An industrial silicon smelting flue gas purification system and production line

Abstract

This utility model relates to the field of flue gas purification technology for industrial silicon DC and AC furnaces. To address the problems of unstable denitrification efficiency, inability to remove high-concentration NOx, catalyst poisoning, and a maximum denitrification efficiency of no more than 90% in existing technologies, this utility model provides an industrial silicon smelting flue gas purification system and production line. The system includes a first-stage waste heat boiler, a medium-high temperature SCR denitrification device, three rake soot blowers, three ultrasonic soot blowers, a second-stage waste heat boiler, a filter dust collector, and a wet desulfurization tower. The rake soot blowers remove ash from the surface of the plate catalyst bed. The industrial silicon smelting flue gas purification system and production line provided by this utility model, through the medium-high temperature SCR denitrification device and the introduction of a pre-stage waste heat boiler to regulate the flue gas temperature to the SCR temperature window, combined with the dual ash removal mechanism of rake soot blowers and ultrasonic soot blowers, prevents catalyst poisoning, blockage, and ash adhesion, thereby improving the denitrification efficiency to as high as 95%.

Description

Technical Field

[0001] This utility model relates to the field of flue gas purification technology for industrial silicon DC furnaces and AC furnaces, and in particular to an industrial silicon smelting flue gas purification system and production line. Background Technology

[0002] The industrial silicon smelting process generates a large amount of high-temperature, dusty flue gas. If this flue gas is emitted directly without effective treatment, it will cause serious environmental pollution, including particulate matter pollution and acid gas pollution in the air, affecting the surrounding air quality and ecological balance, endangering human health, and potentially causing corrosion and damage to nearby buildings and vegetation.

[0003] Existing denitrification methods use low-temperature SCR denitrification (160℃-210℃), which has unstable denitrification efficiency, cannot remove high concentrations of NOx (above 500mg / Nm³), and the catalyst is prone to poisoning, with the highest denitrification efficiency not exceeding 90%. Utility Model Content

[0004] This invention addresses the problems of unstable denitrification efficiency, inability to remove high-concentration NOx, easy catalyst poisoning, and denitrification efficiency not exceeding 90% in existing technologies by providing an industrial silicon smelting flue gas purification system and production line.

[0005] The technical solution adopted in this utility model is:

[0006] An industrial silicon smelting flue gas purification system includes:

[0007] A first-stage waste heat boiler is used to receive the flue gas discharged from the electric arc furnace and perform a first-stage waste heat recovery on the flue gas discharged from the electric arc furnace.

[0008] The medium-high temperature SCR denitrification unit has three plate catalyst beds. The medium-high temperature SCR denitrification unit performs SCR denitrification on the flue gas after primary waste heat recovery through the plate catalyst beds. Each plate catalyst bed is arranged from top to bottom in the flue gas duct, and the cross-section of the plate catalyst bed is vertical.

[0009] Three rake soot blowers are connected to the medium-high temperature SCR denitrification unit to remove ash from the surface of the plate catalyst bed. An air heating device is installed inside the rake soot blower, which enables the rake soot blower to blow out air at 200℃-300℃.

[0010] Three sonic soot blowers are connected to the medium-high temperature SCR denitrification unit. The sonic soot blowers clean the dust inside the plate catalyst bed by causing the plate catalyst bed to vibrate.

[0011] The second-stage waste heat boiler is used to receive the denitrified flue gas and perform secondary waste heat recovery on the denitrified flue gas.

[0012] Dust collectors are used to remove dust from flue gas after secondary waste heat recovery.

[0013] A wet desulfurization tower is used to receive flue gas after secondary waste heat recovery and perform wet desulfurization on it to generate purified flue gas.

[0014] Furthermore, each rake soot blower is connected to the side wall of the flue gas duct, with each connection located on the upper part of the side wall of the flue gas duct where each plate catalyst bed is located. The rake soot blower is equipped with a retractable blowpipe, which has two rows of purging pipes. After the blowpipes extend into the flue gas duct, they move and purge above the plate catalyst bed to remove the ash accumulated at the opening above the plate catalyst bed.

