JPH093520A - Double tube type powder injection nozzle - Google Patents

Abstract

(57) [Summary] [Purpose] A powder whose inner surface has excellent wear resistance, high mechanical strength, and in which each layer of the inner tube forming the nozzle is firmly fixed even during use. To provide a body-blowing nozzle. An inner pipe for blowing a powder-containing fluid and an outer pipe for forming a flow path of a cooling gas for cooling the inner pipe on the outer circumference of the inner pipe, the inner pipe being An inner layer made of fired ceramic, an intermediate layer made of a cushioning material, and an outer layer made of a unidirectional shape memory alloy are laminated in this order from the inner surface side, and by the tightening force by the shape memory of the unidirectional shape memory alloy used for the outer layer, A double-tube type powder injection nozzle having a three-layer structure in which an inner layer, an intermediate layer and an outer layer are integrated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double tube type powder blowing nozzle. More specifically, the present invention relates to a double-tube powder injection nozzle for injecting a non-oxidizing fluid containing abrasive powder into a molten metal.

[0002]

2. Description of the Related Art Conventionally, when a non-oxidizing fluid containing abradable powder is blown into a molten metal, a powder blowing nozzle has been used. Therefore, there is a problem that the inner surface of the inner tube is worn.

Therefore, in order to solve such a problem, as a powder blowing nozzle, a nozzle in which a ceramic coating is formed on the inner surface of an inner tube by thermal spraying (Japanese Patent Laid-Open No. 58-100).
No. 613), a nozzle in which a ceramic pipe is fitted and inserted into the inner surface of the inner tube (Japanese Patent Laid-Open No. 58-100616), and the like.

However, since the ceramic coating formed by thermal spraying on the inner surface of the inner tube of the former nozzle is inferior in mechanical strength, it is easily peeled off and inferior in long-term durability.

In the latter nozzle, the coefficient of thermal expansion of the metal pipe forming the inner tube is larger than that of the ceramic pipe, so that the metal pipe loses the holding power of the ceramic pipe during use and gas And the force that pushes out the ceramic pipe generated when the powder is conveyed exceeds the frictional force generated at the interface between the ceramic pipe and the metal pipe, the phenomenon of the ceramic pipe coming off, and the nozzle that has lost the ceramic pipe that is an abrasion resistant material, There is a problem that it cannot be used for a long time due to wear.

As a nozzle for solving the problems of the above-mentioned nozzle, a ceramics tube is inserted inside a metal tube made of a unidirectional shape memory alloy with a buffer layer interposed between the ceramic tube and the ceramics by the shape recovery force of the metal tube. There has been proposed a powder / particle injection nozzle composed of a composite tube in which the tubes are fixed (JP-A-3-
137068).

In the above-mentioned powder and granule blowing nozzle, the inner surface of the inner tube is surely excellent in abrasion resistance and has a large mechanical strength, but the metal tube is overheated to a high temperature during use, There is a problem that the shape memory property of the tube is lost, the ceramic tube is not held by the metal tube, and the ceramic tube is pulled out in the same manner as described above, so that it cannot be used for a long period of time. Moreover, since it is difficult to industrially manufacture a long pipe, it is necessary to connect a large number of short pipes. It has the disadvantage of having to be reinforced because of its weakness.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and the inner surface of the inner tube is excellent in abrasion resistance, has high mechanical strength, and constitutes a nozzle. An object of the present invention is to provide a powder blowing nozzle in which each layer of the inner tube is firmly fixed even during use.

[0009]

According to the present invention, an inner pipe for blowing a powder-containing fluid and an outer pipe for forming a cooling gas passage for cooling the inner pipe on the outer circumference of the inner pipe. And a unidirectional shape used for the outer layer, wherein the inner tube is formed by laminating an inner layer made of a fired ceramic, an intermediate layer made of a cushioning material, and an outer layer made of a unidirectional shape memory alloy in this order from the inner surface side of the inner tube. The present invention relates to a double-tube powder injection nozzle having a three-layer structure in which an inner layer, an intermediate layer, and an outer layer are integrated by a tightening force due to the shape memory of a memory alloy.

