JPS585104B2 - Dust collection electrode for electrostatic precipitator - Google Patents

Description

[Detailed Description of the Invention] Conventionally, electrostatic precipitators have been widely used to collect dust such as iron powder and mist floating in gas, and the discharge electrode (-) contains lead, copper, nickel, nichrome, titanium, and platinum. For the dust collection electrode (+), iron, lead, wire mesh, etc. are used.

Since metal is used for the electrode, C12, Cr, SO2°HC
Naturally, when collecting dust containing corrosive gases such as L, H2SO4, and ammonia (e.g., municipal waste incineration, flue gas desulfurization, etc.), equipment corrosion problems occur, and especially when used at high temperatures, corrosion becomes even more severe. However, there are many cases in which the device cannot withstand use due to the acceleration, and there is a strong need to consider the material of the device.

Conventionally, as a means to solve these problems of corrosion and strength under high temperatures, synthetic resins have been used.
No. 8-9088, Special Publication No. 1984-8142, Special Publication No. 1973
-2463, Japanese Patent Publication No. 50-2464, etc., but in terms of corrosion resistance and strength, the limit for normal use is 80°C or less, and at higher temperatures, strength decreases, strength deteriorates, etc. Deformation and corrosion deterioration are significant, making it unusable.

JP-A-49-10464 discloses an example of using a thermosetting resin reinforced with glass fiber, asbestos fiber, etc., and JP-A-49-8141 discloses an example in which a thermosetting resin is reinforced with glass fiber, asbestos fiber, etc. An example of using a board made of a compound is shown, but these are superior in terms of strength and heat resistance compared to the materials using synthetic resins mentioned above, but their performance depends on the performance of the thermosetting resin. be done.

For example, unsaturated polyester resins, epoxy resins, furan resins, and urethane resins disclosed in Japanese Patent Publication No. 49-8141 have excellent chemical resistance, but their strength deteriorates significantly at temperatures above 80°C.

Although fluororesin has excellent heat resistance, it has poor chemical resistance, and phenolic resin also has a usage temperature limit of about 100°C.

In high temperature ranges exceeding 100℃,
Heat-resistant glass, heat-resistant brick, which are inorganic materials, depending on the number etc.
By using heat-resistant mortar etc., the normal operating temperature 2
However, these devices require skill to install and have a complicated structure, making them prone to construction defects, which shortens their service life and increases the total cost.

Furthermore, due to the low material strength, it is difficult to construct and handle, and it is easily damaged during use.

Furthermore, since it is an inorganic material, it is impossible to use it as a conductive material.

Therefore, it cannot be used as a dry-type dust collector, and can only be used as a wet-type dust collector, which limits its use.

The present invention relates to improving these drawbacks of conventional dust collectors, and provides heat resistance and corrosion resistance that are sufficiently durable even at a normal temperature of 200°C, and are also effective in dry type dust collectors that have conductivity. , relates to a dust collecting electrode for an electrostatic precipitator having conductivity.

The present invention relates to a dust collecting electrode for an electrostatic precipitator, which contains a thermosetting resin obtained by reacting a polyfunctional epoxy compound and a polyfunctional incyanate compound, a reinforcing material, and a conductive material.

The drawing shows the lowest part of dust collection and an overall view of a commonly used flat plate electrostatic precipitator, but the shape of the dust collection electrode in the present invention may be cylindrical, plate-like, square-shaped by combining plates, etc. , there are no restrictions on its shape.

1 to 3 show a commonly used flat plate type electrostatic precipitator, and the composition according to the present invention is used for the dust collection electrode 1.

Here, there are other types of dust collection electrodes, such as tube, cylinder, and lattice shapes, and these can also be used.

A weight 3 is attached to the lower part of the discharge electrode 2, and the upper part is connected with a conductive wire 4.

Metals such as titanium, platinum, and vanadium are used for 2.

5 shows a water tray for removing dust, which is called a wet type or a semi-wet type, and a method of removing dust by mechanical hammering is called a dry type.
Either is possible.

6 is a DC power supply (c) that charges the dust particles,
There is a so-called one-stage type in which the dust collecting action of charged particles is carried out in the same electric field by means of a ground (7), and there is also a two-stage type in which electrolysis is carried out separately in the charged part and the dust collection part.

The thermosetting resin used in the present invention is a thermosetting resin obtained by reacting a polyfunctional epoxy compound and a polyfunctional isocyanate compound.

