Industrial silicon flue gas comprehensive treatment system

Abstract

The utility model discloses an industrial silicon flue gas comprehensive treatment system which comprises a flue and a chimney at the tail end of the flue, and a high-temperature waste heat boiler, an electric dust removal device, a low-temperature waste heat boiler, an ozone denitration device, a wet desulphurization device and a carbon capture device are sequentially arranged on the flue. The high-temperature waste heat boiler and the low-temperature waste heat boiler are further communicated with the carbon capture device through steam pipelines to supply steam to the carbon capture device, and the waste water output end of the wet desulphurization device is communicated with a flue between the electric dust removal device and the high-temperature waste heat boiler. According to the system and the method, high-efficiency utilization of heat is achieved, CO2 in flue gas can be captured while conventional pollutants such as NOx, SO2 and particulate matter are removed, a large amount of system energy consumption is saved, high-purity silica fume can be recycled, enterprise benefits are improved, secondary pollution is reduced, zero emission of desulfurization wastewater can be achieved, chloride ions in the system can be effectively removed, and desulfurization water consumption is saved.

Description

Technical Field

[0001] The utility model relates to the technical field of comprehensive treatment of industrial silicon electric furnace fume, in particular to an industrial silicon fume comprehensive treatment system. Background Art

[0002] Since the use of charcoal is currently restricted in industrial silicon production, most companies use petroleum coke, clean coal, etc. as reducing agents. During the electric furnace smelting process, the reducing agent reacts with the raw silica with a SiO2 content of not less than 99%, and SiO2 is reduced to Si by C at high temperature. The industrial silicon electric furnace production process is cyclical. During different processes, the flue gas volume, flue gas temperature and particulate matter content continue to change and fluctuate greatly. The particulate matter mainly contains SiO2. Due to the use of petroleum coke, clean coal, etc., the flue gas also contains SO2, NOx and CO2.

[0003] The published group standard "Emission Standards for Air Pollutants in Industrial Silicon Production" T / CNIA0123-2021 stipulates the emission concentration limits of particulate matter, SO2 and NOx for existing and newly built enterprises. At the same time, due to stricter environmental protection policies, total constraints on corporate pollutant emissions, and internal conventions in the industrial silicon industry, some companies have added desulfurization and denitrification equipment, and emission indicators are also moving closer to ultra-low emission indicators in the power industry or other non-power industries. Industrial silicon production is accompanied by a large amount of carbon emissions. Considering the realization of the dual carbon goals in the future, it is foreseeable that the development of synergistic carbon capture technology will be gradually carried out. Due to the influence of the flue gas characteristics of industrial silicon electric furnaces, the application of various desulfurization, denitrification, and dust removal technical routes are subject to varying degrees of restrictions. At present, the mainstream technical routes in domestic industrial silicon electric furnace flue gas treatment projects are: 1. Waste heat boiler + bag dust removal + circulating fluidized bed desulfurization + bag dust removal + SCR denitrification; 2. Waste heat boiler + bag dust removal + SCR denitrification + spray semi-dry desulfurization + flue gas dust collection device; 3. Waste heat boiler + SCR denitrification + waste heat boiler + dry desulfurization + bag dust removal.

[0004] When adopting the technical route of waste heat boiler + bag dust removal + circulating fluidized bed desulfurization + bag dust removal + SCR denitrification, the concentration of particulate matter at the outlet of the fluidized bed desulfurization tower is high, and a high-efficiency bag dust collector needs to be arranged downstream to ensure that the particulate matter meets the emission standards, which occupies a large area; the system resistance is large, and the energy consumption of the induced draft fan is too high; the desulfurization by-product contains a large amount of calcium sulfite, which is difficult to utilize comprehensively; the investment is high, and the circulating fluidized bed design is complex.

[0005] When adopting the technical route of waste heat boiler + bag dust removal + SCR denitrification + spray semi-dry desulfurization + flue gas dust collection device, the overall footprint and system resistance are equivalent to the above-mentioned circulating fluidized bed desulfurization technical route, and it also faces the problem of handling desulfurization ash containing calcium sulfite; key equipment such as SDA atomizers rely on imports, pipes and nozzles are prone to blockage, and investment and maintenance costs are high; semi-dry desulfurization towers will produce solid deposits.

[0006] When the technical route of waste heat boiler + SCR denitrification + waste heat boiler + dry desulfurization + bag dust removal is adopted, the desulfurization efficiency is not high and it is difficult to meet the complex flue gas conditions of industrial silicon electric furnaces; due to the small particle size, large specific surface area and strong adhesion of microsilica powder in the flue gas, it is easy to cause upstream catalyst blockage or secondary combustion; desulfurization is upstream of dust removal, and the addition of desulfurization absorbent affects the recovery of microsilica powder. Summary of the invention

[0007] The purpose of the utility model is to solve the problems in the prior art and to provide an industrial silicon fume comprehensive treatment system that can solve at least one of the above problems.

