JP2003190720A - Bag filter and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bag filter satisfying heat resistance, dimensional stability, filterability, air permeability, repairing properties or the like required in a dust collector for dust-containing gas containing solid particles of an urban incinerator, an industrial waste incinerator or the like and having excellent economical efficiency inclusive of a manufacturing process. <P>SOLUTION: The length difference between the joined parts of the sewing surface of the bag filter formed by sewing a rectangular felt fabric integrated with a filter layer comprising a support layer (scrim) and staple fibers into a cylindrical shape is set to 1.0% or less. Further, the warp yarns of the scrim of the felt fabric and the sewing line of the bag filter are substantially parallel to the center line of the bag filter. Furthermore, the bag filter is not deformed even if thermally set at 240°C. Further, 30 wt.% of the felt fabric comprises a polyphenylene sulfide fiber. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bag filter used for a dust collector of dust-containing gas containing solid particles and a method for manufacturing the same, and more specifically, it is not susceptible to deformation of the bag filter when used for a long time. The filterability and air permeability are low, and the dust releasability is good.
Excellent resistance to condensation when using a bag filter,
Further, the present invention relates to a bag filter which is excellent in workability during filter manufacturing, has less loss of felt, and is excellent in cost performance and a manufacturing method thereof.

[0002]

2. Description of the Related Art Up to now, work for separating solid particles (dust) from a dust-containing gas containing solid particles has been carried out at various places. There are various types of dust collectors for this purpose, which are roughly classified into a power dust collector, an inertial dust collector, a centrifugal dust collector, a washing dust collector, a filtration dust collector, and an electric dust collector. The electric dust collector with specifications suitable for this has been often used especially in the municipal waste incinerator, the industrial waste incinerator and the like. With this specification, the dust collection efficiency is 30 at gas temperature.
Around 0 ° C is the best, but dioxins are generated (new synthesis) at this temperature, and the gas temperature at the entrance of the dust collector is obliged to be 200 ° C or less by the waste treatment method.
In order to control the gas temperature to 200 ° C. or lower, a method of spraying and cooling water is often adopted, and accordingly, the water content in the gas has increased. In this field as well, the filter dust collector has advantages such as high dust collection and filtration efficiency and that the dust collection efficiency is not significantly affected by temperature, and has recently become the mainstream. The technology of blowing powdered activated carbon into fly ash for dioxin adsorption is often used, but in this case, a filter dust collector is mostly used instead of an electric dust collector.

The heart of the filter dust collector is a bag filter, and its filter cloth is often made of fabric or felt. In addition, generally, with a bag filter type dust collector, the dust that has adhered to the bag filter is removed by using a mechanical vibration, reverse air flow method, or intermittent jet device with a pulse jet method, so that the filter can be used for a long period of time. Prolonged and high collection efficiency.

The felt in which short fibers are entangled by the 21 dollar punch method as such a filter cloth is excellent in dust collecting property and air permeability, and is further smoothed by calendering, scouring, braiding, etc. The dust releasability is also good, but short fiber felt alone has problems with mechanical properties such as tear strength and bending fatigue.Therefore, a felt made by entwining short fibers with a woven fabric with a relatively coarse weave called scrim is used. It is commonly used.

The characteristics required for this filter cloth are the type of exhaust gas, the temperature, the chemical properties, the moisture content, the amount, the dust collector,
Depending on the bag filter structure, shape, operating conditions, etc., the materials are inorganic metal fibers, glass fibers, carbon fibers, ceramic fibers, and natural materials.
It is appropriately selected from organic fibers including synthetic fibers. However, recently, many synthetic fibers have been used, which are excellent in mechanical properties, chemical properties, thermal properties, and easy to dispose of. As such synthetic fibers, for example, polyolefin fibers, polyacrylonitrile fibers, polyester fibers, polyamide fibers, etc. are generally used at low temperatures. Furthermore, polyphenylene sulfide fibers, polyimide fibers, aramid fibers, fluorine fibers and the like have also been widely used in order to improve heat resistance, chemical resistance and the like.

