JPH0456094B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a metal band floating support method for supporting a metal band traveling in a heat treatment furnace such as a continuous annealing furnace in a non-contact manner using gas pressure, and the same. Regarding equipment.

<Prior Art> A threading line for metal strips such as steel plates requires a support device that guides and supports the metal strip, and guide rolls are usually used. However, in heat treatment furnaces such as continuous annealing furnaces, the tensile strength of the metal strip running in the furnace decreases as the temperature rises above 800°C. Contact may cause deformation of the metal strip. Therefore, in order to prevent such deformation of the metal strip, a floating support device is developed that uses the principle of hydrostatic bearings to spray high-pressure gas onto the underside of the metal strip and uses the pressure to support the metal strip without contact. It is used.

FIG. 2 is a configuration diagram of an example of this conventional floating support device. In FIG. 2, reference numeral 11 denotes a continuous annealing furnace, and the metal strip 13 is heat-treated while the metal strip 13 runs inside the furnace 11. The inside of the furnace 11 is maintained at a high temperature and is filled with a reducing gas such as hydrogen or nitrogen to prevent surface oxidation of the metal band 13. Inside the furnace 11, a wind box 15 for injecting gas toward the metal band 13 is installed directly below the metal band 13, while a circulation fan 17 is installed outside the furnace 11. Furnace 1 near Wind Box 15
High-temperature gas is sucked in from inside the wind box 15, the pressure is increased, and the gas is supplied to the wind box 15. The high-temperature, high-pressure gas supplied to the wind box 15 is injected from the nozzle port 19 formed on the surface facing the metal band 13, and gas is generated between the surface of the wind box 15 facing the metal band 13 and the metal band 13. The metal strip 13 is suspended and supported by the gas pressure.

<Problems to be solved by the invention> However, the conventionally used circulation fan 17
Because it is necessary to pressurize high-temperature gas to a high pressure, metal fans are required to have the ability to rotate at high speeds at high temperatures, and metal fans cannot withstand use due to their thermal deformation and cleavage phenomenon at high temperatures. . For this reason, fans are used that are made of special materials such as ceramics, which have excellent high-temperature resistance, but these have the drawbacks of being expensive, weak against shocks, and lacking in reliability.

On the other hand, since the gas in the furnace 11 contains hydrogen and the like, its specific gravity is low, and therefore there is a limit to the pressurization ability of the fan, making it unusable in some cases. For example, the critical pressure for pressurizing pure hydrogen (specific gravity 0.08 Kg/m ³ ) at 1000°C is about 100 to 150 mmAq using a conventional fan, which cannot satisfy the required pressure (300 mmAq).

The present invention was made in view of these circumstances, and it can be used without using expensive circulation fans.
It is an object of the present invention to provide a method and apparatus for levitating a metal strip, which can levitate the metal strip by injecting high-temperature, high-pressure gas while suppressing fluctuations in furnace pressure.

<Means for Solving the Problems> The metal strip floating support method according to the present invention achieves this object by injecting gas from a wind box onto the lower surface of the metal strip running in a high-temperature furnace. In a metal band floating support method for floatingly supporting a band,
After pressurizing low-temperature gas inside or outside the furnace, it is heated, and the high-pressure high-temperature gas is used as a driving gas for an ejector, while the driving gas is injected from a nozzle part in the ejector to create a negative pressure at a throat part. The high-temperature gas in the furnace is drawn into the ejector using the negative pressure, and the pressure is increased there, and the gas is sent to the wind box together with the driving gas.

Further, a floating support device for a metal strip according to the present invention that achieves the above object is a floating support device for a metal strip that levitates and supports the metal strip by injecting gas to the lower surface of the metal strip running in a high-temperature furnace. , a wind box located directly below the metal band and blowing gas toward the metal band, a nozzle part that communicates with the wind box and injects driving gas, and a throat part provided in front of the nozzle part. a compressor that boosts the pressure of low-temperature gas inside or outside the furnace; a heating device that heats up the gas pressurized by the compressor and supplies it to the nozzle part of the ejector as a driving gas; A suction channel is provided which communicates the high temperature part with the throat part and sucks high temperature gas in the furnace by the negative pressure generated in the throat part by the injection of driving gas from the nozzle part and guides it to the ejector. Features.

<Function> The low temperature gas pressurized by the compressor is heated by the temperature raising device to become high temperature and high pressure gas and is supplied to the ejector as a driving gas. In the ejector, the driving gas is injected at high speed from the nozzle part to create a negative pressure in the throat part, and the high-temperature gas in the furnace is sucked into the ejector through a suction passage leading into the furnace. The high-temperature gas sucked into the ejector is pressurized there and sent together with the driving gas to the wind box, where it is blown against the metal strip to levitate it.

<Example> Hereinafter, an example of the present invention will be described with reference to FIG. 1 showing its configuration.

