JPH07332878A - Exhaust gas treatment facility for steel making arc furnace - Google Patents

Abstract

PURPOSE:To provide an exhaust gas treatment facility which is capable of treating exhaust gas at less equipment and running costs before removing harmful components contained in an exhaust gas sucked up from an envelop substance installed around an arc furnace. CONSTITUTION:A rear flow side of a suction duct 5 is branched from an arc furnace envelop body 2 where one side is connected to a combustion tower 6 installed to the outside of an arc furnace on an arc furnace direct suction system or its upstream side by way of a damper while the other side is connected to a duct of a building suction system by way of a damper. Furthermore, an auxiliary combustion device 16 is installed to the combustion tower 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facility for treating exhaust gas generated during the operation of an electric arc furnace for steelmaking, especially an exhaust gas supplemented by an enclosure provided around the arc furnace.

[0002]

2. Description of the Related Art Conventionally, the exhaust gas treatment of a steelmaking arc furnace is
As shown in FIG. 2, the direct suction system 18 and the indirect suction system 1
It is carried out by two systems of 9.

The direct suction system 18 directly sucks the exhaust gas generated during the melting work of the arc furnace 3, and after the exhaust gas from the arc furnace 3 is taken out from the furnace lid 4, the combustion tower 6 and the cooling tower. 8 and the suction fan 10 and the like.

The indirect suction system 19 sucks in exhaust gas and dust generated when charging the raw material into the arc furnace 3 or during tapping, and exhaust gas leaked from the opening of the arc furnace 3 during the melting operation of the arc furnace. Then, after being taken out from the arc furnace enclosure 2 and the upper part 11 of the building, it is processed by equipment including a main suction fan 13, a bag filter 14, and the like.

By the way, oil, paint, rubber, chemically synthesized products, etc. are mixed in the scrap used as the raw material of the arc furnace for steelmaking, and white smoke, a bad odor, etc. are generated during the melting work, when the scrap has residual heat, etc. Exhaust gas containing harmful substances is generated, which is an environmental problem.

Most of the exhaust gas containing these harmful components is captured by the direct suction system, and as a method for removing these harmful components, for example, a direct suction system from an arc furnace or a device dedicated to residual heat of scrap is used in a combustion device. The exhaust gas treatment technology of the arc furnace, in which a holding chamber for the combustion exhaust gas is provided on the downstream side to thermally decompose harmful components, and then the gas is cooled rapidly by a gas cooler and dust is removed by a bag filter, is applied. Japanese Patent Application No. 4-264719
It has been filed as an issue.

On the other hand, regarding the exhaust gas generated when the furnace lid of the arc furnace is opened and the raw material is introduced into the arc furnace, or the exhaust gas leaked from the opening portion of the arc furnace during the melting work,
It cannot be captured by the direct suction system, but most of it is captured by the arc furnace enclosure and processed by the indirect suction system.

[0008]

However, the above-mentioned harmful components are contained in the exhaust gas sucked from the arc furnace enclosure at the time of charging the raw material and the exhaust gas leaked from the arc furnace at the initial stage of melting, and the With the increase in the amount of scrap containing a large amount of slag, the influence of these harmful components on the environment is increasing.

Therefore, it is becoming necessary to take measures to remove harmful components from the exhaust gas from the arc furnace enclosure which has been treated by the conventional indirect suction system. As a measure against these, when applying the above-mentioned technologies such as thermal decomposition in the direct suction system and rapid cooling method to the indirect suction system,
The amount of processing becomes enormous, and the running cost also becomes enormous.
Further, even when the exhaust gas treatment system from the arc furnace enclosure is independently installed, there is a problem that the equipment cost increases.

In view of the above situation, according to the present invention, the exhaust gas generated when the furnace lid of the arc furnace is opened and the raw material is charged into the arc furnace, or the exhaust gas leaked from the opening portion of the arc furnace during the melting operation. It is an object of the present invention to provide an exhaust gas treatment facility capable of treating with less equipment cost and running cost in removing harmful components contained in the above.

