KR100394849B1 - Catalytic Non-woven Fabric Filters used for a Temperature Range of 150∼250℃ and Methods for Applying Catalysts to Non-woven Fabric - Google Patents

Abstract

The present invention is a catalyst filter that can remove nitrogen oxides and fine dust at the same time by coating a low-temperature catalyst applicable to the process of discharging the exhaust gas of about 150 ~ 250 ℃ to the filter medium to be used as a filter bag of the dry dust collector and its production It is about a method.

In the present invention, a filter was prepared by applying a catalyst for removing nitrogen oxide, wherein the filter medium is polytetrafluoroethylene (PTFE), meta-aramid fiber, polyamide fiber, polyimide fiber, or the like. This was used.

In the production of the catalyst filter, the catalyst in the slurry state is evenly sprayed on the filter medium by the spray method, coated, dried, and then cured by putting it in an oven for about 4-6 hours at a temperature range of 150 to 250 ° C. Melted, impregnated the filter, taken out, and cured, and the catalyst and the fiber were mixed to produce a felt through a carding process and a needle punching process. In addition, in order to prevent the poisoning of the catalyst by dust, a porous membrane was formed on the surface of the filter to which dust was attached to perform surface filtration by PTFE foam coating method.

Description

Mid- and low-temperature catalyst filter and method for manufacturing the same {Catalytic Non-woven Fabric Filters used for a Temperature Range of 150-250 ° C and Methods for Applying Catalysts to Non-woven Fabric}

The present invention is a catalyst filter that can remove nitrogen oxides and fine dust at the same time by coating a low-temperature catalyst applicable to the process of discharging the exhaust gas of about 150 ~ 250 ℃ to the filter medium to be used as a filter bag of the dry dust collector and its production It is about a method.

Nitrogen oxides are inevitably generated during the combustion process of coal, automobile fuel, and waste incineration, and are represented by NO and NO ₂ , and are classified into thermal NOx, fuel NOx, and prompt NOx according to the generation method. Thermal NOx is produced by oxidizing nitrogen in the combustion air by releasing oxygen in the combustion air at a high temperature, which is generated at a very high temperature of 1300 ° C. Fuel NOx is produced by oxidizing nitrogen contained in fuel during combustion process, but it is not influenced by combustion temperature, but its concentration changes according to oxygen concentration. Prompt NOx is produced by reacting hydrocarbon groups in fuel with nitrogen in combustion air, but it is known that it is not important.

Techniques for reducing the nitrogen oxides thus produced can be broadly classified into pre-combustion treatment, in-combustion treatment and post-combustion treatment. In general, the techniques applied to the combustion process are based on the flame temperature at each location and the chemical reaction control of the combustion. When properly combined, these technologies can achieve emissions reductions of 40 to 70 percent. However, there is a limitation in the combustion control method, so it is inevitable to introduce post-combustion treatment technology.

The nitrogen oxide control technology using a conventional catalyst is a selective catalytic reduction (SCR) using NH ₃ as a reducing agent. This method is a method of selectively reducing nitrogen and water vapor by reacting nitrogen oxides in the exhaust gas with the reducing agent while simultaneously passing the exhaust gas and the reducing agent through the catalyst layer.

The expected reactions between the nitrogen oxide and the reducing agent passing through the catalyst bed are as follows.

4NO + 4NH ₃ + O ₂ ↔ 4N ₂ + 6H ₂ O

2NO ₂ + 4NH ₃ + O ₂ ↔3N ₂ + 6H ₂ O

6NO + 4NH ₃ ↔ 5N ₂ + 6H ₂ O

6NO ₂ + 8NH ₃ ↔ 7N ₂ + 12H ₂ O

4NH ₃ + 3O2 ↔2N ₂ + 6H ₂ O

The basic components of the selective catalytic reduction process are catalytic reactors, catalysts, ammonia spraying and control systems. Catalytic reactors include fixed bed reactors, moving bed reactors, and parallel flow reactors. The fixed bed reactor is a reactor in which granules, pellets, and tubular catalysts are randomly filled in the catalyst bed, and the residence time of the gas is long, which increases the removal efficiency of nitrogen oxide and occupies a large volume. Rises, and catalyst clogging and abrasion is caused by direct collision of gas and catalyst. And when replacing the poisoned catalyst has the disadvantage that the operation of the entire process must be stopped.

At present, the SCR method is operated on a commercial scale in Japan.

Main catalysts used in the SCR method are mainly TiO ₂ , WO ₃ , V ₂ O ₅ , MoO ₃ , and the like.

Recently, it is known that the catalyst can be simultaneously coated to control nitrogen oxides and dust, and research on coating the catalyst on the filter has been conducted. Currently, US Patent Nos. 4,220,633, 4,309,386, 4,732,879 and 5,620,669 , 5,843,390 and the like. In general, the process temperature of the flue gas in the SCR method is applied in the range of 300 ~ 400 ℃ because the removal rate of nitrogen oxide is the highest in this temperature range. Therefore, since the filter medium of the catalyst filter is also exposed to a temperature range of 300 to 400 ° C, the material of the filter medium used at this time may be woven glass fiber, ceramic fabric filter, or woven silica glass fiber. silica glass fiber) and the like have been proposed.

