Dismounting and mounting process for furnace shell and cooling wall of blast furnace body

Abstract

The invention discloses a dismounting and mounting process for a furnace shell and a cooling wall of a blast furnace body. The dismounting and mounting process comprises the following steps: S1, early-stage preparation; s2, dismantling an old blast furnace body: S21, firstly dismantling a furnace top airtight box, then dismantling a furnace top gas sealing cover, and arranging a protection steel plate at the upper part of a furnace top large platform to divide the furnace body into an upper construction area and a lower construction area; s22, the upper area of the furnace body is dismantled, specifically, furnace top equipment, a furnace top crown block, a furnace top frame steel structure, a pressure equalizing pipeline and a valve are sequentially dismantled, and the furnace top equipment comprises a material receiving tank, a pressure equalizing material tank, an upper sealing valve, a lower sealing valve and a guide vertical pipe compensator; s23, dismantling the lower area of the furnace body: synchronously dismantling cooling walls of the furnace body along with the furnace shell, cutting the cooling walls into strips according to an annular welding seam of the furnace shell by oxygen blowing, and then vertically cutting every two cooling walls of each strip of the furnace shell by oxygen blowing in blocks; and S3, a new blast furnace body is installed. According to the invention, a base structure does not need to be reconstructed, and reconstruction cost is reduced; and the residual iron notch can be flexibly switched according to carbon brick damage and abnormal temperature conditions, so as to adapt to different furnace condition requirements.

Description

Technical Field

[0001] This invention relates to the field of blast furnace modification technology, specifically a process for dismantling and installing the blast furnace shell and cooling walls. Background Technology

[0002] As the service life of blast furnaces gradually reaches its end, more and more projects require upgrading and renovation of the furnace and auxiliary pipelines. Generally, it is required to retain the main frame structure of the blast furnace and replace the furnace shell, cooling walls, hot blast ducts and auxiliary pipelines.

[0003] The existing announcement number CN110760634A discloses a method for installing a blast furnace shell. The furnace shell includes multiple sub-shells stacked vertically. The installation method includes: Step 1, assembling multiple sub-shells below a preset height in a forward-mounted manner to form a lower furnace shell module; Step 2, assembling multiple sub-shells above the preset height in a reverse-mounted manner to form an upper furnace shell module; Step 3, connecting the upper furnace shell module to the lower furnace shell module to form the blast furnace shell. Summary of the Invention

[0004] The purpose of this invention is to provide a process for dismantling and installing the blast furnace shell and cooling walls to solve the problems in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a process for dismantling and installing the blast furnace shell and cooling wall, comprising the following steps: S1. Preliminary Preparations: S11. Residual Iron Discharge: The location of the residual iron outlet is determined by thermocouple monitoring based on the furnace condition, with priority given to the outlet on the upper surface of the top carbon brick at the bottom of the furnace. Before residual iron discharge, the rails and the surrounding ground are laid with dry sand with a thickness of ≥300mm. The number of molten iron ladles is estimated based on the amount of molten iron discharged. Steel troughs are placed between the molten iron ladles, and castable refractory with a thickness of ≥100mm is laid in the steel troughs. Residual iron discharge continues for 6-24 hours. S12. Cooling operation: Before cooling the furnace, open the furnace top inspection door, furnace top vent valve and gravity dust collector shut-off valve, and protect the furnace top cables and flammable materials; when cooling the furnace, first use a small water mist, and gradually increase the water volume. The cooling process should last for 24-48 hours. During the cooling period, personnel are prohibited from working or walking on or around the furnace. S2. Demolition of the old blast furnace body: S21. First, remove the airtight box on the top of the furnace, then remove the gas cover on the top of the furnace. Install a protective steel plate on the upper part of the large platform on the top of the furnace to divide the furnace body into upper and lower construction areas. S22. Demolition of the upper part of the furnace body: The furnace top equipment, furnace top crane, furnace top frame steel structure and pressure equalization pipelines and valves are removed in sequence. The furnace top equipment includes receiving tank, pressure equalization tank, upper and lower sealing valves, and guide vertical pipe compensator. S23. Removal of the lower part of the furnace body: The furnace cooling wall is removed simultaneously with the furnace shell. The furnace shell is cut into strips by oxygen blowing along the circumferential weld seam. Then, oxygen blowing is performed vertically along each strip of furnace shell, cutting every two cooling walls in sections. The process is repeated until the surrounding pipe is removed, and all the refractory and furnace charge at the bottom of the furnace body are removed. S3. Installation of the new blast furnace body: S31. A furnace shell pushing platform is set up on the iron tapping platform, directly opposite the furnace body axis and directly below the overhead crane. A furnace shell assembly platform is set up in the area directly below the overhead crane and on one side of the pushing platform. S32. First, push the first ring plate of the furnace bottom into the furnace body installation area for installation, and simultaneously correct the baseline and bottom elevation of the blast furnace shell; after the furnace shell is assembled in the tapping area, it is transported to the sliding trolley by a crane, and the sliding trolley pushes the furnace shell to the center of the furnace body installation area and welds it in place. The installation procedures for the 1-4 ring furnace shells are the same, and the installation of the 1-4 ring cooling walls is completed simultaneously. S33. Before installing the furnace shell in reverse hoisting, a qualified construction unit shall verify its stability. If the furnace frame is not stable, it shall be reinforced according to the design guidance of the design institute. S34. The furnace shell of the 14th-6th section adopts the reverse hoisting method. The furnace shell of the 14th section is sent to the center of the furnace area by a sliding trolley, and then hoisted to the top of the furnace by a hoisting winch. It is then suspended and hoisted on the upper part of the existing frame steel structure by steel wire rope. The hoisting process is repeated in order from high to low to complete the hoisting of the furnace shell of the 13th-6th section. S35. When the furnace shell is hoisted to the tuyere, the three sections of the surrounding pipe are sent to the tuyere platform by the sliding trolley. After the sliding trolley completes the pushing of the tuyere and the furnace shell, the furnace shell is welded and installed. S36. After completing the installation of the tuyeres to the furnace shell of the 7th zone, the corresponding cooling walls and the top protective canopy of the 7th zone are installed simultaneously. After the overall casing is formed, the lifting points are reached simultaneously and the casing is suspended and positioned on the furnace body. S37. When installing the 8th furnace shell and the upper furnace shell, the refractory material inside the furnace is laid simultaneously; before installing the gas cover on the furnace top, the protective shed is removed, and the remaining furnace shell installation and the refractory brick laying of the furnace shell cylinder are completed simultaneously. The installation of the furnace top equipment and steel structure is carried out simultaneously with the construction of the surrounding pipe, and the furnace drying conditions are finally achieved.

