KR20040090182A - Baghouse for simultaneously removing fine particle and nitric oxides to preliminary reduction of dust loading - Google Patents

Abstract

PURPOSE: A hybrid air purification apparatus is provided to simultaneously remove gaseous pollutants such as NOx and particulate pollutants from flue gas by using catalyst-coated filter. CONSTITUTION: The apparatus comprises a clean gas chamber(20) consisting of a cleaning system part and a clean gas outlet part(21), a dust collection chamber(7) where many dust collection filters(19) consisting of a catalyst coated filter, installed vertically down on a perforated plate(22) installed on the lower part of the clean gas chamber, an inner case part(15) separating air current flown in a tangential direction, an inflow duct part(12) where flue gas gone through a desulfurization process and reducing agents sprayed from a reducing agent sprayer are flown in a tangential direction and a hopper(8) primarily collecting dusts of the flue gas flown in a tangential direction by using centrifugal force and discharging the collected dusts.

Description

Baghouse for simultaneously removing fine particle and nitric oxides to preliminary reduction of dust loading}

The present invention relates to a filter dust collector for simultaneously removing dust and nitrogen oxides contained in the exhaust gas generated in power plants, boilers, waste incineration process, metal melting, smelting, heat treatment facilities, petroleum refining and petrochemical manufacturing process, In detail, the filter material having the surface thin film layer is applied to the dust load reduction hybrid type filter device which combines the centrifugal dust collector and the filter dust collector into one device to improve the collection efficiency of fine dust particles and to reduce the dust load applied to the filter. Significantly improves the performance of the dust collector, such as reducing, and in particular, the support layer of the filter medium is supported or coated with a reducing catalyst, so that the fine dust and nitrogen oxide having the function of decomposing nitrogen oxide into harmless nitrogen and water in contact with the reducing agent. The present invention relates to a bag filter that can be removed at the same time.

Exhaust gases emitted from power plants, boilers, and waste incineration processes contain harmful gases such as dust, nitrogen oxides, and sulfur oxides.

In case of dust, remove it by applying electrostatic precipitator or filter dust collector.

In the case of sulfur oxides, the emission concentration is decreasing due to the installation of desulfurization facilities, but the emission of nitrogen oxides is gradually increasing.

The techniques applied to capture nitrogen oxides are removed by the combustion condition improvement method and the post-combustion denitrification system. The combustion condition improvement method reduces the nitrogen oxides by less than 30%. Methods, that is, selective catalytic reduction method, non-selective catalytic reduction method, and sulfur oxide / nitrogen oxide simultaneous treatment technology are applied.

However, each facility is arranged in a line to deal with contaminants such as dust, nitrogen oxides, and sulfur oxides, thus occupying a large amount of space for installation and increasing maintenance costs by requiring separate management of each facility. It has disadvantages such as making.

In addition, in the case of nitrogen oxides, the selective catalytic reduction method is mainly applied. In this case, when dust is attached to the catalyst or sulfur oxides are attached to the catalyst, it cannot function as a catalyst.

Recently, a technique of applying such a catalyst with a filter has been developed.

Conventional electrostatic precipitators are suitable for large-capacity flue gas throughput, but the dust collection concentration is relatively low due to the relatively low dust collection efficiency compared to the filter precipitator. In the case of the filter precipitator, the dust is attached to the precipitating filter and As the loss increases rapidly, it has a disadvantage of periodically exhausting by using high pressure compressed air.

In order to overcome this point, hybrid type dust collectors incorporating two or more dust collection principles have been developed and applied, which can improve dust removal efficiency by combining centrifugal force with filtered dust or combining electric force with filtered dust with a single dust collector. In addition, the dust load flowing into the dust collecting filter can be reduced.

As described above, dust and nitrogen oxides are removed by the respective equipment. Recently, techniques for removing dust and harmful gases at the same time have been proposed, and the possibility of sufficiently replacing existing pollutant treatment devices has been recognized.

However, there are many problems in order to enable high efficiency removal of dust contained in flue gas and stable reaction of nitrogen oxides.

To date, techniques designed to simultaneously remove dust and nitrogen oxides are as follows.

US Pat. No. 4,309,386, which is an example of the prior art, relates to a baghouse and a method for simultaneously removing nitrogen oxides and dust from exhaust gas. A catalyst coated filter is applied to a conventional bag filter, and ammonia is used as a reducing agent. It was.

