A wall-mounted giant ring-shaped direct current pulverized coal burner

Abstract

The present invention discloses a wall-type giant ring-shaped direct current pulverized coal burner, comprising burner nozzles arranged on the four side walls of the boiler. The burner nozzles on the four side walls form a wall-type tangential circular combustion mode in the furnace. The burner nozzles on each side wall are composed of multiple small nozzles arranged in a ring shape to form a giant ring-shaped combined nozzle. In the present invention, multiple small nozzles are arranged in a ring shape on each side wall to form a giant ring-shaped combined nozzle. The giant ring-shaped combined nozzles on the four side walls can form a wall-type tangential circular combustion mode in the furnace. The multiple jets in the giant ring-shaped combined nozzle can effectively enhance the stiffness of each jet through mutual entrainment and mutual support between the fire-facing side and the back-fire-facing side jets, thereby reducing the flame wall brushing phenomenon caused by the rapid decay of the jet stiffness, and fundamentally reducing the risk of coking and high-temperature corrosion on the heating surface of the furnace.

Description

Technical Field

[0001] The invention belongs to the technical field of boiler burners, and in particular relates to a wall-arranged direct current pulverized coal burner. Background Art

[0002] The current layouts of DC pulverized coal burners in large power plant pulverized coal boilers primarily include four-corner tangential-circle and wall-mounted tangential-circle arrangements. In both arrangements, single-nozzle DC burners are arranged in a simple linear pattern along the height of the furnace wall or at the four corners. For example, Chinese invention patent CN102494333B discloses a single-fireball four-corner DC burner burning anthracite, and Chinese utility model patent CN204358718U discloses a wall-mounted tangential-circle-fired pulverized coal boiler burner nozzle arrangement.

[0003] The existing arrangement essentially relies on the jet stiffness of a single burner to resist the impact of the powerful furnace synthetic rotating main airflow (or upstream synthetic airflow). At the same time, due to the small gap between the linearly arranged single nozzles, the air supply conditions on both the downstream and horizontal sides of the jet are poor, further aggravating the horizontal deflection of the jet, and in severe cases causing the jet to directly brush the wall. To this end, under the condition that the linear arrangement within the group remains unchanged, traditional improvement measures include: grouping the burner nozzles along the vertical height direction of the furnace, increasing the distance between groups, and improving the insufficient air supply on the back-fire side of the burner group; adopting a large cut-angle arrangement to improve the air supply conditions on the back-fire side of the jet; and arranging the burners on the wall to keep the burners away from the downstream wall and better improve the air supply conditions on the back-fire side of the jet. However, the above-mentioned improvement measures have limited effects and have failed to completely solve the problem that the single nozzle jet cannot resist the strong upstream flow impact and is strongly deflected, resulting in the actual flame cutting circle in the furnace being difficult to control, and the jet brushing the wall often occurs, causing major accidents such as boiler coking, high-temperature corrosion, flue gas temperature deviation, over-temperature pipe burst, and unstable combustion. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a new type of wall-mounted giant ring-type direct current pulverized coal burner, which is used to solve the problems of jet deflection and flame brushing on the wall caused by insufficient jet rigidity in existing boilers, as well as the coking and high-temperature corrosion of the furnace heating surface caused by this.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solution: a wall-arranged giant ring-shaped direct current pulverized coal burner, including burner nozzles arranged on the furnace walls on four sides of the boiler. The burner nozzles on the four sides of the furnace walls form a wall-type cut-circle combustion mode in the furnace. The burner nozzles on each side of the furnace wall are composed of multiple small nozzles arranged in a ring shape to form a giant ring-shaped combined nozzle.

[0006] Preferably, the small nozzles constituting the giant ring-shaped combined nozzle are arranged along a circular ring, an elliptical ring or a rectangular ring.

[0007] Preferably, on each side of the furnace wall corresponding to the main combustion area of ​​the furnace, multiple groups of giant ring-shaped combined nozzles are provided along the height direction.

