Sintering flue gas desulfurization and denitrification ultra-low emission treatment system and method thereof

Abstract

The invention discloses a sintering flue gas desulfurization and denitrification ultra-low emission treatment system and a method thereof.The system comprises an absorption tower and an exhaust port formed in the top of the absorption tower, an annular shell is arranged on the periphery of the lower portion of the absorption tower, and the interior of the shell is divided into an annular dust removal area, an annular pre-desulfurization area and an annular oxidation area; a plurality of long-arc-shaped dust collection electrodes are arranged in the dust removal area in parallel at intervals, a plurality of corona wires are circumferentially and uniformly distributed between every two adjacent dust collection electrodes, a spray head is arranged at the top of the pre-desulfurization area, a long-arc-shaped gas spraying pipe is arranged at the center in the oxidation area, and a spraying assembly and an active coke layer are sequentially arranged in the absorption tower above the shell from bottom to top; and the exhaust port is connected with a bag-type dust collector. The treatment method comprises the steps of electric precipitation, pre-desulfurization, flue gas oxidation, desulfurization and denitrification, cloth bag dust removal and the like. The method has the advantages that the dual effects of desulfurization and denitrification can be realized at the same time, the operation cost is low, and the national emission standard can be met.

Description

Technical Field

[0001] The present invention belongs to the technical field of sintering flue gas desulfurization and denitrification, and in particular relates to an ultra-low emission treatment system and method for sintering flue gas desulfurization and denitrification. Background Art

[0002] my country's steel enterprises mainly focus on the long process of "sintering-blast furnace-converter-continuous casting" smelting production. The sintering process is the raw material supply process for blast furnace ironmaking. Almost all large steel enterprises have sintering processes, which is one of the largest pollution sources of steel enterprises. The average SO2 concentration in the sintering flue gas generated by the sintering process is 600-1000 mg / Nm 3 Above, NOx concentration is 300~400mg / Nm 3 However, my country's flue gas emission standards require SO2 concentration to be 180mg / Nm 3 Within, NOx concentration is 300mg / Nm 3 Within.

[0003] There are two main traditional desulfurization methods: wet and dry. Currently, more than 60% of sintering desulfurization uses the wet desulfurization process of limestone-gypsum. The gypsum produced by this desulfurization method is not well sold, the production process is complicated, and there is a certain amount of water consumption. It is not the best desulfurization process. For flue gas denitrification, the traditional selective catalytic reduction denitrification process (SCR) has an operating temperature range of 300℃ to 450℃, while the selective non-catalytic reduction denitrification process (SNCR) has an operating temperature range of 950℃ to 1150℃. If a separate SCR or SNCR device is used to denitrify the desulfurized sintering flue gas, it is necessary to reheat the sintering flue gas with a temperature below 200℃. The operating temperature range of the SNCR process is much higher than the sintering flue gas temperature. It is unrealistic to use reheat treatment, and the SCR process is expensive and difficult to be accepted by my country's steel companies. At present, it is not realistic to directly treat the flue gas after limestone-gypsum desulfurization with low-temperature catalyst denitrification, because the moisture content in the flue gas after traditional limestone-gypsum wet desulfurization is very high, and the water volume content of the discharged flue gas is generally above 7%, which will seriously affect the use effect of the catalyst. The traditional limestone-gypsum desulfurization and SCR denitrification process is also not feasible. In summary, the existing simultaneous desulfurization and denitrification system cannot meet the treatment needs of sintering flue gas, and still has the disadvantages of low efficiency of integrated desulfurization and denitrification, complex process, and high equipment maintenance cost. If a separate SCR or SNCR device is used for denitrification, the construction cost will be too high and the enterprise cannot afford it; secondly, when using wet desulfurization, an absorption tower will be set up, and in order to have a better desulfurization effect, multiple spray layers will be set up, which increases the height and operation cost of the absorption tower, and the operation of the high tower has greater safety hazards. Therefore, it is an objective need to develop an ultra-low emission treatment system and method for sintering flue gas desulfurization and denitrification that can achieve the dual effects of desulfurization and denitrification at the same time, has low operating costs, and can meet national emission standards. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the purpose of the present invention is to provide a sintering flue gas desulfurization and denitrification ultra-low emission treatment system and method which can achieve the dual effects of desulfurization and denitrification at the same time, has low operating cost and can meet national emission standards.

[0005] The ultra-low emission treatment system for sintering flue gas desulfurization and denitrification described in the present invention comprises an absorption tower and an exhaust port arranged at the top of the absorption tower, an annular shell is arranged around the lower part of the absorption tower, and the interior of the shell is divided into an annular dust removal zone, a pre-desulfurization zone and an oxidation zone from the outside to the inside by two annular cylinders, each of which is an annular area is provided with a partition, and the two sides of the partition are respectively an air inlet side and an air outlet side, and an air vent connecting two adjacent areas is provided on the annular cylinder close to the air outlet side of the partition, and an air inlet is provided on the shell close to the air inlet side of the dust removal zone partition, a plurality of long arc dust collecting electrodes are arranged in parallel at intervals in the dust removal zone, and a plurality of corona wires are evenly distributed on the circumference between two adjacent dust collecting electrodes, a nozzle is arranged on the top of the pre-desulfurization zone, and a long arc jet pipe is arranged at the center of the oxidation zone, a spray assembly and an activated coke layer are arranged in sequence from bottom to top in the absorption tower above the shell, and a bag dust collector is connected to the exhaust port.

[0006] Furthermore, the effective flow areas of the dust removal zone, the pre-desulfurization zone and the oxidation zone are all larger than the effective flow area of ​​the air inlet.

[0007] Furthermore, aerators are provided in the dust removal area near the air inlet and in the absorption tower between the shell and the spray assembly.

