JP2015113490A - Spray coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spray coating apparatus capable of preventing the occurrence of a fire in the case of performing a much injection.SOLUTION: A spray coating apparatus comprises a plurality of put-out parts for putting out material powder, to each of which there are connected mixture production means for mixing material powder put out from said put-out parts and a carrier gas are mixed into a mixture, and injection means 40 for injecting the mixture produced by the mixture production means. Injection ports 41 of those injection means 40 have a center distance of 1.4 to 5.3 times as large as the internal diameter of the injection ports 41.

Description

  The present invention relates to a thermal spraying device for forming a refractory composition.

  Conventionally, as a thermal spraying apparatus for forming a refractory composition, a raw material powder containing a flammable powder (for example, a metal powder) and a refractory powder (a refractory aggregate) is used as a combustion-supporting carrier gas ( There is known a thermal spraying apparatus that forms a refractory composition by being transported, injected, and ignited and melted by oxygen gas (for example, Patent Document 1).

  Specifically, in Patent Document 1, carrier gas is guided into an ejector by an ejection nozzle, raw material powder and carrier gas are mixed in the ejector, and the mixed mixture is guided downstream along a flow path, and an injection unit. Describes a technique for injecting a mixture and combusting the injected mixture to form a refractory composition.

  As another thermal spraying technique, a technique for repairing a refractory lining by a flame gunning method (flame spraying method) is known (for example, see Patent Document 2). Specifically, Patent Document 2 describes a technique of performing thermal spraying by inserting a lance from the bottom to the top of the furnace.

JP2013-043141A JP 58-43385 A

  In such a thermal spraying technique, in order to efficiently and quickly form a target refractory composition, it is necessary to inject a large amount of the raw material powder from which the refractory composition is based. Further, when a large amount of raw material powder is injected, the heap width on the work surface is small, and the injected raw material powder needs to be smoothly applied to the work surface. Here, the heap width means the maximum length of the width of the welded portion on the work surface when the raw material powder is sprayed onto the work surface. The larger the heap width, the smaller the amount of welding per unit area of the work surface, so the heap width needs to be small. Hereinafter, in this specification, the injection that achieves smooth construction with a large injection amount of the raw material powder and a small heap width is referred to as mass injection. In order to perform mass injection, it is effective to increase the ratio of the raw material powder in the mixture (hereinafter referred to as “solid-gas ratio”). However, if the solid-gas ratio is increased, the frequency of friction between the raw material powders increases, and the risk of causing ignition increases.

  Therefore, the problem to be solved by the present invention is to provide a thermal spraying device capable of preventing the occurrence of ignition when mass injection is performed.

  According to one aspect of the present invention, a thermal spraying apparatus that forms a refractory composition by injecting and burning a mixture of a raw material powder containing a refractory powder and a combustible powder, and a carrier-supporting carrier gas. A plurality of dispensing units for dispensing the raw material powder, and each of the dispensing units mixes the raw material powder dispensed from the dispensing unit and the carrier gas to form the mixture, and And an injection means for injecting the mixture generated by the mixture generation means, and the distance between the centers of the injection ports of these injection means is not less than 1.4 times the inner diameter of the injection port and is 5.3. A thermal spraying device that is less than double is provided.

  In this invention, it is preferable that the injection direction of the said injection means is 50 to 95 degree | times with respect to the straight line which connects between the centers of the said injection opening.

  According to the present invention, the solid-gas ratio is increased by providing a plurality of dispensing sections for dispensing the raw material powder, connecting the ejection means to each dispensing section, and optimizing the arrangement of the ejection ports of each ejection means. Mass injection can be performed. Moreover, since it is not necessary to increase the solid-gas ratio, the occurrence of ignition can be prevented.

It is a conceptual diagram which shows one Embodiment of the thermal spraying apparatus of this invention. It is sectional drawing which shows the structural example of a thermal sprayer main body. It is explanatory drawing which shows the positional relationship of the injection outlet of an injection means. It is explanatory drawing which shows the injection direction of an injection means. It is a conceptual diagram which shows the principal part of other embodiment of the thermal spraying apparatus of this invention. It is explanatory drawing which shows the concept of a heap width.

  FIG. 1 is a conceptual diagram showing an embodiment of the thermal spraying apparatus of the present invention. The thermal spraying apparatus shown in the figure has two thermal sprayer main bodies 10, and the spraying means 40 is connected to each thermal sprayer main body 10 via a transport hose 20 and a lance 30. Each injection means 40 has an injection port 41. These injection ports 41 are arranged in parallel in the horizontal direction and have the same inner diameter.

  FIG. 2 is a cross-sectional view showing a configuration example of the thermal sprayer main body 10. The thermal sprayer main body 10 shown in the figure includes a hopper 11 as a storage means for storing the raw material powder A and an ejector 12 as a mixture generating means.

