JPH0842980A - Method of treating exhaust gas from electric furnace or scrap preheating device for electric furnace - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention is directed to an electric furnace during melting / heating of a material, a scrap preheating device for preheating the material, or white smoke contained in exhaust gas generated from the electric furnace, a foul odor, or the like. The aim is to provide a process that can safely remove harmful components of. [Structure] A cooling device 4 for cooling exhaust gas in a short time to a low temperature region of 50 ° C. or lower where harmful components are solidified, and a dust collecting filter 7 made of a porous resin material 11 for collecting the solidified harmful components. By configuring the processing equipment with
It is possible to reduce harmful components such as malodor in exhaust gas to about 1/500 to 1/1000 of the initial content level without making the filter unusable by clogging with dew condensation water or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an exhaust gas generated during melting, refining, and pyroheating from an electric furnace for melting or refining a metal material, or for preheating a metal material in an electric furnace or in a device for exclusive use of scrap preheating. The present invention relates to a method for removing harmful components contained in exhaust gas generated in the air.

[0002]

2. Description of the Related Art When a metal material is melted and heated in an electric furnace, or preheated in an electric furnace or in a scrap preheating dedicated device, harmful components such as white smoke or a foul odor are generated, which causes a problem. Has become. This white smoke is a mist formed by evaporation of oil adhering to the metal material, which may cause clogging of the filter cloth in the dust collector or a fire. In addition, harmful substances such as foul odors not only worsen the working environment of workers who work there, but also seriously affect the living environment of local residents.

Various methods have been proposed as methods for removing white smoke contained in these exhaust gases or harmful components such as malodors. For example, according to JP-A-2-136693, white smoke discharged from a scrap preheating device or a gas containing a harmful component such as a foul odor is directly cooled to 80 ° C. by a water-washing type spray cooling tower. It is said that it is possible to remove harmful components such as white smoke or foul odor contained in the gas without burning the filter cloth.

[0004]

With this method, however, the amount of water vapor in the exhaust gas entering the dust collector becomes extremely large because the exhaust gas is cooled directly in the water washing type spray cooling tower, and the filter cloth It becomes unavoidable that dew condensation water adheres to the surface. When water adheres to the surface of the filter cloth, the water permeates inside and becomes difficult to remove, and when water is absorbed by the dust collected on the surface of the filter cloth, the dust is hardened and the dust is removed from the surface of the filter cloth. It is impossible to wipe it off, that is, it becomes completely clogged. When the filter is clogged in this way, the pressure loss of the gas passing through the filter increases, and as a result, the amount of dust collecting gas decreases and the dust collecting efficiency deteriorates. Therefore, the filter cloth, which is normally replaced in 3 to 5 years, is forced to be replaced in only a few months.

Further, a large amount of oil is contained, such as exhaust gas generated when melting and raising the temperature of a metal material in an electric furnace, or when preheating in an electric furnace or in a scrap preheating dedicated device. In this case, when the cooling temperature is up to 80 ° C., the temperature is insufficient for removing harmful components such as a bad odor.
Therefore, in the present invention, an electric furnace during melting / heating of the material,
Alternatively, it is possible to ensure that white smoke contained in the exhaust gas generated from the scrap preheating device or the electric furnace during preheating of the material, or harmful components such as a bad odor, without making the filter cloth in the dust collector unusable by dew condensation water. It is intended to provide a method for treating exhaust gas that can be removed.

[0006]

In order to solve the above problems, a method for treating exhaust gas according to the present invention is a method for treating exhaust gas from an electric furnace or a scrap preheating device for an electric furnace, which cools exhaust gas. An electric furnace characterized in that the exhaust gas is cooled to a low temperature region of 50 ° C. or lower by an apparatus, and then the exhaust gas is passed through a dust collecting filter made of a porous resin material to collect harmful components. Alternatively, it is a method of treating exhaust gas from the scrap preheating device for an electric furnace.

A method for treating exhaust gas from an electric furnace or a scrap preheating device for an electric furnace, wherein the exhaust gas is cooled to a low temperature of 50 ° C. or lower by a cooling device for cooling the exhaust gas, and then, after the cooling. From scraps for electric furnaces or electric furnaces characterized by collecting harmful components by mixing an adsorbent such as slaked lime in the exhaust gas, and further allowing the exhaust gas to pass through a dust collection filter made of a porous resin material. The exhaust gas treatment method of

[0008]

A large amount of oil is contained in the exhaust gas generated from the electric furnace during melting / heating of the material, or the scrap preheating device or the electric furnace during preheating of the material. The inventors have confirmed that in the coexistence state with such an oil component, the melting point of harmful components such as malodor is considerably lower than that when it is present alone, and is about 50 ° C.

Therefore, the above exhaust gas is cooled by the cooling device.
By cooling to a low temperature range of ℃ or less in a short time, harmful components such as malodor can be solidified. As a result, almost all of the harmful components in the exhaust gas are collected by the dust collector together with the dust contained in the exhaust gas and are not released to the atmosphere.

Further, the dust collecting filter is composed of a continuous porous resin material having a surface coated with a porous resin material containing fluorine or silicon. The filter cloth, which is a normal woven fabric, has pores of about 80 μm, whereas the pores of the filter surface are about 4 μm, so that, for example, water condensed on the filter surface does not penetrate into the filter. Therefore, since it stays on the surface as it is and flows down downward together with the collected dust, the filter is not disabled due to clogging or the like. Therefore,
The life of the filter does not remain the same as the conventional 3 to 5 months, and the life is further extended from the conventional one.

