Submerged arc furnace gas purifying and recycling system and technology

Abstract

The invention provides a submerged arc furnace gas purification and reutilization system and process, and relates to the technical field of industrial waste gas recycling, the submerged arc furnace gas purification and reutilization system comprises a gas sedimentation purification unit, a cloth bag dust removal unit and a fan unit; the coal gas settling and purifying unit is used for carrying out four-stage settling and purifying treatment on coal gas discharged by a submerged arc furnace, the cloth bag dust removal unit is used for carrying out dust removal treatment on the coal gas from the coal gas settling and purifying unit, and the fan unit comprises a gas purifying fan; the gas purifying fan is used for feeding the coal gas from the cloth bag dust removal unit into the rotary kiln; the system provided by the invention is excellent in stability and good in dust removal effect.

Description

Technical Field

[0001] This invention relates to the field of industrial waste gas recovery and utilization technology, and in particular to a system and process for purifying and reusing blast furnace gas. Background Technology

[0002] The production process of electric arc furnaces generates a large amount of high-temperature coal gas containing combustible components such as CO and H2, but also impurities such as dust, tar, and sulfides. The high temperature, high dust content, and complex composition mean that direct emission would result in energy waste and environmental pollution. Traditional wet dust removal coal gas purification systems are bulky, occupy a large area, consume a lot of water, and generate secondary pollution (wastewater). Dry dust removal systems have low efficiency in removing fine dust, cannot effectively remove tar, and are prone to damage at high temperatures. Electrostatic precipitators have high investment costs and complex maintenance. The purified coal gas is usually used for power generation or combustion, but it is not directly coupled with the rotary kiln process, resulting in low energy utilization. Rotary kilns rely heavily on pulverized coal or natural gas for fuel, leading to high operating costs and failing to meet green production requirements.

[0003] Current technologies have failed to enable the direct use of blast furnace gas for rotary kiln pulverized coal injection, primarily due to substandard gas purification (high dust content, etc.). Traditional gas purification requires multi-stage washing, electrostatic precipitator for tar, desulfurization, and other processes, resulting in high equipment investment, high energy consumption, and complex purification processes. Furthermore, the unstable calorific value of the gas, when directly injected into the rotary kiln, easily leads to kiln temperature fluctuations, affecting product quality. Additionally, the mixture of dust and tar in the gas easily clogs the injection nozzles, making long-term stable operation impossible.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The present invention aims to provide an efficient, low-cost, and stable coal gas purification system and process for submerged arc furnaces, and to directly use the purified coal gas in the rotary kiln pulverized coal injection system to replace part of the pulverized coal, reduce fuel costs, achieve clean and efficient utilization of coal gas, reduce environmental pollution, and improve the stability and reliability of system operation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a system for purifying and reusing coal gas from a submerged arc furnace, comprising a coal gas settling and purification unit, a bag filter unit, and a fan unit.

[0008] The gas settling and purification unit is used to perform four-stage settling and purification treatment on the gas discharged from the electric arc furnace. The bag filter unit is used to remove dust from the gas from the gas purification unit. The fan unit includes a clean air fan, which is used to feed the gas from the bag filter unit into the rotary kiln.

[0009] The gas settling and purification unit includes a primary settling device, a secondary settling device, a tertiary settling device, and a quaternary settling device connected in series.

[0010] The air outlet pipes of the first-stage, second-stage, third-stage, and fourth-stage settling tanks are all vertically installed at the top of the settling tank, and the air inlet pipes are all installed at the bottom of the settling tank.

[0011] The angle between the air inlet pipes of the secondary, tertiary, and quaternary settling tanks and the side wall of the corresponding settling tank is 8°-12°.

[0012] The air outlet pipe of the first-stage sedimentation unit and the air inlet pipe of the second-stage sedimentation unit are connected by a first pipe;

[0013] The angle between the air outlet pipe of the first-stage sedimentation unit and the first pipe is 55°-60°.

[0014] The air outlet pipe of the secondary settling device and the air inlet pipe of the tertiary settling device are connected by a second pipe;

[0015] The included angle between the air outlet pipe of the secondary settling device and the second pipe is 55°-60°;

[0016] The air outlet pipe of the third-stage sedimentation unit and the air inlet pipe of the fourth-stage sedimentation unit are connected by a third pipe;

[0017] The included angle between the air outlet pipe of the three-stage sedimentation unit and the third pipe is 55°-60°.

[0018] Furthermore, based on the above technical solution, dust collection hoppers are provided at the angles between the air outlet pipe of the first-stage sedimentation unit and the first pipe, the angles between the air outlet pipe of the second-stage sedimentation unit and the second pipe, and the angles between the air outlet pipe of the third-stage sedimentation unit and the third pipe, to collect larger dust particles that separate due to inertia and prevent pipe blockage.

[0019] Furthermore, based on the above technical solution, the settling chambers of the first-stage settling device, second-stage settling device, third-stage settling device and fourth-stage settling device are arranged in the shape of an inverted frustum at the bottom of the settling device tank;

[0020] The angle between the diameter of the upper bottom surface of the settling chamber and the generatrix passing through the endpoint of the diameter is 15°-20°.

[0021] Furthermore, based on the above technical solution, the bag filter unit includes multiple bag filters arranged in parallel. Preferably, the multiple bag filters include a first bag filter, a second bag filter, and a third bag filter.

[0022] The dust hoppers of the first, second, and third bag filters are arranged in the shape of an inverted frustum at the bottom of the bag filters;

[0023] The diameter of the top surface of the ash hopper and the angle between it and the generatrix passing through the endpoint of the diameter are 15°-20°.

[0024] Furthermore, based on the above technical solution, the fan unit also includes a coarse air fan, the outlet pipe of which is connected to the inlet pipes of the first bag filter, the second bag filter and the third bag filter respectively, for conveying the coal gas from the four-stage settling device to the first bag filter, the second bag filter and the third bag filter respectively.

