JP2013205011A - Vacuum measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum measuring device with less infiltration of moisture or steam of a molten metal, and with less failure of a vacuum gauge caused by the infiltration happening.SOLUTION: A vacuum measuring device is constructed such that a branch duct-shaped filter part 32 is connected upward to a vacuum space 33, a vacuum gauge 31 is attached to the upper end of the filter part 32 to heat it, and an orifice 34 for trapping steam or droplets is formed in the filter part 32. The upward gradient θ of the filter part 32 for returning the steam or the droplets to the vacuum space 33 is desirably set to 7° or higher. A plurality of stages of orifices 34 is provided, and each is shifted in a surface direction to provide a molecule passage hole 35. A notch-shaped drain 36 is disposed in the lower part of the orifice 34.

Description

  The present invention relates to an apparatus for measuring the degree of vacuum of a space by attaching a vacuum gauge to a space where molten metal vapor or droplets are scattered, and in particular, the scattered vapor or splash penetrates into the vacuum gauge and the vacuum gauge The present invention relates to a vacuum measuring apparatus that prevents the occurrence of a vacuum gauge failure caused by steam and droplets.

  For example, in a reduced pressure molten metal tank containing molten metal such as molten aluminum, an inert gas such as Ar gas is blown into the molten metal, and the molten metal is stirred and circulated, so that the gas and impurities contained in the molten metal are removed. An apparatus for purifying molten metal is used which is discharged from the inside of the molten metal and removed from the inside of the molten metal together with an inert gas as a carrier gas.

FIG. 1 shows an example of such a molten metal purification apparatus. For example, in this molten metal purification apparatus, the impurity removal tank 1 is provided side by side with the molten metal tank 11.
A metal 16 such as aluminum is accommodated in the molten metal tank 11, and the metal 16 is heated by a heater 17 provided outside the molten metal tank 11 to be in a molten state. The lower end of the electrode 15 suspended in the molten metal tank 11 is immersed in the molten metal 16 inside the molten metal tank 11, and the state of the molten metal 16, specifically, its temperature and liquid level are detected. . In the molten metal tank 11, after nitrogen gas is supplied from the nitrogen gas supply source 13, the pressure is reduced to 1/100 atm or less by the nitrogen pressure reducing device 19. A molten metal supply cylinder 12 is provided on the top plate side of the molten metal tank 11, and the molten metal supply cylinder 12 is opened and closed by a lid 18. The molten metal supply cylinder 12 and the interior of the molten metal tank 11 are shielded by a shielding plate 14.

After the molten metal 16 such as aluminum is accommodated in the molten metal tank 11, the molten metal supply pipe 9 is closed by the molten metal, so that the molten metal tank 11 and the impurity removal tank 1 can be depressurized at the same time. Become.
On the other hand, a heater 20 is attached to the outer wall of the impurity removal tank 1, the molten metal 8 is accommodated in the bottom of the inner wall, and the inside is simultaneously with the molten metal tank 11 by the vacuum pump 4 through the exhaust cylinder 2 provided with the filter 3. Exhausted. In addition, argon gas is sent from the argon gas supply source 5 into the impurity removal tank 1 so that the gas is replaced before the exhaust, and the impurity removal tank 1 is always in the molten metal tank after being simultaneously decompressed with the molten metal tank 11. 11 is set to a pressure equal to or lower than 11, for example, a vacuum state on the order of Pa. The interior of the impurity removal tank 1 and the exhaust pipe 2 are shielded by a shielding plate 6. Since the inside of the molten metal tank 11 and the inside of the impurity removal tank 1 are depressurized at the same time, the molten metal 16 does not move to the impurity removal tank 1 through the molten metal supply pipe 9. For example, if the pressure inside the molten metal tank 11 is set to 1 kPa and the pressure inside the impurity removal tank 1 is set to 1 Pa, the molten metal is converted into the molten metal tank 11 by an amount corresponding to about 1 kPa of the pressure difference from the impurity removal tank 1. It is only pushed up in the molten metal supply pipe 9 inside. When the molten metal 16 is molten aluminum, if the specific gravity is 2.5 g / cm ³ , it is only pushed up by 4 cm.

  When a molten aluminum supply pipe 9 is piped from the upper part of the impurity removal tank 1 into the molten metal 16 of the molten metal tank 11 and nitrogen gas is introduced into the molten metal tank 11, the impurity removal tank 1 is passed through the molten aluminum supply pipe 9. The molten metal 16 is pumped from the molten metal tank 11. A baffle plate 7 is attached to the lower end of the molten aluminum supply pipe 9 on the impurity removal tank 1 side, and the molten metal 16 strikes the baffle plate 7 and scatters and accumulates in the impurity removal tank 1.

