JP2014176820A - Thermal spray coater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal spray coater that can securely prevent the combustion and scattering of an in-hopper stock pulverized body caused by back fire inevitable in metal combustion spray coating.SOLUTION: A stock pulverized body contained in a hopper 1 is exhausted out of a discharge outlet 1a. The exhausted stock pulverized body is transported from the discharge outlet 1a to a suction port 3a of an ejector 3. A check valve 2 is provided in a transportation path of the stock pulverized body and turns from an open state to a closed state with an inner pressure rise of the ejector 3. Additionally, the stock pulverized body exhausted out of the discharge outlet 1a of the hopper 1 flows into the check valve 2 by a natural fall under gravity. The transportation path from the outlet 2c of the check valve 2 to the suction port 3a of the ejector 3 is provided with a constriction. The transportation cross-sectional area of the stock pulverized body in the constriction is smaller than that in the transportation path from the discharge outlet 1 to the valve port 2e of the check valve 2.

Description

  The present invention relates to a thermal spraying device applied to thermal spray repair of a refractory.

  In industrial kilns, molten metal containers, and the like, damage is caused to the lining made of refractory material with the use thereof. For such damage, repairs are performed as appropriate. For example, many of the coke ovens in steelworks have been built for more than 20 years, and in particular, the walls of the carbonization chamber continue to be operated with repeated repairs.

  There is a thermal spray repair method as a technique for performing repairs while continuing operations. Examples of the thermal spray repair method include plasma spraying, laser spraying, and flame spraying. However, these spraying methods require a large apparatus. Therefore, in recent years, a thermal spraying method using a metal oxidation exothermic reaction that can be realized with a relatively simple apparatus is also used. In this thermal spraying method, a mixture of metal powder (combustion agent) and refractory powder is transported with oxygen and sprayed onto a hot repair surface. The sprayed mixture forms a refractory composition by an oxidative exothermic reaction of the metal powder caused by receiving heat from the repair surface and melts and adheres to the repair surface.

  When the thermal spray material and oxygen are injected from the thermal spray lance and burned normally on the repair surface, the furnace wall can be repaired smoothly. However, during the work, the fire at the repair site burns out and ignites at the spray lance nozzle (hereinafter referred to as tip ignition), or the fire goes back from the spray lance to the main body of the spray device through the supply hose ( (Hereinafter referred to as backfire) may occur. Tip ignition can trigger backfire. And backfire causes explosion (so-called detonation) exceeding the speed of sound with expansion of the volume, and poses a risk that the supply hose separated due to the rupture of the supply hose or the rupture.

  In this way, the backfire causes a very dangerous situation, and it takes time for the recovery work to be able to resume the thermal spraying work, so it is preferable to prevent the backfire. However, it is difficult to identify the cause of flashback, and it is difficult to avoid the occurrence itself. Therefore, on the premise that the occurrence of flashback is unavoidable, it is customary to adopt a flashback countermeasure in the thermal spraying device.

  The simplest counter-fire countermeasure is to separate the spray lance from the supply hose by an operator with a spray lance when the tip ignition that induces the back fire occurs, and supply the spray material and oxygen from the supply hose to the spray lance. Is to obligate the flashback avoidance operation to shut off. As a result, backfire reaching the supply hose can be prevented and the supply hose can be prevented from bursting. However, if a flashback occurs when the flashback avoidance operation is performed, an explosion occurs at the worker having the thermal spray lance, which may put the worker in danger. Therefore, the thermal spraying device main body and the supply hose are connected by a quick joint (so-called coupler), and the thermal sprayer main body and the supply hose are separated using volume expansion or explosion caused by flashback. A configuration is employed that discharges and avoids rupture of the supply hose. In this configuration, explosion may occur at the thermal spraying apparatus main body, which may damage the thermal spraying apparatus main body, but is considered preferable to exposing the worker to danger.

  In the configuration in which the thermal spraying device main body and the supply hose are separated, it is necessary to connect the thermal spraying device main body with a wire so that the separated supply hose is not far away or violated. However, inadequate connection or forgetting to connect with wires cannot be eliminated, so that it is impossible to completely prevent the supply hose from moving far away or rampage. There is no problem as long as the supply hose is far away, but if the separated supply hose is rampant, there is a great danger for the operator of the thermal spraying device body.