[0025] The exhaust pipe of the fourth-stage settling device and the intake pipe of the coarse gas blower form a herringbone flue; the included angle between the exhaust pipe of the fourth-stage settling device and the intake pipe of the coarse gas blower is 55°-60°.

[0026] The exhaust pipes of the first, second, and third bag filters are respectively connected to the clean air fan.

[0027] Furthermore, based on the above technical solutions, the first bag filter, the second bag filter, and the third bag filter are all spherical explosion-proof bag filters.

[0028] Furthermore, based on the above technical solution, the settling chambers of the primary settling device and the secondary settling device are both connected to the first ash storage silo via pipelines, so as to transport the dust and tar in the settling chambers of the primary settling device and the secondary settling device to the first ash storage silo.

[0029] The settling chambers of the three-stage settling device and the four-stage settling device, as well as the ash hopper of the first bag filter, are all connected by pipes to the second ash storage hopper, so as to transport the dust and tar in the settling chambers of the three-stage settling device and the four-stage settling device, as well as the dust in the ash hopper of the first bag filter, to the second ash storage hopper.

[0030] The dust hoppers of the second and third bag filters are connected to the third ash storage silo via pipes to transport the dust in the dust hoppers of the second and third bag filters to the third ash storage silo.

[0031] Furthermore, based on the above technical solution, compensators are installed on the first, second, and third pipelines.

[0032] Furthermore, based on the above technical solution, the first-stage settling device, the second-stage settling device, the third-stage settling device and the fourth-stage settling device are all dust and tar settling devices. Each dust and tar settling device is equipped with a bin wall vibrator inside the tank, a self-closing explosion-proof valve at the top of the tank, and a connecting flange at the bottom of the tank to transport the dust to the ash storage bin.

[0033] The primary settling tank is a hollow cavity; the secondary, tertiary, and quaternary settling tanks are all equipped with multiple layers of baffles inside their tanks.

[0034] The present invention also provides a process for purifying and reusing blast furnace gas, which operates using the system described above and includes the following steps:

[0035] S1: The blast furnace gas enters the first-stage settling tank, the second-stage settling tank, the third-stage settling tank and the fourth-stage settling tank in sequence for dust and tar settling and purification treatment.

[0036] S2: The gas enters the coarse gas blower from the four-stage settling tank, and then enters the bag filter unit for dust removal.

[0037] S3: The gas treated by the bag filter unit is transported to the rotary kiln as fuel by the clean air blower.

[0038] The present invention provides a system and process for purifying and reusing coal gas from a submerged arc furnace, which has the following beneficial effects:

[0039] 1. The exhaust gas produced by the electric furnace has a maximum temperature of 800-1000℃. It then enters the four-stage settling tank of the gas settling and purification unit to remove large dust particles and some tar, thus achieving cooling. The gas temperature in the system after treatment by the gas settling and purification unit is controlled at approximately 220-250℃. After treatment by the four-stage settling tank, the gas is then sent to the bag filter unit by a coarse air blower. After cooling, the gas passes through the bag filter, and the dust concentration is controlled at 8mg / Nm³. 2 The gas is then introduced into the rotary kiln pulverized coal injection system via a clean air blower. This process ensures good stability and is compatible with current rotary kiln smelting technology.

[0040] 2. The submerged arc furnace gas purification system provided by this invention employs an 8°-12° inlet angle and a 55°-60° connection angle design in the settling tank pipeline. This design allows the gas to be smoothly introduced into each stage of the settling tank, creating a stable laminar flow environment, ensuring deep settling, and achieving efficient inertial pre-separation to intercept coarse particles in advance. The synergistic effect of these two aspects ensures the purification effect of the gas, enabling the system to continuously produce purified gas with a highly stable calorific value, which can be directly injected into the rotary kiln without easily causing kiln temperature fluctuations. At the same time, the dust concentration in the gas is reduced to an extremely low level, fundamentally avoiding the risk of dust and tar mixing and sticking together to clog the spray gun. The entire system, thanks to its excellent design, ensures outstanding stability during long-term operation. Attached Figure Description

[0041] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the gas settling and purification unit in the submerged arc furnace gas purification and reuse system provided in an embodiment of the present invention.

[0043] Figure 2 A schematic diagram of the bag filter unit structure in the blast furnace gas purification and reuse system provided in an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the ash collection hopper structure provided in an embodiment of the present invention;

[0045] Figure label:

[0046] 1. Primary settling tank; 11. Air outlet pipe of primary settling tank; 12. First pipe; 13. Air inlet pipe of primary settling tank;

[0047] 2. Secondary settling tank; 21. Air outlet pipe of the secondary settling tank; 22. Second pipe; 23. Air inlet pipe of the secondary settling tank;

[0048] 3. Three-stage settling tank; 31. Air outlet pipe of the three-stage settling tank; 32. Third pipe; 33. Air inlet pipe of the three-stage settling tank;

[0049] 4. Fourth-stage settling tank; 41. Air outlet pipe of the fourth-stage settling tank; 42. Air inlet pipe of the third-stage settling tank;

[0050] 5. Coarse air blower; 51. Inlet duct of coarse air blower;

[0051] 6. First bag filter; 7. Second bag filter; 8. Third bag filter; 9. Purification fan; 10. Settling bin; 14. Ash hopper; 15. First ash storage bin; 16. Second ash storage bin; 17. Third ash storage bin; 18. Ash collection hopper. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0053] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0054] According to a first aspect of the present invention, a specific embodiment of the present invention provides a gas purification and reuse system for submerged arc furnaces, comprising a gas settling and purification unit, a bag filter unit, and a fan unit;

[0055] The gas settling and purification unit is used to perform four-stage settling and purification treatment on the gas discharged from the electric arc furnace. The bag filter dust removal unit is used to remove dust from the gas from the gas settling and purification unit. The fan unit includes a clean air fan, which is used to feed the gas from the bag filter dust removal unit into the rotary kiln.

