Method for adjusting water temperature difference by automatically adjusting water volume of crystallizer

Abstract

The invention discloses a method for realizing water temperature difference adjustment by automatically adjusting water quantity of a crystallizer, and belongs to the technical field of continuous casting of ferrous metallurgy. According to the technical scheme, default cooling water flow of the wide face and the narrow face of the crystallizer is set according to the continuous casting pulling speed (the pulling speed larger than or equal to 1.3 m / min and the pulling speed smaller than 1.3 m / min are set in two gears); the water inlet and outlet temperature difference of the wide surface and the narrow surface is monitored in real time; when the wide surface temperature difference is larger than 9 DEG C, the wide surface water volume is gradually increased step by step, the water volume is 50 L / min every time, the interval is 1 min, and the pulling speed is reduced by 0.1 m / min if the water volume still exceeds the limit after two times of adjustment; when the temperature difference of the narrow surface is greater than 9 DEG C, increasing 30 L / min every time at an interval of 1 min, and reducing the pulling speed if the limit is still exceeded after two times; keeping the water quantity unchanged when the temperature difference is less than or equal to 9 DEG C; and a visual warning signal is sent out when abnormity occurs. According to the method, dynamic partition accurate adjustment of the cooling water amount is achieved, a multi-stage protection mechanism of increasing water first and then decreasing speed is established, surface cracks of the casting blank are remarkably reduced, and the hot delivery rate and production safety of a casting machine are improved.

Description

Technical Field

[0001] This invention belongs to the field of steelmaking continuous casting technology, specifically relating to a method for automatically adjusting the water volume in a crystallizer to regulate the water temperature difference. Background Technology

[0002] In modern continuous casting production, the crystallizer is a key piece of equipment for the initial solidification of molten steel into a billet shell. Its cooling system's heat extraction capacity directly determines the uniformity of the initial billet shell's thickness, surface quality, and the safety and stability of the entire continuous casting process. The temperature difference between the crystallizer cooling water (ΔT, i.e., the difference between the inlet and outlet water temperatures) is one of the most direct and sensitive process parameters reflecting the cooling intensity, thermal balance, and whether the copper plate's heat load is within a reasonable range. The industry generally considers controlling the temperature difference between the crystallizer's inlet and outlet water within a certain range (usually ≤8~10℃, depending on the steel grade, cross-section, and characteristics of the protective slag) as a basic requirement for ensuring billet quality and preventing major production accidents.

[0003] When the temperature difference in the crystallizer is consistently or momentarily high, it can lead to multiple serious consequences: First, the temperature of the hot surface of the copper plate increases, increasing thermal stress and making it prone to deformation, cracking, or even localized burning. Second, the high temperature difference accelerates the deposition rate of scale such as calcium carbonate and silicates in the cooling water channels, rapidly increasing the thermal resistance of the scale layer and further weakening the heat exchange capacity, forming a typical vicious cycle. Third, the billet shell growth rate slows down, and the liquid core becomes too long, making it prone to surface and subsurface defects such as longitudinal cracks, transverse cracks, star-shaped cracks, and subcutaneous pores during vibration or straightening. In the most severe cases, when the billet shell is locally too thin and its strength is insufficient to withstand the static pressure of molten steel, adhesive leakage or through-leakage accidents will occur, leading to serious equipment damage, prolonged production interruption, huge economic losses, and even major safety accidents.

[0004] Conversely, excessive or uneven cooling (especially overly strong cooling on narrow surfaces) can lead to excessively thick billet shells, overcooling at the corners, and internal stress concentration, causing problems such as corner cracks, central cracks, or bulging deformation. In actual production, the drawing speed is the most important dynamic variable affecting the heat load of the crystallizer. Increasing the drawing speed significantly increases the heat transferred to the crystallizer per unit time; if the water flow adjustment lags behind, the temperature difference will rapidly exceed the standard. If the water flow is not reduced in time after the drawing speed is reduced, it will also lead to overcooling, affecting the uniformity of the billet shell quality.

