Efficient cover type annealing furnace

Abstract

The embodiment of the utility model provides a high-efficiency bell-type annealing furnace which is characterized in that a split-type coil base diffuser for bearing the weight of a steel coil and shunting atmosphere is coaxially arranged above a coil base, and the outer side of the coil base diffuser is connected with an annular guide plate; a coil base air inlet and a coil base air outlet are formed in the top surface of the coil base base, the coil base air inlet and the coil base air outlet are both located on the outer side of the coil base diffuser, the upper portion of the coil base air inlet is further connected with a vertically-through air inlet flow guide pipe, and the air inlet flow guide pipe penetrates through the flow guide plate from bottom to top. After the technical scheme is adopted, the flow rate of protective gas entering the furnace is greatly increased, and the range is increased, so that the penetration depth of jet flow in a main stream is increased, the effective utilization rate of hydrogen entering the furnace for production in a hot purging process section is facilitated, nitrogen entering the furnace in a post-purging process section is also facilitated, and hydrogen replacement is more thorough and complete; the surface quality of the strip steel is further improved; the annealing production period is shortened; and quality improvement and efficiency improvement are realized.

Description

Technical Field

[0001] This utility model relates to the field of steel production technology, and in particular to a high-efficiency bell-type annealing furnace. Background Technology

[0002] Bell-type annealing furnaces are a type of equipment used for high-quality bright annealing of cold-rolled products (including all-hydrogen bell-type annealing furnaces and other similar types). The furnace uses strongly convective circulating pure hydrogen as the protective gas for the annealing process, allowing the rolled steel coils to undergo recrystallization annealing under this protective atmosphere. This eliminates the rolling stress formed during rolling, improves the stamping performance of the steel coils, and compared to ordinary bell-type furnaces, it offers advantages such as higher production capacity, more uniform mechanical properties of annealed strips, higher surface cleanliness, and greater safety and reliability, significantly improving the quality of annealed products.

[0003] In the process of realizing this utility model, the inventors discovered that the prior art has at least the following problems:

[0004] Existing bell-type annealing furnaces still suffer from low protective gas utilization and high energy consumption. Therefore, how to further reduce energy consumption and production costs of bell-type annealing furnaces is a problem that needs to be solved. Utility Model Content

[0005] This utility model provides a bell-type annealing furnace, particularly an all-hydrogen bell-type annealing furnace, and more specifically, an efficient all-hydrogen bell-type annealing furnace, to improve the effective utilization rate of protective gas, reduce the energy consumption of the bell-type annealing furnace, improve quality and efficiency, shorten the annealing cycle, and reduce production costs.

[0006] To achieve the above objectives, this utility model provides a high-efficiency bell-type annealing furnace. A furnace diffuser for supporting the weight of the steel coil and guiding the atmosphere is coaxially arranged above the furnace base. The outer diameter of the furnace diffuser is smaller than the outer diameter of the furnace base. An annular guide plate is fixedly connected to the middle of the outer side of the furnace diffuser. The guide plate has an open cylindrical structure with a larger top and a smaller bottom. The diameter of the top edge of the guide plate is larger than the diameter of the bottom edge of the guide plate. A furnace inlet and a furnace outlet are provided on the top surface of the furnace base. Both the furnace inlet and the furnace outlet are located outside the furnace diffuser. An air inlet guide pipe that runs vertically through the furnace inlet is also connected above the furnace inlet, and the air inlet guide pipe runs through the guide plate from bottom to top.

[0007] Furthermore, the top opening of the air intake guide pipe is 2-3 cm lower than the top surface of the furnace diffuser.

[0008] Furthermore, the intake manifold includes a straight pipe at the top and a reducer pipe fixedly connected to the bottom of the straight pipe.

[0009] Furthermore, the small end of the reducer is fixedly connected to the bottom end of the straight pipe, and the large end of the reducer is fixedly connected to the air inlet of the furnace platform.

[0010] Furthermore, the inner diameter of the reducer at the bottom opening is 70mm, and the inner diameter at the top opening is 50mm.

[0011] Furthermore, the height of the intake manifold is 250mm, and the height of the reducer is 89mm.

[0012] Furthermore, the furnace platform air inlet and outlet are symmetrically distributed along the axis of the furnace platform diffuser.

[0013] The above technical solution has the following beneficial effects:

[0014] The technical solution of this utility model improves the air inlet pipe of the furnace platform equipment by adding an air inlet guide pipe above the original air inlet of the furnace platform, which is equivalent to extending the air inlet pipe of the furnace platform to the top of the guide plate. This allows the protective gas to be guided to the top of the furnace platform during air intake and participate in the atmosphere of the large production cycle, effectively improving the effective utilization rate of the protective gas and reducing production costs.

[0015] In addition, this technical solution also has the following characteristics:

[0016] 1) The newly added inlet guide pipe adopts the working principle of jet diameter change, which greatly increases the flow rate of the protective gas, increases the range of the protective gas, and increases the penetration depth of the jet in the mainstream. This is conducive to hydrogen entering the furnace and participating in the high-temperature atmosphere during production, improving the surface quality of the strip steel and accelerating the cooling rate during the cooling stage. At the same time, it is conducive to nitrogen replacing hydrogen purging in the inner shroud without leaving dead corners, further shortening the annealing production cycle, reducing energy consumption, and increasing unit output. In addition, it also improves the safety of nitrogen replacing hydrogen purging in the early stage of tapping.

[0017] 2) Existing technologies suffer from poor surface cleanliness and brightness of finished steel coils due to the low effective utilization rate of hydrogen in the protective gas. By adopting this technical solution, the effective utilization rate of hydrogen is greatly improved, which also helps to improve the surface cleanliness and brightness of the steel coils. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a high-efficiency bell-type annealing furnace according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the structure of the air intake guide pipe in an embodiment of this utility model;

[0021] Reference numerals: 1. Furnace base; 2. Furnace diffuser; 3. Guide plate; 4. Furnace air inlet; 5. Furnace air outlet; 6. Air inlet guide pipe; 61. Straight pipe; 62. Reducer pipe. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] like Figure 1 As shown, this embodiment of the utility model provides a high-efficiency bell-type annealing furnace. A furnace diffuser 2 is coaxially arranged above the furnace base 1 (the furnace base 1 contains several supporting columns and fireproof and heat-insulating materials such as ceramic fiber, and has an external annular protective cover to protect the ceramic fiber; in fact, the furnace diffuser 2 is supported by the supporting columns). The outer diameter of the furnace diffuser 2 is smaller than the outer diameter of the furnace base 1. An annular guide plate 3 is fixedly connected to the middle of the outer side of the furnace diffuser 2. 3 is an open cylindrical structure with a larger top and a smaller bottom. The diameter of the top edge of the guide plate 3 is larger than the diameter of the bottom edge of the guide plate 3. The top surface of the furnace base 1 is provided with a furnace inlet 4 and a furnace outlet 5. Both the furnace inlet 4 and the furnace outlet 5 are located outside the furnace diffuser 2. An air inlet guide pipe 6 that runs vertically through the furnace inlet 4 is also connected above the furnace inlet 4. The air inlet guide pipe 6 runs through the guide plate 3 from bottom to top. That is, the top opening of the air inlet guide pipe 6 is located above the guide plate 3.

[0024] According to the inventor's research and analysis, the main reason for the long annealing production cycle and high energy consumption of existing bell-type annealing furnaces is that: in existing bell-type annealing furnaces, the furnace inlet 4 and furnace outlet 5 are positioned at the same height and facing each other (for example, on the east and west sides of the furnace platform) below the guide plate 3. When the protective gas (hydrogen / nitrogen) enters the furnace, because the strong convection of the furnace platform circulating fan circulates above the furnace platform diffuser 2 and guide plate 3, part of the newly entered hydrogen is guided by the strong convection atmosphere of the furnace platform circulating fan to participate in the working cycle inside the furnace, while another part of the newly entered protective gas is directly short-circuited and discharged by the furnace outlet 5 (i.e., this part of the gas...). Since the gas cannot enter and reach the top of the guide plate 3, it cannot participate in the working cycle inside the furnace. According to the principle of gas flow ejection, when the circulating fan in the sealed container circulates the airflow by stirring the impeller, under the set pressure balance state, the air intake volume Q1 = the exhaust volume Q2. When the air intake pipe diameter D1 = the exhaust pipe diameter D2 in the sealed container, the airflow ejection force between the guide circulation atmosphere and the outlet discharge is almost equal. Therefore, about 50% of the protective gas fails to participate in the production atmosphere and is directly discharged from the furnace outlet 5. This results in a relatively low utilization rate of the protective gas, energy waste, and restricts the quality and output of the annealing process.