[0008] Furthermore, a plurality of baffles are evenly distributed along the circumference of the lower part of the pre-desulfurization zone, and through holes are processed at the lower ends of the baffles.

[0009] Furthermore, the activated coke layer includes an inclined perforated plate and activated coke particles located on the perforated plate. A screw conveyor is vertically arranged on one side of the absorption tower. The feed port at the bottom of the screw conveyor is connected to the side wall of the absorption tower above the lower end of the perforated plate, and the discharge port at the top of the screw conveyor is connected to the side wall of the absorption tower above the activated coke particles.

[0010] Furthermore, a vibrator is installed on the orifice plate.

[0011] The present invention provides a method for treating a sintering flue gas desulfurization and denitrification ultra-low emission treatment system, comprising the following steps: ①. Electrostatic precipitator: The collected sintering flue gas is uniformly introduced into the dust removal area through the air inlet, and then divided into multiple streams. The multiple streams enter the area between two adjacent dust collecting electrodes respectively, and flow in a circular manner in each area. During the flow, the dust in the sintering flue gas is separated. The voltage between the dust collecting electrode and the corona wire is 12000V~15000V, the distance between two adjacent dust collecting electrodes is 50mm~70mm, the air flow velocity of the sintering flue gas is 2m / s~3.5m / s, and the dust concentration in the sintering flue gas is controlled to be ≤20mg / m 3 ; ② Pre-desulfurization: The sintering flue gas after dust removal in step ① enters the pre-desulfurization zone and flows in a circular manner in the pre-desulfurization zone. At the same time, desulfurization liquid is sprayed from the nozzle to preliminarily remove sulfur dioxide in the sintering flue gas. The air flow velocity of the sintering flue gas is 2m / s~3.5m / s, and the sulfur dioxide concentration in the sintering flue gas is ≤100mg / m 3 ; ③. Flue gas oxidation: the sintering flue gas after pre-desulfurization in step ② enters the oxidation zone and flows in a circular manner in the oxidation zone. At the same time, ozone is ejected from the jet pipe to oxidize the sintering flue gas. The molar ratio of ozone to NO in the sintering flue gas is controlled to be 0.50-0.70; ④. Desulfurization and denitrification: The oxidized sintering flue gas is passed into the lower part of the absorption tower, and active lime powder, catalyst sodium chlorite and water are sprayed out from the spray assembly. After the sintering flue gas reacts with the active lime powder and water, it enters the activated coke layer. The sulfur dioxide concentration in the sintering flue gas after desulfurization and denitrification treatment is ≤15mg / m 3 , nitrogen oxide concentration ≤45mg / m 3 ; ⑤. Bag dust removal: The sintering flue gas after desulfurization and denitrification treatment in step ④ is passed into the bag dust collector from the exhaust port, and the dust concentration in the sintering flue gas at the bag dust collector outlet is controlled to be ≤4mg / m 3 .

[0012] Furthermore, in step ②, the desulfurization liquid is any one of sodium hydroxide solution, calcium hydroxide solution, potassium hydroxide solution or lime milk.

[0013] Furthermore, in step ④, the mass ratio of active lime powder, catalyst sodium chlorite and water is 50:1:5.

[0014] The beneficial effects of the present invention are: 1. The present invention sequentially performs electrostatic precipitator, preliminary desulfurization, oxidation and final desulfurization and denitrification treatment on the sintering flue gas. When performing electrostatic precipitator, the sintering flue gas is diverted to improve the dust removal efficiency and has a good dust removal effect. Then, the sintering flue gas is desulfurized by using a desulfurization liquid, and the sintering flue gas is preliminarily desulfurized to reduce the sulfur dioxide content in the sintering flue gas. Then, ozone is introduced into the sintering flue gas, and the ozone reacts with the nitride in the sintering flue gas to oxidize the nitrogen monoxide in the sintering flue gas to nitrogen dioxide. Then, the sintering flue gas is introduced into an absorption tower, and active lime powder and sodium chlorite are sprayed downward through a spray assembly. and water, wherein sodium chlorite is a catalyst. Under the catalytic action of sodium chlorite, the sintering flue gas comes into contact with active lime powder and water to react. The sulfide in the sintering flue gas is converted into calcium sulfate and calcium sulfite after desulfurization, and the nitride is converted into calcium nitrate after denitrification, thereby removing the sulfide and nitride in the sintering flue gas. Finally, the sintering flue gas enters the activated coke layer, and the activated coke particles are used to further purify the sintering flue gas, and further adsorb the sulfide and nitride in the sintering flue gas. Finally, the sintering flue gas is passed into the bag filter for the final dust removal treatment to meet the ultra-low emission requirements of desulfurization, denitrification and dust removal of the sintering flue gas.

[0015] 2. The present invention adopts a low-temperature semi-dry method to desulfurize and denitrify the sintering flue gas. Compared with the traditional SCR or SNCR treatment method, during the entire treatment process, there is no need to heat the sintering flue gas and no additional energy consumption. The entire removal and absorption reaction can be completed at the normal temperature of the sintering flue gas. There is no problem of environmental pollution to water bodies and soil caused by calcium nitrite solution when using wet treatment methods. Most of the products are calcium sulfate, which can be directly used as building materials. This basically solves the problem of secondary pollution to the environment caused by desulfurization and denitrification products in traditional treatment methods.

[0016] Thirdly, it solves the existing problems of only being able to desulfurize and denitrify separately, or being able to desulfurize and denitrify in steps but with complex processes, large equipment investment, low removal efficiency and low operating costs. The present invention integrates the oxidation, desulfurization and denitrification of sintering flue gas into one device, shortens the process of long-distance transportation of sintering flue gas, reduces the investment in flue gas transportation pipelines, has higher processing efficiency, reduces the number of spray layers in the absorption tower, reduces the height and operating cost of the absorption tower, and improves the safety of the absorption tower operation.