Examples of polyfunctional epoxy compounds include diglycidyl ether of bisphenol A, butadiene jepoxide, and 3,4-epoxycyclohexylmethyl-(3,4
-epoxy) cyclohexane carboxylate, etc. 2
Functional epoxy compounds, triglycidyl ether of para-aminophenol, polyallyl glycidyl ether, triglycidyl ether of trimethylolpropane, etc.
Epoxy compounds with higher functionality are used.

Examples of polyfunctional isocyanate compounds include bifunctional isocyanates such as methanedisonanate, butane-1,1-diisocyanate, diphenylsulfone-4,4'-diisocyanate, polymethylene polyphenylisocyanate, 3,3', 4.4' - A trifunctional or higher functional incyanate such as diphenylmethane tetraisocyanate is used.

The reaction between a polyfunctional epoxy compound and a polyfunctional isocyanate compound can be performed using tertiary amines such as trimethylamine and triethylamide, oxyalkylamines such as dimethylaminoethanol and dimethylaminopentanol, dimethylaniline, trisdimethylaminomethylphenol, etc. The reaction is carried out in the presence of various amines, quaternary ammonium salts such as cetyltrimethylammonium bromide and benzyldimethyltetradecylammonium acetylate, and catalysts such as 2-methylimidazole and 2-ethylimidazole.

The blending ratio of the polyfunctional epoxy compound and the polyfunctional isocyanate compound is 1 equivalent of the former to 1.5 equivalent or more of the latter.
It is preferable to use an equivalent amount or less.

Inorganic or organic fibers are used as the reinforcing material, and the type and required weight are determined based on the required strength, heat resistance, corrosion resistance, molding method, etc.

For example, in the case of alkali resistance used at relatively low temperatures, it is also effective to use organic fibers, and usually a large amount of inorganic fibers is used.

Furthermore, it is also effective to insert metal fibers such as wire mesh to further improve the strength.

Carbon powder, carbon fiber, etc. are used as the conductive material.

Carbon powder and carbon fibers can be used alone or in combination, and their types, particles, combinations, etc. can be changed depending on the required conductive performance and requirements.

Carbon powder and carbon fiber have a rating of 5 to 50% compared to dust collection and other components.
The range is 40% by weight.

The above-mentioned composition can be formed by commonly used hand lay-on molding, spray-up molding, cold press molding, pultrusion molding, extrusion molding, back molding, FW molding, press molding, etc.

The mixing ratio of the thermosetting resin and reinforcing material mentioned above depends on the molding method,
Although it varies depending on strength, corrosion resistance, heat resistance, etc., the reinforcing material content is usually 10 to 60% by weight based on the above-mentioned thermosetting resin, reinforcing material, and conductive material.

In addition, the molding temperature and time are usually 60-200℃, 30-30℃
A range of 0 minutes is used.

Machining (cutting, cutting, drilling,
(screw processing, etc.) can be easily done in the same way as with conventional FRP.

Further, this composition can be easily bonded using mechanical bonding (bolts, rivets, etc.), adhesive bonding (scarfs, batts, lap joints, etc. using adhesives) in the same manner as conventional FRP.

Example 100 g of diglycidyl ether of bisphenol A (manufactured by Dow Chemical Company, USA, DER332, epoxy equivalent weight 174, viscosity 5000 centipoise/25°C) and 4,4'-
Diphenylmethane isocyanate (hereinafter abbreviated as MDI)
174 g and 0.27 g of N-methylmorpholine were thoroughly mixed at room temperature.

In addition, 20% by weight of graphite (Shen-Etsu Graphite AP-6) was mixed with the resin to impart conductivity, and one carbon fiber (Taiyokaki EP-100) was placed on each side of the composition. .

As a reinforcing material, inorganic fiber glass cloth (FFG■FE
CR-2521-22B, plain weave, 200g/m weight)1
Five sheets were used.

For molding, carbon fiber and glass cloth were impregnated with the same weight of resin as the glass cloth, and after vacuum degassing, pressurization was carried out at 80℃ and 100℃ for 1 hour each (press pressure 50℃).
A flat plate (1 m x 2 m) was prepared using 100 kg/cm2G).

This flat plate was machined and used as a flat plate type dust collection electrode.

The dust collecting electrode of the present invention and the conventional vinyl ester resin (a styrene solution of methacrylate of novolak epoxy resin) were used, the other material composition was the same, the molding time was 60℃, 3 hours. Made by hand molding.

The dust collection electrode was placed in an electrostatic precipitator for sulfuric acid mist at 150°C, and 150% of the cut-out specimen of the dust collection electrode plate was used after two months of operation.
The test results at ℃ are shown in Table 1.

