DESCRIPTION THERMAL SPRAY DEVICE
Field
[0001] The present invention relates to a thermal
spray device for forming a refractory composition.
Background
[0002] As a thermal spray device for forming a
refractory composition, there is known a conventional thermal spray device that forms a refractory composition by conveying a raw material powder containing a combustible powder (e.g., metal powder) and a refractory powder (refractory aggregate) by a combustion-supporting carrier gas (oxygen gas), injecting the raw material powder from an injection port of an injector, and igniting and melting the raw material powder.
[0003] In such a thermal spray device, since the raw
material powder containing the combustible powder and the refractory powder is conveyed by the combustion-supporting carrier gas, injected from the injection port of the injector, and ignited and melted as described above, such a phenomenon occurs in some cases that the injection port of the injector catches fire with a flame of a mixture of the

raw material powder and the carrier gas, which are burning by being injected and ignited, spreading thereto (tip ignition). Such a phenomenon also occurs in some cases that, for example, an ejector that mixes the raw material powder and the carrier gas catches fire by friction between its inner surface and the raw material powder (friction ignition).
[0004] If such tip ignition or friction ignition
occurs, such a phenomenon may occur that the ignition proceeds to a direction opposite to a conveyance direction of the raw material powder (backfire). If the backfire occurs, a pressure in a hopper that stores the raw material powder increases abnormally, generating such a phenomenon that the raw material powder is blown upward in the hopper (raw material powder blowing phenomenon), possibly resulting in a fire or an explosion. This is a serious problem in thermal spraying.
There is also the problem that, if a rubber hose
connecting an outlet side of the ejector and the injector
is bent, or the rubber hose or the injection port of the
injector is clogged with the raw material powder, the
pressure in the hopper increases, reducing a suction force
of the ejector.
[0005] To prevent the pressure increase in the hopper,

Patent Literature 1 discloses a thermal spray device having a configuration in which a lid body of a cover member is lifted by a pressure of a gas jetted out from a through hole, opening an upper opening of a cover body when a pressure in a vertical transfer pipe that transfers the raw material powder from the hopper to the ejector increases. If the lid body remains lifted in the thermal spray device according to Patent Literature 1, the suction force of the ejector is reduced due to leakage of the carrier gas, leading to a backfire. As a countermeasure, feeding of the carrier gas is stopped by detecting the lift of the lid body. For example, a rod is provided above the lid body so as to move up when the lid body is lifted, and the feeding of the carrier gas is stopped when the rod moves up.
Citation List
Patent Literature
[0006] Patent Literature 1: Japanese Utility Model
Registration No. 3171530
Summary of Invention
Technical Problem to be Solved by Invention
[0007] However, in the above conventional

configuration, when the pressure in the hopper increases due to the clogging of the rubber hose or the like, the lid body is lifted only a little. Thus, the lift of the lid body cannot be detected, and the carrier gas feeding cannot be stopped in some cases. When the lift of the lid body cannot be detected, the carrier gas keeps leaking due to the lift of the lid body. Thus, the suction force of the ejector is reduced, possibly leading to a backfire. Additionally, the leakage of the carrier gas or the combustible raw material powder to the outside of the device causes a safety problem.
[0008] An object of the present invention is to
provide a thermal spray device capable of reliably stopping feeding of a carrier gas even when a lid body is lifted only a little as in clogging of a rubber hose, or the like.
Solution to Problem
[0009] A thermal spray device according to the present
invention is a thermal spray device that forms a refractory composition by injecting and burning a mixture obtained by mixing a raw material powder containing a refractory powder and a combustible powder, and a combustion-supporting carrier gas, the device including a hopper that stores the raw material powder and has a discharge port to discharge

the raw material powder, an ejector that mixes the raw material powder discharged from the hopper and the carrier gas and conveys the mixture, and an injector that injects the conveyed mixture. A vertical transfer pipe that transfers the raw material powder from the discharge port to the ejector is provided with a through hole, and a cover member that surrounds the through hole from the outside, the cover member including a cover body fixed to an outer periphery of the vertical transfer pipe, and a lid body capable of vertically moving along an outer peripheral surface of the vertical transfer pipe and closing an upper opening of the cover body from above, a plunger is provided to be normally in contact with a side surface of the lid body and receive a load in a direction toward the vertical transfer pipe. When a pressure in the vertical transfer pipe increases, the lid body of the cover member is lifted by a pressure of a gas jetted out from the through hole, and the plunger moves in the direction toward the vertical transfer pipe, stopping feeding of the carrier gas to the ejector by the movement.
Advantageous Effects of Invention
[0010] According to the present invention, even when
the lid body is lifted only a little as in clogging of a

