Flame spray apparatus

Abstract

To provide a flame spray apparatus capable of safely inputting a raw material powder to a hopper even during a flame spray operation, and capable of reducing a height of the hopper.SOLUTION: In a flame spray apparatus for forming a fire-resistant composition by injecting and a burning a mixture of a raw material powder 10 containing a fire resistant powder and an inflammable powder and a combustion supporting carrier gas, a chalk valve 25 that can be opened and closed to partition an inside of the hopper 20 to an upper region including an input port 21a and a lower region including an outputting part 22a.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a thermal spray apparatus for forming a refractory composition. [Background technology]

[0002] Conventionally, thermal spraying devices for forming refractory compositions have been known, which transport and spray raw material powder containing a combustible powder (e.g., metal powder) and a refractory powder (refractory aggregate) using a combustion-supporting carrier gas (oxygen gas), ignite, and melt the powder, thereby forming the refractory composition. As described above, such thermal spraying devices transport and spray raw material powder containing a combustible powder and a refractory powder using a combustion-supporting carrier gas, ignite, and melt the powder. However, because the flame of the mixture of the injected, ignited, and burning raw material powder and carrier gas travels in the opposite direction to the flow of the raw material powder and carrier gas and reaches the hopper storing the raw material powder, a so-called "backfire" can occur. When a backfire occurs, the pressure inside the hopper increases abnormally, causing the raw material powder to blow up inside the hopper (hereinafter referred to as the "raw material powder blow-up phenomenon"), potentially resulting in a fire or explosion, which has been a major problem in thermal spraying.

[0003] Therefore, in Patent Document 1, the inventors disclosed a thermal spraying device that includes a through-hole in a hopper, a blocking member for blocking the through-hole, and a partition mechanism that can open and close the hopper into an upper region including an inlet and a lower region including an outlet. With this thermal spraying device, even if pressure inside the hopper increases, the pressure is released through the through-hole. This eliminates the blow-up phenomenon of raw material powder. Furthermore, when additional raw material powder is added to the hopper during thermal spraying, the open / close damper, which serves as the partition mechanism, is closed to divide the hopper into an upper region including the inlet and a lower region including the outlet. By dividing the hopper into upper and lower regions in this way, even if a backfire or other problem occurs during thermal spraying, the blow-up phenomenon of raw material powder is contained in the lower region and does not reach the upper region. Therefore, raw material powder can be safely added to the hopper even during thermal spraying. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-70939 Summary of the Invention [Problem to be solved by the invention]

[0005] Thermal spraying devices are often used at small construction sites, such as coke oven construction sites. Furthermore, the storage locations of the thermal spraying devices and the passageways leading to the construction sites are often also narrow. Furthermore, there are usually multiple construction sites, and some of these sites are located at different elevations from the storage locations. In such cases, when using the thermal spraying device, it is necessary to manually transport it from the narrow storage location with its different elevations to the small construction site through the narrow passageways. For these reasons, there is a particular demand for miniaturization of thermal spraying devices.

[0006] In this regard, the thermal spraying device of Patent Document 1 uses a vertically rotating open / close damper as a partition mechanism. Therefore, in the thermal spraying device of Patent Document 1, the hopper volume needs to include the volume for storing the raw material powder as well as the volume for the movable range of the vertically rotating open / close damper. This increases the height of the hopper, resulting in an increase in the size of the thermal spraying device. Furthermore, as the height of the hopper increases, the height of the inlet at the top of the hopper also increases, reducing the operability of the work of feeding the raw material powder into the hopper through the inlet. Thus, Patent Document 1 left issues to be resolved in terms of miniaturizing the thermal spraying device, particularly in terms of reducing the height of the hopper.

[0007] The problem to be solved by the present invention is to provide a thermal spraying device that allows raw material powder to be safely added to a hopper even during thermal spraying and that allows the height of the hopper to be reduced. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided the following thermal spraying apparatus. A thermal spraying device for spraying and burning a mixture of raw material powder containing a refractory powder and a combustible powder with a combustion-supporting carrier gas to form a refractory composition, comprising: a hopper for storing the raw material powder and dispensing the raw material powder; a conveying means for mixing the raw material powder discharged from the hopper with the carrier gas and conveying the mixture; and an injection means for injecting the transported mixture, The thermal spraying device further comprises a choke valve that can open and close to separate the inside of the hopper into an upper region including an inlet and a lower region including a discharge outlet. [Effects of the Invention]

[0009] According to the thermal spraying device of the present invention, raw material powder can be safely charged into the hopper even during thermal spraying, and the height of the hopper can be reduced. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a main part of a thermal spraying device according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic perspective view of the main part showing the internal structure (lower region of the hopper) of the thermal spraying device of FIG. [Figure 3] FIG. 4 is a schematic perspective view of the main part showing the internal structure (lower region of the hopper) of a thermal spraying device according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings, in which: Fig. 1 is a cross-sectional view of a main part of a thermal spraying device according to one embodiment of the present invention.

