JP2000288423A - Operation and electrostatic dust collector at boiler flue gas treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the increase of soot and dust concn. at the outlet of an electrostatic dust collector and to always keep the soot and dust concn. at the outlet of a stack to a value below normal value even in the case when the soot and dust concn. flowing into an electrostatic dust collector is temporarily increased or the gas amount to be treated at the electrostatic dust collector is temporarily increased by the overshoot, or the like, at the time of changing boiler load in the case when the removing of the stuck soot and dust by a soot blower is executed at an upstream side device. SOLUTION: At the time at which the increase of treating capacity is required such a case when the soot and dust concn. flowing into the electrostatic dust collector is temporarily increased by the removal of the stuck soot and dust at the upstream side device of the electrostatic dust collector 3 or the gas amount to be treated at the electrostatic dust collector is temporarily increased by the overshoot, or the like, at the time of changing boiler load, the soot and dust are captured by making stuck to a dust collecting pole disposed at the inside of each chamber 12 while combustion waste gas circulates in all chambers 12 through opening of dampers 16 of the plural or all chambers 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating an electric precipitator in a boiler flue gas treatment facility.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a conventional boiler flue gas treatment facility, in which 1 is a boiler main body for burning fuel to generate steam, and 2 is a heat generator for burning 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, and a heat recovery device 2 recovers the combustion exhaust gas from which the sulfur oxides have been removed by the desulfurization device 5. 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. 2, fuel is burned in the boiler body 1 to generate steam, and the combustion exhaust gas discharged from the boiler 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. 3 and 4, the inside of the duct casing 10 in which the hopper 9 is formed in the lower part is divided by a partition wall 11 in a width direction (see FIG. 4) perpendicular to the flow direction of the combustion exhaust gas (see FIG. 4). 4 are divided into eight chambers 12 and a plurality of stages (in FIG.
Of the dust collecting electrode 1) and a plurality of steps in the width direction.
3 and a large number of discharge electrodes (not shown) are disposed between the dust collecting electrodes 13 so that dust adhering to the dust collecting electrodes 13 is knocked down to the dust collecting electrodes 13 at each stage. And a damper 16 is provided at an entrance and an exit of each chamber 12 partitioned by the partition wall 11 so as to be openable and closable, respectively.

In the case shown in FIG. 4, the duct casing 10 is roughly divided into two such that four chambers 12 are put together, and a common damper 17 is provided at the entrance and the exit, respectively. The two inlet ducts 2 communicate with each other through an inlet common duct 18 and an outlet common duct 19, and each half of the entire combustion exhaust gas flows.
0 and two outlet ducts 21 are connected.

In the above-described electric precipitator 3, when an electric field is formed with the discharge electrode (not shown) as a negative electrode and the dust collection electrode 13 as a positive electrode, and the electric field intensity is appropriately increased, the gas around the discharge electrode becomes When insulation breakdown occurs locally, so-called corona discharge occurs, and when flue gas containing dust discharged from the boiler body 1 is passed through such an electric field, the dust is instantaneously charged, and the dust is charged to the dust collecting electrode 13 by Coulomb force. It moves 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, if 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 (approximately 30
[About [mg / m ³ · N]) or less, and as a result, the dust concentration at the outlet of the chimney 8 exceeds the specified value (about 5 [mg / m ³ · N]). It will be.

For this reason, conventionally, as shown in FIG. 4, a desired one of a plurality of chambers 12 is closed with dampers 16 provided at an entrance and an exit of the chamber. Each of the dust collecting electrodes 13 (see FIG.
By hammering with the hammering device 15, the dust attached to the dust collecting electrode 13 is beaten down so as not to flow downstream and collected in the hopper 9, and the hammering of the chamber 12 is completed. Then, the damper 16 is opened and another room 1 is opened.
The second damper 16 is closed, and the same operation as described above is sequentially repeated to hammer the chambers 12 one by one.

