JPH04502577A - Filter for separating particulates from gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Field of filter technology for separating particulates from gas The present invention is a filter for separating fine particles contained in gas through a filter membrane. Regarding.

Background technology This type of filter is used, for example, to purify gas flowing through the flue of a waste incineration plant. The gas is collected in the filter membrane that purifies the gas inside the filter. The dust is encouraged to form as thick a dust salt as possible. this is that when the thickness of the dust salt increases, the gas passing through the filter membrane increases as its thickness increases. This means that the gas will travel a longer distance, allowing more dust to be separated from the gas. It is from.

In flue gas purification equipment, gaseous substances such as sulfur oxides and hydrogen chloride are A catalytic reactor is used to separate impurities from the gas by injecting an absorbent that reacts with the impurities. It will be done. However, in the case where a filter is placed downstream of this contact reactor, , reaction products and unreacted absorbent flow into the dust mass formed on the filter membrane. Deposit.

Therefore, impurities that are not separated in such a catalytic reactor are removed in the filter. The length of residence time in the dust salts will affect the separation performance of the filter. This will have a decisive impact. As the thickness of the dust salt increases, the residence time increases accordingly. The separation performance is improved by the length of time.

As the thickness of the dust salt increases, the pressure drop of the gas passing through the filter increases. . However, at this time, the energy expended by the fan increases, and If the pressure drop is large, depending on the capacity of the fan, it may be difficult to pass through the filter. Sufficient pushing pressure cannot be obtained. Therefore, the resistance that dust salts provide to the fluid Increasing the thickness of the dust salt should be limited depending on the degree of pressure drop determined by the No.

On the other hand, in filters that purify flue gas discharged from waste incineration plants, , when garbage contains moisture, a large amount of water vapor is generated, and at this time hydrogen chloride is released. Due to the generated dust, it is difficult to form thick dust salts on the filter. If If lime is injected into the contact reactor upstream of the filter, hydrogen chloride will be mixed with lime. It reacts and turns into highly hygroscopic calcium chloride. This calcium chloride is water vapor The dust salt formed at this time is dense, sticky and heavy. Dust becomes salt.

This results in a resistance to the fluid and a resulting pressure drop in the fluid passing through the dust mass. will certainly increase, but even if this reaches its maximum, the dust salt will The thickness of the filter is still insufficient to fully remove the water and gaseous impurities, resulting in Purification of the gas is not carried out properly.

In order to improve the separation performance of Conofilter, gaseous impurities are converted into droplets inside the filter. A method is used in which the liquid is condensed at low operating temperatures. Droplets of this impurity This method can remove a larger amount of impurities than when it is in a gaseous state. Therefore, the separation performance of the filter is excellent and high. But dust salt is thinking If it becomes more moist and sticky than it already is, it becomes difficult to separate it from the filter membrane.

Additionally, the operating temperature of the filter, which should be kept too low while this method is carried out, is Therefore, it is difficult to maintain this.

In addition, when forming a powder catalyst layer on the outside of the filter membrane, for example, nitrogen oxide Ammonia can be injected into the gas passing in front of the filter for catalytic reduction of be.

However, this catalytic material is often too heavy and difficult to reduce nitrogen oxides. The filter membrane may flake off before it is thick enough to be useful. There is a problem in forming a catalyst layer on the outside of the catalytic layer.

Therefore, the object of the present invention is to remove the particulates contained in the gas and the gas on the outside of the filter membrane. Dust salts that can efficiently separate dust-like impurities or catalysts for catalytic reduction An object of the present invention is to provide a filter in which a medium layer is formed.

Disclosure of invention The above purpose is to provide a fiber body so as to protrude from the outer surface of the filter membrane, and to An electric conductor is placed inside and/or outside the fiber to charge the fiber. This can be achieved by

Preferably, the electrical conductor inside the filter membrane is a core material provided inside the filter membrane. and the outer electrical conductor is an electrode placed outside the filter membrane.

Maintain an applied voltage of 0 to 50 KV, preferably 20 KVO between the core material and the electricity. I will do it.

When configured with a core material grounded, the electrode is connected to a voltage of 0 to 50 KV, preferably 20 KV. Apply pressure.

When the electrode is grounded, the core material has a voltage of 0 to 50 KV1, preferably 20 kV. Apply voltage.

The filter membrane is a textile material, especially Teflon or polyfluoroethylene. It is preferable that the fiber be made of fiber.

