JP2010201329A - Dust collector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dust collector with excellent running cost. <P>SOLUTION: The dust collector 1 includes filters collecting dust contained in air A. As at least one of the filters, main filters 30 formed by thermocompression bonding of synthetic fibers with diameters of 2-20 μm are provided, the passing speed of the air A through the main filters 30 is set to 0.1-0.2 m/min. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a dust collecting apparatus that collects dust such as oil smoke and oil droplets generated in rolling, drawing, cutting, and the like.

  When rolling, drawing, cutting, etc., there is a problem that dust with viscosity such as oil smoke or oil droplets derived from liquid such as cutting oil, lubricant, mold release agent, etc. scatters in the air and the working environment deteriorates. There is. Therefore, various dust collectors for capturing (collecting) the dust have been proposed at present. For example, an electrostatic dust collector using electrostatic coulomb force for capturing dust, or a filter for capturing dust. There are filter dust collectors used.

  However, although the electrostatic precipitator has the advantage of being able to capture fine particles such as white smoke efficiently, it has a risk of being ignited / exploded by sparks. In addition, since the electrostatic precipitator has a low trapping efficiency due to the fouling of the insulator, a filter such as a pre-filter or an after-filter is eventually required (for example, see Patent Document 1 (reference numerals 6 and 20)). . Specifically, for example, if airborne dust such as diesel carbon that is electrically conductive is included in the air, the capture efficiency is significantly reduced due to fouling, and every certain period (usually about 0.5 to 2 months). Cleaning and inspection are required. If a filter is provided, not only will the equipment cost increase, but also the running cost for filter replacement and maintenance will increase, especially when the filter needs to be replaced. Arise.

  On the other hand, the filter dust collector also has an oil film formed on the filter or accumulates suspended dust, thereby impairing air permeability and lowering trapping efficiency. In particular, in order to improve the capture performance, for example, when a HEPA filter (High Efficiency Particulate Air Filter) or a ULPA filter (Ultra Low Penetration Air Filter), which is a filter for ultrafine particles, is used, it becomes unusable. fast. In addition, these filters are expensive but have low strength and are not suitable for cleaning or the like, so they are consumables, and the running cost is remarkably increased.

  In addition, in order to reduce the disadvantages associated with such filter replacement, dust such as oil smoke is adsorbed on the filter surface to powder made of artificial zeolite or the like called precoat agent, and the oil smoke or the like is adsorbed. An apparatus that suppresses a decrease in the air permeability of the filter by collecting the powder has also been proposed (see, for example, Patent Document 2 (FIG. 1)). However, this apparatus also increases the running cost because the powder is consumed. In addition, since powder supply means and powder recovery means are required, the cost of the equipment increases, and the powder that adsorbs dust such as oil smoke becomes industrial waste, so the cost for processing it is necessary. As a result, the running cost increases.

JP 2001-293394 A Japanese Patent Laid-Open No. 10-296026

  The main problem to be solved by the present invention is to provide a dust collecting device having excellent running cost.

The present invention that has solved this problem is as follows.
[Invention of Claim 1]
A dust collecting device provided with a filter for capturing dust contained in air,
As at least one of the filters, a main filter formed by thermocompression bonding of synthetic fibers having a diameter of 2 to 20 μm is provided.
The ventilation rate of the air passing through the main filter is configured to be 0.1 to 0.2 m / min.
A dust collecting device characterized by that.

[Invention of Claim 2]
The main filter is
A sheet having uneven embossing is pleated, and this pleat folding is repeated to form a cylindrical shape.
And it is arranged so that the pleat fold line extends vertically,
The dust collecting apparatus according to claim 1.

[Invention of Claim 3]
A cylindrical pre-filter that circumscribes the main filter is provided,
The dust collecting apparatus according to claim 2.

[Invention of Claim 4]
A plurality of the main filters are arranged in a direction orthogonal to at least the air flow direction,
On the front side of the plurality of main filters, a plurality of flat metal filters are arranged so as to be continuous in the orthogonal direction,
The plurality of metal filters are all arranged so that they are not parallel to the orthogonal direction and the metal filters adjacent to each other do not face the same direction.
The dust collecting apparatus according to claim 2 or 3.