However, the bag filter used for incinerators of industrial wastes and municipal wastes is regulated to a temperature of 200 ° C. or lower as described above, but is exposed to such a high temperature for a long time. Therefore, the bag filter is heat set with a high temperature pinsetter so that the bag filter does not shrink or deform during use. The felt used for [bug filter] is quite thick, and it takes a lot of force to remove this felt from the pin with a setter. When such a large force is applied, a difference in tension occurs between the end in the felt width direction where tension is applied and the center part where no tension is applied, which results in density difference and strain difference, and the center and end parts in the width direction of the felt. In this case, the end portion becomes long and a difference in length occurs. This phenomenon is called flare in the industry. When the length of the bag filter cylinder is 2 m or more, it is cut so that the long side is taken in the length direction of the felt.
When sewing a bag filter by cutting felts with such differences in length and joining the long sides together, loosen the long sides little by little so that the bag has a regular cylindrical shape. Even so, there is a problem that the difference in length cannot be absorbed and the shape becomes a deformed cylindrical shape. Further, the problem can be avoided by cutting and sewing the abnormal portion so that the long sides have the same length, but a new problem occurs that the yield of the filter cloth decreases. On the other hand, even if the long side has the same length and is sewn after being shaped and cut, it retains a regular cylindrical shape in the initial stage if thermal stress strain remains in the felt, but heat treatment during use and dust removal Strains are gradually released and deformed by the dropping process, and there arises a problem that the maintainability at the time of dust removal and bag filter replacement is poor.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a heat resistance required for a bag filter which is continuously operated at a high temperature for a long time and filters exhaust gas such as an incinerator for such municipal waste and industrial waste. Dimensional stability (low heat shrinkage), filtration performance, dust release property, air permeability, etc. are satisfied at the same time, bending durability during dust removal operation is excellent, and workability during filter production is good. It is intended to provide a bag filter excellent in quality with less felt loss and excellent cost performance, and a manufacturing method thereof.

[0008]

The present invention has the following constitution in order to achieve such a goal. 1. In a bag filter formed by sewing a rectangular felt material, in which a scrim mainly made of synthetic fibers and short fibers are integrally molded, into a cylindrical shape, the bag filter is substantially a regular cylindrical shape, and the rectangular sewn long length is sewn. A bag filter characterized by a difference in length between sides of 1% or less. 2. A first bag filter characterized in that the difference in length between the long sides is 0.6% or less. 3. The bag filter according to the first or second aspect, wherein the warp of the scrim is substantially parallel to the center line of the cylinder of the bag filter, and the sewing joining line is substantially parallel to the center line of the cylinder. 4. The bag filter according to any one of 1 to 3, which is not substantially deformed by heat treatment at 240 ° C. 5. 1st to 4th, characterized in that 30% or more by weight of the felt is made of polyphenylene sulfide fiber
Bug filter described in any of. 6. The heat-setting temperature of the bag filter felt made mainly of synthetic fiber and short fiber is 240 ℃.
A bag filter manufacturing method characterized by the above. 7. 7. The method for producing a bag filter according to claim 6, wherein the heat setting is performed by a heat setter that does not substantially pressurize and does not use the width regulating pin. 8. The bag filter manufacturing method according to the fifth aspect, wherein the heat setting temperature is 240 to 280 ° C.

