CN112231885A - Method for measuring slag amount of continuous casting tundish - Google Patents
Method for measuring slag amount of continuous casting tundish Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/20—Controlling or regulating processes or operations for removing cast stock
- B22D11/201—Controlling or regulating processes or operations for removing cast stock responsive to molten metal level or slag level
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Abstract
The invention discloses a method for measuring the slag amount of a continuous casting tundish, which is realized based on a device for measuring the slag amount of the continuous casting tundish, wherein the measuring device comprises a ladle turret pressure measuring head (4), a ladle weight detector (5), a steel slag detector (6), a water gap opening detector (7), a tundish weight detector (8), a process signal interface unit (9) and a data processing and calculating module (10); the measuring method comprises the following steps: step 1: calibrating covering agent slagging density rhoCAnd density rho of steel slag of steel ladlegAnd the amount S of slag flowing into the crystallizerR(ii) a Step 2: calculating the total slag quantity S of the tundish (3) through a data processing calculation module (10); and step 3: and (4) carrying out deviation correction on the total slag quantity S through a self-correction coefficient E. The method can accurately measure the slag amount of the tundish, provides reference for continuous casting production, and is favorable for improving the production quality of the casting blank.
Description
Technical Field
The invention relates to a method for measuring the slag quantity in continuous casting production, in particular to a method for measuring the slag quantity of a continuous casting tundish.
Background
In continuous casting production, molten steel firstly flows into a tundish from a ladle, then is distributed to each crystallizer from the tundish, and then is solidified and crystallized by the crystallizer and is cast into a casting blank. In the process that the molten steel flows into the tundish from the ladle, the liquid level of the molten steel in the ladle gradually descends along with the pouring, and when the pouring is finished, the steel slag in the ladle flows into the tundish through the long nozzle together with the molten steel to form slag. Excessive steel slag can not only reduce the cleanliness of molten steel, influence the quality of casting blanks, but also cause leakage accidents; but also can accelerate the corrosion of the refractory materials of the tundish, shorten the service life of the refractory materials, increase the weight of the slag shell of the tundish and influence the continuous casting production.
In the aspect of tundish slag quantity measurement, an operator is required to measure the thickness of the tundish slag layer by adopting a three-wire measurement method in the production of the prior art, and due to the reasons of severe operating conditions and environment, high labor intensity of the operator and the like, the measurement is few in practice, manual judgment is basically relied on, and the molten steel purity of the tundish cannot be well mastered. There is currently no relevant means for automatic prediction of slag quantity.
Chinese patent ZL 201510149593.2 discloses a method and a device for measuring the thickness of tundish slag of a continuous casting machine, wherein the method for measuring the thickness comprises the following steps: a winding step, a measuring step and a thickness determining step. The thickness measuring device includes: the device comprises a support frame, a first metal wire and a second metal wire; the supporting frame is rod-shaped and is provided with a clamping part and an inserting part in the vertical downward axial direction; the first wire and the second wire are wound on the insertion portion, and the first wire and the second wire form an overlapping area on the insertion portion. The invention integrates the method and the device of three metal wires to measure the thickness of the tundish slag layer, has simple operation and short measuring time, is essentially an improvement of a three-wire method, is still a manual measuring method and has lower measuring precision.
The document "study of tundish slag layer thickness measurement based on thermal analysis model and image processing" discloses a method based on thermal imaging, which is used for judging the layering condition of tundish steel slag, thereby more accurately measuring the slag thickness. However, the method is complex to implement, the temperature measuring rod at the front end of the method needs to be inserted into molten steel, the working environment is severe, and the maintenance cost is high.
Disclosure of Invention
The invention aims to provide a method for measuring the slag quantity of a continuous casting tundish, which can accurately measure the slag quantity of the tundish, provide reference for continuous casting production and is beneficial to improving the production quality of a casting blank.
The invention is realized by the following steps:
a method for measuring the slag amount of a continuous casting tundish is realized based on a device for measuring the slag amount of the continuous casting tundish, and the device for measuring the slag amount of the continuous casting tundish comprises a ladle turret pressure measuring head arranged on a ladle turret, a ladle weight detector connected with the ladle turret pressure measuring head, a steel slag detector arranged above a sliding nozzle, a nozzle opening detector arranged on the sliding nozzle, a tundish weight detector, a process signal interface unit and a data processing and calculating module; the output ends of the ladle weight detector, the steel slag detector, the water gap opening detector, the tundish weight detector and the process signal interface unit are respectively connected with the input end of the data processing and calculating module, the input end of the process signal interface unit is externally connected with input equipment, and the output end of the data processing and calculating module is externally connected with display equipment;
the measuring method comprises the following steps:
step 1: calibrating covering agent slagging density rhoCAnd density rho of steel slag of steel ladlegAnd the amount S of slag flowing into the crystallizerR；
Step 2: calculating the total slag amount S of the tundish through a data processing calculation module;
and step 3: and (4) carrying out deviation correction on the total slag quantity S through a self-correction coefficient E.
