JP7017290B2 - Corrosion resistant furnace wall member - Google Patents

Description

INDUSTRIAL APPLICABILITY The present invention relates to a corrosion-resistant furnace wall member that prevents corrosion due to hydrogen sulfide and the like, and sulfide corrosion cracking, and is particularly suitable for use in a furnace wall member (cooling water pipe) of a convertor portion of a coal gasification furnace.

In thermal power generation equipment and the like, there is a problem that the structural material is corroded by the gas generated when the fuel is burned. For example, the surface of high-temperature heat transfer tubes (furnace wall members) such as boiler water cooling pipes and superheater pipes for thermal power generation and the surface of cooling water pipes (furnace wall members) of the combustor part of coal gasification furnaces are reduced by sulfide corrosion. There was a risk of being fleshed. Further, there is a possibility that groove-shaped corrosion (cracks) may occur in the furnace wall member.

In order to suppress sulfurization corrosion of the furnace wall member, various techniques for coating the surface of the furnace wall member with a corrosion-resistant coating have been conventionally proposed (for example, Patent Document 1). The technique of Patent Document 1 improves sulfurization corrosion resistance by coating titanium oxide particles on the surface of a furnace wall member to form a titanium oxide film. In addition, by coating the surface of the furnace wall member with silicon oxide and forming a titanium oxide film on the surface of the silicon oxide, the occurrence of cracks in the titanium oxide film is prevented and a dense titanium oxide is produced. The technology to obtain is also known.

For example, in a coal gasification furnace, the ash in the charged coal (pulverized coal) is melted in the gasification furnace and discharged as slag, and this high-temperature molten slag adheres to the cooling water pipe (furnace wall member). It will be. Therefore, in general, a silicon compound (silicon carbide, silicon oxide) and an alumina-based refractory material are provided on the furnace wall member (the surface of the corrosion-resistant coating).

On the other hand, when coal burns in the combustor section, lead derived from coal is present in the gas, and it is considered that lead gas affects the refractory material. For example, since lead has a function of lowering the melting point of the silicon oxide component, the fact is that the melting point of the refractory material may be lowered.

Japanese Unexamined Patent Publication No. 9-272990

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a corrosion-resistant furnace wall member capable of preventing corrosion in a state where lead gas does not affect the furnace wall member. And.

The corrosion-resistant furnace wall member of the present invention according to claim 1 for achieving the above object includes a base material forming the furnace wall, a silicon oxide layer formed on the surface of the base material, and the silicon. A titanium oxide layer formed on the surface of the oxide layer and a zirconium oxide layer provided on the surface side of the titanium oxide layer and suppressing a decrease in the melting point of the silicon oxide layer due to lead are provided . The base material is characterized by being a member of a furnace wall that generates a gas containing lead by burning coal .

In the present invention according to claim 1, the silicon oxide layer is formed between the base material and the titanium oxide layer, so that cracks due to internal stress when the titanium oxide layer is formed are prevented from occurring. To. The zirconium oxide layer suppresses the reaction with lead. Since the reaction with lead is suppressed, when a refractory material is provided on the surface, even if the refractory material disappears due to the influence of lead, the influence of lead is prevented from extending to the titanium oxide layer and the refractory function. Can be maintained to prevent corrosion. Moreover, even when the refractory material is not provided on the surface, the zirconium oxide layer acts as a refractory material that does not react with lead, and the decrease in the melting point of the silicon oxide layer due to lead is prevented to prevent corrosion. be able to.

Therefore, it is possible to prevent corrosion in a state where the lead gas does not affect the furnace wall member. It is also possible to form a zirconium oxide layer on the surface of the substrate.

The corrosion-resistant furnace wall member of the present invention according to claim 2 is the corrosion-resistant furnace wall member according to claim 1, wherein an oxide-based ceramic layer or a carbon layer is formed on the surface of the titanium oxide layer. Is formed, and the zirconium oxide layer is provided on the surface side of the oxide-based ceramic layer or the carbon layer.

In the present invention according to claim 2, since the oxide-based ceramic layer or the carbon layer is provided between the titanium oxide layer and the zirconium oxide layer, the component of the base material (for example, Fe) is titanium. It is prevented from diffusing through the oxide layer to the side (surface side) of the zirconium oxide layer.

Further, the corrosion-resistant furnace wall member of the present invention according to claim 3 is the corrosion-resistant furnace wall member according to claim 2, wherein the oxide-based ceramic layer or the surface of the carbon layer is made of second titanium. The oxide layer is formed, and the zirconium oxide layer is formed on the surface of the second titanium oxide layer.

In the present invention according to claim 3, sulfurization corrosion can be prevented by the two titanium oxide layers. The internal stress when the second titanium oxide layer is formed is relaxed by the oxide-based ceramic layer or the carbon layer, and the occurrence of cracks in the second titanium oxide layer is prevented.