The present invention will be described in detail below. First, the bag filter of the present invention is a rectangular felt in which a scrim mainly composed of synthetic fibers and short fibers are integrally molded, and is sewn into a cylindrical shape, and the shape thereof must be substantially a regular cylindrical shape. Even if the bag filter has a lantern shape whose diameter changes in the longitudinal direction, a deformed shape such as a banana shape that curves in the longitudinal direction, or a bag filter with large irregularities in the sewing line, it can be removed by dust removal operations such as mechanical and reverse airflow methods. Soot and dust in the deformed portion are likely to remain, resulting in a large decrease in air permeability. It also tends to occur when the gas temperature drops, but when a part of the gas component condenses (condensation of water or brewing component), the bag filter deforms, causing parts and irregularities with chicks and folds. Accumulate in the seams you have,
This portion selectively undergoes chemical aging, leading to the destruction of the filter cloth. Place the bag filter sewn in a cylindrical shape on a horizontal surface, fold it flatly into an envelope, and make the folded shape almost rectangular. Hereinafter, this is called a flat state. If it is difficult to obtain a flat state because a reinforcing metal fitting is sewn into the upper or middle part of the bug or the bottom is sewn into the lower part, flatten the cylinder from which the metal fitting and the bottom are removed. A flat bag filter with a large width in the length direction (this is called flat diameter) 1
0 points are measured, and then 10 points having a small flat diameter are measured. The average value (D) and range (r) of these are obtained.
Then, rD% defined by the following mathematical formula is calculated. (R / D) × 100 = rD% A substantially rectangular center line in a flat state (referred to as a straight line A) and a variation u of a deviation between this and the long side in the flat state are measured. u is the difference between the maximum distance and the minimum distance of one long side from the straight line A. Since there are two long sides, find u for both sides and use the larger one. Then measure the length L of the straight line A. Then, uL% and uD% defined by the following formulas are calculated. D is the average value of the above-mentioned flat diameter. (u / L) × 100 ＝ uL% (u / D) × 100 ＝ uD% Make the longitudinal sewing line visible when the bag filter is flattened. Straight line parallel to straight line A (straight line B
Angle) and the tangent line at any point on the sewing line φ
Ask for. This tangent line shall be a straight line connecting two points with a distance of 5 cm or more on the sewing line. The crossing angle is measured based on the straight line B and the angle in the smaller direction is adopted. For angle measurement, the long side length 15c with the intersection of the straight line B and the tangent as one of the vertices
Assuming a triangle of m or more, measure the length of the side and calculate it using a trigonometric function. The maximum value of φ is the seam parallelism θ. Here, the regular cylindrical shape means one satisfying all the following numerical values. rD% ≦ 5, uL% ≦ 1, uD% ≦ 5, −5 ≦ θ ≦ 5

Next, the difference in length between the two long sides (sides sewn together) of the cut rectangular felt divided by the length of the short side (M%). Must be less than 1%. When this is expressed by an equation, if the length of the short side is M1 and the length of the long side is M2, then ((M2-M1) / M1) * 100% = M%. M1 and M2 are measured including the flare length of each side. When M% exceeds 1%, sewing is performed in order to align the ends. When the sewing side is loosened, the unevenness of the sewing part and its surroundings becomes large, and the peelability of dust accumulated in the recess becomes poor and ventilation It is not good because it becomes less uniform and becomes non-uniform filtration, and it is more susceptible to selective chemical deterioration upon condensation. If it is not bulged, the long side after sewing will be left over, and there will be problems such as time and labor for cutting the excess part and loss of shape and deformation into a banana shape. In order to reduce these problems, M% is more preferably 0.6% or less.

Next, the warp threads of the felt scrim are substantially parallel to the center line of the bag filter cylinder, and the stitching line is substantially the center line of the bag filter cylinder.
It is important that they are almost parallel to the warp of the scrim. Needless to say, the strength and elongation of the nomig filter have a great effect on the contraction rate and the amount of deformation when the load increases due to the accumulation of soot and dust, but it is the scrim, but the strength and elongation of the woven fabric is generally in the warp direction (yarn and texture, Depending on the density, it may be in the weft direction, in which case it may be in the weft direction.) Therefore, in this bag filter, the warp of the scrim is almost parallel to the center line of the bag filter cylinder, and It is important that the sewn joint line is approximately parallel to the centerline of the Bagfinoletter cylinder. If the parallelism deteriorates, if dust is accumulated below the bag filter due to accumulation of soot and dust, the bag is likely to be deformed downward while contracting in the radial direction. If it becomes thinner in the radial direction, the bag filter will be pressed tightly to the retainer (cylindrical metal fitting made of metal wire to keep the shape of the bag filter), which will cause a problem of poor dust removal and poor filtration performance. Here, "substantially parallel" means that the crossing angle between the straight line B, which is the center line of the rectangular longitudinal direction in which the bag filter is flattened, and the tangent line of each thread of the scrim, which is almost parallel to this, is less than a certain angle. To tell. It is obtained in the same way as the intersection angle between the tangent line of the sewing line in the longitudinal direction and the straight line B is obtained, but since the felt cannot usually see the thread of the scrim from the surface, it is determined by the following method. . Pay attention to the cross section obtained by cutting the felt of the bag filter in the direction orthogonal to the straight line A. Let y be the distance between the cut warp yarns appearing in the cross section. For y, measure the distance Y1 occupied by at least 40 warps (n1) in the cut surface, and then measure the distance Y2 occupied by n2 warps in different portions, and also Y3 corresponding to n3. Calculate by the following formula. y1 = Y1 / (n1-1) y2 = Y2 / (n2-1) y3 = Y3 / (n3-1) y = (y1 + y2 + y3) / 3 Next, pay attention to the cross section of the felt cut in the direction parallel to the straight line B. To do. The cut warp interval x appearing in this cross section is measured. x is an average value obtained from the number of cut warp yarns within a distance X (10 cm or more or 20 times v or more, whichever is larger). If the cut warp does not exist within the distance X, x = X. x is measured over the entire length of the bag filter in the longitudinal direction, and the minimum value is adopted. Straight line B according to the following formula
The Sugleader, which represents the parallelism between the warp and the scrim warp, also calculates the rim warp parallelism (X / y). (X / y) = X / y (X / y) means that the larger the value, the more parallel. If this value is 11.5 or more, the warp yarns of the scrim can be regarded as being substantially parallel to the straight line A, and the above-mentioned problems are less likely to occur. It is preferably 20 or more.