[0006] Preferably, in S11, the selection of the location of the residual iron tap also includes the upper surface of the ceramic pad on the inner side of the blast furnace bottom, which is determined between the upper surface of the ceramic pad on the inner side of the blast furnace bottom and the upper surface of the carbon brick on the top layer of the furnace bottom, depending on the actual furnace conditions.

[0007] Preferably, when the top carbon bricks at the bottom of the furnace are severely damaged or the thermocouple shows that the temperature in that area is abnormal, the upper surface of the ceramic pad at the bottom of the blast furnace is selected as the taphole for residual iron. Construct a protective system within a 1.5m radius around the bottom of the residual iron trench. First, clear debris from the area, then lay the rails and surrounding ground with quartz sand with a dryness of ≥95%, with a thickness of ≥300mm, ensuring the sand layer is flat and without gaps. Determine the number of molten iron ladles based on the blast furnace volume (estimated at 0.8-1.2t of residual iron per cubic meter of furnace volume). The molten iron ladles should be made of 304 stainless steel with a volume of ≥50m³, maintaining a distance of 1.2-1.5m between ladles. Place U-shaped steel troughs (300mm×200mm×10mm cross-section) in the gaps. Evenly lay castable refractory (high alumina material, Al2O3 content ≥75%) on the inner wall of the steel trough, with a thickness of ≥100mm, and allow the castable refractory to cure for ≥24 hours. The residual iron taphole is formed by oxy-acetylene flame cutting, with the cutting diameter controlled at 800-1000mm. During discharge, the flow rate of molten iron is adjusted by a flow control valve to maintain a stable flow rate of 0.5-0.8m³ / min. At least three full-time safety officers are assigned to monitor the smoothness of the residual iron taphole and the risk of molten iron overflow in real time. The discharge lasts for 6-24 hours until no more molten iron flows out of the residual iron taphole.

[0008] Preferably, during the refractory lining process inside the furnace, the flatness and sealing of the refractory lining should be monitored in real time. If there are any lining defects, they should be repaired in time to ensure the quality of the refractory lining.

[0009] Preferably, in step S12, when using water mist for cooling, the spray intensity of the water mist is controlled to avoid cracks in the furnace body caused by excessively rapid cooling.

[0010] Preferably, 12 hours before cooling the furnace, the owner shall complete the pretreatment of the furnace top area, open all furnace top inspection doors (4-6 doors in total, each door ≥1.2m×1.5m in size) to ensure air circulation inside the furnace; open all vent valves on the furnace top (including main vent valves and standby vent valves) and gravity dust collector shut-off valves, with valve opening degree ≥90%; wrap the furnace top cables (including power cables and control cables) with high-temperature resistant fiberglass cloth, with ≥2 layers of wrapping; and remove all flammable items (such as insulation cotton and plastic pipelines) on the furnace top platform to a safe area more than 10m away from the furnace body. High-pressure atomizing nozzles (atomized particle diameter ≤50μm) are used to spray water mist into the furnace from the inspection door on the top of the furnace. In the initial stage, the spray volume is controlled at 5-8m³ / h, and it is increased by 3-5m³ / h every 6 hours until the spray volume reaches 15-20m³ / h. The furnace cooling period is 24-48 hours. During this period, the furnace temperature is monitored by temperature sensors installed on the side wall of the furnace (arranged at intervals ≤2m). The furnace cooling is stopped when the surface temperature of the furnace drops to 80-100℃.

[0011] Preferably, in step S32, after each section of the furnace shell is installed, the roundness and verticality of the furnace shell must be checked, and the next section of the furnace shell can only be installed after the check is qualified.

[0012] Compared with the prior art, the beneficial effects of the present invention are: In the initial residual iron discharge stage, thermocouples are used to precisely locate the residual iron outlet, coupled with a ≥300mm thick quartz sand protective layer, a 50m³ 304 stainless steel molten iron ladle, and U-shaped steel trough casting refractory buffer, to prevent the risk of molten iron overflow and ladle damage from the source. For furnace cooling operations, a "gradual water mist cooling" method is adopted (initially 5-8m³ / h, gradually increasing to 15-20m³ / h), combined with an 80-100℃ furnace shutdown threshold, to prevent the furnace body from cracking due to excessive temperature differences. Simultaneously, cables are wrapped with high-temperature resistant fiberglass cloth, and flammable materials are moved to a safe area 10m away to eliminate fire hazards. During reverse hoisting, steel wire rope protective pads are installed, and verticality is monitored in real time with a theodolite (stop if deviation exceeds 5mm). Furthermore, the frame's sturdiness is verified by a Class A qualified unit, comprehensively reducing the risk of structural instability and equipment wear.

