JP4582475B2 - Felt manufacturing method - Google Patents

Description

The present invention relates to a method for producing a filter , and more particularly to a method for producing a filter having a function of decomposing harmful substances.

  The exhaust gas from the incinerator is discharged with dust and components that are harmful to the lives of living organisms including humans such as dioxins and nitrogen oxides (NOx). Dust is removed by a bag filter or an electrostatic precipitator. Dioxins, nitrogen oxides (NOx), etc. are decomposed by a decomposition catalyst or adsorbed by activated carbon or the like.

  Up to now, as a method for decomposing toxic substances, a catalyst filter base material in which titanium oxide is coated in a thin film on the inorganic fiber surface (see Patent Document 1), glass fiber cloth is impregnated in titanium oxide sol, heat treated, and further metavanadine. A method of impregnating ammonium acid and heat-treating to adhere the catalyst to the surface of the glass fiber (see Patent Document 2), A method of forming a coating of titania particles by dipping or spraying the glass fiber in colloidal titania [Patent Document] 3)] was proposed. However, if the catalyst is simply supported on the fiber surface such as glass fiber, the catalyst is scattered along with the passing gas, and there is a problem that it is difficult to maintain the effect for a long time.

  As countermeasures, exhaust gas treatment filter cloth in which a base cloth for removing dust, a base cloth for adsorbing and removing harmful substances, and a base cloth having a catalytic component for decomposing harmful substances are sequentially laminated with an inorganic binder [Patent Document] 4), a proposal to suppress the scattering of the catalyst, such as a harmful substance removal filter (see Patent Document 5) in which a catalyst for decomposing harmful substances is arranged in an intermediate layer, a dust removing layer on one side, and a support layer on the other side. However, it was not satisfactory because the catalyst of fine particles sometimes came out from the gap of the texture of the base fabric as the support layer.

  Furthermore, there is a proposal of a configuration (see Patent Document 6 and Patent Document 7) in which a particulate catalyst is supported in a filter cloth and a porous film having fine pores is adhered to suppress the catalyst from falling off. The membrane may be broken, and the gas distribution in the porous membrane is not good, so it is not a satisfactory improvement. In addition, a catalyst filter material (see Patent Document 8) configured as a dust collecting layer / catalyst fiber layer / abrasion resistant layer, and a polymer solution such as polyamideimide on a non-woven fabric to which a catalyst is attached. There are proposals such as a method of impregnating and heat-treating and immobilizing the catalyst on the fiber (see Patent Document 9), but when the catalyst is coated with a polymer, the active sites on the catalyst surface are not exposed, There is a disadvantage that the catalytic function is lost.

  Further, an exhaust gas purifying apparatus provided with a net-like base material carrying a catalyst so that exhaust gas that has passed through the filter cloth of the bag filter is in contact with the inside or outside of the bag filter so that the catalyst is not dispersed [see Patent Document 10] The fins carrying the catalyst are arranged radially inside the cylindrical filter body, and dust in the exhaust gas is first removed by the cylindrical filter, and then contacted with the internal radial fins to decompose NOx and dioxins. The proposal of the bug filter structure (refer patent document 11) to make was made. In addition, there is also a proposal of a baghouse type dust collecting apparatus (see Patent Document 12) in which a photocatalytic reactive substance is supported on a fiber assembly constituting a bag filter and installed together with a light source that generates ultraviolet rays.

JP-A-3-221146 JP-A-9-220466 Japanese Patent No. 3138312 JP-A-11-309316 JP 2003-275515 A JP-A-11-309317 Japanese Patent Laid-Open No. 10-230119 JP 2003-265967 A Japanese Patent Laid-Open No. 10-328515 JP-A-11-19477 JP 2001-269528 A JP 2003-299926 A

  As mentioned above, the focus is on how to fix the catalyst that decomposes harmful substances to the felt, but the fine particles of the catalyst are stably attached to the felt, and backwashing in bag filters etc. It is important to be able to withstand the flow of gas in the opposite direction.

