JP2014087734A - Electric dust collector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a shape and a structure, which enable suppression of re-scattering and energy saving brought about by lengthening of a cleaning period, in an electric dust collector.SOLUTION: In an electric dust collector, a leeward end position of a load electrode plate 2 of a dust collection part 1 is located on a leeward side with respect to a leeward end position of a grounding electrode plate 3. The electric dust collector structurally enables re-scattering dust to be captured with an electrostatic force by the load electrode plate 2 at or behind the leeward end of the grounding electrode plate 3, even when the dust accumulated at the leeward end of the grounding electrode plate 3 by a gradient force becomes excessive and re-scatters. Thus, the effect of enabling suppression of re-scattering and energy saving can be obtained.

Description

  The present invention relates to an electrostatic precipitator that charges airborne particles in air and collects them by electrostatic force.

  Conventionally, this type of electrostatic precipitator applies a high DC voltage to the discharge electrode of the charging unit, generates a positive corona or a negative corona, and charges the dust passing through the charging unit with a positive or negative charge. . There is a wide range of technologies for collecting this charged dust on the surface of the grounding electrode plate with electrostatic force by the high electric field of the dust collector that has a discharge electrode to which a DC high voltage is applied and a grounding electrode plate connected to the ground. Generally known. (For example, refer to Patent Document 1).

  Hereinafter, the principle of the electrostatic dust collection and blowing will be described with reference to FIG.

  As shown in FIG. 15, the electrostatic precipitator includes a charging unit 104 and a dust collecting unit 105. The ventilation direction is the direction from the charging unit 104 to the dust collecting unit 105 (from left to right in FIG. 15). A DC high voltage of +11 kV and +8.3 kV is supplied from the DC high voltage power source 109 to the charging unit 104 and the dust collecting unit 105, respectively. The charging unit 104 includes a discharge wire type discharge electrode 104A and a ground electrode plate 104B. A DC high voltage of +11 kV is applied to the discharge electrode 104A, and a positive corona discharge is generated in the space between the discharge electrode 104A and the ground electrode plate 104B. Positive ions generated by the positive corona give a positive charge to dust (not shown) in the space, and the dust is positively charged. The charged dust is collected on the ground electrode plate 105B by electrostatic force due to a strong electric field formed between the load electrode plate 105A and the ground electrode plate 105B in the dust collection unit 105 in the subsequent stage (dust collection principle).

  In principle, in the dust collector 105 of such an electric dust collector, the load electrode plate 105A and the ground electrode plate 105B are electrode plates having substantially the same size and shape in order to secure a large equal electric field region. Thus, the load electrode plate 105A and the ground electrode plate 105B are arranged alternately and parallel to the wind direction so that the wind upper end and the wind lower end are aligned.

In addition, in Patent Document 1 specification paragraph 0011,
“When the dust collected on the ground electrode plate accumulates, the gap between the high-pressure electrode plate is reduced and spark discharge is likely to occur. Jump out into. "
“When dust that is positively charged at the charging part is collected on the ground electrode plate, it loses its charge, and it also has a negative polarity charge due to electrostatic induction. If it exceeds, it will be attracted by the electric field and jump out of the ground plate into space.
As described, re-scattering of the collected dust is an issue.

JP-A-9-225340

That is, in the electrostatic precipitator, “re-scattering” in which the dust collected by the dust collecting part is more or less separated and scattered in the air continues to exist as a fatal phenomenon. When the dust is re-scattered, the dust collection efficiency, which indicates the degree of dust collection, decreases, and there is a problem that the re-scattered particles with a charge adhere to the wall on the downstream side of the electrostatic precipitator and stain the wall. . Moreover, in order to reduce re-scattering, a countermeasure for shortening the cleaning cycle of the dust collection unit that has been operated is used, but there is a problem in that the amount of utility e (electricity / water) used is increased.

  On the other hand, in the conventional electric dust collector, there is a problem that the entire surface of the ground electrode plate is not efficiently utilized. In addition, a force different from the electrostatic force acts at the windward end of the electrode plate, and there is a problem that dust collected in this portion is re-scattered. In order to identify these issues, we conducted two operational surveys of conventional electrostatic precipitators. The results will be described below with reference to FIGS. 16 to 19 to embody the problem.