Furthermore, slaked lime or the like is blown into the exhaust gas from the adsorbent supply device to adsorb harmful components such as a bad odor, and then the slaked lime or the like blown together with the dust in the exhaust gas is captured by the dust collecting filter. . By this process, the collection efficiency of harmful components such as malodor is further improved.
In addition, the dust captured by the dust collection filter, or
Powdered slaked lime or the like mixed with dust is shaped into particles, and returned to the electric furnace to be melted, so that processing such as exhaust is unnecessary, and secondary pollution can be prevented.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a device configuration diagram of a basic process according to the present invention, showing an example having an adsorbent supply device. This shows a process of decomposing and removing harmful components such as white smoke or foul odor contained in exhaust gas generated during preheating, melting, or temperature rise of a metal material in an electric furnace.

Exhaust gas generated from the electric furnace 1 is introduced into the combustion tower 3 through the duct 2. Here, CO gas contained in the exhaust gas is burned, and at the same time, part of white smoke, malodor, etc. contained in the exhaust gas is thermally decomposed. The exhaust gas leaving the combustion tower 3 is introduced into the cooling device 4. Here, the exhaust gas is directly cooled to 50 ° C. or lower by spray particles of water sprayed from the spray nozzle 5, for example. The malodor and the like once decomposed by combustion heating are regenerated when kept in an atmosphere of 300 ° C. for a certain period of time, and therefore, the water is directly cooled by water to rapidly cool it in a short time.

Here, an example of cooling by water spray in one cooling device has been described as the cooling method.
Of course, the number is not limited to one, and a plurality of cooling devices may be used, and in addition to the water spray, cooling devices such as a water cooling duct, an air cooling duct, and a heat exchange device may be used. Adsorbent supply device 6
By blowing powder such as slaked lime into the exhaust gas, the residual harmful components such as bad odor are adsorbed. Here, as the powder blown into the exhaust gas, in addition to slaked lime, char, coal ash,
Activated carbon, urea, etc. may be used. This blown slaked lime, etc.
The level of harmful components such as a foul odor in the exhaust gas that is captured by the dust collection filter 7 together with the dust in the exhaust gas and is diffused into the atmosphere by the stack 8 is 1/500 to 1/10 of the initial level.
It is reduced to about 00. Dust or slaked lime containing dust captured by the dust collecting filter 7 is sent to the pelletizer 9, is granulated, and is thrown into the electric furnace 1 again to be melted. Therefore, disposal such as disposal becomes unnecessary and secondary pollution can be prevented.

FIG. 2 shows a sectional view of the dust collecting filter according to the present invention. The filter has a structure in which the surface of a base material 10 of a continuous porous resin material having a gap of about 40 to 60 μm is covered with a porous resin material 11 containing fluorine or silicon having a gap of about 4 μm. The gas penetrates into the filter from the direction A covered with the porous resin material, and the internal space 1
Pass 2 and go out of the filter. Dust and moisture are
Before the gas enters the filter from the A direction, it is captured on the surface of the porous resin material 11.

[0016]

According to the process of the present invention, the amount of harmful components such as malodor contained in exhaust gas generated during preheating, melting, or temperature rise of a metal material in an electric furnace can be reduced to 1
It is possible to reduce to / 500 to 1/1000. Moreover, the life of the filter is not only the same as that of the conventional filter, but also the life of the filter is longer than that of the conventional filter. Therefore, the running cost of the filter can be significantly reduced. In this way, almost all of the harmful components in the exhaust gas can be collected by the dust collector without being released into the atmosphere, and the dust collected by this dust collector and the mixture with the dust can be stored in the electric furnace. By returning and re-dissolving, there is no need to treat waste, and secondary pollution can be prevented, which is an excellent effect.

[Brief description of drawings]

FIG. 1 shows preheating of a metal material in an electric furnace according to the present invention,
FIG. 1 shows an apparatus configuration diagram of a basic process for decomposing and removing harmful components such as malodor contained in exhaust gas generated during melting or temperature rise.

FIG. 2 shows a cross-sectional view of a dust collecting filter according to the present invention.

[Explanation of symbols]

 1 Electric Furnace 2 Duct 3 Combustion Tower 4 Cooling Device 5 Spray Nozzle 6 Adsorbent Supply Device 7 Dust Collection Filter 8 Stack 9 Pelletizer 10 Base Material 11 Fluorine- or Silicon-Containing Porous Resin Material 12 Internal Space

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C21C 5/52

Claims (2)

[Claims] 1. A method for treating exhaust gas from an electric furnace or a scrap preheating device for an electric furnace, wherein the exhaust gas is cooled to a low temperature region of 50 ° C. or lower by a cooling device for cooling the exhaust gas, and then the exhaust gas is porous. A method for treating exhaust gas from an electric furnace or a scrap preheating device for an electric furnace, comprising collecting harmful components by passing the exhaust gas through a dust collecting filter made of a high quality resin material. 2. A method for treating exhaust gas from an electric furnace or a scrap preheating device for an electric furnace, wherein the exhaust gas is cooled to a low temperature of 50 ° C. or lower by a cooling device for cooling the exhaust gas, and then the cooled exhaust gas is cooled. From scraps for electric furnaces or electric furnaces characterized by collecting harmful components by mixing an adsorbent such as slaked lime in the exhaust gas, and further allowing the exhaust gas to pass through a dust collection filter made of a porous resin material. Exhaust gas treatment method.