Combustion system and combustion method for a boiler having a fuel flow distribution means in the burner.

Abstract

A combustion system and method, particularly for a power boiler, is provided. The combustion system (1) includes a burner (3, 3', 3'') that supplies a mixed flow (8) of fuel and primary air or gas to a combustion chamber (6) through at least one fuel nozzle (4), a duct (11, 47) in fluid communication with the at least one fuel nozzle (4) for directing the mixed flow (8) of fuel and primary air or gas to the at least one fuel nozzle (4), and a deflector device (21) disposed within the duct (11, 47) upstream of the at least one fuel nozzle (4) to deflect the incoming mixed flow (8) of fuel and primary air or gas. The deflector device (21) includes injection means (22) for injecting auxiliary gas (23) into the duct (11, 47) to deflect the incoming mixed flow (8) of fuel and primary air or gas in a direction from the center of the duct (11, 47) to an outer region thereof, thereby increasing the concentration of the mixed flow (8) of fuel and primary air or gas in the outer region (17) of the fuel nozzle (4) and decreasing the concentration of the mixed flow (8) of fuel and primary air or gas in the center (16) of the fuel nozzle (4).

Description

Technical Field

[0001] The present invention relates to a combustion system, and particularly to a combustion system for a power generation boiler having fuel flow distribution means in a burner and a combustion method using such a combustion system.

Background Art

[0002] Boilers often have a combustion system with a furnace that can be fired with solid fuels such as bituminous coal, lignite, biomass, etc. Such a combustion system typically includes a mill arranged to grind solid fuels such as coal and a duct for supplying the pulverized fuel to one or more burners. The finely pulverized coal and air (gas) are supplied to the combustion chamber of the boiler, ignited, and used to generate high-temperature flue gas that can be used to produce steam for power generation or other industrial applications, for example.

[0003] Instead of pulverized fuel, other fuel types such as gas fuels, for example natural gas, can also be used for combustion in boilers. For example, it is also desirable to use a fuel gas mixture obtained from refinery gas. Refinery gas is a by-product gas from an oil refinery generated during the processing of crude oil. Refinery gas has a low calorific value and can be mixed with natural gas and / or liquefied petroleum gas (LPG) and supplied to the furnace.

[0004] Generally, in the combustion process of fossil fuels, pollutants such as nitrogen oxides (NOx), particulate matter (PM), and carbon monoxide (CO) are generated. When these pollutants are discharged into the atmosphere, they can cause health hazards to humans and animals, have an adverse impact on the environment, and may accelerate global warming. Emission standards around the world, including in the United States and the EU, regulate the allowable emission limits for NOx, CO, and other pollutants. However, there is a need to further reduce the actual emission levels.

[0005] NOx emissions can be reduced by lowering the flame temperature, but lowering the flame temperature reduces radiant heat transfer from the flame, thus decreasing boiler efficiency. Some NOx control technologies used in boilers reduce NOx levels by lowering the flame temperature by changing the air / fuel mixture pattern. Lower flame temperatures and reduced mixture intensity result in high CO levels. High flame temperatures, a tight air / fuel mixture, and near-complete combustion of the fuel are essential for low CO emissions. High levels of CO emissions are mainly due to incomplete combustion caused by improper burner design or combustion conditions (e.g., improper air-fuel ratio).

[0006] Other problems may arise depending on the operating conditions. For example, in a pulverized coal combustion burner, the pulverized coal mill typically operates at a fairly constant air / gas volumetric flow rate across the entire load range. At low loads, the air-fuel ratio decreases, making the pulverized coal mixture lean and difficult to ignite. It also becomes difficult to properly stabilize the flame, and the flame may blow out or blow back. This can be exacerbated by poor quality and / or distribution pattern of the fuel supplied to the boiler's combustion chamber.

[0007] It is desirable to have a combustion system for boilers with different types and qualities of fuels, including fine fuels such as coal, petroleum coke, bituminous coal, lignite, and biomass, as well as a wide range of mixed gas fuels such as refinery and other waste gases, that can be used flexibly while ensuring high efficiency performance with safe fuel ignition and combustion, proper flame stabilization, and reduced NOx and CO emissions across the entire operating range, from full-load to partial-load operation.

[0008] Pulverized coal (PF) burners, such as pulverized coal (PC) burners, are often designed and operated with deflectors, impellers, kickers, or other structural features that protrude into the burner duct to alter the distribution of pulverized coal across the cross-section of the burner nozzle outlet. By distributing the pulverized fuel in a desired manner across the nozzle outlet, it is possible to provide different fuel concentrations and air-to-fuel ratios in various regions of the nozzle outlet, thereby affecting the combustion process, including flame stabilization, fuel burnout, and emissions levels. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] U.S. Patent No. 4669398 [Patent Document 2] European Patent No. 3026338 [Patent Document 3] U.S. Patent No. 6120281

[0010] US4669398A discloses a pulverizing fuel injection system comprising: a first pulverizing fuel injection section configured such that the total amount of primary and secondary air consumed is less than the theoretical amount of air required for the combustion of the pulverizing fuel; a second pulverizing fuel injection section configured such that the total amount of primary and secondary air consumed is substantially equal to the theoretical amount of air for the pulverizing fuel; and an auxiliary air section for injecting auxiliary air into the furnace. The three sections are located in close proximity to each other and control NOx generation during the combustion of the pulverizing fuel.

[0011] EP3026338A1 discloses a combustion system for a boiler and a method for burning solid fuel. The combustion system includes a burner that supplies a mixture of fuel and primary air to the combustion chamber of the boiler via a fuel nozzle. The mixture of fuel and primary air is supplied to the burner via a duct from a crusher that crushes the fuel. A fuel concentrator consisting of a deflector and a diverter is placed in the duct to concentrate the mixture of fuel and primary air at the center of the fuel nozzle. The fuel-rich concentrated jet at the center of the nozzle outlet is described as improving the gasification of the mixture of fuel and primary air, improving the burner's NOx emission performance, and improving ignition and flame stability.

[0012] US6120281A proposes a combustion method utilizing tangential firing, in which a mixture of coal and primary air is discharged from burners located at the corners of the furnace toward a hypothetical circle at the center of the furnace. The air is discharged in two flows from air nozzles also located at the corners of the furnace: one directed toward the center of the furnace to support combustion of the fuel, and the other directed toward the inner surface of the furnace boundary wall to maintain an oxidizing atmosphere and minimize corrosion and slugging. [Overview of the project]

[0013] The object of the present invention is to eliminate or at least reduce the drawbacks of conventional combustion systems and methods designed for boilers as described above. In particular, the object is to provide a combustion system and combustion method suitable for use in boilers that can be flexibly used with different types and qualities of fuel, while providing high-efficiency performance with safe ignition and combustion of fuel, proper flame stabilization, and reduced NOx and CO emissions over a wide operating range. This is preferably achieved using a simple and low-wear design for the combustion system.

