A tundish water inlet flow control system and method

Abstract

The invention discloses a tundish water nozzle flow control system and method, which can adjust the current of the electromagnetic flow control mechanism coil in real time according to the liquid level of the molten steel in the crystallizer, thereby adjusting the electromagnetic field in real time, and realizing the precise control of the flow rate of the molten steel in the water nozzle. This structure and control method are not limited by the size of the water nozzle, and can be applicable to water nozzles of different sizes. At the same time, the adjustment of the flow rate of the molten steel in the water nozzle is realized through electrical signals, and there is no mechanical structure, and the advantages of fast response speed, high control accuracy, no material loss, continuous production, energy saving and environmental protection can be realized.

Description

Technical Field

[0001] The invention belongs to the technology of flow control of water inlet of continuous casting metallurgy tundish, and in particular relates to an electromagnetic tundish water inlet flow control system and method. Background Art

[0002] In order to adapt to the instability of the drawing speed in continuous casting production, it is necessary to adjust the speed of the molten steel flowing out of the tundish water outlet in real time. The speed of the molten steel flowing through the tundish water outlet should be different for different billet drawing speeds, so as to ensure the continuity of the entire continuous casting production. On the other hand, the quality of the continuous casting billet is closely related to the control accuracy of the height of the molten steel in the crystallizer. The more accurate the height control of the molten steel in the crystallizer, the better the quality of the billet. Therefore, accurate control of the height of the molten steel in the crystallizer can greatly ensure the quality of the billet produced by continuous casting. Therefore, it is very necessary to develop a tundish water outlet flow control technology that can be applied to tundish water outlets of different sizes and types and can automatically and accurately control the height of the crystallizer liquid level.

[0003] The existing technology for controlling the flow rate of the tundish water inlet mainly adopts the stopper mechanism method, which uses a hydraulic system or an electric system to control the gap between the stopper and the water inlet to control the flow rate of the tundish water inlet. For example, the patent for the invention of a stopper flow control structure with a stopper rod and a water inlet for safe matching is CN104646653B; the patent for the invention of a stopper rod flow control structure with a stopper rod and a water inlet for safe matching is CN111136255A; the patent for the invention of a flow control structure for suppressing slag from falling from a tundish is CN111136255A. The typical structure of the stopper mechanism is as follows: Figure 1 and 2 As shown, 1-stopper rod, 2-tundish, 3-water inlet, 4-molten steel, the flow rate of the molten steel in the tundish water inlet 3 is controlled by controlling the gap between the stopper rod 1 and the water inlet 3, thereby controlling the liquid level of the molten steel in the crystallizer (the molten steel in the tundish flows into the crystallizer through the water inlet). This structure and control method mainly have the following disadvantages:

[0004] (1) The mechanical structure is complex, the response is not timely, the mechanical accuracy is poor, the control effect is not ideal, and the control accuracy of the crystallizer liquid level is poor;

[0005] (2) Since the stopper rod itself needs to have a certain strength and a certain diameter, it is only suitable for larger tundish water outlets, not for smaller tundish water outlets, and has poor adaptability;

[0006] (3) The stopper rod needs to be replaced every time the tundish is replaced, which increases the operation replacement time, is not conducive to continuous production, and has a large amount of waste, which is not conducive to environmental protection. Summary of the invention

[0007] The object of the present invention is to provide a tundish water inlet flow control system and method to solve the problems of slow response, low control accuracy and poor adaptability of existing flow control mechanisms.

[0008] The present invention solves the above-mentioned technical problems through the following technical solutions: a tundish water inlet flow control system, comprising a tundish and a water inlet arranged on the bottom wall of the tundish, characterized in that it also comprises: an electromagnetic flow control mechanism, a liquid level detector and a control device; the water inlet passes through the electromagnetic flow control mechanism, and the liquid level detector is arranged on the crystallizer; the control device adjusts the coil current of the electromagnetic flow control mechanism according to the liquid level signal detected by the liquid level detector, so as to control the flow rate of the molten steel in the water inlet.

[0009] The electromagnetic tundish water nozzle flow control system of the present invention has a control device that adjusts the current of the electromagnetic flow control mechanism coil in real time according to the liquid level in the crystallizer, thereby adjusting the electromagnetic field in real time, thereby achieving precise control of the flow rate of the molten steel in the water nozzle. This structural form is not limited by the size of the water nozzle and can be applied to water nozzles of different sizes. At the same time, the flow rate of the molten steel in the water nozzle is adjusted by electrical signals. It has no mechanical structure and has the advantages of fast response speed, high control accuracy, no material loss, and can achieve continuous production and energy saving and environmental protection.

