall and multi-stage secondary air to optimize the furnace temperature field, it avoids localized high temperatures that could lead to ash melting and slagging. The ultrasonic soot blower provides thorough cleaning of the convection tube bundle area, effectively solving the problems of fly ash adhesion, wear, and corrosion, thus extending the boiler's service life. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the device structure of the present invention; Figure 2 This is a flowchart of the method steps of the present invention; Figure 3 This is a schematic diagram of the low-NOx combustion synergistic control of the present invention.

[0020] The components include: 1. Micro-negative pressure gasification combustion chamber; 2. Central arch wall; 3. Gasification chamber outlet oxygen supply air device; 4. Ultrasonic soot blower; 5. Air conditioning regulating valve; 6. Flue gas recirculation pipe; 7. Secondary air device; 8. High-pressure high-temperature gasification blower; 9. Hydrogen-oxygen generator; 10. Permanently cold material gate; 11. Material locker; 12. Energy saver; and 13. Dual feeding device. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] See attached document Figure 1 , Figure 1 This is a schematic diagram of a boiler device according to an embodiment of the present invention. The present invention provides a boiler device, including a boiler combustion mechanism, a fuel supply mechanism, a gasification air supply mechanism, and a recovery and cleaning mechanism.

[0023] The boiler combustion mechanism includes a micro-negative pressure gasification combustion chamber 1, which is located at the front of the furnace and is used for the pyrolysis gasification of biomass and the combustion of combustible gases. A central arch wall 2 is located at the top of the outlet of the micro-negative pressure gasification combustion chamber 1, serving to separate the combustion zone and guide the airflow. At the outlet of the micro-negative pressure gasification combustion chamber 1, a gasification chamber outlet oxygen supply air device 3 is installed to supplement the required oxygen when the gasification products enter the main furnace. A secondary air device 7 is located at the top of the outlet of the micro-negative pressure gasification combustion chamber 1, and its air supply cooperates with the gasification outlet holes on the central arch wall 2 to form a rotary combustion mode.

[0024] The gasification air supply mechanism includes a high-pressure, high-temperature gasification fan 8, whose outlet is connected to the bottom of the micro-negative-pressure gasification combustion chamber 1 for supplying gasification air. A hydrogen-oxygen generator 9 is installed outside the high-pressure, high-temperature gasification fan 8 for introducing hydrogen into the gasification air. A flue gas recirculation pipe draws back the flue gas from the boiler tail, and its outlet is connected to the inlet of the high-pressure, high-temperature gasification fan 8. An air conditioning regulating valve 5 is installed outside the flue gas recirculation pipe for adjusting the mixing ratio of the returned flue gas and fresh air.

[0025] The fuel supply mechanism includes a dual-feed device 13, located outside the micro-negative pressure gasification combustion chamber 1, for conveying biomass fuel. A feed lock 11 is located at the bottom of the dual-feed device 13, capable of adjusting the fuel feed rate and fuel layer height. A permanent cooling feed gate 10 is located at the bottom of the feed lock 11 to prevent the fuel flame from propagating upwards.

[0026] The recycling and cleaning mechanism includes an energy-saving device, the air inlet of which is located at the air outlet of the micro-negative pressure gasification combustion chamber 1, for recovering waste heat from the flue gas. An ultrasonic soot blower 4 is arranged in the convection tube bundle area of ​​the energy-saving device for cleaning the soot on the heated surface.