[0008] To achieve the above-mentioned purpose, the utility model proposes an industrial silicon flue gas comprehensive treatment system, including a flue and a chimney at the end thereof, wherein a high-temperature waste heat boiler, an electrostatic precipitator, a low-temperature waste heat boiler, an ozone denitrification device, a wet desulfurization device and a carbon capture device are sequentially arranged on the flue, and the high-temperature waste heat boiler and the low-temperature waste heat boiler are also connected to the carbon capture device through a steam pipe to supply steam thereto, and the wastewater output end of the wet desulfurization device is connected to the flue between the electrostatic precipitator and the high-temperature waste heat boiler.

[0009] Preferably, the electrostatic precipitator device comprises a dust collector body and an ash unloading fine screening module arranged at the bottom of the dust collector body.

[0010] Preferably, the wet desulfurization device comprises a wet desulfurization module, a wastewater atomization evaporation module and a wastewater atomization injection module which are connected in sequence.

[0011] Preferably, the carbon capture device comprises a pretreatment module, an absorption module and a desorption module which are connected in sequence, the smoke exhaust port at the top of the absorption module is connected to the chimney, and the steam inlet of the desorption module is connected to the steam outlet of the high-temperature waste heat boiler and the low-temperature waste heat boiler through a steam pipe.

[0012] Beneficial effects of the utility model: The utility model can adapt to the complex and changeable flue gas conditions of industrial silicon electric furnaces, not only realizing the efficient use of heat, but also being able to capture CO2 in flue gas while removing conventional pollutants such as NOx, SO2 and particulate matter. The two-stage waste heat boiler realizes multi-stage heat recovery, which not only enables the downstream equipment to reach a suitable reaction temperature, but also directly supplies the flue gas heat to the carbon capture device, saving a lot of system energy consumption. The upstream dust collector can recover microsilicon powder with higher purity, improve the efficiency of the enterprise and reduce secondary pollution. The combination of ozone denitrification and wet desulfurization can achieve efficient and coordinated removal of NOx, SO2 and particulate matter. The wastewater flue evaporation process using flue gas waste heat can achieve zero discharge of desulfurization wastewater, effectively remove chloride ions in the system, and save desulfurization water consumption.

[0013] The features and advantages of the present invention will be described in detail through embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The utility model is a structural schematic diagram of an industrial silicon fume comprehensive treatment system.

[0015] In the figure: 1-flue, 2-high temperature waste heat boiler, 3-electrostatic precipitator, 4-low temperature waste heat boiler, 5-ozone denitrification device, 6-wet desulfurization device, 7-carbon capture device, 8-chimney, 9-steam pipe, 31-dust collector body, 32-ash unloading and fine screening module, 61-wet desulfurization module, 62-wastewater atomization evaporation module, 63-wastewater atomization injection module, 71-pretreatment module, 72-absorption module, 73-desorption module. DETAILED DESCRIPTION

[0016] See also Figure 1 The utility model discloses an industrial silicon flue gas comprehensive treatment system, comprising a flue 1 and a chimney 8 at the end thereof, wherein the flue 1 is provided with a high-temperature waste heat boiler 2, an electrostatic precipitator 3, a low-temperature waste heat boiler 4, an ozone denitrification device 5, a wet desulfurization device 6 and a carbon capture device 7 in sequence, wherein the high-temperature waste heat boiler 2 and the low-temperature waste heat boiler 4 are also connected to the carbon capture device 7 through a steam pipe 9 to supply steam thereto, and the waste water output end of the wet desulfurization device 6 is connected to the flue 1 between the electrostatic precipitator 3 and the high-temperature waste heat boiler 2.

[0017] The electrostatic precipitator 3 comprises a precipitator body 31 and an ash removal and fine screening module 32 arranged at the bottom of the precipitator body 31 .

[0018] The wet desulfurization device 6 comprises a wet desulfurization module 61 , a wastewater atomization evaporation module 62 and a wastewater atomization injection module 63 which are connected in sequence.

[0019] The carbon capture device 7 includes a pretreatment module 71, an absorption module 72 and a desorption module 73 which are connected in sequence. The top smoke exhaust port of the absorption module 72 is connected to the chimney 8. The steam inlet of the desorption module 73 is connected to the steam outlets of the high-temperature waste heat boiler 2 and the low-temperature waste heat boiler 4 through a steam pipe 9.