[0010]

OPERATION AND EXAMPLES As described above, the double-tube type powder-blowing nozzle of the present invention comprises the inner tube for blowing the powder-containing fluid and the cooling gas passage for cooling the inner tube. An inner tube made of a fired ceramic in order from the inner surface side of the inner tube, and an outer tube for forming on the outer circumference of the inner tube.
An intermediate layer made of a cushioning material and an outer layer made of a unidirectional shape memory alloy are laminated, and the inner layer, the intermediate layer and the outer layer are integrated by a tightening force of the shape memory of the unidirectional shape memory alloy used for the outer layer. It is characterized by having a three-layer structure.

In the double tube type powder injection nozzle of the present invention, since the inner tube has the above-mentioned three-layer structure,
The inner surface of the inner tube has excellent wear resistance and mechanical strength,
In addition, there is an advantage that each layer forming the inner tube is firmly fixed even during use.

The inner tube is used to blow a powder-containing fluid, and in order from the inner surface side thereof, an inner layer made of fired ceramic, an intermediate layer made of a cushioning material, and a unidirectional shape memory alloy. Composed of outer layers.

Since the inner layer made of the fired ceramic has a dense structure, it is superior in abrasion resistance, mechanical strength and peeling resistance as compared with the conventional ceramic coating formed by thermal spraying. Have.

The inner diameter of the inner layer is determined by the powder supply amount and the carrier gas flow rate, and is not particularly limited. Usually, it is preferably set appropriately according to the powder supply amount and the carrier gas flow rate. .

Examples of the fired ceramics include alumina-based ceramics containing silicon and aluminum as main components, sialon and the like.

A fired ceramic pipe is usually used as the inner layer made of the fired ceramic. Among the above-mentioned fired ceramic pipes, a highly wear-resistant ceramic pipe made of, for example, sialon can be preferably used in the present invention.

In order to firmly fix the inner layer made of the fired ceramic and the outer layer made of a unidirectional shape memory alloy, which will be described later, the joining surfaces of the two must be in close contact so that the contact area is as large as possible. .

Since the inner layer is composed of fired ceramic, its surface is very rough. In order to increase the contact area between the inner layer and the outer layer, (a) a method of increasing the shrinkage ratio of the unidirectional shape memory alloy used in the outer layer, and (b) the outer surface of the inner layer and the inner surface of the outer layer are There is a method of finishing with high precision. Of these methods, (a) above
In the method, if the shrinkage rate of the one-way shape memory alloy of the outer layer is excessively large, the inner layer may be damaged,
Further, the method (b) is disadvantageous because it is difficult to finish the surface with high precision and it takes a long time to finish the surface.

On the other hand, in the present invention, the intermediate layer made of the cushioning material is used between the inner layer and the outer layer, and the outer layer of the outer layer and the inner surface of the outer layer are not required to have high accuracy, but the outer layer is By the compressive force of the unidirectional shape memory alloy used for, the intermediate layer follows the outer surface shape of the inner layer and the inner surface shape of the outer layer, so that the intermediate layer is between the inner layer and the outer layer, Form a tight interface.

The intermediate layer made of the cushioning material deforms when the unidirectional shape memory alloy used for the outer layer is tightened by shape memory, and absorbs excessive stress applied to the inner layer. Therefore, the collapse of the inner layer is prevented.

As the cushioning material used for the intermediate layer,
Examples include copper, lead and various resins.

The intermediate layer may be formed by winding a band-shaped, string-shaped or thread-shaped cushioning material around the outer periphery of the inner layer so as to have a predetermined thickness, or by previously forming the cushioning material into a cylindrical shape. It may be formed by inserting the tubular body into the outer periphery of the inner layer. Among these, the intermediate layer in which the cushioning material is formed in a tubular shape in advance has an advantage that it can be accurately manufactured in the length direction. From these, as the intermediate layer used in the present invention, copper,
A pipe made of a cushioning material such as lead or resin is preferable.

The thickness of the intermediate layer is preferably about 0.5 to 1 mm in order to prevent the inner layer from being crushed and to sufficiently develop the tightening force of the outer layer.

