Flue gas dust removal and denitration system, smelting slag treatment flue gas purification system and process

Abstract

The invention discloses a flue gas dust removal and denitration system and a smelting slag treatment flue gas purification system and technology.The flue gas dust removal and denitration system comprises a dust removal and denitration integrated device, the dust removal and denitration integrated device is provided with a flue gas inlet channel and a flue gas outlet channel, the flue gas outlet channel is provided with a branch pipeline, and the branch pipeline is communicated with the flue gas inlet channel. And the branch pipeline is communicated with the flue gas inlet channel and is provided with an ammonia water spraying inlet. The flue gas dust removal and denitration system can solve the technical problem of influence of flue gas fluctuation on denitration efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of nonferrous smelting environmental protection engineering, and in particular relates to a flue gas dust removal and denitrification system, a smelting slag treatment flue gas purification system and a process. Background Art

[0002] Slag treatment in the nonferrous smelting industry mainly uses various pyrometallurgical waste slags, wet leaching slags, etc. as raw materials, and then adds metallurgical fluxes such as limestone and quartz stone and fuels or reducing agents such as coke and coal for high-temperature smelting to extract valuable metals. The process flue gas generated in this smelting process has a high temperature and contains high-concentration valuable metal dust, some sulfur oxides, nitrogen oxides, carbon monoxide, fluorine, chlorine and other acidic gas pollutants.

[0003] In the early years, the focus of flue gas purification in smelting slag treatment was mainly on the capture of valuable metal dust and flue gas desulfurization. With the increasing attention paid by the state to environmental protection and energy conservation requirements, the increasingly stringent pollutant emission standards have put increasing pressure on environmental protection for non-ferrous smelting enterprises. Therefore, the process requirements for the capture of valuable metal dust, desulfurization and denitrification have become more urgent. In recent years, a "dust removal and denitrification integrated device" has been first applied in the steel, coal chemical, cement, glass and other industries, and has achieved relatively good results. Therefore, the non-ferrous smelting industry has also begun to slowly learn from and apply this device, and to remove nitrogen oxides in flue gas to a certain extent, such as a flue gas dust removal and denitrification integrated device disclosed in the Chinese invention patent application publication number CN117959924A, which combines high-temperature dust collection and SCR denitrification. The denitrification unit in the dust removal and denitrification integrated device generally uses ammonia water as a reducing agent. The evaporator in the denitrification unit heats the outside air, and then mixes it with ammonia water to form ammonia gas, thereby reducing the nitrogen oxides in the flue gas to nitrogen gas. However, this device has also shown certain problems in the application of the non-ferrous smelting industry, such as: (1) Due to the working system of the metallurgical furnace itself, the flue gas fluctuates greatly, which will have a certain impact on the denitrification efficiency; (2) The integrated dust removal and denitrification device generally adopts a structural form in which the denitrification unit is installed on the upper part of the dust removal unit. In order to ensure the maintenance and replacement of the metal filter element in the dust removal unit, the total height of the device needs to be greatly increased; (3) In order to maximize the energy efficiency of the catalyst and ensure a high nitrogen oxide removal rate, the flue gas temperature needs to be controlled in a suitable high temperature range of 300-350°C. This results in the high-temperature flue gas entering the next desulfurization section. The water washing tower needs to consume a large amount of industrial water to cool down, which consumes water and fails to recover the flue gas heat energy. In summary, environmental protection practitioners need to improve and perfect the flue gas purification process according to the characteristics of smelting slag treatment flue gas and the characteristics of the pollutants it contains, while meeting the requirements of dust collection, denitrification, energy saving, and desulfurization, and achieving the emission standards of non-ferrous smelting flue gas, or even the requirements of special emission. Summary of the invention

[0004] In view of the current technical problems, the present invention aims to provide a flue gas dust removal and denitrification system, a smelting slag treatment flue gas purification system and process, which can solve the technical problem of the influence of flue gas fluctuations on denitrification efficiency.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A flue gas dust removal and denitrification system comprises an integrated dust removal and denitrification device, and its structural features are: the integrated dust removal and denitrification device is provided with a flue gas inlet channel and a flue gas outlet channel, the flue gas outlet channel is provided with a branch pipe, the branch pipe is connected to the flue gas inlet channel, and the branch pipe is provided with an ammonia water injection port.