The total amount of the combustion exhaust gas at this time is 1
When the amount of the combustion exhaust gas flowing through each part of the electrostatic precipitator 3 is examined, as shown in FIG. 1/14 of the total amount of combustion exhaust gas flows from the side where the chamber 12 where the damper 16 is closed to the side where the chamber 12 where the damper 16 is closed does not flow through the inlet common duct 18, As a result, the combustion exhaust gas of 1/7 of the total amount flows evenly through each chamber 12, and thereafter, the entire exhaust gas flows from the side where the chamber 12 in which the damper 16 is closed does not exist through the outlet common duct 19. A form in which the amount of flue gas of 1/14 flows into the side where the chamber 12 in which the damper 16 is closed is present, and the amount of flue gas of the entire amount flows out to the two outlet ducts 21 in half. Become.

[0012]

However, in the conventional electric precipitator 3 as described above, when the soot blower removes the adhering dust using an upstream device such as the boiler body 1 or the heat recovery unit 2 of the gas gas heater. In addition, the dust concentration flowing into the electrostatic precipitator 3 may temporarily increase, or the electric precipitator 3 may be overshot due to a change in boiler load.
In the case where the amount of processing gas in the chamber temporarily increases, the same operation method as that of the related art, that is, a desired one of the plurality (eight) of chambers 12 is provided with a damper provided at the inlet and outlet thereof When the operation is performed in such a manner that the combustion exhaust gas is circulated to the remaining (seven) chambers 12, the concentration of dust and dust at the outlet of the electrostatic precipitator 3 increases, and as a result, the outlet of the chimney 8 There is a risk that the dust concentration at the point exceeds the specified value.

[0013] In view of such circumstances, the present invention reduces the concentration of dust flowing into the electric precipitator when the adhering dust is removed by a soot blower in an upstream device such as a boiler body or a heat recovery unit of a gas gas heater. Even if it temporarily increases, or even if the amount of processing gas in the electrostatic precipitator temporarily increases due to overshoot at the time of boiler load change,
It can prevent the rise of the dust concentration at the outlet of the electrostatic precipitator.
An object of the present invention is to provide a method for operating an electric precipitator in a boiler flue gas treatment facility capable of maintaining a dust concentration at an outlet of a chimney below a specified value.

[0014]

SUMMARY OF THE INVENTION The present invention relates to a method for removing flue gas contained in flue gas discharged from a boiler main body and for removing flue gas inside a duct casing having a hopper formed at a lower portion thereof. An operation method of an electric precipitator in a boiler flue gas treatment facility divided into a plurality of chambers in a width direction orthogonal to a flow direction of a normal operation, and usually, an inlet portion of a desired one of a plurality of chambers. With the damper provided at the outlet part closed and closed, the flue gas is allowed to flow to the remaining chambers, so that dust adheres to and collects on the dust collection electrodes disposed inside each chamber. By hammering the dust collection electrode disposed in the closed room with a hammer, the dust attached to the dust collection electrode is beaten down so as not to flow downstream and collected in the hopper portion, The hammering of the room is completed While opening the damper and closing the damper in another chamber, the same operation as described above is sequentially repeated to hammer the chambers one by one. A boiler flue gas treatment facility characterized in that by opening all dampers of the chambers and allowing the combustion exhaust gas to flow through all the chambers, dust is attached to and collected on the dust collecting poles disposed inside each chamber. The present invention relates to an operation method of the electric dust collector.

[0015] The processing capacity may be increased when the dust concentration in the electric dust collector is temporarily increased due to removal of the attached dust in the upstream device of the electric dust collector, or when the boiler load changes. One example is when the amount of processing gas in the electric precipitator by the chute is temporarily increased.

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

Normally, as in the conventional case, the combustion exhaust gas is circulated to the remaining chambers with the dampers provided at the entrance and the exit of a desired one of the plurality of chambers closed and closed. Dust adheres to and collects on the dust collection electrodes provided inside each room, and the dust collection electrodes provided in the closed rooms are hammered by the hammer and adhere to the dust collection electrodes. The dust which has been blown down is collected so as not to flow to the downstream side and collected in the hopper, and when the hammering of that chamber is completed, the damper is opened and the damper of another chamber is closed,
Hereinafter, the same operation as described above is sequentially repeated, and the chambers are hammered one by one.

