Ultralow emission device and process for melting process of flaky vanadium pentoxide

Abstract

The invention relates to the technical field of flaky vanadium pentoxide melting, in particular to a flaky vanadium pentoxide melting process ultralow emission device and process. The ultralow emission device for the flaky vanadium pentoxide melting process comprises a raw material bin, the raw material bin is connected with a first-stage bag-type dust collector through a flash dryer, the first-stage bag-type dust collector is connected with a second-stage cyclone dust collector through a calcining furnace, and the second-stage cyclone dust collector is connected with a melting furnace bin through a second-stage bag-type dust collector. The melting furnace bin is connected with the finished product bin through the melting furnace, the secondary bag-type dust collector is connected with the confluence induced draft fan through the calcination induced draft fan, and the confluence induced draft fan is connected with the flash drying machine through the melting furnace. Tail gas discharged by the drying induced draft fan and the calcining induced draft fan is collected through a pipeline and converged through the converging induced draft fan 17 to be discharged in a centralized mode, pollution discharge points are reduced, ammonia gas generated in the production process is used as a denitration and desulfurization agent, and the ammonia gas discharge amount is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of flake vanadium pentoxide melting, in particular to an ultra-low emission device and process for a flake vanadium pentoxide melting process. Background Art

[0002] The traditional production process of flake vanadium pentoxide (hereinafter referred to as flake vanadium) is to directly melt APV in a reverberatory furnace to produce flake vanadium, which is called the one-step method. Later, after process transformation and upgrading, drying, calcination and melting were processed in steps, which is called the three-step method.

[0003] The one-step production process has been gradually replaced by the three-step process due to its serious pollution, high energy consumption, and low yield. During the production process, a large amount of particulate matter, nitrogen oxides, and sulfur dioxide pollutants will be discharged. For the three-step process, particulate matter emissions are 30mg / m³, nitrogen oxides are as high as 200mg / m³, and sulfur dioxide is as high as 200mg / m³, far exceeding the national "Vanadium Industry Pollutant Emission Standard" (GB26451-2011) revised single standard: particulate matter 10mg / m³, nitrogen oxides 100mg / m³, sulfur dioxide 100mg / m³ requirements. The existing equipment and processes have not completely solved the above problems. Summary of the invention

[0004] In view of the above deficiencies in the prior art, the purpose of the present invention is to provide an ultra-low emission device for the melting process of flake vanadium pentoxide, which collects the tail gas discharged by the drying induced draft fan and the calcining induced draft fan through a pipeline and discharges it in a centralized manner through a converging induced draft fan, thereby reducing the pollution emission points, and utilizing the ammonia generated in the production process as a denitrification and desulfurization agent to reduce the ammonia emission; adding a recycled air duct after the converging induced draft fan as the air volume required for the melting furnace to mix cold air and supplement the calcining hot air furnace, and at the same time, the recycled heat can save process energy consumption, reduce the total amount of tail gas emissions, and can reduce 1 / 4 of the total emission, and the oxygen content index can be reduced from the original 18% to within 15%.

[0005] Another object of the present invention is to provide an ultra-low emission process for the melting process of flake vanadium pentoxide, in which the tail gas collected by the converging induced draft fan enters the spray tower, and undergoes processes such as water spray cooling and filler adsorption, so that the ammonia in the tail gas is dissolved in the water, and at the same time, the sulfur dioxide and nitrogen dioxide in the tail gas are adsorbed, thereby reducing the sulfur dioxide and nitrogen dioxide in the exhaust gas. The sulfur dioxide index is reduced from the original dry outlet 200 mg / m³ to about 2 mg / m³.

[0006] The present invention is achieved by adopting the following technical solutions: The ultra-low emission device for the melting process of flaky vanadium pentoxide comprises a raw material bin, which is connected to a primary bag dust collector through a flash dryer, the primary bag dust collector is connected to a secondary cyclone dust collector through a calcining furnace, the secondary cyclone dust collector is connected to a melting furnace bin through a secondary bag dust collector, the melting furnace bin is connected to a finished product bin through a melting furnace, the secondary bag dust collector is connected to a converging induced draft fan through a calcining induced draft fan, and the converging induced draft fan is connected to the flash dryer through the melting furnace.

