An integrated system and method for synergistic desulfurization, dust removal and denitrification for pelletizing

Abstract

The present invention provides an integrated system and method for coordinated desulfurization, dust removal and denitrification for pelletizing, which belongs to the technical field of industrial air pollution control. The system includes a tempering material injection device and a hot air purge device; the tempering material injection device is connected to the main flue after pelletizing, and the hot air purge device is connected to the insulation device of the electrostatic precipitator; the main flue after pelletizing is connected to the electrostatic precipitator; the tempering material injection device includes a weighing silo and a jet fan respectively connected to the injector; the hot air purge device includes a connected sealing fan and a heater. The present invention sprays a tempering medium into the flue gas after pelletizing, mixes it with the unreacted combustion-supporting agent in the flue gas, reduces its adhesion, and reduces the pressure of the rear environmental protection device. The hot air delivered by the hot air purge device can prevent acidic substances from condensing on the inner wall of the porcelain sleeve of the electrostatic precipitator, reduce the damage rate of the insulating porcelain sleeve of the electrostatic precipitator due to non-operating conditions, and ensure that its electric field remains stable during use.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial air pollution control, and in particular relates to an integrated system and method for coordinated desulfurization, dust removal and denitrification for pelletizing. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Sintering and pelletizing is one of the processes with serious pollutant emissions in steel enterprises. The flue gas discharged from the sintering and pelletizing process contains a variety of dust and harmful components. The existing post-pelletizing flue gas desulfurization, denitrification and dust removal process technology generally adopts the process route of post-pelletizing electrostatic precipitator + limestone / lime-wet desulfurization (single tower or double tower) + wet electrostatic precipitator + flue demister + GGH + SCR reactor + GGH + chimney, or adopts pre-pelletizing denitrification + post-pelletizing electrostatic precipitator + limestone / lime-wet desulfurization (single tower or double tower) + wet electrostatic precipitator. The electrostatic precipitator is a key device in the current post-pelletizing flue gas desulfurization, denitrification and dust removal process route. No matter which route is adopted, there are problems such as the electric field cannot operate normally after the electrostatic precipitator has been running for a period of time, the electric field data is unstable, and there is sticky dust in the flue after the precipitator (before desulfurization) and the flue corrodes the flue (conventional anti-corrosion measures are difficult to solve).

[0004] Conventional pelletizing desulfurization, denitrification and dust removal technology only considers the dust content in the flue gas, the components such as Ca, K, Na, Si, ash in the dust, and the components such as SO2, SO3, HCl in the flue gas, and ignores other components in the pellet production raw materials, such as flux components. Existing pelletizing generally adopts traditional technology, and the dust contained in the pellet tail gas contains a certain amount of flux or flux components such as silicate, lime, calcium fluoride, etc. Dust containing similar flux components has the characteristics of easy moisture absorption at room temperature, easy adhesion to the surface of objects, difficult to clean, and strong corrosiveness (can corrode 904L and sand).

[0005] After part of the dust containing flux components is collected by the electrostatic precipitator, it adheres to the surface of the anode plate and the cathode line. At present, it is generally cleaned by adjusting the vibration measures of the electrostatic precipitator, such as voltage reduction vibration, power-off vibration or using a rotating motor to clean the dust. The adhered dust is difficult to clean, and when the electrostatic precipitator is shut down for maintenance or the pelletizing system is shut down and started, and the flue gas temperature is low, the dust absorbs moisture and becomes highly corrosive, which can corrode the anode and cathode systems of the electrostatic precipitator and the precipitator housing, ash hopper and other components, affecting the normal operation of the electrostatic precipitator while destroying the overall structural stability of the precipitator, causing safety hazards to the production system.

[0006] The dust not collected by the electrostatic precipitator enters the related equipment after the dust collector, such as the induced draft fan, flue, booster fan device and subsequent environmental protection treatment device. When the system is stopped and started, low load or no load, some dust is deposited in the fan, flue and induced draft fan, and absorbs moisture after contact with the outside atmosphere, causing corrosion to the induced draft fan impeller, casing, flue and other problems. Summary of the invention

[0007] In view of the deficiencies in the prior art, the purpose of the present invention is to provide an integrated system and method for coordinated desulfurization, dust removal and denitrification for pelletizing, which reduces the adhesion and corrosiveness of dust contained in the flue gas by spraying a tempering medium into the flue gas after pelletizing, thereby solving the problems of dust adhesion in the anode and cathode systems of the rear electrostatic precipitator, and dust adhesion and corrosion in the subsequent flue and environmental protection devices.