[0007] When the flue gas dust removal and denitrification system of the present application is used for dust removal and denitrification, ammonia water is sprayed in through the ammonia water injection port, mixed with the high-temperature flue gas, and enters the dust removal and denitrification integrated device through the flue gas inlet channel for dust removal and denitrification, and the purified flue gas is discharged through the flue gas outlet channel. A portion of the purified flue gas is drawn out and returned to the dust removal and denitrification integrated device through a branch pipe, forming an internal circulation of the denitrified flue gas. The circulation of this portion of purified flue gas can resist flue gas fluctuations, thereby compensating for the influence of flue gas fluctuations on the denitrification efficiency and ensuring high denitrification efficiency. In addition, the temperature of the purified flue gas is relatively high, and this portion of the flue gas is used as the release wind of ammonia water to replace the outside air and mix with ammonia water, thereby saving the energy consumption of the evaporator on the denitrification unit in the dust removal and denitrification integrated device.

[0008] Preferably, the integrated dust removal and denitration device is provided with a dust removal unit and a denitration unit, and the denitration unit and the dust removal unit are arranged side by side; the flue gas inlet channel is arranged on the dust removal unit, and a receiving chamber is arranged on the top of the dust removal unit, and the receiving chamber is communicated with the denitration unit, and the flue gas outlet channel is arranged at the bottom of the denitration unit. The flue gas enters the dust removal unit through the flue gas inlet channel, and the valuable metal powder in the flue gas is captured by the metal filter element in the dust removal unit. The flue gas with the metal powder removed enters the denitration unit through the receiving chamber to remove nitrogen oxides. The denitration unit is arranged on the side of the dust collector unit, which does not occupy the inspection and maintenance space on the upper part of the dust removal unit, saving the overall space of the integrated dust removal and denitration device.

[0009] Preferably, an ash bin is provided at the bottom of the dust removal unit, and a first buried scraper conveyor is provided at the ash discharge port of the ash bin. The ash bin is provided to collect the valuable metal smoke captured by the dust removal unit and output it through the first buried scraper conveyor.

[0010] Based on the same inventive concept, the present application also provides a smelting slag treatment flue gas purification system, including a metallurgical furnace, a vertical flue and a waste heat boiler, the flue gas outlet of the metallurgical furnace is connected to the bottom flue gas inlet of the vertical flue, and the top flue gas outlet is connected to the flue gas inlet of the waste heat boiler; its structural characteristics are: it also includes a waste heat recovery device, a water washing device, a desulfurization device and the flue gas dust removal and denitrification system as described above; the flue gas outlet of the waste heat boiler is connected to the flue gas inlet channel, the flue gas outlet channel is connected to the flue gas inlet of the waste heat recovery device, and the flue gas is introduced into the water washing device through a fan after heat exchange in the waste heat recovery device; the flue gas outlet of the water washing device is connected to the flue gas inlet of the desulfurization device, and the flue gas outlet of the desulfurization device is connected to the chimney.

[0011] The high-temperature flue gas generated by the metallurgical furnace enters the vertical flue, and the flue gas with some metal dust settled enters the waste heat boiler for heat recovery. At the same time, nearly half of the metal dust in the flue gas settles. The flue gas at the outlet of the waste heat boiler is mixed with the injected ammonia water and enters the integrated dust removal and denitrification device. Most of the metal dust is captured and the nitrogen oxides are removed. Most of the purified flue gas at the outlet of the integrated dust removal and denitrification device enters the subsequent waste heat recovery device for secondary cooling to recover waste heat. The cooled flue gas is pumped to the water washing device by the fan, and then desulfurized and deacidified by the desulfurization device. The treated flue gas is discharged through the chimney to meet the standards. The flue gas purification system of the present invention can not only recover valuable metal dust and remove sulfur oxides and nitrogen oxides, but also fully recover the waste heat of the high-temperature flue gas by setting up a waste heat recovery device, thereby reducing the water consumption and energy consumption of the subsequent water washing tower, and saving energy and protecting the environment.

