JPH1089855A - Waste gas processing device in electric furnace provided with scrap-furnace top pre-heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate an occurrence of trouble caused by scrap sucked into a waste gas discharging passage in an electric furnace for pre-heating the scrap by a furnace top pre-heating device. SOLUTION: This electric furnace 1 is constructed to have a scrap furnace top end pre-heating device operated such that there are provided pre-heating chambers 4, 5 capable of storing metallic scrap on the electric furnace 1, wherein waste gas of the electric furnace 1 is passed through the pre-heating chambers and discharged to a waste gas discharging passage. In this case, there is provided a scrap catcher 20 composed of a U-shaped flow passage for use in lowering the waste gas into the waste gas discharging passage in a right downward direction and further raising the waste gas just above the passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus provided with a preheating chamber for preheating a metal scrap with waste gas on an electric furnace, and collects the scrap flowing into a discharge system by riding the flow of the waste gas. The present invention relates to a waste gas treatment apparatus that can be used.

[0002]

2. Description of the Related Art In an electric furnace such as an arc furnace for melting metal scrap, a preheating chamber is provided on the furnace, and once the metal scrap is stored in the preheating chamber, the metal scrap is preheated by waste gas to save energy. The furnace top preheating device which contributes to the conversion is disclosed in JP-A-8-13616.
It is conventionally known from Japanese Patent Publication No. 3 and other publications.

In such a furnace top preheating apparatus, the scrap is moved from the roof at the top to an upper preheating chamber, a lower preheating chamber, and an electric furnace. Therefore, the waste gas is always sucked into the exhaust system. For this reason, thin scraps are sucked into the discharge system, and these scraps bite or accumulate in the interior of the deodorization tower or cooling tower, the blower, or the baghouse, and cause abnormal vibration of the blower. And suction troubles such as abnormal rise in piping pressure loss. Once such a trouble is caused, it takes a lot of trouble to take out the scrap from the inside of the duct, the inside of the tower, or the like, so that the maintenance cost may be extremely high.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate the possibility of occurrence of a trouble in a waste gas discharge system caused by scrap suction in an electric furnace having the above furnace preheating device. .

[0005]

For this purpose, the present invention provides a preheating chamber capable of accommodating metal scrap on an electric furnace, and discharges waste gas from the electric furnace through the preheating chamber and discharges the waste gas to a waste gas discharge system. An electric furnace equipped with the above-mentioned scrap furnace top preheating device, characterized in that a scrap catcher comprising a U-shaped flow path that raises the waste gas directly upward after lowering the waste gas directly downward is provided in the waste gas discharge system. And Further, the present invention is characterized in that in the waste gas treatment apparatus, the inner diameter of the U-shaped flow path is set so that the descending speed of the waste gas is faster than the rising speed. Further, the present invention is characterized in that in the waste gas treatment apparatus, a baffle plate for suppressing a rise of scrap is provided below the U-shaped channel.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a diagram of a waste gas discharge system of this apparatus. In the figure, 1 is an electric furnace (arc furnace), 2 is its electrode, 3
Is a tap hole, 4 and 5 are preheating chambers provided in the upper and lower stages on the electric furnace 1, and 6 and 6 can be developed at the bottom of the upper preheating chamber 4 by operating a cylinder (not shown). A pair of fork-shaped air-permeable bottom plates pivotally supported so as to form a pair of fork-shaped ventilation holes which are pivotally supported at the bottom of the lower preheating chamber 5 so as to be able to expand downward by the operation of the cylinder. A bottom plate, 8 and 8 are lid plates provided on the upper part of the preheating chamber 4,
Reference numeral 9 denotes an open bottom bucket suspended by a crane wire to transport scrap. In addition, the opening edge of the extension cylindrical portion 10 extending from the lower end of the preheating chamber 5 matches the upper edge opening of the electric furnace 1, and has an arcuate shape which is in sliding contact with each other so that the electric furnace 1 can be tilted. Is formed. Reference numeral 11 denotes a circulation duct that connects the side wall of the extension tube portion 10 and the side wall of the preheating chamber 4 to guide the waste gas of the electric furnace 1 directly to the upper preheating chamber 4.

[0007] A waste gas outlet 12 is provided on the side wall of the preheating chamber 5, and a waste gas duct 13 is connected to the waste gas outlet 12. Reference numeral 14 denotes an opening / closing connection port provided for taking outside air into the waste gas duct 13 when required. For this reason, in this preheating apparatus, the high-temperature waste gas generated in the electric furnace 1 flows through the scrap in the preheating chamber 5 and is discharged to the waste gas outlet 12, and at the same time, passes through the circulation duct 11 to the preheating chamber 4. It is guided and flows through the space between the scraps in the preheating chamber 4 from top to bottom and is discharged to the waste gas outlet 12. The scrap preheated in the preheating chamber 4 is moved to the preheating chamber 5 by opening the bottom plates 6 and 6, and the scrap further preheated in the preheating chamber 5 is opened in the electric furnace 1 by opening the bottom plates 7 and 7. throw into.

