JPH1030801A - Refractory structure for protecting water tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water tube-protecting refractory structure which is designed to prevent breakage of a conventional refractory block through cracking, a decline in heat-transfer efficiency due to an increased thickness of mortar, and high-temperature corrosion of steel bolts and nuts for attachment and fixation. SOLUTION: A water tube-protecting refractory structure is formed by winding on a water tube 11 a thin ribbon-shaped ceramic strip 12 which is advantageous against thermal strain and a decline in heat-transfer efficiency and by fixing such a ceramic strip 12 to the water tube 11 by the use of a fixing means, such as an annular ring or band, in initiating the winding and in ending it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fire protection structure for a water pipe used in a boiler having a water pipe inserted therein, and more particularly to incinerating municipal solid waste and industrial waste, and using the heat of the combustion exhaust gas to generate steam from the boiler. The present invention relates to a refractory structure for protecting a water pipe of a plant for obtaining energy.

[0002]

2. Description of the Prior Art There have been various refractory structures used to protect against heat and corrosive atmosphere from flue gas discharged into a boiler water pipe. An example will be described with reference to FIG. 3. The water pipe 11 is one of a group of boiler water pipes suspended in a combustion gas furnace. The water pipe 11 is covered with a refractory block 22 divided around the water pipe 11. This water pipe 11
The space between the refractory block 22 is filled with a mortar 23. The two refractory blocks are bolts and nuts 24
Are connected integrally.

[0003]

In the conventional refractory structure for protecting a water pipe having such a structure, the refractory block has a relatively high thermal conductivity because it is formed of a ceramic material. Is relatively thick,
With the prior art, maximum heat flow cannot be expected from the combustion gases. Maximum heat flow is important for boiler efficiency.
In addition, since the heat transfer from the refractory block 22 to the water pipe 11 is not performed effectively, the temperature difference between the inside and outside of the refractory block 22 increases, and the temperature on the gas side surface increases. As a result, the difference in thermal expansion between the water pipe 11 side (heat-resistant metal material) and the refractory block (ceramics) increases, and as a result, the thermal stress of the refractory block 22 increases.

Further, when the heat transfer between the refractory block 22 and the water pipe 11 is less than the optimum condition, the temperature of the outer surface of the refractory block 22 rises, and the residual ash (ash) of the burning fuel is increased. ) Melt adheres and forms a heat insulating layer. When the ash begins to adhere, the heat transfer of this layer becomes extremely insufficient, so that the ash 24 is further melt-adhered, and the thickness of the insulating layer is increased, which is a major obstacle to heat transfer. Since the ash 24 contains corrosive components such as chlorine, high-temperature corrosion occurs in the water pipe 11 and damages the water pipe. When the combustion residue ash adheres, the residue ash contains a corrosive component such as chlorine, so that the boiler water pipe 11 is corroded and reduced in thickness through the gap between the two refractory blocks 22. Further, since the bolts and nuts 24 are exposed in the combustion gas, they are easily corroded by the combustion gas,
If such corrosion progresses, the refractory block 22 will be damaged or fall off.

SUMMARY OF THE INVENTION In view of the above technical problems, the present invention has been made to prevent a conventional fire-resistant block from cracking and breaking, to reduce the heat transfer efficiency by thickening the mortar, and to prevent high-temperature corrosion of steel bolts and nuts for mounting and fixing. It is intended to provide a refractory structure for protection.

[0006]

SUMMARY OF THE INVENTION In order to solve these drawbacks, the present invention provides a thin ribbon-shaped refractory thin layer, such as a ceramic strip, which is advantageous for reducing heat distortion and heat transfer efficiency. Winding structure. The fixing of the ceramic strip to the water pipe is performed by fixing the ceramic strip at the beginning and end of the winding with a fixing means such as an annular ring or a band, thereby forming a water pipe protecting refractory structure.

