Modularized low-temperature catalytic filter bag for industrial flue gas treatment and preparation method

Abstract

The invention belongs to the technical field of flue gas treatment, and particularly relates to a modular low-temperature catalytic filter bag for industrial flue gas treatment and a preparation method. Comprising a filter cloth body and an outer frame of a grid structure, the outer frame is detachably supported on an outlet of the filter cloth body, and the filter cloth body comprises a dust removal layer, a desulfurization catalyst layer, a buffer layer and a nitrogen oxide and dioxin synergistic removal layer which are sequentially arranged from outside to inside; the dust removal layer, the desulfurization catalyst layer, the buffer layer and the nitrogen oxide and dioxin synergistic removal layer are detachably arranged on the outer frame; and gaps are formed among the desulfurization catalyst layer, the buffer layer and the nitrogen oxide and dioxin synergistic removal layer. SO2 in flue gas is captured through the desulfurization layer, a sulfur-free environment is provided for the inner nitrogen oxide and dioxin removal layer, the removal efficiency of nitrogen oxide and dioxin is remarkably improved, sulfur oxide and flue gas react and then are deposited on the buffer layer, and the problem that a catalytic filter bag is poor in water resistance and sulfur resistance under the complex flue gas condition is effectively solved.

Description

Technical Field

[0001] The invention belongs to the technical field of flue gas treatment, and in particular relates to a modular low-temperature catalytic filter bag for industrial flue gas treatment and a preparation method thereof. Background Art

[0002] In the process of industrial flue gas treatment, NOx and dioxins are the main pollutants. In industry, denitrification and dioxin removal are mainly carried out through NH3 selective catalytic reduction (NH3-SCR) and activated carbon injection technology. However, activated carbon injection only transfers gas phase dioxins to the solid phase, and cannot directly degrade dioxins, but increases the difficulty of fly ash treatment. Studies have shown that SCR catalysts have the ability to synergistically remove dioxins, and can be loaded onto dust filter bags to make catalytic filter bags to achieve integrated removal of multiple pollutants. However, in low temperature environments (such as 150-300°C), the activity and durability of traditional catalysts such as vanadium tungsten titanium catalysts are easily affected by SO2 and H2O in the flue gas, resulting in the deposition of ammonium bisulfate (NH4HSO4) on the catalyst surface, reducing the activity of the catalyst. Therefore, the development of a catalytic filter bag that is efficient and stable in low temperature environments is crucial to improving the efficiency of flue gas treatment.

[0003] To solve this problem, application number 202310474995.4 discloses a catalytic filter bag with denitration and dioxin removal effects and a preparation method thereof, comprising a breathable membrane layer, a first catalyst composite layer, a second catalyst composite layer and a third catalyst composite layer arranged sequentially from the outside to the inside, wherein the first catalyst composite layer, the second catalyst composite layer and the third catalyst composite layer are respectively fluidized onto the needle felt by the first catalyst, the second catalyst and the third catalyst. The denitration and dioxin removal performance of the catalytic filter bag is improved by sequentially designing a multi-layer catalyst.

[0004] However, due to the complex composition of industrial flue gas, the above-mentioned catalytic filter bags have poor sulfur and water resistance and are easily deactivated, resulting in low removal efficiency. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a modular low-temperature catalytic filter bag for industrial flue gas treatment and a preparation method. The problem of poor water and sulfur resistance of the catalytic filter bag under complex flue gas conditions is effectively solved. The desulfurization layer effectively captures SO2 in the flue gas, provides a sulfur-free environment for the inner layer nitrogen oxide and dioxin removal part, protects the nitrogen oxide and dioxin synergistic removal layer from poisoning, and significantly improves the removal efficiency of nitrogen oxides and dioxins. The oxidized sulfur oxides react with NH3 and H2O in the flue gas to generate NH4HSO4 and deposit on the buffer layer, which has long-term and stable working performance. The filter bag is not only simple in structure and easy to maintain, but also has high efficiency and long-lasting performance, and is particularly suitable for the treatment of complex industrial flue gas.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] One of the purposes of the present invention is to provide a modular low-temperature catalytic filter bag for industrial flue gas treatment, comprising a filter cloth body and an outer frame of a grid structure, wherein the outer frame is detachably supported on the outlet of the filter cloth body, and the filter cloth body comprises a dust removal layer, a desulfurization catalytic layer, a buffer layer and a nitrogen oxide and dioxin synergistic removal layer which are arranged in sequence from the outside to the inside, and the dust removal layer, the desulfurization catalytic layer, the buffer layer and the nitrogen oxide and dioxin synergistic removal layer can all be detachably arranged on the outer frame; wherein a gap is provided between the desulfurization catalytic layer, the buffer layer and the nitrogen oxide and dioxin synergistic removal layer; the material of the desulfurization catalytic layer is manganese oxide; the buffer material used in the buffer layer is γ-Al2O3 or ZnO; the material used in the nitrogen oxide and dioxin synergistic removal layer is an SCR catalyst.

[0008] Furthermore, the thickness of the dust removal layer, the desulfurization catalytic layer, the buffer layer and the nitrogen oxide and dioxin synergistic removal layer are all 2 mm to 4 mm, and the width of the gap is 0.5 mm to 2 mm.

[0009] Furthermore, the SCR catalyst is constructed by using TiO2 as a carrier and Fe, Mn, Ce or Er as an active ingredient, and the active ingredient is loaded on the carrier.

