Large Electric Furnace Flue Gas Trapping Method

Abstract

The present invention discloses a method for capturing the flue gas of a large electric furnace, which is realized through a flue gas capture hood, and includes: S1, during the smelting of the electric furnace, the diversion hood moves to the first position, the left and right fans are turned on, and part of the gas in the hood is extracted and ejected through an angle-adjustable nozzle to form an air curtain outside the smoke exhaust port; S2, when the traveling crane moves, the sensor transmits the position signal of the traveling crane to the PLC. When the PLC determines that the traveling crane will affect the capture effect of the air curtain, a control signal is sent to the control input end of the angle-adjustable nozzle, so that the angle-adjustable nozzle rotates a certain angle towards the inside of the smoke exhaust port to form a figure-eight air curtain, strengthening the capture effect of the roof hood; when the PLC determines that the traveling crane has no influence on the flue gas capture of the roof hood, a control signal is sent to the control input end of the angle-adjustable nozzle, so that the angle-adjustable nozzle rotates towards the outside of the smoke exhaust port and returns to the initial position. The present invention has a good green and low-carbon effect, and the social, environmental and economic benefits are obvious.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas capture, and in particular to a method for capturing flue gas from a large electric furnace. Background Art

[0002] Electric furnace smelting is one of the important processes in the foundry industry. During this process, a large amount of high-temperature flue gas is generated. In order to avoid polluting the indoor and outdoor environments, a large electric furnace flue gas capture hood is required to capture the high-temperature flue gas. The ventilation volume of the large electric furnace flue gas capture hood is generally 600,000 - 1,500,000 m³ / h, and the system operation energy consumption is 800 - 2,000 kW, with huge operation energy consumption. To enhance the capture effect, the existing large electric furnace flue gas capture hoods usually adopt the form of combined operation of a roof hood and a deflector hood. To facilitate the movement of the overhead crane, a certain passage for the overhead crane to move (with a height of 3 - 5 meters) needs to be reserved between the roof hood and the deflector hood. However, the lateral wind formed by the crosswind and the indoor exhaust air flow in the workshop easily causes the flue gas to escape from the passage for the overhead crane to move, polluting the indoor and outdoor environments. To reduce the flue gas escape caused by the lateral wind, the ventilation volume of the roof hood is usually increased (by about 20% - 40%), resulting in a 30% - 50% increase in the initial investment of the system and a 25% - 40% increase in the operation energy consumption. In addition, for the renovation projects carried out in the above manner, due to the limitations of the original roof load on the roof hood and the ventilation duct, and the limited layout position caused by the increase in the volume of the dust collector, the renovation difficulty is relatively large. The above restricts the application of the large electric furnace flue gas capture hood and is not conducive to the environmental protection renovation and green development of foundry enterprises.

[0003] To solve the above problems, the present invention provides a method for capturing flue gas from a large electric furnace, and specifically, the following technical solutions can be adopted:

[0004] The method for capturing flue gas from a large electric furnace according to the present invention is realized through a flue gas capture hood.

[0005] The flue gas capture hood includes

[0006] a roof hood, which has an air inlet and an air outlet. The air inlet is located above the electric furnace, and the air outlet is connected to a dust removal mechanism;

[0007] a deflector hood, which includes a left moving hood and a right moving hood. The left moving hood and the right moving hood are located below the roof hood and are respectively arranged on both sides of the electric furnace. The left moving hood and the right moving hood have a smoke exhaust opening formed at the top when moving towards each other to reach the first position, or a hoisting working space formed at the top when moving away from each other to reach the second position.

[0008] The wind prevention mechanism includes a left blower disposed outside the left moving hood and a right blower disposed outside the right moving hood. The left blower has a left air return opening communicating with the inner cavity of the left moving hood and left air supply openings arranged in rows along the smoke exhaust opening on its outer side. The right blower has a right air return opening communicating with the inner cavity of the right moving hood and right air supply openings arranged in rows along the smoke exhaust opening on its outer side. Angle-adjustable nozzles are provided at both the left air supply openings and the right air supply openings.

