JPH02307550A - Dry electric dust precipitator - Google Patents

Abstract

PURPOSE:To obtain a dry electric dust precipitator capable of employing a vertical gas flow system and showing high dust collecting effect by providing partition wall plate parts to respective dust collecting electrode plates vertically arranged in parallel at an equal interval from the edge parts thereof. CONSTITUTION:Respective dust collecting electrode plates 2 are equipped with partition wall plate parts 2-2, which are vertically provided toward opposed dust collecting electrode plates in a protruding state, at an equal interval from the edge parts thereof and the paired partition wall plates of the opposed dust collecting electrode plates 2 are slightly spaced apart from each other to form flat parts 2-1 and small spaces 4 having a rectangular cross-section. Discharge electrodes 3 each composed of a discharge tube 3-2 equipped with crossing needles 3-1 are suspended from an upper assembled frame at the central parts of the small spaces 4. When the upper assembled frame is insulated from the earth to be connected to a DC high voltage cathode, the tips of the crossing needles 3-1 of the discharge tubes 3 are ionized to generate corona discharge. Since the tips of the crossing needles 3-1 extend to the vicinity of the dust collecting electrode surfaces and are sharp, potential frequency becomes high and corona starting voltage becomes low.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a dry electrostatic precipitator capable of processing a large amount of dust-containing gas with a small installation area, and in particular to a vertical gas flow type dry electrostatic precipitator. It is.

(Prior art) An electrostatic precipitator is a wet electrostatic precipitator (hereinafter referred to as iA is
It is classified into tIE, P, for short) and dry electrostatic precipitator (hereinafter, Dustε, P, for short). Among these, in Dust E, P, etc., the vertical gas flow method cannot be adopted because the dust collected on the dust collecting electrode must be constantly removed, and the horizontal gas flow method is commonly used. However, in Mists B and P, dust and other collected substances can be washed off from the dust collecting electrode using a water washing device, so continuous operation using the vertical gas flow method is possible, and for this reason, the conventional vertical gas flow electric Most of the dust collectors are Mist E, P, and are cylindrical, rectangular, or hexagonal to improve the dust collection rate.

Vertical gas flow type electrostatic precipitators, such as the octagonal type, have been developed and each has its own effects.

(Problem to be Solved by the Invention) However, in the horizontal gas flow type Dust IE, P, the upper and lower gas passages are slightly closed, for example, the upper 8%, for fear that gas will pass through the upper and lower parts of the dust collecting electrode. , bottom 1
The entire surface of the dust collection pole is not used effectively because it is closed to about 0% to allow gas to flow. Also B, P.

In order to equalize the gas flow in the electric field within the horizontal gas flow type, an enlarged flue must be provided at the gas inlet and gas outlet, which requires an enormous amount of installation area and space.

In addition, in the horizontal gas flow type Dust B, P, the dust collection electrode is a flat plate type, so the plate is prevented from curving and reinforced, but if these are made large, they will obstruct the gas passage. The square type cannot be used as is for horizontal gas flow type.

On the other hand, the manufacturing sector of electrostatic precipitators has been in a severe recession since the oil shock, coinciding with the recession in the industrial world, and there has been almost no new construction except for garbage incineration facilities, but due to the recent increase in domestic demand, there is a need to renew or expand equipment. Many contractors have begun planning, but they have had to cancel their plans due to construction site issues.

Also, there are devices made under the exhaust gas regulations a few years ago, such as Duo, which had an outlet dust content of 0.5g/Nm3D according to the exhaust gas regulations.
st B, P, to the current regulation of 0.05g7Nm3
In order to satisfy D, it is necessary to update the old equipment that was made with a dust collection rate of 95% and improve it to a dust collection rate of 99.5%, so the installation area will need to be more than twice as large. be done. However, in the past, no place has installed such a system with such leeway.

Therefore, the object of the present invention is to use a high-temperature electrostatic precipitator (hereinafter referred to as "Hot").
Dust E, P, including (abbreviated as E, P)
To provide a dry type electrostatic precipitator that can solve the construction site problem by making it possible to adopt a vertical gas flow system, and at the same time can process a larger amount of dust-containing gas with the same installation area and has a greater dust collection effect. be.

