JPS6138645A - Operating method of electrical dust precipitator - Google Patents

Abstract

PURPOSE:To increase the dust collecting performance in the operating method of an electrical dust precipitator by detecting the voltage during charge quiescence wherein the intermittent charge operation is performed and maintaining the voltage by a thyristor ignition phase angle control signal when the detected voltage becomes lower than the preset voltage. CONSTITUTION:The minimum value of voltage of an electrical dust precipitator (EP) during the intermittent charge quiescent time is preset in a setter 29 and D is inputted to a controlling device 25. Both EP current signal B obtain by detecting the primary current of a transformer 22 with a detector 26 and EP voltage signal C obtained by detecting the EP voltage with a detector 27 are inputted to the controlling device as the feedback signal and the ignition phase angle control signal A is outputted to a thyristor 21. Thereby, AC electric power regulation is performed and power supply is performed to a discharge pole 24 of EP via a rectifier 23 and a DC reactor 28.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention improves the dust collection performance by preventing a drop in the average voltage of an electrostatic precipitator (hereinafter abbreviated as EP) for coal-fired power plants or iron ore sintering machines. E applicable to intermittent charging operation type EP that aims to improve
This is related to the driving method of P.

[Conventional technology]

In general, EP high-voltage power supplies conventionally adjust commercial AC power by controlling the firing phase angle of a thyristor 1, step up the voltage with a transformer 2, and convert it into a high DC voltage with a rectifier 3, as shown in Fig. 3, for example. , the discharge electrode 4 of the EP via the DC reactor 8
is supplying power. The control device 5 inputs the primary current of the transformer 2 as an EP current signal color detected by a detector 6, and the EPt pressure as an EP voltage signal sound feedback signal detected by a detector 7, In order to achieve control such that the current is constant and spark discharge occurring within the EP occurs at a constant frequency, a firing phase angle control signal 2 is output to the thyristor 1, and as a result, the thyristor output ( The AC power supplied to the transformer 2 is controlled as shown in FIG. 4, and the charging voltage and current of the EP are controlled.

On the other hand, as shown in Fig. 5 (AI), the collected dust layer IO in Ep
(formed on the EP dust collecting electrode 11), if the specific electrical resistance value of the collected dust exceeds 1011 to 1012 Ω/flaw, the dust layer voltage Vd of the dust collecting electrode becomes extremely high, and the dust inside the dust layer increases. dielectric breakdown, a so-called reverse ionization phenomenon, occurs, resulting in a significant drop in dust collection performance. In GPs for coal sintering machines or iron ore sintering machines, the collected dust exhibits high electrical resistance, and the EP capacity is increased to compensate for the above-mentioned low dust collection performance. The conventional intermittent charging method is
As shown in Fig. 7 (N), the phase angle control signal 2 sent to the thyristor 1 is set at the same time as the thyristor firing time (gp charging time 2T,) and the same OFF time (EPP power rest time: T,) c7
) When the frequency of the commercial frequency (50/60H2) or the low voltage side is modulated by an inverter, it is an intermittent signal synchronized with the frequency (for example, 25 to 1 KHz), as shown in FIG. 7(B).

By applying the EP voltage and current shown in (C) to the EP, (the same signal waveform due to the charging method of energization is generated at the 0th pupil)
, (B), (shown in Q) As shown in FIG.
) After the rest time T, the dust layer voltage Vd is sufficiently low and then it is charged again (the thyristor is turned on), which has the effect of suppressing the reverse ionization phenomenon 1 mentioned above (therefore improving the dust collection performance). [Problems to be solved by the invention] However, in the intermittent charging method described above, if the pause time is longer than the charging time, the F and P@ pressures drop, the average voltage decreases, and the dust collection performance deteriorates. There was a problem that the performance decreased.

The present invention was proposed in view of the above circumstances, and in an intermittent charging method that repeats intermittent fogging, charging of EP, and rest, the present invention prevents the minimum value VB of the EP voltage from decreasing during the rest time, and prevents the corona starting voltage from decreasing. Letting VC be vc=t=vn or,
The object of the present invention is to provide an EP operating method that improves the dust collection performance of the EP by adjusting VB to a level slightly higher than VC.

