JPH0551391B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a dust collection device for a refining ladle, and more specifically, when a dust-containing gas generated in the ladle is sucked through a duct provided in a hood. A refining ladle in which dust separated from the dust-containing gas is collected by falling into an external hopper, thereby preventing a reduction in dust collection ability and a reduction in ladle operating efficiency due to frequent duct cleaning. The present invention relates to a dust collector.

Prior Art In molten steel melted in a melting furnace such as an arc furnace or a converter, impurities consisting of nonmetallic inclusions such as hydrogen, oxygen, sulfur, and other oxides generally remain. Therefore, in order to remove the impurities from the molten steel and produce steel with improved steel quality, refining equipment is generally provided in a subsequent process and is suitably used for re-smelting the molten steel. As this refining method, various types of refining methods such as suction vacuum refining method and ladle refining method such as VAD method and LF method have been implemented. In particular, the latter method is characterized by transferring the molten steel melted in the melting furnace to a ladle, heating the molten steel in the ladle while stirring it, and refining it under a reducing atmosphere.

In other words, the ladle refining method is equipped with electric arc heating or resistance heating equipment using a three-phase power source, and it has become possible to melt the slag added to the ladle and heat up the molten steel at the same time. There is. However, on the other hand, since dust-containing gas is generated in the ladle as a result of the refining, it is necessary to install a dust collection means to collect the gas.

Taking the LF method as an example of the in-ladle refining method, as shown in FIG. After pouring the slag 16, the ladle 12 is covered with a refractory lid 18. The molten steel 14 is heated by arc, and an inert gas such as argon is blown from the bottom of the ladle to refine the steel while stirring. That is, three through holes 20 of a predetermined diameter are bored at the top of the furnace lid 18, and a graphite electrode 22 connected to a three-phase AC power source is vertically inserted into each through hole 20, and the lower tip of the electrode is inserted. It is located slightly above the level of the molten steel 14 and reducing slag 16 remaining in the pot 12.

Further, the furnace lid 18 is provided with a chute 24 for introducing slag material made of lime, alumina, etc., and additives such as ferroalloy for composition adjustment, and the additives are introduced from an additive storage tank (not shown). The chute 24 is designed to open only when the vehicle is opened. Note that a porous plug for blowing inert gas is provided at the bottom of the ladle, but its illustration is omitted.

By the way, in the above-described ladle refining method, when arc heating is performed using an electrode, the reducing slag 16 floating on the surface of the molten steel 14 loses its components such as
Dust mainly consisting of fine powders such as MgO, Cao, Sio ₂ and FeO is scattered and remains in the ladle 12. Therefore, it is necessary to collect this dust, but in order to prevent secondary oxidation of the molten steel, the inside of the ladle 12 needs to be maintained in a reducing atmosphere with oxygen supply cut off. The dust cannot be collected directly. Therefore, as shown in Figure 3,
A hood 26 surrounding and covering the electrode 22 and a suction duct 28 communicating with the hood 26 are provided at the top of the furnace lid 18 to suck the dust from an annular space formed between the electrode 22 and the through hole 20. Dust collectors have been put into practical use. Since the dust is contained in the reducing gas in the ladle in a suspended state, the object to be collected by the dust collecting means is referred to as "dust-containing gas" in this specification.

Problems to be Solved by the Invention However, in the conventional dust collector, there is a structural restriction in that three electrodes 22 are inserted through the top of the hood 26, so as shown in FIG. is structured to be led out horizontally from the side of the hood. Moreover, the height (inner height) of the hood to the internal ceiling is, for example,
As shown in FIG. 2 of the 51850 publication, since it is relatively small, only a narrow space is defined within the hood. The dust accompanying the reducing gas that has reached a high temperature in the ladle 12 rises rapidly through the annular space provided in the furnace lid 18, but as mentioned above, the inner height of the hood 26 is relatively low. Since the target is small, the dust-containing gas collides with the top plate of the hood 26 and is rapidly decelerated. In addition, the decelerated dust-containing gas is sucked by the duct 28 connected to the side of the hood 26 and horizontally changed direction, thereby separating the dust and the gas. For this reason, more and more dust 30 accumulates around the connection between the hood 26 and the suction duct 28, as shown in the figure.

This accumulation of dust 30 narrows the opening area of the duct 28 and significantly reduces dust collection efficiency. Furthermore, it is necessary to interrupt the refining of the ladle in order to clean the duct 28, resulting in inconveniences such as a decrease in operational efficiency. For example, in the past, molten steel was poured into the ladle two to three times (total of about 5 hours), and the actual situation was that the dust collection capacity was reduced by about half due to the accumulation of dust in the duct.

