JPS6135467B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flame spray burner, and more particularly to a flame spray burner whose durability is improved by coating the burner nozzle surface with nitride.

In recent years, oxygen spraying has replaced the conventional spraying method as a method of repairing damaged parts of industrial furnaces such as coke ovens and converters.
A flame spraying method has been used in which a powdered refractory spray material is melted in a fuel flame and the molten refractory material is injected and welded to a damaged area of a furnace wall. It is desirable that the burner used for this flame spraying has a combustion chamber, as shown in the figure, and a structure in which combustible gas and combustion-supporting gas are mixed and combusted.
This is because the mixing and combustion of fuel and oxygen in the combustion chamber produces a high flame temperature and a high ejection velocity, which improves the deposition rate of the molten refractory material. Furthermore, there is no risk of backfire. However, since the base material constituting the burner is usually a metal such as copper or stainless steel, there are disadvantages in that the surface of the base material oxidizes during use and the powder refractory sprayed material causes wear on the combustion chamber wall surface. In particular, oxidation of the surface of the base material in the combustion chamber can cause molten powder refractory material to adhere to the surface of the base material, causing significant damage to the flame combustion state. The oxide film on the contact portion impedes the cooling effect of the nozzle forming body, which causes the nozzle forming body to melt and wear away.

In view of the above, the present invention has been developed by coating the inner wall surface of the combustion chamber of the flame spray burner, the inner wall surface of the supply path of the powder refractory spray material, and the contact portion of the nozzle forming body with the water cooling jacket with a non-oxidizing film, especially a nitride. 〓〓〓〓
Therefore, it is an object of the present invention to provide a flame spraying burner which solves the above-mentioned disadvantages and has excellent durability.

The figure shows a cross section of the tip of a flame spraying burner that is an embodiment of the present invention. Reference numeral 1 denotes a nozzle forming body, which is made of metal such as copper or stainless steel, and has a truncated conical cavity 2 that expands forward at its front end, and a fuel-spraying material supply passage 3 at its rear. The truncated cone-shaped cavity 2 is provided with a plurality of combustion-supporting gas injection holes 4, and the combustion-supporting gas injection holes 4 are connected to the truncated-cone-shaped cavity 2 from a combustion-supporting gas supply passage 13, which will be described later. All of the plurality of holes are provided in the front and in the direction converging on the central axis. 5 is the inner wall surface of the truncated conical cavity 2, 6
7 is the tip of the nozzle forming body 1, and 7 is the nozzle forming body 1.
This is the contact portion with the water cooling jacket 8, which will be described later.
A water cooling jacket 8 is made of metal such as copper or stainless steel like the nozzle forming body 1. 9 is a water-cooled jacket outer cylinder, 10 is a water-cooled jacket inner cylinder, 11
12 is the middle cylinder of the water-cooled jacket, and 12 is the tip of the water-cooled jacket, which is an annular plate made of the same material as the outer cylinder 9 and the inner cylinder 10, and the joint with the outer cylinder 9 and the inner cylinder 10 is fixed by a welded part. . Water cooling jacket inner cylinder 1
0 and the fuel/spray material supply passage 3 of the nozzle forming body 1
The annular passage formed by the outer side of the combustion support gas supply passage 13 is used as the combustion-supporting gas supply passage 13. The annular passage formed by the water-cooled jacket outer cylinder 9 and the middle cylinder 11 connects the cooling water outgoing path 14 to the water-cooled jacket inner cylinder 10.
The annular passage formed by the inner cylinder 11 and the inner cylinder 11 provides a cooling water return passage 15. A combustion chamber 17 is formed by the cylindrical cavity 16 formed by the truncated conical cavity 2 and the inner cylinder 10 of the water-cooled jacket 8.
is configured. The inner surface of the inner cylinder 10 of the water-cooling jacket 8 and the contact portion 7 of the water-cooling jacket 8 of the nozzle forming body 1 are configured to be in close contact with each other, so that the nozzle forming body 1 is well cooled by the cooling water while the burner is in use. Prevent overheating and melting. During use, combustible gas and powdered refractory material are supplied from the fuel-sprayed material supply passage 3, and the powdered refractory material is supplied through the combustion-supporting gas supply passage 13 and the combustion-supporting gas injection hole 4. Gas is supplied, the two gases are mixed and combusted in the combustion chamber 17, and the powdered refractory spray material is heated and melted and injected out of the combustion chamber 17. Both gases are normally supplied as described above, but the combustion supporting gas and the thermal spray material may be supplied from the supply passage 3 and the combustible gas may be supplied from the supply passage 13. The above is the same as the burner normally used for flame spraying, but
The burner of the present invention includes the surfaces of the main parts of the nozzle forming body 1, that is, the inner wall surface 5 of the frustoconical cavity 2, the tip 6 of the nozzle forming body, the contact area 7 with the water cooling jacket 8, and the inside of the fuel-sprayed material supply passage 3. The wall surface, etc., is coated with a nitride such as titanium nitride, silicon nitride, or aluminum nitride, thereby solving the drawbacks of the conventional flame spray burner. That is, by coating with nitride, the inner wall surface 5 of the cavity 5, the tip 6, and the contact portion 7 with the water cooling jacket 8 of the nozzle forming body 1 are coated with nitride.
etc. are oxidized by high temperature, and the molten spray material adheres to the inner wall surface 5 and the tip 6 due to the generated oxide film, which disturbs the combustion state and reduces the spray performance, and contact with the water cooling jacket 8. Furthermore, the formation of an oxide film on the inner wall surface 5 of the combustion chamber 17 causes a decrease in thermal conductivity, resulting in insufficient cooling of the nozzle forming body 1 and causing melting loss of the nozzle forming body 1.
We succeeded in preventing wear and other problems by using a powder refractory sprayed material. This is because the base material of the nozzle forming body is copper or stainless steel as described above, and the Bitkers hardness of these is 50 to 160, whereas the Bitkers hardness of the nitride is 2000 to 3000, and the nitride The material has no wettability with the molten sprayed material, and the molten sprayed material does not adhere to the nitride, and the nitride has superior oxidation resistance at high temperatures compared to copper and stainless steel. This is due to reasons such as difficulty in forming an oxide film. Therefore, the first idea would be to use nitride as the base material for the nozzle forming body 1, but as mentioned above, since the hardness is extremely high, there are problems in machining it as a base material for the nozzle forming body 1, which requires precision machining. , and the water-cooling jacket 8 made of copper or stainless steel.
There is a risk that the degree of adhesion of the material will decrease, heat conduction will decrease, and an oxide film will form. In view of the above, the present invention came up with the idea of coating the surface of the main part of the nozzle forming body 1 with a nitride film, and as a result of various experiments,
As mentioned above, 1 to 30% of nitride is applied to the surface of the nozzle forming body.
It has been discovered that the above-mentioned disadvantages can be solved by coating the film with a thickness of 1.mu., preferably in the range of 5 to 15.mu..