Further, the corrosion-resistant furnace wall member of the present invention according to claim 4 is the corrosion-resistant furnace wall member according to any one of claims 1 to 3, wherein the silicon oxide layer is used. The thickness of the titanium oxide layer is 0.01 μm to 10 μm, and the thickness of the zirconium oxide layer is 1 mm to 20 mm (preferably 10 mm).

In the present invention according to claim 4, a corrosion-resistant film can be formed with an appropriate thickness.

Further, the corrosion-resistant furnace wall member of the present invention according to claim 5 is the corrosion-resistant furnace wall member according to any one of claims 1 to 4, wherein the furnace is the base material. The wall member is characterized by being a cooling water pipe constituting the furnace wall of a coal gasification furnace that generates a gas containing lead by burning coal.

According to the fifth aspect of the present invention, corrosion can be prevented in a state where the cooling water pipe constituting the furnace wall of the coal gasification furnace is not affected by the lead gas.

The corrosion-resistant furnace wall member of the present invention can prevent corrosion without being affected by lead gas on the furnace wall member.

It is a schematic block diagram of the coal gasification furnace provided with the corrosion-resistant furnace wall member which concerns on one Embodiment of this invention. It is sectional drawing of the furnace wall member of a converter part. It is an enlarged view of the main part in FIG. It is explanatory drawing which showed the situation of lead.

FIG. 1 shows a schematic state showing the entire coal gasification furnace provided with a cooling water pipe forming the furnace wall as a corrosion-resistant furnace wall member according to an embodiment of the present invention, and FIG. 2 shows a schematic state of the coal gasification furnace. The cross section of the furnace wall member of the combustor part is shown.

As shown in the figure, the coal gasification furnace 1 includes a lower combustor section 2 (combustion chamber) and an upper reducer section 3 (gasification chamber). A burner 4 for supplying pulverized coal is installed in the converter section 2 and the reducer section 3. Further, the combustor unit 2 is provided with a burner 5 for burning the char collected because the reducer unit 3 cannot completely react.

The pulverized coal is burned by the burner 4 of the combustor section 2, and the char is burned by the burner 5, to generate high-temperature heat and supply the heat required for coal gasification to the upper reducer section 3. In the combustor section 2, the charged pulverized coal and char are burned to form a swirling flow and rise to the reducer section 3. At this time, the ash component contained in the pulverized coal and the char is melted, adheres to the furnace wall 11 (wall of the cooling water pipe 12: see FIG. 2) by centrifugal force, becomes molten slag, and flows down to the lower part.

In this way, the furnace wall 11, that is, the wall of the cooling water pipe 12 as a base material is exposed to a high temperature and is exposed to the gas generated by burning coal. Therefore, on the surface of the furnace wall 11, that is, the wall of the cooling water pipe 12 (cooling water pipe 12), a covering material 13 that prevents sulfide corrosion and suppresses the influence of heat of the material of the cooling water pipe 12 is provided. It is provided (corrosion resistant furnace wall member). A refractory material 14 mainly composed of a Si component is provided at an appropriate position on the surface of the covering material 13.

Since the covering material 13 of this embodiment has a fireproof function, the fireproof material 14 can be omitted.

The covering material 13 (corrosion-resistant furnace wall member) will be specifically described with reference to FIGS. 3 and 4.

FIG. 3 shows the detailed situation of the main part in FIG. 2 explaining the situation of the cooling water pipe 12, the covering material 13, and the refractory material 14, and FIG. 4 shows the state showing the state of lead.

As shown in FIG. 3, as the covering material 13, a SiO ₂ layer 21 (a mixture layer of SiO ₂ ) is formed as a silicon oxide layer on the surface of the steel cooling water pipe 12 forming the furnace wall 11. A TIO ₂ layer 22 (a mixture layer of TiO ₂ or the like) is formed on the surface of the SiO ₂ layer 21 as a titanium oxide layer, and an Al ₂ O ₃ layer 23 (Al) as an oxide ceramic layer on the surface of the TIO ₂ layer 22. A mixture layer of _{2O3 and} the like) is formed. The thickness of the SiO ₂ layer 21 and the TiO ₂ layer 22 is preferably in the range of 0.01 μm to 10 μm.

By forming the Al ₂ O ₃ layer 23, the internal stress when the TiO ₂ layer 22 is formed is relaxed, and the occurrence of cracks in the Al ₂ O ₃ layer 23 can be suppressed. Further, the components of the cooling water pipe 12 (for example, Fe) are prevented from diffusing toward the surface side. It is also possible to provide a carbon layer instead of the Al ₂ O ₃ layer 23.

A TiO ₂ layer 24 is formed on the surface of the Al ₂ O ₃ layer 23 as a second titanium oxide layer, and a ZrO ₂ layer 25 is formed on the surface of the TiO ₂ layer 24 as a zirconium oxide layer that suppresses the reaction with lead. It is formed. The thickness of the ZrO ₂ layer 25 can be set in the range of 1 mm to 20 mm, and is preferably set in the range of 1 mm to 10 mm.

