JPH11319630A - Dry process electric duct collector and operation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a dry process electric dust collector from being an excessive design at a normal rated operational time and also to prevent concentration of soot and dust at the outlet of the dust collector from being over a regulated value at the overshoot time. SOLUTION: A gas flow passage 4 consisting of plural numbers of chambers arranged in parallel is provided in the dry process electric dust collector 2, and the gas flow passage 4 is provided in excessive one chamber for hammering a dust collection electrode plate, besides the gas flow passage group provided with a space corresponding to the rated gas flow rate at the normal operation time. At the hammering time of the dust collection electrode in the rated gas flow rate time at a periodical normal operation time of respective chambers, a gas flow in the gas flow passage 4 of the excessive one chamber is shut down and exhaust gas of the rated flow rate is subjected to a dust collection treatment without any trouble by utilizing other whole chambers, and in the case that the gas flow rate is over the rated gas flow rate in the overshoot time in a load increasing process of a combustion device, the exhaust gas is introduced to the whole chambers of the gas flow passage 4 including the excessive one chamber to collect the dust, and during this time the periodical hammering of the dust collection electrode in the whole chamber is not performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treatment apparatus for a combustion apparatus such as a boiler and a dry electric dust collector which is one of the components thereof, and more particularly to a dry electric dust collector at the time of overshooting when the load of the combustion apparatus rises. The present invention relates to a method for operating a dry electric precipitator suitable for preventing overload of the apparatus.

[0002]

2. Description of the Related Art In order to prevent air pollution, dry-type electric precipitators for removing dust in exhaust gas have been widely used as boiler exhaust gas treatment devices. FIG. 5 shows a dry-type electrostatic precipitator, which is a component of the boiler exhaust gas treatment apparatus.
Exhaust gas 1 generated from a boiler such as a thermal power plant is subjected to removal of dust in a dry electric precipitator 22 installed on the downstream side of the boiler exhaust gas passage. Sulfur oxide (SO ₂ ) is removed by a desulfurization device (not shown) installed downstream of
Emitted from the chimney.

In the dry electric precipitator 22, a dust collecting electrode plate (not shown) is regularly hammered to collect dust collected on the precipitating electrode plate, and an impact is applied to the precipitating electrode plate. To collect the dust by dropping the dust downward.

Here, in order to prevent dust from being scattered into the exhaust gas when the dust collecting electrode plate is hammered, chambers forming a plurality of gas passages 24 are arranged in parallel inside the dry electric dust collecting device 22. , Dampers 25, 2 that can shut off gas flow for each chamber
6 are provided at the inlet and / or outlet of each gas flow path 24.

[0005] The dust collecting electrode plate is hammered for each gas passage 24 in each chamber. When the dust collecting electrode plate is hammered, the dust collecting electrode plate is provided at the inlet and / or outlet of each gas flow passage 24. By closing the dampers 25 and 26 to shut off the exhaust gas flow, the dust is prevented from re-scattering into the exhaust gas. For this reason, as shown in FIG. 5, the flow of the exhaust gas is always shut off in one chamber of the gas flow path 24 where the dust collecting electrode plate is hammered. An extra gas passage 24 for one chamber is provided in addition to the number of gas passages 24 corresponding to the space required for the flow of the entire flow rate of the exhaust gas.

[0006]

However, FIG. 3 shows the relationship between the boiler load rise elapsed time or the boiler load increase elapsed time and the boiler outlet gas flow rate. The exhaust gas flow rate may exceed the rated gas flow rate in such a case.In this case, the dry type dust collector will be overloaded, so the dust removal efficiency will decrease and the dust concentration at the outlet of the dry type dust collector will fall below the regulated value. There was a problem that exceeded.

