CN118548963A - Method for measuring, calculating and compensating weight of continuous casting tundish on-line residual steel - Google Patents
Method for measuring, calculating and compensating weight of continuous casting tundish on-line residual steel Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 165
- 239000010959 steel Substances 0.000 title claims abstract description 165
- 238000009749 continuous casting Methods 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 53
- 238000005266 casting Methods 0.000 claims abstract description 47
- 238000005303 weighing Methods 0.000 claims abstract description 45
- 239000007788 liquid Substances 0.000 claims abstract description 41
- 238000009529 body temperature measurement Methods 0.000 claims abstract description 24
- 230000008859 change Effects 0.000 claims abstract description 11
- 238000012545 processing Methods 0.000 claims abstract description 5
- 238000005070 sampling Methods 0.000 claims abstract description 4
- 239000007791 liquid phase Substances 0.000 claims description 17
- 230000008569 process Effects 0.000 claims description 15
- 230000009467 reduction Effects 0.000 claims description 15
- 238000007711 solidification Methods 0.000 claims description 11
- 230000008023 solidification Effects 0.000 claims description 11
- 230000004044 response Effects 0.000 claims description 9
- 230000003628 erosive effect Effects 0.000 claims description 7
- 238000009833 condensation Methods 0.000 claims description 4
- 230000005494 condensation Effects 0.000 claims description 4
- 230000001934 delay Effects 0.000 claims description 4
- 230000005484 gravity Effects 0.000 claims description 3
- 230000001502 supplementing effect Effects 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 14
- 239000002436 steel type Substances 0.000 abstract description 8
- 238000004364 calculation method Methods 0.000 description 13
- 239000002893 slag Substances 0.000 description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 238000005259 measurement Methods 0.000 description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 6
- 230000000903 blocking effect Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- 239000001301 oxygen Substances 0.000 description 6
- 239000003795 chemical substances by application Substances 0.000 description 5
- 230000007547 defect Effects 0.000 description 5
- 230000002159 abnormal effect Effects 0.000 description 4
- 238000012937 correction Methods 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 238000001816 cooling Methods 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000004907 flux Effects 0.000 description 3
- 239000011819 refractory material Substances 0.000 description 3
- 238000006424 Flood reaction Methods 0.000 description 2
- 238000007667 floating Methods 0.000 description 2
- 230000017525 heat dissipation Effects 0.000 description 2
- 238000003384 imaging method Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000003908 quality control method Methods 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
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- 230000008018 melting Effects 0.000 description 1
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- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G17/00—Apparatus for or methods of weighing material of special form or property
- G01G17/04—Apparatus for or methods of weighing material of special form or property for weighing fluids, e.g. gases, pastes
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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
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G23/00—Auxiliary devices for weighing apparatus
- G01G23/48—Temperature-compensating arrangements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/02—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using thermoelectric elements, e.g. thermocouples
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- Fluid Mechanics (AREA)
- Continuous Casting (AREA)
Abstract
The invention discloses a continuous casting tundish online residual steel weight measuring and compensating method, which comprises the steps of processing signal feedback time after continuous temperature measurement sampling frequency of molten steel through a tundish continuous temperature measuring device, judging a low liquid level state of the molten steel in a tundish, feedback time based on couple temperature measurement and steel passing amount according to an inflection point of a continuous temperature measurement value, change of a tundish weighing value, casting steel type characteristics and a superheat degree change trend model, and compensating the pouring end of the tundish. The invention improves the yield of molten steel and reduces the production cost.
Description
Technical Field
The invention relates to a continuous casting online monitoring technology, in particular to a method for measuring and compensating the weight of continuous casting tundish online residual steel.
Background
The continuous casting tundish is one of the key equipment in the continuous casting process, has the functions of stabilizing flow, dividing flow, storing molten steel, floating inclusion and homogenizing the temperature and composition of the molten steel, and plays an important role in the continuous casting operation and ensuring the quality of the molten steel.