[0014] According to a first aspect, the present invention relates to a combustion system, particularly for a boiler, comprising: at least one burner that supplies a mixture of fuel and gas to a combustion chamber via at least one fuel nozzle; a duct in fluid communication with at least one fuel nozzle for guiding the mixture of fuel and gas to at least one fuel nozzle; and a deflector device disposed in the duct upstream of the at least one fuel nozzle for deflecting the incoming mixture of fuel and gas. The deflector device includes an injection means that injects an auxiliary gas into the duct to deflect the incoming mixture of fuel and gas outward from the center of the duct.

[0015] The present invention employs a type of "fluid deflector" that uses a fluid in the form of an auxiliary gas injected from an injection means to deflect the fuel-gas mixture flowing from the center of the duct towards the duct wall or near the wall, instead of conventional structural deflectors (solid deflectors), impellers, or kickers. The injected auxiliary gas collides with the incoming fuel-gas mixture, diffusing it into the surroundings to form distinct fuel-rich zones and fuel-lean zones at the burner or fuel nozzle outlet, which provides a typical setup for a low-NOx burner.

[0016] According to the present invention, in contrast to the various means used in conventional designs to concentrate a fuel-rich jet at the center of the fuel nozzle outlet, the injection means is positioned relative to the fuel nozzle and configured to deflect the incoming fuel-gas mixture to increase the concentration of the fuel-gas mixture in the outer region of the fuel nozzle and decrease the concentration of the fuel-gas mixture in the central part or center of the fuel nozzle. This improves the homogenized flow of fuel that enters the combustion chamber and is burned there.

[0017] It should be noted that the gas referred to herein may be any air, gas (high-temperature or low-temperature gas), or mixture of air and gas that can be used for mixing with fuel in the combustion chamber and for combustion of the fuel-air mixture. Gas is referred to herein interchangeably as primary air or primary air and gas. Gas may also include recirculated flue gas resulting from combustion in the combustion chamber. Similarly, auxiliary gas referred herein may be any air, gas, or mixture of air and gas suitable for performing its function as described herein. Auxiliary gas may be taken from the primary air or gas or secondary air supply of the burner, and at least a portion may be recirculated gas resulting from combustion and recycled to the exhaust means. This may also be fresh air taken from outside using a fan or blower and pushed to the exhaust means, for example, if the boiler does not have enough primary and / or secondary air to supply auxiliary gas, or if the coal or gas fuel has a low calorific value or low pulverization grade and additional air is advantageous. The terms “air” and “gas” are used herein solely to distinguish between gaseous fluid streams for the sake of clarity and understanding.

[0018] The combustion system of the present invention can use any desired fuel. In preferred applications, pulverized fuels (PF) such as pulverized coal, petroleum coke, bituminous coal, lignite, and biomass can be used. The fuel may also be a fuel gas mixture obtained, for example, from refinery gas or other waste gases.

[0019] In a PF combustion burner, the grinding fuel may be supplied by a grinder or mill connected to a duct. The grinding mill can operate at a very constant air / gas volume flow rate throughout the entire load range. The deflector device of the present invention then provides an increased PF fuel concentration to the area outside the burner outlet, thus assisting flame stabilization and ignition, particularly in the low-load operating range of the burner.

[0020] In a preferred embodiment of the present invention, the injection means may include an auxiliary gas nozzle configured to receive an auxiliary gas and inject the auxiliary gas in the direction of flow of the fuel-gas mixture, or at least at an oblique angle. That is, the injected auxiliary gas has at least a counterflow direction component opposite to the direction of flow of the fuel-gas mixture. In this way, the fuel-gas mixture can be efficiently deflected and, if desired, distributed to the sides of the duct. The auxiliary gas nozzle may also be obliquely oriented to induce swirl motion in the inflow of fuel.

[0021] In a particularly preferred embodiment, the auxiliary gas nozzle may be a counterflow nozzle having a nozzle outlet oriented in the opposite direction to the flow direction of the fuel-gas mixture, such that the jet of injected auxiliary gas collides with the inflow mixture of fuel and gas in the opposite direction. Uniform deflection and distribution of the fuel-gas mixture can be achieved in all outer portions of the fuel nozzle outlet.

[0022] It may be advantageous to install auxiliary gas nozzles, particularly counter-flow nozzles, in the horizontal duct portion of a duct directly connected to the fuel nozzle, especially in the duct portion that passes straight downstream of a last duct elbow, where there is no duct curvature. Furthermore, the auxiliary gas nozzles may be positioned on the horizontal centerline of the duct portion, i.e., on the burner's central axis. This allows for a high degree of control over the fuel distribution pattern obtained at the nozzle outlet.

[0023] In any configuration of an auxiliary gas nozzle, particularly a counterflow nozzle, by injecting the auxiliary gas at least partially in a direction opposite to the main fuel flow through the nozzle, the outer layer of the fuel flow can be made thicker, that is, the fuel concentration at the outer portion of the burner outlet can be increased, the fuel concentration at the intermediate portion of the burner outlet can be decreased, and the fuel flow can be homogenized across the cross section. Thereby, a burner with improved ignition performance of the burner, a large effective ignition area, operating in a low load operation range, and low emissions of NOx and CO can be obtained. The low NOx emission level achieves a reducing atmosphere in the inner flame and effectively reduces NOx by reducing substances such as volatile substances and char. The increase in fuel concentration in this region reduces the high oxygen level region in the outer flame of the ignition region. The auxiliary gas nozzle does not include wear parts that receive the mixed flow of fuel and gas, such as structural deflectors, impellers, etc., so less maintenance is required. Erosion and wear of the burner hardware can be significantly or minimally suppressed.

[0024] In the case of lignite burners using core air, it is possible to redirect and use a part of the core air and inject this part of the core air into the duct as a counterflow. Only minor changes to existing lignite low-NOx burners are required.

[0025] The combustion system of any of the above embodiments may further include injection means, in particular means configured to change the outlet velocity of the auxiliary gas injected from the outlet of an auxiliary gas nozzle. For example, the control device of the combustion system may adjust a flow control valve in the supply line connected to the auxiliary gas nozzle. In addition, or alternatively, the injection means, in particular the auxiliary gas nozzle, may include throttling means configured to change the flow cross-section of the auxiliary gas nozzle to adjust the velocity of the injected auxiliary gas. In other words, the injection means or injection nozzle may have a variable opening so that the size of the cross-section can be changed, thereby affecting the velocity of the injected auxiliary gas. In some embodiments, an additional gas blower or fan with adjustable or controllable speed can be provided to change the outlet velocity of the auxiliary gas.

[0026] Advantageously, changing the velocity of the injected auxiliary gas can achieve the same effect as changing the position and size of a fluid deflector or solid deflector (structural deflector), impeller, or kicker in a conventional system. The velocity of the counterflow-injected auxiliary gas determines the size and position of the obstruction to the inflow mixture of fuel and gas. This makes it easier to control how efficiently coal particles or the mixed gas fuel flow are deflected outward from the center of the fuel gas flow. Thus, the combustion system can be easily adapted to accommodate different types and qualities of fuel, including different degrees of grinding and / or drying of pulverized fuel, and the flexibility in adjusting the auxiliary gas flow rate also allows it to easily react to different burner operating conditions.