[0056] The gas settling and purification unit includes a primary settling device 1, a secondary settling device 2, a tertiary settling device 3, and a quaternary settling device 4 connected in series.

[0057] The air outlet pipes of the first-stage sedimentation tank 1, the second-stage sedimentation tank 2, the third-stage sedimentation tank 3 and the fourth-stage sedimentation tank 4 are all vertically installed at the top of the sedimentation tank, and the air inlet pipes are all installed at the bottom of the sedimentation tank.

[0058] The angle between the air inlet pipes of the secondary settling tank 2, the tertiary settling tank 3 and the quaternary settling tank 4 and the corresponding settling tank side wall is 8°-12° (e.g., 9°, 10°, 11°, etc.) (the air inlet pipe 13 of the primary settling tank is connected to the electric arc furnace, and the angle with the tank is a conventional setting and is not specifically limited).

[0059] Specifically, by limiting the angle between the air inlet pipes of the secondary settling tank 2, the tertiary settling tank 3, and the quaternary settling tank 4 and the corresponding settling tank sidewall to 8°-12°, which is smaller than the angle between the air outlet pipes of each settling tank and the first pipe 1, the second pipe 22, and the third pipe 32 respectively, the air inlet angle is steeper, which is beneficial to the settling of solid dust and tar when the gas enters the settling tank. Compared with conventional right-angle sharp turns, the gas conveying angle design of this invention not only enhances the separation effect of solid dust and tar in the gas, but also significantly reduces the local resistance of the airflow and avoids turbulence caused by sudden changes in flow velocity. The airflow provides a stable gravity settling environment for dust, effectively improving dust deposition at corners and ensuring normal equipment operation. However, if the angle between the air inlet pipe of each settling device and the corresponding settling tank is less than 8°, the airflow will form a wall-adhering flow. The gas velocity is low near the wall due to viscosity, while dust particles tend to maintain their original trajectory due to inertia. However, due to the wall obstruction and the influence of the low flow velocity zone, they are very easy to deposit on the wall, especially at the connection between the air inlet pipe and the settling device, which is very likely to cause dust blockage of the pipe. Moreover, a small angle means that the air inlet pipe is relatively long, occupies a lot of space, and is difficult and costly to build.

[0060] The air outlet pipe 11 of the primary settling tank and the air inlet pipe 23 of the secondary settling tank are connected by the first pipe 12;

[0061] The included angle between the air outlet pipe 11 and the first pipe 12 of the first stage sedimentation unit is 55°-60° (e.g., 56°, 57°, 58°, 59°, etc.).

[0062] The air outlet pipe 21 of the secondary settling tank and the air inlet pipe 33 of the tertiary settling tank are connected by the second pipe 22;

[0063] The included angle between the air outlet pipe 21 and the second pipe 22 of the secondary settling device is 55°-60° (e.g., 56°, 57°, 58°, 59°, etc.).

[0064] The air outlet pipe 31 of the third-stage sedimentation unit and the air inlet pipe 42 of the fourth-stage sedimentation unit are connected by the third pipe 32.

[0065] The included angle between the vent pipe 31 and the third pipe 32 of the three-stage settling device is 55°-60° (e.g., 56°, 57°, 58°, 59°, etc.).

[0066] As an optional embodiment of the present invention, ash collection hoppers 18 are provided at the angle between the air outlet pipe 11 and the first pipe 12 of the first-stage sedimentation unit, the angle between the air outlet pipe 21 and the second pipe 22 of the second-stage sedimentation unit, and the angle between the air outlet pipe 31 and the third pipe 32 of the third-stage sedimentation unit, to collect larger dust particles that separate due to inertia and avoid clogging the pipes.

[0067] Specifically, when the airflow changes direction within a pipe angle of 55°-60°, the inertia of heavier dust particles makes it difficult for them to follow the airflow at a large angle, thus causing them to impact the outer wall of the first pipe 12, the second pipe 22, or the third pipe 32 and settle. This can remove some medium and coarse particles before the gas enters the next stage settling tank (these medium and coarse particles will fall into the dust collection hopper 18 set at the bend), reducing the load on the next stage settling tank and achieving effective interstage pre-dust removal. If the airflow changes direction within a pipe angle greater than 60°, some fine particles that have already impacted the pipe wall may be re-entrained by strong eddies, making effective inertial pre-separation impossible. If the airflow changes direction within a pipe angle less than 55°, the airflow turning angle is too large, which will weaken the inertial separation of the airflow and render the pre-dust removal effect at the bend ineffective.

[0068] As an optional embodiment of the present invention, the settling chamber 10 of the first-stage settling tank 1, the second-stage settling tank 2, the third-stage settling tank 3 and the fourth-stage settling tank 4 is arranged in the shape of an inverted frustum at the bottom of the tank body of the settling tank.

[0069] The angle between the diameter of the upper bottom surface of the settling chamber 10 and the generatrix passing through the endpoint of the diameter is 15°-20° (e.g., 16°, 17°, 18°, 19°, etc.).

[0070] Specifically, setting the included angle to 15°-20° can reduce the vertical pressure of dust, and the wall inclination angle also reduces the adhesion area, effectively preventing arching and wall adhesion. Moreover, the angle is greater than the angle of repose of most dust particles, allowing the dust to slide smoothly to the discharge port under the action of gravity with virtually no residue. If the angle is too small, the vertical pressure is high, the interparticle squeezing force is strong, and mechanical bridging is very easy to form. If the angle is too large, in order to achieve the same ash storage capacity, the settling bin will be abnormally tall, increasing the total height of the equipment and the cost.

[0071] As an optional embodiment of the present invention, the bag filter unit includes multiple bag filters arranged in parallel. The number of bag filters can be determined according to the actual flue gas treatment volume. For example, the multiple bag filters may include a first bag filter 6, a second bag filter 7, and a third bag filter 8; the following description uses three bag filters as an example.

