JP3896729B2 - Wet electric dust collector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wet type electrostatic precipitator that prevents a decrease in spark voltage caused by rebound of droplets sprayed and sprayed on a dust collecting electrode.
[0002]
[Prior art]
The boiler exhaust gas treatment system using coal, heavy oil, etc. as a fuel is equipped with a wet desulfurization device to remove sulfur oxides in the exhaust gas, followed by a wet electrostatic precipitator to prevent purple smoke from the chimney Is done. In the wet desulfurization apparatus, water such as circulating water is spray-sprayed in the exhaust gas, the exhaust gas temperature is lowered to the saturation temperature, and the sulfur oxide is absorbed and removed. For this reason, exhaust gas containing a large amount of mist such as water and sulfuric acid is introduced into the wet electrostatic precipitator.
When a high voltage is applied between the discharge electrode and the dust collecting electrode, the mist in the exhaust gas is charged with ions released by the discharge from the discharge electrode. Then, after moving in the direction of the dust collecting electrode by the coulomb generated by the electric field, it is collected on the dust collecting electrode and washed with spray water. Therefore, since the mist collection efficiency is higher when the charge amount is larger and the applied voltage is higher, the wet electrostatic precipitator uses a discharge electrode in which a needle is attached to a base material capable of obtaining a large corona current.
[0003]
[Problems to be solved by the invention]
By the way, the corona current can be further increased if the applied voltage can be increased, but the upper limit is determined by the spark voltage between the discharge electrode and the dust collecting electrode. In the conventional wet electrostatic precipitator, the lengths of the needles attached to the base material of the discharge electrode supplied from one high voltage power source are all the same. As a result of investigating the spraying state of the spray and the occurrence of sparks while applying a spray while operating the spray with a conventional wet electrostatic precipitator, the occurrence of sparks is mainly sprayed to the dust collecting electrode by the spray. When the high voltage is applied, the liquid droplets that have been viewed are almost collected electrically at the dust collection electrode to a position approximately 100 mm below the rebound part. It was confirmed that
An object of the present invention is to provide a wet type electrostatic precipitator that prevents a decrease in spark voltage caused by droplet rebound.
[0004]
[Means for Solving the Problems]
According to the first aspect of the present invention, the particulate matter in the dust collection space is electrically collected on the dust collection electrode with a high voltage applied to the discharge electrode having a structure in which a needle is attached to the base material, and spray sprayed from above In the wet type electrostatic precipitator that cleans the dust collecting electrode by means of, the needle attached to the base material of the discharge electrode is directed to the dust collecting electrode, and the length of the needle located above the spray spray is shortened .
In the invention of claim 2, particulate matter in the dust collection space is electrically collected on the dust collection electrode with a high voltage applied to the discharge electrode, and the dust collection electrode is cleaned by spraying from above. In the wet type electrostatic precipitator to be performed, the discharge electrode has a base material formed by punching a flat plate and a needle-like part, the needle-like part is directed to the dust collecting electrode, and the needle-like part is located above the spray spray. It is the structure which shortened the length of the part.
[0005]
[Effects of the Invention]
According to the configuration of claim 1, by shortening the length of the needle of the discharge electrode arranged near the place where the droplet sprayed on the dust collecting electrode bounces, and by increasing the distance between the needle tip and the dust collecting electrode. It is possible to prevent a decrease in spark voltage caused by looking back at the droplets.
According to the configuration of the second aspect, since the base material and the needle-like portion of the discharge electrode are produced by punching with a flat plate, the manufacturing process is simplified and the processing for the plate material is easy, and the cost can be reduced.
According to the present invention, since the voltage applied to the discharge electrode can be increased, the mist collection efficiency of the wet electrostatic precipitator can be increased.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a wet type electrostatic precipitator to which the present invention is applied.
The wet electrostatic precipitator 10 is mainly composed of a discharge electrode 12, a deer electrode 14, and a spray nozzle 16, which are housed in a housing 18. The housing 18 is provided with an inlet 19 for introducing the processing gas, an outlet 20 for discharging the treated clean gas, and a drain (not shown) for cleaning at the bottom. A processing gas containing mist is introduced into the wet electrostatic precipitator 10 from the inlet 19 in the direction of the arrow 30, and the clean gas from which the mist has been removed is discharged from the outlet 20.
[0007]