The continuous casting production process is a molten steel solidification forming process of pouring a ladle of molten steel into a tundish, pouring the tundish of molten steel into a crystallizer, and pulling a casting blank out of a casting machine in a continuous cooling process. The control of the weight of the tundish molten steel is a key index of continuous casting production and quality control, and relates to the following 4 problems:
1) Tundish flow field stability: the internal flow field of the tundish is disordered when the tonnage of the tundish is too low and the tonnage of the tundish is too fast, so that a large amount of inclusions cannot reach the upper floating point and are involved in a crystallizer, and casting blank quality defects and even steel leakage accidents are caused;
2) The influence of the hydrostatic pressure change of the molten steel on the stability of the casting liquid level of the crystallizer; in the process of rapid change of the weight of a tundish, the static pressure of a pouring channel from the tundish to a crystallizer is greatly changed, so that the response speed of a flow control system is insufficient to cause great fluctuation of the liquid level of the crystallizer, and the response speed is an important factor for causing slag inclusion and inclusion of a casting blank;
3) The amount of molten steel in the tundish is too high: the molten steel is easy to overflow from the overflow port of the tundish and even the upper edge port of the tundish, so that the site safety accident is caused;
4) Multiple effects of tundish molten steel on casting safety, quality control, and continuous casting yield near low critical height: namely, when the continuous casting abnormal operation (the subsequent steel ladle connection is not smooth), the different steel type insert plate continuous casting (the steel ladle in front and rear furnace times are physically separated by the iron plate in the crystallizer), the tundish is replaced and continuous casting is carried out before CAST CAST final casting, and the residual steel in the tundish is lower than the critical height, if the blocking rod (or a flow control device such as a sliding plate and the like) is not closed timely, the vortex formed above the pouring opening of the pouring channel can roll acid slag, covering agent and a large amount of inclusions stored in the tundish into the crystallizer, so that the defects of steel leakage, rising, serious slag inclusion and inclusion of casting blanks are easily caused; if the blocking rod (or the sliding plate) is closed too early, excessive steel remains in the tundish, which causes the loss of molten steel and increases the difficulty of the offline treatment process of the tundish.
At present, all continuous casting tundish are provided with weighing devices, the devices are generally composed of 4 weighing pressure sensors arranged on a tundish car lifting platform, the weighing components comprise the weight of a tundish body, the weight of molten steel in the tundish and the like, and before the tundish is poured, the weight of the tundish body is eliminated through a tare elimination function, and then the weight of molten steel in the tundish is obtained. However, because the weighing range of the weighing device is large, if the maximum molten steel capacity of a tundish for continuous slab casting in a certain steel mill is 70 tons and the weight of a tundish body is 60 tons, the tundish weighing range of the casting machine is between 0 and 130 tons, the weighing linear characteristic of the weighing device cannot meet the weighing precision in such a large span range, and because the weighing device is arranged on a movable lifting platform, the flatness of the platform, dust and sundries around each weighing pressure head have great influence on the weighing precision, and because of the problem of molten steel temperature control in the continuous casting production process, the fact that the solidification amount of the molten steel in the tundish with different degrees in low tonnage can interfere with the judgment of the actual height of the molten steel in the tundish on site.
Therefore, the weighing device of the tundish can only be used as a trend judging basis of the weight of the molten steel of the tundish, in the actual production process, operators need to carry out certain correction on the actual weight of the molten steel in the tundish by visual or special tools after the tundish is started, and the molten steel in the tundish is repeatedly corrected in a manual actual measurement mode when the iron plate of the different steel type is continuously poured, the tundish is replaced and continuously poured and abnormal operation leads to extremely low tonnage of the tundish before continuous casting and final pouring. The method comprises the steps that an operator stands on the ladle cover or the ladle edge of the tundish, inserts an oxygen rod into a certain specific position in molten steel of the tundish, then takes out the oxygen rod, measures the height of molten steel on the oxygen rod, and then approximately calculates the actual weight in the tundish according to the shape of the tundish. However, the operation has a great danger, and different operation gestures of each person can cause a great error, and meanwhile, the continuous casting automation and the less humanization are greatly jeopardized.