[0009] The control mechanism includes a sensor for detecting the position of the traveling crane. The signal output end of the sensor is electrically connected to the signal input end of the PLC, and the control output end of the PLC is electrically connected to the control input end of the angle-adjustable nozzle.

[0010] The flue gas capture method includes:

[0011] S1. During the electric furnace melting, the deflector hood moves to the first position, and the left and right blowers are turned on. Part of the gas inside the deflector hood is extracted and ejected through the angle-adjustable nozzles to form an air curtain outside the smoke exhaust opening, resisting the escape of flue gas caused by the action of lateral wind and improving the capture effect of the roof hood.

[0012] S2. When the traveling crane moves, the sensor transmits the position signal of the traveling crane to the PLC. When the PLC determines that the traveling crane will affect the air curtain's resistance to lateral wind interference, a control signal is sent to the control input end of the angle-adjustable nozzle, causing the angle-adjustable nozzle to rotate a certain angle inward towards the smoke exhaust opening to form an inverted V-shaped air curtain, strengthening the capture effect of the roof hood. When the PLC determines that the traveling crane has no effect on the air curtain's resistance to lateral wind interference, a control signal is sent to the control input end of the angle-adjustable nozzle, causing the angle-adjustable nozzle to rotate outward towards the smoke exhaust opening to return to the initial position.

[0013] The left moving hood and the right moving hood are slidably connected to the linear guide rail, and at least one linear guide rail is provided from top to bottom. This enables the left and right moving hoods to move smoothly along the established track.

[0014] Both the left moving hood and the right moving hood are of a stepped structure that is smaller at the top and larger at the bottom. The left air return opening and the right air return opening are both provided at the shoulders of the stepped structure, and both the left air return opening and the right air return opening are of a single-row and multi-piece structure. The left and right moving hoods are arranged in accordance with the on-site layout structure, having excellent gathering and smoke exhaust effects.

[0015] Both the left air supply opening and the right air supply opening are provided at the top of the stepped structure, and when the traveling crane passes by, the angle-adjustable nozzles both deflect inward from the vertical direction so that the exhaust air forms an inverted V-shaped air curtain outside the smoke exhaust opening. When forming the inverted V-shaped air curtain, it can more effectively prevent the escape of flue gas in the traveling crane passage.

[0016] The deflection angle of the angle-adjustable nozzle is 5 - 25°.

[0017] The large electric furnace flue gas capture method provided by the present invention sucks air from inside the diversion hood through a wind prevention mechanism and sends it to the outside of the smoke exhaust port to form an air curtain connecting the diversion hood and the roof hood, which can effectively avoid the adverse effects of lateral wind inside the workshop on the smoke capture effect of the roof hood; at the same time, through the automatic adjustment mechanism of the nozzle angle of the air supply port, the opening and closing angle of the air curtain can be automatically adjusted according to the traveling state and position of the traveling crane, avoiding the smoke escape caused by the obstruction of the traveling crane beam to the air curtain. Tests show that by controlling the air supply speed of the air curtain, the present invention can resist the influence of lateral wind above 3 m / s, and at the same time, it can also reduce the ventilation volume originally used to resist lateral wind, providing a feasible solution for system transformation. It is estimated that the present invention can reduce the ventilation volume by 20% - 30%, the energy saving can be reduced by 20% - 30%, the operating cost can be reduced by 30%, and the annual operating cost savings are about 2 million yuan per unit. Compared with the traditional transformation plan with an investment of 8 million yuan per unit, the plan described in the present invention only requires 3.2 million yuan per unit, saving more than 60% of the transformation cost. At the same time, it can improve the environmental protection effect of the foundry workshop and improve the occupational health in the workshop, with good green and low-carbon effects, and obvious social, environmental and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of the flue gas capture hood in the present invention.

[0019] Figure 2 is Figure 1 the A - A view of

[0020] Figure 3 is Figure 1 the top view of DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The following will describe in detail the embodiments of the present invention with reference to the accompanying drawings. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific construction processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0022] As Figures 1-3 shown, the large electric furnace flue gas capture method described in the present invention is realized through a flue gas capture hood, which is composed of a roof hood 1, a diversion hood, a wind prevention mechanism and a control mechanism.