  FIG. 16 shows the adhesion of dust on the surface of the electrode plate after long-term use in a conventional electrostatic precipitator in which the dust collector 105 is configured by the load electrode plate 105A and the ground electrode plate 105B having substantially the same size and length. It is the photograph (FIG. 16 (16-1): Ground electrode plate 105B, FIG. 16 (16-2): Load electrode plate 105A) showing the situation. The ventilation direction is from left to right as viewed in FIG.

  As shown in FIG. 16 (16-1), in the ground electrode plate 105B, the windward area T1 is darker in color than the leeward area T2. This indicates that much dust is attached and collected in the windward region T1. On the other hand, in the leeward region T2, there is little dust adhesion. From these facts, it can be seen that in the ground electrode plate 105B, the windward half effectively contributes to dust collection, and the ratio of dust collection contribution in the leeward half is low.

  As shown in FIG. 16 (16-2), in the load electrode plate 105A, the upwind half area S1 area is dark due to dust adhesion, but the downwind half area S2 has almost no dust attached, The metal surface of the electrode plate is clearly visible. The reason why the dust adheres to the upwind half area S1 is that the dust adhering to the area T1 area of the ground electrode plate 105B due to electrostatic force is re-scattered. This is because it adheres to the region S1 of the electrode plate 105A by electrostatic force. On the other hand, there is little dust adhesion in the leeward region S2. The reason is that the re-scattered dust flying to the area S2 area is considered to be insufficiently charged at the time of re-scattering, so that it is no longer easy to be attracted to the load electrode plate 105A side by electrostatic force. Conceivable.

  From the above fact-finding survey, in the dust collection part of the electrostatic precipitator, the leeward half of the ground electrode plate and the load electrode plate contributes effectively to dust collection by electrostatic force, and the leeward half does not contribute much. It has been found. In other words, the entire surface of the ground electrode plate and the load electrode plate was not efficiently used, and the electrode plate length in the ventilation direction was made longer than necessary, leading to high cost and large size. I understand.

  FIG. 17 is a photograph of the lower end portion of the load electrode plate 105A and the ground electrode plate 105B of the dust collector 105 after long-term use in the dust collector 105 of the conventional electric dust collector (FIG. 17 (17- 1): Load electrode plate 105A, FIG. 17 (17-2): Ground electrode plate 105B). The ventilation direction is from left to right as viewed in FIG. The subject of this fact-finding is different from the subject of the first fact-finding.

  As shown in FIG. 17 (17-1), it can be seen that dust is concentrated on the windward lower end b of the load electrode plate 105 </ b> A. Moreover, it turns out that the dust has accumulated also on the wind lower end part c of the grounding electrode plate 105B as shown in FIG. 17 (17-2). (Note that some of the accumulated dust was peeled off and dropped off at the time of photography, and showed a discontinuous accumulation state as shown in FIG. 17. That is, the accumulated dust on the end line of the electrode plate was easily peeled off. I add the fact that.)

  This mechanism will be described.

  As shown in FIG. 18, in the dust collector 105 of the conventional electrostatic precipitator, the voltage from the DC high voltage power supply 109 is applied to the load electrode plate 105A, and the ground electrode plate 105B is parallel to the load electrode plate 105A. Is placed and grounded. The ventilation direction is from left to right.

  In the region “a” in the substantially central portion of the dust collection portion 105 in the ventilation direction, the lines of electric force are emitted in parallel and uniformly from the load electrode plate 105A toward the ground electrode plate 105B. This area a is an equal electric field, and when charged dust comes in, electrostatic force acts and a part of the dust is collected. This is nothing but the basic principle of electrostatic dust collection. On the other hand, at the wind lower end b of the load electrode plate 105A and the wind lower end c of the ground electrode plate 105B, the electric lines of force are curved so as to concentrate on the wind lower ends b and c, thereby forming an unequal electric field region. ing. The behavior of dust flying in this unequal electric field will be described with reference to FIG.

  FIG. 19 (19-1) shows that the dust that has come to the head is directed toward the wind lower end b of the load electrode plate 105 </ b> A and the wind lower end c of the ground electrode plate 105 </ b> B and accumulates. It has long been known that in an unequal electric field, particles are attracted in the direction of a stronger electric field by a gradient force rather than an electrostatic force. (For example, Seto Fukuda “Electrical Dust Collection and Its Application” The Journal of the Institute of Electrical Engineers of Japan, January 1945) Gradient force is the force that a dielectric receives in an unequal electric field and moves in the direction of a stronger electric field. Point to. That is, dust accumulates at the wind lower end portions of both electrode plates due to the gradient force at the wind lower end portion b of the load electrode plate 105A and the wind lower end portion c of the ground electrode plate 105B. And as shown in FIG. 19 (19-2), the dust deposited by the gradient force on the wind lower end b of the load electrode plate 105A and the wind lower end c of the ground electrode plate 105B is easy to peel off when accumulated excessively. At the time of peeling, it is charged with the electric polarity of each attached electrode plate and re-scatters. In summary, dust accumulates on the wind lower end b of the load electrode plate 105A and the wind lower end c of the ground electrode plate 105B due to a gradient force, and charged dust re-scatters when excessively deposited. That is, it can be said that this deposition and re-scattering are continuously occurring.