[0012] 1 includes a hopper 20 for storing raw material powder 10, an ejector 30 as a conveying means, and a spraying means 40. The raw material powder 10 contains a combustible powder (e.g., metal powder) and a refractory powder (refractory aggregate).

[0013] The hopper 20 is formed by combining an upper hopper 21 and a lower hopper 22. The upper hopper 21 has an inlet 21a at its top for introducing the raw material powder 10, and the lower hopper 22 has an outlet 22a at its bottom for dispensing the raw material powder 10. The inlet 21a of the upper hopper 21 is provided with a lid member 23 for opening and closing the inlet 21a, and the outlet 22a of the lower hopper 22 is provided with an opening / closing valve 24 for opening and closing the outlet 22a. The hopper 20 is formed by combining the upper hopper 21 and the lower hopper 22 via a choke valve 25.

[0014] The choke valve 25 has the function of dividing the interior of the hopper 20 into an upper region including the inlet 21a and a lower region including the outlet 22a in an openable and closable manner. That is, when the choke valve 25 is closed, the interior of the hopper 20 is divided into an upper region and a lower region, and when the choke valve 25 is opened, the upper region and the lower region are connected to each other. The mechanism of the choke valve 25 itself is well known, and a detailed description thereof will be omitted. However, by tying or untying a rope around the outer periphery of the sleeve valve 25a, which is the opening / closing portion of the choke valve 25, the opening / closing portion opens and closes horizontally, like a lens shutter. In this embodiment, the height of the hopper 20 is reduced by using the choke valve 25, which opens and closes the opening horizontally, as described above, as a dividing mechanism that opens and closes the interior of the hopper 20 into an upper region and a lower region.

[0015] In this embodiment, the sleeve valve 25a, which is the opening / closing portion of the choke valve 25, is preferably made of a sheet material made of a flame-retardant fiber. That is, since the raw material powder may be blown up in a thermal spraying device as described above, the opening / closing portion of the choke valve is preferably made of a sheet material made of a flame-retardant fiber. Examples of flame-retardant fibers include aramid fiber, modacrylic fiber, flame-retardant rayon, flame-retardant cotton, glass fiber, wool, and flame-retardant polyester fiber, but aramid fiber is most preferred from the standpoint of durability, strength, and other characteristics.

[0016] As shown in FIG. 1, the lower region of the hopper 20 includes a tapered section 22b whose diameter decreases toward the discharge outlet 22a. The taper angle α of this tapered section 22b is preferably 40° or more and 70° or less. The raw material powder 10 used in a thermal spraying device contains a large amount of fine combustible powder, and therefore has lower fluidity than ordinary refractory raw material powder. Therefore, it is preferable to set the taper angle α to 70° or less to ensure the fluidity of the raw material powder 10 in the lower region of the hopper 20. On the other hand, if the taper angle α is small, the height of the lower region of the hopper 20 increases accordingly, so the taper angle α is preferably 40° or more.

[0017] In this embodiment, a flow diverter 26A is provided in the lower region of the hopper 20 directly above the discharge outlet 22a. In this embodiment, the flow diverter 26A is formed from a steel material having a triangular cross section as shown in Figures 1 and 2, and has the function of dividing the flow of raw material powder that falls naturally from the upper region of the hopper 20 through the choke valve 25 into multiple flows (two flows in this embodiment). By providing such a flow diverter 26A directly above the discharge outlet 22a, it is possible to prevent the raw material powder that falls naturally from the upper region of the hopper 20 through the choke valve 25 from clogging the discharge outlet 22a. In other words, when the choke valve 25 is used as a partition mechanism that can open and close the inside of the hopper 20 into an upper region and a lower region, as in this embodiment, the flow of raw material powder that falls naturally through the choke valve 25 tends to concentrate in the center of the lower region, i.e., directly above the discharge outlet 22a, and as a result the raw material powder is compressed by the tapered portion 22b where the diameter decreases, making it easy for the discharge outlet 22a to become clogged. However, by providing a flow divider 26A directly above the discharge outlet 22a, the flow of raw material powder is divided into multiple flows, thereby preventing the raw material powder from clogging the discharge outlet 22a.