[0012] Preferably, the waste heat recovery device includes a heat collector, an evaporator and an oil-water heat exchanger, the flue gas outlet channel is connected to the flue gas inlet of the heat collector, the flue gas outlet of the heat collector is connected to the fan inlet; the heat transfer oil outlet of the heat collector is connected to the heat transfer oil inlet of the evaporator, the heat transfer oil outlet of the evaporator is connected to the heat transfer oil inlet of the oil-water heat exchanger, the heat transfer oil outlet of the oil-water heat exchanger is connected to the heat transfer oil inlet of the heat collector; the hot water exchange outlet of the oil-water heat exchanger is connected to the hot water exchange inlet of the evaporator, and the hot water exchange outlet of the evaporator is connected to the production water pipeline. The heat transfer oil enters the heat collector and is heated to high-temperature heat transfer oil by the high-temperature flue gas after dust removal and denitration. The high-temperature heat transfer oil enters the evaporator to heat water to produce steam. The heat transfer oil after heat exchange enters the oil-water heat exchanger to exchange heat with deoxygenated water, and the low-temperature heat transfer oil returns to the heat collector and circulates back and forth in the waste heat recovery device. The deoxygenated water heated in the oil-water heat exchanger enters the evaporator to absorb heat and produce saturated steam, which is sent to production. The flue gas after heat is recovered by the waste heat recovery device enters the subsequent water washing device.

[0013] Preferably, an ash hopper is provided at the bottom of the waste heat boiler, and a second buried scraper conveyor is provided at the ash discharge port of the ash hopper. The ash hopper can collect the valuable metal smoke in the waste heat boiler and output it through the second buried scraper conveyor.

[0014] Preferably, the water washing device includes a water washing tower body and a first electric demister, and the first electric demister is arranged on the top of the water washing tower body; the desulfurization device includes an absorption tower body, a demister and a second electric demister, the demister is arranged on the top of the absorption tower body, and the second electric demister is arranged on the top of the demister.

[0015] Based on the same inventive concept, the present application also provides a smelting slag treatment flue gas purification process, which uses the smelting slag treatment flue gas purification system as described above, and includes the following steps: Work section 1: the material is subjected to high-temperature oxygen-enriched smelting in a metallurgical furnace to generate dust containing metals and their compounds, sulfur oxides, nitrogen oxides, carbon monoxide, fluorine, chlorine and other acidic gases and high-temperature flue gas;

[0016] Section 2: The flue gas in Section 1 enters the vertical flue, and the unreacted substances in the flue gas react further. At the same time, some metal dust in the flue gas is separated from the flue gas and settles back into the metallurgical furnace;

[0017] Section 3: The flue gas in Section 2 enters the waste heat boiler, which recycles most of the heat to reduce the flue gas temperature. The valuable metal dust in the flue gas settles to the bottom of the waste heat boiler, and the cooled flue gas enters the next section;

[0018] Section 4: The flue gas cooled in Section 3 is mixed with ammonia water sprayed in the flue gas inlet channel of the integrated dust removal and denitrification device and the ammonia water spraying port on the branch pipe. The valuable metal dust and nitrogen oxides in the flue gas are removed by the integrated dust removal and denitrification device. A part of the purified flue gas is returned to the flue gas inlet channel through the branch pipe as dilution wind of ammonia water, forming an internal circulation of the denitrified flue gas.

[0019] Section 5: Most of the purified flue gas after dust removal and denitrification in Section 4 enters the waste heat recovery device for further cooling, recovering the remaining heat energy of the flue gas to form secondary cooling flue gas;

[0020] Section 6: The flue gas from Section 5 is cooled twice and then goes through a water washing device for dust removal and cooling. It is then desulfurized by a desulfurization device and sent to the chimney for emission in compliance with the standards.

[0021] The flue gas purification process of the present application organically integrates the dust removal, denitrification, energy conservation, and desulfurization sections, strictly controls the operating parameters, coordinates the connection of each section, effectively plays the role of each section, and makes the entire process system operate stably. The flue gas after purification meets the corresponding pollutant emission limits, can achieve standard emissions, and meet environmental protection requirements.

[0022] Preferably, in the first stage, the temperature in the metallurgical furnace is 1100-1300°C; in the third stage, the temperature of the flue gas coming out of the waste heat boiler is maintained between 330-380°C; in the fourth stage, before the flue gas enters the integrated dust removal and denitrification device, the SO2 concentration in the flue gas is 10000-15000 mg / Nm 3 After the integrated dust removal and denitrification device captures valuable metal dust, the dust concentration in the flue gas is <30mg / Nm 3 The flue gas temperature in the integrated dust removal and denitrification device is 300-350℃, and the NO x Concentration ≤600mg / Nm 3 , NO after denitrification x Concentration <100mg / Nm 3 ; In section 5, the flue gas temperature at the outlet of the waste heat recovery device is 20-30°C higher than the flue gas dew point temperature; in section 6, the flue gas temperature after desulfurization is 40-50°C, and the dust concentration of the flue gas after desulfurization is <10mg / Nm 3 , SO2 concentration <100mg / Nm 3 .

