An oxygen-enriched low-load low-nitrogen combustion system and method

Abstract

The application discloses an oxygen-rich low-load low-nitrogen combustion system and method, and relates to the technical fields of coal gasification and oxygen-rich combustion. The system comprises a precombustion chamber, a main burner and a combustion furnace. The main burner is sequentially provided with a center stable flame combustion nozzle, a swirl combustion nozzle and an oscillating jet combustion nozzle from inside to outside. The center stable flame combustion nozzle adopts a stable flame cavity structure, and realizes partial premixing of fuel and oxidant through a stable flame air inlet groove. The swirl combustion nozzle is provided with swirl vanes, and the swirl degree thereof is adjusted through a rotating plate and an adjusting screw sleeve. The oscillating jet combustion nozzle is symmetrically arranged in two. The combustion method comprises three modes of full load, intermediate load and low load. The three-stage nozzles are opened in stages to realize stable combustion in a full load range of 15% to 100%. The swirl degree is increased at the intermediate load, and the swirl degree is reduced at the high load. The application can realize wide-load stable combustion and low-nitrogen emission, and is suitable for the field of oxygen-rich combustion of pulverized coal.

Description

Technical Field

[0001] This invention relates to the field of clean coal combustion and flue gas resource utilization technology, specifically to an oxygen-enriched, low-load, low-NOx combustion system and method. Background Technology

[0002] Coal gasification and oxygen-enriched combustion technologies are important directions for the clean and efficient utilization of coal resources. In the combustion of pulverized coal, combustion stability under low-load conditions is a key technical challenge that has troubled those skilled in the art. When the boiler or combustion system load decreases, the furnace temperature drops and the fuel concentration decreases, which can easily lead to unstable combustion or even flameout.

[0003] Existing technologies and their adopted burner structures do not address the wide-load adjustment issues in pulverized coal combustion. Furthermore, existing pulverized coal burners typically require oil injection for combustion assistance under low-load conditions, resulting in poor economic efficiency. Swirl combustion technology generates a rotating airflow through swirl blades, creating a recirculation zone that entrains high-temperature flue gas, which can improve combustion stability to some extent. However, simple swirl combustion still struggles to maintain stable combustion under ultra-low load conditions (such as 15% load). While oscillating jet combustion technology can improve the uniformity of gas distribution, its adaptability under variable load conditions is limited. Summary of the Invention

[0004] The purpose of this invention is to provide an oxygen-enriched, low-load, low-NOx combustion system and method, which solves the technical problems of poor combustion stability, insufficient wide-load adjustment capability, and high NOx emissions in existing pulverized coal combustion systems under low-load conditions.

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

[0006] An oxygen-enriched, low-load, low-NOx combustion system includes a pre-combustion chamber and a main burner; the outlet of the pre-combustion chamber is connected to the inlet of the main burner; the main burner is provided with a central flame-stabilizing nozzle, a swirl nozzle, and an oscillating jet nozzle arranged sequentially from the inside to the outside; the central flame-stabilizing nozzle is coaxially positioned at the center of the swirl nozzle, the swirl nozzle is arranged around the periphery of the central flame-stabilizing nozzle, and the oscillating jet nozzle is arranged around the periphery of the swirl nozzle; it also includes a combustion furnace, the main burner is fixedly mounted on the furnace chamber of the combustion furnace, the central flame-stabilizing nozzle, the swirl nozzle, and the oscillating jet nozzle are located on the furnace chamber wall of the combustion furnace, the pyrolysis gas outlet of the pre-combustion chamber is connected to the central flame-stabilizing nozzle, the swirl nozzle, and the oscillating jet nozzle respectively; it also includes an air separation nitrogen generator, the by-product oxygen outlet of the air separation nitrogen generator is connected to the annular oxidant channel of the central flame-stabilizing nozzle, and air is also introduced into the annular oxidant channel.

[0007] Furthermore, the central flame stabilizing combustion nozzle includes a central fuel channel, an annular oxidizer channel, and a flame stabilizing chamber. The central fuel channel is axially positioned at the center of the central flame stabilizing combustion nozzle. The annular oxidizer channel is arranged around the periphery of the central fuel channel. The flame stabilizing chamber is located at the downstream end of the central fuel channel. An stabilizing air inlet communicating with the interior of the central fuel channel is located upstream of the flame stabilizing chamber. Stabilizing air inlet grooves communicating with the interior of the annular oxidizer channel are also uniformly arranged upstream of the flame stabilizing chamber. These grooves are evenly distributed outside the stabilizing air inlet. A stabilizing air outlet communicating with the interior of the combustion furnace is located downstream of the flame stabilizing chamber. A stabilizing air outlet groove communicating with the interior of the combustion furnace is also located downstream of the flame stabilizing chamber. These grooves are evenly distributed outside the stabilizing air outlet. An oxidizer outlet communicating with the interior of the combustion furnace is located downstream of the annular oxidizer channel.

