Constant-temperature preheating device for continuous casting billet

Abstract

The utility model discloses a continuous casting billet constant temperature preheating device which comprises a first heat preservation pit, a second heat preservation pit and a coal gas injection main pipe, the surface of the coal gas injection main pipe is sequentially provided with a coal gas main pipe hand valve, a coal gas blind plate valve and a nitrogen replacement valve from top to bottom, and the surface of the coal gas injection main pipe is communicated with a nitrogen injection pipe. According to the utility model, the first heat preservation pit, the second heat preservation pit, the gas injection main pipe, the gas main pipe hand valve, the gas blind plate valve, the nitrogen replacement valve, the nitrogen injection pipe, the first gas injection branch pipe, the second gas injection branch pipe, the gas branch pipe stop valve, the combustion-supporting air branch pipe, the combustion-supporting air main pipe, the combustion-supporting air injection pipe, the burner and the combustion-supporting air explosion-proof plate are matched; the device can effectively solve the problems of crack defects and internal organizational structures of high-grade wear-resistant billets, achieves excellent mechanical properties and wear resistance, completes preheating work of cold-state casting billets in advance, and realizes high-efficiency and fast-paced production of the heating furnace.

Description

TECHNICAL FIELD

[0001] The utility model relates to continuous casting billet processing technical field, specifically is a kind of continuous casting billet constant temperature preheating device. BACKGROUND

[0002] China's steel material develops rapidly in recent years, product is applied in each field, bridge, high-rise building, wind power, engineering machinery, gas and oil pipeline, external and internal quality is not inferior to foreign imported product, the main equipment of Baotou Steel 4100mm wide plate production line is by converter, LF refining furnace, RH vacuum furnace, arc continuous casting machine, two step type heating furnace, coarse and fine double rack rolling mill, ACC laminar cooling, hot straightening machine, cold bed, head cutting shear, double side shear, sizing shear, heat treatment normalizing, tempering, quenching three heat treatment furnaces, annual capacity 1.4 million tons, variety involves rare earth wear-resistant steel, high-strength steel, wind power steel, rare earth bridge steel, high-rise building steel, product thickness 8mm-120mm, width 1700-3600mm, steel plate is used in large national heavy machine, and is subjected to the test of time with main project;

[0003] Each kind of steel material is designed with special components, steelmaking process, continuous casting process, slab constant temperature dehydrogenation denitrogenation, low-temperature preheating, high-temperature rapid heating process, large compression ratio rolling process and heat treatment process according to special use position, environment and purpose to meet the use requirements of users, especially the wear-resistant steel plate with high strength grade requirement, good impact performance, high surface and core hardness and high flaw detection level, the rare earth and alloy addition amount in molten steel composition is relatively more, the internal and external cracks of continuous casting billet are relatively high in temperature and gas sensitivity, in order to discharge the hydrogen and nitrogen in the internal casting billet, avoid the post-rolling crack on the surface of steel plate, especially the thick steel plate, cannot be directly loaded or hot-loaded for production, needs to be concentrated after offline stacking heat preservation and exhaust, slowly release the internal gas of slab while reducing the surface crack defect caused by large temperature difference between internal and external slab during heating in heating furnace, the initial low-temperature small-gradient slow preheating is required when the casting billet is heated in heating furnace, and then the casting billet can be rapidly heated to target discharge temperature when the internal temperature of the casting billet reaches the plastic interval above 450 DEG C, the preheating process of the casting billet is very important, and will directly affect the internal flaw detection result of finished product;

[0004] According to the search patent number CN209456513U "a preheating type heat preservation pit", a simple fuel pipe nozzle and oxygen pipe nozzle are used to mix and burn two kinds of gas before the forged steel material enters the heat preservation pit, which preheats the heat preservation pit, the fuel combustion efficiency of this technology is low, the heating capacity is small, and the temperature control is not flexible;

[0005] According to the search patent number CN204194739U "continuous casting billet heat preservation pit", a heat preservation pit for conveniently removing the mill scale in the pit is provided, and the technology does not involve heating in the heat preservation pit.

