A method and device for improving the quality of hot-dip galvanized steel strip products

Abstract

The present invention relates to a method and device for improving the product quality of hot-dip galvanized steel strip, comprising a cooling box, a collecting box, an air suction branch pipe, an air suction main pipe, a circulating fan, and a mixed gas distribution main pipe, wherein the collecting box is arranged below the cooling box; the cooling box is a closed structure, wherein nitrogen is passed through the cooling box, and a plurality of heat exchange pipes are fixed in the cooling box, wherein the mixed gas drawn from the furnace nose is passed through the heat exchange pipes, and the nitrogen and the mixed gas are heat exchanged in the cooling box; the nitrogen outlet of the cooling box is connected to the nitrogen input pipeline of the air knife; one end of the air suction branch pipe extends into the furnace nose and communicates with the furnace nose space, and extends into the furnace nose, and the other ends of the plurality of air suction branch pipes are connected to the air suction main pipe, and the air suction main pipe is connected to the circulating fan, and the air suction main pipe transports the mixed gas in the furnace nose space to the mixed gas distribution main pipe, and the mixed gas distribution main pipe is connected to each heat exchange pipe in the cooling box. The advantage is that the defective rate of hot-dip galvanized steel strip caused by zinc ash is significantly reduced.

Description

Technical Field

[0001] The invention belongs to the field of hot-dip galvanizing of steel strips, and in particular relates to a method and a device for improving the product quality of hot-dip galvanized steel strips. Background Art

[0002] The cold-rolled strip steel continuously passes through the annealing furnace, zinc pot and air knife in the hot-dip galvanizing unit. Figure 1 The strip steel completes recrystallization annealing in the annealing furnace, passes through the furnace nose filled with protective gas at a temperature of 450-470℃ and enters the zinc pot, where a surface alloy coating is formed in the zinc liquid at 450-455℃. After leaving the zinc liquid, the air knife gap nozzle across the width of the strip steel sprays a continuous knife-like nitrogen gas flow to scrape off the excess zinc on the surface of the strip steel and control the thickness of the galvanized layer. Figure 2 On the other hand, the nitrogen gas flow causes a large temperature drop of the zinc liquid on the surface of the strip, thereby reducing the fluidity of the zinc liquid on the surface of the strip. Even if the air knife flow pressure reaches a certain value, the zinc layer thickness no longer decreases with the increase of the air knife flow pressure, forcing the unit to reduce the speed to achieve the required zinc layer thickness. The dual effect of the air knife flow causes a large lag in the control of the zinc layer thickness. When the new zinc layer thickness value is set, the strip runs 500 to 1000 meters to reach the set zinc layer thickness. This section of the strip becomes a substandard product.

[0003] Due to the dual effects of the air knife flow, the temperature of the zinc layer on the surface of the strip quickly drops below the solidification line when passing through the air knife. If the temperature drops too quickly, the difficulty of cutting and stripping the zinc layer in a solid-liquid mixed state will be greatly increased, resulting in a defect called "zinc flow lines" in the galvanized product. As a phenomenon, the "zinc flow line" defect is an external manifestation that the air knife flow reduces the fluidity of the zinc liquid in essence, and is a sufficient confirmation of the reduction in the fluidity of the zinc liquid. To solve this problem, patent application number CN202010097361.8 discloses an air knife control device and method for a hot-dip galvanizing unit, which heats the nitrogen gas flow to reduce the occurrence of the "zinc flow line" defect.

[0004] The strip is introduced into the zinc pot in the furnace nose. The closed furnace nose cavity is filled with a protective gas mixture of nitrogen and hydrogen, which causes the zinc liquid surface under the furnace nose to be unable to form an oxide layer and produces "zinc vapor". The zinc vapor condenses at the lower temperature of the inner wall of the furnace nose to form zinc ash. The "zinc ash" adheres to the surface of the strip and forms fan-shaped or radial defects. Summary of the invention

[0005] The purpose of the present invention is to provide a method and device for improving the quality of hot-dip galvanized steel strip products, reduce or eliminate the need for external medium to heat the nitrogen gas flow, improve the fluidity of zinc liquid on the strip surface when passing through the air knife, thereby eliminating the "zinc flow line" defect and saving energy; and by reducing the zinc ash in the furnace nose, reduce the fan-shaped defects on the strip surface caused by the "zinc ash".