In this method, the exhaust gas discharged from the coal combustion boiler flows directly into the bag filter to remove dust and nitrogen oxides. Therefore, the material of the filter cloth applied to the bag filter must select a material that can withstand high temperatures of 300 ° C or higher. As there is no facility for removing sulfur oxides in the front end, the reduction catalyst of the catalytic coating filter is poisoned by sulfur oxides, resulting in a problem of deterioration in performance.

US 4,874,576, which is another example of the prior art, installs a tubular filter containing a catalyst in a conventional bag filter to remove dust from the filter surface, and nitrogen oxides and sulfur oxides are reacted with a catalyst to remove them. The catalysts are inserted into the tubular filter in pellet form, and the inserted tubular filter is fixed in the axial direction at regular intervals.

This is difficult in laminating the catalyst to the filter, and causes problems in the dust removal operation to shake off the dust adhering to the filter surface.

US 5,585,081, another example of the prior art, relates to a system capable of simultaneously removing sulfur oxides, nitrogen oxides, dust, and the like, injecting an absorbent and a reducing agent in front of a conventional filter dust collector, and removing dust by a dust filter. And, the sulfur oxide passes through the absorbent attached to the dust collecting filter and the absorption reaction takes place and is removed. The nitrogen oxide passes through the stacking surface of the reducing catalyst inserted in the dust collecting filter and reacts with the reducing catalyst to remove it with nitrogen and water. It is a system. Four methods of stacking the catalyst to be inserted into the dust collecting filter include stacking the catalyst in a cylinder such as a holder, inserting a support coated with a catalyst on a bent metal surface into the filter, and a honeycomb catalyst. It can be installed on the top of the filter, a method of filling a catalyst with a separate holder inside the filter.

In this system, since the absorbent is first injected dry, the removal rate of sulfur oxides is low, and there is a problem of poisoning the reduction catalyst layer inserted into the filter. Since the separate holder has a separate holder, it is not easy to maintain and manage the dust collection filter. , Difficult to remove dust attached to the surface of the dust collecting filter by a holder or a honeycomb catalyst in which the catalyst is stacked inside the dust collecting filter, it becomes difficult to replace the dust collecting filter.

In all three examples, the conventional filter dust collector is used. As a result, there is no way to reduce the load of dust flowing into the apparatus, and most of the dust is attached to the dust collector and the pressure loss rapidly increases. This may cause a problem, thereby frequently performing the dust removal operation to shake off the attached dust, which shortens the life of the dust collecting filter, and also activates the catalyst inserted into the holder inside the dust collecting filter by such an operation. It is expected to have a bad effect.

An object of the present invention for solving the above problems is to provide a device applying a catalytic coating filter to a hybrid filter bag for simultaneously removing dust and nitrogen oxide contained in the exhaust gas.

The object of the present invention as described above was applied to the hybrid type dust collector which combines the centrifugal force dust collecting principle and the filter dust collecting principle, the configuration is the exhaust gas flows in a tangential inflow method through the inlet duct, when reaching the dust filter is uniform The distribution plate is installed at the bottom to have a flow, which is configured to be discharged into the atmosphere through the outlet duct,

In the dust collecting filter applied to the dust collection chamber of the hybrid filter dust collector applied to the purpose of the present invention, a catalytic coating filter coated with a reducing catalyst is applied, and a thin film layer is formed on the surface of the filter medium to remove even fine dust with high efficiency. The filter medium support layer is coated with a reducing catalyst to provide a property of decomposing nitrogen oxides into harmless nitrogen and water by reacting with a reducing agent introduced from a shear reducing agent injection device of the filter bag.

In the dust extraction system of the present invention, the compressed air storage tank, the solenoid valve, the compressed air pipe for injection, etc. exist inside the clean gas discharge unit, and multiple compressed air pipes for the present invention are not installed. It is achieved by providing a device composed of a compressed air storage tank, a solenoid valve, and a compressed air pipe for injection, connected to a rotating motor, which rotates by a predetermined angle and delivers compressed air to the filter medium to shake off dust. .

1 is an exemplary industrial exhaust gas process of the present invention,

Figure 2 is a schematic perspective view of the integrated bag filter of the present invention,

Figure 3 is a schematic view showing in detail the dust removal system of the present invention,

4 is a structural diagram of a catalyst coated filter applied to the present invention.

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

(5): reducing agent injector (6): bag filter

(7): Dust collection chamber (8): Hopper

(9): dust exhaust system part (10): stack

(11): Hamjin gas (12): Inlet duct

(13): downdraft (14): updraft

(15); Inner tube 16: distribution plate

(19): dust filter (20): clean gas chamber

21: clean gas outlet 22: perforated plate

(23): high pressure compressed air inlet pipe (24): high pressure compressed air storage tank

(25): solenoid valve (26): compressed air pipe for injection

(28): rotary motor 40: thin film surface layer

(44): Electrostatic filtration layer (42): Reduction catalyst filter support layer

When described in detail with reference to the accompanying drawings, the configuration and the operation of the embodiment of the present invention to achieve the object as described above and to perform the task for eliminating the conventional drawbacks.

In the exhaust gas generating process to which the filter device of the present invention is applied, a process of discharging clean gas into the atmosphere is as shown in FIG. 1.

As shown in FIG. 1, the main configuration includes a fuel injection unit 1, a fuel combustion unit 2, a desulfurization process unit 3, a filter dust collector unit 6, and a stack 10.

The exhaust gas burned in the boiler includes nitrogen oxides, sulfur oxides, dust, and the like. First, sulfur oxides are removed by the desulfurization process unit 3 by the absorbent spray 4.

The impregnated gas and the nitrogen oxide are introduced into the filter dust collector unit 6, which is the main body of the dust collector, which is removed from the dust collection chamber 7 installed therein and discharged to the outside through the hopper 8, and the nitrogen The oxide is reacted with the reducing catalyst coated on the catalytic coating filter of the dust collection chamber by contacting the reducing agent injected from the reducing agent injector 5 to be decomposed into nitrogen and water, and only the clean gas is discharged into the atmosphere through the stack 10. .

The filter dust collecting apparatus 6 includes a dust collecting chamber 7 in which the uppermost clean gas chamber 20 and the dust collecting system unit 9 installed thereon, and a plurality of dust collecting filters 19 serving as intermediate parts are arranged and arranged. The inner cylinder part 15 which isolate | separates the airflow which flows in the tangential direction located in the lower part, the inflow duct part 21 which induces the exhaust gas and the reducing agent to the tangential direction of a dust collector, and the lowermost hopper 8 are comprised.

The exhaust gas flowing into the filter dust collector 6 is configured in such a manner that it flows in the tangential direction of the dust collector.

The filter dust collecting part is located inside the dust collecting chamber in which the dust collecting operation is performed, and the filter dust collecting part is composed of a plurality of catalytic coating filters.

The lower part of the dust collecting chamber is configured by applying a distribution plate so that the airflow flowing into the dust collecting chamber has a uniform flow.

Inside the clean gas chamber, a dust removal system section 9 capable of injecting high-pressure compressed air for dusting off dust adhered to the filter body of the dust collection chamber is configured.

Existing dust removal system has a plurality of pipes and nozzles for injecting high pressure air from the outside of the device to remove the dust collecting filter, the present system is characterized in that it is configured inside the clean gas chamber.

The hopper 8 is configured to be inclined to be vertically reduced by tilting to allow the dust accumulated inside to slide downward by its own weight, and at the bottom thereof, a rotary valve for forcibly discharging dust and Install the same apparatus.

Figure 2 shows a perspective view of an application specific example of a hybrid filter bag applied to the filter bag of the present invention.

In the present invention, the bag filter 6 is a hybrid bag filter device in which the centrifugal force and the bag filter principle are combined with a single bag filter.

The main configuration of the device is composed of the exhaust gas inlet duct 12, the inner cylinder portion 15, the dust collection chamber 7, the clean gas chamber 20, the dust discharge hopper 8, etc., through the inlet duct 12 The nitrogen-containing gas 11 including nitrogen oxide is introduced, and a reducing agent for reducing nitrogen oxide is injected from the reducing agent injection device 5 at this portion.

The dust contained in the inlet flue gas is first attached to the wall surface 17 while being followed by the descending air flow 13 descending to the lower portion, and the impregnated gas which is not removed from the inlet exhaust gas rises to the filter dust collector. 14), wherein the upward airflow has a uniform upward flow distribution by the distribution plate 16 installed at the lower end of the inner cylinder part 15.

The dust collecting filter 19 constituting the filter dust collecting unit is vertically attached to the perforated plate 22, which is a boundary separating the clean gas chamber 20 and the dust collecting chamber 7, and uses a plurality of circular bags to form multiple units. Arrange with a dust collecting filter.

The upper end of the dust collecting filter 19 connected by the perforated plate 22 is opened so that the clean gas passing through the dust collecting filter 19 can be discharged to the outside of the device through the clean gas chamber 20, and the dust collecting filter 19 The bottom is sealed to prevent the impregnated gas 11 from entering the clean gas region.