  According to the present invention, the dust collecting device is excellent in running cost.

It is a top view of the dust collector of this form. It is a front view of the dust collector of this form. It is a figure for demonstrating the shape of a secondary filter and a tertiary filter.

Next, the form for implementing this invention is demonstrated.
[Outline of device]
As shown in FIGS. 1 and 2, the dust collecting apparatus 1 of the present embodiment includes a multistage filter that captures dust including a primary filter 10, a secondary filter 20, a tertiary filter 30, and a quaternary filter 40, A main body (casing) 4 having a sealed structure in which a multistage filter is installed in the inner space, and a ventilation means 3 such as a blower for blowing air A into the main body 4 are mainly included.

[Target of processing]
Air A blown into the main body 4 is air (air) containing dust such as oil smoke and oil droplets scattered during rolling, drawing, cutting, biodiesel refining, etc. The dust contained in the air A is captured.

  The dust to be captured includes, for example, dust called dice oil mist, turbine oil mist, compressor oil mist, oil diffusion vacuum pump exhaust oil smoke, food fryer fume, oil quenching / heat treatment smoke, and plating fume. . In other words, the location and origin of the dust to be captured is not particularly limited. For example, cutting oil (water-soluble cutting oil, mineral oil cutting oil, etc.), lubricant / release agent (for high-temperature press) Etc.) can be exemplified.

  The particles constituting such dust are finely divided in the air A and may have a wide distribution with a particle diameter of 0.05 μm to several tens of μm. Such dust, when at least agglomerated and reliquefied, develops adhesion and viscosity (adhesiveness). Due to this adhesion and adhesiveness, it adheres to multistage filters and the like, and diesel carbon Adsorb other dust.

[Main unit]
The main body 4 is for allowing air A containing dust to pass through a multistage filter installed therein. Therefore, the material of the main body 4 is not particularly limited, and examples thereof include metal, plastic, FRP, and the like.

  Also, the shape of the main body 4 is not particularly limited as long as the air A has a shape that passes through the filters 10, 20, 30, and 40. However, in this embodiment, the main body 4 has a shape suitable for the function and shape of each filter 10, 20, 30, 40. This will be described together with the description of each filter 10, 20, 30, 40.

  In the present embodiment, the main body 4 is provided with the air inlet 4X and the air outlet 4Y, and the air A blown into the main body 4 from the air inlet 4X passes through the filters 10, 20, 30, 40. After passing in this order, the air is discharged from the air outlet 4Y, for example, into the atmosphere.

[Ventilation means]
As a method for circulating the air A through the main body 4, any of a “push-in method” for blowing the air A into the main body 4 and a “suction method” for sucking the air A from the main body 4 can be employed. However, in this embodiment, a push-in method in which air A is blown into the main body 4 from the blow-in opening 4X by the ventilation means 3 such as a blower is adopted.

  According to this pushing method, the inside of the main body 4 has a positive pressure of, for example, 200 to 1000 Pa, so that oil drain to be described later can be easily discharged. Further, for example, since the air outlet 4Y faces the outside other than the work space or communicates with the outside, if a suction type ventilation means is provided on the air outlet 4Y side, a problem of noise occurs. However, when the push-in method is adopted in the dust collector 1 of the present embodiment, noise caused by the ventilation means 3 is absorbed by the filters 10, 20, 30, and 40, and thus the noise problem does not occur. Furthermore, since air A containing dust such as oil smoke and oil droplets does not normally contain dust that damages or corrodes the blades of the blower, the indentation method should be adopted in the dust collector 1 of this embodiment. Is particularly useful.

  The ventilation means 3 is connected to a duct 2 made of, for example, metal or plastic, and air A flowing through the duct 2 is blown into the main body 4 by the ventilation means 3.