[0007] A primary cyclone dust collector is arranged between the flash dryer and the primary bag dust collector, a calcining material bin is arranged between the primary bag dust collector and the calcining furnace, and the flash dryer is connected to the calcining material bin.

[0008] A heat exchanger is provided between the secondary cyclone dust collector and the secondary bag dust collector, and the secondary bag dust collector is connected to the melting furnace silo through a pipeline.

[0009] The first-level bag filter is connected to the converging induced draft fan through a drying induced draft fan, the converging induced draft fan is connected to the calcining furnace through a hot blast furnace, and an SCR denitration reactor is arranged between the melting furnace and the flash dryer.

[0010] The converging induced draft fan is connected to the spray tower B through the spray tower A, and the spray tower B is connected to the exhaust chimney through an online detector.

[0011] The process of the ultra-low emission device for the melting process of flake vanadium pentoxide comprises the following steps: a. The ammonium polyvanadate in the raw material bin enters the flash dryer through the pipeline and is treated at 200-250°C. It then enters the calcining furnace and is treated at 400-460°C. It then enters the melting furnace through the melting furnace bin and is treated at 850-1050°C. After the treatment is completed, it enters the finished product warehouse for storage; b. The tail gas from the flash dryer enters the primary cyclone dust collector, the primary bag dust collector and the drying induced draft fan in sequence, and the tail gas from the calcining furnace enters the secondary cyclone dust collector, the heat exchanger, the secondary bag dust collector and the calcining induced draft fan in sequence. The tail gas discharged from the drying induced draft fan and the calcining induced draft fan is collected through a pipeline and discharged to the spray tower through a converging induced draft fan. A recycling air duct is added after the converging induced draft fan and enters the melting furnace as the melting furnace mixed cold air; c. An SCR denitration reactor is introduced after the tail gas outlet of the melting furnace and before the tail gas inlet of the flash dryer, and ammonia in the recycled air is used as a reducing agent for denitration; d. The tail gas collected by the converging induced draft fan enters the spray tower, and through processes such as water spray cooling and filler adsorption, the ammonia in the tail gas is dissolved into the water, and at the same time, the sulfur dioxide and nitrogen dioxide in the tail gas are adsorbed, thereby reducing the sulfur dioxide and nitrogen dioxide in the exhaust gas.

[0012] The outlet temperature of the calcining furnace is 400-460℃, which is used to reduce the total amount of nitrogen oxides generated when the raw materials enter the melting furnace.

[0013] The tail gas collected by the converging induced draft fan enters the spray tower B after being sprayed in the spray tower A. The spray tower B is divided into two parts. The lower part sprays dilute sulfuric acid to absorb the remaining ammonia in the tail gas. A flushing water tower is arranged on the upper part of the spray tower to first moisten the tail gas after deammoniation to reduce the acidity of the water mist mixed in the tail gas. The tail gas then enters the tube bundle demister to remove the large particles of water mist in the tail gas, and then enters the wire mesh demister to thoroughly remove the water mist in the tail gas, while removing the particulate matter and soluble salt mixed in the water mist.

[0014] The materials collected by the primary cyclone dust collector and the primary bag dust collector enter the calcination silo, the materials collected by the secondary cyclone dust collector and the secondary bag dust collector enter the melting furnace silo, and the tail gas of the melting furnace enters the SCR denitration reactor.

[0015] SCR denitrification reaction mechanism Reaction equation: 4NO+4NH3+O2→4N2+6H2O 2NO2+4NH3+O2→3N2+6H2O.

[0016] Water spray cooling: Atomized water is used to lower the flue gas temperature (130℃→80℃) and reduce the generation of thermal NOx.

[0017] 2NH3+SO2+1 / 2O2+H2O→(NH4)2SO4 NH3+H2SO4→(NH4)2SO4 (adsorbs residual ammonia).

[0018] Filler adsorption: Porous fillers increase the gas-liquid contact area and enhance the dissolution and oxidation of SO2 and NOx.