[0008] Preferably, on the furnace wall corresponding to the main combustion area of ​​the furnace, the giant ring-shaped combined nozzle is composed of a plurality of small primary air nozzles and a plurality of small secondary air nozzles arranged in a ring shape.

[0009] More preferably, the small primary air nozzles and the small secondary air nozzles are arranged in a ring shape with intervals between them.

[0010] More preferably, the small primary air nozzles and the small secondary air nozzles are arranged in pairs or threes on the same circular ring, elliptical ring or rectangular ring.

[0011] More preferably, the small primary air nozzles and the small secondary air nozzles are arranged on two concentric circular rings, elliptical rings or rectangular rings respectively.

[0012] More preferably, the small primary air nozzles and the small secondary air nozzles are respectively arranged on two circular rings of equal diameter and non-concentricity.

[0013] Preferably, on the furnace wall corresponding to the burnout area in the upper part of the furnace, the giant ring-shaped combined nozzle is composed of a plurality of small burnout air nozzles arranged in a ring shape.

[0014] Preferably, the small nozzle installed on the furnace wall can be adjusted up, down, left and right.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] In the present invention, multiple small nozzles are arranged in a ring on each side of the furnace wall, forming a giant ring-shaped composite nozzle. These four-sided giant ring-shaped composite nozzles can form a wall-shaped tangential combustion pattern within the furnace. The multiple jets in this giant ring-shaped composite nozzle effectively enhance the rigidity of each jet through mutual entrainment and mutual support between the fire-facing and fire-removing jets. This reduces the flame wall-brushing phenomenon caused by the rapid decay of jet rigidity, fundamentally reducing the risk of coking and high-temperature corrosion on the furnace heating surface.

[0017] Different from the primary action mode of existing boilers in which the jet of a single burner nozzle directly interacts with the main airflow in the furnace, the present invention adopts a secondary action mode, that is, firstly, multiple single burner nozzles are combined into a giant ring-shaped combined nozzle, and then the jet of the giant ring-shaped combined nozzle interacts with the main airflow in the furnace. As an intermediate between a single small nozzle and the entire furnace burner, the giant annular jet of each giant annular combination nozzle has a strong synthetic rigidity, has a resistance to the lateral impact of the overall rotating airflow of the furnace, and has a stronger restraining effect on the main rotating airflow (tangential circle) of the furnace. It not only makes the jets of the giant annular combination nozzle and its internal small nozzles have a strong anti-deflection ability, but also better overcomes the huge problem that the boiler furnace combustion aerodynamic conditions are increasingly difficult to organize as the capacity increases, forming a stable and reasonable furnace actual tangential circle and combustion temperature gradient distribution, and completely overcomes the problem of poor air supply conditions on both sides brought about by the existing burner jet in the vertical plane, thereby effectively eliminating the flame brushing wall phenomenon, and fundamentally solving the problem of coking and high-temperature corrosion on the heating surface of the large-capacity boiler furnace. In addition, the present invention can also improve the combustion uniformity in the furnace and increase the combustion temperature, which is conducive to promoting the stable combustion and ignition of inferior coal, and at the same time is conducive to reducing the generation of nitrogen oxides. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of a boiler using the wall-mounted giant ring-shaped direct current pulverized coal burner of the present invention.

[0019] Figure 2 Schematic diagram of a giant annular combined nozzle composed of small nozzles with square end sections.

[0020] Figure 3 Schematic diagram of a giant annular combined nozzle composed of small nozzles with circular end cross-sections.

[0021] Figure 4 Schematic diagram of a giant annular combined nozzle composed of small nozzles with rectangular end cross-sections.

[0022] Figure 5 This is a schematic diagram of a giant ring-shaped combined nozzle composed of small nozzles arranged in an elliptical ring.

[0023] Figure 6 This is a schematic diagram of a giant ring-shaped combined nozzle composed of small nozzles arranged along a rectangular ring.

[0024] Figure 7 This is a schematic diagram of the primary air small nozzles and the secondary air small nozzles arranged on two concentric rings.

