JP2013252477A - Power control device and method for electric dust collection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To save power while maintaining dust collection efficiency for dust containing a heavy metal.SOLUTION: A power control device for a wet type electric dust collection device 1 includes a DC high voltage control part 42. The DC high voltage control part 42 performs the variable control of a DC high voltage applied to a discharge electrode of the wet type electric dust collection device according to a density of fine particles. The DC high voltage control part 42 includes a density decision part 51. The density decision part 51 detects a present value of a current of the wet type electric dust collection device 1, and decides the density of the fine particles based on the detected present value of the current. The DC high voltage control part 42 performs the variable control of the DC high voltage according to the density decided by the density decision part 51.

Description

  The present invention relates to a power supply control apparatus and method for an electrostatic precipitator that removes dust and the like from waste gas. In particular, the present invention relates to a power supply control device and method for a wet type electrostatic precipitator that can save power while maintaining the dust collection efficiency of dust containing heavy metals.

  Conventionally, wet electrostatic precipitators (see, for example, Patent Documents 1 to 3) remove harmful dust and mist from waste gas generated in waste incineration processes as well as sulfuric acid mist treatment and aluminum refining exhaust gas treatment in the mining industry. It is used for the purpose of collecting. As described above, the wet type electrostatic precipitator is widely used as a useful device from the viewpoint of air pollution prevention and environmental protection.

  To-be-processed waste gas processed by a wet electrostatic precipitator contains harmful substances such as lead, cadmium and arsenic and heavy metals. For this reason, in such a wet electrostatic precipitator, it is required to increase the dust collection efficiency of dust containing harmful substances and heavy metals.

The wet type electrostatic precipitator generally has a dust collecting electrode having a smooth surface composed of two flat plate types or a cylindrical shape such as a cylindrical shape or a rectangular tube shape, and a linear shape provided in the dust collecting electrode. The discharge line is configured to be included.
When fine particles such as dust and mist are removed by such a wet electrostatic precipitator, a high voltage is charged between the discharge electrode side and the grounded collection electrode side. As a result, a strong current electric field is formed between the discharge electrode side and the grounded dust collection electrode side, and a strong corona discharge is generated from the discharge electrode side as the voltage rises. The dust collection space between the two is filled with negative ions and electrons. When exhaust gas is introduced into the dust collection space, dust and mist in the exhaust gas are negatively charged, move toward the dust collection electrode by the Coulomb force with an electrostatic aggregating action, and adhere to the dust collection electrode. The adhering dust or mist loses a negative charge at the dust collecting electrode, is peeled off from the dust collecting electrode by the washing water and its own weight supplied to the dust collecting electrode, and is discharged to the outside of the electric dust collector.
In this way, the wet electrostatic precipitator can collect various types of solids, fine particles such as liquid fine particles, etc. with high dust collection efficiency.

  In such a wet electrostatic precipitator, a technique for increasing the charging voltage between the discharge electrode and the dust collection electrode is known in order to increase the dust collection efficiency of dust containing heavy metals.

JP 2007-196159 A JP 2002-119889 A Japanese Patent Publication No. 6-91965

  However, simply increasing the charging voltage between the discharge electrode and the dust collecting electrode of the wet type electrostatic precipitator can improve the dust collecting efficiency, but is extremely uneconomical in terms of power saving. On the other hand, if the charging voltage is simply lowered, the dust collection efficiency of dust and the like is reduced, and thus dust and the like cannot be sufficiently removed from the waste gas.

  This invention is made | formed in view of such a condition, and it aims at achieving power saving, maintaining the dust collection efficiency of the dust containing a heavy metal.

A power supply control device for an electrostatic precipitator according to one aspect of the present invention,
A discharge electrode to which a DC high voltage is applied;
A dust collecting electrode for collecting fine particles by a negative corona discharge generated between the discharge electrode and the DC high voltage;
A power control device for an electric dust collector, comprising:
A DC high voltage controller that variably controls a DC high voltage applied to the discharge electrode according to the concentration of the fine particles,
It is characterized by providing.

In this case, the DC high voltage controller is
A concentration determination unit that detects a current value of the current of the electrostatic precipitator and determines the concentration of the fine particles based on the current value of the current, and according to the concentration determined by the concentration determination unit, DC high voltage can be variably controlled.

In addition, the concentration determination unit
A concentration increase determination unit that determines that the concentration of the fine particles has increased when the current value of the current is equal to or less than a first threshold;
A concentration decrease determination unit that determines that the concentration of the fine particles has decreased when the current value of the current is equal to or greater than a second threshold;
With
The direct current high voltage controller is
When it is determined by the concentration increase determination unit that the concentration of the fine particles has increased, control is performed to increase the DC high voltage applied to the electrostatic precipitator,
When it is determined by the concentration decrease determination unit that the concentration of the fine particles has decreased, control is performed to decrease the DC high voltage applied to the electrostatic precipitator.
be able to.

