JPH07216440A - Vacuum degassing device Exhaust system dust adhesion prevention method and device - Google Patents

Abstract

(57) [Summary] [Purpose] For example, to prevent dust from adhering to the inner wall of a nozzle that ejects a high-pressure gas stream of a depressurization booster and / or an ejector used in molten metal vacuum degassing. [Structure] When selectively operating a depressurization booster and / or an ejector according to a target vacuum degree range during vacuum degassing of molten metal, a booster and / or an ejector driving steam that is not selected and stops driving steam supply Inert gas is jetted from the nozzle while it is stopped, and the flow velocity on the nozzle outlet side is maintained at 1.5 m / sec or more to prevent dust attached to the inner wall of the nozzle from degassing from the selectively operating ejector and / or booster. To prevent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for preventing dust from adhering to the inner wall of a nozzle for ejecting a high-pressure gas stream of a decompression booster and / or an ejector used for vacuum degassing of molten metal, for example.

[0002]

2. Description of the Related Art It is well known that vacuum processing is performed in various steps in a metal melting processing step. Particularly in steel manufacturing, high-quality products are manufactured by vacuum degassing of molten steel. Conventionally, in these vacuum processing steps, when a large amount of dust is contained in the exhaust gas, the ejector vacuum pump has been put to practical use because it has no moving parts as an exhaust device, has a long life, and can be easily maintained in operation. .

[0003]

However, in the case of the vacuum degassing treatment of molten steel, the exhaust gas contains a large amount of fine particles (dust) of molten steel and slag, which become low in temperature and are degassed by vacuum degassing. Coagulates and adheres to the inner wall of the exhaust system of the processing equipment, the pressure reducing booster and / or the inner wall of the ejector,
It gives various obstacles. Dust adhesion to the outside is removed by high pressure washing water as shown in FIG.
The tip of the inner wall of the nozzle can be washed, but the inside is difficult.

Therefore, no consideration is given to a high-pressure cleaning nozzle installed on the inner wall of the depressurization booster and / or the ejector to periodically wash off the adhered dust, or to adhere the dust to the inner wall of the nozzle ejecting the high-pressure gas flow. It is not paid, and the actual situation is that the cleaning operation is performed manually by stopping the operation of the device regularly. For example, in a conventional operation, as shown in FIG. 5, an operator enters a manhole of a booster to remove dust adhering to the inner wall of a nozzle that ejects a high-pressure gas stream. It is a place with poor working environment and is dangerous.

The present invention solves the above-mentioned conventional problems, and reliably prevents dust from adhering to the inner wall of the nozzle of the depressurization booster and / or the ejector for ejecting the high-pressure gas flow, thereby improving the operating rate of the apparatus. It is an object of the present invention to provide a dust adhesion prevention method and device that can be used.

[0006]

[Means for Solving the Problems] In order to solve the above problems, the inventors of the present invention have conducted extensive research and studies, and as a result, a booster that operates every time a target vacuum degree during operation of an exhaust system is reached,
When changing the combination of ejectors, check that the exhaust gas enters the nozzle that ejects the high-pressure gas flow and the dust adheres to the inner wall while the booster that is the stop target and the ejector are stopped. The inventors have found that dust can be prevented from adhering to the inner wall of the nozzle by supplying and ejecting an inert gas during this stop, and completed the present invention.

That is, according to the present invention, in selectively operating the depressurization booster and / or the ejector according to the target vacuum degree range during the vacuum degassing treatment of the molten metal, the booster and / or the non-selected booster for stopping the supply of the driving steam are provided. Alternatively, an inert gas is jetted to the ejector from the driving steam nozzle while it is stopped, and the flow velocity on the nozzle exit side is maintained at 1.5 m / sec or more for selective operation. The nozzle inner wall of dust accompanying deaeration from the ejector and / or booster A method for preventing adhesion of dust in a vacuum degassing exhaust system, which is characterized in that it adheres to air.

Further, according to the present invention, in a depressurization booster and / or an ejector used in a metal vacuum processing facility, an inert gas supply circuit is connected to a steam supply circuit to a nozzle for ejecting steam to stop the supply of steam. At the same time, an inert gas is supplied from the inert gas supply circuit to the nozzle, and a switching means is provided for stopping the supply of the inert gas to the nozzle at the same time when the supply of water vapor is started. This is a dust adhesion prevention device.

[0009]

The structure and operation of the present invention will be described. The present invention relates to a decompression booster 1a, 1b, 1c used in a metal vacuum processing facility such as a molten steel vacuum degassing apparatus 3 shown in FIG.
And / or ejectors 2a, 2b, 2c, 2d,
In order to prevent dust from adhering to the inner wall of each of the nozzles 2e, 2f, and 2s and hindering the operation, a purge line that branches from the inert gas supply circuit 4 and that includes the shutoff valve 5a is provided. Nitrogen is supplied from 18 to each nozzle of the booster and the ejector. The inert gas supply circuit 4 is attached to the exhaust duct 6 via the main recompression valve 5b. In the figure, 7a, 7b,
7c and 7d are condensers, 8 is a seal tank, 9 is a gas cooler, 10 is a ladle, and 11 is a lifting device.