[0017] In summary, the equipment of the present invention is provided with an integrated structure, and adopts a low-temperature semi-dry method to comprehensively treat the sintering flue gas, shortening the process and flow of the sintering flue gas treatment, reducing the investment and operation cost of the equipment, and improving the safety performance of the equipment operation. An integrated device is used to simultaneously achieve the dual effects of desulfurization and denitrification of the sintering flue gas. At the same time, the entire treatment process does not require heating and temperature increase of the sintering flue gas, and the desulfurization and denitrification operation can be completed at the conventional temperature of the sintering flue gas. Under the premise of ensuring the efficiency and effect of desulfurization and denitrification, the consumption of additional energy is avoided, and the cost of desulfurization and denitrification of the sintering flue gas is reduced. At the same time, the generated products can be directly used for building materials, avoiding the problem of secondary pollution to the environment, and the discharged flue gas can meet the requirements of national standards, achieving the ultra-low emission purpose of desulfurization and denitrification of sintering flue gas and dust removal. The present invention has the advantages of being able to simultaneously achieve the dual effects of desulfurization and denitrification, low operating cost, and being able to meet national emission standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 for Figure 1 Schematic diagram of the enlarged structure of AA; In the figure: 1-absorption tower, 2-shell, 3-annular cylinder, 4-dust removal zone, 5-pre-desulfurization zone, 6-oxidation zone, 7-partition, 8-air vent, 9-air inlet, 10-dust collecting electrode, 11-corona wire, 12-nozzle, 13-injection pipe, 14-spray assembly, 15-activated coke layer, 16-bag collector, 17-aerator, 18-baffle, 19-orifice plate, 20-screw conveyor, 21-vibrator. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the embodiments and accompanying drawings, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention. Example 1

[0020] like Figures 1-2As shown, a sintering flue gas desulfurization and denitrification ultra-low emission treatment system of the present invention comprises an absorption tower 1 and an exhaust port arranged at the top of the absorption tower 1. An annular shell 2 is arranged around the lower part of the absorption tower 1. The interior of the shell 2 is divided into an annular dust removal zone 4, a pre-desulfurization zone 5 and an oxidation zone 6 from the outside to the inside by two annular tubes 3. The oxidation zone 6 is used for oxidation treatment of the sintering flue gas. Under the ozone concentration, ozone does not react with sulfur dioxide and carbon monoxide in the flue gas, but only reacts with NO, the main component of nitrogen oxides in the sintering flue gas. NO in the sintering flue gas accounts for more than 90% of the mass content of nitrogen oxides in the sintering flue gas. NO is quickly oxidized to NO2. According to the study of reaction kinetics, the reaction rate constant is the largest, and the reaction can be completed within 0.05 seconds. The oxidation of NO can be completed quickly. In each annular area, A partition 7 is provided, and the two sides of the partition 7 are respectively an air inlet side and an air outlet side. An air vent 8 connecting two adjacent areas is provided on the annular cylinder 3 near the air outlet side of the partition 7, and an air inlet 9 is provided on the shell 2 near the air inlet side of the partition 7 in the dust removal area 4. A plurality of long arc dust collecting electrodes 10 are arranged in parallel and at intervals in the dust removal area 4, and a plurality of corona wires 11 are evenly distributed on the circumference between two adjacent dust collecting electrodes 10. A nozzle 12 is provided on the top of the pre-desulfurization area 5, and a long arc-shaped air injection pipe 13 is provided at the center of the oxidation area 6. A spray assembly 14 and an active coke layer 15 are sequentially arranged from bottom to top in the absorption tower 1 above the shell 2. The structures of the spray assembly 14 and the active coke layer 15 are both existing technologies. The indicators of the active coke are as follows: moisture content <3%, ash content <10%, volatile matter 2% to 5%, and compressive strength >300N / cm 2 , wear resistance>98%, particle size between 5mm and 12mm, bulk density 580kg / m 3 ~680kg / m 3 , iodine adsorption value>420mg / g, sulfur capacity>18mg / g, and a bag filter 16 is connected to the exhaust port.

[0021] The effective flow areas of the dust removal zone 4, the pre-desulfurization zone 5 and the oxidation zone 6 are all larger than the effective flow area of ​​the air inlet 9. When the sintering flue gas flows into the dust removal zone 4 from the air inlet 9, the flow rate of the sintering flue gas will slow down due to the increase in the effective flow area, thereby ensuring sufficient time for dust removal, pre-desulfurization and oxidation treatment of the sintering flue gas.

[0022] A gas homogenizer 17 is provided in the dust removal area 4 near the air inlet 9 and in the absorption tower 1 between the shell 2 and the spray assembly 14. The gas homogenizer 17 is a prior art and is used for evenly distributing the sintering flue gas.

[0023] Several baffles 18 are evenly distributed along the circumference of the lower part of the pre-desulfurization zone 5, and the lower end of the baffle 18 is processed with a through hole. The sintering flue gas flows in the pre-desulfurization zone 5 in a circular direction along the pre-desulfurization zone 5. During the flow, since the desulfurization liquid falls from the top, the sintering flue gas located in the upper part of the pre-desulfurization zone 5 can fully contact with the desulfurization liquid, but the sintering flue gas located in the lower part of the pre-desulfurization zone 5 cannot fully contact with the desulfurization liquid, thereby reducing the desulfurization effect. In order to improve this problem, the baffle 18 is set. When the sintering flue gas located in the lower part of the pre-desulfurization zone 5 hits the baffle 18, it changes its flow direction due to being blocked and flows toward the upper part of the zone, thereby promoting the contact between the sintering flue gas and the desulfurization liquid and improving the desulfurization effect of the sintering flue gas.