The covering agent slagging density rhoCThe calibration method specifically comprises the following steps:
step 1.11: in the continuous casting plan of steel grade, after the casting is finished, the molten steel is emptied, only the steel slag remains in the tundish, and the weight of the tundish detected by the weight detector of the tundish at the moment is considered as the weight W of the steel slag of the tundishCT；
Step 1.12: a pouring hole and a plurality of burner holes are formed in a cover of the tundish, after the tundish enters a casting position, a covering agent is put in through the burner holes, a long ladle nozzle is inserted into the casting hole for casting, and the tundish is divided into a plurality of areas through the burner holes and the casting hole;
step 1.13: calculating the average thickness h of the slag layer of each area of the tundishLiThe calculation formula is as follows:
hLi＝0.5βiL+hMINi
wherein i is the number of regions, i is 1,2,3,4,5, …, x, L is the width of the tundish; h isMINiIs the minimum slag layer thickness, beta, of the respective zonesiIs the slag layer gradient coefficient of each area;
step 1.14: according to the average thickness h of the slag layerLiCalculating the volume V of the slag layerCTThe area of the tundish 3 is SLThe calculation formula is as follows:
step 1.15: calculating the slag-forming density rho of the covering agentCThe calculation formula is as follows:
the gradient coefficient beta of the slag layeriThe value range of the compound is 2 to 5 percent。
The amount S of slag flowing into the crystallizerRThe calibration method specifically comprises the following steps:
step 1.21: after a continuous casting schedule is completed, the weight W of the steel slag in the crystallizer is measuredYAnd crystallizer covering agent input weight WYCTaking the weight W of the steel slag of the crystallizerYMinus crystallizer cover input weight WYCIs the weight of the steel slag flowing into the crystallizer;
step 1.22: calculating the amount S of slag flowing into the crystallizerRThe calculation formula is as follows:
wherein m is the number of ladle replacements in the continuous casting plan.
The step 2 also comprises the following sub-steps:
step 2.1: reading the initial slag quantity S0Initial amount of slag S0Is the amount of slag generated in the previous ladle casting in the same continuous casting plan;
step 2.2: reading the weight W of each bag of coating agentCAnd the number n of bags of covering agent put in the current casting plancCalculating the covering agent slagging amount SCThe calculation formula is as follows:
step 2.3: calculating the molten steel flow f at the water gap;
step 2.4: calculating the slag quantity S of the ladlePThe calculation formula is as follows:
wherein p is the water gap steel slag content, rho, detected by the steel slag detectorgThe steel ladle steel slag density;
step 2.5: calculating the amount S of slag generated by the current ladle1The calculation formula is as follows:
S1＝SC+SP-SR；
step 2.6: calculating the total slag quantity S in the tundish in the continuous casting plan, wherein the calculation formula is as follows:
S＝S0+S1。
in the step 2.1, if the current ladle is the ladle cast first in the continuous casting plan, the initial slag amount S is0Is 0.
The method for calculating the molten steel flow f of the water gap comprises the following specific steps:
step 2.3.1: judging the liquid level control mode of the tundish, if the liquid level of the tundish is manually controlled, fixing the opening of the sliding nozzle, and executing the step 2.3.2, if the liquid level of the tundish is automatically controlled, changing the opening of the sliding nozzle, and executing the step 2.3.4;
step 2.3.2: whenever the ladle weight W is not changed in the case where the opening of the sliding gate is not changedLDecrease Δ WTThen, a set of ladle weight time values is sampled until z sets, i.e.
Wherein j is 1,2, …, z-1, z>5; a ladle weight curve is fitted using a least squares method:
WL＝α1TW 2+α2TW+α3
wherein, TWFor stabilizing the casting time, it means the fixed time T from the opening of the sliding gate0Starting period of time, α1，α2，α3Is a constant;
step 2.3.3: when the sliding nozzle is used for deslagging, the molten steel flow f of the nozzle is calculated, and the step 2.4 is carried out, wherein the calculation formula is as follows:
step 2.3.4: opening degree of sliding gateWith variation and pull rate fLWithout change, by tundish weight WTAnd downstream pull rate fLTo calculate the molten steel flow f at the water gap, the calculation formula is as follows:
the step 3 comprises the following sub-steps:
step 3.1: after the last ladle of the continuous casting plan is finished, the molten steel in the tundish is completely emptied, and the weight of the tundish at the moment is considered as the total slag weight W generated by the whole casting planE；
Step 3.2: density of slag formation by covering agent rhoCCalculating the actual slag quantity SEThe calculation formula is as follows:
where ρ isCIs covering agent slagging density;
step 3.3: calculating the self-correction coefficient E after the current k +1 correctionk+1The calculation formula is as follows:
wherein, Δ E is a correction step length, Δ S is a threshold value for starting correction, and k is a correction frequency.