[0011]

In an exhaust gas treatment facility for a steelmaking arc furnace having an enclosure provided around the arc furnace, a wake side of a suction duct from the enclosure of the arc furnace is branched and one of them is directly connected to the arc furnace. Connected via a damper to the combustion tower provided on the discharge side of the arc furnace on the suction system or its upstream side, and connected the other to the duct of the building suction system via a damper, and further provided an auxiliary combustion device in the combustion tower. It is characterized by that.

[0012]

[Operation] Exhaust gas generated when the furnace lid of the arc furnace is opened and the raw material is introduced into the arc furnace, or exhaust gas leaking from the opening portion of the arc furnace during the melting work is contained inside the enclosure provided around the arc furnace. Suction processing is performed within an arbitrary time in the accumulated state. In this case, part or all of the exhaust gas sucked from the arc furnace enclosure can be directly increased with the combustion tower of the suction system or the high temperature exhaust gas on the upstream side thereof to easily raise the exhaust gas temperature from the enclosure. Moreover, since the unburned CO gas contained in the exhaust gas of the suction system can be directly burned by utilizing the oxygen contained in the exhaust gas from the enclosure, the harmful components in the exhaust gas can be thermally decomposed. It is possible to raise the temperature to a possible temperature.

Generally, in order to completely burn the unburned CO gas contained in the exhaust gas of the direct suction system, outside air is introduced from a duct and a part in the middle of the direct suction system, but instead of this, from the above-mentioned arc furnace enclosure. Since it is possible to use the exhaust gas of the above, it is not necessary to increase the amount of dust collection air when viewed from the whole dust collection equipment.

On the other hand, the exhaust gas of the direct suction system from the arc furnace has different temperature and amount depending on the melting time.
The temperature control of the exhaust gas after the merging can be performed by adjusting the damper amount of the exhaust gas from the enclosure.

Further, even when the exhaust gas temperature of the direct suction system is low or the exhaust gas amount is small, the auxiliary combustion device provided in the combustion tower is used in combination to sufficiently raise the harmful components in the exhaust gas. Temperature and temperature control are possible.

The exhaust gas burned in the combustion tower has its temperature lowered in the process of passing through the exhaust gas duct on the downstream side, but if it is kept at a temperature near 300 ° C. for a long time, the harmful substances are regenerated, A cooling tower is provided to allow this temperature range to pass in a short time to prevent regeneration of the harmful substances.

In this manner, most of the exhaust gas leaked to the outside of the arc furnace is detoxified, and then the dust and the like are removed by the dust collector and discharged to the atmosphere. Also, during the operation of the arc furnace, at the time when the generation of harmful components is small, in the exhaust gas system from the arc furnace enclosure, the confluence damper with the direct suction system is closed and the confluence damper with the building system is opened, which is the same as before. Indirect suction system can be used for exhaust gas treatment.

[0018]

EXAMPLE FIG. 1 is an equipment configuration diagram according to the present invention, showing an example of a case where a direct suction system and an indirect suction system are merged on the downstream side of exhaust gas and exhaust gas treatment is performed by one bag filter. Is.

An arc furnace enclosure 2 is provided around the arc furnace 3, and the outside is surrounded by a building 1. The exhaust gas of the direct suction system sucked from the arc furnace 3 is taken out from the furnace lid 4 and then introduced into the combustion tower 6 provided on the downstream side through the duct 5. Of course, bypass line 15
Can also be directly connected to the combustion tower 6.

Since the exhaust gas of the direct suction system from the arc furnace 3 contains unburned CO gas, it reacts with the oxygen in the exhaust gas from the arc furnace enclosure 2 to generate the gas in the combustion tower and its subsequent flow. It burns in the duct 7.

When the exhaust gas temperature of the direct suction system is low, or when the exhaust gas amount is small, the amount of the exhaust gas introduced from the arc furnace enclosure 2 can be reduced by the damper of the bypass line, and the combustion tower 6 can be further reduced. The auxiliary combustion device 16 provided can control the exhaust gas temperature in the combustion tower 6. In this case, the fuel is kerosene, LNG
And so on.