The direct current high voltage control unit
When it is determined by the concentration increase determination unit that the concentration of the fine particles has increased, a DC high voltage applied to the electrostatic precipitator is controlled to a first voltage value,
When it is determined by the concentration decrease determination unit that the concentration of the fine particles has decreased, control is performed so that the DC high voltage applied to the electrostatic precipitator is a second voltage value lower than the first voltage value. ,
be able to.

A power supply control method for an electrostatic precipitator according to one aspect of the present invention includes:
A discharge electrode to which a DC high voltage is applied;
A dust collecting electrode for collecting fine particles by a negative corona discharge generated between the discharge electrode and the DC high voltage;
A power control method executed by a power control device for an electrostatic precipitator comprising:
The method may include a step of variably controlling a DC high voltage applied to the discharge electrode in accordance with the concentration of the fine particles.

  ADVANTAGE OF THE INVENTION According to this invention, the wet electric dust collector which can aim at power saving can be implement | achieved, maintaining the dust collection efficiency of the dust containing a heavy metal.

It is a figure which shows the structural example of the dust collection system which concerns on one Embodiment of this invention. It is sectional drawing which shows schematic structure of the wet electric dust collector which concerns on one Embodiment of this invention. It is a perspective view which shows schematic structure inside the housing of a wet electric dust collector. It is a figure explaining the space charge effect by the microparticles | fine-particles which exist in the gas input into each "chamber" of the dust collection electrode of an electric dust collector. It is a figure which shows the relationship between the electric current dust collector's electric current and voltage (DC high voltage V1) at the time of air loading and gas loading. It is a figure explaining the specific example of the variable control of the charging voltage by a direct-current high voltage control part. It is a figure which shows the state transition of a power supply control apparatus. It is a figure which shows the example of a display of the input screen of TP.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[Configuration of dust collection system]
FIG. 1 is a diagram illustrating a configuration example of a dust collection system according to an embodiment of the present invention.

A dust collection system S shown in FIG. 1 includes a wet electric dust collection device 1, a power supply device 2, and a power supply control device 3, and is connected to an external system 4.
Hereinafter, each structure of the wet electrostatic precipitator 1, the power supply device 2, and the power supply control device 3 will be individually described in that order.

[Configuration of wet electrostatic precipitator]
First, the configuration of the wet electrostatic precipitator 1 will be described with reference to FIG.
FIG. 2 is a cross-sectional view showing a schematic configuration of a wet electrostatic precipitator according to an embodiment of the present invention.
Specifically, FIG. 2 (A) and FIG. 2 (B) are cross-sectional views showing a schematic configuration of the external appearance of the wet type electrostatic precipitator, and are cross-sectional views seen from different directions substantially perpendicular to each other.

  The wet electrostatic precipitator 1 is provided with an upper casing 11, a dust collecting electrode 12 that also functions as a side casing, a lower casing 13, and a frame 14.

  The casing of the wet electrostatic precipitator 1 is configured by combining the upper casing 11, the dust collecting electrode 12, and the lower casing 13 in that order from above. The casing of the wet electrostatic precipitator 1 is fixed by a frame 14 so as to be spaced apart from the ground by a predetermined distance. In the present embodiment, conductive FRP (Fiber Reinforced Plastics) is adopted as the material of the casing of the wet electrostatic precipitator 1.

FIG. 3 is a perspective view illustrating a schematic configuration inside the housing of the wet electrostatic precipitator 1.
As shown in FIG. 3, inside the housing of the wet electrostatic precipitator 1, an upper grid 21, the above-described dust collecting electrode 12, a lower grid 23, an electrode rod 24, a discharge wire 25, a weight 26, An upward spray nozzle 27 and a cleaning pipe 28 are provided.

  As shown in FIG. 3, the upper grid 21, the dust collection electrode 12, and the lower grid 23 are spaced apart from each other by a predetermined distance in that order from above, and are substantially parallel to each other in the horizontal direction. It is arranged.

As shown in FIG. 3, the dust collecting electrode 12 is configured by repeatedly arranging a plurality of “chambers” with a rectangular tube as a unit (hereinafter, such units are referred to as “chambers”). .
Specifically, hereinafter, one of the substantially horizontal directions is referred to as “vertical direction”, and a direction perpendicular to the vertical direction is referred to as “lateral direction”. In this case, by repeatedly arranging N units in the vertical direction and repeating M units in the horizontal direction (hereinafter referred to as “N × M”), the dust collection electrode 12 is configured.
Here, N and M are arbitrary independent integer values. In the present embodiment, as shown in FIG. 3, the number of “chambers” of the dust collection electrode 12 is N × M = 9 × 9. ing.
Moreover, the chamber of the present embodiment is a square tube having sides with a length of 35 to 50 cm.
In this embodiment, conductive FRP is adopted as the material of the dust collection electrode 12.