[Means for solving problems]

The method of operating an IP according to the present invention is an EP that is operated intermittently.
detects the EP voltage during the charging pause time, and when it becomes lower than the set voltage, increases the thyristor firing phase angle control signal to maintain the GP voltage at or above the set voltage during the charging pause time. This is a characteristic feature.

[Effect]

According to the method of the present invention, the minimum value VB of the EP voltage during the charging rest time in the intermittent charging method is detected, and the EP current is supplied during the rest time in order to adjust VB+VC or VB +VC+a (a (vc) 64). However, if EPtfi is controlled so that the above VB is achieved, E
In order to prevent the minimum value VB of the P voltage from decreasing, the above control is performed, thereby preventing a decrease in the average voltage of EP in the intermittent charging method, improving the EPP dust performance, and solving the above-mentioned conventional problems. This is what I did to get it.

〔Example〕

An embodiment of the invention will now be described in detail with reference to the accompanying drawings.

Explain.

FIG. 1 is a diagram showing the configuration of an embodiment of the apparatus used to carry out the method of the present invention, and FIG. 2 (/k) (1 (c+ is the thyristor firing phase angle control signal in FIG. 1, E
It is each operation waveform chart of P voltage and current.

As shown in FIG. 1, AC power is adjusted by controlling the firing phase angle of the thyristor 21, and the transformer 22 boosts the voltage, and the rectifier 23 converts it into a high DC voltage. Power is supplied to the electrode 24. Is the control device R25 a detector for the primary current of the transformer 22? According to 6,
The gp voltage signal C detected by the detector 27 is inputted as a feedback signal to the detected EP current signal color EP voltage, and the firing phase angle control signal A is outputted to the thyristor 21. The setting device 29 sets the EP during the intermittent charging pause time.
The minimum value VB of the voltage is set, and the setting signal thereof is input to the control device 25.

To explain the operation of the embodiment of the present invention, the setter 29 sets the EP voltage minimum value VB during the intermittent charging pause time to be equal to the corona starting voltage VC, or
Set B=VC+α. Therefore, α is α (VC), and the specific value is determined by actual operation.

During intermittent charging (this control is not performed during normal continuous charging shown in FIGS. 6(A), 6(B), and 6C)), at the pause time, the EP voltage vnp detected by the detector 27 and the above-mentioned 1) If VRP≧VB, as shown in FIG. .

2) If vBp < VB, the difference VB -V
Thyristor firing phase angle control signal 2 at a rate according to BP
increase. This amount of increase shall be determined based on actual operation.

As a result, the thyristor firing phase angle control signal 2 is as shown in Fig. 2 (
Al is controlled as shown in Figure 2 (B), and the EP voltage and current are controlled as shown in Figure 2 (B
), (As shown in C1, the minimum value of the EP voltage VFIP during the intermittent charging pause time is limited by VB and controlled near Vn.

〔Effect of the invention〕

As described above, according to the method of the present invention, it is possible to reduce the drop in the EP voltage during the charging pause time in intermittent charging, thereby increasing the EP average voltage during intermittent charging and improving the EP dust collection performance. This will bring about the same effect.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of a device used to carry out the method of the present invention, and FIG. 2 (A) (Bl (C)) shows the thyristor firing phase angle control signal in FIG.
The operation waveform diagrams of the EP voltage and current, and FIGS. 3 to 7 are diagrams for explaining conventional examples, respectively. 21...Thyristor, 25...Control device, 26゜2
7...Detector, 29...Setter, A...Ignition phase angle control signal, B...EP current signal, C...EP voltage signal, D...setting signal. Applicant sub-agent Patent attorney Takehiko Suzue Figure 1 Figure 2 (A) Figure 3 A, Ct source Figure 4 system [No. 4 2 Figure 5 (A) Figure 6 (A) CB) rP Figure 7 (A) (B) Punishment 1

Claims (1)

[Claims] The electrostatic precipitator voltage during the charging pause time of an electrostatic precipitator that is operated intermittently is detected, and when it becomes lower than the set voltage, the thyristor firing phase angle control signal is increased and the voltage is increased during the charging pause time. A method of operating an electrostatic precipitator, characterized by maintaining the electrostatic precipitator voltage at or above a set voltage.