[0008] Furthermore, the number of flame-stabilizing air inlet slots is three, and the three flame-stabilizing air inlet slots are evenly distributed around the annular oxidant channel; the number of flame-stabilizing air outlet slots is three, and the three flame-stabilizing air outlet slots are evenly distributed around the flame-stabilizing cavity; the flame-stabilizing air inlet slots and the flame-stabilizing air outlet slots are staggered around the flame-stabilizing cavity.

[0009] Furthermore, the swirling combustion nozzle includes a swirling channel and swirling blades; the swirling channel is arranged around the periphery of the central flame-stabilizing combustion nozzle, and the swirling blades are disposed inside the swirling channel near the outlet. The end of the swirling blades is fixedly connected to the inner wall of the swirling channel, and the middle and front ends of the swirling blades are slidably connected to the inner wall of the swirling channel. A sliding block is fixedly connected to the outer side of the front end of the swirling blades. A sliding groove is provided on the outer wall of the swirling channel for the sliding block to slide circumferentially along the outer wall of the swirling channel. A rotating... The rotating sleeve has an axial groove on its inner side that corresponds to the sliding groove. The outer end of the sliding block is slidably disposed in the axial groove. The sliding block can slide axially along the vortex channel within the axial groove. The width of both the sliding groove and the axial groove is greater than the width of the sliding block. When the rotating sleeve rotates on the outer wall of the vortex channel, the rotating sleeve can drive the sliding block to move circumferentially along the outer wall of the vortex channel. Since the inner end of the sliding block is fixedly connected to the front end of the vortex blade, and the vortex blade adopts a spring-loaded structure, the vortex blade can drive the sliding block to move axially along the vortex channel, thereby changing the vortex intensity of the vortex blade.

[0010] Furthermore, the number of the oscillating jet combustion nozzles is two, and the two oscillating jet combustion nozzles are symmetrically arranged around the periphery of the swirling combustion nozzle.

[0011] Furthermore, it also includes a control system configured such that the load of the central flame-stabilizing combustion nozzle is 15% of the total load; the load of the swirling combustion nozzle is 50% of the total load; the load of the oscillating jet combustion nozzle is 35% of the total load; in the intermediate load mode, the swirl intensity of the swirling blades is increased; in the full load mode, the swirl intensity of the swirling blades is decreased; and in the low load mode, the minimum load is 15% of the total load.

[0012] Furthermore, the number of the oscillating jet combustion nozzles is two, and the load of each of the two oscillating jet combustion nozzles is 17.5% of the total load.

[0013] Furthermore, fuel is introduced into the fuel inlet of the pre-combustion chamber, and the oxidant inlet of the pre-combustion chamber is connected to the by-product oxygen outlet of the air separation nitrogen generator and is also vented with air.

[0014] Furthermore, the oscillating jet combustion nozzle is provided with an inlet section, a contraction section, an oscillating section, and an outlet section from front to back. The oscillating section includes an upper oscillating inclined plate hinged above the outlet of the contraction section and inclined upwards, and a lower oscillating inclined plate hinged below the outlet of the contraction section and inclined downwards. The inlet section and the contraction section are located in the inner tube, and the oscillating section and the outlet section are located in the outer tube. The outer side of the inner tube and the inner side of the outer tube are connected by a threaded connection. A disturbance element is provided inside the outlet section. The upper and lower oscillating inclined plates are hinged to the contraction section. The joints are respectively equipped with return springs to open the upper and lower oscillating inclined plates. The inner wall of the outer tube is equipped with retaining rings corresponding to the positions of the upper and lower oscillating inclined plates. When the inner and outer tubes rotate relative to each other, they will move axially relative to each other under the threaded engagement, thereby adjusting the distance between the disturbance component and the outlet of the contraction section. When the upper and lower oscillating inclined plates follow the movement of the inner tube and touch the retaining rings, the tilt angle of the upper and lower oscillating inclined plates can change, thereby adjusting the tilt angle of the upper and lower oscillating inclined plates in the oscillation section.

