JP7296248B2 - wet electrostatic precipitator - Google Patents

Description

The present invention relates to a wet electrostatic precipitator.

Conventionally, various wet electrostatic precipitators have been developed and proposed as wet electrostatic precipitators (WESPs) for removing dust (see, for example, Patent Document 1).

JP 2013-240741 A

SUMMARY OF THE INVENTION An object of the present invention is to provide a wet type electrostatic precipitator capable of further improving the dust collection efficiency as compared with the conventional one.

A wet electrostatic precipitator according to one aspect of the present invention comprises:
In a wet electrostatic precipitator that removes dust from exhaust gas supplied from the outside,
a cylindrical dust collecting electrode;
a center dust collection electrode provided in the center of the outer cylindrical dust collection electrode;
a discharge electrode provided between the outer cylinder dust collection electrode and the central dust collection electrode;
a lid provided on top of the outer cylinder dust collection electrode;
a treated water supply unit provided above the outer cylindrical dust collecting electrode and supplying treated water to surfaces of the outer cylindrical dust collecting electrode and the central dust collecting electrode;
a head projecting from the lid so as to have a convex shape;
a rod-shaped voltage applying electrode at least partially housed in the head and having a lower end connected to the discharge electrode;
a plate-shaped buffer plate provided in a portion of the voltage applying electrode accommodated in the head;
a purge gas supply unit provided in the head for supplying a purge gas into the head;
a rectifying cover provided on the lower surface side of the lid so as to cover the opening of the head, and having an electrode hole in the central portion thereof for inserting the voltage applying electrode.

In addition, the wet electrostatic precipitator according to one aspect of the present invention is
In a wet electrostatic precipitator that removes dust from exhaust gas supplied from the outside,
a cylindrical dust collecting electrode;
a discharge electrode provided in the center of the outer cylindrical dust collection electrode;
a lid provided on top of the outer cylinder dust collection electrode;
a treated water supply unit provided on the upper portion of the outer cylinder dust collection electrode for supplying treated water to the surface of the outer cylinder dust collection electrode;
a head projecting from the lid so as to have a convex shape;
a rod-shaped voltage applying electrode at least partially housed in the head and having a lower end connected to the discharge electrode;
a plate-shaped buffer plate provided in a portion of the voltage applying electrode accommodated in the head;
a purge gas supply unit provided in the head for supplying a purge gas into the head;
a rectifying cover provided on the lower surface side of the lid so as to cover the opening of the head, and having an electrode hole in the central portion thereof for inserting the voltage applying electrode.

According to the wet type electrostatic precipitator of the present invention, the dust collection efficiency can be further improved as compared with the conventional one.

BRIEF DESCRIPTION OF THE DRAWINGS It is a longitudinal cross-sectional view which shows the structure of the wet-type electrostatic precipitator by embodiment of this invention. It is a longitudinal cross-sectional view showing the cross-sectional structure near the upper part of the same wet-type electrostatic precipitator. It is a longitudinal cross-sectional view showing the cross-sectional structure near the upper portion of the wet type electrostatic precipitator of the comparative example. It is a longitudinal cross-sectional view showing the configuration of a wet type electrostatic precipitator according to another embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a wet type electrostatic precipitator 10 according to an embodiment of the present invention, and FIG. 2 shows the configuration of the vicinity of the upper portion of the wet type electrostatic precipitator 10. In general, an exhaust gas discharged from a semiconductor manufacturing apparatus is first subjected to a detoxification treatment (detoxification treatment) such as a combustion type or a plasma type in a detoxification device (not shown). The wet type electrostatic precipitator 10 is used for the purpose of removing dust from the exhaust gas G that has been subjected to this detoxification treatment (detoxification treatment) and discharged from the detoxification device.

Specifically, the wet electrostatic precipitator 10 is formed by erecting a cylindrical dust collection electrode 50 on a rectangular parallelepiped drain tank 20, and the drain tank 20 and the dust collection electrode 50 are , are integrally molded so as to communicate with each other.

A cylindrical central dust-collecting electrode 40 is suspended from the center of the cover 30H of the outer cylindrical dust-collecting electrode 50, and a cylindrical discharge is provided between the central dust-collecting electrode 40 and the outer cylindrical dust-collecting electrode 50. An electrode 60 is provided.

The inner and outer surfaces of the discharge electrode 60 are formed in a sawtooth shape, so that the inner surface of the discharge electrode 60 can perform corona discharge with the central dust collection electrode 40. , the outer surface side can perform corona discharge between the dust collection electrode 50 of the outer cylinder.

A treated water supply unit having a treated water inlet (not shown) is provided above the outer cylinder dust collection electrode 50 . can be injected in the form of a mist or curtain.

The exhaust gas G sequentially discharged from the semiconductor manufacturing equipment and the abatement equipment is introduced into the drain tank 20 through a transfer tube (not shown), and then rises inside the outer cylindrical dust collecting electrode 50 .

