Treatment method for air leakage at joint of furnace bottom and furnace wall of roasting furnace

Abstract

The invention discloses a treatment method for air leakage at the joint of a furnace bottom and a furnace wall of a roasting furnace, and belongs to the technical field of wet smelting. Comprising the following steps of air leakage judgment; and air leakage treatment is conducted, specifically, a repairing and plugging agent is selected, holes are drilled in a furnace body shell in a staggered mode, the hole diameter of the drilled holes is 10 mm, the distance between the drilled holes is 300-600 mm, the repairing and plugging agent is injected at the high pressure not higher than 0.1 MPa, it is guaranteed that each glue injection part is fully filled, after the glue solution reaches a certain pressure, air channeling gaps among a steel plate, heat preservation bricks and refractory bricks are fully filled, and an overall sealing layer is formed after the glue solution is solidified; repairing a leakage part; and repairing the internal annular groove. Through combination of roasting furnace parameter abnormal fluctuation and physical furnace detection, the air leakage point positioning problem at the joint of the hearth and the boiling layer furnace wall is solved, and the positioning accuracy is improved to 90% or above. The long-acting repairing effect can be achieved. The method is remarkable in economic benefit.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical industrial equipment, and in particular to a method for controlling air leakage at the connection between a furnace bottom and a furnace wall of a roasting furnace. Background Art

[0002] The fluidized bed boiling roasting furnace is composed of a bellows, boiling section, expansion section, straight section and furnace top from bottom to top. Figure 1 As shown, the bellows is provided with an air inlet pipe, above which is an air distribution plate (hearth). On the air distribution plate is a refractory concrete hearth, on which are buried many hoods with small holes. The distance between the hoods is 100mm and they are arranged in a rectangular plane array. The hoods are filled with refractory materials with a thickness of 200mm to maintain the heat insulation of the distribution plate. The outlet diameter of a single hood is 6mm. The air enters the lower bellows of the roasting furnace through the air inlet pipe, and enters the roasting furnace vertically upward through the hoods welded on the hearth distribution plate, so that the roasted sand in the furnace forms a boiling layer. The boiling layer is equipped with cooling coils, and the furnace body is also provided with interfaces such as a feeding port, a roasted sand overflow port, a furnace gas outlet, a secondary air inlet, and an ignition hole. The furnace wall structure consists of three layers. From the inside to the outside, the first layer is wear-resistant bricks, the second layer is insulation bricks, and the attached Figure 2 The third layer is a steel shell. In order to prevent condensed acid corrosion, an insulation layer is wrapped around the outside of the steel shell.

[0003] Over long-term production operations, air leakage has become an unavoidable problem for the industry due to constant wind scouring, erosion from sulfur-laden flue gases, and thermal expansion and contraction during furnace startup and shutdown. This problem becomes increasingly severe with increasing years of operation, leading to a significant decline in furnace life and low production efficiency, hindering the industry's development. Air leakage in the furnace roof and furnace body is generally easier to locate and control due to the visible presence of flue gas. However, the junction between the hearth and the fluidized bed wall, located in the boiling layer of the roasting furnace, is the most reactive and presents a high risk of air leakage with a high frequency. Air leakage in this location can lead to pressure imbalances within the furnace, localized sintering, increased energy consumption, and even shutdown accidents. Furthermore, locating the leak point is difficult, and traditional air leakage control methods (such as steel plate patching and localized pouring) are difficult to address due to air leakage gaps. Consequently, the operating cycle after repair is short and the maintenance costs are high. Summary of the Invention

[0004] The present invention aims to provide a method for treating air leakage at the junction of the furnace floor and furnace wall of a roasting furnace. This method uses parameter analysis combined with furnace probing technology to accurately locate the leak point, and employs a combination of leak-stopping materials and traditional processes to achieve long-term treatment. This method solves the problems raised in the background art.