  In any of the countermeasures, it is essential that an operator having a thermal spray lance informs the operator of the thermal spray apparatus main body of the occurrence of tip ignition and stops the supply of thermal spray material and oxygen. However, because there is no worker on the main body of the thermal spraying device or the shout cannot be transmitted due to environmental noise around the work, the supply of the thermal spray material and oxygen cannot be stopped, and the tip ignition ignites backfire. The possibility of attracting was increased. Moreover, as a result of not being able to stop the supply of the spray material and oxygen, the spray material to be sprayed sticks to the end of the supply hose and the supply port of the main body of the spray device, and the recovery work may be made more difficult. Various techniques have been proposed as countermeasures against such problems (for example, see Patent Documents 1 to 3).

  Patent Document 1 discloses a thermal spraying apparatus in which a raw material powder transfer path for transferring raw material powder from a hopper discharge port to an ejector is provided with an outside air communication portion communicating with the outside air. In addition, this thermal spraying device includes a baffle member disposed inside the hopper so as to be positioned in at least a part of the projection area of the discharge outlet in a direction parallel to the discharge direction of the raw material powder. According to this apparatus, even if a backfire occurs from the injection means to the ejector, the backfire is dissipated from the outside air communication portion, and it is possible to reduce the backfire reaching the hopper that stores the raw material powder.

  Patent Document 2 provides safety when a hose is detached from the main body due to the impact of flashback by providing a hooking flange on the supply hose connected to the thermal spraying device main body and providing a stopper at a position facing the hooking flange. The thermal spraying apparatus which ensures the is disclosed. Further, this technology adopts a configuration in which the material supply is stopped when the sensor detects the detachment of the flange from the thermal spraying device main body. This thermal spraying device can prevent the supply hose separated from the main body of the thermal sprayer from moving far away or ramping by engaging the retaining flange of the supply hose removed from the supply port with the stopper. And the supply of oxygen can be surely stopped.

  Patent Document 3 discloses a thermal spraying device provided with an emergency stop mechanism in an oxygen supply line. This emergency stop mechanism includes an emergency closing valve interposed in an oxygen supply line that supplies oxygen to an ejector that mixes raw material powder and oxygen, an oxygen branch line that branches from the oxygen supply line, and a hose that connects the oxygen branch line A detection valve, a pressurization line connecting the hose detection valve and the emergency closing valve, and an oxygen exhaust valve provided in the pressurization line are provided. This thermal spraying device is said to be able to reliably shut off oxygen in an emergency.

  On the other hand, as a technique related to the present invention, Patent Document 4 discloses a device that transports powder particles by an ejector action, with a certain amount of powder particles downward at the lower end of a hopper for storing the powder particles. A configuration is disclosed in which the upper end of a vertical conveying unit for vertical conveyance is connected in communication with each other, and the base end of a diffuser unit for sucking the conveyed granular material is connected to the lower end of the vertical conveying unit. A nozzle part is disposed in the vicinity of the connecting part between the diffuser part and the vertical conveying part, and pressurized air is ejected from the nozzle part toward the diffuser part in the powder body supply direction. In this apparatus, a screw conveyor is installed in a casing extending in the vertical and vertical directions as a vertical conveyance unit, and a check valve including an urging spring is disposed below the vertical conveyance unit. This check valve is configured so as to “prevent the backflow of pressurized air from the ejector nozzle portion while allowing extrusion by a screw conveyor”.

JP 2007-238977 A JP 2011-149078 A JP 2012-111973 A JP-A-6-16237

  However, it is possible to reduce the backfire reaching the hopper that stores the raw material powder only by providing an outside air communication part as disclosed in Patent Document 1, but it cannot be completely prevented. Further, since the baffle member in the hopper also overlaps only a part of the projection area of the discharge port, the raw material powder is blown up from the area where the baffle member does not exist when the backfire reaches the hopper. That is, there is a problem that the raw material powder in the hopper is scattered by the shock wave of the backfire.

  Moreover, in the structure which patent document 2, 3 discloses, in order to isolate | separate a supply hose, the pressure rise in a supply hose and an ejector inside is required. Although a pressure increase occurs due to the shock wave of backfire, when such a pressure increase occurs, a backflow of oxygen gas from the ejector portion into the hopper occurs, and the raw material powder in the hopper is scattered as in the configuration of Patent Document 1. Will do.

  It seems that such scattering of the raw material powder in the hopper can be prevented by adopting the configuration disclosed in Patent Document 4. However, when the check valve disclosed in Patent Document 4 is applied to a thermal spraying device, there is a problem that the check valve does not operate immediately when a backfire occurs. That is, in the structure which patent document 4 discloses, raw material powder is discharged | emitted using a screw conveyor during a thermal spraying operation | work. In order to close the check valve, it is necessary to move the raw material powder existing between the valve body and the valve seat. However, in the configuration of Patent Document 4, the blades of the screw conveyor hinder the movement of the raw material powder. Therefore, the check valve cannot be operated until the raw material powder existing between the valve body and the valve seat and the raw material powder accumulated in the screw conveyor are blown up into the hopper due to the pressure increase in the ejector portion. Therefore, even the configuration disclosed in Patent Document 4 cannot prevent the raw material powder in the hopper from being scattered due to the shock wave of the backfire.