rubber hose or the like, the plunger moves in the direction
toward the vertical transfer pipe, acting to stop the
feeding of the carrier gas. Thus, it is possible to
reliably stop the carrier gas feeding.
Brief Description of Drawings
[0011] Fig. 1 is a schematic cross-sectional view of a
thermal spray device according to one embodiment of the present invention.
Fig. 2 is a view illustrating a configuration example of an on-off valve and an air cylinder that operates the on-off valve in the thermal spray device in Fig. 1.
Description of Embodiments
[0012] Hereinafter, an embodiment of the present
invention will be described with reference to the drawings.
Fig. 1 schematically illustrates a cross section of a
thermal spray device according to one embodiment of the
present invention.
[0013] The thermal spray device illustrated in Fig. 1
includes a hopper 20 as a storage to store a raw material
powder 10, an ejector 30, and an injector 40.
[0014] The raw material powder 10 contains a
combustible powder (e.g., metal powder) and a refractory

powder (refractory aggregate). The hopper 20 has an upper opening 21 to receive the raw material powder 10 at its top, and a discharge port 22 to discharge the raw material powder 10 at its bottom. The ejector 30 sucks the raw material powder 10 from the discharge port 22 by a flow of a pressurized carrier gas (oxygen gas), and mixes the carrier gas and the raw material powder 10 into a mixture. The injector 40 is connected to an outlet side of the ejector 30 via a horizontal transfer pipe 50 and a rubber hose 60, and injects the mixture generated by the ejector
30. Note that the horizontal transfer pipe 50 may be
omitted, and the rubber hose 60 may be directly connected
to the outlet side of the ejector 30.
[0015] Next, the configuration of the ejector 30 will
be described in detail. The ejector 30 includes a container 31 having an inner space in communication with the discharge port 22 at the bottom of the hopper 20, a tapered jetting nozzle 32 that jets out the pressurized carrier gas into the inner space of the container 31 from its distal end, and a discharge conduit 33 that guides the mixture from one end to the other end along a flow path with the one end communicating with the inner space of the container 31. That is, in the inner space of the container
31, the carrier gas is jetted out at high speed toward the

one end (proximal end) of the discharge conduit 33 from a
nozzle hole at the distal end of the tapered jetting nozzle
32, bringing the inner space of the container 31 into a
negative pressure state (here, a pressure lower than an
atmospheric pressure). Meanwhile, the discharge port 22 of
the hopper 20 communicates with the inner space of the
container 31 via a vertical transfer pipe 70. Thus, the
ejector 30 sucks the raw material powder 10 into the inner
space of the container 31 from the discharge port 22 by the
flow of the pressurized carrier gas, and mixes the carrier
gas jetted out from the nozzle hole at the distal end of
the jetting nozzle 32 and the raw material powder 10, into
the mixture within the inner space of the container 31.
[0016] In the present invention, the vertical transfer
pipe 70 is provided with a through hole 71 as a pressure releaser for preventing the raw material powder from being blown upward to the hopper 20 when a backfire occurs. In the present embodiment, a plurality of the through holes 71 (e.g., six of the through holes 71 having a diameter of 3 mm) are provided at equal intervals along a circumferential direction of the vertical transfer pipe 70.
[0017] In the present invention, a cover member 80
that surrounds the through holes 71 from the outside is also provided. The cover member 80 includes a cover body