In this embodiment, the discharge electrode for the dust collecting electrode 12 is constituted by an electrode rod 24 and a discharge wire 25.
As shown in FIG. 3, the electrode rod 24 is disposed so as to penetrate the center inside a predetermined “chamber” of the dust collecting electrode 12 in a substantially vertical direction, and has an upper end fixed to the upper grid 21 and a lower end. Is fixed to the lower grid 23.
As shown in FIG. 3, the discharge line 25 is suspended from the upper grid 21 and is disposed so as to penetrate the center inside of a predetermined “chamber” of the dust collecting electrode 12 in a substantially vertical direction. The discharge line 25 is also connected to a weight 26 provided on the upper part of the lower grid 23 so as to have a tension that does not loosen.

  A negative DC high voltage (charge voltage) supplied from the power supply device 2 is directly applied to the electrode rod 24. On the other hand, the negative DC high voltage is applied to the discharge line 25 via the upper grid 21.

  The upward spray nozzle 27 is disposed above the four corners of each “chamber” of the dust collecting electrode 12 and ejects cleaning water flowing through the cleaning pipe 28 as a fine mist in a substantially vertical upward direction. Thereby, fine particles such as mist and dust adhering to the dust collecting electrode 12 can be cleaned and removed.

In the wet electrostatic precipitator 1 of the present embodiment, the washing water is ejected from the upward spray nozzle 27 as a fine mist in a substantially vertical upward direction. Thereby, since dispersion | distribution of washing water becomes good, the quantity of washing water used can be reduced from the quantity of water used conventionally.
The upward spray nozzle 27 is a component that contributes to an increase in negative DC high voltage applied to the electrode rod 24 and the discharge line 25.

  Next, referring to FIG. 1 again, the configuration of the power supply device 2 that applies the negative DC high voltage V to the electrode rod 24 of the wet electrostatic precipitator 1 will be described.

  As shown in FIG. 1, the power supply device 2 generates a negative DC high voltage V in accordance with a voltage setting value supplied from a power supply control device 3 to be described later, and applies it to the electrode rod 24 of the wet electrostatic precipitator 1. Apply. The current values of the voltage and current of the wet electrostatic precipitator 1 are fed back to the power supply control device 3 and used appropriately for the control described later.

A switch 31, a volume 32, and a display unit 33 are provided on the panel of the power supply device 2 in order from the bottom.
The change-over switch 31 is a switch that switches the control of the power supply apparatus 2 from one of “far” and “direct” to the other. When the changeover switch 31 is switched to “far”, the power supply device 2 is remotely controlled by the power supply control device 3 described later. On the other hand, when the changeover switch 31 is switched to “directly”, the power supply device 2 is controlled by a direct panel operation by an operator (not shown) in the vicinity.
The volume 32 is operated by the operator when the changeover switch 31 is switched to “direct”, and gives an instruction to change the voltage setting value or the current setting value. That is, when the changeover switch 31 is switched to “far”, the operation of the volume 32 is prohibited.
The display unit 33 displays the current values of the voltage and current of the wet electrostatic precipitator 1.

  Next, the configuration of the power supply control device 3 that controls the power supply device 2 will be described with reference to FIG.

  The power supply control device 3 is configured by, for example, a programmable logic controller (PLC), and includes a TP (touch panel) 41 and a DC high voltage control unit 42.

  The TP 41 is stacked on a display screen that displays various types of information, and inputs various types of information in accordance with user instruction operations. Details of the input screen of TP41 will be described with reference to FIG.

The direct-current high-voltage control unit 42 determines the value of the charging voltage from the power supply device 2 according to the concentration of fine particles (dust, dust, etc.) contained in the gas (gas G1 in FIG. 2) input to the wet electrostatic precipitator 1. Is variably controlled.
The DC high voltage control unit 42 functionally includes a concentration determination unit 51 in order to variably control the charging voltage in accordance with the concentration of such fine particles.
Here, it is described functionally because it is not necessary to limit the implementation form of the density determination unit 51 to hardware. That is, it is sufficient that the density determination unit 51 has the following functions, and its implementation is not particularly limited, and may be configured by hardware, software, or a combination thereof. It may be constituted by.