  When the molten metal 16 in the molten metal tank 11 is pumped to the impurity removal supply tank 1 through the molten aluminum supply pipe 9, the molten metal 16 is scattered by the baffle plate 7 and the surface area of the molten aluminum is increased. As a result, gas contained in the molten metal 16 and impurities with high vapor pressure are released from the inside of the molten metal 16. Gases released from the inside of the molten metal 16 and vapors of impurities such as magnesium, lead and zinc having a high vapor pressure are inert gases such as nitrogen gas and argon gas as carrier gases sent into the molten metal tank 11. At the same time, it is removed by the filter 3 of the exhaust pipe 2 of the impurity removal tank 1 by the vacuum pump 4 in operation.

  Thus, in the apparatus which removes hydrogen gas and impurities with high vapor pressure from the molten metal 16 scattered in the argon gas under reduced pressure, it is performed at a vacuum pressure on the order of Pa while flowing the argon gas. In the case where the molten metal 16 is molten aluminum, it reacts slightly with nitrogen to form a nitride, preventing the evaporation of impurities, so it must be scattered in argon gas. Argon gas is also optimal as the gas supplied to the molten metal tank 11 for extruding the molten aluminum, but the amount of molten metal 16 to be processed originally in the molten metal tank 11 is larger than the amount shown in FIG. The gas was explained using nitrogen gas for cost reduction. A reduced pressure impurity removing device for metals such as iron that is melted at a high temperature is called an RH device and is used in any steelworks. In these RH apparatuses, a steam ejector pump is used as a large-capacity vacuum pump, which is a means for exhausting non-metallic elements such as sulfur and hydrogen.

  On the other hand, in the case of a metal that melts at a relatively low temperature, such as aluminum scrap, the molten metal temperature is lower than that for iron, so that purification by flux or chlorine gas is sufficiently possible. Therefore, the means as described above are not so popular. However, facilities using chlorine gas are difficult to take environmental measures. Therefore, in recent years, there is an increasing demand for removing magnesium, zinc, lead and the like in scrap aluminum by the above-described means.

  However, since the vapor of molten aluminum is highly corrosive, it is difficult to use a vacuum gauge. If a general vacuum gauge is used as it is and installed, it will fail early and become unusable. Therefore, special techniques and devices are required for installing a vacuum gauge in an apparatus for purifying molten aluminum using inert gas and reduced pressure.

JP 2012-009290 A JP 2007-510272 A JP 2004-349102 A Japanese Patent Laid-Open No. 10-281911

It is sectional drawing which shows the outline of a molten metal refinement | purification apparatus. It is a conceptual diagram which shows one Example of the vacuum measuring apparatus by this invention. It is a conceptual diagram which shows the other Example of the vacuum measuring apparatus by this invention. It is a conceptual diagram which shows the other Example of the vacuum measuring apparatus by this invention.

  The present invention has been made in view of the above-described conventional problems, and provides a vacuum measuring apparatus in which molten metal vapor is less likely to enter and obstruction of a vacuum gauge due to the intrusion is less likely to occur. In particular, an object is to provide a structure suitable for mounting a vacuum gauge in a vacuum space.

  In the present invention, in order to achieve the above object, the vacuum gauge 31 is attached to the tip of the branch duct-shaped filter part 32 connected upward to the vacuum space 33. The filter unit 32 is heated to prevent the vapor from solidifying, and the orifice 34 is provided therein to prevent the vapor and droplets from entering the vacuum gauge 31 so as to return to the vacuum space 33. I made it.

  That is, the vacuum measuring apparatus according to the present invention connects a filter unit 32 having a branched duct shape upward to a decompressed vacuum space 33, heats the filter unit 32, and attaches a vacuum gauge 31 to the upper end of the filter unit 32. 32 is provided with an orifice 34 for trapping vapor or droplets. The upward gradient θ1 of the filter portion 32 for returning the steam and droplets to the vacuum space 33 is preferably 7 ° or more, which is the lowest angle at which the droplets easily flow down.

  The orifice 34 has a partition shape provided in the middle of the filter portion 32, and is preferably provided in a plurality of stages. The orifice 34 is provided with a molecule passage hole 35 through which a rare gas molecule passes. In the case where a plurality of stages of orifices 34 are provided in the filter portion 32, the molecular passage holes 35 of the orifices 34 are preferably arranged so as to be shifted from each other in the surface direction of the orifices 34. At the lower part of the orifice 34, a notch-shaped drain 36 is provided for allowing droplets attached to the wall surfaces of the orifice 34 and the filter portion 32 to flow downward.