[0019] Demister: The tube bundle demister removes large particles of water mist, and the wire mesh demister intercepts micron-sized particles and soluble salts.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) The tail gas emitted by the drying induced draft fan and the calcining induced draft fan is collected through pipelines and discharged in a centralized manner through the converging induced draft fan, thereby reducing the number of pollution emission points; the ammonia generated in the production process is used as a denitrification and desulfurization agent to reduce ammonia emissions; the number of recycled air ducts is increased, and the recycled heat saves process energy consumption, reduces the total amount of tail gas emissions (reduced by 1 / 4), and reduces the oxygen content (from 18% to within 15%).

[0021] (2) According to the characteristics of the flake vanadium production process, an SCR denitrification reactor is added after the tail gas outlet of the melting furnace and before the tail gas inlet of the flash dryer, and ammonia in the recycled air is used as a reducing agent. Unlike other industries that use ammonia water or urea as a reducing agent, there is no need to set up an ammonia spraying device. This method of using ammonia generated during the production process as a reducing agent not only meets the denitrification demand, but also reduces ammonia emissions. The measured nitrogen oxide emission value can be less than 16mg / m³.

[0022] (3) A two-stage spray tower is used to treat the tail gas. The spray tower reduces sulfur dioxide, nitrogen dioxide and particulate matter in the tail gas through processes such as water spray cooling and filler adsorption. The lower part of the spray tower sprays dilute sulfuric acid to adsorb the remaining ammonia and dissolve some vanadium dust to reduce particulate matter emissions. The upper part uses a flushing water tower to moisten the tail gas, and the tube bundle demister and wire mesh demister remove water mist and particulate matter, so that the actual measured index of particulate matter is 2-3 mg / m³. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of an ultra-low emission device for the melting process of flake vanadium pentoxide of the present invention; In the figure: 1. Raw material warehouse; 2. Flash dryer; 3. Primary cyclone dust collector; 4. Primary bag dust collector; 5. Calcination silo; 6. Calcination furnace; 7. Secondary cyclone dust collector; 8. Heat exchanger; 9. Secondary bag dust collector; 10. Melting furnace silo; 11. Melting furnace; 12. Finished product warehouse; 13. Drying induced draft fan; 14. Hot air furnace; 15. Calcination induced draft fan; 16. SCR denitration reactor; 17. Converging induced draft fan; 18. Spray tower A; 19. Spray tower B; 20. Online detector; 21. Emission chimney. DETAILED DESCRIPTION

[0024] In order to make the purpose and technical solution of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings.

[0025] The following embodiments are all implemented by the following devices: The ultra-low emission device for the melting process of flake vanadium pentoxide comprises a raw material bin 1, which is connected to a primary bag dust collector 4 through a flash dryer 2, which is connected to a secondary cyclone dust collector 7 through a calcining furnace 6, which is connected to a melting furnace bin 10 through a secondary bag dust collector 9, which is connected to a finished product bin 12 through a melting furnace 11, which is connected to a secondary bag dust collector 9 through a calcining induced draft fan 15 and a converging induced draft fan 17, which is connected to the flash dryer 2 through the melting furnace 11. A primary cyclone dust collector 3 is provided between the flash dryer 2 and the primary bag dust collector 4, a calcining silo 5 is provided between the primary bag dust collector 4 and the calcining furnace 6, and the flash dryer 2 is connected to the calcining silo 5. A heat exchanger 8 is provided between the secondary cyclone dust collector 7 and the secondary bag dust collector 9, and the secondary bag dust collector 9 is connected to the melting furnace silo 10 through a pipeline. The primary bag dust collector 4 is connected to the converging induced draft fan 17 through the drying induced draft fan 13, and the converging induced draft fan 17 is connected to the calcining furnace 6 through the hot air furnace 14. An SCR denitration reactor 16 is provided between the melting furnace 11 and the flash dryer 2. The converging induced draft fan 17 is connected to the spray tower B19 through the spray tower A18, and the spray tower B19 is connected to the exhaust chimney 21 through the online detector 20.