  The present invention has been proposed in view of the above-described conventional circumstances, and provides a thermal spraying apparatus that can reliably prevent combustion and scattering of raw material powder in a hopper caused by flashback that is unavoidable in metal combustion thermal spraying. With the goal.

  The inventors of the present application considered that it is effective to provide a check valve, particularly for a method for preventing the raw material powder from blowing up from the hopper generated at the time of backfire, and examined the requirements for the check valve to operate effectively. As a result, the present invention has been achieved.

  First, the present invention presupposes a thermal spraying apparatus that transports a raw material powder containing a combustible powder and a refractory powder together with a combustion-supporting carrier gas and injects the material powder onto a workpiece to form a refractory composition. To do. And the thermal spraying apparatus which concerns on this invention is equipped with an ejector, a hopper, a conveyance path, a non-return valve, and a constriction part. The ejector includes an ejector nozzle, ejects a pressurized carrier gas from the ejector nozzle, mixes the carrier gas and the raw material powder by the ejector effect, and sends the mixture to the downstream side. The hopper is disposed above the ejector and accommodates the raw material powder mixed with the carrier gas. The conveying path conveys the raw material powder from the discharge port of the hopper to the inlet of the ejector. The check valve is provided in the conveyance path, and the raw material powder discharged from the discharge port of the hopper flows in due to natural descent due to gravity and changes from the open state to the closed state as the internal pressure of the ejector increases. The narrowed portion is provided in the conveyance path from the check valve outlet to the ejector inlet. The conveyance cross-sectional area of the raw material powder in the constricted portion is smaller than the minimum conveyance cross-sectional area of the raw material powder in the conveyance path from the hopper discharge port to the check valve inlet.

  In this thermal spraying apparatus, the structure which conveys the raw material powder by the natural fall by gravity can be employ | adopted in the whole region of a conveyance path. The conveyance cross-sectional area of the raw material powder at the check valve outlet is smaller than the minimum conveyance cross-sectional area of the raw material powder in the conveyance path from the discharge port of the hopper to the check valve inlet, and the ejector from the check valve outlet. It is also possible to adopt a configuration in which the check valve outlet has the largest transfer cross-sectional area in the transfer path to the inlet.

  In the above thermal spraying apparatus, the check valve may be arranged at the discharge port of the hopper and may have a valve seat portion having a circular valve port through which the raw material powder passes. In this case, the valve body that sits on the valve seat portion and closes the valve port may be arranged vertically below the valve seat portion, adopt a configuration having a circular shape in plan view and protruding toward the valve seat portion side. it can. In this configuration, the check valve may include a guide that guides the valve body only in the vertical direction.

  ADVANTAGE OF THE INVENTION According to this invention, the backflow to the hopper of a fire and a pressure resulting from the backfire which is unavoidable in metal combustion spraying can be prevented reliably, and combustion and scattering of the raw material powder in a hopper can be prevented reliably. As a result, the safety of the operator can be greatly increased.

The figure which shows the thermal spraying apparatus in one Embodiment of this invention The figure which shows the non-return valve with which the thermal spraying apparatus in one Embodiment of this invention is equipped, and a mounting seat The figure which shows operation | movement of the non-return valve in one Embodiment of this invention. The figure which shows an example of the valve body shape of the non-return valve in one Embodiment of this invention

  Hereinafter, an embodiment of the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a schematic view showing a thermal spraying apparatus according to an embodiment of the present invention. As shown in FIG. 1, the thermal spraying apparatus 10 of this embodiment is comprised by the ejector type transport mechanism provided with the ejector 3 as a solid-gas mixing part.

  The ejector 3 includes an ejector nozzle 4 and a diffuser (mixing tube) 5 that is disposed to face the ejector nozzle 4 and expands in the downstream direction. The ejector nozzle 4 injects gas from the tip toward the diffuser 5 at high speed. By the suction action (ejector effect) by the jet gas, the raw material powder (spray material) is sucked from the suction port 3a arranged in the direction (here, upward) intersecting the gas jet direction. The gas jetted from the ejector nozzle 4 and the sucked raw material powder are mixed in the diffuser 5 and sent downstream. The ejector nozzle 4 is connected to a carrier gas supply system (not shown) that supplies a combustion-supporting carrier gas mixed with the raw material powder to the ejector nozzle 4.