The exhaust gas heated to a predetermined temperature or higher in the combustion tower 6 passes through the duct 7 on the downstream side and drops in the cooling tower 8 in a temperature range near 300 ° C. within a short time to regenerate harmful components. Prevent. The cooled exhaust gas is sucked by the suction fan 10 provided on the downstream side, and merges with the indirect suction system through the duct 9.

Exhaust gas of the indirect suction system sucked from the upper part 11 of the building passes through the duct 12 and the main suction fan 13
Are sucked in and dust is removed by the bag filter 14.

When the exhaust gas generated from the arc furnace contains a small amount of harmful components, for example, at the end of melting, it is not necessary to heat the exhaust gas from the arc furnace enclosure 2, and in such a case, the arc furnace By setting the damper of the bypass line 15 of the direct suction system on the downstream side of the enclosure 2 to "close" and the damper of the bypass line 17 of the indirect suction system to "open", it is possible to perform processing by the indirect suction system as in the conventional case. .

[0025]

As described above, in the exhaust gas treatment equipment of the arc furnace according to the present invention, the exhaust gas containing the harmful components trapped by the arc furnace enclosure provided around the arc furnace cannot be directly sucked by the suction system. The temperature of the exhaust gas from the arc furnace enclosure can be easily increased by directly joining the exhaust gas from the arc furnace enclosure, and the oxygen contained in the exhaust gas from the arc furnace enclosure is directly burned in the exhaust gas of the direct suction system. CO
Since it can be used as gas combustion air, it is possible to easily raise the temperature to a temperature at which harmful components are thermally decomposed.

This is the unburned C in the exhaust gas of the direct suction system.
For complete combustion of O gas, exhaust gas from the arc furnace enclosure can be used as a substitute for what was conventionally done by introducing air from the duct connection part or outside air, and the dust collection facility as a whole can process air volume. Does not increase. Therefore, it is possible to minimize the increase in equipment cost for exhaust gas treatment.

When the temperature of the exhaust gas from the direct suction system is low or the amount of the exhaust gas is small, the amount of the exhaust gas introduced from the arc furnace enclosure can be reduced. By using the auxiliary combustion device provided in the above, the exhaust gas temperature can be easily controlled and the fuel consumption can be reduced.

On the other hand, when there are few harmful components in the exhaust gas from the arc furnace at the end of melting, etc., the exhaust gas from the arc furnace enclosure can be joined to the indirect suction system to be treated in the same manner as in the conventional case. Is.

As described above, in the exhaust gas treatment equipment of the arc furnace according to the present invention, since the treatment equipment of the conventional direct suction system can be utilized to the maximum extent, when directly treating the exhaust gas of the indirect suction system or the arc furnace enclosure. As compared with the case where the exhaust gas from the body is treated alone, the harmful components contained in the exhaust gas from the arc furnace enclosure can be removed with much lower equipment cost and running cost.

[Brief description of drawings]

FIG. 1 is an equipment configuration diagram according to the present invention.

FIG. 2 is an example diagram of a facility configuration in a conventional arc furnace.

[Explanation of symbols]

 1 Building 2 Arc Furnace Enclosure 3 Arc Furnace 4 Furnace Lid 5 Duct 6 Combustion Tower 7 Duct 8 Cooling Tower 9 Duct 10 Suction Fan 11 Top of Building 12 Duct 13 Main Suction Fan 14 Bag Filter 15 Bypass Line 16 Auxiliary Combustor 17 Bypass Line 18 Direct suction system 19 Indirect suction system

Claims (1)

[Claims] 1. In an exhaust gas treatment facility for a steelmaking arc furnace having an enclosure around the arc furnace, a wake side of a suction duct from the arc furnace enclosure is branched, and one of them is on a direct suction system of the arc furnace. An exhaust gas treatment facility for a steelmaking arc furnace, which is connected to a combustion tower provided on the outlet side of the arc furnace or an upstream side thereof via a damper, and is further provided with an auxiliary combustion device on the combustion tower.