The prior method for measuring the molten steel in the tundish mainly comprises the following two steps:
In the method 1, the measurement of the molten steel of the tundish is carried out manually in the continuous casting on-line production running state at present: the ladle worker inserts the oxygen rod into the bottom of the tundish through the upper hole of the cover of the tundish, then takes out the oxygen rod, measures the height of molten steel adhered on the oxygen rod, calculates and judges the residual molten steel amount according to the shape of the tundish, and predicts the time of the crystallizer for cutting off.
Because the manual participation judgment can not effectively and accurately judge the residual molten steel amount of the tundish, the slag discharging condition of the crystallizer is very easy to occur under the condition of manual judgment error or missing, thereby causing slag inclusion of a plate blank and even blocking of a water discharging port, and causing quality and safety accidents.
The method 2 aims at the situation that certain danger exists in manual intervention measurement, so that the measurement operation method is improved, a mechanical arm is adopted to replace manual high-risk work, a camera is used to replace naked eyes to observe molten steel on the surface of an iron rod, and manual discrimination and estimation are carried out. However, the accuracy requirement still cannot be met due to the limitation of conditions such as the position of the measuring point, and the like, and the judgment still needs to be performed manually.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method for measuring, calculating and compensating the weight of the continuous casting tundish on-line residual steel, so that the yield of molten steel is improved, and the production cost is reduced.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the method for measuring and compensating the weight of the continuous casting tundish on-line residual steel comprises the following steps:
And processing the signal feedback time after the continuous temperature measurement sampling frequency of the molten steel by a continuous temperature measurement device of the tundish, and calculating the low liquid level state of the molten steel in the tundish, the feedback time based on thermocouple temperature measurement and the steel passing amount according to the inflection point of the continuous temperature measurement value, the change of the weighing value of the tundish, the casting steel grade characteristic and the overheat degree change trend model, so as to compensate when the casting of the tundish is finished.
Preferably, the continuous temperature measuring device of the tundish is arranged at the middle lower part of the tundish.
Preferably, the judgment of the low liquid level state of the molten steel in the tundish is specifically as follows:
The temperature of the liquid-phase measuring point of the tundish, which is measured by the continuous temperature measuring device of the tundish, is reduced from 1550 ℃ to 1450 ℃ within a required time period of 2-8 minutes, and the liquid-phase measuring point of the tundish is judged to be in a low liquid state.
Preferably, when the temperature of the liquid-phase measuring point of the continuous tundish temperature measuring device is reduced to more than 12.5 ℃ in average per minute, the liquid molten steel at the position of the liquid-phase measuring point of the continuous tundish temperature measuring device is judged to be separated into the air.
Preferably, the steel passing amount m=ρv;
wherein ρ is the specific gravity value of steel, which is 7.6g/cm 3; v is the volume of slab cast during this period.
Preferably, the volume V of the crystallizer is calculated as follows:
V=x×y×s;
Wherein x is the width of the crystallizer; y is the thickness of the crystallizer; s is the length of the slab cast during this period;
Where s=v 0t0+(v0t1-1/2gt1^2)+v1t2 (where v 0 is the pre-deceleration speed, t 0 is the hold time at that pull speed, t 1 is the deceleration process time, g is the deceleration rate, v 1 is the hold speed, and t 2 is the hold time).
Preferably, the compensating at the end of pouring the tundish includes:
The thermocouple feedback signal delays supplementing DC;
covering agent weight compensation FG;
Weight compensation NG of the refractory loss in the tundish;
continuous casting speed reduction adjustment delay compensation PH;
When the speed reduction of the liquid phase measuring point temperature of the continuous tundish temperature measuring device meets the condition, the casting is finished, the molten steel quantity in the tundish is calculated according to the steel grade coefficient alpha (namely the solidification speed), and then the actual tonnage at the end of the casting of the tundish is compensated, and the method comprises the following steps:
a tundish weighing value W1 when molten steel contacts a continuous temperature measuring thermocouple during tundish casting;
The highest tonnage alarm is given out for the last time before the final pouring of the tundish and the weighing value W2 of the tundish at the moment;
a tundish weighing value W3 when the continuous temperature measuring couple is disconnected from the steel liquid level before the tundish is finally poured;
tundish weight judgment deviation delta G1 caused by response delay of continuous temperature measurement couple;
The system automatically accumulates the adding quantity delta G2 of the tundish covering agent;
Deviation delta G3 of solidification quantity of molten steel;
Tundish expansion deviation delta G4;
tundish low tonnage weighing linear compensation deltag 5.
