JPS6141756A - Heat and wear resistant fluidized bed boiler tube - Google Patents

Abstract

PURPOSE:To obtain the titled boiler tube having increased heat conductivity by spraying an Ni-Cr alloy on the outside of a steel pipe or spraying and fusing a self-fluxing Co-Ni-Cr-W-B-Si alloy. CONSTITUTION:An Ni-Cr alloy is sprayed on the outside of a steel pipe such as a Cr-Mo steel pipe or an austenitic stainless steel pipe, or a self-fluxing Co-Ni- Cr-W-B-Si alloy is thermally sprayed to obtain a heat and wear resistant fluidized bed boiler tube having high heat conductivity. The area of the heating surface of the tube is reduced to reduce the size of a boiler and to improve the durability, and steam can be generated economically and efficiently at high temp. and pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an evaporation boiler tube used in the boiler field, particularly installed in a 111-bed boiler, and more specifically to a heat-resistant and wear-resistant fluidized bed boiler tube. It is related to.

Normally, in a fluidized bed boiler, an appropriate amount of fluidized medium (limestone, etc.) is filled in the column, air is flowed upward from the lower air distribution plate, and the superficial velocity is made higher than the initial velocity of the flow.
Solid particles are floated into the column through a dispersion plate to create a fluidized state, and powdered coal, etc. is thrown into this and combusted while coming into contact with the fluidized medium, and steam is generated in this fluidized bed. An evaporation tube is installed, and the water inside the tube is converted into heated steam using the combustion heat of the boiler.

This tube is installed horizontally so that it is perpendicular to the flow while the powdered coal and fluidized medium are rising and flowing as described above, so the powdered coal and fluidized media collide with the outer surface of the tube, causing Severe surface abrasion.

For this reason, conventional duplexes undergo severe abrasion at high temperatures of 800 to 850°C, as described above, and the tube surface wears out, making them unsuitable for long-term use.Also, the heat transfer coefficient of the tube is low, making it difficult to produce high-temperature heated steam. In this case, the heat transfer efficiency has to be increased more than necessary, and the number of duplexes has to be increased, which has disadvantages such as high equipment costs.

The present invention has been made to eliminate such drawbacks, and the gist thereof is as follows: 1. Ni-Cr alloy is thermally sprayed on the outside of the steel pipe, or Ni-Cr alloy is thermally sprayed on the outside of the steel pipe, or
A heat-resistant and wear-resistant fluidized bed boiler tube made by thermally spraying and fusing o-Ni-Cr-W-B-Si solid solution alloy.

2. Heat-resistant and wear-resistant flow vJJpg boiler tube 0 as claimed in claim 1, in which the steel pipe is made of a Cr-Mo steel pipe. 3. Heat-resistant as claimed in claim 1, in which the steel pipe is made of austenitic stainless steel pipe.・It is present in wear-resistant fluidized bed boiler tubes, which improves the heat and wear resistance of the tubes, and also increases the heat transfer coefficient and reduces the heat transfer area, making the boiler more compact and efficiently distributing high-temperature heating steam. good(
The purpose is to manufacture.

Hereinafter, the present invention will be explained in detail based on examples.

Example 1゜Cr-Mo fA t-5P, --/Main Toshi, Konog
IIvl) A heat-resistant and abrasion-resistant tube was formed by plasma spraying Ni-Cr in a ratio of 50:50 by weight on the outer surface. In this example, as a result of thermal spraying with the Ni blending ratio adjusted in the range of 45 to ssx and the Cr blending ratio in the range of 55 to 45x, the same good heat-resistant and wear-resistant tube was molded. did it.

Example 2 Using an austenitic stainless steel pipe as the tube main body, the same alloy as in Example 1 was thermally sprayed on the outer surface of the steel pipe, resulting in a tube with excellent heat resistance and wear resistance.

Example 3 A Cr-Mo steel pipe was used as the tube main body, and the outer surface of the steel pipe was coated with 5XCo-21XCr-3,25 (B
As a result of thermal spraying and fusing a solid solution alloy of -2,0XSi-2,5XNi-sxw, a tube with high heat resistance and #4 wear resistance was formed. In this example, the blending ratios of each metal component were Co: 40-70%, C:
r: 12~30x, B: 2.5'~3.5X
, Si: 2~4X, Ni: 2.0~25*,
As a result of thermal spraying with W: 4 to 2 ON, a heat-resistant and abrasion-resistant tube similar to the above was molded.

Example 4 An austenitic stainless steel tube was used as the tube main tube, and the same metal as in Example 3 was thermally sprayed on the outer surface of the steel tube. As a result, a tube with #4 excellent heat and wear resistance was formed.

The above tube, the conventional tube made of SuS 304, and 65%Ni-16%Cr-B-
As a result of repeated wear tests for 1000 hours at a high temperature of 850°C (the inside of the vibrator was not cooled and the above was not passed through) with Si thermally sprayed on the outer surface of SuS 304 JPL, As shown in Table 1, the tube of the present invention was proven to have excellent abrasion resistance.

Table 1 Results of abrasion resistance test As mentioned above, the tube of the present invention not only has excellent heat resistance and abrasion resistance, but also has a high heat transfer coefficient, and the heat transfer area of the entire boiler is larger than that of conventional boilers. As a result, equipment costs can be significantly reduced, durability has improved, and high-temperature, high-pressure steam can be produced efficiently.

Procedure-? 10 orthographic) December 5, 1980

Claims (1)

[Claims] 1. Ni-Cr alloy is thermally sprayed on the outside of the steel pipe, or carbon
A heat-resistant and wear-resistant fluidized bed boiler tube made by thermally spraying and fusing o-Ni-Cr-W-B-Si solid solution alloy. 2. The heat-resistant and wear-resistant fluidized bed boiler tube according to claim 1, wherein the steel tube is made of a Cr-Mo steel tube. 3. The heat-resistant and wear-resistant fluidized bed boiler tube according to claim 1, wherein the steel tube is made of an austenitic stainless steel tube.