  The raw material powder A includes combustible powder (for example, metal powder) and refractory powder (refractory aggregate). The hopper 11 has a dispensing part 11a for dispensing the raw material powder A at the bottom. The ejector 12 sucks the raw material powder A from the dispensing part 11a by the flow of pressurized carrier gas (oxygen gas), and mixes the carrier gas and the raw material powder A to form a mixture.

  The ejector 12 includes a container part 12a having an internal space communicating with the dispensing part 11a at the bottom of the hopper 11, a tapered jet nozzle 12b for jetting pressurized carrier gas from the tip to the internal space of the container part 12a, and a container part A discharge conduit 12c is provided which has one end communicating with the internal space of 12a and guides the mixture from the one end to the other end along the flow path. That is, in the internal space of the container portion 12a, the carrier gas is ejected at a high speed from the nozzle hole at the distal end of the tapered ejection nozzle 12b toward one end (base end) of the discharge conduit 12c, whereby the internal space of the container portion 12a is discharged. Negative pressure (here, pressure lower than atmospheric pressure) is set. On the other hand, the dispensing part 11a of the hopper 11 communicates with the internal space of the container part 12a via the vertical transfer pipe 11b. For this reason, the ejector 12 sucks the raw material powder A from the dispensing part 11a into the internal space of the container part 12a by the flow of the pressurized carrier gas, and ejects the carrier gas and the raw material powder from the nozzle hole at the tip of the ejection nozzle 12b. A is mixed in the internal space of the container portion 12a to form a mixture.

  This mixture is supplied to the conveying hose 20 via the horizontal transfer pipe 13, and further supplied to the injection means 40 via the lance 30 shown in FIG. 1, from the injection port 41 of the injection means 40 toward the work surface B. Be injected. The horizontal transfer pipe 13 can be omitted, and the conveyance hose 20 may be directly connected to the outlet side of the ejector 12.

  FIG. 3 is an explanatory diagram showing the positional relationship of the injection ports 41 of the injection means 40. In the present invention, the center-to-center distance L of the injection ports 41 is set to 1.4 to 5.3 times the inner diameter D of the injection ports 41. If L exceeds 5.3 times D, the target mass injection cannot be realized. That is, when L exceeds 5.3 times D, the raw material powder injected from each injection port 41 is close to being individually injected onto the work surface, and mass injection cannot be realized. On the other hand, L is set to be 1.4 times or more than D due to design restrictions as an actual machine. That is, there is a limit to disposing the injection means 40 close to each other due to the design as an actual machine.

  In the present invention, the inner diameters of the injection ports 41 are basically the same. This is because uniform spraying cannot be performed if the inner diameters of the injection ports 41 are different. However, the inner diameter of each injection port 41 may be slightly different as long as the uniformity of spraying is not impaired. In this case, the inner diameter D used when the distance L between the centers of the injection ports 41 is defined may be an average value of the inner diameters of the injection ports 41.

  Similarly, from the viewpoint of ensuring the uniformity of thermal spraying, the injection ports 41 are basically arranged in parallel as shown in FIG. However, the parallel direction may be a vertical direction or an oblique direction.

  FIG. 4 is an explanatory view showing the injection direction of the injection means 40. In the present invention, the injection direction of the injection means 40 is preferably 50 degrees or more and 95 degrees or less with respect to a straight line connecting the centers of the injection ports 41. That is, it is preferable that the angle θ shown in FIG. 4 is not less than 50 degrees and not more than 95 degrees. This angle θ is not expected to exceed 90 degrees from the point of realizing the mass injection intended by the present invention. However, when design restrictions and manufacturing errors are taken into consideration, the range up to 95 is acceptable.

In addition, from the viewpoint of realizing the mass injection intended by the present invention, the angle θ is preferably set so that the raw material powder injected from each injection port 41 converges on the work surface B at one point. The condition for this is expressed by the following formula (1), where R is the distance to the work surface.
R = 0.5L · tan θ (1)

  Here, the distance R to the construction surface is generally 50 to 200 mm. The center-to-center distance L of the injection ports 41 varies depending on the inner diameter D of the injection ports 41, but D is generally equivalent to 10A (12.7 mm) to 15A (16.1 mm). In this case, the maximum value of the center-to-center distance L of the injection port 41 is 16.1 × 5.3 = 85.3 mm, and when the distance R to the construction surface is the minimum 50 mm, the angle θ is expressed by the above formula (1). 50 degrees. Therefore, the angle θ is preferably 50 degrees or more.

  In the embodiment of FIG. 1, two sprayer main bodies 10 are provided, but can be integrated into one sprayer main body 50 as shown in FIG. 5. That is, two discharging parts 51a are provided in a hopper 51 as a storing means for storing the raw material powder A, and an ejector 52 as a mixture generating means is connected to each discharging part 51a. The configuration of the ejector 52 may be the same as that of the ejector 12 shown in FIG. However, in the present invention, the mixture generating means is not limited to an ejector. The ejector also has an action of sucking the raw material powder from the dispensing unit, but when using a mixture generating unit other than the ejector, a dispensing unit such as a table feeder or a screw feeder can be installed in the dispensing unit.