[0072] The dust hoppers 14 of the first bag filter 6, the second bag filter 7, and the third bag filter 8 are arranged in the shape of an inverted frustum at the bottom of the bag filter.

[0073] The diameter of the upper bottom surface of the ash hopper 14 and the angle between it and the generatrix passing through the endpoint of the diameter are 15°-20°.

[0074] As an optional embodiment of the present invention, the fan unit further includes a coarse air fan 5, the outlet pipe of the coarse air fan 5 being connected to the inlet pipes of the first bag filter 6, the second bag filter 7 and the third bag filter 8 respectively, for conveying the coal gas from the four-stage settling tank 4 to the first bag filter 6, the second bag filter 7 and the third bag filter 8 respectively.

[0075] The exhaust pipe 41 of the four-stage settling unit and the intake pipe 51 of the coarse gas blower form a herringbone flue. The included angle between the exhaust pipe 41 of the four-stage settling unit and the intake pipe 51 of the coarse gas blower is 55°-60° (e.g., 56°, 57°, 58°, 59°, etc.). There is no need to install a dust collection hopper at the included angle between the exhaust pipe 41 of the four-stage settling unit and the intake pipe 51 of the coarse gas blower. After the four-stage settling purification treatment, the content of larger dust particles is reduced, and the risk of clogging the pipes is low.

[0076] In one optional embodiment of the present invention, the outlet pipes of the first bag filter 6, the second bag filter 7, and the third bag filter 8 are respectively connected to the clean air blower 9. Specifically, the outlet pipes of the first bag filter 6, the second bag filter 7, and the third bag filter 8 converge onto a main pipe, which is connected to the inlet of the clean air blower 9. The gas discharged from the clean air blower 9 can be used as fuel for the rotary kiln.

[0077] As an optional embodiment of the present invention, compensators are provided on the first pipe 12, the second pipe 22 and the third pipe 32 to reduce the stress caused by temperature changes or mechanical vibrations in the pipes, and also to help maintain the sealing of the pipes and the smoothness of airflow, and prevent the gas flow and dust removal effect from being affected by pipe deformation.

[0078] As an optional embodiment of the present invention, the settling chambers 10 of the primary settling tank 1 and the secondary settling tank 2 are both connected to the first ash storage silo 15 through pipes, so as to transport the dust and tar in the settling chambers 10 of the primary settling tank 1 and the secondary settling tank 2 to the first ash storage silo 15.

[0079] The settling chambers 10 of the three-stage settling tank 3 and the four-stage settling tank 4, as well as the ash hopper 14 of the first bag filter 5, are all connected by pipes to the second ash storage hopper 16 to transport the dust and tar in the settling chambers 10 of the three-stage settling tank 3 and the four-stage settling tank 4, as well as the dust in the ash hopper 14 of the first bag filter 5, to the second ash storage hopper 16.

[0080] The dust hoppers 14 of the second bag filter 7 and the third bag filter 8 are both connected to the third dust storage bin 17 via pipes, so as to transport the dust in the dust hoppers 14 of the second bag filter 7 and the third bag filter 8 to the third dust storage bin 17.

[0081] As an optional embodiment of the present invention, the primary settling tank 1, the secondary settling tank 2, the tertiary settling tank 3, and the quaternary settling tank 4 are all dust and tar settling tanks. Each dust and tar settling tank is equipped with a silo wall vibrator inside its tank body, a self-closing explosion-proof valve at the top of the tank body, and a connecting flange at the bottom of the tank body to transport the dust to the ash storage silo. The dust in each ash storage silo is transported to the purification ash silo by a sealed scraper conveyor for unloading and external transportation.

[0082] The primary settling tank 1 is a hollow cavity; the secondary settling tank 2, tertiary settling tank 3, and quaternary settling tank 4 are all equipped with multiple layers of baffles. The baffles can be conventionally configured to enhance the settling of powders or tar.

[0083] As an optional embodiment of the present invention, the first bag filter 6, the second bag filter 7, and the third bag filter 8 are all spherical explosion-proof bag filters.

[0084] Specifically, because the furnace gas (i.e., blast furnace gas) has a high CO content and is a special explosive gas, the design adopts an explosion-proof bag filter with a spherical design, which has better airtightness and pressure resistance. Each dust collector is equipped with furnace gas backflushing, which can thoroughly remove the dust adhering to the surface of the filter bag. When manufacturing the bag filter, it is necessary to ensure that the welding is flat and smooth, without leaving any dead corners, to prevent ash accumulation.

[0085] Specifically, to facilitate the maintenance of the dust collector, each dust collector has 8 compartments, and there are a total of 24 compartments in 3 bag dust collectors. The design also takes into account issues such as eliminating structural thermal stress and compensating for thermal expansion. Each compartment in the dust collector must be reliably isolated to meet the requirements for online bag replacement.

[0086] Furthermore, the filter bags used in the baghouse dust collector are membrane-coated fluoropolymer bags commonly used in the industrial submerged arc furnace industry. These filter bags have high temperature resistance, good corrosion resistance, high filtration accuracy, and can withstand high wind speeds of up to 1 m / min.

[0087] Furthermore, from a safety perspective, this invention installs an explosion-proof valve on each bag filter to protect the entire body of the dust collector in case of an accident. Simply replace the explosion-proof valve diaphragm (add an explosion-proof self-closing valve).

[0088] According to a second aspect of the present invention, a process for purifying and reusing blast furnace gas is provided, which operates using the system described above and includes the following steps:

[0089] S1: The blast furnace gas sequentially enters the primary settling tank 1, secondary settling tank 2, tertiary settling tank 3, and quaternary settling tank 4 for dust and tar settling and purification treatment.

[0090] S2: The gas enters the coarse gas fan 5 from the four-stage settling tank 4, and then enters the bag dust collection unit, such as the first bag dust collector 6, the second bag dust collector 7 and the third bag dust collector 8 for dust removal.

[0091] S3: The gas treated by the bag filter unit is transported to the rotary kiln as fuel by the clean air blower 9.