[0018] In this embodiment (FIGS. 1 and 2), the flow diverter 26A is provided directly above the discharge outlet 22a, but a direction changer 26B may also be provided directly above the discharge outlet 22a, as shown in FIG. 3. In FIG. 3, the direction changer 26B is made of steel plates arranged to form a slope, and has the function of changing the direction of the flow of the raw material powder that falls naturally from the upper region of the hopper 20 through the choke valve 25. By providing the direction changer 26B directly above the discharge outlet 22a in this way, clogging of the discharge outlet 22a with the raw material powder can also be prevented.

[0019] The configurations of the flow diverter 26A and the direction changer 26B are not limited to those shown in the drawings. In short, the flow diverter 26A may be any device that functions to divide the flow of raw material powder naturally falling from the upper region of the hopper 20 through the choke valve 25 into multiple flows, and the direction changer 26B may be any device that functions to change the flow of raw material powder naturally falling from the upper region of the hopper 20 through the choke valve 25. For example, an umbrella-shaped (conical or pyramidal) member may be disposed immediately above the dispensing outlet 22a. The umbrella-shaped member functions both as a flow diverter and a direction changer. Therefore, in the present invention, it is not necessary to clearly distinguish between a flow diverter and a direction changer. In other words, providing a flow diverter or direction changer immediately above the dispensing outlet in the present invention means providing a member that functions as at least one of a flow diverter and a direction changer immediately above the dispensing outlet, thereby preventing the raw material powder from clogging the dispensing outlet.

[0020] 1 again, in this embodiment, a plurality of through holes 27 are provided in the upper parts of the lower hopper 22 and the upper hopper 21, i.e., the upper parts of the lower region and the upper region, respectively. In addition, a spring-hinge type closing plate 28 is provided as a closing member that closes these through holes 27 in an openable and closable manner.

[0021] Next, the configuration after the ejector 30 will be described. The ejector 30 sucks the raw material powder 10 from the discharge port 22a of the hopper 20 by the flow of pressurized carrier gas (oxygen gas), and mixes the carrier gas with the raw material powder 10 to form a mixture. The injection means 40 is connected to the outlet side of the ejector 30 via a horizontal transfer pipe 50 and a rubber hose 60, and injects the mixture produced by the ejector 30.

[0022] The ejector 30 is configured in detail as follows: The ejector 30 includes a container 31 having an internal space communicating with the discharge outlet 22a of the hopper 20, and a tapered ejection nozzle 32 that ejects pressurized carrier gas from its tip into the internal space of the container 31. In other words, in the internal space of the container 31, the carrier gas is ejected at high speed from a nozzle hole at the tip of the tapered ejection nozzle 32 toward one end (the base end) of the horizontal transfer pipe 50, thereby creating a negative pressure (here, a pressure lower than atmospheric pressure) in the internal space of the container 31. Meanwhile, the internal space of the container 31 is connected to the discharge outlet 22a of the hopper 20 via a vertical transfer pipe 70. Therefore, the ejector 30 draws the raw material powder 10 into the internal space of the container 31 through the discharge outlet 22a by the flow of pressurized carrier gas. The carrier gas ejected from the nozzle hole at the tip of the ejection nozzle 32 and the raw material powder 10 are mixed in the internal space of the container 31 to form a mixture.

[0023] In the above configuration, if the pressure inside the hopper 20 increases due to the raw material powder clogging the horizontal transfer pipe 50 or the rubber hose 60, the rubber hose 60 being bent, or a flashback (hereinafter collectively referred to as a flashback, etc.), the pressure is released from the through-holes 27 provided in the lower region, the upper region, or both, depending on the open / close state of the choke valve 25 and the remaining amount of raw material powder 10. That is, the through-holes 27 are normally closed by the spring-hinge type closing plates 28 as shown in FIG. 1, but when the pressure inside the hopper 20 increases, the spring-hinge type closing plates 28 rotate outward due to the pressure, opening the opening, and the pressure is released from the through-holes 27. This eliminates the phenomenon of raw material powder being blown up.

[0024] Furthermore, when additional raw material powder is added to hopper 20 during thermal spraying, choke valve 25 is closed to divide the interior of hopper 20 into an upper region including inlet 21a and a lower region including outlet 22a. By dividing hopper 20 into upper and lower regions in this way, even if a backfire or the like occurs during thermal spraying, the raw material powder will be prevented from being blown upward in the lower region and will not reach the upper region. Therefore, raw material powder can be safely added to hopper 20 even during thermal spraying.

