JP3268041B2 - Duct type electrostatic precipitator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duct type electrostatic precipitator, and is intended to obtain a high corona current.

[0002]

2. Description of the Related Art When a fuel such as heavy oil or coal is burned by a boiler, the sulfur content in the fuel is oxidized and SO _x (S
O ₂ and SO ₃ ) are generated. Of the SO _x , SO ₂ gas is efficiently removed by installing a wet flue gas desulfurization device. However, SO ₃ gas is liquefied during the gas cooling process in the flue gas desulfurization unit, and extremely fine S 3
It becomes O ₃ mist (sulfuric acid mist). S for flue gas desulfurization equipment
O ₃ mist is hardly removed, and is discharged from the chimney as it is to become purple smoke. Recently, in many cases regulation value of the SO _x amount with the spread of the flue gas desulfurization apparatus to be satisfied, purple smoke due to SO ₃ mist, simply causes of acid rain 1
Not only that, but also as a new source of visual pollution.

In order to make this purple smoke invisible, it is necessary to suppress the dust concentration at the chimney inlet to a very low level of 10 mg / m ³ N or less, including fine SO ₃ mist. For this reason, it is effective to install a wet electrostatic precipitator downstream of the flue gas desulfurization unit to remove soot and dust containing SO ₃ mist from the exhaust gas. In recent years, a duct type electrostatic precipitator (hereinafter referred to as a duct type EP), which is a very compact wet type electric precipitator, has been developed.
) Has been put to practical use, and the number of cases where this is installed in a flue gas duct is increasing.

In the duct type EP, a plurality of small ducts are provided by partitioning a cross section of a flue gas duct, an inner surface of the small duct is used as a dust collecting electrode, and a rod-shaped discharge electrode is provided at the center of each small duct. This is an electrostatic precipitator that is charged by

The duct type EP will be described with reference to FIGS. FIG. 11 shows the entire configuration of the duct type EP, and FIG. 12 shows a view taken along the line S--S in FIG.

[0006] A plurality of small ducts 1a are provided to partition the cross section of the flue gas duct (casing) 1, and the small ducts 1a are provided.
The inner surface of a is a dust collecting electrode 2. Each small duct 1a
A rod-shaped discharge electrode 3 is provided at the center of the electrode, and the upper and lower ends of the discharge electrode 3 are supported by support beams 5 by mounting brackets 4. A charge tube 8 is attached to each support beam 5, and the charge tube 8 is supported by a support insulator 6 in an insulator chamber 7. The upper charging tube 8 is connected to a high-voltage transformer / rectifier 9 via a through insulator 10. In the drawing, reference numeral 12 denotes a spray nozzle, and reference numeral 13 denotes a connection duct.

[0007] The above-mentioned duct type EP is composed of each small duct 1a.
Dust collection space in the small space (narrow spacing)
Therefore, even if the space charge is high, the dust collection rate is greatly improved as compared with a normal wet-type electrostatic precipitator, so that it is installed and installed in a normal-sized casing 1 and used under high-speed flow. However, performance can be fully demonstrated. As described above, since the duct type EP is a very high-performance dust collecting device, it has recently been effective not only for removing SO ₃ mist but also in a wide range of application fields.

As the discharge electrode 3 of the duct type EP, a high-current discharge electrode capable of stably supplying a corona current 10 times or more larger than that of a normal wet-type electrostatic precipitator is required.
In addition, accurate positioning is important for narrow-spaced electrode arrays, and a high-rigidity structure that is not affected by the vibration caused by sparks or the vibration that may be a concern when used under high-speed flow is required. Is done.

The discharge electrode 3 of the duct type EP will be described with reference to FIGS. FIG. 13 shows the side surface of the discharge electrode,
14 is a view taken along line AA in FIG. 13, and FIG.
The BB line in the arrow is shown.

The discharge electrode 3 includes a support rod 14 and a projection 15. That is, a pin-shaped projection 15 (made of stainless steel) having a sharpened tip is fixed to the surface of the stainless steel support rod 14 by stud welding.
Stable high corona current generation is ensured.

Although the projection 15 is fixed to the support rod 14 by stud welding, the surface of the support rod 14 is formed in a flat surface in order to facilitate weldability and positioning, and the support rod 14 has a square cross section. Square bars are used.
In the drawing, reference numeral 16 denotes a nut for fixing the support rod 14 to the mounting bracket 4.