[0024] The activated coke layer 15 includes an inclined orifice plate 19 and activated coke particles on the orifice plate 19. A screw conveyor 20 is vertically arranged on one side of the absorption tower 1. The feed port at the lower part of the screw conveyor 20 is connected to the side wall of the absorption tower 1 above the lower end of the orifice plate 19, and the discharge port at the upper part of the screw conveyor 20 is connected to the side wall of the absorption tower 1 above the activated coke particles. During the use of the present invention, it is found that the active coke particles are treated in a static state, which is not conducive to the absorption of nitrides and sulfides in the sintering flue gas. In order to improve this situation, a screw conveyor 20 is set. The active coke particles in the active coke layer 15 will enter the screw conveyor 20 from the lower end of the orifice plate 19, and the screw conveyor 20 drives the active coke particles to rise, and then is put into the upper part of the active coke layer 15 from above, so that the active coke particles in the active coke layer 15 are treated in a continuously circulating flow state, and the flow state in the absorption tower 1 is opposite to the flow direction of the sintering flue gas, and the two are in reverse contact, thereby improving the desulfurization and denitrification effect of the active coke particles on the sintering flue gas.

[0025] A vibrator 21 is installed on the orifice plate 19. During operation, the activated coke particles flow toward the lower end along the inclined orifice plate 19 by their own gravity. However, in actual use, it is found that there are problems such as flow dead corners and blockages, which affect the continuous flow of the activated coke particles. In order to solve this problem, a vibrator 21 is provided to promote the flow of the activated coke particles and prevent blockage.

[0026] A treatment method of a sintering flue gas desulfurization and denitrification ultra-low emission treatment system of the present invention comprises the following steps: ①, Electrostatic precipitator: The uniformly collected sintering flue gas is uniformly introduced into the dust removal area 4 through the air inlet 9, and then divided into multiple streams. The multiple streams enter the area between two adjacent dust collecting electrodes 10 respectively, and flow in a circular manner in each area. During the flow process, the dust in the sintering flue gas is separated. Among them, the voltage between the dust collecting electrode 10 and the corona wire 11 is 12000 volts, the distance between two adjacent dust collecting electrodes 10 is 50mm, the air flow velocity of the sintering flue gas is 2m / sm / s, and the dust concentration in the sintering flue gas is 15mg / m 3 ; ② Pre-desulfurization: The sintering flue gas after dust removal in step ① enters the pre-desulfurization zone 5 and flows in a circular manner in the pre-desulfurization zone 5. At the same time, a desulfurization liquid is sprayed from the nozzle 12. The desulfurization liquid is any one of sodium hydroxide solution, calcium hydroxide solution, potassium hydroxide solution or lime milk to preliminarily remove sulfur dioxide in the sintering flue gas. The air flow velocity of the sintering flue gas is 2m / s, and the sulfur dioxide concentration in the sintering flue gas is 95mg / m 3 ; ③. Flue gas oxidation: the sintering flue gas after pre-desulfurization in step ② enters the oxidation zone 6 and flows in a circular manner in the oxidation zone 6. At the same time, ozone is sprayed from the injection pipe 13 to oxidize the sintering flue gas. The molar ratio of ozone to NO in the sintering flue gas is controlled to be 0.50. ④ Desulfurization and denitrification: The oxidized sintering flue gas is passed into the lower part of the absorption tower 1, and active lime powder, catalyst sodium chlorite and water are sprayed from the spray assembly 14. The mass ratio of active lime powder, catalyst sodium chlorite and water is 50:1:5. After the sintering flue gas reacts with the active lime powder and water, it enters the activated coke layer 15. The sulfur dioxide concentration in the sintering flue gas after desulfurization and denitrification treatment is 11 mg / m 3 , nitrogen oxide concentration ≤39mg / m 3 ; ⑤. Bag dust removal: The sintering flue gas after desulfurization and denitrification treatment in step ④ is passed through the exhaust port to the bag dust collector 16, and the dust concentration in the sintering flue gas at the outlet of the bag dust collector 16 is controlled to be 4mg / m 3 .

[0027] It has been verified in practice that the present invention uses an integrated device to achieve the dual effects of desulfurization and denitrification of sintering flue gas. After the sintering flue gas is treated, it is tested that the sulfur dioxide concentration is 11 mg / m 3 , the nitrogen oxide concentration is 39mg / m 3 , dust concentration is 4mg / m 3 , which can better meet the requirements of national standards and achieve the ultra-low emission goals of sintering flue gas desulfurization, denitrification and dust removal. Example 2