81 and a lid body 82. In the present embodiment, the cover
body 81 is shaped such that its lower end is fixed to a
fixing portion 72 provided on an outer periphery of the
vertical transfer pipe 70 and its upper portion is opened.
Additionally, the lid body 82 is provided vertically
movable along an outer peripheral surface of the vertical
transfer pipe 70 via two pieces of packing 82a provided at
upper and lower positions, and thus an upper opening of the
cover body 81 can be closed from above.
[0018] That is, during normal thermal spraying with no
backfire (at normal times), the lid body 82 of the cover member 80 closes the upper opening of the cover body 81, bringing the through holes 71 into a state isolated from outside air by the cover member 80. Therefore, it is possible to prevent outside air from being sucked from the through holes 71 during normal thermal spraying with no backfire.
[0019] Meanwhile, when a backfire occurs to cause a
pressure increase in the vertical transfer pipe 70, a gas is jetted from the through holes 71, lifting the lid body
82 by the pressure of the jetted gas. As a result, the
upper opening of the cover body 81 is opened, and the gas
jetted out from the through holes 71 is discharged to
outside air, so that the pressure is released. Thus, it is

possible to prevent the pressure increase in the vertical
transfer pipe 70, and the raw material powder from being
blown upward to the hopper 20 during the backfire.
[0020] Additionally, in the present embodiment, in
order to more reliably prevent the raw material powder from being blown upward to the hopper 20 during the backfire, a valve member 90 is provided below the discharge port 22 of the hopper 20. The valve member 90 is vertically movable along a vertical shaft 91, and closes the discharge port 22 from below when moving up. That is, when the backfire occurs to cause the pressure increase in the vertical transfer pipe 70, the valve member 90 moves up due to the pressure, closing the discharge port 22. The raw material powder can be thereby prevented from being blown upward to the hopper 20 during the backfire.
[0021] Note that the valve member 90 preferably has a
tapered shape having a diameter that increases downwardly as illustrated in Fig. 1. The discharge port 22 can be thereby reliably closed when the valve member 90 moves up. Additionally, the valve member 90, which is normally located below the discharge port 22 with a space
therebetween, has the tapered shape as described above, and thus the raw material powder is evenly distributed within the vertical transfer pipe 70, so that the raw material

powder can be evenly conveyed.
[0022] In the present embodiment, a cap member 100
that covers the upper opening 21 of the hopper 20 from above is provided so as to prevent the blown raw material powder from directly hitting the face of a surrounding operator even if the raw material powder is blown upward to the hopper 20. Specifically, the cap member 100 is provided such that its lower end is located below the upper opening 21 of the hopper 20. The lower end of the cap member 100 is also located at a height of approximately 1 m from the ground. Thus, the blown raw material powder is jetted out to a position lower than the operator's face, so that the raw material powder can be prevented from directly hitting the face of the surrounding operator.
[0023] Moreover, in the present embodiment, an outlet
side of the horizontal transfer pipe 50 and the rubber hose 60 are butt-joined together. Specifically, the horizontal transfer pipe 50 and the rubber hose 60 are butt-joined together by inserting a proximal end side of the rubber hose 60 into a metal sleeve 61, and coupling the sleeve 61 and the horizontal transfer pipe 50 together using a fastener 62. As described above, the horizontal transfer pipe 50 and the rubber hose 60 are butt-joined together. Thus, when a fire occurs in the ejector 30 or the

horizontal transfer pipe 50 to cause a pressure increase, the rubber hose 60 is detached from the outlet side of the horizontal transfer pipe 50 by the pressure. The pressure is thereby released.
[0024] When the horizontal transfer pipe 50 is not
used, an outlet side of the discharge conduit 33 of the
ejector 30 and the rubber hose 60 are butt-joined together.
[0025] A carrier gas feed pipe 110 is connected to a
proximal end of the jetting nozzle 32 of the ejector 30. An unillustrated high-pressure carrier gas feed source is connected to a feed port 111 of the carrier gas feed pipe 110. The pressurized carrier gas is fed to the ejector 30 through the carrier gas feed pipe 110.
[0026] In the carrier gas feed pipe 110, a master
valve 112, a pressure reducing valve 113, an on-off valve
114, a flow regulating valve 115, and a flowmeter 116 are
provided sequentially from its upstream side. The carrier
gas is depressurized to approximately 0.5 MPa by the
pressure reducing valve 113, and fed to the ejector 30.
[0027] The on-off valve 114 opens/closes a pipeline of
the carrier gas feed pipe 110 by the action of an air cylinder 117. The air cylinder 117 is driven by a drive gas. The drive gas is supplied by a drive gas supply pipe 120 branching from the carrier gas feed pipe 110 on the

