JP2013043141A - Thermal spraying apparatus, thermal spraying method and thermal spraying material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of ignition due to the friction of a raw material powder with a discharge duct.SOLUTION: The thermal spraying apparatus provided with: a storage means 20 storing the raw material powder 10 and having a put-out port 21 for putting out the raw material powder; an ejector 30 sucking the raw material powder 10 from the put-out port 21 with the flow of a pressurized carrier gas and mixing the carrier gas with the raw material powder to make a mixture; and a spraying means 40 for spraying the mixture generated in the ejector 30; wherein in the thermal spraying appratus in which a refractory composition is formed by spraying and burning the mixture, at least a part of an inner surface forming a flow path of the discharge duct 33 of the ejector 30 is made from a resin or rubber.

Description

  The present invention relates to a thermal spraying apparatus and a thermal spraying method for forming a refractory composition, and a thermal spray material used for the thermal spraying.

  Conventionally, as a thermal spraying technique 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 ( A technique for forming a refractory composition by conveying, injecting with oxygen gas), and igniting and melting is known (for example, see Patent Documents 1 and 2).

  In such thermal spraying technology, a mixture of raw material powder and carrier gas is guided downstream along the flow path of the discharge conduit. Conventionally, the discharge conduit is made of metal (stainless steel) in consideration of wear resistance and the like. In general, it is formed by the above-described method, and there is a problem that ignition is likely to occur due to friction between the raw material powder and the discharge conduit.

  In the above-mentioned Patent Document 1, the discharge conduit includes a throttle portion in which the cross-sectional area of the flow path monotonously decreases from one end to the downstream, and an expansion section in which the cross-sectional area of the flow path increases monotonously from the upstream to the other end. Techniques are described to prevent wear of the discharge conduit by forming. However, Patent Document 1 does not specifically describe the material of the discharge conduit. If the discharge conduit is made of a conventional metal, there still remains a problem that ignition is likely to occur due to friction between the raw material powder and the discharge conduit.

  In addition, when ignition occurs, a phenomenon (backfire) occurs in which the ignition proceeds in the direction opposite to the conveying direction of the raw material powder. In order to prevent backfire, it is necessary that the transport speed for transporting the raw material powder be higher than the speed at which combustion proceeds by the backfire (combustion speed). Patent Document 2 describes a technique for providing an external air communication portion in a raw material powder transfer path from a hopper so that the raw material powder does not blow up to the hopper when a backfire occurs. There is no mention of technology to prevent this.

JP 2007-275816 A JP 2007-238977 A

  An object of the present invention is to prevent occurrence of ignition due to friction between a raw material powder and a discharge conduit.

  Another problem is to prevent the occurrence of backfire even if ignition occurs.

  The thermal spraying apparatus of the present invention is 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. Storage means having a discharge outlet for storing the raw material powder and discharging the raw material powder; and sucking the raw material powder from the discharge outlet by a flow of pressurized carrier gas; and An ejector that mixes the raw material powder into the mixture and an injection unit that injects the mixture generated by the ejector, the ejector including a container portion having an internal space communicating with the discharge port; A jet nozzle that jets the pressurized carrier gas from the tip to the internal space; and a discharge conduit that communicates at one end with the internal space and guides the mixture from the one end to the other along the flow path. At least a portion of the inner surface defining the flow path of the discharge conduit, characterized in that formed by a resin or rubber.

  The thermal spraying method of the present invention is a thermal spraying method in which a mixture obtained by mixing a raw material powder containing a refractory powder and a flammable powder and a carrier-supporting carrier gas is injected and burned to form a refractory composition. A discharge step of discharging the raw material powder from a discharge port of the storage means for storing the raw material powder, and a discharge from the discharge port to a container portion having an internal space communicating with the discharge port of the storage means. Introducing step of introducing the raw material powder, an inhaling step of sucking the raw material powder guided by the introducing step by a carrier gas flow, and mixing for mixing the sucked raw material powder and the carrier gas A step of conveying the mixture mixed in the mixing step along a flow path of a discharge conduit having at least a part of an inner surface made of resin or rubber, and injecting the mixture conveyed in the conveying step Injection And extent, characterized in that it comprises a forming step of said mixture injected by the injection process is burned to form a refractory composition.

  In the present invention, as the resin or rubber constituting at least a part of the inner surface forming the flow path of the discharge conduit, it is preferable to use a conductive material from the viewpoint of preventing ignition due to static electricity.