[0027] For the boiler combustion mechanism, the micro-negative pressure gasification combustion chamber 1 is located at the front of the boiler and is the main reaction area after the biomass fuel enters. The interior of this combustion chamber is designed as a heat storage insulated structure to ensure the stability of the internal temperature field and a high-temperature environment to support the pyrolysis and gasification process of the biomass. This chamber maintains a micro-negative pressure state to limit flue gas leakage. The central arch wall 2 is located at the top of the outlet of the micro-negative pressure gasification combustion chamber 1, dividing the combustion area into a front gasification zone and a rear main combustion zone. The central arch wall 2 is constructed using heat storage materials to achieve double-sided radiative heat exchange and provide structural support. Multiple gasification outlet holes are provided on the central arch wall 2 to guide the gasification products into the main combustion zone. The gasification chamber outlet oxygen supply air device 3 is located at the outlet of the micro-negative pressure gasification combustion chamber 1, close to the discharge area of ​​the gasification products. The device consists of a series of nozzles used to supplement the oxygen required for secondary combustion of the gasification products about to enter the main furnace, thereby promoting the complete combustion of organic gases. The secondary air device 7 is located at different positions in the main combustion zone of the furnace, including the middle arch wall 2 and the rear arch area. The device includes multiple air supply nozzles, the design direction and angle of which are coordinated with the airflow guided by the gasification outlet holes of the middle arch wall 2, aiming to form a rotating mixed airflow in the main combustion zone of the furnace. The air supply system may include two or more sets of cross-flow secondary air, and by adjusting the air volume and velocity of each set of air supply, the airflow organization in the furnace and the mixing effect of fuel and air can be optimized.

[0028] For the gasification air supply mechanism, the high-pressure high-temperature gasification blower 8 is located at the bottom of the boiler, and its air outlet is connected to the bottom air chamber of the micro-negative pressure gasification combustion chamber 1 through an independent air duct. This blower provides the pressure and air volume to drive the gasification air through the fuel bed. The hydrogen-oxygen generator 9 is installed outside the high-pressure high-temperature gasification blower 8, and the hydrogen it produces is transported to the air outlet of the high-pressure high-temperature gasification blower 8 through a pipeline. The hydrogen is mixed with the gasification air here and then sent into the micro-negative pressure gasification combustion chamber 1. The hydrogen-oxygen generator 9 can produce and supply hydrogen in real time according to operational needs. The flue gas recirculation pipe is located at the tail end of the boiler and is used to draw out a portion of the low-temperature flue gas (temperature range typically 150℃ to 200℃) from the boiler flue gas outlet. The outlet end of the flue gas recirculation pipe is connected to the inlet end of the high-pressure high-temperature gasification blower 8 to realize the recycling of part of the flue gas. The air conditioning regulating valve 5 is installed near the connection between the flue gas recirculation pipe and the inlet end of the high-pressure high-temperature gasification blower 8 to precisely control the mixing ratio of the returned flue gas and fresh air, thereby adjusting the oxygen content of the mixed gasification air entering the gasification chamber.

[0029] For the fuel supply mechanism, the dual-feed device 13 is located on the top of the micro-negative pressure gasification combustion chamber 1, specifically as a double-screw feeder or a double-push rod feeder, etc., for continuously feeding biomass fuel into the furnace. This device can adjust the fuel feed rate. The locking device 11 is located at the bottom of the dual-feed device 13, in the channel before the fuel enters the furnace. The locking device 11 can be a star valve or a double-flap valve, etc., allowing adjustment of the fuel feed rate into the micro-negative pressure gasification combustion chamber 1 and the height of the formed material layer. The permanent cooling gate 10 is located at the bottom of the locking device 11, adjacent to the furnace inlet. This gate adopts an internal water-cooling structure, using cooling circulating water to remove heat, thereby physically isolating the high-temperature furnace from the fuel delivery system, effectively preventing the flame from propagating upwards along the fuel channel, and ensuring the safety of the fuel supply.

[0030] For the recycling and cleaning mechanism, the economizer is located at the boiler's flue gas outlet, downstream of the convection tube bundle area. Its inlet is connected to the outlet of the micro-negative pressure gasification combustion chamber 1 via a flue. This economizer is used to recover the waste heat from the high-temperature flue gas after combustion, typically for preheating boiler feedwater or combustion air. The ultrasonic soot blower 4 is arranged in the convection tube bundle area of ​​the economizer. This device generates high-frequency ultrasonic waves to cause the accumulated ash particles on the heated surface to vibrate, fatigue, and fall off, thereby achieving online soot removal of the heated surface, maintaining heat exchange efficiency, and effectively removing dust from the back of the tube bundle that is difficult to reach using traditional methods.