[0092] As an optional embodiment of the present invention, the technical parameters of the first bag filter 6, the second bag filter 7, and the third bag filter 8 are as follows:

[0093] 1) Fluoromex bag filter specifications: Ф132×5000;

[0094] 2) A complete set of fluoropolymer bags contains 432 bags;

[0095] 3) Bag filter area 895m² 2 ;

[0096] 4) The operating temperature of the cloth bag is <250℃;

[0097] 5) The maximum operating temperature of the cloth bag is 350℃ (30 minutes);

[0098] 6) Filter bag material: 20# carbon steel;

[0099] 7) Filtration velocity < 0.39 m / min;

[0100] 8) Dust concentration at the outlet ≤ 10 mg / m³ 3 ;

[0101] 9) Dust removal efficiency reaches 99.8%;

[0102] 10) The bag filter has a sealed structure with upper and lower parts, three bags per group, and twenty-four chambers. The upper part of the dust collector is equipped with a nitrogen back-flushing device and a special mechanism to back-flush and clean the bags in the twenty-four chambers in turn. The lower part of the dust collector is equipped with a nitrogen inlet pipe.

[0103] As an optional embodiment of the present invention, the technical parameters of the coarse air blower 5 are as follows:

[0104] 1) Equipped with a variable frequency motor, quantity 1 unit;

[0105] 2) The impeller of the fan is made of heat-resistant, wear-resistant, low-alloy, high-strength structural steel material Q420C;

[0106] 3) The fan shaft material is 45# steel;

[0107] 4) The shaft end seal uses a return pipe;

[0108] 5) The bearings are lubricated with machine oil, and the bearing housings are cooled with circulating water;

[0109] 6) The matching centrifugal motor is an explosion-proof asynchronous motor with an explosion-proof rating of DIIBT4;

[0110] 7) The protection level of the frequency converter motor is IP54, and the insulation class is F.

[0111] The technical parameters of the bag filter and the coarse air blower used in the following embodiments are as described above.

[0112] Specifically, the primary function of the rough air blower 5 is to overcome the air resistance of the pipeline and the four-stage dust and tar settling device, while also providing a certain pressure head to the subsequent bag filter. The total resistance of the equipment is approximately 4000 Pa, maintaining positive pressure in the bag filter. The rough air blower 5 must be able to operate stably and reliably in high-temperature, high-dust environments. It must have excellent airtightness, isolating it from the outside air, and the motor must be explosion-proof. To ensure the system's control requirements, the rough air blower 5 is equipped with a variable frequency drive (VFD).

[0113] Furthermore, the impeller is made of heat-resistant, wear-resistant, low-compound, high-strength structural steel Q420C, which has high strength, good fatigue resistance, high toughness, low brittleness, temperature difference adaptability, good cold forming performance, weldability, good corrosion resistance and certain wear resistance. It also has high comprehensive mechanical properties in the normalized or normalized and tempered state.

[0114] Furthermore, the purifying gas fan 9 is mainly used to overcome the backflushing of subsequent furnace gas and the pressure conveying in pipelines. Except for corrosion resistance, the performance requirements of the purifying gas fan 9 are consistent with those of the coarse gas fan.

[0115] The selection of the clean air fan 9 and the rough air fan 5 also took into account the special characteristics of frequency conversion regulation. Electric furnaces cannot maintain a stable frequency during production. Changes in raw materials and various unstable factors during production cause furnace pressure fluctuations. Therefore, the frequency-controlled fans cannot operate at 100% full load for extended periods. The actual operating frequency is generally between 22-28Hz to regulate furnace pressure. Thus, when selecting the fans, the air volume is increased by a certain factor to meet the overall system requirements.

[0116] Furthermore, the gas discharged from the purification fan 9 can enter the rotary kiln and be used as fuel to replace pulverized coal.

[0117] The present invention will now be described in further detail with reference to specific embodiments and comparative examples.

[0118] Example 1

[0119] This embodiment provides a system for purifying and reusing coal gas from a submerged arc furnace, such as... Figure 1-2As shown, it includes a gas settling and purification unit, a bag filter unit, and a fan unit. The gas settling and purification unit is used to perform four-stage settling and purification treatment on the gas discharged from the electric arc furnace. The bag filter unit is used to remove dust from the gas from the gas purification unit. The fan unit includes a clean air fan, which is used to feed the gas from the bag filter unit into the rotary kiln.

[0120] The gas settling and purification unit includes a primary settling device 1, a secondary settling device 2, a tertiary settling device 3, and a quaternary settling device 4 connected in series.

[0121] The air outlet pipes of the first-stage sedimentation tank 1, the second-stage sedimentation tank 2, the third-stage sedimentation tank 3 and the fourth-stage sedimentation tank 4 are all vertically installed at the top of the sedimentation tank, and the air inlet pipes are all installed at the bottom of the sedimentation tank.

[0122] The angle between the air inlet pipes of the secondary settling tank 2, the tertiary settling tank 3 and the quaternary settling tank 4 and the side wall of the corresponding settling tank is 8°.

[0123] The air outlet pipe 11 of the primary settling tank and the air inlet pipe 23 of the secondary settling tank are connected by the first pipe 12;

[0124] The included angle between the air outlet pipe 11 and the first pipe 12 of the first stage sedimentation unit is 55°;

[0125] The air outlet pipe 21 of the secondary settling tank and the air inlet pipe 33 of the tertiary settling tank are connected by the second pipe 22;

[0126] The included angle between the air outlet pipe 21 and the second pipe 22 of the secondary settling device is 55°;

[0127] The air outlet pipe 31 of the third-stage sedimentation unit and the air inlet pipe 42 of the fourth-stage sedimentation unit are connected by the third pipe 32.

[0128] The included angle between the air outlet pipe 31 and the third pipe 32 of the three-stage settling device is 55°.