[0010] Furthermore, when the active components are Fe, Mn and Ce, the molar ratio of Fe, Mn, Ce and TiO2 in the SCR catalyst is 0.1:0.2:0.2:1; when the active components are Fe, Mn and Er, the molar ratio of Fe, Mn, Er and TiO2 in the SCR catalyst is 0.1:0.2:0.2:1.

[0011] Furthermore, the dust removal layer is made of ePTFE.

[0012] Furthermore, the method for preparing the desulfurization catalyst layer comprises the following steps:

[0013] Manganese oxide, a penetrant, a binder and a solvent are mixed to form a precursor slurry, which is impregnated on a PTFE substrate, rolled twice, and shaped at 250°C, and then calcined at 270°C to obtain a desulfurization catalytic layer; based on the total mass of the precursor slurry, the amount of manganese oxide is 20wt.% to 50wt.%, the amount of the penetrant is 1wt.% to 5wt.%, the amount of the binder is 5wt.% to 20wt.%, and the remainder is solvent, which is 100% in total, and the calcination time is 2h.

[0014] Furthermore, the method for preparing the buffer layer comprises the following steps:

[0015] γ-Al2O3 or ZnO, a penetrant, a binder and a solvent are mixed to form a precursor slurry, which is impregnated on a PTFE substrate, rolled twice, and shaped at 250°C, and then calcined for a second time at 270°C to obtain a buffer layer; based on the total mass of the precursor slurry, the amount of γ-Al2O3 or ZnO is 40wt.%~70wt.%, the amount of the penetrant is 1wt.%~5wt.%, the amount of the binder is 5wt.%~20wt.%, and the remainder is solvent, totaling 100%, and the calcination time is 2h.

[0016] Furthermore, the method for preparing the nitrogen oxide and dioxin synergistic removal layer comprises the following steps:

[0017] An SCR catalyst, a penetrant, a binder and a solvent are mixed to form a precursor slurry, which is impregnated on a PTFE substrate, rolled twice, and shaped at 250°C, and then calcined for the third time at 270°C to obtain a nitrogen oxide and dioxin synergistic removal layer; based on the total mass of the precursor slurry, the amount of the SCR catalyst is 20wt.% to 50wt.%, the amount of the penetrant is 1wt.% to 5wt.%, the amount of the binder is 5wt.% to 20wt.%, and the remainder is solvent, which is 100% in total, and the calcination time is 2h.

[0018] Furthermore, the penetrant is a PTFE concentrated dispersion with a mass concentration of 60 wt.%, the binder is silica sol, and the solvent is water.

[0019] The second object of the present invention is to provide a method for preparing the modular low-temperature catalytic filter bag for industrial flue gas treatment, comprising the following steps:

[0020] The desulfurization catalytic layer is adhered to the dust removal layer, and then the desulfurization catalytic layer, the buffer layer and the nitrogen oxide and dioxin synergistic removal layer are detachably fixed on the outer frame in turn to obtain a modular low-temperature catalytic filter bag, wherein the buffer layer is fixed on the outer frame by a quick locking structure.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The low-temperature catalytic filter bag provided by the present invention removes particulate matter through a dust removal layer. The flue gas after dust removal enters a desulfurization layer. The desulfurization layer has manganese oxide as an active component and has excellent low-temperature activity. It can react with SO2 in the flue gas to consume the residual trace SO2 in the flue gas, but it itself will not be sulfated and will not affect the desulfurization effect. It provides a sulfur-free environment for the inner layer nitrogen oxide and dioxin removal part, significantly improving the nitrogen oxide and dioxin removal rate. The loaded catalyst is not easy to deactivate and has high stability. The oxidized sulfur oxide reacts with NH3 and H2O in the flue gas to generate NH4HSO4 and deposit on the buffer layer, effectively solving the problem of poor water and sulfur resistance of the catalytic filter bag under complex flue gas conditions.

[0023] (2) The present invention fixes the buffer layer on the outer frame through a quick locking structure. After the buffer layer is replaced, it can be regenerated through heat treatment or cleaning technology. The regenerated buffer layer still has good adsorption performance. The modular design, especially the independent replacement function of the buffer layer, makes the filter bag maintenance more convenient and greatly reduces the operating cost of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the modular low-temperature catalytic filter bag for industrial flue gas treatment of the present invention.

[0025] Figure 2 The schematic diagram of the top view of the modular low-temperature catalytic filter bag for industrial flue gas treatment of the present invention.

[0026] Figure 3 This is a schematic diagram of the system structure of the catalytic filter bag of the present invention for industrial flue gas treatment.

[0027] Figure 4 The present invention is a schematic diagram of the process flow of using the low-temperature catalytic filter bag for industrial flue gas treatment. Description of the drawings:

[0029] 1. Dust removal layer, 2. Desulfurization catalytic layer, 3. Buffer layer, 4. Nitrogen oxide and dioxin synergistic removal layer.

[0030] 1-1, simulated flue gas components, 1-2, mixer, 1-3, fly ash feeder, 1-4, temperature controller, 1-5, catalytic filter bag, 1-6, dust collector, 1-7, cooler, 1-8, induced draft fan, 1-9, NH3 conveyor. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Certain words are used in the present invention to refer to specific components. Those skilled in the art should understand that technicians will use different nouns to refer to the same component. The present invention does not distinguish between components by the difference in nouns, but by the difference in the functions of the components. As mentioned throughout the specification and claims, "including" is an open term and should be understood as "including but not limited to".