Further, in consideration of the overshoot in advance, if the dry-type electrostatic precipitator is designed so that the dust concentration at the outlet of the dry-type electric precipitator does not exceed the regulation value at that time, the normal operation of the dry-type electrostatic precipitator may be reduced. The dry type electrostatic precipitator has a problem that an unused device part is formed, which is excessively designed and increases equipment costs.

An object of the present invention is to prevent the dry electric precipitator from being excessively designed with respect to a normal rated operation and to prevent the concentration of dust at the outlet of the dry electric precipitator from exceeding a regulation value during overshoot. It is in.

[0009]

The structure of the present invention to achieve the above object is as follows. A gas flow path group provided in an exhaust gas flow path discharged from a combustion device, divided into a plurality of chambers, and arranged in parallel, and a damper for shutting off a gas flow provided for each inlet and / or outlet of each gas flow path In a dry-type electrostatic precipitator equipped with: a regular dust collecting electrode plate hammer that is sequentially performed for each gas channel at a rated gas flow rate, the inlet of the gas channel performing the dust collecting electrode plate hammer and / or
Or close the gas path by closing the damper provided at the outlet,
If the gas flow exceeds the rated gas flow at the time of overshoot in the load rise of the combustion device, the exhaust gas is guided to the gas passages of all the rooms to collect dust, and during this time, the dust collecting electrode plate hammer in each room is used. This is a method of operating a dry electric precipitator without hitting.

At this time, the timing of overshoot is predicted based on the load signal of the combustion device and a predetermined load rise pattern of the combustion device, and before the overshoot occurs, the inlets and / or the gas flow paths of the gas passages of all the chambers are set. Alternatively, it is desirable to collect dust by fully opening the damper provided at the outlet and guiding the exhaust gas to the gas passages of all the rooms.

Therefore, in the dry electric precipitator according to the present invention, the sum of the dust collection loads of the gas passages in all the chambers except the one in which the dust collecting electrode plate is hammered corresponds to the rated gas flow rate. It is designed such that the total dust collection load of the gas passages of all the chambers in a state where no chamber for performing the electrode plate hammering is provided corresponds to the gas flow rate at the time of overshoot.

Further, in order to realize the operation method of the above-mentioned dry electric dust collector, the following dry electric dust collector is used. That is, when it is determined that the gas flow rate is the rated gas flow rate based on the load signal from the combustion device, the dust collection electrode plate is hammered periodically for each gas flow path in accordance with the rated operation pattern signal. A damper provided at the inlet and / or outlet of the gas flow channel for hammering is closed to shut off the gas flow channel, and when it is determined that the boiler load is increasing based on a load signal from the combustion device, a predetermined boiler is set. The overshoot timing is predicted based on the load rise pattern signal, and before the overshoot occurs, the dampers provided at the entrances and / or exits of all the chambers are fully opened to control the gas to be introduced into all gas flow paths. A dry-type electric power collector provided with a control device and opening and closing devices for respectively opening and closing dampers provided at an entrance and / or an exit of each of the rooms driven and controlled by the control device. It is a device.

The present invention also includes an exhaust gas treating apparatus in which the above-mentioned dry type electrostatic precipitator is arranged in a flow path of exhaust gas discharged from a combustion device. The combustion device is a boiler, a refuse incinerator, a hot blast stove, or the like, and the load signal of the combustion device is an exhaust gas flow rate, a required amount of boiler power generation output, a fuel command, or the like.

[0014]

As described above, in the dry electrostatic precipitator of the present invention, the total space of the gas flow path group consisting of a plurality of chambers is made to correspond to the rated gas flow rate during normal operation, and the space other than the gas flow path group is used. In addition, an extra gas flow path for one chamber for hammering the dust collecting electrode plate is provided, and when the hammering the dust collecting electrode plate at the rated gas flow rate during regular normal operation of each chamber, the extra The dampers provided at the inlet and / or outlet of one of the gas flow paths are fully closed to shut off the gas flow in the gas flow path, and the rated exhaust gas flow rate can be safely used by using all other chambers. Dust collection processing can be performed.

