JP5192933B2 - Conductive bag filter for granulator dryer - Google Patents

Description

  The present invention relates to a conductive bag filter used for powder filtration, and more particularly to a conductive bag filter used for a granulation dryer, and more specifically, from a sewing machine stitching portion of a bag filter that is safe and free from powder explosion. The present invention relates to a bag filter with less leakage of powder particles.

  A granulation dryer is used as one of granulating means such as seasonings, granular foods such as sprinkles, tableting granules for pharmaceuticals, and granular detergents. In a granulator / dryer generally used, an arbitrary granule is introduced into the granulator / dryer, and the granule is convected by warm air from below the granule layer in the granulator / dryer. The binder liquid is sprayed on the granular material convected from the side wall or the upper part of the glass, and granulated or coated with the granulated material while being dried. The warm air is introduced from the lower part of the granulation dryer, filtered through a bag filter provided at the upper part of the granulation dryer, and then released into the atmosphere through an exhaust port. In addition, as described in Patent Document 1 described later, a method has been proposed in which powder particles attached to the filter are removed by extending or contracting the bag filter with an external force such as an air cylinder so that the bag filter is not clogged. .

  As the bag filter, a conductive fiber made of a non-conductive synthetic resin fiber woven fabric coated with a conductive wire such as a stainless steel wire, a synthetic fiber coated with a metal such as silver or nickel, carbon, etc. A technique is also known in which conductive properties are imparted to a fabric made of synthetic resin by arranging in a lattice shape, and electrostatic charges generated and accumulated when filtering fine powder particles in exhaust gas are filtered out to the outside. .

  In addition, as a shape of the bag filter, a filter in which a plurality of filter portions are arranged to increase the surface area of the filter as in Patent Document 3 described later has been proposed. The following patent documents were found as prior art documents.

  For example, in Patent Document 1, even when the maximum allowable charge amount is 15 kg or less and the charged particle layer height of the granular material is increased within a predetermined range, the flow state of the granular material by hot air or There has been proposed a fluidized bed granulator capable of balancing the dry state and the state of moisture accumulation in the granular material by spraying liquid. In paragraph [0013], a bag filter is built in the filter casing at the upper part of the granulation container, and an air cylinder or other actuator installed at the upper part of the casing is connected to each bag filter, and the actuator is used as necessary. Thus, the bag filter is configured to vibrate in the vertical direction. An exhaust port is provided in the upper part of the filter casing, and an exhaust duct extending in the vertical direction communicates with the exhaust port. The exhaust duct communicates with an exhaust pipe in which an exhaust filter is installed on the way. Is described. Also, in paragraph [0017], during operation, warm air passes through the granulation vessel, is introduced into the upper filter casing, is filtered by a bag filter inside, and has an exhaust port, an exhaust duct, and an exhaust filter by a blower. It is released into the atmosphere via the exhaust pipe. Furthermore, there is a description that when the filtration capacity of the bag filter is lowered, the upper air cylinder is operated to remove them.

  Further, in Patent Document 2, in a powder processing apparatus provided with a bag filter for capturing powder particles in a gas, the bag filter includes a filter base material made of woven cloth, and the filter base material is There has been proposed a powder processing apparatus having an antistatic means, wherein the antistatic means is a conductive fiber in which a silver coating is formed on a synthetic resin fiber.

Further, in Patent Document 3, a cotton-like conductive belt is arranged between non-conductive belts made of a large number of cotton-like fibers, and both cotton-like belts are used to form a conductive mesh substrate as a core material. A bag filter characterized by being formed into a cylindrical shape with a filter cloth slid onto both front and back surfaces has been proposed. FIG. 1 shows a plurality of cylindrical bag filters.

JP 2002-361666 (Abstract, [0013], [0017]) JP 2003-1089 (Claim 1, Summary) In fact, Sho 52-035679 (Claim 1, Fig. 1)

  It is an object of the present invention to provide a conductive filter cloth used in a granulation dryer that hardly causes powder particles to leak out of a bag filter from a sewing processing section and does not cause powder explosion due to static electricity or the like. Objective.