[0025] In this embodiment, once the raw material powder has been charged into the hopper 20, the charging port 21a is closed with the cover member 23 and the choke valve 25 is opened. This allows the charged raw material powder to fall naturally from the upper region to the lower region and then be discharged from the discharge port 22a to the ejector 30, allowing the thermal spraying process to continue without any problems. At this time, in this embodiment, the flow diverter 26A is provided directly above the discharge port 22a, so that the raw material powder 10 that falls naturally from the upper region of the hopper 20 through the choke valve 25 can be prevented from clogging the discharge port 22a.

[0026] As described above, according to this embodiment, raw material powder can be safely charged into the hopper 20 even during thermal spraying. In this embodiment, the height of the hopper 20 can be reduced by using the choke valve 25, which opens and closes the opening horizontally, as described above, as a partition mechanism that opens and closes the interior of the hopper 20 into an upper region and a lower region.

[0027] In this embodiment, the hopper 20 is a split type divided into an upper hopper 21 and a lower hopper 22, but the hopper 20 may also be a normal one-piece type. However, if the hopper 20 is a split type as in this embodiment, the choke valve 25 can be easily installed and replaced, so the split type is preferable.

[0028] In addition, in this embodiment, the ejector 30 is provided as a conveying means, but the present invention is not limited to this. For example, a means for feeding raw material powder (for example, a table feeder, a screw feeder, or the like) may be provided below the hopper 20, and the raw material powder may be fed by this means, and the fed raw material powder may be transported by a carrier gas.

[0029] In addition, in this embodiment, the carrier gas is ejected by the ejection nozzle 32, but the present invention is not limited to this. For example, in addition to the ejection nozzle 32, a mechanism for ejecting the carrier gas downstream of the dispensing outlet 22a or into the hopper 20 may be provided.

[0030] Furthermore, in this embodiment, a spring-hinge type closure plate 28 is provided as a closure member that closes the through-hole 27, and the spring-hinge type closure plate 28 rotates to open the through-hole 27 when pressure increases due to the occurrence of a flashback or the like, but the closure member can also be a member that deforms or disappears when a flashback or the like occurs. Also, although multiple through-holes 27 are provided in this embodiment, only one through-hole may be used. However, it is preferable to provide multiple through-holes in order to efficiently release pressure due to the occurrence of a flashback or the like. Note that the through-hole may be omitted in the present invention. [Industrial Applicability]

[0031] The thermal spraying device of the present invention can be used in industrial furnaces and the like that use combustible metal powder-containing thermal spraying, such as coke ovens, hot stoves, converters, melting furnaces, AOD furnaces, ladles, tundishes, vacuum degassing furnaces, torpedo cars, electric furnaces, incinerators, induction furnaces, heating furnaces, and glass furnaces. [Explanation of symbols]

[0032] 10 Raw material powder 20 Hopper 21 Upper hopper 21a Inlet 22 Lower hopper 22a Payment outlet 22b Tapered section 23 Cover member 24 On-off valve 25 Choke valve 25a Sleeve valve (choke valve opening and closing part) 26A shunt 26B Turner 27 Through hole 28 Spring hinged closure plate (closure member) 30 Ejector (transport means) 31 Container section 32 Spout nozzle 40 Injection means 50 horizontal transfer pipe 60 Rubber Hose 70 Vertical transfer pipe

Claims

1. A thermal spraying device for spraying and burning a mixture of raw material powder containing a refractory powder and a combustible powder with a combustion-supporting carrier gas to form a refractory composition, comprising: a hopper for storing the raw material powder and dispensing the raw material powder; a conveying means for mixing the raw material powder discharged from the hopper with the carrier gas and conveying the mixture; and an injection means for injecting the transported mixture, The thermal spraying device further comprises a choke valve that can open and close to separate the inside of the hopper into an upper region including an inlet and a lower region including a discharge outlet.

2. 2. The thermal spraying device according to claim 1, wherein the opening and closing portion of the choke valve is made of a sheet material made of flame-retardant fiber.

3. The thermal spray device of claim 2 , wherein the flame-retardant fibers are aramid fibers.

4. 3. The thermal spraying device according to claim 1, wherein the lower region of the hopper includes a tapered portion whose diameter decreases toward the discharge outlet, and the tapered portion has a taper angle of 40° or more and 70° or less.

5. 3. The thermal spraying device according to claim 1 or 2, further comprising, in the lower region of the hopper, a flow divider that divides the flow of raw material powder that falls naturally from the upper region of the hopper via the choke valve into multiple flows or a redirector that changes the direction of the flow of the raw material powder, located directly above the discharge outlet.

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