[0033] Prior art, such as application number 202310474995.4, discloses a catalytic filter bag with denitration and dioxin removal effects and a preparation method thereof, comprising a breathable membrane layer, a first catalyst composite layer, a second catalyst composite layer and a third catalyst composite layer arranged sequentially from the outside to the inside, wherein the first catalyst composite layer, the second catalyst composite layer and the third catalyst composite layer are respectively fluidized onto the needle felt by the first catalyst, the second catalyst and the third catalyst. The denitration and dioxin removal performance of the catalytic filter bag is improved by sequentially designing a multi-layer catalyst.

[0034] However, due to the complex composition of industrial flue gas, the above-mentioned catalytic filter bags have poor sulfur and water resistance and are easily deactivated, resulting in low removal efficiency.

[0035] Based on the above problems, the present invention provides a modular low-temperature catalytic filter bag for industrial flue gas treatment, such as Figure 1 and Figure 2 As shown, it includes a filter cloth body and an outer frame of a grid structure, wherein the outer frame is detachably supported on the outlet of the filter cloth body, and the filter cloth body includes a dust removal layer 1, a desulfurization catalytic layer 2, a buffer layer 3 and a nitrogen oxide and dioxin synergistic removal layer 4 which are arranged in sequence from the outside to the inside, and the dust removal layer 1, the desulfurization catalytic layer 2, the buffer layer 3 and the nitrogen oxide and dioxin synergistic removal layer 4 can all be detachably arranged on the outer frame; wherein a gap is provided between the desulfurization catalytic layer 2, the buffer layer 3 and the nitrogen oxide and dioxin synergistic removal layer 4.

[0036] The material of the desulfurization catalyst layer 2 is manganese oxide.

[0037] The buffer material used in the buffer layer 3 is γ-Al2O3 or ZnO.

[0038] The material used for the nitrogen oxide and dioxin synergistic removal layer 4 is SCR catalyst.

[0039] Among them, the present invention removes particulate matter through the dust removal layer 1, and the flue gas after dust removal enters the desulfurization layer 2. The desulfurization layer is attached with manganese oxide as an active component with excellent low-temperature activity, which can react with SO2 in the flue gas and consume the residual trace SO2 in the flue gas, but it itself will not be sulfated and will not affect the desulfurization effect. It provides a sulfur-free environment for the inner layer nitrogen oxide and dioxin removal part, significantly improves the nitrogen oxide and dioxin removal rate, and the loaded catalyst is not easy to deactivate and has high stability. The oxidized sulfur oxides react with NH3 and H2O in the flue gas to generate NH4HSO4 and deposit on the buffer layer 3.

[0040] The buffer layer 3 can adsorb NH4HSO4, and the nitrogen oxide and dioxin synergistic removal layer 4 is used to catalyze the reduction of nitrogen oxides and catalytic degradation of dioxins. The nitrogen oxide and dioxin synergistic removal layer 4 mainly has a synergistic effect between multiple metals to enhance the stability of the catalyst, and has excellent water resistance, so that it exhibits better activity when water vapor exists.

[0041] There is a gap between the desulfurization catalytic layer 2, the buffer layer 3 and the nitrogen oxide and dioxin synergistic removal layer 4, which is used for the convenient disassembly of the buffer layer on the one hand, and on the other hand, to capture the sulfur oxides (mainly SO3) generated by the desulfurization layer. If no gap is left, the generated ammonium bisulfate is likely to be deposited in the desulfurization layer, causing poisoning of the SCR catalyst and reducing the catalytic effect of the SCR catalyst.

[0042] In a specific embodiment, the SCR catalyst is constructed by using TiO2 as a carrier and Fe, Mn, Ce or Er as an active ingredient, and the active ingredient is loaded on the carrier. When the active ingredients are Fe, Mn and Ce, the molar ratio of Fe, Mn, Ce and TiO2 in the SCR catalyst is 0.1:0.2:0.2:1; when the active ingredients are Fe, Mn and Er, the molar ratio of Fe, Mn, Er and TiO2 in the SCR catalyst is 0.1:0.2:0.2:1.

[0043] Among them, when the active components are Fe, Mn and Ce, the SCR catalyst is a Fe-Mn-Ce / TiO2 composite catalyst, and when the active components are Fe, Mn and Er, the SCR catalyst is a Fe-Mn-Er / TiO2 composite catalyst. Rare earth elements Ce or Er are introduced into the Fe-Mn-Ce / TiO2 composite catalyst and the Fe-Mn-Er / TiO2 composite catalyst. On the one hand, the specific surface area of ​​the catalyst and the dispersion of the metal are increased, which helps to form more active sites, thereby improving the catalytic performance; the reducibility of the catalyst is improved, the temperature of the reduction peak is reduced, the active substance is more easily reduced, and the migration ability of the surface oxygen is improved; on the other hand, the number of Lewis acid and Bronsted acid sites on the catalyst surface is significantly increased, which is crucial for the adsorption of NH3 and the SCR reaction. Er doping promotes the generation of intermediates (such as -NH2 species and adsorbed NO2), which help to improve the activity of the SCR reaction. In addition, the rare earth elements in the SCR catalyst have good oxygen storage capacity, and the combination of the two with manganese oxide can further improve the catalytic performance, and the introduction of Fe and Er can increase the specific surface area of ​​the catalyst, and the latter can improve the sulfur resistance and water resistance. In addition, the present invention does not limit the specific preparation method of the Fe-Mn-Ce / TiO2 composite catalyst and the Fe-Mn-Er / TiO2 composite catalyst, as long as it is prepared using existing technologies, such as impregnation method, coprecipitation method or sol-gel method.

