JP2000189845A - Electric precipitator of boiler exhaust gas treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the cost reducible by eliminating the necessity for providing an excessive chamber or a damper, to reduce the use amt. of water and to dispense with an exclusive waste water treatment apparatus. SOLUTION: The electric precipitator is constituted by providing hammering devices 15 for striking down the soot attached to dust collecting electrodes 13, to the dust collecting electrodes 13 of respective stages other than a most downward stage and providing a water supply device 17 for supplying water to the surface of the dust collecting electrode of the most downstream stage to form a water film thereon to the dust collecting electrode 13 of the most downstream stage and guiding a part of circulating water in the water supply device 17 to a desulfurizer 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric precipitator for boiler flue gas treatment equipment.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a conventional boiler flue gas treatment facility, wherein 1 is a boiler main body that burns fuel to generate steam, and 2 is a heat generator that generates heat from combustion exhaust gas discharged from the boiler main body 1. And 3 is an electric precipitator for collecting dust contained in the combustion exhaust gas from which heat has been recovered by the heat recuperator 2 of the gas gas heater, and 5 is an electric precipitator. A desulfurization device for removing sulfur oxides contained in the combustion exhaust gas from which dust is collected by the device 3. 8 is a reheater of a gas gas heater for reheating by heating, 8 is a chimney for discharging the combustion exhaust gas reheated by the reheater 6 of the gas gas heater to the atmosphere, and 4 is a discharge from the boiler body 1. Attracted flue gas An induction ventilator 7 provided between the electrostatic precipitator 3 and the desulfurizer 5 for guiding the flue gas reheated by the reheater 6 of the gas gas heater to the chimney 8 for discharge into the atmosphere. It is an exhaust fan.

In the conventional boiler flue gas treatment equipment shown in FIG. 4, fuel is burned in the boiler main body 1 to generate steam, and the combustion exhaust gas discharged from the boiler main body 1 at that time is induced draft. The heat is recovered by the heat recovery unit 2 of the gas gas heater, and the electric dust collection device 3
Dust is collected by a desulfurizer 5, sulfur oxides are removed by a desulfurizer 5, and reheated by the heat recovered by the heat recovery unit 2 in a reheater 6 of a gas gas heater. It is being released into the atmosphere.

[0004] The flue gas discharged from the desulfurizer 5 after removing sulfur oxides is usually about 50 ° C.
When the temperature of the flue gas drops to about the water saturation state, and the flue gas after desulfurization is discharged directly from the chimney 8 into the atmosphere, white smoke is generated. The combustion exhaust gas discharged from the desulfurization device 5 is reheated by using a gas gas heater.

[0005] Incidentally, the electric dust collector 3 is usually
As shown in FIGS. 5 and 6, the inside of a duct casing 10 having a hopper 9 formed at a lower portion is partitioned by a partition wall 11 in a width direction (see FIG. 6) orthogonal to the flow direction of the combustion exhaust gas (see FIG. 6). 6 is divided into eight chambers 12, and inside each chamber 12, a plurality of stages (in FIG.
Of the dust collecting electrode 1) and a plurality of steps in the width direction.
3 and a discharge electrode 14 between the dust collecting electrodes 13, and a hammering device 15 for knocking down the dust adhering to the dust collecting electrodes 13 to the dust collecting electrodes 13 of each stage. Further, a damper 16 is provided at the entrance and the exit of each chamber 12 partitioned by the partition wall 11 so as to be openable and closable.

In the above-mentioned electric precipitator 3, when an electric field is formed with the discharge electrode 14 as a negative electrode and the dust collection electrode 13 as a positive electrode, and the intensity of the electric field is appropriately increased, the gas around the discharge electrode 14 becomes localized. When a so-called corona discharge is caused and a combustion exhaust gas including dust discharged from the boiler main body 1 is passed through such an electric field, the dust is instantaneously charged,
It moves to the collection electrode 13 due to Coulomb force and is collected.

If the dust collected and adhered to the dust collecting electrode 13 is left as it is, the surface of the dust collecting electrode 13 is completely covered with the dust, and the collecting efficiency is reduced. By operating the device 15, the dust adhering to the dust collection electrode 13 is knocked down, collected by the hopper 9, and appropriately processed.

However, when the hammering device 15 is simply operated to knock down the dust adhering to the dust collecting electrode 13, a part of the collected dust flows to the downstream side together with the combustion exhaust gas and the electric dust is collected. The dust concentration at the outlet of the dust device 3 is set to a certain value (about 30
[Mg / m ³ · N]) or less, and as a result, the dust concentration at the outlet of the chimney 8 exceeds a desired value (about 5 [mg / m ³ · N]). Will be lost.