[0027] In a further configuration of any of the embodiments of the combustion system described above, the injection means, particularly the auxiliary gas nozzle, may be arranged to be adjustable with respect to its direction in space, such that the injection or discharge angle may be changed or adjusted as necessary with respect to at least two of the three orthogonal axes X, Y, and Z. In such a configuration, one or both of the velocity and the number of swirls of the auxiliary gas to be injected can be adjusted as necessary in response to the fuel type and the operating mode, for example, partial load operation, even during burner operation (online). If necessary, an additional gas blower or fan may be used.

[0028] Any embodiment including the auxiliary gas nozzle described above, particularly the counterflow nozzle, may further include a shielding device (shielding device) disposed upstream of the supply line for supplying the auxiliary gas to the auxiliary gas nozzle and in the duct in the vicinity thereof to shield the supply line from erosion and wear by the inflowing mixed stream of fuel and gas. The shielding device may be, for example, in the form of a semi-cylindrical shell or plate and may be made of a wear-resistant material.

[0029] In some advantageous embodiments, the combustion system may further include baffle means disposed upstream, i.e., upstream of the auxiliary gas nozzle outlet, and having a concave surface facing in the direction of the auxiliary gas nozzle outlet for diffusing the discharged auxiliary gas to the side surface of the duct. The baffle means may preferably be dish-shaped or bowl-shaped so as to uniformly distribute the discharged auxiliary gas outward toward the duct wall surrounding the duct. The deflection effect of the counterflow nozzle can be enhanced.

[0030] The combustion systems described so far may have burners and ducts of any shape or size. For example, the ducts may have a circular or rectangular cross-section. In some specific types of combustion systems, the burner may be a round burner including a tubular primary duct for supplying a mixed flow of fuel and gas to the combustion chamber, and at least a tubular secondary duct arranged concentrically with the primary duct such that the downstream end of the primary duct defines a fuel nozzle, for supplying secondary air (or gas) to the combustion zone of the combustion chamber. The burner may optionally further include a tubular third duct arranged concentrically with the second duct for supplying a third air (or gas) to the combustion zone of the combustion chamber. The deflector device may include a swirl tube arranged to supply auxiliary gas to the duct and discharge it into the duct in such a direction that it deflects the inflow mixed flow of fuel and gas toward the outer region of the main duct and induces a swirling motion of the mixed flow of fuel and gas around the longitudinal axis of the main duct.

[0031] The swirl pipe deflects the fuel-gas mixture entering from the center of the duct outwards within the duct, while simultaneously swirling the mixture to improve mixing. This creates a favorable fuel distribution with a fuel-rich zone in the outer region of the fuel nozzle outlet and a fuel-lean zone in the center of the fuel nozzle outlet, enabling the achievement of a stable flame, an enhanced fuel outburn, and a large fireball within the combustion zone with low NOx and CO emission levels.

[0032] In some embodiments, the circular burner may further comprise a core tube located in the center of the circular burner within a primary duct for supplying auxiliary core air to the combustion chamber, and the swirl tube may be an additional tube (additional tube) arranged around the core tube and sealed to it at its downstream end. The additional tube may have elongated inclined slots that penetrate the walls of the additional tube and extend at angles to the longitudinal direction of the additional tube and to planes perpendicular to the longitudinal direction, and the elongated through-slots are located close to the sealed downstream end at a distance from the burner outlet.

[0033] In other embodiments, the swirl pipe may be a closed pipe located at the center of a circular burner within the main duct and having a closed downstream end. The closed pipe may have an elongated inclined slot penetrating the wall of the closed pipe and extending at an angle to the longitudinal direction of the closed pipe and to a plane perpendicular to the longitudinal direction, where the elongated penetrating slot is located close to the closed downstream end in terms of distance from the burner outlet.

[0034] In any of the embodiments described above, the auxiliary gas may be supplied to additional tubes and closure tubes, respectively, and flow through these tubes and exit into the main duct through through-slots or notches. The through-slots are arranged at an angle to cause a kind of twist or swirl in the discharged auxiliary gas, and the fuel particles or mixed gas fuel flow is deflected by this swirling gas to the area outside the gas and fuel duct. The swirl tube may be nonmetallic and does not include any impeller or other means protruding into the main duct so as to reduce pressure loss and wear.

[0035] In another embodiment, a combustion method is provided, characterized by supplying a mixture of fuel and gas from at least one burner to a combustion chamber via a duct through at least one fuel nozzle, and deflecting the incoming mixture of fuel and gas in the duct using an injection means, wherein the injection means injects an auxiliary gas into the duct to deflect the incoming mixture of fuel and gas from the center of the duct toward the outer region, increasing the concentration of the mixture of fuel and gas in the outer region of the fuel nozzle and decreasing the concentration of the mixture of fuel and gas in the central part of the fuel nozzle or in the central part.

[0036] The combustion method of the present invention can be carried out using the combustion system of any of the embodiments described above, and similar effects can be obtained. To avoid repetition, the above descriptions of embodiments of the combustion system of the present invention and their advantages are generally referenced and apply equally to the method of the present invention.

[0037] In some embodiments of this method, deflecting the incoming mixed flow of fuel and gas in the duct can be advantageously carried out using an auxiliary gas nozzle, preferably a counterflow nozzle that receives the auxiliary gas and injects the auxiliary gas in the opposite direction to the flow direction of the mixed fuel and gas, or at least at an oblique angle.

[0038] In another embodiment of this method, deflecting the incoming fuel-gas mixture in the duct can be accomplished using a swirl pipe positioned within the duct and configured to deflect the incoming fuel-gas mixture toward the outer region of the primary duct and to discharge auxiliary gas into the duct through a slot inclined in such a direction that it induces a swirling motion of the fuel-gas mixture around the longitudinal axis of the primary duct.