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A device for improving the quality of hot-dip galvanized steel strip products, comprising a cooling box, a collecting box, an air suction branch pipe, an air suction main pipe, a circulating fan, and a mixed gas distribution main pipe, wherein the collecting box is arranged below the cooling box;

[0008] The cooling box is a closed structure, nitrogen is passed through the cooling box, a number of heat exchange tubes are fixed in the cooling box, the mixed gas drawn from the furnace nose is passed through the heat exchange tubes, and the nitrogen and the mixed gas are heat exchanged in the cooling box; the nitrogen outlet of the cooling box is connected to the nitrogen input pipeline of the air knife;

[0009] One end of the suction branch pipe extends into the furnace nose and communicates with the furnace nose space, and extends into the furnace nose. The other ends of the plurality of suction branch pipes are connected to the suction main pipe, and the suction main pipe is connected to a circulation fan. The suction main pipe transports the mixed gas in the furnace nose space to the mixed gas distribution main pipe, and the mixed gas distribution main pipe is connected to each heat exchange pipe in the cooling box;

[0010] The collecting box comprises a box body, an air duct, an ash hopper, a rotary valve and an air supply pipe. The outside of the box body is covered with a heat-insulating layer. The top of the box body is connected to the air duct through a flange. One end of the air duct is connected to the heat exchange pipe, and the other end extends into the box body. The outside of the air duct is covered with a heat-insulating layer. The bottom of the box body is fixedly connected to the ash hopper. A discharge port is provided at the bottom of the ash hopper, and a rotary valve is installed at the discharge port. The upper part of the box body is connected to an air supply pipe, which is connected to a furnace nose to guide the gas in the box body to the zinc liquid surface in the furnace nose.

[0011] The furnace nose is a double-layer hollow structure, which includes an inner wall and an outer wall, a cavity structure is formed between the inner wall and the outer wall, and the outer wall is covered with an insulation layer; one end of the air suction branch pipe extends into the furnace nose space formed by the inner wall, and the air suction main pipe and the mixed gas distribution main pipe are both connected to the cavity structure; the mixed gas in the furnace nose space is led out by the air suction branch pipe and enters the cavity structure, and then is led out by the mixed gas distribution main pipe and sent to the cooling box, so that the temperature of the inner wall is consistent with that in the furnace nose.

[0012] The suction branch pipe is connected to the upper part of the furnace nose, the suction main pipe is connected to the lower part of one side of the cavity structure, and the mixed gas distribution main pipe is connected to the upper part of the other side of the cavity structure.

[0013] The gas supply pipe is divided into two paths, one path is connected to one side of the furnace nose, and is used to introduce the gas in the box into the zinc liquid surface on the lower surface side of the strip in the furnace nose, and the other path is connected to the other side of the furnace nose, and is used to introduce the gas in the box into the zinc liquid surface on the upper surface side of the strip in the furnace nose.

[0014] The cooling box is provided with a nitrogen inlet and a nitrogen outlet on both sides, the heat exchange tube is vertically fixed in the cooling box, and the two ends of the heat exchange tube are respectively connected to the top cover and the bottom surface of the cooling box by flanges; nitrogen passes through the cooling box in the horizontal direction and mixed gas passes through the vertical direction.

[0015] The thermal insulation layer is a silicate material layer, and the outside of the cooling box is covered with a thermal insulation layer.

[0016] The gas pipeline is connected with a temperature detection device for detecting the temperature of the gas in the gas pipeline.

[0017] The heat exchange tube is connected with a valve, and the heat exchange tube is connected with the mixed gas distribution main pipe via the valve.