For this reason, conventionally, as shown in FIG. 6, dampers 16 provided at the inlet and outlet of a desired one of a plurality of chambers 12 are closed and the chambers are closed. By hammering the dust collecting poles 13 of each stage disposed in the inside 12 with a hammering device 15, the dust attached to the dust collecting poles 13 is knocked down so as not to flow downstream, and the hopper section 9. When the hammering of the chamber 12 is completed, the damper 16 is opened and the damper 16 of another chamber 12 is closed, and the same operation as described above is sequentially repeated.
The chambers 12 were hammered one by one in order.

[0010]

However, if the hammering of the chambers 12 is performed one by one as described above, the spare chambers 12 which are not originally required for collecting dust are required. In addition to having to provide extra,
2 must be provided with a damper 16 and the electric precipitator 3
This has the disadvantage of increasing the cost.

As the electric precipitator 3, there is not only a dry type as described above, but also a wet type in which a water film is always formed on the entire surface of the dust collecting electrode 13 in each stage. However, such a wet type electrostatic precipitator 3 has a drawback that the amount of water used increases and a dedicated wastewater treatment device must be provided, which also leads to an increase in cost.

In view of such circumstances, the present invention can reduce the cost by eliminating the need for providing an extra chamber or damper, but can reduce the amount of water used and can eliminate the need for a dedicated wastewater treatment device. It is an object of the present invention to provide an electric precipitator for a flue gas treatment facility.

[0013]

SUMMARY OF THE INVENTION The present invention relates to an electric collector of a boiler flue gas treatment facility, which is disposed upstream of a desulfurization unit and has a plurality of dust collecting poles arranged in a flow direction of flue gas therein. In the dust collector, a hammering device for knocking down the dust adhering to the dust collecting electrode is provided at each of the dust collecting electrodes other than the most downstream stage, and water is attached to the surface of the dust collecting electrode at the most downstream stage. And a water supply device for forming a water film by supplying water.

In the electric dust collector of the boiler flue gas treatment facility, part of the water for the desulfurization unit is introduced into a water supply unit,
It is desirable to circulate the water after forming the water film on the surface of the dust collection electrode at the lowest stage, and to introduce a part of the circulated water to the desulfurizer.

According to the above means, the following effects can be obtained.

[0016] During operation of the electric precipitator, water is supplied to the surface of the lowermost stage dust collection electrode by the operation of the water supply device to form a water film. The dust collected and attached is washed away by the water film each time, while the dust attached to the dust collecting electrode of each stage other than the most downstream stage is:
By periodically operating the hammering device, the device is beaten down, collected, and appropriately processed. At this time, part of the dust flows to the downstream side together with the combustion exhaust gas.

However, the dust that has flowed to the downstream side together with the combustion exhaust gas is collected by the dust collection electrode at the lowest stage and washed away by the water film, so that the dust concentration at the outlet of the electric dust collector is: It is suppressed below a certain value, and the dust concentration at the outlet of the chimney can be maintained at a desired value.

As a result, it is not necessary to hammer the chambers one by one in order, so that there is no need to provide extra spare chambers which are not necessary for collecting dust, and to provide a damper for each chamber. Is unnecessary, and the cost of the electric precipitator can be reduced.

Further, in the electric dust collector of the boiler flue gas treatment facility, a part of the water for the desulfurizer is introduced into the water feeder, and a water film is formed on the surface of the lowermost dust collecting electrode. By circulating the water and configuring a part of the circulating water to be guided to the desulfurization device, the amount of water used can be reduced, while a part of the circulating water can be used as makeup water for the desulfurization device. There is no need to provide a dedicated wastewater treatment device, and this also leads to cost reduction.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show an example of an embodiment of the present invention. In the drawings, the parts denoted by the same reference numerals as those in FIGS. 4 to 6 represent the same parts. This is similar to the conventional one shown in FIGS. 4 to 6, but the feature of this illustrated example is that, as shown in FIGS. A hammering device 15 for knocking down dust adhering to the dust collecting electrode 13 was provided, and a water supply device 17 for supplying water to the surface of the dust collecting electrode 13 at the most downstream stage to form a water film was provided. On the point.

In the illustrated example, the water supply device 17 includes:
Part of the water for the desulfurization device 5 is introduced, and water is sprayed from a plurality of nozzles 18 onto the surface of the dust collection electrode 13 at the most downstream stage to form a water film. The water after the formation of the water film is collected in the hopper section 9 and circulated by the operation of the circulation pump 19, and a part of the circulated water is desulfurized by the desulfurizer 5.
It is configured to lead to.

Next, the operation of the illustrated example will be described.

