JPS6034754A - Electric dust collecting apparatus - Google Patents

Abstract

PURPOSE:To obtain a dust collector requiring low operation cost and having high electrode cleaning effect by providing a detecting circuit for overvoltage and spark discharge and a charge controlling device to the electric dust collecting apparatus, enabling control of stopping of charge within a specified time range. CONSTITUTION:At least either one of overvoltage or spark discharge between electrodes is detected by a detecting circuit 18 and a charge stopping signal is fed when the number of detection exceeds specifically set value. Such charge control device 19 is installed. The charge stopping signal is fed to an interlock circuit 23, and the charge is stopped within a range of specifically set time. By this constitution, high cleaning effect of electrodes is obtd. and the dust collecting performance is improved. Moreover, the operation cost is saved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to an electrostatic precipitator characterized by electrode cleaning means.

Generally, in order to operate an electrostatic precipitator (hereinafter referred to as EP) with high efficiency, it is necessary to apply as high a voltage as possible between the electrodes (between the collecting electrode and the discharge electrode). However, simply increasing the voltage between the electrodes will cause spark discharge to occur as well as corona discharge, which is necessary for electrostatic precipitate action. Furthermore, if the interelectrode voltage is lowered, spark discharge will no longer occur, but corona discharge will also not occur efficiently, resulting in a decrease in dust collection efficiency.

That is, the dust collection efficiency is maximized when spark discharge occurs under appropriate conditions. The voltage at which this spark discharge occurs depends on the operating state of the EP and changes from moment to moment. Therefore, in order to keep the frequency of spark discharge constant even if the operating state changes, the voltage must be constantly adjusted. There is a need.

FIG. 1 shows an example of a conventional EP constant power supply configuration, in which a commercial DC high voltage is obtained from a commercial AC power supply 11 via a Zyristor 12, a high voltage transformer 13, a high voltage rectifier 14, and a reactor 15. Then, this high DC voltage is applied between the dust collecting electrode 16 and the discharge electrode 162 of the electrode section 16 .

The DC voltage applied to the electrode section 16 is controlled by a charge control circuit 17.
7 is supplied with a detection signal from a detection circuit 18 provided in the electrode section 16.

This detection circuit 18 detects the voltage applied to the electrode section 16, the frequency of sparks, etc., and the control circuit 17
generates a pulse signal having a phase angle α with respect to the commercial AC power supply 11, controls the conduction angle of the thyristor 12, and controls the voltage and current supplied to the electrode section 16.

However, in such an EP, as shown in Figure 2, the discharge characteristics change over time to CB compared to the initial discharge characteristics [A]
) and become inferior. This is because dust adheres to the electrode portion 16 during charging, reducing the discharge effect.

For this reason, although not particularly shown in the figure, a hammering device is formed on each electrode 161 and 162 as an electrode cleaning device for removing dust and the like attached to the electrode portion 16. This hammering device is a mechanical hammer that combines an electric motor and a speed reducer, or an electromagnetic hammer that uses a magnet.
The dust collecting electrode 161 is hammered intermittently to peel off the attached dust. For example, as shown in Figure 3,
When the EP charging voltage is supplied, the dust collecting pole hammering device and the discharge electrode hammering device are driven intermittently, and the dust collecting pole 1
This is to remove dust attached to the discharge electrode 61 and the discharge electrode 162.

However, even when hammering is performed with a high voltage applied to the electrode part 16, since the high voltage is still applied to the electrode part 16, the dust adhering to the dust collection electrode 16 and the discharge electrode 162 may be removed. cannot be efficiently peeled off from the electrode, and the cleaning effect of hammering cannot be fully exerted. This phenomenon of decrease in corona current with respect to the same charge voltage accelerates the adhesion of dust on the discharge electrode 162 and further deteriorates the discharge characteristics, repeating a vicious cycle, which has the drawback of gradually decreasing the dust collection performance. had.

This invention was made in view of the above-mentioned circumstances, and includes a detection circuit that detects the occurrence of at least one of overvoltage between electrodes and C spark discharge and counts the number of occurrences, and a detection circuit that specifies the number of times of detection by this detection circuit. The device is equipped with a charge control device that supplies a charge stop signal when the set value is exceeded, and the control device controls the charge stop within a specified time range. The purpose is to provide an electrostatic precipitator with excellent dust removal performance.

