JP2000227284A - Vacuum refining equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a pressure loss due to sticking of smoky dust to the inside of an exhaust duct of a vacuum refining furnace such as AOD, VOD or RH or a vessel and of a gas cooler. SOLUTION: An exhaust gas channel of a vacuum refining furnace 1 is provided with a bypass channel 6 in parallel with a gas cooler 3, and a water- cooled jacket 9 is so provided as to surround the tube body of the bypass channel 6, while an exhaust gas temperature gage 8 and an opening regulation damper are provided. Exhaust gas is passed through both of the gas cooler 3 and the bypass channel 6, while the temperature of the exhaust gas introduced into a dry type dust collector 4 is made the hear-resistance temperature of the collector 4 or below. According to this constitution, the quantity of the exhaust gas introduced into the gas cooler 3 can be lessened, while overheat of the dry type dust collector 4 is prevented. Therefore the amount of smoky dust sticking to the inside of an exhaust duct 2 and the gas cooler 3 is lessened and it is possible to reduce a pressure loss due to sticking of the smoky dust and to execute vacuum refining with excellent efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to AOD, VOD,
The present invention relates to an apparatus for reducing pressure loss due to adhesion of smoke dust to an exhaust duct and a gas cooler of a decompression refining furnace such as RH or a vessel (hereinafter, simply referred to as a decompression refining furnace).

[0002]

2. Description of the Related Art Generally, in the smelting of stainless steel and ultra-low carbon steel, in order to suppress deoxidization of iron and chromium and perform decarburization efficiently, vacuum refining by blowing oxygen from a lance or tuyere under reduced pressure. Has been adopted. In such vacuum refining, strong stirring of the molten steel is required in order to promote the reaction to a superior level, but this generates a large amount of heat and at the same time generates a large amount of dust containing iron oxide.

As shown in FIG. 3, conventionally, exhaust gas generated from a vacuum refining furnace 1 is cooled from an exhaust duct 2 through a gas cooler 3, smoke is removed through a dry dust collector 4 such as a bag filter, and then exhausted. When introduced into the device 5, the dust in the exhaust gas adheres to the inner surfaces of the exhaust duct 2 and the gas cooler 3 to cause a pressure loss in the exhaust gas path.

[0004] When a pressure loss occurs, the pressure in the vacuum refining furnace increases, resulting in a reduction in refining efficiency. Although a large amount of Ar gas is supplied to maintain the refining efficiency, it is not sufficient. As a result, a large amount of Ar gas is consumed, the refining time is prolonged, the efficiency is reduced, and the refractory material is increased in erosion.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the pressure loss due to the adhesion of smoke dust to the exhaust duct and the gas cooler of the vacuum refining furnace, and to efficiently perform the vacuum refining.

[0006]

Means for solving the above problems are as follows: exhaust gas from a vacuum refining furnace is passed through a gas cooler;
In a device for passing a dry dust collector, a bypass path is provided in parallel with the gas cooler, a water cooling jacket is provided around a pipe of the bypass path, and an exhaust gas thermometer is provided between the gas cooler and the dry dust collector. An evacuation refining apparatus characterized in that an opening degree adjustment damper adjusted by a temperature measured by an exhaust gas thermometer is provided in the bypass path.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. In FIG. 1, components having the same names and functions as those in FIG. 3 are denoted by the same reference numerals. FIG.
In the above, a bypass path 6 for bypassing the gas cooler 3 is provided, an opening adjustment damper 7 is provided in the bypass path 6, and an exhaust gas thermometer 8 is provided between the gas cooler 3 and the dry dust collector 4. As shown in FIG. 2, a water cooling jacket 9 is provided around the pipe of the bypass passage 6.

In FIG. 1, the exhaust gas discharged from the vacuum refining furnace 1 is cooled from the exhaust duct 2 through the gas cooler 3 and then to the dry dust collector 4 and the bypass duct 6 from the exhaust duct 2. There is provided a path through which the water is cooled by the water-cooling jacket 9 (FIG. 2) and then reaches the dry dust collector 4.