It is also possible to omit the Al _{2O 3} layer 23 and the TiO ₂ layer 24 (second titanium oxide layer) and form the ZrO ₂ layer 25 on the surface of the TiO ₂ layer 22.

A Si-based refractory material 14 is provided at an appropriate position on the surface of the ZrO ₂ layer 25 (for example, a portion around the pipe). The refractory material 14 can maintain the cooling effect of the cooling water flowing through the cooling water pipe 12.

In the corrosion-resistant furnace wall member described above, the SiO ₂ layer 21 is formed between the cooling water pipe 12 and the TiO ₂ layer 22, and further, the Al _{2O 3} layer 23 is formed between the TiO ₂ layer 22 and the ZrO ₂ layer 25. And the TiO ₂ layer 24 (second titanium oxide layer) is formed, so that the generation of cracks due to internal stress when the TiO ₂ layers 22 and 24 are formed is prevented, and the two titanium oxide layers (2 layers of titanium oxide layer) are formed. The TIM ₂ layers 22, 24) can prevent sulfide corrosion of the cooling water pipe 12.

When coal burns in the convertor section 2 (see FIG. 1), lead derived from coal is present in the gas, and it is considered that lead gas affects the refractory material 14. For example, as shown in FIG. 4, since lead has a function of lowering the melting point, it is conceivable that the melting point of the refractory material 14 is lowered by reacting with the refractory material 14.

Since the ZrO ₂ layer 25 is present in the corrosion-resistant furnace wall member described above, as shown in FIG. 4, lead (gas phase) 29 infiltrates into the refractory material 14 (dotted line in the figure). (Indicated by the arrow), even if the lead layer 30 is formed on the surface of the ZrO ₂ layer 25, or a part of the refractory material 14 disappears (indicated by the alternate long and short dash line in the figure), the reaction with lead Is suppressed.

Since the reaction of the furnace wall member with lead 29 is suppressed, even if the refractory material 14 disappears due to the influence of lead 29 (part or all), the influence of lead 29 extends to the TiO ₂ layers 22 and 24. This can be prevented and the fireproof function of the zirconia oxide can be maintained to prevent corrosion.

Even when the refractory material 14 is not provided, the ZrO ₂ layer 25 acts as a refractory material that does not react with lead 29, and the melting point of the covering material 13 is prevented from being lowered by the lead 29, so that the cooling water pipe 12 can be used. Corrosion can be prevented.

Therefore, it is possible to prevent corrosion in a state where the member (cooling water pipe 12) constituting the furnace wall 11 is not affected by the lead gas.

The above-mentioned embodiment has been described with reference to an example in which the corrosion-resistant furnace wall member is used for the member (cooling water pipe 12) of the furnace wall 11 of the combustor portion 2 of the coal gasification furnace 1, but coal is burned. It can also be applied to the furnace wall member of a boiler that produces steam.

INDUSTRIAL APPLICABILITY The present invention can be used in the industrial field of corrosion-resistant furnace wall members that prevent corrosion due to hydrogen sulfide and the like and sulfide corrosion cracking.

1 Coal gasification furnace 2 Combustor part 3 Reducer part 4, 5 Burner 11 Furnace wall 12 Cooling water pipe 13 Covering material 14 Refractory material 21 SiO ₂ layer 22, 24 TIO ₂ layer 23 Al ₂ O ₃ layer 25 ZrO ₂ layer 29 Lead 30 Lead layer

Claims (5)

The base material that forms the furnace wall and
The silicon oxide layer formed on the surface of the base material and
The titanium oxide layer formed on the surface of the silicon oxide layer and
A zirconium oxide layer provided on the surface side of the titanium oxide layer and suppressing a decrease in the melting point of the silicon oxide layer due to lead is provided .
The base material is a member of the furnace wall that generates a gas containing lead by burning coal.
Corrosion resistant furnace wall member. In the corrosion-resistant furnace wall member according to claim 1,
An oxide-based ceramic layer or a carbon layer is formed on the surface of the titanium oxide layer, and the oxide-based ceramic layer or carbon layer is formed.
A corrosion-resistant furnace wall member, characterized in that the zirconium oxide layer is provided on the surface side of the oxide-based ceramic layer or the carbon layer. In the corrosion-resistant furnace wall member according to claim 2,
A second titanium oxide layer is formed on the surface of the oxide-based ceramic layer or the carbon layer, and the second titanium oxide layer is formed.
A corrosion-resistant furnace wall member, characterized in that the zirconium oxide layer is formed on the surface of the second titanium oxide layer. The corrosion-resistant furnace wall member according to any one of claims 1 to 3.
The thickness of the silicon oxide layer and the titanium oxide layer is 0.01 μm to 10 μm.
A corrosion-resistant furnace wall member having a zirconium oxide layer having a thickness of 1 mm to 20 mm. The corrosion-resistant furnace wall member according to any one of claims 1 to 4.
The member of the furnace wall, which is the base material, is a corrosion-resistant furnace wall member, which is a cooling water pipe constituting the furnace wall of a coal gasification furnace that generates a gas containing lead by burning coal.

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