In this invention, when charging is manually stopped for a few seconds while a conventional EP is in operation, the dust adhering to the dust collecting electrode and the discharge electrode peels off and falls, and the electrode hammering device is also superior. This method takes advantage of the fact that the cleaning effect has been obtained, and as shown in Figure 4, it automatically stops charging at a certain number of overvoltages or spark frequency, and removes the electrode without using a hammering device. It cleans the water.

The present invention will be described in detail below with reference to the drawings. EP is composed of multiple dust collection chambers, each equipped with an independent electrode section, arranged in series in the direction of air flow, and Figure 5 corresponds to one of the dust collection chambers. I'll show you the parts that will work. That is, in the same way as shown in FIG.
6 converts the voltage into a DC high voltage and supplies it to the electrode section 16. Based on the voltage applied to the electrode section 16,
The detection circuit 18 detects the occurrence of overvoltage and spark discharge, and sends a signal to the charge control circuit 19. This control circuit 1
Reference numeral 9 uses an overvoltage count circuit 20 to count when overvoltage is detected, and a spark once count circuit 21 to count when spark discharge occurrence is detected. A predetermined number of overvoltages is set for the overvoltage number counting circuit 20 by a setter 22, and when the counted number of overvoltage times exceeds the set number, the interlock circuit 20
A charging stop signal is sent to 3. Similarly, when the spark frequency counting circuit 21 exceeds the spark frequency set by the setting device 24, a charging stop signal is sent to the interlock circuit 23.

The interlock circuit 23 is used to prevent multiple dust collection chambers in the EP from stopping charging at the same time and deteriorating dust collection performance. When a stop signal is input and a charging stop signal from another dust collection chamber is not input, a charging stop signal is sent to the control circuit 19. In accordance with this stop signal, the control circuit 19 shuts off the gate of the thyristor 12 for a predetermined period of time to stop charging the electrode section 16.

In addition, in the dust collection chamber on the downstream side that is arranged in series,
In particular, in order to minimize changes in dust collection performance, the intermittent charging control circuit 25 is connected to the interlock circuit 23 and the control circuit 1.
It is effective to perform intermittent charging control in which the gate is shut off a plurality of times in response to charging stops as described above.

As described above, according to the present invention, there is provided a detection circuit that detects the occurrence of at least one of overvoltage and spark discharge between electrodes and counts the number of occurrences thereof, and a detection circuit that detects the occurrence of at least one of overvoltage and spark discharge between electrodes, and a detection circuit that detects the occurrence of at least one of overvoltage and spark discharge between electrodes, and a detection circuit that detects the occurrence of at least one of overvoltage and spark discharge between electrodes. The charging control device is provided with a charging stop signal to which a charging stop signal is supplied in a state in which charging is stopped, and the charging stop is controlled within a time range specified by this control device.
It is possible to provide an electrostatic precipitator with a simple configuration, low equipment costs and low operating costs, and a high electrode cleaning effect with excellent dust collection performance.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the configuration of the power supply of a conventional electrostatic precipitator, Figure 2 is a diagram showing the discharge characteristics of the device in Figure 1, and Figure 3 is a diagram showing the
FIG. 4 is a timing chart explaining the charging state of an electrostatic precipitator according to an embodiment of the present invention, and FIG. 5 is a timing chart explaining the operation of the charging and hammering device shown in FIG. FIG. 11... AC power supply, 12... Thyristor, 13...
・High voltage transformer, 14... High voltage rectifier, 15... Reactor, 16... Electrode part, 161... Dust collection electrode, 162
... Discharge electrode, 17... Charge control circuit, 18... Detection circuit, 19... Charge control circuit, 2o... Overvoltage frequency counting circuit, 21... Spark frequency counting circuit, 22...・
Overvoltage frequency setting device, 23...interlock circuit, 2
4...Spark frequency setting device, 25...Intermittent charging control circuit.

Claims (1)

[Claims] A detection circuit that detects the occurrence of at least one of overvoltage and spark discharge between electrodes and counts the number of occurrences thereof, and a charging circuit that supplies a charging stop signal when the number of detections by this detection circuit exceeds a specified set value. What is claimed is: 1. An electrostatic precipitator comprising: a control device, and configured to control charging stoppage within a time range specified by the control device.