[0008] In order to achieve the above object, the technical solution of the present invention is:

[0009] In a first aspect, a synergistic desulfurization, dust removal and denitrification integrated system for pelletizing includes a tempering material injection device and a hot air purge device; the tempering material injection device is connected to a post-pellet main flue, the hot air purge device is connected to an insulation device of an electrostatic precipitator; the post-pellet main flue is connected to an electrostatic precipitator;

[0010] The tempered material injection device comprises a weighing bin and an injection fan respectively connected to the injector; the hot air blowing device comprises a connected sealing fan and a heater.

[0011] Optionally, a manual gate valve and a star-shaped ash discharge valve are provided between the weighing silo and the jet fan.

[0012] Optionally, a first gas input device is provided between the weighing silo and the manual plug valve.

[0013] Optionally, the gas source of the first gas input device is compressed air or nitrogen.

[0014] Optionally, a second gas input device is provided between the jet blower and the ejector.

[0015] Optionally, the gas source of the second gas input device is nitrogen.

[0016] Optionally, the sealing fan is connected to a third gas delivery device.

[0017] Optionally, the gas source of the third gas delivery device is clean air.

[0018] Optionally, the insulating device is a box beam or an insulating box.

[0019] In the second aspect, a method for integrated desulfurization, dust removal and denitrification for pelletizing includes the following processes:

[0020] The conditioning material stored in the weighing silo and the gas delivered by the jet fan are mixed in the ejector and then sprayed into the main flue after the pelletizing, where they mix / react with the unreacted combustion aid in the flue gas and react with the SO2 / SO3 in the flue gas;

[0021] The flue gas mixed / reacted with the modulating substance is dusted in an electrostatic precipitator; during the dust collection process, the hot air delivered by the hot air blowing device heats the insulation device of the electrostatic precipitator.

[0022] Optionally, the modulated substance includes one or more of calcium oxide powder and high-activity calcium hydroxide powder.

[0023] Optionally, the temperature of the hot air delivered by the hot air blowing device is higher than the acid dew point of the flue gas by more than 10°C.

[0024] The beneficial effects of the present invention are:

[0025] The present invention sprays a conditioning medium into the flue gas after pelletizing, mixes it with the unreacted combustion-supporting agent in the flue gas, reduces its adhesion, and solves the problem of dust adhesion to the rear electrostatic precipitator plate, dust adhesion to the flue, and corrosion; the conditioning medium can react with part of the SO2 / SO3 in the flue gas, appropriately reduce its concentration, and reduce the pressure of the rear desulfurization system; the conditioning substance can react with HF in the flue gas, appropriately reduce its concentration, and reduce the pressure of the rear environmental protection device (such as the anti-corrosion pressure of the flue, desulfurization tower, etc. and the replacement frequency of the insulating porcelain sleeve of the electrostatic precipitator). The hot air delivered by the hot air blowing device can prevent the acidic substances from condensing on the inner wall of the porcelain sleeve of the electrostatic precipitator, reduce the damage rate of the insulating porcelain sleeve of the electrostatic precipitator due to non-operating conditions, and ensure that its electric field remains stable during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0027] Figure 1 It is a schematic diagram of the structure of the tempered material injection device in Example 1 of the present invention.

[0028] Figure 2 It is a schematic diagram of the structure of the hot air blowing device in Example 1 of the present invention.

[0029] Figure 3 It is a schematic diagram of the partial structure of the electrostatic precipitator in Example 1 of the present invention.

[0030] Among them: 1. Weighing silo; 2. Manual plug-in valve; 3. Star-shaped ash discharge valve; 4. Ejector; 5. Second gas input device; 6. Jet fan; 7. Main flue after pelletizing; 8. Sealed fan; 9. Heater; 10. Electrostatic precipitator; 11. Pneumatic hammer; 12. Insulating porcelain sleeve; 13. Cathode hanger; 14. Air supply pipe; 21. First gas input device. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0032] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0033] Example 1

[0034] An integrated system for synergistic desulfurization, dust removal and denitrification for pelletizing, comprising a tempering material injection device and a hot air purge device; the tempering material injection device is connected to a post-pelletizing main flue 7, and the hot air purge device is connected to an electrostatic precipitator; the post-pelletizing main flue 7 is connected to an electrostatic precipitator;

[0035] The tempered material injection device comprises a weighing bin 1 and an injection fan 6 respectively connected to an injector 4; the hot air blowing device comprises a sealing fan 8 and a heater 9 connected thereto.