[0028] like Figures 1-2As shown, a sintering flue gas desulfurization and denitrification ultra-low emission treatment system of the present invention comprises an absorption tower 1 and an exhaust port arranged at the top of the absorption tower 1. An annular shell 2 is arranged around the lower part of the absorption tower 1. The interior of the shell 2 is divided into an annular dust removal zone 4, a pre-desulfurization zone 5 and an oxidation zone 6 from the outside to the inside by two annular tubes 3. The oxidation zone 6 is used for oxidation treatment of the sintering flue gas. Under the ozone concentration, ozone does not react with sulfur dioxide and carbon monoxide in the flue gas, but only reacts with NO, the main component of nitrogen oxides in the sintering flue gas. NO in the sintering flue gas accounts for more than 90% of the mass content of nitrogen oxides in the sintering flue gas. NO is quickly oxidized to NO2. According to the study of reaction kinetics, the reaction rate constant is the largest, and the reaction can be completed within 0.05 seconds. The oxidation of NO can be completed quickly. In each annular area, A partition 7 is provided, and the two sides of the partition 7 are respectively an air inlet side and an air outlet side. An air vent 8 connecting two adjacent areas is provided on the annular cylinder 3 near the air outlet side of the partition 7, and an air inlet 9 is provided on the shell 2 near the air inlet side of the partition 7 in the dust removal area 4. A plurality of long arc dust collecting electrodes 10 are arranged in parallel and at intervals in the dust removal area 4, and a plurality of corona wires 11 are evenly distributed on the circumference between two adjacent dust collecting electrodes 10. A nozzle 12 is provided on the top of the pre-desulfurization area 5, and a long arc-shaped air injection pipe 13 is provided at the center of the oxidation area 6. A spray assembly 14 and an active coke layer 15 are sequentially arranged from bottom to top in the absorption tower 1 above the shell 2. The structures of the spray assembly 14 and the active coke layer 15 are both existing technologies. The indicators of the active coke are as follows: moisture content <3%, ash content <10%, volatile matter 2% to 5%, and compressive strength >300N / cm 2 , wear resistance>98%, particle size between 5mm and 12mm, bulk density 580kg / m 3 ~680kg / m 3 , iodine adsorption value>420mg / g, sulfur capacity>18mg / g, and a bag filter 16 is connected to the exhaust port.

[0029] The effective flow areas of the dust removal zone 4, the pre-desulfurization zone 5 and the oxidation zone 6 are all larger than the effective flow area of ​​the air inlet 9. When the sintering flue gas flows into the dust removal zone 4 from the air inlet 9, the flow rate of the sintering flue gas will slow down due to the increase in the effective flow area, thereby ensuring sufficient time for dust removal, pre-desulfurization and oxidation treatment of the sintering flue gas.

[0030] A gas homogenizer 17 is provided in the dust removal area 4 near the air inlet 9 and in the absorption tower 1 between the shell 2 and the spray assembly 14. The gas homogenizer 17 is a prior art and is used for evenly distributing the sintering flue gas.

[0031] Several baffles 18 are evenly distributed along the circumference of the lower part of the pre-desulfurization zone 5, and the lower end of the baffle 18 is processed with a through hole. The sintering flue gas flows in the pre-desulfurization zone 5 in a circular direction along the pre-desulfurization zone 5. During the flow, since the desulfurization liquid falls from the top, the sintering flue gas located in the upper part of the pre-desulfurization zone 5 can fully contact with the desulfurization liquid, but the sintering flue gas located in the lower part of the pre-desulfurization zone 5 cannot fully contact with the desulfurization liquid, thereby reducing the desulfurization effect. In order to improve this problem, the baffle 18 is set. When the sintering flue gas located in the lower part of the pre-desulfurization zone 5 hits the baffle 18, it changes its flow direction due to being blocked and flows toward the upper part of the zone, thereby promoting the contact between the sintering flue gas and the desulfurization liquid and improving the desulfurization effect of the sintering flue gas.

[0032] The activated coke layer 15 includes an inclined orifice plate 19 and activated coke particles on the orifice plate 19. A screw conveyor 20 is vertically arranged on one side of the absorption tower 1. The feed port at the lower part of the screw conveyor 20 is connected to the side wall of the absorption tower 1 above the lower end of the orifice plate 19, and the discharge port at the upper part of the screw conveyor 20 is connected to the side wall of the absorption tower 1 above the activated coke particles. During the use of the present invention, it is found that the active coke particles are treated in a static state, which is not conducive to the absorption of nitrides and sulfides in the sintering flue gas. In order to improve this situation, a screw conveyor 20 is set. The active coke particles in the active coke layer 15 will enter the screw conveyor 20 from the lower end of the orifice plate 19, and the screw conveyor 20 drives the active coke particles to rise, and then is put into the upper part of the active coke layer 15 from above, so that the active coke particles in the active coke layer 15 are treated in a continuously circulating flow state, and the flow state in the absorption tower 1 is opposite to the flow direction of the sintering flue gas, and the two are in reverse contact, thereby improving the desulfurization and denitrification effect of the active coke particles on the sintering flue gas.

[0033] A vibrator 21 is installed on the orifice plate 19. During operation, the activated coke particles flow toward the lower end along the inclined orifice plate 19 by their own gravity. However, in actual use, it is found that there are problems such as flow dead corners and blockages, which affect the continuous flow of the activated coke particles. In order to solve this problem, a vibrator 21 is provided to promote the flow of the activated coke particles and prevent blockage.