[0010] Furthermore, the electromagnetic flow control mechanism includes an annular iron core, a first coil and a second coil; a first salient pole and a second salient pole are respectively provided on opposite sides of the annular iron core, and a pair of magnetic poles are formed by the first salient pole and the second salient pole; the first coil and the second coil are respectively wound on the first salient pole and the second salient pole; the first coil and the second coil are respectively connected to the control device, and the water outlet passes through the gap between the first salient pole and the second salient pole.

[0011] The annular iron core can concentrate the magnetic lines of force and form a closed magnetic circuit. The salient pole structure is used at the water inlet, which is more conducive to the concentration of the magnetic lines of force at the water inlet, and passes through the water inlet of the middle ladle to form a closed magnetic circuit, thereby enhancing the force of the electromagnetic field on the molten steel in the water inlet; the first coil and the second coil are passed with current in the same direction, and the control device adjusts the current of the first coil and the second coil in real time according to the crystallizer liquid level signal, thereby realizing precise control of the flow rate of the molten steel in the water inlet.

[0012] Furthermore, there are multiple water outlets, and there are multiple pairs of magnetic poles, and each pair of magnetic poles corresponds to one water outlet.

[0013] In order to ensure the uniformity of the flow of molten steel in the tundish into the crystallizer, a multi-inlet structure is adopted. The structural dimensions of each inlet are the same. The flow rate of molten steel in multiple tundish inlets can be controlled simultaneously through multiple pairs of magnetic poles in an electromagnetic flow control mechanism.

[0014] Furthermore, the liquid level detector adopts an eddy current sensor, which can dynamically and non-contactly measure the distance between the measured metal liquid level and the probe surface, thereby obtaining the real-time height of the molten steel in the crystallizer. The non-contact detection method avoids the influence of the detector itself on the liquid level, improves the detection accuracy of the liquid level, and indirectly improves the control accuracy of the molten steel flow rate in the water nozzle.

[0015] Furthermore, the control device is a control module with S7-300PLC as its core.

[0016] The present invention further provides a tundish water inlet flow control method, which is applied to the tundish water inlet flow control system as described above, comprising:

[0017] Step 1: Obtain the liquid level of molten steel in the crystallizer;

[0018] Step 2: Compare the liquid level in step 1 with the set height, and adjust the current of the first coil and the second coil according to the comparison difference, change the intensity of the electromagnetic field, and control the flow rate of the molten steel in the nozzle.

[0019] Furthermore, in step 2, the liquid level difference is obtained by performing a PID control algorithm on the comparison difference, and the liquid level difference is converted into a current signal and input into the first coil and the second coil.

[0020] Different liquid level height differences output current signals of different sizes. The current sizes of the first coil and the second coil are adjusted by current signals of different sizes to maintain the liquid level of the molten steel in the crystallizer at a set height. The entire control process is closed-loop control with high control accuracy and fast response.

[0021] Beneficial Effects

[0022] Compared with the prior art, the present invention provides a tundish water inlet flow control system and method, which adjusts the current of the electromagnetic flow control mechanism coil in real time according to the liquid level of the molten steel in the crystallizer, thereby adjusting the electromagnetic field size in real time, and realizing precise control of the flow rate of the molten steel in the water inlet. This structural form is not limited by the size of the water inlet and can be suitable for water inlets of different sizes. At the same time, the flow rate of the molten steel in the water inlet is adjusted by electrical signals. It has no mechanical structure and has the advantages of fast response speed, high control accuracy, no material loss, and can realize continuous production and energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a schematic diagram of the structure of a stopper-type flow control device in the background technology of the present invention;

[0025] Figure 2 is a cross-sectional view of a stopper-type flow control device in the background technology of the present invention;

[0026] Figure 3 2 is a schematic structural diagram of an electromagnetic tundish water inlet flow control system according to an embodiment of the present invention;

[0027] Figure 4 is a cross-sectional view of an electromagnetic tundish water inlet flow control system according to an embodiment of the present invention;

[0028] Figure 5 is a schematic structural diagram of an electromagnetic flow control mechanism in an embodiment of the present invention;

[0029] Figure 6 is a top view of the electromagnetic flow control mechanism in an embodiment of the present invention;

[0030] Figure 7 Schematic diagram of the power-on state of the electromagnetic tundish water inlet flow control system in an embodiment of the present invention;

[0031] Figure 8 It is a closed-loop control circuit of the electromagnetic tundish water inlet flow control method in the embodiment of the present invention;

[0032] Among them, 1-stopper rod, 2-tundish, 3-water nozzle, 4-molten steel, 5-electromagnetic flow control mechanism, 51-second coil, 52-second salient pole, 53-first coil, 54-first salient pole, 55-annular iron core, 6-magnetic pole, A-the distance between the first salient pole and the second salient pole, B-the distance between the opposite sides of the annular iron core, F-magnetic lines of force, I-current direction. DETAILED DESCRIPTION

[0033] The following is a clear and complete description of the technical solutions in the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] like Figure 3 and 4As shown, a tundish water inlet flow control system provided by the present invention comprises a tundish 2, a water inlet 3 arranged on the bottom wall of the tundish 2, an electromagnetic flow control mechanism 5, a liquid level detector and a control device; the water inlet 3 passes through the electromagnetic flow control mechanism 5, and the liquid level detector is arranged on the crystallizer; the coil of the electromagnetic flow control mechanism 5 and the liquid level detector are respectively connected to the control device; the control device adjusts the coil current of the electromagnetic flow control mechanism 5 according to the liquid level signal detected by the liquid level detector, so as to control the flow rate of the molten steel 4 in the water inlet 3.