  In such a vacuum measuring apparatus according to the present invention, the diluted gas in the vacuum space 33 is introduced into the vacuum gauge 31 through the filter unit 32, and gas molecules are detected by the vacuum gauge 31 to measure the vacuum. At this time, since the filter unit 32 is connected upward to the vacuum space 33, it is difficult for droplets to enter the vacuum gauge 31 from the vacuum space 33. Even if the liquid droplets enter the filter unit 32, the filter unit 32 is heated, so that the liquid droplets do not solidify and return to the vacuum space 33 side along the gradient of the filter unit 32, Discharged.

  In addition to this, since the orifice 34 is provided in the filter portion 32, the orifice 34 also prevents liquid droplets from entering the vacuum gauge 31 side. In particular, if the filter section 32 is provided with a plurality of stages of orifices 34 and the molecular passage holes 35 of the orifices 34 are shifted from each other in the plane direction, the effect of blocking the droplets is further enhanced. In the case where the notched drain 36 is provided at the lower part of the orifice 34, the droplets adhering to the wall surfaces of the orifice 34 and the filter part 32 are flowed downward along the gradient of the filter part 32, It can encourage the return.

  As described above, in the vacuum measuring apparatus according to the present invention, when the vacuum gauge 31 measures the vacuum in the vacuum space 33, it is difficult for vapor and droplets to reach the vacuum gauge 31 by the filter portion 32 and the orifice 34 provided thereon. Therefore, the trouble of the vacuum gauge 31 due to the intrusion of vapor or droplets is less likely to occur, and stable vacuum measurement is possible.

In the present invention, in order to achieve the above object, a branch duct-like filter portion 32 connected upward is provided in the vacuum space 33, and a vacuum gauge 31 is attached to the upper end thereof. The filter unit 32 is heated and provided with an orifice 34 for tripping vapor and droplets.
Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

  FIG. 2 shows an embodiment of a vacuum measuring device according to the present invention. For example, the above-described apparatus for purifying molten aluminum has a vacuum space 33 to be decompressed. FIG. 2 shows a structure in which the vacuum gauge 31 is attached to the vacuum space 33. In the example of FIG. 2, the vacuum space 33 is an example of a vertical pipe shape, and an arrow indicates the direction of gas flow.

  A duct-shaped filter section 32 is connected to the vacuum space 33 by giving an upward gradient, and the filter section 32 is heated by a heat source 37 to a temperature at which droplets therein do not solidify. The vacuum gauge 31 is provided at the upper end of the filter portion 32. As long as the filter portion 32 has an upward slope, the angle may change midway. Moreover, the structure where another tubular duct branches may be sufficient. In any case, the vacuum gauge 31 is provided at a position higher than the connection position of the filter unit 32 to the vacuum space 33. The gradient of the filter section 32 shown in FIG. 2 is θ1, and this θ1 is set to 7 ° or more, which is the minimum angle at which the droplets easily flow down. Further, the heat source 37 may be disposed in the vicinity of the filter portion 32 as illustrated, or may be attached in a state where a wire heater is wound so as to surround the tubular filter portion 32.

  The filter part 32 is provided with an orifice 34. As described above, the filter portion 32 has a duct shape, and the orifice 34 has a partition plate shape that partitions the filter portion 32 on the way. In the embodiment of FIG. 2, the internal passage of the filter portion 32 has a cylindrical shape, and the orifice 34 has a disk shape for partitioning it. The orifice 34 is provided with a molecule passage hole 35 for passing gas molecules at one or more places.

  The orifice 34 is preferably provided in the filter portion 32 in a plurality of stages, more specifically, three or more stages. The molecule passage holes 35 provided in the respective orifices 34 are provided so as to be shifted from each other in the surface direction. For example, when the molecule passage hole 35 of an orifice 34 is provided in the vicinity of the center, the molecule passage hole 35 of the orifice 34 above it is provided at a position deviated from the center. In FIG. 2, the arrow indicates a state in which molecules pass through the lower orifice 34.

  A cut-out drain 36 is provided in a part or all of the orifice 34. The drain 36 is provided below the orifice 34, that is, on the bottom surface side of the filter portion 32. In the embodiment of FIG. 2, a drain 36 is provided in the orifice 34 in the two stages from the bottom. The drain may be provided not only in the lower stage but in all the orifices 34.

  When the vacuum gauge 31 is used in such a vacuum measuring device, the heated filter unit 32 prevents moisture and molten metal splashes from entering the vacuum gauge 31, and the vacuum space 33 remains in a molten state while the molten metal remains in a molten state. It plays an important role in returning to the river. However, if the filter part 32 is simply installed, it will be clogged immediately. Therefore, after taking a large droplet, it is preferable that the droplet is naturally converted into a droplet while being heated to such an extent that it is not solidified by the filter unit 32, and then returned to the vacuum space 33 and discharged from the filter unit 32. In this state, it is effective to measure the vacuum pressure in the system through the filter unit 32.