(Fire damper)
The air outlet of the ventilation means 3 is connected to the inlet 4X of the main body 4. The inlet 4X is provided with a fire damper 5 that opens and closes the inlet 4X. The fire damper 5 is attached to the upper side of the blowing port 4X so as to be rotatable about a hinge 5A. Therefore, when the ventilation means 3 is driven and air A is blown into the main body 4 from the blowing port 4X, the fire damper 5 is rotated upward about the hinge 5A by the blowing pressure of the air A, and thus the blowing port. Open 4X. On the other hand, when the driving of the ventilation means 3 is stopped and the blowing of the air A from the blowing port 4X is stopped, the fire-proof damper 5 rotates downward about the hinge 5A by gravity and thus closes the blowing port 4X ( Cover) (mechanical opening and closing mechanism).

  In this regard, high temperature dust such as sparks may be blown into the main body 4, and an oil film is adhered to the secondary filter 20 or the tertiary filter 30. May ignite. If these are ignited, the oil film is also stuck to the blades of the ventilation means 3 and the inner wall of the duct 2, so that there is a risk of spreading to these oil films. However, in the dust collecting apparatus 1 of this embodiment, if the driving of the ventilation means 3 is stopped immediately, the fireproof dambar 5 rotates downward about the hinge 5A and the blowing port 4X is closed, so that the ventilation means 3 is closed. And it is prevented that it spreads to the oil film stuck to the duct 2 or the like.

[Multistage filter]
Next, the multistage filter disposed in the main body 4 will be described. In the following description, for convenience of explanation, the third order filter 30, the second order filter 20, the first order filter 10, and the fourth order filter 40 will be described in this order.

(3rd order filter (main filter))
The tertiary filter 30 is a main filter for capturing dust such as oil smoke and oil droplets, and has various characteristics.
In other words, at present, the general principle and form for capturing ultrafine particles is a form utilizing fine fibers that depend on the “diffusion adsorption” principle in which Brownian motion and intermolecular attractive force are dominant, and is around 0.4 μm. There are known HEPA filters, ULPA filters, and the like obtained by forming a micro glass wool in a felt shape.

"General ULPA filter specifications"
Fiber: Micro glass wool having a diameter of about 0.4 μm Sheet molding: Adhesion with binder Per unit weight: 100 g / m ²
1 cell area: 17m ²
Treatment air volume: 34m ³ / min
Ventilation speed: 2m / min
Capturing (collecting) performance: 0.1 μm × 99.99%

However, this conventional filter has a problem that it is quickly unusable as described above.
That is, the interfiber distance (gap) of the filter is usually proportional to the fiber diameter. In addition, an oil film sticks to the constituent fibers of the filter (adhesion of oil components), and when this oil film grows or other dust such as diesel carbon adheres to this oil film, the filter gap is clogged, Increases ventilation resistance. Therefore, the conventional filter using fine fibers having a diameter of about 0.4 μm has a problem that the gap is narrow, and the gap is quickly clogged, so that it cannot be used quickly. In addition, since the conventional filter is formed by forming fine fibers with a binder, the gap is further narrowed, and it becomes even faster to be unusable. Furthermore, since the conventional filter has a low molding strength due to the use of fine fibers, it is not suitable for cleaning or the like and is a consumable product, which increases running costs.

  Therefore, the present inventor has made various studies in order to solve these problems, and as a result, a filter using thick fibers of 2 to 20 μm, preferably 5 to 10 μm, more preferably 6 μm, A form that can be captured has been developed.

  Conventionally, it has been considered that it is impossible to capture such ultrafine particles of about 0.05 μm using such thick fibers depending on the diffusion adsorption principle. However, if the thick fiber is a synthetic fiber and is formed by thermocompression bonding, and the ventilation rate is 0.1 to 0.2 m / min, preferably 0.1 to 0.15 m / min, the thick fiber is thicker than 5 μm. Even if fibers are used, ultrafine particles can be captured.

