A system for rapid heating of a strip

Abstract

The application discloses a system for realizing quick heating of strip steel and relates to the technical field of industrial furnaces, which is characterized in that the system comprises oppositely arranged furnace linings, high-temperature fans and a plurality of gas pipelines; jet flow air boxes are oppositely arranged between the furnace linings; the adjacent surfaces of the oppositely arranged jet flow air boxes are each provided with a jet flow nozzle and a heating device; the surfaces away from each other of the oppositely arranged jet flow air boxes are each provided with a circulating gas inlet; the furnace linings are provided with a circulating gas outlet; and the high-temperature fans are connected with the circulating gas inlets and the circulating gas outlet through the gas pipelines. The system improves the convective heat transfer coefficient between the strip steel in the furnace and the protective gas, strengthens the heating rate of the strip steel in the strip steel continuous annealing unit, reduces the size of the furnace, and improves the production efficiency of the furnace.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial furnace, more particularly, it relates to a system for realizing rapid heating of strip steel. BACKGROUND

[0002] In a strip steel continuous annealing unit and a strip steel continuous hot-dip plating (zinc plating, aluminum-zinc plating, etc.) unit, the heating and temperature rising of the strip steel mainly rely on radiation tube heating, direct flame jet heating, open flame heating, etc. The units for producing home appliance plates and automobile plates have strict requirements on the surface quality of the strip steel. Considering that the annealing furnace is filled with protective gas, the radiation tube heating mode is mostly adopted, and jet impact preheating (heating the strip steel to about 300 DEG C) can also be combined with the protective gas. In the radiation tube heating furnace, heat is exchanged between the strip steel and the radiation tube through thermal radiation. Since the emissivity of the strip steel is low (the emissivity of stainless steel bright plate is generally less than 0.1, and the emissivity of common carbon steel is usually not higher than 0.2), the space required for the temperature rising of the strip steel is very large, thus resulting in low heating efficiency. SUMMARY

[0003] The purpose of the present application is to provide a system for realizing rapid heating of strip steel, to improve the convective heat transfer coefficient between the strip steel and the protective gas in the furnace, to improve the heating rate of the strip steel in the strip steel continuous annealing unit, to improve the production efficiency of the furnace and the unit, and to reduce the size of the strip steel continuous annealing furnace.

[0004] The above technical purpose of the present application is achieved by the following technical scheme: a system for realizing rapid heating of strip steel, comprising oppositely arranged furnace linings, a high-temperature fan and a plurality of gas pipelines; jet blast boxes are oppositely arranged between the furnace linings; adjacent surfaces of the oppositely arranged jet blast boxes are each provided with a jet nozzle and a heating device; and the surfaces away from each other of the oppositely arranged jet blast boxes are each provided with a circulating gas inlet; a circulating gas outlet is arranged on the furnace lining; and the high-temperature fan is connected with the circulating gas inlets and outlets through the gas pipelines.

[0005] The present application is further provided as follows: it further comprises a heat accumulator A, a heat accumulator B, a four-way reversing valve A and a four-way reversing valve B; the high-temperature fan is connected with the four-way reversing valve A through the gas pipelines; the four-way reversing valve A is connected with the heat accumulator A and the heat accumulator B through the gas pipelines; and the four-way reversing valve B is connected with the circulating gas outlet, the circulating gas inlet, the heat accumulator A and the heat accumulator B through the gas pipelines.

[0006] The present application is further provided as follows: the adjacent surfaces of the oppositely arranged jet blast boxes adopt a concave-convex structure connected with each other; the heating device is arranged in the concave part; and the jet nozzle is arranged in the convex part.

[0007] The heating device is an electric resistance belt or a radiation tube, and the radiation tube is an electric radiation tube or a gas radiation tube.

[0008] The jet nozzle is a slit nozzle or a circular nozzle.

[0009] The surface of the jet fan and the surface of the heating device are both sprayed with a high-emissivity coating.

[0010] In summary, the present application has the following advantages:

[0011] (1) The high-temperature protective gas circulation jet in the furnace enhances the convective heat exchange between the protective gas and the strip steel, and improves the heating rate of the strip steel.

[0012] (2) The strong stirring action of the circulating protective gas makes the temperature in the furnace uniform, and improves the temperature uniformity in the width direction of the strip steel.

[0013] (3) By spraying a high-emissivity coating on the jet fan and the heating device, the radiation heat transfer intensity to the strip steel is enhanced.