FIG. 2 shows a booster, 1 is a booster body, 12 is a nozzle, 13 is a manhole, 14 is an exhaust duct suction port, and 15 is a duct discharge port. Drive steam line 1 attached to nozzle 12a of booster 1
A purge line 18 is connected to 6 to blow nitrogen into the nozzle. Reference numeral 17 is a valve of the drive steam line 16. FIG. 3 shows the ejector 2 in the same manner. The purge line 18 is connected to the drive vapor line 16 attached to the ejector nozzle 12b, and nitrogen is blown into the nozzle.

The intent of the present invention is to prevent the exhaust dust stream from flowing into the nozzle for ejecting the driving steam, and at the same time when the depressurization booster and / or the ejector are stopped, the driving steam line is stopped. A purge line 18 is connected to a driving steam line 16 leading to a nozzle of a pressure reducing booster and / or an ejector by closing a valve 17 of 16, and an inert gas such as nitrogen gas is supplied to the booster nozzle and the ejector nozzle. Nitrogen gas is injected to the booster and / or ejector which are stopped, and the flow velocity at the nozzle exit side is 1.5 m /
By maintaining the time of not less than sec, the exhaust gas flow is prevented from turning around.

[0012]

EXAMPLES Table 1 shows the operating procedure of each valve shown in FIG. 4, and shows the purge nitrogen flow rate and time.

[0013]

[Table 1]

Conventionally, in order to maintain a predetermined vacuum capacity because dust adheres to the inner surfaces of the booster and ejector nozzles, once a week, for example, in the case of a booster, a manhole is opened and a person enters the booster. ,bar·
Although dust on the inner surface of the nozzle was removed using a tool such as a scoop, the present invention eliminated the work.
Similarly, in the case of the ejector as well, the dust on the inner surface of the nozzle was removed once with a frequency of once a week, for example, by using a tool such as a hammer to pull out the nozzle of the ejector, but the present invention eliminates the work. It was

[0015]

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it is possible to expect a high operating efficiency and to provide a device excellent in practicability and durability by simply adding simple equipment. It can be improved, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is an overall schematic diagram of an apparatus to which the present invention is applied.

[Fig. 2] An explanatory view of the main part of the booster

FIG. 3 is a partial explanatory view of an ejector.

FIG. 4 is an explanatory diagram of a procedure of the exhaust system dust adhesion prevention method of the present invention.

5A is a diagram showing dust adhesion inside the booster steam nozzle, and FIG. 5B is a diagram showing dust adhesion inside the ejector steam nozzle.

[Explanation of symbols]

 1a decompression booster 1b decompression booster 1c decompression booster 2a decompression ejector 2b decompression ejector 2c decompression ejector 2d decompression ejector 2e decompression ejector 2f decompression ejector 2s decompression ejector 3 molten steel vacuum degassing device 4 no nozzle Active gas supply circuit 5a Leading pressure reducing valve 5b Main pressure reducing valve 6 Exhaust duct 7a Condenser 7b Condenser 7c Condenser 7d Condenser 8 Seal tank 9 Gas cooler 10 Ladle 11 Lifting device 12a Booster nozzle 12b Ejector nozzle 13 Manhole 14 Exhaust duct inlet Duct outlet 16 Driven steam line 17 Driven steam line valve 18 Purge line

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasuo Obana 1 Nishinosu, Oita-shi, Oita New Nippon Steel Oita Steel Co., Ltd.

Claims (2)

[Claims] 1. A booster and / or an ejector which is non-selected to stop the supply of driving steam when selectively operating a depressurizing booster and / or an ejector according to a target vacuum degree range during vacuum degassing of molten metal. During operation, the inert gas is jetted from the driving steam nozzle to maintain the nozzle outlet side flow velocity at 1.5 m / sec or more to selectively operate the ejector and / or booster to prevent dust from adhering to the inner wall of the nozzle. Vacuum degassing exhaust system dust adhesion prevention method characterized by preventing. 2. A depressurizing booster and / or an ejector used in a metal vacuum processing facility, wherein an inert gas supply circuit is connected to a steam supply circuit to a nozzle for ejecting steam, and the inert gas supply circuit is connected to the inert gas supply circuit at the same time when the steam supply is stopped. An inert gas is supplied from the gas supply circuit to the nozzle, and the supply of the inert gas to the nozzle is stopped at the same time when the supply of steam is started. Vacuum degassing equipment with switching means Exhaust system dust adhesion prevention device.