(Means for Solving the Problems) In order to achieve the above object, the inventors of the present invention have made extensive studies on the structure of dust collection electrodes, discharge electrodes, etc. On the electrode plate, at equal intervals from the edge,
By providing a partition plate section that functions as a supplementary partition plate that protrudes vertically toward the opposing dust collecting electrode plate, dividing it into a small space with a rectangular cross section, and installing a discharge electrode with a crossed needle in the center. The present invention was achieved by discovering that a vertical gas flow system can be employed in a dry electrostatic precipitator.

That is, the present invention provides a dust collecting electrode chamber that includes dust collecting electrode plates vertically arranged in parallel in an electrostatic precipitator casing and discharge electrodes arranged at equal intervals between the dust collecting electrode plates. In a dry electrostatic precipitator that circulates process gas and electrically collects and removes fine particles floating in the gas, each dust collecting electrode plate is vertically protruded toward the opposing dust collecting electrode plate. The partition plate portions are provided at equal intervals from the edge and at intervals longer than the distance between the dust collection electrode plates, and the partition plates of the pair of opposing dust collection electrode plates are slightly spaced apart from each other so that the dust collection electrode plates are flat. This invention relates to a dry type electrostatic precipitator characterized in that a small space having a rectangular cross section is formed with a section, and the discharge electrodes are each composed of a discharge electrode with crossed needles and are located at the center of the small space.

In the electrostatic precipitator of the present invention, the width of the flat part between each partition plate of the dust collecting electrode plate is preferably larger than the interval between the opposing dust collecting electrode plates, and a bar is provided at the bottom of the dust collecting electrode plate. It is preferable that a hammering member is provided at the end of the attached bar so that it can be hammered, thereby completely knocking off the dust that collects on the dust collecting electrode plate.

In addition, the partition plate attached to each dust collection electrode plate serves as a reinforcement plate for the dust collection electrode plate, and each partition plate can also function as a dust collection electrode, so the dust collection area is approximately 80.
This increases the dust collection area by more than %, and when used in combination with a discharge electrode with crossed needles, corona discharge is relatively evenly applied to the inner surface of a small space with a rectangular cross section, and ion wind is applied evenly to each part. By increasing the moving speed of the dust particles,
tsh-^nderson's formula % formula % (1) In the formula: η1・Dust collection rate (%) ω= Apparent moving speed (m/5ec) A・Total dust collection area (m2) Q=Total gas amount (m '/sec) It is possible to maximize the specific dust collection area (A/Q).

In addition, in the conventional [) ust B, P, horizontal gas flow type was adopted because there was a risk of dust re-scattering, but with the development of the above-mentioned cross-nail discharge electrode, the dust collection power became extremely strong, so vertical gas flow type was adopted. There is no need to worry about re-scattering in the flow. Vertical gas flow refers to flowing gas through the collection electrode chamber from the bottom to the top or from the top to the bottom.

The present invention will be explained in detail below with reference to the drawings.

(Example) Fig. 1 shows a discharge tube 3-2 having 11 dust-collecting electrode plates 2 arranged in parallel inside a casing l of an electrostatic precipitator and a crossed needle 3-1 between each dust-collecting electrode plate 2, 2. 1 shows, in cross section, a part of an electrostatic precipitator according to an example of the present invention, which is equipped with a discharge electrode 3 made of. As shown in the figure, in the electrostatic precipitator of the present invention, each dust collecting electrode plate 2 is
Vertical partition plate portions 2-2 are provided that protrude perpendicularly toward the opposing dust collecting electrode plates at equal intervals from the edge, and the pair of partition plates of the opposing dust collecting electrode plates are slightly spaced apart from each other. Then, a small space 4 having a rectangular cross section is formed with the flat portion 2-1. In the center of this small space 4, a discharge electrode 3 consisting of a discharge tube 3-2 equipped with a crossed needle 3-■ shown in FIGS. 2A and 2B is installed.
It is suspended vertically from the upper frame in the same way. That is, in the illustrated electrostatic precipitator, the dust collecting electrode chamber is formed by a total of 80 small spaces 4, 10 in the horizontal direction and 8 in the vertical direction between the dust collecting electrode plates at both ends. Normally, the interval (Ill) between the dust collecting electrode plates 2, 2 is 200 to 400 mm, and the width of the flat part 2-1 (
β1) is 300 to 450 mm, and in the illustrated dust collector, W・300 mad, L=148 mm, H2
=4tun, Ws-135mm, 1.・375mm
It is.