  First, as described above, since the filter gap is roughly proportional to the fiber diameter, the filter gap using thick fibers is wide. The gap remains wide. And if the filter gap remains wide, ultrafine particles cannot be captured depending on the principle of diffusion adsorption, but since the oil film sticks to the thick fiber, the thick fiber is in a so-called thick state due to the sticking of the oil film. In practice, the gap becomes narrower. Therefore, ultrafine particles can be captured depending on the diffusion adsorption principle (however, if the aeration rate is too high, the capture depending on the diffusion adsorption principle is not performed). In addition, dust such as oil smoke and oil droplets adheres to the fiber and aggregates and re-liquefies and flows down (self-cleaning performance), so that the fiber does not become fat until the gap is clogged. This is different from the conventional filter using fine fibers in which the gap is clogged before the dust re-liquefies and flows. That is, according to the filter using the thick fibers of this embodiment, a gap suitable for capturing ultrafine particles is constantly maintained, and a maintenance-free filter that can be used continuously for a long period of time is obtained. In addition, since the filter uses strong and thick fibers, the molding strength is strong, maintenance such as cleaning is possible, and there is no need to use consumables.

  The inventor conducted a test using a filter having the following specifications. As a result, this filter has a diffusion adsorption equivalent to that of a general ULPA filter, although the fiber thickness is about 14 times that of a general ULPA filter (the ventilation rate is about 1/14 times). It turns out that an effect is acquired.

"specification"
Fiber: Polyester long fiber with a diameter of around 6 μm Sheet molding: Thermocompression bonding Weight per unit: 260 g / m ²
1 cell area: 105m ²
Treatment air volume: 15m ³ / min
Ventilation speed: 0.14 m / min

  The tertiary filter (main filter) 30 of the present embodiment adopts the filter using the thick fibers as described above, has the advantages described above, and is extremely excellent in running cost.

  As a raw material of the fiber used for the tertiary filter 30, a synthetic fiber that does not require adhesive molding with a binder and enables molding by thermocompression bonding is used. The synthetic fiber is not particularly limited as long as thermocompression bonding is possible. For example, nylon, vinylon, polyester, acrylic, polyolefin, polyurethane, or the like can be used.

  In the tertiary filter 30 of this embodiment, the air volume of the ventilation means 3 and the size of the main body 4 can be adjusted in order to slow down the ventilation speed, but in order to slow down the ventilation speed while ensuring the air volume. It is preferable to increase the filter area. Therefore, in the present embodiment, as shown in FIGS. 3A and 3B, the tertiary filter 30 is replaced with a sheet 31 having a concavo-convex emboss 31c (a filter using the thick fibers of the present embodiment). A pleat is folded, and this pleat folding is repeated to form a cylindrical shape. In the example illustrated in FIG. 3, a mountain fold type pleat fold (mountain pleat fold) 31 a and a valley fold type pleat fold (valley pleat fold) 31 b are sequentially repeated to form a cylindrical shape.

When the pleat folds 31a, 31b,... Are repeated in this way, the filter area is increased. However, if fine fibers are used as in the conventional filter, the strength of the filter 30 (sheet 31) is weak, so it is necessary to interpose a separator for securing and maintaining this gap between adjacent pleats 30X. is there. When the separator is interposed in this manner, the interval between the adjacent pleats 30X is widened. Therefore, in the case of a cylindrical shape, the number of pleat folds 31a, 31b... (The number of pleats) is reduced and the filter area is sufficient. (Or the filter 30 needs to be enlarged). However, the tertiary filter 30 (sheet 31) of this embodiment is strong because thick fibers are used, and the minimum spacing between adjacent pleats 30X is secured and maintained by the uneven emboss 31c. Therefore, a separator is not necessary. As a result, even in the case of a cylindrical shape, it is not necessary to reduce the number of pleat folds 31a, 31b..., And the area of the tertiary filter 30 (sheet 31) can be made sufficiently wide.
Note that the fold 30X means a portion of the sheet 31 sandwiched between adjacent pleat folds 31a and 31b.

  In the present embodiment, the form of the pleat folds 31a and 31b is not particularly limited. For example, as shown in FIG. 3A, it can be folded back at an almost acute angle, or as shown in FIG.