[0039] Further details of advantageous embodiments of the present invention can be referenced from the dependent claims, drawings and related detailed description. The present invention will now be described in more detail with reference to the drawings, which illustrate exemplary embodiments of the present invention, and the present invention is not limited in any sense, and the same reference numerals are used in all drawings to specify the same elements. The drawings are as follows: [Brief explanation of the drawing]

[0040] [Figure 1] Figure 1 is a simplified perspective view of a combustion system including a counterflow nozzle according to an exemplary embodiment of the present invention. [Figure 2] Figure 2 is a side view of the combustion system shown in Figure 1. [Figure 3] Figure 3 is a front view of the outlet of a burner having two fuel nozzles above and below the fuel nozzle and a secondary air nozzle, according to an exemplary embodiment of the present invention. [Figure 4] Figure 4 is a top view of the combustion system shown in Figures 1 to 3. [Figure 5]Figure 5 is a schematic side view of one of the fuel nozzles of the combustion system shown in the figure. Figures 1 to 4 show the flow of the mixed fuel and gas in the combustion chamber, and the resulting flame, to illustrate the operation of the combustion system according to one embodiment of the present invention. [Figure 6] Figure 6 is a top view of a combustion system, including a variation of the deflector device of the combustion system, according to another exemplary embodiment of the present invention. [Figure 7] Figure 7 is an enlarged schematic cross-sectional view of the combustion system in Figure 6, showing the flow of the mixed fuel and gas. [Figure 8] Figure 8 is a side view of a combustion system including a circular burner and a swirl tube according to another exemplary embodiment of the present invention. [Figure 9] Figure 9 is a simplified and enlarged view of the swirl pipe used in the circular burner shown in Figure 8. [Figure 10] Figure 10 is a side view of another type of circular burner, including a combustion system and a swirl tube, according to another exemplary embodiment of the present invention. [Figure 11] Figure 11 is a simplified, enlarged partial side view of the combination of the core air tube and swirl tube used in the circular burner shown in Figure 10. [Figure 12] Figure 12 is a top view of a boiler having a tangential arrangement of burners according to an exemplary embodiment of the present invention. [Figure 13] Figure 13 is a front view of a boiler having a fire arrangement in front of the burner indicating the fuel swirling direction, according to an exemplary embodiment of the present invention. [Modes for carrying out the invention]

[0041] Figure 1 shows a side view of a combustion system 1 for use with a power generation boiler 2 (not shown in Figure 1, but shown in Figure 5), for example, according to an exemplary embodiment of the present invention. Figures 2, 3, and 4 show a side view, front view, and top view of the combustion system 1 of Figure 1. Figures 1 and 5 are partial schematic diagrams showing the operation of the combustion system 1 placed in the boiler 2. In the illustrated exemplary embodiment, the combustion system 1 includes a burner 3 having at least one, in this case two, fuel nozzles 4 at its free end, which supplies a mixed flow of fuel and gas to the combustion chamber 6 of the boiler 2 (shown in Figures 2 and 5) via at least one fuel nozzle 4. The burner 3 is connected to a fuel source (not shown) via a duct system 7. In a preferred application, the burner 3 may be connected to a crusher or mill (not shown) configured to crush solid fuel such as coal, coke, lignite, or biomass to the desired finish and supply a mixed flow 8 of crushed fuel and gas to the burner 3 and further to the fuel nozzles 4 via the duct system 7. Combustion system 1 is particularly suitable for use as a lignite combustion system 1.

[0042] On the other hand, the combustion system 1 shown in Figures 1 to 4 is illustrated and described as including a pulverized fuel burner 3 to supply a mixed flow 8 of pulverized fuel and gas to a fuel nozzle 4 and into the combustion chamber 6. The combustion system 1 can be used with any desired fuel, and in particular, fuel gas mixtures obtained from purified gas or other combustible waste gases may be used. The description with respect to pulverized coal fuel (PF), such as pulverized coal, shall also apply to other types of fuels, in particular fuel gas mixtures from purified gas.

[0043] Furthermore, the combustion system shown in Figures 1 to 4 includes one burner 3 and two fuel nozzles, and the combustion system may include any number of one, two, three or more burners 3 and / or fuel nozzles 4.

[0044] Referring again to Figures 1 to 4, the duct system 7 in this example includes a first duct section 9, which, in the operating state, is a vertical duct section 9 as shown in the figure and is a common duct for the system. The combustion system 1 also has a separate first vertical duct section 9 for each individual burner 3, and a second duct section 11, which is a horizontal duct section that is fluidly connected to the first vertical duct section 9 via a corresponding elbow 12 in the operating state, as shown in the figure. The duct sections 9 and 11 may each have, for example, a rectangular cross-section.

[0045] Referring particularly to Figure 3, a simplified front view of the burner outlet 13, including two fuel nozzles 4 and a secondary air nozzle 14, is shown. Each fuel nozzle 4 is subdivided into a central nozzle section 16 located in the center or middle of each fuel nozzle 4, and peripheral nozzle sections 17 arranged to surround the central nozzle section 16. The sections 17 are located at each corner of the central nozzle section 16 and around it.

[0046] The secondary air nozzles 14 are positioned above and below each fuel nozzle 4 and, for example, inject secondary air 15 into the combustion chamber 6 of the boiler 2, thereby stably burning the fuel-gas mixture 8 in the combustion chamber 6. The axis C of the secondary nozzle 14 (see Figure 5) is parallel to the axis B of the fuel nozzle 4. The fuel nozzle 4 may have a peripheral fuel nozzle channel 18 that is in fluid communication with the peripheral nozzle portion 17 of the nozzle outlet 13, and a core air pipe 19 that is in fluid communication with the central nozzle portion 16 of the nozzle outlet 13.

[0047] Refer again to Figures 1, 2, and 4. As shown in each figure, the combustion system 1 of the exemplary embodiment includes a deflector device 21 positioned within a second, downstream of the corresponding elbow 12 and upstream of the corresponding fuel nozzle 4, on the horizontal duct portion 11 (later also simply referred to as duct 11) of the duct system 7, in order to deflect the incoming mixture flow 8 of fuel and gas before it is supplied to the fuel nozzle 4. The deflector device 21 includes ejection means 22 for ejecting auxiliary gas 23 into the duct 11 in order to deflect the mixture flow 8 of fuel and gas flowing outward from the center of the duct 11.

[0048] In the exemplary embodiments shown in Figures 1-5, the injection means 22 includes an auxiliary gas nozzle 24 configured to receive an auxiliary gas 23 and inject the auxiliary gas 23 in a direction at least oblique to the flow direction 26 of the incoming fuel-gas mixture 8. In particular, the auxiliary gas nozzle 24 may be a counterflow nozzle having a nozzle outlet 27 oriented upstream of the fuel-gas, i.e., opposite to the flow direction 26, such that the jet of injected auxiliary gas 23 collides with the incoming fuel-gas mixture 8 in the opposite direction. As a result, the incoming fuel-gas mixture 8 is uniformly deflected and distributed outward along the side or duct wall 28 of the duct 11, increasing the concentration of the fuel-gas mixture 8 in the outer region or peripheral nozzle portion 17 of the fuel nozzle 4 and decreasing the concentration of the fuel-gas mixture 8 in the central region or central portion 16 of the fuel nozzle 4. This provides a desired distribution of fuel flow for improving ignition and combustion in the combustion chamber 6.