  A supply hose 6 is connected to the downstream outlet of the diffuser 5, and a thermal spray lance 7 is connected to the other end of the supply hose 6. The supply hose 6 is slidably and closely connected to the outside of the outlet of the diffuser 5. In this configuration, the pressure in the thermal spray lance 7 is increased by backfire, and when the pressure reaches the ejector 3 by flowing back through the supply hose 6, the supply hose 6 is detached from the diffuser 5 and the pressure is released to the outside.

  A hopper 1 is connected above the suction port 3a, and a raw powder composed of a mixture of combustible powder and refractory powder is accommodated in the hopper 1. The discharge port 1a of the hopper 1 is provided at the lower end of the hopper 1, and the raw material powder accommodated in the hopper 1 is discharged from the discharge port 1a by natural descent due to gravity. Although not particularly limited, in the present embodiment, the payout port 1a is circular in plan view.

  A check valve 2 is disposed between the hopper 1 and the ejector 3. The check valve 2 changes from the open state to the closed state as the internal pressure of the ejector 3 increases until the pressure generated by the backfire reaches the ejector 3 and the supply hose 6 is detached.

  Although not particularly limited, in the present embodiment, the valve seat portion 2 a of the check valve 2 has a circular valve port 2 e through which the raw material powder passes, and is disposed at the discharge port 1 a of the hopper 1. And the valve body 2b which seats on the valve seat part 2a and closes the valve port 2e is arrange | positioned under the valve seat part 2a. In this example, the valve port 2e is disposed along the edge of the payout port 1a and has a circular shape in plan view. There is no biasing means for applying a biasing force to the valve body 2b, and the valve body 2b is stationary by its own weight on the mounting seat 2d fixed at a position facing the valve seat portion 2a. The valve body 2b rises and seats on the valve seat portion 2a when a force is applied from below.

  A shutter portion 8 is provided directly below the check valve 2, and the shutter portion 8 and the suction port 3 a of the ejector 3 are connected by a connecting pipe 9. The supply and stop of the raw material powder can be switched by opening and closing the shutter 8a of the shutter unit 8. The supply and stop of the carrier gas to the ejector nozzle 4 can be switched by opening and closing an electromagnetic valve interposed in the carrier gas supply system. The opening and closing of the shutter 8a and the opening and closing of the electromagnetic valve may be realized by a switch operation on the surface of the control panel or may be realized by a remote operation by a wireless transmitter. In addition, these mechanisms can be opened or closed by providing a mechanism that opens when the supply hose 6 is properly attached to the outlet of the diffuser 5 and closes when the supply hose 6 is not properly attached. Good. In FIG. 1, for the purpose of explanation, parts other than the thermal spray lance 7 are shown as cross-sectional views.

  The raw material powder discharged from the discharge port 1 a of the hopper 1 and passing through the open check valve 2 is supplied to the suction port 3 a of the ejector 3. The raw material powder that has reached the ejector 3 is mixed with a carrier gas ejected from the ejector nozzle 4 in the diffuser 5, and the mixture is conveyed to the thermal spray lance 7 via the supply hose 6. When sprayed onto the high temperature workpiece from the tip of the thermal spray lance 7, the combustible powder burns by receiving heat and melts the refractory powder to form the thermal spray on the workpiece.

  Now, in the thermal spraying apparatus 10 of this embodiment, a constriction part is provided in the conveyance path of the raw material powder from the outlet 2c of the check valve 2 to the suction port 3a which is the inlet of the ejector 3. The conveyance cross-sectional area of the raw material powder in the narrowed portion is smaller than the minimum conveyance cross-sectional area of the raw material powder in the conveyance path from the discharge port 1a of the hopper 1 to the valve port 2e that is the inlet of the check valve 2. In addition, a conveyance cross-sectional area means the opening area of the part which has contributed substantially to conveyance of a raw material powder in the cross section perpendicular | vertical to a conveyance direction in the conveyance path of a raw material powder.

  As described above, the raw material powder discharged from the discharge port 1 a of the hopper 1 is supplied to the check valve 2, and the raw material powder that has passed through the check valve 2 is supplied to the suction port 3 a of the ejector 3. If the static pressure of the raw material powder is ignored, the supply amount of the raw material powder at a specific position on the transport path, that is, the amount of the raw material powder falling per unit time at the specific position on the transport path is the transport cross-sectional area at that position. If the conveyance cross-sectional area is large, the fall amount increases, and if the conveyance cross-sectional area is small, the fall amount decreases. Therefore, the supply amount of the raw material powder to the ejector 3 is determined by the portion having the smallest conveyance cross-sectional area in the conveyance path from the discharge port 1a of the hopper 1 to the suction port 3a of the ejector 3. On the other hand, the supply speed of the raw material powder to the thermal spray lance 7 is slightly larger than the amount of the raw material powder dropped per unit time due to the action of the suction force by the ejector 3, but it is assumed that the suction force is constant. Then, the supply speed of the raw material powder, that is, the part having the smallest conveyance sectional area of the conveyance path from the discharge port 1a of the hopper 1 to the suction port 3a of the ejector 3 is determined.

