JPS62176558A - Dust removing device - Google Patents

Abstract

PURPOSE:To reduce the lowering in dust removing capacity, by opposedly arranging a negative discharge electrode and a positive electrode in order in a gas flowing direction and providing an ionization part forming an unequal electric field in a gas flow passage and a volume part wherein the cross-sectional area of a powder passage increases from the ionization part between both electrodes. CONSTITUTION:The dust in the gas introduced into an ionization part 2 from a gas inlet 6 is negatively charged in the ionization part 2 and flocculated to be grown into coarse particles in a volume part 3 by the abrupt decrease in a gas flow speed within said part 3 to enter the filter cylinder 12 made of conductive ceramics of a filtering part 4. The negatively charged dust is repelled from the inner peripheral surface of the negatively charged filter cylin der 12 and only clean gas passes through a filter wall to be exhausted from a clean gas outlet 14. A positive electrode rod 15 attracts the negatively charged dust to promote the removal of dust. The dust separated from the gas is fallen to a dust discharge part 5 to be attracted to and accumulated on the bottom part thereof by electrostatic force and appropriately discharged from a dust discharge port 16.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dust remover that removes dust by passing a gas containing fine dust through it.

Conventional technology As a dust removal device for gases containing fine dust, such as coal combustion gas and coal gasification gas, an electric collector uses corona discharge to charge the dust in the gas and electrostatically collect it. Dust container (
electrostat precipitato
r; EP) is well known.

This device forms an unequal electric field by applying a DC voltage of opposing volts, with the discharge electrode being negative and the dust collecting electrode plate on which dust is attached being positive, to generate a corona discharge. The positive ions immediately lose their charge at the discharge electrode, but the negative ions flow toward the dust collection electrode, attach to dust in the airflow flowing in the electric field, and adhere to the dust collection electrode plate due to Coulomb force. Dust on the electrode plates is periodically hammered and dropped into a hopper.

Electrostatic precipitators can easily capture fine particles, have little gas pressure loss, and can handle a wide range of gas (soot) properties (for example, particle size 0.001/'% gas temperature 500°C, gas However, on the other hand, the device for applying the DC voltage of the enemy Pol F becomes large-scale, and the dust accumulated on the dust collection electrode releases electric charge. There is a phenomenon in which dust separates from the dust collection electrode, and in this case, dust collection performance is significantly reduced. In addition, due to the accumulation of dust on the dust collecting electrode, the electrical discharge action decreases,
Also, when the temperature reaches a certain level, the electrical resistance becomes unstable,
Dust collection performance deteriorates. Another drawback is that mechanical peeling such as hammering is periodically required to collect the dust accumulated on the dust collecting electrode.

In addition to the above-mentioned dust remover for removing dust from exhaust gas, a dust collector in which a porous furnace tube made of heat-resistant ceramic is installed inside a housing is about to be put into practical use.

This type of precipitator is suitable for handling high temperature gases such as 500°C or higher.
It is said to be able to process gases up to about 100°C, making it suitable for removing dust from high-temperature gases such as coal combustion gas and coal gasification gas. In addition, the dust collection rate is high and it is possible to collect dust of less than 10 μm, and the processing capacity can be easily increased by increasing the number of plates, making it possible to process large volumes of gas with small equipment costs. It has the advantage of being able to do so.

However, the drawback is that the pores of the furnace tube become clogged with dust, and especially in the case of coal combustion gas, tar adheres, reducing the dust collection performance. Pulse backwashing is used to remove clogging, but it is not sufficiently effective against tar adhesion. Also, the pressure loss is 1 to 2 digits lower than that of an electrostatic precipitator.
The order of magnitude is also large, and that much extra power is consumed.

Purpose The present invention utilizes the advantages of an electrostatic precipitator, which is currently considered to have the best dust collection performance, and a dust collector using a ceramic furnace tube, which is said to be suitable for removing dust from high-temperature, large-capacity gases. The purpose of the dust collector according to the present invention is to provide a dust removing device that partially combines the above features and eliminates the drawbacks. The discharge electrode and the old electrode are placed opposite each other, and by applying a DC voltage between the two electrodes, the cross-sectional area of the gas flow path is increased from the mm part that forms an unequal electric field in the gas flow path and the gm part. A porous furnace tube through which gas passes through the tube wall and a means for negatively charging the tube wall.

With the above configuration, corona discharge occurs in the ionized part where an uneven electric field is formed, positive ions are immediately neutralized by the discharge electrode, and negative ions travel toward the positive electrode, killing dust passing through this electric field. The contained gas, for example, soot dust particles in soot and smoke, acquire a negative charge and become a negatively charged body.

The gas flow rate is set high in the ionization section, and the dust particles, which are negatively charged bodies, are guided into the volume section together with the gas without adhering to the positive electrode. In the volume part, the cross-sectional area of the flow path increases, so the flow velocity decreases, and negatively charged dust particles adhere to each other, causing agglomeration and coarsening.