[0023] Preferably, in the third stage, the valuable metal dust in the flue gas settles to the ash hopper at the bottom of the waste heat boiler, and is transported to the metallurgical furnace through the second buried scraper conveyor, and is recycled in the first stage; in the fourth stage, the valuable metal dust in the flue gas is captured by the dust removal unit in the integrated dust removal and denitrification device and falls into the ash bin at the bottom of the dust removal unit, and is transported to the metallurgical furnace through the first buried scraper conveyor, and is recycled in the first stage. The flue gas purification process of the present application can not only recover the valuable metal dust particles and recycle them, but also achieve the standard emission of flue gas.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The flue gas dust removal and denitrification system of the present invention realizes internal circulation of part of the dust removal and denitrification flue gas, thereby improving the removal rate of nitrogen oxides. At the same time, the structure of the integrated dust removal and denitrification device is adjusted, thereby optimizing the inspection and maintenance space of the dust removal unit;

[0026] (2) The smelting slag treatment flue gas purification system of the present invention not only recovers valuable metal dust and removes sulfur oxides and nitrogen oxides, but also can fully recover the waste heat of high-temperature flue gas, reduce the water and energy consumption of subsequent water washing towers, and save energy and protect the environment;

[0027] (3) The smelting slag treatment flue gas purification process of the present invention organically integrates the dust removal, denitrification, energy saving and desulfurization sections. By strictly controlling the operating parameters and coordinating the connection of each section, the role of each section is effectively exerted, so that the entire process system operates stably; the flue gas after purification meets the corresponding pollutant emission limit and can achieve standard emission;

[0028] (4) The smelting slag treatment flue gas purification process of the present invention can not only recover valuable metal dust particles and reuse them as resources, but also achieve standard flue gas emissions. At the same time, it also meets the requirements of energy conservation and environmental protection, providing a design technology reference for similar enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of the flue gas dust removal and denitrification system of the present invention;

[0030] Figure 2 yes Figure 1 Schematic diagram of the main structure of the integrated dust removal and denitrification device;

[0031] Figure 3 yes Figure 2 A side view structural schematic diagram of;

[0032] Figure 4 It is a schematic diagram of the structure of the smelting slag treatment flue gas purification system of the present invention;

[0033] Figure 5 This is a process flow chart of smelting slag treatment flue gas purification of the present invention;

[0034] Figure 6 yes Figure 5 Process flow chart of the waste heat recovery device.

[0035] In the figure

[0036] 1-metallurgical furnace, 2-vertical flue, 3-waste heat boiler, 301-ash hopper, 4-integrated dust removal and denitrification device, 401-flue gas inlet channel, 402-flue gas outlet channel, 403-dust removal unit, 404-denitrification unit, 405-accommodation chamber, 406-ash bin, 5-waste heat recovery device, 501-heat collector, 502-evaporator, 503-oil-water heat exchanger, 6-first buried scraper conveyor, 7-centrifugal induced draft fan, 8-water washing device, 801-water washing tower body, 802-first electric demister, 9-desulfurization device, 901-absorption tower body, 902-demister, 903-second electric demister, 10-chimney, 11-second buried scraper conveyor, 12-branch pipeline. DETAILED DESCRIPTION

[0037] The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict. For the convenience of description, if the words "upper", "lower", "left" and "right" appear in the following, they only indicate that the upper, lower, left and right directions are consistent with the drawings themselves, and do not limit the structure.