OBJECT OF THE INVENTION The present invention has been proposed in view of the above-mentioned drawbacks inherent in the conventional dust collecting device for a refining ladle. The purpose is to prevent the inconvenience of significantly reducing dust collection efficiency due to accumulation of dust in the ladle, and at the same time to improve the efficiency of refining operations in the ladle.

Means for Solving the Problems In order to overcome the above problems and achieve the initial objectives, the present invention provides a plurality of electrodes that are removably inserted into the electrode insertion portion of the furnace cover that is attached to the refining ladle. The electrode is disposed on the top of the furnace lid, and is raised to a sufficiently large internal height so as to minimize the speed of the dust-containing gas generated in the ladle during refining and arriving from the electrode insertion part. A dust collector comprising a hood and a suction duct connected to the top of the hood and led out vertically upward, wherein the dust-containing gas is sucked and collected by the suction duct, wherein the suction duct is The suction duct extends horizontally and is gently bent so as not to disturb the smooth flow of the dust-containing gas to which the suction is performed after being led vertically upward from the hood. At the same time, it is connected in communication with the side surface of a dust collection hopper having a diameter larger than that of the duct, and at the same time, it is connected to the side surface of the dust collection hopper at a portion displaced approximately perpendicularly to the connection portion of the suction duct from the hopper. A small-diameter suction duct is connected and extends horizontally, and the dust-containing gas passing through the suction duct is rapidly decelerated by the large-diameter dust collection hopper to separate it into dust and gas. The present invention is characterized in that the dust is collected by falling into the hopper.

Embodiments Next, a preferred embodiment of the dust collector for a refining ladle according to the present invention will be described with reference to the accompanying drawings. Note that the same members as those already explained in connection with FIG. 3 will be designated by the same reference numerals to simplify the explanation.
FIG. 1 schematically shows a preferred embodiment of the dust collector according to the present invention, in which a hood 26 extends vertically upward to a sufficiently large extent compared to conventional hoods, and has a high internal height. is set large. That is, the hood 26 disposed on the top of the furnace cover 18
The internal height of the ladle 12 is raised to a size that prevents the velocity of the gas from being reduced as much as possible when the dust-containing gas in the ladle 12 enters the hood from the electrode insertion part 20. Note that the internal height of the hood 26 is, for example, 46 to
It is preferable to set it so that it is about 50cm larger.

The suction duct 28 is connected to the top eccentric position of the raised hood 26 and extends vertically upward. That is, the three electrodes 22 are inserted through the top of the furnace lid 18 as described above, and therefore it is difficult to connect the suction duct 28 to the center of the furnace lid. For this reason, as is clear from FIGS. 1 and 2, one side of the hood 26 is made to protrude obliquely in the horizontal direction, and the furnace cover 18 is
A suction duct 28 is connected from above to the eccentric projecting portion, and is led out vertically upward. This overhanging part is the hearth lid 18
It is arranged at a position that does not interfere with the chute 24 provided in the ladle 12, the operation port for sampling the molten steel in the ladle 12, etc.

Furthermore, a suction duct 28 is connected to the dust collector.
is bent at a substantially right angle along the length of its extension. At this bend, the flow rate of the dust-containing gas is reduced, the dust and gas are separated, and the dust is collected into a hopper connected to the bend, thereby further improving dust collection efficiency. There is.

For example, the suction duct 28 vertically led out from the top eccentric position of the hood 26 is gently curved so as not to disturb the smooth flow of the dust-containing gas sucked by the dust collector, as described later, and the direction of the suction duct 28 is It has been converted horizontally and continues to extend for a predetermined distance. The suction duct 28 is connected to the upper side surface of a vertical dust collection hopper 32 having a larger diameter than the duct 28 at the end of its horizontal extension. Further, another suction duct 28 having a smaller diameter than the hopper 32 is connected to a side surface of the hopper 32 and at a position displaced approximately at right angles to the connection part of the duct 28, and also extends in the horizontal direction. There is. Note that the other end of this other suction duct 28 is connected to a dust collector (not shown).

The hopper 32 has, for example, a cylindrical main body, which is converged downward into a truncated conical shape, and has an opening at its lower end. A lid 34 is attached to this opening so as to be openable and closable, and is connected to, for example, a pneumatic cylinder 34 to drive the lid 34 to open and close as appropriate. Note that the hopper 32 may take the form of a cyclone. Further, a bucket 38 for collecting dust is movably disposed below the hopper 32, and is configured to collect dust that falls when the lid 34 is opened. That is, after dust is collected in the bucket 38, the bucket 38 is transported to a dust disposal yard, and another bucket 38 is brought below the hopper 32 to continue collecting dust.

