Water quenching and water circulation cooling process for color-coated sheet

Abstract

The invention discloses a color-coated sheet water-quenching and water-circulating cooling process, and relates to the technical field of color-coated sheet production, and the color-coated sheet water-quenching and water-circulating cooling process comprises the following steps: S1, storing circulating cooling water in a water-quenching circulating water storage tank; s2, when the color coating unit needs to cool the color-coated sheet, a cooling water supply pump is started, cooling water is conveyed into a set of cooling water nozzles on the front face and the back face of the strip steel through the cooling water supply pump, the cooling water is sprayed to the surface of the color-coated sheet in a fan shape through the cooling water nozzles, and cooling of the strip steel is achieved; s3, cooling water cools the color-coated sheet and is heated at the same time, and the heated cooling water flows back into a water quenching backflow tank in a self-flowing mode; continuous and reliable operation of the cooling system can be ensured, blockage of the cooling system caused by oil sludge is prevented, meanwhile, rapid cooling of the color-coated sheet can be achieved, and it can be ensured that the outlet temperature of the color-coated sheet of a continuous production line is 45 DEG C or below.

Description

Technical Field

[0001] The invention relates to the technical field of production of color-coated plates, in particular to a water quenching and water circulating cooling process for color-coated plates. Background Art

[0002] Color-coated steel refers to cold-rolled and galvanized steel sheets with a coating applied directly to the surface, enhancing their aesthetics and protecting them from corrosion. Because color-coated steel can be directly used in industries such as construction and home appliances, eliminating the need for post-molding painting and contributing to energy conservation and environmental protection, its application is expanding.

[0003] The production process for color-coated steel sheets involves pre-treating the substrate surface, applying several layers of paint continuously, curing it through baking, rapidly cooling it, and then winding it into coils. Color-coated steel sheet production is a continuous process, requiring the paint on the surface to cure at high temperatures. Once cured, the sheets must be rapidly cooled before they can be coiled. Therefore, the cooling process is a key factor in determining the production efficiency of color-coated steel sheets.

[0004] The most traditional method for cooling color-coated strip steel is air cooling. However, this method is ineffective, results in uneven cooling, and the strip steel is easily deformed by high airflow, affecting the final strip shape. Currently, most color-coating lines use water quenching for strip cooling. The circulating water used for this cooling is currently cooled by plate heat exchangers. Because the cooling water comes into direct contact with the cured strip steel, incompletely cured coating on the strip surface can enter the circulating cooling water, forming sludge. This sludge can easily clog the plate heat exchanger, requiring frequent maintenance and impacting continuous production.

[0005] For this purpose, a water quenching and water circulating cooling process for color-coated plates was invented, which has important practical significance for improving the normal operation of the color-coating unit and improving the quality of the color-coated plates. Summary of the Invention

[0006] Purpose of the invention: In view of the problems with the cooling method of color-coated plates in the current production process of color-coated plates, the purpose of the present invention is to provide a water quenching and water circulation cooling process for color-coated plates to solve the problems of low cooling efficiency of plate coolers and easy clogging of oil sludge, thereby increasing the operating speed of the color-coating unit and improving the quality of color-coated plates.

[0007] Technical solution: A water quenching and water circulation cooling process for color-coated plates, comprising the following steps:

[0008] S1, circulating cooling water is stored in the water quenching circulating water storage tank;

[0009] S2. When the color coating unit needs to cool the color coated steel sheet, the cooling water supply pump is started to deliver cooling water to a set of cooling water nozzles on the front and back sides of the steel strip. The cooling water is sprayed in a fan shape onto the surface of the color coated steel sheet through the cooling water nozzles to cool the steel strip.

[0010] S3, the cooling water is heated while cooling the color-coated plate, and the heated cooling water flows back to the water quenching water reflux tank by gravity;

[0011] S4, the water in the water quenching water reflux tank is filtered by a barrel filter through a cooling water inlet pump and then enters the circulating water cooling tower;

[0012] S5. The circulating water is cooled in the circulating water cooling tower, and the cooled circulating water is returned to the water quenching circulating water storage tank to achieve purification and circulation of the quenching water.

[0013] Furthermore, the entire water quenching cooling water circulation system is as follows Figure 1 As shown, the system is controlled by PLC. The control system receives information on the strip running speed, strip thickness, and water temperature in the water quenching circulating water storage tank of the unit, and controls the flow rates of the cooling water supply pump and the cooling water inlet pump.

[0014] Furthermore, the cooling water supply pump is a variable frequency centrifugal pump, and the control system calculates the cooling water circulation volume W based on the water temperature T in the water quenching circulating water storage tank, the speed u of the unit and the thickness t of the color-coated plate, and adjusts it through the frequency conversion controller.