[0014] (4) After setting the four-way reversing valve and the heat accumulator on the protective gas circulation pipeline, the gas temperature entering the high-temperature fan is reduced, effectively protecting the high-temperature fan. The heat storage and release of the heat accumulator make the heat of the protective gas as much as possible not to be lost, improving the thermal efficiency of the furnace.

[0015] (5) The system can be installed in the heating section of the strip steel continuous annealing furnace unit, or in the soaking section and the holding section, which stabilizes the temperature of the strip steel. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a schematic diagram of a strip steel rapid heating system in a low-temperature furnace zone in an embodiment of the present application;

[0017] Figure 2 is a schematic diagram of a strip steel rapid heating system in a high-temperature furnace zone in an embodiment of the present application (electric resistance belt, four-way reversing valve valve position I state);

[0018] Figure 3 is a schematic diagram of a strip steel rapid heating system in a high-temperature furnace zone in an embodiment of the present application (electric resistance belt, four-way reversing valve valve position II state);

[0019] Figure 4 is a schematic diagram of a strip steel rapid heating system in a high-temperature furnace zone in an embodiment of the present application (radiation tube, four-way reversing valve valve position I state);

[0020] Figure 5This is a schematic diagram of the rapid heating system for strip steel in the high-temperature furnace zone (radiant tube, four-way reversing valve in position II state) in an embodiment of the present invention.

[0021] In the diagram: 1. Furnace lining; 2. Jet box; 3. Resistance band; 4. Jet nozzle; 5. Strip steel; 6. Strip steel travel channel; 7. Circulating gas outlet; 8. Circulating gas inlet; 9. Circulating gas; 10. High-temperature fan; 11. Gas pipeline; 12. Heat storage body A; 13. Heat storage body B; 14. Four-way reversing valve A; 15. Four-way reversing valve B; 16. Radiant tube. Detailed Implementation

[0022] The following is in conjunction with the appendix Figures 1-5 The present invention will be described in further detail below.

[0023] Example 1: A system for rapid heating of strip steel, such as Figure 1 As shown, the furnace includes a furnace lining 1, a high-temperature blower 10, and several gas pipes 11 arranged opposite each other. Jet boxes 2 are positioned opposite each other between the furnace linings 1. Adjacent surfaces of the opposite jet boxes 2 are equipped with jet nozzles 4 and heating devices, while the opposing surfaces of the opposite jet boxes 2 are equipped with circulating gas inlets 8. Circulating gas outlets 7 are provided on the furnace lining 1. The high-temperature blower 10 is connected to the circulating gas inlets 8 and outlets 7 via gas pipes 11. The adjacent surfaces of the opposite jet boxes 2 adopt an interconnected concave-convex structure, with the heating device located in the concave area and the jet nozzles 4 located in the convex area. The heating device is a resistance band 3 or a radiant tube 16, which can be an electric radiant tube 16 or a gas radiant tube 16. The jet nozzles 4 are slit nozzles or circular nozzles. The surfaces of the jet boxes 2 where the heating devices are installed and the surfaces of the heating devices are coated with a high-emissivity coating. A strip steel travel channel 6 is located between the opposite jet boxes 2.

[0024] The concave-convex structure is used on the side of the jet air box 2 facing the strip steel 5. The concave part forms a space for installing the heating device (resistance strip 3 or radiation tube 16), which is beneficial to jet exhaust. The convex part is processed to form the jet nozzle 4 (slit nozzle or circular nozzle), which helps to form a jet of the protective gas and to improve the heat transfer intensity by impacting the strip steel 5. The surface of the jet air box 2 (the side facing the strip steel 5) and the surface of the heating device are sprayed with a high-emissivity coating to improve the radiation heat transfer intensity in the furnace. The strip steel 5 is heated while passing between the oppositely arranged jet air boxes 2. The strip steel 5 is installed with jet air boxes 2 and heating devices on both sides, forming a symmetrical heating form. The circulating gas inlet 8 is arranged on the back (the side facing away from the strip steel 5) or the side of the jet air box 2, and the circulating gas outlet 7 is arranged on the furnace lining 1. The high-temperature protective gas in the furnace is extracted from the circulating gas outlet 7 by the high-temperature fan 10, and after being pressurized, it is blown into the jet air box 2, and then it is sprayed and impacts the strip steel 5 at the jet nozzle 4, forming high-intensity convective heat transfer to the strip steel 5, and then it is dispersed in the furnace, forming strong stirring action to the gas in the furnace, and at the same time, it performs convective heat transfer with the heating device in the furnace, making the temperature in the furnace uniform. The protective gas in the furnace circulates under the action of the high-temperature fan 10, achieving the effect of strengthening heat transfer.

[0025] Example two: a system for rapidly heating the strip steel 5, as shown in Figures 2-5 The system further includes a heat accumulator A 12, a heat accumulator B 13, a four-way reversing valve A 14, and a four-way reversing valve B 15. The high-temperature fan 10 is connected to the four-way reversing valve A 14 through the gas pipeline 11. The four-way reversing valve A 14 is connected to the heat accumulator A 12 and the heat accumulator B 13 through the gas pipeline 11. The four-way reversing valve B 15 is connected to the circulating gas outlet 7, the circulating gas inlet 8, the heat accumulator A 12, and the heat accumulator B 13 through the gas pipeline 11. The heat accumulator A 12 and the heat accumulator B 13 can be small ball heat accumulators or honeycomb heat accumulators.

[0026] The concave-convex structure is used on the side of the strip steel 5 facing the jet air box 2. The concave part forms a space for installing the heating device (resistance strip 3 or radiation tube 16), which is conducive to jet exhaust. The convex part is processed into a jet nozzle 4 (slit nozzle or circular nozzle), which helps to form a jet of protective gas and improve the convective heat transfer intensity by impacting the strip steel 5. The strip steel 5 is heated and passes between the oppositely arranged jet air boxes 2. The strip steel 5 is installed with jet air boxes 2 and heating devices on both sides, forming a symmetrical heating form. The circulating gas inlet 8 is arranged on the back (the side facing away from the strip steel 5) or side of the jet air box 2, and the circulating gas outlet 7 is arranged on the furnace lining 1. The high-temperature fan 10 draws the high-temperature protective gas in the furnace from the circulating gas outlet 7. The high-temperature protective gas flows through the four-way valve B15, flows into the heat accumulator A12, and exchanges heat with the heat accumulator A12. The temperature of the heat accumulator A12 rises, and the temperature of the high-temperature protective gas decreases. The high-temperature protective gas flowing out of the heat accumulator A12 flows into the four-way valve A14, and then flows into the suction end of the high-temperature fan 10. After being pressurized by the high-temperature fan 10, the high-temperature protective gas flows into the four-way valve A14, flows into the heat accumulator B13, and exchanges heat with the heat accumulator B13. The temperature of the heat accumulator B13 decreases, and the temperature of the protective gas increases. The protective gas flows through the four-way valve B15 and is blown into the jet air box 2. Then, the protective gas is sprayed and impacted on the strip steel 5 at the jet nozzle 4, forming high-intensity convective heat transfer on the strip steel 5. Then, the protective gas is dispersed in the furnace and forms a strong stirring effect on the gas in the furnace, while exchanging heat with the heating device in the furnace by convection, so that the temperature in the furnace is uniform. The protective gas in the furnace circulates under the action of the high-temperature fan 10, achieving the effect of strengthening heat exchange, as shown in Figure 2 and Figure 4 .

[0027] The four-way valve A14 and the four-way valve B15 need to be quickly switched to change the direction of the gas flow after a certain period (such as 60s, 120s, etc.). As shown in Figure 3 and Figure 5 , the four-way valve is in state II, and the direction of the gas flow is changed to Figure 2 and Figure 4, the gas flow after the valve position is changed is as follows: the high-temperature protective gas in the furnace is drawn out from the circulating gas outlet 7 by the high-temperature fan 10, flows through the four-way reversing valve B15, flows into the heat storage body B13, the high-temperature protective gas exchanges heat with the heat storage body B13, the temperature of the heat storage body B13 is increased, and the temperature of the high-temperature protective gas is decreased, the high-temperature protective gas flowing out of the heat storage body B13 flows into the four-way reversing valve A14, and then flows into the suction end of the high-temperature fan 10, after being pressurized by the high-temperature fan 10, flows into the four-way reversing valve A14, flows into the heat storage body A12, the protective gas exchanges heat with the heat storage body A12, the temperature of the heat storage body A12 is decreased, the temperature of the protective gas is increased, and the protective gas flows through the four-way reversing valve B15 and is blown into the jet blast box 2. Then the jet blast box 2 sprays and impacts the strip steel 5 at the jet blast nozzle 4, forms high-strength convection heat exchange with the strip steel 5, and then diffuses in the furnace, forms strong stirring effect on the gas in the furnace, and at the same time, exchanges heat with the heating device in the furnace in convection, so that the temperature in the furnace is uniform. The protective gas in the furnace circulates and flows under the action of the high-temperature fan 10, and the effect of strengthening heat exchange is achieved.

[0028] The present application is aimed at the furnace area with a furnace temperature below 700 DEG C, and simultaneously installs a heating device (resistance belt 3, electric radiation pipe, gas radiation pipe, etc.) and a jet device (slit, round hole, etc.) in the furnace, under the action of the high-temperature fan 10, the protective gas in the furnace is drawn out, is blown into the jet blast box 2 after the wind pressure is increased, then high-speed jet flow is formed at the jet blast nozzle 4 on the blast box, impacts the strip steel 5 to be heated, and high-efficiency convection heat exchange is carried out with the strip steel 5.

[0029] The present application is aimed at the furnace area with a furnace temperature below 700 DEG C, and simultaneously installs a heating device (resistance belt 3, electric radiation pipe, gas radiation pipe, etc.) and a jet device (slit, round hole, etc.) in the furnace, under the action of the high-temperature fan 10, the protective gas in the furnace is drawn out, is blown into the jet blast box 2 after the wind pressure is increased, then high-speed jet flow is formed at the jet blast nozzle 4 on the blast box, impacts the strip steel 5 to be heated, and high-efficiency convection heat exchange is carried out with the strip steel 5.

[0030] The specific embodiment is only an explanation of the present application, and is not a limitation of the present application, and those skilled in the art can make modifications to the embodiment without creative contribution according to the needs after reading the present application, but as long as the present application is within the scope of the claims, it is protected by the patent law.

Claims

1. A system for achieving rapid heating of a strip steel, characterized by: It comprises opposite furnace linings (1), high-temperature fans (10) and several gas pipes (11); jet blast boxes (2) are arranged opposite to the opposite furnace linings (1), the adjacent surfaces of the opposite jet blast boxes (2) are each provided with a jet spout (4) and a heating device, and the surfaces away from each other of the opposite jet blast boxes (2) are each provided with a circulating gas inlet (8); the furnace linings (1) are provided with a circulating gas outlet (7); the high-temperature fans (10) are connected with the circulating gas inlets (8) and the circulating gas outlet (7) through the gas pipes (11); The adjacent surfaces of the opposite jet blast boxes (2) are provided with a concave-convex structure connected with each other, the heating device is arranged in the concave part, and the jet spout (4) is arranged in the convex part. The surfaces of the jet blast boxes facing the strip steel are provided with a concave-convex structure, the space formed by the concave part is used to install the heating device, which is beneficial to jet exhaust, and the convex part is used to process the jet spout, which is helpful to form a jet of protective gas and impact the strip steel to improve the intensity of convective heat exchange; the surfaces of the jet blast boxes and the surfaces of the heating devices are sprayed with a high-emissivity coating to improve the intensity of radiative heat exchange in the furnace; the strip steel travels between the opposite jet blast boxes during heating, so that the jet blast boxes and the heating devices are installed on the left and right sides of the strip steel, forming a symmetrical heating form; the circulating gas inlets are arranged on the back or side surfaces of the jet blast boxes, and the circulating gas outlets are arranged on the furnace linings, the high-temperature protective gas in the furnace is extracted from the circulating gas outlets by the high-temperature fans, is boosted, is blown into the jet blast boxes, is then sprayed and impacted on the strip steel at the jet spouts, forms high-intensity convective heat exchange on the strip steel, is then dispersed in the furnace, forms a strong stirring action on the gas in the furnace, and at the same time, performs convective heat exchange with the heating devices in the furnace, so that the temperature in the furnace is uniform; the protective gas in the furnace flows circularly under the action of the high-temperature fans, and the effect of strengthening heat exchange is achieved.

2. The system for rapid heating of a strip steel according to claim 1, characterized in that: It also comprises a heat accumulator A (12), a heat accumulator B (13), a four-way reversing valve A (14) and a four-way reversing valve B (15); the high-temperature fans (10) are connected with the four-way reversing valve A (14) through the gas pipes (11), the four-way reversing valve A (14) is connected with the heat accumulator A (12) and the heat accumulator B (13) through the gas pipes (11), and the four-way reversing valve B (15) is connected with the circulating gas outlet (7), the circulating gas inlet (8), the heat accumulator A (12) and the heat accumulator B (13) through the gas pipes (11).

3. The system for rapid heating of a strip steel of claim 1, wherein: The heating device is an electric resistance belt (3) or a radiation tube (16), and the radiation tube (16) is an electric radiation tube or a gas radiation tube.

4. The system for rapid heating of a strip steel of claim 1, wherein: The jet spout (4) is a slit spout or a circular spout.

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