[0044] In a specific embodiment, the dust removal layer 1 is made of ePTFE.

[0045] In a specific embodiment, the method for preparing the desulfurization catalytic layer 2 comprises the following steps:

[0046] Manganese oxide, a penetrant, a binder and a solvent are mixed to form a precursor slurry, which is impregnated on a PTFE substrate, and rolled twice, and shaped at 250° C., and then calcined at 270° C. to obtain a desulfurization catalyst layer 2;

[0047] Based on the total mass of the precursor slurry, the amount of manganese oxide is 20wt.% to 50wt.%, the amount of penetrant is 1wt.% to 5wt.%, the amount of binder is 5wt.% to 20wt.%, and the remainder is solvent, which totals 100%. The calcination time is 2h.

[0048] In a specific embodiment, the method for preparing the buffer layer 3 comprises the following steps:

[0049] γ-Al2O3 or ZnO, a penetrant, a binder and a solvent are mixed to form a precursor slurry, which is impregnated on a PTFE substrate, rolled twice, and shaped at 250°C, and then calcined for the second time at 270°C to obtain a buffer layer 3.

[0050] Based on the total mass of the precursor slurry, the amount of γ-Al2O3 or ZnO is 40wt.%~70wt.%, the amount of the penetrant is 1wt.%~5wt.%, the amount of the binder is 5wt.%~20wt.%, and the balance is solvent, totaling 100%, and the calcination time is 2h.

[0051] In a specific embodiment, the method for preparing the nitrogen oxide and dioxin synergistic removal layer 4 comprises the following steps:

[0052] The SCR catalyst, penetrant, binder and solvent are mixed to form a precursor slurry, which is impregnated on a PTFE substrate, rolled twice, and shaped at 250° C., and then calcined for the third time at 270° C. to obtain a nitrogen oxide and dioxin synergistic removal layer 4.

[0053] Based on the total mass of the precursor slurry, the amount of SCR catalyst is 20wt.% to 50wt.%, the amount of penetrant is 1wt.% to 5wt.%, the amount of binder is 5wt.% to 20wt.%, and the remainder is solvent, which is 100% in total. The calcination time is 2h.

[0054] In a specific embodiment, the penetrant is a PTFE concentrated dispersion with a mass concentration of 60 wt.%, the binder is silica sol, and the solvent is water.

[0055] On the other hand, the present invention provides a method for preparing the modular low-temperature catalytic filter bag for industrial flue gas treatment, comprising the following steps:

[0056] The desulfurization catalytic layer 2 is adhered to the dust removal layer 1, and then the desulfurization catalytic layer 2, the buffer layer 3 and the nitrogen oxide and dioxin synergistic removal layer 4 are detachably fixed on the outer frame in sequence to obtain a modular low-temperature catalytic filter bag, wherein the buffer layer 3 is fixed on the outer frame by a quick locking structure.

[0057] The mixed layer formed by the desulfurization catalytic layer 2 and the dust removal layer 1, the desulfurization catalytic layer 2, the buffer layer 3 and the nitrogen oxide and dioxin synergistic removal layer 4 are fixed on the outer frame in an existing conventional detachable manner, such as bonding connection, snap connection, etc. Since the buffer layer 3 is replaced frequently, the buffer layer 3 is an independent replaceable module, fixed to the outer frame by a quick locking structure, using buttons, zippers, magnetic locks, snaps or other quick locking devices. After the buffer layer is replaced, it can be regenerated by heat treatment or cleaning technology, and the regenerated buffer layer still has good adsorption performance. Through modular design, especially the independent replacement function of the buffer layer, the filter bag maintenance is more convenient, which greatly reduces the operating cost of the system.

[0058] The invention is further described below through specific examples.

[0059] Example 1

[0060] The present invention provides a modular low-temperature catalytic filter bag for industrial flue gas treatment, such as Figure 1 As shown, it includes a filter cloth body and an outer frame of a grid structure, the outer frame is detachably supported on the outlet of the filter cloth body, the filter cloth body includes a dust removal layer 1, a desulfurization catalytic layer 2, a buffer layer 3 and a nitrogen oxide and dioxin synergistic removal layer 4 arranged in sequence from the outside to the inside, and the dust removal layer 1, the desulfurization catalytic layer 2, the buffer layer 3 and the nitrogen oxide and dioxin synergistic removal layer 4 can be detachably arranged on the outer frame; wherein a gap is provided between the desulfurization catalytic layer 2, the buffer layer 3 and the nitrogen oxide and dioxin synergistic removal layer 4. Among them, an ash hopper is also provided below the filter cloth body.

[0061] The material of the desulfurization catalyst layer 2 is manganese oxide, and the manganese oxide is 50% manganese nitrate solution.

[0062] The buffer material used in the buffer layer 3 is γ-Al2O3.