[0026] Example 1 The ultra-low emission process of the flake vanadium pentoxide melting process comprises the following steps: a. The ammonium polyvanadate in the raw material bin 1 enters the flash dryer 2 through the pipeline, is treated at 230°C, then enters the calcining furnace 6, is treated at 430°C, then enters the melting furnace 11 through the melting furnace bin 10, is treated at 950°C, and after the treatment is completed, enters the finished product bin 12 for storage; b. The tail gas from the flash dryer 2 enters the primary cyclone dust collector 3, the primary bag dust collector 4 and the drying induced draft fan 13 in sequence, and the tail gas from the calcining furnace 6 enters the secondary cyclone dust collector 7, the heat exchanger 8, the secondary bag dust collector 9 and the calcining induced draft fan 15 in sequence. The tail gas discharged from the drying induced draft fan 13 and the calcining induced draft fan 15 is collected through a pipeline, and discharged to the spray tower through the converging induced draft fan 17. A recycling air duct is added after the converging induced draft fan 17, and enters the melting furnace 11 as the cold air mixed with the melting furnace 11; c. After the tail gas outlet of the melting furnace 11 and before the tail gas inlet of the flash dryer 2, an SCR denitration reactor 16 is introduced to perform denitration using ammonia in the recycled air as a reducing agent; d. The tail gas collected by the converging induced draft fan 17 enters the spray tower, and after the water spray cooling and filler adsorption process, the ammonia in the tail gas is dissolved in the water, and the sulfur dioxide and nitrogen dioxide in the tail gas are adsorbed at the same time, thereby reducing the sulfur dioxide and nitrogen dioxide in the exhaust gas.

[0027] The tail gas collected by the converging induced draft fan 17 enters the spray tower B19 after spraying in the spray tower A18. The spray tower B19 is divided into two parts. The lower part sprays dilute sulfuric acid to absorb the remaining ammonia in the tail gas. The upper part of the spray tower B19 is provided with a flushing water tower to first moisten the tail gas after deammoniation to reduce the acidity of the water mist mixed in the tail gas, and then enters the tube bundle demister to remove the large particles of water mist in the tail gas, and then enters the wire mesh demister to thoroughly remove the water mist in the tail gas and remove the particles mixed in the water mist. The materials collected by the primary cyclone dust collector 3 and the primary bag dust collector 4 enter the calcination silo 5, and the materials collected by the secondary cyclone dust collector 7 and the secondary bag dust collector 9 enter the melting furnace silo 10. The tail gas of the melting furnace 11 enters the SCR denitrification reactor 16.

[0028] Example 2 The ultra-low emission process of the flake vanadium pentoxide melting process comprises the following steps: a. The ammonium polyvanadate in the raw material bin 1 enters the flash dryer 2 through the pipeline and is treated at 200°C, then enters the calcining furnace 6 and is treated at 400°C, then enters the melting furnace 11 through the melting furnace bin 10 and is treated at 850°C, and after the treatment is completed, enters the finished product bin 12 for storage; b. The tail gas from the flash dryer 2 enters the primary cyclone dust collector 3, the primary bag dust collector 4 and the drying induced draft fan 13 in sequence, and the tail gas from the calcining furnace 6 enters the secondary cyclone dust collector 7, the heat exchanger 8, the secondary bag dust collector 9 and the calcining induced draft fan 15 in sequence. The tail gas discharged from the drying induced draft fan 13 and the calcining induced draft fan 15 is collected through a pipeline, and discharged to the spray tower through the converging induced draft fan 17. A recycling air duct is added after the converging induced draft fan 17, and enters the melting furnace 11 as the cold air mixed with the melting furnace 11; c. After the tail gas outlet of the melting furnace 11 and before the tail gas inlet of the flash dryer 2, an SCR denitration reactor 16 is introduced to perform denitration using ammonia in the recycled air as a reducing agent; d. The tail gas collected by the converging induced draft fan 17 enters the spray tower, and after the water spray cooling and filler adsorption process, the ammonia in the tail gas is dissolved in the water, and the sulfur dioxide and nitrogen dioxide in the tail gas are adsorbed at the same time, thereby reducing the sulfur dioxide and nitrogen dioxide in the exhaust gas.