[0013] The dismantling process is "synchronized and modularized": An innovative "simultaneous dismantling of furnace shell and cooling wall" model is adopted. The furnace shell is cut into 1.5-2m strips along the circumferential weld seam, and then vertically divided into sections (2m x 1.5m), avoiding repetitive work of dismantling the cooling wall separately. The dismantling of equipment in the upper area proceeds in the order of "core-auxiliary-steel structure," eliminating the need for repeated adjustments to hoisting equipment. Compared to traditional step-by-step dismantling, the efficiency of single-furnace dismantling is increased by more than 20%. The installation process involves coordinated "forward and reverse hoisting": Furnace shells in sections 1-4 are installed using a "assembly-sliding-welding" assembly line operation, with the sliding trolley pushing at a speed of 0.5-1m / min. The installation process for sections 1-4 is unified, reducing process changeover time. Furnace shells in sections 6-14 are hoisted from high to low, utilizing existing frames for suspension and positioning, eliminating the need for costly temporary supports. Combined with "synchronous construction" of the enclosure pipe, cooling wall, and refractory materials (e.g., refractory material is laid simultaneously when installing the 8th furnace shell), the overall furnace shutdown cycle is shortened by 10-15%, reducing production losses for the company.

[0014] The furnace bottom ring plate is installed using a total station to calibrate the baseline (axis deviation ≤3mm) and bottom elevation (deviation ≤5mm); after each furnace shell is installed, the roundness (deviation ≤5mm) and verticality must be checked, and the welds are subjected to 100% ultrasonic testing (pass rate ≥98%); when installing the casing, the flatness of the flange sealing surface is ≤0.1mm, and the bolt tightening torque is controlled at 800-1000N・m, eliminating potential hazards from structural dimensions to connection sealing.

[0015] The process is clearly applicable to blast furnaces with a volume of ≥850m³, especially for technical upgrade projects that "retain the main frame and replace the furnace shell and cooling wall", which do not require reconstruction of the basic structure and reduce the cost of the upgrade. The residual iron tap can be flexibly switched (carbon brick tap / ceramic pad tap) according to the carbon brick damage and abnormal temperature conditions to adapt to different furnace conditions. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. 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 claimed invention, but merely to illustrate selected embodiments of the invention.

[0018] Please see Figure 1 In this embodiment of the invention, a process for dismantling and installing the blast furnace shell and cooling wall includes the following steps: S1. Preliminary Preparations: S11. Residual Iron Discharge: The location of the residual iron outlet is determined by thermocouple monitoring based on the furnace condition, with priority given to the outlet on the upper surface of the top carbon brick at the bottom of the furnace. Before residual iron discharge, the rails and the surrounding ground are laid with dry sand with a thickness of ≥300mm. The number of molten iron ladles is estimated based on the amount of molten iron discharged. Steel troughs are placed between the molten iron ladles, and castable refractory with a thickness of ≥100mm is laid in the steel troughs. Residual iron discharge continues for 6-24 hours. S12. Cooling operation: Before cooling the furnace, open the furnace top inspection door, furnace top vent valve and gravity dust collector shut-off valve, and protect the furnace top cables and flammable materials; when cooling the furnace, first use a small water mist, and gradually increase the water volume. The cooling process should last for 24-48 hours. During the cooling period, personnel are prohibited from working or walking on or around the furnace. S2. Demolition of the old blast furnace body: S21. First, remove the airtight box on the top of the furnace, then remove the gas cover on the top of the furnace. Install a protective steel plate on the upper part of the large platform on the top of the furnace to divide the furnace body into upper and lower construction areas. S22. Demolition of the upper part of the furnace body: The furnace top equipment, furnace top crane, furnace top frame steel structure and pressure equalization pipelines and valves are removed in sequence. The furnace top equipment includes receiving tank, pressure equalization tank, upper and lower sealing valves, and guide vertical pipe compensator. S23. Removal of the lower part of the furnace body: The furnace cooling wall is removed simultaneously with the furnace shell. The furnace shell is cut into strips by oxygen blowing along the circumferential weld seam. Then, oxygen blowing is performed vertically along each strip of furnace shell, cutting every two cooling walls in sections. The process is repeated until the surrounding pipe is removed, and all the refractory and furnace charge at the bottom of the furnace body are removed. Construction area division: Q235B steel plate (thickness ≥16mm, size matching the large platform on the furnace top) is used as protective steel plate and fixed to the upper part of the large platform on the furnace top (0.8-1.2m away from the edge of the furnace body) with expansion bolts. A 50mm high water-retaining edge is set at the edge of the steel plate to divide the furnace body into an upper construction area (from the furnace top to the upper middle part of the furnace body) and a lower construction area (from the lower middle part of the furnace body to the furnace bottom). Demolition of the upper area: Dismantling of core equipment on the furnace top: First, dismantle the furnace top airtight box (using 4 5t hand-operated hoists for symmetrical hoisting, and preheating to 80-100℃ with heating rods when removing bolts), then dismantle the furnace top gas cover (using a 25t truck crane for hoisting, cutting off the gas pipeline and performing nitrogen purging before dismantling, with the gas concentration ≤0.5% after purging). Dismantling of auxiliary equipment on the furnace top: The furnace top equipment is dismantled in sequence, including the receiving tank (volume ≥ 20m³, hoisted simultaneously by two 10t winches), the equalizing tank (diameter ≥ 3m, the pressure inside the tank is released to atmospheric pressure before dismantling), the upper and lower sealing valves (valve weight ≤ 5t, hoisted by a 5t electric hoist), and the guide vertical pipe compensator (corrugated compensator model DN800, avoid collision with the corrugated section during dismantling); then the furnace top trolley is dismantled (span ≥ 20m, lifted by four 50t truck cranes, the track bolts are removed using a torque wrench according to the specified torque); Steel structure and pipeline dismantling: dismantle the furnace top frame steel structure (material Q355B, cut in sections using oxy-acetylene flame, each section weighing ≤10t), then dismantle the equalizing pipeline and valves (pipeline diameter ≥DN300, clean the residual gas in the pipeline before dismantling, and cover the surrounding equipment with fireproof blankets during cutting). Demolition of the lower area (core and difficult process): Pre-dismantling treatment: First, clean up the debris on the lower platform of the furnace body, and set up temporary supports on the outside of the furnace shell (using Φ200mm seamless steel pipes, with a spacing of ≤2m) to prevent the furnace shell from deforming; Synchronous dismantling operation: The furnace cooling wall (made of ductile iron, single piece weight ≤3t) and the furnace shell (made of Q345R, thickness ≥20mm) are dismantled simultaneously. Using an oxy-acetylene flame (cutting nozzle model G01-100), the furnace shell is cut into strips (each strip height 1.5-2m) along the circumferential weld seam. The cutting speed is controlled at 50-80mm / min to avoid local overheating. Then, the furnace shell is cut into sections along the vertical gap between every two cooling walls on each section. The section size is controlled at 2m×1.5m (length×height), and each section weighs ≤5t. Residue cleaning: After cutting, the furnace shell and cooling wall blocks are transported to the designated stacking area by a 16t crane. After being dismantled in a cycle to the position of the surrounding pipe (material is Q345R, diameter ≥2m), the residual refractory material (material is clay brick) and furnace charge (mixture of coke and ore) at the bottom of the furnace body are cleaned with a high-pressure water gun (pressure ≥10MPa) until the furnace bottom base is completely exposed.