[0025] Figure 8 This is a schematic diagram of the primary air small nozzles and the secondary air small nozzles arranged on two equal-diameter non-concentric circular rings.

[0026] Figure 9 This is a schematic diagram showing that the primary air small nozzles and the secondary air small nozzles are arranged in pairs.

[0027] Figure 10 This is a schematic diagram of the primary air small nozzles and the secondary air small nozzles arranged in a three-by-three manner.

[0028] Figure 11 The figure is a comparison diagram of velocity distribution in the furnace of a boiler using a traditional burner and a burner of the present invention.

[0029] Figure 12 The figure is a comparison of the temperature distribution in the furnace of a boiler using a traditional burner and the burner of the present invention. DETAILED DESCRIPTION

[0030] The following is a further detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention, and are not intended to limit the present invention.

[0031] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limiting the present invention.

[0032] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0033] like Figure 1 As shown, the present invention discloses a wall-mounted giant ring-shaped direct current pulverized coal burner, comprising burner nozzles arranged on the four side walls 100 of a boiler. These burner nozzles on the four side walls 100 can form a wall-shaped tangential combustion pattern within the furnace. Unlike the prior art, the burner nozzles on each side wall 100 are composed of multiple small nozzles arranged in a ring, forming giant ring-shaped combined nozzles 10, 20, 30, and 40. These giant ring-shaped combined nozzles 10, 20, 30, and 40 are distributed at different heights on the furnace wall 100. Four giant ring-shaped combined nozzles (e.g., four giant ring-shaped combined nozzles 10) corresponding to the same height on the four side walls 100 are offset from the centerline of the furnace wall 100 by a certain distance. The jets ejected from these nozzles interact within the furnace, forming a suitable rotating combustion tangential circle, thus achieving a wall-shaped tangential combustion pattern.

[0034] The distance between the installation center of the giant ring-shaped combination nozzle and its adjacent wall should generally be greater than 0.7 times its equivalent diameter, so that the small nozzle on the back-fire side is at a certain distance from the adjacent wall to prevent the jet on the back-fire side of the giant ring-shaped combination nozzle from being too close to the adjacent wall and sticking to the wall.

[0035] like Figure 2 、 3 As shown in Figures 4 and 5, the end sections of the small nozzles 1 and 2 constituting the giant annular combined nozzle can be square, circular, rectangular, or C-shaped as disclosed in Chinese invention patent CN104676585B.

[0036] like Figure 4 、 5 As shown in , 6, the small nozzles 1 and 2 constituting the giant ring type combined nozzle can be arranged along a circular ring (such as Figure 4 As shown), elliptical ring (as Figure 5 as shown) or rectangular ring (as Figure 6 shown) arrangement.

[0037] like Figure 1 As shown, the giant annular combination nozzles on the furnace wall 100 include multiple groups of giant annular combination nozzles 10, 20 and 30 corresponding to the main combustion area of ​​the furnace, and a giant annular combination nozzle 40 corresponding to the burnout area at the upper part of the furnace. Among them, the giant annular combination nozzles 40 corresponding to the burnout area of ​​the furnace are composed of multiple small burnout air nozzles arranged in a ring shape. On the furnace wall corresponding to the main combustion area of ​​the furnace, as shown in FIG. Figure 2-10 As shown, the giant annular combined nozzle is composed of a plurality of primary air small nozzles 1 and a plurality of secondary air small nozzles 2 arranged in an annular shape.

[0038] In a preferred embodiment, each giant annular combination nozzle 10, 20, and 30 in the main combustion zone comprises six small primary air nozzles 1 and six small secondary air nozzles 2. The giant annular combination nozzle 40 in the burnout zone comprises 12 small burnout air nozzles. These nozzles have a square end cross-section, with the primary air nozzle 1 having a side length of 0.36m, the secondary air nozzle 2 having a side length of 0.44m, and the burnout air nozzle having a side length of 0.36m. The equivalent diameter of the giant annular combination nozzle is 3.6m.