[0129] like Figure 3 As shown, ash collection hoppers 18 are provided at the angle between the air outlet pipe 11 and the first pipe 12 of the first stage sedimentation unit, the angle between the air outlet pipe 21 and the second pipe 22 of the second stage sedimentation unit, and the angle between the air outlet pipe 31 and the third pipe 32 of the third stage sedimentation unit.

[0130] The settling chambers 10 of the first-stage settling tank 1, the second-stage settling tank 2, the third-stage settling tank 3, and the fourth-stage settling tank 4 are arranged in the shape of an inverted frustum at the bottom of the settling tank body;

[0131] The angle between the diameter of the upper bottom surface of the settling chamber 10 and the generatrix passing through the endpoint of the diameter is 15°;

[0132] The bag filter unit includes a first bag filter 6, a second bag filter 7, and a third bag filter 8 arranged in parallel.

[0133] The dust hoppers 14 of the first bag filter 6, the second bag filter 7, and the third bag filter 8 are arranged in the shape of an inverted frustum at the bottom of the bag filter.

[0134] The diameter of the upper bottom surface of the ash hopper 14 and the angle between it and the generatrix passing through the endpoint of the diameter are 15°.

[0135] The fan unit also includes a coarse air fan 5. The outlet pipe of the coarse air fan 5 is connected to the inlet pipes of the first bag filter 6, the second bag filter 7 and the third bag filter 8 respectively, for conveying the coal gas from the fourth stage settling tank 4 to the first bag filter 6, the second bag filter 7 and the third bag filter 8 respectively.

[0136] The exhaust pipe 41 of the fourth-stage settling tank and the intake pipe 51 of the rough gas blower 5 form a herringbone flue; the included angle between the exhaust pipe 41 of the fourth-stage settling tank and the intake pipe 51 of the rough gas blower 5 is 55°.

[0137] The exhaust pipe of the coarse air blower 5 is connected to the inlet pipe of the first bag filter 6.

[0138] The exhaust pipes of the first bag filter 6, the second bag filter 7, and the third bag filter 8 are respectively connected to the clean air fan 9. The gas discharged by the clean air fan 9 can be used as fuel for the rotary kiln.

[0139] Compensators are installed on the first pipe 12, the second pipe 22 and the third pipe 32;

[0140] The settling chambers 10 of the primary settling tank 1 and the secondary settling tank 2 are both connected to the first ash storage silo 15 through pipelines, so as to transport the dust and tar in the settling chambers 10 of the primary settling tank 1 and the secondary settling tank 2 to the first ash storage silo 15.

[0141] The settling chambers 10 of the three-stage settling tank 3 and the four-stage settling tank 4, as well as the ash hopper 14 of the first bag filter 5, are all connected by pipes to the second ash storage hopper 16 to transport the dust and tar in the settling chambers 10 of the three-stage settling tank 3 and the four-stage settling tank 4, as well as the dust in the ash hopper 14 of the first bag filter 5, to the second ash storage hopper 16.

[0142] The dust hoppers 14 of the second bag filter 7 and the third bag filter 8 are both connected to the third dust storage bin 17 via pipes, so as to transport the dust in the dust hoppers 14 of the second bag filter 7 and the third bag filter 8 to the third dust storage bin 17.

[0143] The first-stage settling tank 1, the second-stage settling tank 2, the third-stage settling tank 3, and the fourth-stage settling tank 4 are all dust and tar settling tanks. Each dust and tar settling tank is equipped with a bin wall vibrator inside the tank body, a self-closing explosion-proof valve at the top of the tank body, and a connecting flange at the bottom of the tank body to transport the dust to the ash storage bin. The dust in each ash storage bin is transported to the purification ash bin by a sealed scraper conveyor for unloading and external transportation.

[0144] Among them, the first-stage settling tank 1 is a hollow cavity; the tanks of the second-stage settling tank 2, the third-stage settling tank 3 and the fourth-stage settling tank 4 are all equipped with multiple layers of baffles.

[0145] The first bag filter 6, the second bag filter 7, and the third bag filter 8 are all spherical explosion-proof bag filters.

[0146] This embodiment also provides a process for purifying and reusing blast furnace gas. The system operation of this embodiment includes the following steps:

[0147] S1: The blast furnace gas enters the first-stage settling tank 1, the second-stage settling tank 2, the third-stage settling tank 3 and the fourth-stage settling tank 4 in sequence for dust and tar settling and purification treatment.

[0148] S2: The gas enters the coarse gas fan 5 from the fourth-stage settling tank 4, and then enters the first bag filter 6, the second bag filter 7 and the third bag filter 8 for dust removal.

[0149] S3: The coal gas processed in the first bag filter 6, the second bag filter 7 and the third bag filter 8 is transported to the rotary kiln as fuel by the clean air blower 9.

[0150] Table 1 shows a comparison of the gas properties before and after the system treatment of the submerged arc furnace gas purification system provided in this embodiment. The dust concentration test is conducted in accordance with ASTM D6331-2024, and the gas concentration is monitored by a laser gas analyzer (manufacturer: Anhui Wanyi Technology, model LG5100).

[0151] Table 1

[0152]

[0153] As shown in Table 1, the system provided by the present invention maintains a constant content of hydrogen, oxygen and CO within a certain small range during operation, indicating that the system provided by the present invention has excellent stability; and the dust concentration in the coal gas after system treatment is significantly reduced to below 8 mg / Nm3, indicating good dust removal effect.

[0154] Comparative Example 1

[0155] The difference between this comparative example and Example 1 is that the air inlet pipes of the secondary settling tank 2, the tertiary settling tank 3, and the quaternary settling tank 4 are all at an angle of 90° to the corresponding settling tank body. The rest of the structure and operation steps are the same as in Example 1.

[0156] Table 2 shows a comparison of the gas performance of the submerged arc furnace gas purification system before and after stable operation. The dust concentration test was conducted in accordance with ASTM D6331-2024, and the gas concentration was monitored by a laser gas analyzer (manufacturer: Anhui Wanyi Technology, model LG5100).