The outer layer made of the unidirectional shape memory alloy is used for fixing the inner layer formed by split molding.

Conventionally, a metal pipe is used as the outer layer, and a ceramic pipe is mechanically joined as the inner layer by shrink fitting. However, if there is a temperature change in the operating environment of the nozzle, it is Due to the difference in the coefficient of thermal expansion of the ceramic pipe, the inner diameter of the metal pipe becomes larger than the outer diameter of the ceramic pipe, and the divided ceramic pipe is displaced due to the pressure of the carrier gas, and the ceramic pipe comes out. There's a problem.

On the other hand, in the present invention, the metal pipe and the ceramic pipe are integrated with each other by not using a means such as shrink fitting, but tightening the outer layer made of the unidirectional shape memory alloy by shape memory. I am using
Even if there is a temperature change within the temperature range from room temperature to the design temperature (maximum temperature when the shape retention force of the shape memory alloy is maintained), a constant tightening force with almost no change can be obtained. .

As the outer layer made of the unidirectional shape memory alloy, for example, a metal tube made of a unidirectional shape memory alloy is used. The metal tube is subjected to shape memory treatment so that its diameter is reduced by heating.

The thickness of the outer layer made of the unidirectional shape memory alloy is 2 to 3.5 in terms of mechanical strength and cooling properties.
It is preferably about mm. The difference (clearance) between the inner diameter of the outer layer and the outer diameter of the intermediate layer is preferably about 1 to 2 mm when the outer layer and the intermediate layer are laminated.

In the inner tube used in the present invention, an intermediate layer made of a cushioning material is inserted inside a cylindrical outer layer made of, for example, a unidirectional shape memory alloy, and an inner layer made of fired ceramic is placed inside the intermediate layer. By inserting, the inner layer, the intermediate layer and the outer layer are laminated, and by heating the whole or the outer layer, the tightening force by the shape memory of the unidirectional shape memory alloy used for the outer layer is expressed, and the inner layer, the intermediate layer Obtained by combining the layers and the outer layers.

An outer pipe is provided on the outer periphery of the inner pipe in order to form a cooling gas flow path for cooling the inner pipe.

One feature of the present invention is that the outer tube is provided on the outer circumference of the inner tube.

When the outer tube is not provided on the outer circumference of the inner tube, the inner layer, the intermediate layer and the outer layer of the inner tube are integrated by the tightening force by the shape memory of the one-way shape memory alloy used for the outer layer. When the inner tube, especially its outer layer, is heated during use to a temperature higher than the design temperature of the unidirectional shape memory alloy, the tightening force by the outer layer is reduced, and as a result, Similar to the case where only the conventional shrink fitting is performed, the position shift and the omission of the split-molded inner layer occur.

On the other hand, in the nozzle of the present invention, the outer tube is provided on the outer circumference of the inner tube, and the flow path of the cooling gas for cooling the inner tube is formed between the outer tube and the outer tube. Overheating of the inner pipe can be prevented by passing the cooling gas through the flow path.

The cooling gas flow path provided between the inner pipe and the outer pipe has a groove formed in advance in the longitudinal direction by a milling machine, for example, on the outer periphery of the inner pipe, that is, the outer layer, and then the inner pipe is formed. It may be a passage formed by inserting it inside the outer pipe, and a space is provided between the inner circumference of the outer pipe and the outer circumference of the inner pipe, and a spacer is inserted in the space to hold the space. However, the void may be used as the flow path of the cooling gas.

As the outer tube, for example, SUS30
4, a pipe made of a flame-retardant metal such as stainless steel such as SUS310S, SUS430. The wall thickness of the pipe is preferably about 1.5 to 2.5 mm from the viewpoint of improving mechanical strength and cooling properties.

As the cooling gas that can be ventilated in the cooling gas passage, it is preferable to use a cooling gas having a high contact cooling capacity. Typical examples of such cooling gas include gases such as LPG, nitrogen gas, carbon dioxide gas, and hydrocarbon gas.