[0005] Traditional crystallizer water flow control often relies on fixed parameter tables or manual experience-based adjustments, which presents the following prominent problems: 1) The response speed to non-steady-state conditions such as fluctuations in casting speed, switching of steel grades, and changes in the consumption of protective slag is slow. Operators usually need to observe the temperature difference and then make manual adjustments, which has a significant lag. 2) The heat load difference between the wide side (curved side) and the narrow side (side) is large (the heat input of the wide side is usually much higher than that of the narrow side), but traditional regulation often uses uniform water volume or simple proportional adjustment, which makes it difficult to achieve precise zone control; 3) The lack of an effective multi-level protection mechanism means that when the water volume has been increased to the upper limit and the temperature still cannot be controlled, the only option is to manually reduce the speed or stop the machine, which increases the operational risk and production fluctuations. 4) The adjustment strategy lacks standardization and intelligence, relies on personal experience, and is prone to over-adjustment or under-adjustment, resulting in large fluctuations in billet quality, decline in the quality of the first and last billets, and limited hot delivery rate.

[0006] Therefore, developing an intelligent adjustment method that can monitor the independent temperature difference between wide and narrow surfaces in real time, automatically increase the water volume of each zone step by step, and automatically reduce the set casting speed when the adjustment limit is reached is of great significance for improving the dynamic adaptability of the continuous casting process, ensuring production safety, stabilizing the quality of the cast billet, and increasing the hot delivery rate. Summary of the Invention

[0007] In view of this, the purpose of this invention is to solve the above problems and provide a method for automatically adjusting the water volume of the crystallizer to regulate the water temperature difference. This method achieves rapid, adaptive, and precise matching of cooling intensity through control logic such as default water volume setting for different drawing speeds, independent temperature difference monitoring for wide and narrow surfaces, step-by-step incremental water volume adjustment, and linkage reduction of drawing speed in case of abnormalities.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A method for automatically adjusting the water flow in a crystallizer to regulate the water temperature difference includes: Set the default cooling water flow rate for the wide and narrow faces of the crystallizer according to the continuous casting speed; Real-time acquisition of the temperature difference between the inlet and outlet water at the wide side and the narrow side of the crystallizer; When the temperature difference between the inlet and outlet water of the wide face is greater than the first preset temperature difference threshold, the flow rate of the cooling water of the wide face is adjusted at least once, increasing by the first preset water volume value each time, and waiting for the first preset time interval after adjustment. If the temperature difference between the inlet and outlet water of the wide face is still greater than the first preset temperature difference threshold, the next adjustment is performed. If the temperature difference between the inlet and outlet water of the wide face is still greater than the first preset temperature difference threshold after a preset number of adjustment steps, the continuous casting speed setting value is reduced. When the temperature difference between the inlet and outlet water of the narrow face is greater than the second preset temperature difference threshold, the cooling water flow rate of the narrow face is adjusted at least once, increasing by the second preset water flow rate value each time, and waiting for the second preset time interval after adjustment. If the temperature difference between the inlet and outlet water of the narrow face is still greater than the second preset temperature difference threshold, the next adjustment is performed. If the temperature difference between the inlet and outlet water of the narrow face is still greater than the second preset temperature difference threshold after a preset number of adjustments, the continuous casting speed setting value is reduced.

[0009] Furthermore, when the temperature difference between the inlet and outlet water on the wide side is less than or equal to the first preset temperature difference threshold and the temperature difference between the inlet and outlet water on the narrow side is less than or equal to the second preset temperature difference threshold, the current cooling water flow rate remains unchanged.

[0010] Furthermore, the default cooling water flow rate is set to at least two levels based on whether the pulling speed reaches or exceeds a preset pulling speed threshold, wherein the water volume of the wide and narrow sides of the higher pulling speed level is greater than the corresponding water volume of the lower pulling speed level.

[0011] Furthermore, the preset pulling speed threshold is 1.3 m / min.

[0012] Furthermore, both the first preset temperature difference threshold and the second preset temperature difference threshold are 9°C.

[0013] Furthermore, the first preset water volume value for each increment of the wide side is greater than the second preset water volume value for each increment of the narrow side.

[0014] Furthermore, the feature is that the flow rate of the wide-face cooling water increases by 50 L / min each time, and the flow rate of the narrow-face cooling water increases by 30 L / min each time.

[0015] Furthermore, both the first preset time interval and the second preset time interval are 1 min.

[0016] Furthermore, the reduction in the continuous casting speed setting is 0.1 m / min.

[0017] Furthermore, the method also includes issuing a visual warning signal when abnormal temperature differences occur.