[0063] The material used in the NOx and dioxin synergistic removal layer 4 is SCR catalyst, which is FeMnCe / TiO 2， The molar ratio of Fe, Mn, Ce and TiO2 in the FeMnCe / TiO2 catalyst is 0.1:0.2:0.2:1.

[0064] The thickness of the dust removal layer, the desulfurization catalytic layer, the buffer layer and the nitrogen oxide and dioxin synergistic removal layer are all 3 mm, and the width of the gap is 1 mm.

[0065] The dust removal layer 1 is made of ePTFE.

[0066] The method for preparing the desulfurization catalyst layer 2 comprises the following steps:

[0067] A 50% manganese nitrate solution, a 60wt.% PTFE concentrated dispersion, a silica sol and water are mixed to form a precursor slurry, which is impregnated on a PTFE substrate and subjected to two impregnation rolling operations, wherein the pressure of the latter impregnation rolling operation is greater than that of the former, and the mixture is shaped at 250°C, and then calcined at 270°C for 2h to obtain a desulfurization catalytic layer 2; based on the total mass of the precursor slurry, the amount of manganese oxide is 30wt.%, the amount of PTFE concentrated dispersion is 3wt.%, the amount of silica sol is 10wt.%, and the remainder is water, which is 100% in total.

[0068] The method for preparing the buffer layer 3 comprises the following steps:

[0069] γ-Al2O3, PTFE concentrated dispersion with a mass concentration of 60wt.%, silica sol and water are mixed to form a precursor slurry, which is impregnated on a PTFE substrate and subjected to two impregnation rolling processes, wherein the pressure of the latter impregnation rolling process is greater than that of the former, and the product is shaped at 250°C, and then calcined at 270°C for 2h to obtain a buffer layer 3; based on the total mass of the precursor slurry, the amount of γ-Al2O3 is 50wt.%, the amount of PTFE concentrated dispersion is 3wt.%, the amount of silica sol is 10wt.%, and the remainder is solvent, which is 100% in total.

[0070] The preparation method of the nitrogen oxide and dioxin synergistic removal layer 4 comprises the following steps:

[0071] The SCR catalyst, a PTFE concentrated dispersion with a mass concentration of 60wt.%, silica sol and water are mixed to form a precursor slurry, which is impregnated on a PTFE substrate and rolled twice, wherein the pressure of the latter rolling is increased compared with the previous rolling, and the slurry is fixed at 250°C, and then calcined at 270°C for 2h to obtain a nitrogen oxide and dioxin synergistic removal layer 4;

[0072] Based on the total mass of the precursor slurry, the amount of the SCR catalyst is 30 wt.%, the amount of the PTFE concentrated dispersion is 3 wt.%, the amount of the silica sol is 10 wt.%, and the remainder is the solvent, which is 100% in total.

[0073] The method for preparing the modular low-temperature catalytic filter bag for industrial flue gas treatment comprises the following steps:

[0074] The desulfurization catalytic layer 2 is adhered to the dust removal layer 1, and then the desulfurization catalytic layer 2, the buffer layer 3 and the nitrogen oxide and dioxin synergistic removal layer 4 are detachably fixed on the outer frame in sequence, wherein the mixed layer formed by the desulfurization catalytic layer 2 and the dust removal layer 1, the desulfurization catalytic layer 2 and the nitrogen oxide and dioxin synergistic removal layer 4 are arranged on the outer frame by means of snap connection, and the buffer layer 3 is quickly fixed on the outer frame by means of magnetic lock, so as to obtain a modular low-temperature catalytic filter bag.

[0075] Example 2

[0076] The present invention provides a modular low-temperature catalytic filter bag for industrial flue gas treatment, such as Figure 1As shown, it includes a filter cloth body and an outer frame of a grid structure, the outer frame is detachably supported on the outlet of the filter cloth body, the filter cloth body includes a dust removal layer 1, a desulfurization catalytic layer 2, a buffer layer 3 and a nitrogen oxide and dioxin synergistic removal layer 4 arranged in sequence from the outside to the inside, and the dust removal layer 1, the desulfurization catalytic layer 2, the buffer layer 3 and the nitrogen oxide and dioxin synergistic removal layer 4 can be detachably arranged on the outer frame; wherein a gap is provided between the desulfurization catalytic layer 2, the buffer layer 3 and the nitrogen oxide and dioxin synergistic removal layer 4. Among them, an ash hopper is also provided below the filter cloth body.

[0077] The material of the desulfurization catalyst layer 2 is manganese oxide, and the manganese oxide is 50% manganese nitrate solution.

[0078] The buffer material used in the buffer layer 3 is γ-Al2O3.

[0079] The material used in the NOx and dioxin synergistic removal layer 4 is SCR catalyst, which is FeMnCe / TiO 2， The molar ratio of Fe, Mn, Ce and TiO2 in the FeMnCe / TiO2 catalyst is 0.1:0.2:0.2:1.

[0080] The thickness of the dust removal layer, the desulfurization catalytic layer, the buffer layer and the nitrogen oxide and dioxin synergistic removal layer are all 4 mm, and the width of the gap is 2 mm.

[0081] The dust removal layer 1 is made of ePTFE.