[0018] A method for improving the quality of hot-dip galvanized steel strip products comprises the following steps:

[0019] 1) The nitrogen from the nitrogen storage tank is input into the cooling box, and the mixed gas extracted from the furnace nose in the heat exchange tube is heat exchanged with the nitrogen in the cooling box, the nitrogen is heated to 80-110°C, the mixed gas is cooled to 180-230°C, and the zinc vapor in the mixed gas is condensed to form "zinc ash" and precipitated. The precipitated "zinc ash" is collected by the collection device and can be discharged from the discharge port;

[0020] 2) After cooling and separating the "zinc ash", the mixed gas is introduced onto the surface of the zinc liquid in the furnace nose, so that the surface temperature of the zinc liquid in the furnace nose is reduced to 410-430°C, thereby reducing the generation of zinc vapor;

[0021] 3) In the cooling box, the nitrogen heated by heat exchange is transported to the nitrogen input pipeline of the air knife; the temperature of the nitrogen is adjusted by controlling the input amount of the mixed gas heat exchange tube and the air volume of the mixed gas, thereby adjusting the temperature of the air knife flow.

[0022] After the mixed gas in the furnace nose space is extracted, it first enters the cavity structure between the inner wall and the outer wall of the furnace nose, so that the temperature of the inner wall of the furnace nose is consistent with the temperature inside the furnace nose, thereby eliminating the zinc ash produced after the zinc vapor condenses on the inner wall of the furnace nose, and then the mixed gas is discharged from the cavity structure and enters the heat exchange tube in the cooling box.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention uses the air knife medium-nitrogen to cool the mixed gas in the furnace nose, so that the temperature of the "zinc vapor" in the mixed gas drops below the freezing point and condenses into "zinc ash", and then the "zinc ash" in the mixed gas is separated; on the other hand, the surface temperature of the zinc liquid in the furnace nose is lowered by returning the cooled mixed gas to the furnace nose, reducing the generation of "zinc vapor". The present invention significantly reduces the defective rate of hot-dip galvanized strip steel products caused by "zinc ash".

[0025] 2. The inner wall of the furnace nose is heated by the circulation of the mixed gas in the furnace nose, so that the temperature of the inner wall of the furnace nose is consistent with that of the furnace nose, thereby eliminating the "zinc ash" produced by condensation of zinc vapor in the furnace nose on the inner wall of the furnace nose, reducing the "zinc ash" in the furnace nose, and reducing the fan-shaped defects on the surface of the strip caused by "zinc ash", thereby improving the surface quality of the strip.

[0026] 3. The "zinc ash" separated in the cooling box is collected by the collection box and discharged from the system to prevent the "zinc ash" from returning to the furnace nose and affecting the surface quality of the strip.

[0027] 4. In the cooling box, the nitrogen before entering the air knife is heated by the mixed gas in the furnace nose to increase the air knife flow temperature, thereby improving the fluidity of the zinc liquid, eliminating the "zinc flow pattern" defect of the strip, and increasing the galvanizing speed of the strip.

[0028] 5. The present invention utilizes the flowing air knife medium - nitrogen with original delivery pressure to cool the mixed gas in the furnace nose. No additional cooling medium is required. At the same time, no additional heating equipment is required to heat the air knife medium. Instead, the mixed gas is circulated in the furnace nose to heat the inner wall of the furnace nose only by relying on the circulating fan, which saves energy and reduces production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of galvanizing of steel strip.

[0030] Figure 2 It is a schematic diagram of the strip steel after galvanizing.

[0031] Figure 3 This is a schematic diagram of the structure of a device for improving the quality of hot-dip galvanized steel strip products. Figure 1 .

[0032] Figure 4 This is a schematic diagram of the structure of a device for improving the quality of hot-dip galvanized steel strip products. Figure 2 .

[0033] Figure 5 It is a connection diagram between the suction main pipe and the furnace nose.

[0034] Figure 6 It is a schematic diagram of the position of the strip in the furnace nose.

[0035] Figure 7 It is a schematic diagram of the structure of the cooling box.