The fibrous body is preferably composed of polyfluoroethylene fibers, and has a length of 10 ~50mm, preferably 30 mm, thickness 0. 2tsm equivalent or less 0.1 pm, preferably 0.1 pm.

Brief description of the drawing FIG. 1 is a longitudinal sectional view of a bag filter according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a part of the bag filter shown in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION The bag filter 1 shown in Figure 1 comprises a housing 2, a gas, e.g. Inlet 3 for taking in flue gas from the plant and outlet 4 for discharging purified gas has. The interior of this housing 2 is divided by plates 5 to 3 and 3, respectively. It is divided into a waste gas chamber 2a and a purge gas chamber 2b, which communicate with the outlet 4. usually , the bag filter 1 has 100 to 500 bags arranged vertically across the gas flow direction, It usually has 300 filter bags 7.

The upper ends of these filter bags 7 are connected to the bottom surface of the plate 5 with its opening and the plate 5 It is removably attached so that it communicates with the communication hole 6 of. This filter bag 7 The length is 3-5m, usually 5m, and the diameter is 100-200+U.

It is usually 125 to 130 mm. The distance between two adjacent filter bags 7 is 300-5001mm usually 400ii. In addition, the interval in the transverse direction is 300~ 500 ms, usually 400 mm.

The electrodes 8 are connected between the filter bags 7 at the diagonal intersections of the four adjacent filter bags 7. One electrode is arranged in line at each point.

As is clear from FIG. 1, the lengths of these electrodes 8 are the same, but the length of each electrode is the same. It is thinner than the rutabag 7 and is formed into a circular bar shape. This electrode 8 The diameter is 20-40 mts, usually 30 titx. Also, the electrode 8 is attached to the plate 5. The holder (not shown) is inserted into the drilled hole (not shown) and the holder (not shown) is inserted so as not to contact the plate 5. (not shown). A voltage of 20KV is applied to electrode 8 through the holder. is added.

On the other hand, nozzles 10 are arranged in the purification gas chamber 2b above the opening of the filter bag 7. It is arranged above the filter bag 7 and across the longitudinal direction of the filter bag. A nozzle tube 9 is provided. This nozzle tube 9 is connected to a pressure tank (not shown). When removing dirt from the filter bag 7, the filter bag Air is ejected from the nozzle 10 toward the filter bag 7, and the purification ability of the filter bag 7 is increased. It is now possible to recover. Compressed air for purification is supplied at the same time and in the same nozzle tube. Squirt forcefully and repeatedly.

The nozzle tube 9 can be attached to and detached from the purification gas chamber 2b for replacing the filter bag 7. established in For the same reason, the ceiling of the housing 2 has a A plurality of doors 11 are provided which are opened and closed on both sides. Also, as is clear from Figure 1, The bottom of the housing functions as a dust pocket to collect dust separated from the gas. It is formed into a funnel shape to make it more effective. This dust is transferred to a conveyor (not shown). ) to a dust container (not shown).

As is clear from FIG. 2, the filter bag 7 is provided with a membrane so as not to impede the flow of gas. A cage 12 as a core material surrounding the main body is attached. moreover, These cages 12 are grounded via plates 5.

Moreover, as is clear from FIG. 2, the outside of the filter bag 7 has a filter bag 7 A fibrous body 13 is provided which overhangs from the membrane body. These fibrous bodies 13 are Made from the same textile material as the filter. This textile material is surrounded by a thick dust mass When operating the filter, ensure that it can withstand temperatures higher than the operating temperature. It is determined in consideration of the temperature and the thickness of the dust mass 14 formed surrounding the fibrous body 13. Ru. Acrylic fibers are applicable to temperatures between 60 and 130℃, and temperatures between 130 and 150℃. Polyester fiber for temperature, Hariton (registered trademark) for temperature of 150-180℃ For fibers, Teflon (registered trademark) fibers are applied at temperatures of 180 to 240°C.

The length of the fiber body 13 is 10-501B1%, preferably 30tats, and the thickness is 0. It is equal to or smaller than 2mm, preferably 0.1a.

In use, the bag filter 1 works as follows.