[0015] An oxygen-enriched, low-load, low-NOx combustion method, employing the aforementioned oxygen-enriched, low-load, low-NOx combustion system, includes the following steps: after the fuel and oxidant partially combust and heat up in the pre-combustion chamber, the pyrolysis gas discharged from the pre-combustion chamber is jointly fed into the combustion furnace for combustion; in full-load mode, the central flame-stabilizing combustion nozzle, the swirl combustion nozzle, and the oscillating jet combustion nozzle are turned on; in intermediate-load mode, the central flame-stabilizing combustion nozzle and the swirl combustion nozzle are turned on, and the oscillating jet combustion nozzle is turned off; in low-load mode, the central flame-stabilizing combustion nozzle is turned on, and the swirl combustion nozzle and the oscillating jet combustion nozzle are turned off; in the intermediate-load mode, the swirl intensity of the swirl blades is increased; in the full-load mode, the swirl intensity of the swirl blades is decreased.

[0016] The beneficial effects of this invention are as follows: By configuring 15% core load as flame-stabilizing chamber combustion, 50% load as swirl combustion, and 35% load as oscillating jet combustion, stable combustion is achieved across the entire range from 15% ultra-low load to 100% full load; under ultra-low load conditions, a stable flame can be maintained solely by the central flame-stabilizing combustion nozzle, eliminating the need for fuel injection; the central flame-stabilizing combustion nozzle employs a flame-stabilizing chamber structure, achieving partial premixing of fuel and oxidizer, significantly improving flame root stability; and through the staged layout of the burner, different stages can be flexibly opened or closed according to load requirements. Other burners achieve precise control of combustion intensity; the swirl blades of the swirl combustion nozzle adopt a spring-loaded structure and are adjusted with a rotating sleeve, which can change the blade angle by active rotation and adapt to axial movement under the action of airflow, making the swirl intensity adjustment more flexible and the structure more compact; by-product oxygen from the air separation nitrogen production unit is mixed with air as an oxidant to achieve oxygen-enriched combustion, further improving combustion efficiency and stability, and suppressing NOx generation; the high-temperature pyrolysis gas generated in the pre-combustion chamber is directly distributed to nozzles at each stage, making the combustion organization more reasonable, which is conducive to stable combustion and low nitrogen emissions under wide loads. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0018] Figure 1 This is a schematic diagram of the system of the present invention;

[0019] Figure 2 This is a cross-sectional view of the main burner of the present invention;

[0020] Figure 3This is a schematic diagram of the end face structure of the main burner of the present invention;

[0021] Figure 4 This is a partial cross-sectional view of the central flame-stabilizing combustion nozzle of the present invention;

[0022] Figure 5 This is a schematic diagram of the exploded structure of the central flame-stabilizing combustion nozzle of the present invention;

[0023] Figure 6 This is a schematic diagram of the structure of the oscillating jet combustion nozzle of the present invention;

[0024] Figure 7 For the present invention Figure 2 A magnified structural diagram of part A;

[0025] Figure 8 This is a schematic diagram of the swirl blade adjustment section of the swirl combustion nozzle of the present invention;

[0026] Figure 9 This is a schematic diagram of the air intake of each nozzle of the main burner of the present invention;

[0027] In the diagram: 1-Pre-combustion chamber; 2-Main burner; 3-Combustion furnace; 4-Air separation nitrogen generator; 21-Central flame stabilizing combustion nozzle; 22-Swirl combustion nozzle; 23-Oscillating jet combustion nozzle; 211-Central fuel passage; 212-Annular oxidizer passage; 213-Flame stabilizing chamber; 214-Flame stabilizing air inlet; 215-Flame stabilizing air inlet groove; 216-Flame stabilizing air outlet; 217-Flame stabilizing air outlet groove; 218- Oxidizing agent outlet; 221-Swirl channel; 222-Swirl blade; 223-Sliding block; 224-Sliding groove; 225-Rotating sleeve; 226-Axial groove; 231-Inlet section; 232-Contraction section; 233-Oscillating section; 234-Outlet section; 235-Upper oscillating inclined plate; 236-Lower oscillating inclined plate; 237-Inner pipe; 238-Outer pipe; 239-Baffle ring; 2310-Disturbance component. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of 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, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] The present invention will be further described below with reference to embodiments.

[0030] like Figure 1 , Figure 2 and Figure 9As shown, this embodiment provides an oxygen-enriched, low-load, low-NOx combustion system.