[0012]

A very large corona current is supplied to maintain the performance of the duct type EP. However, when the applied voltage is increased to obtain the maximum corona current in order to obtain the limit performance, the voltage is increased. The upper limit is determined by the first spark generation in the dust collection space. Sparks are more likely to occur as the distance between the discharge electrode system (high voltage side) and the dust collection electrode system (ground side) becomes shorter, and where the surface of each becomes sharp and the lines of electric force concentrate. Easy to occur. The first spark is generated at the place where the spark is most likely to occur, and the spark voltage is determined according to the conditions of the distance (array) and the electrode surface shape.

In the conventional duct-type EP shown in FIGS. 13 to 15, the support rod 14 of the discharge electrode 3 has a square cross section, and the corner portion has an acute angle. The end of the wall 1a is also an acute angle because it is the end of the thin plate. For this reason, although the distance is larger than the distance between the tip of the projection 15 and the wall surface of the small duct 1a, the end of the wall of the small duct 1a and the support rod 14
The first spark may occur with the corner of the In this case, compared to the case where the first spark occurs between the tip of the projection 15 and the wall surface of the small duct 1a, the spark voltage is considerably lower, the corona current obtained is lower, and sufficient high performance cannot be obtained. Will be.

[0014]

According to a first aspect of the invention for solving the above-mentioned problems, a cross section of a flue gas duct is divided to form a plurality of small ducts, and an inner surface of the small duct is used as a dust collecting electrode. In a duct-type electrostatic precipitator provided with a rod-shaped discharge electrode at the center of each small duct, the discharge electrode is composed of a support rod having a rectangular cross section and a barb-like projection with a sharp tip attached to the support rod. Become less
At least, the corners of the cross section of the support rod at the portion from the tip to the first projection mounting portion are formed in an arc shape.

According to a second aspect of the present invention for solving the above-mentioned problems, a plurality of small ducts are formed by partitioning a cross section of a flue gas duct, and the inner surface of the small duct is used as a dust collecting electrode. In a duct type electrostatic precipitator provided with a rod-shaped discharge electrode at the center of the support rod, the discharge electrode comprises a support rod having a rectangular cross section, and a barb-like protrusion having a sharp tip attached to the support rod. At least the tip
The cross section of the support rod at a portion from the portion to the first protrusion attachment portion is formed in a circular shape.

According to a third aspect of the present invention, there is provided a fuel cell system in which a plurality of small ducts are formed by partitioning a cross section of a flue gas duct, and an inner surface of the small duct is used as a dust collecting electrode. In the duct-type electrostatic precipitator provided with a rod-shaped discharge electrode at the center of the rectangular shape, the discharge electrode has a barb-shaped projection with a sharp tip attached and a hollow rectangular cross-section with a corner formed in an arc shape. And a mounting member having a circular cross section fixed to an end of the supporting rod.

[0017]

According to the first aspect of the present invention, at least the corners of the cross section of the support rod from the end to the mounting portion of the projection are formed in an arc shape, so that the concentration of lines of electric force is reduced, and the end of the wall surface of the small duct The first spark between the part and the corner of the support rod is eliminated.

According to the second aspect of the present invention, since the cross section of the support rod from at least the end to the projection mounting portion is formed in a circular shape, the concentration of the electric force lines is reduced by easy machining, and The occurrence of the first spark between the end of the wall surface of the duct and the corner of the support rod is eliminated.

According to the third aspect of the present invention, since the discharge electrode is constituted by the hollow support rod and the mounting member having a circular cross section, the rigidity of the support rod is increased to reduce the concentration of the lines of electric force, thereby reducing the size of the electric field lines. The generation of the first spark between the end of the wall surface of the duct and the discharge electrode is eliminated.

[0020]

1 is a side view of a discharge electrode of a duct-type EP according to an embodiment of the first invention, FIG. 2 is a view taken along the line II-II in FIG. 1, and FIG. -III line is shown.
Note that the same members as those shown in FIGS. 11 to 15 are denoted by the same reference numerals, and redundant description is omitted.

The discharge electrode 21 is provided at the center of each of the dust collecting electrodes 2, that is, each of the small ducts 1 a, and is composed of a support rod 22 and a projection 15. The support rod 22 has a square cross section, and the cross-section corner 22a is formed in an arc shape. Since the projection 15 is fixed to the flat portion of the support rod 22 by stud welding, the arc-shaped cross-sectional corner 22 a does not affect the attachment of the projection 15.