  Further, the width of the fold 30X (the distance between the pleat folds 31a and 31b adjacent to each other) is not particularly limited. For example, it can be considered that individual pleats 30X have different widths.

  However, the inner diameter (distance from the center of the cylinder to the valley pleat fold 31b × 2) L1 is 200 to 300 mm, preferably 250 mm, and the outer diameter of the tertiary filter 30 (the center of the cylinder). 2) L2 is 400 to 600 mm, preferably 550 mm, and distance L3 between the adjacent pleat folds 31a and 31a (pleat pitch; see FIG. 3 (b)). Is 3.5 to 7.0 mm, preferably 4.0 mm, the cylindrical tertiary filter 30 has sufficient strength and exhibits sufficient capture performance.

In addition, the size and protrusion length of the uneven emboss 31c are not particularly limited. However, when the distance (pleat pitch) L3 between the pleat folds 31a and 31a is set to 3.5 to 4.0 mm as described above, the size (area) of the uneven emboss 31c is 4 to 8 mm ² , preferably 4-5 mm ² and a protrusion length of 1.5-3.0 mm, preferably 1.5-2.0 mm, are preferable in that the interval between adjacent pleats 30X can be reliably secured and maintained. It is.

  In this embodiment, the method for forming the concave / convex emboss 31c is not particularly limited, and can be a known method, for example, a method in which the sheet 31 is formed between a pair of concave / convex embossing rolls having concaves and convexes that fit together. Can do.

For example, when the outer diameter L2 is 550 mm, the inner diameter L1 is 250 mm (the width of the fold 30X is 150 mm), the pleat pitch L3 is 4 mm, and the height in the vertical direction of the filter 31 is 2000 mm, the mountain pleat fold 31a is “550π / 4 = 432 (mountain)”, and the area per one third-order filter 30 is 432 (mountain) × 0.15 m × 2 × 2 m≈259 m ² .

  In this embodiment, the cylindrical tertiary filter 30 is arranged such that a line (pleated fold line) formed by the pleat folds 31a and 31b extends vertically. In this arrangement, when dust such as oil smoke or oil droplets aggregates and reliquefies, it flows down due to gravity. Therefore, a drain pan or the like (not shown) is arranged at the bottom of the main body 4, and the oil drain collected in the drain pan or the like is discharged by using a pump or the like, for example, from the oil outlet 8 as shown in FIG. Can be provided. The oil drain can be easily discharged because the main body 4 has a positive pressure as described above. Further, in the present embodiment, the strength of the sheet 31 itself is strong and bending or the like is difficult to occur, so that the re-liquefied oil drain smoothly flows downward. As a result, there is no fear that the fibers are partially overweight, and the capturing performance is evenly exhibited as the entire tertiary filter 30.

  Furthermore, in this embodiment, in addition to the strength of the sheet 31 itself, the strength of the tertiary filter 30 as a whole can be increased by increasing the number of folds of the pleats, and further, the ventilation rate is extremely high. Since the pressure applied to the sheet 31 is reduced by being set late, it is not necessary to provide an aggregate made of a punch plate or the like inscribed in the cylinder (in contact with the valley pleat fold 31b), thereby reducing the equipment cost. can do.

  By the way, in this embodiment, as shown in FIGS. 1 and 2, the main body 4 is formed by a rectangular parallelepiped front step portion 4A and a rear step portion 4B taller than the front end portion 4A. The air A blown into 4A flows toward the rear stage 4B. A plurality of tertiary filters 30 are arranged in the rear stage portion 4B, twelve in the illustrated example. Specifically, a plurality of tertiary filters 30 are arranged in the distribution direction (direction from the front stage portion 4A toward the rear stage portion 4B). Are arranged in such a manner that four are arranged in the width direction (a direction orthogonal to the distribution direction), and three are arranged in the illustrated example.

