JPS5826981B2 - How to operate a dry electrostatic precipitator equipped with a water film electrostatic precipitator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a dry electrostatic precipitator having a water film electrostatic precipitator.

Traditionally, dry electrostatic precipitators have been used in a wide range of fields, including the collection of exhaust gas from heavy oil-fired and coal-fired boilers, the collection of exhaust gas from cement kilns and finishing mills, and the collection of exhaust gas from garbage incinerators. However, conventional dry electrostatic precipitators have problems such as dust scattering during hammering and the occurrence of dust concentration peaks, especially those in the rearmost chamber relative to the gas flow. .

According to recent research, the above-mentioned problem has been solved to some extent by placing a water film type electrostatic precipitator downstream of the dry type electrostatic precipitator. Since water was being supplied continuously to the dust collector in the building, the amount of fresh water used was not only uneconomical, but also a large amount of money had to be spent on purifying the wastewater after dust collection. Moreover, since the temperature of the gas accumulates and drops after being multiplied, it is necessary to reheat the gas and then discharge it from the chimney, which raises the problem of equipment and operating costs. Ta.

Therefore, the present inventors further researched a dust collector in which a water film type electrostatic precipitator is placed after a dry type electrostatic precipitator, and as a result of investigating dust collection of exhaust gas from heavy oil-fired boilers, the dry type electrostatic precipitator The dust collection efficiency of the dust collection electrode of the water film type electrostatic dust collection part is approximately 40 to 5 when the dust collection electrode of the dust part is not hammered.
0%, while the dust collection efficiency of the dust collecting electrode of the water film type electrostatic precipitator is about 80 to 90% when hammering the dust collecting electrode of the dry type electrostatic precipitator. It was found that the dust collection efficiency is high when using a hammer, but it is relatively low when no hammer is used.

In other words, it has been found that the effect of supplying water to the dust collecting electrode of the water film type electrostatic precipitator when the dust collecting electrode of the dry type electrostatic precipitator is not hammered is small.

Therefore, the present invention provides a method for supplying water intermittently to the dust collection electrode of a water film type electrostatic precipitator in synchronization with the hammering period of the final chamber of the dry type electrostatic precipitator, without continuously supplying water. Embodiments thereof will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing a dry electrostatic precipitator having a water film electrostatic precipitator.

In FIG. 1, 1 is a first stage dry type electrostatic precipitator, 2 is a final stage dry type electrostatic precipitator, and 3 is a water film type electrostatic precipitator.

The water film type electrostatic precipitator 3 is provided downstream of the final stage dry type electrostatic precipitator 2, and flat plate-shaped dust collecting electrodes are arranged parallel to the gas flow, each surface of which has a water film. A type in which a water film is formed on the surface of the electrode, or a type in which multiple groove-shaped electrodes are arranged in the direction that blocks the gas flow, and a water film is formed on the electrode surface.
It consists of a type that forms a water film on the dust collection electrode.

4 is a hammering device of the final stage dry electrostatic precipitator 2; 5 is a water supply device to the water film electrostatic precipitator 3; 6 is a charging device for the water film electrostatic precipitator 3; These water supply devices 5
and the charging device 6 is electrically connected to operate in synchronization with the hammering device 4, or the charging device 6 is
It is activated by a timer linked to the

Further, arrow 7 indicates the inflow of exhaust gas, and arrow 8 indicates the outflow of collected exhaust gas.

FIG. 2 shows the first embodiment of the method of the present invention, where the cycle time t is plotted on the horizontal axis, the operating state of the hammering device 4 is represented by a, and the operating state of the water supply device 5 is represented by b. Representation,
The operating state of the charging device 6 is represented by C.

That is, instead of continuously supplying water to the dust collecting electrode of the water film type electrostatic precipitator 3 and charging C, the timing is adjusted to the hammering period a of the final stage dry type electrostatic precipitator 2. , only from immediately before to immediately after a.

FIG. 3 shows a second embodiment of the method of the present invention.
Regarding a and b in the figure, it is the same as in Figure 2, but
Regarding the charge of the dust collecting electrode of the water film type electrostatic precipitator 3, C
I, C2+C3, and so on, done somewhat sequentially.

FIG. 4 shows the hammering characteristics of the dry electrostatic precipitator 2, where the horizontal axis N is the number of hammerings and the vertical axis F is the hammering force.

Also, k is the peak magnification, and d is the curve for the 99.9% peeling point.

In other words, the peak value of the dust concentration at the outlet of the dry electrostatic precipitator 2 is determined by the number of hammer strikes N and the hammering force F, but the water film electrostatic precipitator 3 increases the dust collection efficiency during hammering. Since it goes up, reduce the number of hammer strikes N, increase the hammer strike force F,
Even if the peak magnification increases as a result, the water film type electrostatic precipitator 3 can compensate for the increase.

Next, Table 1 shows comparative clothing between the conventional method and the method of the present invention.

In Table 1, ■ indicates a conventional dry electrostatic precipitator, and ■ indicates a water film electrostatic precipitator in which a water film electrostatic precipitator is placed downstream of the dry electrostatic precipitator. When water is supplied and charged continuously (24 hours per day) to the multiplier electrode of
2 is based on the second embodiment of the present invention (the example shown in FIG. 3).

As can be seen from Table 1, in Examples ■ and ■ of the present invention,
The gas temperature can be kept almost the same as in the conventional dry electrostatic precipitator I, and can be kept below the outlet concentration of said I.

Also, water supply time 1 for ■ and ■ In other words, the water supply amount is - and - compared to ■, and the load 2 8 Regarding the electric time, ■ is also negative compared to ■.

4 Therefore, the operating method of the present invention does not continuously supply water to the dust collecting electrode of the water film type electrostatic precipitator, but intermittently supplies water in synchronization with the hammering period of the final chamber of the dry type dust collector. Because of this, not only is the amount of water used significantly reduced, making it possible to operate at low cost, but also the drop in gas temperature is small, resulting in energy savings, and the effects achieved are extremely impressive.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view showing an outline of the dust collection equipment operated by the method of the present invention, FIG. 2 is an explanatory diagram of the cycle of the first embodiment of the method of the present invention, and FIG. A similar explanatory diagram of the second embodiment, FIG. 4, is an explanatory diagram of the relationship between the number of hammerings and the hammering force. 1... First stage dry electrostatic precipitator, 2...
Final stage dry type electrostatic precipitator, 3... Water film type electrostatic precipitator, 4... Hammering device, 5... Water supply device, 6...・Charging device, a... Hammering period, b... Water supply amount, Cp C1, C2+c3...
...Charged agent.

Claims (1)

[Claims] 1. In electrostatic precipitator equipment in which a water film electrostatic precipitator is disposed downstream of the dry electrostatic precipitator and the dust collection electrode of the dry precipitator is intermittently hammered, A dry electrostatic precipitator having a water film electrostatic precipitator, characterized in that water is intermittently supplied to the dust collecting electrode of the water film electrostatic precipitator in synchronization with the hammering period of the final chamber. How to operate the equipment.