[0157] Table 2

[0158]

[0159] As can be seen from Tables 1 and 2, in Comparative Example 1, the angle between the air inlet pipes of the secondary settling tank 2, the tertiary settling tank 3, and the quaternary settling tank 4 and the corresponding settling tank body was changed to a conventional 90° right angle. As a result, not only did some dust accumulate at the right angle in the gas entering the secondary settling tank 2, the tertiary settling tank 3, and the quaternary settling tank 4, but the gas flow stability was also poor, which affected the dust treatment effect of the gas settling and purification unit.

[0160] Comparative Example 2

[0161] The difference between this comparative example and Example 1 is that the included angle between the air outlet pipe 11 of the first-stage sedimentation device and the first pipe 12 is 90°.

[0162] The included angle between the air outlet pipe 21 and the second pipe 22 of the secondary settling device is 90°;

[0163] The included angle between the air outlet pipe 31 and the third pipe 32 of the three-stage sedimentation unit is 90°;

[0164] The included angle between the air outlet pipe 41 of the fourth-stage settling device and the air inlet pipe 51 of the coarse air blower is 90°, and the rest of the structure and operation steps are the same as in Embodiment 1.

[0165] Table 3 shows a comparison of the gas performance of the submerged arc furnace gas purification system before and after stable operation. The dust concentration test was conducted in accordance with ASTM D6331-2024, and the gas concentration was monitored by a laser gas analyzer (manufacturer: Anhui Wanyi Technology, model LG5100).

[0166] Table 3

[0167]

[0168] As can be seen from Tables 1 and 3, in Comparative Example 2, the angle between the outlet pipes of the secondary settling tank 2, the tertiary settling tank 3, and the quaternary settling tank 4 and the corresponding first, second, or third pipes was changed to a conventional 90° right angle. This resulted in some dust being deposited at the right angle in the gas entering the secondary settling tank from the primary settling tank, entering the tertiary settling tank from the secondary settling tank, and entering the quaternary settling tank from the tertiary settling tank. This affected the dust treatment effect of the gas settling and purification unit.

[0169] Comparative Example 3

[0170] The difference between this comparative example and Example 1 is that the included angle between the air outlet pipe 11 of the first-stage sedimentation device and the first pipe 12 is 45°.

[0171] The included angle between the air outlet pipe 21 and the second pipe 22 of the secondary settling device is 45°;

[0172] The included angle between the air outlet pipe 31 and the third pipe 32 of the three-stage sedimentation unit is 45°;

[0173] The included angle between the air outlet pipe 41 of the fourth-stage settling device and the air inlet pipe 51 of the coarse air blower is 45°, and the rest of the structure and operation steps are the same as in Embodiment 1.

[0174] Table 4 shows a comparison of the gas performance of the submerged arc furnace gas purification system before and after stable operation. The dust concentration test was conducted in accordance with ASTM D6331-2024, and the gas concentration was monitored by a laser gas analyzer (manufacturer: Anhui Wanyi Technology, model LG5100).

[0175] Table 4

[0176]

[0177] As can be seen from Tables 1 and 4, in Comparative Example 3, the angle between the outlet pipes of the secondary settling tank 2, the tertiary settling tank 3, and the quaternary settling tank 4 and the corresponding first, second, or third pipes was changed to 45°. The angle was too small, which would weaken the effect of pre-separation of medium and coarse particles by inertia and affect the dust treatment effect of the gas settling and purification unit.

[0178] Comparative Example 4

[0179] The difference between this comparative example and Example 1 is that the angle between the air inlet pipes of the secondary settling tank 2, the tertiary settling tank 3 and the quaternary settling tank 4 and the corresponding settling tank body is 90°.

[0180] The included angle between the air outlet pipe 11 of the first-stage sedimentation unit and the first pipe 12 is 90°;

[0181] The included angle between the air outlet pipe 21 and the second pipe 22 of the secondary settling device is 90°;

[0182] The included angle between the air outlet pipe 31 and the third pipe 32 of the three-stage sedimentation unit is 90°;

[0183] The remaining structure and operation steps are the same as in Example 1.

[0184] Table 5 shows a comparison of the gas performance of the submerged arc furnace gas purification system before treatment and after stable operation. The dust concentration test was conducted in accordance with ASTM D6331-2024, and the gas concentration was monitored by a laser gas analyzer (manufacturer: Anhui Wanyi Technology, model LG5100).

[0185] Table 5

[0186]

[0187] Comparative Example 4 is an existing conventional submerged arc furnace gas purification system. In the gas settling purification unit, the corresponding pipeline connections between each setter are all 90° right angles. Some dust in the gas is deposited at the right angles, and the gas changes significantly during the operation of the entire system, affecting the stability of the entire system and the dust treatment effect.

[0188] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for cleaning and reusing of the off-gas of a submerged arc furnace, characterized in that, The coal gas precipitation purification unit, the bag dust removal unit and the fan unit are included; The coal gas precipitation purification unit is used for four-stage precipitation purification treatment of the coal gas discharged by the furnace, the bag dust removal unit is used for dust removal treatment of the coal gas from the coal gas precipitation purification unit, and the fan unit includes a clean gas fan used for feeding the coal gas from the bag dust removal unit into the rotary kiln. The coal gas precipitation purification unit includes a first-stage precipitator (1), a second-stage precipitator (2), a third-stage precipitator (3) and a fourth-stage precipitator (4) connected in sequence. The gas outlet pipes of the first-stage precipitator (1), the second-stage precipitator (2), the third-stage precipitator (3) and the fourth-stage precipitator (4) are vertically arranged at the top of the tank body of the precipitator, and the gas inlet pipes are arranged at the lower part of the tank body of the precipitator. The angle between the gas inlet pipe of the second-stage precipitator (2), the third-stage precipitator (3) and the fourth-stage precipitator (4) and the side wall of the tank body of the corresponding precipitator is 8°-12°. The gas outlet pipe (11) of the first-stage precipitator and the gas inlet pipe (23) of the second-stage precipitator are connected through a first pipe (12). The angle between the gas outlet pipe (11) of the first-stage precipitator and the first pipe (12) is 55°-60°. The gas outlet pipe (21) of the second-stage precipitator and the gas inlet pipe (33) of the third-stage precipitator are connected through a second pipe (22). The angle between the gas outlet pipe (21) of the second-stage precipitator and the second pipe (22) is 55°-60°. The gas outlet pipe (31) of the third-stage precipitator and the gas inlet pipe (42) of the fourth-stage precipitator are connected through a third pipe (32). The angle between the gas outlet pipe (31) of the third-stage precipitator and the third pipe (32) is 55°-60°.