Preferably, the weight compensation of the refractory loss in the tundish ng=loss coefficient×weight of molten steel in each ladle×continuous casting number;
and calculating the continuous casting speed reduction adjustment delay compensation PH according to the steel passing quantity of different crystallizers.
Preferably, the tundish weight judgment deviation delta G1 = { [ W1- (V1-V2) t1] + [ W3-V3 t 1) ] }/2 caused by the response delay of the continuous temperature measurement couple;
Wherein V1 is the descending speed of the weighing of the large ladle when the first furnace of the tundish is started to reach W1 (a large ladle slide plate is not required to be fully opened in the pouring process of the tundish); v2 is the actual speed of the pouring basket when the initial furnace is started to reach W1 and the pouring basket is poured into the crystallizer; v3 is the outflow speed of the tundish molten steel when the continuous temperature measuring couple is disconnected from the liquid level of the steel before final casting; t 1 is the response delay time of the temperature measurement thermocouple.
The molten steel solidification amount deviation Δg3=α×t2;
wherein alpha is the molten steel condensation speed (steel grade coefficient, i.e. condensation speed) at different temperatures of different steel grades in a low temperature state; t2 is the time calculated by the system from the safe initial pull speed V4 deceleration starting point weighing W4 to the final pouring point weighing W5;
the tundish expands capacity deviation Δg4 =βtt3;
wherein, beta is an erosion influence coefficient; t3 is the total pouring time of the tundish;
The tundish low tonnage weighing linear compensation delta G5 is the weighing linear compensation from W3 to W5.
The method for measuring, calculating and compensating the weight of the continuous casting tundish online residual steel mainly solves the potential safety hazard caused by manual operation, prevents abnormal accidents caused by manual judgment, effectively controls the stability and safety of production logistics, and achieves the effects of solving the production safety and controlling the continuous casting production quality. The novel judging method is discovered and invented through the original thermometer in the tundish, the liquid level of the liquid molten steel in the tundish can be intuitively judged, and on the premise of the judging method, the measurement and judgment can be carried out on line in the continuous casting state through a model mechanism for pre-judging the advance. The method is simple, the technical principle is mature, and the method is convenient and practical in practice, and has higher application value on similar metallurgical continuous casting occasions. Can be popularized and used in various domestic large steel enterprises, and has very wide application prospect.
Drawings
FIG. 1 is a diagram of tundish temperature trend;
FIG. 2 is a schematic diagram of a tundish temperature profile;
FIG. 3 is a schematic diagram of a temperature profile taken by a thermometer when the tundish enters the final CAST stage;
FIG. 4 is a schematic diagram of the liquid phase measurement point temperature of the tundish continuous temperature measuring device for measuring and compensating the temperature according to the invention;
FIG. 5 is a schematic diagram of the pull rate versus tundish weight for the calculation and compensation method of the present invention;
FIG. 6 is a flow chart of compensation calculation for the calculation and compensation method of the present invention;
FIG. 7 is a logic flow diagram of the calculation and compensation method of the present invention.
Detailed Description
In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below with reference to the accompanying drawings and examples.
The invention provides a method for measuring and compensating the weight of continuous casting tundish on-line residual steel, which comprises the following steps:
and processing the signal feedback time after the continuous temperature measurement sampling frequency of the molten steel by a continuous temperature measurement device of the tundish, judging the low liquid level state of the molten steel in the tundish, the feedback time based on thermocouple temperature measurement and the steel passing amount according to the inflection point of the continuous temperature measurement value, the change of the weighing value of the tundish, the casting steel grade characteristic and the overheat degree change trend model, and compensating the casting end of the tundish. The defect problem existing in manual judgment can be effectively solved.
Referring to fig. 1, the tundish is required to be baked and preheated before casting, the preheating temperature can reach about 1150 ℃, then molten steel casting is performed, and the trend temperature of the thermometer is increased. The part temperature at the position A is the preheating state temperature of the tundish. The position B is the time when the middle part is separated from the preheating state and enters the preparation stage (the heat source is not used for heating, so that the heat dissipation state is changed), and the temperature of the imaging has the tendency of temperature return (temperature reduction). And then the temperature rises rapidly as the liquid molten steel is added to the tundish.