[0025] In an example of an existing product, the hydrogen inlet pipe of the furnace valve station is generally DN40, with an inlet pressure of 5-6 kPa and a flow rate of 20-30 m³ / h. 3 / h; The nitrogen inlet pipeline of the furnace valve station is DN65, with an inlet pressure of 6-8 kPa and a flow rate of 100-140 m³ / h. 3 / h, while the protective gas inlet pipeline consists of two media pipelines connected in parallel. The diameter of the pipeline entering the furnace platform is DN65. During the production process, driven by the high-speed circulating fan inside the furnace, some of the protective gas fails to participate in the large-circulation furnace atmosphere during production gas delivery and is directly discharged from the exhaust port. The effect of entering the furnace to participate in the production atmosphere circulation is not good.

[0026] Therefore, this technical solution improves the bell-type annealing furnace by utilizing the working principle of jet diameter change and designing an inlet guide pipe. An inlet guide pipe 6 is connected to the original furnace inlet 4 (the two can also form an integrated structure). The top opening of the inlet guide pipe 6 is located above the guide plate 3, which facilitates the direct flow of protective gas to the top of the guide plate 3 during intake, allowing it to participate in the atmosphere of the large production cycle. This minimizes the influence of the protective gas on the vortex zone formed by the inner wall and the bottom of the guide plate 3, and reduces the circumferential circulation flow of the protective gas from the furnace diffuser 2 to the bottom of the furnace before it is discharged from the furnace outlet 5, thereby improving the effective utilization rate of the protective gas entering the furnace.

[0027] Furthermore, since a load-bearing plate needs to be laid on the top surface of the furnace diffuser 2 during construction, a better implementation method is to make the top opening of the air intake guide pipe 6 2-3cm lower than the top surface of the furnace diffuser 2 to avoid obstruction of air intake.

[0028] Furthermore, such as Figure 1 ,like Figure 2 As shown, the air intake guide pipe 6 is preferably a straight structure. The air intake guide pipe 6 includes a straight pipe 61 at the top and a reducing pipe 62 fixedly connected to the bottom of the straight pipe 61. The reducing pipe 62 has a structure that is smaller at the top and larger at the bottom. The small end of the reducing pipe 62 is fixedly connected to the bottom end of the straight pipe 61, and the large end of the reducing pipe 62 is fixedly connected to the furnace platform air inlet 4. Since the guide plate 3 extends obliquely upwards and outwards from the outside of the furnace platform diffuser 2 and blocks the furnace platform air inlet 4, holes or notches can be made in the guide plate 3 (for example, by using A422 ordinary welding rods and hot-melting the guide plate 3 through the holes by electric welding). Then, the air intake guide pipe 6 passes through the guide plate 3 from bottom to top. By designing the inlet guide pipe 6 in this way, based on the working principle of jet diameter variation, the flow rate of the protective gas can be significantly increased, the range of the protective gas can be increased, and the penetration depth of the jet in the mainstream can be improved. This is conducive to hydrogen entering the furnace and participating in the high-temperature atmosphere during production, improving the surface quality of the strip steel and accelerating the cooling rate of the cooling stage. At the same time, it is beneficial to ensure that nitrogen does not leave dead corners when replacing the inner shroud with hydrogen purging, and further shortens the annealing production cycle, reduces energy consumption, and increases the unit output.