[0015] Furthermore, the circulation volume W of the cooling water is related to the water temperature T in the water quenching circulating water storage tank, the speed u of the unit and the thickness t of the color-coated plate, and the relationship between them is:

[0016] W = 375 × t × u / (260-T).

[0017] Furthermore, the volume of the water quenching circulating water storage tank is between 30 and 100 m3. In order to achieve the cooling efficiency of the color-coated plate, the water temperature t in the water quenching circulating water storage tank is controlled between 25 and 40°C. In order to ensure that the water temperature in the water tank meets this requirement, the water quenching circulating water storage tank is equipped with a cooling system.

[0018] Furthermore, quenching water is sprayed onto the surface of the strip through a group of nozzles arranged on the upper and lower surfaces of the strip. The cooling water nozzle is a fan-shaped nozzle, the spray angle A is 30 to 90 degrees, the distance H between the cooling water nozzle and the strip is 200 to 400 mm, and the number of nozzles on a single side is related to the distance D between the two nozzles.

[0019] Furthermore, in order to achieve the cooling effect of the strip steel, the entire cooling system has a total of 8 groups of nozzles, each nozzle is controlled by a separate flow regulating valve to control the flow of the nozzle, the spacing between each group of nozzles is 600mm, and the water quenching circulating water storage tank is equipped with an exhaust system.

[0020] Furthermore, the cooling water inlet pump is linked to the cooling water supply pump, and the two pumps are controlled by PLC to run at the same speed to ensure the stability of the liquid level in the water quenching water reflux tank.

[0021] Furthermore, the cooling capacity of the circulating water cooling tower is selected according to the maximum width, thickness and operating speed of the color-coated plate produced by the unit, and the maximum cooling capacity is:

[0022]

[0023] Furthermore, the filter medium of the barrel filter is made of stainless steel, ceramic or plastic, and the filtration accuracy is 1 to 5 μm.

[0024] Beneficial effects:

[0025] Since the cooling efficiency in the production process of color-coated plates is an important factor affecting their production efficiency and product quality, the present invention can ensure the continuous and reliable operation of the cooling system, prevent the cooling system from being blocked due to sludge, and at the same time achieve rapid cooling of the color-coated plates, ensuring that the outlet temperature of the color-coated plates on the continuous production line is below 45°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the process flow chart of water quenching and water circulation cooling;

[0027] Figure 2 This is the layout diagram of the cooling nozzle;

[0028] Figure 3 This is the nozzle layout diagram of the cooling system.

[0029] In the figure: 1. Water quenching circulating water storage tank; 2. Cooling water supply pump; 3. Cooling water nozzle; 4. Color-coated steel plate; 5. Water quenching water return tank; 6. Cooling water inlet pump; 7. Circulating water cooling tower; 8. Barrel filter. DETAILED DESCRIPTION

[0030] In order to make the technical solution of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Example 1

[0032] According to the attached Figure 1-3 , provides a water quenching and water circulation cooling process for color-coated plates, comprising the following steps:

[0033] S1, circulating cooling water is stored in water quenching circulating water storage tank 1;

[0034] S2. When the color coating unit needs to cool the color coated steel sheet, the cooling water supply pump 2 is started. The cooling water is supplied to a set of cooling water nozzles 3 on the front and back sides of the steel strip through the cooling water supply pump 2. The cooling water is sprayed in a fan shape onto the surface of the color coated steel sheet 4 through the cooling water nozzles 3 to cool the steel strip;

[0035] S3, the cooling water is heated while cooling the color-coated plate 4, and the heated cooling water flows back to the water quenching water reflux tank 5 by gravity;

[0036] S4, the water in the quenching water reflux tank 5 passes through the cooling water inlet pump 6 and is filtered by the barrel filter 8 before entering the circulating water cooling tower 7;

[0037] S5. The circulating water is cooled in the circulating water cooling tower 7. The cooled circulating water is returned to the water quenching circulating water storage tank 1 to achieve purification and circulation of the water quenching water.

[0038] In this embodiment, the entire water quenching cooling water circulation system is as follows: Figure 1 As shown, the system is controlled by PLC. The control system receives information about the strip running speed, strip thickness, and water temperature in the water quenching circulating water storage tank of the unit, and controls the flow of the cooling water supply pump 2 and the cooling water inlet pump 6.

[0039] In this embodiment, the cooling water supply pump 2 is a variable frequency centrifugal pump. The control system calculates the circulation volume W of the cooling water based on the water temperature T in the water quenching circulating water storage tank 1, the speed u of the unit and the thickness t of the color-coated plate, and adjusts it through the frequency conversion controller.

