A tangential firing system for a tangentially fired boiler

Abstract

The application discloses a cyclone combustion system of a wing wall furnace boiler, wherein the lower furnace, the main combustion area furnace and the upper furnace all comprise a front wall, a right side wall, a back wall and a left side wall; the front wall, the right side wall, the back wall and the left side wall of the main combustion area furnace are all provided with inclined wing walls between two adjacent sides; each of the four wing walls is provided with a wind distribution chamber; each of the four wind distribution chambers is provided with a burnout air device and two or more layers of cyclone pulverized coal burners from top to bottom; the axes of the burner nozzles of the cyclone pulverized coal burners of the same layer in the four wind distribution chambers are arranged in a diagonal line in pairs; and the cyclone pulverized coal burners of the same layer in the four wind distribution chambers are all connected with the same coal mill; the application can improve the self-stable combustion capacity, the uniformity of the airflow in the furnace and the flame fullness, avoid the flame brushing the wall, realize the good combustion air power flow field organization in the furnace, precisely control the smoke temperature deviation, ensure the safe operation of the large-capacity high-parameter boiler and better meet the high-index requirement of the new generation of coal power technology.

Description

Technical Field

[0001] This invention relates to a swirl combustion system for a boiler, and more particularly to a swirl combustion system for a boiler with a wing-walled furnace. Background Technology

[0002] To adapt to the development of new power systems, the next generation of coal-fired power plants needs to further expand the technical indicator system of coal-fired power plants, focusing on aspects such as "clean and carbon reduction, safety and reliability, efficient regulation and intelligent operation," which places higher demands on boiler performance.

[0003] Among large coal-fired boilers, the most widely used types include tangential combustion boilers, wall-mounted opposed-flow combustion boilers, and W-type flame combustion boilers. Tangential combustion boilers, equipped with once-through burners, rely on the interaction of combustion at the four corners to organize the aerodynamic field within the furnace, creating a rotating airflow to enhance combustion. However, this rotating airflow can lead to residual rotating flue gas at the furnace outlet, causing large temperature deviations and flow field organization risks. This can result in problems such as pulverized coal particles brushing against the walls and high-temperature corrosion. Furthermore, the rising airflow encounters significant resistance at the four 90° corners, creating a "corner effect" that affects the uniformity of airflow and flame coverage within the furnace. Additionally, the once-through burner's combustion stability is relatively weak due to burner characteristics. Wall-mounted opposed-flow combustion boilers, equipped with swirl burners, offer strong self-stabilizing combustion capabilities. However, large opposed-flow combustion boilers have a large width-to-depth ratio. When the furnace width is large, factors such as pulverized coal deviation, air distribution deviation, and steam-water flow can cause large temperature deviations in the flue gas on both sides of the walls, which is detrimental to precise control of large-capacity, high-parameter processes. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned shortcomings of the prior art by providing a swirl combustion system for a wing-walled furnace boiler. This system can improve self-stabilizing combustion capability, uniformity of airflow within the furnace, and flame coverage, while preventing flame from brushing against the furnace walls. It also achieves a good combustion aerodynamic flow field organization within the furnace, precisely controls flue gas temperature deviation, ensures the safe operation of large-capacity, high-parameter boilers, and better meets the high-indicator requirements of next-generation coal-fired power technology.

[0005] To achieve the above objectives, the present invention provides a swirl combustion system for a wing-walled furnace boiler, wherein the lower furnace, the main combustion zone furnace, and the upper furnace each include a front wall, a right side wall, a rear wall, and a left side wall; characterized in that: inclined wing walls are provided between the adjacent sides of the front wall, right side wall, rear wall, and left side wall of the main combustion zone furnace, and the upper and lower ends of the wing walls are connected to the upper and lower furnace corners respectively through triangular upper and lower transition zones; each of the four wing walls is provided with an air distribution chamber, and each of the four air distribution chambers is provided with a burnout air device and two or more layers of swirl pulverized coal burners from top to bottom; the nozzle axes of each swirl pulverized coal burner in the same layer of the four air distribution chambers are arranged diagonally in pairs; each swirl pulverized coal burner in the same layer of the four air distribution chambers is connected to the same coal mill; and each swirl pulverized coal burner in different layers corresponds to a different coal mill.

