JPH05231632A - Local exhauster - Google Patents

Abstract

PURPOSE:To improve safety against such a trouble of ignition of oil mist adhering to an exhaust duct, by a method wherein the title exhauster prevents the oil mist from adhering to the exhaust duct while cooling the exhaust duct. CONSTITUTION:Cooling water is injected from upper and lower shower heads 6, 7 provided on an exhaust duct 1, is always allowed to flow along the inner surface of the exhaust duct 1 and to circulate, and thus the cooling water cools the exhaust duct 1. Oil mist contained in exhaust smoke S, such as soot, produced on a quenching oil tank 4 is caught being in contact with the cooling water flowing inside the exhaust duct 1 and the exhaust smoke S is purified. In this way, the oil mist can be prevented from adhering to the inner surface of the exhaust duct 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local exhaust system for local exhaust in a local exhaust unit such as a quenching furnace or a tempering furnace for heat treatment in a factory.

[0002]

2. Description of the Related Art For example, a local exhaust device used in a quenching oil tank of a quenching furnace has a structure shown in FIG. This is an exhaust hood 3 in which a lower end portion 1a of an exhaust duct 1 having an axial flow type exhaust fan 2 extends in a skirt shape.
The upper end portion 1b of the exhaust duct 1 is exposed from the roof 5 of the factory building to the outside through the exhaust fan 1 and the exhaust gas S such as oil smoke generated in the quench oil tank 4 is exhausted by the exhaust fan. 2, the suction duct 1 is sucked to the exhaust duct 1 side and discharged to the outside.

[0003]

In the conventional local exhaust system as described above, in addition to the oil mist contained in the oil smoke adhering to the inner peripheral surfaces of the exhaust duct 1 and the exhaust hood 3 due to long-term operation, Since the exhaust duct 1 and the exhaust hood 3 are heated by the flue gas S, hot air or flame may be momentarily generated on the quenching oil tank 4 side during the quenching process. Even if it does not lead to a fire, the exhaust duct 1
The oil mist adhering to the exhaust hood 3 or the exhaust hood 3 may catch fire, resulting in, for example, activation of a fire alarm device or an automatic fire extinguisher device, which is not preferable.

The present invention has been made in view of the above problems, and collects components such as oil mist contained in exhaust gas (exhaust gas) to generate deposits on the inner peripheral surface of the exhaust duct. It is intended to provide a structure in which the above-mentioned deposit is prevented from catching fire by cooling the exhaust duct itself as much as possible.

[0005]

According to the present invention, a lower end of an exhaust duct is exposed to a local exhaust required for local exhaust through an exhaust hood, and an upper end of the exhaust duct is exposed outdoors. In a local exhaust device in which an exhaust fan provided in the exhaust duct sucks the exhaust gas of a local exhaust part and discharges it to the outdoors, the exhaust duct is always cooled from above the exhaust duct while the exhaust fan is operating. It is characterized in that cooling water discharge means is provided for discharging water and causing the cooling water to flow downward along the inner peripheral surface of the exhaust duct.

[0006] It is desirable for effective utilization of water resources to collect the cooling water that has flowed down along the exhaust duct and recycle it.

[0007]

According to this structure, the cooling water flows along the inner peripheral surface of the exhaust duct at least as long as the exhaust fan is operating. Therefore, even if the exhaust gas discharged through the exhaust duct contains components such as oil mist, the inner peripheral surface of the exhaust duct is protected by cooling water, and the components such as oil mist flow through the exhaust duct. Since it is collected by contact with water, the inner peripheral surface of the exhaust duct and the components such as oil mist do not come into direct contact with each other, which allows the components such as oil mist to adhere to the inner peripheral surface of the exhaust duct. Can be prevented.

Since the exhaust duct is cooled by the cooling water flowing through the inner peripheral surface of the exhaust duct as described above, even if components such as oil mist adhere to the inner peripheral surface of the exhaust duct. It is possible to prevent the components from catching fire.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 are views showing an embodiment of the present invention, and show an example of a local exhaust system for exhausting in a quenching oil tank 4 similarly to FIG. 3, which is common to FIG. The same reference numerals are given to the portions to be performed.

As shown in FIGS. 1 and 2, annular shower heads 6 and 7 are individually provided at the upper and lower portions of the exhaust duct 1 as cooling water discharge means, and these shower heads 6 are provided. , 7, the water in the cooling water tank 8 is supplied as the cooling water W by the pump 9 through the water supply pipe 10.

As shown in FIG. 2, the shower heads 6 and 7 are formed by bending a predetermined pipe material into a ring shape so as to have a diameter smaller than that of the exhaust duct 1. A plurality of nozzle holes 11 that are directed obliquely downward are formed on the outer periphery at equal pitches along the circumferential direction. Therefore, each of the shower heads 6 and 7 jets the cooling water W obliquely downward to the inner circumferential surface of the exhaust duct 1, and the jetted cooling water W goes downward along the inner circumferential surface of the exhaust duct 1. It will flow.

In the exhaust duct 1, upstream of the exhaust fan 2, the upper and lower stages of the water receiving channels 12, 13 are provided.
While the exhaust hood 3 is provided with the rectifying plate 14
A relatively large water receiving tank 15 which is integrated with the above is provided, and a draining plate 16 which prevents the cooling water W from scattering outward is provided above the water receiving tank 15. Then, the cooling water W jetted from the shower head 6 on the upper side and flowing down in the exhaust duct 1 is the water receiving channel 12 or 1.
All the cooling water W that has been collected in 3 and then returned to the cooling water tank 8 through the recovery pipe 17 and sprayed from the shower head 7 on the lower side to flow down to the upper part of the exhaust hood 3 is collected in the water receiving tank 15. After being collected, it is returned to the cooling water tank 8 through the recovery pipe 18.