[0018] The beneficial effects of this invention are as follows: 1. Dynamic and precise zoning adjustment of the cooling water volume in the crystallizer has been achieved. By monitoring the inlet and outlet water temperature difference of the wide side (arc surface) and narrow side (side surface) in real time, and implementing a step-by-step incremental adjustment strategy for each temperature difference independently (the wide side uses a larger step increment to quickly respond to its higher heat load, while the narrow side uses a smaller step increment for fine adjustment), the cooling intensity of the corresponding area can be effectively enhanced in a short time after the temperature difference exceeds the limit, so that the temperature difference quickly returns to the safe range. This effectively avoids the problem of mismatched cooling between the wide and narrow sides caused by the traditional uniform adjustment method, and significantly improves the uniformity of the billet shell thickness and the consistency of surface quality.

[0019] 2. A multi-level overload protection mechanism of "increasing water first, then decreasing speed" is established. When the temperature difference still fails to recover after stepwise increasing the adjustment to a preset number of times (twice in this embodiment), the pulling speed setting is automatically reduced (preferably by 0.1 m / min), thereby reducing the heat input load of the crystallizer from the source. This avoids the dilemma that simply increasing the water volume may lead to excessively high water system pressure, increased energy consumption, or the inability to control the temperature even when the water volume has reached its limit. This mechanism greatly improves the system's fault tolerance to extreme operating conditions and production safety, and reduces the probability of leakage accidents.

[0020] 3. Improved adaptability to casting speed fluctuations and production stability. The default water volume is divided into at least two levels based on whether the casting speed reaches or exceeds a preset threshold (preferably 1.3 m / min). The higher casting speed level corresponds to a higher water volume across the wide and narrow face, ensuring that the initial parameters are basically matched with the current heat load. Simultaneously, a visual warning signal is issued in case of abnormalities, facilitating rapid operator intervention. The lower casting speed level can be preferentially used as the starting value initially, further reducing the risk of excessive temperature differences during unsteady-state stages. These measures collectively reduce the quality fluctuations at the beginning and end of the cast billet caused by frequent casting speed changes, significantly reducing the incidence of common defects such as surface longitudinal cracks, corner cracks, and bulging.

[0021] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Detailed Implementation

[0022] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments are only illustrative of the basic concept of the present invention; in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0023] Example 1 This embodiment provides a method for automatically adjusting the water flow in the crystallizer to regulate the water temperature difference, applied to a slab continuous casting machine (including No. 1 and No. 2 continuous casting machines). The execution process is as follows: First, set the default cooling water flow rates for the wide (arc) and narrow (side) faces of the crystallizer based on the continuous casting speed. Specific parameters are as follows: When the casting speed is set to ≥1.3 m / min, the water flow rate of the wide face (arc surface) of the No.1 continuous casting machine is 3900 L / min and the water flow rate of the narrow face (side) is 550 L / min; the water flow rate of the wide face (arc surface) of the No.2 continuous casting machine is 3800 L / min and the water flow rate of the narrow face (side) is 630 L / min. When the casting speed is set to <1.3 m / min, the water flow rate of the wide face (arc surface) of the No. 1 continuous casting machine is 3700 L / min and the water flow rate of the narrow face (side) is 550 L / min; the water flow rate of the wide face (arc surface) of the No. 2 continuous casting machine is 3600 L / min and the water flow rate of the narrow face (side) is 550 L / min.

[0024] The system automatically selects the parameter values ​​corresponding to the low pulling speed (<1.3 m / min) as the default value. At the same time, the crystallizer inlet water temperature is controlled at 25-35℃ (40℃ is allowed in summer), the target inlet water temperature is 30-35℃, and the inlet and outlet water temperature difference is controlled to be ≤10℃.

[0025] Secondly, the temperature difference between the inlet and outlet water on the wide side and the narrow side of the crystallizer is obtained in real time.

[0026] When the temperature difference between the inlet and outlet water of both the wide and narrow sides is ≤9℃, the current cooling water flow rate remains unchanged.

[0027] When the temperature difference between the inlet and outlet water of the wide face is >9℃, the cooling water flow rate of the wide face is adjusted step by step: first, add water to the wide face at 50 L / min, and after timing for 1 minute, re-judge the temperature difference; if it is still >9℃, continue to add water to the wide face at 50 L / min, and after timing for 1 minute again, if it is still >9℃, the set pull speed is automatically reduced by 0.1 m / min.

[0028] When the temperature difference between the inlet and outlet water of the narrow face is >9℃, the cooling water flow rate of the narrow face is adjusted step by step: first, add water to the narrow face at 30 L / min, and re-judge the temperature difference after 1 minute; if it is still >9℃, continue to add water to the narrow face at 30 L / min, and if it is still >9℃ after 1 minute, the set pull speed is automatically reduced by 0.1 m / min.