That is, the conventional refractory block is formed to have a predetermined shape and is thick and uneven in thickness, so that it is easily broken by thermal stress. However, the present invention provides a thin and uniform ribbon-shaped refractory block. The water stress is reduced by winding and covering the water tube with a thin layer zone. By winding a ribbon-like thin refractory layer (hereinafter referred to as a ceramic strip) along a thin and uniform water pipe, heat transfer to the water pipe is efficiently performed, and the thermal efficiency of the steam generating plant is increased. Further, the ribbon-shaped ceramic strip is wound around the water pipe, and both ends are fixed by a ring, thereby preventing high-temperature corrosion of the mounting portion.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described specifically. In order to solve the above problems, the present invention employs a configuration in which a ribbon-shaped ceramic strip is wound around a boiler water pipe. By doing so, it is possible to prevent damage to the refractory block and detachment of the mounting portion due to high-temperature corrosion, which have conventionally occurred. These structures are composed of a ribbon-shaped ceramic band and a ring for fixing. For the ribbon-shaped ceramic band, it is preferable to use fine ceramics made of nitride-bonded SiC or oxide-bonded SiC in the form of a thin plate, but not only this, but also long and short fiber whiskers, particles, etc. in metal. FRM (Fiber Reinforced Met), which is excellent in strength, elastic modulus, heat resistance and abrasion resistance, and is lightweight.
al), taking advantage of the heat resistance and wear resistance of ceramics,
Its weakness is reinforced by silicon carbide whiskers, and a whisker reinforced ceramic which is a highly reliable high-temperature strength material, a functionally graded material combining ceramics and metal, and has a surface temperature of 1700 at a thickness of 0.5 to 10 mm.
C. and a temperature gradient of 1000.degree. The ribbon-shaped ceramic strip can be wound tightly around the water pipe by applying a chemical hard or water-soluble hard plastic adhesive between the boiler water pipe and the ceramic strip. The hot water corrosion of the water pipe does not occur because it can be prevented. Such a method is not only easy to install, but also because the ribbon-shaped ceramic band is thin (for example, a thickness of about 0.5 to 10 mm), no excessive thermal stress is generated, and the boiler water pipe can be easily removed. Has an excellent action of high heat transfer efficiency. That is,
According to the present invention, the above configuration not only improves the durability of the boiler water pipe and the ceramic strip covering the boiler water pipe, but also increases the recovery of the combustion energy of the incinerator that burns refuse. Further, the plastic adhesive between the ribbon-shaped ceramic strip and the water pipe is chemically hardened or water-soluble, so that the ceramic strip can be firmly fixed to the boiler water pipe during construction. Due to these effects, even when the boiler water pipe is exposed to a combustion gas having a large amount of corrosive components, the boiler water pipe is extremely less likely to lose its wall thickness due to high-temperature corrosion over a long period of time, and can provide a highly reliable fire-resistant water pipe protection structure.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a water pipe 11 of a plurality of water pipes extending vertically or horizontally to form a water pipe assembly in a combustion chamber of a boiler such as a high temperature incinerator for municipal solid waste or industrial waste. Is shown. As shown in FIG. 1, the outer periphery of the water pipe 11 is wound by a ribbon-shaped thin ceramic band 12. The winding method is such that the upper and lower adjacent ceramic strips 12 are wound so as to polymerize about 1/5 to 1/3 of each other, and a plastic adhesive 13 having a chemical hardening property or a water-hardening property is buried between the two. Fix it. It is preferable to use a heat-resistant material for the plastic adhesive 13. Then, the wound ribbon-shaped ceramic strip 12 is formed.
The winding start 12a and the winding end 12b are fixed by an annular heat-resistant material ring 14. In this embodiment, the heat-resistant material ring 14 is constituted by a shrink-fit heat-resistant material ring 14 which is divided into two pieces. However, the heat-resistant material ring 14 may be constituted by a heat-resistant material ring which is not divided into two pieces or a band body. .

According to this embodiment, the incinerator in which the water pipe is inserted burns municipal waste and industrial waste and generates high-temperature combustion gas, but the steel water pipe 11 is wound by the ribbon-shaped ceramic band 12. Since the water pipe is coated once, high-temperature corrosion of the water pipe caused by the combustion gas can be completely prevented. Also, as described above, since the ribbon-shaped ceramic strip has a thin film structure with a uniform thickness, it has high heat conductivity,
Thermal energy can be effectively transmitted to the water pipe, and overheating of the surface of the ceramic strip is prevented, and ash does not accumulate on the surface on the combustion gas side as in the conventional case, and high heat conductivity can be maintained. Heat transfer to the water pipe is efficient,
The thermal efficiency of the steam generation plant increases. Further, since there are no bolts, nuts, and the like exposed to the combustion gas side as in the conventional case, the occurrence of high-temperature corrosion in that portion is suppressed.

[0011]

As described above, according to the present invention, the following effects can be obtained. (1) The ribbon-shaped ceramic strip of the present invention is thin, light in weight, easy to carry and install, and has low thermal stress during operation and is not easily damaged. (2) Since the ribbon-shaped ceramic strip is thin, the heat transfer of the combustion gas energy to the boiler water pipe is good. (3) In the gap between the ribbon-shaped ceramic strip and the boiler water pipe, a plastic adhesive having chemical or water-soluble hardness is buried, so that it is fixed at the time of construction to form a firm structure. Therefore, there is no invasion of hot corrosive gas, and the life of the boiler water pipe is significantly extended.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a water pipe protecting refractory structure according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA ′ of FIG.

FIG. 3 is a cross-sectional view showing a conventional fireproof block.

FIG. 4 is a sectional view taken along line BB ′ of FIG. 3;

[Explanation of symbols]

 Reference Signs List 11 water pipe 12 ceramic strip 13 plastic adhesive 14 fixing means

Claims (2)

[Claims] In order to protect a water pipe in a boiler against high-temperature corrosion caused by the products of combustion in the boiler, a ribbon-like thin refractory layer is wound around at least a region of the water pipe facing a combustion gas. A fire-resistant structure for protecting water pipes. 2. A water pipe protecting fire-resistant structure, wherein the winding start and the winding end of the ribbon-shaped fire-resistant thin layer belt are fixed to the water pipe by an annular fixing means.