JPH06185864A - Exhaust gas treating equipment - Google Patents

Abstract

PURPOSE:To provide a dry gas treating equipment for reductive exhaust gas containing zinc vapor. CONSTITUTION:The exhaust gas treating equipment is provided with a condenser, a dry dust collecting device, a control damper, an emergency shut-off valve and a porous plate arranged in the order named and the control damper is mounted in such a manner as to keep the valve body horizontal when it is fully closed. This arrangement can obviate the need for the waste water treatment accompanied by treatment of the carbon monoxide containing exhaust gas emitted from the condenser.

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 after recovering crude zinc from the exhaust gas containing zinc vapor obtained by reduction and volatilization in zinc smelting.

[0002]

2. Description of the Related Art Zinc concentrate or the like is roasted into one of the dry smelters of zinc to form an oxide, which is then heat-reduced with other zinc oxide-containing raw materials to obtain an exhaust gas containing zinc vapor. There is a method of absorbing zinc in lead by using a lead condenser or the like, and separating and recovering zinc from lead by controlling the temperature.
An example of a smelting method based on such a principle is called an ISP method, and the ISP method is the mainstream of the dry method because it can simultaneously treat lead and zinc.

In recent years, demands for lowering smelting costs have become strict,
Although various novel methods have been proposed to satisfy this, any dry method can be used to reduce zinc oxide and volatilize zinc, and then use a condenser to coagulate and recover zinc vapor. It is also followed in the law.

By the way, the exhaust gas generated when the zinc oxide is reduced is a strongly reducing gas containing zinc vapor, carbon monoxide, carbon dioxide gas, dust and the like. Naturally, the exhaust gas after zinc recovery is also generated. It is a strongly reducing gas containing carbon monoxide. Normally, the concentration of carbon monoxide in this exhaust gas is 5
In some cases, the exhaust gas may reach about 0%, and after the dust is removed, it is introduced into the combustion chamber and burned, carbon monoxide in the exhaust gas is used as a fuel, and is converted into carbon dioxide before being released into the atmosphere.

When oxygen is mixed in the exhaust gas containing a large amount of carbon monoxide, gas explosion may occur. Normally, in such a system, the control damper is operated to maintain a positive pressure in the apparatus. However, such exhaust gas contains a considerable amount of dust as described above,
If the dust accumulates in the system, the control damper will malfunction. In order to avoid this situation, the exhaust gas discharged from the condenser is first treated by a wet dust removing facility such as a spray tower to remove dust. As a result, as a matter of course, a large amount of waste water is generated compared with the wet dust removal equipment, which imposes a heavy load on the waste water treatment equipment. It should be noted that dust removal by the dry method is not usually adopted because it cannot prevent flashback of carbon monoxide to the previous step.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a gas treatment facility that does not require a load on the wastewater treatment facility.

[0007]

The gas treatment equipment of the present invention which solves the above-mentioned problems removes zinc in exhaust gas discharged from a reduction furnace, removes dust and supplies the carbon monoxide combustion furnace with the exhaust gas. In a gas treatment facility used to remove dust in the step of burning carbon monoxide in the inside, a dry dust remover provided after the condenser, a control damper provided after the dry dust remover, and after the control damper An emergency shutoff valve provided and a perforated plate provided after the emergency shutoff valve. The valve body of the control damper is mounted so as to be horizontal when fully closed, preferably as an emergency shutoff valve. When using a butterfly valve, when the butterfly valve is installed so that its valve body is horizontal when fully closed, and a sluice valve is used as an emergency shutoff valve Are those valve is to attach so as to be perpendicular when the the partition valve was fully closed.

[0008]

The feature of the present invention lies in the arrangement and combination of the respective devices, and the respective devices themselves are not specially novel. For example, as a dry dust remover, something that generates an electric arc such as an electrostatic precipitator cannot be used, but other dust chambers, cyclones, bag filters, etc. can be used, and control dampers and emergency shutoff valves are also commercially available. There is no problem with the butterfly valve and sluice valve.

In the present invention, the provision of the dry dust remover after the condenser is intended to prevent accumulation of dust on the control damper and prevent malfunction of the control damper due to dust. Therefore, when viewed from the flow of exhaust gas, it is necessary to provide the dry dust remover upstream of the control damper. The capability of the dry dust remover used is that at least sedimentation and
It suffices to remove the deposits, and it is not necessary to completely remove even the fines that fly out of the system together with the exhaust gas. If even such fine dust is to be completely removed, the dry dust remover will be extremely large-scaled, which not only significantly increases the processing cost, but also increases the risk of gas leakage and air inclusion. May cause carbon dioxide explosion. The dust removed by the dry dust remover is discharged outside the system by a double damper method or the like.

As described above, the present invention does not necessarily remove even fine dust scattered with the exhaust gas by the dry dust remover, so the fine dust floats in the exhaust gas and flows downstream. Therefore, it is necessary to prevent this floating dust from accumulating on the control damper.For this reason, the pipe part where the control damper should be installed should be a vertical pipe part, and the valve body should be horizontal when the control damper is fully closed. Install.

In the present invention, an emergency shutoff valve is provided downstream of the control damper in order to prevent flashback from the carbon monoxide combustion furnace when the operation is stopped. To do. When using a butterfly valve as this emergency shut-off valve, it is preferable to attach a butterfly valve to the vertical pipe as well as the control damper so that the valve body becomes horizontal when fully closed. It is preferable that the valve body is attached to the pipe so that the valve body becomes vertical when fully closed.