  Further, in the present invention, in order to prevent the occurrence of flashback by increasing the conveying speed of the raw material powder, the inner diameter of the straight portion having a constant inner diameter in the discharge conduit is 8 mm or more and 12 mm or less, and the nozzle hole diameter at the tip of the ejection nozzle Is preferably 2 mm or more and 4 mm or less.

  Furthermore, in the present invention, from the viewpoint of suppressing wear of the discharge conduit, it is preferable to use a raw material powder in which particles of 0.1 mm or less are 10% by mass or more as the raw material powder.

  According to the present invention, at least a part of the inner surface forming the flow path of the discharge conduit is made of resin or rubber, thereby preventing the occurrence of ignition (spark) due to friction between the raw material powder and the discharge conduit. Can do.

  In addition, by limiting the inner diameter of the straight portion of the discharge conduit and the nozzle hole diameter of the ejection nozzle as described above, the conveying speed of the raw material powder can be increased, the occurrence of backfire can be prevented, and the raw material can be prevented. The discharge amount of the powder can also ensure a desired amount or more.

  Furthermore, as the raw material powder, wear of the discharge conduit can be suppressed by using a raw material powder in which particles of 0.1 mm or less are 10% by mass or more.

It is sectional drawing of the principal part which shows one Embodiment of the thermal spraying apparatus of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a main part showing an embodiment of a thermal spraying apparatus of the present invention.

  The thermal spraying apparatus shown in FIG. 1 includes a hopper 20 as a storage unit that stores the raw material powder 10, an ejector 30, and an injection unit 40.

  The raw material powder 10 includes combustible powder (for example, metal powder) and refractory powder (refractory aggregate). Preferably, the particle size is such that particles of 0.1 mm or less are 10 mass% or more. The reason will be described later.

  The hopper 20 has a discharge outlet 21 for discharging the raw material powder 10 at the bottom. The ejector 30 sucks the raw material powder 10 from the outlet 21 by the flow of pressurized carrier gas (oxygen gas), and mixes the carrier gas and the raw material powder 10 to form a mixture. The injection means 40 is connected to the outlet side of the ejector 30 via the horizontal transfer pipe 50 and the rubber hose 60, and injects the mixture generated by the ejector 30. The horizontal transfer pipe 50 can be omitted, and the rubber hose 60 may be directly connected to the outlet side of the ejector 30.

  Next, the configuration of the ejector 30 will be described in detail. The ejector 30 includes a container part 31 having an internal space communicating with the discharge outlet 21 at the bottom of the hopper 20, a tapered jet nozzle 32 that jets pressurized carrier gas from the tip to the internal space of the container part 31, and a container part. 31 is provided with a discharge conduit 33 that communicates with the internal space 31 at one end 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 31, the carrier gas is ejected at a high speed from the nozzle hole at the tip of the tapered ejection nozzle 32 toward one end (base end) of the discharge conduit 33, thereby causing the internal space of the container portion 31 to be ejected. Negative pressure (here, pressure lower than atmospheric pressure) is set. On the other hand, the outlet 21 of the hopper 20 communicates with the internal space of the container portion 31 through the vertical transfer pipe 70. For this reason, the ejector 30 sucks the raw material powder 10 into the internal space of the container part 31 from the discharge outlet 21 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 32. 10 are mixed in the internal space of the container 31 to form a mixture.

  In the present invention, in the ejector 30, in order to prevent the occurrence of ignition due to the friction between the discharge conduit 33 and the raw material powder 10, at least a part of the inner surface forming the flow path of the discharge conduit 33 is made of resin or rubber. To do. In the embodiment of FIG. 1, the entire inner surface of the discharge conduit 33 and the entire inner surface of the container portion 31, that is, the entire inner surface of the ejector 30 are made of resin or rubber. Specifically, the entire discharge conduit 33 and the container part 31 are made of resin or rubber. Among these, the discharge conduit 33 has a double tube structure in which the inner tube 33b is fitted into the outer tube 33a, and when the inner tube 33b is consumed, only the inner tube can be replaced. In addition, although the discharge conduit | pipe 33 was made into the double tube structure, it is not limited to this, It is good also as a single tube structure.

  In the present embodiment, the entire inner surface forming the flow path of the horizontal transfer pipe 50 is also made of resin or rubber. Specifically, resin or rubber is lined on the inner surface of the horizontal transfer pipe 50 to form the lining layer 50a. Furthermore, in this embodiment, the lining layer 50a of the horizontal transfer pipe 50 and the rubber hose 60 are abutted and joined. That is, in the present embodiment, the ejector 30 and the inner surfaces of the downstream flow paths are all formed of resin or rubber so that the metal is not exposed. Thereby, generation | occurrence | production of the ignition (spark) by friction with raw material powder and the inner surface of the flow path can be prevented reliably.