[0082] The method for preparing the desulfurization catalyst layer 2 comprises the following steps:

[0083] A 50% manganese nitrate solution, a 60wt.% PTFE concentrated dispersion, a silica sol and water are mixed to form a precursor slurry, which is impregnated on a PTFE substrate and subjected to two impregnation rolling operations, wherein the pressure of the latter impregnation rolling operation is greater than that of the former, and the mixture is shaped at 250°C, and then calcined at 270°C for 2h to obtain a desulfurization catalytic layer 2; based on the total mass of the precursor slurry, the amount of manganese oxide is 40wt.%, the amount of PTFE concentrated dispersion is 4wt.%, the amount of silica sol is 10wt.%, and the remainder is water, which is 100% in total.

[0084] The method for preparing the buffer layer 3 comprises the following steps:

[0085] γ-Al2O3, PTFE concentrated dispersion with a mass concentration of 60wt.%, silica sol and water are mixed to form a precursor slurry, which is impregnated on a PTFE substrate and subjected to two impregnation rolling processes, wherein the pressure of the latter impregnation rolling process is greater than that of the former, and the product is shaped at 250°C, and then calcined at 270°C for 2h to obtain a buffer layer 3; based on the total mass of the precursor slurry, the amount of γ-Al2O3 is 40wt.%, the amount of PTFE concentrated dispersion is 4wt.%, the amount of silica sol is 10wt.%, and the remainder is solvent, which is 100% in total.

[0086] The preparation method of the nitrogen oxide and dioxin synergistic removal layer 4 comprises the following steps:

[0087] The SCR catalyst, a PTFE concentrated dispersion with a mass concentration of 60wt.%, silica sol and water are mixed to form a precursor slurry, which is impregnated on a PTFE substrate and rolled twice, wherein the pressure of the latter rolling is increased compared with the previous rolling, and the slurry is fixed at 250°C, and then calcined at 270°C for 2h to obtain a nitrogen oxide and dioxin synergistic removal layer 4;

[0088] Based on the total mass of the precursor slurry, the amount of the SCR catalyst is 40wt.%, the amount of the PTFE concentrated dispersion is 4wt.%, the amount of the silica sol is 10wt.%, and the remainder is the solvent, which is 100% in total.

[0089] The method for preparing the modular low-temperature catalytic filter bag for industrial flue gas treatment comprises the following steps:

[0090] The desulfurization catalytic layer 2 is adhered to the dust removal layer 1, and then the desulfurization catalytic layer 2, the buffer layer 3 and the nitrogen oxide and dioxin synergistic removal layer 4 are detachably fixed on the outer frame in sequence, wherein the mixed layer formed by the desulfurization catalytic layer 2 and the dust removal layer 1, the desulfurization catalytic layer 2 and the nitrogen oxide and dioxin synergistic removal layer 4 are arranged on the outer frame by means of snap connection, and the buffer layer 3 is quickly fixed on the outer frame by means of magnetic lock, so as to obtain a modular low-temperature catalytic filter bag.

[0091] Example 3

[0092] The present invention provides a modular low-temperature catalytic filter bag for industrial flue gas treatment, such as Figure 1As shown, it includes a filter cloth body and an outer frame of a grid structure, the outer frame is detachably supported on the outlet of the filter cloth body, the filter cloth body includes a dust removal layer 1, a desulfurization catalytic layer 2, a buffer layer 3 and a nitrogen oxide and dioxin synergistic removal layer 4 arranged in sequence from the outside to the inside, and the dust removal layer 1, the desulfurization catalytic layer 2, the buffer layer 3 and the nitrogen oxide and dioxin synergistic removal layer 4 can be detachably arranged on the outer frame; wherein a gap is provided between the desulfurization catalytic layer 2, the buffer layer 3 and the nitrogen oxide and dioxin synergistic removal layer 4. Among them, an ash hopper is also provided below the filter cloth body.

[0093] The material of the desulfurization catalyst layer 2 is manganese oxide, and the manganese oxide is 50% manganese nitrate solution.

[0094] The buffer material used in the buffer layer 3 is γ-Al2O3.

[0095] The material used in the NOx and dioxin synergistic removal layer 4 is SCR catalyst, which is FeMnEr / TiO 2， The molar ratio of Fe, Mn, Er and TiO2 in the FeMnEr / TiO2 catalyst is 0.1:0.2:0.2:1.

[0096] The thickness of the dust removal layer, the desulfurization catalytic layer, the buffer layer and the nitrogen oxide and dioxin synergistic removal layer are all 3 mm, and the width of the gap is 1 mm.

[0097] The dust removal layer 1 is made of ePTFE.

[0098] The method for preparing the desulfurization catalyst layer 2 comprises the following steps:

[0099] A 50% manganese nitrate solution, a 60wt.% PTFE concentrated dispersion, a silica sol and water are mixed to form a precursor slurry, which is impregnated on a PTFE substrate and subjected to two impregnation rolling operations, wherein the pressure of the latter impregnation rolling operation is greater than that of the former, and the mixture is shaped at 250°C, and then calcined at 270°C for 2h to obtain a desulfurization catalytic layer 2; based on the total mass of the precursor slurry, the amount of manganese oxide is 30wt.%, the amount of PTFE concentrated dispersion is 3wt.%, the amount of silica sol is 10wt.%, and the remainder is water, which is 100% in total.