[0019] S3. Installation of the new blast furnace body: S31. A furnace shell pushing platform is set up on the iron tapping platform, directly opposite the furnace body axis and directly below the overhead crane. A furnace shell assembly platform is set up in the area directly below the overhead crane and on one side of the pushing platform. S32. First, push the first ring plate of the furnace bottom into the furnace body installation area for installation, and simultaneously correct the baseline and bottom elevation of the blast furnace shell; after the furnace shell is assembled in the tapping area, it is transported to the sliding trolley by a crane, and the sliding trolley pushes the furnace shell to the center of the furnace body installation area and welds it in place. The installation procedures for the 1-4 ring furnace shells are the same, and the installation of the 1-4 ring cooling walls is completed simultaneously. S33. Before installing the furnace shell in reverse hoisting, a qualified construction unit shall verify its stability. If the furnace frame is not stable, it shall be reinforced according to the design guidance of the design institute. S34. The furnace shell of the 14th-6th section adopts the reverse hoisting method. The furnace shell of the 14th section is sent to the center of the furnace area by a sliding trolley, and then hoisted to the top of the furnace by a hoisting winch. It is then suspended and hoisted on the upper part of the existing frame steel structure by steel wire rope. The hoisting process is repeated in order from high to low to complete the hoisting of the furnace shell of the 13th-6th section. S35. When the furnace shell is hoisted to the tuyere, the three sections of the surrounding pipe are sent to the tuyere platform by the sliding trolley. After the sliding trolley completes the pushing of the tuyere and the furnace shell, the furnace shell is welded and installed. S36. After completing the installation of the tuyeres to the furnace shell of the 7th zone, the corresponding cooling walls and the top protective canopy of the 7th zone are installed simultaneously. After the overall casing is formed, the lifting points are reached simultaneously and the casing is suspended and positioned on the furnace body. S37. When installing the 8th furnace shell and the upper furnace shell, the refractory material inside the furnace is laid simultaneously; before installing the gas cover on the furnace top, the protective shed is removed, and the remaining furnace shell installation and the refractory brick laying of the furnace shell cylinder are completed simultaneously. The installation of the furnace top equipment and steel structure is carried out simultaneously with the construction of the surrounding pipe, and the furnace drying conditions are finally achieved.