[0031] This oxygen-enriched, low-load, low-NOx combustion system includes a pre-combustion chamber 1, a main burner 2, and an air separation nitrogen generator 4. Fuel, such as pulverized coal, is introduced into the fuel inlet of the pre-combustion chamber 1; an oxidant (with byproduct oxygen and air) is introduced into the oxidant inlet. Partial combustion and pyrolysis occur within the pre-combustion chamber 1, producing high-temperature pyrolysis gas. The pyrolysis gas outlet of the pre-combustion chamber 1 is connected via pipelines to the inlets of a central flame-stabilizing nozzle 21, a swirling combustion nozzle 22, and an oscillating jet combustion nozzle 23, respectively, thus directly supplying the high-temperature pyrolysis gas to each stage of the nozzles for combustion. The byproduct oxygen outlet of the air separation nitrogen generator 4 is connected to the annular oxidant channel 212 of the central flame-stabilizing nozzle 21. Air is also introduced into the annular oxidant channel 212, where it mixes with the byproduct oxygen to form an oxygen-enriched oxidant, supplying some of the oxidant required for flame-stabilized combustion. The pre-combustion chamber 1 helps improve combustion stability, reduce NOx emissions, and increase the pulverized coal burnout rate.

[0032] The main burner 2 is equipped with, from the inside out, a central flame-stabilizing nozzle 21, a swirling nozzle 22, and an oscillating jet nozzle 23. The central flame-stabilizing nozzle 21 is coaxially positioned at the center of the swirling nozzle 22, which is arranged in a ring around the periphery of the central flame-stabilizing nozzle 21. The oscillating jet nozzle 23 is located around the periphery of the swirling nozzle 22. The main burner 2 is fixedly mounted on the furnace chamber of the combustion furnace 3, and the central flame-stabilizing nozzle 21, swirling nozzle 22, and oscillating jet nozzle 23 are located on the furnace chamber wall of the combustion furnace 3. Viewed from the burner outlet end face, the center is the outlet of the flame-stabilizing chamber, the middle ring is the outlet of the swirling nozzle 22, and the outermost ring is the outlet of the oscillating jet nozzle 23.

[0033] The pre-combustion chamber 1 and the combustion furnace 3 adopt an oxygen-enriched combustion mode, with the oxidant being a mixture of oxygen and air, forming a two-stage oxygen-enriched combustion mode.

[0034] The combustion system also includes a control system (not shown in the figure). The control system is configured such that the load on the central flame stabilizer nozzle 21 is 15% of the total load, the load on the swirl nozzle 22 is 50% of the total load, and the load on the oscillating jet nozzle 23 is 35% of the total load. There are two oscillating jet nozzles 23, symmetrically arranged around the periphery of the swirl nozzle 22, with each oscillating jet nozzle 23 carrying a load of 17.5% of the total load. The minimum load in the low-load mode is 15% of the total load.

[0035] like Figures 2 to 5 As shown, the specific structure of the center flame stabilizing combustion nozzle 21 is described in detail.

[0036] The central flame stabilizer nozzle 21 includes a central fuel channel 211, an annular oxidizer channel 212, and a flame stabilizing chamber 213. The central fuel channel 211 is axially positioned at the center of the central flame stabilizer nozzle 21 and is used to introduce high-temperature pyrolysis gas (containing unburned fuel components) from the pre-combustion chamber 1. The annular oxidizer channel 212 is arranged around the periphery of the central fuel channel 211 and is used to introduce an oxygen-enriched oxidizer formed by mixing oxygen produced as a byproduct of the air separation nitrogen generator 4 with air. The flame stabilizing chamber 213 is located at the downstream end of the central fuel channel 211.

[0037] The flame stabilizing chamber 213 has a flame stabilizing inlet 214 upstream, communicating with the interior of the central fuel channel 211. Pyrolysis gas enters the flame stabilizing chamber 213 through the flame stabilizing inlet 214. The flame stabilizing inlet grooves 215, communicating with the interior of the annular oxidant channel 212, are also uniformly distributed upstream of the flame stabilizing inlet 214. A portion of the oxidant enters the flame stabilizing chamber 213 through the flame stabilizing inlet grooves 215, where it partially premixes with the pyrolysis gas from the central fuel channel 211 within the flame stabilizing chamber 213.

[0038] Downstream of the flame stabilizing chamber 213 is a flame stabilizing outlet 216 communicating with the interior of the combustion furnace 3. Downstream of the flame stabilizing chamber 213 is also a flame stabilizing outlet groove 217 communicating with the interior of the combustion furnace 3. The flame stabilizing outlet grooves 217 are evenly distributed on the outer side of the flame stabilizing outlet 216. The mixture of fuel and oxidizer is ejected through the flame stabilizing outlet 216 and the flame stabilizing outlet groove 217, forming a stable flame at the outlet of the flame stabilizing chamber 213.