[0100] The method for preparing the buffer layer 3 comprises the following steps:

[0101] γ-Al2O3, PTFE concentrated dispersion with a mass concentration of 60wt.%, silica sol and water are mixed to form a precursor slurry, which is impregnated on a PTFE substrate and subjected to two impregnation rolling processes, wherein the pressure of the latter impregnation rolling process is greater than that of the former, and the product is shaped at 250°C, and then calcined at 270°C for 2h to obtain a buffer layer 3; based on the total mass of the precursor slurry, the amount of γ-Al2O3 is 50wt.%, the amount of PTFE concentrated dispersion is 3wt.%, the amount of silica sol is 10wt.%, and the remainder is solvent, which is 100% in total.

[0102] The preparation method of the nitrogen oxide and dioxin synergistic removal layer 4 comprises the following steps:

[0103] The SCR catalyst, a PTFE concentrated dispersion with a mass concentration of 60wt.%, silica sol and water are mixed to form a precursor slurry, which is impregnated on a PTFE substrate and rolled twice, wherein the pressure of the latter rolling is increased compared with the previous rolling, and the slurry is fixed at 250°C, and then calcined at 270°C for 2h to obtain a nitrogen oxide and dioxin synergistic removal layer 4;

[0104] Based on the total mass of the precursor slurry, the amount of the SCR catalyst is 30 wt.%, the amount of the PTFE concentrated dispersion is 3 wt.%, the amount of the silica sol is 10 wt.%, and the remainder is the solvent, which is 100% in total.

[0105] The method for preparing the modular low-temperature catalytic filter bag for industrial flue gas treatment comprises the following steps:

[0106] The desulfurization catalytic layer 2 is adhered to the dust removal layer 1, and then the desulfurization catalytic layer 2, the buffer layer 3 and the nitrogen oxide and dioxin synergistic removal layer 4 are detachably fixed on the outer frame in sequence, wherein the mixed layer formed by the desulfurization catalytic layer 2 and the dust removal layer 1, the desulfurization catalytic layer 2 and the nitrogen oxide and dioxin synergistic removal layer 4 are arranged on the outer frame by means of snap connection, and the buffer layer 3 is quickly fixed on the outer frame by means of magnetic lock, so as to obtain a modular low-temperature catalytic filter bag.

[0107] The catalytic filter bag prepared in Example 1 is used for industrial flue gas treatment, such as Figure 3 As shown, the industrial flue gas treatment system is mainly composed of a simulated flue gas generation system and a dust removal-denitrification-dioxin removal system.

[0108] Among them, the simulated flue gas generation system simulates the flue gas component 1-1, the mixer 1-2 and the fly ash feeder 1-3, wherein the mixer 1-2 is also provided with a temperature controller 1-4, and the air of the required flow rate is heated by the temperature controller 1-4 as a carrier gas. The simulated flue gas component 1-1 includes industrial flue gases such as water vapor, HCl, SO2, NO and dioxins, wherein the water vapor is passed through the water vapor generator to achieve the required flue gas humidity, the fly ash feeder 1-3 achieves the required dust concentration, and the dioxin is used to generate a certain amount of dioxin through the dioxin generator to test the removal performance of the prepared catalytic filter bag.

[0109] The dust removal-denitrification-dioxin removal system includes a catalytic filter bag 1-5, a dust collector 1-6, a cooler 1-7 and an induced draft fan 1-8. The dust collector 1-6 is provided at the lower end of the ash hopper of the catalytic filter bag 1-5, and the outlet is connected to the cooler 1-7 through an air outlet duct. The cooler 1-7 is connected to the induced draft fan 1-8. A sampling point is provided on the air outlet duct for measuring the flue gas components before and after the reaction.

[0110] The mixer 1-2 is connected to the catalytic filter bag through a delivery pipeline, and an NH3 delivery device 1-9 is also provided on the delivery pipeline for delivering NH3 to the flue gas. Along the flow direction of the flue gas, a flue gas sampling area is provided behind the connection end of the NH3 delivery device 1-9 and the delivery pipeline for checking the flue gas composition. Figure 4 As shown, the catalytic filter bag undergoes a catalytic reduction reaction with nitrogen oxides and dioxins in the flue gas, thereby achieving synergistic removal of nitrogen oxides and dioxins.

[0111] The test conditions are: smoke flow rate is 25Nm 3 / h, dioxin concentration is 10ng I-TEQ / Nm 3 , SO2 concentration is 40Nm 3 / h, HCl concentration is 35Nm 3 / h, dust concentration is 10g / Nm 3 , NO x Concentration is 350mg / Nm 3 , moisture content is 15% (volume ratio), ammonia nitrogen ratio is 1.0 (volume ratio), test temperature range is 130-210℃, flue gas temperature is 150℃, filtration wind speed: 0.75m / min (filter bag size). The results are shown in Table 1.

[0112] Table 1 Results of sulfur oxide, nitrogen oxide and dioxin removal and dust removal

[0113]

[0114]

[0115] As shown in Table 1, within the temperature range of 130℃~210℃, the desulfurization rate is above 99%, indicating that the desulfurization layer has basically removed SO2, eliminating the toxic effect of SO2 on the synergistic removal layer of nitrogen oxides and dioxins, making the denitrification efficiency and dioxin removal efficiency stable at above 95% and 92% respectively, and the removal efficiency is also increasing with the increase of temperature. Under low temperature conditions, efficient synergistic removal of nitrogen oxides and dioxins can be achieved. In addition, it can be seen from Table 1 that the prepared catalytic filter bag also has extremely high dust filtration capacity, realizing the integrated removal of dust removal-denitrification-dioxin removal.