[0020] Basic platform setup: Setting up the moving platform: A furnace shell moving platform is built with Q355B steel at the position of the iron tapping platform (bearing capacity ≥20t / m²) directly opposite the furnace body axis. The platform is ≥20m long and ≥5m wide. The platform surface is covered with 20mm thick steel plates, which are welded and fixed together. 1.2m high-speed rail guardrails are set on both sides of the platform. Assembly platform setup: A furnace shell assembly platform is built in the area directly below the overhead crane (rated lifting capacity ≥ 50t) and on one side of the moving platform (spacing ≤ 3m). The platform foundation is made of C30 concrete (thickness ≥ 300mm) and the surface is covered with 16mm thick steel plates. Positioning pins (diameter ≥ 50mm, spacing ≤ 1.5m) are set on the platform for positioning during furnace shell assembly. 1-4 Installation of furnace shell and cooling wall (foundation layer installation): Installation of the furnace bottom ring plate: The first furnace bottom ring plate (material Q345R, diameter matching the furnace bottom, thickness ≥30mm) is hoisted to the moving platform by a 16t overhead crane, and then pushed into the furnace body installation area by a hydraulic moving device (thrust ≥100t). After adjusting the levelness of the ring plate (deviation ≤2mm / m), it is welded and fixed by submerged arc automatic welding (welding wire type H08MnA); at the same time, the baseline of the blast furnace shell (axis deviation ≤3mm) and the bottom elevation (elevation deviation ≤5mm) are corrected by a total station (accuracy ≤2mm). Furnace Shell Assembly and Installation: The furnace shell is assembled in a ring on the assembly platform at the tapping area. Each section of the furnace shell (corresponding to a 90° arc, weight ≤15t) is positioned using locating pins. The assembly gap is controlled at 2-3mm. Spot welding (using E5015 welding rods) is used for fixation. After assembly, the overall weight is ≤60t. A 50t overhead crane then lifts the furnace shell onto a sliding trolley (load capacity ≥80t, travel speed 0.5-1m / min). The sliding trolley pushes the furnace shell along the track to the center of the furnace installation area. After ensuring the roundness of the entire furnace shell (roundness deviation ≤ 5mm), circumferential welding is performed using submerged arc automatic welding. The welding current is controlled at 500-600A, the voltage at 30-32V, and the welding speed at 25-30cm / min. The installation procedure for furnace shells 1-4 is consistent. After each furnace shell is installed, the corresponding cooling wall is immediately installed. The space between the cooling wall and the furnace shell is filled with refractory castable (material is low cement castable, bulk density ≥ 2.6g / cm³), with a filling thickness ≥ 50mm and a curing time ≥ 48h. Preparations before reverse hoisting: Stability verification: 72 hours before the furnace shell is installed and reversed, a construction unit with a Class A general contracting qualification for metallurgical engineering construction shall use a total station to test the verticality (deviation ≤1 / 1000) and spacing (deviation ≤5mm) of the furnace frame (including columns and beams). At the same time, a stress tester shall be used to monitor the stress value of key nodes of the frame (stress value ≤150MPa) to verify the stability of the frame. Frame reinforcement: If the inspection finds unstable parts in the furnace frame (such as excessive verticality deviation or excessive stress value), the frame shall be reinforced according to the special reinforcement plan issued by the design institute by adding gusset plates (material Q355B, thickness ≥12mm) and setting diagonal braces (Φ159mm seamless steel pipes). After the reinforcement is completed, the frame shall be re-inspected until the stability requirements are met. 6-14 Furnace shell reverse hoisting (upper middle part installation): Lifting equipment configuration: Two 100t hoisting winches (rated head ≥ 50m, wire rope safety factor ≥ 6) are used, along with four sets of pulley blocks (pulley diameter ≥ 500mm), set at designated locations on the furnace top platform. The winch foundation is made of C30 concrete (volume ≥ 5m³) and undergoes an overload test (loaded with 120% rated load and held for 30min). The hoisting process is as follows: Starting with the 14th furnace shell, hoisting proceeds from high to low. The 14th furnace shell (weight ≤25t) is transported to the center of the furnace area via a sliding trolley (traveling speed 0.8-1m / min). The hoisting winch connects to the furnace shell lifting points (4 lifting points are set for each furnace shell, evenly distributed) via steel wire ropes (diameter ≥32mm, length ≥60m), and slowly hoists it to the top of the furnace (lifting speed ≤0.5m / min). After adjusting the furnace shell position, the steel wire ropes are suspended and fixed to the lifting lugs on the upper part of the existing steel frame structure (load capacity verified to be ≥30t). The same process is followed to complete the hoisting of the 13th, 12th, 11th, 10th, 9th, 8th, 7th, and 6th furnace shells. After each furnace shell is hoisted, a temporary fixing device (Φ50mm bolts) is used to connect it to the already installed furnace shell to prevent displacement. Simultaneous installation of enclosure pipes: Transport and positioning of the casing pipe: The casing pipe (divided into three sections, each weighing ≤30t, made of Q345R material) is transported to the tapping yard by flatbed trailer, and then lifted by a 50t overhead crane to the sliding trolley and sent to the tuyere platform (the elevation of which matches the tuyere and furnace shell). Installation and fixing of the casing: After the sliding trolley completes the pushing and welding of the tuyere and furnace shell, adjust the position of the casing so that the casing fits into the connecting flange of the tuyere and furnace shell (the flatness of the sealing surface is ≤0.1mm). Use high-strength bolts (model M30, performance grade 8.8) for connection. The bolt tightening torque is controlled at 800-1000N・m. After the connection is completed, use graphite packing (section size 10mm×10mm) to seal the flange sealing surface. Matching installation and refractory masonry: Cooling wall and protective shed installation: After the tuyeres to the 7th zone furnace shell are installed, the corresponding cooling walls are installed simultaneously. The installation gap of the cooling walls is controlled at 3-5mm, and refractory mortar (material is high alumina, Al2O3 content ≥65%) is used for filling. Then, the top protective shed of the 7th zone is built. The protective shed uses Q235B steel as the frame (section size 100mm×100mm), and the surface is covered with color steel plate (thickness ≥0.8mm). The height of the shed is ≥2.5m, and protective netting (mesh size ≤50mm×50mm) is set around it. Positioning and refractory material construction of the enclosure pipe: After the enclosure pipe is formed as a whole, the position of the enclosure pipe is adjusted synchronously by four 10t hand-operated hoists to ensure that the deviation between the center line of the enclosure pipe and the furnace body axis is ≤3mm. The enclosure pipe is then suspended and positioned on the pre-set lifting points of the furnace body frame. When installing the 8th belt and the upper furnace shell, the refractory material construction inside the furnace is started simultaneously. The refractory material used is high-alumina brick (Al2O3 content ≥85%, size 230mm×114mm×65mm). The full mortar method is used during construction, and the mortar joint thickness is controlled at 2-3mm. A flatness test is performed every 3 layers (deviation ≤2mm / m). Finishing and Acceptance: Removal and final installation of the protective shed: Before installing the gas cover on the furnace top, a 16t overhead crane is used to remove the top protective shed of the 7th section. During the removal process, collisions with the already installed furnace shell are avoided. Simultaneously, the installation of the remaining furnace shell (furnace top position) and the laying of refractory bricks (material is carbon brick, bulk density ≥1.8g / cm³) in the hearth are completed. After the hearth refractory bricks are laid, pre-treatment before drying the furnace is carried out (preheating to 100-120℃ using electric heating tubes and keeping warm for 24 hours). Simultaneous construction and acceptance: The installation of furnace top equipment (airtight box, gas cover, etc.) and steel structure (frame, platform, etc.) and the surrounding pipe masonry are carried out simultaneously. After the installation is completed, the furnace body is subjected to overall sealing test (using airtightness test, pressure 0.1MPa, pressure holding for 30min, leakage rate ≤0.5%) and structural stability test (using total station to test verticality and roundness). After all tests are qualified, it is confirmed that the furnace drying conditions are met, and finally the blast furnace can be successfully tapped.