[0031] See attached document Figure 2 and attached Figure 3 The present invention also provides a boiler device and a combustion method for reducing oxides by staged air distribution and low ammonia combustion, comprising the following steps: S1. Biomass fuel is metered and the feed rate is adjusted through a dual-feed device 13 and a feed lock 11, and then fed into the bottom of the micro-negative pressure gasification combustion chamber 1 through a permanent cooling feed gate 10 to form a fuel layer with controllable thickness. S2. Using the high-pressure high-temperature gasification blower 8, the high-temperature flue gas returned from the tail of the boiler through the flue gas recirculation pipe is mixed with the fresh air controlled by the air conditioning regulating valve 5. After adjusting the ratio, the hydrogen output from the hydrogen-oxygen generator 9 is introduced to the outlet of the high-pressure high-temperature gasification blower 8 and sent into the bottom of the micro-negative pressure gasification combustion chamber 1 together with the mixed gasification air. S3, the fuel inside the micro-negative pressure gasification combustion chamber 1 undergoes thermal cracking and gasification with the support of the heat storage body adiabatic combustion technology to produce combustible gas and coke; S4. The combustible gas after being vaporized in the micro-negative pressure gasification combustion chamber 1 is led out from the outlet and the gasification outlet hole of the central arch wall 2, and oxygen is supplemented at the outlet of the micro-negative pressure gasification combustion chamber 1 through the gasification chamber outlet oxygen supplementation air device 3. S5. The airflow guided by the gasification outlet of the central arch wall 2 cooperates with at least two sets of cross secondary air supplied by the secondary air device 7 to form a rotating mixed combustion in the main combustion zone of the furnace, burning off the coke and the remaining combustible gas. S6. The high-temperature flue gas after combustion is recovered by the energy-saving device, and the heated surface is cleaned by the ultrasonic soot blower 4.

[0032] In step S1, biomass fuel first enters through a dual-feed device 13, which performs preliminary metering and delivery of the fuel. Subsequently, the fuel enters a feeder 11 located below the dual-feed device 13. The feeder 11, through its internal structure, can precisely adjust the fuel feed rate into the micro-negative pressure gasification combustion chamber 1. By adjusting the feed rate, the thickness of the fuel layer at the bottom of the micro-negative pressure gasification combustion chamber 1 can be dynamically controlled. By precisely controlling the fuel layer thickness within the range of 300mm-500mm, this thickness range aims to ensure that the gasification air can uniformly penetrate the fuel layer, promoting complete fuel gasification, while avoiding air short-circuiting due to an excessively thin fuel layer or incomplete gasification due to an excessively thick fuel layer.

[0033] Before entering the micro-negative pressure gasification combustion chamber 1, the fuel must pass through the permanently cooled fuel gate 10 located at the bottom of the fuel lock 11. The permanently cooled fuel gate 10 employs water-cooled anti-backburning technology, with an internal cooling water circulation channel. The cooling water removes heat, keeping the gate itself and the area in contact with the fuel at a low temperature. This technology aims to provide a physical barrier, effectively preventing the flame and heat from the high-temperature furnace from flowing back upwards along the fuel delivery channel, thereby completely eliminating the safety hazard of fuel backburning into the hopper and ensuring the safe operation of the boiler.

[0034] In step S2, the preparation of the gasification air first involves mixing a portion of the high-temperature flue gas from the boiler tail with fresh air. The high-temperature flue gas, with a temperature range of 150℃-200℃, is returned through a flue gas recirculation pipe. The fresh air is introduced through an air conditioning regulating valve 5. This valve 5 can precisely control the amount of fresh air introduced according to the boiler's operating status and gasification requirements to adjust the oxygen content of the mixed gas. This mixed gas is then drawn in through the inlet of the high-pressure, high-temperature gasification fan 8. This step utilizes the waste heat of the boiler tail flue gas, reducing the additional energy requirement for preheating the gasification air. Simultaneously, the returned flue gas reduces the oxygen concentration in the gasification air, thereby suppressing the formation of thermal nitrogen oxides during the gasification process.