Therefore, since the cross-sectional corner 22a of the support rod 22 at the portion closest to the end of the dust collecting electrode 2 has an arc shape, the lines of electric force are not concentrated and the first spark is generated at this portion. Is eliminated. In this embodiment, the cross-section corner 22 a is formed in an arc shape over the entire length of the support rod 22, but at least from the mounting portion (end) to the mounting bracket 4 to the mounting portion of the projection 15 (projection mounting portion). Is formed in an arc shape, that is, at least a portion where the projection 15 is not attached between the tip end portion of the support rod 22 and a portion where the projection 15 is attached (in the support rod 22).
At least the part from the tip to the first protrusion attachment part)
The present invention is achieved by forming the cross-section corner 22a of the support rod 22 in an arc shape.

According to the duct type EP of the first invention, generation of the first spark between the end of the dust collecting electrode 2 and the discharge electrode 21 is eliminated, and the tip of the projection 15 and the small duct 1a are always removed.
The first spark is generated between the wall and the wall.

The second invention will be described with reference to FIGS. 4 is a side view of a discharge electrode of a duct-type EP according to an embodiment of the second invention, FIG. 5 is a view taken along a line VV in FIG. 4, FIG.
4 shows a view taken along line VI-VI in FIG.

One discharge electrode 25 is provided at the center of each of the dust collecting electrodes 2, that is, each of the small ducts 1 a, and is composed of a support rod 26 and a projection 15. Both ends of the support rod 26 are threaded to be attached to the mounting bracket 4, but the process of cutting into a circular cross section, which is a lower process of the threading, is an attachment portion of the projection 15 (projection attachment portion).
(The portion indicated by reference numeral 27 in the figure). In other words, at least a portion where the projection 15 is not attached between the tip of the support rod 22 and a portion where the projection 15 is attached (at least the tip of the support rod 22).
The section of the support rod 22 (from the part to the first protrusion attachment part) is formed in a circular shape. The projection 15 is a support rod 22
Are fixed by stud welding to the square cross section.

Therefore, since the cross section of the support bar 26 at the portion closest to the end of the dust collecting electrode 2 is formed in a circular shape, the lines of electric force are not concentrated, and the first spark is generated at this portion. Completely eliminated. In addition, since the processing to the circular cross section is performed simultaneously with the lower processing of the threading processing, it is not necessary to add a processing step.

According to the duct type EP of the second invention, the occurrence of the first spark between the end of the dust collecting electrode 2 and the discharge electrode 25 is completely eliminated without adding a processing step, and the projection is always formed. The first spark is generated between the tip of No. 15 and the wall surface of the small duct 1a.

The third invention will be described with reference to FIGS. FIG. 7 shows a duct type EP according to an embodiment of the third invention.
8, FIG. 8 is a view taken along line VIII-VIII in FIG. 7, FIG. 9 is a view taken along line IX-IX in FIG. 7, and FIG. 10 is a view taken along line XX in FIG. Is shown.

One discharge electrode 31 is provided at the center of each of the dust collecting electrodes 2, that is, each small duct 1a, and a support rod 32 to which the projection 15 is fixed, and a mounting rod attached to both ends of the support rod 32. Material 33. Mounting material 3
The discharge electrode 31 is supported at the center of the small duct 1a by attaching 3 to the mounting bracket 4.

The support rod 32 is formed by processing a round pipe to have a rectangular cross section, and the corner 32a is formed in an arc shape. The mounting member 33 has a circular cross section, and the outer diameter dimension r is substantially equal to the distance R between the opposite sides of the support rod 32.

Attachments 33 are inserted into both ends of the support rod 32, and both are fixed by welding. Since the duct type EP is used in a highly corrosive gas atmosphere as in the case of collecting SO ₃ mist, the support rod 32 having a rectangular cross section is used.
The gap formed between the gap and the mounting member 33 having a circular cross section is completely sealed by fill-in welding. Since the distance R between the opposite sides of the support rod 32 and the outer diameter r of the mounting member 33 are substantially equal, the center lines of the two coincide and the straightness is sufficiently maintained.

Therefore, since the cross section of the mounting member 33 closest to the end of the dust collecting electrode 2 is formed in a circular shape, the lines of electric force are not concentrated, and the first spark generation at this point is completely completed. Will be resolved. Further, since the support rod 32 has a hollow square pipe shape, the cross section can be enlarged without increasing the weight.

According to the duct type EP of the third invention, the rigidity of the support rod 32 is increased without increasing the weight, and the first spark is completely generated between the end of the dust collecting electrode 2 and the discharge electrode 25. And the first spark always occurs between the tip of the projection 15 and the wall surface of the small duct 1a.