Further, FIGS. 2A and 2B show an example of the discharge electrode 3 with crossed nails. The discharge tube is a steel tube with a diameter of 17 to 34 mm;
.

The one shown is SGP 2O.
It is A. The discharge needle 3-1 is a steel wire with a diameter of 2 to 5 mm. The easiest and cheapest way to install this discharge needle 3-1 is to sharpen both ends of a thin round wire, pass it through a hole provided in the discharge tube 3-2, and weld it so that it is perpendicular to the discharge tube. This is preferable because a discharge electrode can also be produced. The installation angle θ1 of the discharge needle 3-1 shown in FIG. 2A (the angle with respect to the center line parallel to the dust collecting electrode plate passing through the center of the cross section of the discharge wire) is 25 to 40 degrees, and the angle θ2 of the needle amount is 50 to 40 degrees. It is 80°.

It is preferable that the needle length 12 is 100 to 150 ff1m and the interval 13 between every other needle is 100 to 150 mm. For example, in the illustrated example, θ1=30°, θ2・60°
, β2・120 mm, R3”120ml11.

Next, each dust collecting electrode plate is composed of a flat part 2-1 and a partition plate part 2-2 as described above, and components a, shown in cross section in FIG. 3,
It is practically preferable to form the structure by appropriately combining b and C as shown in FIG. Component a,
The shapes of b and c are as shown in Figure 4, and the height H is usually 20
It is appropriately selected within the range of 00 to 6000+ nm.

A part of one dust collection electrode plate 2 formed by appropriately combining the above members a, b, and c is shown in FIG. 5, and its side surface is shown in FIG. 6, along line A-A in FIG. The cross-sections are shown in Fig. 7. However, in the drawings, 5 indicates an upper bar, 6 indicates a lower bar, and 7 indicates a hammering member. The illustrated dust collecting electrode plate is a dust collecting scraper plate located in the middle, and one of the partition wall portions 2-2 is not present in the dust collecting electrode plates at both ends.

In the illustrated dust collecting electrode plate, members a, b, and c are tightened with bolts and nuts to form one dust collecting electrode plate.
Of course, it is not limited to this only.

The completed dust collecting electrode plates are assembled into a desired number of dust collecting electrode plates and arranged accurately to form a rectangular square small space collective cross section as shown in FIG. As described above, the discharge tube is suspended from the upper frame in the center of the rectangular shape arranged in this way.

(Function) Now, when the above-mentioned upper framework is insulated from the earth (grounding part) and connected to the negative electrode of a high voltage DC, the tip of the needle of the discharge tube is ionized and corona discharge occurs. As the voltage is gradually increased, the corona discharge becomes vigorous and reaches 0.8 mA/per 12 dust collector plates.
A discharge current of more than m2 begins to flow. The current gradually increases and can reach 1.2mA7m2, but no spark occurs in this area. The corona discharge in this case is different from the corona discharge phenomenon in the case of a simple discharge electrode, and is a discharge from a fixed bright spot.

In the case of a discharge line, it is a fluctuating bright spot that moves 50 to 80 mm vertically. Therefore, the movement of the negatively charged dust particles in the space in the duct also moves while shaking up and down and also while being subjected to resistance due to the viscosity of the gas, so that the moving speed ω of the particles decreases. Furthermore, since the needle tip extends close to the dust collection pole surface and the needle tip is sharp, the potential gradient of the corona discharge from the needle tip becomes high and the corona starting voltage becomes low. Therefore, good dust collection can be achieved with a large corona current of 0.8 m^ per dust collection area.