  That is, in the conventional electrostatic precipitator, locally accumulated dust is likely to re-scatter at the wind lower end b of the load electrode plate 105A and the wind lower end c of the ground electrode plate 105B, thereby improving dust collection efficiency. It was decreasing. Then, since the re-scattered dust released as it is is charged, there is a problem that it adheres to the downstream wall surface of the electrostatic precipitator and stains the wall surface.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrostatic precipitator that effectively uses the entire electrode plate of the dust collector and that is less likely to rescatter.

  In order to achieve this object, the present invention provides an electrostatic precipitator in which a load electrode plate and a ground electrode plate are alternately arranged in parallel. It is located on the leeward side from the lower end position, thereby achieving the intended purpose.

  According to the present invention, in the electrostatic precipitator in which the load electrode plates and the ground electrode plates are alternately arranged in parallel, the lee end position of the load electrode plate is located closer to the lee side than the lee end position of the ground electrode plate. To do. With such a configuration, even if dust accumulated by the gradient force becomes excessive and re-scatters at the windward lower end of the ground electrode plate, the load electrode plate provided on the leeward side from the windward lower end portion of the ground electrode plate, Re-scattered dust can be collected by electrostatic force. As a result, this type of electrostatic precipitator exhibits high dust collection efficiency, and also has the effect of reducing the amount of dirt on the wall of the wake and reducing the amount of utility (electric / water) used by extending the cleaning cycle. Can do.

Principle diagram of the dust collecting part of the electric dust collector according to Embodiment 1 of the present invention (2-1) State diagram of dust collection at the end by the gradient force in the dust collection part, (2-2) State diagram of collection of re-scattered dust at the end face The block diagram of the dust collection part and voltage electrode plate part of the electric dust collector by Embodiment 2 of this invention Configuration diagram of an electrostatic precipitator according to Embodiment 3 of the present invention Principle diagram of the dust collecting part of the electric dust collector according to Embodiment 4 of the present invention A photograph showing the state of dust collection at the end of the load electrode plate in Example 1 Observation diagram of dust adhesion on electrode plate surface in Case 1 of Example 2 (Example 4) Observation diagram of dust adhesion on electrode plate surface in Case 2 of Example 2 Observation diagram of dust adhesion on electrode plate surface in Case 3 of Example 2 Observation diagram of dust adhesion on electrode plate surface in Case 4 of Example 2 Photograph showing the state of dust collection at the end of the ground electrode plate in Example 3 Observation diagram of dust adhesion on electrode plate surface in Case 5 of Example 4 Observation diagram of dust adhesion on electrode plate surface in Case 6 of Example 4 Observation diagram of dust adhesion on electrode plate surface in Case 7 of Example 4 Configuration diagram of charging unit and dust collection unit of conventional electrostatic precipitator (15-1) schematic diagram, (15-2) perspective view (16-1) Photograph showing the state of dust collection on the surface of the ground electrode plate of the conventional electrostatic precipitator (16-2) Photograph showing the state of dust collection on the surface of the load electrode plate (17-1) Photograph showing the state of dust collection at the downstream end of the load electrode plate of the conventional electric dust collector (17-2) Photograph showing the state of dust collection at the downstream end of the ground electrode plate Explanatory diagram of electric lines of force between plates of conventional electrostatic precipitator Explanatory drawing of the dust behavior at the end of the electrode plate of the conventional electrostatic precipitator (19-1) The figure showing the dust adhesion state due to the gradient force at the wind lower end, (19-2) Re-scattering from the wind lower end A diagram representing the state

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

(Embodiment 1)
The electrostatic precipitator according to the first embodiment will be described with reference to FIGS. 1 and 2.