In the housing 18, dust collecting electrodes 14 and discharge electrodes 12 are alternately arranged at predetermined intervals, and mist in the exhaust gas introduced between both electrodes is charged by corona discharge from the discharge electrodes 12. It is collected by the dust collecting electrode 14 by Coulomb force. As shown in FIG. 2, the discharge electrode 12 has a structure in which a needle 24 is attached to a base material 22, and the needle 24 is arranged at a predetermined interval toward the dust collection electrode 14. In FIG. 3, the discharge electrode 12 is formed by forming a base material 22 with a pipe and welding the root of a needle 24 to the outer periphery of the pipe. The length of the needle 24 is shortened to the vicinity of the position where the droplet sprayed from the spray nozzle 16 rebounds at the dust collection electrode 14, and is made longer below that position. In this example, three short needles 24a are arranged above the spray nozzle 16 side, and long needles 24 are arranged below it. Reference numeral 23 denotes a lid attached to the upper end of the pipe 22 by welding or the like.
[0008]
FIG. 4 is a perspective view showing another embodiment of the discharge electrode. In the present embodiment, the base material of the discharge electrode and the needle-like portion directed to the dust collecting electrode are punched out from a flat plate. The discharge electrode 12 has a plurality of needle-like portions 34 extending along the plate surface with a base material 32 having a predetermined width symmetrical, and each needle-like portion 34 has an oblique upper side and a horizontal lower side. It forms a triangle and is formed on the side of the base material 32. The plurality of upper needle-like parts 34a arranged on the spray nozzle 16 side shorten the length from the base material 32 to the apex of the triangle, and the plurality of needle-like parts 34 arranged below the upper part are upper It is formed to be longer than the needle-like portion 34a.
[0009]
Next, the operation of this embodiment will be described.
Exhaust gas containing mist is introduced into the wet electrostatic precipitator 10 and a high voltage is applied between the discharge electrode 12 and the dust collecting electrode 14. As a result, the mist is charged and collected on the dust collecting electrode 14 by Coulomb force. The collected mist is washed away with water sprayed from the spray nozzle 16 to the dust collecting electrode 14. The droplet sprayed on the dust collecting electrode 14 bounces off at the dust collecting electrode 14 as shown in FIG. 2, but it is within 100 mm below the bounce portion due to corona discharge from the discharge electrode 12 arranged in the vicinity of the bounce portion. Most are collected electrically. Further, since the length of the needle 24 of the discharge electrode 12 is short and the distance between the tip of the needle 24 and the dust collecting electrode 14 is long, the spark voltage due to the rebound is increased. Therefore, the applied voltage applied to the discharge electrode of the entire wet electrostatic precipitator can be increased.
[0010]
In the area where the length of the needle is shortened, the distance between the needle tip and the dust collecting electrode becomes long, so that the corona current is difficult to flow and the amount of mist charge is reduced, and the dust collecting performance in this area is reduced. The height of this region is within several hundred millimeters compared to several thousand millimeters of the height of the dust collecting electrode, and the ratio of the total area is small. On the other hand, since the applied voltage applied to the discharge electrode of the entire wet electrostatic precipitator increases, the dust collection performance is greatly improved.
In addition, although the present Example demonstrated the wet-type electrostatic precipitator with a horizontal gas flow, it is applicable similarly to the case of a vertical gas flow.
[0011]
【The invention's effect】
According to the present invention, since the applied voltage can be increased, the mist collection efficiency of the wet electrostatic precipitator can be maintained at high efficiency.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating a wet electrostatic precipitator according to the present invention.
FIG. 2 is an explanatory diagram of a spray situation during cleaning.
FIG. 3 is a perspective view of a discharge electrode.
FIG. 4 is a perspective view of another embodiment of a discharge electrode.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Wet electrostatic precipitator 12 Dust collection electrode 14 Discharge electrode 16 Spray nozzle 22 Base material 24 Needle 32 Base material 34 Needle-shaped part

Claims (2)

Particulate matter in the dust collection space is electrically collected on the dust collection electrode with a high voltage applied to the discharge electrode with a needle attached to the base material, and the dust collection electrode is cleaned by spraying from above. In the wet electrostatic precipitator to perform,
A wet electrostatic precipitator characterized in that a needle attached to a base material of the discharge electrode is directed to a dust collecting electrode, and the length of the needle located above the spray is shortened. In a wet type electrostatic precipitator that collects particulate matter in the dust collection space electrically with a high voltage applied to the discharge electrode and collects the dust collection electrode by spraying from above.
The discharge electrode has a base material formed by punching a flat plate and a needle-like portion, and directs the needle-like portion toward the dust collecting electrode and shortens the length of the needle-like portion located above the spray spray. Wet electrostatic precipitator characterized by the above.

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