CN102929303B - Method and device for controlling concentration of acid for acid washing in production process of cold-rolled strip steel - Google Patents
Method and device for controlling concentration of acid for acid washing in production process of cold-rolled strip steel Download PDFInfo
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- 239000002253 acid Substances 0.000 title claims abstract description 275
- 238000000034 method Methods 0.000 title claims abstract description 44
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 31
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 23
- 239000010959 steel Substances 0.000 title claims abstract description 23
- 238000005406 washing Methods 0.000 title abstract description 6
- 238000013178 mathematical model Methods 0.000 claims abstract description 10
- 238000010992 reflux Methods 0.000 claims abstract description 4
- 238000005554 pickling Methods 0.000 claims description 40
- 239000011159 matrix material Substances 0.000 claims description 35
- 238000005259 measurement Methods 0.000 claims description 26
- 238000012546 transfer Methods 0.000 claims description 26
- 238000005097 cold rolling Methods 0.000 claims description 21
- 238000013461 design Methods 0.000 claims description 21
- 238000010586 diagram Methods 0.000 claims description 19
- 230000007246 mechanism Effects 0.000 claims description 9
- 238000004364 calculation method Methods 0.000 claims description 7
- 238000001802 infusion Methods 0.000 claims description 5
- 230000001447 compensatory effect Effects 0.000 claims description 4
- 230000004044 response Effects 0.000 claims description 4
- 230000002452 interceptive effect Effects 0.000 claims description 3
- 238000004088 simulation Methods 0.000 claims description 3
- 238000006467 substitution reaction Methods 0.000 claims description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 abstract description 20
- 230000008569 process Effects 0.000 abstract description 5
- 239000002699 waste material Substances 0.000 abstract description 4
- 238000003912 environmental pollution Methods 0.000 abstract description 3
- 230000008878 coupling Effects 0.000 abstract description 2
- 238000010168 coupling process Methods 0.000 abstract description 2
- 238000005859 coupling reaction Methods 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 23
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 14
- 235000021110 pickles Nutrition 0.000 description 10
- 229910052742 iron Inorganic materials 0.000 description 7
- 239000007788 liquid Substances 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 3
- 150000008064 anhydrides Chemical class 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 238000004448 titration Methods 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 208000037656 Respiratory Sounds Diseases 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
Abstract
The invention discloses a method and a device for controlling the concentration of acid for acid washing in the production process of cold-rolled strip steel. According to the method, three acid adding tanks are arranged on an acid circulation groove of an acid washing production line and communicated with one another, each acid adding tank and an acid solution reflux pipeline of the acid groove are connected in series with an acid concentration measuring device, the actual acid concentration value of an acid solution in the acid groove on the production line is measured by the acid concentration measuring device, fed back to a multivariable controller through an acid concentration analyzer, and compared with an acid concentration value which is required to be given by a process in the multivariable controller, and the difference is taken as an input value of a multivariable controller model. The acid concentrations among the three acid adding tanks influence one another, so a coupling relation among the acid concentrations of three measuring points is needed to be found, a mathematical model of the acid circulation groove of the production line is established, and multivariable decoupling computing is performed. By the control method, closed-loop control over the acid concentration can be realized, so that the using amount of hydrochloric acid is reduced, the amount of regenerated waste acid is reduced, and environmental pollution is reduced.
Description
Technical field
The present invention relates to a kind of cold-rolling steel strip pickling acid concentration control method and device.
Background technology
One important procedure in cold rolled strip steel production is exactly pickling, and pickling is the chemical process chemically removing oxidation on metal surface iron sheet.Iron scale on belt steel surface (
) be all the basic anhydride being not dissolved in water, when they are immersed in acid solution, these basic anhydride just with acid generation series of chemical.Iron scale on carbon steel or surface of low-alloy steel has the character of loose, porous and crackle, these iron scales are aligned together in company with band steel, straightening, transmission, through alternating bending, these gaps are strengthened further, thus acid solution and iron scale while reacting also with the iron matrix generation chemical reaction of outline band steel.The object of pickling to remove the oxide layer of belt steel surface, the hysteresis quality that conventional pickling ubiquity acid concentration controls, the stability contorting of concentration of hydrochloric acid cannot be realized, in actual production process, concentration of hydrochloric acid fluctuation is large, cause strip cleaning quality unstable, and the use amount of acid is bigger than normal, cause the waste of hydrochloric acid.Existing pickling unit adopts manual acid concentration to control mostly in the world at present, and main cause is that the accuracy that acid concentration is measured in real time is difficult to ensure do not have ripe measurement and control program.Generally that artificial timing sampling is also analyzed by titrimetry (titration) acid concentration to sample, carry out mending acid according to practical experience again and implement acid concentration Non-follow control, the disadvantage of this method is the hysteresis quality controlled, because the change of actual acid concentration and many factors closely related, the travelling speed of such as unit, the band width of steel, the degree of oxidation and steel grade etc. of belt steel surface, so artificial control method certainly will cause acid concentration fluctuation fluctuated large, instability is caused to the cleaning quality of band steel.