As described above, the nozzle of the present invention is provided with the outer pipe, and the cooling gas flow passage is formed between the outer pipe and the inner pipe. By venting the cooling gas to the outer layer, it is possible to prevent the outer layer of the inner tube from being overheated. Further, in general, when a short ceramic pipe is connected to form an inner layer of the inner tube, the mechanical strength of the joint is low, so that it is weak against the stress from the side direction. Since the outer tube is provided on the outer circumference of the tube, it has a mechanical strength sufficient to withstand the above stress.

The double-tube powder injection nozzle of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic perspective view of a double pipe type powder injection nozzle 1 of the present invention, and FIG. 2 is an enlarged sectional view taken along the line AA of FIG.

In FIG. 2, an outer tube 6 is provided on the outer circumference of an inner tube 5 in which an inner layer 2 made of fired ceramic, an intermediate layer 3 made of a cushioning material, and an outer layer 4 made of a unidirectional shape memory alloy are sequentially laminated. Has been. The inner layer 2, the intermediate layer 3, and the outer layer 4 are integrated by the tightening force by the shape memory of the unidirectional shape memory alloy used for the outer layer 4. Inside the inner layer 2, a passage 7 for injecting a powder-containing fluid is provided.
Is provided between the inner pipe 5 and the outer pipe 6, and a flow path 8 for cooling gas for cooling the inner pipe 5 is provided. As shown in FIG. 2, the flow path 8 can be provided by forming a vertical groove in the outer layer 4 of the inner tube 5 by machining using a milling machine or the like.

Next, the double-tube type powder blowing nozzle of the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1 The nozzle shown in FIG. 1 was used. That is, the inner diameter 15.
An intermediate layer 3 was formed by using a fired ceramic pipe (material: sialon) having a thickness of 5 mm and a thickness of 2 mm as the inner layer 2 and inserting the fired ceramic pipe into a copper pipe having a thickness of 0.5 mm as a buffer material. . The outer diameter of the mid layer 3 was 20.5 mm.

Next, as the outer layer 4, a pipe made of an iron-based unidirectional shape memory alloy (28% by weight of manganese, 6% silicon).
% By weight, 6% by weight of chromium, balance iron, inner diameter 22.5 mm,
After using the estimated inner diameter of 20.5 mm and the height of the convex portion of the slit on the inner surface of 0.9 mm) to heat the pipe to increase its diameter, a laminate of the inner layer 2 and the intermediate layer 3 is obtained. And then cooled to reduce the diameter of the pipe to the original diameter, and the inner layer 2, the intermediate layer 3 and the outer layer 4 are integrated by the tightening force by the shape memory of the unidirectional shape memory alloy. Tube 5 was formed.

As the outer pipe 6, a stainless steel pipe (SU
S304, inner diameter 26.7 mm) was used, and the inner pipe 5 was inserted into the pipe to obtain the double-pipe type powder blowing nozzle 1.

The obtained nozzle 1 is installed on the bottom of the converter type melting furnace, and 20 to 1 of pulverized coal is used by using nitrogen gas as a carrier fluid.
It is blown from the passage 7 at a conveying speed of 20 kg / mim, and at the same time, the flow rate of LPG in the passage 8 is 10 to 40 Nm ³ / h.
It was made to flow at r and cooled from the rear end to the front end of the nozzle 1.

After 5 minutes from the start of operation, the tip temperature of the nozzle 1 was measured by a thermocouple and found to be about 300.degree. This was significantly lower than the upper limit of the shape memory retention temperature (550 to 600 ° C.), and no trouble was observed during operation.

A large amount of pulverized coal-containing gas was made to flow from the passage 7 of the inner tube 5, but the molten iron solidified material (so-called mushroom) was less generated at the tip of the nozzle 1, and the gas flow rate hardly changed. It was

Comparative Example 1 In Example 1, the flow path 8 between the inner pipe 5 and the outer pipe 6 was used.
Nozzle 1 was operated in the same manner as in Example 1 except that LPG was not ventilated by blocking.

When 5 minutes passed after the operation, the tip temperature of the nozzle 1 was measured by a thermocouple in the same manner as in Example 1, and it was about 900 ° C., which was much higher than the upper limit of the shape memory retention temperature of the outer layer, After several uses, the detachment of the ceramic pipe was confirmed with an endoscope.