The concentration determination unit 51 has a function of determining the concentration of fine particles. The implementation form of the function is not particularly limited, and may be a function of actually measuring the concentration of fine particles. However, in this embodiment, a current electric field formed between the discharge electrode side and the grounded dust collecting electrode 12 side. A function for estimating the concentration of the fine particles by detecting the current of the corona discharge generated by is provided in the concentration determination unit 51. In other words, the function of detecting the current as an index of the concentration of the fine particles is provided in the concentration determination unit 51.
Hereinafter, the function provided in the concentration determination unit 51, that is, the function of detecting the current as an index of the concentration of the fine particles will be described in detail with reference to FIGS.

FIG. 4 is a diagram for explaining the space charge effect due to the fine particles present in the gas input to each “chamber” of the dust collecting electrode 12 of the wet electrostatic precipitator 1.
In the following description, “air load” refers to a state in which fine particles (dust collection target) such as dust and dust are not included in the gas input to each “chamber” of the dust collecting electrode 12 of the wet electrostatic precipitator 1. A state in which fine particles (dust collection target) such as dust and dust are included in a certain amount or more is called “gas load”.
As shown in FIG. 4 (1), during the air load, a high DC current is applied between the electrode rod 24 or the discharge wire 25 (hereinafter, only the discharge wire 25 will be referred to for convenience of explanation) and the grounded collector electrode 12 side. When the voltage V is applied, a strong current electric field is formed between the discharge wire 25 side and the grounded dust collecting electrode 12 side, and a vigorous corona discharge is generated from the discharge wire 25 side as the voltage rises. To do.
On the other hand, as shown in FIG. 4B, the concentration of fine particles such as dust in the gas (gas G1 in FIG. 2) input to the opening of each “chamber” of the dust collecting electrode 12 during gas loading. Becomes higher, a large amount of space charges (negative ions i) are formed in the dust collection space in the “chamber”. Then, the corona discharge in the vicinity of the discharge line 25 is suppressed by the shielding effect by these large amount of space charges. Suppression of corona discharge by such a large amount of space charge is generally referred to as “space charge effect” or “corona blocking phenomenon”. This space charge effect (corona blocking phenomenon) is more likely to occur as the concentration of fine particles such as dust in the gas G1 (gas) increases and as the particle diameter of the fine particles decreases.

Next, with reference to FIG. 5, the relationship between the electric current and voltage of the wet electrostatic precipitator 1 which changes according to the concentration of the fine particles will be described.
FIG. 5 is a diagram showing the relationship between the current and voltage (DC high voltage V1) of the wet electrostatic precipitator 1 during air loading and gas loading.
Specifically, a curve L1 showing the relationship between the current and voltage during air loading and a curve L2 showing the relationship between the current and voltage (DC high voltage V1) during gas loading are shown.
In FIG. 5, the vertical axis represents the current of the wet electrostatic precipitator 1, and the horizontal axis represents the effective voltage of the charging voltage (DC high voltage V1) of the wet electrostatic precipitator 1.
When the DC high voltage of the wet electrostatic precipitator 1 is a constant value V1a (V1a is an arbitrary value less than or equal to the rated voltage), the curve L2 at the time of gas loading where the concentration of fine particles is high is higher than the concentration of fine particles. Is located below the curve L1 when the air load is low. From this, when the DC high voltage of the wet electrostatic precipitator 1 is a constant value V1a, the concentration of the fine particles decreases as the current value increases, and conversely increases as the current value decreases. I understand.
Therefore, in the present embodiment, as described above, a current is detected as an index of the concentration of fine particles, and the value of the DC high voltage V1 is variably controlled according to the detected current value.

More specifically, as can be seen from the curve L2 during gas loading, the higher the concentration of the fine particles in the gas G1 (gas), the lower the current value of the wet electrostatic precipitator 1 due to the space charge effect. Therefore, the concentration determination unit 51 determines the concentration of fine particles such as dust in the gas G1 (gas) when the current value of the wet electrostatic precipitator 1 (current value of the current supplied from the power supply device 2) is low. Can be determined to be high.
On the other hand, as can be seen from the curve L1 during air loading, the lower the concentration of the fine particles in the gas G1 (gas), the higher the current value of the wet electrostatic precipitator 1 due to the space charge effect. Therefore, the concentration determination unit 51 determines the concentration of fine particles such as dust in the gas G1 (gas) when the current value of the wet electrostatic precipitator 1 (current value of the current supplied from the power supply device 2) is high. Can be determined to be low.

  Next, a specific example of variable control of the charge voltage by the DC high voltage control unit 42 applied to the present embodiment will be described with reference to FIG.