upstream side of the on-off valve 114.
[0028] The drive gas supply pipe 120 is provided with
a mechanical valve 130 including a plunger 131. The
plunger 131 is normally in contact with a side surface of
the lid body 82 as illustrated in Fig. 1. In this state,
the mechanical valve 130 closes the drive gas supply pipe
120. The plunger 131 also receives a load in a direction
toward the vertical transfer pipe 70. In other words, the
plunger 131 is urged in the direction toward the vertical
transfer pipe 70. In such a configuration, when the
pressure in the vertical transfer pipe 70 increases, the
lid body 82 is lifted by the pressure of the gas jetted out
from the through holes 71. The contact engagement between
the side surface of the lid body 82 and the plunger 131 is
thereby released, so that the plunger 131 moves in the
direction toward the vertical transfer pipe 70 (moves
forward). When the plunger 131 moves forward, the
mechanical valve 130 opens the drive gas supply pipe 120.
[0029] That is, when the lid body 82 is lifted along
with the pressure increase in the vertical transfer pipe 70, the plunger 131 moves forward, opening the drive gas supply pipe 120. The drive gas (here, of the same type as the carrier gas) is thereby supplied to the air cylinder 117 through the drive gas supply pipe 120. The on-off

valve 114 is closed by the action of the air cylinder 117. The feeding of the carrier gas to the ejector 30 is thereby stopped.
[0030] As described above, in the thermal spray device
according to the present embodiment, the plunger 131 is normally in contact with the side surface of the lid body 82, and the plunger 131 further receives the load in the direction toward the vertical transfer pipe 70. Thus, even when the lid body 82 is lifted only a little as in clogging of the rubber hose 60, or the like, the plunger 131 moves in the direction toward the vertical transfer pipe 70 (moves forward), acting to stop the feeding of the carrier gas. Thus, it is possible to reliably stop the carrier gas feeding.
[0031] Fig. 2 illustrates a configuration example of
the on-off valve 114 and the air cylinder 117 that operates the on-off valve 114. The air cylinder 117 includes a pair of cylinders 117a individually provided with racks 117a-1. The pair of cylinders 117a are disposed in a cylinder chamber 117b. The cylinder chamber 117b is divided into an inner chamber 117b-1 and outer chambers 117b-2 on opposite sides in a sealed state by the pair of cylinders 117a. Compression springs 117c are disposed in the outer chambers 117b-2 on the opposite sides of the cylinder chamber 117b.

The compression springs 117c individually apply a force of pressing the pair of cylinders 117a. A distal end of the drive gas supply pipe 120 is also connected to the inner chamber 117b-1 of the cylinder chamber 117b. Meanwhile, the on-off valve 114 includes a pinion 114a that meshes with the racks 117a-1 of the pair of cylinders 117a. The pinion 114a is provided integrally with a ball valve 114b. That is, the on-off valve 114 is operated in association with the action of the pair of cylinders 117a by a rack and pinion mechanism obtained by meshing between the racks 117a-1 and the pinion 114a.
[0032] In the above configuration, the mechanical
valve 130 including the plunger 131 normally closes the drive gas supply pipe 120 as described using Fig. 1. Thus, no drive gas is supplied to the air cylinder 117. In this state, the pair of cylinders 117a individually move forward by the pressing forces of the compression springs 117c, so that the on-off valve 114 comes into an open state (the state in Fig. 2).
[0033] Subsequently, when the lid body 82 is lifted
along with the pressure increase in the vertical transfer pipe 70, the plunger 131 moves forward, opening the drive gas supply pipe 120. The drive gas (here, of the same type as the carrier gas) is thereby supplied to the air cylinder

117 through the drive gas supply pipe 120. Specifically, the drive gas is supplied to the inner chamber 117b-1 of the cylinder chamber 117b, and the pair of cylinders 117a move backward against the pressing forces of the
compression springs 117c by the pressure of the drive gas. The on-off valve 114 is thereby rotated into a closed state, stopping the carrier gas feeding.
[0034] To resume the carrier gas feeding, the lid body
82 is returned to the original state illustrated in Fig. 1, and the plunger 131 is also returned to the original state (in contact with the side surface of the lid body 82) after closing the master valve 112. After that, the drive gas in the drive gas supply pipe 120 between the mechanical valve 130 and the air cylinder 117 is discharged to the outside by an unillustrated leak valve or the like. The drive gas is thereby also discharged from the inner chamber 117b-1 of the air cylinder 117, so that the air cylinder 117 returns to the initial state. The on-off valve 114 returns to the open state by this action of the air cylinder 117. The carrier gas feeding is resumed by opening the master valve 112.
[0035] Here, the side surface of the lid body 82 is
preferably shaped such that a portion below the contacting portion with the plunger 131 has a downwardly decreasing