During the operation of the electric precipitator 3, a part of the water for the desulfurization device 5 is introduced into the water supply device 17, and the water is constantly supplied from the plurality of nozzles 18 to the surface of the lowermost stage precipitating electrode 13. Is sprayed to form a water film, and after forming the water film on the surface of the dust collecting electrode 13 at the most downstream stage, the water is collected by the hopper 9 and circulated by the operation of the circulation pump 19.

As a result, the dust collected and attached to the dust collecting electrode 13 at the lowermost stage is washed away by the water film each time, while the dust attached to the dust collecting electrode 13 at each stage other than the lowermost stage. Is beaten down by periodically operating the hammering device 15, collected by the hopper 9, and treated as appropriate. At this time, part of the dust flows to the downstream side together with the combustion exhaust gas. .

However, the dust that has flowed to the downstream side together with the combustion exhaust gas is collected by the dust collector 13 at the lowest stage and washed away by the water film, so that the dust concentration at the outlet of the electric dust collector 3 is reduced. Is a certain value (about 30 [mg /
m ³ · N]), and the dust concentration at the outlet of the chimney 8 is also a desired value (about 5 [mg / m ³ · N]).
Can be held.

As a result, it is not necessary to hammer the chambers 12 one by one in order, so that there is no need to provide extra spare chambers 12 which are originally unnecessary for collecting dust, There is no need to provide the damper 16 in the 12 (see FIG. 3), and the cost of the electric dust collecting device 3 can be reduced.

A part of the water for the desulfurization unit 5 is introduced into the water supply unit 17, and the dust collection electrode 13 at the lowest stage is provided.
Since the water film only needs to be formed on the surface of the substrate, the amount of water used is small.

On the other hand, the water after the formation of the water film on the surface of the dust collecting electrode 13 at the most downstream stage gradually becomes cloudy as it contains dust while being circulated. Is guided to the desulfurization device 5 and can be used as makeup water, so that there is no need to provide a dedicated wastewater treatment device, and this also leads to cost reduction.

In this way, the cost can be reduced by eliminating the need for providing the extra chamber 12 and the damper 16, but the amount of water used can be reduced, and a dedicated wastewater treatment device can be eliminated.

It should be noted that the electric precipitator of the boiler flue gas treatment equipment of the present invention is not limited to the above-described illustrated example, and various changes can be made without departing from the gist of the present invention. Of course.

[0032]

As described above, the first aspect of the present invention is as described above.
According to the electric dust collector of the boiler flue gas treatment equipment described above, it is possible to achieve an excellent effect that the cost can be reduced by eliminating the necessity of providing an extra chamber or a damper, and the invention according to claim 2 of the present invention. According to the electric precipitator of the boiler flue gas treatment facility, in addition to the above-mentioned effects, it is possible to achieve an excellent effect that the amount of water used can be reduced and a dedicated wastewater treatment device can be eliminated.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of an example of an embodiment of the present invention.

FIG. 2 is an enlarged side sectional view of a main part of an example of an embodiment of the present invention.

FIG. 3 is an enlarged plan cross-sectional view of an essential part of an example of an embodiment of the present invention, and is a view corresponding to the view taken along line III-III of FIG. 2;

FIG. 4 is an overall schematic configuration diagram of a conventional example.

FIG. 5 is an enlarged side sectional view of a main part of a conventional example.

6 is an enlarged plan cross-sectional view of a main part of a conventional example, and FIG.
FIG. 6 is a view corresponding to the arrow I-VI.

[Explanation of symbols]

 3 Electric Dust Collector 5 Desulfurizer 12 Chamber 13 Dust Collector 15 Hammer 17 Water Supply 19 Circulation Pump

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D002 AA02 AC01 BA02 BA12 BA14 CA01 CA07 DA66 EA01 EA02 EA05 GA02 GB02 GB03 HA07 HA08 4D054 AA02 BA01 BA08 DA02 DA06 DA11 EA21 EA30

Claims (2)

[Claims] 1. An electric dust collector for a boiler flue gas treatment facility, wherein the dust collector is disposed upstream of a desulfurizer and has a plurality of dust collectors arranged in a flow direction of flue gas inside the desulfurizer. A hammering device for knocking down the dust adhering to the dust collecting electrode is provided at each stage of the dust collecting electrode, and water is supplied to the surface of the dust collecting electrode at the most downstream stage to form a water film. An electric precipitator for a boiler flue gas treatment facility, comprising a water supply device. 2. A part of water for a desulfurization device is introduced into a water supply device, and water after forming a water film on the surface of a dust collecting electrode at the lowest stage is circulated, and a part of the circulated water is removed. The electric dust collector of a boiler flue gas treatment facility according to claim 1, wherein the electric dust collector is configured to be guided to a desulfurizer.