[0005] The technical solution adopted in the present invention is as follows: A method for controlling air leakage at the connection between the furnace bottom and the furnace wall of a roasting furnace, characterized by comprising the following steps: S1. Air leakage determination Real-time collection of roaster operating parameters for analysis, combined with physical furnace exploration to determine the location of air leaks; The air leakage determination specifically includes the following steps: S1.1. Parameter Monitoring and Analysis: Real-time collection of roasting furnace operating parameters: bellows pressure, blast volume, boiling layer temperature distribution, and furnace gas outlet temperature. When the bellows pressure drops in a short period of time, the temperature differences between the boiling layer temperatures and between different areas of the furnace bottom suddenly increase, with a single point temperature drop of ≥30°C and a regional temperature difference of ≥20°C. At this time, first observe the blast volume to eliminate the blower as a cause, and then observe the boiling layer temperature and furnace bottom temperature changes. If the temperature difference between the various temperature measurement points increases and the temperature of some temperature measurement points drops abnormally compared to the previous temperature, it can be preliminarily determined that sintering has occurred around the abnormally dropped temperature point. S1.2 Furnace Probing Verification: Insert a steel chisel or steel pipe through the charging port to the area around the measuring point of abnormal temperature change. If the chisel does not touch the wind cap but is inserted on a hard block, this position can be determined as the sintering position; S1.3. Confirmation of air leakage: After the position is determined, the air volume can be repeatedly opened to the maximum or closed to the minimum, supplemented by the method of blowing compressed air at the sintering position and breaking the material by poking with a steel chisel. After repeated attempts, if all parameters return to near normal values and the material feeding and discharging are normal, the furnace can resume normal operation; if this position repeatedly sinters, it can be determined that an air leakage has occurred at this position, and it is necessary to use air blowing to cool down, extinguish the flame, and shut down the furnace.

[0006] S2. Air leakage control S2.1. External high-pressure glue injection: Use a repair and plugging agent with strong bonding properties, high temperature resistance, acid corrosion resistance, and oxidation resistance. Drill holes in the furnace shell at offset positions with a diameter of 10mm and a spacing of 300-600mm. Use a high pressure of no more than 0.1MPa to inject the repair and plugging agent to ensure that each injection site is fully filled. After the glue reaches a certain pressure, it fully fills the airflow gaps between the steel plates, insulation bricks, and refractory bricks. After the glue solidifies, it forms an overall sealing layer to repair the leaking parts. S2.2. Repair of internal annular groove: A 300mm wide and 200mm deep annular groove is chiseled downward from the outer edge of the furnace bottom between the bottom plate around the roasting furnace bed and the connection between the boiling layer furnace wall, and the gap between the bottom casting material and the side wall tiles is cleaned out. The gap is filled with a repair sealant. A 500mm high guard plate is fixed on the furnace wall with a homemade Y-shaped frame made of steel bars at every 0.5m, and the evenly mixed steel fiber castable is poured into the guard plate and the annular groove. Then, it is compacted with a vibrating rod and an electric rammer to ensure that the internal gap is densely filled.

[0007] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. The present invention can accurately locate: by combining abnormal fluctuations in roasting furnace parameters with physical furnace detection, the problem of locating air leakage points at the connection between the hearth and the boiling layer furnace wall is solved, and the positioning accuracy is increased to more than 90%.

[0008] 2. The present invention can provide long-term repair: high-performance repair plugging agent is combined with traditional casting technology to simultaneously seal the inside and outside, and the leakage recurrence period after repair is extended to more than 3 years.

[0009] 3. The economic benefits of the present invention are significant: this method can completely solve the problem of interlayer air leakage without dismantling and rebuilding the brick body. It has a short construction period and low investment cost. After the repair is completed, the operating stability of the roasting furnace is significantly improved, the frequency of starting and stopping the furnace is reduced, maintenance costs are saved, and the zinc concentrate processing capacity is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is the structural diagram of the fluidized bed roaster; Figure 2 This is the structural diagram of the connection between the furnace bottom and the boiling section furnace wall; As shown in the figure: 1-furnace top, 2-straight section, 3-expanded section, 4-boiling section, 5-bellows; 11-clay insulation bricks, 12-wear-resistant high-alumina bricks, 13-refractory fiber felt, 14-refractory castable. DETAILED DESCRIPTION

[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0012] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention. Example

