JPS5810146B2 - Shitsushiki Denki Yujinki - Google Patents

Description

[Detailed description of the invention] The present invention relates to a wet electrostatic precipitator.

Recently, a wet electrostatic precipitator using electrospray as shown in FIG. 2 has been proposed.

This wet type electrostatic precipitator consists of collection electrode plates 1 and 1 installed in parallel.
, 1 . . . , and a high-voltage charged pipe connected to the liquid supply pipe 2a is placed in the vertical center of the divided gas flow path (midway between the two collecting electrode plates 1, 1). The electric spray nozzles 3a are arranged in multiple stages, and the direction of the charged liquid is attracted and separated by the strong electrostatic field generated between the charged electric spray nozzles 3a and the collector plate 1. It flies, and during the flight it comes into contact with dust-containing gas and collects dust.

In this type of wet electrostatic precipitator, when the charged electrolytic spray nozzle 3a is charged to a state just before dielectric breakdown, the droplets fly toward the collecting electrode plate as if being electrically attracted, and the liquid that comes into contact with dust-containing gas on the way The droplets will eventually be reliably adsorbed on the collecting plate,
It is known that the droplet recovery rate is extremely high.

However, when put into practical use, there is a risk that spark discharge may occur due to the accumulation of collected dust on the collecting electrode plate 1 or changes in the thickness of the falling layer of collected droplets, so the best conditions for electrospraying may be required. It is not possible to operate in a charged state immediately before dielectric breakdown, and a considerable amount of droplets are lost to the outside of the system along with the airflow.

In particular, it is practical to arrange the charged electric spray nozzle in multiple stages as shown in Figure 2, so that the droplets come into contact with the dust-containing air stream multiple times. Loss of the spray droplets cannot be prevented since the lower surface of the fuel cell 1 must be operated within dielectric breakdown limits under conditions of highest dust accumulation and high liquid flow rate.

In view of the above, the present invention has developed a wet electrostatic precipitator that prevents spray droplets from escaping out of the system along with airflow, and improves dust collection efficiency by reliably collecting spray droplets. The present invention provides a wet type electrostatic precipitator with improved performance.

The present invention will be described below based on embodiments shown in the accompanying drawings.

Reference numeral 1.1 denotes a collecting electrode plate 1 that stands in parallel and is grounded. A large number of parallel collecting electrode plates 1 are placed side by side in the main body of the dust collector (not shown), and divide the gas flow path in the vertical direction. , so that the gas passes from the bottom to the top through each divided gas flow path, that is, between the pair of juxtaposed collecting electrode plates 1, 1.

Charged electric spray nozzles 3, 3 are arranged in a stepped manner in the vertical center of each of the divided gas flow paths.

A high voltage terminal of a high voltage generator 4 is connected to this charged electric spray nozzle 3 (it may be connected via a liquid supply pipe 2 connected to the electric spray nozzle 3 or a liquid supplied by the liquid supply pipe 2). .

), while the collector plate 1 is charged with the opposite sign (grounded)
By doing so, the liquid in the liquid supply pipe 2 becomes droplets 6 due to the strong electrostatic field between the charged electric spray nozzle 3 and the collecting electrode plate 1.
The direction toward the collecting electrode plate 1 is designed to be suction-flighted.

The charged electric spray nozzle in the lower stage is charged to a lower voltage than the upper stage through the resistor R, which reduces the amount of dust adhering and makes it difficult to generate spark discharge in the lower stage where the liquid flow rate on the surface of the collecting electrode plate 1 is large. By charging to a low voltage and then applying a higher voltage to the upper stage, when the droplet 6, once charged at a low voltage, rises with the airflow, it is tilted toward the collecting electrode plate 1 side by receiving a repulsive force. None.

Below the charged electric spray nozzles 3, 3, an uncharged droplet spray nozzle 5 is located at the vertical center of the similarly divided gas flow path.
Although this droplet spray nozzle 5 is not shown, the liquid collected by the collecting electrode plate 1 is used for circulation.

Since the droplets 7 of the droplet spray nozzle 5 also serve to clean the collecting electrode plate 1, it is preferable to use an empty conical spray nozzle, or more preferably an empty conical spray nozzle as shown in FIG.