As shown in FIG. 1, the electrostatic precipitator according to the present embodiment includes a front charging unit 8 and a rear dust collecting unit 1. The charging unit 8, the DC voltage V ₁₁ of the high-voltage power supply 11 is applied to the discharge electrode 9, a corona discharge between the ground plate 10 of the charging unit (not shown) is generated, the dust that flows from the windward Charges up.

In the dust collector 1, load electrode plates 2 and ground electrode plates 3 are alternately arranged in parallel. A voltage V ₄ is applied to the load electrode plate 2 from a DC high voltage power source 4, and the ground electrode plate 3 is grounded. The ventilation direction is from left to right in parallel with the load electrode plate 2 and the ground electrode plate 3. The lee end b of the load electrode plate 2 is located leeward than the lee end c of the ground electrode plate 3.

  As shown in FIG. 1, an arrow indicating electric lines of force generated in parallel and uniformly from the load electrode plate 2 toward the ground electrode plate 3 is displayed in a region a where both electrode plates face each other. This area is an equal electric field, and when charged dust comes in, electrostatic force acts and a part of the dust is collected.

  On the other hand, the wind lower end portion c of the ground electrode plate 3 is an unequal electric field region, as indicated by the arrow of the electric lines of force that are curved and concentrated on the wind lower end portion c.

  The behavior of dust flying in this unequal electric field will be described with reference to FIG.

  As shown in FIG. 2 (2-1), the dust flying near the wind lower end c of the ground electrode plate 3 is attracted to the wind lower end c by the gradient force and is accumulated. Then, as shown in FIG. 2 (2-2), dust accumulated on the wind lower end portion c of the ground electrode plate 3 is peeled off when accumulated in a large amount, and at this time, the same negative electricity as the attached electrode plate is removed. Charges with polarity and re-scatters. The re-scattered dust is attracted to the load electrode plate 2 having the opposite polarity to the charged electric polarity, and is collected in the region d by electrostatic force.

  In this way, by providing a part of the load electrode plate 2 on the leeward side with respect to the leeward end c of the ground electrode plate 3, it is possible to collect dust that has peeled off and re-scattered from the ground electrode plate 3.

  Further, dust can be collected using the entire electrode plate from the windward side to the leeward side of both the load electrode plate 2 and the ground electrode plate 3, and dust can be collected efficiently.

  Moreover, since the ground electrode plate 3 can be reduced in size when trying to obtain the same dust collection efficiency, it is possible to hold down the material used.

(Embodiment 2)
The electrostatic precipitator according to the second embodiment will be described with reference to FIG.

As shown in FIG. 3, the dust collector 1 of the electric dust collector of the present embodiment has a load electrode plate 2 and a ground electrode plate 3 arranged in parallel. A voltage V ₄ is applied to the load electrode plate 2 from a DC high voltage power source 4, and the ground electrode plate 3 is grounded. The ventilation direction is from left to right. The wind lower end b of the load electrode plate 2 is in the same position as the wind lower end c of the ground electrode plate 3.

And the most characteristic part of this Embodiment is demonstrated. The voltage electrode plate portion 5 in which the voltage electrode plates 6 serving as the second load electrode plates are arranged in parallel is arranged on the leeward side of the dust collecting portion 1. A voltage V ₇ is applied to the voltage plate 6 from a DC high voltage power source 7. The interval between the voltage electrode plates 6 is equal to the interval between the load electrode plates 2 of the dust collector 1, and the voltage electrode plate 6 is arranged on the extended surface of the load electrode plate 2 in the leeward direction. Here, in the dust collection part 1, since the load electrode plate 2 and the ground electrode plate 3 are provided facing each other in parallel, an equal electric field is mainly formed as a whole. On the other hand, in the voltage electrode plate portion 5, since there is no ground plane at the opposite position, an unequal electric field is formed between the voltage electrode plate portion 5 and the upstream ground electrode plate 3.

  In this way, by arranging the voltage electrode plate portion 5 having the voltage electrode plate 6 serving as the second load electrode plate on the leeward side in the same plane as the load electrode plate 2, the lee end portion of the ground electrode plate 3 is disposed. The dust separated and scattered from c can be further collected by the voltage plate portion 5 on the downstream side.