[0029] When abnormal temperature occurs, the system issues a flashing color visual warning signal and provides a default value modification window for operators to adjust according to actual process needs.

[0030] In practical applications, the crystallizer cooling system adopts an independent water control method for the wide surface (arc surface) and the narrow surface (side surface), and all adjustment actions are automatically executed by PLC or DCS.

[0031] 1. Set the default cooling water flow rate for the wide and narrow faces of the crystallizer according to the continuous casting speed. The system acquires the current continuous casting speed v (m / min) in real time and automatically selects the default cooling water flow rate accordingly, with two settings: When the pulling speed v ≥ 1.3 m / min (higher pulling speed setting): #1 Continuous Casting Machine: Default water flow rate for wide face is 3900 L / min, and for narrow face it is 550 L / min; #2 Continuous Casting Machine: Default water flow rate for wide face is 3800 L / min, and for narrow face it is 630 L / min.

[0032] When the pulling speed v < 1.3 m / min (lower pulling speed setting): #1 Continuous Casting Machine: Default water flow rate for wide face is 3700 L / min, and for narrow face it is 550 L / min; #2 Continuous Casting Machine: Default water flow rate for wide face is 3600 L / min, and for narrow face it is 550 L / min.

[0033] When the system is powered on and initialized or when process parameters are reset, it automatically prioritizes the water volume corresponding to the lower pumping speed (v<1.3 m / min) as the initial default value. Then, it automatically switches to the corresponding speed based on the real-time pumping speed.

[0034] 2. Real-time acquisition of the temperature difference between the inlet and outlet water at the wide end and the narrow end of the crystallizer. The system collects temperature data from the inlet and outlet water mains of the crystallizer and from independent temperature measurement points on the wide and narrow sides, with a sampling period of no more than 5 seconds, and calculates the following respectively: ΔT_wide_face = outlet water temperature of wide_face – inlet water temperature ΔTnarrow face = Narrow face outlet water temperature – Inlet water temperature The target for controlling the inlet water temperature is 25-35℃ (maximum of 40℃ is allowed in summer), and the overall temperature difference process target is ≤10℃, but this method uses 9℃ as the abnormal trigger threshold.

[0035] 3. Adjustment when the temperature difference between the inlet and outlet water of the wide face exceeds the first preset temperature difference threshold. When ΔT wide area > 9℃, perform the following step-by-step incremental adjustment: First increment: Increase the wide-face cooling water flow rate by the first preset water volume value of 50 L / min (based on the current flow rate), and wait for the first preset time interval of 1 min after the adjustment command is issued; Recalculate the ΔT width after 1 minute: If ΔT (wide surface temperature) is ≤9℃, stop adding water to the wide surface and maintain the current water level. If ΔT wide area is still >9℃, then perform the second increment: increase the cooling water flow rate of the wide area by 50 L / min again (cumulative increase of 100 L / min), and wait for 1 min again after adjustment; The second assessment will be made after a 1-minute wait. If ΔT (wide surface temperature) is ≤9℃, stop adding water and maintain the current water level. If the ΔT wide face temperature is still >9℃ (i.e., it has not recovered after two preset increments of adjustment), the continuous casting speed setting will be automatically reduced by 0.1 m / min, while the currently increased water volume will remain unchanged, and a visual warning signal will be triggered.

[0036] 4. Adjustment when the temperature difference between the inlet and outlet water at the narrow face exceeds the second preset temperature difference threshold. When ΔTnarrow face > 9℃, the narrow face adjustment logic is executed independently (in parallel with the wide face, without mutual interference): First increment: Increase the cooling water flow rate of the narrow face by 30 L / min to the second preset water flow value, and wait for the second preset time interval of 1 min after adjustment; Wait 1 minute to make a judgment: If ΔTnarrow surface ≤ 9℃, stop adding water to the narrow surface; If the temperature is still >9℃, then increase it for the second time: increase the cooling water flow rate of the narrow face by 30 L / min again (cumulative increase of 60 L / min), and wait for 1 minute after adjustment; The second assessment will be made after a 1-minute wait. If ΔT (narrow surface temperature) ≤ 9℃, stop adding water; If the temperature remains above 9℃, the current pulling speed setting will be automatically reduced by 0.1 m / min to maintain the current water volume, and a visual warning signal will be issued.