With reference to fig. 2, the continuous temperature measuring device of the tundish is placed at the middle lower part of the tundish and is blocked by the refractory (avoiding damage caused by direct contact with the liquid molten steel). Therefore, after the water inlet of the ladle is opened, molten steel enters the tundish and gradually floods the temperature measuring point of the temperature measuring instrument. At this time, the temperature of the thermometer will rise from the start of the liquid molten steel entering the tundish (i.e. it represents the liquid molten steel entering the tundish) until the molten steel floods the thermometer, the imaging temperature will reach the liquid molten steel temperature stepwise (about 1550 ℃), and enter into a temperature stable state.
After the continuous casting of a CAST is finished, the tundish needs to be replaced, and the molten steel in the tundish needs to be discharged as completely as possible (the residual molten steel amount is reduced, the cost is effective) at the same time, so that the falling of inclusions in the tundish is avoided.
In combination with the inflection point position shown in the C position part in FIG. 3, the temperature drop will highlight the boundary point between the thermometer and the liquid molten steel and steel slag. From this, it can be distinguished that the relative liquid level position of liquid molten steel has been lower than the temperature measuring point position, namely the temperature measuring point is the slag temperature that is measured at this moment. The temperature measuring point is then exposed to the air along with the decrease of the liquid level in the tundish, but is influenced by the heat preservation effect in the tundish and the heat radiation of the liquid molten steel, the liquidus temperature of the molten steel is 1500 ℃, and the temperature is gradually decreased.
Referring to fig. 4, the determination of the low liquid level state of the molten steel in the tundish is specifically as follows:
The temperature of the liquid phase measuring point of the continuous temperature measuring device of the tundish is reduced from 1550 ℃ to 1450 ℃ and the required time period is between 2 and 8 minutes, and the liquid phase measuring point is judged to be in a low liquid level state.
When the temperature of the liquid-phase measuring point of the continuous temperature measuring device of the tundish is above 12.5 ℃ in average every minute, the liquid molten steel at the position of the liquid-phase measuring point of the continuous temperature measuring device of the tundish is judged to be separated into the air.
Referring to fig. 5, T3 is a final treatment, namely closing the blocking rod, and the tundish needs to perform the operation of closing the blocking rod when the molten steel is at an extremely low liquid level to ensure the production quality of the continuous casting slab and prevent the scrap caused by slag coiling and slag discharging. However, in the prior art, the characteristics of the delay of the feedback signal of the temperature measuring point and the interference of the thermocouple feedback signal and the time difference of continuous casting speed reduction and other factors are considered, and are needed to be used as important characteristics for calculation. Therefore, the problem of inaccurate manual judgment in the past is solved, and the judgment is carried out by taking time quantification as the automatic casting basis according to the widths of different steel grades and different casting sections.
T1 corresponds to the liquid phase temperature of the tundish (about 1520 ℃ C. —according to the characteristics of steel types, the temperature will be different), V1 corresponds to the normal casting pulling speed (generally above 1.2), when the weight of the tundish of T1 reaches the range of the low liquid level, the pulling speed V controlled by the tundish should be correspondingly adjusted (the pulling speed is reduced), so that the variable speed of V2 is generated at the node, and the pulling speed of V2 is controlled to be 0.8 as the speed reduction treatment. Because certain delay exists in the speed reduction intervention process, the delay is two, namely the thermocouple feedback temperature delay S1 and the continuous casting speed reduction adjustment delay S2 (the simulation pulling speed is reduced from 1.2 to 0.8), and the continuous casting is always kept in a casting state in the process. Based on the two delays, the calculation compensation is performed, and the compensation of S1 is calculated according to the steel passing amount of the casting speed.
