JPS6044976B2 - electrostatic precipitator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic precipitator, and more particularly to an electrostatic precipitator suitable for removing dust from a gas to be processed containing high-resistance dust.

Regarding electrostatic precipitation of gases to be processed containing high-resistance dust, the problems of reduced collection efficiency and unstable operation due to reverse ionization are well known.

Various preventive measures have been attempted to prevent this reverse ionization phenomenon, and the present inventors have already proposed a moving electrode type electrostatic precipitator as one of the preventive measures. -27369 etc. disclosed some techniques.

This moving electrode type electrostatic precipitator is designed to prevent the formation of a thick dust deposit layer on the surface of the dust collecting electrode plate in order to prevent reverse ionization. In other words, the dust collection electrode plate is moved alternately between a dust collection area through which the gas to be treated passes and a non-dust collection area through which the gas to be treated does not pass, and the dust collected on the surface of the dust collection electrode plate in the dust collection area is removed. By adjusting the moving speed of the dust-collecting electrode plate, the surface of the dust-collecting electrode plate in the dust-collecting area has a dust accumulation layer to the extent that no reverse ionization phenomenon occurs. thickness can be suppressed. In order to use this moving electrode type electrostatic precipitator more effectively, attempts have been made to use a dust collection method or device in combination with other dust collectors.

For example, by installing a regular fixed flat plate type electrostatic precipitator in front of a moving electrode type electrostatic precipitator and connecting these electrostatic precipitators with a duct, dust in the gas to be treated can be collected first by the fixed flat plate type electrostatic precipitator. Attempts have been made to roughly remove high-resistance dust with an electrostatic precipitator, and then use a subsequent moving electrode electrostatic precipitator to collect high-resistance dust that is difficult to collect with a fixed flat plate electrostatic precipitator. However, in the above configuration, since a duct is interposed between the front and rear dust collectors, the gas to be treated once rectified by the fixed flat plate electrostatic precipitator condenses in the duct, and returns to the rear stage. Due to the diffusion within the moving electrode type electrostatic precipitator, the flow of the gas to be treated is unstable and undesired excessive flow or drift occurs, resulting in unstable operation and a decrease in the dust collection rate.

In particular, with a moving electrode type electrostatic precipitator, due to its structural characteristics, the volume of the non-dust collecting area is large in proportion to the total volume of the casing, so if the flow of the gas to be treated is unstable, However, some of the gas to be treated did not only pass through the dust collection area, but also passed through the non-dust collection area, which had a marked tendency to reduce the dust collection rate. Furthermore, the disadvantage that dust in the gas to be treated that enters the non-dust collecting area has an adverse effect on the mechanical drive mechanism cannot be ignored. In order to solve the above problems, measures such as installing a rectifying plate at the entrance of the moving electrode type electrostatic precipitator or increasing the effective volume of the dust collection area can be considered, but these measures are Although it causes an increase in equipment costs, sufficient effects cannot be expected.

Furthermore, as a countermeasure against high-resistance dust, the electrostatic precipitator disclosed in Japanese Patent Application Laid-Open No. 50-659 discloses a wet-type electrostatic precipitator in which a water spray nozzle is installed in the front fixed precipitator. ing.

However, although such wet dust collectors are effective to a certain extent as a countermeasure against high-resistance dust, they require a water spray nozzle, and the adhesive force of the dust increases.
There is a problem in that special measures such as washing with water are required to remove dust from the moving electrode of the stage. SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic precipitator that solves the above-mentioned drawbacks of the prior art and efficiently collects a gas to be processed containing high-resistance dust.