[0015] Furthermore, the flare of each sonic sootblower is located close to the upper part of the side wall of the flue gas duct where the corresponding rake sootblower is located.

[0016] Furthermore, the device is characterized by having an ammonia atomizing device installed in the medium-high temperature SCR denitrification unit, which atomizes the ammonia water when it is sprayed out, thereby better mixing with the flue gas and improving the denitrification efficiency.

[0017] Furthermore, the ammonia atomization device is equipped with two spray guns, namely an internal spray gun and a pre-ammonia spray gun. The internal spray gun provides ammonia water for the denitrification reaction inside the medium-high temperature SCR denitrification device; the pre-ammonia spray gun is set at the outlet of the first-stage waste heat boiler to pre-spray ammonia, which is used to improve the denitrification reaction efficiency.

[0018] A bypass pipe A is installed in the pipeline between the electric arc furnace and the first-stage waste heat boiler. The bypass pipe A is used to connect the pre-ammonia injection gun. An ammonia injection grid A is installed in the pipeline between the electric arc furnace AC / DC furnace and the first-stage waste heat boiler and the bypass pipe A, and between the pipeline and the inlet of the first-stage waste heat boiler. This is used to ensure that the ammonia gas injected by the pre-ammonia injection gun and the flue gas are fully mixed.

[0019] Furthermore, a bypass pipe B is installed in the flue gas duct between the outlet of the waste heat boiler and the inlet of the medium-high temperature SCR denitrification unit for connecting the internal spray gun;

[0020] An ammonia injection grid B is installed at the junction of the flue gas pipeline from the inlet of the medium-high temperature SCR denitrification unit to the waste heat boiler and the bypass pipeline B, which is used to ensure that the ammonia gas sprayed from the internal spray gun is fully mixed with the flue gas.

[0021] Based on the same inventive concept, this utility model also provides an industrial silicon production line, which includes a submerged arc furnace and the aforementioned industrial silicon smelting flue gas purification system.

[0022] Based on the same inventive concept, this utility model also provides an industrial silicon production line, which includes a submerged arc furnace and the aforementioned industrial silicon smelting flue gas purification system.

[0023] The beneficial effects of this utility model are:

[0024] The industrial silicon smelting flue gas purification system and production line provided by this utility model uses a medium-high temperature SCR denitrification device and introduces a pre-stage waste heat boiler to regulate the flue gas temperature to the SCR temperature window. Combined with a specially designed rake soot blower and sonic soot blower dual cleaning mechanism, it prevents catalyst poisoning, blockage and ash adhesion, and improves the denitrification efficiency to as high as 95%. It breaks through the bottleneck that the denitrification efficiency of NOx concentrations above 500mg / Nm³ cannot exceed 90% in the existing technology. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 Schematic diagram of an industrial silicon smelting flue gas purification system;

[0027] Figure 2 This is a structural diagram of an industrial silicon smelting flue gas purification system.

[0028] Figure 3 This is a top view of a rake-type soot blower and a plate-type catalyst bed. Detailed Implementation

[0029] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0030] The following disclosure provides many different embodiments or examples for implementing various structures of this invention. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this invention.

[0031] The embodiments of the utility model will now be described in detail with reference to the accompanying drawings.

[0032] As attached Figure 1 To be continued Figure 3 As shown, the industrial silicon smelting flue gas purification system disclosed in this embodiment includes the following components: a primary waste heat boiler 1, a medium-high temperature SCR denitrification device 3, three rake soot blowers 7, three acoustic soot blowers 8, a secondary waste heat boiler 4, a filter dust collector 2, and a wet desulfurization tower 6. Based on the complete structure of the above-mentioned industrial silicon smelting flue gas purification system, this embodiment also provides a submerged arc furnace 5. The industrial silicon smelting flue gas purification system purifies the flue gas discharged from the submerged arc furnace 5. The functions and connections of the above components are described below.

