JPH0646104U - Inner wall structure of combustor in circulating fluidized bed boiler - Google Patents

Abstract

(57) [Summary] [Objective] The lower portion of the water pipe 38a of the exposed lower portion R of the water pipe wall 36
Provided is an inner wall structure of a combustor capable of preventing the particles from being abraded by the fine particles a. [Structure] A large-diameter upper inner wall 35 connected to an upper part of a small-diameter lower inner wall 32 made of a refractory material, and a large number of water pipes 3 provided in parallel to the inner surface of the upper inner wall 35 in the vertical direction.
8 and a water pipe wall 36 composed of fins 39 connecting between the water pipes 38, and the lower inner wall 32 and the upper inner wall 3 are provided.
The retreat wall part 3 retreated from the water pipe wall 36 at the connection part with the 5
3a is formed, the exposed lower portion R of the water pipe wall 36 is expanded in the outer diameter direction and embedded in the retreat wall portion 33a, and the shoulder portion 33 continuous below the retreat wall portion 33a and the A space S is formed between the exposed lower portion R and the exposed lower portion R of the water pipe wall 36 is formed by retreating from the wall surface of the water pipe wall 36.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to the inner wall structure of a combustor in a circulating fluidized bed boiler.

[0002]

[Prior art]

 As a boiler that efficiently burns solid fuel, a circulating fluidized bed boiler is known in which ash and limestone or sand particles are mixed and fluidized in the fluidized bed. An example of this circulation type fluidized bed boiler will be described. As shown in FIG. 2, a tower-shaped combustor 1, an external heat exchanger 2 adjacent to the combustor 1, and an external heat exchanger 2 are provided. A cyclone 7 in which a conduit 6 extending downward is inserted into a hot recycle 5 which is arranged in the upper part, is connected to the combustor 1 by a thick connecting pipe 3, and is divided by a partition wall 4 of the external heat exchanger 2, and the cyclone 7 And an evaporation part (not shown) connected to the upper part of the.

The combustor 1 is formed by connecting a large diameter portion 8 having a large inner diameter to an upper portion and a small diameter portion 9 having a small inner diameter to a lower portion via a taper portion 10. The area from the middle of the small-diameter portion 9 to the lower side is the dense bed area A, and the upper area is the freeboard area B. A dense bed material is accommodated in the dense bed region A to form a dense bed 11, in which coal 12 as a solid fuel is fed from the fuel supply pipe 13 and limestone 14 is used for the purpose of capturing sulfur. It is adapted to be supplied from the supply pipes 15, respectively. The primary air 17 serves as fluidized air from the primary air system 16. Reference numeral 18 denotes a secondary air system, and the secondary air 19 is supplied from the secondary air system 18 for complete combustion.

As shown in FIG. 3, in the combustor 1 configured as described above, the lower inner wall 20 is usually made of a refractory material, and at least a part of the upper inner wall 21 is formed as a water pipe wall 22. . That is, the water pipe wall 22 extends vertically between the upper header 23 and the lower header 24, and as shown in FIG. 4, a plurality of water pipes 25 are arranged at predetermined intervals d. The water pipes 25 are connected by fins 26. The inner surface of the water pipe wall 22 is exposed inside the combustor 1, but the outer surface is covered with an outer wall 27 made of a refractory material.

[0005]

[Problems to be solved by the device]

 By the way, in the combustor 1 having the inner wall structure as described above, the step portion is formed at the joint portion between the lower inner wall 20 made of the refractory material and the water pipe wall 22 constituting the upper inner wall 21. Specifically, as shown in FIGS. 5 and 6, since the lower end of the water pipe 25 is connected to the lower header 24, the lower header 24 is buried in the lower inner wall 20, and thus the lower inner wall 20. The exposed lower end 25a of the water pipe immediately above has a problem that the fine particles a collide and wear, and it requires a great deal of time and labor to repair it, and the operation must be stopped during that time. However, there is a problem that the operation utilization rate deteriorates.