From such a point of view, the object of the present invention is that fine particles such as catalysts are present stably in the felt without losing their functions, and the gas is not reversed in the case of normal gas flow. It is an object of the present invention to provide a method for producing a felt that can be made into a felt containing a catalyst that does not scatter even when it flows.

In order to solve the above-mentioned problems, the present invention provides a first web layer, a first base fabric layer, an active powder layer, a second web layer, and a second base fabric layer which are sequentially laminated and integrated by needling. A felt manufacturing method comprising an active powder layer comprising titanium oxide, vanadium oxide, silver oxide, tungsten oxide, silicon oxide, aluminum oxide, zirconium oxide, molybdenum oxide, cobalt oxide, copper oxide, manganese oxide One or more metal oxides selected from the group consisting of polyvinyl alcohol (PVA), carboxymethyl cellulose, ethyl cellulose, xanthan gum, guar gum, gum arabic, alginate, polyacrylate, and vinyl acetate. Applying the slurry added to the aqueous solution containing the agent on the side of the first base fabric layer facing the second web layer, and needling According some to be formed by heat treatment at 100 to 200 ° C. before or after integration.

A second aspect of the present invention is the felt manufacturing method according to the first aspect, wherein the active powder layer further includes activated carbon in addition to the metal oxide .

Claim 3 is the method for producing felt according to claim 1, wherein the first web layer and the second web layer are fluorine fibers, polyester fibers, polyamide fibers, acrylic fibers, aramid fibers, polyphenylene sulfide fibers, cotton fibers, One or more selected from glass fibers and inorganic fibers are used as the constituent materials.

Claim 4 is the method for producing felt according to claim 1, wherein the first base fabric layer and the second base fabric layer are made of fluorine fiber, polyester fiber, polyamide fiber, acrylic fiber, aramid fiber, polyphenylene sulfide fiber, cotton. One or more selected from fiber, glass fiber, and inorganic fiber are used as the constituent material.

As an effect of the present invention, there is produced a felt in which the particulate catalyst is stably present in the felt without losing the catalytic function and is not scattered with the gas flow.

The felt targeted by the present invention has a laminated structure in which at least a web layer, a base fabric layer, an active powder layer, a web layer, and a base fabric layer are sequentially laminated, and these are integrated by needling. For convenience, the laminated structure is referred to as “first web layer, first base fabric layer, active powder layer, second web layer, second base fabric layer”.
Here, the active powder used for the active powder layer is selected from titanium oxide, vanadium oxide, silver oxide, tungsten oxide, silicon oxide, aluminum oxide, zirconium oxide, molybdenum oxide, cobalt oxide, copper oxide, and manganese oxide 1 One or more metal oxides, which are one or more thickening bonds selected from polyvinyl alcohol (PVA), carboxymethylcellulose, ethylcellulose, xanthan gum, guar gum, gum arabic, alginate, polyacrylate, and vinyl acetate. In addition to the aqueous solution containing the agent, it is applied as a slurry between the first base fabric layer and the second web layer.

The first web layer is a layer exposed on one surface of the felt. When the felt produced by the method of the present invention is used as a bag filter, the first web layer is a layer for capturing fine particles such as dust. Materials used for the first web layer include synthetic fibers such as fluorine fibers, polyphenylene sulfide fibers, aramid fibers, polyamide fibers, polyester fibers, and acrylic fibers, natural fibers such as cotton and wool, inorganic fibers such as glass fibers and ceramic fibers, etc. One or more types such as inorganic fibers and metal fibers such as stainless steel fibers may be arbitrarily selected, and other types of fibers may be mixed. The shape of the fiber is not particularly limited as long as it functions as a felt. Typically, a fiber having a length of 0.8 to 10.0 dtex is cut into a length of 2 to 100 mm, and the basis weight is 30. ˜300 g / cm ²

A 1st base fabric layer becomes a support body of a 1st web layer, and becomes a coating surface of the below-mentioned active powder layer. The material used for the first base fabric layer is synthetic fiber such as fluorine fiber, polyphenylene sulfide fiber, aramid fiber, polyamide fiber, polyester fiber and acrylic fiber, natural fiber such as cotton and wool, inorganic fiber such as glass fiber and ceramic fiber. One or more kinds such as metal fibers such as stainless steel fibers may be arbitrarily selected, and other kinds of fibers may be further mixed. The shape of the base fabric is, for example, a woven fabric in which the basis weight is 50 to 1000 g / m ² by multi-filament, monofilament, and spun yarn being satin weave or plain weave.