[0049] As shown in Figures 1 and 4, for example, a supply line 29 is provided in fluid communication with an auxiliary gas nozzle (secondary flow nozzle) 24 to supply auxiliary gas 23 to the auxiliary gas nozzle 24. In the illustrated example, the supply line 29 extends through the side wall of the burner 3, but it may also be provided through one of the duct walls 28 of the duct 11. The auxiliary gas 23 supplied by the supply line 29 may be any air, gas, or mixture of air and gas that is available and suitable to perform the deflection function of the present invention. In particular, the auxiliary gas 23 may be tapped from the gas or secondary air supply of the burner 3. It may also include at least a portion of recirculated gas (not shown) that is generated in the combustion chamber 6, returned, mixed with additional air or gas, and supplied to the supply line 29. If sufficient primary and / or secondary air is not available in the boiler 2, fresh air can be taken in from the outside and supplied to the supply line 29 via a blower or fan. In particular, when the grinding grade of the pulverized fuel is low, or when the calorific value of the pulverized fuel or fuel gas mixture is low, the combustion of the fuel can be promoted by using or adding fresh air.

[0050] Continuing with reference to Figures 1 and 4, the shielding device 31 can be placed inside the duct 11 to shield the feed line 29 from the fuel and gas inflow mixture 8, by positioning it upstream of the portion of the feed line 29 that flows through the duct 11, in order to prevent erosion and wear of the feed line 29. The shielding device 31 may be, for example, in the form of a semi-cylindrical shell or plate positioned close to the feed line 29 and partially surrounding the sides of the feed line 29. The shielding device 31 is made of a wear-resistant material, such as steel, alloy, or wear-resistant plastic material. The shielded feed line 29 can be manufactured from any material, including plastic material. The shielding device 31 may be omitted if not necessary.

[0051] The operation of the combustion system 1 described above will be explained in more detail using Figure 5. Figure 5 shows a cutout of the combustion system 1 in the figure. For clarity, Figures 1 to 4 show only a portion of the duct system 7, which includes a part of the burner 3, a vertical duct section 9 and a horizontal duct section 11, a fuel nozzle 4 at the free end of the burner 3, and two secondary nozzles 14 positioned above and below the fuel nozzle 4. The vertical axis A indicates the outer boundary or wall of the combustion chamber 6 of the boiler 2 where the outlet 13 of the fuel nozzle 4 is located. A mixture of fuel and gas 8 is supplied through the duct system 7. The fuel may be crushed fuel, in particular crushed coal, or a fuel gas mixture including, for example, purified gas or waste gas. The mixture of fuel and gas 8 is supplied through the vertical duct section 9 and swirls within the elbow 12 from the vertical upward flow direction to the horizontal flow direction 26 toward the fuel nozzle 4. When the mixed flow of fuel and gas 8 reaches the vicinity of the deflector device 21, it is deflected by the deflection device 21 towards the side of the duct 11 or the duct wall 28.

[0052] Specifically, the auxiliary gas 23 is discharged from the nozzle outlet 27 of the auxiliary nozzle 24 in a flow direction approximately opposite to the flow direction 26 of the fuel-gas mixture 8 in the center of the duct 11. When the injected auxiliary gas 23 collides with the inflow fuel-gas mixture 8, it effectively deflects the mixture 8 outward, i.e., upward, downward, and to the sides of the duct 11, acting to cause the mixture 8 to flow around the deflection device 21. This is achieved solely by the fluid, i.e., the auxiliary gas 23, and does not require any solid deflectors (structural deflectors), kickers, or impellers within the duct 11.

[0053] The velocity of the discharged auxiliary gas 23 can be selected based on the position of the counterflow nozzle 24 in the duct 11 and its position relative to the outlet 13 of the fuel nozzle 4, the supply capacity of the supply line 29 and the counterflow nozzle 24, the type and quality of fuel used, and operating conditions such that a fuel-rich jet 32 ​​concentrates in the outer region of the duct 11 and reaches the outer region or peripheral nozzle portion 17 of the fuel nozzle 4, while a reduced concentration of the fuel-gas mixture, i.e., a fuel-lean jet 33, flows around the counterflow nozzle 24 and reaches the central nozzle portion 16 of the fuel nozzle 4. This provides a favorable fuel distribution at the fuel nozzle outlet 13 at the inlet to the combustion chamber 6, which greatly enhances the ignition, combustion, and burnout of the fuel in the combustion chamber 6 and provides a large, extended, and stable flame 34 in the combustion chamber 6.

[0054] As shown in Figure 5, a low-pressure zone 36, which serves as an ignition stabilization region, is formed approximately downstream of the central nozzle section 16 of the fuel nozzle 4, between the upper and lower fuel gas flows that substantially flow into the combustion chamber 6 from the peripheral nozzle section 17. Gas and fuel particles are drawn into the low-pressure region 36 from the lower part of the upper fuel gas flow 37, which includes the fuel-rich jet 32, and the upper part of the lower fuel gas flow 38, which also includes the fuel-rich jet 32, and ignited. Some of the high-temperature combustion products formed during ignition are circulated within this low-pressure ignition stabilization zone 36, as indicated by the circulation arrow 39 in the figure, thus stabilizing the ignition. This provides the fuel particles drawn into the region 36 from the upper and lower fuel gas flows 37 and 38 with the ignition energy necessary to ignite them. The fuel-gas ratio within the ignition stabilization zone 36 increases, and the amount of energy required to initiate ignition decreases, further promoting stable ignition.

[0055] As a result, the combustion system 1 achieves improved ignition performance of the burner 3, an increased effective ignition area, and low NOx and CO emissions in the low-load operating range. Low NOx emission levels are achieved by the reducing atmosphere in the internal flame, i.e., the low-pressure zone 36, resulting in effective NOx reduction through the reduction of volatile substances, char, or other fuel particles in this region. NOx emission levels are further reduced by the reduction of the high-oxygen level regions in the outer flame of the ignition area, i.e., zones 37 and 38 in Figure 5. The large ignition area with widely distributed fuel particles promotes complete combustion of the fuel in the flame 34, thereby further reducing CO emissions. The burner 3 has low maintainability because it does not contain wear parts such as structural deflectors (solid deflectors) that receive the mixed flow of fuel and gas in the duct 11. In addition, erosion and wear of the burner 3 hardware can be minimized.

[0056] The combustion system 1 can be modified in various ways. For example, as shown in Figure 5, the secondary air nozzle 14 may be tilted at a constant angle with respect to the axis B of the fuel nozzle 4, or preferably, may be tiltable, in order to allow adjustment of the injection angle of secondary air 15 into the combustion chamber 6. The secondary air tilt allows for further control of the flame 34 and combustion.

[0057] Further optional modifications are shown in Figure 4. As can be seen from the figure, the combustion system 1 may include injection means 22, in particular means configured to change the outlet velocity of the auxiliary gas 23 injected from the nozzle outlet 27 of the counterflow nozzle 24. In one exemplary embodiment, a flow control valve 40 is located in fluid communication with the supply line 29 and can be controlled by a control device (not shown) of the combustion system 1 to adjust the flow rate and velocity of the auxiliary gas 23 supplied to the counterflow nozzle 24 via the supply line 29.