Ion nitriding is a nitride coating method.
method, ion plating method, plasma spray method,
Although there are CVD methods, etc., in the above experiment, the coating was performed by ion plating method. That is, the nozzle forming body 1 was used as a cathode, and the evaporated molecules of the nitride were ionized and deposited on the nozzle forming body 1 in a glow discharge of an inert gas at a pressure of about 1 Pa. Various coatings were produced by this method, and thermal spraying experiments were conducted using a burner to which the nozzle forming body 1 was attached, and the results were as follows.

Experimental Example 1 Cavity inner wall surface 5 of the nozzle forming body 1 made of stainless steel, tip portion 6 and contact portion 7 with water cooling jacket 8
was coated with titanium nitride to a thickness of 0.3μ. A thermal spraying experiment was carried out using a flame spraying burner to which this nozzle forming body 1 was attached, by conveying a powder refractory thermal spraying material at a rate of 20 kg/h at a rate of C ₃ H ₈ 5 Nm ³ /h. At this point, the coating on the inner wall surface 5 of the cavity was partially worn, and the sprayed material began to be welded to that part.

Experimental Example 2 Titanium nitride was coated to a thickness of 5 μm under the same conditions as in Experimental Example 1 above. When thermal spraying experiments were conducted under the same conditions, no abnormality was observed on the cavity inner wall surface 5 even after approximately 50 hours of use.

Experimental Example 3 Furthermore, 30% titanium nitride was added under the same conditions as in Experimental Example 1 above.
When a similar thermal spraying experiment was carried out with a coating of μm thick, cracks occurred in the coating. This is thought to be due to the difference in thermal expansion coefficient between the base material stainless steel of the nozzle forming body 1 and titanium nitride.

The above results are representative of the experiments conducted, and it was confirmed from these results that it is effective to coat the film with a thickness in the range of 1 to 30 μm.

The present invention relates to a burner for flame spraying in which the surface of the main part of the nozzle forming body is coated with a film of titanium nitride, silicon nitride, aluminum nitride, etc. to a thickness of 1 to 30μ, that is, the main part of the wall surface of the combustion chamber, powder refractory spraying. This is a flame spray burner in which the material supply passage and the contact area between the nozzle forming body and the water cooling jacket are coated with nitride, which eliminates wear on the inner wall surfaces of the combustion chamber and the like. In addition, oxidation of the coating portion of the nozzle forming body can be prevented, there is no welding of the sprayed material, and furthermore, the cooling effect is not impaired, so it is now possible to prevent melting damage of the nozzle forming body.

[Brief explanation of the drawing]

The figure is a cross-sectional view of a nozzle portion of a thermal spray burner according to an embodiment of the present invention. 1 is a nozzle forming body, 2 is a truncated conical cavity, 3 is a fuel-powder thermal spray material supply passage, 4 is a combustion-supporting gas injection hole, 5 is an inner wall surface of the truncated conical cavity 2, and 6 is a tip of the nozzle forming body 1. , 7 is a contact portion of the nozzle forming body 1 with the water cooling jacket 8, 8 is a water cooling jacket, 13
16 is a combustion-supporting gas supply passage, 16 is a cylindrical cavity, and 17 is a combustion-supporting gas supply passage.
is a combustion chamber formed by a truncated conical cavity 2 and a cylindrical cavity 16. 〓〓〓〓

Claims (1)

[Claims] 1. The inner wall surface of the combustion chamber of the nozzle forming body, the inner wall surface of the powder spray material supply passage, and/or the contact portion with the water cooling jacket is coated with nitride.1
A burner for flame spraying characterized by forming a nitride film with a thickness of 30μ to 30μ. 2. The flame spray burner according to claim 1, wherein the nitride coated is any one of titanium nitride, silicon nitride, and aluminum nitride.