[0036] In the figure: 1-strip steel, 2-air knife, 3-sinking roller, 4-zinc pot, 5-furnace nose, 6-annealing furnace, 7-suction branch pipe, 8-suction main pipe, 9-circulation fan, 10-mixed gas distribution main pipe, 11-cooling box, 12-nitrogen inlet, 13-nitrogen outlet, 14-heat exchange pipe, 15-valve, 16-nitrogen input pipeline, 17-inner wall, 18-outer wall, 19-cavity structure, 20-box, 21-air guide pipe, 22-ash hopper, 23-rotary valve, 24-gas delivery pipe, 25-thermal insulation layer, 26-temperature detection device, 27-waste hopper, 28-furnace nose space. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0038] Example 1

[0039] See Figure 3 , Figure 7 A device for improving the quality of hot-dip galvanized strip steel products, comprising a cooling box 11, a collecting box, an air suction branch pipe 7, an air suction main pipe 8, a circulating fan 9, and a mixed gas distribution main pipe 10, wherein the collecting box is arranged below the cooling box 11. The cooling box 11 is used to realize the heat exchange between the mixed gas in the furnace nose 5 and the medium of the air knife 2-nitrogen. The cooling box 11 is a closed structure, and a nitrogen inlet 12 and a nitrogen outlet 13 are respectively arranged on both sides of the cooling box 11, which are used to pass nitrogen to the cooling box 11. A plurality of heat exchange tubes 14 are vertically fixed in the cooling box 11, and the two ends of the heat exchange tubes 14 are respectively connected to the top cover and the bottom surface of the cooling box 11 by flanges; the heat exchange tubes 14 can be made of stainless steel tubes, 10 to 30 tubes. The heat exchange tubes 14 are 2.9 to 3.2 m long, 1.5 mm thick, and 50 to 60 mm in outer diameter. Nitrogen is passed through the cooling box 11 in the horizontal direction, and mixed gas is passed through the vertical direction. The heat exchange tube 14 is filled with the mixed gas extracted from the furnace nose 5, and the nitrogen and the mixed gas are heat exchanged in the cooling box 11; the nitrogen outlet 13 of the cooling box 11 is connected to the nitrogen input pipeline 16 of the air knife 2. On the one hand, the mixed gas circulates through these heat exchange tubes 14; on the other hand, the nitrogen before entering the air knife 2 continuously passes through the cooling box 11 to cool the circulating gas in the heat exchange tube 14. The more steel pipes there are in the cooling box 11, the larger the heat exchange area and the higher the heat exchange efficiency. The mixed gas in the furnace nose 5 is cooled by the nitrogen medium of the air knife 2 to separate the "zinc ash", so as to achieve the purpose of reducing the "zinc ash" in the furnace nose 5; the heat dissipated by the mixed gas through the heat exchange tube 14 is used to heat the medium of the air knife 2 - nitrogen, which improves the fluidity of the surface zinc liquid when the strip 1 passes through the air knife 2, thereby increasing the unit speed and reducing the occurrence of "zinc flow line" defects.

[0040] See Figure 3One end of the suction branch pipe 7 is connected to the furnace nose 5 and extends into the furnace nose 5. The other ends of the suction branch pipes 7 are connected to the suction main pipe 8. The suction main pipe 8 is connected to a circulating fan 9. The suction main pipe 8 transports the mixed gas in the furnace nose 5 to the mixed gas distribution main pipe 10. The mixed gas distribution main pipe 10 is connected to each heat exchange pipe 14 in the cooling box 11.

[0041] The heat exchange tube 14 is connected with a valve 15, and the heat exchange tube 14 is connected to the mixed gas distribution main pipe 10 through the valve 15. The number of heat exchange tubes 14 put into use is determined by controlling the number of valves 15 opened and closed, and then the size of the circulating air volume is controlled. When the circulating air volume increases, the temperature of the air knife 2 flow is relatively high, and the circulating air return temperature is relatively high; when the circulating air volume decreases, the temperature of the air knife 2 flow is relatively low, and the circulating air return temperature is relatively low. In specific production, when the unit produces 0.4≤thickness≤1.5mm specification strip steel 1, the valve 15 is selected to open more, and the temperature of the air knife 2 flow is relatively increased to adapt to the high running speed of the thin specification strip steel 1. When the unit produces 1.5<thickness≤2..5mm specification strip steel 1, the valve 15 is selected to open less, and the circulating air return temperature is relatively reduced, so as to achieve the purpose of reducing the surface temperature of the zinc liquid in the furnace nose 5 and reducing the "zinc steam".