Figure 3 shows a perspective view of the application of the dust removal system newly applied to the filter bag of the present invention.

In the conventional general dust removal system, a plurality of pipes and nozzles are positioned to inject high pressure air from outside the apparatus to shake off dust attached to the dust collecting filter.

In the present dust collector, the dust removal system unit 9 is configured in the clean gas chamber 20.

Specifically, the compressed air is introduced into the high pressure compressed air storage tank 24 through the high pressure compressed air inlet pipe 23, and the compressed air for injection is provided through a solenoid valve 25 capable of injecting the high pressure compressed air. The compressed air of the dust collecting filter high pressure is transferred through the compressed air injection nozzle 27 which flows into the pipe 26 and the lower part, and the dust attached to the dust collecting filter is dropped.

At this time, the high pressure compressed air reservoir 24, the solenoid valve 25, and the compressed air pipe 26 for injection are rotated in the clean gas chamber 20 by the rotary motor 28 existing in or above the dust collector. It is.

4 is a structural diagram of the catalytic coating filter which is the dust collecting filter 19 applied to the dust collecting chamber 7 of the filter dust collecting apparatus 6 of the process of the present invention.

The filter medium is formed of two or three layers. The thin film surface layer 40, which is the primary layer, has a nanoporous layer or a conventional thin film layer, and the reducing catalyst filter layer 42, which is the secondary layer, has a reducing catalyst. The correction or filtration layer 44, which is a supported or coated layer, may be applied or not, which is composed of an electrostatic filter.

Referring to the operation of the filter bag of the present invention configured as described above are as follows.

Dust and nitrogen oxides contained in the inlet flue gas 11 passing through the desulfurization process unit 3 are introduced into the filter dust collector 6, where the flow direction of the air flows in the form of falling along the tangent of the filter dust collector. .

This does not flow directly into the dust collection chamber 7 by the inner cylinder to form a downdraft and hit the wall surface of the lower portion by centrifugal force to collect the dust primarily.

The remaining dust particles which are not collected at the lower reaches the dust collection chamber 7 and are removed while passing through the dust collecting filter 19. The clean gas is raised inside the dust collecting filter 19 to clean the gas chamber 20. It is discharged out through the clean gas outlet 21.

Since a relatively large amount of dust particles are collected by the downwardly flowed air flowing in the tangential direction, the amount of dust flowing into the dust collecting filter 19 is reduced as compared with the case of using only a conventional filter dust collector. It is possible to significantly suppress the sudden increase in pressure loss of the dust collecting filter due to the accumulation.

The dust flowing through the dust collection chamber 7 is mainly collected on the surface of the dust collecting filter. Since the surface layer of the dust collecting filter is formed as a thin film layer, it is particularly effective for collecting fine dust particles. There is a characteristic to improve.

Dust adhering to the surface of the dust collecting filter is dedusted by the pressurized compressed air supplied through the injection compressed air pipe 26 and the compressed air injection nozzle 27, and the dust removal system is installed inside the clean gas chamber 20. It is characterized in that it is installed, the high pressure compressed air storage tank 24, the solenoid valve 25 and the injection compressed air pipe is connected to the rotary motor 28, while rotating to deliver the high pressure compressed air to the dust collecting filter There is this.

In addition, the support layer 42 of the catalytic coating filter used as the dust collecting filter 19 is supported or coated with a reducing catalyst to reduce nitrogen oxides, wherein the active temperature range of the reducing catalyst used is about 150-250 ° C. Compared with the catalyst mainly used for the activity temperature is low.

Since the filter material can be used at 150-250 ° C. to apply the material of the filter material, the material selection of the filter body can be made more diverse than that of the conventional reduction catalyst.

The reducing agent injected to react with the reducing catalyst may use ammonia, hydrocarbons, urea, or the like depending on the type of catalyst applied.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

As described above, the present invention is characterized in that the hybrid filter dust collector and the catalyst-coated filter medium are effectively disposed in a single device to remove dust and nitrogen oxide contained in the exhaust gas at the same time.

In addition, the filter dust collector applied to the present invention in the form of a hybrid incorporating two or more of the dust collection principle, the dust contained in the exhaust gas to be removed by the centrifugal force primarily by centrifugal force of the dust contained in the dust containing gas By reducing the load, it is possible to reduce the increase in pressure loss in the filter, thus reducing the number of dust removal operations to shake off the dust on the filter surface, thereby preventing the breakage of the filter compared to the filter used in the conventional bag filter. There is a characteristic that can extend the life.