  When a plurality of the tertiary filters 30 are arranged in this way, if the ventilation speed of the air A is about 2 m / min as in the prior art, the ventilation is concentrated only on the tertiary filter 30 on the front stage 4A side. There is a risk of being done. However, in this embodiment, since the ventilation speed is set to be extremely slow, 0.1 to 0.2 m / min, there is no possibility of causing a large difference in ventilation speed locally in the rectangular parallelepiped rear stage portion 4B. Therefore, even when the tertiary filters 30 are arranged side by side in the flow direction and the width direction, there is no possibility that the air A will intensively hit only the tertiary filter 30 on the front stage 4A side, and (a) in FIG. As shown in FIG. 5, since the air A hits each tertiary filter 30 evenly from four directions, the trapping efficiency is extremely excellent.

(Secondary filter (pre-filter))
Next, the secondary filter 20 will be described.
The secondary filter 20 of this embodiment is a cylindrical filter that circumscribes each tertiary filter (main filter) 30 as shown in FIG. In the secondary filter 20, for example, dust having a relatively large particle diameter of 10 to 20 μm is captured prior to the capture by the tertiary filter 30, so that the tertiary filter 30 is prevented from being clogged.

  In this secondary filter 20, the principle of capturing dust is not particularly limited, and for example, the diffusion adsorption principle can be used. However, it is preferable to capture the dust with the large particle diameter using the diffusion adsorption principle. According to this embodiment, the self-flushing property is ensured.

  As the secondary filter 20, a known filter can be used, for example, a urethane filter, a metal filter, a chemical fiber, a natural fiber, or the like can be used, and it is composed of glass wool or polyester fiber. A filtered filter can also be used.

  The thickness M of the secondary filter 20 (see FIG. 3B) is not particularly limited, and is usually 10 to 30 mm, preferably 15 mm. However, if the secondary filter 20 has such a thickness, there is a risk of bending. However, in the present embodiment, the secondary filter 20 is arranged so as to circumscribe the strong cylindrical tertiary filter 30 and the shape is maintained by the tertiary filter 30, so the aggregate is used using an aggregate or the like. There is no need to prevent deflection.

(Primary filter)
Next, the primary filter 10 will be described.
The air A blown from the blowing port 4X formed in the peripheral wall of the front stage part 4A first passes through the primary filter 10 arranged in the front stage part 4A. In the primary filter 10, for example, large dust of 10 to 1000 μm, such as fibrous suspended dust, is captured.

  As the primary filter 10, a known metal filter formed of a metal such as stainless steel, nickel, copper, aluminum or the like in a net shape or a porous shape can be used. By using a metal filter as the primary filter 10, the primary filter 10 itself is prevented from igniting, and high temperature dust such as sparks is captured by the primary filter so that the secondary filter 20 or The ignition of the tertiary filter 30 is prevented.

  The primary filter 10 is provided so as to block the flow of air A in the front stage portion 4A. For example, the primary filter 10 extends from the lower end (floor surface) to the upper end (top surface) of the front stage portion 4A and in the width direction (flow direction). (Orthogonal direction) It can be composed of a single metal filter over the entire length. However, in the present embodiment in which a plurality of secondary filters 20 and tertiary filters 30 are arranged in a direction (width direction) orthogonal to the air A flow direction, the following form is recommended.

  That is, as shown in FIG. 1, a plate-like metal filter is continued in the width direction (orthogonal direction) on the front stage side of the plurality of secondary filters 20 and the tertiary filter 30 in this embodiment, in the front stage portion 4A. As shown in the figure, four in the illustrated example are arranged, and the plurality of metal filters 11, 12, 13, and 14 are not parallel to the width direction and are adjacent to each other, in this embodiment, the metal filter 11 And the metal filter 12, the metal filter 12 and the metal filter 13, and the metal filter 13 and the metal filter 14 are arranged so as not to face the same direction.