  A bag filter is constructed by stitching together a filter cloth (hereinafter referred to as a conductive filter cloth) made of a synthetic resin in which conductive fibers (conductive threads) as shown in Patent Document 2 are arranged on a non-conductive filter base material. In this case, the conductive yarns arranged in a lattice shape are reliably brought into contact with each other on the stitching surfaces of the conductive filter cloths, and the electrostatic charge generated by the contact between the powder particles or the contact between the bag filter and the powder particles is generated. It is necessary to secure a path through which electrons can freely move to the outside so that they can escape to the outside without fail. In this case, as shown in FIG. 2 of the present specification, at least one of the sutures used for suturing at the stitching site is used as a conductive yarn, so that the conductive yarn arranged in a lattice shape is reliably conducted. However, when sewing a bag filter having a complicated three-dimensional shape by stitching a plurality of conductive filter cloths, naturally the conductive thread wears due to external forces such as friction and stress because the number of stitches increases. Since the cut stitches are likely to occur, contact between the conductive yarns becomes insufficient, and there is a possibility that powder explosion may occur due to accumulation of electrostatic charges and instantaneous discharge to the air.

  For this reason, if the shape of the bag filter is simplified and the number of stitches is minimized to avoid the accumulation of static electricity, or if a octopus-like complicated shape as shown in FIGS. In preparation for the case of cutting due to wear or the like, the stitched portions of the filter cloths are bridged with conductive yarns, so that the filter cloths to be stitched need to be supplementarily conducted. In this case, although a conduction path for releasing the electrostatic charge accumulated by bridging with the conductive yarn is secured to the outside, there is a problem that fine powder particles may leak from the seam by bridging with the conductive yarn. there were. In order to prevent clogging of the filter, in particular, when the powder filter is wiped off by expanding and contracting the foot of the bag filter by an external force such as an air cylinder, the seam opens by applying stress to the foot, and from there It was the cause that the internal granular material leaked out. The leaked powder particles are undesirable because they adhere to the granulator and cause malfunctions, or the powder particles may scatter in the factory and force employees to wear dust masks. It was.

  The present invention relates to a bag filter having conductivity used in a granulation dryer, and the stitched portion is formed by superposing conductive filter cloths constituting each portion and stitching them with a conductive thread, and then winding the stitched portion. The conductive bag filter for a granulating dryer solves the above-mentioned problem by being formed by folding back clockwise or counterclockwise to hide the stitched portion and sewing both sides of the hidden conductive thread. . That is, a filter substrate made of a woven fabric of synthetic resin fibers such as nylon and polyester is coated with a conductive wire such as stainless steel wire or a synthetic fiber such as nylon, polyester or glass fiber with a metal such as silver or nickel or carbon. In a bag filter that is sewn using a conductive filter cloth in which conductive fibers (hereinafter referred to as conductive yarns) are arranged on a filter base material, the conductive thread is sewed by folding back the stitched portion as described above. By concealing the inside, the conductive yarn of the stitched portion is protected from friction and stress generated when the bag filter is expanded and contracted by an external force such as an air cylinder to clean the filter. As a result, there is no possibility that the conductive yarn in the stitched portion will be cut due to wear. The conductive yarn is electrically conducted, and accumulation of electrostatic charges in the bag filter can be prevented. Furthermore, by forming the stitched portion in the above-described manner, the durability of the stitched portion is improved and the filter cloth has a structure in which the stitched portion overlaps, so that the powder particles from the inside of the bag filter Can prevent body leakage. Here, the conductive yarns arranged on the filter base material may be arranged in any pattern as long as the conductive yarns are not parallel to each other at the stitched portion and can be in contact with each other. It is preferable because conduction paths are formed in the vertical and horizontal directions.

  The shape of the conductive bag filter may be any shape. For example, a plurality of filter parts including a ceiling part and a cylindrical foot part, and a semicircular shape in front view to which the filter part is attached The device mounting base part and the skirt part attached to the lower part of the base part may be sewn together by a stitched portion. Since the surface area of the filter portion can be increased by providing the plurality of filter portions in a so-called octopus shape, the efficiency of powder filtration can be increased. However, with such an octopus foot structure, the number of stitched parts increases, and there is a high possibility that the conduction path will be interrupted. Conventionally, as shown in Fig. 1, each filter part is bridged by a bridge to ensure the conduction path. However, by applying the present invention, the bridge can be omitted as described above, so that the leakage of powder particles from the bridge seam, which is the biggest problem of this bridge, can be solved. it can.