[0038] like Figure 1 and Figure 2 As shown, a flue gas dust removal and denitration system provided in this embodiment includes a dust removal and denitration integrated device 4, which is provided with a flue gas inlet channel 401 and a flue gas outlet channel 402, and the flue gas outlet channel 402 is provided with a branch pipe 12, which is connected to the flue gas inlet channel 401, and the branch pipe 12 is provided with an ammonia injection port. Figure 2 and Figure 3 As shown, the integrated dust removal and denitration device 4 is provided with a dust removal unit 403 and a denitration unit 404, and the denitration unit 404 is arranged side by side with the dust removal unit 403. The dust removal unit 403 uses a metal alloy or a metal compound porous material as the metal filter element of the dust removal unit 403, and the metal filter element is resistant to high temperature and has a high metal dust capture efficiency, and has excellent resistance to strong acid, strong alkali and thermal corrosion. The denitration unit 404 adopts the SCR method for denitration, and the denitration catalyst uses a wide temperature SCR denitration catalyst, and the denitration reducing agent uses a 10% wt ammonia solution. The flue gas inlet channel 401 is arranged at the lower part of the dust removal unit 403, and the top of the dust removal unit 403 is provided with a accommodating chamber 405, which is connected to the denitration unit 404 through the flue gas neck section and the flue gas backflow section, and the flue gas outlet channel 402 is arranged at the bottom of the denitration unit 404. An ash bin 406 is provided at the bottom of the dust removal unit 403 , and a first buried scraper conveyor 6 is provided at the ash discharge port of the ash bin 406 .

[0039] like Figure 4As shown, this embodiment also provides a smelting slag treatment flue gas purification system, including a metallurgical furnace 1, a vertical flue 2, a waste heat boiler 3, a waste heat recovery device 5, a water washing device 8, a desulfurization device 9 and the flue gas dust removal and denitrification system as described above, the flue gas outlet of the metallurgical furnace 1 is connected to the bottom flue gas inlet of the vertical flue 2, and the top flue gas outlet of the vertical flue 2 is connected to the flue gas inlet of the waste heat boiler 3. The flue gas outlet of the waste heat boiler 3 is connected to the flue gas inlet channel 401, and the flue gas outlet channel 402 is connected to the flue gas inlet of the waste heat recovery device 5. After the flue gas is heat-exchanged in the waste heat recovery device 5, it is introduced into the water washing device 8 through the fan 7. The flue gas outlet of the water washing device 8 is connected to the flue gas inlet of the desulfurization device 9, and the flue gas outlet of the desulfurization device 9 is connected to the chimney 10. The waste heat boiler 3 is arranged in an open-air vertical manner, and is composed of a vertical flue, a radiation cooling chamber and a convection zone. The boiler adopts a combination of suspension and support, adopts forced circulation, and has its own steam drum. An ash hopper 301 is provided at the bottom of the waste heat boiler 3, and a manhole door and an observation hole are provided on the side wall of the waste heat boiler and on both sides of the ash hopper 301. A second buried scraper conveyor 11 is provided at the ash discharge port of the ash hopper 301 to return the collected valuable metal dust to the metallurgical furnace 1 for resource recycling. The waste heat boiler 3 adopts a cleaning method that combines high-efficiency elastic vibration and gas pulse soot blower blasting cleaning, and explosion-proof doors are arranged on the tops of the first and second radiation chambers.

[0040] like Figure 6 As shown, the waste heat recovery device 5 includes a heat collector 501, an evaporator 502 and an oil-water heat exchanger 503. The flue gas outlet channel 402 is connected to the flue gas inlet of the heat collector 501, and the flue gas outlet of the heat collector 501 is connected to the inlet of the fan 7. The heat transfer oil outlet of the heat collector 501 is connected to the heat transfer oil inlet of the evaporator 502, the heat transfer oil outlet of the evaporator 502 is connected to the heat transfer oil inlet of the oil-water heat exchanger 503, and the heat transfer oil outlet of the oil-water heat exchanger 503 is connected to the heat transfer oil inlet of the heat collector 501. The hot water outlet of the oil-water heat exchanger 503 is connected to the hot water inlet of the evaporator 502, and the hot water outlet of the evaporator 502 is connected to the production water pipeline. The waste heat recovery device 5 recovers the high-temperature flue gas at the outlet of the dust removal and denitration integrated device 4 for secondary waste heat recovery, generates saturated steam, and sends it to the steam network for production use.