[0020] Working process of this utility model:

[0021] In the working process of the comprehensive treatment system of industrial silicon flue gas of the utility model, the pollutant-containing flue gas in the flue 1 first enters the high-temperature waste heat boiler 2, and is cooled from 500-600°C to 300-400°C to reach the suitable reaction temperature of the electrostatic precipitator. The electrostatic precipitator 3 is arranged between the high-temperature waste heat boiler 2 and the low-temperature waste heat boiler 4, and includes a dust collector body 31 and an ash unloading fine screening module 32. After the flue gas enters the dust collector body 31, the particles will fall into the ash unloading fine screening module 32 under the action of gravity or the vibration action of the dust collector body 31, and the useless particles will be removed and the fine screening recovery of microsilicon powder will be completed. The flue gas after dust removal enters the low-temperature waste heat boiler 4, and is cooled from 300-400°C to below 150°C, reaching the optimal reaction temperature of ozone denitrification. The ozone denitrification device 5 is arranged between the low-temperature waste heat boiler 4 and the wet desulfurization and wastewater zero discharge device 6. After the dust-removed flue gas enters, the removal of NOx is completed. The wet desulfurization 6 is arranged downstream of the ozone denitrification device 5, and includes a wet desulfurization module 61, a wastewater atomization evaporation module 62 and a wastewater atomization injection module 63. The wet desulfurization module 61 mainly removes SO2. The generated wastewater is first atomized and evaporated in the wastewater atomization evaporation module 62, and then sprayed by the wastewater atomization injection module 63 into the flue 1 between the high-temperature waste heat boiler 2 and the electrostatic precipitator 3. The atomized wastewater evaporates at a temperature of 300-400°C using the waste heat of the flue gas. After the salt crystallizes, it is removed by the electrostatic precipitator 3 together with the particulate matter in the flue gas, and the water vapor enters the wet desulfurization module 61 for recycling. The flue gas after desulfurization then enters the carbon capture device 7, which includes a pretreatment module 71, an absorption module 72 and a desorption module 73. The flue gas with conventional pollutants that meet the emission standards first passes through the pretreatment module 71 to complete the fine desulfurization and cool down to 40-50°C to reach the optimal reaction temperature for CO2 chemical absorption. The absorption module 72 is arranged between the pretreatment module 71 and the desorption module 73. The internal rising flue gas reacts with the CO2 absorbent flowing downward in the countercurrent to complete the absorption of CO2. The flue gas after pollution reduction and carbon reduction is connected to the chimney 8 through the exhaust port at the top of the absorption module 72 and finally discharged into the atmosphere. The steam pipe 9 transports the steam generated by the high-temperature waste heat boiler 2 and the low-temperature waste heat boiler 4 to the desorption module 73 as a heat source, so that the desorption module 73 reaches the optimal desorption temperature. The absorbent rich in CO2 is transported from the absorbent outlet of the absorption module 72 to the desorption module 73, and the desorption of CO2 is completed under high temperature conditions and the high-purity CO2 is discharged for treatment.

[0022] The wet desulfurization device 6 comprises a wet desulfurization module 61, a wastewater atomization evaporation module 62 and a wastewater atomization injection module 63, and the desulfurized wastewater adopts a flue evaporation zero emission process.

[0023] The carbon capture device 7 comprises a pretreatment module 71, an absorption module 72 and a desorption module 73. The process adopts a chemical absorption method and the absorbent adopts an amine solution.

[0024] The steam generated by the high-temperature waste heat boiler 2 and the low-temperature waste heat boiler 4 can be supplied to the desorption module 73 at the same time, or can be supplied to the desorption module 73 in a one-in-one-standby manner.

[0025] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention falls within the protection scope of the present invention.

Claims

1. An industrial silicon fume comprehensive treatment system, characterized by: The invention comprises a flue (1) and a chimney (8) at the end thereof, wherein a high-temperature waste heat boiler (2), an electrostatic precipitator (3), a low-temperature waste heat boiler (4), an ozone denitrification device (5), a wet desulfurization device (6) and a carbon capture device (7) are sequentially arranged on the flue (1), wherein the high-temperature waste heat boiler (2) and the low-temperature waste heat boiler (4) are also connected to the carbon capture device (7) via a steam pipe (9) to supply steam thereto, and the waste water output end of the wet desulfurization device (6) is connected to the flue (1) between the electrostatic precipitator (3) and the high-temperature waste heat boiler (2).

2. The industrial silicon fume comprehensive treatment system according to claim 1, characterized in that: The electric dust removal device (3) comprises a dust collector body (31) and an ash removal fine screening module (32) arranged at the bottom of the dust collector body (31).

3. The industrial silicon fume comprehensive treatment system according to claim 1, characterized in that: The wet desulfurization device (6) comprises a wet desulfurization module (61), a wastewater atomization evaporation module (62) and a wastewater atomization injection module (63) which are connected in sequence.

4. An industrial silicon fume comprehensive treatment system according to any one of claims 1 to 3, characterized in that: The carbon capture device (7) comprises a pretreatment module (71), an absorption module (72) and a desorption module (73) which are connected in sequence, the smoke exhaust port at the top of the absorption module (72) is connected to the chimney (8), and the steam inlet of the desorption module (73) is connected to the steam outlets of the high-temperature waste heat boiler (2) and the low-temperature waste heat boiler (4) through a steam pipe (9).

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