On the other hand, when the dust concentration in the electric precipitator is temporarily increased due to the removal of the dust attached to the upstream device of the electric precipitator, or when the boiler load changes, the electric precipitator is used. When it is necessary to increase the processing capacity, such as when the amount of processing gas is temporarily increased, the dampers of all of the plurality of chambers are opened, the combustion exhaust gas is circulated through all the chambers, and the dust is collected by the dust collection electrodes disposed inside each chamber. Adheres and is collected.

As a result, all of the plurality of chambers that are not normally used at the same time are temporarily used at the same time only when it is necessary to increase the processing capacity. The dust concentration at the outlet of the apparatus does not rise, and the dust concentration at the outlet of the chimney is kept below the specified value.

[0020]

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

FIG. 1 shows an example of an embodiment of the present invention. In the drawing, portions denoted by the same reference numerals as those in FIGS. 2 to 4 represent the same components, and the basic configuration is shown in FIGS. 4 is the same as the conventional one shown in FIG. 4, but the feature of this example is that, as shown in FIG. 1, the upstream device (the boiler body 1 and the heat recovery unit 2 of the gas gas heater) of the electric precipitator 3. Etc.) when the dust concentration to the electric precipitator 3 is temporarily increased due to the removal of the adhering dust in the electric precipitator 3 or the amount of processing gas in the electric precipitator 3 is temporarily increased due to overshoot when the boiler load changes. When it is necessary to increase the processing capacity, for example, by opening all the dampers 16 of the plurality of chambers 12 and allowing the combustion exhaust gas to flow through all the chambers 12, dust is attached to the dust collection electrodes 13 disposed inside each chamber 12. The point is to collect.

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

Normally, as in the conventional case shown in FIG. 4, the dampers 16 provided at the entrance and the exit of a desired one of the plurality of chambers 12 are closed and closed, and the remaining chambers are closed. The combustion exhaust gas is circulated to the chambers 12 and
Dust adheres to and collects on the dust collecting electrode disposed in the interior of the chamber, and the dust collecting electrode 13 disposed in the closed chamber 12 is hammered by the hammering device 15, and When the dust attached to the chamber 12 is knocked down and collected in the hopper 9 so as not to flow to the downstream side, and the hammering of the chamber 12 is completed,
The damper 16 is opened, and the damper 16 of another chamber 12 is closed. Thereafter, the same operation as described above is sequentially repeated, and the chambers 12 are hammered one by one in order.

On the other hand, when the dust concentration on the electric precipitator 3 is temporarily increased due to the removal of the adhering dust in the upstream device of the electric precipitator 3 or when the boiler load changes, the electric precipitator is overshooted. When the processing capacity needs to be increased, for example, when the amount of processing gas in the dust device 3 is temporarily increased, all the dampers 16 of the plurality of chambers 12 are opened, and the combustion exhaust gas is circulated to all the chambers 12, and distributed inside the respective chambers 12. Dust collection electrode 1 installed
Dust adheres to 3 and is collected.

Assuming that the total amount of the combustion exhaust gas at this time is 1, when looking at the amount of the combustion exhaust gas flowing through each part of the electrostatic precipitator 3, as shown in FIG.
燃 焼 of the total amount of combustion exhaust gas flows into the respective chambers 12, and １ ／ of the total amount of combustion exhaust gas flows uniformly into each chamber 12, and thereafter, flows into the two outlet ducts 21. A half of the total amount of the combustion exhaust gas flows out.

When the processing capacity needs to be increased, the processing capacity is only temporary. After that, the state is immediately returned to the same state as the normal state, and the dust collecting electrode 13 is hammered. There is no worry that the surface of the dust electrode 13 is completely covered with dust and the collection efficiency is reduced.