[0006] According to the search patent number CN2858121Y "A Hot Steel Billet Insulation Pit", a conventional hot slab insulation pit is provided. This technology does not involve heating inside the insulation pit.

[0007] For some temperature-sensitive steel grades, slow cooling by stacking in extremely cold winter temperatures is difficult to achieve, let alone slow heat preservation and exhaust. Typically, slabs are stacked in underground slow-cooling pits to minimize the rate of temperature drop. However, this method, lacking an external heat source, cannot control the constant temperature and time at a specific temperature according to different process requirements. It can only minimize heat loss and slow the rate of temperature drop, reducing internal and surface shrinkage stress as much as possible. For rare earth wear-resistant steel and rare earth bridge steel, excessively rapid cooling can still lead to quality problems such as steel plate cracks, non-compliance in flaw detection, and low impact resistance. In severe cases, the slab may break during heating within the furnace, causing major production accidents. For some slabs with long preheating times, this significantly impacts the production efficiency of the heating furnace. Therefore, we propose a continuous casting slab constant-temperature preheating device to solve these problems. Utility Model Content

[0008] The purpose of this utility model is to provide a constant temperature preheating device for continuous casting billets. This device can effectively solve the problems of crack defects and internal microstructure of high-grade wear-resistant steel billets, achieve excellent mechanical properties and wear resistance characteristics, complete the preheating of cold-cast billets in advance, and realize high-efficiency and fast-paced production in heating furnaces.

[0009] To achieve the above objectives, this utility model provides the following technical solution: a constant temperature preheating device for continuously cast billets, comprising a first insulation pit, a second insulation pit, and a main gas injection pipe. From top to bottom, the surface of the main gas injection pipe is sequentially equipped with a main gas pipe hand valve, a gas blind flange valve, and a nitrogen replacement valve. A nitrogen injection pipe is connected to the surface of the main gas injection pipe. The other end of the main gas injection pipe is connected to a first gas injection branch pipe. A second gas injection branch pipe is connected to the surface of the first gas injection branch pipe. A gas branch pipe shut-off valve is provided on the surface of the second gas injection branch pipe. A combustion air branch pipe is connected to the surface of the second gas injection branch pipe. The other end of the combustion air branch pipe is connected to a combustion air main pipe. A combustion air injection pipe is connected to the surface of the combustion air main pipe. Burners are provided on both the left and right sides of the first and second insulation pits. Combustion air explosion-proof plates are provided on the top of both the first and second insulation pits.

[0010] Preferably, the nitrogen injection pipe is positioned on the surface of the main gas injection pipe between the gas blind valve and the nitrogen replacement valve.

[0011] Preferably, the gas injection branch pipe surface is provided with a gas venting valve and a gas main pipe shut-off valve in sequence from the center to both sides.

[0012] Preferably, the surface of the second coal gas injection sub-pipe is connected with a coal gas pressure detector, and the surface of the combustion air sub-pipe is provided with an air pressure detector.

[0013] Preferably, the surface of the combustion air injection pipe is connected with a combustion air pneumatic valve, and the other end of the combustion air injection pipe is connected with a combustion air fan.

[0014] Preferably, the number of the combustion air explosion-proof plates is two, and the two combustion air explosion-proof plates are designed as high-low covers.

[0015] Compared with the prior art, the utility model has the beneficial effects as follows:

[0016] 1. The device can effectively solve the problems of high-grade wear-resistant steel billet crack defects and internal organization structure, achieve excellent mechanical properties and wear resistance, complete the cold-state billet preheating work in advance, and realize high-efficiency fast-paced production of the heating furnace.

[0017] 2. The utility model discloses a heating furnace, which is characterized by comprising a first heat preservation pit and a second heat preservation pit formed by dividing an original large pit, a coal gas injection main pipe, a coal gas total pipe hand valve, a coal gas blind plate valve, a nitrogen replacement valve, a nitrogen injection pipe, a first coal gas injection sub-pipe, a second coal gas injection sub-pipe, a coal gas branch pipe cut-off valve, a combustion air sub-pipe, a combustion air main pipe, a combustion air injection pipe, a burner and a combustion air explosion-proof plate. BRIEF DESCRIPTION OF DRAWINGS

[0018] Fig. 1 It is a structure schematic view of the utility model;

[0019] Fig. 2 It is a structure three-dimensional view of the utility model;

[0020] Fig. 3 It is a structure three-dimensional view of the second coal gas injection sub-pipe of the utility model.

[0021] In the figure: 1, the first holding pit; 2, the second holding pit; 3, the main gas injection pipe; 4, the gas main pipe hand valve; 5, the gas blind plate valve; 6, the nitrogen replacement valve; 7, the nitrogen injection pipe; 8, the first gas injection branch pipe; 9, the second gas injection branch pipe; 10, the gas branch pipe cut-off valve; 11, the combustion air branch pipe; 12, the combustion air main pipe; 13, the combustion air injection pipe; 14, the burner; 15, the combustion air explosion-proof plate; 16, the gas diffuser valve; 17, the gas main pipe cut-off valve; 18, the gas pressure detector; 19, the air pressure detector; 20, the combustion air pneumatic valve; 21, the combustion air fan. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of the utility model.

[0023] Embodiment one:

[0024] Please refer to Figs. 1-3 , in order to realize the purpose of high work efficiency, the following technical scheme is provided, specifically discloses: including the first holding pit 1, the second holding pit 2 and the main gas injection pipe 3, the surface of the main gas injection pipe 3 is sequentially provided with the gas main pipe hand valve 4, the gas blind plate valve 5 and the nitrogen replacement valve 6 from top to bottom, the surface of the main gas injection pipe 3 is communicated with the nitrogen injection pipe 7, the other end of the main gas injection pipe 3 is communicated with the first gas injection branch pipe 8, the surface of the first gas injection branch pipe 8 is communicated with the second gas injection branch pipe 9, the surface of the second gas injection branch pipe 9 is provided with the gas branch pipe cut-off valve 10, the surface of the second gas injection branch pipe 9 is communicated with the combustion air branch pipe 11, the other end of the combustion air branch pipe 11 is communicated with the combustion air main pipe 12, the surface of the combustion air main pipe 12 is communicated with the combustion air injection pipe 13, the left and right sides of the first holding pit 1 and the second holding pit 2 are both provided with the burner 14, and the top of the first holding pit 1 and the second holding pit 2 is both provided with the combustion air explosion-proof plate 15, the device can effectively solve the problems of high-grade wear-resistant steel billet crack defects and internal organization structure, achieve excellent mechanical properties and wear-resistant characteristics, complete the cold-state casting billet preheating work in advance, and realize high-efficiency fast-paced production of the heating furnace.

[0025] Embodiment two:

[0026] Please refer to Figs. 1-3The embodiment is used for realizing the high practicality, and provides the technical scheme, and specifically discloses that the position of the nitrogen injection pipe 7 communicated on the surface of the coal gas injection main pipe 3 is between the coal gas blind plate valve 5 and the nitrogen replacement valve 6, the surface of the coal gas injection branch pipe is sequentially provided with the coal gas diffusion valve 16 and the coal gas main pipe shutoff valve 17 from the center to both sides, the surface of the second coal gas injection branch pipe 9 is connected with the coal gas pressure detector 18 in parallel, the surface of the combustion air branch pipe 11 is provided with the air pressure detector 19, the surface of the combustion air injection pipe 13 is communicated with the combustion air pneumatic valve 20, the other end of the combustion air injection pipe 13 is communicated with the combustion air fan 21, the number of the combustion air explosion-proof plates 15 is two, and the two combustion air explosion-proof plates 15 are designed as high-low covers, the existing heat preservation pit without the heating function is transformed, the pit is divided into the first heat preservation pit 1 and the second heat preservation pit 2 from one big pit, the temperature control is more flexible, the heat preservation in the pit adopts the fiber module material with low thermal conductivity, the high-alumina brick is arranged on the upper layer of the pit bottom, the lightweight heat preservation brick is arranged on the lower layer, the fiber module is built around the pit wall, the high-low cover adopts the fiber module hung, the fiber plate is arranged between the track and the roller moving part, the asbestos cloth is arranged at the intersection of the high-low covers, two pairs of burners 14 are added on the length direction of the bottoms of the two pits, the heating capacity, the pipe diameter and the power of the combustion air fan 21 are based on the maximum heat compensation in the slab temperature drop process, the fuel is led out from the heating furnace coal gas main pipe, the coal gas main pipe hand valve 4, the coal gas blind plate valve 5, the nitrogen replacement valve 6, the coal gas diffusion valve 16, the combustion air explosion-proof plate 15, the coal gas main pipe shutoff valve 17, the coal gas branch pipe shutoff valve 10, the coal gas pressure detector 18, the coal gas low-pressure alarm interlocking shutoff, compressed air driving, the burner 14 adopts the automatic pulse switching control of large and small fires, the temperature curve setting is automatically controlled, and the operation personnel does not need to be added.

[0027] In use, the heat preservation pit is provided with two pits, which are respectively a first heat preservation pit 1 and a second heat preservation pit 2, and each heat preservation pit can place three stacks of slabs. The support around the pit body is mainly a steel plate framework, and the inner side of the steel plate is lined with refractory fiber modules. Four table pulse high-speed burners 14 are respectively installed on the east and west sides of the bottom of the first heat preservation pit 1 and the second heat preservation pit 2, and ignition guns, flame monitors, ignition control units, two independent combustion air fans 21, combustion air pneumatic valves 20, air pipelines, and explosion-proof membranes, gas pipelines, and diffusion systems, gas shut-off valves, gas shut-off valves, gas blind plate valves 5, nitrogen replacement valves 6, low-pressure detection and alarm interlocking cut-off functions, etc. The whole heating system is automatically controlled in the DCS system. The fuel is the same mixed gas as the heating furnace. In order to ensure the safety of the work below the heat preservation pit, a fixed gas alarm is specially set, a top ventilation system, a pit lighting system, and the signal of the gas alarm is introduced into the manned duty room. The upper part of the heat preservation pit is provided with a high cover and a bottom cover to cover the slabs in the pit. When the high cover of the first heat preservation pit 1 is opened, it passes from above the low cover of the second heat preservation pit 2. When the low cover of the second heat preservation pit 2 is opened, it passes from below the high cover of the first heat preservation pit 1. When the first heat preservation pit 1 and the second heat preservation pit 2 are closed, the high cover and the low cover are parked side by side. The high cover and the low cover move on the track. The power source is two motors and a speed reducer. The high and low cover switch is controlled by the forward and reverse rotation of the motor. A compression wheel device is set to protect the high and low cover from exceeding the working stroke. An electrical command controller protection device is set. When the high and low cover is fully open or fully closed, the electrical switch is automatically cut off for interlocking protection. The operator receives the production plan of the slabs into the heat preservation pit for heating, opens the heat preservation pit ventilator and the pit bottom lighting, sends power and starts the combustion air fan 21, opens the gas diffusion and nitrogen, and replaces the air in the gas pipeline after the nitrogen is closed and the gas blind plate is opened. The gas pipeline is qualified. The nitrogen is closed and the gas blind plate is opened. The gas is sent to replace the nitrogen. After the explosion test is qualified, the diffusion is closed. The gas concentration in the pit is detected. The personnel evacuate below the heat preservation pit. The operator starts the ignition program on the screen. After confirming that the burner 14 is ignited, the high and low cover is closed to preheat the heat preservation pit to the highest furnace temperature. Then the high and low cover is opened to the middle position. The crane is commanded to load the special slabs that need to be heated and preserved into the two pits. After the pit is filled with slabs, the high and low cover is closed. The heat preservation curve is set: heating time, heating speed, target temperature, heat preservation time, cooling speed, and heat preservation completion. After the heat preservation is completed, the burner 14 pneumatic valve is automatically closed, the gas section valve is cut off, and the operator is prompted to prepare for the hoisting of the slabs in the pit. The on-off and size of the air and gas are adjusted, the ignition and extinguishing protection of the burner 14 is automatically controlled by the touch screen (and each burner 14 can be independently controlled). The furnace temperature and flow can be monitored and adjusted in time through various instruments. When a certain burner 14 is extinguished, the flame monitor will issue an alarm and immediately automatically close the gas quick cut valve in front of the burner 14. If the stable combustion cannot be restored after three resets, the operator will manually close the gas large and small fire manual ball valves in front of the burner 14, analyze and judge the cause of the extinguishing, and take appropriate measures.The device can effectively solve the problems of crack defects and internal structure of high-grade wear-resistant steel billets, achieve excellent mechanical properties and wear-resistant characteristics, complete the cold billet preheating work in advance, and realize high-efficiency fast-paced production of the heating furnace.

[0028] In the description of the present patent, it needs to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present patent and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present patent. In the description of the present patent, it needs to be explained that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "setting" should be understood broadly, for example, it can be fixedly connected, set, or can be detachably connected, set, or integrally connected, set. For those skilled in the art, the specific meaning of the above terms in the present patent can be understood according to the specific circumstances.

[0029] Although the embodiments of the present utility model have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the present utility model, and the scope of the present utility model is defined by the appended claims and their equivalents.

Claims

1. A constant temperature preheating device for continuous casting billets, comprising a first holding pit (1), a second holding pit (2) and a main gas injection pipe (3), characterized in that: The surface of the coal gas injection main pipe (3) is sequentially provided from top to bottom with a coal gas main pipe hand valve (4), a coal gas blind plate valve (5) and a nitrogen replacement valve (6), the surface of the coal gas injection main pipe (3) is communicated with a nitrogen injection pipe (7), the other end of the coal gas injection main pipe (3) is communicated with a first coal gas injection branch pipe (8), the surface of the first coal gas injection branch pipe (8) is communicated with a second coal gas injection branch pipe (9), the surface of the second coal gas injection branch pipe (9) is provided with a coal gas branch pipe cut-off valve (10), the surface of the second coal gas injection branch pipe (9) is communicated with a combustion air branch pipe (11), the other end of the combustion air branch pipe (11) is communicated with a combustion air main pipe (12), the surface of the combustion air main pipe (12) is communicated with a combustion air injection pipe (13), the left and right sides of the first heat preservation pit (1) and the second heat preservation pit (2) are both provided with a burner (14), and the top of the first heat preservation pit (1) and the second heat preservation pit (2) is both provided with a combustion air explosion-proof plate (15).

2. A constant temperature preheating device for continuous casting billets according to claim 1, characterized in that: The nitrogen injection pipe (7) is communicated with the surface of the coal gas injection main pipe (3) between the coal gas blind plate valve (5) and the nitrogen replacement valve (6).

3. A constant temperature preheating device for continuous casting billets according to claim 1, characterized in that: The surface of the coal gas injection branch pipe is sequentially provided from the center to both sides with a coal gas diffusion valve (16) and a coal gas main pipe cut-off valve (17).

4. A constant temperature preheating device for continuous casting billets according to claim 1, characterized in that: The surface of the second coal gas injection branch pipe (9) is connected in parallel with a coal gas pressure detector (18), and the surface of the combustion air branch pipe (11) is provided with an air pressure detector (19).

5. A constant temperature preheating device for continuous casting billets according to claim 1, characterized in that: The surface of the combustion air injection pipe (13) is communicated with a combustion air pneumatic valve (20), and the other end of the combustion air injection pipe (13) is communicated with a combustion air fan (21).

6. A constant temperature preheating device for continuous casting billets according to claim 1, characterized in that: The number of the combustion air explosion-proof plates (15) is two, and the two combustion air explosion-proof plates (15) are designed as high-low covers.

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