2. The ore smelting furnace coal gas cleaning and recycling system according to claim 1, characterized in that, The angles between the gas outlet pipe (11) of the first-stage precipitator and the first pipe (12), the gas outlet pipe (21) of the second-stage precipitator and the second pipe (22) and the gas outlet pipe (31) of the third-stage precipitator and the third pipe (32) are each provided with a dust collecting hopper (18) for collecting large dust particles due to inertial separation to avoid pipe blockage.

3. The ore smelting furnace coal gas cleaning and recycling system according to claim 1, characterized in that, The settling bin (10) of the first-stage precipitator (1), the second-stage precipitator (2), the third-stage precipitator (3) and the fourth-stage precipitator (4) is arranged in the form of an inverted circular truncated cone at the bottom of the tank body of the precipitator. The angle between the upper bottom surface diameter of the settling bin (10) and the generatrix passing through the end points of the diameter is 15°-20°.

4. The ore smelting furnace coal gas cleaning and recycling system according to claim 1, characterized in that, The bag dust removal unit includes a plurality of bag dust collectors arranged in parallel, preferably, the plurality of bag dust collectors include a first bag dust collector (6), a second bag dust collector (7) and a third bag dust collector (8). The dust hopper (14) of the first bag dust collector (6), the second bag dust collector (7) and the third bag dust collector (8) is arranged in the form of an inverted circular truncated cone at the bottom of the bag dust collector. The angle between the upper bottom surface diameter of the dust hopper (14) and the generatrix passing through the end points of the diameter is 15°-20°.

5. The ore smelting furnace coal gas cleaning and recycling system according to claim 4, characterized in that, The fan unit further comprises a coarse gas fan (5), the air outlet pipeline of the coarse gas fan (5) is connected with the air inlet pipeline of the first bag-type dust collector (6), the second bag-type dust collector (7) and the third bag-type dust collector (8) respectively, for conveying the coal gas from the four-stage settler (4) into the first bag-type dust collector (6), the second bag-type dust collector (7) and the third bag-type dust collector (8) respectively; The air outlet pipeline (41) of the four-stage settler and the air inlet pipeline (51) of the coarse gas fan form a herringbone gas flue, and the included angle between the air outlet pipeline (41) of the four-stage settler and the air inlet pipeline (51) of the coarse gas fan is 55-60°. The air outlet pipeline of the first bag-type dust collector (6), the second bag-type dust collector (7) and the third bag-type dust collector (8) is connected with a clean gas fan (9) respectively.

6. The ore smelting furnace coal gas cleaning and recycling system according to claim 5, characterized in that, The first bag-type dust collector (6), the second bag-type dust collector (7) and the third bag-type dust collector (8) are all spherical explosion-proof bag-type dust collectors.

7. The ore smelting furnace coal gas cleaning and recycling system according to claim 4, characterized in that, The settling bin (10) of the first-stage settler (1) and the second-stage settler (2) is connected with a first dust storage bin (15) through a pipeline, for conveying the dust and tar in the settling bin (10) of the first-stage settler (1) and the second-stage settler (2) into the first dust storage bin (15); The settling bin (10) of the third-stage settler (3) and the fourth-stage settler (4) and the dust hopper (14) of the first bag-type dust collector (5) are connected with a second dust storage bin (16) through a pipeline, for conveying the dust and tar in the settling bin (10) of the third-stage settler (3) and the fourth-stage settler (4) and the dust hopper (14) of the first bag-type dust collector (5) into the second dust storage bin (16); The dust hopper (14) of the second bag-type dust collector (7) and the third bag-type dust collector (8) is connected with a third dust storage bin (17) through a pipeline, for conveying the dust in the dust hopper (14) of the second bag-type dust collector (7) and the third bag-type dust collector (8) into the third dust storage bin (17).

8. The ore smelting furnace coal gas cleaning and recycling system of claim 1, wherein, A compensator is arranged on the first pipeline (12), the second pipeline (22) and the third pipeline (32).

9. The ore smelting furnace coal gas cleaning and recycling system according to claim 1, characterized in that, The first-stage settler (1), the second-stage settler (2), the third-stage settler (3) and the fourth-stage settler (4) are all dust tar settlers, a bin wall vibrator is arranged in the tank body of each dust tar settler, a self-closing explosion-proof valve is arranged on the top of the tank body, and a connecting flange is arranged on the bottom of the tank body, for conveying the dust into the dust storage bin. The first-stage settler (1) is a hollow body, and a plurality of layers of guide plates are arranged in the tank body of the second-stage settler (2), the third-stage settler (3) and the fourth-stage settler (4).

10. A process for cleaning and reusing of the off-gas of a submerged arc furnace, characterized in that, The system is operated according to any one of claims 1-9, comprising the following steps: S1: the coal gas of the electric arc furnace enters the first-stage settler (1), the second-stage settler (2), the third-stage settler (3) and the fourth-stage settler (4) in sequence for dust and tar settling and purification treatment; S2: The coal gas from the fourth stage settler (4) enters the coarse gas fan (5) and then enters the bag dust removal unit for dust removal treatment; S3: The coal gas treated by the bag dust removal unit is delivered to the rotary kiln by the clean gas fan (9) as fuel.

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