[0033] A waste heat boiler 1 is used to receive the flue gas discharged from the electric arc furnace 5 and to perform a waste heat recovery on the flue gas discharged from the electric arc furnace 5.

[0034] The medium-high temperature SCR denitrification unit 3 contains three plate catalyst beds 31. The medium-high temperature SCR denitrification unit 3 uses the plate catalyst beds 31 to perform SCR denitrification on the flue gas from primary waste heat recovery; as shown in the attached diagram. Figure 2 As shown, the flue gas duct where the medium-high temperature SCR denitrification unit 3 is located is a vertical straight duct. Each plate catalyst bed 31 is arranged from top to bottom in this section of the flue gas duct, and the cross-section of the plate catalyst bed 31 is vertical.

[0035] The rake soot blower 7 is connected to the medium-high temperature SCR denitrification device 3 and is used to remove dust from the surface of the plate catalyst bed 31. An air heating device is installed inside the rake soot blower 7, which allows the rake soot blower 7 to blow out air at 200℃-300℃. When the temperature is 200℃-300℃, it is easier to remove dust from the plate catalyst bed 31 and less likely to produce sticky dust.

[0036] The sonic soot blower 8 is connected to the medium-high temperature SCR denitrification device 3. The sonic soot blower 8 cleans the dust inside the plate catalyst bed 31 by causing the plate catalyst bed 31 to vibrate. The specific process is as follows: because the cross-section of the plate catalyst bed 31 is vertical, the dust will fall out from the thin mesh in the plate catalyst bed 31 due to vibration.

[0037] Secondary waste heat boiler 4 is used to receive the denitrified flue gas and perform secondary waste heat recovery on the denitrified flue gas.

[0038] Filter dust collector 2 is used to remove dust from the flue gas after secondary waste heat recovery.

[0039] The wet desulfurization tower 6 is used to receive the flue gas after secondary waste heat recovery and perform wet desulfurization on it to generate purified flue gas.

[0040] The beneficial effects of the above technical solution are as follows: By using the medium-high temperature SCR denitrification device 3 and introducing a pre-stage waste heat boiler 1 to adjust the flue gas temperature to the SCR temperature window, combined with the specially designed rake soot blower 7 (providing 200-300℃ hot air to prevent ash adhesion) and the sonic soot blower 8 dual ash removal mechanism, the problems of catalyst poisoning, blockage and ash adhesion in the existing technology are significantly solved, the denitrification efficiency is improved, and the denitrification efficiency reaches up to 95%, breaking through the bottleneck that the denitrification efficiency of NOx concentrations above 500mg / Nm³ cannot exceed 90% in the existing technology.

[0041] As attached Figure 3 As shown, each rake soot blower 7 is connected to the side wall of the flue gas duct. Each connection is located on the upper part of the side wall of the flue gas duct where each plate catalyst bed 31 is located. The rake soot blower 7 is equipped with a retractable blow pipe 72. Two rows of purging pipes 73 are installed on the blow pipe 72. After the blow pipe 72 extends into the flue gas duct, it moves and purifies above the plate catalyst bed 31 to remove the ash accumulated at the opening above the plate catalyst bed 31.

[0042] Furthermore, the flare of each sonic sootblower 8 is located close to the upper part of the side wall of the flue gas duct where the corresponding rake sootblower 7 is located.

[0043] Furthermore, the medium-high temperature SCR denitrification unit 3 is equipped with an ammonia water atomization device, which makes the ammonia water form an atomization effect when it is sprayed out, thereby better mixing with the flue gas and improving the denitrification efficiency.