[0036] Through the above device, the tempering medium is sprayed into the post-pelletizing flue gas transported in the post-pelletizing main flue 7, so that the modulated substance is mixed with the unreacted combustion-supporting agent in the flue gas to reduce its adhesion, and with some SO2 / SO3 / HF and other components in the flue gas, appropriately reducing their concentration, reducing the pressure of the rear environmental protection device (such as the anti-corrosion pressure of the flue, desulfurization tower, etc. and the replacement frequency of the insulating porcelain sleeve of the electrostatic precipitator). The hot air delivered by the hot air blowing device can increase the temperature inside the porcelain sleeve of the electrostatic precipitator, prevent the gaseous acidic substances in the flue gas from condensing on its inner wall, thereby reducing the damage rate of the insulating porcelain sleeve of the electrostatic precipitator, ensuring that its electric field remains stable during use, thereby improving the treatment effect of the post-pelletizing flue gas and extending the service life of the electrostatic precipitator.

[0037] A manual gate valve 2 and a star-shaped ash discharge valve 3 are provided between the weighing silo 1 and the ejector 4; the manual gate valve 2 is used for repairing and replacing the star-shaped ash discharge valve, and the star-shaped ash discharge valve 3 is used for quantitative discharge.

[0038] Optionally, a pneumatic hammer 11 is provided on the wall of the weighing silo 1 to promote the falling of powder inside the weighing silo 1 .

[0039] A first gas input device 21 is provided between the weighing silo 1 and the manual gate valve 2; the gas source of the first gas input device 21 is compressed air or nitrogen; the compressed air or nitrogen plays a fluidizing role.

[0040] A second gas input device 5 is provided between the jet blower 6 and the ejector 4; the jet blower 6 is a Roots blower, and the gas source of the second gas input device 5 is nitrogen as a backup gas source; the ejector 4 is a Venturi type.

[0041] The sealed fan 8 is connected to the third gas delivery device; the gas source of the third gas delivery device is clean air, which includes clean hot air (dust content less than 5mg / Nm 3 ) or clean air; the sealed fan uses a high-pressure centrifugal fan.

[0042] Among them, the function of the first gas input device 21 is fluidization; the function of the second gas input device 5 is a backup gas source; the function of the third gas delivery device is fluidization.

[0043] The heater 9 is connected to the box beam of the electrostatic precipitator 10, such as Figure 3 As shown, the box girder includes an insulating porcelain sleeve 12, and the clean air heated by the heater 9 is input from above between the insulating porcelain sleeve 12 and the cathode hanger 13; specifically, it is input from the air supply pipe 14 of the upper cover of the insulating porcelain sleeve, and uniformly dispersed to the inside of the insulating porcelain sleeve 12 along the air outlet of the cylinder. The structure of the insulating porcelain sleeve used in this embodiment is the same as the structure of the porcelain sleeve and the sleeve of the Chinese utility model patent "An insulating device for a pelletizing electrostatic precipitator" with application number 202323176333.3.

[0044] In this embodiment, two branches are arranged under the weighing silo 1, and a manual plug valve 2, a first gas input device 21 interface and a star-shaped ash discharge valve 3 are respectively provided in each branch. After the two branches are connected to the injectors 4, they enter the main flue 7 after the pelletizing together; accordingly, the upstream pipelines of the two injectors 4 are respectively provided with their own injection fans 6 and second gas input device 5 interfaces; the hot air blowing device includes a plurality of hot air blowing pipelines, and the plurality of hot air blowing pipelines are respectively provided with their own sealing fans 8, third gas delivery device interfaces and heaters 9, and the two hot air blowing pipelines are respectively connected to different box beams of the electrostatic precipitator.

[0045] An integrated method for synergistic desulfurization, dust removal and denitrification for pelletizing includes the following processes:

[0046] The conditioning material stored in the weighing silo 1 and the gas delivered by the jet blower 6 are mixed in the ejector 4 and then sprayed into the main flue 7 after the pelletizing, where they react with the unreacted combustion aid in the flue gas and react with the SO2 / SO3 in the flue gas;

[0047] The flue gas after mixing / reacting with the modulating substance enters the electrostatic precipitator 10 heated by the hot air delivered by the hot air blowing device for dust collection.

