JPH08196939A - Prevention of hunting of concentration of soot at outlet of electric precipitator - Google Patents

Abstract

PURPOSE: To stably control an electric precipitator by calculating and setting charge quantity or a charge rate so that the concn. of soot enters blind zone width. CONSTITUTION: A soot densitometer 3 is arranged to the outlet flue 2 of an electric precipitator 1 to detect the amt. of soot in exhaust gas and the detection value is inputted to a charge control unit 6' as a soot concn. signal 4 and an alarm signal 5 is also inputted thereto in order to check the reliability of the signal. The signal wire 7' from the charge control unit 6' to a DC high voltage power supply device 8' is set to a serial transmission system in such a manner as to be able to set a charge rate linearly. In the charge control unit 6', the outlet soot concn. signal 4 of the electric precipitator 1 is read to calculate an average value at every definite cycle and the charge of the electric precipitator 1, that is, the charge rate of the DC high voltage power supply device 8' is stepwise controlled so that the average value enters a preset range (blind zone width). By this constitution, it is judged that the concn. of soot is hunted outside blind zone width.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dust concentration hunting prevention method applied to charge control of an electrostatic precipitator.

[0002]

2. Description of the Related Art FIG. 4 shows a schematic configuration of a charge control system for an electrostatic precipitator. In this system, a soot concentration meter 3 is installed at the outlet of the electrostatic precipitator 1 (hereinafter abbreviated as “EP”), the amount of soot in the exhaust gas of the EP outlet flue 2 is detected using the soot concentration meter 3, and the charge controller 6 Dust concentration signal 4 that correlates with quantity
By inputting, the DC high voltage power supply 8 (hereinafter abbreviated as PP) charge amount of DC high voltage power supply or intermittent charging so that the amount of dust in the outlet of EP1 falls within a preset range (dead band width). Rate is automatically set by the charge control device 6, and the P.P. P8 is discharge electrode 9
Voltage and current are supplied to. Here, the dust concentration alarm signal 5 is input to the charge control device 6 in order to improve the reliability of the dust concentration signal 4, and is configured to stop the charge control when the dust concentration meter 3 fails. It is a thing.

[0003]

However, in the above system, the charge control device 6 to the P.P. Since the setting of the charge amount or charge rate to P8 is performed by hard wired (H / W), these settings can be made only step by step, and the dust concentration may hunt across the dead zone. Therefore, the detected dust concentration signal is not stable, and the control of the DC high voltage applied to the discharge electrode in the electrostatic precipitator is unstable. Therefore, the present invention provides a method for preventing hunting of dust concentration at the outlet of an electric dust collector, which solves the problems of the conventional device and enables stable control of the dust collector.

[0004]

Therefore, according to the present invention, an electrostatic precipitator, a DC high-voltage power supply device for applying a high DC voltage to the electrostatic precipitator, and an outlet dust amount of the electrostatic precipitator are detected. The soot and dust concentration meter and the soot and dust concentration signal output from the soot and dust concentration meter are processed, and the DC high-voltage power supply device is set with the charge amount of the DC high voltage to be supplied to the electrostatic precipitator or the charge rate of intermittent charge. In equipment equipped with a charge control device for commanding, serial transfer is performed so that the charge amount or charge rate from the charge control device to the DC high-voltage power supply device becomes linear, and when the dust concentration hunts, the same dust concentration Is to calculate and set the charge amount or charge rate so as to be within the dead zone, and this is used as a means for solving the problem.

[0005]

In the EP (electrostatic precipitator) charge control according to the present invention, when the EP exit dust concentration starts to hunt around the dead band, the dust concentration below the detected value and the charge amount or charge rate at that time. Then, based on the dust concentration above the detected value and the charge amount or charge rate at that time, calculate the charge amount or charge rate within which the dust concentration falls within the dead band width, and serially transmit the signal line 7 even if the calculated result is an odd value. P.C. It can be set to P (DC high voltage power supply). As a result, the dust concentration falls within the dead zone. If the dust concentration is out of the dead band width, the calculated or set charge amount or charge rate is finely adjusted so that it falls within the dead band width.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of an EP charge control system of the present invention, and FIG. 2 is a flow chart for explaining the present invention. FIG.
In the above, a dust concentration meter 3 is installed in the outlet flue 2 of the electrostatic precipitator (EP) 1, and the amount of dust in the exhaust gas is detected by this, and the dust concentration signal is sent to the charge control device 6'having the function of the present invention. 4 and the alarm signal 5 is input for the purpose of checking the reliability of the signal. Further, the signal line 7'from the charge control device 6'to the DC high-voltage power supply device (PP) 8'is serially transmitted (SI / O) so that the charge rate can be set linearly. In the above configuration, in the charge control device 6 ', the outlet dust concentration signal 4 of the EP1 is read and an average value is calculated at every constant cycle. Charge, ie P. The charge rate of P8 'is changed stepwise (for example, 1/1, 1/5, 1/1
1, 1/21, 1/31, 1/61, 1/121, 1/241).
As a result, when the charge rate and the dust concentration have the following relationship, it is determined that the dust concentration is hunting across the dead zone.