[0039] Downstream of the annular oxidant channel 212 is an oxidant outlet 218 that communicates with the interior of the combustion furnace 3. Oxidant that does not enter the flame stabilization chamber 213 is directly sprayed out through the oxidant outlet 218, mainly for the combustion of pyrolysis gases sprayed from the swirl combustion nozzle 22 and the oscillating jet combustion nozzle 23.

[0040] There are three flame stabilizing inlet slots 215, which are evenly distributed around the circumference of the annular oxidizer channel 212. There are also three flame stabilizing outlet slots 217, which are evenly distributed around the flame stabilizing cavity 213. The flame stabilizing inlet slots 215 and flame stabilizing outlet slots 217 are staggered around the circumference of the flame stabilizing cavity 213.

[0041] The flame stabilizing chamber 213 only serves the purpose of premixing and stabilizing the flame; the combustion of fuel and oxidizer mainly occurs at the outlet of the flame stabilizing chamber 213.

[0042] like Figure 2 , Figure 3 , Figure 7 andFigure 8 As shown, the specific structure of the swirl combustion nozzle 22 is described in detail.

[0043] The swirl combustion nozzle 22 includes a swirl channel 221 and swirl blades 222. The swirl channel 221 is arranged around the periphery of the central flame-stabilizing combustion nozzle 21 and is used to introduce high-temperature pyrolysis gas from the pre-combustion chamber 1. The swirl blades 222 are disposed inside the swirl channel 221 near the outlet. The ends of the swirl blades 222 are fixedly connected to the inner wall of the swirl channel 221, while the middle and front ends of the swirl blades 222 are slidably connected to the inner wall of the swirl channel 221. The swirl blades 222 adopt a spring-loaded structure and have a certain elastic deformation capability. After the airflow passes through the swirl blades 222, it generates a rotational motion, forming a recirculation zone that entrains high-temperature flue gas, thereby enhancing ignition and stabilizing combustion.

[0044] A sliding block 223 is fixedly connected to the outer front end of the swirl blade 222. A sliding groove 224 is provided on the outer wall of the swirl channel 221, allowing the sliding block 223 to slide circumferentially along the outer wall of the swirl channel 221. A rotating sleeve 225 is rotatably mounted on the outer wall of the swirl channel 221, and an axial groove 226 corresponding to the sliding groove 224 is provided on the inner side of the rotating sleeve 225. The outer end of the sliding block 223 is slidably disposed within the axial groove 226, allowing the sliding block 223 to slide axially along the swirl channel 221 within the axial groove 226. The widths of both the sliding groove 224 and the axial groove 226 are greater than the width of the sliding block 223 to ensure that the sliding block 223 can move both circumferentially and axially.

[0045] The swirl intensity adjustment method of the swirl blade 222 is as follows: When the rotating sleeve 225 rotates on the outer wall of the swirl channel 221, the rotating sleeve 225 drives the sliding block 223 to move circumferentially along the outer wall of the swirl channel 221 through the axial groove 226. Since the inner end of the sliding block 223 is fixedly connected to the front end of the swirl blade 222, and the end of the swirl blade 222 is fixed, the torsion angle of the swirl blade 222 is changed, thereby realizing the active adjustment of the swirl intensity. At the same time, as a spring-loaded structure, when the swirl blade 222 rotates with the sliding block 223, the elastic deformation of the swirl blade 222 drives the sliding block 223 to move axially along the axial groove 226 and the sliding groove 224, causing the axial position of the front end of the swirl blade 222 to change, adaptively changing the swirl intensity to adapt to fluctuations in operating conditions.

[0046] Under intermediate load conditions, the swirl intensity of the swirl blades 222 is increased to increase the radial velocity and decrease the axial velocity, thereby widening the flame and improving flame and combustion stability. Under high load conditions, the swirl intensity of the swirl blades 222 is decreased to increase the axial velocity and decrease the radial velocity, thereby enhancing the jet impact and ensuring the flame penetration depth and impact effect.

[0047] like Figure 6As shown, the specific structure of the oscillating jet combustion nozzle 23 is described in detail.

[0048] There are two oscillating jet combustion nozzles 23, which are symmetrically arranged around the periphery of the swirling combustion nozzle 22. Each oscillating jet combustion nozzle 23 is provided with an air inlet section 231, a contraction section 232, an oscillation section 233 and an air outlet section 234 from front to back.