Example 2 The same nozzle 1 as that used in Example 1 was prepared, the nozzle 1 was operated in the same manner as in Example 1, and the characteristics of the nozzle 1 were examined according to the following methods. Table 1 shows the results.
Shown in

(A) Average Nozzle Life The nozzle 1 is operated, a measuring rod is periodically inserted into the nozzle 1, and the time required to reach the usage limit (20% of the initial length) of the nozzle 1 is measured. To do.

(B) Abrasion state of the inner surface of the nozzle After operating for 3000 hours, the nozzle 1 is sliced into
Examine the difference between the inner diameter and the initial inner diameter.

(C) Presence / absence of separation of inner layer of nozzle It is checked whether or not the pressure indicated by the pressure gauge installed in the nozzle 1 fluctuates during the operation for 3000 hours.

When the inner layer 2 is separated, the nozzle 1
A sharp drop in pressure is observed as the diameter of the rises sharply.

Comparative Example 2 In Example 2, instead of the pipe made of an iron-based unidirectional shape memory alloy as the outer layer 4, a conventional stainless steel (SUS304) pipe (inner diameter 21 mm, outer diameter 25 m) was used.
m) was used to heat the pipe, and then the laminate of the inner layer 2 and the intermediate layer 3 was inserted and cooled to integrate the inner layer 2, the intermediate layer 3 and the outer layer 4, and In the same manner, a double tube type powder blowing nozzle was obtained.

The characteristics of the obtained nozzle were examined in the same manner as in Example 2. Table 1 shows the results.

[0057]

[Table 1]

From the results shown in Table 1, in the nozzle obtained in Example 2, there was no separation of the inner layer, the melting rate was low,
It can be seen that it has a long life.

[0059]

EFFECTS OF THE INVENTION In the double-tube type powder injection nozzle of the present invention, the inner surface of the inner tube is excellent in abrasion resistance, the mechanical strength is large, and each layer of the inner tube constituting the nozzle is used. Since it is firmly fixed even in the above, it has excellent durability and a long life.

Further, since the double-tube type powder injection nozzle of the present invention has a double-tube structure, it has excellent durability against the stress from the radial direction and, in spite of being thickened, it is resistant to melting. It has excellent fragility.

Therefore, the double-tube type powder-blowing nozzle of the present invention has excellent convenience in transportation and construction, and has an inner tube and an outer tube made of a unidirectional shape memory alloy which is not susceptible to temperature rise. It has an advantage that it can be cooled by two systems of the outer tube.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a double-tube type powder blowing nozzle according to the present invention.

FIG. 2 is an enlarged cross-sectional view taken along the line AA of the double-tube powder injection nozzle shown in FIG.

[Explanation of symbols]

 1 Double-tube type powder injection nozzle 2 Inner layer 3 Middle layer 4 Outer layer 5 Inner tube 6 Outer tube 8 Cooling gas flow path

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Kumazawa 1 Fujimachi, Hirohata-ku, Himeji-shi, Hyogo Nippon Steel Corporation Hirohata Works

Claims (4)

[Claims] 1. An inner tube for blowing a powder-containing fluid,
And an outer tube for forming a flow path of cooling gas for cooling the inner tube on the outer circumference of the inner tube, the inner tube being an intermediate layer consisting of an inner layer made of fired ceramic and a cushioning material in order from the inner surface side thereof. Layer and an outer layer composed of a unidirectional shape memory alloy are laminated, and a three-layer structure in which the inner layer, the intermediate layer and the outer layer are integrated by the tightening force of the shape memory of the unidirectional shape memory alloy used for the outer layer is formed. A double-tube type powder injection nozzle characterized by having. 2. The double-tube type powder injection nozzle according to claim 1, wherein the inner layer made of the fired ceramic is a highly abrasion-resistant ceramic pipe. 3. The double-tube type powder injection nozzle according to claim 1, wherein the intermediate layer is a pipe made of copper, lead or resin. 4. The double-tube type powder injection nozzle according to claim 1, wherein the outer tube is a pipe made of a flame-retardant metal.