[0044] Furthermore, the ammonia atomizing device is equipped with two spray guns, namely an internal spray gun and a pre-ammonia spray gun. The internal spray gun provides ammonia water for the denitrification reaction inside the medium-high temperature SCR denitrification unit 3; the pre-ammonia spray gun is set at the outlet of the first-stage waste heat boiler 1 to pre-spray ammonia, which is used to improve the denitrification reaction efficiency.

[0045] A bypass pipe A 51 is installed in the pipeline between the electric arc furnace 5 and the first-stage waste heat boiler 1. The bypass pipe A 51 is used to connect the pre-ammonia injection gun. An ammonia injection grid A 52 is installed in the pipeline between the junction of the electric arc furnace 5 and the first-stage waste heat boiler 1 and the bypass pipe A 51 and the inlet of the first-stage waste heat boiler 1. This grid is used to ensure that the ammonia gas injected by the pre-ammonia injection gun and the flue gas are fully mixed.

[0046] Furthermore, a bypass pipe B 11 is installed in the flue gas duct between the outlet of the waste heat boiler 1 and the inlet of the medium-high temperature SCR denitrification unit 3 for connecting the internal spray gun;

[0047] An ammonia injection grid B12 is installed at the junction of the flue gas pipeline and the bypass pipeline B11 between the inlet of the medium-high temperature SCR denitrification unit 3 and the inlet of the medium-high temperature SCR denitrification unit 3, so as to fully mix the ammonia gas sprayed from the internal spray gun with the flue gas.

[0048] The beneficial effects of the above technical solution are as follows: In terms of catalyst arrangement and soot blowing, each layer of plate catalyst bed 31 is arranged sequentially from top to bottom in the flue gas duct and the cross-section is vertically oriented, which is conducive to the uniform flow of flue gas and improves the denitrification efficiency; the rake soot blower 7 is installed on the upper part of the corresponding catalyst side wall and has a retractable blow pipe 72. The two rows of blow pipes 73 on it can penetrate into the duct and move to blow above the catalyst, which can effectively remove the ash accumulated at the upper opening. In conjunction with the sonic soot blower 8 close to the rake soot blower 7, the dust inside the catalyst is further cleaned by vibration, ensuring the cleanliness of the catalyst and maintaining the high efficiency of denitrification performance.

[0049] Regarding ammonia injection and mixing, the ammonia atomizing device in the medium-high temperature SCR denitrification unit 3 enables the ammonia water to form an atomized effect when sprayed, fully mixing with the flue gas and improving denitrification efficiency. The internal spray gun is responsible for providing ammonia water for the denitrification reaction inside the unit. The pre-spray ammonia spray gun is set at the outlet of the first-stage waste heat boiler 1 to pre-spray ammonia, which can further improve the denitrification efficiency. The two work together, and the bypass pipe A 51 connects the pre-spray ammonia spray gun and the ammonia spray grid A 52 to ensure that the ammonia gas and flue gas are fully mixed. The bypass pipe B 11 connects the internal spray gun and the ammonia spray grid B 12 to ensure that the ammonia gas sprayed from the internal spray gun is fully mixed with the flue gas. The entire system makes the ammonia water and flue gas mix more evenly and fully. The ammonia water injection and mixing are optimized from multiple links and multiple positions, comprehensively improving the denitrification efficiency and ensuring the efficient and stable operation of the industrial silicon smelting flue gas purification system, which has significant environmental and economic benefits.

[0050] Based on the same inventive concept, this embodiment also provides an industrial silicon production line, which includes a submerged arc furnace and the aforementioned industrial silicon smelting flue gas purification system.

[0051] Based on the same inventive concept, this embodiment also provides an industrial silicon production line, which includes a submerged arc furnace and the aforementioned industrial silicon smelting flue gas purification system.