[0013] like Figure 1 This embodiment provides a method for controlling air leakage at the connection between the furnace bottom and the furnace wall of a roasting furnace, comprising the following specific steps: 1. Methods for determining air leakage locations 1.1. Parameter monitoring and analysis: Real-time collection of roasting furnace operating parameters (bellows pressure, blast volume, boiling layer temperature distribution, furnace gas outlet temperature). When air leakage occurs at the connection between the roasting furnace body and the hearth, part of the compressed air in the bellows will not pass through the wind cap but directly enter the roasting furnace from the air gap. Sintering will inevitably occur at the furnace bottom due to insufficient or uneven blast volume. The bellows pressure will drop significantly in a short period of time. The temperature difference between the boiling layer temperatures and the different areas of the furnace bottom (4 to 5 temperature measuring points are installed in the boiling layer and around the furnace bottom of the roasting furnace) will suddenly increase. The temperature drop of a single point is ≥30°C and the regional temperature difference is ≥20°C. At this time, first observe the blast volume to eliminate the cause of the blower, and then observe the changes in the boiling layer temperature and the furnace bottom temperature. The temperature difference between the temperature measuring points becomes larger and the temperature of some temperature measuring points has dropped abnormally and significantly compared to before. It can be preliminarily determined that sintering has occurred around the abnormally dropped temperature points. 1.2. Furnace Probing Verification: Insert a steel chisel or steel pipe through the charging port to the area around the measuring point where the temperature changes abnormally. If the chisel cannot touch the wind cap, as if it is inserted into a hard block (sintered material), this position can be determined as the sintering position.

[0014] 1.3. Leakage Confirmation: After the location is determined, the air volume can be repeatedly increased or decreased to the maximum, supplemented by methods such as blowing compressed air at the sintering location and poking the material with a steel chisel to break it up. After repeated attempts, if all parameters return to near-normal values and the material feeding and discharging are normal, the furnace can be resumed for normal operation. If repeated sintering occurs at this location, it can be determined that an air leak has occurred at this location and the temperature must be lowered by air blast, the flame must be extinguished, and the furnace must be shut down.

[0015] 2. Air leakage control method 2.1 External High-Pressure Glue Injection: Select a leak repair agent with strong bonding properties, high temperature resistance (≥1200°C), acid corrosion resistance, and oxidation resistance. Drill holes (10mm diameter, 300-600mm spacing) in the furnace shell at offset locations. Inject the leak repair agent under high pressure (no higher than 0.1MPa). Ensure that each injection area is fully filled. Once the glue reaches a certain pressure, it will fully fill the airflow gaps between the steel plates, insulation bricks, and refractory bricks. After the glue solidifies, it forms a complete sealing layer, repairing the leak.

[0016] 2.2 Internal Annular Groove Repair: A 300mm wide and 200mm deep annular groove was chiseled downward from the outer edge of the furnace bottom between the bottom plate around the hearth and the fluidized bed furnace wall. The gap between the bottom casting material and the side wall tiles was cleaned out and filled with a repair sealant. 500mm high guard plates were fixed to the furnace wall every 0.5m using a homemade Y-shaped frame made of steel bars. Evenly mixed steel fiber castable was poured into the guard plates and annular groove, and then compacted with a vibrating rod and electric rammer to ensure that the internal gaps were densely filled.

[0017] 3. Supporting measures to extend the furnace period Refined operation: Maintain stable feed and blast volumes as much as possible, with an air-to-charge ratio of 1500-1700 Nm³ / t and a roasting temperature of 920-940°C. Strictly follow the heating curve when starting the furnace, maintaining negative pressure inside the furnace to ensure uniform expansion of the refractory materials. When shutting down the furnace to cool, natural cooling should be used as much as possible to avoid emergency cooling caused by long-term high blast, thereby ensuring the service life of the hearth and furnace walls.

[0018] Strictly control the composition and particle size of the materials entering the furnace: avoid the negative impact of a single impurity exceeding the standard, the particle size control -200 mesh> 60%, avoid large particles, especially prevent lumps, stones, and metal debris from entering the furnace.

[0019] Cooling coils: Cooling coils are crucial to the stable operation of fluidized bed furnaces, and bursts can severely damage roasters. When cooling coils, the weld quality should be carefully inspected, any defects promptly addressed, and all welds reinforced. The pH value of the circulating water should be maintained between 9 and 12 (25°C) to prevent scaling within the coils. The wind cap at the bottom of the coil, which blows directly toward the bottom of the coil, should be modified to an oblique blower or directly blocked to prevent localized damage to the coil caused by direct wind.