The active powder layer is a part responsible for a special function in the felt produced by the method of the present invention, includes a catalyst that decomposes dioxins and nitrogen oxides in the air, and can also include activated carbon.

  Dioxins and nitrogen oxides are known to be decomposed in the air using metal oxides as catalysts. In the present invention, metal oxides such as titanium oxide, vanadium oxide, silver oxide, tungsten oxide, silicon oxide, aluminum oxide, zirconium oxide, molybdenum oxide, cobalt oxide, copper oxide, and manganese oxide are used as decomposition catalysts for dioxins and nitrogen oxides. Products, preferably titanium oxide, vanadium oxide, silver oxide are used. The metal oxides may be used alone or in combination of two or more. In order for the metal oxide to act as a catalyst, contact with air containing dioxins or nitrogen oxides becomes a problem. Therefore, the smaller the particle size of the metal oxide, the better. However, since the ultrafine particles are likely to be scattered out of the felt together with the gas, the particle size is practically 5 to 500 μm, preferably 250 to 350 μm.

  The active powder layer may be mixed with one or more of the above metal oxides and further activated carbon. Activated carbon adsorbs dioxins and nitrogen oxides, and at the same time desorption proceeds under high temperature conditions. Thereby, the residence time of dioxins and nitrogen oxides in the active powder layer can be lengthened, and the contact time with the catalyst is lengthened to increase the decomposition efficiency. Since activated carbon is porous, it can function even if the apparent particle size is large. However, in consideration of sandwiching between felts and subsequent needling, the apparent particle size is preferably 5 to 2000 μm, more preferably 10 to 1000 μm. The mixing amount of the activated carbon is arbitrarily determined, but in order to expect the effects of the metal oxide and the activated carbon, the mixing ratio of the metal oxide and the activated carbon is about 100: (10 to 150).

Metal oxides, or active powder to which was added activated carbon, the write sandwiched form of powder felt Takeno is handling complicated, and it is difficult to uniformly arrange these activities powder felt surface. Therefore, in the method of the present invention, these powders are added to a viscous aqueous solution to form a viscous slurry, which can be easily applied to one side of the first base fabric (the side opposite to the first web) and applied. Thereafter, the particles are easily adhered to each other and to the first base fabric surface. In this way, the thickening binder added to increase the viscosity and adhere it may hinder the ventilation when it is felt. After that, it is decomposed by applying heat. For this purpose, thickening binder must be intended easily decomposed by heat, specifically, polyvinyl alcohol (PVA), carboxymethyl cellulose, ethyl cellulose, xanthan gum, guar gum, gum arabic, alginates, polyacrylic acid Salt, vinyl acetate, etc.

The active powder in the viscous slurry is practically about 50 to 70% by weight in the slurry, and this is preferably applied to one side of the first base fabric. The active powder slurry may be applied to produce a felt as it is, but it is preferably used for felt production after lightly drying after application to reduce the tackiness. The larger the coating amount, the more advantageous, but practically it is about 100 to 600 g / m ² after drying.

  The second web and the second base fabric are basically selected from the same group as the first web and the first base fabric, respectively. These may be the same material and properties as the first web and the first base fabric, respectively, or may be different materials and properties.

The first web layer, the first base fabric layer, the active powder layer, the second web layer, and the second base fabric layer are laminated, and these are integrated by needling. The condition of the needle is not particularly limited, but is about 100 to 15 million pieces / cm ² .