[0048] Among them, since the insulating device of the electrostatic precipitator 10 is heated by the hot air delivered by the hot air blowing device, it can always be in an insulating state to avoid the occurrence of adhesion, thereby ensuring that its electric field remains stable during use.

[0049] In the above process, the modulating substance can react with various components in the flue gas in terms of chemical composition to reduce the sticky components in the flue gas. The hot air transported by the hot air blowing device enters the equipment of the electrostatic precipitator 10 that needs to be kept insulated and dry for a long time, such as the electrostatic precipitator box beam / insulation box, etc. The hot air can control the temperature to above the condensation temperature of the sticky components, and prevent the sticky components from adhering in the temperature environment, thereby achieving the overall effect of solving the problem of dust adhering to the rear electrostatic precipitator plates and dust adhering to the flue.

[0050] The prepared substance includes one or more of calcium oxide powder and highly active calcium hydroxide powder; it is an industrialized finished product

[0051] The dosage of the modulating material needs to be adjusted according to the pelletizing operation load or the pelletizing main induced draft fan load.

[0052] Likewise, the gas flow rate of the first gas input device 21, the gas flow rate of the second gas input device 5 and the gas flow rate of the third gas delivery device need to be adjusted according to the processing load.

[0053] The hot air temperature delivered by the hot air blowing device is more than 10°C higher than the flue gas acid dew point.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pelletizing integrated system for synergistic desulfurization, dust removal and denitrification, characterized in that: It includes a tempering material injection device and a hot air blowing device; the tempering material injection device is connected to the main flue after pelletizing, and the hot air blowing device is connected to the insulation device of the electric precipitator; the main flue after pelletizing is connected to the electric precipitator; The tempered material injection device comprises a weighing bin and an injection fan respectively connected to the injector; the hot air blowing device comprises a connected sealing fan and a heater.

2. The integrated system for synergistic desulfurization, dust removal and denitrification for pelletizing as claimed in claim 1, characterized in that: A manual plug valve and a star-shaped ash discharge valve are arranged between the weighing silo and the jet fan.

3. The integrated system for synergistic desulfurization, dust removal and denitrification for pelletizing as claimed in claim 2, characterized in that: A first gas input device is provided between the weighing bin and the manual plug valve; Optionally, the gas source of the first gas input device is compressed air or nitrogen.

4. The integrated system for synergistic desulfurization, dust removal and denitrification for pelletizing according to claim 1, characterized in that: A second gas input device is provided between the jet blower and the ejector; Optionally, the gas source of the second gas input device is nitrogen.

5. The integrated system for synergistic desulfurization, dust removal and denitrification for pelletizing according to claim 1, characterized in that: The sealing fan is connected to a third gas delivery device; Optionally, the gas source of the third gas delivery device is clean air.

6. The integrated system for synergistic desulfurization, dust removal and denitrification for pelletizing according to claim 1, characterized in that: The insulating device is a box beam or an insulating box.

7. The integrated system for synergistic desulfurization, dust removal and denitrification for pelletizing as claimed in claim 6, characterized in that: The heater is connected to the insulating porcelain bushing in the box beam.

8. The integrated system for synergistic desulfurization, dust removal and denitrification for pelletizing according to claim 1, characterized in that: The silo wall of the weighing silo is provided with a pneumatic hammer.

9. A method for integrated desulfurization, dust removal and denitrification for pelletizing based on the integrated desulfurization, dust removal and denitrification system for pelletizing as claimed in any one of claims 1 to 8, characterized in that: The process includes: The conditioning material stored in the weighing silo and the gas delivered by the jet fan are mixed in the ejector and then sprayed into the main flue after the pelletizing, where they react with the unreacted combustion aid in the flue gas and react with the SO2 / SO3 in the flue gas; The flue gas mixed / reacted with the modulating substance is dusted in an electrostatic precipitator; during the dust collection process, the hot air delivered by the hot air blowing device heats the insulation device of the electrostatic precipitator.

10. The integrated method for synergistic desulfurization, dust removal and denitrification for pelletizing as claimed in claim 9, characterized in that: The modulated substance includes one or more of calcium oxide powder and highly active calcium hydroxide powder; Optionally, the temperature of the hot air delivered by the hot air blowing device is higher than the acid dew point of the flue gas by more than 10°C.

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