Furthermore, the cylindrical foot and the cylindrical skirt are each formed into a cylindrical shape by overlapping both ends of one conductive filter cloth to form a cylindrical shape, and then welding the overlapped portions. Can be formed. Joining the conductive filter cloth by welding is preferable because the possibility of the powder particles leaking from the joint can be minimized. In addition, when the filter cloths are joined together by stitching, some thickness is generated in the stitched part, so it is easy for the granules to enter the gap between the stitched parts. Although it was difficult to remove and the particulate matter that could not be removed caused contamination (contamination by different types of residual particulate matter), which was a cause of harm to the quality of the product. It is possible to prevent fear. For the welding, methods such as thermal welding by blowing hot air to the welded portion, thermal welding with a thermal iron, ultrasonic welding using an ultrasonic sewing machine or the like are used.

In addition, if cleaning of the upper suture part, which is subject to stress, is necessary during cleaning with an air cylinder, after the ceiling part of the bag filter and the cylindrical foot part are stitched, external force is directly applied to the stitched part. The filter part may be reinforced by covering with a patch and sewing both sides of the suture thread of the stitching part together with the patch so as not to be added. In addition to attaching the patch, a hook used for suspending the bag filter on the granulation dryer may be attached.

  It is possible to provide a conductive filter cloth used in a granulation dryer that hardly causes powder particles to leak out of the bag filter from the sewing processing section and does not cause powder explosion due to static electricity or the like.

  Even when a bag filter having a complicated shape is desired, if the present invention is applied, there is no need to provide a bridge, so that the possibility of the powder particles leaking out from the seam of the bridge can be eliminated.

  By sewing each stitched part of the bag filter for the granulator dryer, the filter cloths are stacked in multiple layers and machined, so that the stress applied to the filter cloth during dust collection and removal is reduced. It is possible to provide a filter cloth in which there is no opening of the sewing machine stitch portion and no leakage of the granular material.

When the cylindrical foot portion and the cylindrical skirt portion are processed into a cylindrical shape, a bag filter free from the risk of contamination can be easily manufactured by processing by a thermal welding method instead of stitching.

  Hereinafter, examples of the present invention will be specifically described in comparison with conventional bag filters. FIG. 1 is a diagram schematically showing a conduction path of a conventional bag filter having a plurality of filter portions. FIG. 2 is a diagram schematically showing a cross section of a conventional bag filter. FIG. 3 is a view schematically showing a cross section of the suture processing portion of the present invention. FIG. 4 is a view schematically showing a cross section of a bag filter to which the present invention is applied. FIG. 5 is a diagram schematically showing a cross section of the foot portion and the skirt portion according to the present invention. FIG. 6 is a view showing an extra filter cloth at a welded portion by a conventional welding method.

  In the conventional bag filter 1, first, the filter cloth of the filter portion 11 and the filter cloth of the base portion 14 are overlapped and stitched with the first conductive thread 21, and then the filter cloth is quadrupled at the stitched portion as shown in FIG. 2. The filter cloths were folded back so that the outer ends of the conductive yarns were finally stitched with two needle stitches 22. The skirt portion 15 and the base portion 14 are also sewn in the same manner, and the first conductive yarn 21 and the second conductive yarn 23 are exposed to the outside of the bag filter 1 at any stitched portion. Further, the first conductive yarn 21 and the second conductive yarn 23 in FIG. 2 correspond to the first conduction path 24 and the second conduction path 25 in FIG. 1, respectively, and the filter portion 11, the base portion 31, the base portion 31, and the like. In order to ensure sufficient electrical conduction between the skirt portions 15, the first conduction path 24 and the second conduction path 25 are connected by the bridge 20. As described above, the bridge 20 causes leakage of the granular material.