[0020] The present invention can achieve precise positioning: by combining abnormal fluctuations in roasting furnace parameters with physical furnace detection, the problem of locating air leakage points at the connection between the hearth and the boiling layer furnace wall is solved, and the positioning accuracy is increased to more than 90%.

[0021] The present invention can achieve long-term repair: high-performance repair and plugging agents are combined with traditional casting technology to simultaneously seal the inside and outside, and the leakage recurrence period after repair is extended to more than 3 years.

[0022] The present invention can achieve significant economic benefits: the method can completely solve the problem of interlayer air leakage without dismantling and rebuilding the brick body, with a short construction period and low investment cost. After the repair is completed, the operating stability of the roasting furnace is significantly improved, the frequency of starting and stopping the furnace is reduced, maintenance and repair costs are saved, and the zinc concentrate processing capacity is increased.

Claims

1. A method for treating air leakage at the connection between the furnace bottom and the furnace wall of a roasting furnace, characterized in that: The following steps are involved: S1. Air leakage determination Real-time collection of roaster operating parameters for analysis, combined with physical furnace exploration to determine the location of air leaks; S2. Air leakage control S2.

1. External high-pressure glue injection: Use a repair plugging agent and drill holes in the furnace shell at different locations. The diameter of the holes is 10mm and the spacing is 300-600mm. Use a high pressure of no more than 0.1MPa to inject the repair plugging agent to ensure that each injection site is fully filled. After the glue reaches a certain pressure, it will fully fill the air leakage gaps between the steel plates, insulation bricks, and refractory bricks. After the glue solidifies, it forms an overall sealing layer to repair the leaking parts. S2.

2. Repair of internal annular groove: A 300mm wide and 200mm deep annular groove is chiseled downward from the outer edge of the furnace bottom between the bottom plate around the roasting furnace bed and the connection between the boiling layer furnace wall, and the gap between the bottom casting material and the side wall tiles is cleaned out. The gap is filled with a repair sealant. A 500mm high guard plate is fixed on the furnace wall with a homemade Y-shaped frame made of steel bars at every 0.5m, and the evenly mixed steel fiber castable is poured into the guard plate and the annular groove. Then, it is compacted with a vibrating rod and an electric rammer to ensure that the internal gap is densely filled.

2. The method for treating air leakage at the connection between the furnace bottom and the furnace wall of a roasting furnace according to claim 1, characterized in that: In step S1, the air leakage determination specifically includes the following steps: S1.

1. Parameter Monitoring and Analysis: Real-time collection of roasting furnace operating parameters: bellows pressure, blast volume, boiling layer temperature distribution, and furnace gas outlet temperature. When the bellows pressure drops in a short period of time, the temperature differences between the boiling layer temperatures and between different areas of the furnace bottom suddenly increase, with a single point temperature drop of ≥30°C and a regional temperature difference of ≥20°C. At this time, first observe the blast volume to eliminate the blower as a cause, and then observe the boiling layer temperature and furnace bottom temperature changes. If the temperature difference between the various temperature measurement points increases and the temperature of some temperature measurement points drops abnormally compared to the previous temperature, it can be preliminarily determined that sintering has occurred around the abnormally dropped temperature point. S1.2 Furnace Probing Verification: Insert a steel chisel or steel pipe through the charging port to the area around the measuring point of abnormal temperature change. If the chisel does not touch the wind cap but is inserted on a hard block, this position can be determined as the sintering position; S1.

3. Confirmation of air leakage: After the position is determined, the air volume can be repeatedly opened to the maximum or closed to the minimum, supplemented by the method of blowing compressed air at the sintering position and breaking the material by poking with a steel chisel. After repeated attempts, if all parameters return to near normal values and the material feeding and discharging are normal, the furnace can resume normal operation; if this position repeatedly sinters, it can be determined that an air leakage has occurred at this position, and it is necessary to use air blowing to cool down, extinguish the flame, and shut down the furnace.

3. The method for treating air leakage at the connection between the furnace bottom and the furnace wall of a roasting furnace according to claim 1, characterized in that: In step 2, the repair and plugging agent selected is a repair and plugging agent with strong bonding properties, high temperature resistance, acid corrosion resistance, and oxidation resistance.

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