  When the droplets are scattered in all directions from the splash flow, if the droplets adhere to the detection part of the vacuum gauge 31 or if the droplets block the detection part of the vacuum gauge 31, the vacuum gauge 31 does not show an accurate measurement value. . Accordingly, the orifice 34 is provided to prevent the liquid droplet from entering the vacuum gauge 31. The orifice 34 has three or more stages. Since the molecule passage holes 35 of the plurality of orifices 34 are displaced from each other in the plane direction, the droplets are prevented from reaching the vacuum gauge 31. The liquid droplet trapped at the orifice 34 before reaching the vacuum gauge 31 is guided to the bottom of the filter unit 32 through the notch-shaped drain 36 of the orifice 34, and then returns to the vacuum space 33 through the filter unit 32. Discharged. In order for the liquid droplets to flow smoothly and return to the vacuum space 33, the gradient θ1 of the filter unit 32 needs to be 7 ° or more, which is the minimum angle at which the liquid droplets naturally flow down.

  FIG. 3 shows another embodiment of the vacuum measuring apparatus according to the present invention. In this example, the vacuum space 33 is illustrated as a horizontal pipe. The filter part 32 is branched vertically to the horizontal vacuum space 33 and heated by a heat source 37. A vacuum gauge 31 is provided at the upper end of the filter part 32, a plurality of orifices 34 having molecular passage holes 35 are provided in the filter part 32, and the molecular passage holes 35 of each orifice 34 are displaced in the surface direction. The notch-shaped drain 36 is provided at least in the lower orifice 34 as in the embodiment described above with reference to FIG. The orifice 34 is provided inside the filter portion 32 with a gradient of θ2, and this θ2 is set to 7 ° or more, which is the minimum angle at which the droplets easily flow down.

  Also in this embodiment, since the molecular passage hole 35 of each orifice 34 is displaced in the surface direction, the droplet does not reach the vacuum gauge 31. The droplets trapped before reaching the vacuum gauge 31 return to the vacuum space 33 through the notch-shaped drain 36 and are discharged.

FIG. 4 shows a case where the vacuum gauge 31 is attached after the valve 39 and the metal mesh filter 38 are attached after the filter portion 32. Accordingly, very fine impurity vapor is removed by the metal mesh filter 38, and the vacuum gauge 31 can be restarted by simply closing the valve 39 and replacing the metal mesh filter 38 during maintenance. Since the filter portion 32 has a high temperature, a ceramic filter may be used instead of the metal mesh filter 38 as long as it has heat resistance and corrosion resistance. The internal configuration of the filter unit 32 is the same as that of the embodiment described above with reference to FIG.
The vacuum gauge 31 according to these embodiments is attached to the vacuum space 33 between the vacuum pump 4 and the impurity removal tank 1.

  In the present invention, for example, an inert gas such as Ar gas is blown into the molten metal, and the molten metal is stirred and circulated, so that gas and impurities contained in the molten metal are released from the molten metal and removed from the molten metal. It is possible to apply to the vacuum measurement etc. in the refiner | purifier of the molten metal to do.

31 Vacuum gauge 32 Filter part 33 Vacuum space 34 Orifice 35 Molecular passage hole 36 Drain 37 Heat source 38 Metal mesh filter 39 Valve

Claims (7)

In the vacuum measuring device provided with a vacuum gauge (31) in the vacuum space (33) to be depressurized, a branch duct-shaped filter part (32) is connected upward to the vacuum space (33), and this filter part (32) And a vacuum gauge (31) attached to the upper end thereof, and an orifice (34) for trapping vapor and droplets is provided in the filter part (32). The vacuum measuring device according to claim 1, wherein the upward gradient θ1 of the filter section (32) is 7 ° or more. The vacuum measuring device according to claim 1 or 2, wherein a plurality of orifices (34) are provided in the middle of the filter portion (32). The vacuum measuring device according to any one of claims 1 to 3, wherein the orifice (34 is provided with a molecule passage hole (35) through which a rare gas molecule passes. 5. The vacuum measuring device according to claim 4, wherein the molecular passage holes (35) of the orifices (34) are arranged so as to be shifted from each other in the surface direction of the orifices (34). A notch-shaped drain (36) is provided at the lower part of the orifice (34) to allow the liquid droplets adhering to the walls of the orifice (34) and the filter portion (32) to flow downward. The vacuum measuring apparatus in any one of -5. The vacuum measuring device according to any one of claims 1 to 6, wherein a valve (39) and a metal mesh filter (38) are attached between the filter part (32) and the vacuum gauge (31).

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