  When such a minimum conveyance cross-sectional area having the smallest conveyance cross-sectional area is provided in the material powder conveyance path from the outlet 2c of the check valve 2 to the suction port 3a of the ejector 3, the material is discharged from the discharge port 1a of the hopper 1. The amount of raw material powder to be produced is larger than the amount of raw material powder that passes through the minimum conveyance cross-sectional area. For this reason, the raw material powder is accumulated above the minimum conveyance cross-sectional area, and as a result, the checker 2 is filled with the raw material powder.

  In the experiment by the inventors of the present application, the minimum transfer cross-sectional area from the discharge port 1a of the hopper 1 to the valve port 2e of the check valve 2 is determined, and the raw material powder from the outlet 2c of the check valve 2 to the suction port 3a of the ejector 3 is measured. When it was made smaller than the minimum conveyance cross-sectional area in the conveyance path, the check valve 2 operated as the internal pressure of the ejector 3 increased, but the raw material powder from the hopper 1 could not be completely prevented from being blown up. On the other hand, if the check valve 2 is filled with raw material powder, the response speed of the check valve 2 with respect to the rise in the internal pressure of the ejector 3 can be increased, and the powder powder from the hopper 1 is completely blown up. I can't. In the latter case, the internal pressure of the ejector 3 rises in a state where the inside of the check valve 2 (especially the downstream side of the valve body 2b) is filled with the raw material powder. It is considered that the rise of the powder efficiently moves the valve body 2b upward so that the check valve 2 can be operated quickly. On the other hand, in the former case, since the raw material powder falls in the air inside the check valve 2, the valve body 2b is moved upward by the gas flow. Therefore, the valve body 2b cannot be raised unless there is a sufficient gas flow for the movement of the valve body 2b. That is, the check valve 2 is not closed unless after a certain amount of gas flows. Therefore, even if it is possible to reduce the blowing of the raw material powder from the hopper 1, it is considered impossible to completely prevent it.

For example, in the configuration shown in FIG. 1, the transport sectional area of the discharge port 1 a (= the valve port 2 e of the check valve 2) of the hopper 1 is D _h , and the transport sectional area of the outlet 2 c of the check valve 2 is D _c . the conveying cross-sectional area of the mouth 3a and _{D e.} Based on the above consideration, in this case, it is preferable that D _h > D _c or D _h > D _e . In this example, the outlet 2c or the suction port 3a of the check valve 2 is a narrowed portion.

The conveying cross-sectional area D _h of the thus payout opening 1a, the conveying cross-sectional area of the conveying cross-sectional area D _c or aspiration opening 3a of the outlet 2c of the check valve 2 when larger than D _e, the payout opening 1a of the hopper 1 The amount of raw material powder supplied to the check valve 2 is larger than the amount of raw material powder discharged from the outlet 2 c of the check valve 2. Therefore, the check valve 2 is filled with the raw material powder. In addition, by further reducing the conveying cross-sectional area D _e of the suction port 3a than the conveying cross-sectional area D _c of the check valve 2 of the outlet 2c, filled with the raw material powder to the suction port 3a of the ejector 3. As a result, the pressure can be transmitted to the valve body 2b more efficiently. Therefore, it is more preferable to satisfy D _h > D _c > D _e, and further, quick filling of the check valve 2 and the inside of the conveyance path between the check valve 2 and the suction port 3a of the ejector 3 is realized. From the viewpoint, it is preferable that the conveyance cross-sectional area D _c of the outlet 2 c of the check valve 2 is the largest in the conveyance path from the outlet 2 c of the check valve 2 to the suction port 3 a of the ejector 3. Conversely, if the conveying cross-sectional area D _h of payout opening 1a as is minimized, as described above, the response speed of the check valve 2 is reduced.

  Moreover, in this embodiment, since raw material powder falls by the natural flow by gravity and fills the inside of the check valve 2, the valve body 2b can be easily moved with a relatively small force. On the other hand, in the configuration in which the material powder is discharged by forcibly applying a force to the discharge port 1a of the hopper 1 like a screw conveyor, the material powder filling the inside of the check valve 2 (above the valve body 2b) Since the existing raw material powder) is pressed and compacted, the valve body 2b cannot be moved with a little force. That is, the response speed of the check valve 2 decreases. From this point of view, it can be said that it is particularly preferable that the raw material powder is conveyed by natural descent due to gravity in the entire conveyance path for conveying the raw material powder from the discharge port 1a of the hopper 1 to the suction port 3a of the ejector 3. In addition, the drop due to the natural flow is economically advantageous in that it does not require power energy for supplying the raw material powder.