Next, it is important that the bag filter is not substantially deformed by heat treatment at 240 ° C. The temperature at the time of exhaust gas filtration in municipal waste incinerators, industrial waste incinerators, etc. is regulated to 200 ° C or lower as described above, but in reality, when the operation is unstable such as when starting or stopping, In case of abnormal combustion due to the concentration of inflammable incinerated matter, it may take longer than this for a short time, and it is important for safety to prevent substantial deformation at 240 ° C. Deformation during use tends to occur during manufacturing of the felt, especially when non-uniform tension (strain) remains during heat setting. Since the shape of this bag filter has a great influence on the removal property and air permeability (air permeability) as described in detail above, it is necessary that it does not deform even during use. The fact that it does not deform by heat treatment at 240 ° C. means that the heat deformation rate (LL%) of the felt obtained in the heat deformation test of the bag filter described later is 3% or less, preferably 2.5% or less. Of course, after treating the bag filter in an oven at 240 ° C for 24 hours, immediately spreading the bag filter on a horizontal surface at room temperature and leaving it for 2 hours or more, it means that the bag filter has a regular cylindrical shape. If the bag filter is large, cut it into a size that fits in the oven and process.

Next, in the bag filter of the present invention, it is also an important requirement that 30% or more by weight of the felt is made of polyphenylene sulfide fiber. Normally, waste incinerators are regulated to 200 ° C or lower as mentioned above in terms of measures against dioxin, but polyolefin fibers, polyacrylonitrile fibers, polyester fibers, and polyamide fibers are particularly insufficient in terms of heat resistance. Although the fiber is considerably improved in heat resistance, it is insufficient in terms of some chemical resistance, and in the present invention, heat resistance, heat shrinkage, strength (including durability), flame resistance, chemical resistance, etc. It is preferable that 30% or more of polyphenylene sulfide fiber excellent in these properties required for the bag filter is contained. More preferably, it is 40% or more. Fibers other than the polyphenylene sulfide fiber, including glass fiber, are appropriately selected depending on the application of the bag filter, use conditions and the like.

The polyphenylene sulfide resin includes cross-linked type polymers and linear type polymers, which are often used as resins, but the latter having an increased degree of polymerization is used for fibers. Spinning is performed by using this resin in the melt spinning method by the same ordinary method as polyester fibers, polyamide fibers and the like. Similarly, short fibers are spun, drawn, and crimped, and then cut. Examples of these fibers include Procon (registered trademark) manufactured by Toyobo Co., Ltd.

Next, a heat set which does not pressurize the bag filter felt mainly comprising synthetic fibers and short fibers, which constitutes the bag filter of the present invention, is heat set at least without using the width regulating pin. It is preferable to use a felted material for producing the bag filter of the present invention.