[0116] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0117] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A modular low-temperature catalytic filter bag for industrial flue gas treatment, characterized in that: The invention comprises a filter cloth body and an outer frame of a grid structure, wherein the outer frame is detachably supported on the outlet of the filter cloth body, and the filter cloth body comprises a dust removal layer (1), a desulfurization catalytic layer (2), a buffer layer (3) and a nitrogen oxide and dioxin synergistic removal layer (4) which are arranged in sequence from the outside to the inside, and the dust removal layer (1), the desulfurization catalytic layer (2), the buffer layer (3) and the nitrogen oxide and dioxin synergistic removal layer (4) are all detachably arranged on the outer frame; wherein a gap is provided between the desulfurization catalytic layer (2), the buffer layer (3) and the nitrogen oxide and dioxin synergistic removal layer (4); The material of the desulfurization catalytic layer (2) is manganese oxide; The buffer material used in the buffer layer (3) is γ-Al2O3 or ZnO; The material used for the nitrogen oxide and dioxin synergistic removal layer (4) is an SCR catalyst.

2. The modular low-temperature catalytic filter bag for industrial flue gas treatment according to claim 1 is characterized in that: The thickness of the dust removal layer (1), the desulfurization catalytic layer (2), the buffer layer (3) and the nitrogen oxide and dioxin synergistic removal layer (4) are all 2 mm to 4 mm, and the width of the gap is 0.5 mm to 2 mm.

3. The modular low-temperature catalytic filter bag for industrial flue gas treatment according to claim 1 is characterized in that: The SCR catalyst is constructed by using TiO2 as a carrier and Fe, Mn, Ce or Er as an active component, and the active component is loaded on the carrier.

4. The modular low-temperature catalytic filter bag for industrial flue gas treatment according to claim 2 is characterized in that: When the active components are Fe, Mn and Ce, the molar ratio of Fe, Mn, Ce and TiO2 in the SCR catalyst is 0.1:0.2:0.2:1; when the active components are Fe, Mn and Er, the molar ratio of Fe, Mn, Er and TiO2 in the SCR catalyst is 0.1:0.2:0.2:

1.

5. The modular low-temperature catalytic filter bag for industrial flue gas treatment according to claim 1, characterized in that: The dust removal layer (1) is made of ePTFE.

6. The modular low-temperature catalytic filter bag for industrial flue gas treatment according to claim 1, characterized in that: The method for preparing the desulfurization catalytic layer (2) comprises the following steps: Mixing manganese oxide, a penetrant, a binder and a solvent to form a precursor slurry, impregnating the PTFE substrate, performing two dip rolling operations, and shaping the slurry at 250° C., and then calcining the slurry at 270° C. to obtain a desulfurization catalyst layer (2); Based on the total mass of the precursor slurry, the amount of manganese oxide is 20wt.% to 50wt.%, the amount of penetrant is 1wt.% to 5wt.%, the amount of binder is 5wt.% to 20wt.%, and the remainder is solvent, which totals 100%. The calcination time is 2h.

7. The modular low-temperature catalytic filter bag for industrial flue gas treatment according to claim 6, characterized in that: The method for preparing the buffer layer (3) comprises the following steps: Mixing γ-Al2O3 or ZnO, a penetrant, a binder and a solvent to form a precursor slurry, impregnating the PTFE substrate, performing two impregnation rolls, and shaping at 250°C, and then calcining the buffer layer (3) for the second time at 270°C; Based on the total mass of the precursor slurry, the amount of γ-Al2O3 or ZnO is 40wt.%~70wt.%, the amount of the penetrant is 1wt.%~5wt.%, the amount of the binder is 5wt.%~20wt.%, and the balance is solvent, totaling 100%, and the calcination time is 2h.

8. The modular low-temperature catalytic filter bag for industrial flue gas treatment according to claim 7, characterized in that: The method for preparing the nitrogen oxide and dioxin synergistic removal layer (4) comprises the following steps: The SCR catalyst, the penetrant, the binder and the solvent are mixed to form a precursor slurry, which is impregnated on a PTFE substrate, and rolled twice, and shaped at 250° C., and then calcined for the third time at 270° C. to obtain a nitrogen oxide and dioxin synergistic removal layer (4); Based on the total mass of the precursor slurry, the amount of SCR catalyst is 20wt.% to 50wt.%, the amount of penetrant is 1wt.% to 5wt.%, the amount of binder is 5wt.% to 20wt.%, and the remainder is solvent, which is 100% in total. The calcination time is 2h.

9. The modular low-temperature catalytic filter bag for industrial flue gas treatment according to claim 8, characterized in that: The penetrant is a PTFE concentrated dispersion with a mass concentration of 60wt.%, the binder is silica sol, and the solvent is water.

10. A method for preparing a modular low-temperature catalytic filter bag for industrial flue gas treatment according to any one of claims 1 to 9, characterized in that: The following steps are involved: The desulfurization catalytic layer (2) is adhered to the dust removal layer (1), and then the desulfurization catalytic layer (2), the buffer layer (3) and the nitrogen oxide and dioxin synergistic removal layer (4) are detachably fixed on the outer frame in sequence, thereby obtaining a modular low-temperature catalytic filter bag, wherein the buffer layer (3) is fixed on the outer frame by a quick locking structure.

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