[0040] In this embodiment, the circulation volume of cooling water W (m 3 / h) is related to the water temperature T (℃) in the water quenching circulating water storage tank 1, the speed u (mpm) of the unit and the thickness t (mm) of the color-coated plate 4. The relationship between them is:

[0041] W = 375 × t × u / (260-T).

[0042] In this embodiment, the volume of the water quenching circulating water storage tank 1 is 30 to 100 m 3 In order to achieve the cooling efficiency of the color-coated plate 4, the water temperature t in the water quenching circulating water storage tank 1 is controlled between 25 and 40°C. In order to ensure that the water temperature in the water tank meets this requirement, the water quenching circulating water storage tank 1 is equipped with a cooling system.

[0043] In this embodiment, quenching water is sprayed onto the surface of the strip through a group of nozzles arranged on the upper and lower surfaces of the strip. The cooling water nozzle 3 is a fan-shaped nozzle, the spray angle A is 30 to 90°, and the distance H between the cooling water nozzle 3 and the strip is 200 to 400 mm. The number of nozzles on a single side is related to the distance D between the two nozzles.

[0044] In this embodiment, in order to achieve the cooling effect of the strip steel, the entire cooling system has a total of 8 groups of nozzles, each nozzle is controlled by a separate flow regulating valve to control the flow of the nozzle, the spacing between each group of nozzles is 600mm, and the water quenching circulating water storage tank 1 is provided with an exhaust system.

[0045] In this embodiment, the cooling water inlet pump 6 is linked to the cooling water supply pump 2 , and the two pumps are controlled by PLC to run at the same speed to ensure that the liquid level in the quenching water reflux tank 5 is stable.

[0046] In this embodiment, the cooling capacity of the circulating water cooling tower 7 is selected according to the maximum width, thickness and operating speed of the color-coated plate 4 produced by the unit, and the maximum cooling capacity is:

[0047]

[0048] In this embodiment, the filter medium of the barrel filter 8 is made of stainless steel, ceramic or plastic, and the filtration accuracy is 1 to 5 μm.

[0049] Example 2

[0050] In a color coating production line, the color coating unit cools the strip in the initial coating and final coating water quenching sections. The unit's maximum strip thickness is 1200×0.5mm, and the maximum strip speed is 150m / min. The strip temperature is required to drop from 260°C at the furnace outlet to below 40°C after passing through the water quenching system. Based on this requirement, the water quenching system is constructed as follows:

[0051] (1) In the initial coating section of the unit, the following settings are respectively set: Figure 1 The water quenching cooling system shown is controlled by PLC. The control system receives information such as the strip running speed, strip thickness, and water temperature in the water quenching circulating water storage tank 1 of the unit, and controls the flow of the cooling water supply pump 2 and the cooling water inlet pump 6.

[0052] (2) According to the water quenching requirements of the unit, the volume of the water quenching circulating water storage tank 1 is 50m 3 In order to achieve the cooling efficiency of the color-coated plate, the water temperature t in the water quenching circulating water storage tank 1 is controlled between 30±5℃. The water quenching circulating water storage tank 1 is equipped with a cooling system.

[0053] (3) According to the setting of the water temperature in the water quenching circulating water storage tank 1 to 30℃, the maximum speed of the unit to 150mpm and the thickness of the color-coated plate 4 to 0.5mm, the flow rate of the cooling circulating water is determined to be: 122m 3 / h.

[0054] (4) The cooling water supply pump 2 adopts a variable frequency centrifugal pump. The control system calculates the circulation volume W of the cooling water based on the information such as the water temperature T in the water storage tank, the speed u of the unit and the thickness t of the color-coated plate 4. The frequency conversion controller changes the flow rate by adjusting the speed of the pump motor.

[0055] (5) Water quenching water is sprayed onto the surface of the strip through a set of nozzles installed on the upper and lower surfaces of the strip. The nozzles are fan-shaped nozzles with a spray angle A of 65°. The distance H between the nozzles and the strip is 350mm, and the spacing D between the two nozzles is 300mm. Four nozzles are arranged on one side. The entire cooling system has a total of 8 sets of nozzles. When producing products with extreme specifications, all 8 sets of nozzles are put into operation.

[0056] (6) The cooling water inlet pump 6 is linked to the cooling water supply pump 2. The two pumps are controlled by PLC to run at the same speed, which can ensure the stability of the liquid level in the quenching water reflux tank 5.

[0057] (7) The cooling capacity of the circulating water cooling tower 7 is selected based on the maximum width, thickness and operating speed of the color-coated plate produced by the unit. The cooling capacity required under the limit specifications is:

[0058] Cooling capacity = 15.3 × 1.2 × 0.5 × 150 = 1377 kW

[0059] The actual cooling power of the unit is determined to be 1400kW.

