Composite filter material for preventing bag from being burnt by ammonium bisulfate as well as preparation method and application of composite filter material

Abstract

The invention belongs to the technical field of composite filter materials, and particularly relates to a composite filter material capable of resisting bag pasting caused by ammonium bisulfate, a preparation method and application. The preparation method comprises the following steps that S1, PTFE dispersion resin and an extrusion aid are mixed to obtain a first mixture, the first mixture is aged in a drying oven, and the aged first mixture is subjected to preforming, pushing and calendering to obtain a PTFE calendered belt; s2, a coupling agent, a surfactant, an extrusion aid, a V / Sb / Ce / Ti catalyst and PTFE dispersion resin are mixed to obtain a second mixture, the second mixture is aged in a drying oven, and the aged second mixture is subjected to pre-forming, pushing and calendering to obtain a PTFE composite calendered belt; s3, the PTFE calendering belt and the PTFE composite calendering belt are composited and overlaid, and a PTFE composite film is prepared through a two-way stretching process, high-temperature sintering and cooling; and S4, thermally laminating the catalyst system-doped PTFE composite film and the PTFE needled felt base material to serve as a gas purification surface of the composite filter material, and taking the PTFE composite film without the catalyst as a dust facing surface to prepare the composite filter material capable of preventing the bag from being burnt by ammonium bisulfate.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite filter materials, and particularly relates to an ammonium bisulfate anti-pasting composite filter material, a preparation method and an application thereof. Background Art

[0002] The country's requirements for environmental governance are becoming increasingly stringent. Various industrial flue gases need to reach below 10 mg / Nm3 to meet the emission requirements, and some regions have higher requirements (5 mg / Nm3). Using traditional electrostatic precipitation and needle felt dust removal can no longer meet the emission requirements. PTFE membrane filter products play an important role in the field of industrial flue gas dust removal filtration due to their high filtration accuracy, low energy consumption, easy dust cleaning and other properties.

[0003] However, in the actual use process, the PTFE membrane filter bag will have the phenomenon of bag pasting. The main reason for bag pasting is that ammonia water or ammonia is excessive during the flue gas emission process, and then reacts with water vapor and sulfur dioxide to generate ammonium bisulfate, resulting in bag pasting. Since the dust adheres to the surface of the filter bag and cannot fall off, the resistance during dust filtration becomes larger, manifested as an increase in differential pressure, increasing energy consumption and reducing the service life of the filter material. Moreover, the membrane separation layer of the membrane filter bag is prone to rupture or detachment during use, resulting in excessive dust emission, thus increasing the operating cost of the enterprise and the environmental protection assessment risk. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention mixes PTFE dispersion resin + coupling agent / surfactant + extrusion aid + V / Sb / Ce / Ti catalyst system evenly, and uses the biaxial stretching method to prepare a PTFE double-layer composite membrane doped with catalyst. Among them: the double-layer composite membrane is composed of a dust-facing surface without catalyst addition and a clean gas surface doped with catalyst.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] A preparation method of an ammonium bisulfate anti-pasting composite filter material, the preparation method comprising the following steps:

[0007] S1. Mix PTFE dispersion resin and extrusion aid evenly to obtain mixture one, age mixture one in an oven, and preform and push and calender the aged mixture one to obtain a PTFE calendered tape;

[0008] S2. Mix coupling agent, surfactant, extrusion aid, V / Sb / Ce / Ti catalyst and PTFE dispersion resin evenly to obtain mixture two, age mixture two in an oven, and preform and push and calender the aged mixture two to obtain a PTFE composite calendered tape;

[0009] S3. Superpose and laminate the PTFE calendered tape and the PTFE composite calendered tape. The composite calendered base tape is subjected to a biaxial stretching process, high-temperature sintering, and cooling to produce a PTFE composite film with high mechanical strength and the ability to inhibit the formation of ammonium bisulfate.

[0010] S4. Thermally bond the surface of the PTFE composite film doped with the catalyst system to the PTFE needle-punched felt substrate as the clean gas side of the composite filter material, and the surface of the PTFE composite film without the attached catalyst as the dust-facing side to prepare a composite filter material resistant to ammonium bisulfate bagging.

[0011] Furthermore, the content of PTFE dispersion resin in the first mixture is 70 - 90 wt%, and the content of the extrusion aid is 10 - 30 wt%. The extrusion aid is one of gasoline, aviation kerosene, naphtha, and petroleum ether.