In order to achieve the above object, the electrostatic precipitator according to the present invention has a front-stage electrostatic precipitator having a fixed flat plate type dust-collecting electrode and a rear-stage electrostatic precipitator having a moving electrode type dust-collecting electrode. It is characterized by being provided continuously within the casing. By adopting the above configuration, the gas to be treated containing high-resistance dust is first roughly removed and rectified in a pre-stage electrostatic precipitator, where a considerable amount of the contained dust is roughly removed and then sent to the latter-stage electrostatic precipitator. In the second stage electrostatic precipitator, the gas to be processed stably passes through the dust collection area without intruding into the non-dust collection area, and high resistance dust that is difficult to collect in the first stage electrostatic precipitator is also removed. Dust can be collected efficiently, and the entire device can perform stable and efficient electrostatic collection.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a casing 1 has an inlet flue 2 at one end,
An outlet flue 3 is provided at the other end. Further, a front-stage electrostatic precipitator 10 is continuously provided on the side of the inlet flue 2 in the casing 1, and a rear-stage electrostatic precipitator is continuously provided on the side of the outlet flue 3. The pre-stage electrostatic precipitator 10 includes a plurality of fixed flat plate type dust collecting electrodes 11 (hereinafter sometimes simply referred to as dust collecting electrodes) arranged at predetermined intervals in parallel to the flow direction of the gas to be treated. and a plurality of linear discharge electrodes 12 arranged opposite to these dust collection electrodes 11. The upper end of the discharge electrode 12 is supported by a discharge electrode support member 13, and the discharge electrode support member 1
3 is supported by a suspension beam 14, and this suspension beam 14 is supported by the casing 1 via an insulator 15. Further, a weight 16 is attached to the lower end of each discharge electrode 12, and thereby each discharge electrode 12 is kept under tension. Further, a pre-stage hopper 17 that is integrated with the casing 1 is provided below the pre-stage electrostatic precipitator 10 . The latter stage electrostatic precipitator 20 includes a plurality of moving electrode type dust collecting electrodes 21 (hereinafter sometimes simply referred to as moving electrodes) arranged at predetermined intervals in parallel to the flow direction of the gas to be treated.

) and a plurality of linear discharge electrodes 22 arranged opposite to these moving electrodes 21. Like the discharge electrode 12, the discharge electrode 22 is supported by a discharge electrode support member 23, a suspension beam 24, and an insulating cloth 25, and is tensioned by a weight 26. Further, below the latter stage electrostatic precipitator 20, a latter stage hopper 27 which is integral with the casing 1 is provided. The movable electrode 21 is divided in the horizontal direction at a constant pitch, and each divided movable electrode 21 is a pair of endless cables that orbit between a pair of main driving wheels 28 and a pair of driven wheels 29 connected to a drive device. 30, and as the endless cable 30 moves, it rotates between the dust collection area and the non-dust collection area. A moving electrode 21, a pair of main driving wheels 28, a pair of driven wheels 29, a main driving wheel 28 and a driven wheel 2
A pair of endless cables 30 stretched between the two electrodes 9 constitute a dust collecting electrode plate moving device, and a plurality of these dust collecting electrode plate moving devices are provided in parallel. In the figure, the part where the discharge electrode 21 is arranged is a dust collection area, and the area above and below it forms a non-dust collection area. A dust removal device 31 is provided at a position where the moving electrode 21 passes through the non-dust collection area below. In order to reliably scrape off the dust collected and deposited on the moving electrode 21 in the dust collection area, the dust removing device 31 usually uses a rotating wire brush or the like that covers the entire length of the moving electrode 21.

Next, the operation of this embodiment will be explained.

The gas to be treated containing high-resistance dust is introduced into the pre-stage electrostatic precipitator 10 from the inlet flue 2.
0, a considerable amount of the included dust is collected on the dust collecting electrode 11 by the corona current based on the high voltage applied between the discharge electrode 12 and the dust collecting electrode 11.