[0049] The oscillation section 233 includes an upper oscillation inclined plate 235 hinged above the air outlet of the contraction section 232 and inclined upwards, and a lower oscillation inclined plate 236 hinged below the air outlet of the contraction section 232 and inclined downwards. Return springs (not shown) are respectively provided at the hinged connections between the upper oscillation inclined plate 235 and the lower oscillation inclined plate 236 and the contraction section 232 to allow the upper oscillation inclined plate 235 and the lower oscillation inclined plate 236 to open.

[0050] The intake section 231 and the contraction section 232 are located in the inner tube 237, while the oscillation section 233 and the exhaust section 234 are located in the outer tube 238. The outer side of the inner tube 237 and the inner side of the outer tube 238 are connected by a threaded connection. A disturbance element 2310 is provided inside the exhaust section 234. A retaining ring 239 is provided on the inner wall of the outer tube 238 corresponding to the positions of the upper oscillation inclined plate 235 and the lower oscillation inclined plate 236.

[0051] When the inner tube 237 and the outer tube 238 rotate relative to each other, under the threaded engagement, the inner tube 237 and the outer tube 238 will move axially relative to each other, thereby adjusting the distance between the disturbance element 2310 and the outlet of the contraction section 232. When the upper oscillating inclined plate 235 and the lower oscillating inclined plate 236 move with the inner tube 237 and touch the retaining ring 239, the inclination angle of the upper oscillating inclined plate 235 and the lower oscillating inclined plate 236 can change, thereby adjusting the inclination angle of the upper oscillating inclined plate 235 and the lower oscillating inclined plate 236 of the oscillating section 233. Through the above structure, the oscillating jet combustion nozzle 23 can generate an oscillating jet, ensuring uniform distribution of gas in the furnace.

[0052] like Figure 1 and Figure 9 As shown, this embodiment provides an oxygen-enriched, low-load, low-nitrogen combustion method.

[0053] This combustion method uses the aforementioned oxygen-enriched, low-load, low-NOx combustion system and includes the following steps:

[0054] The fuel and oxidant partially combust and heat up in the pre-combustion chamber 1, undergoing a pyrolysis reaction to produce high-temperature pyrolysis gas. The pyrolysis gas discharged from the pre-combustion chamber 1 is then sent to the combustion furnace 3 for combustion through the central flame stabilizing combustion nozzle 21, the swirling combustion nozzle 22, and the oscillating jet combustion nozzle 23, respectively.

[0055] This combustion method has three load modes:

[0056] Full-load mode: The center stabilizing flame combustion nozzle 21, the swirling flame combustion nozzle 22, and the oscillating jet combustion nozzle 23 are activated to achieve 100% total load output. At this time, the center stabilizing flame combustion nozzle 21 bears 15% of the load, the swirling flame combustion nozzle 22 bears 50% of the load, and the two oscillating jet combustion nozzles 23 each bear 17.5% of the load (totaling 35% of the load). In full-load mode, the swirl intensity of the swirling blades 222 is reduced, increasing the axial velocity and decreasing the radial velocity, thereby enhancing the jet impact.

[0057] Intermediate load mode: Open the center flame stabilizer nozzle 21 and the swirl nozzle 22, and close the oscillating jet nozzle 23. The total load is 65% (15% + 50%). In intermediate load mode, the swirl intensity of the swirl blades 222 is increased, which widens the flame and improves flame stability and combustion stability.

[0058] Low-load mode: The center flame stabilizer nozzle 21 is activated, while the swirl nozzle 22 and the oscillating jet nozzle 23 are deactivated. The minimum load in low-load mode is 15% of the total load. Through the above-described tiered activation strategy, a wide range of load regulation is achieved, from 15% ultra-low load to 100% full load. When switching from full-load mode to low-load mode, the oscillating jet nozzle 23 and the swirl nozzle 22 are deactivated in stages.

