JP2022154007A - Electric dust collector and operation method thereof - Google Patents

Abstract

To provide an electric dust collector which is a wet type, and can further enhancing a power saving effect while maintaining dust collection efficiency during an operation by intermittent charge.SOLUTION: An electric dust collector 10 comprises: an electric dust collector main body 1; a power source 2 which has, as a switching element, an insulation gate bipolar transistor (IGBT); an intermittent charge control unit 3; and a dust density meter 4 for measuring dust density of an exhaust gas discharged from the electric dust controller main body 1. The intermittent charge control unit 3 outputs a signal for instructing change of a combination of charge time and non-charge time, to a power source 2 so that the dust density of the exhaust gas measured by the dust density meter 4, is in a prescribed range of density.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electrostatic precipitator and an operating method of the electrostatic precipitator. More specifically, the present invention relates to a wet-type electrostatic precipitator that performs charging by intermittent charging as means for saving power, and a method of operating the same.

Conventionally, wet type electrostatic precipitators have been widely used for the purpose of collecting harmful dust from exhaust gas generated in waste incineration processes such as aluminum refining exhaust gas treatment (see Patent Documents 1 to 3).

In such a wet type electrostatic precipitator, as a general technique for improving the dust collection efficiency of dust containing heavy metals, the voltage between the dust collection electrode and the discharge electrode, that is, the voltage applied to the discharge electrode is increased to a certain voltage or more ( As an example, a method of applying a high voltage of 70 kV or higher is known. Then, as a means for saving power in such high-voltage operation, when the dust concentration of the exhaust gas to be treated temporarily decreases, the application to the discharge electrode is switched from continuous charging to intermittent charging. A method has been implemented (see U.S. Pat.

According to the operation method by intermittent charging described above, in the wet type electrostatic precipitator, the power saving effect can be enjoyed while maintaining the dust collection efficiency substantially. However, in the intermittent charging operation method, if the dust concentration in the exhaust gas to be treated suddenly increases for some reason, there is a risk that the dust collection efficiency will drop beyond the allowable range.

For this reason, conventionally, in the operation of wet type electrostatic precipitators, in order to avoid the above-mentioned risk, the charging time is sufficiently long in consideration of the safety margin for the combination of the charging time and the non-charging time during operation by intermittent charging. A lengthened combination was set for On the other hand, regarding the operation method of the wet type electrostatic precipitator, it is required to further optimize the combination of the charging time and the non-charging time during operation by intermittent charging to further improve the power saving effect. was

JP 2007-196159 A JP-A-2002-119889 Japanese Patent Publication No. 6-91965 Japanese Patent Application Laid-Open No. 2020-11208

SUMMARY OF THE INVENTION An object of the present invention is to further improve the power saving effect while maintaining the dust collection efficiency during operation by intermittent charging in a wet type electrostatic precipitator.

The inventor of the present invention uses a power supply for an electrostatic precipitator that performs intermittent charging as a power supply that includes an insulated gate bipolar transistor (IGBT) as a switching element (hereinafter also referred to as an "IGBT power supply"). The inventors have found that the above problems can be solved by feeding back the dust concentration of the power supply to the operation of the power supply to control the change in the combination of the charging time and the non-charging time, and have completed the present invention. Specifically, the present invention provides the following. An insulated gate bipolar transistor (IGBT) is a power switching element that uses a MOSFET for an input section and a bipolar transistor for an output section.

(1) an electric dust collector main body, a power supply including an insulated gate bipolar transistor (IGBT) as a switching element, an intermittent charging control device, and a dust concentration meter for measuring the dust concentration of the exhaust gas discharged from the electric dust collector main body; wherein the intermittent charging control device provides the power source with a combination of charging and non-charging times so that the dust concentration of the exhaust gas measured by the dust concentration meter remains within a predetermined concentration range. An electrostatic precipitator that outputs a signal indicating a change.

According to the invention of (1), in an electric dust collector that performs intermittent charging, the power saving effect can be further enhanced while maintaining the dust collection efficiency.

(2) The method of operating an electrostatic precipitator according to (1), wherein the minimum unit of change in the combination of the charging time and the non-charging time is 10 msec or less.

According to the invention of (2), by controlling the combination of the charging time and the non-charging time in extremely short time units, which could not be realized by the thyristor type power supply widely used in the past, The effect produced by the invention of (1) can be enjoyed as a more excellent effect.