The upper and lower water receiving channels 12, 1
The water receiving channel 13 on the lower side of 3 is made to face the central portion side of the exhaust duct 1 rather than the water receiving channel 12 on the upper stage in order to collect the cooling water W which could not be collected by the water receiving channel 12 on the upper stage. There is.

On the other hand, the cooling water tank 8 has a filter 19 and a ball tap valve (float valve) 20.
Is provided. The filter 19 serves to remove foreign matter contained in the cooling water W returned to the cooling water tank 8 from the recovery pipes 17 and 18, and the ball tap valve 20 keeps the water level in the cooling water tank 8 due to evaporation or the like. When the water falls, the opening of the water supply pipe 21 is opened according to the displacement of the ball (float) to automatically replenish and supply cooling water until a predetermined water level is reached.

In FIG. 1, solid arrows indicate the flow of cooling water W, and broken arrows indicate the flow of smoke exhaust S.

Therefore, according to the structure of this embodiment, since the pump 9 is linked to the activation of the exhaust fan 2, when the operation of the exhaust fan 2 is started, the pump 9 is activated and the shower heads 6, 6. The cooling water W is supplied to 7, and the shower heads 6 and 7 spray the cooling water W on the inner peripheral surface of the exhaust duct 1, while exhausting smoke such as oil smoke generated by the quenching process in the quenching oil tank 4. S is sucked from the exhaust hood 3 to the exhaust duct 1 side by the exhaust fan 2 and is discharged outdoors.

As described above, as long as the exhaust fan 2 is in operation, the shower heads 6 and 7 are constantly discharged with the cooling water W.
The cooling water W discharged from the water flows downward along the inner peripheral surface of the exhaust duct 1 and then the water receiving channel 12 or 13
And is returned to the cooling water tank 8. The cooling water W discharged from the lower shower head 7 flows from the lower end portion 1 a of the exhaust duct 1 along the upper inner peripheral surface of the exhaust hood 3, and then is collected in the water receiving tank 15 and is stored in the cooling water tank 8. The cooling water W is constantly circulated around the inner peripheral surface of the exhaust duct 1 when returned.

Therefore, while the exhaust duct 1 is constantly cooled by the cooling action of the cooling water W, the inner peripheral surface of the exhaust duct 1 is covered with the flow of the cooling water W, so the cooling water W
In the portion where the exhaust gas flows, the exhausted smoke S such as oil smoke generated in the quenching oil tank 4 and flowing through the exhaust duct 1 does not directly contact the inner peripheral surface of the exhaust duct 1. Exhaust smoke S such as oil smoke flowing in the exhaust duct 1 comes into contact with the cooling water W flowing in the exhaust duct 1 to cause the components such as oil mist contained in the exhaust smoke to become the cooling water W. The collected flue gas S is purified by contact with the cooling water W, and is then discharged from the upper end portion 1b of the exhaust duct 1 to the outside.

Therefore, it is possible to prevent the oil mist contained in the flue gas S from adhering to the inner peripheral surface of the exhaust duct 1, and even if hot air or flame is generated on the quenching oil tank 4 side as in the conventional case, those The oil mist attached to the exhaust duct 1 will not catch fire.

Further, the cooling water W sprayed from the upper and lower shower heads 6 and 7 has two upper and lower water receiving channels 12 and 1.
3 and the water receiving tank 15 are surely collected and then collected, and further, the scattering of the cooling water W flowing into the water receiving tank 15 to the outside is prevented by the draining plate 16 and the flange portion 22 of the water receiving tank 15. The water W never enters the quenching oil tank 4.

Here, it goes without saying that the present invention can be applied to a local exhaust portion other than the quenching oil tank 4 of the quenching furnace exemplified in the above embodiment.

[0022]

As described above, according to the present invention, the cooling water discharging means provided in the exhaust duct discharges the cooling water so that the cooling water flows along the inner peripheral surface of the exhaust duct. Not only the exhaust duct is cooled by the cooling water, but also the components such as oil mist contained in the exhaust gas are collected by the cooling water for the purpose of purifying the exhaust (flue gas) by the cooling water. Even if the exhaust contains oil mist, the oil mist does not adhere to the inner peripheral surface of the exhaust duct, and there is no risk of ignition to the oil mist adhered to the inner peripheral surface of the exhaust duct as in the past, which is safe. Sex is further improved.

Further, as described above, by preventing the oil mist from adhering to the exhaust duct, the man-hour required for cleaning the local exhaust system can be reduced, and the exhaust gas discharged to the outside can be purified in advance by the cooling water. Therefore, there is an effect that air pollution due to exhaust gas can be prevented.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a local exhaust device showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a structural explanatory view showing an example of a conventional local exhaust system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Exhaust duct 1a ... Lower end 1b ... Upper end 2 ... Exhaust fan 3 ... Exhaust hood 4 ... Quenching oil tank (local exhaust part required) 6, 7 ... Shower head 8 ... Cooling water tank 9 ... Pump 12, 13, ... Water channel 15 ... Water tank S ... Smoke exhaust W ... Cooling water

Claims (1)

[Claims] 1. A lower end portion of an exhaust duct is exposed through an exhaust hood to a local exhaust portion requiring local exhaust,
In the local exhaust device, the upper end of the exhaust duct is exposed to the outside, and the exhaust fan provided in the exhaust duct sucks the exhaust gas of the local exhaust part and discharges it to the outdoors. Local exhaust gas characterized by being provided with cooling water discharge means for discharging cooling water from above the exhaust duct at all times during operation of the fan and allowing the cooling water to flow downward along the inner peripheral surface of the exhaust duct. apparatus.