  On the other hand, in the bag filter 3 for the granulation dryer of the present invention, first, as shown in FIG. 4, the filter cloth of the filter portion 32 and the filter cloth of the base portion 31 are overlapped and stitched with the first conductive yarn 34, It is formed by folding the stitched portion counterclockwise so as to hide the stitched portion and sewing the hidden first conductive thread 34 on both sides with the stitching thread 37. That is, as shown in FIG. 3, when the two filter cloths to be stitched together are the first filter cloth 35 and the second filter cloth 36 for convenience, the first filter cloth 35 and the second filter cloth 36 are first overlapped. The first filter cloth 35 and the second filter cloth 36 are stitched together with the first conductive thread 34. Next, the conductive thread 34 obtained by stitching the first filter cloth 35 and the second filter cloth 36 is turned clockwise or counterclockwise around the center of rotation to hide the stitched portion, and the first conductive thread 34 is covered with the suture thread 37. Are sewn together to form a stitched portion 33. If the filter cloth is stitched by the method of the present invention, the first conductive thread 34 is not exposed to the outside of the filter and is not worn out, so the conventional bridge 20 (FIG. 1) serving as an auxiliary conduction path is omitted. Can do. It should be noted that any one of the first filter cloth 35 and the second filter cloth 36 may be overlaid. In addition, a conductive thread may be used as the suture thread 37, but it is preferable to use a durable thread such as nylon or polyester from the viewpoint of cost cut.

  The shape of the bag filter to which the present invention is applied can be any shape such as a rectangular parallelepiped, a sphere, a cylinder, a cone, etc., and includes, for example, a ceiling portion 39 and a cylindrical foot portion 38 as shown in FIG. A plurality of filter parts 32, a device mounting base part 31 having a semicircular shape in front view to which the filter part 32 is attached, and a skirt part 40 attached to the lower part of the base part 31 are sewn together by a stitched portion. Particularly useful in the bag filter 3 for dryers. Of the stitched portions, a lower stitched portion 41 for stitching the skirt portion 40 and the base portion 31, a middle stitched portion 42 for stitching the base portion 31 and the foot portion 38, and an upper stitch for stitching the foot portion 38 and the ceiling portion 39. If the structure of the stitched portion 33 shown in FIG. 3 is adopted as the processed portion 43, there is no fear that the conduction path is broken in the middle even if the bag filter has a complicated shape as in this embodiment.

  Further, when it is desired to reinforce the upper stitched portion 43, first, the filter cloth of the foot portion 38 and the filter cloth of the ceiling portion 39 are sewn with the conductive yarn 44 as shown in FIG. The upper stitched portion 43 may be formed by covering the stitched portion with the covering cloth 45 whose both ends are folded and sewing the inner side of the conductive yarn 44 with the stitched suture 46. Here, when attaching the hook part 47 used when suspending a bag filter to a granulation dryer, before sewing the patch cloth 45, the hook part 47 is placed between the patch cloth 45 and the filter cloth of the ceiling part 39. It is good to sew it in between. Here, instead of the conductive thread 44, the filter cloth of the foot part 38 and the filter cloth of the ceiling part 39 may be sewn with a thread made of the same material as the suture thread 46.

  As shown in FIG. 4, any number of attachment cloths 49 provided in the skirt portion 40 with button receiving holes 48 are sewn to the end of the skirt portion, so that the bag filter 3 can be easily attached to a granulating dryer (not shown). This is preferable. The button receiving hole 48 is reinforced around the hole with a grid so that the attachment cloth 49 does not come loose. Further, if an O-ring 51 is interposed in a pocket portion 50 formed by folding the end of the skirt portion, when the bag filter is attached to the granulation dryer, the gap between the bag filter and the granulation dryer is It can prevent that a granular material leaks. After the end of the filter cloth of the skirt portion 40 is folded back once inside, first, the folded filter cloth is sewed with the suture thread 52 so that the folded filter cloth is doubled, and then both sides of the suture thread 52 are skirted. When it is sewn with the suture thread 53 and the suture thread 54 so as to be tripled together with the filter cloth of the section 40, it is possible to prevent the end of the filter cloth from being unraveled, and the granular material from the stitches. Can prevent leakage. When the attachment cloth 49 is attached to the skirt portion 40, the attachment cloth 49 is inserted into the pocket portion 50 before the pocket portion 50 is closed with the suture thread 53 and the suture thread 54, and the lower portion of the attachment cloth 49 is fixed with the suture thread 69. After that, the filter cloth is quadrupled with the suture thread 53 and the suture thread 54 (two ends of the skirt part 40 folded from the outside, one attachment cloth 49, and one skirt part 40). The pocket 50 is closed by sewing.