The gas containing dust passes through the inlet 3 under a certain pressure to the waste gas chamber 2 of the housing 2. guided by a. Here, the inlet 2 is provided at the upper end of the filter bag 7, and the inlet 2 is provided at the upper end of the filter bag 7. The water flows downwards outside the filter bag 7 (see illustration). filter bag The dust separated by the purification action in step 7 is returned to the filter bag 7 by the inflowing gas. It doesn't circulate.

between the electrode 8 to which an applied voltage of 20KV is applied and the filter bag 7 to which it is grounded. An electric field is maintained in the waste gas chamber 2a due to the potential difference, and an electric field is maintained outside the filter bag 7. The action also extends to the fibrous body 13 in the direction of the arrow (see FIG. 2).

When the gas passes through these electric fields, the dust particles have a corresponding charge on the fibers 13. and is charged with the opposite charge.

Therefore, gas passes through the filter bag 7 and the cage 12 and heads into the interior thereof. During this process, only the fine particles are attracted to the fiber body 13. A fibrous body in which fine particles are charged When in contact with 13, these particles become electrically neutralized and repel each other. Not at all. Then, it accumulates on the outer surface of the filter bag 7 and forms a lump. particle size Since relatively large particles gather outside the filter bag 7, there are many dust particles inside. It will have a cavity of. Therefore, the resistance to the fluid and therefore the pressure of the fluid Due to this porous dust mass, the force drop becomes just the right value to maintain separation performance.

The bag filter 1 according to the invention has the same pressure drop as the conventional bag filter. However, compared to the conventional one, the dust mass is much thicker. did Therefore, this bag filter 1 provides better separation with the same pressure drop as the conventional one. performance can be obtained.

After this, the gas flows from inside the filter bag 7 to the purified gas chamber 2b and further to the outlet. 4, flows into a chimney (not shown), and is released into the atmosphere. Also, the filter bag The fibrous body 13 protruding from the outside of the filter 7 serves as a contact point for the filter to reduce nitrogen oxides. When used for media, heavy dust particles accumulate on the outside of the filter bag 7. It also acts as reinforcement to support the weight.

Naturally, the present invention is not limited to the embodiments described above.

The present invention may be modified and implemented in a manner different from the scope of the claims.

That is, a voltage of 20 KV is applied to the electrode 8, while the cage 12 is grounded. Then, the connection point on the grounding side is electrode 8, and a voltage of 20KV is connected to cage 12. It's okay.

Furthermore, the voltage applied between the electrode 8 and the cage 12 is not limited to 20KV; It can be made different from that. and preferably to maximize effectiveness. It should be between 0 and 50kv. Furthermore, for example, the The electrode 8 placed thereon has a hollow cylindrical shape and is configured as an electrode with a gas permeable structure having a large number of through holes. It is possible to accomplish this.

Furthermore, the circular rod-shaped electrode 8 can of course be configured in a rectangular shape, or in a helical shape. It is also possible to configure

Fig, 2 international search report international search report PCT/SE　90100002

Claims (9)

[Claims] 1. a bag-shaped filter membrane (7) formed from a permeable material; The membrane (7) has at least one opening for releasing gas flowing through the membrane body. and a core material (12) having a gas permeable structure disposed inside the filter membrane (7). In the filter membrane (7), the outer surface thereof extends from the membrane body. A sea urchin fiber body (13) is provided inside and/or outside the filter membrane (7). It is characterized in that electric conductors (12, 8) are arranged to charge the fibrous body (13). A filter to separate particulates from a characteristic gas. 2. The electrical conductor is constructed of a core material (12) disposed inside the filter membrane (7). 2. A filter according to claim 1, characterized in that: 3. The electrical conductor comprises an electrode (8) arranged outside the filter membrane (7). The filter according to claim 1 or 2, characterized in that: 4. Maintain an applied voltage of 0 to 50 KV between the core material (12) and the electrode (8). The filament according to claims 2 and 3, characterized in that a voltage is applied as follows. Luta. 5. The core material (12) is grounded, and a voltage of 0 to 50 KV is applied to the electrode (8). 5. The filter according to claim 4, further comprising: 6. The electrode (8) is configured to be grounded, and a voltage of 0 to 50 KV is applied to the core material (12). 5. The filter according to claim 4, further comprising: 7. Claims characterized in that the filter membrane (7) is constructed from a textile material. The filter according to any one of items 1 to 6. 8. The filter membrane (7) is made of polyfluoroethylene fiber. The filter according to claim 7. 9. The fiber body (13) is made of polyfluoroethylene fiber, and its length is 1. 0 to 50mm, with a thickness equal to or smaller than 0.2mm. The filter according to any one of claims 1 to 8, characterized in that the filter is characterized by: