JPH0243113B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dust collection method in a melting furnace such as an electric furnace.

[Conventional technology]

Conventionally, soot and smoke containing a large amount of dust is generated when raw material scrap is input during melting work or when oxygen is blown into an electric furnace. Dust collectors or elevating hood type dust collectors equipped with bellows hoods that move up and down or expand and contract so as to cover the upper part of electric furnaces are used.

The former type of fixed hood dust collector has the disadvantage that it must suck in a large amount of indoor air along with smoke, and requires a large-capacity suction fan.

On the other hand, the latter elevating hood type dust collector can be used with a small-capacity suction fan compared to the fixed hood type dust collector mentioned above, and can reduce power consumption, but the input of raw material scraps is This is usually carried out using a crane, and the bellows hood gets in the way, so it has to be pulled up each time.Furthermore, when raw materials are added, impurities burn due to the residual heat in the furnace, causing the most amount of dust, and in this case, as mentioned above, the hood is removed. Dust collection cannot be carried out effectively because it is pulled up.

For this reason, a system has been proposed in which the fixed hood and the elevating hood are used together to collect dust from the entire building, and the two are switched between the two (for example,
Publication No. 96706).

[Problem that the invention seeks to solve]

However, even in the above system, the suction air volume, that is, the size of the suction fan, is such that a large-capacity fan is used that sucks in a large amount of indoor air as well as the smoke generated by the fixed hood.
Since the suction can be simply switched between suction using a fixed hood and suction using an elevating hood, a large amount of power is unavoidably consumed.

[Means for solving problems]

In view of this, the present invention combines a fixed hood and an elevating hood, uses each effectively depending on the melting period, and adjusts the suction air volume to perform effective dust collection with low electric power. The purpose is to

That is, the first invention relates to the method, which includes an elevating hood located above the melting furnace and whose lower end is extendable and retractable, and a fixed hood attached to the upper part of the building housing the melting furnace, and communicating with each hood. The suction duct that connects the suction duct is equipped with an opening/closing damper, and the suction fan that connects the suction duct is equipped with a rotation speed conversion means. The present invention is characterized in that the suction air volume ratio between the hood and the elevating hood is selected and the suction air volume of the suction fan is adjusted by the rotational speed conversion means in accordance with the operating order of the melting furnace.

A second invention relates to an apparatus for carrying out the above-mentioned method, including a telescopic elevating hood that is disposed above the melting furnace and is extendable and retractable to a set position, and a retractable elevating hood that surrounds the upper part of the elevating hood and is disposed on the ceiling of the building. A fixed hood, a suction duct that communicates with each hood and connects to a dust collector via a suction fan, an opening/closing damper placed at an appropriate position in each suction duct, and a rotation speed converter that adjusts the suction air volume of the suction fan. The system is equipped with a system that allows related operations to be performed depending on the operation, such as raising and lowering the elevating hood to a set position, selecting the suction air volume ratio of both hoods by adjusting the opening/closing angle of each opening/closing damper, and adjusting the suction air volume by the rotation speed conversion means. This is a characteristic feature.

[Effect]

Determine the position of the elevating hood according to the operational guidelines,
Operate the opening/closing damper to select the suction air volume ratio between the fixed hood and the elevating hood. Further, the rotation speed of the suction fan, that is, the suction air volume is selected by the rotation speed conversion means.
This allows efficient suction with the minimum power required for operation.

〔Example〕

The present invention will be explained below based on embodiments shown in the drawings.

The figure shows an example in which an electric furnace is used as a melting furnace, and a normal crane 4 that runs along a rail 3 provided in a building 2 is used as a means for feeding raw material scrap into the electric furnace 1. It will be done.

The dust collector 5 mainly includes a fixed hood 8 attached to the roof 6 of the building 2, and an elevating hood 10 that can be raised and lowered or retracted.
Reference numeral 10 is connected to branch ducts 11 and 12 and communicated through both branch ducts 14, and is further provided with a dust collector such as a bag filter for removing suctioned dust, although not shown.

The elevating hood 10 is composed of a fixed base hood 15 connected to the branch duct 12, a bellows hood 16 connected to the base hood, and an elevating device 17 for expanding and contracting the bellows hood. The lower end is approximately square or circular, and the bellows hood 16 is made of heat-resistant cloth and is formed in the shape of a truncated pyramid or cone with its lower part expanded, with 3 vertically spaced intervals on the outer periphery. frames 1
8, 19, 20, and weights 21, 22, 23 made of steel pipes or the like, and a weight cone 24 is also attached at the lowest end, respectively.

The lifting device 17 includes each of the frames 18, 19,
Lifting wires 25 are attached to the four corners of the building 2 or at equal intervals, and each wire 25 is wound around a guide pulley 27 provided on a fixed frame 26 attached to the building 2 with an appropriate mounting frame (not shown) and held in place. The bellows hood 16 is wound up by a winch device (not shown) provided at It is selected and maintained at an intermediate position B, indicated by a chain line, in which it is lifted up, and an upwardly pulled-up position C, indicated by a chain line, in which the crane 4 is allowed to pass. The intermediate position B is preferably as low as possible, where there is no risk of burnout due to radiant heat from the electric furnace or electrode rod during the melting operation.

Each of the branch ducts 11 and 12 is provided with an opening/closing damper 30, 31, respectively, and each opening/closing damper is connected to an appropriate opening/closing means (not shown).
As a result, the opening/closing damper 30 for the fixed hood 8 can be selectively opened and closed at a required intermediate angle, as shown in FIG.
40%, 60%, 100% position, and elevating hood 10
The opening/closing damper 31 has an opening degree as shown in FIG.
They are selectively opened and closed at 30%, 60%, and 100% positions.