[0041] The water washing device 8 includes a water washing tower body 801 and a first electric precipitator 802. The first electric precipitator 802 is arranged at the top of the water washing tower body 801. The first electric precipitator 802 is a wet electric precipitator made of conductive glass fiber reinforced plastic. The flue gas after dust removal and denitrification passes through the water washing tower body 801 to further remove the smoke and harmful substances therein, and after reducing the flue gas temperature, it is further purified by the first electric precipitator 802 at the top and sent to the subsequent desulfurization device 9. The water washing tower body 801 is made of glass fiber reinforced plastic, with an integrated tower tank and a multi-layer large nozzle spray structure. The bottom of the tower body is used as a circulation tank. The desulfurization device 9 includes an absorption tower body 901, a demister 902 and a second electric precipitator 903. The second electric precipitator 903 is a wet electric precipitator made of conductive glass fiber reinforced plastic. The demister 902 is arranged at the top of the absorption tower body 901, and the second electric precipitator 903 is arranged at the top of the demister 902. The defoamer 902 uses a layer of baffled defoamer to preliminarily remove large-size absorption liquid and acid mist. The desulfurization tower body 901 is made of glass fiber reinforced plastic, the main filler is 76mm Haier ring, the material is PP, the folded plate defoamer is made of PP, the bottom of the tower body is a liquid storage tank, and the bottom is designed as a slope to drain the acid sludge.

[0042] like Figure 5 As shown, this embodiment also provides a smelting slag treatment flue gas purification process, using the smelting slag treatment flue gas purification system as described above, including the following steps:

[0043] Section 1: Pyrometallurgical waste slag, wet leaching slag and other materials are added with appropriate auxiliary materials and fuels, and firstly smelted at high temperature in a metallurgical furnace 1, and oxygen-rich air is blown in. The temperature in the furnace is 1100-1300℃ to ensure sufficient reaction time. While the main metal molten material is generated, there is still a high concentration of volatile metal dust, and some nitrogen oxides, sulfur oxides, and acidic gases enter the high-temperature flue gas;

[0044] Section 2: The high-temperature flue gas at the outlet of the metallurgical furnace 1 in Section 1 enters the vertical flue 2. The vertical flue 2 has a suitable height, so that the unreacted substances in the flue gas can further react. At the same time, part of the metal dust is separated from the flue gas and settles back into the metallurgical furnace 1.

[0045] Section 3: The flue gas in Section 2 enters the waste heat boiler 3, which recycles most of the heat to reduce the flue gas temperature. At the same time, nearly half of the valuable metal dust in the flue gas settles into the ash hopper 301 at the bottom of the waste heat boiler 3 due to the temperature reduction, and is concentrated by the second scraper conveyor 11 and returned to the metallurgical furnace 1 for re-smelting. The outlet flue gas temperature of this section is 330-380°C;

[0046] Section 4: The flue gas cooled in section 3 is mixed with ammonia water sprayed at the ammonia water spray inlet on the branch pipe 12 in the flue gas inlet channel 401 of the integrated dust removal and denitrification device 4. Most of the valuable metal dust in the flue gas is first captured by the high-temperature metal filter element of the dust removal unit 403, and the captured metal dust falls into the ash bin 406, and is concentrated by the first buried scraper conveyor 6 and then returned to the metallurgical furnace 1 for re-smelting to recover valuable metals; the flue gas temperature after dust removal is 300-350°C, flows out through the containing chamber and enters the SCR denitrification unit 404 on the side to remove nitrogen oxides; in addition, part of the purified flue gas after dust removal and denitrification is drawn out from the flue gas outlet channel 402 as dilution wind of ammonia water, and returned to the flue gas inlet channel 401 of the integrated dust removal and denitrification device 4, forming a denitrification flue gas internal circulation; before the flue gas dust removal and denitrification of this section, NO x Concentration ≤600mg / Nm 3 , SO2 concentration is maintained at 10000~15000mg / Nm 3 The dust concentration of flue gas discharged after dust removal and denitrification is less than 30mg / Nm 3 , NO x Concentration <100mg / Nm 3 ;

[0047] Section 5: After dust removal and denitration in Section 4, the ~300℃ high-temperature flue gas enters the heat transfer oil waste heat recovery device 5 for secondary cooling. The ~170℃ heat transfer oil is sent to the heat collector 501 through the circulation pump. After being heated by the dust removal and denitration high-temperature flue gas, the ~220℃ high-temperature heat transfer oil enters the evaporator 502 to heat water and produce steam. After heat exchange, the ~180℃ heat transfer oil enters the oil-water heat exchanger 503 to exchange heat with the 104℃ deoxygenated water. The ~170℃ low-temperature heat transfer oil returns to the circulation pump and enters the heat collector 501 again, circulating back and forth in the system; the deoxygenated water in the oil-water heat exchanger 503 is heated to ~160℃ and enters the evaporator 502 to absorb heat and produce saturated steam; the flue gas after heat recovery by the heat transfer oil waste heat recovery device 5 enters the next water washing and desulfurization section. This section must ensure that the outlet flue gas temperature is 20-30℃ higher than the dew point;