  Hereinafter, the structure of the check valve 2 will be described in detail. Fig.2 (a)-FIG.2 (d) are figures which show the valve body 2b with which the non-return valve 2 in this embodiment is equipped, and the attachment seat 2d. FIG. 2A corresponds to a plan view of the valve body 2b. FIG. 2B corresponds to a front view of the valve body 2b. FIG. 2C corresponds to a plan view of the mounting seat 2d. FIG. 2D corresponds to a front view of the mounting seat 2d.

  As shown in FIGS. 2 (a) and 2 (b), the valve body 2b of the check valve 2 includes a conical umbrella portion 21 that sits on the valve seat portion 2a and closes the valve port 2e, A cylindrical support shaft 22 is provided on the bottom surface of the umbrella portion 21 and is arranged coaxially with the umbrella portion 21. As shown in FIG. 1, the support shaft 22 is disposed along the vertical direction, and the apex of the umbrella portion 21 is disposed toward the valve seat portion 2a.

  As shown in FIG. 1, the valve body 2b is installed on a mounting seat 2d that is fixedly supported in a state of facing the valve seat portion 2a. As shown in FIGS. 2C and 2D, the mounting seat 2 d includes a cylindrical guide 26 and a support member 27 that fixes the guide 26 to the casing of the check valve 2. Although not particularly limited, in this embodiment, the mounting seat 2d includes four plate-like support members 27, and the end surface of the support member 27 on the valve seat portion 2a side and the guide 26 on the valve seat portion 2a side. It is flush with the end face.

  The mounting seat 2d is fixed to the housing of the check valve 2 with the axis of the guide 26 along the vertical direction, and the support shaft 22 of the valve body 2b is inserted into the guide. In this configuration, the valve body 2b is held in a state where the bottom surface of the umbrella portion 21 is in contact with the guide 26 and the support member 27 (hereinafter referred to as a normal position), and the moving direction of the valve body 2b is limited only in the vertical direction. Will be. By restricting the moving direction of the valve body 2b in this way, the valve body 2b can be seated on the valve seat portion 2a with an accurate and shortest moving distance. Of course, the length of the support shaft 22 is larger than the moving distance from the normal position to the seating position.

  FIGS. 3A and 3B are diagrams illustrating the operation of the check valve 2. FIG. 3A corresponds to the open state, and FIG. 3B corresponds to the closed state. As shown in FIG. 3 (a), the valve body 2b is disposed at the normal position in a state where the raw material powder in the hopper 1 is conveyed to the ejector 3 without backfire. In this state, the raw material powder flows down around the valve body 2b toward the downstream side. When the internal pressure of the ejector 3 rises due to the occurrence of backfire, the valve body 2b moves upward with the movement of the raw material powder filled in the check valve 2 as described above, and is seated on the valve seat portion 2a. To do. Thereby, the backflow to the hopper 1 of the raw material powder which exists downstream from the non-return valve 2 can be prevented. Moreover, since the valve port 2e of the valve seat part 2a which is a communication port with the hopper 1 is closed, it is possible to prevent high-pressure gas generated by flashback from flowing into the hopper 1. As a result, the raw material powder from the hopper 1 can be reliably prevented from being blown up or scattered. When the pressure is released, the valve body 2b returns to the normal position due to the weight of the valve body 2b and the natural fall of the raw material powder.

  The umbrella portion 21 may be solid or hollow. However, it is not preferable to employ a hollow structure in which the bottom side of the umbrella portion 21 is open. In such a configuration, since the raw material powder that naturally descends from above cannot enter from the lower side of the umbrella portion 21 to fill the hollow portion of the umbrella portion 21, a gap is generated in the portion. In this case, when the raw material powder moves as the internal pressure of the ejector 3 increases, the valve body 2b does not move until the gap is filled, and the response speed decreases.

  In general, from the viewpoint of ease of movement of the valve body 2b, the valve body 2b is preferably lightweight. However, in the configuration of the present embodiment, since the valve body 2b moves while the raw material powder is filled in the check valve 2, the valve body 2b is seated on the valve seat portion 2a. The raw material powder enters between the support shaft 22 and the guide 26 of 2b. Therefore, if the valve body 2b is too light, the raw material powder that has entered between the support shaft 22 and the guide 26 prevents the movement of the support shaft 22 and makes it difficult for the valve body 2b to move to the normal position. Therefore, in the structure of this embodiment, it is preferable that the valve body 2b has a certain amount of weight.