The bag filter is used in an urban refuse incinerator, an industrial waste incinerator or the like at a high temperature for a long time as described above. Therefore, when the felt contracts, the retainer is pressed tightly, and even if vibration is applied mechanically or with pulse jet air to dislodge the dust, it is difficult for the dust to be peeled off, which reduces the air permeability and lowers the filtration capacity. To do this, entangle the scrim and short fibers into a felt,
A heat treatment is performed so that a predetermined thermal contraction rate is obtained, and in order to obtain a predetermined width, tension is set in the width direction with a pin.

However, when a pin is used to remove the phenolic material from the pin, the felt material is 300 to 1000 g / m ² , and the thickness is 1.0 to
Since it is made of heavy and thick material of 3.Omm, it has a large pull-out resistance, a large tension is applied, and it runs with the widthwise end pulled. Therefore, tensile strain is generated in the width direction of the felt material due to the difference in tension applied to the edge portion and the center portion of the felt material that has not yet been completely cooled, and the edge portion is likely to have a longer wavy flare state. If there is flare at the end, the end cut portion is long and the cut line near the center of the felt is short. The above problem occurs when sewing is performed using such a cut piece. Therefore, sewn joint surfaces are usually sewn with a difference of more than 1.0%. In this case, the above-mentioned problem occurs. To prevent this, heat treatment is performed again to remove distortion, cutting is performed so that flare parts are not included, and there is an extra step or loss such as cutting once and then cutting again into a rectangle. There are problems that the size of the filter becomes large, that the felt material is deformed and the warp and the weft are not orthogonal to each other, and that the strength utilization factor is reduced and the life of the bag filter is shortened.

In order to prevent such problems in the present invention, these problems are solved by heat setting without using the width regulating pin at the time of heat setting in which the felt used in this bag filter is not pressurized. I found a thing to do. This heat setter may be used between any steps such as a hot press calendering performed after felt forming and a hair-burning step, but it is preferable to use it in the last step to remove thermal strain.

Next, it is an important requirement that the heat setting temperature is 240 ° C. or higher. Of course, this set temperature depends on the type of synthetic fiber, but the gas temperature at the exhaust gas filter inlet in ordinary incinerators for municipal waste, industrial waste, etc. is 200
Although it is regulated below ℃, in actual filtration, a large amount of water is added to cool the exhaust gas, and it is operated in a substantially hot state. Generally, the actual set effect of hot heat and dry heat is the wet set. Is higher, and the difference is said to be 30-40 ° C. Further, as described above, the temperature becomes higher during abnormal conditions, so in order to eliminate the problem of shrinkage during use, it is preferable to set the treatment temperature at 240 ° C. or higher and the treatment time for 1 minute or longer, depending on the fiber used. More preferably, the temperature is 250 ° C. or higher and 1 minute or longer, depending on the fibers used.

Next, the polyphenylene sulfide fiber was
The heat setting temperature of the felt containing more than 30% is 240 ℃ ～ 280 ℃
Is desirable. Since polyphenylene sulfide fiber is not heat-set sufficiently as described above at a temperature of less than 240 ° C, there is a problem that the shrinkage rate becomes large and the shape-retaining property and the dust-peeling property are problematic, and when it exceeds 280 ° C, deterioration or partial melting occurs. The air permeability is lowered, which is not preferable.

Next, the fineness of the short fibers has a great influence on the filterability, and the smaller the fiber diameter (the smaller the fineness) is, the larger the filtration area becomes. Generally, the fiber diameter is preferably 23 μm or less. Furthermore, in the case of municipal refuse incinerators, the so-called dust collection, including the two-stage dust collector and ash melting furnace, has a very wide range of particle sizes of O.3 to 200 μm. In the filtration of the bag filter, a cake layer called a primary dust layer is first formed on the filtration surface, which further improves the filtration performance. Therefore, the dust that was thrown off adhered to the surface of the bag filter.
It is important that only the secondary dust layer is preserved and the above primary dust layer is preserved as it is. In order to prevent the primary dust layer from falling off, it is more advantageous for the inter-fiber voids to consist of various types to secure the dust with various particle sizes as described above. Thing, the cross section is round,
It is preferable that Y, U, V, C and other modified materials are mixed. Even when it is used without forming a cake layer, various fiber thicknesses and cross-sectional shapes are used. In particular, for filtering fine particles, it is preferable to use a material having a small fiber thickness and a complicated cross-sectional shape.