[0012] Furthermore, the coupling agent is a silane coupling agent, specifically including γ-aminopropyltriethoxysilane, vinyltriethoxysilane, and γ-methacryloxypropyltrimethoxysilane; the surfactant is a non-ionic surfactant, specifically including fatty acid glycerides, polyoxyethylene fatty acid esters, and polyoxyethylene fatty alcohol ethers; the extrusion aid is one of gasoline, aviation kerosene, naphtha, and petroleum ether. In step S2, the content of the dispersion resin is 70 - 80% of the total addition amount, the content of the extrusion aid is 10 - 15% of the total addition amount, the content of the surfactant is 1 - 5% of the total addition amount, the content of the V / Sb / Ce / Ti catalyst is 1 - 5% of the total addition amount, and the content of the coupling agent is 1 - 5% of the total addition amount.

[0013] Furthermore, the ratio of V:Sb:Ce:Ti in the V / Sb / Ce / Ti catalyst is 1:3:3:3.

[0014] Furthermore, in steps S1 and S2, the temperature in the oven during aging is 40 - 60 °C, and the aging time is 12 - 24 h.

[0015] Furthermore, in step S3, the biaxial stretching process is asynchronous biaxial stretching or synchronous biaxial stretching. The temperature in the degreasing zone during stretching is 100 - 320 °C, the temperature in the stretching zone is 120 - 350 °C, the sintering temperature is 300 - 450 °C, the cooling rate during cooling is 5 - 50 °C / min, the longitudinal stretching ratio is 5 - 20, and the transverse stretching ratio is 10 - 20. The air permeability of the obtained PTFE composite film is 100 - 200 mm / s.

[0016] Furthermore, the calendering thickness of the PTFE calendered tape is 100 - 500 μm, the calendering thickness of the PTFE composite calendered tape is 100 - 500 μm, and the thickness of the double-layer PTFE composite film is 5 - 20 μm.

[0017] Further, during the thermal lamination in step S4, the temperature is 320 - 380 °C, the pressure between the front and rear rubber rollers and the hot roller is 0.1 - 1 MPa, the distance is 0.08 - 0.6 mm, and the speed is 5 - 15 m / min.

[0018] An anti-ammonium bisulfate bag caking composite filter material is prepared by the preparation method of the anti-ammonium bisulfate bag caking composite filter material described above.

[0019] The anti-ammonium bisulfate bag caking composite filter material as described above is applied in the fields of cement, steel, and electricity.

[0020] Advantages of the present invention:

[0021] 1. The addition of the coupling agent and the surfactant is to make the PTFE dispersion resin and the V / Sb / Ce / Ti catalyst mix evenly and crosslink with each other, so that there is a certain intermolecular force between the PTFE dispersion resin and the V / Sb / Ce / Ti catalyst, preventing the catalyst from falling off during the actual working conditions of the composite membrane.

[0022] 2. The double-layer PTFE membrane has high strength, and the PTFE membrane on the dust-facing surface can protect the catalyst loaded on the clean gas surface, avoiding the catalyst from falling off due to the mechanical scouring of dust.

[0023] 3. The V / Sb / Ce / Ti catalyst system can inhibit the formation of ammonium bisulfate, thus avoiding a large amount of ammonium bisulfate adhering to the surface of the filter material and causing bag caking, and solving the problems of large pressure difference and filter bag replacement caused by bag caking. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0025] Figure 1 It is the preparation flow chart of the preparation method in the present invention;

[0026] Figure 2 It is the cross-sectional view of the anti-ammonium bisulfate bag caking composite filter material prepared in the present invention.

[0027] Wherein: 1 - substrate (PTFE needle punched felt), 2 - doped catalyst PTFE membrane (clean gas membrane surface), 3 - PTFE membrane without attached catalyst (dust-facing membrane surface) Specific Embodiments

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0029] Example 1:

[0030] A preparation method of an ammonium bisulfate anti-pasting composite filter material, the preparation method comprising the following steps:

[0031] S1. Mix PTFE dispersion resin and an extrusion aid (such as gasoline, aviation kerosene, naphtha, petroleum ether, etc.) through a V-type mixer to obtain a first mixture. Age the uniformly mixed first mixture in an oven, where: the content of the extrusion aid is 15 wt%, the oven temperature during aging is 40 °C, and the aging time is 12 h; subject the treated mixture to pre-forming and push extrusion and calendering to obtain a PTFE calendered tape, where: the calendered thickness is 200 μm;