  In addition, the structure which supports the valve body 2b is not specifically limited, Arbitrary structures are employable. For example, the number of support shafts 22 and guides 26 may be plural, and the cross-sectional shape is not limited to a circle. The mounting seat 2d only needs to have a structure that supports the guide 26 and allows the raw material powder to pass downward, and the structure is not particularly limited. Further, in the present embodiment, the support shaft 22 and the guide 26 are provided at a position opposite to the valve seat portion 2a with the valve body 2b interposed therebetween, but the hopper 1 rather than the valve seat portion 2a side (ie, the valve body 2b). Side). Thus, in the structure which arrange | positions a support shaft and a guide in the hopper 1 side rather than the valve body 2b, it is preferable that the valve body 2b is lighter. Furthermore, it is not essential to provide a support shaft, and it is also possible to employ a guide that contacts the outer edge of the valve body 2b and guides the valve body 2b.

  Moreover, the umbrella part 21 of the valve body 2b should just be seated on the valve seat part 2a, and can close the valve port 2e, and the shape is arbitrary. From the viewpoint of realizing efficient movement according to the increase in the internal pressure on the downstream side (ejector 3 side), the umbrella portion 21 has a shape in which the cross-sectional area increases toward the downstream side, that is, protrudes toward the valve seat portion 2a. It is preferable to have a shape that In addition, from the viewpoint of not hindering the flow of the raw material powder due to natural descent, the valve port 2e of the valve seat portion 2a is circular in plan view, and the valve body 2b is an axial object having a vertex protruding toward the valve seat portion 2a. It is preferable to comprise a rotating body. With this configuration, the raw material powder can be smoothly passed to the downstream side without being retained on the valve body 2b. 4 (a) and 4 (b) are front views showing another example of the shape of the umbrella portion of the valve body 2b based on this viewpoint. In FIG. 4A, the valve body 2 b has a configuration in which a hemispherical umbrella portion 23 is fixed to the support shaft 22. In FIG. 4B, the valve body 2b has a rotating body-like umbrella shape (a shape in which the side surface of the cone is recessed) having a concave curved surface on the valve seat portion 2a side fixed to the support shaft 22. Yes.

  The composition of the raw material powder and the carrier gas used in the thermal spraying apparatus 10 of the present embodiment are not particularly limited. For example, metallic silicon can be used as the combustible powder, and silica, cordierite, or the like can be used as the refractory powder. Pure oxygen or the like can be used as the carrier gas.

  Further, the size of the hopper 1, the size of the ejector 3, the discharge amount of the raw material powder, the diameter and length of the supply hose 6, and the material are not particularly limited. The supply hose 6 may be a pipe made of any material such as a flexible hose or a pipe having rigidity such as a metal pipe. In addition, the cross-sectional shape of the pipe is preferably circular, but other cross-sectional shapes may be adopted. Further, as the supply hose 6, a configuration in which a pipe having an appropriate length connected to the thermal spraying apparatus 10 and a pipe on the downstream side of the pipe are connected by coupling or the like can be adopted. In this configuration, it is possible to easily replace only the portion on the outlet side of the diffuser 5 where the inner surface of the supply hose 6 is severely worn, and the maintainability can be improved.

For example, when the structure shown in FIG. 1 is applied to thermal spraying using a raw material powder composed of 15% by mass of metallic silicon and 85% by mass of silica, the discharge rate can be set to several tens to 200 kg / h. When the carrier gas is oxygen having a purity of 100%, the flow rate can be 30 Nm ³ / h, and the material supply rate can be 100 kg / h or the like.

  The supply hose 6 having an inner diameter of 30 mm and a length of several m to 100 m can be used. As described above, when the supply hose 6 is configured by connecting a plurality of supply hoses 6, the length of the portion on the outlet side of the diffuser 5 can be set to 100 to 500 mm.

  In this configuration, when backfire was generated, it was possible to completely prevent the raw material powder in the hopper 1 from being blown up. In addition, it was possible to reliably prevent fire from entering the hopper 1. In this confirmation, the diameter of the discharge port 1a (valve port 2e) of the hopper 1 is 25 mm, the diameter of the outlet 2c of the check valve 2 is 23 mm, and the diameter of the suction port 3a of the ejector 3 is 18.5 mm. The operation is performed in a state where the valve body 2b in the normal position is filled with the raw material powder to the extent that the valve body 2b is filled inside the valve 2. In this example, the diameter of the valve body 2b is 28 mm, which is 3.0 mm larger than the diameter of the discharge port 1 a of the hopper 1 and 5.0 mm larger than the diameter of the outlet 2 c of the check valve 2.