FIG. 6 is a diagram illustrating a specific example of variable control of the charging voltage by the DC high voltage control unit 42.
FIG. 6 shows a curve L3 that shows the relationship between the current and voltage during air loading, and a curve L4 that shows the relationship between the current and voltage (DC high voltage V1) during gas loading.
In FIG. 6, the vertical axis indicates the current of the wet electrostatic precipitator 1, and the horizontal axis indicates the effective voltage of the charging voltage (DC high voltage V1) of the wet electrostatic precipitator 1.
In the present embodiment, the effective voltage of the charging voltage (DC high voltage V1) of the wet electrostatic precipitator 1 is assumed to take a binary value of an energy saving voltage value V12 and a normal voltage value V11 (V11> V12).
Here, in the present embodiment, as shown in FIG. 1, the concentration determination unit 51 includes a concentration increase determination unit 61 and a concentration decrease determination unit 62 in order to realize such variable control illustrated in FIG. 6. Prepare. The concentration increase determination unit 61 determines that the concentration of the fine particles has increased when the current value (current value of the current supplied from the power supply device 2) is equal to or lower than the first threshold C1 (see FIG. 6). . When the current becomes equal to or lower than the first threshold C1, the concentration of the fine particles becomes higher than a certain level, so that the dust collection efficiency of the fine particles needs to be increased. Therefore, the DC high voltage control unit 42 increases the charging voltage (DC high voltage V1) of the power supply device 2 from the energy saving voltage value V12 to the normal voltage value V11 when the current becomes equal to or less than the first threshold C1. The dust collection efficiency is improved by performing control, more specifically, control for increasing the voltage set value.
On the other hand, the concentration decrease determination unit 62 determines that the concentration of the fine particles has decreased when the current value (current value of the current supplied from the power supply device 2) is equal to or greater than the second threshold C2. When the current is equal to or higher than the second threshold value C2, the concentration of the fine particles is low, so that it is not necessary to increase the dust collection efficiency of the fine particles. Therefore, when the current becomes equal to or higher than the second threshold C2, the DC high voltage control unit 42 decreases the charging voltage (DC high voltage V1) of the power supply device 2 from the normal voltage value V11 to the energy saving voltage value V12. Power is saved by controlling.

As described above, when the current value becomes the first threshold value C1 or less and the concentration of the fine particles becomes higher than a certain level, the charging voltage (DC high voltage V1) of the power supply device 2 becomes the normal voltage value V11, and the collection of fine particles. Dust efficiency is improved.
Here, although the current value is equal to or higher than the second threshold C2 and the concentration of the fine particles is low, the charged voltage (DC high voltage V1) of the power supply device 2 is excessive if the normal voltage value V11 remains unchanged. A large charge voltage is applied, and power is wasted. Therefore, in such a case, the charging voltage (DC high voltage V1) of the power supply device 2 is lowered to the energy saving voltage value V12, so that power saving can be achieved.

Note that, during abnormal discharge, the power supply device 2 prevents the occurrence of spark discharge by reducing the value of the DC high voltage V1 for a short time.
However, a decrease in the value of the DC high voltage V1 during an abnormal discharge causes a decrease in the current value. Therefore, regardless of the concentration of the fine particles (even when the concentration of the fine particles does not change), even when the abnormal discharge occurs and the value of the DC high voltage V1 is reduced, If the current value is equal to or lower than the first threshold C1, there is a possibility that it is erroneously determined that the concentration of the fine particles has increased.
Therefore, in order to prevent such erroneous determination, the concentration determination unit 51 prohibits detection of changes in the concentration of the fine particles while the value of the DC high voltage V1 is reduced due to abnormal discharge.

[Operation of wet electrostatic precipitator]
Next, with reference to FIG. 7, operation | movement of the dust collection system S of this embodiment of the above structure is demonstrated.
FIG. 7 is a diagram illustrating state transition of the power supply control device.
In FIG. 7, each state is indicated by one ellipse, and is determined by a code including “S” drawn on the ellipse.
The state transition from one state to one state is executed when a predetermined condition (hereinafter referred to as “transition condition”) is satisfied.
In FIG. 7, such a transition condition is represented by adding a symbol including “T” to an arrow representing a transition from one state to one state.

Hereinafter, each of the states S1 to S3 will be described.
The standby state S1 is an initial stage state where the power supply of the power supply control device 3 is turned on, and is still in a standby state with the charged voltage (voltage set value) being 0V.
In the normal voltage state S2, when the concentration of the fine particles in the gas G1 (gas) is high, the charging voltage (voltage set value) is set to the normal voltage value V11 in order to increase the dust collection efficiency and remove these fine particles. It is in a state.
The energy saving voltage state S3 is a state in which the charged voltage (voltage set value) is set to the energy saving voltage value V12 in order to suppress the amount of power consumed when the concentration of the fine particles in the gas G1 (gas) becomes low. is there. The energy saving voltage value V12 is defined as a value that can reduce the concentration of impurities such as fine particles to a target value or less even if the dust collection efficiency of the fine particles is lowered.