[0039] The area of ​​the cross section at the end of the small primary air nozzle 1 may be smaller than, equal to, or larger than the area of ​​the cross section at the end of the small secondary air nozzle 2.

[0040] like Figure 2-6 As shown, the small primary air nozzles 1 and the small secondary air nozzles 2 are arranged in a ring at intervals from each other, that is, the small primary air nozzles 1 and the small secondary air nozzles 2 are alternately arranged on the same circular ring, elliptical ring or rectangular ring to enhance the interaction between the fuel jet and the air jet and promote the mixing process of the fuel and air.

[0041] like Figure 7As shown, the primary air small nozzle 1 and the secondary air small nozzle 2 are arranged on two concentric rings to form a giant ring type combined nozzle. Of course, the primary air small nozzle 1 and the secondary air small nozzle 2 can also be arranged on two concentric elliptical rings or rectangular rings to form a giant ring type combined nozzle. Figure 7 As shown, the primary air small nozzles 1 are arranged on the outer large ring, and the secondary air small nozzles 2 are arranged on the inner small ring, but the opposite may also be true.

[0042] like Figure 8 As shown, the small primary air nozzle 1 and the small secondary air nozzle 2 can also be arranged on two circular rings of equal diameter and different centers to form a giant ring-shaped combined nozzle.

[0043] like Figure 9 As shown, the small primary air nozzles 1 and the small secondary air nozzles 2 can also be arranged in pairs on the same circular ring, elliptical ring or rectangular ring, that is, two adjacent small primary air nozzles 1 and two adjacent small secondary air nozzles 2 are alternately arranged along the ring to form a giant ring-shaped combined nozzle.

[0044] like Figure 10 As shown, the small primary air nozzles 1 and the small secondary air nozzles 2 can also be arranged in a three-by-three manner on the same circular ring, elliptical ring or rectangular ring, that is, three adjacent small primary air nozzles 1 and three adjacent small secondary air nozzles 2 are alternately arranged along the ring to form a giant ring-shaped combined nozzle.

[0045] The total number of primary air small nozzles and secondary air small nozzles in each giant ring-shaped combination nozzle should be no less than 5, and the number should increase as the boiler capacity increases; the power of a single primary air small nozzle should be no less than 3-5MW. The diameter or equivalent diameter of each giant ring-shaped combination nozzle should be no less than 1m, and increase as the boiler capacity increases. The above-mentioned equivalent diameter refers to the diameter of a circle with the same area as the ring. For giant ring-shaped combination nozzles with small nozzles arranged along two rings, the equivalent diameter refers to the average of the equivalent diameters of the two rings.

[0046] Preferably, for ease of installation, the small nozzles within the giant annular combination nozzle are mounted perpendicular to the furnace wall. This reduces sensitivity to installation angle compared to existing tangentially-shaped boilers. However, the small nozzles can be adjusted up, down, left, and right. That is, the angles between the primary and secondary air nozzles and the wall described in this invention can be adjusted up, down, left, and right according to operational requirements, allowing for control of the actual tangential circle size and adjustment of the flame center position.

[0047] The inventors conducted computational fluid dynamics (CFD) numerical simulations on a tangential pulverized coal boiler using a traditional wall-type burner arrangement and a pulverized coal boiler using the giant ring-type direct current pulverized coal burner described in the present invention to analyze the flow and combustion differences under the two schemes. Figure 11-12The calculation results are given, where Figure 11 Velocity cloud diagrams of cross sections at different heights in the furnace under two burner layout schemes. Figure 12 The temperature field cloud diagram of the longitudinal mid-section of the furnace under two burner layout schemes.

[0048] from Figure 11 As can be seen, compared to boilers using conventional direct current burners with a wall-type tangential circular arrangement, boilers using the burners of this invention achieve a more effectively formed tangential flow circle within the furnace, a smaller high-velocity zone near the wall, and significantly reduced jet wall brushing. This fundamentally reduces the coking and high-temperature corrosion problems on the furnace heating surfaces caused by jet wall brushing, thereby improving boiler operational reliability.