[0034] A treatment method of a sintering flue gas desulfurization and denitrification ultra-low emission treatment system of the present invention comprises the following steps: ①, Electrostatic precipitator: The uniformly collected sintering flue gas is uniformly introduced into the dust removal area 4 through the air inlet 9, and then divided into multiple streams. The multiple streams enter the area between two adjacent dust collecting electrodes 10 respectively, and flow in a circular manner in each area. During the flow process, the dust in the sintering flue gas is separated. The voltage between the dust collecting electrode 10 and the corona wire 11 is 13000 volts, the distance between two adjacent dust collecting electrodes 10 is 60 mm, the air flow velocity of the sintering flue gas is 3 m / s, and the dust concentration in the sintering flue gas is controlled to be 10 mg / m 3 ; ② Pre-desulfurization: The sintering flue gas after dust removal in step ① enters the pre-desulfurization zone 5 and flows in a circular manner in the pre-desulfurization zone 5. At the same time, a desulfurization liquid is sprayed from the nozzle 12. The desulfurization liquid is any one of sodium hydroxide solution, calcium hydroxide solution, potassium hydroxide solution or lime milk to preliminarily remove sulfur dioxide in the sintering flue gas. The air flow velocity of the sintering flue gas is 3m / s, and the sulfur dioxide concentration in the sintering flue gas is controlled to be 90mg / m 3 ; ③. Flue gas oxidation: the sintering flue gas after pre-desulfurization in step ② enters the oxidation zone 6 and flows in a circular manner in the oxidation zone 6. At the same time, ozone is ejected from the injection pipe 13 to oxidize the sintering flue gas. The molar ratio of ozone to NO in the sintering flue gas is controlled to be 0.60. ④ Desulfurization and denitrification: The oxidized sintering flue gas is passed into the lower part of the absorption tower 1, and active lime powder, catalyst sodium chlorite and water are sprayed from the spray assembly 14. The mass ratio of active lime powder, catalyst sodium chlorite and water is 50:1:5. After the sintering flue gas reacts with the active lime powder and water, it enters the activated coke layer 15. The sulfur dioxide concentration in the sintering flue gas after desulfurization and denitrification treatment is 13mg / m 3 , nitrogen oxide concentration ≤36mg / m 3 ; ⑤. Bag dust removal: The sintering flue gas after desulfurization and denitrification treatment in step ④ is passed through the bag dust collector 16 from the exhaust port, and the dust concentration in the sintering flue gas at the outlet of the bag dust collector 16 is controlled to be ≤3.5mg / m 3 .

[0035] It has been verified in practice that the present invention uses an integrated device to achieve the dual effects of desulfurization and denitrification of sintering flue gas. After the sintering flue gas is treated, it is tested that the sulfur dioxide concentration is 13mg / m 3 , nitrogen oxide concentration is 36mg / m 3 , dust concentration is 3.5mg / m 3 , which can better meet the requirements of national standards and achieve the ultra-low emission goals of sintering flue gas desulfurization, denitrification and dust removal. Example 3

[0036] like Figures 1-2As shown, a sintering flue gas desulfurization and denitrification ultra-low emission treatment system of the present invention comprises an absorption tower 1 and an exhaust port arranged at the top of the absorption tower 1. An annular shell 2 is arranged around the lower part of the absorption tower 1. The interior of the shell 2 is divided into an annular dust removal zone 4, a pre-desulfurization zone 5 and an oxidation zone 6 from the outside to the inside by two annular tubes 3. The oxidation zone 6 is used for oxidation treatment of the sintering flue gas. Under the ozone concentration, ozone does not react with sulfur dioxide and carbon monoxide in the flue gas, but only reacts with NO, the main component of nitrogen oxides in the sintering flue gas. NO in the sintering flue gas accounts for more than 90% of the mass content of nitrogen oxides in the sintering flue gas. NO is quickly oxidized to NO2. According to the study of reaction kinetics, the reaction rate constant is the largest, and the reaction can be completed within 0.05 seconds. The oxidation of NO can be completed quickly. In each annular area, A partition 7 is provided, and the two sides of the partition 7 are respectively an air inlet side and an air outlet side. An air vent 8 connecting two adjacent areas is provided on the annular cylinder 3 near the air outlet side of the partition 7, and an air inlet 9 is provided on the shell 2 near the air inlet side of the partition 7 in the dust removal area 4. A plurality of long arc dust collecting electrodes 10 are arranged in parallel and at intervals in the dust removal area 4, and a plurality of corona wires 11 are evenly distributed on the circumference between two adjacent dust collecting electrodes 10. A nozzle 12 is provided on the top of the pre-desulfurization area 5, and a long arc-shaped air injection pipe 13 is provided at the center of the oxidation area 6. A spray assembly 14 and an active coke layer 15 are sequentially arranged from bottom to top in the absorption tower 1 above the shell 2. The structures of the spray assembly 14 and the active coke layer 15 are both existing technologies. The indicators of the active coke are as follows: moisture content <3%, ash content <10%, volatile matter 2% to 5%, and compressive strength >300N / cm 2 , wear resistance>98%, particle size between 5mm and 12mm, bulk density 580kg / m 3 ~680kg / m 3 , iodine adsorption value>420mg / g, sulfur capacity>18mg / g, and a bag filter 16 is connected to the exhaust port.

[0037] The effective flow areas of the dust removal zone 4, the pre-desulfurization zone 5 and the oxidation zone 6 are all larger than the effective flow area of ​​the air inlet 9. When the sintering flue gas flows into the dust removal zone 4 from the air inlet 9, the flow rate of the sintering flue gas will slow down due to the increase in the effective flow area, thereby ensuring sufficient time for dust removal, pre-desulfurization and oxidation treatment of the sintering flue gas.

[0038] A gas homogenizer 17 is provided in the dust removal area 4 near the air inlet 9 and in the absorption tower 1 between the shell 2 and the spray assembly 14. The gas homogenizer 17 is a prior art and is used for evenly distributing the sintering flue gas.

[0039] Several baffles 18 are evenly distributed along the circumference of the lower part of the pre-desulfurization zone 5, and the lower end of the baffle 18 is processed with a through hole. The sintering flue gas flows in the pre-desulfurization zone 5 in a circular direction along the pre-desulfurization zone 5. During the flow, since the desulfurization liquid falls from the top, the sintering flue gas located in the upper part of the pre-desulfurization zone 5 can fully contact with the desulfurization liquid, but the sintering flue gas located in the lower part of the pre-desulfurization zone 5 cannot fully contact with the desulfurization liquid, thereby reducing the desulfurization effect. In order to improve this problem, the baffle 18 is set. When the sintering flue gas located in the lower part of the pre-desulfurization zone 5 hits the baffle 18, it changes its flow direction due to being blocked and flows toward the upper part of the zone, thereby promoting the contact between the sintering flue gas and the desulfurization liquid and improving the desulfurization effect of the sintering flue gas.