(3) A method of operating an electrostatic precipitator, wherein the electrostatic precipitator includes an electrostatic precipitator main body, a power supply having an insulated gate bipolar transistor (IGBT) as a switching element, an intermittent charging control device, and an exhaust gas. and a dust concentration meter for measuring dust concentration, and the intermittent charging control device determines an appropriate combination of charging time and non-charging time according to fluctuations in the dust concentration of the exhaust gas measured by the dust concentration meter. A method of operating an electrostatic precipitator, wherein the combination of the charging time and the non-charging time is changed during operation of the electrostatic precipitator by instructing the power supply.

According to the invention of (3), the combination of the charging time and the non-charging time is appropriately switched while the operation of the device is continued without stopping the operation, so that the dust collection efficiency is improved in the electrostatic precipitator that performs intermittent charging. while maintaining the power saving effect.

(4) The method of operating an electrostatic precipitator according to (3), wherein the minimum unit of change in the combination of the charging time and the non-charging time is 10 msec or less.

According to the invention of (4), by controlling the combination of the charging time and the non-charging time in extremely short time units, which could not be realized by the thyristor type power supply widely used in the past, The effect produced by the invention of (3) can be enjoyed as a more excellent effect.

ADVANTAGE OF THE INVENTION According to this invention, a wet-type electrostatic precipitator can further improve the power saving effect while maintaining the dust collection efficiency at the time of operation by intermittent charging.

BRIEF DESCRIPTION OF THE DRAWINGS It is a front view which shows typically the structure of the electrostatic precipitator of this invention. It is a sectional view for electric precipitators of the present invention. 2(A) and 2(B) are cross-sectional views viewed from different directions substantially perpendicular to each other. FIG. 2 is an equivalent circuit diagram showing the circuit configuration of the power conversion circuit of the power source of the electrostatic precipitator of the present invention;

<Electric Precipitator>
An electrostatic precipitator 10, which is one embodiment of the present invention, is a wet electrostatic precipitator that collects harmful dust contained as fine particles in various types of exhaust gas. As shown in FIG. 1, the electrostatic precipitator 10 includes an electrostatic precipitator main body 1, an IGBT power source 2, an intermittent charging control device 3, and a dust concentration meter 4. It is composed by

The above-mentioned "power supply control system" that constitutes the electrostatic precipitator 10 reflects the information on the dust concentration of the treated exhaust gas measured by the dust concentration meter 4 in the operation of the intermittent charging control device 3, During the operation of the electrostatic precipitator 10, the operation of the IGBT power source 2 that performs intermittent charging is controlled.

[Electric dust collector body]
As shown in FIG. 2, the electrostatic precipitator body 1 that constitutes the electrostatic precipitator 10 includes an upper casing 11, a dust collection electrode 12 that also functions as a side casing, a lower casing 13, and a frame 14. ing. The upper casing 11, the dust collecting electrode 12, and the lower casing 13 are combined in that order from above to form a housing of the electrostatic precipitator main body 1. As shown in FIG. Also, the housing of the electrostatic precipitator main body 1 is usually installed at a predetermined distance above the ground by a frame 14 .

Inside the housing of the electrostatic precipitator main body 1, as shown in FIG. The upper grid 121, the dust collecting electrode 12, and the lower grid 122 are arranged in that order from above, separated from each other by a predetermined distance, and substantially parallel to each other in the horizontal direction. In addition, inside the housing of the main body 1 of the electric dust collector, a spray nozzle and a washing pipe are provided for washing away dust adhering to the dust collection electrode 12 .

A preferable example of the material of the casing of the electrostatic precipitator main body 1 is conductive FRP (Fiber Reinforced Plastic). Exhaust gas treated by the electrostatic precipitator 10 may contain so-called corrosive substances such as hydrofluoric acid and sulfurous acid gas in addition to harmful dust. For this reason, in recent years, conductive fiber-reinforced plastics have been adopted in place of conventional metal materials as materials for forming gas-contacting parts such as casings and dust collecting electrodes of electrostatic precipitators. By adopting FRP, corrosion resistance is mainly enhanced, and it is possible to manufacture at a lower cost than highly corrosion-resistant metal materials.

[Power control system]
A power supply 2 having an insulated gate bipolar transistor (IGBT) as a switching element, an intermittent charging control device 3, and a "power supply control system" comprising a dust concentration meter 4 is an electrostatic precipitator measured by the dust concentration meter 4. The dust concentration of the exhaust gas discharged from the main body 1 is fed back to the intermittent charging control device 3, and the combination of the charging time and the non-charging time in the power supply 2 that performs intermittent charging is controlled using a preset dust concentration threshold value as a target value. do.