The dust deposited on the dust collection electrode 11 is intermittently dropped into the front hopper 17 by a hammering device (not shown), and is discharged from the system by a dust discharge device (t) not shown. The gas to be treated, from which a considerable amount of dust has been collected in the first-stage electrostatic precipitator, is subsequently introduced into the second-stage electrostatic precipitator 20 . In this latter-stage electrostatic precipitator 20 as well, dust in the gas to be treated is collected on the moving electrode 21 by the corona current in the same manner as described above. The collected dust moves to the lower non-dust collection area together with the moving electrode 21, is peeled off from the moving electrode 21 by the dust removal device 31, passes through the rear hopper 27, and is removed from the system by a dust discharge device (not shown). be discharged. The moving period in which the moving electrode 21 moves back and forth between the dust collecting area and the non-dust collecting area is selected within a range that does not cause a reverse ionization phenomenon even if high resistance dust in the gas to be treated is collected and deposited on the moving electrode 21. There is. Therefore, high-resistance dust in the gas to be processed, which could not be sufficiently collected by the front-stage electrostatic precipitator 10, can be almost completely collected by the rear-stage electrostatic precipitator 20. What is also worth mentioning is that the rear-stage electrostatic precipitator 20 is provided immediately after the front-stage electrostatic precipitator 10 without any intervening duct, so in a moving electrode type electrostatic precipitator, this is not possible. It is possible to prevent instability of operation and decrease in dust collection rate due to excessive flow and drift, which have been difficult to take measures against. That is,
Pre-stage electrostatic precipitator 1 having a fixed flat plate type precipitate electrode 11
0 has a function of roughly removing dust in the gas to be treated by electrostatic precipitator, and also has a function of rectifying the gas to be treated with respect to the subsequent electrostatic precipitator 20. Therefore, the gas to be treated passes through the dust collection region of the rear electrostatic precipitator in a rectified state shown by the dotted line A, and stable and efficient electrostatic precipitate can be performed in the latter electrostatic precipitator 20. According to a trial calculation by the present inventors, compared to a conventional technology in which a fixed flat plate type electrostatic precipitator and a moving electrode type electrostatic precipitator were connected via a duct, the device according to the present invention It is possible to reduce the outlet dust concentration by about 20%, and when securing the same dust collection rate, it is possible to reduce the equipment cost by about 10%. FIG. 2 shows a model of another embodiment of the present invention.

In FIG. 2, the casing 1 is provided with a front-stage electrostatic precipitator 10 having two lines of fixed flat plate type dust-collecting electrodes 11 and a rear-stage electrostatic precipitator 20 having two lines of moving-electrode type dust-collecting electrodes 21. ing. According to this embodiment, even if the inlet dust concentration of the process gas is extremely high, the outlet dust concentration of the process gas can be kept low. The present invention is not limited to the embodiment shown in FIG. 1 or FIG. 2, and at least one of the electrostatic precipitators may be configured in a plurality of series. Further, it is sufficient that the front-stage electrostatic precipitator and the rear-stage electrostatic precipitator are substantially continuous, and for example, a rectifying plate for the gas to be treated may be provided between them.
As described above, according to the present invention, it is possible to stably and efficiently electrostatically collect a gas to be processed containing high resistance and dust, and it is also economical and requires less installation space. We can provide dust equipment.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the invention, and FIG. 2 is a model diagram showing another embodiment of the invention. 1...Casing, 2...Inlet flue,
3...Exit flue, 10...Pre-stage electric dust collection section, 11...Fixed flat plate type dust collection electrode, 20
......Late stage electric dust collecting section, 21...Moving electrode type dust collecting electrode.

Claims (1)

[Claims] 1. The first stage dry type electrostatic precipitator and the second stage dry type electrostatic precipitator are provided in succession in the same casing, the first stage dry type electrostatic precipitator is composed of a fixed flat plate type dust collection electrode, and the second stage dry type electrostatic precipitator is A pair of main driving wheels arranged at a predetermined distance above and rotated by a drive source, a pair of driven wheels arranged below the main driving wheels corresponding to the main driving wheels, and a tension between the main driving wheels and the driven wheels. and a pair of endless cables whose longitudinal direction is arranged parallel to the gas flow and are arranged at a predetermined interval in the vertical direction between the pair of endless cables, and the center portions of both ends are fixed to the endless cables. A plurality of dust collection electrode plate moving devices each having a plurality of rectangular dust collection electrode plates that move together with an endless cable are provided in parallel, and a central position between the plurality of dust collection electrode plate rows configured in the vertical direction is provided. An electrostatic precipitator characterized in that a discharge electrode is provided to form a dust collection area.