[0040] The activated coke layer 15 includes an inclined orifice plate 19 and activated coke particles on the orifice plate 19. A screw conveyor 20 is vertically arranged on one side of the absorption tower 1. The feed port at the lower part of the screw conveyor 20 is connected to the side wall of the absorption tower 1 above the lower end of the orifice plate 19, and the discharge port at the upper part of the screw conveyor 20 is connected to the side wall of the absorption tower 1 above the activated coke particles. During the use of the present invention, it is found that the active coke particles are treated in a static state, which is not conducive to the absorption of nitrides and sulfides in the sintering flue gas. In order to improve this situation, a screw conveyor 20 is set. The active coke particles in the active coke layer 15 will enter the screw conveyor 20 from the lower end of the orifice plate 19, and the screw conveyor 20 drives the active coke particles to rise, and then is put into the upper part of the active coke layer 15 from above, so that the active coke particles in the active coke layer 15 are treated in a continuously circulating flow state, and the flow state in the absorption tower 1 is opposite to the flow direction of the sintering flue gas, and the two are in reverse contact, thereby improving the desulfurization and denitrification effect of the active coke particles on the sintering flue gas.

[0041] A vibrator 21 is installed on the orifice plate 19. During operation, the activated coke particles flow toward the lower end along the inclined orifice plate 19 by their own gravity. However, in actual use, it is found that there are problems such as flow dead corners and blockages, which affect the continuous flow of the activated coke particles. In order to solve this problem, a vibrator 21 is provided to promote the flow of the activated coke particles and prevent blockage.

[0042] A treatment method of a sintering flue gas desulfurization and denitrification ultra-low emission treatment system of the present invention comprises the following steps: ①, Electrostatic precipitator: The uniformly collected sintering flue gas is uniformly introduced into the dust removal area 4 through the air inlet 9, and then divided into multiple streams. The multiple streams enter the area between two adjacent dust collecting electrodes 10 respectively, and flow in a circular manner in each area. During the flow process, the dust in the sintering flue gas is separated. Among them, the voltage between the dust collecting electrode 10 and the corona wire 11 is 15000 volts, the distance between two adjacent dust collecting electrodes 10 is 70 mm, the air flow velocity of the sintering flue gas is 3.5 m / s, and the dust concentration in the sintering flue gas is controlled to be 14 mg / m 3 ; ② Pre-desulfurization: The sintering flue gas after dust removal in step ① enters the pre-desulfurization zone 5 and flows in a circular manner in the pre-desulfurization zone 5. At the same time, a desulfurization liquid is sprayed from the nozzle 12. The desulfurization liquid is any one of sodium hydroxide solution, calcium hydroxide solution, potassium hydroxide solution or lime milk to preliminarily remove sulfur dioxide in the sintering flue gas. The air flow velocity of the sintering flue gas is 3.5m / s, and the sulfur dioxide concentration in the sintering flue gas is controlled to be 80mg / m 3 ; ③. Flue gas oxidation: the sintering flue gas after pre-desulfurization in step ② enters the oxidation zone 6 and flows in a circular manner in the oxidation zone 6. At the same time, ozone is ejected from the injection pipe 13 to oxidize the sintering flue gas. The molar ratio of ozone to NO in the sintering flue gas is controlled to be 0.70. ④ Desulfurization and denitrification: The oxidized sintering flue gas is passed into the lower part of the absorption tower 1, and active lime powder, catalyst sodium chlorite and water are sprayed from the spray assembly 14. The mass ratio of active lime powder, catalyst sodium chlorite and water is 50:1:5. After the sintering flue gas reacts with the active lime powder and water, it enters the activated coke layer 15. The sulfur dioxide concentration in the sintering flue gas after desulfurization and denitrification treatment is 9mg / m 3 , nitrogen oxide concentration 38mg / m 3 ; ⑤. Bag dust removal: The sintering flue gas after desulfurization and denitrification treatment in step ④ is passed through the exhaust port to the bag dust collector 16, and the dust concentration in the sintering flue gas at the outlet of the bag dust collector 16 is controlled to be ≤3mg / m 3 .

[0043] It has been verified in practice that the present invention uses an integrated device to achieve the dual effects of desulfurization and denitrification of sintering flue gas. After the sintering flue gas is treated, it is tested that the sulfur dioxide concentration is 9 mg / m 3 , nitrogen oxide concentration is 38mg / m 3 , dust concentration is 3mg / m 3 , which can better meet the requirements of national standards and achieve the ultra-low emission goals of sintering flue gas desulfurization, denitrification and dust removal.

[0044] In general, the equipment with an integrated structure of the present invention adopts a low-temperature semi-dry method to comprehensively treat the sintering flue gas, shortening the process and flow of sintering flue gas treatment, reducing the investment and operating costs of the equipment, and improving the safety performance of the equipment operation. An integrated device is used to simultaneously achieve the dual effects of desulfurization and denitrification of the sintering flue gas, without the need to heat the sintering flue gas, thereby reducing the treatment cost of the sintering flue gas. After the sintering flue gas is treated by the method of the present invention, the sulfur dioxide concentration, nitrogen oxide concentration and dust concentration can be stably controlled at a relatively low level, achieving the ultra-low emission purpose of desulfurization, denitrification and dust removal of the sintering flue gas, reducing the pollution of the sintering flue gas to the environment, and reducing the secondary pollution of the reaction products to the environment.