[0048] Section 6: The flue gas cooled twice in Section 5 passes through the water scrubber body 801 to further remove the smoke and harmful substances therein. After the flue gas temperature is lowered again, it passes through the first electrostatic precipitator 802 on the top for further purification and is sent to the subsequent desulfurization device 9; after the flue gas is desulfurized by the desulfurization tower body 901, the large-particle absorption liquid and acid mist are removed by the demister 902. The tail gas after desulfurization and defoaming enters the second electrostatic precipitator 903 to remove tiny acid mist and droplets. After deep purification, it is sent to the chimney to meet the discharge standards. This section must ensure that the dust concentration of the outlet flue gas is less than 10mg / Nm 3 , SO2 concentration <100mg / Nm 3 .

[0049] The flue gas purification process in this embodiment can not only recycle valuable metal resources and remove sulfur oxides and nitrogen oxides, but also fully recycle the waste heat of high-temperature flue gas, save energy and protect the environment, and achieve flue gas emission standards or even special emission requirements.

[0050] The contents explained in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the embodiments made by those skilled in the art fall within the scope defined by the claims attached to the present invention.

Claims

1. A flue gas dust removal and denitrification system, comprising a dust removal and denitrification integrated device (4), characterized in that: The integrated dust removal and denitrification device (4) is provided with a flue gas inlet channel (401) and a flue gas outlet channel (402), the flue gas outlet channel (402) is provided with a branch pipe (12), the branch pipe (12) is connected to the flue gas inlet channel (401), and the branch pipe (12) is provided with an ammonia water injection port.

2. The flue gas dust removal and denitrification system according to claim 1, characterized in that: The integrated dust removal and denitration device (4) is provided with a dust removal unit (403) and a denitration unit (404), and the denitration unit (404) and the dust removal unit (403) are arranged side by side; the flue gas inlet channel (401) is arranged on the dust removal unit (403), a receiving chamber (405) is provided on the top of the dust removal unit (403), and the receiving chamber (405) is connected to the denitration unit (404); the flue gas outlet channel (402) is arranged at the bottom of the denitration unit (404).

3. The flue gas dust removal and denitrification system according to claim 2, characterized in that: An ash bin (406) is provided at the bottom of the dust removal unit (403), and a first buried scraper conveyor (6) is provided at the ash discharge port of the ash bin (406).

4. A smelting slag treatment flue gas purification system, comprising a metallurgical furnace (1), a vertical flue (2) and a waste heat boiler (3), wherein the flue gas outlet of the metallurgical furnace (1) is connected to the bottom flue gas inlet of the vertical flue (2), and the top flue gas outlet of the vertical flue (2) is connected to the flue gas inlet of the waste heat boiler (3); characterized in that: It also includes a waste heat recovery device (5), a water washing device (8), a desulfurization device (9) and a flue gas dust removal and denitrification system as described in any one of claims 1 to 3; the flue gas outlet of the waste heat boiler (3) is connected to the flue gas inlet channel (401), and the flue gas outlet channel (402) is connected to the flue gas inlet of the waste heat recovery device (5), and the flue gas is introduced into the water washing device (8) through the fan (7) after heat exchange in the waste heat recovery device (5); the flue gas outlet of the water washing device (8) is connected to the flue gas inlet of the desulfurization device (9), and the flue gas outlet of the desulfurization device (9) is connected to the chimney (10).

5. The smelting slag treatment flue gas purification system according to claim 4, characterized in that: The waste heat recovery device (5) comprises a heat collector (501), an evaporator (502) and an oil-water heat exchanger (503); the smoke outlet channel (402) is connected to the smoke inlet of the heat collector (501), and the smoke outlet of the heat collector (501) is connected to the inlet of the fan (7); the heat transfer oil outlet of the heat collector (501) is connected to the heat transfer oil inlet of the evaporator (502), the heat transfer oil outlet of the evaporator (502) is connected to the heat transfer oil inlet of the oil-water heat exchanger (503), and the heat transfer oil outlet of the oil-water heat exchanger (503) is connected to the heat transfer oil inlet of the heat collector (501); the hot water outlet of the oil-water heat exchanger (503) is connected to the hot water inlet of the evaporator (502), and the hot water outlet of the evaporator (502) is connected to a production water pipeline.