Various filtration methods can be used to reduce or detoxify harmful substances such as municipal waste incinerators and industrial waste incinerators that contain harmful substances. First, slaked lime and an absorbent are added to remove HCl and SOx. A catalytic reaction tower is provided to remove NOx, and ammonia is blown in to carry out a reduction reaction. In addition, there are cases where powdered activated carbon is blown in due to regulations on dioxins. In addition, it is obligatory to keep the exhaust gas temperature in the filtration zone below 200 ° C, and water is often added to cool the exhaust gas. Therefore, the soot-containing dust gas is the unrecovered and unreacted H
Soot dust adheres to the filter cloth in a state of containing Cl, SOx, NOx and additives, a large amount of water, and a part of unburned oil in the waste. Therefore, it may be difficult to fall off even by the dust removal operation. (Residual HCl, SO
Further, x, NOx, etc. are rendered harmless by post-treatment. ) In order to facilitate the removal of soot and dust, it is also preferable to perform water supplementation and pumping.

It is essential that the pumping and oil processing agents for this purpose endure the use conditions of the bag filter, and as described above, high temperature durability, chemical resistance (strong acidity, strong alkalinity),
It is necessary to have excellent abrasion resistance, and a fluororesin-based water repellent or oil repellent is preferable. Specific examples include tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, ethylene / tetrafluoroethylene copolymer, and tetrafluoroethylene.

Next, the basis weight of this felt is preferably 400 g / m ² or more for general municipal waste incinerators and industrial waste incinerators. The fabric weight of felt is an important factor that determines the performance as a filter cloth, such as air permeability, filtration rate and filtration efficiency. If the basis weight is small, it will be affected by manufacturing variations and the space between the fibers that make up the felt will become large, causing leakage of soot and dust, resulting in poor reliability. Inferior resistance to the weight of soot dust adhering to the surface and dimensional change of the felt over time, especially elongation
(Creep) easily occurs, which is not preferable. In order to maintain the reliability and enhance the filtration performance, the basis weight is more preferably 450 g / m ² or more, although it depends on the application and the standard.

The felt for a filter of the present invention is composed of a scrim as a support layer and a filtration layer made of short fibers. The felt molding of the short fibers is performed by laminating the short fibers with a card web or the like and then The entanglement can be performed by the one-doll punching method or the water punching method, but any of them may be used in the present invention. The method for laminating the short fibers on the scrim is not particularly limited. To change the machine direction and transverse direction of the short fibers, for example, adjust the feeding angle and speed of the card web through the cross layer and the $ 21 punch line speed or adjust the longitudinal direction of the $ 21 punch line. It is possible to directly supply the card web to the, and adjust the amount. Further, for the purpose of improving dust releasability, calendering, surface shirring, quilling treatment, etc., in which a heating roller is brought into contact with and pressed to smooth the surface can be applied.

Hereinafter, the present invention will be described more specifically by way of examples. The present invention is not limited to these examples. The physical properties used in this example are measured by the following methods.

The basis weight is represented by JIS L1096 6.4 mass per unit area. Three 20 cm x 20 cm samples are taken, the absolute dry mass W'of each is measured, and calculated by the following formula. Unit weight (g / m ² ) = W ′ × (1 + r / 100) × 1 / a where W ′: absolute dry mass (g) r: official moisture regain (%) a: area of test piece (m ² ).

The air permeability is measured at n = 3 using a high pressure type air permeability tester manufactured by Techno World, and expressed as an average value. (Measuring pressure: 124Pa)

Long-side length difference ratio: A rectangular cut felt placed on a horizontal plane and the dimensional difference of the long side divided by the value of the shorter long side, expressed as a percentage. The flare part is measured on the horizontal surface including the flare length. If it is difficult to measure the length of the flare, cut on the assumed sewing line on the long side where flare is occurring. The length of the cut long tape is measured and taken as the length including flare. When measuring from the sewn bag filter, remove the sewing thread in the longitudinal sewing part of the cylinder from which the reinforcing cloth and metal fittings on the upper and lower parts of the bag fin letter have been removed, and make the condition before sewing the dimensional difference on one long side as described above. To measure.