If the gas flow rate exceeds the rated gas flow rate of the dry electric precipitator at the time of overshoot in the process of increasing the load of the combustion device, if the gas flow rate exceeds the rated gas flow rate of the dry electric precipitator, all the chambers of the gas flow path, including the extra chamber, will Dust is collected by guiding the exhaust gas.During this period, the regular dust collecting electrode plate is not hammered in all rooms. Operation in which the dust concentration at the outlet of the electric precipitator does not exceed the regulation value becomes possible.

[0016]

Embodiments of the present invention will be described with reference to the drawings. 1 and 2 show an embodiment of the present invention. As shown in FIG. 1, an exhaust gas 1 generated from a boiler such as a thermal power plant flows downstream of a boiler exhaust gas channel. After being introduced into the dry electric precipitator 2 installed on the side, dust is removed, and the processing gas 3 is subjected to sulfur oxidation in a desulfurizer (not shown) installed downstream of the dry electric precipitator 2 as necessary. The matter (SO ₂ ) is removed and then discharged from the chimney. In the present invention, the dry electric precipitator 2 comprises:
As shown in FIG. 2, during normal operation of the boiler, the dampers 5 and 6 provided at the inlet and / or outlet of each of the plurality of gas passages 4 arranged in parallel are sequentially closed for each room. Hammering is performed by setting the charge of the dust collecting electrode plate in the gas flow path 4 to zero, and the rated exhaust gas flow rate is subjected to the dust collection processing without any trouble using the gas flow paths 4 in all other rooms.

If the gas flow rate exceeds the rated gas flow rate during overshoot in the boiler load raising process, as shown in FIG. 1, the exhaust gas is guided to the gas passages 4 of all the rooms to collect dust. Shall not periodically hammer the collecting electrode plate.

For example, when the dry electric precipitator 2 is provided with eight gas channels 4 having the same volume, the gas is passed through the seven chambers during normal operation in which the rated gas flow rate is introduced into the dry electric precipitator 2. During the overshoot in the load increasing process (FIG. 3), the gas flows through all eight chambers. In this example, the total space of the gas flow path group has a margin of 8/7 = 1.14 times (14%) with respect to the increase of the gas flow rate at the time of the overshoot. The rate of increase in the gas flow rate at the time of shooting may vary depending on the load rising speed, or is about 10%, so that the space can sufficiently cope with the above.

In the case of overshooting according to the prior art, when the dust concentration at the outlet of the dry-type electrostatic precipitator is overdesigned so as not to exceed the regulation value, about 10% is added to the overdesigned amount (14%) of the present invention and further overdesigned additional amount. However, in the case of the present invention, it is possible to save about 10% of this extra design addition. However, it is conceivable that dust collection efficiency is reduced by not hammering the dust collecting electrode plate during overshoot. However, since the overshoot time is about 5 minutes, this overshoot time is different from that in normal operation. The hammering time of the current collector plate in the room, for example, if hammering work is performed every two hours in eight sections, it is shorter than about 15 minutes or more. The reduction in dust collection efficiency is within a negligible range.

As shown in FIG. 4, the controller 13 predicts the timing of overshoot on the basis of the load signal 11 from the boiler and a predetermined boiler load rise pattern (pattern shown in FIG. 3) signal 12, and the overshoot is predicted. Before the chute, the damper opening / closing device 14 is driven to fully open the dampers 5 and 6 provided at the entrance and / or the exit of each chamber, and the exhaust gas is guided to all the chambers of the dry electric dust collector 2 to collect dust. By doing so, it is possible to reliably cope with an increase in gas flow rate during overshoot.

In normal operation, the rated operation pattern 1
5 is selected, the dampers 5 and 6 of each gas flow path 4 are sequentially closed, and the current collecting electrode plate in the gas flow path is hammered. In this way, the dry electric precipitator 2 can be operated without being over-designed, and the dust concentration at the outlet of the dry electric precipitator 2 does not exceed the regulation value during overshoot.