At that time, the dust in the exhaust gas G is charged with negative ions by corona discharge, attracted to the central dust collection electrode 40 or the outer cylinder dust collection electrode 50, and then washed down by the treated water W and dropped into the drain tank 20. do.

The treated water W accumulated in the drain tank 20 is drained to the outside through a drain port (not shown). On the other hand, the exhaust gas G from which the dust has been removed is discharged from the exhaust port 70 to the outside through a pipe (not shown).

On the lid 30H and around the exhaust port 70, a cylindrical head 80 is formed in a convex shape so as to protrude from the outer cylinder dust collecting electrode 50. The head 80 and the outer cylinder The dust collection electrode 50 is integrally formed so as to communicate with each other.

A rod-shaped voltage application electrode 90 is suspended from the center of the head lid 80H so as to penetrate the head lid 80H. is exposed from the head 80. As shown in FIG.

A voltage of −24 kV is applied to the voltage applying electrode 90, while the central dust collecting electrode 40 is grounded.

A disk-shaped buffer plate (baffle plate) 100 made of an insulating material, which is a separate part, is provided along the longitudinal direction of the portion of the voltage applying electrode 90 that is accommodated in the head portion 80 . They are provided at intervals, thereby preventing the treated water W from entering into the head 80 or rising not only in the form of water droplets but also in the form of mist.

A purge gas supply unit 110 having a purge gas hole is provided in the upper part of the head 80 , and by supplying a purge gas (dry air) PG from the purge gas supply unit 110 into the head 80 , the expected amount of air from the voltage applying electrode 90 is reduced. It prevents the occurrence of abnormal discharge that does not occur.

In the case of the present embodiment, a rectifying cover 120 having a U-shaped cross section is provided on the lower surface side of the lid 30H so as to cover the opening 130 of the head 80 and protrude downward. . An electrode hole 120H for inserting the voltage applying electrode 90 is formed in the center of the lower surface of the rectifying cover 120 .

Note that the rectifying cover 120 is made of, for example, polytetrafluoroethylene (PTFE), which is a fluororesin excellent in insulation and heat resistance.

By the way, as in the comparative example shown in FIG. 3, in which the parts corresponding to those in FIG. Therefore, the purge gas flows near the inner wall surface of the head 80, and the rising exhaust gas G containing moisture cannot be sufficiently purged to the voltage applying electrode 90, resulting in an unexpected abnormal discharge. occurrence cannot be avoided. Furthermore, since purging cannot be performed sufficiently, the exhaust gas G containing moisture rises through a small gap between the disk-shaped buffer plate 100 and the voltage applying electrode 90. , an abnormal discharge occurs at the root of the voltage applying electrode 90, which may cause a serious problem for the wet electrostatic precipitator 10 as a whole.

On the other hand, if the rectifying cover 120 is provided as in the present embodiment to regulate the flow of the purge gas PG, the portion of the voltage applying electrode 90 on the lower surface side of the lid 30H can also be sufficiently purged and dried. . As a result, it is possible to prevent the occurrence of unexpected abnormal discharge, and to prevent burnout of the voltage applying electrode 90 . In addition, wasteful consumption of energy can be prevented, and dust collection efficiency can be improved.

Incidentally, if the flow rate of the purge gas PG is C1, the inner diameter of the electrode hole 120H is _d1 , and the outer diameter of the voltage applying electrode 90 is _d2 , then the flow velocity V1 of the purge gas PG is expressed by Equation (1).
(Number 1)
V1=C1/(πd ₁ ² /4−πd ₂ ² /4) (1)

On the other hand, assuming that the flow rate of the exhaust gas G is C2, the inner diameter of the outer cylindrical dust collection electrode 50 is _D1 , and the outer diameter of the central dust collection electrode 40 is _D2 , the flow velocity V2 of the exhaust gas G is expressed by Equation (2). .
(Number 2)
V2=C2/(πD ₁ ² /4−πD ₂ ² /4) (2)

In order to obtain a drying effect on the voltage applying electrode 90, the wet electrostatic precipitator 10 is configured so that the formula (3) holds.
(Number 3)
V1>V2 (3)

In addition, in the above embodiment, the case where the present invention is applied to one dust collection electrode of the wet type electrostatic precipitator 10 was described, but the present invention is not limited to this. For example, a wet electrostatic precipitator 200 shown in FIG. 4 may be used. A wet type electrostatic precipitator 200 for removing dust from an exhaust gas G supplied from the outside, comprising a cylindrical outer cylinder dust collection electrode 220, a discharge electrode 60 provided in the center of the outer cylinder dust collection electrode 220, and an outer cylinder A lid 30H provided on the peripheral edge of the dust collection electrode 220, a treated water supply section provided on the upper portion of the outer cylinder dust collection electrode 220 for supplying treated water to the surface of the outer cylinder dust collection electrode 220, and a convex shape. a rod-shaped voltage applying electrode 90 at least partly accommodated in the head 80 and having a lower end connected to the discharge electrode 60, and the voltage applying electrode 90 Of these, a plate-like buffer plate 100 provided in the portion accommodated in the head 80, a purge gas supply unit 110 provided in the head 80 for supplying purge gas into the head 80, and A rectifying cover 120 provided on the lower surface side of the lid 30H so as to cover the opening 130 and having an electrode hole 120H for inserting the voltage applying electrode 90 in the central portion. The present invention can be widely applied to dust collectors.