[0059] The combustion method adopts a two-stage oxygen-enriched combustion form. The oxidant in the main burner 2 is a mixture of by-product oxygen and air.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. An oxygen-enriched, low-load, low-NOx combustion system, characterized in that, It includes a pre-combustion chamber (1) and a main burner (2); The outlet of the pre-combustion chamber (1) is connected to the inlet of the main burner (2); The main burner (2) is provided with a central flame stabilizing nozzle (21), a swirling combustion nozzle (22) and an oscillating jet combustion nozzle (23) arranged sequentially from the inside to the outside. The central flame stabilizer nozzle (21) is coaxially disposed at the center of the swirling flame nozzle (22), the swirling flame nozzle (22) is arranged around the periphery of the central flame stabilizer nozzle (21), and the oscillating jet nozzle (23) is disposed around the periphery of the swirling flame nozzle (22). The combustion furnace (3) has the main burner (2) fixedly installed on the furnace chamber of the combustion furnace (3). The central flame stabilizing combustion nozzle (21), the swirl combustion nozzle (22) and the oscillating jet combustion nozzle (23) are located on the furnace wall of the combustion furnace (3). The pyrolysis gas outlet of the pre-combustion chamber (1) is connected to the central flame stabilizing combustion nozzle (21), the swirl combustion nozzle (22) and the oscillating jet combustion nozzle (23) respectively. The air separation nitrogen generator (4) has an oxygen byproduct outlet connected to the annular oxidant channel (212) of the central flame stabilizing combustion nozzle (21), and air is also introduced into the annular oxidant channel (212).

2. The oxygen-enriched, low-load, low-NOx combustion system according to claim 1, characterized in that, The central flame stabilizer combustion nozzle (21) includes a central fuel channel (211), an annular oxidizer channel (212), and a flame stabilizer chamber (213). The central fuel channel (211) is axially positioned at the center of the central flame-stabilizing combustion nozzle (21). The annular oxidizer channel (212) is arranged around the periphery of the central fuel channel (211). The flame-stabilizing cavity (213) is located at the downstream end of the central fuel channel (211). A flame-stabilizing air inlet (214) communicating with the interior of the central fuel channel (211) is provided upstream of the flame-stabilizing cavity (213). A flame-stabilizing air inlet groove (214) communicating with the interior of the annular oxidizer channel (212) is also uniformly arranged upstream of the flame-stabilizing cavity (213). 15) The flame stabilizing air inlet groove (215) is evenly distributed on the outside of the flame stabilizing air inlet (214). Downstream of the flame stabilizing cavity (213) is a flame stabilizing air outlet (216) that communicates with the inside of the furnace of the combustion furnace (3). Downstream of the flame stabilizing cavity (213) is a flame stabilizing air outlet groove (217) that communicates with the inside of the furnace of the combustion furnace (3). The flame stabilizing air outlet groove (217) is evenly distributed on the outside of the flame stabilizing air outlet (216). Downstream of the annular oxidant channel (212) is an oxidant outlet (218) that communicates with the inside of the furnace of the combustion furnace (3).

3. The oxygen-enriched, low-load, low-NOx combustion system according to claim 2, characterized in that, The number of the flame stabilizing air inlet grooves (215) is three, and the three flame stabilizing air inlet grooves (215) are evenly distributed along the circumference of the annular oxidant channel (212); The number of the flame stabilizing gas outlet grooves (217) is three, and the three flame stabilizing gas outlet grooves (217) are evenly distributed around the flame stabilizing cavity (213) along the circumference of the flame stabilizing cavity (213). The flame stabilizing air inlet groove (215) and the flame stabilizing air outlet groove (217) are staggered in the circumferential direction of the flame stabilizing cavity (213).

4. The oxygen-enriched, low-load, low-NOx combustion system according to claim 1, characterized in that, The swirling combustion nozzle (22) includes a swirling channel (221) and swirling blades (222). The swirling channel (221) is arranged around the periphery of the central flame-stabilizing combustion nozzle (21). The swirling blade (222) is disposed inside the swirling channel (221) near the outlet. The end of the swirling blade (222) is fixedly connected to the inner wall of the swirling channel (221). The middle and front ends of the swirling blade (222) are slidably connected to the inner wall of the swirling channel (221). A sliding block (223) is fixedly connected to the outer side of the front end of the swirling blade (222). A sliding groove (224) is provided on the outer wall of the swirling channel (221) for the sliding block (223) to slide circumferentially along the outer wall of the swirling channel (221). A rotating sleeve (225) is rotatably disposed on the outer side of the outer wall of the swirling channel (221). A corresponding sliding groove (224) is provided on the inner side of the rotating sleeve (225). The axial groove (226) is provided, and the outer end of the sliding block (223) is slidably disposed in the axial groove (226). The sliding block (223) can slide axially along the vortex channel (221) in the axial groove (226). The width of the sliding groove (224) and the axial groove (226) is greater than the width of the sliding block (223). When the rotating sleeve (225) rotates on the outer wall of the vortex channel (221), the rotating sleeve (225) can drive the sliding block (223) to move circumferentially along the outer wall of the vortex channel (221). Since the inner end of the sliding block (223) is fixedly connected to the front end of the vortex blade (222), the vortex blade (222) adopts a spring plate structure. The vortex blade (222) can drive the sliding block (223) to move axially along the vortex channel (221), thereby changing the vortex degree of the vortex blade (222).