  A test was performed using the thermal spraying apparatus shown in FIG. 1 to confirm the presence or absence of ignition and to evaluate the smoothness and heap width of the construction body. The results are shown in Table 1.

In the test, a raw material powder (particles of 0.1 mm or less: 20% by mass) composed of silica (SiO ₂ ): 85% by mass as a refractory powder and 15% by mass of metal Si as a combustible powder, The raw material powder was injected by flowing a carrier gas (oxygen gas) of 0.5 MPa. In Comparative Example 1 and Comparative Example 2, spraying was performed from one spraying means 40 using only one sprayer main body 10 in the spraying apparatus of FIG.

  The injection amount of the raw material powder was 50 kg / h per spraying machine body except for Comparative Example 2, and 100 kg / h in Comparative Example 2. Table 1 shows the inner diameter of the injection port 41 of the injection means 40, the center-to-center distance of the injection port 41, the spraying distance (distance R to the work surface described in FIG. 4), and the injection angle (angle θ described in FIG. 4). It is as follows.

  About the presence or absence of ignition, the presence or absence of a spark generation | occurrence | production was confirmed visually in the injection means 40 vicinity. If ignition occurs, the spark travels through the transport hose 20 and the lance 30 and is confirmed near the injection means 40.

  About the smoothness of the construction body, it was evaluated as excellent (体) when the size of the unevenness of the construction body was 3 mm or less, and good (◯) when it was 3 mm or more and 5 mm or less.

  The heap width means the maximum length of the width of the welded portion to the work surface when spraying while moving the spraying means (jet nozzle) in one direction as shown in FIG. The heap width of each example was converted into an index with a width of 100. The larger the heap width is, the smaller the amount of welding per unit area of the work surface is. In this test, it was evaluated that the effect of mass injection was not obtained when the heap width exceeded 150 in terms of an index.

  As shown in Table 1, in Examples 1 to 8 within the scope of the present invention, no ignition was confirmed, and smoothness was also good. Moreover, the heap width was less than 150, and the effect of mass injection was also obtained.

  Comparative Example 1 is not an example of mass injection because there is one injection means 40 and the injection amount is 50 kg / h. Comparative Example 2 is an example in which the number of injection means 40 is one and the injection amount is increased to 100 / kg, but ignition occurred because of the large solid-gas ratio.

  The comparative example 3 is an example in which the distance between the centers of the injection ports 41 is too large, and the heap width becomes 180, and the effect of mass injection cannot be obtained. Comparative Example 4 is an example in which the injection angle is 44 degrees smaller than 50 degrees. In this case, before reaching the construction surface B, the injected raw material powder collides with each other and scatters. For this reason, the heap width was 210, and the effect of mass injection was not obtained.

  The thermal spraying technology of the present invention is a combustible combustor such as a coke oven, converter, melting furnace, AOD furnace, ladle, tundish, vacuum degassing furnace, kneading car, electric furnace, incinerator, induction furnace, heating furnace, glass furnace, etc. It can be used in industrial kilns and the like in which a conductive metal powder-containing thermal spray is used.

DESCRIPTION OF SYMBOLS 10 Thermal sprayer body 11 Hopper 11a Dispensing part 11b Vertical transfer pipe 12 Ejector (mixture production | generation means)
12a Container portion 12b Ejection nozzle 12c Discharge conduit 13 Horizontal transfer tube 20 Conveyance hose 30 Lance 40 Injecting means 41 Injecting port 50 Thermal sprayer main body 51 Hopper 52 Ejector A Raw material powder B Work surface

According to one aspect of the present invention, a thermal spraying apparatus that forms a refractory composition by injecting and burning a mixture of a raw material powder containing a refractory powder and a combustible powder, and a carrier-supporting carrier gas. A plurality of dispensing units for dispensing the raw material powder, and each of the dispensing units mixes the raw material powder dispensed from the dispensing unit and the carrier gas to form the mixture, and , it connects the injection means for injecting the generated by the mixture generator said mixture, these injection means comprise an injection port 2, the distance between the centers of the ejection ports, an inner diameter of the injection port The thermal spraying apparatus which is 1.4 times or more and 5.3 times or less is provided.

Claims (2)

A thermal spraying apparatus that forms a refractory composition by injecting and burning a mixture of a raw material powder containing a refractory powder and a combustible powder, and a combustion-supporting carrier gas,
Having a plurality of dispensing sections for dispensing the raw material powder;
Mixing means for mixing the raw material powder dispensed from the dispensing section and the carrier gas into the dispensing section to form the mixture, and injection means for injecting the mixture generated by the mixture generating section Connected
The thermal spraying apparatus in which the center-to-center distance of the injection ports of these injection means is 1.4 to 5.3 times the inner diameter of the injection port.   2. The thermal spraying apparatus according to claim 1, wherein an injection direction of the injection unit is 50 degrees or more and 95 degrees or less with respect to a straight line connecting the centers of the injection ports.

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