U.S. Patent No. 4,220,633 and U.S. Patent No. 4,309,386 use catalyst coating on a filter in a dust collector and method for simultaneously removing nitrogen oxides and dust, and filter metal by spraying a metal catalyst and a non-metal catalyst into a solution. A filter was prepared by coating on a filter, and an appropriate application temperature was 250 to 400 ° C., and glass, metal, ceramic, and the like were used as the filter medium.

In the case of US Pat. No. 4,732,879, a glass fiber or ceramic filter was used as a filter medium, and various metal oxide catalysts such as Ti, V, Zr, and Si were prepared by themselves or mixed to prepare a catalyst and dissolve them in an organic solvent to dissolve the filter. After soaking in, taken out, the surface was dried, and then placed in a microwave oven or a general oven and maintained for several hours in a temperature range of 250 to 500 ° C. This method is called cure treatment, which is intended to remove organic or hydroxyl groups contained in the catalyst and the filter, and to make the activity of the catalyst the best. Pores having a uniform distribution are formed on the surface of the catalyst filter cured in this manner.

U.S. Pat.Nos. 5,620,669 and 5,843,390 produce a catalytic fiber by mixing a catalyst with a fiber and then mixing it with PTFE, which is the main filter material, to produce a felt through a carding process and a needle process, and a surface to which inflow dust adheres. The catalyst was prepared by laminating PTFE at the surface to form a microporous membrane.

Among the existing catalysts developed for the removal of nitrogen oxides, the mixed catalyst of V ₂ O ₅ / TiO ₂ is known to have the best removal efficiency of nitrogen oxides. The biggest disadvantage of these catalysts is that the removal rate of nitrogen oxides is 300 ~ Since it is the highest in the 400 ° C range, the process must be performed in this temperature range, and the value of the filter medium used here is expensive. Therefore, there is a disadvantage that the use of the V ₂ O ₅ / TiO ₂ catalyst is limited in the process of the lower or higher temperature range.

An object of the present invention for solving the above disadvantages is that the application temperature of the existing catalyst filter is applied to a high temperature of 300 ~ 400 ℃, the temperature range is 150 to 250 ℃ with a catalyst that can be applied to the filter It is aimed at removing nitrogen oxide and fine dust at the same time, and the catalyst coated on the filter media should be uniformly distributed, and the catalyst and filter media should be well bonded and there should be no wear or damage of catalyst even if used for a long time. When the catalyst is attached to the catalyst, poisoning phenomenon occurs in which the catalyst does not exhibit its original function. To prevent such phenomenon, a membrane coating is formed on the surface of the catalyst to remove fine dust first, and the nitrogen oxide is secondary by the catalyst. It is to prepare a filter having a structure that is removed.

1 is a diagram of nitrogen oxide removal according to temperature of the catalyst for removing nitrogen oxide applied to the present invention (Example MG-1),

2 is a diagram illustrating nitrogen oxide removal by temperature of the catalyst for removing nitrogen oxides (exemplary MG-2) applied to the present invention;

3 is a diagram of nitrogen oxide removal according to temperature of the catalyst for removing nitrogen oxides applied to the present invention (Example MG-3),

4 is a diagram of nitrogen oxide removal according to temperature of the catalyst for removing nitrogen oxides applied to the present invention (Example MG-4);

5 is a schematic view of a catalyst filter for medium and low temperature of the present invention.

<Description of the symbols for the main parts of the drawings>

The present invention is to achieve the object as described above, to meet the above requirements to obtain a filter bag for a dust collector that can obtain a low pressure loss, high dust collection efficiency and separation efficiency.

The present invention has a MG-1, MG-2, MG-3, MG-4 catalyst in order to achieve the above object, it was applied to the filter medium to prepare a filter. MG-1 and MG-2 have high nitrogen oxide removal rates in the temperature range of 140 to 170 ° C., but have the disadvantage that they show optimal effects only in the absence of sulfur oxides. MG-3 and MG-4 are applicable in the temperature range of 180 to 220 ℃ and can be used without problems when the concentration of sulfur oxides is low, but the nitrogen oxide removal rate is slightly lower than MG-1 and MG-2. Results of nitrogen oxide removal rates for MG-1 and MG-2 are shown in FIGS. 1 and 2. However, in the case of sulfur oxides can be removed by using an absorbent, even in the presence of sulfur oxides there is no difficulty in using MG-1 and MG-2. In the case of MG-3 and MG-4, when the temperature is increased to 220 ° C or higher, the concentration of NO ₂ is increased as a side reaction. Therefore, it is appropriate to use in this temperature range. The results of nitrogen oxide removal rates for MG-3 and MG-4 are shown in FIGS. 3 and 4.