  In order to sew the foot portion 38 and the skirt portion 40 of the bag filter of the present invention into a cylindrical shape, as shown in FIG. 5, one end (first end portion 55) and the other end (second end) of the filter cloth are used. It is preferable to overlap the portion 56) and sew with the three needles 57 so that there is little leakage of powder from the stitched portion. Although not shown, the first end portion 55 and the second end portion 56 are overlapped by several centimeters from the end portion, and the overlapped portion is thermally welded using hot air, a thermal iron, etc. If ultrasonic welding is performed using a sewing machine or the like, the first end portion 55 and the second end portion 56 can be simply joined together. In addition, since no gap is formed at all, the powder is formed in the back of the stitched portion as in the past. It is preferable because there is no possibility that particles remain and contamination occurs. In addition, when joining an edge part by welding, the possibility of contamination is reduced further by making it not to produce the excess filter cloth 59 (FIG. 6) which remains without being welded on both sides of the welding part 58. FIG. be able to. Specifically, when using hot air, it is necessary to make the cloth overlap margin equal to or less than the hot air nozzle width so that it can be securely pressed to the edge of the cloth with a press roller. It is preferable to use a jig that adjusts the edge of the cloth so that the overlap of the cloth is equal to or less than the width of the thermal iron.

Hereinafter, the present invention will be described more specifically with reference to examples.

[Example 1]
By the bubble point method, the maximum pore diameter of the perforated line of the conductive filter cloth (without the bridge portion) was measured. The reagent was ethanol, and the temperature was measured at 25 ° C. The measurement results are as summarized in FIG.

[Comparative Example 1]
The maximum pore diameter was measured under the same conditions as in Example 2 except that a conductive filter cloth having a bridge portion was used as a sample for measurement of the maximum pore diameter of the perforation. The measurement results are as summarized in FIG.

[Example 2]
In order to evaluate the leakage of the granular material from the bridge portion applied to the conventional bag filter and the leakage of the granular material from the conductive filter cloth of the bag filter of the present invention, the powder shown in FIG. Granule leakage was measured. First, an upper mesh 62 and a lower mesh 63 are interposed in a filter holder 61 made using a pipe made of polyvinyl chloride as shown in the figure, and the cross section of the filter holder 61 is interposed between the upper mesh 62 and the lower mesh 63. The test filter cloth 64 cut according to the filtration area (19.6 cm ² , diameter 50 mm) is set. The set mesh plays the role of crushing the crushed powder. A glass fiber filter paper 65 and a flow meter 66 are connected to the downstream of the filter holder 61 via a pipe so that the vacuum pump 67 can perform suction while measuring the suction amount with the flow meter 66. The filter holder 61 is provided with two iron balls 68 for dropping off, and is used when dust particles remaining on the surface of the test filter cloth 64 are wiped off and cleaned. The granular material leaked without being filtered by the test filter cloth 64 is trapped in the glass fiber filter paper 65, and the amount of the leaked granular material can be calculated by measuring the weight of the glass fiber filter paper 65. Measurement conditions and operations are as follows.
<Measurement conditions>
1. Used granular material: JIS standard powder, 10 types of fly ash (particle size: 4.8 to 5.7 μm)
2. Test filter cloth: A conductive filter cloth in which conductive yarn is arranged on a polyester filter base material, cut into a circle having a diameter of 50 mm.
<Operation>
1. Suction for 10 minutes at a wind speed of 2 m / min to stabilize the moisture of the glass fiber filter paper.
2. Measure the weight of the glass fiber filter paper for leak measurement.
3. Place 2 g of fly ash on the upper mesh of the filter holder.
4). While sucking at a wind speed of 2 m / min, lightly tap the top to drop the dust onto the filter cloth.
After suctioning for 5.5 minutes, stop suctioning.
6). Measure the weight of the glass fiber filter paper.
7). Remove the upper mesh.
8). Turn the filter holder upside down and wipe off the dust on the test filter cloth with a scraping iron ball.
9. Repeat steps 3 to 8 three times.
The measurement results are as summarized in Table 1 and FIG.