[0035] Subsequently, the hydrogen produced by the hydrogen-oxygen generator 9 is introduced to the outlet of the high-pressure, high-temperature gasification blower 8. The hydrogen, along with the mixed gasification air, enters the bottom of the micro-negative-pressure gasification combustion chamber 1. In this invention, the hydrogen acts as a catalyst in the gasification combustion. As a highly reactive substance, hydrogen can promote the thermal decomposition of biomass and accelerate the gasification reaction process. Hydrogen can participate in the decomposition reaction of hydrocarbons, and in the reaction, it plays a role in promoting the conversion of complex organic matter into small-molecule combustible gases.

[0036] Furthermore, hydrogen can reduce nitrogen-containing compounds in fuel into nitrogen gas, rather than nitrogen oxides, through a reduction process. This reduces the formation of nitrogen oxides at the chemical reaction mechanism level, achieving low-NOx combustion. The hydrogen is produced and used immediately, and can be output on demand, thus ensuring the flexibility of system operation.

[0037] In step S3, inside the micro-negative pressure gasification combustion chamber 1, the biomass fuel layer formed by the fuel supply mechanism undergoes pyrolysis and gasification under the action of the introduced gasification air. Both the front furnace of the micro-negative pressure gasification combustion chamber 1 and the central arch wall 2 employ regenerator-based adiabatic combustion technology. This technology utilizes the low thermal conductivity and high heat storage capacity of the regenerator material (high-temperature resistant ceramic) to effectively reduce heat loss to the furnace wall, maintain a high-temperature environment inside the furnace, and ensure a uniform and stable temperature field in the combustion zone.

[0038] With the support of this regenerator adiabatic combustion technology, the combustion temperature inside the micro-negative pressure gasification combustion chamber 1 is stably controlled at 900℃. Under this temperature condition, biomass fuel undergoes a rapid pyrolysis reaction, producing... The gasification products are mainly small-molecule combustible gases and solid coke. Temperature control at 900℃ is crucial for nitrogen oxide formation: it ensures effective biomass gasification while effectively inhibiting the formation of thermal nitrogen oxides, which typically form in large quantities at higher temperatures (e.g., above 1200℃). The formation reactions of thermal nitrogen oxides include: ; ; In the formula, For nitrogen molecules, O is an oxygen atom; for nitric oxide molecules, N is a nitrogen atom. This indicates a reversible reaction.

[0039] When the combustion temperature is controlled at 900℃, the concentrations of oxygen and nitrogen atoms decrease, thereby inhibiting the aforementioned reactions. Simultaneously, this invention optimizes the structure and airflow organization of the gasification combustion chamber, resulting in a shorter residence time of the high-temperature flue gas in the adiabatic zone. This shorter residence time further limits the opportunity for the high-temperature flue gas to react with nitrogen in the air to generate nitrogen oxides, thus achieving low nitrogen oxide emissions.

[0040] In step S4, the combustible gas generated in the micro-negative pressure gasification combustion chamber 1, after completing pyrolysis and gasification, will be drawn out through two main paths: a portion of the combustible gas will be drawn out directly from the outlet of the micro-negative pressure gasification combustion chamber 1, while the other portion will be drawn out through multiple gasification outlet holes provided on the central arch wall 2. This staged extraction method aims to perform preliminary separation and pretreatment of the gasification products when they enter the main furnace, providing a basis for subsequent staged combustion.

[0041] At the outlet of the micro-negative pressure gasification combustion chamber 1, oxygen is supplied to the extracted combustible gas through the gasification chamber outlet oxygen supply air device 3. The precise supply of this oxygen supply air is designed to ensure that this portion of the combustible gas can undergo initial combustion, thereby preheating the gas entering the main furnace and reducing the generation of incomplete combustion products.

[0042] At the same time, the combustible gas flow guided by the gasification outlet of the central arch wall 2 interacts with the existing flame (initial combustion from the gasification chamber outlet) in the main combustion zone of the furnace when it enters the main combustion zone of the furnace, forming a preliminary rotating combustion.