[0049] from Figure 12 It can be seen that boilers using the burner of the present invention achieve significantly higher combustion temperatures within the furnace, demonstrating that this solution also facilitates pulverized coal combustion and heat release, thereby improving boiler efficiency. Furthermore, compared to traditional wall-mounted tangentially-circular burners, boilers using the burner of the present invention have a smaller low-temperature zone at the center of the furnace. This demonstrates that the present invention transforms traditional near-wall annular flame combustion into more uniform volumetric combustion, thereby improving combustion uniformity within the furnace.

[0050] In the present invention, the mutual entrainment of multiple jets within the giant annular combined nozzle prevents individual jets from dispersing into the external space, thereby enhancing overall jet rigidity. Furthermore, the rotating flue gas flow within the furnace and the deflected upstream jet primarily impact the giant annular combined nozzle's fire-facing jet, while the jet away from the fire, protected from direct impact, maintains relatively strong jet rigidity. Conversely, the stiffer jet away from the fire supports the potentially deflected fire-facing jet, effectively preventing significant deflection of the fire-facing jet.

[0051] The giant ring-shaped direct current pulverized coal burner provided by the present invention is particularly suitable for the design of new boilers with large capacity and large furnace size of 200MW and above and the transformation of existing boilers. The giant ring-shaped direct current pulverized coal burner with a wall arrangement can significantly improve the various problems such as jet brushing caused by insufficient jet stiffness in large-capacity boilers and the coking of the heating surface and high-temperature corrosion caused by this, and can make the boiler run more safely and stably. At the same time, it is conducive to controlling the generation of combustion nitrogen oxides. In summary, the present invention can effectively overcome the defects in the prior art and improve the safety and stability of boiler operation, and therefore has a high industrial application value.

[0052] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A wall-mounted giant ring-shaped direct current pulverized coal burner, comprising burner nozzles arranged on the four side walls of the boiler, the burner nozzles on the four side walls forming a wall-type tangential circular combustion mode in the furnace, characterized by: The burner nozzles on each side of the furnace wall are composed of multiple small nozzles arranged in a ring shape to form a giant ring-shaped combined nozzle.

2. The giant ring type direct current pulverized coal burner according to claim 1, characterized in that: The small nozzles that constitute the giant ring-shaped combined nozzle are arranged along a circular ring, an elliptical ring or a rectangular ring.

3. The giant ring type DC pulverized coal burner according to claim 1, characterized in that: On each side of the furnace wall corresponding to the main combustion area of ​​the furnace, multiple groups of giant ring-shaped combined nozzles are provided along the height direction.

4. The giant ring type direct current pulverized coal burner according to claim 1, characterized in that: On the furnace wall corresponding to the main combustion area of ​​the furnace, the giant ring-shaped combined nozzle is composed of multiple small primary air nozzles and multiple small secondary air nozzles arranged in a ring shape.

5. The giant ring type direct current pulverized coal burner according to claim 4, characterized in that: The primary air small nozzles and the secondary air small nozzles are arranged in a ring shape at intervals.

6. The giant ring type direct current pulverized coal burner according to claim 4, characterized in that: The small primary air nozzles and the small secondary air nozzles are arranged in pairs or threes on the same circular ring, elliptical ring or rectangular ring.

7. The giant ring type direct current pulverized coal burner according to claim 4, characterized in that: The small primary air nozzles and the small secondary air nozzles are respectively arranged on two concentric circular rings, elliptical rings or rectangular rings.

8. The giant ring type direct current pulverized coal burner according to claim 4, characterized in that: The primary air small nozzles and the secondary air small nozzles are respectively arranged on two circular rings with equal diameters and different centers.

9. The giant ring type direct current pulverized coal burner according to claim 1, characterized in that: On the furnace wall corresponding to the burnout area at the upper part of the furnace, the giant ring-shaped combined nozzle is composed of multiple small burnout air nozzles arranged in a ring shape.

10. The giant ring type direct current pulverized coal burner according to claim 1, characterized in that: The small nozzle installed on the furnace wall can be adjusted up, down, left and right.

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