[0058] Alternatively, for example, a gas blower or fan 41 may be provided to draw in gas from a gas supply source or fresh air from the outside and supply it to the supply line 29 as auxiliary gas 23. The gas blower or fan 41 is speed-adjustable, and in a preferred embodiment, its speed is controllable during operation, in order to allow the outlet velocity of the auxiliary gas 23 to be changed by adjusting or controlling the speed of the gas blower or fan 41.

[0059] In another embodiment that can be used as an alternative or additional, the combustion system 1 may include a throttle means 42 configured to modify the flow cross-section of an auxiliary gas nozzle 24 to adjust the velocity of the auxiliary gas 23 being injected. The auxiliary gas nozzle 24 may have a variable opening controlled, for example, by a control device (not shown) during operation, thereby changing the cross-sectional size and, consequently, the velocity of the injected auxiliary gas 23.

[0060] In all these embodiments, changing the velocity of the injected auxiliary gas 23 can achieve the same effect as changing the position and size of the deflection device 21 or any structural deflector (solid deflectors), impeller, or kicker in a conventional system. The velocity of the backflow injected auxiliary gas 23 determines the size and position of the obstruction given to the inflow fuel-gas mixture 8. This makes it easy to control how efficiently the fuel particles or mixture fuel flow are deflected outward from the center of the fuel-gas flow 8. Thus, the combustion system 1 can be adapted to easily accommodate different types and qualities of fuel, including different degrees of pulverization and / or drying of pulverized fuel. For example, the velocity of the injected auxiliary gas 23 can be increased for fuels with an increased ratio of larger fuel particle size and / or higher degree of dryness to provide greater momentum for effectively deflecting and distributing the fuel outward. The velocity of the injected auxiliary gas 23 can be decreased by adjusting it for fuels with a high degree of pulverization, which have an increased fraction of smaller fuel particle size, and for fuel-gas mixtures that do not contain pulverized fuel, which require lower momentum for deflection.

[0061] The rate at which the auxiliary gas 23 is injected can be adjusted according to the burner operating conditions. This rate may be increased during full-load operation when a grinding fuel with a low gas-fuel ratio is supplied to the burner 3 from a grinder or mill, and may be decreased during partial-load operation when the gas-fuel ratio of the grinder is increased. This provides further flexibility in adjusting and optimizing the flow rate of the auxiliary gas 23 in response to various burner operating conditions, including ignition, combustion, and pollutant emission levels.

[0062] As a further modification, in any of the embodiments of the combustion system 1 described above, the injection means 22, in particular the auxiliary gas nozzle 24, may be positioned to be adjustable with respect to its orientation in space. In particular, the injected auxiliary gas nozzle 24 may be positioned to be adjustable such that the nozzle outlet 27 and the injection or discharge angle can be changed or adjusted as needed with respect to at least two of the three orthogonal axes X, Y, and Z, as shown in Figure 4. In particular, adjustment of the nozzle outlet 27 in the YZ plane perpendicular to the axis B of the fuel nozzle 4 is advantageous for adjusting the deflection of the incoming fuel-gas mixture 8 in a desired direction. The elbow 12 preferably concentrates the incoming fuel-gas mixture 8 in the upper region of the duct 11 and deflects a portion of the mixture 8 downward toward the bottom of the duct wall 28. Depending on the boiler conditions, it may also be desirable to deflect the fuel-gas mixture 8 toward the sides of the duct 11. Furthermore, nozzle outlets 27 that are inclined upward on both sides of the duct 11 can further induce swirling motion within the fuel-gas mixture 8. The swirling mixture flow 8 exiting the fuel nozzle outlet 27 can further improve fuel distribution, ignition, and combustion within the combustion chamber 6.

[0063] Another optional embodiment of the combustion system 1 is shown in Figures 6 and 7. Figures 6 and 7 show an enlarged cutout of the burner 3. In this embodiment, the combustion system 1 may further include a baffling means 43 positioned in front of, i.e., upstream of, the nozzle outlet 27 of the auxiliary gas nozzle 24. The baffling means 43 may be dish-shaped or bowl-shaped and include a concave surface 44 facing the direction of the auxiliary gas nozzle outlet 27.

[0064] As can be seen from the detailed view in Figure 7, the concave surface 24 of the baffle means 43 acts to spread the discharged auxiliary gas 23 outward toward the duct wall 28 of the duct 11 during operation, as indicated by the arrow 46 in Figure 7. The diffused auxiliary gas 46 then collides with the fuel-gas mixture flow 8 flowing around the deflector device 21, providing further deflection of the mixture flow 8, which is already deflected by the baffle means 43, thereby enhancing the overall distribution effect on the mixture flow 8. The baffle means 43 may preferably be made of a wear-resistant material.

[0065] Referring to Figures 8 and 9, another embodiment of the combustion system 1 according to the present invention is shown. The combustion system 1 is particularly suited for use as a coal combustion system 1, but other solid or gaseous fuels may also be used as described above. In this exemplary embodiment, the combustion system 1 includes a circular burner 3' which includes a tubular primary duct 47 for supplying a mixed flow 8 of fuel and primary air to the combustion chamber 6. The term “primary air” is commonly used in relation to the type of coal combustion system shown in the figures. The primary air may include any air, gas (high-temperature or low-temperature gas), or mixture of air and gas that can be used for mixing with and burning the fuel. The terms “primary air” and “gas” as used herein are interchangeable. The downstream end 48 of the primary duct 47 defines a fuel nozzle 4. The burner 3' further includes a tubular secondary duct 49 which is arranged concentrically around the primary duct 47 for supplying secondary air 51 to the combustion chamber 6. In the illustrated example, the burner 3' further includes a tubular tertiary duct 52 arranged concentrically around a secondary duct 49 for supplying tertiary air 53 to the combustion chamber 6. The primary duct 47, secondary duct 49, and tertiary duct 52 are all arranged concentrically. The tertiary duct 52 can be omitted if not necessary, but is preferably provided to increase flame expansion and improve the performance of the burner 3' with respect to fuel ignition and combustion.

[0066] As seen in Figures 8 and 9, the deflection device 21 in the burner 3' includes a swirl tube 54 that is positioned to supply auxiliary gas 23 in the direction indicated by arrow 56 in Figure 8 and eject the auxiliary gas 23 into the duct 11. This deflects the incoming fuel-primary air mixture 8 toward the outer region of the primary duct 47 and causes the fuel-primary air mixture 8 to swirl around the longitudinal axis B of the primary duct 47 and the fuel nozzle 4.

[0067] The swirl tube 54 is a closed tube 57 located in the center of the circular burner 3' within the main duct 47, and has a closed downstream end 58. The closed end 58 is located at a distance from the nozzle outlet 27 of the burner 3'. The closed tube 57 includes elongated inclined slots 59 distributed circumferentially around the closed tube 57, extending from the inside to the outside of the closed tube 57 through the wall 61 of the closed tube 57. The through slots 59 are inclined at an angle to the longitudinal direction along the axis B of the closed tube 57 and to a plane perpendicular to the longitudinal direction. The through slots 59 are located near the closed downstream end 58.

