A circulating fluidized bed boiler hood with adjustable resistance

Abstract

The present invention discloses a circulating fluidized bed boiler hood with adjustable resistance, comprising an outer cover, a core tube and a throttle cap; a positioning hole is provided on the top of the outer cover, and a plurality of hood guide holes are provided on the side wall; a limiting column is provided on the top of the throttle cap, the throttle cap is sleeved in the outer cover, and the limiting column is inserted into the positioning hole; the inner wall at the bottom of the throttle cap has an internal thread, the top of the core tube has an external thread, and the core tube and the throttle cap are connected by matching the internal and external threads; a plurality of throttle holes are provided on the side wall of the throttle cap, and air can flow out through the core tube, the throttle hole and the guide hole in sequence. In the specific operation of the circulating fluidized bed boiler hood with adjustable resistance described in the present invention, a plurality of guide holes are provided on the side of the outer cover along the circumferential direction, and a plurality of throttle holes are provided on the side wall of the core tube, and the material flows out from the guide hole in sequence through the core tube and the throttle hole, wherein the total area of ​​the throttle hole can be adjusted by the thread between the core tube and the throttle cap to adjust the total flow area so as to flexibly adjust the hood resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of boilers, and in particular relates to a circulating fluidized bed boiler hood with adjustable resistance. Background Art

[0002] During the operation of circulating fluidized bed boilers, a stable material circulation needs to be established. The hood on the air distribution plate has an important influence on the realization of this process. When designing the boiler, it is necessary to ensure that the air is evenly distributed over the entire furnace cross section. Under the premise of uniform fluidization of the material, the fluidization dead zone should be avoided to prevent accidents such as slag leakage in the wind chamber, uneven fluidization, and coking of the bed layer. There are many types of hoods. Several types of hoods have been widely used in China, including pigtail hoods, Γ hoods, arrow hoods, columnar hoods, and bell hoods. The pigtail hood originated from the Finnish Ahlstrom Company. The upper and lower sections of the hood are vertically connected to the bottom of the furnace and the wind chamber respectively, and the middle section is horizontally arranged in the wear-resistant refractory material layer of the air distribution plate. This type of hood rarely wears, but the horizontal section is prone to slag accumulation and clogging, and the resistance design is relatively large, so it is less used now.

[0003] The Γ-shaped hood is a directional hood. As a single-hole hood, it has a larger aperture and can be divided into right-angle and inclined shapes according to the different outlet angles. The resistance of this hood is low, and uneven air distribution can easily cause slag leakage. In actual operation, the resistance is only 3kPa, which is very likely to cause slag leakage. In addition, the Г-shaped hood has high installation requirements and needs to be calibrated one by one, otherwise it is very easy for the hoods to be worn against each other. At present, it is mostly used as a directional hood near the slag discharge port.

[0004] The arrow-shaped hood is also a kind of directional hood. This type of hood consists of a main air duct and a double-hole or multi-hole nozzle pipe. Each hole blows downward at a certain angle to the hood body. From the actual use, the arrow-shaped hood wears less and the installation requirements are not as strict as those of the Γ-shaped hood, but slag leakage still exists.

[0005] Cylindrical hoods are widely used on small and medium-sized circulating fluidized bed boilers. This type of hood has a simple structure, is easy to manufacture, and has moderate resistance. However, there are many hoods, the hood spacing is small, and the outer holes are prone to wear and deformation. When the fluidizing wind fluctuates, some materials will be sucked back into the wind chamber through the outer holes or block the hood, resulting in insufficient ventilation and burning of the hood. The hood has a short service life and a large maintenance workload. Currently, this type of hood is only used on the external bed and return feeder of large circulating fluidized bed boilers.

[0006] The bell-shaped hood is a type of hood that is currently used more frequently. The hood consists of a core tube and an outer cover. The core tube is fixed through the air distribution plate, and the hood is fixed to the upper end of the core tube. There are several external holes around the outer cover of the hood. Due to the large aperture, it is not easy to be blocked by particles, and the hood is generally cast. However, with the trend of large-scale circulating fluidized bed boilers, the size of the boiler air chamber continues to increase, and the air chamber pressure in different areas of the air distribution plate can no longer be designed using the average value. The hood needs to be arranged in different areas to cope with the deviation of the air pressure distribution in the air chamber. This results in the need to install a variety of hoods with different resistance characteristics on the air distribution plate to ensure uniform air distribution. In addition, as the operating time of the boiler increases, the hood aperture continues to increase, resulting in a continuous decrease in the resistance of the hood in the wear area, requiring frequent replacement. Summary of the invention

[0007] The object of the present invention is to provide a circulating fluidized bed boiler hood with adjustable resistance, so as to effectively improve the problem of uneven resistance distribution of an air distribution plate occurring during use.

[0008] In order to achieve the above object, the present invention adopts the following technical scheme:

[0009] A circulating fluidized bed boiler hood with adjustable resistance, comprising an outer cover, a core tube and a throttling cap;

[0010] A positioning hole is provided on the top of the outer cover, and a plurality of hood guide holes are provided on the side wall;

[0011] A limiting post is arranged on the top of the throttle cap, the throttle cap is sleeved in the outer cover, and the limiting post is inserted into the positioning hole;

[0012] The inner wall at the bottom of the throttle cap is provided with internal threads, the top of the core tube is provided with external threads, and the core tube and the throttle cap are connected by matching the internal and external threads;

[0013] A plurality of throttle holes are arranged on the side wall of the throttle cap, and the air can flow out through the core tube, the throttle holes and the guide holes in sequence.

[0014] Furthermore, the outer cover is bell-shaped; a circle of hood guide holes is arranged around the lower part of the side wall of the outer cover.

[0015] Furthermore, the number of throttling holes on the throttling cap is 6 to 60, the hole diameter is 1 to 10 mm, and they are distributed in 2 to 6 layers.

[0016] Furthermore, the diameter of the positioning hole is 10 to 20 mm.

[0017] Furthermore, a limiting device for limiting the maximum height of the threaded fit between the core tube and the throttle cap is provided between the core tube and the throttle cap.

[0018] Furthermore, the limiting device is a step arranged on the outer wall of the core tube.

[0019] Furthermore, at least two layers of throttling holes are arranged on the side wall of the throttling cap, and the height of the internal thread extends from the lower edge of the throttling cap (3) to the height of the topmost layer of throttling holes.

[0020] Furthermore, by adjusting the thread fit height between the core tube and the throttle cap, the total flow area of ​​the throttle hole can be adjusted.

[0021] Furthermore, the height of the lowest layer of throttling holes is higher than the height of the guide holes.

[0022] Furthermore, a through hole is provided at the lower part of the outer cover for the core tube and the throttling cap to enter therein; and the outer wall of the core tube is sealed and matched with the through hole at the bottom of the outer cover.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] During the specific operation of the circulating fluidized bed boiler hood with adjustable resistance described in the present invention, a plurality of guide holes are arranged along the circumferential direction on the side of the outer cover, and a plurality of throttling holes are arranged on the side wall of the core tube, and the material flows out from the guide holes through the core tube and the throttling holes in sequence, wherein the total area of ​​the throttling holes can be adjusted by the threads between the core tube and the throttling cap to adjust the total flow area so as to flexibly adjust the resistance of the hood. In addition, during installation, it is only necessary to insert and fix the limit column into the positioning hole, which is convenient for installation and reduces the maintenance cost of the later equipment. At the same time, it can be used for the design of new boilers and can also be applied to the transformation of boilers that have been put into operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0026] Figure 1 It is a structural schematic diagram of an outer cover of a circulating fluidized bed boiler hood with adjustable resistance according to the present invention;

[0027] Figure 2 is a cross-sectional view of the core tube;

[0028] Figure 3 is a cross-sectional view of the throttle cap;

[0029] Figure 4 It is a schematic diagram of the assembly structure of a circulating fluidized bed boiler hood with adjustable resistance according to the present invention;

[0030] Among them, 1 is the outer cover, 2 is the core tube, 3 is the throttling cap, 4 is the positioning hole, 5 is the wind cap guide hole, 6 is the positioning column, 7 is the throttling hole, 8 is the external thread, and 9 is the internal thread. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0032] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit exemplary embodiments according to the present invention.

[0033] See also Figures 1 to 4 As shown, the present invention provides a circulating fluidized bed boiler hood with adjustable resistance, comprising an outer cover 1, a core tube 2 and a throttling cap 3.

[0034] The outer cover 1 is bell-shaped, with a positioning hole 4 on the top and a through hole for the core tube 2 and the throttling cap to enter therein at the bottom; a plurality of hood guide holes 5 are provided around the lower part of the side wall of the outer cover 1.

