Circulating fluidized bed boiler

Abstract

The utility model discloses a circulating fluidized bed boiler which is characterized in that a screen type heating surface is arranged in a hearth of the circulating fluidized bed boiler, an inlet header is arranged at the bottom end of the screen type heating surface, and an outlet header is arranged at the top end of the screen type heating surface; and the top end of the screen type heating surface is hung and fixed through a hanging device. According to the circulating fluidized bed boiler, the structure of the tube panel is innovated, an L-shaped elbow at the lower part is omitted, the fixed end at the lower part is optimized into the free end, and the tube panel can be suspended on the top plate to freely expand downwards, so that the deformation caused by unbalanced stress of the tube panel can be effectively avoided, and the expansion stress of an elbow area at the lower part and a header pipe joint area is reduced; and the reliability is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of combustion equipment / circulating fluidized bed, in particular to a circulating fluidized bed boiler. Background Art

[0002] The heating surface of the superheater or reheater in a conventional circulating fluidized bed boiler furnace generally adopts an L-shaped tube screen type. Since the characteristics of the medium flowing inside it are different from those in the water-cooled wall tube, the expansion characteristics of the two heating surfaces are different, forming a large expansion difference at the connection point. Therefore, the design usually adopts a model in which the fixing point of the screen or the screen over the water-cooled wall is at the bottom, and the screen-type heating surface expands from bottom to top. It is believed that during normal operation, the screen-type heating surface should be in a taut state of force balance under the action of the downward pull of the water-cooled wall, its own gravity, the upward pull of the hanging device, and the upward expansion force of the heating surface, and there will be no bending.

[0003] However, in actual operation, there are certain deviations in the temperature distribution of the same screen wall and the concentration distribution of the furnace materials. The sealing cover and expansion joint of the screen heating surface passing through the ceiling area are also prone to improper installation. The failure of the constant force spring hanger may also cause the screen heating surface to be stuck and unable to expand freely upward, which will break the balance between the downward pull of the water-cooled wall on the screen heating surface, its own gravity, the upward pull of the hanging device and the upward expansion force of the heating surface, resulting in deformation of the tube screen. This situation especially occurs in supercritical boilers, because the heating surface in the supercritical boiler furnace is made of austenitic stainless steel materials such as SA-213TP347H with higher grades. Due to the large linear expansion of the material, the stress generated by thermal expansion is enough to crack the stress concentration parts such as the heating surface tube, L-shaped screen elbow area, and header root pipe seat, causing leakage and non-stop.

[0004] The L-shaped tube screen type currently used in conventional circulating fluidized bed boilers is restricted by the setting of its expansion system. In actual operation, it is difficult to achieve a balance between the downward pull of the water-cooled wall, its own gravity, the upward pull of the hanging device, and the upward expansion force of the heated surface. In addition, the flexibility of the tube screen increases in a high-temperature environment, which leads to deformation of the tube screen. Large expansion stress is generated in the lower elbow area, the header pipe joint area, etc., which causes cracking and leakage. Utility Model Content

[0005] The purpose of the utility model is to overcome the problems of the prior art and disclose a circulating fluidized bed boiler. The utility model solves the problems of distortion and deformation of the conventional L-shaped screen heating surface and stress cracking of the header pipe seat by arranging the structure of the screen heating surface and its connecting parts in the circulating fluidized bed boiler.

[0006] The purpose of the utility model is achieved through the following technical solutions:

[0007] A circulating fluidized bed boiler is provided with a platen-type heating surface in the furnace of the circulating fluidized bed boiler, an inlet header is provided at the bottom of the platen-type heating surface, and an outlet header is provided at the top of the platen-type heating surface; the top of the platen-type heating surface is suspended and fixed by a hanging device.

[0008] According to a preferred embodiment, the platen-type heating surface is composed of straight tube plates.

[0009] According to a preferred embodiment, the platen-type heating surface and the outlet header are flexibly connected by a bent pipe.

[0010] According to a preferred embodiment, a furnace roof seal is provided at a position where the top of the screen-type heating surface passes through the furnace ceiling.

[0011] According to a preferred embodiment, the furnace roof seal is composed of a three-dimensional expansion joint.

[0012] According to a preferred embodiment, throttling holes are provided at each pipe joint position between the inlet header and the platen-type heating surface.

[0013] According to a preferred embodiment, a furnace wall seal is provided at the position where the inlet header penetrates the furnace water-cooled wall.

[0014] According to a preferred embodiment, the furnace wall seal is composed of a three-dimensional expansion joint.

[0015] The above-mentioned main scheme of the utility model and its further optional schemes can be freely combined to form multiple schemes, all of which are schemes that can be adopted and claimed for protection by the utility model. After understanding the scheme of the utility model, those skilled in the art can understand that there are many combinations based on the existing technology and common knowledge, all of which are technical schemes to be protected by the utility model, and they are not exhaustively listed here.

[0016] Beneficial effects of the utility model:

[0017] In the circulating fluidized bed boiler of the utility model, by innovating the tube panel structure, the lower L-shaped elbow is eliminated, and the lower fixed end is optimized to a free end. The tube panel can be suspended on the top plate and expand downward freely, which can effectively avoid deformation caused by unbalanced force on the tube panel, reduce the expansion stress in the lower elbow area and the header pipe joint area, and improve reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a circulating fluidized bed boiler of the utility model;

[0019] Among them, 1-inlet header, 2-furnace wall seal, 3-water-cooled wall, 4-screen heating surface, 5-furnace top seal, 6-outlet header, 7-hanging device. DETAILED DESCRIPTION

[0020] The following describes the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0021] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0022] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the utility model product is usually placed when in use, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0023] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0024] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In addition, the present utility model should point out that, in the present utility model, if the specific structure, connection relationship, position relationship, power source relationship, etc. are not specifically written out, the structure, connection relationship, position relationship, power source relationship, etc. involved in the present utility model are all known by technical personnel in this field on the basis of existing technology without creative work.