[0042] See Figure 3 The collecting box includes a box body 20, an air duct 21, an ash hopper 22, a rotary valve 23, and an air delivery pipe 24. The box body 20 is covered with a heat-insulating layer. The top of the box body 20 is connected to the air duct 21 through a flange. One end of the air duct 21 is connected to the heat exchange pipe 14, and the other end extends into the box body 20. The air duct 21 is covered with a heat-insulating layer 25. The heat-insulating layer 25 is a silicate material layer. The setting of the heat-insulating layer 25 can ensure that the temperature of the mixed gas and the "zinc ash" after cooling in the stainless steel pipe is not heated by the mixed gas in the collecting box, and continues to settle to the bottom of the box body 20. The air duct 21 and the heat exchange pipe 14 can be a stainless steel pipe. The bottom of the box 20 is fixedly connected to the ash hopper 22. The ash hopper 22 is used to collect the condensed and settled "zinc ash" for easy discharge. A discharge port is provided at the bottom of the ash hopper 22. The rotary valve 23 is installed at the discharge port to keep the collection box in a closed state to discharge the "zinc ash" to the outside of the collection box, and the waste hopper 27 is used to hold the "zinc ash" discharged from the collection box. The upper part of the box 20 is connected to the gas pipeline 24, which is connected to the furnace nose 5 to guide the gas in the box 20 to the zinc liquid surface in the furnace nose 5. The outside of the cooling box 11 is covered with an insulation layer. The gas pipeline 24 is connected to a temperature detection device 26 for detecting the gas temperature in the gas pipeline 24 and feeding it back to the control center to adjust the switch of the valve 15, and then adjust the number of heat exchange tubes 14 put into operation.

[0043] See Figure 3The gas delivery pipe 24 is divided into two paths, one of which is connected to one side of the furnace nose 5 and is used to introduce the gas in the box 20 to the zinc liquid surface on the lower surface side of the strip 1 in the furnace nose 5, and the other is connected to the other side of the furnace nose 5 and is used to introduce the gas in the box 20 to the zinc liquid surface on the upper surface side of the strip 1 in the furnace nose 5. Directly guiding the cooled mixed gas to the zinc liquid surface can relatively reduce the surface temperature of the zinc liquid and achieve the effect of suppressing the generation of zinc vapor; the cross section of the furnace nose 5 is a rectangular structure, and the strip 1 passes through the middle of the rectangle. The circulating return gas delivery pipe 24 is arranged on both sides of the strip 1, in order to make the cooling of the zinc liquid surface more uniform.

[0044] See Figure 3 , Figure 7 , a method for improving the quality of hot-dip galvanized steel strip products, comprising the following steps:

[0045] 1) Nitrogen gas at 15-28℃ from nitrogen storage tank at 6800-7200m 3 The air volume of / h is input into the cooling box 11, and the mixed gas extracted from the furnace nose 5 in the heat exchange tube 14 is heat exchanged with nitrogen in the cooling box 11, and the mixed gas is cooled to 180-230°C, and the zinc vapor in the mixed gas condenses to form "zinc ash" and settles. The settled "zinc ash" is collected by the collecting device and can be discharged from the discharge port;

[0046] 2) After cooling and separating the "zinc ash", the mixed gas is introduced onto the surface of the zinc liquid in the furnace nose 5, so that the surface temperature of the zinc liquid in the furnace nose 5 is reduced to 410-430°C;

[0047] 3) In the cooling box 11, the nitrogen is heated to 80-110°C after heat exchange and transported to the nitrogen input pipeline 16 of the air knife 2. The temperature of the air knife 2 flow increases, which enhances the fluidity of the zinc liquid on the surface of the strip 1 when passing through the air knife 2. The temperature of the nitrogen is adjusted by controlling the input amount of the mixed gas heat exchange pipe 14 and the air volume of the mixed gas, and then the temperature of the air knife 2 flow is adjusted.

[0048] Example 2

[0049] On the basis of Example 1, the furnace nose structure and the process before the mixed gas is transported to the cooling box 11 are changed to prevent the zinc vapor from condensing on the inner wall 17 of the furnace nose 5 to produce zinc ash.