[0023] Among them, the roof hood 1 has an air inlet 11 and an air outlet 12. The air inlet 11 is located above the electric furnace M, and the air outlet 12 is connected to the dust removal mechanism; the flow guide hood includes a left moving hood 21 and a right moving hood 22, both of which are located below the roof hood 1 and are respectively arranged on both sides of the electric furnace M. Among them, the left moving hood 21 and the right moving hood 22 have a smoke exhaust port 23 formed at the top when moving towards each other to reach the first position, or a hoisting working space formed at the top when moving away from each other to reach the second position. Both the first position and the second position are points determined according to the actual situation on site. In order to achieve the guiding effect and avoid deviating from the established moving direction, both the left moving hood 21 and the right moving hood 22 are slidably connected to the linear guide rail 24. The left moving hood 21 and the right moving hood 22 are usually of a stepped structure with a smaller upper part and a larger lower part. There is one linear guide rail 24 arranged on the bottom surface, and one is installed slightly below the stepped surface of the left moving hood 21 and the right moving hood 22, so as to make the guiding effect more effective.

[0024] The above-mentioned wind prevention mechanism includes a left fan 31 located outside the left moving hood 21 and a right fan 32 located outside the right moving hood 22. Both the left fan 31 and the right fan 32 are axial fans. Among them, the end of the inlet pipe 33 of the left fan 31 is connected to the inner cavity of the left moving hood 21 to form a left air return port 34. The left air return port 34 is usually located at the shoulder of the stepped structure of the hood body and is arranged in a single row with multiple ones; the end of the outlet pipe 35 of the left fan 31 is located at the stepped top of the left moving hood 21 and is connected to a plurality of angle-adjustable nozzles 36 arranged in a single row along a straight line, that is, a plurality of left air supply ports arranged in a single row along the outside of the smoke exhaust port 23 are formed. Similarly, the end of the inlet pipe of the right fan 32 is connected to the inner cavity of the right moving hood 22 to form a right air return port. The right air return port is usually located at the shoulder of the stepped structure of the hood body and is arranged in a single row with multiple ones; the end of the outlet pipe of the right fan 32 is located at the stepped top of the right moving hood 22 and is connected to a plurality of angle-adjustable nozzles arranged in a single row along a straight line, that is, a plurality of left air supply ports arranged in a single row along the outside of the smoke exhaust port 23 are formed. Under the action of the left fan 31 and the right fan 32, the high-temperature flue gas in the flow guide hood enters the exhaust pipe respectively from the left and right air return ports and is ejected by the angle-adjustable nozzles 36 to form an anti-interference air curtain located outside the smoke exhaust port 23, preventing the interference of the lateral wind in the workshop on the smoke collection of the roof hood. Usually, the outlet of the angle-adjustable nozzle 36 is vertically upward. When the overhead crane passes, the angle-adjustable nozzles 36 on both sides deflect inward by a certain angle, making the anti-interference air curtain in a shape of an inverted V to enhance the anti-interference ability.

[0025] In order to enable the angle-adjustable nozzle 36 to automatically adjust the gas ejection direction, a sensor for detecting the position of the traveling crane is installed near the traveling crane track. The signal output end of the sensor is electrically connected to the signal input end of the PLC, and the control output end of the PLC is electrically connected to the control input end of the angle-adjustable nozzle 36. Usually, the deflection angle of the angle-adjustable nozzle 36 is 5-25°.

[0026] The large electric furnace flue gas capture method described in the present invention includes:

[0027] S1. During the smelting of the electric furnace, the deflector moves to the first position, the left and right blowers are turned on, and part of the gas in the deflector is extracted and ejected through the angle-adjustable nozzle 36 to form an air curtain outside the smoke exhaust port 23, resisting the smoke escape caused by the action of the lateral wind and improving the capture effect of the roof hood 1.

[0028] S2. When the traveling crane moves, the sensor transmits the position signal of the traveling crane to the PLC. When the PLC determines that the traveling crane will affect the air curtain's resistance to lateral wind interference, a control signal is sent to the control input end of the angle-adjustable nozzle 36, causing the angle-adjustable nozzle 36 to rotate a certain angle towards the inside of the smoke exhaust port 23 to form a figure-eight air curtain and strengthening the capture effect of the roof hood 1. When the PLC determines that the traveling crane has no influence on the smoke capture of the roof hood 1, a control signal is sent to the control input end of the angle-adjustable nozzle 36, causing the angle-adjustable nozzle 36 to rotate towards the outside of the smoke exhaust port 23 and return to the initial position.