Reference numeral 8 denotes a repulsion electrode, and the repulsion electrode 8 uses the collection electrode plates 1 and 1, is disposed between the collection electrode plates 1 and 1, and is connected to the high voltage terminal of the high voltage generator 4. , anti-flash electrode 8
A strong electrostatic field is generated between the collecting electrode plates 1 and 1.

As shown in FIGS. 4A to 4G, this reciprocating electrode 8 is
A flat plate, a window lattice flat plate, a corrugated plate, a multi-needle plate, etc. may be used, but the charge should be of the same sign as the electric spray nozzle 3, and preferably at a higher voltage than the electric spray nozzle 3. They are charged to at least the same voltage.

Therefore, in the wet electrostatic precipitator of the present invention, the dust-containing airflow flowing in from below the gas flow path first contacts the spray droplets 7 of the droplet spray nozzle 5 to remove large-diameter dust, and then together with the airflow. The remaining dust and mist rises and is removed by contact with the charged droplets 6 sprayed from the charged electric spray nozzle 3, and the charged droplets 6 after contact are collected by the collection electrode plate 1 and cleaned. Gas rises.

Of course, this clean gas is not completely free of dust and mist of the sprayed liquid, and these fine dust and mist are repelled by the repulsion electrode 8 and are removed from the vertical rise of the airflow, and are transferred to the collecting electrode plates 1, 1 side. The particles move at an angle, and are eventually collected on the collecting electrode plates 1, 1.

In addition, in the wet type electrostatic precipitator of the present invention, the uncharged droplet spray nozzle 5 is located on the upstream side of the air flow path, that is, below the charged electric spray nozzle 3, where the largest amount of dust accumulates and the largest number of collected droplets flow down. Since the droplet spray nozzle 5 is also charged, there is less risk of dielectric breakdown, and the electrically charged spray nozzle 3 on the downstream side of the airflow can be charged at a high voltage. Spray droplets can be collected reliably.

In addition, the droplet spray nozzle 5 can freely select the droplet diameter and droplet amount, and the droplet spray nozzle 5 can spray minute droplets that come into frequent contact with dust but are easily accompanied by airflow. However, these minute droplets are collected by the charged droplets in the next stage and the repulsion force of the repulsion electrode, thereby improving the dust collection efficiency.

Furthermore, the charged electric spray nozzle 3 cannot use circulating water because the inner diameter of the nozzle cannot be made extremely large and the conductivity of the liquid must not be too high. Circulating water can be used, and even if the amount of spray is increased, the amount of water consumed will not increase.

Furthermore, since the wet electrostatic precipitator of the present invention is provided with the repellent electrode 8 at the most downstream position, it is possible to collect mist that could not be collected even by electrospraying from the charged electrospray nozzle 3, and drop droplets. Even if the droplets sprayed from the spray nozzle 5 rise with the airflow, they are collected by the two-step action of electric spray and repellent electrode, and are efficiently misted with extremely low pressure loss. As a result, it has a remarkable effect on improving dust collection efficiency.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view explaining the principle of an embodiment of the wet electrostatic precipitator of the present invention, Fig. 2 is a longitudinal cross-sectional view of a conventional method, Fig. 3 is a cross-sectional view taken along line Y-Y in Fig. 1, and Fig. 4 is a book. A shows an example of the reciprocating electrode used in the invention. D and F are plan views, and B, C, E, and G are partial perspective views. 1...Collection electrode plate, 2...Liquid supply tube, 3.
...Charged electric spray nozzle, 4...High voltage generator, 5...Droplet spray nozzle, 6...
...Droplet, 7...Droplet, 8...Reverse electrode, 9...Insulator.

Claims (1)

[Scope of Claims] 1. A charged electric spray nozzle is disposed in the vertical center of a gas flow path divided by collecting electrode plates arranged in parallel and grounded to attract and fly charged droplets toward the collecting electrode plates. In the wet electrostatic precipitator, an uncharged droplet spray nozzle is disposed below the charged electric spray nozzle in the vertical center of the gas flow path, and an uncharged droplet spray nozzle is arranged above the charged electric spray nozzle in the gas flow path. for,
A wet electrostatic precipitator comprising a reciprocal electrode charged to the same polarity as the charged electric spray nozzle.