By this needling, the first web layer, the first base fabric layer, the second web layer and the second base fabric layer are integrated, and the active powder is sandwiched between the first base fabric layer and the second web layer. There will be a layer. When the active powder slurry is applied to the side of the first base fabric layer facing the second web layer , the active powder layer is coated with active powder between the first base fabric layer and the second web layer. Although it is in the form of a film, by heating this, the thickening binder is decomposed to become only the active powder. That is, it is heat-treated before or after needling. Alternatively, heat treatment may be performed after the bag filter is used. The thickening binder is decomposed and removed by the heat treatment , and each particle of the active powder is surrounded by a web of web fibers and fixed. As a result, for example, when the gas flows from the first web as a bag filter, the active powder may be scattered outside when the gas flows from the second base fabric through the second web by backwashing or the like. Disappear.

As mentioned above, it is essential for the present invention to decompose the thickening binder of the active powder layer. Therefore, the felt is heat-treated before or after needling. Or when heat required for decomposition | disassembly is added at the time of use of a felt, it may not be necessary to provide a heat treatment process specially. The temperature required for the heat treatment depends on the type of the thickening binder and the time during which heat is applied, but it is usually sufficient if the temperature is 100 to 200 ° C. for about 30 minutes to 24 hours.

The conditions of use of the filter produced by the method of the present invention vary depending on the intended function and the active powder to be used . For example, when the purpose is to decompose dioxins, nitrogen is used at 150 to 250 ° C. together with the exhaust gas. When the purpose is to decompose the oxide, it is preferably carried out at 150 to 250 ° C. while injecting ammonia into the exhaust gas upstream of the bag filter. Under these conditions, a metal oxide that can function as a catalyst for decomposition of dioxins and decomposition of nitrogen oxides is appropriately selected and used.

(1) Production of each layer Web layer: Both the first web and the second web were made of polytetrafluoroethylene (PTFE) cotton having a fineness of 3.3 dtex and a length of 70 mm, each having a basis weight of 270 g / m ² .
Base fabric layer: A PTFE fiber plain weave having a fineness of 440 dtex and a basis weight of 104 g / m ² was used for both the first and second base fabrics.
Active powder layer-1: Titanium oxide, tungsten oxide, and others (silica content, etc.) having a particle size of 30 to 50 μm are mixed at a ratio of 80: 8: 12 (weight ratio), and PVA [Nippon Synthetic Chemical Industry ( Co., Ltd., "GL-05" (trade name)] in addition to a 3 wt% aqueous solution and kneaded well to obtain a slurry having a solid content of 60 wt%. This slurry was applied to the surface opposite to the first web of the first base fabric so that the solid content was about 400 g / m ² .
Active powder layer-2: mixture of the above titanium oxide, tungsten oxide, and others (silica content, etc.) and activated carbon [manufactured by Nimura Chemical Industry Co., Ltd., “Taiko SA1000-W50” (trade name), average particle size 10 μm, ratio Surface area of 1,300 m ² / g] was mixed at a ratio of 100: 10 (weight ratio), and this was added to a 3% by weight aqueous solution of PVA in the same manner as above and kneaded well to obtain a slurry having a solid content of 60% by weight. It apply | coated so that solid content might be set to about 400 g / m < ² > on the surface opposite to the 1st web of a 1st base fabric.

(2) Production of felt Catalyst-carrying filter according to the method of the present invention; laminated on first web layer / first base fabric layer / active powder layer / second web layer / second base fabric layer, and this is about 3.5 million Needle / m ² (total number of flocks) was needled and entangled, and heated at 180 to 200 ° C. for 24 hours. A cross-sectional photograph of this felt is shown in FIGS. FIG. 2 is a partially enlarged view of FIG. In the cross-sectional photographs of FIGS. 1 and 2, the first web layer / first base fabric layer / active powder layer / second web layer / second base fabric layer are from the top, and the base fabric layer is a cross-section of the constituent fibers. Is visible.