More specifically, as shown in FIGS. 5 and 6, the fuel gas G rising in the combustor 1 is accompanied by fine particles a such as sand, and this is in the freeboard area B on the large diameter portion 8 side. To fall on the water pipe wall 22, and accumulate on the shoulder portion 20a of the lower inner wall 20. The vector of the falling state of the fine particles a is as shown in FIG. Then, since the falling fine particles a collide with the water pipe 25 at the lower end 25a of the water pipe to change its direction, the lower end 25a is worn. It has been confirmed that the degree of this wear is particularly severe in the vicinity N of the portion of the water pipe 25 where the fin 26 is attached, as shown in FIG. Depending on the operating conditions, a part of the ascending fine particles a may directly hit the lower end of the water pipe 25, so that the wear becomes more severe.

In short, the portion of the water pipe 25 through which the fine particles a flow in parallel does not cause significant wear, but it is a portion such as the shoulder portion 20a of the lower inner wall 20 that changes the downflow direction, and is locally attached to this water pipe 25. And collide with each other, and at this time, the fine particles a function as an abrasive and generate severe abrasion.

[0008]

[Means for Solving the Problems]

 The present invention has been made in order to solve the problems in the conventional circulating fluidized bed boiler, and comprises a large-diameter upper inner wall connected to an upper part of a small-diameter lower inner wall made of refractory material. , Has a large number of water pipes provided in parallel to the inner surface of the upper inner wall in the longitudinal direction, and a water pipe wall composed of fins that connect the water pipes to each other. It forms a receding wall part that is receded from the water pipe wall, and the exposed lower part of the water pipe wall is expanded in the outer diameter direction and embedded in the receding wall part, and a shoulder continuous below the receding wall part is formed. The present invention provides an inner wall structure of a combustor in a circulating fluidized bed boiler, wherein a space is formed between a portion and a lower exposed portion.

[0009]

[Work]

 According to the inner wall structure of the combustor in the circulating fluidized bed boiler of the present invention, the exposed lower portion of the water pipe wall expands outwardly and forms a space between the shoulder and the exposed lower portion. Therefore, the falling particles do not come into contact with the exposed lower part of the water pipe, and the lower inner wall is located inward of the water pipe wall forming the upper inner wall. Since it does not hit the lower end of the water pipe, the wear can be prevented.

[0010]

【Example】

 An embodiment of the inner wall structure of the combustor in the circulating fluidized bed boiler according to the present invention will be described below with reference to FIG. FIG. 1 is an enlarged side view showing the main part of the inner wall structure. The lower inner wall 32 forming the combustor 31 is made of refractory material, and the upper end thereof is formed with a shoulder portion 33 that expands outward. . The inner edge 34 of the lower inner wall 32 is positioned so as to be recessed inward from the inner edge 37 of the water pipe wall 36 forming a part of the upper inner wall 35 so as to have a distance D therein. A water pipe wall 36 is formed on the inner surface of the upper inner wall 35. A large number of water pipes 38 constituting this water pipe wall 36 are arranged in parallel in the vertical direction, and a fin 39 is provided between these water pipes 38. The lower part of the water pipe 38a and the lower part of the fin 39a of the water pipe are both configured to expand in the outer diameter direction at an angle θ. The lower end 38a of the water pipe is connected to the lower header 40 arranged in the thick portion of the upper inner wall 35.

In addition, a retreat wall portion 33a is formed on the upper portion of the shoulder portion 33 so as to retreat from the water pipe wall 36 in the outer diameter direction, and is connected at an intermediate position between the water pipe lower portion 38a and the fin lower portion 39a. A space S is formed between the exposed lower portion R of the water pipe wall 36 and the shoulder 33. Therefore, the fine particles a falling along the water pipe wall 36 are formed so as not to directly collide with the water pipe lower end portion 38a and the fin lower end portion 39a.

In the operating state of the boiler having the above-described structure, the fine particles a falling along the water pipe wall 36 are exposed from the exposed lower portion R on the front surface of the receding wall portion 33a at the lower end of the straight portion of the water pipe wall 36. After they are separated and once deposited on the shoulder portion 33, they fall into a dense bed (not shown) or are accompanied by the combustion gas G and rise again. On the other hand, the fine particles a ′ rising along the inner edge 34 of the lower inner wall 32 are partially diffused outward from the upper end of the lower inner wall 32 and rise. In this way, neither the falling fine particles a nor the rising fine particles a ′ come into vigorous contact with the water pipe lower portion 38a of the water pipe wall 36 and the exposed lower portion R of the fin lower portion 39a.

That is, the lower part of the water pipe 38a and the lower part of the fin 39a, which are the lower end parts of the water pipe wall 36 exposed in the combustor 1, recede from the vertical surface of the water pipe wall 36 and have a space S. Therefore, the falling fine particles a and the like are released at this portion, and the exposed portion near the shoulder portion 20a as shown in FIGS. 5 and 6 disappears, and the abrasion phenomenon of the water pipe 38 occurs. Will not do. Therefore, according to the present invention, the combustor of the circulating fluidized bed boiler can be used for a long period of time.

[0014]

[Effect of device]

 As is clear from the above description, the inner wall structure of the combustor in the circulating fluidized bed boiler according to the present invention is composed of a large-diameter upper inner wall 35 connected to an upper part of a small-diameter lower inner wall 32 made of refractory material, The upper inner wall 35 has a large number of water pipes 38 arranged in parallel in the longitudinal direction, and a water pipe wall 36 composed of fins 39 connecting the water pipes 38, and the lower inner wall 32 and the upper portion. A receding wall portion 33a retracted from the water pipe wall 36 is formed at a connection portion with the inner wall 35, and an exposed lower portion R of the water pipe wall 36 is expanded outwardly in the receding wall portion 33a. A space S is formed between the shoulder 33 and the exposed lower portion R that are buried and continuous below the receding wall portion 33a. The exposed lower portion R of the water pipe wall 36 is formed by the space S. Since it is formed by retreating from the wall surface of It is possible to prevent wear of the exposed lower R that out, not only can greatly reduce the auxiliary Osamu work, there is an effect that it is possible to improve the operation utilization of the boiler.

[Brief description of drawings]

FIG. 1 is an enlarged view of a main part of an embodiment of an inner wall structure of a combustor in a circulating fluidized bed boiler according to the present invention.

FIG. 2 is a schematic view of a circulating fluidized bed boiler according to the present invention.

FIG. 3 is a partial sectional view showing an inner wall structure of a conventional combustor.

4 is a cross-sectional view taken along the line AA of the inner wall of FIG.

5 is an enlarged view of part B in FIG.

6 is a view taken along the line CC of FIG.

FIG. 7 is a velocity vector diagram of falling particles.

[Explanation of symbols]

32 lower inner wall 33 shoulder 33a retreat wall
34 Inner Edge 35 Upper Inner Wall 36 Water Tube Wall 37 Inner Edge 3
8 water pipe 38a water pipe lower part 39a fin lower part 40 header R exposed lower part S space part

Claims (1)

[Scope of utility model registration request] 1. A large diameter upper inner wall connected to an upper portion of a small diameter lower inner wall made of a refractory material, and a large number of water pipes provided in parallel to the inner surface of the upper inner wall in the longitudinal direction, and It has a water pipe wall composed of fins that connect between them, and forms a receding wall portion that is receded from the water pipe wall at the connecting portion between the lower inner wall and the upper inner wall, and the exposed lower portion of the water pipe wall A combustor in a circulating fluidized bed boiler, which is expanded in the outer diameter direction and embedded in the receding wall portion, and a space is formed between a shoulder portion continuous below the receding wall portion and the exposed lower portion. Inner wall structure.