Thermal deformation test of bag filter felt: The felt before or after sewing is cut into a square with a side of 40 cm and used as a sample. The direction of the side is the longitudinal direction of the bag filter
Align with (vertical) and at right angles (horizontal). Mark the sample so that the vertical and horizontal directions are known. Then draw a line through the center of the sample and parallel to each side, and mark at a position 15 cm away from this center point. After leaving the sample in a place controlled by standard conditions for 24 hours or more, measure the vertical and horizontal lengths (LLO). Then put the sample in the oven at 240 ℃.
× Dry heat treatment for 24 hours. After the dry heat treatment is completed, the sample is taken out of the oven and left for 24 hours or longer in a place controlled to a standard state, and then the length and width (LL1) is measured. The thermal deformation rate (LL%) of felt is calculated by the following formula. LL% = (LLO-LL1) / LLO × 100 LL% is measured in the vertical and horizontal directions, respectively. In addition, three samples are created for each felt, and the average value of the three values is used as the felt value. Bag filter shape after retainer set: Diameter 161-
Observe the appearance of the bag filter when sewn with a bag filter of 163 cm and length of 3000 ± 30 mm and attached to the retainer. The sewing method of the bag filter is S012T3-1 made by Japan GORE-TEX Co., Ltd. using sewing thread PTFE fiber, 3 stitches, stitch pitch 13 to 15 stitches / 6 cm, stitch line distance 3.5 to 4.Omm, and seam 13 to 15 mm. The retainer used had a diameter of 160 to 161 mm, a distance between rings of 175 to 185 mm, a distance between vertical lines of 38 to 42 mm, and a length of 3050 mm.

Bag filter filtration test conditions are model UDC-814PS manufactured by Shinto Dust Collector Co., Ltd., bag filter size diameter 165 mm length 5500 mm, the same number of 96 filters, with a test bag filter attached, and exhaust gas temperature 170 ~ 200 ℃,
The operation was performed with a filtration rate of 1.3 rn / min, a pressure drop of 200 mm water column, a pulsed jet system with a dropout, and a constant pressure drop control. Exhaust gas is the combustion gas of the industrial waste incinerator whose polymer layer is mainly composed of polyester polymer. The test period was 25 days of continuous operation. At the end of the test, a pulse pulse jet was struck to finish the test and the test bag filter was removed. The test bag filter was sewn to the above size, and two pieces were attached for each level of the example and comparative examples, and the sensory test was performed for deformation of the bag filter, wrinkles and cracks on the cloth surface, dust peelability, and retainer detachability. It was evaluated by. It was judged that those that were easy to put on and take off had good maintainability. Comparative Example 1 was not sewn and filtered because it was not suitable as a filter medium without a bag filter filtration test.

[0032]

[Example] The felt for a filter was prepared by a general non-woven fabric processing process. As for the heat setter, Ichikin Kogyo Co., Ltd.'s high temperature heat treatment machine was modified so that it could be processed without using width control pins. The felt heating time was 1.5 minutes. Table 1 shows scrim, materials used as short fibers (scrim, short fibers), PPS mixing ratio, felt weight, presence or absence of heat setter pin, same temperature, thermal deformation rate of felt, bag filter shape after retainer set, cutting Difference rate M (%) of the length of the long side of the piece, bag filter appearance shape as bag filter shape data, index of parallelism of scrim warp x /
y, diameter variation index uD%, uL%, arc degree rL%, seam parallelism θ, practical machine filtration test result and suitability of bag filter are shown. In the table, ◯ indicates that it is preferable as a bug finoletter, and X indicates that it is not preferable.