A perforated plate is provided downstream of the emergency shutoff valve, and it is preferable that this is closer to the inlet of the carbon monoxide combustion furnace. The reason for this is that this perforated plate sets the blowing speed of the exhaust gas into the combustion furnace at a predetermined value or more, and thus prevents flashback. Usually, this blowing speed is set to a flashback speed of carbon monoxide of 1 m / sec or more, preferably 10 m / sec or more.
m / sec or more. The blowing speed is adjusted by appropriately selecting the number of holes and the size of the holes in the perforated plate.

When using the gas treatment equipment of the present invention, the exhaust gas containing zinc vapor generated from the reduction furnace is introduced into the condenser to remove zinc vapor, and then introduced into the gas treatment equipment of the present invention. Most of the dust in the exhaust gas is removed by the dry dust remover. Then, the exhaust gas containing fine dust passes through the control damper and the emergency cutoff valve, is adjusted to a predetermined gas velocity by the perforated plate, and is blown into the carbon monoxide combustion furnace. Carbon monoxide in the exhaust gas is burned in a carbon monoxide combustion furnace to become carbon dioxide. The combustion heat generated at this time can be effectively recovered and utilized by, for example, introducing the carbon monoxide combustion furnace exhaust gas into a drying facility, and the exhaust gas is finally rendered harmless and released into the atmosphere.

[0014]

EXAMPLES Next, examples of the present invention will be described. (Example 1) As a reduction furnace, a reaction tower having an inner diameter of 1.5 m and a height of 2.5 m, and a inner diameter of 1.5 m, It has a settler with a length of 5.25m. After the settler, a condenser with an inner dimension of 5mm, a width of 1m, and a height of 0.58m is installed, and the inner dimension is 1m wide just above the discharge end of the condenser.
m, depth 0.8m, height 2.6m offtake,
After the offtake, a dust chamber with a width of 1.5 m, a depth of 1 m, and a height of 3 m and a combustion chamber with a width of 0.8 m, a length of 4.7 m, and a height of 1.7 m as inner dampers were used as control dampers. The butterfly valve, the butterfly valve as an emergency shutoff valve, and a perforated plate having 30 holes with a diameter of 35 mm opened as evenly as possible as possible at 30 locations. A zinc recovery facility including the gas treatment facility of the invention was constructed. At this time, both the control damper and the emergency shutoff valve were attached to the vertical piping so that the respective valve bodies were horizontal when fully closed. Exhaust gas in the combustion chamber was cooled by a water-cooling jacket type cooler, dust-removed by a bag filter having a heat-resistant temperature of 250 ° C., and released into the atmosphere.

Using this zinc recovery facility, 297 kg / h of zinc-containing raw material, 416 kg / g of coke powder, oxygen (purity 90%) 408 Nm ³ / h, air 140 Nm ³ /
After charging H for continuous operation for 5 days, the operation was stopped, and the state of dust adhesion on the control damper part was observed and the operating state of the emergency shutoff valve was confirmed.

As a result, the dust is 10 mm in the horizontal pipe section.
Since the deposits were only of a moderate thickness, the deposits on the control damper and the emergency shutoff valve did not pose any problem, confirming the good operation of the control damper during operation. In addition, the emergency shutoff valve actuated at the same time as the operation was stopped and was fully closed. The blowing speed of the exhaust gas blown into the combustion furnace from the perforated plate during the main operation was 13 m / sec (8 Nm / sec), and the carbon monoxide concentration in the exhaust gas at the combustion furnace inlet was 48%. It was In addition, the dust concentration in the discharged gas removed by the bag filter installed after the combustion furnace is always 0.004 g.
/ Nm ³ or less, which could be released into the atmosphere as it was.

As described above, according to this embodiment, it is obvious that the conventional wet dust removing equipment need not be used if the gas treatment equipment of the present invention is used.

[0018]

By using the gas treatment equipment of the present invention, since the wet dust removal equipment is not used, the waste water treatment accompanying the treatment of exhaust gas containing carbon monoxide discharged from the condenser can be made unnecessary.

Front page continued (72) Inventor Keiji Fujita Ai Saijo City, Ehime Prefecture Sakuichi City 227-3

Claims (3)

[Claims] 1. A gas used to remove zinc in exhaust gas discharged from a reduction furnace, remove dust to supply it to a carbon monoxide combustion furnace, and remove dust in a step of burning carbon monoxide in the exhaust gas. In the treatment facility, a dry dust remover provided after the condenser, a control damper provided after the dry dust remover, an emergency shutoff valve provided after the control damper, and an emergency shutoff valve provided after the emergency shutoff valve An exhaust gas treatment facility comprising a perforated plate and a valve body of a control damper mounted so as to be horizontal when fully closed. 2. The exhaust gas treatment equipment according to claim 1, wherein a butterfly valve is used as the emergency shutoff valve, and the valve body is mounted so that the valve body becomes horizontal when the butterfly valve is fully closed. 3. The exhaust gas treatment equipment according to claim 1, wherein a sluice valve is used as the emergency shutoff valve, and the sluice valve is mounted so that the valve body is vertical when the sluice valve is fully closed.