[0026] refer to Figure 1 As shown, the figure shows a circulating fluidized bed boiler, in which a platen-type heating surface 4 is provided in the furnace of the circulating fluidized bed boiler, an inlet header 1 is provided at the bottom end of the platen-type heating surface 4, and an outlet header 6 is provided at the top end of the platen-type heating surface 4; the top end of the platen-type heating surface 4 is suspended and fixed by a hanging device 7.

[0027] Preferably, the platen-type heating surface 4 is composed of straight tube panels. Conventional circulating fluidized bed boilers use L-shaped tube panels, which easily produce stress concentration areas at the lower elbows, increasing the risk of leakage. The platen-type heating surface 4 uses straight tube panels to avoid stress concentration problems.

[0028] Preferably, the platen heating surface 4 and the outlet header 6 are connected by a flexible elbow. The force point of the hanging device 7 is rooted on the tube plate, and the platen heating surface 4 and the outlet header 6 are connected by a flexible elbow, eliminating the expansion stress caused by the wall temperature deviation between the tubes.

[0029] Preferably, a furnace top seal 5 is provided at the position where the top of the platen-type heating surface 4 passes through the furnace ceiling. Further, the furnace top seal 5 is composed of a three-dimensional expansion joint.

[0030] Preferably, throttling holes are provided at the positions of the pipe joints between the inlet header and the platen-type heating surface 4, thereby reducing the flow deviation between the tube panels.

[0031] Preferably, a furnace wall seal 2 is provided at the position where the inlet header 1 penetrates the furnace water-cooled wall 3. Further, the furnace wall seal 2 is composed of a three-dimensional expansion joint.

[0032] Through the structural arrangement of the furnace wall seal 2 and the furnace roof seal 5, the relative displacement between the water-cooled wall 3 and the platen-type heating surface 4 can be absorbed while ensuring sealing.

[0033] The outlet header 6 (or the inlet header 1) of the platen heating surface 4 of the utility model is the zero point of vertical expansion, and the whole expands downward, eliminating the upward expansion force generated during the operation of the conventional L-shaped platen superheater and solving the problem of tube platen distortion.

[0034] In the circulating fluidized bed boiler of the utility model, by innovating the tube panel structure, the lower L-shaped elbow is eliminated, and the lower fixed end is optimized to a free end. The tube panel can be suspended on the top plate and expand downward freely, which can effectively avoid deformation caused by unbalanced force on the tube panel, reduce the expansion stress in the lower elbow area and the header pipe joint area, and improve reliability.

[0035] Example

[0036] A circulating fluidized bed boiler, the working medium side process is: enter the inlet header 1 from the steam connecting pipe, enter the outlet header 6 after being heated by the platen heating surface 4, and finally lead out from the outlet header 6 to the subsequent process.

[0037] In order to reduce the flow deviation between tube panels, a throttling hole needs to be set at the inlet header 1 pipe joint.

[0038] At the lower end, the relative thermal displacement between the screen-type heating surface 4 and the water-cooled wall 3 at the through-wall position is about 60mm to 200mm, so the through-furnace wall seal 2 adopts a three-dimensional expansion joint, which can effectively absorb the relative displacement between the screen-type heating surface 4 and the water-cooled wall 3. Due to the large displacement, the expansion joint can be pre-displaced by 30mm to 40mm to extend the service life of the expansion joint. The screen-type heating surface 4 at the furnace top position and the ceiling of the water-cooled wall 3 have a relative thermal displacement of about 10 to 20mm, so the through-furnace top seal 5 also adopts an expansion joint to absorb the expansion difference.

[0039] During normal operation of the boiler, the platen heating surface 4 expands downward in the vertical direction with the outlet header 6 as the expansion zero point. Because it is sealed with the water-cooled wall by an expansion joint and can move freely relative to it, the platen heating surface 4 will not be subjected to any upward force that causes the tube plate to twist and deform.

[0040] The stress point of the hanging device 7 is rooted on the platen heating surface 4. The platen heating surface 4 and the outlet header 6 are connected by a flexible elbow to eliminate the expansion stress effect of the wall temperature deviation between tubes on the tube panel and the header pipe seat.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A circulating fluidized bed boiler, characterized in that: The furnace of the circulating fluidized bed boiler is provided with a platen-type heating surface (4). The bottom end of the platen-type heating surface (4) is provided with an inlet header (1), and the top end of the platen-type heating surface (4) is provided with an outlet header (6); The top end of the screen-type heating surface (4) is suspended and fixed by a hanging device (7); A furnace top seal (5) is provided at the position where the top of the screen-type heating surface (4) passes through the furnace ceiling; The furnace top seal (5) is composed of a three-dimensional expansion joint; Throttling holes are provided at the pipe joint positions of the inlet header (1) and the platen-type heating surface (4).

2. The circulating fluidized bed boiler according to claim 1, characterized in that: The platen-type heating surface (4) is composed of straight tube plates.

3. The circulating fluidized bed boiler according to claim 1, characterized in that: The platen-type heating surface (4) and the outlet header (6) are flexibly connected by means of a bent pipe.

4. The circulating fluidized bed boiler according to claim 1, characterized in that: A furnace wall seal (2) is provided at the position where the inlet header (1) penetrates the furnace water-cooled wall (3).

5. The circulating fluidized bed boiler according to claim 4, characterized in that: The furnace wall seal (2) is composed of a three-dimensional expansion joint.

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