  Hereinafter, the transition conditions T1 to T5 for transition to the states S1 to S3 will be described.

  Transition condition T1: A condition for making a transition from the standby state S1 to the normal voltage state S2. In the standby state S1, a switch (not shown) for instructing the start of dust collection is turned on or an external system This is satisfied when the activation signal transmitted from 4 is received.

  Transition condition T2: a condition for transition from the normal voltage state S2 to the energy saving voltage state S3, which is satisfied when the current value of the current becomes equal to or greater than the second threshold C2 (see FIG. 6) in the normal voltage state S2. It is.

  Transition condition T3: a condition for transitioning from the energy saving voltage state S3 to the normal voltage state S2, which is satisfied when the current value of the current is equal to or lower than the first threshold C1 (see FIG. 6) in the energy saving voltage state S3. It is.

  Transition condition T4: a condition for transition from the normal voltage state S2 to the standby state S1, and in the normal voltage state S2, when a switch (not shown) for instructing the start of dust collection is turned off or external It is satisfied when a stop signal transmitted from the system 4 is received.

  Transition condition T5: This is a condition for transition from the energy saving voltage state S3 to the standby state S1. In the energy saving voltage state S3, a switch (not shown) for instructing the start of dust collection is turned off or externally. It is satisfied when a stop signal transmitted from the system 4 is received.

  Here, the external system 4 is a system that controls the entire process that involves generation of exhaust gas, and exchanges various types of information through communication with the power supply control device 3. For example, the external system 4 transmits an activation signal of the dust collection system S to the power supply control device 41 when a predetermined condition is satisfied.

When the activation signal transmitted from the external system 4 is received in the standby state S1, or when a switch (not shown) for instructing the start of dust collection is turned on, the transition condition T1 is When satisfied, the state of the power supply control device transitions from the standby state S1 to the normal voltage state S2.
Then, the direct-current high voltage control unit 42 sets the normal voltage value V11 to the voltage set value and notifies the power supply device 2 of it. Although the form of notification is not particularly limited, the present embodiment employs a technique for notifying the voltage setting value by transmitting a level signal that varies between 4 and 20 mA according to the voltage setting value. That is, voltage values are associated with each other in the range of 4 to 20 mA, and the voltage value corresponding to the level (current value) of the level signal is notified from the DC high voltage control unit 42 to the power supply device 2 as a voltage setting value.
The power supply device 2 generates the DC high voltage V1 so as to be the notified voltage setting value, that is, the normal voltage value V11 here, and applies it to the wet electrostatic precipitator 1.

While the normal voltage state S2 is continuing, the exhaust gas is stopped by stopping the process controlled on the external system 4 side, and the concentration of fine particles in the gas G1 (gas) decreases. When the current value of the current notified from the power supply device 2 rises and exceeds the second threshold C2, the transition condition T2 is satisfied, and the state of the power supply control device 3 changes from the normal voltage state S2 to the energy saving voltage state S3. Transition.
Then, the direct current high voltage control unit 42 sets the energy saving voltage value V12 to the voltage setting value (updates the setting), and notifies the power supply device 2 of it. The power supply device 2 generates the DC high voltage V1 so that the notified voltage setting value, that is, here the energy saving voltage value V12, is applied, ie, the DC high voltage V1 is reduced and applied to the wet electrostatic precipitator 1. .

While the energy-saving voltage state S3 is continuing, the concentration of fine particles in the gas G1 (gas) increases due to the exhaust gas being regenerated by restarting the process controlled on the external system 4 side. Accordingly, when the current value of the current notified from the power supply device 2 decreases and falls below the first threshold value C1, the transition condition T3 is satisfied, and the state of the power supply control device 3 changes from the energy saving voltage state S3 to the normal voltage state S2. Transition to.
Then, the DC high voltage control unit 42 sets the normal voltage value V11 to the voltage setting value (updates the setting), and notifies the power supply device 2 of it. The power supply device 2 generates the DC high voltage V1 so as to be the notified voltage setting value, that is, the normal voltage value V11 here, that is, raises the DC high voltage V1 and applies it to the wet electrostatic precipitator 1. .

  Note that when the switch (not shown) for instructing the start of dust collection is turned off in the normal voltage state S2 or the energy saving voltage state S3, or a stop signal transmitted from the external system 4 is received. In this case, the transition condition T4 or T5 is satisfied, and the state of the power supply control device 3 transitions from the normal voltage state S2 or the energy saving voltage state S3 to the standby state S1.

[Example of TP display]
Next, a display example of the input screen of TP41 of the power supply control device 3 of the present embodiment having the above configuration will be described.
FIG. 8 is a diagram illustrating a display example of the TP input screen.