[0032] S2. Mix a coupling agent / surfactant, an extrusion aid, a V / Sb / Ce / Ti catalyst, and PTFE dispersion resin through a V-type mixer to obtain a second mixture. Age the uniformly mixed second mixture in an oven, where: the content of the extrusion aid is 15 wt%, the oven temperature during aging is 40 °C, the aging time is 12 h, the content of the coupling agent is 2 wt% (KH550), the surfactant is 1 wt% (sodium dodecylbenzenesulfonate), and the proportion of the V / Sb / Ce / Ti catalyst system is 5 wt% (V:Sb:Ce:Ti = 1:3:3:3); subject the treated mixture to pre-forming and push extrusion and calendering to obtain a PTFE composite calendered tape, where: the calendered thickness is 200 μm;

[0033] S3. Stack two layers of calendered blank film base tapes for lamination. The composite calendered base tape is subjected to a biaxial stretching process, high-temperature sintering, and cooling to make a PTFE composite film with high mechanical strength and capable of inhibiting the formation of ammonium bisulfate. Among them: the biaxial stretching process is asynchronous biaxial stretching, the temperature of the degreasing zone during stretching is 200 °C, the temperature of the stretching zone is 300 °C, the sintering temperature is 350 °C, the cooling rate during cooling is 10 °C / min, the longitudinal stretching ratio is 10, and the transverse stretching ratio is 15. The obtained PTFE composite film has an air permeability of 150 mm / s, a thickness of 10 μm, a warp breaking strength of 30.2 N, and a weft breaking strength of 25.9 N.

[0034] S4. Apply the prepared PTFE composite membrane to PTFE membrane - covered filter media. Among them: The composite filter media consists of a PTFE composite membrane and a PTFE needle - punched felt substrate. The membrane surface doped with the catalyst system is thermally bonded to the substrate, serving as the clean - gas side of the composite filter media, while the membrane surface without the attached catalyst serves as the dust - facing side, playing the role of filtering soot and protecting the catalyst from being washed away. The process parameters for the thermal bonding of the PTFE composite membrane and the substrate in the composite filter media are: temperature 370 °C, pressure between the front and rear rubber rollers and the hot roller is 0.5 MPa, spacing is 0.5 mm, and speed is 10 m / min. The air permeability of the finally prepared composite filter media is 5.3 cm / s. After 15 - day working condition simulation, the generation amount of ammonium bisulfate is 19 g.

[0035] Comparative Example 1:

[0036] A preparation method of an anti - ammonium bisulfate caking composite filter media, the preparation method includes the following steps:

[0037] S1. Mix PTFE dispersion resin and an extrusion aid (such as gasoline, aviation kerosene, naphtha, petroleum ether, etc.) through a V - type mixer to obtain mixture one. Age the uniformly mixed mixture one in an oven. Among them: the content of the extrusion aid is 15 wt%, the oven temperature during aging is 40 °C, and the aging time is 12 h; Subject the treated mixture to pre - forming, pushing, and calendering to obtain a PTFE calendered tape. Among them: the calendered thickness is 200 μm;

[0038] S2. Perform a biaxial stretching process, high - temperature sintering, and cooling on the calendered blank film base to make a PTFE membrane. Among them: the biaxial stretching process is asynchronous biaxial stretching, the temperature in the degreasing zone during stretching is 200 °C, the temperature in the stretching zone is 300 °C, the sintering temperature is 350 °C, the cooling rate during cooling is 10 °C / min, the longitudinal stretching ratio is 10, and the transverse stretching ratio is 15. The obtained PTFE composite membrane has an air permeability of 185 mm / s, a thickness of 7 μm, a warp - direction breaking strength of 10.2 N, and a weft - direction breaking strength of 8.6 N.

[0039] S3. Apply the prepared PTFE membrane to PTFE membrane - covered filter media. Among them: the composite filter media consists of a PTFE membrane and a PTFE needle - punched felt substrate. The process parameters for the thermal bonding of the PTFE membrane and the substrate in the composite filter media are: temperature 370 °C, pressure between the front and rear rubber rollers and the hot roller is 0.5 MPa, spacing is 0.5 mm, and speed is 10 m / min. The air permeability of the finally prepared composite filter media is 6.5 cm / s. After 15 - day working condition simulation, the generation amount of ammonium bisulfate is 1082 g.