The correction step length delta E is less than 0.1Ek。
The threshold value Delta S of the opening correction is more than 0.1SE。
The invention realizes the measurement of the tundish slag amount by comprehensively calculating the flow condition of the continuous casting system and utilizing a soft measurement method, provides more accurate reference for the continuous casting system operator and is beneficial to improving the production quality of casting blanks.
Drawings
FIG. 1 is a schematic view of a measuring apparatus for the amount of slag in a continuous casting tundish;
FIG. 2 is a flow chart of the method for measuring the amount of slag in a continuous casting tundish according to the present invention;
FIG. 3 is a schematic view of a tundish partition in the method for measuring the amount of slag in a continuous casting tundish of the present invention.
In the figure, 1 steel ladle, 2 sliding water gap, 3 tundish, 31 nozzle hole, 32 casting hole, 4 steel ladle rotary table pressure measuring head, 5 steel ladle weight detector, 6 steel slag detector, 7 water gap opening detector, 8 tundish weight detector, 9 process signal interface unit and 10 data processing and calculating module.
Detailed Description
The invention is further described with reference to the following figures and specific examples.
Referring to the attached figure 1, the method for measuring the slag amount of the continuous casting tundish is realized based on a measuring device of the slag amount of the continuous casting tundish, and the measuring device of the slag amount of the continuous casting tundish comprises a ladle turret pressure measuring head 4 arranged on a ladle turret, a ladle weight detector 5 connected with the ladle turret pressure measuring head 4, a steel slag detector 6 arranged above a sliding water gap 2, a water gap opening detector 7 arranged on the sliding water gap 2, a tundish weight detector 8, a process signal interface unit 9 and a data processing and calculating module 10; the output ends of the ladle weight detector 5, the steel slag detector 6, the water gap opening detector 7, the tundish weight detector 8 and the process signal interface unit 9 are respectively connected with the input end of the data processing and calculating module 10, the input end of the process signal interface unit 9 is externally connected with input equipment, and the output end of the data processing and calculating module 10 is externally connected with display equipment. The ladle weight detector 5 is a sensor for measuring weight, measures the weight of the ladle 1 which is currently poured in real time through a ladle turret pressure measuring head 4 arranged on a ladle turret, and outputs the weight value to the data processing and calculating module 10; the steel slag detector 6 is a sensor for measuring steel slag, and is used for measuring the content of the steel slag contained in the steel flow flowing through the sliding gate 2 in real time, and outputting the measurement result to the data processing and calculating module 10, preferably, the steel slag detector 6 can adopt an electromagnetic induction type detector with a function of measuring the percentage content of the steel slag in the prior art, and the measured data of the content of the steel slag is accurate; the water gap opening detector 7 is a device for measuring the opening of the current sliding water gap 2, and the detection result is also transmitted to the data processing and calculating module 10 in real time; the tundish weight detector 8 is a sensor for measuring weight, measures the weight of the tundish 3 which works currently in real time through a pressure measuring head arranged on a tundish car, and outputs the weight value to the data processing and calculating module 10; the process signal interface unit 9 is a signal conversion device that has two functions: firstly, converting the currently poured steel signal information into codes, and secondly, receiving the net weight signals and casting blank pulling speed signals of the currently poured steel ladle 1 and the tundish 3 and outputting the information to the data processing and calculating module 10; the data processing and calculating module 10 is a device having functions of data acquisition, model analysis and calculation, and result output, and preferably, it can adopt processing units such as an industrial personal computer, a Programmable Logic Controller (PLC), a Digital Signal Processor (DSP), etc. in the prior art, and it receives related signals and data transmitted from the ladle weight detector 5, the steel slag detector 6, the nozzle opening detector 7, the tundish weight detector 8, and the process signal interface unit 9, and calculates the total amount of slag discharged after comprehensive processing and outputs the total amount to a display.