[0060] (8) The circulating water is filtered by a barrel filter 8, and the filter medium is a stainless steel filter mesh with a filtration accuracy of 1 to 5 μm.

[0061] The water quenching cooling process can maintain continuous and stable operation within a regular maintenance cycle, and can also achieve rapid cooling of the color-coated plates, ensuring that the outlet temperature of the color-coated plates on the continuous production line is below 40°C. The main purpose of timely maintenance is to clean the impurities in the filter.

[0062] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A water quenching and water circulation cooling process for color-coated plates, characterized by: The following steps are involved: S1, circulating cooling water is stored in a water quenching circulating water storage tank (1); S2. When the color coating unit needs to cool the color coated plate, the cooling water supply pump (2) is started, and the cooling water is supplied to a group of cooling water nozzles (3) on the front and back sides of the steel strip through the cooling water supply pump (2). The cooling water is sprayed in a fan shape onto the surface of the color coated plate (4) through the cooling water nozzles (3), thereby cooling the steel strip; S3, the cooling water is heated while cooling the color-coated plate (4), and the heated cooling water flows back to the water quenching water reflux tank (5) by gravity; S4, the water in the water quenching water reflux tank (5) is filtered by the barrel filter (8) through the cooling water inlet pump (6) and then enters the circulating water cooling tower (7); S5. The circulating water is cooled in the circulating water cooling tower (7), and the cooled circulating water is returned to the water quenching circulating water storage tank (1) to achieve purification and circulation of the water quenching water.

2. The water quenching and water circulating cooling process for color-coated plates according to claim 1, characterized in that: The water quenching water circulation cooling process is controlled by a PLC, which receives information on the strip steel running speed, strip steel thickness, and water temperature in the water quenching circulation water storage tank of the unit, and controls the flow of the cooling water supply pump (2) and the cooling water inlet pump (6).

3. The water quenching and water circulating cooling process for color-coated plates according to claim 2, characterized in that: The cooling water supply pump (2) is a variable frequency centrifugal pump. The PLC calculates the cooling water circulation volume W based on the water temperature T in the water quenching circulating water storage tank (1), the speed u of the unit and the thickness t of the color-coated plate, and adjusts it through the variable frequency controller.

4. The water quenching and water circulating cooling process for color-coated plates according to claim 3 is characterized in that: The circulation volume W of the cooling water is related to the water temperature T in the water quenching circulating water storage tank (1), the speed u of the unit and the thickness t of the color-coated plate (4), and the relationship between them is: W = 375 × t × u / (260-T).

5. The water quenching and water circulating cooling process for color-coated plates according to claim 1, characterized in that: The volume of the water quenching circulating water storage tank (1) is between 30 and 100 m3. In order to achieve the cooling efficiency of the color-coated plate (4), the water temperature t in the water quenching circulating water storage tank (1) is controlled between 25 and 40°C. In order to ensure that the water temperature in the water tank meets this requirement, the water quenching circulating water storage tank (1) is equipped with a cooling system.

6. The water quenching and water circulating cooling process for color-coated plates according to claim 1, characterized in that: The cooling water nozzle (3) is a fan-shaped nozzle, the spray angle A is 30-90 degrees, the distance H between the cooling water nozzle (3) and the steel strip is 200-400 mm, and the number of nozzles on a single side is related to the distance D between the two nozzles.

7. The water quenching and water circulating cooling process for color-coated plates according to claim 1, characterized in that: In order to achieve the cooling effect of the strip steel, the entire cooling system has a total of 8 groups of nozzles, each nozzle has a flow rate controlled by a separate flow regulating valve, the spacing between each group of nozzles is 600mm, and the water quenching circulating water storage tank (1) is provided with an exhaust system.

8. The water quenching and water circulating cooling process for color-coated plates according to claim 2, characterized in that: The cooling water inlet pump (6) is linked to the cooling water supply pump (2), and the two pumps are controlled by PLC to run at the same speed to ensure that the liquid level in the water quenching water return tank (5) is stable.

9. The water quenching and water circulating cooling process for color-coated plates according to claim 1, characterized in that: The cooling capacity of the circulating water cooling tower (7) is selected based on the maximum width, thickness and operating speed of the color-coated plate (4) produced by the unit, and the maximum cooling capacity is:

10. The water quenching and water circulating cooling process for color-coated plates according to claim 1, characterized in that: The filter medium of the barrel filter (8) is made of stainless steel, ceramic or plastic, and the filtering accuracy is 1 to 5 μm.

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