The voltage V ₇ of the DC high voltage power source 7 to be applied to the voltage electrode plate unit 5, it is set higher than the voltage V ₄ of the DC high voltage power source 4 is applied to the load electrode plate 2 of the dust collection unit 1. That is, V ₇ > V ₄ may be satisfied. Is. By setting V ₇ > V ₄ , dust that re-scatters and comes to the voltage electrode plate portion 5 can be collected with a stronger electrostatic force. Further, since there is no grounded electrode plate facing the voltage electrode plate portion 5, the concern about dielectric breakdown and sparks can be greatly reduced. Therefore, the voltage V ₇ applied to the voltage electrode plate 6 can be made higher than the voltage V ₄ applied to the load electrode plate 2. And, compared with the electrode plate interval (distance between the load electrode plate 2 and the ground electrode plate 3) of the dust collecting unit 1, in the voltage electrode plate unit 5, the interval between adjacent electrode plates (interval between the voltage electrode plates 6). Has doubled. Therefore, the applied voltage V ₇ can be about twice that of V ₄ , and the dust collection efficiency is improved accordingly.

(Embodiment 3)
An electric dust collector according to the third embodiment will be described with reference to FIG. The same components as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

The present embodiment is a two-stage electrostatic precipitator arranged in order of the charging unit 8, the dust collecting unit 1, and the voltage electrode plate unit 5 from the windward side. The charging unit 8 includes a discharge electrode 9 and a ground electrode plate 10, and a voltage V ₁₁ (for example, 11 kV) for charging dust by corona discharge is supplied from the DC high-voltage power supply 11 to the discharge electrode 9.

A voltage V ₄ (for example, 8.3 kV) is applied to the load electrode plate 2 of the dust collection unit 1 from the DC high-voltage power supply 4 as in the first and second embodiments.

Here, the voltage V ₁₁ applied to the discharge electrode 9 of the charging unit 8 is usually larger than the voltage V ₄ applied to the load electrode plate 2 of the dust collection unit 1 in order to generate corona discharge. It has become.

  Therefore, the electrostatic precipitator of the present embodiment uses the DC high-voltage power source 11 used for the charging unit 8 in common with the voltage electrode plate unit 5, so that a dedicated DC high-voltage power source is used for the voltage electrode plate unit 5. It is possible to reduce the cost by omitting the provision.

(Embodiment 4)
The electrostatic precipitator according to the fourth embodiment will be described with reference to FIG.

As shown in FIG. 5, the dust collector 1 of the electric dust collector (not shown) of the present embodiment has a load electrode plate 2 and a ground electrode plate 3 arranged in parallel. A voltage V ₄ is applied to the load electrode plate 2 from a DC high voltage power source 4, and the ground electrode plate 3 is grounded. The ventilation direction is from left to right. The windward lower end portion c of the ground electrode plate 3 is located leeward than the windward lower end portion b of the load electrode plate 2.

  Here, the same re-scattering mechanism exists also about the dust adhering to the wind lower end part b of the load electrode plate 2. Therefore, in other words, as shown in FIG. 5, this mechanism is curved from the lower end b of the load electrode plate 2 toward the leeward region e of the ground electrode plate 3, and the electric field line arrows extend. ing. In particular, the electric field in the vicinity of the windward end b of the load electrode plate 2 where the lines of electric force are dense is the strongest. The region where the lines of electric force are curved is a region of an unequal electric field.

  Dust (not shown) flying in the unequal electric field accumulates toward the wind lower end b of the load electrode plate 2 where the electric field is maximum due to the gradient force. Then, a large amount of dust accumulated at the windward lower end b of the load electrode plate 2 is peeled off, and at this time, it is charged (positively charged) with the electric polarity of the load electrode plate 2 attached thereto and re-scatters. The re-scattered dust is collected in the area e of the ground electrode plate 3 by electrostatic force.

  In this way, by providing a part of the ground electrode plate 3 on the leeward side from the leeward end b of the load electrode plate 2, it is possible to collect dust that has peeled off and re-scattered from the ground electrode plate 3.

  Moreover, since it is possible to reduce the size of the load electrode plate 2 when trying to obtain the same dust collection efficiency, it is possible to suppress the material used.

Example 1
FIG. 6 is a photograph of the electrode plates (load electrode plate 2 and ground electrode plate 3) after the dust collection experiment was performed under the following conditions in the electric dust collector having the configuration of FIG. 2 (2-1). .

The electrode plate interval between the load electrode plate 2 and the ground electrode plate 3 of the dust collector 1 was 15 mm, and the voltage applied between the load electrode plate 2 and the ground electrode plate 3 was DC + 13 kV. Dust passing therethrough was diluted with exhaust air from a diesel engine with air, and was passed at a passing air speed of 9 m / s under the condition of a dust concentration of about 0.5 mg / m ³ . The operation time was 12 hours.