  In this configuration, a hole communicating with the outside air may be provided in the conveyance path between the suction port 3a of the ejector 3 and the check valve 2. This makes it possible to dissipate backfire from the hole. The conveying path between the suction port 3a of the ejector 3 and the check valve 2 is filled with the raw material powder during the thermal spraying work, so that some material spillage may occur, but this spillage is allowed. As long as it is possible, the provision of the hole is not hindered.

  Moreover, as mentioned above, when the inside of the check valve 2 is not filled with the raw material powder, the response speed of the check valve 2 to the pressure increase inside the ejector 3 is lowered. Therefore, a check window or sensor for confirming whether or not the inside of the check valve 2 is filled with the raw material powder is provided in the check valve 2, and the ejector 3 can operate only when the check valve 2 is filled with the raw material powder. You may employ | adopt the structure which becomes.

  As described above, according to the present invention, it is possible to reliably prevent the backflow of fire and pressure to the hopper 1 due to the backfire that is unavoidable in metal combustion spraying, and the combustion and scattering of the raw material powder in the hopper 1. Can be reliably prevented. As a result, the safety of the operator can be greatly increased.

  The above-described embodiments do not limit the technical scope of the present invention, and various modifications and applications other than those already described are possible within the scope of the present invention. For example, in the above embodiment, the check valve 2 is provided below the dispensing port 1a of the hopper 1, and the ejector 3 is further provided below the check valve 2. However, these may be connected continuously and have an appropriate length. You may connect through the connecting pipe. Further, the valve seat portion 2a may directly connect the valve port 2e to the dispensing port 1a. In this case, the valve seat portion 2a can be configured integrally with the dispensing port 1a. Furthermore, the shape of the valve port 2e, the cross-sectional shape of each connecting pipe, and the like can be arbitrarily set. In addition, in the above-described embodiment, the shutter unit 8 is installed between the check valve 2 and the ejector 3, but the installation of the shutter unit 8 is not essential and is optional.

  INDUSTRIAL APPLICABILITY The present invention can reliably prevent combustion and scattering of the raw material powder in the hopper caused by flashback, which is inevitable in metal combustion spraying, and is useful as a spraying device.

1 Hopper 1a Discharge port 2 Check valve 2a Valve seat 2b Valve body 2c Outlet 2d Mounting seat 2e Valve port 3 Ejector 3a Suction unit (Ejector inlet)
4 Ejector nozzle 5 Diffuser 6 Supply hose 7 Thermal spray lance 10 Thermal spray device

Claims (5)

A thermal spraying device for conveying a raw material powder containing a combustible powder and a refractory powder together with a combustion-supporting carrier gas and spraying the material powder onto a workpiece to form a refractory composition,
An ejector comprising an ejector nozzle, ejecting the pressurized carrier gas from the ejector nozzle, mixing the carrier gas and the raw material powder by an ejector effect, and delivering the mixture downstream;
A hopper disposed above the ejector and containing the raw material powder mixed with the carrier gas;
A conveying path that conveys the raw material powder from the discharge opening of the hopper to the entrance of the ejector; and the raw material powder discharged from the discharge opening of the hopper flows in by gravity drop, and A check valve that changes from an open state to a closed state as the internal pressure of the ejector increases,
Provided in the transport path from the check valve outlet to the ejector inlet, the transport cross-sectional area of the raw material powder of the raw material powder in the transport path from the hopper discharge port to the check valve inlet A constriction smaller than the minimum transport cross-sectional area;
A thermal spraying device comprising:   The thermal spraying device according to claim 1, wherein the raw material powder is conveyed by natural descent due to gravity in the entire area of the conveyance path.   The conveyance cross-sectional area of the raw material powder at the outlet of the check valve is smaller than the minimum conveyance cross-sectional area of the raw material powder in the conveyance path from the discharge port of the hopper to the inlet of the check valve, and the check valve The thermal spraying device according to claim 1, wherein an outlet of the check valve has a maximum conveyance cross-sectional area in the conveyance path from the outlet of the nozzle to the inlet of the ejector. The check valve
A valve seat having a circular valve port that is disposed at the discharge port of the hopper and through which the raw material powder passes;
A valve body that is disposed vertically below the valve seat portion, has a circular shape in a plan view that is seated on the valve seat portion and closes the valve port, and that protrudes toward the valve seat portion;
The thermal spraying device according to any one of claims 1 to 3, further comprising:   The thermal spraying device according to claim 4, wherein the check valve includes a guide for guiding the valve body only in a vertical direction.

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