## EQU1 ## Rc = Rc ₂ = Rc ₄

SN <SO ₂ Rc: Current charge rate Rc ₂ : Charge rate before 2 control cycles Rc ₄ : 4 Charge rate before 4 control cycles SN: Soot concentration average value (%) SO at the end of the current control cycle ₂ : Lower limit of dead band width (%) If it is determined that the dust concentration is hunting, determine the next charge rate from the following formula.

(Equation 3) Solving the above equation,

[Equation 4] Becomes Rc ′: Next charge rate value Rc ₁ : 1 Charge rate before control cycle SN ₁ : 1 Average dust concentration before control cycle Here, the logarithmic precision is used in the calculation in the charge control device 6 ′ to use the normal equation. This is to prevent it.

As shown in FIG. 3, in the DC high-voltage power supply device 8 ', in order to obtain the subdivided timing of the power adjustment, the charge amount or charge rate command signal 7'is used. The charging rate Rc ′ calculated by Equation 4 is obtained by charging the battery once every five half cycles. When the charge rate is hunting, the charge rate between stepwise charge rates is calculated. For example, when the value calculated by Equation 4 is an odd value such as 1 / 5.3, the actual charge rate is calculated. The rate will be chosen to be 1/5 or 1/6, but it will be rounded up to choose 1/5, which reduces soot and dust. As a result, the electric power obtained by converting the single-phase alternating current power supply into direct current by the thyristor is charged at the timing set by the charging rate command signal 7 ', transformed, rectified and applied to the discharge electrode 9. If the dust concentration does not reach the dead zone as a result of being charged at the determined charge rate, the charge rate is finely adjusted.
For example, when the calculated charge rate is 1/171, it is 1 after fine adjustment.
/ 173. The above control is shown in the flowchart of FIG. In the flow chart, FX means a charge rate hunting flav. It means that hunting occurs when FX = 1 and no hunting occurs when FX = 0.

[0008]

As described in detail above, according to the present invention,
In the conventional charge control system of the electrostatic precipitator, even if there is no charge rate that makes the dust concentration within the dead zone, the charge rate is controlled to put the dust concentration in the dead zone, which causes hunting of the dust concentration. On the other hand, since a halfway charge rate can be set in the DC high-voltage power supply device by serial transmission, hunting of dust concentration can be suppressed. Especially at a low charge rate, if the charge rate is changed stepwise, the difference in the dust concentration becomes large, and by eliminating the hunting width of the detected dust concentration becoming large,
A stable control power can be applied to the discharge electrode in the dust collector to enable more stable dust collection control.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram according to an embodiment of the present invention.

FIG. 2 is a flow chart for explaining the operation of the present invention.

FIG. 3 is a circuit configuration diagram of a power supply device of the present invention.

FIG. 4 is also a schematic configuration diagram of a conventional charge control system.

[Explanation of symbols]

 1 Electrostatic precipitator 2 Electrostatic precipitator outlet flue 3 Soot dust concentration meter 4 Soot dust concentration signal 5 Soot dust concentration meter alarm signal 6'Charge control device 7'Charge amount or charge rate command signal 8'DC high voltage power supply device 9 Discharge electrode

Claims (1)

[Claims] 1. An electrostatic precipitator and a DC high-voltage power supply for applying a high DC voltage to the electrostatic precipitator, a dust concentration meter for detecting the amount of soot dust at the outlet of the electrostatic precipitator, and an output by the dust concentration meter In a facility equipped with a charge control device that processes a soot dust concentration signal to be generated and instructs the DC high-voltage power supply device to set the charge amount of the DC high voltage supplied to the electrostatic precipitator or the charge rate of intermittent charge. Serial transfer is performed so that the setting of the charge amount or charge rate from the charge control device to the DC high-voltage power supply device becomes linear, and when the dust concentration hunts, the charge amount is set so that the dust concentration falls within the dead zone. Alternatively, a method for preventing hunting of soot and dust concentration at the outlet of an electrostatic precipitator characterized by calculating and setting a charge rate.