  In this respect, the overall flow direction of the air A blown from the blowing port 4X is a direction from the primary filter 10 toward the secondary filter 20 or the tertiary filter 30 (direction shown as “flow direction” in FIG. 1). However, the flow direction of the air A when passing through the primary filters 11, 12, 13, and 14 is a direction orthogonal to the primary filters 11, 12, 13, and 14 that pass through (primary filters 11, 12). , 13, 14 in which the filter surfaces face). Therefore, when the arrangement directions of the primary filters 11, 12, 13, and 14 are limited as in the present embodiment, for example, high-temperature dust that has passed through the primary filters 11 and 14 located on both side ends of the front filters 4A Since it goes to the peripheral wall and collides with the peripheral wall and falls, it goes to the subsequent filter such as the secondary filter 20 and the tertiary filter 30 and is not captured by the subsequent filter, and the risk of ignition is further reduced. . Further, the high temperature dust that has passed through the primary filters 12 and 13 located in the center also goes to the filter 12 or 13 or the distance to the subsequent filter, so the risk of ignition is further reduced.

  The degree of orientation of the primary filters 11, 12, 13, and 14 (how much the angle with respect to the orthogonal direction is determined) depends on the distance from the tertiary filter 30, the air velocity of the air A, and the primary filter. It can be determined as appropriate based on the width of 11, 12, 13, 14 and the like.

(4th order filter (check filter))
Next, the quaternary filter 40 will be described.
In the dust collector 1 of this embodiment, the 4th order filter 40 is arrange | positioned above each 3rd order filter 30, The air A which passed the order of the 1st filter 10, the 2nd filter 20, and the 3rd filter 30 is as follows. Finally, it passes through the fourth order filter 40.

  The quaternary filter 40 mainly functions, for example, when it operates for the first time after the dust collector 1 is introduced, or when the tertiary filter 30 is washed or replaced. In these cases, oil film is not attached to the constituent fibers of the tertiary filter 30 (so-called wet state) and the distance between the fibers is wide, so that dust such as oil smoke and oil droplets is removed from the tertiary filter. 30 may pass. Therefore, the fourth filter 40 collects dust at this stage.

  Since this quaternary filter 40 hardly captures dust such as oil smoke or oil droplets after the tertiary filter 30 gets wet, the reduction of the capture efficiency of the quaternary filter 40 is not a big problem. An expensive filter such as a ULPA filter can be used.

  In this embodiment, the fourth-order filters 40 are provided so as to correspond to the respective third-order filters 30, and twelve are provided in the illustrated example. However, the present invention is not limited to this form. For example, the air that has passed through the respective third-order filters 30 is collected and processed by a smaller number of fourth-order filters 40 than the first, second, etc. third-order filters 30. You can also

  In the present embodiment, the fourth-order filter 40 is disposed at the upper end of the rear stage 4B, and the rear stage 4B is made higher than the front stage 4A for this arrangement. However, the present invention is not limited to this form. For example, the quaternary filter 40 is disposed outside the rear end 4B, and the air A that has passed through the tertiary filter 30 is guided to the quaternary filter 40 through an appropriate pipe or the like. A form or the like can also be adopted.

  However, when all the filters 10, 20, 30, 40 are arranged in the main body 4 composed of the front stage part 4A and the rear stage part 4B integrated as in the present embodiment, the four stages of filters 10, 20, 30, 40 are arranged. Since the sound absorption effect by is most effectively exhibited, the noise prevention performance of the ventilation means 3 is excellent.

[Others]
As described above, the air A that passes through each of the filters 10, 20, 30, and 40 in order and is discharged from the air outlet 4Y is refreshed to be highly purified air, and thus, for example, is recirculated in a factory or the like. Can do. And if it recirculates in this way, an air-conditioning energy loss will decrease and a significant energy saving will be achieved.

  Further, by capturing dust with the four-stage filters 10, 20, 30, and 40 as described above, the ventilation load is reduced, and for example, the pressure loss can be reduced to 1 kPa or less. The power cost can be reduced.

  Furthermore, according to the dust collector 1 of this form, since it becomes a simple structure only with the ventilation means 3 and the filters 10, 20, 30, and 40, it is excellent also in operability.

  In this embodiment, the multistage filter has four stages, but it can also have more stages.