[0035] like Figure 5 and 6 As shown, the electromagnetic flow control mechanism 5 includes an annular iron core 55, a first coil 53 and a second coil 51; a first salient pole 54 and a second salient pole 52 are respectively provided on opposite sides of the annular iron core 55, and a pair of NS magnetic poles 6 are formed by the first salient pole 54 and the second salient pole 52; the first coil 53 and the second coil 51 are respectively wound on the first salient pole 54 and the second salient pole 52; the first coil 53 and the second coil 51 are respectively connected to the control device, and the water inlet 3 passes through the gap between the first salient pole 54 and the second salient pole 52.

[0036] In the short-process continuous casting technology, in order to ensure the uniformity of the molten steel in the tundish 2 flowing into the crystallizer, a multi-water inlet structure is adopted, that is, a plurality of water inlets 3 are provided on the bottom wall of the tundish 2, and the structural dimensions of each water inlet 3 are the same. There are multiple pairs of magnetic poles 6 corresponding to the water inlets 3, and the number of water inlets 3 is the same as the number of magnetic poles 6. Figure 6 As shown, there are three nozzles 3 and three pairs of magnetic poles 6, each nozzle 3 has an inner diameter of about 10 mm, and multiple pairs of magnetic poles 6 in an electromagnetic flow control mechanism 5 can simultaneously control the flow rate of molten steel 4 in multiple nozzles 3 of the tundish 2. This structure and control method has no mechanical structure, fast response speed, high control accuracy, no material loss, and can achieve continuous production, energy saving and environmental protection, etc. In this structure with multiple nozzles and small nozzles, the stopper type flow control device cannot meet the use requirements, because the stopper itself needs to have a certain strength and a certain diameter.

[0037] In this embodiment, the liquid level detector adopts an eddy current sensor. The eddy current sensor selects a single-channel intelligent high-precision eddyNCDT 3300 series multifunctional eddy current sensor. The eddy current sensor is small in size and highly sensitive. It can dynamically and non-contactly measure the distance between the measured metal liquid level and the probe surface, thereby obtaining the real-time height of the molten steel in the crystallizer. The non-contact detection method avoids the influence of the detector itself on the liquid level, improves the detection accuracy of the liquid level, and indirectly improves the control accuracy of the flow rate of the molten steel in the water inlet 3.

[0038] The control device is a control module with S7-300PLC as the core. S7-300 is a general-purpose PLC that can be used in various applications in automation engineering, especially in manufacturing engineering. S7-300PLC has various CPU modules with different performance levels available. The standard CPU provides a wide range of basic functions, such as instruction execution, I / O reading and writing, and communication through MPI and CP modules. The compact CPU has integrated I / P and has high-speed calculation, frequency measurement, positioning, PID adjustment and other counting functions.

[0039] like Figure 6 and 7 As shown, during operation, the first coil 53 and the second coil 51 are energized (the current direction I is the same), and the magnetic lines of force F excited by the energized coils will form multiple closed-loop magnetic circuits along the annular core 55. Since the annular core 55 at the water inlet 3 adopts a salient pole structure, that is, the spacing A between the first salient pole 54 and the second salient pole 52 is smaller than the spacing B between the opposite sides of the annular core 55, this is conducive to the magnetic lines of force 11 passing through the salient poles first, and is more conducive to the concentrated magnetic lines of force F passing through the water inlet 3 of the tundish 2 and forming the NS magnetic pole 6, thereby increasing the force of the electromagnetic field on the molten steel 4 in the water inlet 3.