Referring to fig. 2, the measuring method includes the following steps:
step 1: calibrating covering agent slagging density rhoCAnd density rho of steel slag of steel ladlegAnd the amount S of slag flowing into the crystallizerR。
The covering agent slagging density rhoCThe calibration method specifically comprises the following steps:
step 1.11: taking a certain steel grade continuous casting plan with less slag, emptying molten steel after casting is finished, only remaining steel slag in the tundish 3, and detecting the weight W of the tundish through a tundish weight detector 8 at the momentTNamely the weight W of the tundish steel slagCT(since the value of the tundish weight at the casting site is determined by default at the time of setting the apparatus to subtract the tare weight of the tundish itself (i.e. the tundish weight W)T) So that the tundish weight W is at this timeTNamely, the weight W of the tundish steel slagCT)。
Please refer to fig. 3, step 1.12: a plurality of burner holes 31 are formed in a cover of the tundish 3 and are used for baking burners in the preparation stage of the tundish 3, and after the tundish 3 enters a casting position, a covering agent is generally put in through the burner holes 31; the ladle cover of the tundish 3 is additionally provided with a casting hole 32 for the ladle long nozzle to be inserted for casting, and the tundish 3 is divided into a plurality of areas by the burner nozzle hole 31 and the casting hole 32. The burner holes 31 and the casting holes 32 are the passages for the steel slag to enter the tundish 3, and are usually the thickest part of the slag layer. The number of the burner holes 31 is determined according to the size of the tundish 3, and is generally 2 or 4, referring to fig. 2, four burner holes 31 are arranged on the cover of the tundish 3, the four burner holes 31 are symmetrically arranged on two sides of the casting hole 32, and the four burner holes 31 and the casting hole 32 divide the tundish 3 into five areas.
Step 1.13: calculating the average thickness h of the slag layer of each area of the tundish 3LiThe calculation formula is as follows:
hLi＝0.5βiL+hMINi
where i is the number of zones, i is 1,2,3,4,5, …, x, L is the width of the tundish 3; h isMINiIs the minimum slag layer thickness of the respective zones, typically at the edges; beta is aiThe gradient coefficient of the slag layer in each area is determined according to the distribution of the slag layer in each area, and the value is usually 2-5%.
Step 1.14: according to the average thickness h of the slag layerLiCalculating the volume V of the slag layerCTThe area of the tundish 3 is SLThe calculation formula is as follows:
step 1.15: calculating the slag-forming density rho of the covering agentCThe calculation formula is as follows:
since the steel slag is divided into three layers and the densities are different, two methods can be used for calibrating the coveringSlag density rho of agentC. One is to get the average density, and the concrete method is that after the casting is finished, the molten steel is emptied, and only the residual steel slag is left in the tundish 3. At this time, considering that the covering agent slagging in the tundish 3 is the main part of the steel slag, the steel ladle slagging is omitted, and the average density, namely the covering agent slagging density, can be obtained by taking the net weight of the tundish at this time and dividing by the volume of the steel slag. However, it should be noted that this casting plan for calibration requires strict control of ladle slagging, and a less-slagging steel grade plan can be taken out, supplemented with a steel-remaining operation flow. And secondly, nominal density is taken, the slag layer can be ignored when the sintered layer is taken as the main body of the steel slag and the slag density of the liquid layer is close to that of the sintered layer, and the steel slag sample of the sintered layer is taken to measure the density of the steel slag sample, namely the covering agent slagging density.
The density rho of the steel ladle steel slaggDuring the calibration, because the steel slag in the ladle 1 is single in composition, the problem of various forms does not need to be considered, and the steel slag poured out of the ladle 1 can be taken for calibration after the casting of the ladle 1 is finished. It should be noted that, since a certain amount of residual molten steel may be generally mixed into steel slag, it is preferable to calibrate the steel slag density of the ladle after the completion of the steel scrap recovery operation from the steel slag.
The amount S of slag flowing into the crystallizerRThe calibration method specifically comprises the following steps:
step 1.21: after a continuous casting schedule is completed, the weight W of the steel slag in the crystallizer is measuredYAnd crystallizer covering agent input weight WYCTaking the weight W of the steel slag of the crystallizerYMinus crystallizer cover input weight WYCIs the weight of the steel slag flowing into the crystallizer.
Step 1.22: calculating the amount S of slag flowing into the crystallizerRThe calculation formula is as follows:
where m is the number of replacement ladles 1 in the continuous casting plan.
Step 2: the total slag amount S of the tundish 3 is calculated by the data processing calculation module 10.
Step 2.1: reading the initial slag quantity S0Initial amount of slag S0Is the amount of slag generated in the casting of the previous ladle 1 in the same continuous casting plan; if the current ladle 1 is the first ladle in the continuous casting plan, the initial slag amount S0Is 0.