The control state of the power supply device 2 is displayed in the upper left column of TP41. That is, the display in the upper left column corresponds to the state of the changeover switch 31 on the panel surface of the power supply device 2.
In the upper right column of TP41, current values of voltage and current notified from the power supply device 2 are displayed. In the example of the figure, “50” kv is displayed as the current value of the voltage, and “700” mA is displayed as the current value of the current. That is, the display in the upper right column corresponds to the state of the display unit 33 on the panel of the power supply device 2.

In the middle column of TP41, set values of the normal voltage state S2 and the energy saving voltage state S3 are displayed, respectively.
In the example of the figure, “60” kv is the charge voltage in the normal voltage state S2, “900” mA is the second threshold value C2, and “0” minutes are the normal remaining time of the normal voltage state S2. “3” is set as the duration setting value of the voltage state S2.
Further, “50” kv as the charge voltage in the energy saving voltage state S3, “600” mA as the first threshold C1, and “0” as the remaining duration time of the energy saving voltage state S3 are the continuation of the energy saving voltage state S3. “1” is set as the time setting value.

[Effects of wet electrostatic precipitator of this embodiment]
In summary, the dust collection system S of the present embodiment can provide the following advantageous effects (1) to (5) as compared with the conventional dust collection system.

(1) Conventionally, increasing the charging voltage of a wet electrostatic precipitator can increase the efficiency of dust collection, but it is uneconomical because of the large amount of power consumed, and energy saving is required these days. The result was against the circumstances. On the other hand, if the charging voltage is simply lowered, the collection efficiency of fine particles, dust and the like is lowered, so that the fine particles and dust cannot be sufficiently removed from the waste gas.
On the other hand, in this embodiment, the power supply control device 3 variably controls the charging voltage according to the concentration of the fine particles. Thereby, power saving can be achieved while maintaining the dust collection efficiency of fine particles containing heavy metals and dust while achieving power saving by suppressing the DC high voltage applied excessively.

(2) In this embodiment, the DC high voltage control unit 42 variably controls the DC high voltage applied according to the current detected by the concentration determination unit 51.
As a result, it is possible to supply the optimum DC high voltage corresponding to the concentration of the fine particles. Therefore, when the concentration of the fine particles is low, the DC high voltage applied excessively is suppressed to achieve power saving. can do. Furthermore, when the concentration of the fine particles is high, by supplying a sufficient direct current high voltage, it is possible to save power while maintaining the collection efficiency of the fine particles containing heavy metals and dust.

(3) Further, in the present embodiment, when the DC high voltage control unit 42 determines that the current rises below the first threshold C1 and the concentration of the fine particles has increased by the concentration increase determination unit 61, the power supply device 2 Control for increasing the charging voltage is performed.
On the other hand, the direct current high voltage control unit 42 performs control to decrease the charged voltage of the power supply device 2 when the concentration decrease determination unit 62 determines that the current is equal to or higher than the second threshold C2 and the concentration of the fine particles has decreased. Is done.
Thereby, the fluctuation | variation of the density | concentration of microparticles | fine-particles is determined by determining the up-and-down movement of an electric current. And when it determines with the density | concentration of microparticles | fine-particles rising, the improvement of the dust collection efficiency of microparticles | fine-particles containing heavy metal and dust can be aimed at by supplying sufficient DC high voltage. Furthermore, when it is determined that the concentration of the fine particles has decreased, it is possible to achieve power saving by suppressing the supply of excessively applied DC high voltage.

(4) Moreover, in this embodiment, when it determines with the direct-current high voltage control part 42 having increased the density | concentration of microparticles | fine-particles, control which makes a direct current | flow high voltage 1st voltage value is performed. On the other hand, when it is determined that the concentration of the fine particles has decreased, the DC high voltage control unit 42 performs control to set the DC high voltage to a second voltage value lower than the first voltage value. Thereby, when it is determined that the concentration of the fine particles has increased, the collection efficiency of the fine particles containing heavy metals and dust can be improved by setting the first voltage value to be a sufficient voltage value. Furthermore, when it is determined that the concentration of the fine particles has decreased, power saving can be achieved by setting the second voltage value in which the DC high voltage is suppressed rather than the first voltage value.

(5) In the present embodiment, the power supply device 2 generates a DC high voltage by reducing the current for a predetermined time during abnormal discharge. Then, the concentration determination unit 51 does not detect a change in the concentration of the fine particles within a predetermined time during which the current is reduced during abnormal discharge.
Thereby, at the time of abnormal discharge in which excessive voltage is generated, the power supply device 2 can prevent spark discharge by reducing the current for a predetermined time. The concentration determination unit 51 reduces the current within a predetermined time period so that the concentration of the fine particles is not erroneously determined to be decreased due to the current being decreased by the power supply device 2 due to abnormal discharge. It does not detect changes in the concentration of fine particles. Therefore, even when abnormal discharge occurs, it is possible to improve dust collection efficiency while continuously achieving power saving.