[0022]

According to the present invention, the dry electric precipitator is not overdesigned during normal operation, and the dry electric precipitator outlet dust concentration at the time of overshoot does not exceed the regulation value. The operation of the dust device becomes possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a dry electric precipitator according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a dry electric precipitator according to an embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a boiler load rising elapsed time and a boiler processing gas flow rate.

FIG. 4 is a control system diagram of the dry electric precipitator according to the embodiment of the present invention.

FIG. 5 is an explanatory view of a conventional dry-type electrostatic precipitator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust gas 2 Dry-type electrostatic precipitator 3 Processing gas 4 Gas flow path (chamber) 5, 6 Damper 11 Load signal 12 Load rise pattern 13 Control device 14 Damper opening / closing device 15 Rated operation pattern

Claims (6)

[Claims] 1. A gas flow path group provided in an exhaust gas flow path discharged from a combustion device, divided into a plurality of chambers and arranged in parallel, and a gas provided for each inlet and / or outlet of each gas flow path. In a dry-type electrostatic precipitator equipped with a damper that shuts off the flow, the gas flow path that performs the hammering operation during the regular hammering operation for each gas flow path at the rated gas flow rate If the gas flow exceeds the rated gas flow at the time of overshoot due to an increase in the load of the combustion device, the exhaust gas flows to all the chambers by closing the dampers provided at the inlet and / or outlet of And performing dust collection while the hammering of the dust collecting electrode plate in each chamber is not performed during this period. 2. An overshoot timing is predicted based on a load signal of a combustion device and a predetermined load rise pattern of the combustion device. 2. The method for operating a dry electric dust collecting apparatus according to claim 1, wherein the exhaust gas is guided to the gas passages of all the rooms by fully opening the damper provided at the outlet to collect dust. 3. A gas flow path group provided in an exhaust gas flow path discharged from a combustion device, divided into a plurality of chambers and arranged in parallel, and a gas provided for each inlet and / or outlet of each gas flow path. In a dry-type electrostatic precipitator equipped with a damper that shuts off the flow, the sum of the dust-collecting loads of the gas passages in all the rooms other than the room where the dust-collecting electrode plate is hammered corresponds to the rated gas flow rate. A dry-type electrostatic precipitator characterized in that the total dust-collecting load of the gas flow passages in all the chambers in a state where no chamber for hammering the electrode plate is provided corresponds to the gas flow rate during overshoot. . 4. An exhaust gas treatment device comprising the dry electric precipitator according to claim 3, disposed in a flow path of exhaust gas discharged from the combustion device. 5. A gas flow path group provided in an exhaust gas discharged from a combustion device, divided into a plurality of chambers and arranged in parallel, and a gas flow provided for each inlet and / or outlet of each gas flow path. In a dry-type electrostatic precipitator equipped with a shut-off damper, when it is determined that the gas flow rate is the rated gas flow rate based on the load signal from the combustion device, the dust collection electrode is periodically and periodically repeated for each gas flow path according to the rated operation pattern signal. In order to make a hammer,
When it is determined that the boiler load has risen based on a load signal from the combustion device, the damper provided at the inlet and / or outlet of the gas flow path for hammering the dust collection electrode plate is closed to shut off the gas flow path. Predict the timing of overshoot based on a predetermined boiler load rise pattern signal, and fully open the dampers provided at the entrance and / or exit of all rooms before overshoot to introduce gas into all gas flow paths A control device for performing control to perform the control, and an entrance and / or an entrance of each room that is driven and controlled by the control device
Or an opening / closing device for opening / closing a damper provided at an outlet, respectively. 6. An exhaust gas treatment device, wherein the dry type electrostatic precipitator according to claim 5 is arranged in a flow path of exhaust gas discharged from the combustion device.