[0021] Preferably, in S11, the selection of the location of the residual iron tap also includes the upper surface of the ceramic pad on the inner side of the blast furnace bottom, which is determined between the upper surface of the ceramic pad on the inner side of the blast furnace bottom and the upper surface of the carbon brick on the top layer of the furnace bottom, depending on the actual furnace conditions.

[0022] Preferably, when the top carbon bricks at the bottom of the furnace are severely damaged or the thermocouple shows that the temperature in that area is abnormal, the upper surface of the ceramic pad at the bottom of the blast furnace is selected as the taphole for residual iron. Construct a protective system within a 1.5m radius around the bottom of the residual iron trench. First, clear debris from the area, then lay the rails and surrounding ground with quartz sand with a dryness of ≥95%, with a thickness of ≥300mm, ensuring the sand layer is flat and without gaps. Determine the number of molten iron ladles based on the blast furnace volume (estimated at 0.8-1.2t of residual iron per cubic meter of furnace volume). The molten iron ladles should be made of 304 stainless steel with a volume of ≥50m³, maintaining a distance of 1.2-1.5m between ladles. Place U-shaped steel troughs (300mm×200mm×10mm cross-section) in the gaps. Evenly lay castable refractory (high alumina material, Al2O3 content ≥75%) on the inner wall of the steel trough, with a thickness of ≥100mm, and allow the castable refractory to cure for ≥24 hours. The residual iron taphole is formed by oxy-acetylene flame cutting, with the cutting diameter controlled at 800-1000mm. During discharge, the flow rate of molten iron is adjusted by a flow control valve to maintain a stable flow rate of 0.5-0.8m³ / min. At least three full-time safety officers are assigned to monitor the smoothness of the residual iron taphole and the risk of molten iron overflow in real time. The discharge lasts for 6-24 hours until no more molten iron flows out of the residual iron taphole.

[0023] Preferably, during the refractory lining process inside the furnace, the flatness and sealing of the refractory lining should be monitored in real time. If there are any lining defects, they should be repaired in time to ensure the quality of the refractory lining.

[0024] Preferably, in step S12, when using water mist for cooling, the spray intensity of the water mist is controlled to avoid cracks in the furnace body caused by excessively rapid cooling.

[0025] Preferably, 12 hours before cooling the furnace, the owner shall complete the pretreatment of the furnace top area, open all furnace top inspection doors (4-6 doors in total, each door ≥1.2m×1.5m in size) to ensure air circulation inside the furnace; open all vent valves on the furnace top (including main vent valves and standby vent valves) and gravity dust collector shut-off valves, with valve opening degree ≥90%; wrap the furnace top cables (including power cables and control cables) with high-temperature resistant fiberglass cloth, with ≥2 layers of wrapping; and remove all flammable items (such as insulation cotton and plastic pipelines) on the furnace top platform to a safe area more than 10m away from the furnace body. High-pressure atomizing nozzles (atomized particle diameter ≤50μm) are used to spray water mist into the furnace from the inspection door on the top of the furnace. In the initial stage, the spray volume is controlled at 5-8m³ / h, and it is increased by 3-5m³ / h every 6 hours until the spray volume reaches 15-20m³ / h. The furnace cooling period is 24-48 hours. During this period, the furnace temperature is monitored by temperature sensors installed on the side wall of the furnace (arranged at intervals ≤2m). The furnace cooling is stopped when the surface temperature of the furnace drops to 80-100℃.

[0026] Preferably, in step S32, after each section of the furnace shell is installed, the roundness and verticality of the furnace shell must be checked, and the next section of the furnace shell can only be installed after the check is qualified.

[0027] In the residual iron discharge process, the molten iron ladle needs to be preheated before use. The temperature inside the ladle is raised to 150-200℃ by electric heating, and the preheating time is ≥2h to prevent the molten iron from solidifying due to excessive temperature difference after entering the ladle.