[0034]

In the duct type electrostatic precipitator according to the first aspect of the present invention, the first projection from at least the tip of the support rod is provided.
Since the discharge electrode is formed by forming the cross-sectional corner of the support rod at the portion up to the mounting portion into an arc shape, the first spark between the end of the dust collection electrode and the discharge electrode is eliminated, and it is always eliminated. The first spark is generated between the tip of the projection and the wall surface of the small duct. As a result, the spark voltage rises, the supply corona current rises, and the performance can be improved.

In the duct type electrostatic precipitator of the second invention,
Attach the first projection from at least the tip of the support rod
Since the discharge electrode is formed by forming the cross section of the support rod up to the part into a circular shape, the first spark occurs between the end of the dust collecting electrode and the discharge electrode without adding machining steps Therefore, the first spark always occurs between the tip of the projection and the wall surface of the small duct. As a result, the spark voltage rises, the supply corona current rises, and the performance can be improved without increasing the cost.

In the duct type electrostatic precipitator of the third invention,
Since the discharge electrode was composed of a hollow, rectangular cross-section support rod to which the protrusions were attached, and a circular cross-section mounting material fixed to the end of the support rod, the cross-section of the support rod could be reduced without increasing the weight. The first spark is prevented from being generated between the end of the dust collecting electrode and the discharge electrode, and the first spark is always generated between the tip of the projection and the wall surface of the small duct. As a result, the spark voltage increases, the supply corona current increases, the rigidity can be increased, and the performance can be improved.

[Brief description of the drawings]

FIG. 1 is a side view of a discharge electrode of a duct type electrostatic precipitator according to one embodiment of the first invention.

FIG. 2 is a view taken along the line II-II in FIG.

FIG. 3 is a view taken along line III-III in FIG. 1;

FIG. 4 is a side view of a discharge electrode of the duct type electrostatic precipitator according to one embodiment of the second invention.

FIG. 5 is a view taken along line VV in FIG. 4;

FIG. 6 is a view taken along line VI-VI in FIG. 4;

FIG. 7 is a side view of a discharge electrode of the duct type electrostatic precipitator according to one embodiment of the third invention.

FIG. 8 is a view taken along line VIII-VIII in FIG. 7;

FIG. 9 is a view taken along line IX-IX in FIG. 7;

FIG. 10 is a view taken along line XX in FIG. 7;

FIG. 11 is an overall configuration diagram of a duct type electrostatic precipitator.

FIG. 12 is a view taken along line SS in FIG. 11;

FIG. 13 is a side view of a discharge electrode in a conventional duct type electrostatic precipitator.

FIG. 14 is a view taken along the line AA in FIG. 13;

FIG. 15 is a view taken along line BB in FIG. 13;

[Explanation of symbols]

 1a Small duct 2 Dust collecting electrode 4 Mounting bracket 15 Projection 21, 25, 31 Discharge electrode 22, 26, 32 Support rod 33 Mounting material

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Showa 60-91257 (JP, U) Japanese Utility Model Showa 52-63283 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) B03C 3/00-3/88

Claims (3)

(57) [Claims] 1. A duct type electric collector in which a plurality of small ducts are formed by partitioning a cross section of a flue gas duct, an inner surface of the small duct is used as a dust collecting electrode, and a rod-shaped discharge electrode is provided at the center of each small duct. In the dust device, the discharge electrode is:
A support bar having a rectangular cross section and a barb-like projection with a sharp tip attached to the support bar, and the first projection mounting from at least the tip of the support bar.
A duct-type electrostatic precipitator, wherein the cross-sectional corners of the support bar up to the part are formed in an arc shape. 2. A duct-type electric collector in which a plurality of small ducts are formed by partitioning a cross section of a flue gas duct, an inner surface of the small duct is used as a dust collecting electrode, and a rod-shaped discharge electrode is provided at the center of each small duct. In the dust device, the discharge electrode is:
A support bar having a rectangular cross section and a barb-like projection with a sharp tip attached to the support bar, and the first projection mounting from at least the tip of the support bar.
A duct-type electrostatic precipitator, wherein a cross section of a support rod at a part up to a part is formed in a circular shape. 3. A duct-type electric collector in which a plurality of small ducts are formed by partitioning a cross section of a flue gas duct, an inner surface of the small duct is used as a dust collecting electrode, and a rod-shaped discharge electrode is provided at the center of each small duct. In the dust device, the discharge electrode is:
A support rod of the hollow cross-section corners are formed in a circular arc shape in a rectangular with thorn-like projections that a pointed tip is attached, and a cross-sectional circular shaped mounting member fixed to an end portion of the support rod A duct-type electrostatic precipitator, comprising: