A method for prolonging the service life of a heating cover of a bell-type furnace

Abstract

The present application relates to a kind of methods for prolonging the service life of cover-type furnace heating cover, comprising: 1) adding shock-absorbing hanger;2) reduce the landing speed of heating cover;3) set up landing sand pit;4) heating cover furnace lining construction after normal temperature cold dry and extrusion;5) increase the annealing time of initial temperature section of oven, etc.;By using the way of "normal temperature cold dry + extrusion", the refractory brick layer of heating cover furnace lining is more dense, by lengthening the annealing curve to avoid the fine small holes of furnace lining during heating, by using various shock-absorbing means to eliminate the vibration generated during the lifting and landing of heating cover, effectively increase the service life of heating cover furnace lining, prolong the service life of heating cover.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cold rolling and heat treatment, and particularly relates to a method for prolonging the service life of a cover of a cover furnace. BACKGROUND

[0002] The cover annealing furnace is used for recrystallization annealing of a steel coil after cold rolling to meet the mechanical properties of the steel strip, such as Figure 1 As shown in the figure, the main equipment of the cover furnace includes a furnace table 1, an inner cover 2, a heating cover 3 and a cooling cover. The steel coils 4 are stacked on the furnace table 1, and after the inner cover 2 is sealed, the air in the inner cover 2 is replaced by nitrogen, and then hydrogen is introduced through a hydrogen gas nozzle 5. The heating cover 3 is buckled outside the inner cover 2, and the burners are ignited to heat and anneal the steel coils 4. The heating cover 3 is a steel shell, and the inner side is provided with a furnace lining 31 made of refractory material. The heating cover needs to be buckled and unbuckled every time the annealing is completed. The weight of each heating cover is more than 10 tons, and the vibration during each buckling and unbuckling of the heating cover 3 is an important cause of damage to the furnace lining 31, which seriously affects the service life of the heating cover 3.

[0003] A Chinese patent application with the publication number CN104195320A discloses an "inner cover of high-temperature cover furnace for oriented silicon steel", which comprises an inner cover body and an inner cover top cover located at the top of the inner cover body. The top periphery of the inner cover body is fixedly and sealingly connected with the outer periphery of the inner cover top cover. The inner cover body is provided with a deformation compensation section capable of deforming to compensate for the height of the inner cover body. The deformation compensation section can deform to compensate for the height of the inner cover body, so as to ensure that the inner cover can appropriately deform under high temperature and high pressure, thereby adapting to thermal expansion and contraction during operation of the inner cover, avoiding leakage caused by bulging deformation or rupture of the inner cover due to stress release, affecting normal use, thereby effectively improving the high-temperature and high-pressure resistance of the cover furnace and prolonging the service life of the cover furnace.

[0004] A Chinese utility model patent with the authorization publication number 203582931U discloses a "inner cover of cover furnace", which comprises a flange seat, a water trough, a cylinder, a guide ear, a lifting lug, a head, and a positioning block. The water trough is arranged on one side of the flange seat, and the cylinder is arranged on the flange seat. The cylinder is provided with a guide ear on one side, and the cylinder is provided with a positioning block on the side opposite to the guide ear. The lifting lug is composed of three pieces, which are evenly distributed on the cylinder. The cylinder is provided with a head at the upper end. The cylinder is in a corrugated shape. The head is in a butterfly shape. By making the cylinder in a corrugated shape, the corrugation adopts an Austrian Abner structure, which increases the resistance to thermal deformation, improves the strength, and prolongs the service life of the inner cover.

[0005] The purposes of the above two disclosure documents are to prolong the service life of the inner cover of the cover furnace, but their concerns and solutions are all the damage caused by the deformation or rupture of the inner cover due to high temperature and high pressure; the problem of reducing the service life of the heating cover caused by vibration during buckling and unbuckling of the heating cover is not concerned and solved.

[0006] The application provides a method for prolonging the service cycle of a heating cover of a bell-type furnace, which makes the refractory brick layer of the furnace lining of the heating cover more compact by adopting a normal-temperature cold drying and extrusion mode, avoids the generation of fine and small pores in the furnace lining during furnace baking by prolonging the annealing curve, and eliminates the vibration generated during the lifting and lowering of the heating cover by adopting various damping methods, thereby effectively increasing the service life of the furnace lining of the heating cover and prolonging the service cycle of the heating cover.

[0007] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0008] A method for prolonging the service cycle of a heating cover of a bell-type furnace comprises the following measures:

[0009] 1) a damping hanger is additionally arranged on the top of the heating cover, and a damper is arranged in the damping hanger to serve as a buffer when the heating cover is lifted;

[0010] 2) the falling speed of the heating cover is reduced; after the heating cover is lifted, the heating cover is first lowered at a speed of 25-35 mm / s, and when the bottom surface of the heating cover is 0.8-1.2 m away from the ground, the heating cover is lowered at a speed of 10-15 mm / s until the heating cover falls onto the ground;

[0011] 3) a landing sand pit is arranged; a landing sand pit is arranged at the working position and the placing position of the heating cover after the heating cover is removed, and the landing sand pit is arranged corresponding to the bottom feet of the heating cover;

[0012] 4) the furnace lining of the heating cover is cold dried at normal temperature after being built; after the refractory bricks of the furnace lining are built, the heating cover is placed in a closed space at a temperature of 10-20 DEG C for more than 30 hours before the furnace is baked; and the furnace lining is pressed tightly and compacted by using an extrusion die during the cold drying at normal temperature;

[0013] 5) the annealing time of the initial temperature section of the furnace baking is increased; during the initial temperature section of the furnace baking, the heating cover is kept at a temperature of 150 DEG C + / - 10 DEG C for 33 + / - 0.5 h, and the temperature is raised from 150 DEG C to 300 DEG C in 16-18 h.

[0014] Further, the length and width of the landing sand pit are greater than the length and width of the corresponding direction of the bottom feet of the heating cover, the depth of the pit body of the landing sand pit is 400-600 mm, and fine sand is filled in the pit body.

[0015] Further, the shock-absorbing hanger is composed of a bottom beam, shock absorbers, a hanger beam and a hanger ring; the shock absorbers are 2 groups and symmetrically arranged at the two ends of the bottom beam and the hanger beam; the shock absorber is composed of a shock absorber outer cylinder, a top plate, a bottom plate, a movable plate, a movable rod and a shock-absorbing spring; the top of the shock absorber outer cylinder is provided with the top plate, the bottom is provided with the bottom plate, the movable plate is arranged in the shock absorber outer cylinder, the lower end of the movable rod is connected with the movable plate through threads, the upper end of the movable rod is connected with the hanger beam after penetrating through the top plate; the shock-absorbing spring is arranged on the movable rod between the top plate and the movable plate; the shock absorber is connected with the bottom beam through the bottom plate, and the bottom plate is connected with the bottom beam through a plurality of bolts; the hanger ring is arranged at the middle part of the hanger beam.

[0016] Further, the extrusion die is composed of a plurality of arc-shaped extrusion plates and a plurality of groups of support devices; the arc-shaped extrusion plates are closely arranged on the inner side of the furnace lining, and the height of the arc-shaped extrusion plate is the same as the height of the furnace lining; the two arc-shaped extrusion plates oppositely arranged along the radial direction of the heating cover are supported by the corresponding support devices and tightly abut against the inner walls of the furnace linings on the two sides; each group of support devices is composed of two arc-shaped support plates, one pressing rod and two nut sleeves; the back surface of the arc-shaped extrusion plate away from the furnace lining is provided with the arc-shaped support plate, the arc-shaped support plate has an arc shape matched with the plate-shaped extrusion plate, the arc-shaped extrusion plate is a wooden plate, and the arc-shaped support plate is a steel plate; one end of the arc-shaped support plate connected with the pressing rod is provided with a connecting rod, the connecting rod is provided with threads, the two ends of the pressing rod are respectively provided with threads, and the connecting rod and the corresponding end of the pressing rod are connected through the corresponding nut sleeve; when the nut sleeve is rotated, the arc-shaped support plates on the pressing rod move relatively or oppositely.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] 1) After the lining of the heating cover is built, the "normal temperature cold drying + extrusion" mode is adopted to eliminate the tiny cracks generated during the baking of the furnace, so that the refractory brick layers are more dense and more solid;

[0019] 2) When the existing technology is used to bake the furnace, the fine and dense small holes of the heating cover refractory lining are easily generated, the present application prolongs the annealing curve to avoid the generation of the fine and dense small holes of the furnace lining during the baking of the furnace, so that the furnace lining is more dense;

[0020] 3) The present application adopts a plurality of shock-absorbing means to eliminate the vibration generated during the lifting of the heating cover;

[0021] 4) The method can effectively increase the service life of the furnace lining of the heating cover, and the service cycle of the heating cover is prolonged from about 24 months to about 48 months. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structural schematic view of the cover furnace.

[0023] Figure 2 is a structural schematic view of the shock-absorbing hanger of the present application.

[0024] Figure 3 This is a conventional oven drying curve diagram for a bell-type furnace.

[0025] Figure 4 This is the furnace drying curve diagram of the bell-type furnace described in this invention.

[0026] In the diagram: 1. Furnace platform 2. Inner cover 3. Heating cover 31. Furnace lining 4. Steel coil 5. Hydrogen nozzle 601. Bottom beam 602. Shock absorber outer cylinder 603. Movable plate 604. Top plate 605. Movable rod 606. Shock absorber spring 607. Bottom plate 608. Bolt 609. Lifting beam 610. Lifting ring Detailed Implementation

[0027] 1. The method for extending the service life of a bell-type furnace heating hood according to the present invention includes taking the following measures:

[0028] 1) Add a shock-absorbing hanger; the shock-absorbing hanger is installed on the top of the heating cover, and a shock absorber is installed in the shock-absorbing hanger to buffer the heating cover when it is lifted;

[0029] 2) Reduce the landing speed of the heating cover; when the heating cover is lifted and lowered, it should first descend at a speed of 25-35 mm / s. When the bottom surface of the heating cover is 0.8-1.2 m from the ground, the speed should be changed to 10-15 mm / s until it lands on the ground.

[0030] 3) Set up sand pits; construct sand pits at the working position of the heating cover and at the placement position after the cover is removed, with each sand pit corresponding to the base of the heating cover.

[0031] 4) After the furnace lining of the heating cover is built, it is cooled and dried at room temperature; after the refractory bricks that make up the furnace lining are built and before the furnace is dried, the heating cover is placed in a closed space at 10-20℃ for more than 30 hours; during the cooling and drying process at room temperature, the furnace lining is pressed and compacted using an extrusion mold.

[0032] 5) Increase the annealing time in the initial temperature section of the oven; in the initial temperature section of the oven, hold the temperature for 33±0.5h when heated to 150±10℃; the time to raise the temperature from 150℃ to 300℃ is 16 to 18 hours.

[0033] Furthermore, the length and width of the landing sand pit are greater than the length and width of the base of the heating cover in the corresponding direction, the depth of the landing sand pit is 400-600mm, and the pit is filled with fine sand.

[0034] Furthermore, such as Figure 2As shown, the shock-absorbing hanger consists of a base beam 601, shock absorbers, a hanging beam 609, and a lifting ring 610; the shock absorbers are in two sets, symmetrically arranged at both ends of the base beam 601 and the hanging beam 609; each shock absorber consists of an outer cylinder 602, a top plate 604, a bottom plate 607, a movable plate 603, a movable rod 605, and a shock-absorbing spring 606; the outer cylinder 602 has a top plate 604 at its top and a bottom plate 607 at its bottom, and the movable plate 603 is located at the bottom of the shock absorber. Inside the outer cylinder 602 of the shock absorber, the lower end of the movable rod 605 is connected to the movable plate 603 by a thread, and the upper end of the movable rod 605 passes through the top plate 604 and is connected to the lifting beam 609; a shock-absorbing spring 606 is provided on the movable rod 605 between the top plate 604 and the movable plate 603; the shock absorber is connected to the bottom beam 601 through the bottom plate 607, and the bottom plate 607 and the bottom beam 601 are connected by multiple bolts 608; the lifting ring 610 is located in the middle of the lifting beam 609.

[0035] Furthermore, the extrusion die consists of several arc-shaped extrusion plates and several sets of support devices; the arc-shaped extrusion plates are closely arranged inside the furnace lining, and the height of the arc-shaped extrusion plates is the same as the height of the furnace lining; two arc-shaped extrusion plates arranged radially opposite each other along the heating hood are supported by corresponding support devices and pressed against the inner walls of the furnace lining on both sides; each set of support devices consists of two arc-shaped support plates, one pressure rod, and two nut sleeves; an arc-shaped support plate is provided on the back of the arc-shaped extrusion plate away from the furnace lining, and the arc-shaped support plate has an arc shape that matches the plate-shaped extrusion plate. The arc-shaped extrusion plate is made of wood, and the arc-shaped support plate is made of steel plate; a connecting rod is provided at one end of the arc-shaped support plate connected to the pressure rod, and the connecting rod is threaded. Both ends of the pressure rod are threaded, and the corresponding ends of the connecting rod and the pressure rod are connected by corresponding nut sleeves; when the nut sleeves are rotated, the arc-shaped support plates on the pressure rod move relative to or away from each other.

[0036] The maintenance cost of furnace linings for heating hoods is very high, with replacements costing approximately 300,000 yuan per cycle. A typical bell-type furnace production area has dozens of operating furnace platforms and dozens of heating hoods, resulting in substantial annual expenses for lining maintenance. The purpose of this invention is to extend the service life of furnace linings for heating hoods and reduce maintenance costs. Considering the following two aspects, multiple measures were adopted, and their comprehensive application yielded significant results.

[0037] 1. Vibration reduction.

[0038] 1. A shock-absorbing hanger is used to reduce vibration when the heating cover is lifted.

[0039] 2. To address the vibration issue when the heating cover lands, a method was adopted to reduce the landing speed of the heating cover.

[0040] 3. Add a landing sandpit, which means building a sandpit at the fixed position where the base of the heating cover will land, to reduce shock when the heating cover lands.

[0041] Second, increase the strength of the furnace lining.

[0042] 1. The refractory brick lining of the heating cover adopts a room temperature cold drying method, which means that after the new refractory bricks are laid and before the furnace is dried, a room temperature cold drying process is added to make the refractory brick lining more solid.

[0043] 2. During the room temperature cold drying process, a certain pressure is applied to the refractory brick masonry layer using an extrusion mold to make the refractory brick masonry layer more solid.

[0044] 3. The new furnace lining needs to be baked before use. This invention adopts the method of extending the initial temperature period of the baking process to prevent the formation of fine pores during the baking process, making the furnace lining denser.

[0045] The following embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0046]

Example

[0047] In this embodiment, the method for extending the service life of the bell-type furnace heating hood is as follows:

[0048] I. Vibration damping hanger, consisting of a base beam, vibration dampers, hanger beams, and hanger rings; the vibration damper comprises an outer cylinder, top plate, bottom plate, movable plate, movable rod, and vibration damping springs. The functions of each part are as follows:

[0049] 1. Bottom beam: The upper part of the bottom beam is connected to two shock absorbers, and the lower part is welded and fixed to the top of the heating cover.

[0050] 2. Shock absorber outer cylinder: It adopts a steel structure, with the top closed by a welded top plate and the bottom closed by a welded bottom plate.

[0051] 3. Movable plate: When the heating cover is lifted, the lifting beam drives the movable plate to slide upward along the outer cylinder of the shock absorber through the movable rod, compressing the spring and playing a shock-absorbing role.

[0052] 4. Movable rod: Used to connect the movable plate and the lifting beam. The lower end of the movable rod is screwed to the movable plate. During lifting, the movable rod drives the movable plate upward to compress the spring.

[0053] 5. Bolts: Used to connect the base plate of the shock absorber to the base beam.

[0054] 6. Lifting beam: The bottom two ends of the lifting beam are connected to two movable rods, and the top middle is connected to a lifting ring. When the beam is lifted, it moves the two movable rods.

[0055] 7. Lifting ring: Located in the middle of the lifting beam, the crane hook and lifting ring are used together when the heating cover is lifted.

[0056] 8. Top plate: Welded and fixed to the outer cylinder of the shock absorber. During the lifting of the heating cover, the top plate bears the upward pressure of the spring.

[0057] 9. Base plate: Welded and fixed to the outer cylinder of the shock absorber, and the base plate is fixed to the bottom beam by bolts.

[0058] 10. Spring: It bears the weight of the heating cover when it is lifted and acts as a buffer.

[0059] II. Reduce the landing speed of the heating cover, the specific process is as follows:

[0060] 1. Use a crane for lifting, and select the landing gear according to the set landing speed of the heating cover.

[0061] 2. By setting the output frequency of the inverter, the descent speed of the crane hoist motor corresponding to the landing gear is preset. In this embodiment, the speed corresponding to the landing gear is set to 12mm / s.

[0062] 3. After the heating cover is lifted, it will descend at a speed of 30mm / s. When the bottom of the heating cover is 1m from the ground, stop descending and press the "landing position" speed selection switch to make the heating cover fall to the ground at a speed of 12mm / s.

[0063] III. Set up a landing sandpit, as detailed below:

[0064] 1. In this embodiment, the heating cover has four feet. When the heating cover is in operation, the four feet have fixed positions. In this embodiment, four sand pits are constructed at the fixed positions of the four feet. Each sand pit is a cube structure with a side length of 500mm. After the pit is constructed, it is filled with fine sand.

[0065] 2. When removing the heating cover after bell-type annealing, the heating cover is lifted off the furnace platform and placed in a designated area. Therefore, four sand pits are also constructed in the area where the heating cover is placed after removal.

[0066] IV. Room temperature cold drying of the furnace lining refractory brick layer;

[0067] In this embodiment, a room temperature cold drying step is added after the new furnace lining is built and before the furnace is dried. The heating cover after the furnace lining is built is placed in a closed space at a temperature of 10-20°C for 30 hours. This step can eliminate the micro-cracks generated in the furnace lining during the furnace drying process.

[0068] V. Extrusion of the refractory brick lining layer in the furnace;

[0069] During the room-temperature cold drying process, six sets of prefabricated extrusion dies are used to extrude the refractory brick lining. The height of the arc-shaped extrusion plates (wooden boards) is the same as the height of the furnace lining. The pressure rod is made of steel pipe, with threads machined at both ends and nut sleeves installed. The arc-shaped extrusion plates are pressed tightly against the inner side of the furnace lining by tightening the nuts. At each end of the pressure rod, there is an arc-shaped support plate (steel plate) with a thickness of 20mm and a length and width of 100mm. First, the length of the support device is adjusted, and the arc-shaped support plates press the arc-shaped extrusion plates into contact with the inner side of the furnace lining. Then, the nut sleeves are tightened five turns along the extension direction, so that the two arc-shaped extrusion plates symmetrically arranged in the same set of extrusion dies press and compact the furnace lining. This ensures that the furnace lining is tight after drying, reducing the penetration of heat energy.

[0070] 6. Revise the furnace drying curve and lengthen the annealing time in the initial temperature range of the furnace drying process.

[0071] Existing oven methods involve heating to 150℃ and holding at that temperature for 13 hours (e.g.) Figure 3 As shown), in this embodiment, the oven is heated to 150°C and then held at that temperature for 33 hours (as shown). Figure 4 As shown). The existing oven method takes 12 hours to heat from 150℃ to 300℃ (e.g.). Figure 3 As shown), in this embodiment, it took 17 hours to raise the oven temperature from 150°C to 300°C (as indicated). Figure 4 As shown). According to the existing oven baking curve (e.g. Figure 3 As shown), many tiny pores will form inside the furnace lining. This embodiment extends the annealing time in the initial temperature section of the furnace (e.g., Figure 4 As shown in the figure, this can eliminate the conditions for the formation of these fine pores and enhance the heat resistance of the furnace lining.

[0072] After adopting the measures described in this embodiment, the service life of the heating cover is extended from 24 months to 48 months.

[0073] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for extending the service life of a bell-type furnace heating hood, characterized in that, This includes taking the following measures: 1) A shock-absorbing hanger is added; the shock-absorbing hanger is located on the top of the heating cover, and a shock absorber is installed in the shock-absorbing hanger to buffer the heating cover during lifting; the shock-absorbing hanger consists of a bottom beam, shock absorbers, a lifting beam, and a lifting ring; there are two sets of shock absorbers, symmetrically arranged at both ends of the bottom beam and the lifting beam; the shock absorber consists of an outer cylinder, a top plate, a bottom plate, a movable plate, a movable rod, and a shock-absorbing spring; the top of the outer cylinder of the shock absorber is provided with a top plate, and the bottom is provided with a bottom plate. The movable plate is located inside the outer cylinder of the shock absorber. The lower end of the movable rod is connected to the movable plate by a thread, and the upper end of the movable rod passes through the top plate and connects to the lifting beam; a shock-absorbing spring is installed on the movable rod between the top plate and the movable plate; the shock absorber is connected to the bottom beam through the bottom plate, and the bottom plate and the bottom beam are connected by multiple bolts; the lifting ring is located in the middle of the lifting beam; 2) Reduce the landing speed of the heating cover; when the heating cover is lifted and lowered, it should first descend at a speed of 25-35 mm / s. When the bottom surface of the heating cover is 0.8-1.2 m from the ground, the speed should be changed to 10-15 mm / s until it lands on the ground. 3) Set up landing sand pits; construct landing sand pits at the working position of the heating cover and at the placement position after the cover is removed, with each landing sand pit corresponding to the bottom foot of the heating cover; the length and width of the landing sand pits are greater than the length and width of the bottom foot of the heating cover in the corresponding direction, the depth of the landing sand pits is 400-600mm, and the pits are filled with fine sand. 4) After the furnace lining of the heating cover is built, it is dried at room temperature; after the refractory bricks that make up the furnace lining are built and before the furnace is dried, the heating cover is placed in a closed space at 10-20℃ for more than 30 hours; during the room temperature drying process, the furnace lining is pressed and compacted using an extrusion mold. 5) Increase the annealing time in the initial temperature section of the oven; in the initial temperature section of the oven, hold the temperature for 33±0.5h when heated to 150±10℃; the time to raise the temperature from 150℃ to 300℃ is 16 to 18 hours.

2. The method for extending the service life of a bell-type furnace heating hood according to claim 1, characterized in that, The extrusion die consists of several arc-shaped extrusion plates and several sets of support devices. The arc-shaped extrusion plates are closely arranged inside the furnace lining, and the height of the arc-shaped extrusion plates is the same as the height of the furnace lining. Two arc-shaped extrusion plates arranged radially opposite each other along the heating hood are supported by corresponding support devices and pressed against the inner walls of the furnace lining on both sides. Each set of support devices consists of two arc-shaped support plates, one pressure rod, and two nut sleeves. An arc-shaped support plate is provided on the back of the arc-shaped extrusion plate away from the furnace lining. The arc-shaped support plate has an arc shape that matches the plate-shaped extrusion plate. The arc-shaped extrusion plate is made of wood, and the arc-shaped support plate is made of steel plate. A connecting rod is provided at one end of the arc-shaped support plate connected to the pressure rod. The connecting rod is threaded, and both ends of the pressure rod are threaded. The corresponding ends of the connecting rod and the pressure rod are connected by corresponding nut sleeves. When the nut sleeve is rotated, the arc-shaped support plate on the pressure rod moves relative to or away from each other.

Images