Device and method for dry low-temperature denitrification of industrial kilns

Abstract

The present invention belongs to the field of flue gas purification technology, specifically to a device and method for dry, low-temperature denitrification in industrial kilns. The device comprises a denitrification tower and a bag filter connected by a flue gas duct, as well as a denitrification agent generator connected to the denitrification tower via a liquid inlet pipe. The denitrification tower has an inverted U-shaped structure and is internally equipped with a spray device connected to the liquid inlet pipe, which is equipped with a liquid inlet pump. The device has a simple structure, is easy to install, and is convenient to operate. The denitrification agent is non-toxic and odorless, safe, reliable, and effective, with a denitrification efficiency exceeding 95%.

Description

Technical Field

[0001] The present invention belongs to the technical field of flue gas purification, and in particular relates to a device and method for dry low-temperature denitration of an industrial kiln. Background Art

[0002] Industrial kiln flue gas contains a large amount of NO x 、SO x , dust and other pollutants. According to statistics, SO x 90% of NO x 70% of the carbon dioxide and 70% of the soot come from the direct combustion of raw coal. Therefore, industrial furnace flue gas is the main cause of air pollution in my country. Controlling coal-fired flue gas pollution, controlling nitrogen oxides in flue gas, and achieving ultra-low emissions are strict requirements of environmental protection departments and are also necessary for environmental protection.

[0003] The existing SCR dry denitrification technology uses ammonia as a denitrification reducing agent, which preferentially reacts with NO in the flue gas at 305-400℃. x A reduction reaction occurs, generating nitrogen and water, without an oxidation reaction with oxygen in the flue gas, thereby achieving flue gas denitrification. However, when the flue gas temperature falls below 305°C, ammonium sulfate (NH4)2SO4 and ammonium bisulfate NH4HS04 are easily generated. Ammonia salts are highly viscous and easily adhere to the heating surfaces of the catalytic module and the rear end of the boiler, corroding and clogging the equipment and affecting boiler operation. The catalytic module is prone to poisoning and failure, requiring regular replacement, resulting in high operating and maintenance costs. Furthermore, ammonia water is a highly toxic and hazardous substance, flammable and explosive. If ammonia escapes, it will cause secondary pollution. Summary of the Invention

[0004] In order to solve the problems of complex equipment, high cost and easy secondary pollution in the existing SCR dry denitrification technology, the present invention provides a more scientific and advanced industrial kiln dry low-temperature denitrification device and method.

[0005] In order to achieve the above objectives, the following technical solutions are adopted:

[0006] The present invention provides a device for dry low-temperature denitrification of an industrial kiln, comprising a denitrification tower and a bag dust collector connected by a flue gas duct, and also comprising a denitrification agent generating device, wherein the denitrification agent generating device is connected to the denitrification tower via a liquid inlet pipe, and the denitrification tower is an inverted U-shaped structure and is internally provided with a spray device, and the spray device is connected to the liquid inlet pipe.

[0007] Furthermore, the denitrification agent generating device includes a plurality of raw material storage tanks and reaction tanks, and each of the raw material storage tanks is independently connected to the reaction tank via a raw material pipe.

[0008] Furthermore, each of the raw material pipes is provided with a metering pump, and the liquid inlet pipe is provided with a liquid inlet pump.

[0009] Furthermore, the spray device includes a plurality of spray pipes, and each of the spray pipes is equipped with a plurality of high-pressure micron atomizing spray guns.

[0010] Furthermore, the smoke inlet and the smoke outlet of the denitrification tower are symmetrically arranged at the lower part of the denitrification tower, and the diameter of the smoke duct is consistent with the boiler smoke pipe.

[0011] Furthermore, the denitrification tower is 22 meters high and is provided with a plurality of maintenance observation holes.

[0012] The present invention also provides a denitration method using the above device, comprising the following steps:

[0013] A. Prepare the denitrification agent in the reaction tank and transport it to the spray device through the liquid inlet pump and liquid inlet pipe;

[0014] B. The flue gas from the industrial kiln enters the bottom of the denitrification tower through the flue gas pipeline and mixes with the denitrification agent after passing through the high-pressure micron atomization spray gun. The vaporized denitrification agent fully contacts and reacts with the nitrogen oxides in the flue gas;

[0015] C. The flue gas after the reaction enters the bag dust collector through the smoke outlet and the smoke duct, and the non-toxic nitrogen is sent into the chimney for discharge. The impurities in the flue gas are filtered, absorbed, captured, collected and purified by the bag dust collector.

[0016] Furthermore, the denitrification agent is hypochlorous acid water prepared by combining one or more of sodium hypochlorite, sodium chlorite and chlorine dioxide with deionized water in the presence of a catalyst, and the concentration of the hypochlorous acid water is 30,000 ppm.

[0017] Furthermore, the catalyst is an aqueous solution of sulfamic acid and citric acid.

[0018] Compared with the existing SCR technology, the present invention has the following beneficial effects:

[0019] 1. Hypochlorous acid water has the characteristic of low-temperature denitrification. Without the need for a catalytic module, it can fully and rapidly react flue gas at 60-300°C with nitrogen oxides to produce nitrogen and water. Hypochlorous acid water has extremely strong redox properties, quickly and efficiently decomposing and reducing nitrogen oxides from flue gas. It also reacts with sulfur dioxide in the flue gas to remove sulfates. Furthermore, hypochlorous acid water is odorless, non-toxic, non-flammable, and non-explosive, making it safe to store and generating no secondary pollution. It also produces no wastewater or exhaust gas, thus meeting environmental requirements.

[0020] 2. The denitrification device of the present invention is an inverted U-shaped tower, which is installed after the induced draft fan at the smoke outlet of the kiln and before the bag dust collector. The smoke inlet is connected to the induced draft fan, and the smoke outlet is connected to the dust collector. The diameter of the U-shaped tower is designed according to the air volume and the wind speed of 10 meters. The tower height is designed to ensure that the denitrification reaction time is preferably 3 seconds, and the design height is 22 meters. Multi-layer atomizing spray guns are installed in the tower. The denitrification agent is sprayed into the denitrification device through the atomizing spray gun, heated and vaporized by the flue gas, and fully contacts and reacts with the nitrogen oxides in the flue gas. After vaporization, the denitrification agent is more reactive and contacts with the nitrogen oxides in the gaseous state, which increases the contact area, improves the reaction conditions, and achieves a better denitrification effect.

[0021] 3. The process of the present invention is simple. Only an atomizing spray gun is installed inside the equipment, and no catalytic module is required. Therefore, the equipment has a small diameter, occupies a small area, is compact, easy to install, easy to operate, and does not require major maintenance.

[0022] 4. A bag dust collector is installed behind the denitrification tower to capture and collect the salt substances generated during the denitrification process, and remove them together with the fly ash particles, reducing secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of the device for dry low-temperature denitration in an industrial kiln according to the present invention;

[0024] Figure 2 This is a process flow chart of the dry low-temperature denitrification in an industrial kiln according to the present invention.

[0025] Markings in the attached figure: 1 is the flue gas duct, 2 is the denitrification tower, 3 is the bag dust collector, 4 is the raw material storage tank, 5 is the reaction tank, 6 is the metering pump, and 7 is the spray device. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0027] Example 1

[0028] A device for dry low-temperature denitrification of industrial kilns, such as Figure 1 As shown, it includes a denitrification tower 2 and a bag dust collector 3 connected by a flue gas duct 1, and also includes a denitrification agent generating device, which is connected to the denitrification tower 2 through a liquid inlet pipe. The denitrification tower 2 is an inverted U-shaped structure and is provided with a spray device 7 inside. The spray device 7 is connected to the liquid inlet pipe, and a liquid inlet pump is provided on the liquid inlet pipe.

[0029] As an implementation method, the denitrification agent generating device includes a plurality of raw material storage tanks 4 and reaction tanks 5, and each of the raw material storage tanks 4 is independently connected to the reaction tank 5 through a raw material pipe.

[0030] Furthermore, each raw material pipe is provided with a metering pump 6. When the denitrification agent needs to be prepared, each raw material enters the reaction tank 5 through the metering pump 6 for mixing reaction.

[0031] Furthermore, the denitrification agent is hypochlorous acid water prepared by one or more of sodium hypochlorite, sodium chlorite and chlorine dioxide and deionized water in the presence of a catalyst, and the catalyst is an aqueous solution of sulfamic acid and citric acid.

[0032] The preparation method of the low-temperature denitrification agent for hypochlorous acid water is as follows: 100 kg of deionized water is taken, 200 g of aminosulfonic acid and 300 g of citric acid are added to prepare an acidic aqueous solution with a pH value of 3 to 4, 7.6 kg of the prepared acidic aqueous solution is taken, 2 kg of sodium hypochlorite with a content of 10% and 0.4 kg of sodium chlorite with a content of 25% are added to prepare a low-temperature denitrification agent for hypochlorous acid water with a concentration of 30,000 ppm.

[0033] As an implementable embodiment, the spray device 7 includes three spray pipes, each of which is equipped with a plurality of high-pressure micron atomizing spray guns, which can convert the denitrification agent from liquid to ultrafine mist.

[0034] As an implementable embodiment, the smoke inlet and smoke outlet of the denitrification tower 2 are symmetrically arranged at the lower part of the denitrification tower 2, which increases the movement distance of the smoke in the denitrification tower 2, increases the reaction time, and makes the reaction more complete. The diameter of the smoke pipe 1 is consistent with the boiler smoke pipe.

[0035] As an implementable embodiment, the denitrification tower 2 is 22 meters high, and the diameter of the tower is designed according to the air volume and the wind speed of 10 meters. A maintenance observation hole is set on the denitrification tower 2 at 3 meters, 6 meters and 10 meters away from the bottom of the tower.

[0036] Use process as Figure 2 As shown, hypochlorous acid water, a low-temperature denitrifier, is first prepared using a raw material storage tank 4, a metering pump 6, and a reaction tank 5. This low-temperature denitrifier is then transported to the spray device 7 of the denitrification tower 2 via a liquid inlet pump and a liquid inlet pipe. The low-temperature denitrifier is then converted from liquid to an ultrafine mist by a high-pressure micron atomizer spray gun and evenly sprayed into the denitrification tower 2. Kiln flue gas enters the bottom of the denitrification tower 2 via the flue gas duct 1, moving upwards and mixing with the atomized low-temperature denitrifier. The denitrifier is vaporized by the high-temperature flue gas. In the U-shaped duct of the denitrification tower 2, it fully contacts and reacts with nitrogen oxides in the flue gas, producing non-toxic nitrogen and water. This nitrogen then enters the bag filter 3 along with the flue gas through the flue gas duct 1. In the bag filter 3, the non-toxic nitrogen is discharged into the chimney. Fly ash particles and various salts generated during denitrification and desulfurization in the flue gas are filtered, absorbed, captured, collected, and purified by the bag filter 3.

[0037] The flue gas at the flue gas outlet of bag filter 3 was tested and the nitrogen oxide content was less than 50mg / m 3 , the sulfur dioxide content is less than 30mg / m 3 .

[0038] Table 1 is a comparison of the industrial kiln dry low-temperature denitrification method SCER of the present invention with the traditional SCR denitrification method and SNCR denitrification method.

[0039] Table 1. Comparison of three industrial furnace denitrification methods

[0040]

[0041] As can be seen from Table 1, compared with traditional SCR and SNCR denitrification methods, the present invention has great advantages in safety, environmental protection and denitrification rate.