[0029] The high-temperature flue gas generated during the operations such as smelting, charging, and electrode replacement of the above-mentioned electric furnace M can all rise along the deflector and be captured by the roof hood 1 together with the air curtain smoke in the traveling crane passage, and then be sent to the dust collector by the total ventilation system for dust removal and discharged up to the standard.

[0030] It should be noted that in the description of the present invention, terms indicating orientation or positional relationship such as "front", "rear", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

Claims

1. A method for capturing the flue gas of a large electric furnace, which is realized through a flue gas capture hood, Characterized in that: The flue gas capture hood includes: A roof hood, which has an air inlet and an air outlet. The air inlet is located above the electric furnace, and the air outlet is connected to a dust removal mechanism; A deflector hood, which includes a left moving hood and a right moving hood. The left moving hood and the right moving hood are located below the roof hood and are respectively arranged on both sides of the electric furnace. The left moving hood and the right moving hood have a smoke exhaust port formed at the top when moving towards each other to reach the first position, or a hoisting working space formed at the top when moving away from each other to reach the second position; A wind prevention mechanism, which includes a left fan arranged outside the left moving hood and a right fan arranged outside the right moving hood. The left fan has a left air return port connected to the inner cavity of the left moving hood and a left air supply port arranged in a row along the smoke exhaust port on its outside. The right fan has a right air return port connected to the inner cavity of the right moving hood and a right air supply port arranged in a row along the smoke exhaust port on its outside. Angle adjustment nozzles are arranged at both the left air supply port and the right air supply port; A control mechanism, which includes a sensor for detecting the position of the overhead crane. The signal output end of the sensor is electrically connected to the signal input end of the PLC, and the control output end of the PLC is electrically connected to the control input end of the angle adjustment nozzle; The method for capturing the flue gas includes: S1. When the electric furnace is smelting, the deflector hood moves to the first position, the left and right fans are turned on, part of the gas in the deflector hood is extracted and ejected through the angle adjustment nozzle to form an air curtain outside the smoke exhaust port, resisting the escape of flue gas caused by the action of lateral wind and improving the capture effect of the roof hood; S2. When the overhead crane moves, the sensor transmits the position signal of the overhead crane to the PLC. When the PLC judges that the overhead crane will affect the air curtain's resistance to lateral wind interference, a control signal is sent to the control input end of the angle adjustment nozzle, so that the angle adjustment nozzle rotates a certain angle towards the inside of the smoke exhaust port to form a figure-eight air curtain, strengthening the capture effect of the roof hood; when the PLC judges that the overhead crane has no influence on the flue gas capture of the roof hood, a control signal is sent to the control input end of the angle adjustment nozzle, so that the angle adjustment nozzle rotates towards the outside of the smoke exhaust port to return to the initial position.

2. The method for capturing the flue gas of a large electric furnace according to claim 1, Characterized in that: The left moving hood and the right moving hood are slidably connected to a linear guide rail, and at least one linear guide rail is arranged from top to bottom.

3. The method for capturing the flue gas of a large electric furnace according to claim 2, Characterized in that: Both the left moving hood and the right moving hood are of a stepped structure that is smaller at the top and larger at the bottom. The left air return port and the right air return port are both arranged at the shoulders of the stepped structure, and both the left air return port and the right air return port are of a single-row and multi-piece structure.

4. The method for capturing the flue gas of a large electric furnace according to claim 3, Characterized in that: Both the left air supply port and the right air supply port are arranged at the top of the stepped structure, and when the overhead crane passes by, the angle adjustment nozzles are both deflected inward from the vertical direction so that the exhaust air forms a figure-eight air curtain outside the smoke exhaust port.

5. The method for capturing the flue gas of a large electric furnace according to claim 4, Characterized in that: The deflection angle of the angle adjustment nozzle is 5-25°.

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