The drive motor M of the suction fan 13 includes a rotation speed conversion means 3 using frequency conversion or mechanical speed change means.
2, and the suction air volume is also changed accordingly.

Next, electric furnace operation and dust collection procedures will be explained based on the flowchart shown in FIG. 4.

In the figure, the top, middle, and bottom of the lift hood indicate the upper pull-up position C, intermediate position B, and lowest lowered position A, respectively.
The numbers in the bottom row of the vertical hood damper and fixed hood damper columns are the damper opening positions shown in Figures 5 and 6, the top number is the suction air volume m ³ /min, and the air volume column is the total suction air volume of the fan. It is.

First, when the tapping of the electric furnace is completed and preparations for the next operation (including repairs) are being made, the elevating hood 10 is in the upwardly pulled position C, and the elevating hood damper 31 is fixed at the opening degree 2 position. The hood damper 30 has an opening degree of 4
The rotation speed of fan motor M is 500.p.
Let it be m. As a result, suction is mainly performed by the fixed hood 8, and the suction air volume of approximately 4500 m ³ /min by the fan 13 is approximately 3000 m 3 /min from the fixed hood 8.
m ³ /min Suction is drawn from the lifting hood 10 at a rate of about 1500 m ³ /min. Next, when charging raw materials for the first time, the opening/closing dampers 30 and 31 are set to an opening degree of 5,
5 (all fully open), and the suction air volume is 6400m ³ /min.
cause it to rise. This is because impurities burn due to residual heat in the furnace during charging, producing a large amount of smoke, and the lifting hood 10 is pulled upward for crane operation.

After charging the raw materials, the crane is moved to the outside and the furnace lid is closed. Then, the elevating hood 10 is lowered to the intermediate position B, and the elevating hood 10 is used as the main source for sucking smoke.
However, when the temperature is relatively low and the amount of smoke generated is small at the beginning of melting, the fan motor M is decelerated to save power, and the time is set by a timer.

Next, when adding raw materials, the temperature inside the furnace is high and the amount of smoke generated is large, and the lifting hood 10 has been pulled up to the upper lifting position C for convenience of crane operation, so the suction air volume by the suction fan 13 is at its maximum. After moving the crane 4 outward and closing the furnace lid, the elevating hood 10 is lowered to the intermediate position B, and the maximum suction air volume is maintained until the amount of smoke is reduced. The time is set by a timer.

Incidentally, when oxygen is blown, smoke containing a large amount of oxides is generated, but the time is relatively short, so the elevating hood 10 is lowered to the lowest position A to improve dust collection efficiency. This is how it was done.

During other operations, as shown in the diagram, the position of the elevating hood, the fixed hood, the suction ratio of the elevating hood, and the opening degree of the damper are appropriately selected depending on the amount of smoke emitted, the presence or absence of crane operation, etc. to minimize the amount of smoke as much as possible. It is as if it is suctioned by power.

〔Effect of the invention〕

As described above, according to the present invention, the elevating hood and the fixed hood are used together, and the suction ratio is adjusted by adjusting the expansion and contraction of the elevating hood and the opening/closing damper for both hoods according to the amount of smoke produced during the operation of the melting furnace. Since the number of rotations of the suction fan is adjusted at the same time, suction can be carried out effectively and economically.

[Brief explanation of drawings]

The drawings show embodiments of the present invention.
The figure is a vertical cross-sectional view with some parts of the melting factory including the electric furnace omitted, Figure 2 is a front view of the main parts of the elevating hood, and Figure 3
The figure is an explanatory diagram of the elevating device for the elevating hood, Fig. 4 is a flowchart showing the relationship between electric furnace operation and operation procedures of the dust collector, and Figs. 5 and 6 are dampers for fixed hoods and for elevating hoods, respectively. FIG. 6 is an explanatory diagram of the opening degree of the damper. 1... Electric furnace, 5... Dust collector, 8... Fixed hood, 10... Elevating hood, 11... Branch duct, 12... Branch duct, 13... Suction fan,
14...Main duct, 30...Opening/closing damper, 31...
... Opening/closing damper, 32... Rotation speed conversion means.

Claims (1)

[Scope of Claims] 1. An elevating hood located above the melting furnace and having a telescopic lower end, and a fixed hood attached to the upper part of the building housing the melting furnace, and a suction duct communicating with each hood. is equipped with an opening/closing damper,
In addition, the suction fan that connects the suction duct is equipped with a rotation speed conversion means, and the height relative to the melting furnace can be selected by adjusting the expansion and contraction of the elevating hood, and the suction air volume ratio between the fixed hood and the elevating hood can be selected by adjusting the opening/closing degree of the opening/closing damper. and a method for collecting dust in a melting furnace, characterized in that the suction air volume of the suction fan is adjusted by means of rotational speed converting means, selectively carried out according to the order of operation of the melting furnace. 2. A telescopic elevating hood placed above the melting furnace that can be expanded and retracted to a set position, a fixed hood surrounding the elevating hood and placed on the ceiling of the building, and communicating with each hood via a suction fan. It is equipped with a suction duct that connects to a dust collector, an opening/closing damper placed at the appropriate position of each suction duct, and a rotation speed conversion means that adjusts the suction air volume of the suction fan, and allows the elevating hood to be raised and lowered to a set position. A dust collection device for a melting furnace, characterized in that selection of the suction air volume ratio of both hoods by adjusting the opening/closing angle of each opening/closing damper and adjustment of the suction air volume by a rotation speed conversion means are operated in conjunction with each other according to the operation.