FIG. 2 is a cross-sectional view of the bypass path 6, and FIG.
1 is a water supply port, 12 is a drain port, and 13 is a smoke exhaust port.
The cooling water that has exited the drain port 12 is supplied again from the water supply port 11 through a cooler (not shown).

The temperature of the exhaust gas introduced into the dry dust collector 4 from the gas cooler 3 and the bypass path 6 is measured by an exhaust gas thermometer 8 and the measured temperature signal is adjusted by the adjusting device 1.
Enter 0. The adjusting device 10 compares the measured temperature signal with a preset signal of the heat-resistant temperature of the dry dust collector 4 and adjusts the opening degree such that the temperature of the exhaust gas introduced into the dry dust collector 4 becomes lower than the heat-resistant temperature. Adjust the damper 7. The opening adjustment damper 7 may be an on-off valve or a flow adjustment valve.

Table 1 shows the operating conditions and the average value of the results obtained when the stainless steel was smelted 10 times in each of the embodiment using the apparatus of the present invention shown in FIG. 1 and the comparative example not using the bypass path. showed that. In the example, of the gas flow rate of 3200 kg / hr passing through the exhaust duct, 1000 kg / hr was passed through the bypass path. A vacuum AOD furnace was used as the vacuum refining furnace, and the average temperature of the exhaust gas at the gas cooler inlet was 400 ° C.

[0012]

[Table 1]

As shown in Table 1, the degree of vacuum in the AOD furnace was 60 torr in the comparative example, but was reduced to 40 torr in the example. As a result, the Ar gas consumption can be reduced by 20 Nm ³ / ch, and the refining time is 0.7 minutes / c.
h was shortened. Although the temperature of the exhaust gas introduced into the dry dust collector was 38 ° C. in the comparative example, it was as high as 90 ° C. in the example, but no problem occurred in the bag filter.

[0014]

As described above, in the present invention, the bypass path is provided in parallel with the gas cooler, and the exhaust gas is introduced into the dry dust collector through both the gas cooler and the bypass path, and the exhaust gas is introduced into the dry dust collector. Temperature is set to be lower than the heat-resistant temperature of the dry dust collector.
The amount of exhaust gas passing through the exhaust duct and the gas cooler can be reduced while preventing the dry dust collector from overheating. As a result, the amount of smoke dust adhering to the inner surfaces of the exhaust duct and the gas cooler is reduced to reduce the pressure loss due to the smoke dust adhesion, so that the vacuum refining can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a diagram showing an exhaust gas path of the present invention.

FIG. 2 is a sectional view of a water cooling bypass path.

FIG. 3 is a diagram showing a conventional exhaust gas path.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Decompression refining furnace 2 Exhaust duct 3 Gas cooler 4 Dry dust collector (bag filter) 5 Vacuum exhaust device 6 Bypass path 7 Opening adjustment damper 8 Exhaust gas thermometer 9 Water cooling jacket 10 Adjustment device 11 Water supply port 12 Drainage port 13 Smoke exhaust port

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomoaki Tanaka 3434 Shimada, Hikari-shi, Yamaguchi Prefecture Nippon Steel Corporation Hikari Works (72) Inventor Makoto Kado 46-59 Ohara Nakahara, Tobata-ku, Kitakyushu, Fukuoka Prefecture F-term in Nippon Steel Plant Design Co., Ltd. (reference) 4K001 AA10 BA24 GA19 GB09 4K013 AA01 BA07 CA09 CA25 CE00 CE01 CE09 CF11 FA01 4K056 AA02 BA04 CA02 DB13 DC05 DC17 FA08 FA13 FA27

Claims (1)

[Claims] 1. A device for passing exhaust gas from a vacuum refining furnace through a gas cooler and then passing through a dry dust collector, wherein a bypass path is provided in parallel with the gas cooler, and a pipe of the bypass path surrounds a water cooling jacket. An exhaust gas thermometer is provided between the gas cooler and the dry dust collector, and an opening adjustment damper adjusted by a temperature measured by the exhaust gas thermometer is provided in the bypass path. apparatus.