In addition, since the dust extraction system is installed in the clean gas chamber, the conventional dust removal system does not require the application of a plurality of solenoid valves and pipes, thereby reducing the installation cost. The hybrid dust collector of the present dust collector has a cylindrical structure. The size of the device to which the filter can be applied is limited, but since the dust removal system is located inside the clean gas chamber, the device can be enlarged.

In addition, as a filter body applied in the present invention, a catalytic coating filter was applied, and the surface of the filter body is formed with a surface layer having nanopores or a thin film layer, thereby significantly improving dust collection efficiency.

In addition, the support layer of the catalytic coating filter used as the dust collection filter of the present invention is supported or coated with a reducing catalyst, so that the reducing agent and nitrogen oxide contained in the flue gas react with each other through the catalyst layer to decompose nitrogen oxide into harmless nitrogen and water and It has a characteristic to be discharged to the middle.

Claims (10)

In the apparatus for removing dust and nitrogen oxide contained in the flue gas generated in power plants, boilers, waste incineration process, metal melting, smelting, heat treatment facilities, petroleum refining and petrochemical manufacturing process, Consists of an integrated filter dust collector that simultaneously removes dust load reduction fine dust and nitrogen oxide, The filter dust collector (6) comprises a clean gas chamber (20) consisting of a dedusting system (9) and a clean gas outlet (21) installed therein, which constitute the uppermost part, A dust collecting chamber (7) for collecting dust by collecting a plurality of dust collecting filters (19) composed of a catalytic coating filter installed vertically downward on the perforated plate (22) installed at the lower portion of the clean gas chamber; An inner cylinder part 15 separating the air flow flowing in a tangential direction located at a lower portion thereof, An inlet duct 21 in which the reducing agent injected from the impregnated flue gas and the reducing agent injector having passed through the desulfurization process flows in a tangential direction of the dust collector; A dust collecting reduction type dust collecting device for simultaneously removing fine dust / nitrogen oxides, characterized in that it comprises a hopper (8) which collects and discharges the dust of exhaust gas flowing in the tangential direction at the bottom, using centrifugal force. The method of claim 1, The dust collection and reduction type fine dust / nitrogen oxide simultaneous dust removal filter, characterized in that the distribution plate 16 is installed in order to uniformly distribute the flow of the exhaust gas flowing into the dust collection chamber below the inner cylinder portion (15). The method of claim 1, The dedusting system unit 9 installed inside the clean gas chamber 20 has a high pressure compressed air inlet pipe 23, a high pressure compressed air storage tank 24 storing the compressed air, and high pressure compressed air. It is composed of a solenoid valve (25), a compressed air pipe for injection (26) connected to the pipe and a compressed air injection nozzle (27) installed in the lower portion thereof, and the rotary motor (28) for rotating it Filter dust collecting device for removing dust load reduction fine dust / nitrogen oxide at the same time, characterized in that configured to rotate in the clean gas chamber 20 by. The method of claim 1, The structure of the dust collecting filter 19 is the bottom is blocked, the top is an open structure, the structure of the filter layer is composed of a thin film surface layer 40, which is a primary layer from the outside, and a reduction catalyst filter support layer 42, which is a secondary layer. Dust collecting reduction type fine dust / nitrogen oxide removal filter for dust at the same time characterized in that. The method of claim 4, wherein And a reduction filter medium support layer (42), followed by a correction filtration layer (44) which is a tertiary layer. The method of claim 4, wherein The thin foil surface layer structure 40 is a dust collection reduced dust type, characterized in that composed of one selected from the nano-porous layer or the thin film layer / filter dust collecting device for the simultaneous removal of nitrogen oxides. The method of claim 4, wherein The reduction catalyst filter support layer 42, which is the secondary layer, is configured to use one selected from a supporting method and a coating method for reducing catalyst. The method according to any one of claims 4 to 7, The reduction catalyst filter support layer (42), which is the secondary layer, is a filter material for reducing dust load-reducing fine dust / nitrogen oxide simultaneously, characterized in that the filter material can withstand a temperature of 150 ° C. or more. The method according to any one of claims 4 to 7, Reduction catalyst applied to the reduction catalyst filter support layer 42, which is the secondary layer, is a reduction catalyst that can be applied at an active temperature of 150 to 250 ° C. Dust collector. The method of claim 1, Reducing agent flowing into the inlet duct portion 21 is a dust collection, dust reduction and fine dust / nitrogen oxide at the same time characterized in that one selected from the group consisting of urea, hydrocarbons.