CN1840715A - Method for dynamic setting and control of hot-roll heating furnace temperature - Google Patents

Abstract

The related dynamic control method for heating furnace temperature comprises: (1) calculating end temperature of section with blank by forecasting model as forward recursion; (2) as the moved distance, dynamic calculating current target temperature; (3) calculating the current need temperature; (4) considering all difference, weighing with expert experience. This invention saves energy, improves precision, and can fit to production request.

Description

Method for dynamic setting and control of hot-roll heating furnace temperature

(1) technical field

The present invention relates to the kinetic controlling equation method of furnace temperature of heating furnace in the course of hot rolling.

(2) background technology

Hot-rolling heating furnace generally all is the stepped start-stop system continuous furnace of three sections or four-part form, and the major function of process control is the requirement according to the board briquette system, works out corresponding heating process, satisfying heating quality, and the requirement of rolling line rhythm, and energy-conservation as far as possible.The furnace plate blank time inside furnace is generally all more than 120 minutes, and tens meters of process furnace total lengths are if the dynamic control method of none is difficult to realize the automatic control of heat-processed.The key of control is dynamically to provide the target temperature of each section and forecast following board briquette rapidly and accurately, and sets the furnace gas temperature of each section according to necessary furnace temperature weighting.Method commonly used has two kinds, and a kind of is to be benchmark with the final target temperature of coming out of the stove all the time, and the problem of bringing is reasonably to distribute thermal load, because heating curve is non-linear, so right and wrong are excellent as a result for the forecast in the soaking zone front.Another kind method is determined each section target temperature according to each section in stove remaining time, and calculate the position of coming out of the stove from the position at current slab place always, its deficiency is that calculated amount is big, and each section target temperature is subjected to the influence of each section time inside furnace precision of prediction, and fluctuation is big.In order to ensure the desired target temperature of hot rolling technology and equal temperatures, must after having considered the factor that the influential slab of institute heats, the furnace temperature of heating furnace set(ting)value be adjusted dynamically.The main contents that furnace temperature of heating furnace is dynamically set comprise: the board briquette forecasting model; Dynamically determine the target temperature of each section of slab; Calculate the monolithic slab and reach the needed furnace temperature of place section target temperature, be also referred to as necessary furnace temperature; Necessary furnace temperature to all slabs in the section is weighted setting.

Existing board briquette forecasting model has two types, and one is meant the digital-to-analogue type, and it is an algebraic model, can only provide the medial temperature of slab, can't forecast the upper and lower surface temperature of slab; The 2nd, the unidimensional difference model, it will be to the layering of slab thickness direction in order to provide medial temperature, and what of the number of plies directly influence computational accuracy, the number of plies is many, and precision is relatively good, but calculated amount is also big, the number of plies is few, and calculated amount is little, but precision can't meet the demands again.Existing slab has two kinds in definite method of each section target temperature, and a kind of is that slab one shove charge just determines good, also constant later on, and this is a kind of method of static state, can't satisfy the requirement that hot rolling is produced; Another method be according to slab from how long surplusly coming out of the stove also and in each section remaining time, dynamically determine the target temperature at each section section end by given intensification slope, owing to the time is estimated, so that the target temperature that this method provides fluctuates is bigger.Because a slab goes to extraction from the process furnace of packing into, need through preheating section, first heating zone, second heating zone and soaking zone, total time is more than 120 minutes, existing method of calculation are that the necessary temp of outlet from the slab to the soaking zone all calculates, not only calculated amount is big, and because the time is estimated to be forbidden, forecast precision also is affected, the temperature of the compute segment that has need not, wasted computational resource.Also having the weighting of existing each section of process furnace furnace gas temperature to set, is to utilize some rules, and its shortcoming is loaded down with trivial details, and weighting coefficient jumps big.Therefore there are many deficiencies in existing furnace temperature of heating furnace kinetic controlling equation method, can not satisfy the needs that hot rolling is produced well.

(3) summary of the invention

The object of the present invention is to provide a kind of method for dynamic setting and control of hot-roll heating furnace temperature, this setting control method can forecast the temperature of slab rapidly and accurately, adjust the last target temperature of section in real time, satisfy the requirement of slab heating quality, rolling line rhythm better, and save energy, the prior art computational effort is big, the defective of low precision thereby overcome.

The present invention is achieved in that a kind of method for dynamic setting and control of hot-roll heating furnace temperature, it is characterized in that being undertaken by following four steps:

(1) adopt the board briquette forecasting model to calculate the last temperature of section of slab place section, these method of calculation are forward recursion;

(2) press slab miles of relative movement, the target temperature at each section of dynamic calculation slab section end;

(3) calculate the needed furnace gas temperature of slab present segment, promptly necessary furnace temperature;

(4) difference of considering all slabs of present segment is carried out expertise weighting setting.

Above-mentioned method for dynamic setting and control of hot-roll heating furnace temperature, described forecasting model is by the last temperature of regular hour step-length prediction section from the slab current position, the calculating of model parameter is forward recursion, and only calculates the upper and lower surface temperature and the medial temperature of slab.

Above-mentioned method for dynamic setting and control of hot-roll heating furnace temperature, the target temperature of described soaking zone is pre-determined by system, the target temperature of second heating zone determines that according to the equal temperature of processing requirement the target temperature of first heating zone and preheating section is to determine according to the temperature rise rate of given slab Moving Unit distance.

The board briquette forecasting model that the present invention adopts is a forward recursion, and is effectively simple, need not complicated calculating, and only need calculate slab upper and lower surface temperature and medial temperature; Be target temperature by each section of slab position calculation section end, rather than the time, because the length of each section of process furnace is fixed, what each slab moved also is fixed, so more stable accurately according to the target temperature at each section of slab position calculation section end; Carrying out necessary furnace temperature when calculating, only calculating the necessary furnace temperature of present segment, not only solved the nonlinear problem in the control, and calculated load is reducing greatly; When actual set, considered the slab difference of each section, utilize expertise to be weighted setting, weighting coefficient is a continually varying.The present invention can forecast the temperature of slab rapidly and accurately, adjusts the last target temperature of section in real time, satisfies the requirement of slab heating quality, rolling line rhythm better, and save energy, and the prior art computational effort is big, the defective of low precision thereby overcome.

(4) embodiment

A kind of method for dynamic setting and control of hot-roll heating furnace temperature is characterized in that being undertaken by following four steps:

(1) adopt the board briquette forecasting model to calculate the last temperature of section of slab place section, these method of calculation are forward recursion;

(2) press slab miles of relative movement, the target temperature at each section of dynamic calculation slab section end;

(3) calculate the needed furnace gas temperature of slab present segment, promptly necessary furnace temperature;

(4) difference of considering all slabs of present segment is carried out expertise weighting setting.

Specify each above-mentioned step below.

1. board briquette forecasting model, the function of board briquette forecasting model is by the last temperature of regular hour step-length prediction section from the slab current position, in the control of furnace plate blank heat-processed, all to predict each piece in the stove, if the Model Calculation amount is big, calculated load certainly will to be increased, the real-time of influence process control.This modelling technique does not need to calculate the temperature of each layer giving the correct time in advance, only need to calculate upper and lower surface temperature and medial temperature, and the calculating of model parameter is forward recursion, calculates simply, and speed is fast.Concrete method of calculation are as follows:

Slab upper surface temperature:

$\mathrm{\θ}(\frac{H}{2},t)=\underset{i=0}{\overset{4}{\mathrm{\Σ}}}{(-1)}^i{A}_i\left(t\right)+\underset{j=1}{\overset{4}{\mathrm{\Σ}}}{(-1)}^{j-1}{B}_j\left(t\right)$

The slab underlaying surface temperature:

$\mathrm{\θ}(-\frac{H}{2},t)=\underset{i=0}{\overset{4}{\mathrm{\Σ}}}{(-1)}^i{A}_i\left(t\right)+\underset{j=1}{\overset{4}{\mathrm{\Σ}}}{(-1)}^{j-1}{B}_j\left(t\right)$

The slab medial temperature:

θ _m(t)＝A ₀(t)

Above various model coefficient obtain by the following formula recursion:

$\left[\begin{array}{c}{A}_0\left(t\right)\\ A_1\left(t\right)\\ A_2\left(t\right)\\ A_3\left(t\right)\\ A_4\left(t\right)\\ B_1\left(t\right)\\ B_2\left(t\right)\\ B_3\left(t\right)\\ B_4\left(t\right)\end{array}\right]=\left[\begin{array}{ccccccccc}1& 0& 0& 0& 0& 0& 0& 0& 0\\ 0& m_1\left(t\right)& 0& 0& 0& 0& 0& 0& 0\\ 0& 0& m_2\left(t\right)& 0& 0& 0& 0& 0& 0\\ 0& 0& 0& m_3\left(t\right)& 0& 0& 0& 0& 0\\ 0& 0& 0& 0& m_4\left(t\right)& 0& 0& 0& 0\\ 0& 0& 0& 0& 0& m_1^{*}\left(t\right)& 0& 0& 0\\ 0& 0& 0& 0& 0& 0& m_2^{*}\left(t\right)& 0& 0\\ 0& 0& 0& 0& 0& 0& 0& m_3^{*}\left(t\right)& 0\\ 0& 0& 0& 0& 0& 0& 0& 0& m_4^{*}\left(t\right)\end{array}\right]\left[\begin{array}{c}{A}_0\left(0\right)\\ A_1\left(0\right)\\ A_2\left(0\right)\\ A_3\left(0\right)\\ A_4\left(0\right)\\ B_1\left(0\right)\\ B_2\left(0\right)\\ B_3\left(0\right)\\ B_4\left(0\right)\end{array}\right]$

$+\left[\begin{array}{c}{a}^2\·({\mathrm{\φ}}_S+{\mathrm{\φ}}_I)\·t/(\mathrm{\λ}\·H)\\ p_1\·K\·(1-m_1\left(t\right))\\ p_2\·K\·(1-m_2\left(t\right))\\ p_3\·K\·(1-m_3\left(t\right))\\ p_4\·K\·(1-m_4\left(t\right))\\ q_1\·R\·(1-m_1^{*}\left(t\right))\\ q_2\·R\·(1-m_2^{*}\left(t\right))\\ q_3\·R\·(1-m_3^{*}\left(t\right))\\ q_4\·R\·(1-m_4^{*}\left(t\right))\end{array}\right]$

In the following formula:

λ is the slab thermal conductivity, and ρ is a slab proportion, c _pBe slab specific heat, the three is the physical parameter that is heated slab, is given in the reality.

$a^2=\frac{\mathrm{\λ}}{\mathrm{\ρ}\·c_p},$ Be the slab thermal diffusivity.

$m_i\left(t\right)=\exp \{-\frac{4\·i^2\·a^2\·{\mathrm{\π}}^2\·t}{H^2}\}--(i=1~4)$

$m_j^{*}\left(t\right)=\exp \{-\frac{{(2j-1)}^2\·a^2\·{\mathrm{\π}}^2\·t}{H^2}\}--(j=1~4)$

T: calculate step-length, adopt period interval time (1～2 minute)

H: slab thickness

$K=\frac{({\mathrm{\φ}}_S+{\mathrm{\φ}}_I)\·H}{2\·\mathrm{\λ}},$ $R=\frac{({\mathrm{\φ}}_S+{\mathrm{\φ}}_I)\·H}{4\·\mathrm{\λ}}$

${\mathrm{\φ}}_S={\mathrm{\ϵ}}_S\·\mathrm{\σ}\·[{(T_S+273)}^4-{(\mathrm{\θ}(\frac{H}{2},0)+273)}^4]$

${\mathrm{\φ}}_I={\mathrm{\ϵ}}_I\·\mathrm{\σ}\·[{(T_I+273)}^4-{(\mathrm{\θ}(-\frac{H}{2},0)+273)}^4]$

ε _S: top, slab position sum total radiation coefficient, determine by burying the idol experiment

ε _I: bottom, slab position sum total radiation coefficient, determine by burying the idol experiment

σ: Stefann-Boltzmann constant

T _S: top, slab position furnace temperature is provided by thermopair in the stove

T _I: bottom, slab position furnace temperature is provided by thermopair in the stove

p ₁＝-0.106694，p ₂＝0.03125，p ₃＝-0.0183，p ₄＝0.007812

q ₁＝0.821068，q ₂＝-0.101245，q ₃＝0.0452020，q ₄＝-0.03248

2. dynamically determine the section target temperature, in order to satisfy the requirement of slab heat-up rate, general process furnace is divided into preheating section, first heating zone, second heating zone and soaking zone.The target temperature of soaking zone is determined by plan, promptly pre-determine by system, the target temperature of second heating zone is to determine according to the equal temperature of processing requirement, and the target temperature of first heating zone and preheating section is to determine according to the temperature rise rate of given slab Moving Unit distance.Concrete grammar is as follows:

The soaking zone target temperature ${\mathrm{\θ}}_5^{*}={\mathrm{\θ}}_{\mathrm{obj}}^{*};{\mathrm{\θ}}_{\mathrm{obj}}$ Be the target temperature of coming out of the stove.

The second heating zone target temperature ${\mathrm{\θ}}_4^{*}={\mathrm{\θ}}_{\mathrm{obj}}^{*}-\mathrm{\Δ}{\mathrm{\θ}}_J;$ Δ θ _JFor guaranteeing the soaking zone restriction temperature of the equal temperature of target, 15～30 ℃ of spans.

The first heating zone target temperature ${\mathrm{\θ}}_3^{*}=\frac{\mathrm{\β}\·{\mathrm{\θ}}_4^{*}\·l_{3\mathrm{pre}}+{\mathrm{\θ}}_3\·l_4}{\mathrm{\β}\·l_{3\mathrm{pre}}+l_4};$ β be first heating zone with the temperature rise rate of second heating zone than (value is 0.9～1.2), θ ₃Be the slab tracking temperature of current position, l ₄Be the segment length of second heating zone, l _3preBe the residue segment length of current position slab in first heating zone.

The target temperature of preheating section ${\mathrm{\θ}}_2^{*}=\frac{\mathrm{\α}\·{\mathrm{\θ}}_4^{*}\·l_{2\mathrm{pre}}+{\mathrm{\θ}}_2\·(l_3+l_4)}{\mathrm{\α}\·l_{2\mathrm{pre}}+l_3+l_4};$ α is the preheating zone and the temperature rise rate ratio of heating zone; θ ₂Be Current Temperatures in the preheating zone; l ₄Be the segment length of second heating zone, l ₃Be the segment length of first heating zone, l _2preBe the residue segment length of current position slab at preheating section, θ ₄ ^*Be the second heating zone target temperature, α be the preheating zone with the temperature rise rate of heating zone than (value is 0.9～1.2).

3. the calculating of necessary furnace temperature, so-called necessary furnace temperature is exactly the furnace gas temperature that calculated slab is necessarily required for the section of reaching target temperature in current position, this setting control method only need calculate the necessary furnace temperature of slab in the section of place, do not need to predict the situation of this slab, calculate thereby simplify greatly at other section.Concrete grammar is as follows:

At first obtain the factor of influence η of the change of expression i section furnace temperature to j section temperature out _{I, j}, i wherein, j=2,3,4,5 represent preheating section, a heating zone, two heating zones and soaking zone respectively.

${\mathrm{\η}}_{i,j}=\frac{\mathrm{\Δ}{\mathrm{Tout}}_i}{\mathrm{\Δ}{T}_j}$

Δ T in the formula _jThe change amount of representing j section furnace temperature; Δ Tout _iBe that i section temperature out is with respect to Δ T _jVariable quantity.

The furnace temperature that slab need change is:

$\mathrm{\ΔTFj}\left(k\right)=\frac{\mathrm{\Δ}{T}_{\mathrm{MDj}}}{{\mathrm{\η}}_j\left(k\right)}$

Wherein:

Δ TFj (k): j piece band steel is in the furnace temperature change amount of K section;

Δ T _MDj: the deviation of band steel j forecast temperature and target temperature;

η _j(k): the factor of influence of band steel j k section;

Z: there is section in band steel j;

At last, the necessary furnace temperature of band steel j is:

TFj(k)＝TFSj(k)+ΔTFj(k)

In the formula:

TFj (k): band steel j k section furnace temperature is set;

TFSj (k): band steel j k segment standard furnace temperature;

Δ TFj (k): band steel j k section furnace temperature adjustment amount.

4. the weighting of furnace temperature is set, in one section in the process furnace polylith slab is arranged, the corresponding again necessary furnace temperature of each piece slab, and finally can only set a furnace temperature, so will give priority to different slabs, this setting control method adopts weighted-average method, is characterized in weights at different situation continually varyings, and the rule of variation is determined according to expertise.