In the calculation of the steel flux m, the speed reduction rate of the actual continuous casting machine ranges from 0.125 to 0.75m/min 2, and in the embodiment, the value is 0.1m/min 2 for easy understanding. Casting length (height) s=vt+1/2 gt 2, v is the initial velocity, t is the target time (e.g. 1.2-0.8 takes 4 minutes), g is the casting rate change rate 0.1m/s, 2 is the square. By the above, it is possible to calculate how many slabs (heights) the mold has been pulled down during the deceleration process, and since x (length), y (width) of the mold is constant during the deceleration process, the specific gravity value ρ=7.6 g/cm 3 (density) of steel can be calculated, and the tapping liquid weight (this is the steel passing amount m) can be calculated. I.e. the steel throughput m=ρv=7.6 g/cm 3 (x y x s)
The calculation of the steel flux m facilitates the effective measurement and calculation of the molten steel quantity in the tundish.
Referring to fig. 6 and 7, in this embodiment, the delay compensation method includes a steel grade coefficient α (steel grade is low-temperature and easy to be cooled), a temperature coefficient β (the lower the temperature is, the more the cooled steel is), and in order to ensure the safety of T3, correction calculation is required to be performed on T3 when the molten steel is low, and T is less than or equal to 5 ℃ (calculated by cooling 3 ℃ every 10 minutes—natural cooling of molten steel).
The original T1 amount is a relatively coarse estimate based on tundish weighing (which in practice will have errors and is excluded here) while taking into account quality and casting safety (preventing static pressure drop anomalies). The coefficient can be given according to the size of the section, so that enough judgment space is reserved for the second deceleration.
In this process, the determination of the first deceleration point, the calculation (including correction) of the second deceleration starting point, and the molten steel consumed for the holding time before the final casting (ladle replacement) of the different steel grades are involved. And prevent the slag from rolling up in the abnormal lowest tonnage (height), cause the waste billet, influence the production quality.
Compensating at the end of tundish casting includes:
the thermocouple feedback signal delays supplementing DC (substantially constant);
covering agent weight compensation FG (weight controllable);
weight compensation NG for the loss of refractory materials in the tundish (loss coefficient multiplied by weight of molten steel in each ladle multiplied by continuous casting number);
The continuous casting speed reduction adjustment delay compensates PH (calculated according to the steel passing amount of different crystallizers).
When the speed reduction of the liquid phase measuring point temperature of the continuous tundish temperature measuring device meets the condition, the casting of the steel plate is finished, the molten steel quantity in the tundish is calculated according to the steel grade coefficient alpha, and then the actual tonnage at the end of the casting of the tundish is compensated, and the method comprises the following steps:
a tundish weighing value W1 when molten steel contacts a continuous temperature measuring thermocouple during tundish casting;
The highest tonnage alarm is given out for the last time before the final pouring of the tundish and the weighing value W2 of the tundish at the moment;
a tundish weighing value W3 when the continuous temperature measuring couple is disconnected from the steel liquid level before the tundish is finally poured;
the tundish weight judgment deviation delta G1 caused by the response delay of the continuous temperature measurement couple, namely delta G1= [ W1- (V1-V2) t1+ (W3-V3) t1]/2 because of the heat transfer time difference t1 of the refractory materials wrapped outside the temperature measurement couple;
Wherein V1 is molten steel flowing into the tundish every second when the ladle slide plate is fully opened in a full ladle state; v2 is the steel flux per second of the current casting; v3 is the outflow speed of the tundish molten steel when the continuous temperature measuring couple is disconnected from the liquid level of the steel before final casting;
The system automatically accumulates the adding quantity delta G2 of the tundish covering agent;
In the state of low superheat degree, the solidification amount of molten steel in the tundish; because no new molten steel is injected, the heat dissipation speed of the tundish is high, the actual molten steel amount is low easily caused by the fact that the cold steel in the tundish is cooled, and the solidification speed of the cold steel is different due to different steel types, different superheat degrees and different temperature actual results, so that the solidification amount deviation delta G3 of the molten steel is required to be according to the solidification speed of the steel types at a specific temperature, namely the steel type temperature compensation coefficient alpha, namely delta G3 = alpha t2;
wherein alpha is the condensation speed of molten steel at different temperatures of different steel grades in a low-temperature state; t2 is the time calculated by the system from the safe initial pull speed V4 deceleration starting point weighing W4 to the final pouring point weighing W5;
Tundish bottom resistance to erosion: after continuous casting for a certain time according to the tundish, the bottom refractory material has certain erosion and melting loss, so that the actual content is increased, and an erosion influence coefficient beta is introduced, namely, the tundish expansion deviation delta G4 = beta t3 caused by erosion;
wherein, beta is an erosion influence coefficient; t3 is the total pouring time of the tundish;
Low tonnage weighing linear compensation of the tundish; i.e. the weighing between W3 and W5 is linearly compensated Δg5.