Claims

1. An industrial silicon smelting flue gas purification system, characterized in that, include: A first-stage waste heat boiler is used to receive the flue gas discharged from the electric arc furnace and perform a first-stage waste heat recovery on the flue gas discharged from the electric arc furnace. The medium-high temperature SCR denitrification unit has three plate catalyst beds. The medium-high temperature SCR denitrification unit performs SCR denitrification on the flue gas after primary waste heat recovery through the plate catalyst beds. Each plate catalyst bed is arranged from top to bottom in the flue gas duct, and the cross-section of the plate catalyst bed is vertical. Three rake soot blowers are connected to the medium-high temperature SCR denitrification unit to remove ash from the surface of the plate catalyst bed. An air heating device is installed inside the rake soot blower, which enables the rake soot blower to blow out air at 200℃-300℃. Three sonic soot blowers are connected to the medium-high temperature SCR denitrification unit. The sonic soot blowers clean the dust inside the plate catalyst bed by causing the plate catalyst bed to vibrate. The second-stage waste heat boiler is used to receive the denitrified flue gas and perform secondary waste heat recovery on the denitrified flue gas. Dust collectors are used to remove dust from flue gas after secondary waste heat recovery. A wet desulfurization tower is used to receive flue gas after secondary waste heat recovery and perform wet desulfurization on it to generate purified flue gas.

2. The industrial silicon smelting flue gas purification system according to claim 1, characterized in that, Each rake soot blower is connected to the side wall of the flue gas duct. Each connection is located on the upper part of the side wall of the flue gas duct where each plate catalyst bed is located. The rake soot blower is equipped with a retractable blowpipe with two rows of purging pipes installed on it. After the blowpipes extend into the flue gas duct, they move and purge above the plate catalyst bed to remove the ash accumulated at the opening above the plate catalyst bed.

3. The industrial silicon smelting flue gas purification system according to claim 1, characterized in that, The flare of each sonic sootblower is located close to the upper part of the side wall of the flue gas duct where the corresponding rake sootblower is located.

4. The industrial silicon smelting flue gas purification system according to any one of claims 1-3, characterized in that, The medium- and high-temperature SCR denitrification unit is equipped with an ammonia water atomization device, which atomizes the ammonia water when it is sprayed out, thereby better mixing with the flue gas and improving the denitrification efficiency.

5. The industrial silicon smelting flue gas purification system according to claim 4, characterized in that, The ammonia atomizing device is equipped with two spray guns: an internal spray gun and a pre-ammonia spray gun. The internal spray gun provides ammonia for the denitrification reaction inside the medium- and high-temperature SCR denitrification device. The pre-ammonia injection gun is set at the outlet of the first-stage waste heat boiler to pre-inject ammonia in order to improve the reaction efficiency of denitrification. A bypass pipe A is installed in the pipeline between the electric arc furnace and the first-stage waste heat boiler. The bypass pipe A is used to connect the pre-ammonia injection gun. An ammonia injection grid A is installed in the pipeline between the electric arc furnace AC / DC furnace and the first-stage waste heat boiler and the bypass pipe A, and between the pipeline and the inlet of the first-stage waste heat boiler. This is used to ensure that the ammonia gas injected by the pre-ammonia injection gun and the flue gas are fully mixed.

6. The industrial silicon smelting flue gas purification system according to claim 5, characterized in that, A bypass pipe B is installed in the flue gas pipeline between the outlet of the waste heat boiler and the inlet of the medium-high temperature SCR denitrification unit for connecting the internal spray gun; An ammonia injection grid B is installed at the junction of the flue gas pipeline from the inlet of the medium-high temperature SCR denitrification unit to the waste heat boiler and the bypass pipeline B, which is used to ensure that the ammonia gas sprayed from the internal spray gun is fully mixed with the flue gas.

7. An industrial silicon production line, characterized in that, The system includes a direct-flow electric arc furnace and the industrial silicon smelting flue gas purification system as described in any one of claims 1-6.

8. An industrial silicon production line, characterized in that, It includes a submerged arc furnace and an industrial silicon smelting flue gas purification system as described in any one of claims 1-6.

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