[0050] See Figure 4-Figure 6 Normally, the temperature of the mixed gas in the furnace nose 5 is higher than the temperature of the inner wall 17 of the furnace nose 5. The mixed gas condenses near the inner wall 17 of the furnace nose 5, which easily produces zinc ash. For this reason, the furnace nose 5 is designed to be a hollow structure. Figure 4-Figure 6The strip steel 1 passes through the rectangular closed furnace nose space 28 of the inner wall of the furnace nose. The outer cover of the furnace nose 5 adopts a double-layer structure. While increasing the temperature of the inner wall 17, a cavity structure 19 is formed between the inner wall 17 and the outer wall 18. The outer wall 18 is covered with an insulation layer. One end of the suction branch pipe 7 extends into the furnace nose space 28, and the suction main pipe 8 and the mixed gas distribution main pipe 10 are both connected to the cavity structure 19. Since the upper part of the furnace nose space 28 is close to the annealing furnace 6, the temperature of the upper part of the furnace nose space 28 is higher than that of the lower part, the suction branch pipe 7 is connected to the upper part of the furnace nose space 28, the suction main pipe 8 is connected to the lower part of one side of the cavity structure 19, and the mixed gas distribution main pipe 10 is connected to the upper part of the other side of the cavity structure 19, so that the mixed gas can fully pass through the entire cavity structure 19, and the circulating fan 9 provides power to suck the mixed gas in the furnace nose space 28 into the suction branch pipe 7, and then enter the cavity structure 19 through the suction main pipe 8. After circulating in the cavity, it is led out by the mixed gas distribution main pipe 10 and sent to the cooling box 11, so that the temperature of the inner wall 17 is consistent with that in the furnace nose space 28, so as to avoid the condensation of zinc vapor on the inner wall 17 of the furnace nose 5 to produce zinc ash.

[0051] Before the mixed gas in the furnace nose 5 is transported to the cooling box 11, it first enters the cavity structure 19 between the inner wall 17 and the outer wall 18 of the furnace nose 5, so that the temperature of the inner wall 17 of the furnace nose 5 is consistent with the temperature inside the furnace nose 5, thereby eliminating the zinc ash produced after the zinc vapor condenses on the inner wall 17 of the furnace nose 5, and then the mixed gas is discharged from the cavity structure 19 and enters the heat exchange tube 14 in the cooling box 11.

[0052] The above technical features can be combined in any one or more embodiments or examples in a suitable manner. Although the embodiments of the present invention have been shown and described, it can be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and purpose of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

[0053] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Claims

1. A device for improving the quality of hot-dip galvanized steel strip products, characterized in that: It includes a cooling box, a collecting box, an air suction branch pipe, an air suction main pipe, a circulating fan, and a mixed gas distribution main pipe, and the collecting box is arranged below the cooling box; The cooling box is a closed structure, nitrogen is passed through the cooling box, a number of heat exchange tubes are fixed in the cooling box, the mixed gas drawn from the furnace nose is passed through the heat exchange tubes, and the nitrogen and the mixed gas are heat exchanged in the cooling box; the nitrogen outlet of the cooling box is connected to the nitrogen input pipeline of the air knife; One end of the suction branch pipe extends into the furnace nose and communicates with the furnace nose space, and extends into the furnace nose. The other ends of the plurality of suction branch pipes are connected to the suction main pipe, and the suction main pipe is connected to a circulation fan. The suction main pipe transports the mixed gas in the furnace nose space to the mixed gas distribution main pipe, and the mixed gas distribution main pipe is connected to each heat exchange pipe in the cooling box; The collecting box includes a box body, an air guide pipe, an ash hopper, a rotary valve, and an air delivery pipe. The outside of the box body is covered with a heat-insulating layer. The top of the box body is connected to the air guide pipe through a flange. One end of the air guide pipe is connected to the heat exchange pipe, and the other end extends into the box body. The outside of the air guide pipe is covered with a heat-insulating layer. The bottom of the box body is fixedly connected to the ash hopper. A discharge port is provided at the bottom of the ash hopper, and a rotary valve is installed at the discharge port. The upper part of the box body is connected to an air delivery pipe, which is connected to the furnace nose to guide the gas in the box body to the zinc liquid surface in the furnace nose. The furnace nose is a double-layer hollow structure, and the furnace nose includes an inner wall and an outer wall, a cavity structure is formed between the inner wall and the outer wall, and the outer wall is covered with a heat preservation layer; one end of the air suction branch pipe extends into the furnace nose space formed by the inner wall, and the air suction main pipe and the mixed gas distribution main pipe are both connected with the cavity structure; the mixed gas in the furnace nose space is led out by the air suction branch pipe and then enters the cavity structure, and then is led out by the mixed gas distribution main pipe and sent to the cooling box, so that the temperature of the inner wall is consistent with that in the furnace nose; The cooling box is provided with a nitrogen inlet and a nitrogen outlet on both sides, the heat exchange tube is vertically fixed in the cooling box, and the two ends of the heat exchange tube are respectively connected to the top cover and the bottom surface of the cooling box by flanges; nitrogen passes through the cooling box in the horizontal direction and mixed gas passes through the vertical direction.