[0042] Example 2

[0043] This embodiment is basically the same as Example 1, and the similarities are not repeated here. The difference lies in the preparation method of the hypochlorous acid water low-temperature denitrification agent: 100 kg of deionized water is taken, 200 g of aminosulfonic acid and 300 g of citric acid are added to prepare an acidic aqueous solution with a pH value of 3 to 4, 7 kg of the prepared acidic aqueous solution is taken, and 3 kg of sodium hypochlorite with a content of 10% is added to prepare a hypochlorous acid water low-temperature denitrification agent with a concentration of 30,000 ppm.

[0044] Example 3

[0045] This embodiment is basically the same as Example 1, and the similarities are not repeated here. The difference lies in the preparation method of the hypochlorous acid water low-temperature denitrification agent: 100 kg of deionized water is taken, 200 g of aminosulfonic acid and 300 g of citric acid are added to prepare an acidic aqueous solution with a pH value of 3 to 4, 8.8 kg of the prepared acidic aqueous solution is taken, and 1.2 kg of sodium chlorite with a content of 25% is added to prepare a hypochlorous acid water low-temperature denitrification agent with a concentration of 30,000 ppm.

[0046] The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are considered to be within the scope of protection of the present invention.

Claims

1. A device for dry low-temperature denitration of an industrial kiln, comprising a denitration tower (2) and a bag filter (3) connected via a flue gas duct (1), characterized in that: It also includes a denitrification agent generating device, the denitrification agent generating device is connected to the denitrification tower (2) via a liquid inlet pipe, the denitrification tower (2) is an inverted U-shaped structure, a spray device (7) is provided inside, the spray device (7) is connected to the liquid inlet pipe, and the smoke inlet and smoke outlet of the denitrification tower (2) are symmetrically arranged at the lower part of the denitrification tower (2); The denitrification agent is hypochlorous acid water prepared by combining one or more of sodium hypochlorite, sodium chlorite and chlorine dioxide with deionized water in the presence of a catalyst; the catalyst is an aqueous solution of aminosulfonic acid and citric acid.

2. The device for dry low-temperature denitrification of an industrial kiln according to claim 1, characterized in that: The denitrification agent generating device comprises a plurality of raw material storage tanks (4) and reaction tanks (5), and each of the raw material storage tanks (4) is independently connected to the reaction tank (5) via a raw material pipe.

3. The device for dry low-temperature denitrification of an industrial kiln according to claim 2, characterized in that: Each of the raw material pipes is provided with a metering pump (6), and the liquid inlet pipe is provided with a liquid inlet pump.

4. The device for dry low-temperature denitrification of an industrial kiln according to claim 1, characterized in that: The spray device (7) comprises a plurality of spray pipes, and each of the spray pipes is equipped with a plurality of high-pressure micron atomizing spray guns.

5. The device for dry low-temperature denitrification of an industrial kiln according to claim 1, characterized in that: The diameter of the flue gas duct (1) is consistent with that of the boiler flue gas pipe.

6. The device for dry low-temperature denitrification of an industrial kiln according to claim 1, characterized in that: The denitrification tower (2) is 22 m high and is provided with a plurality of maintenance observation holes.

7. A denitration method using the device according to claim 2 or 3, characterized in that: The following steps are involved: A. Prepare a denitrification agent in a reaction tank (5) and transport it to a spray device (7) through a liquid inlet pump and a liquid inlet pipe; B. The flue gas from the industrial kiln enters the bottom of the denitrification tower (2) through the flue gas pipe (1) and mixes with the denitrification agent after passing through the high-pressure micron atomization spray gun. The vaporized denitrification agent fully contacts and reacts with the nitrogen oxides in the flue gas; C. The flue gas after the reaction in the denitrification tower (2) enters the bag dust collector (3) through the smoke outlet and the smoke pipe (1), and the non-toxic nitrogen is sent to the chimney for discharge. The impurities in the flue gas are filtered, absorbed, captured, collected and purified by the bag dust collector (3).

8. The denitration method according to claim 7, characterized in that: The concentration of the hypochlorous acid water is 30000 ppm.

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