[0068] During operation, the auxiliary gas 23 is supplied through a closure pipe 57 and flows toward its closed end 58. The auxiliary gas 23 can be supplied from any suitable air and / or gas source, such as a first, second, or third air supply source or an external air / gas source. The auxiliary gas 23 exits from the inside of the closure pipe 57 through a through-slot 59, is deflected therefrom, and has both radial and axial moving components, as well as a swirling component around the main duct 47 after passing through the through-slot 59. This swirling air 56 collides with the inflow of fuel and air 8, deflecting the mixed flow 8 toward the outer region of the main duct 47, i.e., the duct wall 28, and also induces a swirling motion in the mixed flow 8. In this way, the mixed flow 8 of fuel and primary air receives a rotational impulse and moves away from the closure pipe 57 toward the outer wall 28 of the primary duct 47. This creates a swirling fuel-air mixture 8 flowing into the combustion chamber 6, resulting in a richer fuel concentration in the outer region 17 of the nozzle outlet 27 of the combustor 3' and a richer fuel concentration in the central portion 16. Thus, substantially the same effects as those of the auxiliary gas nozzle 24 in the embodiments of Figures 1 to 7 are achieved, including improved ignition and combustion performance, an expanded combustion zone, a stabilized flame, a fuel-enhanced autobahn, and low NOx and low CO emission levels. To avoid repetition, refer to the description of the effects and benefits described in relation to the embodiments of Figures 1 to 7, which also apply to the combustion system 1 in Figures 8 and 9.

[0069] Referring to Figures 10 and 11, another embodiment of the combustion system 1 having a circular burner 3' according to the present invention is shown. This embodiment substantially corresponds to the embodiment shown in Figures 8 and 9. The description of the embodiments in Figures 8 and 9 also applies to the embodiments in Figures 10 and 11, unless otherwise noted below, so that the same reference numerals indicate the same parts used in both embodiments.

[0070] In the exemplary embodiments of Figures 10 and 11, the circular burner 3'' also includes first, second, and optional third ducts 47, 49, 52 arranged concentrically with respect to each other. Furthermore, the boiler 3' further includes a core air pipe 62 located in the center of the circular burner 3' within a main duct 47 for supplying auxiliary core air 63 to the combustion chamber 6. The swirl pipe 54 is, in the illustrated example, an additional pipe 64 arranged around the core air pipe 62 and sealed to it at its downstream end 66. The pipe 64 includes elongated inclined slots 59 distributed circumferentially around the pipe 64 near the sealed downstream end 66, extending through the walls 61 of the additional pipe 64 at an angle oblique to the longitudinal direction of the additional pipe 64 corresponding to axis B, and in a plane perpendicular to the longitudinal direction. The elongated through slots 59 are identical or substantially similar to the through slots 59 of the burner 3' in the embodiments shown in the figures. The same effect is obtained in 8 and 9. Figure 11 shows the enlarged cut-out section of the additional tube 64 and core air tube 62, with an elongated slope passing through slot 59.

[0071] During operation, auxiliary gas 23 is supplied from a suitable source through an annular space 67 defined between an additional pipe 64 and the core air pipe 62. The auxiliary gas 23 flows through the annular space 67 to a sealed downstream end 66 and out through a through-slot 59 into the main duct 47, where it is deflected both radially and axially and undergoes twisting or swirling around the additional pipe 64. When it collides with the incoming fuel-air or gas mixture 8 flowing through the primary duct 47, the swirling auxiliary gas 56 deflects the fuel-air flow 8 to the outer region of the primary duct 47 and also induces a swirling motion in the mixture 8. In this way, the fuel-air or gas mixture 8 receives a rotational impulse and moves away from the closed pipe 57 and closer to the outer wall 28 of the primary duct 47. As a result, the swirling fuel-air / gas mixture 8 enters the combustion chamber 6, which has a richer fuel concentration than 17 at the center 16 of the nozzle outlet 27 of the burner 3''. As a result, the distribution of fuel-air / gas flow into the combustion chamber 6 is improved, providing a foundation for safe fuel ignition and combustion, proper stabilization of the flame 34, and high-efficiency performance with reduced NOx and CO emissions across the entire operating range, for both full-range and partial-load operation.

[0072] Figure 12 shows a top view of a boiler 2 having a tangential arrangement of burners 3 (or 3' or 3') according to an exemplary application of the present invention. A mixture of fuel and air 8 is injected tangentially to a virtual circle 69 from burners 3 (3', 3'') located on the boiler wall 68 surrounding the combustion chamber 6, forming a vertical vortex at the center of the combustion chamber 6. Such a configuration can be advantageously used, for example, in a lignite combustion boiler, and the burners 3, 3' and 3' of the present invention are particularly well suited to this application. Alternatively, burners 3 (3', 3'') can also be positioned in the corners of the combustion chamber 6. The advantages achieved by burners 3, 3' and 3' result in corresponding advantages and improvements in the overall performance and efficiency of the lignite combustion boiler.

[0073] Figure 13 shows a front view of a boiler 2 having a front flame arrangement of burners according to an exemplary embodiment of the present invention. Any of the burners 3, 3', and 3'' described above can be advantageously used in the boiler 2 shown in the figure. Figure 13 also shows the direction of fuel swirling of the fuel-primary air mixture flow 8 exiting the fuel nozzles 4 of burner 3(3', 3'') and flowing into the combustion chamber 6 with circular arrows 71. In the illustrated example, to improve the mixing of fuel and air entering the combustion zone of the combustion chamber 6, deflection devices 21, such as auxiliary gas nozzles 24 or swirl tubes 54, can be arranged to induce the swirling motion shown by arrows 71. In particular, adjacent burners 3(3', 3'') can be selectively arranged to induce swirling in the same direction 71a or in opposite directions 71b, not only to promote the mixing of air and fuel but also to avoid the occurrence of hot spots in specific zones of the combustion chamber 6.

[0074] Burners 3 (3', 3'') may be positioned to achieve a desired swirling pattern of the fuel-airflow provided in the combustion chamber 6 to improve performance depending on the operating conditions. Conveniently, this can be achieved using only auxiliary gas 23 injected from auxiliary gas nozzles 24 or swirl pipes 54, without requiring complex hardware structures to swirl the fuel-airflow within the burners. Furthermore, the velocity of the injected auxiliary gas 23 can be varied to respond appropriately to changes in fuel type or operating conditions.