diameter. Thus, the plunger 131 can be smoothly returned to the original position only by applying a load to the lid body 82 from above in returning the lid body 82 to the original state.
[0036] As described above, in the present embodiment,
the plunger 131 is incorporated in the mechanical valve 130, and the movement (forward movement) of the plunger 131 causes the mechanical valve 130 to be opened, and the on-off valve 114 to be closed by the air cylinder 117, stopping the carrier gas feeding to the ejector 30. The present invention is not limited to such a configuration. For example, the movement (forward movement) of the plunger 131 may be converted into an electrical signal, and the on-off valve 114 may be closed by the electrical signal, stopping the carrier gas feeding to the ejector 30. In conclusion, any desired configuration that stops the carrier gas feeding to the ejector 30 based on the movement (forward movement) of the plunger 131 may be employed.
Industrial Applicability
[0037] The thermal spray device according to the
present invention can be used for, for example, industrial kilns using combustible metal powder-containing thermal spraying, such as a coke oven, a converter, a melting

furnace, an AOD furnace, a ladle, a tundish, a vacuum degassing furnace, a torpedo car, an electric furnace, an incinerator, an induction furnace, a heating furnace, and a glass furnace.
Reference Signs List
[0038] 10 RAW MATERIAL POWDER
20 HOPPER (STORAGE)
21 UPPER OPENING
22 DISCHARGE PORT

30 EJECTOR
31 CONTAINER
32 JETTING NOZZLE
33 DISCHARGE CONDUIT
40 INJECTOR
50 HORIZONTAL TRANSFER PIPE
60 RUBBER HOSE
70 VERTICAL TRANSFER PIPE
71 THROUGH HOLE
72 FIXING PORTION

80 COVER MEMBER
81 COVER BODY
82 LID BODY 82a PACKING

83 VALVE MEMBER
84 VERTICAL SHAFT 100 CAP MEMBER

110 CARRIER GAS FEED PIPE
111 FEED PORT
112 MASTER VALVE
113 PRESSURE REDUCING VALVE
114 ON-OFF VALVE 114a PINION 114b BALL VALVE
115 FLOW REGULATING VALVE
116 FLOWMETER
117 AIR CYLINDER 117a CYLINDER 117a-1 RACK
117b CYLINDER CHAMBER 117b-1 INNER CHAMBER 117b-2 OUTER CHAMBER 117c COMPRESSION SPRING 120 DRIVE GAS SUPPLY PIPE
130 MECHANICAL VALVE
131 PLUNGER

We Claim :
1. A thermal spray device that forms a refractory composition by injecting and burning a mixture obtained by mixing a raw material powder containing a refractory powder and a combustible powder, and a combustion-supporting carrier gas, the thermal spray device comprising:
a hopper that stores the raw material powder and has a discharge port to discharge the raw material powder;
an ejector that mixes the raw material powder discharged from the hopper and the carrier gas and conveys the mixture; and
an injector that injects the conveyed mixture, wherein
a vertical transfer pipe that transfers the raw material powder from the discharge port to the ejector is provided with a through hole, and a cover member that surrounds the through hole from outside,
the cover member includes a cover body fixed to an outer periphery of the vertical transfer pipe, and a lid body capable of vertically moving along an outer peripheral surface of the vertical transfer pipe and closing an upper opening of the cover body from above,
a plunger is provided to be normally in contact with a side surface of the lid body and receive a load in a

direction toward the vertical transfer pipe, and
when a pressure in the vertical transfer pipe increases, the lid body of the cover member is lifted by a pressure of a gas jetted out from the through hole, and the plunger moves in the direction toward the vertical transfer pipe, stopping feeding of the carrier gas to the ejector by the movement.
2. The thermal spray device as claimed in claim 1,
wherein the side surface of the lid body is shaped such
that a portion below a contacting portion with the plunger
has a downwardly decreasing diameter.