[Comparative Example 2]
Measurement was performed under the same conditions as in Example 1 except that the following test filter cloth was used.
Test filter cloth: Conductive filter cloth in which conductive yarn is arranged on a polyester filter base, diameter 50
Cut into a circle of mm, and use a thread (20th count) similar to the conductive thread used for the bridge section, with 3 rows of sewing machines. The interval between each stitch is 1 cm. The total number of needle holes was 35.
The measurement results are as summarized in Table 1 and FIG.

  From the results of Example 1 and Comparative Example 1, it was suggested that the perforation of the bridge portion had a larger diameter than the perforation of the conductive yarn and caused leakage of the granular material. When the leakage of the granular material was actually measured according to Example 2 and Comparative Example 2, there was a leakage of the granular material in the conductive filter cloth having the bridge portion, but the granular material was in the conductive filter cloth having no bridge portion. It became clear that there was almost no leakage of the body.

  As described above, according to the present invention, it is possible to omit the bridge portion that has been essential in the prior art, and to provide a conductive filter cloth with excellent durability that is less likely to leak powder particles and is less likely to cause abrasion of the conductive yarn. Can be provided.

It is the figure which showed typically the conduction | electrical_connection path | route of the bag filter which has several conventional filter parts. It is the figure which showed the cross section of the conventional bag filter typically. It is the figure which showed typically the cross section of the stitching process part of this invention. It is the figure which showed typically the cross section of the bag filter to which this invention is applied. It is the figure which showed typically the suture cross section of the foot | leg part and skirt part of this invention. It is the figure which showed the excess filter cloth of the welding part by the conventional welding method. It is the photograph which showed the measurement result of the maximum diameter of the perforation of the electrically conductive yarn and bridge part which were measured by Example 1 and the comparative example 1 by the bubble point method. It is the figure which showed typically the apparatus for measuring the leakage of the granular material used in the Example. It is the graph which put together the result of having measured the leakage of the granular material of Example 2 and Comparative Example 2. FIG.

Explanation of symbols

1 Bag filter (conventional example)
DESCRIPTION OF SYMBOLS 11 Filter part 12 Ceiling part 13 Foot part 14 Base part 15 Skirt part 20 Bridge 21 1st electrically conductive thread 22 Two needle stitch 23 2nd electrically conductive thread 24 1st conduction | electrical_connection path 25 2nd conduction | electrical_connection path 3 Bag filter (this invention)
31 Base part 32 Filter part 33 Sewing part 34 First conductive thread 35 First filter cloth 36 Second filter cloth 37 Suture thread 38 Foot part 39 Ceiling part 40 Skirt part 41 Lower suture part 42 Middle suture part 43 Upper suture part Processed portion 44 Conductive thread 45 Batter 46 Suture 47 Hook portion 48 Button receiving hole 49 Attaching fabric 50 Pocket portion 51 O-ring 52 Suture 53 Suture 54 Suture 55 First end 56 Second end 57 Three needles 58 welding part 59 extra filter cloth 61 filter holder 62 upper mesh 63 lower mesh 64 test filter cloth 65 glass fiber filter paper 66 flow meter 67 vacuum pump 68 iron ball for dropping 69 suture thread

Claims (4)

In the bag filter having conductivity used in the granulation dryer, the stitched portion is overlapped with the conductive filter cloths constituting the respective portions and stitched with a conductive thread, and then the clockwise portion or the stitched portion is wound around the stitched portion. A conductive bag filter for a granulating dryer, wherein the conductive bag filter is formed by folding it in a counterclockwise direction to hide the stitched portion and sewing both sides of the hidden conductive yarn. The conductive bag filter has a plurality of filter parts including a ceiling part and a cylindrical foot part, a semicircular device mounting base part to which the filter part is attached, and a cylindrical shape attached to the lower part of the base part. The conductive bag filter for a granulator / dryer according to claim 1, wherein the skirt portion is sewn together by a stitched portion. The granulation according to claim 2, wherein the cylindrical foot portion and the cylindrical skirt portion are formed by overlapping both ends of one conductive filter cloth into a cylindrical shape, and then welding the overlapped portions. Conductive bag filter for dryer. 3. The sewing machine according to claim 2, wherein after the ceiling portion and the cylindrical foot portion are stitched together, a covering cloth is covered so that an external force is not directly applied to the stitching portion, and both sides of the suture thread of the stitching portion are sewn together with the covering cloth. Conductive bag filter for granulator dryer.