[0075] A combustion system and method for power generation boilers is provided in particular. The combustion system 1 comprises burners 3, 3', 3' that supply a mixture 8 of fuel and primary air or gas to a combustion chamber 6 via at least one fuel nozzle 4, ducts 11, 47 that are in fluid communication with at least one fuel nozzle 4 for guiding the mixture 8 of fuel and primary air or gas to at least one fuel nozzle 4, and a deflector device 21 positioned in the ducts 11, 47 upstream of the at least one fuel nozzle 4 to deflect the incoming mixture 8 of fuel and primary air or gas. The deflector device 21 comprises an injection means 22 that injects an auxiliary gas 23 into the ducts 11, 47 to deflect the incoming mixture 8 of fuel and primary air or gas from the center outwards, thereby increasing the concentration of the mixture 8 of fuel and primary air or gas in the outer region 17 of the fuel nozzle 4 and decreasing the concentration of the mixture 8 of fuel and primary air or gas in the central portion 16 of the fuel nozzle 4. [Explanation of symbols]

[0076] 1. Combustion System 2 Boilers 3 burners 4 Fuel nozzles 6 Combustion chamber 7 Duct System 8 Mixed flow 9. First vertical duct section 11. Second duct section 12 Elbow 13 Nozzle outlet 14. Secondary air nozzle 15 Secondary air 16. Central nozzle section 17 Peripheral nozzle section 18 Peripheral fuel nozzle channels 19 Core air tubes 21 Deflector device 22 Ejection means 23 Auxiliary gas 24 Auxiliary gas nozzles 26 Flow direction 27 Nozzle outlet 28 Duct wall 29 supply lines 31 Shielding device 32 Fuel-rich jet 33 Fuel Lean Jet 34 Flames 36 Low pressure region 37 Upper fuel gas flow 38 Lower fuel gas flow 39 Circular Arrow 41. Gas blowers, fans 42 Throttle mechanism 43 Baffling methods 44 Concave 46 Diffusion aid gases 47 Primary duct 48 Downstream end 49 Secondary duct 51 Secondary air 52. Tertiary duct 53 Tertiary air 54 Swivel pipe 56 Arrows 57 Closed tube 58 Downstream end 59 Penetrating Slots 61 Wall 62 Core Air Pipe 63 Auxiliary core air 64 Additional tubes 66 Downstream end 67 Circular Space 68 Boiler wall 69 virtual yen 71 Arrow

Claims

1. In particular, combustion systems for boilers, At least one burner (3, 3', 3'') supplies a mixture of fuel and gas (8) to a combustion chamber (6) through at least one fuel nozzle (4), A duct (11, 47) that is in fluid communication with at least one fuel nozzle (4) and guides a mixed flow of fuel and gas to at least one fuel nozzle (4), A deflector device (21) is positioned in a duct (11, 47) upstream of at least one fuel nozzle (4) to deflect the incoming mixed flow of fuel and gas, Equipped with, The deflector device (21) includes an injection means (22) that injects an auxiliary gas (23) into the duct (11, 47) to deflect the incoming fuel-gas mixture flow toward the outer region including the upper and lower parts of the duct (11, 47). The injection means (22) includes an auxiliary gas nozzle (24) that protrudes into the duct (11, 47), The combustion system includes an auxiliary gas nozzle (24) having a nozzle outlet (27) directed upstream of the fuel and gas.

2. The combustion system according to claim 1, wherein the injection means (22) is positioned in correspondence with the fuel nozzle (4) and is configured to deflect the incoming fuel-gas mixture so as to increase the concentration of the fuel-gas mixture in the outer region (17) of the fuel nozzle (4) and decrease the concentration of the fuel-gas mixture in the central portion (16) of the fuel nozzle (4).

3. The combustion system according to claim 1 or 2, wherein the fuel is a pulverized fuel, particularly pulverized coal, or a fuel gas mixture obtained from refined gas.

4. The combustion system according to claim 1, wherein the auxiliary gas nozzle (24) is installed on the horizontal duct portion (11) on the centerline of the duct portion (11) of the duct (7) which is directly connected to the fuel nozzle (4).

5. The combustion system according to claim 1 or 4, further comprising means (40, 41, 42) configured to change the outlet velocity of the auxiliary gas (23) injected from the nozzle outlet (27) of the auxiliary gas nozzle (24).

6. The combustion system according to claim 5, wherein the auxiliary gas nozzle (24) includes a throttle means (42) that changes the flow cross-section of the auxiliary gas nozzle (24) to adjust the speed of the injected auxiliary gas (23).

7. In particular, combustion systems for boilers, A mixture of fuel and gas (8) is passed through at least one fuel nozzle (4) to the combustion chamber (6). At least one burner (3, 3', 3'') to supply power, It is in fluid communication with at least one fuel nozzle (4), and at least one fuel nozzle (4) A duct (11, 47) guides a mixed flow of fuel and gas, At least one fuel nozzle (4) is located in the duct (11, 47) upstream of the fuel and a deflector device (21) that deflects the incoming mixed flow of gas, Equipped with, The deflector device (21) injects auxiliary gas (23) into the ducts (11, 47), The incoming mixture of fuel and gas is deflected from the center of the duct (11, 47) outwards. It is equipped with a spraying means (22), The injection means (22) includes at least one auxiliary gas nozzle (24) configured to receive auxiliary gas (23) and inject the auxiliary gas (23) in the opposite direction to the flow direction (26) of the fuel-gas mixture flow (8), or at least at an oblique angle. A combustion system in which at least one auxiliary gas nozzle (24) is adjustable in terms of its orientation in space to change the injection angle of the auxiliary gas (23).

8. The combustion system according to any one of claims 1, 4 to 7, further comprising a shielding device (31) positioned upstream of and in close proximity to the supply line (29) that supplies auxiliary gas to the auxiliary gas nozzle (24) within the duct (11), which shields the supply line (24) from the inflow mixed flow (8) of fuel and gas.

9. The combustion system according to any one of claims 1, 4 to 8, further comprising a baffle means (43) positioned in front of the nozzle outlet (27) of the auxiliary gas nozzle (24), having a concave surface (44) facing the direction of the auxiliary gas nozzle outlet (27), and for diffusing the injected auxiliary gas (23) on the side of the duct (11).

10. A method of combustion, The steps include supplying a mixture of fuel and gas (8) from at least one burner (3, 3', 3'') to the combustion chamber (6) via a duct (11, 47) through at least one fuel nozzle (4), The steps include: deflecting the incoming fuel and gas mixture (8) in the duct (11, 47) by injecting auxiliary gas (23) into the duct (22, 47) in a direction toward the outer region including the upper and lower parts from the center of the duct (11, 47), thereby increasing the concentration of the fuel and gas mixture (8) in the outer region (17) of the fuel nozzle (4) and decreasing the concentration of the fuel and gas mixture (8) in the central part (16) of the fuel nozzle (4) using an injection means (22); Includes, The deflection of the fuel and gas inflow mixture flow (8) in the duct (11) is This is performed using an auxiliary gas nozzle (24) that receives the auxiliary gas (23) and injects the auxiliary gas (23) in the reverse direction, at least at an oblique angle to the flow direction (26) of the fuel-gas mixture flow (8) in the duct (11). The auxiliary gas nozzle (24) protrudes into the duct (11, 47).

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