6. The smelting slag treatment flue gas purification system according to claim 4, characterized in that: An ash hopper (301) is provided at the bottom of the waste heat boiler (3), and a second buried scraper conveyor (11) is provided at the ash discharge port of the ash hopper (301).

7. The smelting slag treatment flue gas purification system according to claim 4, characterized in that: The water washing device (8) comprises a water washing tower body (801) and a first electric demister (802). The first electric demister (802) is arranged on the top of the water washing tower body (801); the desulfurization device (9) comprises an absorption tower body (901), a demister (902) and a second electric demister (903), the demister (902) being arranged on the top of the absorption tower body (901), The second electric demister (903) is arranged on top of the demister (902).

8. A smelting slag treatment flue gas purification process, characterized in that: The smelting slag treatment flue gas purification system as claimed in claims 4 to 7 comprises the following steps: Stage 1: The material is smelted in a metallurgical furnace (1) at high temperature and in an oxygen-rich environment, generating dust containing metals and their compounds, sulfur oxides, nitrogen oxides, carbon monoxide, acidic gases such as fluorine and chlorine, and high-temperature flue gas; Section 2: The flue gas in Section 1 enters the vertical flue (2), and the unreacted substances in the flue gas further react. At the same time, some metal dust in the flue gas is separated from the flue gas and settles back into the metallurgical furnace (1); Section three: the flue gas in section two enters the waste heat boiler (3), and the waste heat boiler (3) recycles most of the heat to reduce the flue gas temperature, and the valuable metal dust in the flue gas settles to the bottom of the waste heat boiler (3), and the flue gas after cooling enters the next section; Section four: the flue gas after cooling in section three is mixed with ammonia water sprayed at the flue gas inlet channel (401) of the integrated dust removal and denitrification device (4) and the ammonia water spray inlet on the branch pipe (12), and the valuable metal dust and nitrogen oxides in the flue gas are removed by the integrated dust removal and denitrification device (4), and a part of the purified flue gas is returned to the flue gas inlet channel (401) through the branch pipe (12) as dilution wind for the ammonia water, thereby forming an internal circulation of the denitrified flue gas; Section 5: Most of the purified flue gas after dust removal and denitrification in Section 4 enters the waste heat recovery device (5) for further cooling to recover the remaining heat energy of the flue gas and form secondary cooled flue gas; Section 6: The secondary cooled flue gas in Section 5 is subjected to dust removal and further cooling by the water washing device (8), and then is subjected to desulfurization treatment by the desulfurization device (9) before being sent to the chimney for emission in compliance with the emission standards.

9. The smelting slag treatment flue gas purification process according to claim 8, characterized in that: In the first section, the temperature in the metallurgical furnace (1) is 1100-1300°C; in the third section, the temperature of the flue gas from the waste heat boiler (3) is maintained between 330-380°C; in the fourth section, before the flue gas enters the integrated dust removal and denitrification device (4), the SO2 concentration in the flue gas is 10000-15000 mg / Nm 3 After the dust removal and denitrification integrated device (4) captures the valuable metal dust, the dust concentration in the flue gas is less than 30mg / Nm 3 The flue gas temperature in the integrated dust removal and denitrification device (4) is 300-350°C, and the NO x Concentration ≤600mg / Nm 3 , NO after denitrification x Concentration <100mg / Nm 3 In the fifth section, the flue gas temperature at the outlet of the waste heat recovery device (5) is 20 to 30°C higher than the flue gas dew point temperature; in the sixth section, the flue gas temperature after desulfurization is 40 to 50°C, and the dust concentration of the flue gas after desulfurization is <10mg / Nm 3 , SO2 concentration <100mg / Nm 3 .

10. The smelting slag treatment flue gas purification process according to claim 8, characterized in that: In the third stage, the valuable metal dust in the flue gas settles to the ash hopper (301) at the bottom of the waste heat boiler (3), and is transported to the metallurgical furnace (1) through the second buried scraper conveyor (11), and is recycled as a resource in the first stage; in the fourth stage, the valuable metal dust in the flue gas is captured by the dust removal unit (403) in the integrated dust removal and denitrification device (4) and falls into the ash bin (406) at the bottom of the dust removal unit (403), and is transported to the metallurgical furnace (1) through the first buried scraper conveyor (6), and is recycled as a resource in the first stage.

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