In order to execute the above control, the "power supply control system" measures the above dust concentration in real time with the dust concentration meter 4 while the electrostatic precipitator 10 is in operation. Then, the intermittent charging control device 3 instructs the power supply 2 to change the combination of the charging time and the non-charging time so that the dust concentration of the exhaust gas stays within a predetermined concentration range set in advance. output a signal to

(power supply)
A power supply 2 that constitutes the "power supply control system" is a DC high voltage power supply that includes an insulated gate bipolar transistor (IGBT) as a switching element. As an example, the power supply 2 includes a DC high voltage generating section 2A and a DC high voltage input section 2B, as shown in FIG. A high negative DC voltage is applied from the power supply 2 to the electrode rod 123 constituting the discharge electrode of the electrostatic precipitator main body 1 .

In the DC high voltage generator 2A, a series of processes such as boosting and rectification are performed on the AC voltage supplied from the AC power supply (not shown in FIG. 2, AC power supply 25 in FIG. 3). Outputs a high voltage direct current obtained by

FIG. 3 shows an equivalent circuit of a power conversion circuit that constitutes the power supply 2. As shown in FIG. As shown in the figure, in the power conversion circuit C1, an AC power supply 25, an input-side rectifier 24, a switching element 23, a transformer 22, and an output-side rectifier 21 are sequentially connected from the input side to the output side. In the power conversion circuit C1, the switching element 23 is an insulated gate bipolar transistor (IGBT).

Further, in the power conversion circuit C1, for example, when the concentration of fine particles in the gas introduced into the main body 1 of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body 1 of the main body of the main body of the main body of the main body 1 of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body, for example, when the concentration of fine particles in the gas supplied to the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of the main body of being below a certain level, etc. A switching charging scheme switching means (not shown) is also provided.

As shown in FIG. 3, the power conversion circuit C1 further controls the operation of the power supply 2 according to the dust concentration of the treated exhaust gas discharged from the electrostatic precipitator main body 1 during operation by intermittent charging. An intermittent charging control device 3 is installed.

(Intermittent charging control device)
As described above, the intermittent charging control device 3 is configured by an information processing device having a function of controlling the combination of the charging time and the non-charging time in the power source 2, which is an "IGBT type power source", according to the dust concentration of the exhaust gas. be able to.

Specifically, the control of the operation of the power supply for the combination of the charging time and the non-charging time is performed by using the dust concentration of the exhaust gas measured by the dust concentration meter 4 as an input value and presetting this input value. This can be done by outputting to the power supply 2 a signal instructing to change the combination of the charging time and the non-charging time when the difference from the reference value obtained exceeds the threshold. The intermittent charging control device 3 can also be configured, for example, by adding the above functions by making necessary improvements to a general-purpose "control panel for the main body of an electrostatic precipitator" installed in an existing electrostatic precipitator. can do.

[Operation of electrostatic precipitator]
The basic operation and operating method of the electrostatic precipitator 10 having the above configuration will be described. In the electrostatic precipitator 10, the DC high voltage of the negative electrode generated from the DC high voltage generating section 2A (FIG. 2) is passed through the DC high voltage input section 2B (FIG. 2) as a DC high voltage to the discharge electrode ( applied to the electrode rod 123 and the discharge wire 124). Then, when the value of the DC high voltage rises, a negative corona discharge is generated between the discharge electrode and each side of the "chamber" of the dust collection electrode 12 surrounding it, and as a result, dust is discharged from the discharge electrode. Negative ions migrate in a direction toward each side of the "chamber" of pole 12 and an ionic wind is generated in the same direction.

Thus, in the electrostatic precipitator 10, the space around the dust collection electrode 12 becomes an ion space. Therefore, as shown in FIG. 2, when the exhaust gas G1 to be treated containing fine particles such as mist and dust is supplied to the lower part of the casing of the electrostatic precipitator and flows through the space around the dust collection electrode 12, negative ions The fine particles are charged by the collision of the particles. The charged fine particles adhere to the side surfaces of the dust collection electrode 12 . In this manner, the fine particles are removed from the exhaust gas G1 to be treated. The treated exhaust gas G2 from which fine particles have been removed is discharged from the upper portion of the housing of the electrostatic precipitator 10 .

The electrostatic precipitator 10 is operated by switching the charging method for the electrostatic precipitator main body 1 from continuous charging to intermittent charging when the dust concentration in the exhaust gas to be treated falls below a certain concentration.

(Control of intermittent charging)
[ The power supply control system controls the combination of the charging time and the non-charging time in the power supply 2 that performs intermittent charging so as to be an appropriate combination.

Here, in the thyristor-type power supply that has been widely used in the past, the setting of the combination of the charging time and the non-charging time is 20 ms, such as 20 ms, 40 ms, and 60 ms, due to the characteristics of the thyristor method. It was limited to setting in multiples of seconds. In addition, these set values must be set in advance before starting the operation of the electrostatic precipitator, and it is impossible to change the above combinations during operation.