[0035] The throttle cap 3 includes a cylindrical throttle wall, the top of which is sealed and fixed with a limiting column 6; the bottom of the cylindrical throttle wall is open for the top of the core tube to extend therein. Three layers of throttle holes 7 are arranged circumferentially on the cylindrical throttle wall. The inner wall of the cylindrical throttle wall is provided with an internal thread 8. The throttle cap 3 is sleeved in the outer cover 1, and the limiting column 6 is inserted into the positioning hole 4.

[0036] The core tube 2 has an external thread 9 on the top and a step on the side wall; the core tube 2 and the throttle cap 3 are connected by matching internal and external threads; the outer wall of the core tube 2 is sealed with the through hole at the bottom of the outer cover 1; the air flows out through the core tube 2, the throttle hole 7 and the guide hole 5 in sequence. The aperture of the positioning hole 4 is 15 mm. The number of throttle holes 7 on the throttle cap 3 is 24, with an aperture of 10 mm, distributed in 3 layers. The total flow area of ​​the throttle hole 7 can be adjusted by the thread matching height between the core tube 2 and the throttle cap 3. The side wall of the core tube 2 is provided with a step to limit the maximum height of the thread matching between the core tube 2 and the throttle cap 3.

[0037] When the thread of the core tube 2 is lower than the height of the lowest throttle hole 7, the overall resistance of the hood is the lowest. When the resistance of the hood needs to be increased, the thread between the core tube 2 and the throttle cap 3 can be rotated to block the lowest row of throttle holes 7 of the throttle cap 3 through the top of the core tube 2, thereby increasing the resistance of the throttle cap and improving the overall resistance characteristics of the hood. Through the mutual combination of parameters such as the diameter, number, and number of rows of throttle holes 7, a resistance-adjustable hood suitable for different boilers can be designed to facilitate boiler operation adjustment. The entire set of hoods is made of casting technology, and the material is selected from wear-resistant alloy to ensure its high-temperature wear-resistant characteristics.

[0038] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A circulating fluidized bed boiler hood with adjustable resistance, characterized in that: It comprises an outer cover (1), a core tube (2) and a throttle cap (3); The top of the outer cover (1) is provided with a positioning hole (4), and the side wall is provided with a plurality of hood guide holes (5); A limiting column (6) is arranged on the top of the throttle cap (3), the throttle cap (3) is sleeved in the outer cover (1), and the limiting column (6) is inserted into the positioning hole (4); The inner wall at the bottom of the throttling cap (3) is provided with an internal thread (8), the top of the core tube (2) is provided with an external thread (9), and the core tube (2) and the throttling cap (3) are connected by matching the internal and external threads; A plurality of throttle holes (7) are arranged on the side wall of the throttle cap (3), and air can flow out through the core tube (2), the throttle holes (7) and the guide holes (5) in sequence; A limiting device is provided between the core tube (2) and the throttle cap (3) for limiting the maximum height of the thread fit between the core tube (2) and the throttle cap (3); The limiting device is a step arranged on the outer wall of the core tube (2); At least two layers of throttling holes (7) are arranged on the side wall of the throttling cap (3), and the height of the internal thread (8) extends from the lower edge of the throttling cap (3) to the height of the topmost layer of throttling holes (7); By adjusting the thread fit height between the core tube (2) and the throttle cap (3), the total flow area of ​​the throttle hole (7) can be adjusted; The height of the lowest layer of throttling holes (7) is higher than the height of the flow guide holes (5).

2. The circulating fluidized bed boiler hood with adjustable resistance according to claim 1, characterized in that: The outer cover (1) is bell-shaped; a circle of hood guide holes (5) is arranged around the lower part of the side wall of the outer cover (1).

3. The circulating fluidized bed boiler hood with adjustable resistance according to claim 1, characterized in that: The number of throttling holes (7) on the throttling cap (3) is 6 to 60, the hole diameter is 1 to 10 mm, and they are distributed in 2 to 6 layers.

4. The circulating fluidized bed boiler hood with adjustable resistance according to claim 1, characterized in that: The diameter of the positioning hole (4) is 10 to 20 mm.

5. The circulating fluidized bed boiler hood with adjustable resistance according to claim 2, characterized in that: The lower part of the outer cover (1) is provided with a through hole for the core tube (2) and the throttling cap to enter therein; the outer wall of the core tube (2) is sealed and matched with the through hole at the bottom of the outer cover (1).

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