As a result, all of the plurality of chambers 12 which are not normally used at the same time are temporarily used at the same time only when it is necessary to increase the processing capacity. The dust concentration at the outlet of the dust device 3 does not increase, and the dust concentration at the outlet of the chimney 8 is maintained at a specified value or less.

As described above, when the soot blower removes the adhering dust with the upstream equipment such as the boiler body 1 and the heat recovery unit 2 of the gas gas heater, the concentration of the dust flowing into the electric dust collector 3 temporarily increases. Even if the processing gas amount in the electrostatic precipitator 3 is temporarily increased due to overshoot at the time of boiler load change or the like, it is possible to prevent the rise of the dust concentration at the outlet of the electric precipitator 3. The dust concentration at the outlet of the chimney 8 can always be kept below a specified value.

The operation method of the electric precipitator in the boiler flue gas treatment equipment of the present invention is not limited to the above-described example, and various modifications may be made without departing from the gist of the present invention. Obviously you can get it.

[0030]

As described above, the first aspect of the present invention is as described above.
According to the operating method of the electric precipitator in the boiler flue gas treatment equipment described in the above-mentioned items 3, when the soot blower removes the adhering dust using an upstream device such as a boiler body or a heat recovery unit of a gas gas heater, Even if the concentration of soot and dust flowing into the dust collector temporarily increases, or the amount of processing gas in the electrostatic dust collector temporarily increases due to overshoot at the time of boiler load change, etc. It is possible to prevent the rise of the dust concentration at the outlet of the device, and to achieve an excellent effect that the dust concentration at the outlet of the chimney can always be maintained at a specified value or less.

[Brief description of the drawings]

FIG. 1 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 an arrow IV-IV in FIG.

FIG. 2 is an overall schematic configuration diagram of a conventional example.

FIG. 3 is an enlarged side sectional view of a main part of a conventional example.

FIG. 4 is an enlarged plan sectional view of a main part of a conventional example,
FIG. 4 is a view corresponding to the arrow V-IV.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler main body (upstream apparatus) 2 Heat recovery unit of gas gas heater (upstream apparatus) 3 Electric dust collecting device 9 Hopper section 10 Duct casing 11 Partition wall 12 Room 13 Dust collecting pole 15 Hammering device 16 Damper

Claims (3)

[Claims] 1. A duct casing installed to remove dust contained in flue gas discharged from a boiler main body and having a hopper section formed in a lower part thereof, extends in a width direction orthogonal to a flowing direction of the flue gas. A method for operating an electric precipitator in a boiler flue gas treatment facility divided into a plurality of chambers, wherein normally, a damper provided at an inlet and an outlet of a desired one of the plurality of chambers. In the closed and closed state, the combustion exhaust gas is circulated to the remaining chambers, so that the dust is attached to and collected on the dust collecting poles disposed inside each chamber, and is disposed in the closed chamber. By hammering the dust collecting electrode with a hammer, the dust attached to the dust collecting electrode is beaten down so as not to flow downstream and collected in the hopper, and when the hammering of the chamber is completed, When the damper is opened Then, close the dampers in other chambers, and repeat the same operation as above to sequentially hammer the chambers one by one, while opening the dampers in all of the multiple chambers when the processing capacity needs to be increased. The operation of the electric precipitator in the boiler flue gas treatment facility, characterized in that the flue gas is circulated through all the chambers, so that dust is attached to and collected on the dust collection poles arranged inside each chamber. Method. 2. The boiler according to claim 1, wherein the time when the processing capacity needs to be increased is a time when the concentration of dust in the electric precipitator is temporarily increased due to removal of the attached dust in the upstream device of the electric precipitator. An operation method of the electric precipitator in the flue gas treatment facility. 3. The boiler flue gas treatment facility according to claim 1, wherein the time when the processing capacity needs to be increased is a time when the amount of processing gas in the electric dust collector is temporarily increased due to an overshoot when the boiler load changes. Dust operation method.