  It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.

  For example, in the above-described embodiment, the DC high voltage control unit 42 variably controls the charging voltage by a type between the normal voltage value V11 and the energy saving voltage value V12, but the present invention is not limited to this. For example, the charging voltage that is variably controlled by the DC high voltage controller 42 can be variably controlled in multiple stages or in an analog manner, not in two stages.

Returning to FIG. 1, the concentration determination unit 51 includes a concentration increase determination unit 61 and a concentration decrease determination unit 62 in order to determine such a fine particle concentration index (current).
The concentration increase determination unit 61 determines that the concentration of the fine particles has increased when the current value (current value of the current supplied from the power supply device 2) is equal to or lower than the first threshold C1 (see FIG. 6). . In contrast, the concentration decrease determination unit 62 decreases the concentration of the fine particles when the current value (current value of the current supplied from the power supply device 2) is equal to or greater than the second threshold C2 (see FIG. 6). It is determined that
Then, the direct current high voltage control unit 42 controls to increase the charging voltage (direct current high voltage V1) of the power supply device 2, more specifically, when the concentration increase determination unit 61 determines that the concentration of the fine particles has increased. Control to increase the voltage setting value. On the other hand, the direct current high voltage control unit 42 controls to lower the charging voltage (direct current high voltage V1) of the power supply device 2 when the concentration decrease determination unit 62 determines that the concentration of the fine particles has decreased. Is controlled to lower the voltage set value.

  Moreover, in the said embodiment, although the direct-current high voltage control part 42 is comprised by PLC, it is not restricted to this, For example, it is also possible to set it as simple and cheap structures, such as a relay control board.

DESCRIPTION OF SYMBOLS 1 ... Wet electrostatic dust collector 2 ... Power supply device 3 ... Power supply control device 4 ... External system 11 ... Upper casing 12 ... Dust collection electrode 13 ... Lower casing 14 ...・ Frame 21: upper grid 23 ... lower grid 24 ... electrode rod 25 ... discharge line 26 ... weight 27 ... upward spray nozzle 28 ... cleaning pipe 31 ... switching Switch 32 ... Volume 33 ... Display unit 41 ... TP
42 ... DC high voltage control unit 51 ... concentration determination unit 61 ... concentration increase determination unit 62 ... concentration decrease determination unit

Claims (5)

A discharge electrode to which a DC high voltage is applied;
A dust collecting electrode for collecting fine particles by a negative corona discharge generated between the discharge electrode and the DC high voltage;
A power control device for an electric dust collector, comprising:
A DC high voltage controller that variably controls a DC high voltage applied to the discharge electrode according to the concentration of the fine particles,
A power supply control device for an electrostatic precipitator. The direct current high voltage controller is
A concentration determination unit that detects a current value of the current of the electrostatic precipitator and determines the concentration of the fine particles based on the current value of the current, and according to the concentration determined by the concentration determination unit, The power control apparatus for an electrostatic precipitator according to claim 1, wherein the DC high voltage is variably controlled. The concentration determination unit
A concentration increase determination unit that determines that the concentration of the fine particles has increased when the current value of the current is equal to or less than a first threshold;
A concentration decrease determination unit that determines that the concentration of the fine particles has decreased when the current value of the current is equal to or greater than a second threshold;
With
The direct current high voltage controller is
When it is determined by the concentration increase determination unit that the concentration of the fine particles has increased, control is performed to increase the DC high voltage applied to the electrostatic precipitator,
When it is determined by the concentration decrease determination unit that the concentration of the fine particles has decreased, control is performed to decrease the DC high voltage applied to the electrostatic precipitator.
The power supply control device for an electrostatic precipitator according to claim 2. The direct current high voltage controller is
When it is determined by the concentration increase determination unit that the concentration of the fine particles has increased, a DC high voltage applied to the electrostatic precipitator is controlled to a first voltage value,
When it is determined by the concentration decrease determination unit that the concentration of the fine particles has decreased, control is performed so that the DC high voltage applied to the electrostatic precipitator is a second voltage value lower than the first voltage value. ,
The power supply control device for an electrostatic precipitator according to claim 3. A discharge electrode to which a DC high voltage is applied;
A dust collecting electrode for collecting fine particles by a negative corona discharge generated between the discharge electrode and the DC high voltage;
A power control method executed by a power control device for an electrostatic precipitator comprising:
A power control method for an electrostatic precipitator, comprising the step of variably controlling a DC high voltage applied to the discharge electrode in accordance with the concentration of the fine particles.

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