[0043] In step S5, the combustible gas flow guided by the gasification outlet of the central arch wall 2 enters the main combustion zone of the furnace as the primary fuel gas flow. In this main combustion zone, the central arch wall 2 and the secondary air device 7 collaboratively deliver at least two sets of cross-flow secondary air with specific directions and velocities. The injection positions, angles, and momentum of these cross-flow secondary air are optimized to interact with the incoming combustible gas flow.

[0044] The interaction between the cross-flow secondary air and the combustible gas flow creates a strong vortex in the main combustion zone of the furnace. This vortex motion increases the turbulence intensity of the airflow, enabling rapid and uniform mixing of combustible gas, coke particles, and sufficient oxygen. This intense mixing ensures full contact between fuel and oxygen, promoting complete combustion of coke and remaining combustible gas in a short time, effectively reducing the carbon content in the ash and achieving fuel conversion. This enhanced mixing and combustion process helps improve the overall combustion efficiency of the boiler.

[0045] In step S6, after leaving the main combustion zone of the furnace, the high-temperature flue gas enters the economizer at the boiler flue gas outlet. The economizer contains heat exchange tube bundles. As the high-temperature flue gas flows through the tube bundles, the heat it carries is transferred to the medium flowing inside the tube bundles (such as boiler feedwater or combustion air) through convection and radiation, thereby recovering the waste heat from the flue gas. This waste heat recovery process aims to improve the overall thermal efficiency of the boiler and reduce energy consumption.

[0046] An ultrasonic soot blower 4 is arranged in the convection tube bundle region of the energy-saving device. The ultrasonic soot blower 4 generates ultrasonic waves of specific frequency and energy, causing the ash particles attached to the surface of the heat exchange tube bundle to vibrate at high frequency. This vibration reduces the adhesion between the ash layer and the tube bundle surface, and causes the ash particles to collide with each other, resulting in the ash peeling off from the tube bundle surface. The acoustic characteristics of ultrasonic waves enable effective cleaning of the back side of the tube bundle and dead-angle areas through reflection and refraction.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A boiler device, comprising a boiler combustion mechanism, characterized in that, The boiler combustion mechanism is externally equipped with a fuel supply mechanism, and is equipped with a gasification air supply mechanism at its bottom. It also includes a recovery and cleaning mechanism at its bottom. The boiler combustion mechanism comprises: A micro-negative pressure gasification combustion chamber (1) is used for the gasification and combustion of biomass; The central arch wall (2) is located at the top of the outlet of the micro-negative pressure gasification combustion chamber (1) to separate the combustion zone and guide the airflow; The oxygen supply air device (3) at the outlet of the gasification chamber is installed at the outlet of the micro-negative pressure gasification combustion chamber (1) to supplement the oxygen required for combustion. A secondary air device (7) is installed at the top of the outlet of the micro-negative pressure gasification combustion chamber (1), and the gasification outlet of the central arch wall (2) cooperates with the secondary air device (7) to form a rotary combustion.

2. The boiler equipment according to claim 1, characterized in that, The gasification air supply mechanism includes: High-pressure high-temperature gasification blower (8), the air outlet of the high-pressure high-temperature gasification blower (8) is connected to the bottom of the micro negative pressure gasification combustion chamber (1), and a hydrogen-oxygen generator (9) is installed on the outside of the high-pressure high-temperature gasification blower (8) to supply gasification air to the micro negative pressure gasification combustion chamber (1). The flue gas recirculation pipe (6) has its outlet end connected to the inlet end of the high-pressure high-temperature gasification blower (8), and an air conditioning regulating valve (5) is installed on the outside of the flue gas recirculation pipe (6).

3. The boiler equipment according to claim 1, characterized in that, The fuel supply mechanism includes: A dual-feed device (13) is provided outside the micro-negative pressure gasification combustion chamber (1) for feeding biomass fuel into the micro-negative pressure gasification combustion chamber (1); A feed lock (11) is provided at the bottom of the dual feed device (13), and the feed lock (11) can adjust the feed rate and the material layer height; A permanent cooling gate (10) is provided at the bottom of the feed lock (11) to prevent fuel backfire.