Step 2.2: for covering agent slagging amount SCThe amount of the covering agent is determined by the amount of the covering agent charged into the tundish 3, and is mainly a multilayer covering slag including a liquid layer, a sintered layer, and a slag layer formed by the covering agent charged into the tundish 3. Usually, the covering agent is quantitatively bagged, when in use, an operator or a robot puts the tundish 3 into the bag, thus neglecting slagging loss and reading the weight W of each bag of the covering agentCAnd the number n of bags of covering agent put in the current casting plancCalculating the covering agent slagging amount SCThe calculation formula is as follows:
step 2.3: and calculating the molten steel flow f of the water gap.
The flow rate of molten steel at a nozzle is difficult to measure by a direct meter due to the high temperature of the molten steel, and two calculation methods are generally used for the flow rate f of molten steel at a nozzle. One is calculated by a mechanism model, and if the molten steel at the sliding nozzle 2 is in a free falling state when flowing out, the calculation formula of the molten steel flow f at the nozzle is as follows:
wherein: k is the flow coefficient of the sliding gate 2, O is the opening of the sliding gate 2, ρSIs the molten steel density, d is the diameter of the sliding gate 2, g is the gravity acceleration, and h is the molten steel level height in the ladle 1.
When steel slag is mixed in the molten steel, because the density of the steel slag is far less than that of the molten steel, the calculation formula of the molten steel flow f of the water gap is as follows:
the method has clear physical meaning and better precision under the condition of stable system parameters. However, the calculation accuracy is affected by the tare weight drift of the ladle 1 when the nozzle is replaced in the production field.
And the other is calculated by using the weight derivative of the molten steel. Theoretically measuring the weight W of the ladleLThe molten steel flow f at the water gap can be obtained by differentiating time, but actually, the weighing system of the ladle 1 has a large weighing range, so the working environment is severe and the precision is not high. Meanwhile, data fluctuation is frequent under various interference factors of a steel casting site, and the instantaneous flow during slag discharging is difficult to measure. But if the random noise cancels each other in view of the long-term multipoint data, the measured value tends to be reliable. The invention adopts the calculation method to calculate the molten steel flow f at the water gap. The method for calculating the molten steel flow f of the water gap comprises the following specific steps:
step 2.3.1: and (3) judging the liquid level control mode of the tundish 3, if the liquid level of the tundish 3 is manually controlled (can be controlled by adopting a human intervention mode), fixing the opening degree of the sliding water gap 2, executing the step 2.3.2, and if the liquid level of the tundish 3 is automatically controlled (can be automatically controlled by adopting control equipment in the prior art), changing the opening degree of the sliding water gap 2, and executing the step 2.3.4.
Step 2.3.2: in the case where the opening of the sliding gate nozzle 2 is not changed, every time the ladle weight W is changedLDecrease Δ WTAt that time, a set of weight time values of ladle 1 is sampled until z sets, i.e.
Wherein j is 1,2, …, z-1, z,. Delta WTShould be more than 10 times of the minimum weighing unit of the ladle rotary platform scale, the value of z depends on the computing capacity of the data processing and computing module 10, but z should be more than 5. The ladle weight curve can be fitted using the least squares method:
WL＝α1TW 2+α2TW+α3
wherein, TWTo be stableThe fixed casting time is a fixed time T from the opening of the sliding gate 20The starting time period. Then may be at T0At a time point after the moment, the weight of the ladle is sampled for a plurality of times, and alpha is obtained by using a curve fitting mode1，α2，α3The value of (c).
The current accurate ladle weight W can be calculated according to the timeLThen, the flow rate f of molten steel at the nozzle can be obtained by derivation.
Step 2.3.3: when the sliding nozzle 2 is used for deslagging, the molten steel flow f of the nozzle is calculated, and the step 2.4 is carried out, wherein the calculation formula is as follows:
step 2.3.4: the opening of the sliding water gap 2 is changed and the pulling speed f is changedLWithout change, by tundish weight WTAnd downstream pull rate fLTo calculate the molten steel flow f at the water gap, the calculation formula is as follows:
since the liquid level in the tundish 3 is generally constant, it is not possible to fit its weight curve as with the ladle 1. But the weight of the tundish 3 is far less than that of the ladle 1, so the tundish is higher than that of the ladle 1 in weighing precision although the tundish is also subjected to severe continuous casting working conditions. But by the weight of the tundish WTWhen the molten steel flow f of the water gap is calculated, the downstream flow, namely the downstream pulling speed, is supposed to be unchanged, and if the downstream pulling speed is changed, the calculation precision is influenced.
Step 2.4: for slag amount S of ladlePThe steel ladle slag discharging is mainly steel slag in a steel ladle 1 which is rolled into a tundish 3 by molten steel eddy current through a sliding water gap 2, and the slag discharging amount S of the steel ladle 1 is calculatedPThe total amount of slag discharged from the sliding gate 2, i.e., the amount of slag discharged from the ladle SPThe water gap steel slag content p can be obtained by integrating the time t, and the calculation formula is as follows:
wherein p is the water gap steel slag content rho detected by the steel slag detector 6gThe steel ladle steel slag density.
Step 2.5: the amount of slag S currently generated by the ladle1Slagging S by covering agentCAnd slag discharging S of steel ladlePComposition, and then the amount of slag S flowing into the crystallizer is removedRCalculating the amount S of slag generated by the current ladle 11The calculation formula is as follows:
S1＝SC+SP-SR。
amount of slag S flowing into the moldRUsually, the situation is avoided in the continuous casting process, but in practice, the slag is difficult to completely prevent. In current continuous casting, tundish slagging occurs under two conditions: firstly, the ladle 1 is changed and poured, the steel flow violently impacts the liquid level of the tundish 3, and the steel slag is brought into the crystallizer; secondly, the liquid level of the molten steel in the tundish 3 is too low, and the molten steel in the tundish 3 forms a vortex to roll the steel slag into the crystallizer. In the continuous casting process, the tundish 3 needs to keep a certain liquid level, so the working condition II rarely appears under normal conditions and can be disregarded. The working condition is difficult to avoid at one time, and the slag quantity increased by the crystallizer during ladle replacement and casting can be calibrated off lineR。
Step 2.6: in continuous casting production, a continuous casting plan usually uses the same tundish 3, and all ladles 1 in the same continuous casting plan flow into the same tundish 3, so that the total slag quantity S of the current tundish 3 is the initial slag quantity S left in the tundish 3 after the first ladles 1 in the same continuous casting plan are poured0Adding the amount S of slag generated by the current ladle 11. The total slag amount S in the tundish 3 in the continuous casting plan is calculated by the following formula:
S＝S0+S1。
and step 3: even if the calibration is performed off-line, the continuous casting system working condition is bound to change along with the time. And (3) carrying out deviation correction on the total slag quantity S through a self-correction coefficient E, wherein the correction formula is as follows:
S＝S0+S1+Ek
wherein E iskIs the self-correction coefficient after the current k-th correction, and the initial value of E is E0Is 0.
In actual use, factors such as aging of the sliding nozzle 2, change of parameters of the ladle 1, deformation of the ladle turret pressure measuring head 4 and the like cause deviation between a flow calculated by using offline calibration data and an actual value, and the deviation generally increases along with the use time and finally even accumulates to an unacceptable degree of a user. Therefore, it is necessary to correct the deviation by on-line self-correction, the measuring device needs to be continuously self-corrected to correct the parameters in use, and the self-correction coefficient E of the measuring method needs to meet certain conditions because the working conditions in continuous casting production are continuously changed. The self-correction coefficient E is calculated as follows:
step 3.1: for steel grades of less high gauge, the tundish 3 may be emptied completely after the last ladle 1 has been emptied of molten steel at the end of the casting schedule, in order to increase the yield, the weight of the tundish at this point being considered to be the total slag weight W produced by the entire casting scheduleE。
Step 3.2: because the covering agent slagging accounts for the main part of residues after the molten steel in the tundish 3 is emptied, the slagging density rho of the covering agent is usedCCalculating the actual slag quantity SEThe calculation formula is as follows:
where ρ isCIs the covering agent slagging density.
Step 3.3: calculating the self-correction coefficient E after the current k +1 correctionk+1The calculation formula is as follows:
wherein, the delta E is a correction step length, the value of the correction step length can be adjusted according to the self-correction frequency, if the use condition allows, the self-correction is more frequent, and the delta E can be smaller; otherwise, the larger the size of the sample. In general, since the change in system parameters is not usually too drastic, Δ E should be less than 0.1Ek. Δ S is the threshold for the opening correction, the value of Δ S is related to the composition of the residue in the tundish 3, and should not be too small, at least more than 0.1SE. k is the number of corrections.
Example (b):
a: calibrating covering agent slagging density rhoCAnd density rho of steel slag of steel ladlegAnd the amount of slag flowing into the crystallizer SR.