The material for coating the catalyst was a filter material of polytetrafluoroethylene (PTFE), meta-aramid fiber, and polyamide fiber, and the filter material was the best in continuous operation. The application temperature is able to withstand the temperature range of 250 ℃, and is suitable as a filter material because of its excellent physical strength and mechanical strength.

The catalyst filter may be prepared by spraying a catalyst in a slurry state, by dipping the filter after dissolving the catalyst in a solvent, or by mixing the catalyst with the fiber before opening the fiber to prepare the catalyst fiber from the beginning. have.

After the spray method and the dipping method, it is placed in an oven and maintained at 150 to 250 ° C. for 4 to 6 hours. This operation is said to be cured, and when this is taken out, the production of the catalyst filter is completed first. Curing improves the bond between the catalyst and the filter, increases the activity, and removes unnecessary elements such as organic compounds on the surface of the filter. In addition, appropriate pores are formed on the surface of the filter, and the pores formed are uniformly distributed. In the dipping method, if the repetition is repeated several times, the surface area of the catalyst coated on the surface of the filter is increased to increase the area capable of reacting with the nitrogen oxide, thereby increasing the removal rate of the nitrogen oxide.

The catalyst causes poisoning by adhesion of dust and contact with harmful gases. That is, dust is attached to the catalyst to prevent the role of the catalyst. In order to overcome this disadvantage, a porous membrane is formed on the surface of the catalyst by coating a membrane. PTFE is used as the membrane material.

A schematic diagram of the catalyst filter thus prepared is shown in FIG. 5. The catalyst filter can remove nitrogen oxide and fine dust at the same time, and has excellent performance of collecting dust and excellent removal rate of nitrogen oxide by surface filtration.

(Example)

The present invention is the first structural theory to the coating material that can be applied to the process of discharging the exhaust gas of about 150 ~ 250 ℃ to the filter medium of the non-woven fabric, and by coating the membrane on the surface to be prepared to remove nitrogen oxides and fine dust at the same time As the filter medium used to achieve the above structure, polytetrafluoroethylene (PTFE), meta-aramid fiber, polyamide fiber, and PTFE are used as membrane materials. In addition, as a second manufacturing methodology, a slurry catalyst which is applicable to the process of discharging the exhaust gas of about 150 to 250 ° C. to the filter medium, which is a nonwoven fabric, is coated on the surface to remove nitrogen oxides and fine dust at the same time. It is applicable to the process of manufacturing and discharging the exhaust gas of about 150 to 250 ℃ by using the nonwoven fabric filter material. It is prepared by melting and dipping a good catalyst to remove nitrogen oxide fine dust at the same time, and mixing the catalyst with the fiber which is applicable to the process of exhausting the exhaust gas of about 150 ~ 250 ℃ before opening the fiber. It is completed by manufacturing with a catalyst fiber.

The present invention as described above allows the catalyst to be coated on the filter medium and the membrane is coated on the surface so that it is possible to remove nitrogen oxide and fine dust at the same time. In addition, since surface filtration is performed, the pressure loss is low, which has the effect of reducing the total energy cost. Therefore, when the catalytic filter is installed in an incinerator, a coal combustion furnace, an LNG combustion process, a chemical plant, or the like that discharges exhaust gas containing nitrogen oxides, clean air can be discharged. One of the important factors in the production of a catalyst filter is the price of the catalyst. The catalyst used in the present invention is inexpensive, and thus it is considered to be more economical in terms of facility cost than the case of installing a catalytic reactor by the selective catalytic reduction method. In addition, when SCR is used, the operation must be stopped when the catalyst is replaced, and when the catalyst filter is used, several dust collectors can be installed and used without interruption of operation.

Claims (6)

Medium and low temperature, which is manufactured to remove nitrogen oxides and fine dust at the same time by coating a catalyst that is applicable to the process of discharging the exhaust gas of about 150 ~ 250 ℃ to non-woven fabric and coating the membrane on the surface Catalyst filter. The method of claim 1, The filter medium is a catalyst filter for medium and low temperature, characterized in that one selected from the group consisting of polytetrafluoroethylene (PTFE), meta-aramid fiber, polyamide fiber (polyimide fiber) . The method of claim 1, Catalyst for medium and low temperature, characterized in that PTFE is used as the membrane material. The non-woven filter medium is coated with a catalyst in the form of slurry applicable to the process of discharging the exhaust gas of about 150 ~ 250 ℃, and the membrane is coated on the surface to be manufactured to remove nitrogen oxides and fine dust at the same time Method for producing a medium and low temperature catalyst filter. Manufacturing a catalyst filter for medium and low temperature, characterized in that to remove the fine dust of nitrogen oxide at the same time by melting and dipping the catalyst applicable to the process of discharging the exhaust gas of about 150 ~ 250 ℃ nonwoven fabric Way. A method for producing a catalyst filter for medium and low temperature, characterized in that the catalyst is applicable to the process of discharging the exhaust gas of about 150 to 250 ° C. before the fiber is opened, and then, the fiber is prepared as a catalyst fiber from the beginning.