The material indications in Table 1 are as follows. PPS: Polyphenylene sulfide fiber is Toyobo
Procon (registered trademark) short fiber 2.2dtex, fiber length 60m
m, PI: Polyimide fiber is made by Inspec Fibers
The scrim with P84 short fiber 2.2 dtex and fiber length 60 mm PPS was a plain weave with a process length of 500 dtex 120 filament twist number S150 T / M, and 22 lines / in for each line. The PI scrim used was P84 long fiber 1060 dtex 480 filament twist number Z80T / M, and weave plain weave with each 12 wefts / in. First, PPS and PI in Table 1 were pre-opened with a mixed cotton machine, then opened with a roller card, fiber arrangement was performed, then the web on one side was laminated with a cross layer, the scrim was aligned, and then the penny bread was placed. Do and wind up. This is called an intermediate felt. Similarly, stack the web on the other side and match the intermediate felt that was rolled up earlier,
Then, a penny bread and a finishing 21 bread are performed to obtain a rolled felt material. The basis weights of the short fibers on both sides were almost the same. This felted material was heat-treated under the conditions shown in Table 1, and then pressed at 200 ° C. and 30 kgf / cm. The calender temperature was 230 ° C. only in Example 4 and Comparative Example 4.

The bag filters of Examples 1 to 4 had a regular cylindrical shape and were suitable as bag filters even in the filtration test. In Comparative Example 1, the set temperature was higher than the melting point of the used PPS fiber and it hardened and stiffened, and the felt lacked flexibility, and the air permeability was as small as 1 (cc / square cm / s), and the surface cracked even when bent. Was generated and was not suitable as a filter medium.

In Comparative Example 2, since the set temperature was low, the deformation rate LL% of the bag filter in the thermal deformation test was large, and the shrinkage which seems to be due to the abnormal temperature during the over-test still occurred and the retainer was tightened and removed for a long time to repair. It was found to be inadequate as a filter medium because it was inferior in properties and that dust adhered to the surface and the dust separation by the pulse jet was not sufficient.

In Comparative Example 3, since a pin was used in the heat setter, flare occurred and the difference L% in the length of the long side was large, the appearance of the sewing bug was banana-shaped, and it was difficult to attach it to the retainer. It didn't turn well.

Although Comparative Example 4 is a felt of PIlOO%, since a pin is used, a flare of a degree larger than that of Comparative Example 3 is generated, a difference rate L% of the length of the long side is large, and the appearance of the bug is sewn by force. It had a banana shape and a lantern shape, and it was difficult to attach it to the retainer, and the seam line was not bent well after attachment.

[0038]

[Table 1]

[0039]

EFFECTS OF THE INVENTION According to the present invention, the bag filter is not deformed even when used for a long time, the filterability and the air permeability are not lowered so much, and the dust is easily peeled off. It has become possible to provide a bag filter with excellent resistance to occurrence.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a method for measuring diameter variation.

FIG. 2 is a schematic diagram showing variations in displacement of long sides.

FIG. 3 is a schematic diagram showing a difference in length of long sides of cut pieces.

FIG. 4 is a schematic diagram showing seam parallelism.

FIG. 5 is a schematic view showing scrim warp parallelism.

[Explanation of symbols]

1: Flat bag filter, 2: Cut pieces, 3: Center line (straight line A), 4: Small flare side, 5: Large flare side, 6: Sewing line, 7: Scrim warp.

Claims (8)

[Claims] 1. A bag filter formed by sewing a rectangular felt material, which is composed mainly of a scrim mainly composed of synthetic fibers and short fibers, into a cylindrical shape, wherein the bag filter has a substantially regular cylindrical shape, and the rectangular shape A bag filter characterized in that the difference in length between the long sides sewn in is less than 1%. 2. The bag filter according to claim 1, wherein the difference in length between the long sides is 0.6% or less. 3. The warp threads of the scrim are substantially parallel to the cylindrical center line of the bag filter, and the sewing joining line thereof is substantially parallel to the cylindrical center line of the bag filter.
The described bug filter. 4. The bag filter according to claim 1, which is not substantially deformed by heat treatment at 240 ° C. 5. The bag filter according to any one of claims 1 to 4, wherein 30% or more by weight of the felt is made of polyphenylene sulfide fiber. 6. A method of manufacturing a bag filter, wherein the heat setting temperature of a bag filter felt material mainly composed of synthetic fibers and short fibers is 240 ° C. or higher. 7. The method of manufacturing a bag filter according to claim 6, wherein the heat setting is performed by a heat setter that does not substantially pressurize and does not use the width regulating pin. 8. The method for producing a bag filter according to claim 5, wherein the heat setting temperature is 240 to 280 ° C.