Next, the coarse particulate dust led to the filtration section 5 is drawn into the furnace cylinder together with the gas, but since the furnace cylinder is negatively charged, the negatively charged coarse particulate dust is electrostatically repelled. Only gas passes through the pores of the furnace cylinder to remove dust, and only clean gas passes through the walls of the furnace cylinder. The repulsed negatively charged dust particles fall by gravity and are guided to the dust discharge section. Since the dust discharge section is normally grounded, negatively charged dust particles are also attracted to the discharge section by electrostatic force.

Embodiments of the present invention will be described in detail below based on the drawings.

In the embodiment of the present invention shown in FIG. 1, the inside of the dust removal casing 1 is divided into an ionization section 2, a container section B, an aperture section 4, and a dust discharge section 5 from the top. Of course? There is no partition wall between the front part 2 and the volume part 6, and they are distinguished by the fact that the cross-sectional area of the volume part 3 is larger than the [i77 area of the ionization part 2].

The upper end of the ionization section 1 is a gas conduit 6 containing dust, to which a conduit for the gas to be treated is connected.

Inside the ionization section 2, a negative discharge electrode 8 connected to the power supply section 7 and a grounded positive electrode 9 are placed opposite each other, and a DC voltage of several thousand to an enemy voltage can be applied between the two electrodes. It has become.

The volume section 3 following the ionization section 2 consists of a truncated conical enlarged section and a large diameter section, in which the gas flow rate decreases rapidly.

Partition walls 10.11 are provided above and below the filtration section 4, and a plurality of porous tubes 12 made of a conductive heat-resistant material (usually a ceramic material are used) connect the upper and lower ends with electrical insulators 15.
It is supported by the partition wall 10.11 via. An outlet 14 for the clean gas that has been filtered by the furnace tube 12 is provided on the side wall of the chamber 4 . The conductive ceramic furnace cylinder 12 is connected to the negative electrode of the power supply section 7, so that a negative voltage of several thousand to volts can be applied thereto. A grounded positive electrode rod 15 is provided at the center line of each furnace cylinder 12 .

The lower part of the dust discharge part 5 is shaped like a hopper, and a dust discharge port 16 that can be opened and closed is provided at the lower end of the hopper.

The wall of the hopper part of the dust discharge section is electrically neutral, but the wall near the discharge port at the lower end is of positive polarity.

Since this device is configured as described above, 1. Ionization part 2
As mentioned above, the dust in the gas introduced from the gas population 6 is negatively charged in the ionization section 2, and as the gas flow rate rapidly decreases in the volume section s, it becomes agglomerated into coarse particles, and the dust in the atomization section 4 is The negatively charged dust that enters the furnace cylinder 12 is repelled by the negatively charged inner peripheral surface of the furnace cylinder, and only the clean gas passes through the furnace cylinder wall and exits from the clean gas outlet 14. Attracting charged dust promotes dust removal. The dust separated from the gas falls into the dust discharge part 5, is attracted and deposited on the bottom part by electrostatic force, and is discharged from the dust discharge port 16 as appropriate.

As a means for negatively charging the conductive ceramic porous furnace tube 12 in the aperture section, as shown in FIG. A perforated metal tube 18 is provided with an electrical insulator 17 interposed therebetween, a negative voltage is applied to the porous furnace tube 12, and the metal tube 18 is grounded, thereby creating a negative induction in the porous furnace tube 12. An electric charge may be generated.

With this configuration, dust in the gas that has entered the inside of the furnace tube 12 is repelled by the inner surface of the furnace tube 12 and falls downward, similar to the embodiment shown in FIG.
After passing through the wall of the perforated metal tube 18, the gas is discharged from the clean gas outlet. Ceramic tube 1
2 is brittle, so the metal tube 18 also serves as a reinforcing material. Needless to say, if the gas being treated is at a high temperature, the perforated metal tube 18 must be made of a heat-resistant metal.

In addition, by introducing a gas containing dust to the outside of the porous filter cylinder,
In the case of a dust removal device having a structure in which clean gas is permeated into the inside of a porous furnace tube and recovered, the perforated metal tube may be provided with a gap inside the furnace tube.

Moreover, when the furnace cylinder 12 is made of non-conductive ceramic,
As shown in FIG. 3, a conductive winding 19 is provided in contact with the inner circumferential surface of the furnace cylinder 12, and a negative voltage of several thousand volts to 10,000 volts is applied thereto. The rest of the structure is the same as the embodiment shown in FIG.

In this case as well, as shown in Figure 4, ? A perforated metal 'C? 18, and by applying a positive voltage thereto, a negative induced charge may be generated in the winding 19. As in the embodiment shown in FIG. 5, a porous furnace tube made of non-conductive ceramic In a type of dust remover that filters clean gas from the outside to the inside of the p-tube 12, the conductive winding 12 may be provided in contact with the outer peripheral surface of the p-tube 12. Although FIG. 5 shows a structure in which one porous furnace tube is provided for the sake of explanation, in an actual apparatus, a plurality of porous furnace tubes are provided. In this embodiment, the 5 furnace cylinder 12 is provided in the gas inlet chamber 6 which also serves as a volume part, and the upper side of the wall 10 supporting the upper end of the s furnace cylinder 12 whose lower end is closed is the 5 filtration chamber through which clean gas passes. It is 4. An ionization section 2 is provided in the gas introduction path to the gas inlet chamber 3, and gas containing dust is introduced into the chick section. A clean gas outlet 14 is provided in the filtration chamber 4 . Further, a dust outlet 16 is provided at the lower end of the gas inlet chamber 3.