[0040] The working principle of the tundish water inlet flow control system of the present invention is as follows: the change of the liquid level of the molten steel in the crystallizer causes the change of the gap between the eddy current sensor and the liquid level, thereby causing the change of the eddy current signal. The liquid level height (real-time liquid level) of the molten steel in the crystallizer is calculated according to the size of the eddy current signal. The control module compares the liquid level with the set height and converts the comparison result into a current signal. The current signal is input to the first coil 53 and the second coil 51 of the electromagnetic flow control mechanism 5, and the current size of the first coil 53 and the second coil 51 is changed, thereby changing the strength of the electromagnetic field, and then changing the force (restraining force) on the molten steel in the water inlet 3, thereby realizing the control of the flow rate of the molten steel in the water inlet 3, so that the liquid level of the molten steel in the crystallizer is maintained stable. When the comparison result between the liquid level and the set height is a positive deviation, the larger the positive deviation is, the higher the actual liquid level is than the set height, and a large current signal is output (the positive deviation is positively correlated with the current size), the magnetic field strength is enhanced, the restraining force on the molten steel is increased, the flow rate of the molten steel is reduced, and the actual liquid level is reduced to the set height as soon as possible; when the comparison result between the liquid level and the set height is a negative deviation, the larger the negative deviation is, the lower the actual liquid level is than the set height, and a small current signal is output (the negative deviation is negatively correlated with the current size), the magnetic field strength is reduced, the restraining force on the molten steel is reduced, the flow rate of the molten steel is increased, and the actual liquid level is increased to the set height as soon as possible.

[0041] The present invention further provides a tundish water inlet flow control method, which is applied to the tundish water inlet flow control system as described above, comprising:

[0042] Step 1: Obtain the liquid level of molten steel in the crystallizer;

[0043] Step 2: Compare the liquid level in step 1 with the set height, and adjust the current of the first coil 53 and the second coil 51 according to the comparison difference to change the strength of the electromagnetic field to control the flow rate of the molten steel 4 in the nozzle 3.

[0044] like Figure 8 As shown, in step 2, the difference between the liquid level and the set height is subjected to a PID control algorithm to obtain the liquid level difference, which is converted into a current signal and input into the first coil 53 and the second coil 51 to change the flow rate of the molten steel 4 in the water inlet 3, thereby changing the liquid level in the crystallizer. The liquid level is collected in real time according to the sampling period, and the flow rate of the molten steel 4 in the water inlet 3 is constantly changed by comparing with the set height to maintain a stable liquid level in the crystallizer, accurately control the liquid level in the crystallizer, meet the requirements of different ingots and different pulling speeds of the continuous casting machine, and improve the quality of the ingots. The entire control process is a closed-loop control with high control accuracy and fast response.

[0045] The tundish water inlet flow control system and flow control method provided by the present invention utilize the particularity of the flowing liquid in the water inlet (molten steel) to adjust the strength of the electromagnetic field through the liquid level signal in the crystallizer to adjust the inhibitory force on the molten steel (non-conductive liquid has no inhibitory effect), thereby achieving precise control of the flow rate of the molten steel in the water inlet. The system and method have no mechanical structure, have the advantages of fast response speed, high control accuracy, no material loss, and can achieve continuous production and energy saving and environmental protection. At the same time, this structure and control method are not limited by the size of the water inlet, and can be applicable to water inlets of different sizes, greatly improving adaptability.

[0046] What is disclosed above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or modifications within the technical scope disclosed in the present invention, which should be covered within the protection scope of the present invention.

Claims

1. A tundish nozzle flow control system, comprising a tundish and a plurality of nozzles arranged on the bottom wall of the tundish, characterized in that: Also includes: An electromagnetic flow control mechanism, a liquid level detector and a control device; the water inlet passes through the electromagnetic flow control mechanism, and the liquid level detector is arranged on the crystallizer; the control device adjusts the coil current of the electromagnetic flow control mechanism according to the liquid level signal detected by the liquid level detector, so as to control the flow rate of the molten steel in the water inlet; The electromagnetic flow control mechanism includes an annular iron core, a first coil and a second coil; a first salient pole and a second salient pole are respectively provided on opposite sides of the annular iron core, and the first salient pole and the second salient pole constitute a pair of magnetic poles; the first coil and the second coil are respectively wound on the first salient pole and the second salient pole; the first coil and the second coil are respectively connected to the control device, and the water outlet passes through the gap between the first salient pole and the second salient pole; there are multiple pairs of magnetic poles, and each pair of magnetic poles corresponds to a water outlet.

2. The tundish water inlet flow control system according to claim 1, characterized in that: The liquid level detector adopts an eddy current sensor.

3. The tundish water inlet flow control system according to claim 1 or 2, characterized in that: The control device is a control module with S7-300PLC as the core.

4. A tundish water inlet flow control method, applied to the tundish water inlet flow control system as claimed in any one of claims 1 to 3, characterized in that: include: Step 1: Obtain the liquid level of molten steel in the crystallizer; Step 2: Compare the liquid level in step 1 with the set height, and adjust the current of the first coil and the second coil according to the comparison difference, change the intensity of the electromagnetic field, and control the flow rate of the molten steel in the nozzle.

5. The method for controlling flow at a tundish nozzle according to claim 4, characterized in that: In the step 2, the liquid level difference is obtained by performing a PID control algorithm on the comparison difference, and the liquid level difference is converted into a current signal and input into the first coil and the second coil.

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