[0028] In the furnace cooling operation, the number of high-pressure atomizing nozzles is matched with the blast furnace volume. When the blast furnace volume is <1000m³, 4 nozzles are arranged; when the volume is 1000m³≤2000m³, 6 nozzles are arranged; and when the volume is ≥2000m³, 8 nozzles are arranged. The nozzles are evenly distributed around the inspection door on the top of the furnace to ensure that the water mist covers the entire furnace area.

[0029] During the demolition process of the lower part of the furnace body, a special dust removal device (with a processing air volume ≥ 5000 m³ / h) is used for oxygen blowing cutting. The dust generated during cutting is collected by a dust collection hood, and the dust emission concentration is ≤ 30 mg / m³, which meets the requirements of the "Emission Standard of Air Pollutants for Industrial Furnaces and Kilns" (GB9078-1996).

[0030] In the installation process of furnace shells 1-4, after each furnace shell is installed, an ultrasonic flaw detector (probe frequency 2.5-5MHz) is used to perform non-destructive testing on the circumferential seam of the furnace shell, with a testing coverage of 100%, to ensure that the welded joint is free of defects such as cracks and lack of fusion, and the welding qualification rate is ≥98%.

[0031] During the reverse hoisting process, protective pads (made of rubber, with a thickness of ≥10mm and an area of ​​≥200mm×200mm) are installed at the connection points between the wire rope and the furnace shell hoisting point to prevent the wire rope from abrading the furnace shell surface. At the same time, a theodolite is used to monitor the verticality of the furnace shell in real time during the hoisting process. If the deviation exceeds 5mm, the hoisting is stopped immediately, and the operation is continued after adjustment.

[0032] In the furnace refractory lining process, the refractory materials must undergo quality inspection before entering the site. The inspection items include bulk density, compressive strength (≥50MPa), and flexural strength (≥8MPa). Only materials that pass the inspection can be used. After the lining is completed, a high-temperature adhesive (usage temperature ≥1200℃) is used to seal the gaps in the refractory materials to enhance the overall sealing performance of the refractory materials.

[0033] In the installation process of the enclosure pipe, the enclosure pipe welding adopts gas shielded welding (the shielding gas is a mixture of Ar and CO2 gas with a volume ratio of 8:2), the welding current is 200-250A, the voltage is 22-25V, and the welding speed is 15-20cm / min. After the welding is completed, the weld is subjected to radiographic inspection (inspection ratio 20%) to ensure that the weld quality meets the requirements of "Welding Procedure Qualification for Pressure Equipment" (NB / T47014-2011).

[0034] During the installation of the furnace top equipment, when the furnace top airtight box is installed, the sealing surface is ground (surface roughness Ra≤0.8μm), and an airtightness test is performed after installation (pressure 0.05MPa, pressure holding for 15min, no leakage); when the upper and lower airtight valves are installed, the deviation between the valve opening indicator and the actual opening is adjusted to ≤1% to ensure accurate valve operation.

[0035] The process is applicable to blast furnaces with a volume of ≥850m³, and is especially suitable for technical renovation projects involving the simultaneous removal and installation of the furnace shell and cooling wall. It can shorten the blast furnace shutdown cycle by 10-15% and extend the service life of the furnace body by 5-8 years after installation.

[0036] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for dismantling the blast furnace shell and cooling walls, characterized in that, Includes the following steps: S1. Preliminary Preparations: S11. Residual Iron Discharge: The location of the residual iron outlet is determined by thermocouple monitoring based on the furnace condition, with priority given to the outlet on the upper surface of the top carbon brick at the bottom of the furnace. Before residual iron discharge, the rails and the surrounding ground are laid with dry sand with a thickness of ≥300mm. The number of molten iron ladles is estimated based on the amount of molten iron discharged. Steel troughs are placed between the molten iron ladles, and castable refractory with a thickness of ≥100mm is laid in the steel troughs. Residual iron discharge continues for 6-24 hours. S12. Cooling operation: Before cooling the furnace, open the furnace top inspection door, furnace top vent valve and gravity dust collector shut-off valve, and protect the furnace top cables and flammable materials; when cooling the furnace, first use a small water mist, and gradually increase the water volume, and continue cooling the furnace for 24-48 hours. S2. Demolition of the old blast furnace body: S21. First, remove the airtight box on the top of the furnace, then remove the gas cover on the top of the furnace. Install a protective steel plate on the upper part of the large platform on the top of the furnace to divide the furnace body into upper and lower construction areas. S22. Demolition of the upper part of the furnace body: The furnace top equipment, furnace top crane, furnace top frame steel structure and pressure equalization pipelines and valves are removed in sequence. The furnace top equipment includes receiving tank, pressure equalization tank, upper and lower sealing valves, and guide vertical pipe compensator. S23. Removal of the lower part of the furnace body: The furnace cooling wall is removed simultaneously with the furnace shell. The furnace shell is cut into strips by oxygen blowing along the circumferential weld seam. Then, oxygen blowing is performed vertically along each strip of furnace shell, cutting every two cooling walls in sections. The process is repeated until the surrounding pipe is removed, and all the refractory and furnace charge at the bottom of the furnace body are removed. S3. Installation of the new blast furnace body: S31. A furnace shell pushing platform is set up on the iron tapping platform, directly opposite the furnace body axis and directly below the overhead crane. A furnace shell assembly platform is set up in the area directly below the overhead crane and on one side of the pushing platform. S32. First, push the first ring plate of the furnace bottom into the furnace body installation area for installation, and simultaneously correct the baseline and bottom elevation of the blast furnace shell; after the furnace shell is assembled in the tapping area, it is transported to the sliding trolley by a crane, and the sliding trolley pushes the furnace shell to the center of the furnace body installation area and welds it in place. The installation procedures for the 1-4 ring furnace shells are the same, and the installation of the 1-4 ring cooling walls is completed simultaneously. S33. Before installing the furnace shell in reverse hoisting, a qualified construction unit shall verify its stability. S34. The furnace shell of the 14th-6th section adopts the reverse hoisting method. The furnace shell of the 14th section is sent to the center of the furnace area by a sliding trolley, and then hoisted to the top of the furnace by a hoisting winch. It is then suspended and hoisted on the upper part of the existing frame steel structure by steel wire rope. The hoisting process is repeated in order from high to low to complete the hoisting of the furnace shell of the 13th-6th section. S35. When the furnace shell is hoisted to the tuyere, the three sections of the surrounding pipe are sent to the tuyere platform by the sliding trolley. After the sliding trolley completes the pushing of the tuyere and the furnace shell, the furnace shell is welded and installed. S36. After completing the installation of the tuyeres to the furnace shell of the 7th zone, the corresponding cooling walls and the top protective canopy of the 7th zone are installed simultaneously. After the overall casing is formed, the lifting points are reached simultaneously and the casing is suspended and positioned on the furnace body. S37. When installing the 8th furnace shell and the upper furnace shell, the refractory material inside the furnace is laid simultaneously; before installing the gas cover on the furnace top, the protective shed is removed, and the remaining furnace shell installation and the refractory brick laying of the furnace shell cylinder are completed simultaneously. The installation of the furnace top equipment and steel structure is carried out simultaneously with the construction of the surrounding pipe, and the furnace drying conditions are finally achieved.