Since the operation of this embodiment is clear from the explanation up to this point, the explanation will be omitted.

If the cross-sectional structure of a porous ceramic furnace cylinder is schematically shown in FIG. 6, a large number of cavities 31 of about several tens of micrometers are interspersed within the ceramic substance 6o, and these voids are separated by a diameter of several micrometers from each other. It has a structure in which the passages 32 communicate with each other through a large number of passages 32. The cross sections of these cavities 31 and passages 32 are exposed on the surface of the furnace cylinder.

In a conventional dust remover using a porous ceramic furnace tube, when gas containing dust passes through the passage 32 and cavity 31 from one side of the filter tube wall to the other side, these filters and As a result, dust larger than the passage diameter is blocked from passing through and removed.

Therefore, in order to reduce the minimum particle size of the dust to be removed, it is necessary to reduce the diameter of the passage 32, which increases the pressure loss when gas passes through, and increases the capacity of the blower. Alternatively, it may be necessary to increase the number of furnace tubes, leading to an increase in cost.

On the other hand, in the dust removal device of the present invention, the dust in the gas is removed by negatively charging the dust, and also by negatively charging the furnace cylinder and electrostatically repelling it. The diameter of the passageway 32 within 30 can be significantly larger than the minimum particle size of the dust to be removed. Moreover, since the dust that comes to the vortex part is coarse-grained, the pressure loss when the gas passes through is reduced, and conversely, the passing flow rate can be increased, so the number of furnace tubes can be reduced. It is possible to reduce costs.

Effects As explained above, in the dust removal device according to the present invention, even when the gas to be treated reaches a certain high temperature, the dust removal function of the ceramic porous furnace tube does not deteriorate, and dust does not adhere accurately. The drop in dust removal ability is less than in the case of an electric precipitator.

Furthermore, since the dust removal device of the present invention uses both the filter function of the ceramic porous furnace tube and the electrostatic repellent, the dust collection efficiency is superior to both an electric precipitator and a ceramic filter. At the same time, the pressure loss is small and
Periodic hammering in the case of electrostatic precipitators and backwashing in the case of ceramic filters are also unnecessary.

In addition, the voltage applied to the ionizing part is a fraction of that of a normal electrostatic precipitator, and the device becomes an r-shaped float, contributing to cost reduction.

As described above, the present invention combines the advantages of an electric precipitator, which is currently considered to have excellent dust collection performance, and a dust remover using a ceramic porous furnace tube, and has advantages that compensate for the disadvantages. It can be said to be a dust removal device.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of an embodiment of the present invention, FIG. 2 is a sectional view showing a modified embodiment of the filter cylinder portion, and FIG. 3 is a sectional view showing another embodiment of the invention. Fig. 4 is a cross-sectional view showing a modified example of the furnace cylinder part, Fig. 5 is a cross-sectional view showing the configuration of yet another example, and Fig. 6 is a schematic cross-sectional view showing the cross-sectional structure of the porous ceramic furnace cylinder. It is a schematic diagram. 2...Ionization part 6...Volume part 4...
P vortex section 5... Dust discharge section 6... Gas population 7... DC power supply. 8... Negative discharge electrode 9... Positive electrode 10.11
... Partition wall 12 ... Ceramic porous furnace cylinder 1: J, 17 ... Electrical insulator 14 ... Clean gas outlet 16 ... Dust discharge port 18 ... Perforated metal tube 19 ...・Conductive winding Figure 2 Figure 4

Claims (4)

[Claims] (1) In a dust remover that removes dust by passing gas containing fine dust, a negative discharge electrode and a positive electrode are placed opposite each other in the order of the flow direction of the gas, and a DC voltage is applied between the two electrodes to remove the gas. an ionization section that forms an uneven electric field in the flow path; a volume section in which the cross-sectional area of the gas flow path increases from the ionization section; a porous filter tube through which gas passes through the tube wall; and a porous filter tube that negatively charges the tube wall. What is claimed is: 1. A dust remover comprising: a filtration section having means for filtering; (2) A patent claim characterized in that the above-mentioned porous filter tube is made of an electrically conductive heat-resistant material, and the means for negatively charging the tube wall is one that applies a negative voltage to the tube wall. The dust remover described in item 1 of the scope. (3) The above-mentioned porous filter tube is made of a conductive material, and the means for negatively charging the tube wall is a perforated metal tube that surrounds the filter tube with an appropriate gap and is electrically insulated from the filter tube. 2. The dust remover according to claim 1, wherein a positive voltage is applied to the metal tube. (4) The above-mentioned porous filter tube is made of a non-conductive material, and a conductive winding is provided on the inside or outside of the tube, whichever side allows gas to enter the tube wall, and a negative voltage is applied thereto. A dust remover according to claim 1, characterized in that: