CN102814481B - Continuous casting secondary cooling dynamic control method based on online temperature measuring and heat transferring model - Google Patents

Abstract

The invention provides a continuous casting secondary cooling dynamic control method based on an online temperature measuring and heat transferring model. The continuous casting secondary cooling dynamic control method includes constructing a new continuous casting secondary cooling dynamic model, planting the new continuous casting secondary cooling dynamic model into a computer system, embedding the new continuous casting secondary cooling dynamic model into a water distribution system of a continuous casting machine and enabling the new continuous casting secondary cooling dynamic model to be in communication connection with a PLC (programmable logic controller); mounting a non-contact type temperature measuring instrument CQU-2MB in a continuous casting straightening area and enabling the non-contact type temperature measuring instrument CQU-2MB to be in communication connection with the PLC and to form a feedback circuit with the new continuous casting secondary cooling dynamic model; acquiring various technological operation parameters by the new continuous casting secondary cooling dynamic model in an online manner during continuous casting; carrying out simulation computation of parameters in real time; measuring the temperature of the surface of a casting blank in the continuous casting straightening area in an online manner; and controlling and adjusting the quantity of water for continuous casting secondary cooling by comparison and computation for the temperature measured in real time in the online manner, the temperature which is predicted by a heat transferring model and is corrected in real time and the temperature of the surface of a target casting blank. By the continuous casting secondary cooling dynamic control method, accuracy and reliability of continuous casting secondary cooling dynamic control and stability of running of continuous casting secondary cooling are greatly improved, and the method is simple and feasible in implementation and obvious in effect.

Description

Continuous casting two cold dynamic control method based on temperature measurement on-line and heat transfer model

Technical field

The present invention relates to a kind ofly based on continuous casting blank temperature on-line measurement FEEDBACK CONTROL and mathematical Model of Heat Transfer, dynamically control the continuous casting two cold combining and dynamically control new method.The method is mainly used in the direct casting forming field of metallurgy industry ferrous materials and other metal materials, is applicable to the cooling dynamic control of secondary of all kinds conticaster.

Background technology

Along with the high speed development of steel industry, output of steel has reached state of saturation both at home and abroad, and the quality of product made from steel has become the important goal of steel industry development.The quality of continuous casting billet has material impact to the production of subsequent product and end product quality.The production of high-quality strand, Cheng Liao continuous casting manufacturing enterprise and continuous casting worker's main target, promoting steel products quality has become the main path that iron and steel enterprise enhances competitiveness.One important procedure producing as iron and steel, casting process is the key link of steel products coagulation forming, quality control, the cooling control of secondary in casting process is unreasonable is that strand cracks, the major reason of center segregation, the defect such as loose.Strengthening the online stability control of casting process casting blank solidification state, is important means and the basic guarantee that improves continuous casting billet quality.

Be accompanied by birth and the fast development of continuous casting of iron and steel technology, the cooling control method of continuous casting secondary has also obtained developing by leaps and bounds.At the Development of Continuous Casting Technique initial stage, the secondary of conticaster is cooling to be controlled by a fixing water meter conventionally, and by the temperature of water distribution workman naked eyes judgement continuous casting billet, thereby secondary cooling water is artificially adjusted.Along with development and the application of computer simulation technique in metallurgy of technology, secondary cooling water is no longer to be adjusted by the water meter of fixing and artificial judgement, but according to continuous casting billet target surface temperature, by off-line simulation of Heat Transfer model, is calculated and obtained.Secondary cooling water amount is a curved line relation system changing with pulling rate normally, and this meets pulling rate continually varying actual conditions more.Full-fledged along with automatic technology and computer modeling technique, the cooling control of secondary of current most of conticaster has developed into online computer dynamic and has controlled.Two cold dynamic control technologies have been strengthened the dirigibility of the cooling control of secondary greatly, pulling rate, the degree of superheat and the impact cooling on secondary of other operating procedure factors can be considered to a certain extent, and two cold water distributions of conticaster can be adjusted online according to actual process operating parameter.

For two cold dynamic control technologies of casting process, Chinese scholars has all been done a large amount of research.Two cold dynamic controls of main flow are the dynamic control based on Mathematical Model For Heat Transfer In Solidification at present, by setting up corresponding continuous casting two cold heat transfer model, Real-time Collection continuous casting production operation parameter (as pulling rate, the degree of superheat etc.), calculate the temperature field of continuous casting billet, and make comparisons with predetermined continuous casting billet target surface temperature, the online secondary cooling system of determining casting machine, and implement online adjustment and control.The application of two cold dynamic control methods, makes great progress the cooling control of continuous casting secondary, and dirigibility strengthens greatly, and can solve to a certain extent the interference of the operating parameter fluctuations such as pulling rate, the degree of superheat.But this dynamic control method that relies on mathematical model of the computer completely still has some limitations:

1. two cold kinetic-control systems are open-loop control systems, and it does not remove to investigate actual casting blank surface temperature, but self heat transfer model is calculated to strand temperature field, are used as continuous casting billet actual temperature, and for judgement and two cold controls.

2. the control effect of two cold kinetic-control systems its accuracy and the reliability of heat transfer model that place one's entire reliance upon.If the boundary condition of heat transfer model does not conform to actual conticaster boundary condition, the true hot state of continuous casting billet just cannot correctly be reflected in the strand temperature field that heat transfer model calculates, and can not effectively implement secondary cooling water and dynamically control, and even causes casting blank defect.

3. casting process is a continuously motion, very complicated cooled and solidified process.Due to the limitation that the temporal requirement of On-line Control and Mathematical Models solve, Dynamic Heat Transfer be all one-dimensional model conventionally, has done a lot of simplification and assumptions, and the boundary condition of heat transfer model is difficult to meet completely the actual boundary condition of conticaster production.

Above-mentioned 3 restricted technical matterss based on heat transfer model two cold dynamic controls, the just major reason of at present a lot of iron and steel enterprise's caster two cold kinetic-control systems and two cold dynamic soft-reduction system applies poor effect.

For avoiding the interference of solidification and heat transfer model accuracy, another method is that the continuous casting billet skin temperature according to actual measurement carries out that secondary cooling water is online dynamically to be controlled, i.e. two cold closed-loop dynamic control methods.In control procedure, the surface temperature of continuous casting billet is carried out to on-line measurement, Real-time Feedback is got back to and is controlled in model, has the model of control to calculate in real time, and continuous casting secondary cooling water is dynamically controlled.The reliability that the two cold closed-loop dynamic based on casting blank surface temperature on-line measurement the are controlled models order of accuarcy that strand actual temperature is measured that places one's entire reliance upon.In casting process, continuous casting billet is the object of high temperature motion, has water smoke, dust, greasy dirt etc. in residing environment, and casting billet surface is covered with iron scale and the moisture film of irregularity simultaneously.These factors all cause the on-line measurement of casted blank surface temperature of continuous casting secondary cold region more difficult.For the measurement of continuous casting billet skin temperature, can only carry out online Measurement accuracy to the continuous casting billet skin temperature in the two less regions of cold middle and later periods water smoke at present.In two cold-zones that cannot directly measure casting blank surface temperature, the accuracy of the dynamic control of its water yield can not get the assurance of controlling.Therefore, the two cold dynamic control models based on casting blank surface temperature on-line measurement still have some limitations in actual continuous casting application.

In sum, no matter be two cold dynamic control methods or the two cold dynamic control methods based on casting blank surface temperature on-line measurement based on solidification and heat transfer model, all there is at present its limitation, directly have influence on control and the raising of continuous casting billet quality.

Summary of the invention

For prior art above shortcomings, the present invention solves the sex-limited and accuracy problem of the dynamic control office of existing continuous casting two cold, improves accuracy, reliability that continuous casting two cold is dynamically controlled, and the stability of operation; To promote steel products quality, improve continuous casting throughput rate.

Solve the problems of the technologies described above, the technical solution used in the present invention is as follows: a kind of continuous casting two cold dynamic control method based on temperature measurement on-line and heat transfer model, it is characterized in that, build the dynamic new model of continuous casting two cold and implant computer system, embed the water distribution system of conticaster, and be connected communication with PLC controller; Contactless temperature-measuring instrument CQU-2MB is installed on to continuous casting aligning region, and is connected communication with PLC controller, form backfeed loop with the dynamic new model of continuous casting two cold; Concrete grammar comprises the steps:

1) the current process operation parameter of the dynamic new model online acquisition of continuous casting two cold, comprise pulling rate, molten steel overheat, secondary cooling water amount, molten steel composition, secondary cooling water temperature, crystallizer coolant water temperature, and strand Temperature Distribution, shell thickness distribution and the liquid core length parameter obtaining in whole casting process calculated in real-time simulation;

2) application contactless temperature-measuring instrument CQU-2MB, on-line continuous is measured continuous casting billet skin temperature;

3) in conjunction with the casting blank surface temperature of surveying casting blank surface temperature and the real-time Dynamic Heat Transfer simulation calculation of revising, according to the partition factor in two cold each loops, the two real casting blank surface temperatures in cold each loop of the current control cycle of calculative determination;

4) in conjunction with actual casting blank surface temperature and target surface temperature, adopt pid control algorithm, calculate the cooling water inflow that obtains current control cycle two cold each loops, and output to PLC controller, the water yield of each two cold loops of On-line Control adjustment;

5) when continuous casting secondary cooling water being carried out to dynamically control, according to the strand temperature of the strand temperature of actual measurement and heat transfer model prediction, adopt pid algorithm, the online boundary condition of revising Dynamic Heat Transfer, revise the heat transfer coefficient in two cold each loops, for next heat transfer model, calculate and use;

6) step 1)-step 5) all completes fast in a control cycle, and control cycle was set in 5 seconds, and each control cycle can repeated execution of steps 1)-step 5).

Further, in a control cycle, the control step of described two cold dynamic new models comprises:

A, determine current continuous casting billet real surface temperature:

In conjunction with observed temperature and the real-time heat transfer model predicted temperature of revising, according to both differences, determine each current continuous casting billet real surface temperature of two cold loops, computational algorithm is as follows:

(1)

In formula: ithe sequence number of-each two cold control loops,

=1,2,3,

τ-the time, s;

t _i ( τ)-constantly τthe ithe strand real surface temperature of two cold loops, ° C;

t _c,i ( τ)-constantly τof heat transfer model prediction and calculation ithe casting blank surface temperature of two cold loops, ° C;

t _cs ( τ)-constantly τthe casting blank surface temperature of the continuous temperature measurement point of heat transfer model prediction and calculation, ° C;

t _m ( τ)-constantly τcontinuous temperature measurement is put measured casting blank surface temperature, ° C;

η-temperature correction coefficient; Relevant with the accuracy of observed temperature, value is 0.8-1.2 conventionally, is 1.0 under normal circumstances;

e( i)- ithe partition factor of two cold loops; This coefficient is relevant with two cold loop water yield ratios, two cold loop length etc., 0 < e( i) < 1, the partition factor sum of all two cold loops is necessary for 1.0;

e _s the partition factor of-continuous temperature measurement point place two cold loops;

B, calculate and adjust and control the continuous casting two cold water yield in real time:

In conjunction with actual casting blank surface temperature and target surface temperature, the water yield of each two cold control loops of On-line Control adjustment; Control method adopts PID control method, and computational algorithm is as follows:

　　　　　　 (2)

(3)

In formula: Δ t _i ( τ)-constantly τthe itwo cold loop strand real surface temperature and target surface temperature gaps, ° C;

t _{aim, i} - ithe target casting blank surface temperature of two cold loops, ° C;

q _i ( τ)-constantly τthe ithe control water yield of two cold loops, L/min;

k _p , k _i , k _d -be respectively proportional gain, integral time and derivative time.

For ease of computer programming, realize, conventionally can carry out difference discrete and obtain process control difference equation controlling the differential equation of model or transport function.Formula (3) is carried out obtaining after difference discrete following governing equation:

(4)

In formula: q _i ( k), q _i ( k-1)-constantly kand constantly k-1 ithe control water yield of two cold loops, L/min;

Δ τ-control time step-length, i.e. control cycle, s.

C, revise in real time the boundary condition of Dynamic Heat Transfer:

When continuous casting secondary cooling water being carried out to dynamically control, according to the temperature of observed temperature and heat transfer model prediction, revise online the boundary condition of Dynamic Heat Transfer, revise the heat transfer coefficient in two cold each loops; For improving the boundary condition correction efficiency of Dynamic Heat Transfer, make the actual heat transfer boundary condition of its level and smooth convergence continuous casting, adopt PID control method to revise the heat transfer coefficient of each two cold loops of Dynamic Heat Transfer:

　　　　　　 (5)

(6)

In formula: Δ t _h,i ( τ)-constantly τthe ithe difference of two cold loop model prediction computation temperature and strand real surface temperature, ° C;

h _i ( τ)-constantly τthe ithe heat transfer coefficient of two cold loops, W/ (m ²° C);

Formula (6) is carried out obtaining after difference discrete following governing equation:

(7)

In formula: h _i ( k), h _i ( k-1)-constantly kand constantly k-1 ithe heat transfer coefficient of two cold loops, W/ (m ²° C).

Compared to existing technology, the present invention has following beneficial effect:

1, combine two cold closed-loop dynamic control methods based on casting blank surface temperature on-line measurement and the advantage of the two cold dynamic control methods based on solidification and heat transfer model, and complementary both deficiency and limitation, propose to have set up a kind of new continuous casting two cold dynamic model; Greatly improved accuracy, reliability that continuous casting two cold is dynamically controlled, and the stability of operation.

2, apply the casting blank surface temperature of on-line measurement, revise in real time the boundary condition of Dynamic Heat Transfer, can guarantee that Dynamic Heat Transfer is at every moment consistent with the actual heat transfer of continuous casting, improve the temperature prediction accuracy rate of Dynamic Heat Transfer; Made up the inaccurate problem of the dynamic model of secondary cooling water temperature prediction based on solidification and heat transfer model.

3, adopt strand temperature online to measure the method combining with Dynamic Heat Transfer prediction, determine continuous casting billet actual temperature, and expand the strand true temperature that obtains two cool regions that cannot carry out on-line measurement, definite continuous casting blank temperature is more realistic, more reliable; Made up the problem that two cold closed-loop dynamic control methods based on casting blank surface temperature on-line measurement can only measure portion region strand temperature, and the inaccurate problem of the dynamic model of secondary cooling water temperature prediction based on solidification and heat transfer model.

4, take existing continuous casting two cold dynamic control method as basis, learn from other's strong points to offset one's weaknesses, set up a kind of new continuous casting two cold dynamic model, realize the cooling long-term stability of continuous casting secondary and accurately dynamically control, application foundation possesses, and the method application is simple, and effect is obvious.

Accompanying drawing explanation

Fig. 1 is the dynamic new model control principle drawing of continuous casting two cold of the present invention;

Fig. 2 is the control system sketch of the dynamic new model of continuous casting two cold of the present invention.

Embodiment

Referring to Fig. 1 and Fig. 2, a kind of continuous casting two cold dynamic control method based on temperature measurement on-line and heat transfer model, dynamic control model and heat transfer model dynamic control model in conjunction with temperature measurement on-line build the dynamic new model of continuous casting two cold and implant computer system, embed the water distribution system of conticaster, and be connected communication with PLC controller; Contactless temperature-measuring instrument CQU-2MB is installed on to continuous casting aligning region, and is connected communication with PLC controller, form backfeed loop with the dynamic new model of continuous casting two cold; Concrete grammar comprises the steps:

1) the current process operation parameter of the dynamic new model online acquisition of continuous casting two cold, comprise pulling rate, molten steel overheat, secondary cooling water amount, molten steel composition, secondary cooling water temperature, crystallizer coolant water temperature etc., and the parameters such as strand Temperature Distribution, shell thickness distribution and liquid core length that obtain in whole casting process are calculated in real-time simulation;

2) application contactless temperature-measuring instrument CQU-2MB, on-line continuous is measured continuous casting billet skin temperature; Consider the impact of oxidized iron sheets on surface of casting blank, in some groups of temperature datas that obtain in continuous coverage, screen maximum temperature value as the true casting blank surface temperature of current control cycle, and feed back to continuous casting Central Control Room by PLC controller.Patent of the present invention is only measured the casting blank surface temperature in aligning region (critical area).

3) in conjunction with the casting blank surface temperature of surveying casting blank surface temperature and the real-time Dynamic Heat Transfer simulation calculation of revising, according to the partition factor in two cold each loops, the two real casting blank surface temperatures in cold each loop of the current control cycle of calculative determination;

4) in conjunction with actual casting blank surface temperature and target surface temperature, adopt pid control algorithm, calculate the cooling water inflow that obtains current control cycle two cold each loops, and output to PLC controller, the water yield of each two cold control loops of On-line Control adjustment;

5) when continuous casting secondary cooling water being carried out to dynamically control, according to the strand temperature of the strand temperature of actual measurement and heat transfer model prediction, adopt pid algorithm, the online boundary condition of revising Dynamic Heat Transfer, revise the heat transfer coefficient in two cold each loops, for next heat transfer model, calculate and use;

6) step 1)-step 5) all completes fast in a control cycle, and control cycle was set in 5 seconds, and each control cycle can repeated execution of steps 1)-step 5).

Further, in a control cycle (water yield control cycle), specifically comprise:

A, determine current continuous casting billet real surface temperature:

In conjunction with observed temperature and the real-time biography heat transfer model predicted temperature of revising, according to both differences, determine each current continuous casting billet real surface temperature of two cold loops, computational algorithm is as follows:

(1)

In formula: ithe sequence number of-each two cold control loops,

=1,2,3,

τ-the time, s;

t _i ( τ)-constantly τthe ithe strand real surface temperature of two cold loops, ° C;

t _c,i ( τ)-constantly τof heat transfer model prediction and calculation ithe casting blank surface temperature of two cold loops, ° C;

t _cs ( τ)-constantly τthe casting blank surface temperature of the continuous temperature measurement point of heat transfer model prediction and calculation, ° C;

t _m ( τ)-constantly τcontinuous temperature measurement is put measured casting blank surface temperature, ° C;

η-temperature correction coefficient; Relevant with the accuracy of observed temperature, value is 0.8-1.2 conventionally, is 1.0 under normal circumstances;

e( i)- ithe partition factor of two cold loops; This coefficient is relevant with two cold loop water yield ratios, two cold loop length etc., 0 < e( i) < 1, the partition factor sum of all two cold loops is necessary for 1.0;

e _s the partition factor of-continuous temperature measurement point place two cold loops;

B, calculate and adjust and control the continuous casting two cold water yield in real time:

In conjunction with actual casting blank surface temperature and target surface temperature, the water yield of each two cold control loops of On-line Control adjustment; Control method adopts PID control method, and computational algorithm is as follows:

　　　　　　 (2)

(3)

In formula: Δ t _i ( τ)-constantly τthe itwo cold loop strand real surface temperature and target surface temperature gaps, ° C;

t _{aim, i} - ithe target casting blank surface temperature of two cold loops, ° C;

q _i ( τ)-constantly τthe ithe control water yield of two cold loops, L/min;

k _p , k _i , k _d -be respectively proportional gain, integral time and derivative time.

For ease of computer programming, realize, conventionally can carry out difference discrete and obtain process control difference equation controlling the differential equation of model or transport function.Formula (3) is carried out obtaining after difference discrete following governing equation:

(4)

In formula: q _i ( k), q _i ( k-1)-constantly kand constantly k-1 ithe control water yield of two cold loops, L/min;

Δ τ-control time step-length, i.e. control cycle, s.

C, revise in real time the boundary condition of Dynamic Heat Transfer:

When continuous casting secondary cooling water being carried out to dynamically control, according to the temperature of observed temperature and heat transfer model prediction, revise online the boundary condition of Dynamic Heat Transfer, revise the heat transfer coefficient in two cold each loops.For improving the boundary condition correction efficiency of Dynamic Heat Transfer, make the actual heat transfer boundary condition of its level and smooth convergence continuous casting, the present invention also adopts PID control method to revise the heat transfer coefficient of each two cold loops of Dynamic Heat Transfer:

　　　　　　 (5)

(6)

In formula: Δ t _h,i ( τ)-constantly τthe ithe difference of two cold loop model prediction computation temperature and strand real surface temperature, ° C;

h _i ( τ)-constantly τthe ithe heat transfer coefficient of two cold loops, W/ (m ²° C).

Formula (6) is carried out obtaining after difference discrete following governing equation:

(7)

In formula: h _i ( k), h _i ( k-1)-constantly kand constantly k-1 ithe heat transfer coefficient of two cold loops, W/ (m ²° C).

Fig. 2 is shown in by the control system sketch of the dynamic new model of continuous casting two cold of the present invention.The temperature measurement on-line instrument of control system adopts the contactless temperature-measuring instrument CQU-2MB of the 2M of University Of Chongqing research department research and development, this temperature measurer can be avoided the impact of the disturbing factors such as water smoke effectively, solve under dust pollution and hot environment the problems such as long-time on-line operation, can measure exactly continuous casting billet skin temperature in long-term stability under the condition of high temperature, for improving the assurance that provides the foundation of the reliability of the dynamic new model of continuous casting two cold of the present invention.The temperature recording online feeds back to the dynamic new model of continuous casting two cold of Central Control Room by PLC controller, casting blank surface temperature in conjunction with the Dynamic Heat Transfer of revising in real time in line computation, calculate and obtain the current cooling water inflow that needs two cold each control loops of adjustment, and output to PLC controller, each two cold loop is dynamically controlled.Meanwhile, according to the strand temperature of actual measurement, revise the boundary condition of Dynamic Heat Transfer, guarantee that the boundary condition of Dynamic Heat Transfer is consistent with the actual heat transfer condition of continuous casting, thereby improve accuracy and the reliability of the dynamic new model of continuous casting two cold of the present invention.

The present invention is by setting up a kind of new continuous casting two cold dynamic model, and in casting process, casting blank surface temperature on-line measurement system moves with the two cold dynamic new models based on solidification and heat transfer model simultaneously; The various process operation parameters of the dynamic new model online acquisition of continuous casting two cold, the Temperature Distribution of whole continuous casting billet is calculated in real-time simulation; The casting blank surface temperature in continuous casting aligning district is carried out to on-line measurement (the present invention only measures the casting blank surface temperature of a position), feed back to the dynamic new model of continuous casting two cold; By the temperature of online actual measurement,, temperature and the target casting blank surface temperature of the heat transfer model prediction of correction in real time carry out comparing calculation, control in real time and adjust the continuous casting two cold water yield; Meanwhile, revise online the boundary condition of continuous casting heat transfer model, guarantee that the boundary condition of Dynamic Heat Transfer conforms to the actual heat transfer condition of continuous casting constantly.

The present invention is applicable to the direct casting forming field of metallurgy industry ferrous materials and other metal materials, can directly embed the water distribution system of all kinds conticaster, implements continuous casting two cold and dynamically controls.Take existing continuous casting two cold dynamic control method as basis, set up a kind of new continuous casting two cold dynamic model, realize the cooling long-term stability of continuous casting secondary and accurately dynamically control, application foundation and effect have all obtained actual proof, apply simplely, effect is obvious; There is higher Stability and veracity.

The cooling action effect of continuous casting secondary directly reacts in the temperature of strand, and it is to take strand temperature as controlling target that continuous casting two cold is dynamically controlled, and according to the gap of current casting blank surface temperature and target casting blank surface temperature, carries out control.

The present invention obtains colleges and universities of central authorities of University Of Chongqing basic scientific research operating cost (item number: subsidy 0903005203188,0211005202036); in conjunction with control the advantage of model and the two cold dynamic control models based on solidification and heat transfer model based on two cold closed-loop dynamic of casting blank surface temperature on-line measurement; and complementation both deficiency and limitation; a kind of new continuous casting two cold dynamic model is set up in proposition, has completed the research of the continuous casting two cold dynamic control method that new temperature measurement on-line combines with heat transfer model.The dynamic new model of this continuous casting two cold can be predicted the casting blank solidification state in whole casting process, also can on-line measurement key position the casting blank surface temperature in (as continuous casting aligning district), and carry out Comprehensive Control in conjunction with the strand temperature of online actual measurement and correction model prediction in real time, thereby guarantee accuracy and reliability that continuous casting two cold is dynamically controlled.The present invention, to promoting steel products quality, improves continuous casting throughput rate and has important practical significance.

Claims (1)

1. the continuous casting two cold dynamic control method based on temperature measurement on-line and heat transfer model, is characterized in that, builds the dynamic model of secondary cooling water and implants computer system, embeds the water distribution system of conticaster, and is connected communication with PLC controller; Contactless temperature-measuring instrument CQU-2MB is installed on to continuous casting aligning region, and is connected communication with PLC controller, form backfeed loop with continuous casting two cold dynamic model; Concrete grammar comprises the steps:

1) the current process operation parameter of continuous casting two cold dynamic model online acquisition, comprise pulling rate, molten steel overheat, secondary cooling water amount, molten steel composition, secondary cooling water temperature, crystallizer coolant water temperature, and real-time simulation is calculated, and the continuous casting blank temperature obtaining in whole casting process distributes, shell thickness distributes and liquid core length parameter;

2) application contactless temperature-measuring instrument CQU-2MB, on-line continuous is measured continuous casting billet skin temperature;

3) in conjunction with the continuous casting billet skin temperature of surveying continuous casting billet skin temperature and the real-time Dynamic Heat Transfer simulation calculation of revising, according to the partition factor in two cold each loops, the two real continuous casting billet skin temperatures in cold each loop of the current control cycle of calculative determination;

4) in conjunction with actual continuous casting billet skin temperature and target surface temperature, adopt pid control algorithm, calculate the cooling water inflow that obtains current control cycle two cold each loops, and output to PLC controller, the water yield of each two cold loops of On-line Control adjustment;

5) when continuous casting secondary cooling water being carried out to dynamically control, according to the continuous casting blank temperature of the continuous casting blank temperature of actual measurement and heat transfer model prediction, adopt pid algorithm, the online boundary condition of revising Dynamic Heat Transfer, revise the heat transfer coefficient in two cold each loops, for next heat transfer model, calculate and use;

Above step 1)-step 5) all completes fast in a control cycle, and control cycle was set in 5 seconds, and each control cycle can repeated execution of steps 1)-step 5);

In a control cycle, concrete control step comprises:

A, determine current continuous casting billet real surface temperature:

In conjunction with observed temperature and the real-time heat transfer model predicted temperature of revising, according to both differences, determine each current continuous casting billet real surface temperature of two cold loops, computational algorithm is as follows:

$T_i\left(\mathrm{\&tau;}\right)=T_{c,i}\left(\mathrm{\&tau;}\right)+\frac{e\left(i\right)}{e_s}\&CenterDot;\mathrm{\&eta;}(T_m\left(\mathrm{\&tau;}\right)-T_{\mathrm{cs}}\left(\mathrm{\&tau;}\right))---\left(1\right)$

In formula: the sequence number of each two cold loops of i-, i=1,2,3,

τ-time, s;

T _i(τ) the continuous casting billet real surface temperature of-moment τ i bis-cold loops, ℃;

T _c,i(τ) continuous casting billet skin temperature of i bis-cold loops of-moment τ heat transfer model prediction and calculation, ℃;

T _cs(τ) continuous casting billet skin temperature of the continuous temperature measurement point of-moment τ heat transfer model prediction and calculation, ℃;

T _m(τ)-τ continuous temperature measurement is put measured continuous casting billet skin temperature constantly, ℃;

η-temperature correction coefficient; Relevant with the accuracy of observed temperature, value is 0.8-1.2;

The partition factor of e (i)-i bis-cold loops; This coefficient and two cold loop water yield ratios, two cold loop length are relevant, 0<e (i) <1, and the partition factor sum of all two cold loops is necessary for 1.0;

E _sthe partition factor of-continuous temperature measurement point place two cold loops;

B, calculate and adjust and control the continuous casting two cold water yield in real time:

In conjunction with actual continuous casting billet skin temperature and target surface temperature, the water yield of each two cold loops of On-line Control adjustment; Control method adopts PID control method, and computational algorithm is as follows:

△T _i(τ)=T _i(τ)-T _aim,i (2)

$Q_i\left(\mathrm{\&tau;}\right)=K_P[\mathrm{\&Delta;}{T}_i\left(\mathrm{\&tau;}\right)+\frac{1}{K_I}{\&Integral;}_0^{\mathrm{\&tau;}}\mathrm{\&Delta;}{T}_i\left(\mathrm{\&tau;}\right)\mathrm{d\&tau;}+K_D\frac{\mathrm{d\&Delta;}{T}_i\left(\mathrm{\&tau;}\right)}{\mathrm{d\&tau;}}]---\left(3\right)$

In formula: Δ T _i(τ)-moment τ i bis-cold loop continuous casting billet real surface temperature and target surface temperature gaps, ℃;

T _{aim, i}the target continuous casting billet skin temperature of-i bis-cold loops, ℃;

Q _i(τ) the control water yield of-moment τ i bis-cold loops, L/min;

K _p, K _i, K _d-be respectively proportional gain, integral time and derivative time;

For ease of computer programming, realize, to controlling the differential equation of model or transport function, carry out difference discrete and obtain process control difference equation; Formula (3) is carried out obtaining after difference discrete following governing equation:

$Q_i\left(k\right)=Q_i(k-1)+K_P[(1+\frac{\mathrm{\&Delta;\&tau;}}{K_I}+\frac{K_D}{\mathrm{\&Delta;\&tau;}}){\mathrm{\&Delta;T}}_i\left(k\right)-(1+\frac{{2K}_D}{\mathrm{\&Delta;\&tau;}}){\mathrm{\&Delta;T}}_i(k-1)+\frac{K_D}{\mathrm{\&Delta;\&tau;}}{\mathrm{\&Delta;T}}_i(k-2)]---\left(4\right)$

In formula: Q _i(k), Q _i(k-1)-k and constantly the control water yield of i bis-cold loops of k-1 constantly, L/min;

Δ τ-control time step-length, i.e. control cycle, s;

C, revise in real time the boundary condition of Dynamic Heat Transfer:

When continuous casting secondary cooling water being carried out to dynamically control, according to the temperature of observed temperature and heat transfer model prediction, revise online the boundary condition of Dynamic Heat Transfer, revise the heat transfer coefficient in two cold each loops; For improving the boundary condition correction efficiency of Dynamic Heat Transfer, make the actual heat transfer boundary condition of its level and smooth convergence continuous casting, adopt PID control method to revise the heat transfer coefficient of each two cold loops of Dynamic Heat Transfer:

△T _h,i(τ)=T _c,i(τ)-T _i(τ) (5)

$h_i\left(\mathrm{\&tau;}\right)=K_P[{\mathrm{\&Delta;T}}_{h,i}\left(\mathrm{\&tau;}\right)+\frac{1}{K_I}{\&Integral;}_0^{\mathrm{\&tau;}}{\mathrm{\&Delta;T}}_{h,i}\left(\mathrm{\&tau;}\right)\mathrm{d\&tau;}+K_D\frac{d{\mathrm{\&Delta;T}}_{h,i}\left(\mathrm{\&tau;}\right)}{\mathrm{d\&tau;}}]---\left(6\right)$

In formula: Δ T _h,i(τ) difference of-moment τ i bis-cold loop model prediction computation temperature and continuous casting billet real surface temperature, ℃;

H _i(τ) heat transfer coefficient of-moment τ i bis-cold loops, W/ (m ²℃);

Formula (6) is carried out obtaining after difference discrete following governing equation:

$h_i\left(k\right)=h_i(k-1)+K_P[(1+\frac{\mathrm{\&Delta;\&tau;}}{K_I}+\frac{K_D}{\mathrm{\&Delta;\&tau;}}){\mathrm{\&Delta;T}}_{h,i}\left(k\right)-(1+\frac{{2K}_D}{\mathrm{\&Delta;\&tau;}}){\mathrm{\&Delta;T}}_{h,i}(k-1)+\frac{K_D}{\mathrm{\&Delta;\&tau;}}{\mathrm{\&Delta;T}}_{h,i}(k-2)]---\left(7\right)$

In formula: h _i(k), h _i(k-1)-k and the constantly heat transfer coefficient of i bis-cold loops of k-1 constantly, W/ (m ₂℃).

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