  Further, the lee end b of the load electrode plate 2 was made approximately 40 mm longer on the leeward side than the lee end c of the ground electrode plate 3. FIG. 6 shows that a large amount of dust adheres to a dark (black) portion.

  As shown in FIG. 6, the fact that the dust that has re-scattered is collected in the region d on the downstream side of the wind lower end c of the ground electrode plate 3 of the load electrode plate 2 becomes darker in color. I know from that.

  The same result was obtained in an experiment in which the distance between the electrode plates was changed in the range of 5 mm to 20 mm. Further, the maximum value of the voltage applied between the electrode plates was 1 kV per electrode plate interval of 1 mm, and the minimum value of the applied voltage was half of that.

  In addition, the same result can be obtained regardless of whether the applied voltage is a positive voltage or a negative voltage.

(Example 2)
The second example is an experiment of collecting dust by changing the position of the wind lower end portion c of the ground electrode plate 3 in the configuration of the first embodiment.

As shown in FIG. 1, the length of the load electrode plate 2 is L ₁ , and the distance between the wind lower end c of the ground electrode plate 3 and the wind lower end b of the load electrode plate 2 is D ₁ .

  Extending the entire length of the dust collection unit 1 in the ventilation direction has an effect of improving the dust collection efficiency of the electric dust collector. In this example, the size of the electrode plate with high dust collection efficiency was confirmed by experiments within a limited space. The experimental contents and results are shown below.

In the experimental electrostatic precipitator, a dust collector 1 in which a plurality of load electrode plates 2 and ground electrode plates 3 are alternately arranged in parallel at intervals of 10 mm is provided behind a charging unit (not shown). Is. In a state where a +8 kV DC voltage was applied to the load electrode plate 2, air containing diesel dust having a dust concentration of 0.5 mg / m ³ was passed at a wind speed of 9 m / s for 16 hours to conduct a dust collection experiment. The thickness of all the electrode plates is 0.4 mm, and the material is SUS304. The dimensions of the load electrode plate 2 are 120 mm in height and 360 mm in total length.

On the other hand, four types of grounding electrode plates 3 were used. The total length of the ground electrode plate 3 was prepared to be 1 times the total length of the load electrode plate 2, and 0.25 times, 0.5 times, and 0.75 times. For easy comparison, the position on the windward side of the load electrode plate 2 and the ground electrode plate 3 was set to the same position. The distance D ₁ from the wind lower end c of the ground electrode plate 3 to the wind lower end b of the load electrode plate 2 is 0 times (case 1), 0.75 with respect to the total length L ₁ of the load electrode plate 2. Experiments were performed with four patterns of double (case 2), 0.5 times (case 3), and 0.25 times (case 4). The height dimensions of the load electrode plate 2 and the ground electrode plate 3 are the same.

Case 1 is the prior art itself and is used as a reference for comparison. And each electrode plate shall be observed after dust collection operation for 16 hours in each case. The observation method is to convert the optical micrograph (50 magnification) of each part of each electrode plate into a black and white binary image using binary imaging software (Photo Filter), and calculate the% area of the black part indicating dust adhesion. Binary image analysis software (Pixel
(Counter).

  FIG. 7 shows a dust collection state of the load electrode plate 2 and the ground electrode plate 3 in the case 1. The black part is the part where dust is attached. The arrow indicates the direction of ventilation, and it can be seen that the dust (black part) attached decreases as the ground electrode plate 3 and the load electrode plate 2 move downstream in the flow direction of the wind. The numerical value shown at the bottom of each image is the% area of the black part indicating that dust has adhered (the black part area of each image ÷% value of the total area). This “black part% area” is a value proportional to the actual black part area, and can be handled equivalent to the actual area. The larger this value, the more dust is attached. That is, it shows the magnitude of the dust collecting ability in each part of the electrode plate. The total black area% area of the ground electrode plate 3 in case 1 is 130%. The total black area% area of the load electrode plate 2 is 38%. Therefore, in this case 1, the total area of the black portion% of the ground electrode plate 3 and the load electrode plate 2 is 168%, and this is the dust collecting ability of the dust collecting portion of the case 1.