Claims

1. A sintering flue gas desulfurization and denitrification ultra-low emission treatment system, comprising an absorption tower (1) and an exhaust port arranged at the top of the absorption tower (1), characterized in that An annular shell (2) is arranged around the lower part of the absorption tower (1), and the interior of the shell (2) is divided into an annular dust removal zone (4), a pre-desulfurization zone (5) and an oxidation zone (6) from the outside to the inside by two annular cylinders (3). A partition (7) is arranged in each annular zone, and the two sides of the partition (7) are respectively an air inlet side and an air outlet side. A vent (8) connecting the two adjacent zones is arranged on the annular cylinder (3) near the air outlet side of the partition (7), and an air inlet (9) connecting the two adjacent zones is arranged on the shell (2) near the air inlet side of the partition (7) of the dust removal zone (4). An air port (9) is provided, in the dust removal zone (4), with a plurality of long arc-shaped dust collecting electrodes (10) arranged in parallel and at intervals, and a plurality of corona wires (11) are evenly distributed on the circumference between two adjacent dust collecting electrodes (10), a nozzle (12) is provided at the top of the pre-desulfurization zone (5), a long arc-shaped air injection pipe (13) is provided at the center of the oxidation zone (6), a spray assembly (14) and an active coke layer (15) are provided in sequence from bottom to top in the absorption tower (1) above the shell (2), and a bag filter (16) is connected to the air port.

2. The ultra-low emission treatment system for desulfurization and denitrification of sintering flue gas according to claim 1 is characterized in that The effective flow areas of the dust removal zone (4), the pre-desulfurization zone (5) and the oxidation zone (6) are all larger than the effective flow area of ​​the air inlet (9).

3. The ultra-low emission treatment system for desulfurization and denitrification of sintering flue gas according to claim 1 is characterized in that A gas homogenizer (17) is provided in the dust removal area (4) near the air inlet (9) and in the absorption tower (1) between the shell (2) and the spray assembly (14).

4. The ultra-low emission treatment system for desulfurization and denitrification of sintering flue gas according to claim 1 is characterized in that A plurality of baffles (18) are evenly distributed along the circumference of the lower part of the pre-desulfurization zone (5), and a through hole is processed at the lower end of the baffle (18).

5. The ultra-low emission treatment system for desulfurization and denitrification of sintering flue gas according to claim 1 is characterized in that The activated coke layer (15) comprises an inclined perforated plate (19) and activated coke particles located on the perforated plate (19); a screw conveyor (20) is vertically arranged on one side of the absorption tower (1); a feed port at the bottom of the screw conveyor (20) is connected to a side wall of the absorption tower (1) above the lower end of the perforated plate (19); and a discharge port at the top of the screw conveyor (20) is connected to a side wall of the absorption tower (1) above the activated coke particles.

6. The ultra-low emission treatment system for desulfurization and denitrification of sintering flue gas according to claim 5 is characterized in that A vibrator (21) is mounted on the orifice plate (19).

7. The method for treating a sintering flue gas desulfurization and denitrification ultra-low emission treatment system according to claim 1, characterized in that: The following steps are involved: ①. Electrostatic precipitator: The uniformly collected sintering flue gas is uniformly introduced into the dust removal zone (4) through the air inlet (9), and then divided into multiple streams. The multiple streams enter the area between two adjacent dust collecting electrodes (10) respectively, and flow in a circular manner in each area. During the flow process, the dust in the sintering flue gas is separated. The voltage between the dust collecting electrode (10) and the corona wire (11) is 12000V to 15000V, the distance between two adjacent dust collecting electrodes (10) is 50mm to 70mm, the air flow velocity of the sintering flue gas is 2m / s to 3.5m / s, and the dust concentration in the sintering flue gas is controlled to be ≤20mg / m 3 ; ② Pre-desulfurization: The sintering flue gas after dust removal in step ① enters the pre-desulfurization zone (5) and flows in a circular manner in the pre-desulfurization zone (5). At the same time, desulfurization liquid is sprayed from the nozzle (12) to preliminarily remove sulfur dioxide in the sintering flue gas. The air flow velocity of the sintering flue gas is 2m / s to 3.5m / s, and the sulfur dioxide concentration in the sintering flue gas is controlled to be ≤100mg / m 3 ; ③. Flue gas oxidation: the sintering flue gas after the pre-desulfurization in step ② enters the oxidation zone (6) and flows in a circular manner in the oxidation zone (6). At the same time, ozone is ejected from the injection pipe (13) to oxidize the sintering flue gas. The molar ratio of ozone to NO in the sintering flue gas is controlled to be 0.50 to 0.

70. ④ Desulfurization and denitrification: The oxidized sintering flue gas is introduced into the lower part of the absorption tower (1), and active lime powder, catalyst sodium chlorite and water are sprayed out from the spray assembly (14). After the sintering flue gas reacts with the active lime powder and water, it enters the activated coke layer (15). After the desulfurization and denitrification treatment, the sulfur dioxide concentration in the sintering flue gas is ≤15mg / m 3 , nitrogen oxide concentration ≤45mg / m 3 ; ⑤. Bag dust removal: The sintering flue gas after the desulfurization and denitrification treatment in step ④ is passed through the exhaust port into the bag dust collector (16), and the dust concentration in the sintering flue gas at the outlet of the bag dust collector (16) is controlled to be ≤4 mg / m 3 .

8. The method for treating a sintering flue gas desulfurization and denitrification ultra-low emission treatment system according to claim 7, characterized in that: In step ②, the desulfurization liquid is any one of sodium hydroxide solution, calcium hydroxide solution, potassium hydroxide solution or lime milk.

9. The method for treating a sintering flue gas desulfurization and denitrification ultra-low emission treatment system according to claim 7, characterized in that: In step ④, the mass ratio of the active lime powder, the catalyst sodium chlorite and water is 50:1:5.

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