On the other hand, in the electrostatic precipitator 10 provided with an "IGBT power supply" as the power supply 2, the switching element of the IGBT system operates at a high frequency. can easily be set to a minimum unit of 10 msec or less, and it is also possible to set a combination of the charging time and the non-charging time in 1 msec units. Similarly, the set time during operation can be freely set in arbitrary time units of 1 ms.

Therefore, the combination of the power supply 2, which is an "IGBT type power supply", and the intermittent charging control device 3 that controls the operation of the power supply 2 according to the dust concentration of the treated exhaust gas discharged from the main body 1 of the electrostatic precipitator, For example, during operation of the electrostatic precipitator 10 by intermittent charging, the combination of charging time and non-charging time can be changed to a more appropriate combination with extremely high degree of freedom and speed that cannot be achieved with other configurations. . Thus, in the electrostatic precipitator 10, the operation of the "power control system" realizes the maximum energy saving effect within a predetermined allowable dust concentration range.

EXAMPLES The present invention will be described in more detail below with reference to examples of test operations, but the present invention is not limited to the following examples.

(Comparative example: Thyristor power supply)
An electrostatic precipitator comprising an electrostatic precipitator body having the structure shown in FIG. 2 and a thyristor-type power supply was operated for 8 hours, and fluctuations in power consumption due to switching between continuous charging and intermittent charging were confirmed. In this electrostatic precipitator, the average dust concentration in the exhaust gas during continuous charging was 10 mg/Nm ³ and the power consumption was 591 kWh.

Subsequently, a test operation was performed for 8 hours by intermittent charging in the above electrostatic precipitator equipped with a thyristor power source. At this time, the combination of charging time and non-charging time was set to a fixed combination of 100 msec charging time and 80 msec non-charging time. In this test run, the power consumption was able to be reduced to 403 kWh while maintaining the average dust concentration at 10 mg/Nm ³ (8hr average) (see Table 1).

(Example: IGBT power supply)
In an electrostatic precipitator comprising an electrostatic precipitator body having the same configuration as the comparative example and an IGBT power source, the combination of charging time and non-charging time is controlled by feeding back the dust concentration of the exhaust gas in real time. maintained an average dust concentration of 10 mg/Nm ³ or less during operation. The power consumption at that time was able to be reduced to 296 kWh (see Table 1).

From the test results in Table 1 above, it can be seen that the present invention can further improve the power saving effect while maintaining the dust collection efficiency during intermittent charging operation in a wet type electrostatic precipitator.

1 Electric Dust Collector Main Body 11 Upper Casing 12 Dust Collection Electrode (Side Casing)
13 Lower casing 14 Frame 121 Upper grid 122 Lower grid 123 Electrode rod 124 Discharge wire 125 Weight 2 Power source 2A DC high voltage generator 2B DC high voltage input 3 Intermittent charging control device 4 Dust concentration meter 10 Electric dust collector 21 Output side Rectifier 22 Transformer 23 Switching element (IGBT)
24 Input-side rectifier 25 AC power supply C1 Power conversion circuit G1 Exhaust gas to be treated G2 Exhaust gas after treatment

Claims (4)

an electric dust collector body;
a power supply comprising an insulated gate bipolar transistor (IGBT) as a switching element;
an intermittent charging controller;
a dust concentration meter that measures the dust concentration of the exhaust gas discharged from the electrostatic precipitator main body,
The intermittent charging control device instructs the power source to change the combination of charging time and non-charging time so that the dust concentration of the exhaust gas measured by the dust concentration meter remains within a predetermined concentration range. output a signal to
Electrostatic precipitator. The minimum unit of the change width of the combination of the charging time and the non-charging time is 10 ms or less,
A method of operating the electrostatic precipitator according to claim 1. A method for operating an electrostatic precipitator,
The electrostatic precipitator,
an electric dust collector body;
a power supply comprising an insulated gate bipolar transistor (IGBT) as a switching element;
an intermittent charging controller;
a dust densitometer that measures the dust concentration of the exhaust gas,
The electrostatic precipitator is controlled by instructing the power supply by the intermittent charging control device to select an appropriate combination of charging time and non-charging time according to fluctuations in the dust concentration of the exhaust gas measured by the dust concentration meter. changing the combination of charging and uncharging times during operation of
A method of operating an electrostatic precipitator. The minimum unit of the change width of the combination of the charging time and the non-charging time is 10 ms or less,
A method of operating the electrostatic precipitator according to claim 3.

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