  However, since it is the discharge conduit 33 portion that is most likely to ignite due to friction between the raw material powder and the inner surface of the flow passage, at least a part of the inner surface of the discharge conduit 33 is made of resin or rubber in the present invention. It is a requirement to configure. Although it is preferable that the entire inner surface of the discharge conduit 33 is made of resin or rubber, even if it is a part of the inner surface, the occurrence of ignition can be suppressed more significantly than in the prior art. When a part of the inner surface of the discharge conduit 33 is made of resin or rubber, ignition is likely to occur due to friction in a portion of the discharge conduit 33 close to the container portion 31 side. The range of at least about 150 mm from one end of the side is preferably composed of resin or rubber.

  In the present invention, the type of resin or rubber constituting the inner surface of the flow path is not particularly limited, but as the resin, vinyl chloride resin, polystyrene, ABS, polyethylene, polypropylene, nylon, acrylic resin, fluororesin, polycarbonate, methylpentene resin , Polyurethane, phenol resin, melamine resin, epoxy resin, etc., rubber includes natural rubber, butadiene rubber, styrene rubber, butyl rubber, ethylene / propylene rubber, nitrile rubber, acrylic rubber, urethane rubber, silicone rubber, fluorine rubber, etc. .

The resin or rubber used in the present invention preferably has conductivity. This is to prevent static electricity from accumulating due to friction with the raw material powder and causing ignition. As the degree of conductivity, the volume resistivity is preferably less than 10 ⁸ Ω · m. Such a conductive resin can be obtained by dispersing conductive particles in a resin, and examples thereof include conductive polyethylene. The conductive rubber can be obtained by dispersing conductive particles in an insulating elastic polymer (rubber), and examples thereof include nitrile rubber.

  In the present embodiment, the entire discharge conduit 33 and the container part 31 of the ejector 30 are made of resin or rubber so that the inner surface of the flow path is made of resin or rubber. Similarly to the transfer pipe 50, resin or rubber may be lined on the inner surface of the flow path.

  As described above, in the present invention, at least a part of the inner surface forming the flow path of the discharge conduit 33 is made of resin or rubber. The inner surface of the channel made of resin or rubber is physically more easily worn than the inner surface of a conventional metal channel. In order to suppress this abrasion, in the present invention, it is preferable to use a raw material powder having a particle size constitution in which particles of 0.1 mm or less are 10% by mass or more. By limiting the ratio of coarse particles exceeding 0.1 mm in this way, even if the inner surface of the flow path is made of resin or rubber, the wear can be suppressed.

  In the present invention, at least a part of the inner surface forming the flow path of the discharge conduit 33 is made of resin or rubber so as to prevent the occurrence of ignition due to friction. The possibility of ignition by friction is not zero. Therefore, in a preferred embodiment of the present invention, means is provided for preventing the occurrence of backfire (a phenomenon in which ignition proceeds in the direction opposite to the conveying direction of the raw material powder) even if ignition occurs. To prevent flashback, as described above. It is necessary that the conveying speed for conveying the raw material powder be higher than the speed (combustion speed) at which combustion proceeds by backfire. From this point, in the present invention, it is preferable that the inner diameter of the straight portion having a constant inner diameter in the discharge conduit 33 is 8 mm or more and 12 mm or less, and the nozzle hole diameter at the tip of the ejection nozzle 32 is 2 mm or more and 4 mm or less. When the inner diameter of the straight portion of the discharge conduit 33 is more than 12 mm or the nozzle hole diameter is more than 4 mm, the conveying speed of the raw material powder becomes slow, so that it is difficult to prevent backfire and also causes a defective conveyance of the raw material powder. Even if the inner diameter of the straight portion of the discharge conduit 33 and the nozzle hole diameter are large, it is possible to increase the conveying speed of the raw material powder if the flow rate of the carrier gas is increased. As the rebound loss increases, the flow rate of the carrier gas is limited. Accordingly, the inner diameter of the straight portion of the discharge conduit 33 is preferably 12 mm or less, and the nozzle hole diameter is preferably 4 mm or less.

  On the other hand, when the inner diameter of the straight portion of the discharge conduit 33 is less than 8 mm, the raw material powder is easily clogged, the transportability is deteriorated, and the transport amount (discharge amount) of the raw material powder is also decreased. Further, if the nozzle hole diameter at the tip of the ejection nozzle 32 is less than 2 mm, a sufficient flow rate of the carrier gas cannot be ensured, the transportability is deteriorated, and the carrier gas (oxygen gas) is insufficient, resulting in poor ignition.

