JPS631366B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a melting method for an arc furnace, and in particular,
The present invention relates to a melting method that provides high thermal efficiency.

A method of obtaining high thermal efficiency is known by using the heat contained in the exhaust gas discharged from the arc furnace to preheat the material to be melted, such as scrap, which is charged into the arc furnace to the highest possible temperature. It is being However, in the past, preheating of the material to be melted was generally carried out outside the furnace body of the arc furnace, and in such cases, if the material to be melted contained low-grade scrap such as dull powder, the preheating There was a problem in that the oil contained in the low-grade scrap was burned and the material to be melted was melted outside the arc furnace.

On the other hand, if the preheating temperature of the material to be melted is suppressed in order to avoid such inconveniences, the incomplete combustion of the oil contained in the low-grade scrap will generate white smoke with a foul odor, which will worsen the facility environment and , high thermal efficiency cannot be obtained sufficiently.

The present invention has been made against the background of the above circumstances, and its purpose is to melt materials to be melted at high temperatures without deteriorating the environment, even if the materials to be melted include low-grade scrap. Preheat,
An object of the present invention is to provide an arc furnace melting method that provides high thermal efficiency.

In order to achieve such an object, the present invention provides an arc furnace melting method for melting a material to be melted by alternately using a pair of arc furnace bodies, comprising: (2) a step of blowing carbon and oxygen-containing gas, burning the carbon to generate CO gas, and guiding the CO gas into the other furnace; (2) blowing the oxygen-containing gas to C.O.
The present invention is characterized in that it further includes the step of combusting the gas to preheat the material to be melted that has been previously charged into the other furnace body for melting in the other furnace body.

In this way, the material to be melted before melting is preheated in the other furnace body, so the preheating temperature of the material to be melted can be increased, and the CO gas generated in one furnace body is transferred to the other furnace body. Since the material to be melted is preheated by combustion in one of the furnace bodies, the heat generated in one of the furnace bodies is used extremely effectively for preheating, resulting in high thermal efficiency.
Even if the material to be melted contains low-grade scrap, the preheating temperature is high, so the oil contained in the low-grade scrap is completely combusted, eliminating the deterioration of the facility environment.

Also, since carbon is burned to generate CO gas in one of the furnace bodies during melting,
The heat of combustion is used for melting, resulting in significant savings in expensive electricity.

Next, an example of the method of the present invention will be explained in detail based on the drawings.

In FIGS. 1 and 2, a pair of bases 10
A pair of symmetrically arranged arc furnace bodies 12a, 12b are tiltably disposed on the arcs a, 10b. That is, furnace stands 14a, 14b with engaging teeth formed on a straight line are fixed on the bases 10a, 10b, and furnace legs 15a, 15b with engaging teeth formed on an arc are fixed on the bases 10a, 10b. Matching teeth and hearth stand 14a, 1
In the state where the engagement teeth of 4b are engaged, the furnace stands 14a, 1
4b, respectively. Furnace legs 15a, 15
One end of b is an extendable tilting drive device 16a, 1
6b, respectively, and the furnace legs 1
5a and 15b, a plurality of rollers 18 are provided on one circumference.
are arranged, and the furnace bodies 12a and 12b are connected to the rollers 1.
8 on the furnace legs 15a and 15b, respectively. Therefore, the furnace bodies 12a and 12b are tilted by the tilting drive devices 16a and 16b, respectively, and the molten steel inside each is transferred to the tapping port 20.
The steel is tapped into the ladle 22 through the holes 20a and 20b, and is rotated around a vertical central axis during melting. Furthermore, the furnace body 12
carbon injection nozzles 24a and 12b, respectively.
24b and oxygen injection nozzles 26a, 26b.

Melting furnace lid 28, electrode rod 30, and preheating furnace lid 3
2 is applied alternately to the furnace bodies 12a and 12b, and is applied to the furnace bodies 12a and 12b alternately.
In each case, melting and preheating are performed alternately. That is, the furnace bodies 12a and 1
A pair of rails 34 are laid on both sides of 2b, and a gantry 36 is mounted on the rails 34.
The vehicle is arranged so as to run across 2a and 12b. The gantry 36 has a melting furnace lid 28
is suspended so that it can be raised and lowered, and the electrode rod 3
0 lifting device 38 is provided. Lifting device 3
8 is a gantry 36 as shown in FIG.
A column 40 that can be raised and lowered is provided on one leg of the
and an arm 42 projecting horizontally from the upper end of the support 40, and the electrode rod 30 fixed to the tip of the arm 42 can be moved up and down.
The electrode rods 30 are each connected to a power supply device 46 through a water-cooled bus tube 44, so that power from the power supply device 46 is supplied to the electrode rods 30.

On the other hand, as shown in FIG. 2, a vertical pipe 48 that also serves as a part of the exhaust path is installed at an intermediate position between the furnace bodies 12a and 12b. A rotating duct 50 connected to the preheating furnace lid 32 is connected to the vertical pipe 48 so as to be rotatable about the axis thereof. The preheating furnace lid 32 is raised and lowered by a hanging device (not shown), rotated about a vertical tube 48, and fitted into an opening of the furnace body 12a or 12b. The lower end of the vertical pipe 48 is connected by an exhaust duct 52 to a clamshell type bucket 54 serving as a common preheating chamber for accommodating materials to be melted for additional loading, and the bucket 54 is connected to an exhaust fan (not shown). The air is sucked and exhausted through an exhaust duct 56.