[0029] Furthermore, the inner diameter of the bottom opening of the reducer 62 is 70mm, and the inner diameter of the top opening of the reducer 62 is 50mm. The original design of the furnace inlet 4 was a φ76×3mm stainless steel pipe; therefore, the inner diameter of the bottom opening of the reducer 62 remains 70mm. After consulting the *Chemical Pipeline Design Manual* and performing calculations, based on a flow rate of 140m³ / h... 3 Based on the calculation, the flow velocity is approximately 10.1 m / s. After modifying the pipe outlet diameter to φ50 (φ57×3.5) by changing the diameter, the flow velocity can be increased to 19.8 m / s. The increase in gas supply resistance is less than 200 Pa, and the impact on the flow rate is negligible. At the same flow rate, the outlet flow velocity is approximately 19.8 m / s, which is almost double the flow velocity. This is consistent with the principle of typical jet flow, and better results can be achieved at this time.

[0030] Furthermore, based on the above results, the intake guide pipe 6 is designed in detail. The total height of the intake guide pipe 6 is 250mm, and the height of the reducer pipe 62 is 89mm. In practical applications, it can be formed by welding a 304 stainless steel concentric reducer pipe φ76×φ57×3.0mm with a 304 stainless steel straight pipe.

[0031] Furthermore, following existing technology, the furnace platform air inlet 4 and the furnace platform air outlet 5 are symmetrically distributed along the axis of the furnace platform diffuser 2, that is, the circumferential angle between the two is 180°.

[0032] In a specific embodiment using the above-mentioned improved method, the parameters for nitrogen purging and hydrogen replacement in the furnace before tapping are shortened from the original 35 minutes to 20 minutes, effectively shortening the annealing cycle and increasing furnace output.

[0033] In the above detailed description, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features in a single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, with each claim representing a separate preferred embodiment of the invention.

[0034] The disclosed embodiments have been described above to enable any person skilled in the art to implement or use this invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not limited to the embodiments given herein, but is consistent with the widest scope of the principles and novel features disclosed in this application.

[0035] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A high-efficiency bell-type annealing furnace, characterized in that, A furnace diffuser (2) is coaxially arranged above the furnace base (1). The outer diameter of the furnace diffuser (2) is smaller than the outer diameter of the furnace base (1). An annular guide plate (3) is fixedly connected to the outside of the furnace diffuser (2). The guide plate (3) is an open cylindrical structure with a larger top and a smaller bottom. The diameter of the top edge of the guide plate (3) is larger than the diameter of the bottom edge of the guide plate (3). A furnace inlet (4) and a furnace outlet (5) are arranged on the top surface of the furnace base (1). The furnace inlet (4) and the furnace outlet (5) are both located outside the furnace diffuser (2). An air inlet guide pipe (6) that runs vertically through the furnace inlet (4) is also connected above the furnace inlet (4). The air inlet guide pipe (6) runs through the guide plate (3) from bottom to top.

2. The high-efficiency bell-type annealing furnace as described in claim 1, characterized in that, The top opening of the air inlet guide pipe (6) is 2-3 cm lower than the top surface of the furnace diffuser (2).

3. The high-efficiency bell-type annealing furnace as described in claim 1, characterized in that, The air intake guide pipe (6) includes an upper straight pipe (61) and a reducing pipe (62) fixedly connected to the lower part of the straight pipe (61).

4. The high-efficiency bell-type annealing furnace as described in claim 3, characterized in that, The small end of the reducing pipe (62) is fixedly connected to the bottom end of the straight pipe (61), and the large end of the reducing pipe (62) is fixedly connected to the furnace inlet (4).

5. The high-efficiency bell-type annealing furnace as described in claim 4, characterized in that, The inner diameter of the bottom opening of the reducing pipe (62) is 70 mm, and the inner diameter of the top opening of the reducing pipe (62) is 50 mm.

6. The high-efficiency bell-type annealing furnace as described in claim 5, characterized in that, The height of the air intake guide pipe (6) is 250 mm, and the height of the variable diameter pipe (62) is 89 mm.

7. The high-efficiency bell-type annealing furnace as described in claim 1, characterized in that, The furnace inlet (4) and the furnace outlet (5) are symmetrically distributed along the axis of the furnace diffuser (2).

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