  In addition, in this embodiment, although the discharge conduit | pipe 33 consists only of a straight part, you may provide the aperture | diaphragm | squeeze part and expansion part like the said patent document 1 in the entrance side and exit side of a straight part.

  When thermal spraying is performed using the above thermal spraying apparatus, first, the raw material powder 10 is dispensed from the dispensing outlet 21 of the hopper 20 (dispensing process). Next, the raw material powder 10 is guided to the container portion 31 of the ejector 30 having an internal space communicating with the discharge outlet 21 of the hopper 20 via the vertical transfer pipe 70 (introduction step), and the raw material powder guided by this introduction step 10 is sucked by the carrier gas flow in the ejector 30 (suction process), and the raw material powder 10 and the carrier gas are mixed (mixing process). And the mixture mixed by the mixing process is conveyed along the flow path of the discharge conduit | pipe 33 in which at least one part of the inner surface was comprised with resin or rubber | gum (conveyance process), and the conveyed mixture is injected by the injection means 40. It injects (injection process) and burns the injected mixture to form a refractory composition (formation process).

Example 1
A test was performed using the thermal spraying apparatus shown in FIG. 1 to confirm the presence or absence of ignition. 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. As the ejector 30, those composed of conductive polyethylene and those composed of nitrile rubber were used. The length of the rubber hose 60 was 10 m. As the rubber hose 60, a conductive hose was used in order to extinguish an ignition factor due to static electricity.

  The raw material powder was conveyed in units of 10 kg, and this was carried out five times, and the presence or absence of ignition was confirmed visually. A portion that is easily ignited is in the vicinity of the outlet of the discharge conduit 33, and if ignition occurs, the spark travels through the rubber hose 60 and is confirmed in the vicinity of the injection means 40.

  As a result of the test, no occurrence of ignition was confirmed in any of the ejector 30 made of conductive polyethylene and the nitrile rubber.

  As a comparative example, in the thermal spraying apparatus of FIG. 1, the same test as described above was performed for the ejector 30 made of stainless steel and SS steel. As a result, the occurrence of ignition was confirmed in all the comparative examples.

(Example 2)
In the thermal spraying apparatus of FIG. 1, the test was performed by changing the inner diameter of the straight portion of the discharge conduit 33 and the nozzle hole diameter at the tip of the ejection nozzle 32, and the backfire prevention performance was confirmed. The raw material powder is the same as in Example 1, and the pressure condition of the carrier gas (oxygen gas) is also the same as in Example 1. The length and material of the rubber hose 60 are the same as those in the first embodiment. In the test, the ejector 30 was made of conductive polyethylene, the rubber hose 60 was forcibly burned, and the presence or absence of flashback was visually confirmed.

The test results are shown in Table 1.

  As shown in Table 1, Examples A to H in which the inner diameter of the straight portion of the discharge conduit 33 is 8 mm or more and 12 mm or less and the nozzle hole diameter at the tip of the ejection nozzle 32 is 2 mm or more and 4 mm or less are confirmed to be flashback. In addition, the transportability of the raw material powder was good, and there was no problem with the discharge amount of the raw material powder from the discharge conduit 33.

  On the other hand, in Examples I to M that deviate from the preferable condition of the present invention in which the inner diameter of the straight portion of the discharge conduit 33 is 8 mm or more and 12 mm or less, or the nozzle hole diameter of the tip of the ejection nozzle 32 is 2 mm or more and 4 mm or less, backfire occurs confirmed. However, in this test, the presence or absence of flashback in the case of forced ignition was confirmed. From the viewpoint of preventing ignition, which is the first problem of the present invention, Examples I to M also solve the problem. It can be done.

  In Examples I to M, some problems were observed in the transportability of the raw material powder. That is, in Example I, since the nozzle hole diameter was small, the carrier gas flow rate was insufficient, and the rubber hose 60 tended to be poorly conveyed. In Example J, since the nozzle hole diameter was large, the flow rate of the carrier gas decreased, and the raw material powder tended to stay in the discharge conduit 33 of the ejector 30. In Example K, since the inner diameter of the discharge conduit 33 was small, the raw material powder tended to stay in the discharge conduit 33. In Examples L and M, since the inner diameter of the discharge conduit 33 is large, the flow velocity in the discharge conduit 33 is reduced, and the raw material powder tends to stay in the discharge conduit 33. However, these transportability problems are in an allowable range in actual construction.