Next, examples of the present invention will be described.
First, a test was conducted to clarify that ultrafine particles can be captured by controlling the ventilation rate (air permeability) even with a filter using thick fibers.

(Test method)
First, lubricating oil (turbine oil # 32) was dropped on a hot plate heated to 300 to 400 ° C. to generate a large amount of oil smoke (white smoke). Then, the air containing the oily smoke was sucked from the suction hood and aerated through a test filter having the following specifications. This aeration was performed using a suction blower, and as shown in Table 1, the speed was changed every predetermined time. The test filter was once immersed in lubricating oil and used after 1 hour.

"Design specification"
Fiber: Polyester long fiber with a diameter of around 6 μm Sheet molding: Thermocompression bonding Weight per unit: 260 g / m ²
Area: 18m ²

  For the air that passed through the test filter and was discharged from the suction blower, the remaining white smoke was evaluated as the capture performance. The results are shown in Table 1.

  As shown in Table 1, white smoke remained when the ventilation speed was 0.33 m / min, but the white smoke disappeared when the ventilation speed was 0.2 m / min and 0.14 m / min. This shows that even a filter using thick fibers can capture 0.05 μm-class ultrafine particles by controlling the ventilation rate (air permeability).

  Next, a test was conducted to clarify that the self-cleaning performance was exhibited by the filter using thick fibers.

(Test method)
Carbon oil (slurry) containing 80% graphite powder is sprayed on the surface of the test filter with the specifications shown below, and a suction blower (Fuji Electric blower VFC084P, air volume MAX0.35 m ³ / min) was used to conduct air.

"Design specification"
Fiber: Polyester long fiber with a diameter of around 6 μm Sheet molding: Thermocompression bonding Weight per unit: 260 g / m ²
Area: 0.25m ²

As shown in Table 2, the carbon oil was sprayed for 10 minutes, and then the blower was simply turned (interval) for 30 minutes without spraying. This spraying / interval was repeated three times in succession.
In addition, since the differential pressure changes depending on the degree of clogging of graphite powder, a self-cleaning performance is evaluated by attaching a differential pressure gauge to the exhaust side of the test filter and measuring the change in differential pressure with this differential pressure gauge. I made it. The test filter was pre-coated with lubricating oil (turbine oil # 32) and used after 1 hour. In addition, the air volume in Table 2 is the air volume on the blower exhaust side (diameter 25 mm).

  INDUSTRIAL APPLICABILITY The present invention can be applied as a dust collecting device that collects dust such as oil smoke and oil droplets generated in rolling, drawing, cutting and the like.

  3 ... Ventilation means, 4 ... Main body, 4A ... Front stage part, 4B ... Rear stage part, 4X ... Blowing inlet, 4Y ... Air vent, 5 ... Fire damper, 5A ... Hinge, 8 ... Oil outlet, 10 ... Primary filter 20 ... secondary filter, 30 ... tertiary filter, 31 ... sheet, 31a, 31b ... pleated fold, 31c ... uneven embossing, 40 ... quaternary filter, A ... air.

Claims (4)

A dust collecting device provided with a filter for capturing dust contained in air,
As at least one of the filters, a main filter formed by thermocompression bonding of synthetic fibers having a diameter of 2 to 20 μm is provided.
The ventilation rate of the air passing through the main filter is configured to be 0.1 to 0.2 m / min.
A dust collecting device characterized by that. The main filter is
A sheet having uneven embossing is pleated, and this pleat folding is repeated to form a cylindrical shape.
And it is arranged so that the pleat fold line extends vertically,
The dust collecting apparatus according to claim 1. A cylindrical pre-filter that circumscribes the main filter is provided,
The dust collecting apparatus according to claim 2. A plurality of the main filters are arranged in a direction orthogonal to at least the air flow direction,
On the front side of the plurality of main filters, a plurality of flat metal filters are arranged so as to be continuous in the orthogonal direction,
The plurality of metal filters are all arranged so that they are not parallel to the orthogonal direction and the metal filters adjacent to each other do not face the same direction.
The dust collecting apparatus according to claim 2 or 3.

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