Reference numeral 20 denotes a scrap catcher provided in the waste gas duct 13, and reference numeral 30 denotes the scrap catcher 20.
, A deodorizing tower provided in the discharge system, a cooling tower 40, an intake blower 50, a bag filter 60, and waste gas from the electric furnace 1 is sucked by the intake blower 50 to be scrapped by the scrap catcher 20, It is sent to the bag filter 60 through the deodorization tower 30 and the cooling tower 40. Ducts are provided to the bag filter 60 so that waste gas in the building is sucked from a hood 61 provided above the tap 3 and a hood 62 provided above the preheating chamber 4. The deodorization tower 30 is provided with a plurality of burners 31 in the tower, and deodorizes by burning combustible components, odorous gas and the like in the waste gas. The cooling tower 40 has a structure in which a thin tube 41 for circulating cooling water is provided in the tower to cool waste gas by heat exchange.

However, the scrap catcher 2
0, the descending path 22 and the ascending path 2 are provided by providing the partition plate 21 in a hanging shape as shown in an enlarged cross section in FIG.
3, a scrap retainer 24 is provided below the partition plate 21 at a sufficient distance from the lower end of the partition plate 21, and open / close bottom plates 25, 25 are provided at the bottom of the scrap retainer 24. By slightly inclining the partition plate 21 toward the descending path 22, the inner diameter of the descending path 22 is made smaller than the inner diameter of the ascending path 23. Reference numeral 26 denotes a baffle provided at the lower part of the ascending path 23 to suppress the rise of scrap. Reference numeral 27 denotes a rectifying plate provided at the upper part of the ascending path 23 for guiding the waste gas toward the discharge port.

[0010] Therefore, the waste gas guided into the scrap catcher 20 through the waste gas duct 13 descends directly below the descending path 22 and then rises directly above the ascending path 23. Incidentally, by setting the partition plate 21 to be inclined such that the inner diameter of the descending passage 22 is smaller than the inner diameter of the ascending passage 23, the descending speed V1 of the waste gas is, for example, 8 to 10 m / s.
The ascending speed V2 is 5 to 7 m / s, and the descending speed V1 is set to be faster than the ascending speed V2. Due to the sudden drop and change of direction of the waste gas, the scrap mixed in the waste gas is stalled and hits the scrap stay 24. And ensure that they can be collected. Then, the rising speed of the rising path 23 of the waste gas is made slower by this, so that the rising of the scrap is prevented. In addition, the baffle plate 26 is effective for further preventing the scrap from rising at that portion. The scrap stored in the scrap stay 24 is carried out by opening the opening and closing bottom plates 25, 25 as appropriate.

FIG. 3 shows that the lower part of the partition plate 21 is
Although the inner diameter on the descending path 22 side is narrowed by bending to the two sides, a speed difference between the descending path 22 and the ascending path 23 can be provided even in such a form. In this embodiment, the exhaust gas is discharged from the lower preheating chamber 5. However, the number of preheating chambers, the exhaust port of the waste gas, and the like are not limited to this embodiment, but may be various.

[0012]

As described above, the waste gas treatment apparatus of the present invention
By installing a scrap catcher in the waste gas discharge system, it is possible to reliably collect the scrap flowing in from the furnace top preheating chamber, so that it is possible to avoid the problem that the scrap does not flow into the deodorization tower or the cooling tower. There is a beneficial effect that makes maintenance easier.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a waste gas treatment device in an electric furnace having a scrap furnace top preheating device according to the present invention.

FIG. 2 is an enlarged vertical sectional view of the scrap catcher of FIG.

FIG. 3 is a longitudinal sectional view showing another embodiment of the scrap catcher of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric furnace 4 Preheating chamber 5 Preheating chamber 6 Air permeable bottom plate 7 Air permeable bottom plate 12 Waste gas outlet 13 Waste gas duct 20 Scrap catcher 21 Partition plate 22 Descending path 23 Ascending path 24 Scrap retention 25 Opening bottom plate 26 Baffle plate 27 Rectifying plate 30 Deodorization Tower 40 Cooling tower 50 Intake blower 60 Bag filter

Claims (3)

[Claims] A scrap furnace top preheating device is provided on an electric furnace, wherein a preheating chamber capable of housing metal scrap is provided, and waste gas from the electric furnace flows through the preheating chamber and is discharged to a waste gas discharge system. An electric furnace provided with a scrap furnace top preheating device, characterized in that a scrap catcher comprising a U-shaped flow path is provided in a waste gas discharge line, in which the waste gas is lowered directly downward and then ascended right above. Waste gas treatment equipment in electric furnaces. 2. An electric furnace equipped with a scrap furnace top preheating device according to claim 1, wherein the inner diameter of the U-shaped flow path is set so that the descending speed of the waste gas is faster than the rising speed. Waste gas treatment equipment. 3. The waste gas treatment apparatus for an electric furnace equipped with a scrap furnace top preheating device according to claim 1, wherein a baffle plate for suppressing the rise of scrap is provided below the U-shaped flow path.