[0029] The tail gas collected by the converging induced draft fan 17 enters the spray tower B19 after spraying in the spray tower A18. The spray tower B19 is divided into two parts. The lower part sprays dilute sulfuric acid to absorb the remaining ammonia in the tail gas. The upper part of the spray tower B19 is provided with a flushing water tower to first moisten the tail gas after deammoniation to reduce the acidity of the water mist mixed in the tail gas, and then enters the tube bundle demister to remove the large particles of water mist in the tail gas, and then enters the wire mesh demister to thoroughly remove the water mist in the tail gas and remove the particles mixed in the water mist. The materials collected by the primary cyclone dust collector 3 and the primary bag dust collector 4 enter the calcination silo 5, and the materials collected by the secondary cyclone dust collector 7 and the secondary bag dust collector 9 enter the melting furnace silo 10. The tail gas of the melting furnace 11 enters the SCR denitrification reactor 16.

[0030] Example 3 The ultra-low emission process of the flake vanadium pentoxide melting process comprises the following steps: a. The ammonium polyvanadate in the raw material bin 1 enters the flash dryer 2 through the pipeline, is treated at 250°C, then enters the calcining furnace 6, is treated at 460°C, then enters the melting furnace 11 through the melting furnace bin 10, is treated at 1050°C, and enters the finished product bin 12 for storage after the treatment is completed; b. The tail gas from the flash dryer 2 enters the primary cyclone dust collector 3, the primary bag dust collector 4 and the drying induced draft fan 13 in sequence, and the tail gas from the calcining furnace 6 enters the secondary cyclone dust collector 7, the heat exchanger 8, the secondary bag dust collector 9 and the calcining induced draft fan 15 in sequence. The tail gas discharged from the drying induced draft fan 13 and the calcining induced draft fan 15 is collected through a pipeline, and discharged to the spray tower through the converging induced draft fan 17. A recycling air duct is added after the converging induced draft fan 17, and enters the melting furnace 11 as the cold air mixed with the melting furnace 11; c. After the tail gas outlet of the melting furnace 11 and before the tail gas inlet of the flash dryer 2, an SCR denitration reactor 16 is introduced to perform denitration using ammonia in the recycled air as a reducing agent; d. The tail gas collected by the converging induced draft fan 17 enters the spray tower, and after the water spray cooling and filler adsorption process, the ammonia in the tail gas is dissolved in the water, and the sulfur dioxide and nitrogen dioxide in the tail gas are adsorbed at the same time, thereby reducing the sulfur dioxide and nitrogen dioxide in the exhaust gas.

[0031] The tail gas collected by the converging induced draft fan 17 enters the spray tower B19 after spraying in the spray tower A18. The spray tower B19 is divided into two parts. The lower part sprays dilute sulfuric acid to absorb the remaining ammonia in the tail gas. The upper part of the spray tower B19 is provided with a flushing water tower to first moisten the tail gas after deammoniation to reduce the acidity of the water mist mixed in the tail gas, and then enters the tube bundle demister to remove the large particles of water mist in the tail gas, and then enters the wire mesh demister to thoroughly remove the water mist in the tail gas and remove the particles mixed in the water mist. The materials collected by the primary cyclone dust collector 3 and the primary bag dust collector 4 enter the calcination silo 5, and the materials collected by the secondary cyclone dust collector 7 and the secondary bag dust collector 9 enter the melting furnace silo 10. The tail gas of the melting furnace 11 enters the SCR denitrification reactor 16.

[0032] Example 4 The difference from Example 1 is that the flash drying temperature is 220°C; the calcination temperature is 450°C; and the melting temperature is 980°C.

[0033] Comparative Example 1 Drying process: Equipment: Raw material warehouse → flash dryer → single-stage cyclone dust collector → drying induced draft fan → independent exhaust chimney.

[0034] Parameters: Drying temperature: 230℃; Dust removal method: single-stage cyclone dust collector; Tail gas treatment: Direct discharge without desulfurization and denitrification.

[0035] Calcination process: Equipment: calcination silo → calcination furnace → single-stage bag dust collector → calcination induced draft fan → independent emission chimney.

[0036] Parameters: Calcination temperature: 430°C; Dust removal method: single-stage bag dust collector; Tail gas treatment: No heat recovery, no SCR denitrification device.

[0037] Melting process: Equipment: melting furnace silo → melting furnace → single-stage cyclone dust collector → melting induced draft fan → independent exhaust chimney.