Filter used for comparison (supporting catalyst by dipping); 298 g / m ² (fineness 3.3 dtex × length 70 mm) on both sides of the base fabric 104 g / m ² (plain weave base fabric using PTFE fibers with fineness 440 dtex) The PTFE fiber web was needled to obtain a PTFE filter having a basis weight of 700 g / m ² . The PTFE filter was impregnated with a slurry containing a catalyst by a dipping coat machine and impregnated with a solid content of about 400 g / m ² . The slurry containing the catalyst may be obtained by putting a mixed powder obtained by mixing titanium oxide, tungsten oxide, and the like (silica content, etc.) at a ratio of 80: 8: 12 (weight ratio) in a 3 wt% aqueous solution of PVA. The mixture was kneaded to a solid content of 60% by weight.

(3) a 25cm square filter dropping test was pre-weighed catalyst was fixed in a stainless steel frame, the fixed filter surface of the pulse air 4 kgf / cm ² to (directed to the filtration surface from the clean surface) of about 0 Sprayed for 1 second. After repeating 30,000 injections, the filter was removed from the frame and its weight was measured. The reduced amount at this time was defined as the amount of catalyst falling off.

The results are shown in Table 1.

In general, the bag filter sprays pulsed air ( ² to 7 kgf / cm ² ) to remove dust accumulated on the surface. In the catalyst-carrying filter, this pulsed air causes the catalyst carried in the filter to fall off and eventually disappear. The catalyst-carrying filter according to the method of the present invention retained 98.8% of the catalyst by 30,000 pulsed air injections. This number of pulses corresponds to about 5 years when used in an incinerator. Considering that the general durability of PTFE filters is about 3 to 4 years, it is considered that the dioxin removal performance does not decrease greatly during use, and the superiority of this catalyst-supported filter is demonstrated. It was done.

(4) Dioxin removal test Dioxins in the gas before and after the filter are passed through the felt using the active powder layer-1 and the felt using the active powder layer-2 in the exhaust gas of the fluidized bed incineration facility, respectively. Concentration was measured.

The obtained results are shown in Table 2.
High dioxin removal efficiency was obtained with the filter produced by the method of the present invention.

In the felt production method of the present invention, the particulate catalyst can be stably present in the felt without losing the catalytic function, and the produced felt does not cause the catalyst to scatter with the gas flow, and vice versa. It does not scatter even by washing, and therefore the catalytic function can be maintained over a long period of time.

It is a cross-sectional photograph of the felt manufactured in the Example. It is the cross-sectional photograph which expanded the part of FIG.

Claims (4)

A felt manufacturing method in which at least a first web layer, a first base fabric layer, an active powder layer, a second web layer, and a second base fabric layer are sequentially stacked and integrated by needling. ,
  The active powder layer is made of one or more metal oxides selected from titanium oxide, vanadium oxide, silver oxide, tungsten oxide, silicon oxide, aluminum oxide, zirconium oxide, molybdenum oxide, cobalt oxide, copper oxide, and manganese oxide. A slurry added to an aqueous solution containing one or more thickening binders selected from polyvinyl alcohol (PVA), carboxymethyl cellulose, ethyl cellulose, xanthan gum, guar gum, gum arabic, alginate, polyacrylate, and vinyl acetate A method for producing a felt, which is formed by applying to the first base fabric layer facing the second web layer and heat-treating at 100 to 200 ° C. before or after integration by the needling. 2. The felt manufacturing method according to claim 1 , wherein the active powder layer further includes activated carbon in addition to the metal oxide. Each of the first web layer and the second web layer comprises at least one member selected from fluorine fiber, polyester fiber, polyamide fiber, acrylic fiber, aramid fiber, polyphenylene sulfide fiber, cotton fiber, glass fiber, and inorganic fiber. The method for producing a felt according to claim 1 . Each of the first base fabric layer and the second base fabric layer contains at least one selected from fluorine fiber, polyester fiber, polyamide fiber, acrylic fiber, aramid fiber, polyphenylene sulfide fiber, cotton fiber, glass fiber, and inorganic fiber. The felt manufacturing method according to claim 1, wherein the felt is a constituent material.