Assuming that the flow rate of the exhaust gas G is C4 and the inner diameter of the outer cylinder dust collecting electrode 220 is _D3 , the flow velocity V4 of the exhaust gas G is: It is represented by Formula (4).
(Number 4)
^V4 =C4/( _πD32 /4) (4)

C3=C1 and V3=V1, and the wet electrostatic precipitator 200 is configured to satisfy the formula (5) in order to obtain a drying effect on the voltage applying electrode 90.
(Number 5)
V3>V4 (5)

In the above-described embodiment, the present invention is applied to the wet electrostatic precipitator 200 without the central dust collection electrode 40 .

Further, in the above-described embodiment, the case where the head 80 is formed to protrude from the lid 30H so as to have a convex shape has been described, but the present invention is not limited to this. You may form so that it may become one.

10, 200 Wet electrostatic precipitator 20 Drain tank 30H Lid 40 Center dust collection electrode 50, 220 Outer cylinder dust collection electrode 60, 210 Discharge electrode 70 Exhaust port 80 Head 80H Head lid 90 Voltage application electrode 100 Buffer plate 110 Purge gas supply unit 120 rectification cover 120H electrode hole 130 opening

Claims (2)

In a wet electrostatic precipitator that removes dust from exhaust gas supplied from the outside,
a cylindrical dust collecting electrode;
a center dust collection electrode provided in the center of the outer cylindrical dust collection electrode;
a discharge electrode provided between the outer cylinder dust collection electrode and the central dust collection electrode;
a lid provided on top of the outer cylinder dust collection electrode;
a treated water supply unit provided above the outer cylindrical dust collecting electrode and supplying treated water to surfaces of the outer cylindrical dust collecting electrode and the central dust collecting electrode;
a head projecting from the lid so as to have a convex shape;
a rod-shaped voltage applying electrode at least partially housed in the head and having a lower end connected to the discharge electrode;
a plate-shaped buffer plate provided in a portion of the voltage applying electrode accommodated in the head;
a purge gas supply unit provided in the head for supplying a purge gas into the head;
a rectifying cover provided on the lower surface side of the lid so as to cover the opening of the head, and having an electrode hole in the central portion for inserting the voltage applying electrode ,
Assuming that the flow rate of the purge gas is C1, the inner diameter of the electrode hole is _d1 , and the outer diameter of the voltage applying electrode is _d2 , the flow velocity V1 of the purge gas is expressed by equation (1),
(Number 1)
V1=C1/(πd ₁ ² /4−πd ₂ ² /4) (1)
Assuming that the flow rate of the exhaust gas is C2, the inner diameter of the outer cylindrical dust-collecting electrode is _D1 , and the outer diameter of the central dust-collecting electrode is _D2 , the flow velocity V2 of the exhaust gas is expressed by equation (2),
(Number 2)
V2=C2/(πD ₁ ² /4−πD ₂ ² /4) (2)
In order to obtain a drying effect on the voltage-applying electrode, it is configured so that equation (3) holds (Equation 3)
V1>V2 (3)
A wet electrostatic precipitator characterized by: In a wet electrostatic precipitator that removes dust from exhaust gas supplied from the outside,
a cylindrical dust collecting electrode;
a discharge electrode provided in the center of the outer cylindrical dust collection electrode;
a lid provided on top of the outer cylinder dust collection electrode;
a treated water supply unit provided on the upper portion of the outer cylinder dust collection electrode for supplying treated water to the surface of the outer cylinder dust collection electrode;
a head projecting from the lid so as to have a convex shape;
a rod-shaped voltage applying electrode at least partially housed in the head and having a lower end connected to the discharge electrode;
a plate-shaped buffer plate provided in a portion of the voltage applying electrode accommodated in the head;
a purge gas supply unit provided in the head for supplying a purge gas into the head;
a rectifying cover provided on the lower surface side of the lid so as to cover the opening of the head, and having an electrode hole in the central portion for inserting the voltage applying electrode ,
Let C3 be the flow rate of the purge gas, _d3 be the inner diameter of the electrode hole, and _d4 be the outer diameter of the voltage applying electrode.
(Number 4)
V3=C3/(πd ₃ ² /4−πd ₄ ^2/4 ) (4)
Assuming that the flow rate of the exhaust gas is C4 and the inner diameter of the outer cylinder dust collection electrode is _D3 , the flow velocity V4 of the exhaust gas is represented by the formula (5),
(Number 5)
^V4 =C4/( _πD32 /4) (5)
In order to obtain the drying effect on the voltage-applying electrode, it is configured so that the equation (6) holds (Equation 6)
V3>V4 (6)
A wet electrostatic precipitator characterized by:

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