FIG. 8 shows a dust collection state of the load electrode plate 2 and the ground electrode plate 3 in the case 2. That is, the distance D ₁ between the wind lower end c of the ground electrode plate 3 and the wind lower end b of the load electrode plate 2 is 0.75 × L ₁ . In case 2, the same analysis as in case 1 was performed. The dust collection capacity in Case 2 was 56% (ground electrode plate 3) + 115% (load electrode plate 2) = 171%.

Similarly, FIG. 9 shows a dust collection state of the load electrode plate 2 and the ground electrode plate 3 in the case 3. That is, the distance D ₁ between the wind bottom end c of the ground electrode plate 3 and the wind bottom end b of the load electrode plate 2 is 0.5 × L ₁ . FIG. 10 shows a dust collection state of the load electrode plate 2 and the ground electrode plate 3 in the case 4. That is, the distance D ₁ between the wind lower end c of the ground electrode plate 3 and the wind lower end b of the load electrode plate 2 is 0.25 × L ₁ .

  Table 1 shows the result of totaling black area% areas indicating the dust collection ability in case 1 to case 4.

As shown in Table 1, it can be seen that the dust collection capability increases as the position of the wind lower end portion c of the ground electrode plate 3 is shifted to the upstream side. Then, it considered the maximum value exists between the D ₁ = 0.5L ₁ ~0.75L _1, dust collecting capacity Beyond that point decreases.

  This is because the load electrode plate 2 downstream of the wind lower end portion c of the ground electrode plate 3 collects dust re-scattered from the ground electrode plate 3 as described above. And if the area of the grounding electrode plate 3 is too small, the area where dust can be collected decreases, so that the dust collecting ability cannot be sufficiently exhibited.

When the dust collection capacity is Case 2 (D ₁ = 0.75L ₁ ), the conventional electrostatic dust collector exhibits almost the same performance.

Further, among the D ₁ = 0.5L ₁ ~0.75L _1, to exhibit conventional electrostatic dust collecting capability of + 10% or more of the capabilities of the precipitator of the estimation.

(Example 3)
FIG. 11 is a photograph of the electrode plates (the load electrode plate 2 and the ground electrode plate 3) after the dust collection experiment was performed under the following conditions in the electric dust collector having the configuration shown in FIG.

  In the configuration of the experimental electrostatic precipitator, the leeward end c of the ground electrode plate 3 was made approximately 30 mm longer on the leeward side than the leeward end b of the load electrode plate 2. Other experimental conditions such as electrode plate spacing are the same as those in Example 1.

  As shown in FIG. 11, the scattered dust is collected in the ground electrode plate 3 region d on the downstream side of the wind lower end portion b of the load electrode plate 2, and the color is darkly black. I understand from that.

  The same result was obtained in an experiment in which the distance between the electrode plates was changed in the range of 5 mm to 20 mm. Further, the maximum value of the voltage applied between the electrode plates was 1 kV per electrode plate interval of 1 mm, and the minimum value of the applied voltage was half of that.

  In addition, the same result can be obtained regardless of whether the applied voltage is a positive voltage or a negative voltage.

(Example 4)
The fourth example is an experiment of collecting dust by changing the position of the wind lower end b of the load electrode plate 2 in the configuration of the fourth embodiment.

As shown in FIG. 5, the length of the ground electrode plate 3 is L ₂ , and the distance between the wind lower end portion b of the load electrode plate 2 and the wind lower end portion c of the ground electrode plate 3 is D ₂ . (Note that L ₁ = L ₂ ).

  Here, as in Example 2, the size of the electrode plate with high dust collection efficiency was confirmed by experiments. The experimental contents and results are shown below. Note that description of experimental conditions common to the second embodiment, such as the configuration of the apparatus, is omitted.

The ground electrode plate 3 has a height of 120 mm and a total length of 360 mm. On the other hand, three types of load electrode plates 2 were used. And the position of the windward side of the load electrode plate 2 and the ground electrode plate 3 was made the same position for easy comparison. The distance D ₂ from the wind bottom end b of the load electrode plate 2 to the wind bottom end c of the ground electrode plate 3 is 0 times (case 1) and 0.75 times the total length L ₂ of the ground electrode plate 3 ( Case 5), 0.5 times (Case 6), and 0.25 times (Case 7) were tested in four patterns. The height dimensions of the load electrode plate 2 and the ground electrode plate 3 are the same.

  Case 1, that is, the result of the configuration of the electrostatic precipitator in the prior art uses the result of Case 1 of Example 2. And the dust collection capability of each case was compared with this case 1 as a reference.