[0006] This invention creates an octagonal furnace by adding wing walls at the four corners of the main combustion zone. Multiple layers of swirling pulverized coal burners are installed in the air distribution chambers on the wing walls, enhancing self-stabilizing combustion capabilities. The nozzle axes of each swirling pulverized coal burner in the same layer of the four air distribution chambers are arranged diagonally in pairs, avoiding both tangential and simple opposing combustion methods. This avoids risks such as residual rotating flue gas at the furnace outlet, large temperature deviations in the outlet flue gas, and deviations in the flow field organization. This results in more uniform airflow within the furnace, with combustion unaffected by the furnace boundary and the flames and airflow from other burners, leading to a better independent flame shape. The combustion flame is more uniform, with less flame interference and fluctuation, resulting in better flame stability. Simultaneously, it avoids flame wall brushing, achieving excellent combustion aerodynamic flow field organization within the furnace, precisely controlling flue gas temperature deviations, and ensuring the safe operation of large-capacity, high-parameter boilers. As a further improvement of the present invention, the burnout air device includes two or more layers, with two or more burnout air nozzles in each layer; the multi-dimensional burnout air is arranged on the wing wall, which can realize the full coverage of the burnout air in the furnace cross section, enhance the fullness and coverage of the burnout air in the furnace, control the uniformity of the rising airflow in the burner area, and significantly reduce NOx emissions and flue gas temperature deviation. As a further improvement of the present invention, the distance between the front wall and the rear wall is b, and the distance between the right wall and the left wall is a, with the ratio of a to b being 0.95-1.05; the width L of each wing wall is 0.2-0.3 times (a+b) / 2; this furnace width-to-depth ratio can better construct large-angle θ and large-scale wing wall structures, which is more conducive to controlling the uniformity of the combustion aerodynamic field in the furnace. The wing walls of this width create conditions for independent combustion of the self-stabilized swirl burner. Combustion is less affected by the spatial furnace boundary and the flame and airflow of other burners, resulting in better independent combustion flame morphology. The combustion flame in the furnace is more uniform, with less flame interference and fluctuation, and better combustion stability. As a further improvement of the present invention, the angle θ between each wing wall and the front wall, right side wall, rear wall, or left side wall is an obtuse angle and preferably 135°; it has the best effect in eliminating the corner effect, resulting in better flame filling in the furnace and more uniform airflow in the large space of the furnace. As a further improvement of the present invention, each layer of swirl pulverized coal burner includes an upper burner and a lower burner; the layered burners help to improve the uniformity of flue gas temperature in the furnace. In summary, this invention can improve self-stabilizing combustion capability, uniformity of airflow in the furnace and flame coverage, and avoid flame brushing against the walls, thereby achieving good combustion aerodynamic flow field organization in the furnace, accurately controlling flue gas temperature deviation, ensuring the safe operation of large-capacity, high-parameter boilers, and better meeting the high-indicator requirements of next-generation coal-fired power technology. Attached Figure Description

[0007] Figure 1 This is a perspective view of an embodiment of the present invention.

[0008] Figure 2 This is a front view of an embodiment of the present invention.

[0009] Figure 3 This is a left view of an embodiment of the present invention.

[0010] Figure 4 for Figure 2 AA sectional view.

[0011] Figure 5 for Figure 2 BB cross-sectional view.

[0012] Figure 6 This is a structural diagram of a coal mill and its swirl coal burner in an embodiment of the present invention. Detailed Implementation

[0013] The invention will be further described below with reference to the accompanying drawings.

[0014] like Figures 1 to 6As shown, this embodiment of a swirl combustion system for a wing-walled furnace boiler includes a lower furnace 1, a main combustion zone furnace 2, and an upper furnace 3, each comprising a front wall, a right side wall, a rear wall, and a left side wall. Inclined wing walls 8 are provided between adjacent sides of the front wall 4, right side wall 7, rear wall 6, and left side wall 5 of the main combustion zone furnace 2. The upper and lower ends of the wing walls 8 are connected to the corners of the upper furnace 3 and lower furnace 1 via triangular upper transition zones 9 and lower transition zones 10, respectively. The distance between the front wall 4 and the rear wall 6 is b, and the distance between the right side wall 7 and the left side wall 5 is a, with the ratio of a to b being 0.95-1.05. The width L of each wing wall 8 is 0.2-0.3 times (a+b) / 2. The angle θ between the wing wall 8 and the front wall, right wall, rear wall, or left wall is 135°. Each of the four wing walls 8 is equipped with an air distribution chamber 11. Each of the four air distribution chambers 11 is equipped with a burnout air device and six layers of swirl pulverized coal burners 12 from top to bottom. Each layer of swirl pulverized coal burners 12 includes an upper burner 121 and a lower burner 122. The burnout air device includes three layers, with three burnout air nozzles 13 in each layer. The nozzle axes of each swirl pulverized coal burner in the same layer of the four air distribution chambers 11 are arranged diagonally in pairs. Each swirl pulverized coal burner 121 and 122 in the same layer of the four air distribution chambers 11 is connected to the same coal mill 14. Each swirl pulverized coal burner in different layers corresponds to a different coal mill.