The furnace bodies 12a and 12b are interconnected by a connecting duct 58 so that CO (carbon monoxide) gas generated during melting of one is sent to the other. Note that the connection duct 58 and the exhaust duct 52 are connected by a bypass duct 62 equipped with an opening/closing damper 60, and a CO2 for preheating is connected.
The air volume of gas etc. can be adjusted.

Next, a method of melting the arc furnace configured as described above will be explained.

For example, when the electrode rod 30 is inserted into the furnace body 12a and the material to be melted is being melted by being supplied with power from the power supply device 46, there is already a state in the other furnace body 12b that is not shown in the figure. The material to be melted is charged from a bucket that does not have a casing, and the material to be melted for additional loading is charged into the bucket 54. In such a state, in the furnace body 12a, the carbon mixed in advance with the material to be melted and the carbon injected from the carbon injection nozzle 24a are mixed with oxygen, air, etc. injected from the oxygen injection nozzle 26a. is combusted by oxygen in the oxygen-containing gas to generate CO gas. This CO gas is sent into the other furnace body 12b through the connecting duct 58, where it is supplied with oxygen-containing gas and combusted. Therefore, the material to be melted in the furnace body 12b is
It is preheated to extremely high temperatures by burning CO gas. That is, since the material to be melted is preheated while being charged into the furnace body 12b, the material to be melted can be preheated to a high temperature without worrying about melting, and the temperature inside the furnace body 12a during melting can be preheated. Since the heat is effectively used for preheating the inside of the furnace body 12b, high thermal efficiency can be obtained. Moreover, by preheating the material to be melted at a high temperature,
The oil content of low-grade scrap contained in the material to be melted is completely combusted, and the deterioration of the equipment environment is completely eliminated.

The exhaust gas discharged from the furnace body 12b is
Rotating duct 50, vertical pipe 48, and exhaust duct 5
2 is supplied into the bucket 54, and the material to be melted for reloading, which has been previously accommodated in the bucket 54, is preheated.

When the melting inside the furnace body 12a is completed, the electrode rod 30
Then, the melting furnace lid 28 is removed from the furnace body 12a, and the bucket 54 is moved onto the furnace body 12a, so that the material to be melted in the bucket 54 is transferred to the furnace body 1.
Additional charges are made from the upper opening of 2a. Then, the electrode rod 30 and the melting furnace cover 28 are returned to the furnace body 12a, and the additional material to be melted is melted in the furnace body 12a. Even during this melting, the carbon injection nozzle 24 and the oxygen injection nozzle 2
Carbon and oxygen-containing gas is injected from 6 to produce CO
Gas is generated, and the material to be melted in the furnace body 12b is efficiently preheated in the same manner as described above, and the material to be melted for reloading newly accommodated in the bucket 54 is preheated.

When melting in the furnace body 12a is completed, the furnace body 12a is tilted by the operation of the tilting drive device 16a, and molten steel is tapped into the ladle 22. When the furnace body 12a is returned, the material to be melted is newly charged into the furnace body 12a, and the melting furnace lid 28 and electrode rod 30 on the furnace body 12a are attached to the furnace body 12b, and conversely, the furnace body 12a is loaded with the material to be melted. The preheating furnace lid 32 on the body 12b is rotated together with the rotating duct 50 and mounted on the furnace body 12a. And from then on,
The same operations as described above are performed, and melting is performed in the furnace body 12b, and at the same time, preheating of the material to be melted is performed in the furnace body 12a.

Thus, according to this embodiment, the CO gas generated in one furnace body 12a during melting is guided into the other furnace body 12b into which the material to be melted is charged, where the CO gas is Since the material to be melted is preheated to a high temperature by the heat of combustion, high thermal efficiency can be obtained. According to experiments conducted by the present inventors, it was possible to recover 50% of the heat that was conventionally released along with the exhaust gas from the furnace body during melting.

In addition, even if the material to be melted is low-grade scrap containing a large amount of oil, the oil is completely combusted with the combustion of the CO gas, preventing foul odors, white smoke, etc., and maintaining a favorable working environment. At the same time, since carbon is burnt in one of the furnace bodies 12a during melting to generate CO gas, expensive electric power can be significantly saved by the heat of combustion.

Furthermore, according to this embodiment, the material to be melted for additional loading is preheated by the exhaust gas of the CO gas used to preheat the material to be melted in the other furnace body 12b.
There is an advantage that the heat contained in the exhaust gas is further recovered, resulting in higher thermal efficiency.

It should be noted that the above-mentioned method is merely an example of the method of the present invention, and it goes without saying that the present invention can be modified in various ways without departing from its spirit.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of an arc furnace to which an example of the method of the present invention is applied. FIG. 2 is a plan view of FIG. 1. FIG. 3 is a partially cut away side view of FIG. 1 showing different cycles. 12a, 12b: Furnace body, 54: Bucket (preheating chamber).

Claims (1)

[Claims] 1. An arc furnace melting method for melting a material to be melted by alternately using a pair of arc furnace bodies, the method comprising blowing carbon and oxygen-containing gas into one of the furnace bodies during melting. a step of combusting the carbon to generate CO gas and guiding the CO gas into the other furnace body; further combusting the CO gas by blowing oxygen-containing gas into the other furnace; An arc furnace melting method comprising the step of preheating a material to be melted that has been previously charged into the furnace body for melting within the furnace body.