[0040]

[0041] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

[0042] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and the descriptions in the specification are only used to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed.

Claims

1. A method for preparing an ammonium bisulfate resistant paste bag composite filter material, characterized in that: The preparation method comprises the following steps: S1, uniformly mixing the PTFE dispersion resin and the extrusion aid to obtain a mixture 1, aging the mixture 1 in an oven, preforming, pushing and extruding the aged mixture 1 to obtain a PTFE calendering tape; S2, mixing the coupling agent, surfactant, extrusion aid, V / Sb / Ce / Ti catalyst and PTFE dispersed resin uniformly to obtain a second mixture, aging the second mixture in an oven, and preforming, pushing and rolling the aged second mixture to obtain a PTFE composite calendering tape; S3, compounding and superimposing the PTFE calendered tape and the PTFE composite calendered tape, and subjecting the composite calendered base tape to a biaxial stretching process, high-temperature sintering and temperature reduction cooling to make a PTFE composite membrane with high mechanical strength and inhibiting the generation of ammonium bisulfate; S4. Thermally bond the surface of the PTFE composite membrane doped with the catalyst system to the PTFE needle-punched felt substrate as the clean air surface of the composite filter material, and use the surface of the PTFE composite membrane without the catalyst attached as the dust-facing surface to prepare an ammonium bisulfate-resistant paste bag composite filter material.

2. The method for preparing an ammonium bisulfate resistant paste bag composite filter material according to claim 1, characterized in that: The content of PTFE dispersed resin in the first mixture is 70-90wt%, and the content of extrusion aid is 10-30wt%. The extrusion aid is one of gasoline, aviation kerosene, naphtha and petroleum ether.

3. The method for preparing an ammonium bisulfate resistant paste bag composite filter material according to claim 1, characterized in that: The coupling agent is a silane coupling agent, specifically including γ-aminopropyltriethoxysilane, vinyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane; the surfactant is a non-ionic surfactant, specifically including fatty acid glyceride, polyoxyethylene fatty acid ester and polyoxyethylene fatty alcohol ether; the extrusion aid is one of gasoline, aviation kerosene, naphtha and petroleum ether, and in step S2, the content of the dispersed resin is 70-80% of the total addition amount, the content of the extrusion aid is 10-15% of the total addition amount, the content of the surfactant is 1-5% of the total addition amount, the content of the V / Sb / Ce / Ti catalyst is 1-5% of the total addition amount, and the content of the coupling agent is 1-5% of the total addition amount.

4. The method for preparing an ammonium bisulfate resistant paste bag composite filter material according to claim 1, characterized in that: The ratio of V:Sb:Ce:Ti in the V / Sb / Ce / Ti catalyst is 1:3:3:

3.

5. The method for preparing an ammonium bisulfate resistant paste bag composite filter material according to claim 1, characterized in that: During aging in steps S1 and S2, the temperature in the oven is 40-60° C. and the aging time is 12-24 hours.

6. The method for preparing an ammonium bisulfate resistant paste bag composite filter material according to claim 1, characterized in that: In step S3, the biaxial stretching process is asynchronous biaxial stretching or synchronous biaxial stretching, the temperature of the degreasing zone during stretching is 100-320°C, the temperature of the stretching zone is 120-350°C, the temperature during sintering is 300-450°C, the cooling rate is 5-50°C / min, the longitudinal stretching ratio is 5-20, the transverse stretching ratio is 10-20, and the air permeability of the obtained PTFE composite membrane is 100-200mm / s.

7. The method for preparing an ammonium bisulfate resistant paste bag composite filter material according to claim 1, characterized in that: The calendering thickness of the PTFE calendering belt is 100-500 μm, the calendering thickness of the PTFE composite calendering belt is 100-500 μm, and the thickness of the double-layer PTFE composite film is 5-20 μm.

8. The method for preparing an ammonium bisulfate resistant paste bag composite filter material according to claim 1, characterized in that: The temperature during heat bonding in step S4 is 320-380° C., the pressure between the front and rear rubber rollers and the hot roller is 0.1-1 MPa, the spacing is 0.08-0.6 mm, and the speed is 5-15 m / min.

9. An ammonium bisulfate resistant paste bag composite filter material prepared by the preparation method of an ammonium bisulfate resistant paste bag composite filter material according to any one of claims 1 to 8.

10. The ammonium bisulfate resistant paste bag composite filter material as claimed in claim 9 is used in the fields of cement, steel and electric power.

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