2. The process for dismantling and installing the blast furnace shell and cooling wall according to claim 1, characterized in that, In S11, the selection of the location of the residual iron tap also includes the upper surface of the ceramic pad on the inner side of the blast furnace bottom, which is determined by choosing between the upper surface of the ceramic pad on the inner side of the blast furnace bottom and the upper surface of the carbon brick on the top layer of the furnace bottom, according to the actual furnace conditions.

3. The process for dismantling and installing the blast furnace shell and cooling wall according to claim 1, characterized in that, When the top carbon bricks at the bottom of the furnace are severely damaged or the thermocouple shows that the temperature in that area is abnormal, the upper surface of the ceramic pad at the bottom of the blast furnace inside the furnace is selected as the tap for residual iron. Construct a protective system within a 1.5m radius around the bottom of the residual iron trough. First, clear away debris from the area. Then, lay the rails and surrounding ground with quartz sand with a dryness of ≥95%, with a thickness of ≥300mm, and ensure the sand layer is flat and without gaps. Determine the number of molten iron ladles based on the blast furnace volume. The molten iron ladles should be made of 304 stainless steel with a volume of ≥50m³. Maintain a distance of 1.2-1.5m between ladles and place U-shaped steel channels in the gaps. The inner wall of the steel channels should be evenly covered with castable refractory with a thickness of ≥100mm. The curing time for the castable refractory should be ≥24h. The residual iron outlet is formed by oxy-acetylene flame cutting, with the cutting diameter controlled at 800-1000mm. During discharge, the flow rate of molten iron is adjusted by a flow control valve to maintain a stable flow rate of 0.5-0.8m³ / min. The smoothness of the residual iron outlet and the risk of molten iron overflow are monitored in real time. The discharge period is 6-24 hours until no molten iron flows out of the residual iron outlet.

4. The process for dismantling and installing the blast furnace shell and cooling wall according to claim 1, characterized in that, During the refractory lining process inside the furnace, the flatness and sealing of the refractory lining must be monitored in real time. If there are any lining defects, they should be repaired in time to ensure the quality of the refractory lining.

5. The process for dismantling and installing the blast furnace shell and cooling wall according to claim 1, characterized in that, In step S12, when using water mist for cooling, the spray intensity of the water mist is controlled to avoid cracks in the furnace body caused by excessively rapid cooling.

6. The process for dismantling and installing the blast furnace shell and cooling wall according to claim 5, characterized in that, 12 hours before cooling the furnace, open all the inspection doors on the furnace top to ensure air circulation inside the furnace; open all the vent valves on the furnace top and the shut-off valves of the gravity dust collector, with the valve opening degree ≥90%; wrap the furnace top cables with high-temperature resistant fiberglass cloth, with ≥2 layers of wrapping; and remove all flammable materials on the furnace top platform to a safe area more than 10m away from the furnace body. High-pressure atomizing nozzles are used to spray water mist into the furnace from the maintenance door on the top of the furnace. In the initial stage, the spray volume is controlled at 5-8 m³ / h, and it is increased by 3-5 m³ / h every 6 hours until the spray volume reaches 15-20 m³ / h. The furnace cooling period is 24-48 hours. During this period, the furnace temperature is monitored by temperature sensors installed on the side wall of the furnace. The furnace cooling is stopped when the surface temperature of the furnace drops to 80-100℃.

7. The process for dismantling and installing the blast furnace shell and cooling wall according to claim 1, characterized in that, In step S32, after each section of the furnace shell is installed, the roundness and verticality of the furnace shell must be checked. Only after the check is qualified can the next section of the furnace shell be installed.

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