It is said that 0.2mA/m'' is sufficient for dust collection on the surface of a general dust collection electrode plate, but a current four times that amount flows.Therefore, high efficiency can be obtained.Also, the spark starting voltage is The spark starting voltage between the surface of the vibrator and the surface of the flat part is very high because it is the surface of the tube and the surface of the dust collecting electrode plate.If the gas composition is good, the voltage can be increased to 8KV/cm or more. If the artificial dust content is large and the particles are small and the discharge wire is small, the discharge current will be very small, and in some cases, the current will hardly flow and the terminal voltage of the rectifier will be three times as high. As a result, sparks occur frequently and the dust collection rate is greatly reduced.Even in such a case, the present invention allows a corona current to flow at a low voltage, so that such a situation does not occur and good operation can be performed.

(Effects of the Invention) As explained above, in the electrostatic precipitator of the present invention, the total dust collection area A of the formula (1) is 81 more than just a flat plate type
~85% larger. This is because a dust collection electrode partition plate (intermediate supplementary plate) is placed in a small space, and this partition plate functions on both sides in the same way as the dust collection electrode plate surface, so the dust collection rate is greatly improved. Rise.

Furthermore, the following advantages can be obtained compared to conventional electrostatic precipitators using simply parallel dust collecting electrodes.

a) In most cases, there is no need for a lower framework to prevent the lower part of the discharge electrode from swinging. However, it is necessary to bind a series of discharge tubes in each duct (small space) with one bar.

b) Slight displacement and subsidence of the main body foundation is acceptable.

I don't feel any inconvenience with the individual subsidence of 49 mm inside and outside.

C) Even if the distance between the discharge needle of the discharge electrode and the electrode plate surface becomes slightly narrow due to slight distortion of the collecting plate surface or dust accumulation, operation can be performed without causing sparks.

For example, even if the distance between the tip of the needle and the surface of the electrode plate is off by about 173 degrees, it can be operated without sparking.

d) When the electrical resistance of the dust is high <10"0 cm, it is possible to operate at a relatively high voltage even when a simple discharge wire would have to operate at a low voltage due to frequent sparks = e) The hammering of the dust collection electrode is done at each Since each board is hammered sequentially at regular intervals, the amount of dust that is re-dispersed after one lighting session is small.

Further, the scattered dust is immediately collected at a place a little higher than the place where it was scattered, so the amount of dust flying into the air is extremely small or almost non-existent.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a dry electrostatic precipitator as an example of the present invention, FIG. 2 A is a cross-sectional view of a discharge electrode used in the dry electrostatic precipitator of the present invention, and FIG. Figure 3 is a sectional view of the constituent members a, b, and C of the dust collecting electrode plate; Figure 4 is a perspective view of members a, b, and C in Figure 3; Figure 5 is a side view of the discharge electrode in Figure A; The figure is a front view of an example of the dust collecting electrode plate used in the dry electrostatic precipitator of the present invention, FIG. 6 is a side view of the dust collecting electrode plate of FIG. 5, and FIG. 7 is the A-- It is a sectional view along the A line. 1... Electrostatic precipitator casing 2... Dust collecting electrode plate 2-1... Flat part of the dust collecting electrode plate 2-2... Partition plate part 2-3... Mounting plate of member C Part 4...Small space 5...Upper bar 6...
Lower bar 7... Hammering member 0 0
0 Go) Figure 4 Figure 5 Figure 7 Figure 6

Claims (1)

[Scope of Claims] 1. A dust collecting electrode chamber equipped with dust collecting electrode plates arranged vertically in parallel in an electrostatic precipitator casing and discharge electrodes arranged at equal intervals between each dust collecting electrode plate, In a dry electrostatic precipitator that circulates the gas to be treated in a direction and electrically collects and removes fine particles floating in the gas, each dust collecting electrode plate projects vertically toward the opposing dust collecting electrode plate. The vertical partition plates are provided at equal intervals from the edge and at intervals longer than the interval between the dust collection electrode plates, and the partition plates of pairs of opposing dust collection electrode plates are slightly spaced apart from each other to collect dust. 1. A dry electrostatic precipitator characterized in that a small space having a rectangular cross section is formed with a flat part of an electrode plate, and a discharge electrode is composed of a discharge electrode with crossed needles, and each of the discharge electrodes is located at the center of the small space. 2. The dry electrostatic precipitator according to claim 1, wherein the lower bar of the dust collecting electrode plate is provided with a hammering member for dropping dust collected on the electrode plate by impact from a hammer.