JPH0115761B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is designed to prevent heat transfer tubes and furnace wall tubes disposed in a fluidized bed boiler layer from being worn out due to contact with a flowing fluid medium (for example, sand, etc.). This relates to a protective device.

As shown schematically in Figure 1, a fluidized bed boiler consists of vertical furnace wall tubes a arranged around the periphery and successively connected by fins b as shown in Figure 2 to form a tube wall. A medium (for example, sand) is deposited, the fluidized medium is caused to flow by blowing air into the layer c under the layer c of the fluidized medium, and heat transfer tubes embedded in the layer c. The upper end of the furnace wall tube a and the upper end of the heat transfer tube d are connected to the steam drum e, and the steam separated in the steam drum e is sent to the demand, and the separated water is ,
Water can be introduced into the lower end of the heat transfer tube d or the lower end of the furnace wall tube a to allow water to circulate, and furthermore, fuel (for example, pulverized coal) can be supplied into or onto the fluidized bed. supply pipe f
is provided. g is a water tube and h is an air dispersion nozzle.

In the fluidized bed boiler with the above configuration,
The fluidized medium flows by blowing air and comes into contact with the heat exchanger tubes d and the furnace wall tubes a. Although it varies depending on the type of fluidized medium, in general, the inner surface of the furnace wall tube a and the lower surface of the heat transfer tube d at the height corresponding to the height at which the fluidized medium flows are provided with a fluidized medium blown up by air (for example, As the particles (sand) and crushed coal flow and come into contact with each other, friction occurs and wear on the pipe surface progresses.

The present invention was made for the purpose of preventing wear on the surfaces of the furnace wall tubes and heat transfer tubes located in the range where the fluidized medium of the fluidized bed flows in such a fluidized bed boiler. On the bottom side of the heat tube,
The wear-resistant material is bonded to prevent wear due to friction with the fluid medium, and the use of sintered metal as the wear-resistant material prevents the heat transfer coefficient of the tube surface from decreasing.

Embodiments of the present invention will be described below with reference to the drawings.

3 and 4 show an embodiment of the present invention, in which a wear-resistant material 2 is bonded to the lower half surface of a heat exchanger tube 1 to protect it. That is, heat exchanger tube 1
In order to protect the lower half of the heat exchanger tube 1 located in the range where the fluidized medium of the fluidized bed flows, the bottom half of the heat exchanger tube 1 is The wear-resistant materials 2 are sequentially arranged in the circumferential direction at the locations corresponding to the halves, and burnt in this state to sinter the wear-resistant materials 2. At this time, the wear-resistant material 2 shrinks by being baked and adheres to the surface of the heat exchanger tube 1, and in some parts melts into the surface of the heat exchanger tube 1 and adheres, and as shown in FIG. 3, in the longitudinal direction of the heat exchanger tube, A gap 3 is formed by contraction of the wear-resistant material 2. Since this gap 3 is narrow, even if a fluid medium such as sand collides with the construction surface of the wear-resistant material 2, the fluid medium will not enter the gap 3 and rub the surface of the heat transfer tube. By joining 2, it is possible to prevent the progress of wear of the heat exchanger tube 1.

Note that the upper half of the heat exchanger tube 1 is also hit by the fluidized medium while it is flowing, but since it is less abraded than the lower half, it is not necessary to apply the wear-resistant material 2 to the upper half.

Once the wear-resistant material has been bonded to the surface of the heat transfer tube as described above, the properties of the heat transfer tube 1 itself will change due to burning during bonding and its strength will decrease.
In order to return this to its original strength, normalization processing is performed.

The wear-resistant material 2 used in the present invention is a sintered metal, and its main components are based on Fe, Cr,
It is a complex boride containing Mo, N, and W. It is kneaded and placed on the surface of the heat exchanger tube, and then attached to the tube surface by vacuum diffusion bonding.

5 and 6 show another embodiment of the present invention, in which a wear-resistant material 2 is bonded to the inner surface of a furnace wall tube 4. FIG. That is, in order to protect the vertically arranged furnace wall tubes 4 from the fluidized bed position to the height position where the fluidized medium can flow and come in contact with the furnace wall tubes 4, a wear-resistant material 2 is baked and bonded to the surface of the furnace wall tubes 4. let In this case, the fins 5 for connecting the furnace wall tubes 4 are first welded to the tubes 4, and then the wear-resistant material 2 is applied to the surface of the furnace wall tubes 4 located on the inside of the furnace as shown in FIG. Place it so that it covers the fin 5 and bake. As a result, the wear-resistant material 2 shrinks and adheres to the surface of the furnace wall tube 4, and at the same time, the part that covered the fin 5 is removed from the fin 5.
fin 5 as shown in FIGS. 5 and 8.
It adheres to the surface of the furnace wall tube 4 with a clearance 6 formed therebetween. In the clearance 6 formed above,
As shown in Figures 5 and 6, the SUS round rod 7 is connected to the furnace wall tube 4.
One end of the round rod 7 is welded, and the other end is left unwelded so that it can escape during thermal expansion.

In the above embodiment as well, a gap 3 is formed between each wear-resistant material 2 in the longitudinal direction of the tube due to contraction.
This gap 3 poses no problem in preventing wear.

As described above, according to the protection device for the surfaces of heat transfer tubes, furnace wall tubes, etc. in a fluidized bed boiler of the present invention, a wear-resistant material that does not reduce the heat transfer coefficient of the tubes is bonded to the tube surfaces, and the Since the pipe is designed to prevent wear due to the operation of the medium, the progress of wear on the pipe can be prevented with wear-resistant material, and the heat transfer coefficient on the pipe surface is hardly reduced. It can be effective.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a general example of a fluidized bed boiler, Fig. 2 is a cutaway plan view partially showing the furnace wall tube in Fig. 1, and Fig. 3 is a schematic diagram showing a general example of a fluidized bed boiler. An example diagram of the application, Fig. 4 is a view taken along the arrow A-A in Fig. 3,
Fig. 5 is a cutaway plan view showing an example of applying the device of the present invention to a furnace wall tube, Fig. 6 is a side view of Fig. 5, and Figs. 7 and 8 are sectional views showing the procedure for applying the wear-resistant material. It is. 1 is a heat exchanger tube, 2 is a wear-resistant material, 4 is a furnace wall tube, 5 is a fin, and 7 is a round bar.

Claims (1)

[Claims] 1. A wear-resistant material made of sintered metal is sintered on the surface of the tubes that come into contact with the fluidized medium, such as the furnace wall tubes that make up the tube wall of a fluidized bed boiler and the heat transfer tubes inside the fluidized bed boiler layer. A protection device for heat exchanger tubes, etc. inside a fluidized bed boiler layer, characterized by being covered with a