The method comprises the steps of recording (mainly comprising an information collecting and processing device, information output, tonnage correction, speed reduction maintaining and final casting) through an upper computer, calculating to obtain a compensated W3' =W3+delta G1-delta G2-delta G3+delta G4+delta G5, correcting the weighing of the tundish, and starting to reduce the speed when the weight of the tundish reaches W4.
Of the above parameters, t1 is a constant obtained by experiment; t2 is calculated according to the casting section, the initial speed, the deceleration rate, the deceleration target speed and the holding time (each time calculated by a computer according to the current section and the speed); alpha is provided empirically as shown in the following table:
note that: wherein, deltaT is a continuous temperature measurement temperature value 1 minute before the tonnage of the tundish is W3.
The invention relates to a method for measuring and calculating tonnage of a continuous casting tundish (comprising the process of inserting an iron plate of different steel types, changing the ladle or casting the continuous casting). The method is an effective method for improving the online intelligent operation and the safe operation rate of the continuous casting machine under the robot operation, unmanned on site, less man and complex operation environment.
According to the invention, the advance characteristic is found according to the temperature data information obtained by the original tundish thermometer, and a novel judging method is summarized by combining the actual production running state, so that whether the liquid molten steel in the tundish reaches the low liquid level or not is automatically judged, a blocking list is automatically closed after the liquid molten steel reaches the low liquid level, and the liquid molten steel automatically enters into a CAST (compact casting) preparation state, thereby avoiding the danger caused by manual operation and the influence on the accuracy caused by a manual judging mechanism.
And deducing based on a calculation model of the molten steel amount in the tundish, and combining three compensation algorithms to improve the accuracy degree of the molten steel amount in the tundish.
The proposal of the calculation logic part changes the defects caused by the excessive dependence on the weighing device and the artificial estimation, can calculate the molten steel quantity cast in real time in the process of reducing the continuous casting speed according to the time ratio generated by reducing the continuous casting speed, and deduces the molten steel quantity in the tundish in real time on line. Finally, the automatic closing of the rod is achieved when the minimum molten steel amount in the tundish is reached, and the production optimization is ensured.
It will be appreciated by persons skilled in the art that the above embodiments are provided for illustration only and not for limitation of the invention, and that variations and modifications of the above described embodiments are intended to fall within the scope of the claims of the invention as long as they fall within the true spirit of the invention.
Claims (9)
1. A method for measuring and compensating the weight of continuous casting tundish on-line residual steel is characterized in that:
And processing the signal feedback time after the continuous temperature measurement sampling frequency of the molten steel by a continuous temperature measurement device of the tundish, judging the low liquid level state of the molten steel in the tundish according to the inflection point of the continuous temperature measurement value, the change of the weighing value of the tundish, the casting steel grade characteristic and the overheat degree change trend model, calculating the feedback time based on the thermocouple temperature measurement and the steel passing amount, and compensating when the casting of the tundish is finished.
2. The method for measuring and compensating the weight of the continuous casting tundish online residual steel according to claim 1, which is characterized in that: the continuous temperature measuring device of the tundish is arranged at the middle lower part of the tundish.
3. The method for measuring and compensating the weight of the continuous casting tundish on-line residual steel according to claim 1, wherein the judgment of the low liquid level state of the molten steel in the tundish is specifically as follows:
The temperature of the liquid-phase measuring point of the tundish, which is measured by the continuous temperature measuring device of the tundish, is reduced from 1550 ℃ to 1450 ℃ in a range, the required time period is 2-8 minutes, and the liquid-phase measuring point is judged to be in a low liquid level state.