[0038] Parameters: Melting temperature: 950℃; Dust removal method: single-stage cyclone dust collector; Tail gas treatment: Direct discharge without spray desulfurization.

[0039] Comparative Example 2 Drying process: Equipment: Raw material warehouse → flash dryer → first-stage cyclone dust collector → drying induced draft fan → independent spray tower → discharge chimney.

[0040] Parameters: Drying temperature: 240℃; Spray tower: Only water is sprayed for cooling (no dilute sulfuric acid spray), and the particulate matter is reduced to 12mg / m³.

[0041] Calcination process: Equipment: calcination silo → calcination furnace → single-stage bag dust collector → calcination induced draft fan → SCR denitrification device (ammonia sprayed with purchased ammonia water) → emission chimney.

[0042] Parameters: Calcination temperature: 450℃; SCR denitration temperature: requires additional heating to 350°C; Denitrification efficiency: 85%, NOx emission 110mg / m³.

[0043] Melting process: Equipment: melting furnace silo → melting furnace → single-stage cyclone dust collector → melting induced draft fan → activated carbon adsorption tower → discharge chimney.

[0044] Parameters: Melting temperature: 980℃; Activated carbon adsorption: SO2 dropped to 80mg / m³, particulate matter 8mg / m³; The test data of Examples 1-3 are shown in Table 1.

[0045] The test data of Example 4 and Comparative Examples 1-2 are shown in Table 2.

[0046] Table 1: Test data of Examples 1-3

[0047] Table 2: Test data of Example 4 and Comparative Examples 1-2

[0048] By comparing the pollutant emission data before and after the treatment of the embodiment above, it can be clearly seen that the present invention has a significant effect in reducing pollutant emissions. Before treatment, particulate matter emissions were about 32.8-35.6 mg / m³, and after treatment they dropped to 2.2-3.2 mg / m³, with a significant drop, meeting and far below the 10 mg / m³ limit of particulate matter in the revised version of the National "Vanadium Industry Pollutant Emission Standard" (GB26451-2011). Sulfur dioxide was about 205-210 mg / m³ before treatment, and was as low as 1.5-2 mg / m³ after treatment, which also far exceeded the standard requirements. Nitrogen oxides were 320-350 mg / m³ before treatment, and only 15.4-15.8 mg / m³ after treatment, which is far below the standard of 100 mg / m³, indicating that the device and process have strong removal capabilities for various pollutants and can effectively achieve ultra-low emissions. After treatment, the average flue gas temperature dropped from 130-138℃ to 75-80℃, thanks to the water spray cooling process in the spray tower, which not only reduced the exhaust gas temperature, but also created favorable conditions for subsequent treatment. The moisture content increased from 8.23-8.7% to 11.8-12.4%, because the water spray cooling allowed moisture to enter the exhaust gas, and a series of physical and chemical adsorption processes in the spray tower also affected the moisture content.

[0049] The ultra-low emission device and process of the melting process of flake vanadium pentoxide of the present invention achieves ultra-low emission, energy saving and consumption reduction, and low-cost operation through core technologies such as centralized tail gas treatment, utilization of self-produced ammonia, and heat recycling. In terms of pollutant emissions, the particulate matter, SO2, and NOx after treatment are far lower than the national standards, which is significantly superior to traditional processes and existing treatment methods; energy consumption is reduced by more than 33%, and the oxygen content is optimized; the operating cost is reduced by 33% compared with the existing process. The process has strong adaptability to complex raw materials and production load fluctuations, and has significant competitiveness and promotion value.

Claims

1. An ultra-low emission device for the melting process of flake vanadium pentoxide, characterized in that: The invention comprises a raw material bin (1), wherein the raw material bin (1) is connected to a primary bag dust collector (4) via a flash dryer (2), the primary bag dust collector (4) is connected to a secondary cyclone dust collector (7) via a calcining furnace (6), the secondary cyclone dust collector (7) is connected to a melting furnace bin (10) via a secondary bag dust collector (9), the melting furnace bin (10) is connected to a finished product bin (12) via a melting furnace (11), the secondary bag dust collector (9) is connected to a converging induced draft fan (17) via a calcining induced draft fan (15), and the converging induced draft fan (17) is connected to the flash dryer (2) via the melting furnace (11).