2. The device for improving the quality of hot-dip galvanized steel strip products according to claim 1, characterized in that: The suction branch pipe is connected to the upper part of the furnace nose, the suction main pipe is connected to the lower part of one side of the cavity structure, and the mixed gas distribution main pipe is connected to the upper part of the other side of the cavity structure.

3. The device for improving the quality of hot-dip galvanized steel strip products according to claim 1, characterized in that: The gas supply pipe is divided into two paths, one path is connected to one side of the furnace nose, and is used to introduce the gas in the box into the zinc liquid surface on the lower surface side of the strip in the furnace nose, and the other path is connected to the other side of the furnace nose, and is used to introduce the gas in the box into the zinc liquid surface on the upper surface side of the strip in the furnace nose.

4. The device for improving the quality of hot-dip galvanized steel strip products according to claim 1, characterized in that: The thermal insulation layer is a silicate material layer, and the outside of the cooling box is covered with a thermal insulation layer.

5. The device for improving the quality of hot-dip galvanized steel strip products according to claim 1, characterized in that: The gas pipeline is connected with a temperature detection device for detecting the temperature of the gas in the gas pipeline.

6. The device for improving the quality of hot-dip galvanized steel strip products according to claim 1, characterized in that: The heat exchange tube is connected with a valve, and the heat exchange tube is connected with the mixed gas distribution main pipe via the valve.

7. A method for improving the quality of hot-dip galvanized steel strip products using the device according to any one of claims 1 to 6, characterized in that: The following steps are involved: 1) The nitrogen from the nitrogen storage tank is input into the cooling box. The mixed gas extracted from the furnace nose in the heat exchange tube exchanges heat with the nitrogen in the cooling box. The nitrogen is heated to 80-110°C, and the mixed gas is cooled to 180-230°C. The zinc vapor in the mixed gas condenses to form "zinc ash" and settles. The settled "zinc ash" is collected by the collection device and can be discharged from the discharge port; 2) After cooling and separating the "zinc ash", the mixed gas is introduced onto the surface of the zinc liquid in the furnace nose, so that the surface temperature of the zinc liquid in the furnace nose is reduced to 410-430°C, thereby reducing the generation of zinc vapor; 3) In the cooling box, the nitrogen heated by heat exchange is transported to the nitrogen input pipeline of the air knife; the temperature of the nitrogen is adjusted by controlling the input quantity of the mixed gas heat exchange tube and the air volume of the mixed gas, thereby adjusting the temperature of the air knife flow.

8. A method for improving the quality of hot dip galvanized steel strip products according to claim 7, characterized in that: After the mixed gas in the furnace nose space is extracted, it first enters the cavity structure between the inner wall and the outer wall of the furnace nose, so that the temperature of the inner wall of the furnace nose is consistent with the temperature inside the furnace nose, thereby eliminating the zinc ash produced after the zinc vapor condenses on the inner wall of the furnace nose, and then the mixed gas is discharged from the cavity structure and enters the heat exchange tube in the cooling box.

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