[0015] In this embodiment, the furnace dimensions a and b are 18-22 meters, the large-scale wing wall dimension L is 4-6 meters, the furnace height H1 in the main combustion zone is 15-22 meters, and the furnace height H2 in the burnout air zone is 10-20 meters, forming a large furnace combustion space; a total of six coal mills 14 are configured, each coal mill 14 corresponds to upper and lower layers of burners 121 and 122, with four burners per layer, for a total of twelve layers of burners and forty-eight burners in the entire furnace; the lower furnace 1 and upper furnace 3 of this invention are quadrilaterals, and the main combustion zone furnace 2 is located at each corner. A chamfered wing wall 8 is added to form an octagonal furnace. Multiple layers of swirling pulverized coal burners 12 are installed in the air distribution chambers 11 on the wing wall 8, which improves the self-stabilizing combustion capability. The nozzle axes of the swirling pulverized coal burners in the same layer within the four air distribution chambers 11 are arranged diagonally in pairs, representing a non-tangential combustion method, and not a simple opposing combustion method. This avoids risks such as residual rotating flue gas at the furnace outlet, large temperature deviations in the outlet flue gas, large temperature deviations in the flue gas from both side walls, and deviations in the flow field organization, resulting in a more uniform airflow within the furnace, and the ratio of a to b is 0. The furnace, with a diameter of 0.95-1.05, is designed to be nearly square. The two sets of diagonally positioned swirl pulverized coal burners 12 intersect and interact, avoiding the large deviations in pulverized coal, air distribution, and steam-water flow caused by the wider furnace of a counter-firing boiler. Each burner is arranged on the wing wall 8 of the octagonal furnace. If the width L of the wing wall 8 is too large, the furnace dimensions a and b will increase for the same furnace cross-sectional dimensions, resulting in poor furnace economy. If the width L of the wing wall 8 is too small, the flame of the self-stabilizing swirl burner 12 will brush against the wall. The distance from the center of the wing wall 8 to the center of the furnace is... The distance from C increases, affecting the flame expansion and furnace filling degree; the width dimension L of each wing wall 8 is 0.2-0.3 times (a+b) / 2, which creates conditions for independent combustion of the self-stabilizing swirl burner. Combustion is less affected by the space furnace boundary and the flame and airflow of other burners, resulting in a better independent combustion flame shape. The combustion flame in the furnace is more uniform, with less flame interference and fluctuation, and better combustion stability. At the same time, it avoids flame brushing the wall, which can achieve good combustion aerodynamic flow field organization in the furnace, accurately control flue gas temperature deviation, and ensure the safe operation of large-capacity high-parameter boilers. The ratio of a to b is 0.95-1.05, which can better construct large-angle included angle θ and large-scale wing wall structure, and is more conducive to controlling the uniformity of the combustion aerodynamic field in the furnace. With included angle θ of 135°, the resistance of the rising airflow in the furnace is minimal in the four corner spaces, and its corner effect is the best, resulting in better flame filling in the furnace and more uniform airflow in the large space of the furnace. The large-scale L wing wall structure, which arranges each burner 11 and air distribution chamber 11, also creates flexibility in the arrangement of burnout air, breaking through the limitation that only a single burnout air can be arranged in a single corner at the same height. Multiple layers and multiple burnout air nozzles 13 form a multi-dimensional burnout air distribution system. The burnout air nozzles on multiple wing walls act simultaneously, which can achieve full coverage of burnout air in the furnace cross section, enhance the filling and coverage of burnout air in the furnace, control the uniformity of rising airflow in the burner area, and significantly reduce NOx emissions and flue gas temperature deviation. In summary, this invention can improve self-stabilizing combustion capability, uniformity of airflow in the furnace and flame coverage, and avoid flame brushing against the walls, thereby achieving good combustion aerodynamic flow field organization in the furnace, accurately controlling flue gas temperature deviation, ensuring the safe operation of large-capacity, high-parameter boilers, and better meeting the high-indicator requirements of next-generation coal-fired power technology.

[0016] The above embodiments have been used to illustrate the invention, but it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the invention to the scope of the described embodiments.

Claims

1. A swirl combustion system for a wing-walled furnace boiler, wherein the lower furnace, the main combustion zone furnace, and the upper furnace each include a front wall, a right side wall, a rear wall, and a left side wall; characterized in that: Inclined wing walls are provided between the front wall, right wall, rear wall, and left wall of the furnace in the main combustion zone. Each of the four wing walls has an air distribution chamber. Each of the four air distribution chambers has a burnout air device and two or more layers of swirl pulverized coal burners from top to bottom. The nozzle axes of each swirl pulverized coal burner in the same layer of the four air distribution chambers are arranged diagonally in pairs. Each swirl pulverized coal burner in the same layer of the four air distribution chambers is connected to the same coal mill. Each swirl pulverized coal burner in different layers corresponds to a different coal mill.

2. The swirl combustion system of a wing-wall furnace boiler as described in claim 1, characterized in that: The burnout air device includes two or more layers, with two or more burnout air nozzles on each layer.

3. The swirl combustion system of a wing-wall furnace boiler as described in claim 1 or 2, characterized in that: The distance between the front wall and the rear wall is b, and the distance between the right wall and the left wall is a, with the ratio of a to b being 0.95-1.05; the width L of each wing wall is 0.2-0.3 times (a+b) / 2.

4. The swirl combustion system of a wing-wall furnace boiler as described in claim 3, characterized in that: The angle θ between each wing wall and the front wall, right side wall, rear wall, or left side wall is an obtuse angle and preferably 135°.

5. The swirl combustion system of a wing-wall furnace boiler as described in claim 4, characterized in that: Each layer of swirl pulverized coal burner includes an upper burner and a lower burner.

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