${\mathrm{\θ}}_{\mathrm{setk}}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}({\mathrm{\μ}}_i*w_i*{\mathrm{TF}}_i\left(k\right))/\underset{i=1}{\overset{n}{\mathrm{\Σ}}}(w_i*{\mathrm{\μ}}_i)$

θ _Setk: k section setting furnace temperature (℃);

N: the slab piece number of k section;

μ _i: whether i piece slab is special base, and special base is taken as 10, otherwise is 1;

w _i: set the weighting numerical value of usefulness, it provides according to expertise, and the method for determining is as follows:

At first, the necessary furnace temperature in the calculating K section and the deviation of average necessary furnace temperature:

$\mathrm{\Δ}{T}_i={\mathrm{TF}}_i\left(k\right)-\underset{i}{\overset{n}{\mathrm{\Σ}}}{\mathrm{TF}}_i\left(k\right)/n$

Then, determine according to following regular classification:

If the deviation maximum value that following formula provides is MAX (Δ T greater than 10 _i)＞10, then

$w_i=\left\{\begin{array}{c}1/60*\mathrm{\&Delta;}{T}_i+0.5;\mathrm{\&Delta;}{T}_i\&Element;[-\mathrm{30,30}]\\ 1;\mathrm{\&Delta;}{T}_i>30\\ 0;\mathrm{\&Delta;}{T}_i<-30\end{array}\right.$

If deviation maximum value MAX (the Δ T that following formula provides _i)≤10, then

$w_i=\left\{\begin{array}{c}9/40*\mathrm{\&Delta;}{T}_i+27/40;\mathrm{\&Delta;}{T}_i\&Element;[-\mathrm{30,10}]\\ 0.1;\mathrm{\&Delta;}{T}_i<-30\end{array}\right.$

Embodiment 1

When four process furnace are produced, the calculating step-length of board briquette forecasting model adopted 2 minutes, utilize the residue time inside furnace of current furnace gas temperature and this section, calculate the last position of section of this slab place section always, obtain slab section end forecast temperature from the current position of slab; Next calculate the last target temperature of section of slab, Δ θ _JGet 30 ℃, α gets 1, and β gets 1; According to method of the present invention, calculate the necessary furnace temperature of slab at last, and comprehensively the necessary furnace temperature of all slabs is weighted setting.

Embodiment 2

When three process furnace are produced, the calculating step-length of board briquette forecasting model adopted 1 minute, utilize the residue time inside furnace of current furnace gas temperature and this section, calculate the last position of section of this slab place section always, obtain slab section end forecast temperature from the current position of slab; Next calculate the last target temperature of section of slab, Δ θ _JGet 15 ℃, α gets 1, and β gets 1.1; According to method of the present invention, calculate the necessary furnace temperature of slab at last, and comprehensively the necessary furnace temperature of all slabs is weighted setting.

The results showed, can the forecast with unerring accuracy temperature of slab of the present invention, can adjust the section target temperature of slab place section according to the temperature dynamic ground of the position of slab and slab, reasonably set the furnace gas temperature of each section, thereby satisfy the requirement of slab heating quality, rolling line rhythm better, and reduced manual intervention and artificial variation, saved energy consumption.

Claims (3)

1. method for dynamic setting and control of hot-roll heating furnace temperature is characterized in that being undertaken by following four steps:

(1) adopt the board briquette forecasting model to calculate the last temperature of section of slab place section, these method of calculation are forward recursion;

(2) press slab miles of relative movement, the target temperature at each section of dynamic calculation slab section end;

(3) calculate the needed furnace gas temperature of slab present segment, promptly necessary furnace temperature;

(4) difference of considering all slabs of present segment is carried out expertise weighting setting.

2. method for dynamic setting and control of hot-roll heating furnace temperature according to claim 1, it is characterized in that forecasting model is by the last temperature of regular hour step-length prediction section from the slab current position, the calculating of model parameter is forward recursion, and only calculates the upper and lower surface temperature and the medial temperature of slab.

3. method for dynamic setting and control of hot-roll heating furnace temperature according to claim 1, the target temperature that it is characterized in that soaking zone is pre-determined by system, the target temperature of second heating zone determines that according to the equal temperature of processing requirement the target temperature of first heating zone and preheating section is to determine according to the temperature rise rate of given slab Moving Unit distance.