5. The oxygen-enriched, low-load, low-NOx combustion system according to claim 1, characterized in that, The number of the oscillating jet combustion nozzles (23) is two, and the two oscillating jet combustion nozzles (23) are symmetrically arranged around the swirling combustion nozzle (22).

6. The oxygen-enriched, low-load, low-NOx combustion system according to claim 1, characterized in that, It also includes a control system configured such that the load on the central flame stabilizer nozzle (21) is 15% of the total load; the load on the swirling flame nozzle (22) is 50% of the total load; and the load on the oscillating jet flame nozzle (23) is 35% of the total load. In the intermediate load mode, the swirl intensity of the swirl blades (222) is increased; In the full-load mode, the swirl intensity of the swirl blades (222) is reduced; The minimum load for the low-load mode is 15% of the total load.

7. The oxygen-enriched, low-load, low-NOx combustion system according to claim 6, characterized in that, The load of each of the two oscillating jet combustion nozzles (23) is 17.5% of the total load.

8. The oxygen-enriched, low-load, low-NOx combustion system according to claim 1, characterized in that, Fuel is introduced into the fuel inlet of the pre-combustion chamber (1), and the oxidant inlet of the pre-combustion chamber (1) is connected to the by-product oxygen outlet of the air separation nitrogen generator (4) and air is introduced.

9. The oxygen-enriched, low-load, low-NOx combustion system according to claim 1, characterized in that, The oscillating jet combustion nozzle (23) is provided with an air inlet section (231), a contraction section (232), an oscillating section (233), and an air outlet section (234) in sequence from front to back. The oscillating section (233) includes an upper oscillating inclined plate (235) hinged to the upper side of the air outlet of the contraction section (232) and inclined upward, and a lower oscillating inclined plate (236) hinged to the lower side of the air outlet of the contraction section (232) and inclined downward. The air inlet section (231) and the contraction section (232) are located in the inner tube (237), and the oscillating section (233) and the air outlet section (234) are located in the outer tube (238). The outer side of the inner tube (237) and the inner side of the outer tube (238) are connected by a threaded connection. The air outlet section (234) is provided with a disturbance element (2310). The upper oscillating inclined plate (235) and the lower oscillating inclined plate (236) are connected to the contraction section. (232) is provided with return springs at the hinge connection to allow the upper oscillating inclined plate (235) and the lower oscillating inclined plate (236) to open. The inner wall of the outer tube (238) is provided with retaining rings (239) corresponding to the positions of the upper oscillating inclined plate (235) and the lower oscillating inclined plate (236). When the inner tube (237) and the outer tube (238) rotate relative to each other, the inner tube (237) and the outer tube (238) will move relative to each other axially under the threaded engagement, thereby adjusting the distance between the disturbance component (2310) and the outlet of the contraction section (232). When the upper oscillating inclined plate (235) and the lower oscillating inclined plate follow the movement of the inner tube (237) and touch the retaining ring (239), the tilt angle of the upper oscillating inclined plate (235) and the lower oscillating inclined plate can change, thereby adjusting the tilt angle of the upper oscillating inclined plate (235) and the lower oscillating inclined plate in the oscillation section (233).

10. A method for oxygen-enriched, low-load, low-NOx combustion, characterized in that, Combustion using the oxygen-enriched, low-load, low-NOx combustion system according to any one of claims 1 to 9 includes the following steps: After the fuel and oxidant are partially burned and heated in the pre-combustion chamber (1), the pyrolysis gas discharged from the pre-combustion chamber (1) is sent together into the combustion furnace (3) for combustion. In full load mode, the central flame stabilizer nozzle (21), the swirling combustion nozzle (22) and the oscillating jet combustion nozzle (23) are turned on. In the intermediate load mode, the central flame stabilizing combustion nozzle (21) and the swirling combustion nozzle (22) are turned on, and the oscillating jet combustion nozzle (23) is turned off. In low-load mode, the central flame stabilizer nozzle (21) is turned on, and the swirling combustion nozzle (22) and the oscillating jet combustion nozzle (23) are turned off. In the intermediate load mode, the swirl intensity of the swirling combustion nozzle (22) is increased; in the full load mode, the swirl intensity of the swirling combustion nozzle (22) is decreased.

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