Effects of the Embodiment The effects of the dust collector for a refining ladle according to the embodiment configured as described above will be described below. After pouring molten steel 14 melted in a melting furnace to a predetermined level into a ladle 12 and further adding, for example, basic reducing slag 16, a furnace lid 18 is attached to the ladle. Further, an electrode 22 is inserted into the ladle through the through hole 20, and the molten steel 14 is reheated by an arc, and at the same time, the molten steel 14 is stirred by blowing inert gas from the bottom of the ladle.

At this time, a large amount of dust is generated in the ladle 12 placed in a reducing atmosphere as the reduction reaction progresses. This dust is entrained by high-temperature reducing gas,
It rises from the small annular gap formed between the through hole 20 of the furnace 18 and the electrode 22 and is collected by the hood 26. In this case, the hood 26 is raised to provide sufficient internal height as described above.
Moreover, since the suction duct 28 is led out vertically from the top of the hood, the dust-containing gas is sucked into the duct 28 without being hindered from its natural upward flow. That is, the dust-containing gas generated in the ladle 12 during refining and arriving into the hood 26 from the electrode insertion portion 20 is sucked into the duct 28 without reducing its speed as much as possible. Therefore, the accumulation of dust in the vicinity of the hood connection part of the suction duct 28 is dramatically reduced, and the duct 28 is not blocked by a large amount of dust accumulating in a short period of time as in the conventional case.

Further, the dust-containing gas sucked and collected by the duct 28 passes through the duct at a required flow rate, but as described above, the duct 28 bends at a substantially right angle while extending horizontally. Since the hopper 32 is connected to the dust collection hopper 32 having a larger diameter, the dust-containing gas is rapidly decelerated at this bent portion, and the dust and the gas are separated well. And this separated dust with high specific gravity (for example, Fe, Cao, Mgo, etc.)
falls and is collected into a hopper 32 connected to the bent portion. Further, the gas from which dust has been separated is discharged to the outside of the system via the duct 28.

Effects of the Invention As explained above, according to the dust collection device for a refining ladle according to the present invention, the dust-containing gas generated in the refining ladle and arriving in the hood is removed from the gentle bend in the suction duct. Since the dust passes through the hood, its smooth flow is not obstructed, and therefore, a large amount of dust does not accumulate in the hood. Further, while the dust transfer gas is being transferred by suction through the horizontal suction duct, it reaches the part of the dust collection hopper 32 which has a larger diameter than the duct, where it is rapidly decelerated and the dust and gas At the same time, the dust falls into the hopper and is collected. As described above, according to the present invention, the amount of dust that accumulates in the duct over time is reduced overall, and since frequent cleaning of the duct is no longer required, ladle operation efficiency can be improved, etc. , has many beneficial effects.

[Brief explanation of drawings]

FIG. 1 is a schematic structural diagram showing an embodiment of a dust collector for a refining ladle according to the present invention, FIG. 2 is a schematic plan view of FIG. 1, and FIG. FIG. 2 is a schematic diagram of a dust collector for a ladle. 12... Ladle, 18... Furnace lid, 22... Electrode,
26...Hood, 28...Suction duct, 32...
Hotupa.

Claims (1)

[Scope of Claims] 1. A plurality of electrodes 22 that are removably inserted into electrode insertion portions 20 of a furnace lid 18 attached to a refining ladle 12, and a plurality of electrodes 22 disposed on the top of the furnace lid 18. , a hood 26 with a raised internal height that is sufficiently large so as not to reduce the speed of the dust-containing gas generated in the ladle 12 during refining and arriving from the electrode insertion part 20 as much as possible, and a top of the hood 26. It consists of a suction duct 28 that is connected and led out vertically upward,
In the dust collector in which the dust-containing gas is sucked and collected by the suction duct 28, the suction duct 28 is configured to smoothly collect the dust-containing gas that is suctioned after being led out vertically upward from the hood 26. The suction duct 28 extends in the horizontal direction while being gently bent so as not to obstruct the flow, and at the end of the horizontal extension, the suction duct 28 touches the side surface of the dust collection hopper 32, which has a larger diameter than the duct 28. At the same time, a suction duct 28 having a diameter smaller than that of the hopper 32 is disposed on the side surface of the dust collection hopper 32 and displaced approximately at right angles to the connection area of the suction duct 28.
The dust-containing gas passing through the suction duct 28 is rapidly decelerated by the large-diameter dust collection hopper 32 and separated into dust and gas. A dust collector for a refining ladle, characterized in that it is configured to collect dust by falling into the hopper 32.