In other words, the dust collecting electrode according to the present invention has almost no change in mechanical properties, electrical properties, or other properties, but the dust collecting electrode made of conventional materials has a retention rate of 40 coefficients in terms of mechanical properties, significant strength deterioration, and surface deterioration. The roughness, appearance, etc. changed significantly, and as a result, the electrical characteristics became almost non-conductive, and the strength of the entire device was close to its limit as a structure, and it was confirmed that long-term use was impossible. It was done.

In the above table, the surface roughness was measured using a surface roughness meter SURFCOM manufactured by Tokyo Seimitsu Co., Ltd., and the surface roughness was expressed using the maximum height (Hmax) of JIS B 0601.

The weight reduction rate was determined by measuring the initial weight W of the dust collecting electrode plate and the weight W' after 2 months.

It was calculated using the following formula.

Other properties were measured according to JIS K 6911-1970.

The dust collection electrode of the present invention used in an electrostatic precipitator for sulfuric acid mist at 150°C has been used for one year, but no change has been observed, the dust collection efficiency is the same as the initial performance, and it is corrosion resistant and heat resistant. , conductivity, etc. are sufficient.

The dust collecting electrode for an electrostatic precipitator according to the present invention has the characteristics of high strength and heat resistance, as well as arc resistance, high temperature corrosion resistance, high temperature dimensional stability, and dust resistance required for a dust collecting electrode for an electrostatic precipitator. Various performances such as removability are significantly improved compared to conventional dust collection electrodes.

Regarding the above performance, Table 2 shows a comparison between the dust collecting electrode according to the present invention and the conventional dust collecting electrode.

In Table 2, the dust collection electrode plate according to the present invention is the dust collection electrode plate described in the above embodiment, and the conventional dust collection electrode plate is
The electrode was obtained by hand molding using a styrene solution of methacrylate of novolak epoxy resin as the resin, and the other material composition, molding temperature, and time were the same as those of the dust collecting electrode of the present invention.

1) About arc resistance In electrostatic precipitators, arcs occur on the dust collecting electrode because a constant voltage is applied between the discharge electrode and the dust collecting electrode. This results in a loss of properties and a decline in dust collection performance.

In the dust collecting electrode according to the present invention, arc resistance is significantly improved.

The table shows a comparison of the surface roughness of the dust collection electrode plates.

2) Regarding high temperature corrosion resistance Electrostatic precipitators usually process corrosive gases, so
Deterioration of strength and corrosion resistance at high temperatures are important issues.

Conventional dust collecting electrodes had limited performance, but the present invention significantly improves its performance.

The table shows the weight change rate of the dust collection electrode plate when treated with SO2 and HF.

3) Regarding high-temperature dimensional stability, the interval between the discharge electrode and the dust collecting electrode, which is the lifeblood of an electrostatic precipitator, must always maintain a certain degree of accuracy, and if the accuracy is poor, the dust collection performance will deteriorate significantly. .

In conventional dust collection electrodes, the dust collection electrode is deformed when used at high temperatures, but in the dust collection electrode of the present invention, this deformation is largely prevented, and the deterioration in performance is reduced.

The table shows warpage and twisting of the dust collection electrode plate.

Warpage is expressed by the warpage in the length direction of the dust collecting electrode plate in units of mm, and twist is expressed by the angle of twist in the width direction.

4) Regarding dust removal ability: Dust that adheres to the dust collection electrode will cause a decline in dust collection performance, so the method is usually to vibrate the dust collection electrode at regular intervals to cause the dust that has adhered to fall off downward. adopted,
The level of dust collection performance is maintained.

However, less vibration work is advantageous in terms of maintenance and dust collection performance.

Conventional dust collection electrodes collect dust in a short period of time, so
Although it was necessary to vibrate frequently, the dust collection electrode of the present invention requires less vibration than conventional ones.

The table shows the number of vibration operations per power month.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the overall assembly of a flat plate type electrostatic precipitator, Figure 2 shows the main parts of the dust collector, and Figure 3 is a diagram of A in Figure 2.
It is a view from arrow A. Explanation of symbols, 1... Dust collection pole, 2...
Discharge electrode, 3... Weight, 4... Conductor, 5
...Water tray for removing dust, 6...DC power supply (-), 7... Earth (+).

Claims (1)

[Claims] 1. A dust collecting electrode for an electrostatic precipitator comprising a thermosetting resin obtained by reacting a polyfunctional epoxy compound and a polyfunctional isocyanate compound, a reinforcing material, and a conductive material.