FIG. 1A shows a first embodiment of the present invention, and as shown in FIG.
An ejector 21 located outside the furnace 11 is communicated with the wind box 15 via a flow path 23. The ejector 21 has a nozzle portion 25 and a throat portion 27 provided in front of the nozzle portion 25, and the throat portion 27 is communicated with the inside of the furnace 11 via a suction channel 29. The end of the suction channel 29 on the furnace 11 side is opened to a high temperature section H near the wind box 15, so that high temperature gas from that section in the furnace 11 can be supplied to the ejector 21. Further, the nozzle portion 25 of the ejector 21 is connected to a temperature raising device 33 via a flow path 31, and the temperature raising device 33 is connected to a compressor 37 via a flow path 35, and the inlet side of the compressor 37 is The wind box 15 is connected to a low-temperature section L in the furnace 11 located away from the wind box 15 via a flow path 39 . The compressor 37 sucks and pressurizes the low temperature gas in the furnace in the low temperature section L, and the temperature raising device 33 heats the pressurized high pressure low temperature gas to the same temperature as the high temperature section H in the furnace 11. In this embodiment, a heat exchanger is used as the temperature raising device 33, and the low temperature gas discharged from the compressor 37 is heated with high temperature combustion gas obtained from a device not shown.

In this way, the high-temperature, high-pressure gas that is pressurized by the compressor 37 and heated by the temperature raising device 33 is supplied to the ejector 21 as a driving gas, and the driving gas is injected from the nozzle portion 25 of the ejector 21 at high speed. Throat part 2
7 to generate negative pressure. Then, the high-temperature gas in the furnace 11 is sucked into the ejector 21 through the suction channel 29 due to the negative pressure, and the sucked high-temperature gas is pressurized there and is sent to the wind box 15 along with the driving gas.
The metal band 13 is blown onto the metal band 13 from the nozzle opening 19 to levitate the metal band 13. At this time,
The weight flow ratio of the gas passing through the compressor 37 and temperature raising device 33 to the gas sucked from the suction channel 29 can be operated at approximately 1:3 to 1:5.

The present inventors suctioned 300Nm ³ /h from the cooling zone (low-temperature section L) into the furnace gas consisting of pure hydrogen to increase the pressure to 4.5 atg, and then raised the pressure to 1100°C using the heating device 33. Heat and ejector 21
1350N from the heating zone (high temperature section H).
Suction hydrogen at m ³ /h x 1100℃, 300mmAq x 1100
By blowing air into the wind box 15 at a temperature of 0.5°C, a steel strip of 0.5 ^t mm x 500 ^w mm could be levitated.

On the other hand, FIG. 1b shows a second embodiment of the present invention, in which the driving gas for the ejector is introduced from outside the furnace. This is an example when the inside of the furnace 11 is filled with high-temperature combustion exhaust gas, and since the same type of combustion exhaust gas as inside the furnace 11 can be used,
This is manufactured and used outside the system. That is, as shown in FIG. 1b, air is pressurized by the compressor 37 and is supplied to the temperature raising device 43 via the flow path 41, and pressurized fuel is supplied from the flow path 45 to the temperature raising device 4.
By sending the combustion exhaust gas to the burner 47 of No. 3 and burning it, the combustion exhaust gas is supplied to the ejector 21 as a driving gas.

<Effects of the Invention> As described above in detail with reference to one embodiment, according to the present invention, it is possible to levitate and support a metal strip at low cost without using an expensive circulation fan.

[Brief explanation of the drawing]

FIGS. 1a and 1b are block diagrams of a metal band levitation support apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram of a metal band levitation support apparatus according to a conventional example. In the drawing, 11 is a continuous annealing furnace, 13 is a metal strip, 1
5 is a wind box, 21 is an ejector, 25 is a nozzle part,
27 is a throat portion, 29 is a suction channel, 33, 43
37 is a temperature raising device and a compressor.

Claims (1)

[Scope of Claims] 1. A metal strip floating support method in which a metal strip running in a high-temperature furnace is buoyed and supported by injecting gas from a wind box to the lower surface of the metal strip, which After increasing the pressure of the gas, it is heated, and the high-pressure high-temperature gas is used as a driving gas for the ejector.In the ejector, the driving gas is injected from the nozzle part to generate negative pressure at the throat part, and the negative pressure is used as the driving gas for the ejector. A method for floating and supporting a metal strip, characterized in that high-temperature gas in a furnace is sucked into the ejector, the pressure is increased there, and the air is sent to a wind box together with the driving gas. 2. In a metal strip levitation support device that levitates and supports a metal strip by injecting gas onto the lower surface of the metal strip running in a high-temperature furnace, the device is located directly below the metal strip and blows gas toward the metal strip. an ejector having a nozzle part that communicates with the wind box and injects driving gas, and a throat part provided in front of the nozzle part; and a compressor that boosts the pressure of low-temperature gas inside or outside the furnace. , a temperature raising device for raising the temperature of the gas pressurized by the compressor and supplying the gas to the nozzle portion of the ejector as a driving gas; and a heating device that communicates the high temperature section in the furnace with the throat portion to supply the driving gas from the nozzle portion. 1. A floating support device for a metal strip, comprising a suction flow path that sucks high-temperature gas in the furnace by the negative pressure generated in the throat portion due to injection and guides it to the ejector.