4. The method for measuring and compensating the weight of the continuous casting tundish online residual steel according to claim 3, which is characterized in that: when the temperature of the liquid-phase measuring point of the continuous tundish temperature measuring device is reduced to more than 12.5 ℃ in average every minute, the liquid molten steel at the position of the liquid-phase measuring point of the continuous tundish temperature measuring device is judged to be separated into the air.
5. The method for measuring and compensating the weight of the continuous casting tundish on-line residual steel according to claim 1, wherein the steel passing amount m=ρv;
wherein ρ is the specific gravity value of steel, which is 7.6g/cm 3; v is the volume of slab cast during this period.
6. The method for measuring and compensating the weight of the continuous casting tundish on-line residual steel according to claim 5, wherein the volume V of the crystallizer is specifically calculated as follows:
V=x×y×s;
wherein x is the width of the crystallizer; y is the thickness of the crystallizer; s is the length of the slab cast during this period;
Wherein s=v 0t0+(v0t1-1/2gt1^2)+v1t2;
Where v 0 is the pre-deceleration speed, t 0 is the hold time at the pull-up speed, t 1 is the deceleration process time, g is the deceleration rate, v 1 is the hold speed, and t 2 is the hold time.
7. The method for measuring and compensating the weight of the continuous casting tundish on-line residual steel according to claim 3, wherein the compensating at the end of the casting of the tundish comprises:
The thermocouple feedback signal delays supplementing DC;
covering agent weight compensation FG;
Weight compensation NG of the refractory loss in the tundish;
continuous casting speed reduction adjustment delay compensation PH;
when the speed reduction of the liquid phase measuring point temperature of the continuous tundish temperature measuring device meets the condition, the casting is finished, the molten steel quantity in the tundish is calculated according to the steel grade coefficient alpha, and then the actual tonnage at the end of the casting of the tundish is compensated, and the method comprises the following steps:
a tundish weighing value W1 when molten steel contacts a continuous temperature measuring thermocouple during tundish casting;
The highest tonnage alarm is given out for the last time before the final pouring of the tundish and the weighing value W2 of the tundish at the moment;
a tundish weighing value W3 when the continuous temperature measuring couple is disconnected from the steel liquid level before the tundish is finally poured;
tundish weight judgment deviation delta G1 caused by response delay of continuous temperature measurement couple;
The system automatically accumulates the adding quantity delta G2 of the tundish covering agent;
Deviation delta G3 of solidification quantity of molten steel;
Tundish expansion deviation delta G4;
tundish low tonnage weighing linear compensation deltag 5.
8. The method for measuring and compensating the weight of the continuous casting tundish online residual steel according to claim 7, which is characterized in that: the weight compensation of the refractory loss in the tundish ng=loss coefficient×weight of molten steel in each ladle×continuous casting number;
and calculating the continuous casting speed reduction adjustment delay compensation PH according to the steel passing quantity of different crystallizers.
9. The method for measuring and compensating the weight of the continuous casting tundish online residual steel according to claim 7, which is characterized in that: the tundish weight judgment deviation delta G1 = { [ W1- (V1-V2) t1] + [ W3-V3 t1] } 2 caused by the response delay of the continuous temperature measurement couple;
Wherein V1 is the ladle weighing descending speed when the tundish is started to be poured to W1; v2 is the actual speed of the pouring basket when the initial furnace is started to reach W1 and the pouring basket is poured into the crystallizer; v3 is the outflow speed of the tundish molten steel when the continuous temperature measuring couple is disconnected from the liquid level of the steel before final casting; t1 is the response delay time of the temperature measurement thermocouple;
The molten steel solidification amount deviation Δg3=α×t2;
wherein alpha is the condensation speed of molten steel at different temperatures of different steel grades in a low-temperature state; t2 is the time calculated by the system from the safe initial pull speed V4 deceleration starting point weighing W4 to the final pouring point weighing W5;
the tundish expands capacity deviation Δg4 =βtt3;
wherein, beta is an erosion influence coefficient; t3 is the total pouring time of the tundish;
The tundish low tonnage weighing linear compensation delta G5 is the weighing linear compensation from W3 to W5.
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