JPH034257B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an electrostatic precipitator.

As shown in the block diagram of FIG. 1, an electrostatic precipitator conventionally has a high-voltage power supply 2 that converts commercial power into a high-voltage DC voltage and supplies it to the electrostatic precipitator 1, and a high-voltage DC high-voltage generated by the high-voltage power supply 2. It is comprised of a control device 3 that generates a signal U to control the.

Therefore, the action of the control device 3 is, for example, to adjust the charging voltage, that is, the DC high voltage generated by the high voltage power source 2, so as to always maintain the maximum dust collection effect using a spark frequency control device built into it. In addition, in the case of a precipitator with little variation in characteristics, the charge voltage may be manually adjusted to a constant value.

However, with any of these methods, the charging voltage is conventionally adjusted to maintain the highest dust collection effect, and from the perspective of energy conservation, the dust collection efficiency is increased more than necessary, resulting in unnecessary waste. It may be consuming power.

Therefore, in order to avoid wasteful power consumption, a dust concentration meter 6 is provided at the outlet of the dust collector 1, as shown in the block diagram of FIG. By setting the control signal U to a certain value A as shown in Fig. 3A, and adjusting the magnitude of the charge voltage, an improved method can be considered in which the dust collection efficiency is not increased more than necessary and the power consumption is reduced. .

The present invention further advances this improved method, and as shown in FIG. 3B, the value of the control signal U is set to a constant value A.
The purpose is to provide an electrostatic precipitator that saves energy by changing pulse-like at an appropriate period and charging intermittently and repeatedly stopping. convert to voltage,
A high-voltage power supply circuit supplies the above-mentioned electrostatic precipitator, and an intermittent charging operation is repeated in which the DC power supplied from this high-voltage power supply circuit to the above-mentioned electrostatic precipitator is supplied for T1 time and then the supply is stopped for T2 time. Based on a charge control means to control, a dust concentration meter provided on the outlet side of the electrostatic precipitator, and a concentration signal outputted from the dust concentration meter, the charge increases when the dust concentration becomes less than a set value. T1/(T1+
The above T1,
It is characterized by comprising an adjustment means for adjusting T2.

An embodiment of the present invention will be explained with reference to the drawings.
Figure 4 is a block diagram showing the circuit configuration, Figure 5
The figure is an output waveform diagram of the pulse generator in Figure 4, Figure 6 is a voltage-current characteristic diagram of the electrostatic precipitator, Figure 7 is a diagram of the current and voltage waveforms of the precipitator in Figure 4, and Figure 8 is a diagram of the voltage-current characteristics of the electric precipitator. In the diagram showing the relationship between electrostatic precipitating efficiency and power consumption, characteristic a shows the one based on the improved method shown in FIG. 2, and characteristic b shows the one based on the present invention.

First, in FIG. 4, the same reference numerals as in FIGS. 1 and 2 indicate the same members, and 4 is a gate circuit having two inputs a, b and one output c, with input b being When given, the input a is output as the output c, and when the input b is 0, the output c is also 0. 5 is a pulse generator, and from the output terminal b, as shown in _FIG. The pulse is outputted as a gate signal at a period of T ₁ +T ₂ , and T ₁ and T ₂ are determined by the input a, that is, the output signal D of the dust concentration meter 6 as follows.

That is, the pulse generator 5 has adjustment means,
When D is small, that is, the dust concentration is low, T ₁ is decreased or T ₂ is increased to make T ₁ /T ₁ + T ₂ small, and conversely when D becomes large, T ₁ /T ₁ + T is Increase ₂ . For example, when D changes from 0 to 100%,
By setting T ₁ =10 ms and changing T ₂ from 0 to 500 ms, T ₁ /T ₁ +T ₂ is changed in the range of 1 to 0.02.

The input a of the gate circuit 4 uses the output of the conventional control circuit 3 shown in FIG. In the circuit shown in FIG. 4, the control device 3, gate circuit 4, and pulse generator 5 supply DC power from the high-voltage power supply 2 to the electrostatic precipitator 1 for T1 hours, and then
A charging controller is configured to repeat an intermittent charging operation in which supply is stopped for a certain period of time, and an adjustment is made in the pulse generator 5 to adjust the time widths T1 and T2 of the intermittent charging based on the output signal of the dust concentration meter 6. have the means. It should be noted that if the pulse generator 5 can also be configured to allow manual setting of T ₁ and T ₂ , it will be useful when the dust concentration meter 6 is out of order or in applications where there are few variations in characteristics.

In such a device, the output U of the control device 3
is as shown in FIG. 3B, and the pulse height A is the same as the output of the conventional control device 3, but T ₁ ,
Since T ₂ is determined by the output signal D of the dust concentration meter 6 or manually, when the dust collection efficiency increases and the exit dust collection concentration decreases, the ratio of charging time to one cycle, that is, T ₁ /T ₁ + T ₂ decrease, charging time T ₁
If this decreases, the dust collection efficiency will decrease and the outlet dust concentration will increase. On the other hand, when the dust concentration decreases, the opposite movement occurs. In this way, the dust concentration can be maintained at the desired value while no charging is performed.
During T ₂ , the power consumption is 0, so the purpose of energy saving can be achieved. In addition, as mentioned above, in an intermittent electrostatic precipitator, when the concentration of dust on the outlet side decreases, it is equipped with an adjustment means that adjusts T1 and T2 to increase T1/T1 + T2. This has the effect of performing a wide variety of fine-grained charge control depending on the concentration. In other words,
When the dust concentration is low, charge control is performed as follows.

Reduce T1 and leave T2 unchanged.

Increase T2 and leave T1 as is.