A1: calibrating covering agent slagging density rhoC。
Taking a certain mark of high-strength steel casting plan with little slag left in steel-retaining operation, emptying molten steel after casting is finished, only remaining steel slag in a tundish 3, wherein the weight of the tundish is the weight W of the steel slagCT＝2.5t。
The tundish 3 is divided into 5 zones, i.e. i is 5, by four burner holes 31 and pouring holes 32. The minimum slag layer thickness measured at the middle edge of each zone is hMIN1＝0.07m，hMIN2＝0.08m，hMIN3＝0.10m，hMIN4＝0.09m，hMIN50.08m, the width L of the tundish 3 is 2m, betaiTaken 2%, then according to the following equation:
hLi＝0.5βiL+hMINi
to obtain hL1＝0.09m，hL2＝0.10m，hL3＝0.12m，hL4＝0.11m，hL5＝0.10m。
Area S of tundish 3L＝10m2The volume of the slag layer can be obtained:
further, the density of the slag layer can be obtained:
a2: calibrating steel ladle steel slag density rhog。
After the recovery operation of the steel ladle scrap steel is finished, the density rho of the steel ladle steel slag can be obtained by measuring the residual steel slagg＝2.9t/m3。
A3: calibrating the amount S of slag flowing into the crystallizerR。
After a continuous casting plan is finished, measuring the weight W of the steel slag in the crystallizerY0.09t, the crystallizer is covered with a weight WYCThe number of planned ladle 1 replacements, m, was 10 at 0.05t, and the amount of slag was obtained according to the following formula:
b: the total slag amount S of the tundish 3 is calculated.
B1: reading the initial slag quantity S0＝0.115m3。
B2: reading the weight W of the covering agentC0.025t, the number of bags n put into the ladle castingCCalculating the covering agent slagging amount as 4:
b3: the level of the tundish 3 is currently in the automatic control state, and the step B32 is transferred.
B32: with varying downstream draught velocity fLUnder the condition that the weight of the tundish is not changed within 4t/min, the weight dW of the tundish is changed within 1min according to the unit time dt of the tundishTCalculate nozzle flow 0.1 t:
b4: slag from the current ladle 1 start-upThe amount is integrated to obtain the slag amount S of the ladleP：
B5: calculating the amount S of slag generated by the current ladle1。
S1＝SC+SP-SR＝0.061m3。
B6: and calculating the total slag quantity S.
S＝S0+S1+Ek＝0.186m3
Wherein: ek＝0.01m3。
C: and (4) self-correcting.
After the casting schedule was completed, the molten steel in the tundish 3 was emptied and the total slag weight W was measuredEThe actual slag quantity can be calculated as 0.55 t:
take Delta E as 0.09Ek，△S＝0.11SEDue to (S)E-S)>0.11SE。
Then Ek+1＝Ek+|△E|＝0.0109m3。
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method for measuring the slag quantity of a continuous casting tundish is characterized by comprising the following steps: the method is realized based on a measuring device of the slag amount of the continuous casting tundish, and the measuring device of the slag amount of the continuous casting tundish comprises a ladle turret pressure measuring head (4) arranged on a ladle turret, a ladle weight detector (5) connected with the ladle turret pressure measuring head (4), a steel slag detector (6) arranged above a sliding water gap (2), a water gap opening detector (7) arranged on the sliding water gap (2), a tundish weight detector (8), a process signal interface unit (9) and a data processing and calculating module (10); the output ends of the ladle weight detector (5), the steel slag detector (6), the water gap opening detector (7), the tundish weight detector (8) and the process signal interface unit (9) are respectively connected with the input end of the data processing and calculating module (10), the input end of the process signal interface unit (9) is externally connected with input equipment, and the output end of the data processing and calculating module (10) is externally connected with display equipment;
the measuring method comprises the following steps:
step 1: calibrating covering agent slagging density rhoCAnd density rho of steel slag of steel ladlegAnd the amount S of slag flowing into the crystallizerR；
Step 2: calculating the total slag quantity S of the tundish (3) through a data processing calculation module (10);
and step 3: and (4) carrying out deviation correction on the total slag quantity S through a self-correction coefficient E.
2. The method for measuring the amount of slag in a continuous casting tundish according to claim 1, wherein: the covering agent slagging density rhoCThe calibration method specifically comprises the following steps:
step 1.11: in the steel grade continuous casting plan, after the casting is finished, molten steel is emptied, only steel slag remains in the tundish (3), and the weight of the tundish detected by the tundish weight detector (8) at the moment is considered as the weight W of the steel slag in the tundishCT；
Step 1.12: a casting hole (32) and a plurality of burner holes (31) are formed in a ladle cover of the tundish (3), after the tundish (3) enters a casting position, a covering agent is put in through the burner holes (31), a ladle long nozzle is inserted into the casting hole (32) for casting, and the tundish (3) is divided into a plurality of areas by the burner holes (31) and the casting hole (32);
step 1.13: calculating the average thickness h of the slag layer of each area of the tundish (3)LiThe calculation formula is as follows:
hLi＝0.5βiL+hMINi
wherein i is the number of zones, i is 1,2,3,4,5, …, x, L is of the tundish (3)Width, hMINiIs the minimum slag layer thickness, beta, of the respective zonesiIs the slag layer gradient coefficient of each area;
step 1.14: according to the average thickness h of the slag layerLiCalculating the volume V of the slag layerCTThe area of the tundish 3 is SLThe calculation formula is as follows:
step 1.15: calculating the slag-forming density rho of the covering agentCThe calculation formula is as follows:
3. the method for measuring the amount of slag in a continuous casting tundish according to claim 2, wherein: the gradient coefficient beta of the slag layeriThe value range of (A) is 2-5%.