  Table 2 shows the result of totaling black area% areas indicating the dust collection ability in Case 1, Case 5, Case 6, and Case 7.

The total of the black part% area which shows the total dust collection capability by both the grounding electrode plate 3 and the load electrode plate 2 in each case is shown at the right end of Table 2. According to this, the% area of case 1 (conventional type, D ₂ = 0) is 168, but the load electrode plate 2 is short, case 5 (D ₂ = 0.75 L ₂ ), case 6 (D ₂ = 0). .5L ₂ ) and Case 7 (D ₂ = 0.25L ₂ ), the black area% areas are 184, 196, and 192, respectively, which in turn exceed the value 168 of Case 1.

As shown in Table 2, it can be seen that the dust collection capability increases by shifting the position of the wind lower end b of the load electrode plate 2 to the upstream side. Then, it considered the maximum value exists between the D ₂ = 0.5L ₂ ~0.75L _2, the dust collecting ability Beyond that point decreases.

  This is because the ground electrode plate 3 downstream of the wind lower end b of the load electrode plate 2 collects dust re-scattered from the load electrode plate 2 as described above. And if the area of the load electrode plate 2 is too small, the area where dust can be collected decreases, so that the dust collecting ability cannot be sufficiently exhibited.

Further, between the D ₂ = 0.5L ₂ ~0.75L _2, to exhibit conventional electrostatic dust collecting capability of + 10% or more of the capabilities of the precipitator of the estimation.

  The electrostatic precipitator according to the present invention makes it possible to suppress re-scattering by making the lengths of the load electrode plate and the ground electrode plate of the dust collecting portion equal in the ventilation direction, and to save energy by prolonging the cleaning cycle. Therefore, it is useful in a wide range.

DESCRIPTION OF SYMBOLS 1 Dust collection part 2 Load electrode plate 3 Grounding electrode plate 4 DC high voltage power supply 5 Voltage electrode plate part 6 Voltage electrode plate 7 DC high voltage power supply 8 Charging part 9 Discharge electrode 10 Grounding electrode plate 11 DC high voltage power supply

Claims (8)

In the electrostatic precipitator in which the load electrode plate and the ground electrode plate are alternately arranged in parallel,
An electrostatic precipitator in which a windward lower end position of the load electrode plate is located on a leeward side of a windward lower end position of the ground electrode plate. The load electrode plate is composed of a first load electrode plate on the windward side and a second load electrode plate on the leeward side,
An equal electric field is mainly formed between the first load electrode plate and the ground electrode plate,
An electrostatic precipitator in which an unequal electric field is mainly formed between the second electrode plate side and the ground electrode plate. The electrostatic precipitator according to claim 2, wherein a voltage higher than that of the first load electrode plate is applied to the second load electrode plate. The windward lower end position of the ground electrode plate is on the windward side of the windward lower end position of the load electrode plate,
The electrostatic precipitator according to claim 1, wherein the electrostatic precipitator is provided at a distance smaller than 0.75 times the total length of the load electrode plate in the ventilation direction from the wind lower end position of the load electrode plate. The wind bottom position of the ground electrode plate is
The electrostatic precipitator according to claim 4, wherein the electrostatic precipitator is provided at a distance of 0.25 to 0.5 times a total length in a ventilation direction of the load electrode plate from a wind lower end position of the load electrode plate. In a two-stage type electric dust collector composed of a charging part and a dust collecting part,
The dust collecting unit is arranged alternately in parallel with the load electrode plate and the ground electrode plate,
The load electrode plate is composed of a first load electrode plate on the windward side and a second load electrode plate on the leeward side,
The windward lower end position of the second load electrode plate is disposed on the leeward side from the wind lower end position of the ground electrode plate,
Furthermore, the electrostatic precipitator which applies the voltage of the said power supply for charging parts to the said 2nd load electrode plate. In the electrostatic precipitator in which the load electrode plate and the ground electrode plate are alternately arranged in parallel,
The windward lower end position of the load electrode plate is on the windward side from the wind lower end position of the ground electrode plate,
An electrostatic precipitator provided at a distance smaller than 0.75 times the total length in the ventilation direction of the ground electrode plate from the wind lower end position of the ground electrode plate. The wind-lower end position of the load electrode plate is
The electrostatic precipitator according to claim 7, wherein the electrostatic precipitator is provided at a distance of 0.25 to 0.5 times a total length of the ground electrode plate in a ventilation direction from a wind lower end position of the ground electrode plate.

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