[0037] 5. When the temperature difference between the inlet and outlet water on the wide side is less than or equal to the first preset temperature difference threshold and the temperature difference between the inlet and outlet water on the narrow side is less than or equal to the second preset temperature difference threshold. As long as ΔT wide face ≤ 9℃ and ΔT narrow face ≤ 9℃, regardless of whether the current water volume has been adjusted by adding water, the system will maintain the current cooling water flow rate and continue to operate at the existing value until the next temperature difference abnormality is triggered.

[0038] 6. Visual warning signal: As long as the first water addition is triggered in any area of ​​the wide or narrow face, the corresponding area will be highlighted on the HMI screen by flashing color (red is recommended) + text alarm. At the same time, the abnormal start time, speed of addition, temperature difference and water volume change curve will be recorded for easy post-event analysis.

[0039] Default value modification window: The system provides an interface for authorized process personnel to edit default water volume parameters. It supports saving multiple sets of process parameter tables for different continuous casting machine types, billet cross sections, steel grades, and protective slag systems, enabling rapid switching and continuous optimization.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for automatically adjusting the water flow in a crystallizer to regulate the water temperature difference, characterized in that, include: Set the default cooling water flow rate for the wide and narrow faces of the crystallizer according to the continuous casting speed; Real-time acquisition of the temperature difference between the inlet and outlet water at the wide side and the narrow side of the crystallizer; When the temperature difference between the inlet and outlet water of the wide face is greater than the first preset temperature difference threshold, the cooling water flow rate of the wide face is adjusted at least once, increasing by the first preset water flow rate each time, and waiting for the first preset time interval after adjustment. If the temperature difference between the inlet and outlet water of the wide face is still greater than the first preset temperature difference threshold, the next adjustment is performed. If the temperature difference between the inlet and outlet water of the wide face is still greater than the first preset temperature difference threshold after a preset number of incremental adjustments, then the continuous casting speed setting value is reduced. When the temperature difference between the inlet and outlet water of the narrow face is greater than the second preset temperature difference threshold, the cooling water flow rate of the narrow face is adjusted at least once, increasing by the second preset water flow rate value each time, and waiting for the second preset time interval after adjustment. If the temperature difference between the inlet and outlet water of the narrow face is still greater than the second preset temperature difference threshold, the next adjustment is performed. If the temperature difference between the inlet and outlet water of the narrow face is still greater than the second preset temperature difference threshold after a preset number of adjustments, the continuous casting speed setting value is reduced.

2. The method for automatically adjusting the water volume in the crystallizer to regulate the water temperature difference according to claim 1, characterized in that, When the temperature difference between the inlet and outlet water on the wide side is less than or equal to the first preset temperature difference threshold and the temperature difference between the inlet and outlet water on the narrow side is less than or equal to the second preset temperature difference threshold, the current cooling water flow rate remains unchanged.

3. The method for automatically adjusting the water volume in the crystallizer to regulate the water temperature difference according to claim 1 or 2, characterized in that, The default cooling water flow rate is set in at least two levels based on whether the pulling speed reaches or exceeds the preset pulling speed threshold. The water volume of the wide and narrow sides of the higher pulling speed level is greater than the corresponding water volume of the lower pulling speed level.

4. The method for automatically adjusting the water volume in the crystallizer to regulate the water temperature difference according to claim 3, characterized in that, The preset pulling speed threshold is 1.3 m / min.

5. The method for automatically adjusting the water volume in the crystallizer to regulate the water temperature difference according to claim 1, characterized in that, Both the first preset temperature difference threshold and the second preset temperature difference threshold are 9°C.

6. The method for automatically adjusting the water volume in the crystallizer to regulate the water temperature difference according to claim 1, characterized in that, The first preset water volume value for each increment of the wide side is greater than the second preset water volume value for each increment of the narrow side.

7. The method for automatically adjusting the water volume in the crystallizer to regulate the water temperature difference according to claim 1 or 6, characterized in that, The flow rate of the wide-face cooling water increases by 50 L / min each time, and the flow rate of the narrow-face cooling water increases by 30 L / min each time.

8. The method for automatically adjusting the water volume in the crystallizer to regulate the water temperature difference according to claim 1, characterized in that, Both the first preset time interval and the second preset time interval are 1 min.

9. The method for automatically adjusting the water volume in the crystallizer to regulate the water temperature difference according to claim 1, characterized in that, The reduction in the continuous casting speed setting is 0.1 m / min.

10. The method for automatically adjusting the water volume in the crystallizer to regulate the water temperature difference according to any one of claims 1 to 9, characterized in that, Also includes: When abnormal temperature differences occur, a visual warning signal is issued.