(Example 3)
In the thermal spraying apparatus shown in FIG. 1, the test was performed by changing the particle size composition of the raw material powder, and the amount of wear of the discharge conduit 33 was investigated. The ejector 30 was made of conductive polyethylene. The pressure condition of the carrier gas (oxygen gas) and the length and material of the rubber hose 60 are the same as those in the first embodiment.

The test results are shown in Table 2.

  As shown in Table 2, the wear amount of the discharge conduit 33 can be reduced by setting the ratio of particles of 0.1 mm or less in the raw material powder to 10 mass% or more. This is because the wear of the discharge conduit 33 due to coarse particles exceeding 0.1 mm is reduced. Even if the discharge conduit 33 is worn, particles having a size of 0.1 mm or less enter the worn portion of the discharge conduit 33, so that the particles having a size of 0.1 mm or less serve to coat the discharge conduit 33. This is because the wear of 33 is reduced.

  In addition, from the result of abrasion of the discharge conduit 33, the ratio of particles of 0.1 mm or less is preferably 20% by mass or more, and more preferably 30% by mass or more.

  In addition, although refractory powder shall use only siliceous powder, it is not limited to this. For example, as the refractory powder, one or more selected from siliceous powder, calcia powder, alumina-silica powder, alumina powder, calcia-silica powder, cordierite powder, and magnesia powder are used. It is good to do.

  Moreover, although combustible powder decided to use metal Si, it is not limited to this. For example, the combustible powder may be Al or an Al—Mg alloy.

  The thermal spraying technology of the present invention is combustible such as 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 for industrial kilns and the like in which metal powder-containing thermal spraying is used.

10 Raw material powder 20 Hopper (storage means)
DESCRIPTION OF SYMBOLS 21 Discharge port 30 Ejector 31 Container part 32 Injection nozzle 33 Discharge conduit 33a Outer tube 33b Inner tube 40 Injection means 50 Horizontal transfer pipe 50a Lining layer 60 Rubber hose 70 Vertical transfer pipe

Claims (8)

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,
Storage means having a discharge outlet for storing the raw material powder and discharging the raw material powder;
An ejector that sucks the raw material powder from the outlet through a flow of pressurized carrier gas, and mixes the carrier gas and the raw material powder to form the mixture;
An injection means for injecting the mixture generated by the ejector,
The ejector is
A container portion having an internal space communicating with the discharge outlet;
An ejection nozzle that ejects the pressurized carrier gas from the tip into the internal space;
A discharge conduit that communicates with the internal space at one end and guides the mixture from the one end to the other end along a flow path;
A thermal spraying apparatus in which at least a part of an inner surface forming a flow path of the discharge conduit is made of resin or rubber.   The thermal spraying device according to claim 1, wherein the resin or rubber has conductivity. The discharge conduit has a straight portion with a constant cross-sectional area of the flow path, and the straight portion has an inner diameter of 8 mm or more and 12 mm or less,
The thermal spraying device according to claim 1 or 2, wherein a nozzle hole diameter at a tip of the ejection nozzle is 2 mm or more and 4 mm or less. A thermal spraying method for forming a refractory composition by injecting and combusting a mixture of a raw material powder containing a refractory powder and a combustible powder and a combustion-supporting carrier gas,
A payout step of paying out the raw material powder from a payout port of a storage means for storing the raw material powder;
Introducing the raw material powder dispensed from the dispensing outlet into a container portion having an internal space communicating with the dispensing outlet of the storage means;
An inhalation step of inhaling the raw material powder guided by the introduction step by a flow of a carrier gas;
A mixing step of mixing the inhaled raw material powder and the carrier gas;
A conveying step of conveying the mixture mixed in the mixing step along a flow path of a discharge conduit having at least a part of an inner surface made of resin or rubber; and
An injection step of injecting the mixture conveyed by the conveyance step;
And a forming step of burning the mixture injected in the injection step to form a refractory composition.   The thermal spraying method of Claim 4 which uses what has electroconductivity as said resin or rubber | gum. In the inhalation step, the raw material powder is inhaled by a flow of carrier gas ejected by an ejection nozzle having a nozzle hole diameter of 2 mm or more and 4 mm or less at the tip,
6. The thermal spraying method according to claim 4, wherein, in the transporting step, the straight part having a constant inner diameter provided in the discharge conduit is transported under a condition where the inner diameter is 8 mm or more and 12 mm or less.   The thermal spraying method in any one of Claims 4-6 which uses the raw material powder whose particle | grains of 0.1 mm or less are 10 mass% or more as said raw material powder.   The thermal spray material which consists of raw material powder which is the raw material powder used with the thermal spraying method in any one of Claims 4-6, Comprising: Particle | grains of 0.1 mm or less are 10 mass% or more.

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