4. The boiler equipment according to claim 1, characterized in that, The recycling and cleaning organization includes: An energy saver (12) is provided at the air outlet of the micro negative pressure gasification combustion chamber (1). An ultrasonic dust blower (4) is arranged in the convection tube bundle area of ​​the energy saver (12) and is used to clean dust.

5. A combustion method for reducing oxides in a boiler by staged air distribution and low-ammonia combustion, applied to the boiler equipment described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Biomass fuel is metered and the feed rate is adjusted by a dual-feed device (13) and a locking device (11), and then fed into the bottom of the micro-negative pressure gasification combustion chamber (1) through a permanent cooling gate (10) to form a fuel layer with controllable thickness. S2. Using a high-pressure high-temperature gasification blower (8), the high-temperature flue gas returned from the tail of the boiler through the flue gas recirculation pipe (6) is mixed with the fresh air controlled by the air conditioning regulating valve (5). After adjusting the ratio, the hydrogen output from the hydrogen-oxygen generator (9) is introduced to the outlet of the high-pressure high-temperature gasification blower (8) and sent into the bottom of the micro-negative pressure gasification combustion chamber (1) together with the mixed gasification air. S3, the fuel inside the micro-negative pressure gasification combustion chamber (1) undergoes thermal cracking and gasification with the support of the heat storage body adiabatic combustion technology to produce combustible gas and coke; S4. The combustible gas after being vaporized in the micro-negative pressure gasification combustion chamber (1) is led out from the outlet and the gasification outlet hole of the central arch wall (2), and oxygen is supplemented at the outlet of the micro-negative pressure gasification combustion chamber (1) through the gasification chamber outlet oxygen supplementation air device (3). S5. The airflow guided by the gasification outlet of the central arch wall (2) cooperates with at least two sets of cross secondary air supplied by the secondary air device (7) to form a rotating mixed combustion in the main combustion zone of the furnace, burning off the coke and the remaining combustible gas. S6. The high-temperature flue gas after combustion is recycled by the energy-saving device (12) and the heated surface is cleaned by the ultrasonic soot blower (4).

6. The combustion method for reducing oxides in a boiler with staged air distribution and low ammonia combustion according to claim 5, characterized in that, In step S1, forming a fuel layer with controllable thickness includes the following steps: The feed rate and material layer height are adjusted by the locking device (11), and the material layer thickness is controlled within 300mm-500mm; The Yongleng material gate (10) uses water-cooled anti-backburning technology to block the flame from spreading upwards during fuel transportation.

7. The combustion method for reducing oxides in a boiler with staged air distribution and low ammonia combustion according to claim 5, characterized in that, In step S2, the temperature range of the high-temperature flue gas is 150℃-200℃, and the hydrogen output from the hydrogen-oxygen generator (9) participates in catalytic gasification combustion to control the conversion of fuel nitrogen to nitrogen oxides.

8. The combustion method for reducing oxides in a boiler with staged air distribution and low ammonia combustion according to claim 5, characterized in that, In step S3, the front furnace of the micro-negative pressure gasification combustion chamber (1) and the middle arch wall (2) both adopt the heat storage body adiabatic combustion technology. The thermal cracking gasification makes the combustion temperature stably controlled at 900℃, and the high temperature flue gas has a short residence time in the adiabatic zone.

9. The combustion method for reducing oxides in a boiler with staged air distribution and low ammonia combustion according to claim 5, characterized in that, In step S4, the combustible gas after being gasified in the micro-negative pressure gasification combustion chamber (1) is drawn out from the outlet and the gasification outlet hole of the middle arch wall (2) and forms a rotating combustion with the flame in the main combustion zone of the furnace.

10. The combustion method for reducing oxides in a boiler with staged air distribution and low ammonia combustion according to claim 5, characterized in that, In step S5, the formation of rotary mixed combustion in the main combustion zone of the furnace includes the following steps: The gas flow guided by the gasification outlet of the central arch wall (2) is used as the main combustible gas flow to enter the main combustion zone of the furnace. At least two sets of cross secondary air with specific directions and speeds are introduced through the central arch wall (2) and the secondary air device (7). The cross secondary air interacts with the combustible gas flow to form a vortex in the main combustion zone of the furnace.

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