4. The method for measuring the amount of slag in a continuous casting tundish according to claim 1, wherein: the amount S of slag flowing into the crystallizerRThe calibration method specifically comprises the following steps:
step 1.21: after a continuous casting schedule is completed, the weight W of the steel slag in the crystallizer is measuredYAnd crystallizer covering agent input weight WYCTaking the weight W of the steel slag of the crystallizerYMinus crystallizer cover input weight WYCIs the weight of the steel slag flowing into the crystallizer;
step 1.22: calculating the amount S of slag flowing into the crystallizerRThe calculation formula is as follows:
wherein m is the number of replacement ladles (1) in the continuous casting plan.
5. The method for measuring the amount of slag in a continuous casting tundish according to claim 1, wherein: the step 2 also comprises the following sub-steps:
step 2.1: reading the initial slag quantity S0Initial amount of slag S0Is the amount of slag generated in the casting of the previous ladle (1) in the same continuous casting plan;
step 2.2: reading the weight W of each bag of coating agentCAnd the number n of bags of covering agent put in the current casting plancCalculating the covering agent slagging amount SCThe calculation formula is as follows:
step 2.3: calculating the molten steel flow f at the water gap;
step 2.4: calculating the slag amount S of the ladle (1)PThe calculation formula is as follows:
wherein p is the water gap steel slag content rho detected by the steel slag detector (6)gThe steel ladle steel slag density;
step 2.5: calculating the current slag quantity S generated by the ladle (1)1The calculation formula is as follows:
S1＝SC+SP-SR；
step 2.6: calculating the total slag quantity S in the tundish (3) in the continuous casting plan, wherein the calculation formula is as follows:
S＝S0+S1。
6. the method for measuring the amount of slag in a continuous casting tundish according to claim 5, wherein: in said step 2.1, if the current ladle (1) is the first ladle to be cast in the continuous casting plan, the initial amount of slag S0Is 0.
7. The method for measuring the amount of slag in a continuous casting tundish according to claim 5, wherein: the method for calculating the molten steel flow f of the water gap comprises the following specific steps:
step 2.3.1: judging the liquid level control mode of the tundish (3), if the liquid level of the tundish (3) is manually controlled, fixing the opening degree of the sliding water gap (2), and executing the step 2.3.2, if the liquid level of the tundish (3) is automatically controlled, changing the opening degree of the sliding water gap (2), and executing the step 2.3.4;
step 2.3.2: when the opening of the sliding gate (2) is not changed, every time the ladle weight W is changedLDecrease Δ WTAt the moment, a set of weight time values of the ladle (1) is sampled until the z set, i.e.
Wherein j is 1,2, …, z-1, z>5; a ladle weight curve is fitted using a least squares method:
WL＝α1TW 2+α2TW+α3
wherein, TWFor stabilizing the casting time, the opening degree of the sliding water gap (2) is fixed at the time T0Starting period of time, α1，α2，α3Is a constant;
step 2.3.3: when the sliding nozzle (2) is used for deslagging, the molten steel flow f of the nozzle is calculated, and the step 2.4 is carried out, wherein the calculation formula is as follows:
step 2.3.4: the opening degree of the sliding gate (2) is changed and the downstream pulling speed f is changedLWithout change, by tundish weight WTAnd downstream pull rate fLTo calculate the molten steel flow f at the water gap, the calculation formula is as follows:
8. the method for measuring the amount of slag in a continuous casting tundish according to claim 1, wherein: the step 3 comprises the following sub-steps:
step 3.1: after the last ladle (1) at the end of the continuous casting schedule is completely emptied of molten steel in the tundish (3), the weight of the tundish at this point is taken as the total slag weight W produced by the entire casting scheduleE；
Step 3.2: density of slag formation by covering agent rhoCCalculating the actual slag quantity SEThe calculation formula is as follows:
where ρ isCIs covering agent slagging density;
step 3.3: calculating the self-correction coefficient E after the current k +1 correctionk+1The calculation formula is as follows:
wherein, Δ E is a correction step length, Δ S is a threshold value for starting correction, and k is a correction frequency.
9. The method for measuring the amount of slag in a continuous casting tundish according to claim 8, wherein: the correction step length delta E is less than 0.1Ek。
10. The method for measuring the amount of slag in a continuous casting tundish according to claim 8, wherein: the threshold value Delta S of the opening correction is more than 0.1SE。
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