Let T1 be small and T2 be large.

The above three types of charge control can be performed. On the other hand, if the concentration of dust particles is high, the above T1
The sizes of and T2 can be reversed.

In general, the relationship between the voltage V and current I of an electrostatic precipitator is as shown in the characteristic diagram in Figure 6, the corona starting voltage
The current I begins to flow only when Vo, and as the voltage V increases, the current I rapidly increases.

Further, the dust collection efficiency increases as the product V _p ·V _av of the voltage peak value V _p and its average value V _av increases.

Now, in Fig. 6, at the point of V ₁ and I ₁ , when the operation is performed with a charge voltage using the control signal according to the improved method shown in Fig. 3 A, V ₁ · V _av = V ₁ ² . ,
Since power consumption W = I ₁ · V ₁ , for example, I ₁ =
If 900mA, V ₁ = 50kV, V _p・V _av = 50×50=2500, W=0.9×50=45kW
becomes.

Here, if the current I is 1/3, that is, 300 mA, then V _p · V _av = V ₂ ² , W = I ₂ · V ₂ , so for example, if V ₂ = 35 kV, V _p · V _av = 1225 , W=0.3
×35=10.5kW.

On the other hand, the device of the present invention uses a pulsed control signal U as shown in FIG. 3B.
The voltage V and the current I change as shown in Fig. 7, and assuming that the magnitude of the current during the charging time T ₁ is I ₁ = 900 mA and is the same as the operation example in the improved method, the peak value of the voltage V _p is From Figure 6, V _p =V ₁ =50kV. Also, for example, if T ₁ = 10 ms and find T ₂ that results in the same power consumption as the operation example of the improved method, W = V _p・ I ₁・ T ₁ / (T ₁ + T ₂ ) = 50×0.9×10 /
From the relationship (10+T ₂ )=10.5kW, we get T ₂ =33ms.

That is, in the operation example according to the present invention, T ₁ =10ms,
If T ₂ = 33ms, 10.5kW of improved method operation example
The power consumption is the same as , and at this time, the voltage V is
Even if the current is cut off during T ₂ , as shown by the hatching in FIG. 7, it does not drop to V ₀ rapidly due to the capacitance of the precipitator. Therefore, the cutoff time
Even if T ₂ exists, the average value of the voltage Vav will not become so small. This value varies depending on the dust collector and operating conditions, and cannot be determined even if the characteristics shown in Figure 6 are given.
For example, if V _av = 27kV,
V _p・V _av = 50 × 27 = 1350, and compared to the improved method operation example, V _p・V _av = (1350−
1225)/1225=10% dust collection efficiency improves.

According to experiments, the relationship between power consumption and dust collection efficiency is generally as shown in Figure 8, where characteristic a corresponds to the improved method in Figure 3A, and characteristic b corresponds to the improved method in Figure 3A.
Figure B, that is, the characteristics according to the present invention, in order to obtain the same dust collection efficiency c, the improved method requires power consumption of A, but according to the present invention, power consumption of B is required, so the present invention is implemented. Therefore, the power consumption of A-B can be saved.

In short, according to the present invention, there is provided an electrostatic precipitator, a high-voltage power circuit that converts a commercial power supply voltage into a DC high voltage, and supplies the DC high voltage to the electrostatic precipitator; T1
A charging control means that controls to repeat an intermittent charging operation in which the supply is stopped for T2 hours after being supplied for a time, a dust concentration meter installed on the outlet side of the electrostatic precipitator, and an output from this dust concentration meter. Based on the concentration signal, T1/(T1+T2) in the charge control means is decreased when the dust concentration becomes lower than the set value, and T1/(T1+T2) is decreased when the dust concentration becomes higher than the set value.
The present invention is industrially extremely useful because it provides an electrostatic precipitator that saves energy by including an adjusting means for adjusting T1 and T2 so as to increase (T1+T2).

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a known electrostatic precipitator, Fig. 2 is a block diagram showing an improved method of Fig. 1, and Fig. 3A is a waveform diagram of the control signal U in Fig. 2. B is a waveform diagram when the control signal is output in pulse form in FIG. 2, FIG. 4 is a block diagram showing an embodiment of the present invention, and FIG. 5 is an output waveform diagram of the pulse generator of FIG. 4. , Figure 6 is a characteristic diagram of the electric precipitator, Figure 7 is a current and voltage waveform diagram of the precipitator in Figure 4, and Figure 8 is a diagram showing the relationship between dust collection efficiency and power consumption. Characteristic a shows the characteristic according to the improved method shown in FIG. 2, and characteristic b shows the characteristic according to the present invention. 1...Electric precipitator, 2...High voltage power supply, 3...Control device, 4...Gate circuit, 5...Pulse generator, 6...Dust concentration meter, D...Dust concentration signal, U
...control signal, _T1 ...charging time, _T2 ...stopping time.

Claims (1)

[Claims] 1. An electrostatic precipitator, a high-voltage power supply circuit that converts the commercial power supply voltage into DC high voltage and supplies it to the electrostatic precipitator, and the DC power supplied from this high-voltage power supply circuit to the electrostatic precipitator at T1. A charging control means that controls to repeat an intermittent charging operation in which the supply is stopped for T2 hours after being supplied for a time, a dust concentration meter installed on the outlet side of the electrostatic precipitator, and an output from this dust concentration meter. Based on the concentration signal, when the dust concentration becomes lower than the set value, the charge control means
An electrostatic precipitator characterized by comprising an adjusting means for adjusting T1 and T2 so as to reduce T1/(T1+T2) and increase T1/(T1+T2) when the dust concentration becomes larger than a set value. Device.