2. The ultra-low emission device for melting process of flake vanadium pentoxide according to claim 1, characterized in that: A primary cyclone dust collector (3) is provided between the flash dryer (2) and the primary bag dust collector (4), a calcining material bin (5) is provided between the primary bag dust collector (4) and the calcining furnace (6), and the flash dryer (2) is connected to the calcining material bin (5).

3. The ultra-low emission device for melting process of flake vanadium pentoxide according to claim 1, characterized in that: A heat exchanger (8) is provided between the secondary cyclone dust collector (7) and the secondary bag dust collector (9), and the secondary bag dust collector (9) is connected to the melting furnace silo (10) through a pipeline.

4. The ultra-low emission device for melting process of flake vanadium pentoxide according to claim 1, characterized in that: The primary bag filter (4) is connected to a converging induced draft fan (17) via a drying induced draft fan (13), the converging induced draft fan (17) is connected to a calcining furnace (6) via a hot air furnace (14), and an SCR denitration reactor (16) is provided between the melting furnace (11) and the flash dryer (2).

5. The ultra-low emission device for melting process of flake vanadium pentoxide according to claim 1, characterized in that: The converging induced draft fan (17) is connected to the spray tower B (19) via the spray tower A (18), and the spray tower B (19) is connected to the exhaust chimney (21) via the online detector (20).

6. A process for the ultra-low emission device for melting process of flake vanadium pentoxide according to any one of claims 1 to 5, characterized in that: The following steps are involved: a. The ammonium polyvanadate in the raw material bin (1) enters the flash dryer (2) through a pipeline and is treated at 200-250°C. It then enters the calcining furnace (6) and is treated at 400-460°C. It then enters the melting furnace (11) through the melting furnace bin (10) and is treated at 850-1050°C. After the treatment is completed, it enters the finished product bin (12) for storage; b. The tail gas from the flash dryer (2) enters the primary cyclone dust collector (3), the primary bag dust collector (4) and the drying induced draft fan (13) in sequence, and the tail gas from the calcining furnace (6) enters the secondary cyclone dust collector (7), the heat exchanger (8), the secondary bag dust collector (9) and the calcining induced draft fan (15) in sequence. The tail gas discharged from the drying induced draft fan (13) and the calcining induced draft fan (15) is collected through a pipeline and discharged to the spray tower through a converging induced draft fan (17). A recycling air duct is added after the converging induced draft fan (17) and enters the melting furnace (11) to serve as cold air for the melting furnace (11); c. An SCR denitration reactor (16) is introduced after the tail gas outlet of the melting furnace (11) and before the tail gas inlet of the flash dryer (2), and ammonia in the recycled air is used as a reducing agent to perform denitration; d. The tail gas collected by the converging induced draft fan (17) enters the spray tower, and after the water spray cooling and filler adsorption process, the ammonia in the tail gas is dissolved in the water, and the sulfur dioxide and nitrogen dioxide in the tail gas are adsorbed at the same time, thereby reducing the sulfur dioxide and nitrogen dioxide in the exhaust gas.

7. The process according to claim 6, characterized in that The exhaust gas collected by the converging induced draft fan (17) enters the spray tower B (19) after being sprayed in the spray tower A (18). The spray tower B (19) is divided into two parts. The lower part sprays dilute sulfuric acid to absorb the remaining ammonia in the exhaust gas. A flushing water tower is arranged on the upper part of the spray tower B (19) to first humidify the exhaust gas after deammoniation to reduce the acidity of the water mist mixed in the exhaust gas. The exhaust gas then enters the tube bundle demister to remove the large particles of water mist in the exhaust gas, and then enters the wire mesh demister to completely remove the water mist in the exhaust gas and remove the particulate matter mixed in the water mist.

8. The process according to claim 6, characterized in that The materials collected by the primary cyclone dust collector (3) and the primary bag dust collector (4) enter the calcining bin (5), the materials collected by the secondary cyclone dust collector (7) and the secondary bag dust collector (9) enter the melting furnace bin (10), and the tail gas of the melting furnace (11) enters the SCR denitration reactor (16).

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