China Patent Publication No. CN1462321 discloses a kind of continuous acid-washing method and continuous pickling device, its continuous acid-washing method is, while supply acid solution respectively in multiple descaling baths of formation continuous pickling device in two or more descaling bath, while when carrying out pickling to the band steel of conveying, with the thickness of iron scale on described band steel, the width of described band steel and the transporting velocity of described band steel obtain acid solution aggregate supply, the allocation proportion of respective acid solution quantity delivered in described two or more descaling bath is obtained by the pickling pattern of described band steel and the transporting velocity of described band steel.The acid amount that pickling pipe controller consumes when predicting the pickle pickling in the 3rd groove and final groove being stored in continuous pickling device, determines respectively to the quantity delivered of pickle in the 3rd groove and final groove, makes acid solution feed system supply acid solution.Acid concentration CONTINUOUS VISCOSITY MEASURING is supplied the acid concentration of pickle in the 3rd groove of acid solution and final groove to make METHOD FOR CONTINUOUS DETERMINATION to being stored in respectively, and supply acid solution, to make the acid concentration that be stored in three groove and final groove pickle respectively with desired value match each other by acid solution feed system to the 3rd groove and final groove according to the tested acid concentration value recorded continuously.Acid concentration that discharge pickle from final groove, that be restricted can be made like this to be increased to 12%, to make the acid concentration being stored in pickle in other descaling baths increase simultaneously.
China Patent Publication No. CN1280633 discloses a kind of acid concentration CONTINUOUS VISCOSITY MEASURING, wherein combination has the body of pickle continuously along a direction by path being provided with and can making to hold pickle in descaling bath, to be arranged on body and to flow through the densitometer of the pickle of path, thermometer and conductivity meter with in fact METHOD FOR CONTINUOUS DETERMINATION, and calculating the calculation element of pickle acid concentration according to these measurement results.Use this acid concentration CONTINUOUS VISCOSITY MEASURING, FEEDBACK CONTROL forms the concentration of hydrochloric acid in several descaling baths of continuous acid-washing equipment in final descaling bath.
In above-mentioned disclosed document, relate to acid concentration measurement mechanism, the measuring method adopted relate to temperature survey, density measure and conductivity measurement, utilizes temperature, density and conductivity to extrapolate acid concentration.What adopt is the method that single argument controls acid concentration, and whole Measuring Time is longer, needs 1 hour, is a kind of discontinuous measurement method.Due to the hysteresis quality that acid concentration controls, cannot realize the stability contorting of concentration of hydrochloric acid, in actual production process, concentration of hydrochloric acid fluctuation is large, cause strip cleaning quality unstable, and the use amount of acid is bigger than normal, causes the waste of hydrochloric acid.
Summary of the invention
The object of the present invention is to provide a kind of cold-rolling pickling acid concentration control method of the present invention and device, this control method adopts Multivariable Decoupling Control method to realize acid concentration closed-loop control, thus saves hydrochloric acid consumption, reduces acid regeneration quantity, reduces environmental pollution.
To achieve these goals, the present invention adopts following technical scheme:
A kind of cold-rolling pickling acid concentration control method, the sour circulation groove of pickling lines configures three acid adding tanks, interconnect between three acid adding tanks, series connection acid concentration measurement mechanism on the acid solution reflux line of each acid adding tank and acid tank, the actual acid concentration value obtaining acid solution in acid tank on production line by the measurement of acid concentration measurement mechanism through acid concentration analyzer rear feed to multivariable controller, acid concentration value given with technological requirement in multivariable controller compares, and its difference is as the input value of multivariable controller models; Because the acid concentration between three acid adding tanks is interactive, namely it is inter-related for measuring the acid concentration value obtained, therefore the coupled relation between the acid concentration must finding out three measurement points, set up the mathematical model of production line acid circulation groove, and carry out the calculation of multivariable decoupling total, multivariable control system is converted into single variable control system; Concrete steps are:
The first step, sets up the multivariable model of controlled device descaling bath on pickling lines
The controlled device acid adding tank transfer function matrix of production line acid tank
expression formula be:
（7）
Acid adding tank transfer function matrix
inverse function
expression formula is:
（6）
In formula:
be the sectional area of three acid adding tanks, three acid adding volumes are identical,
it is the departure of the acid adding flow that technique allows;
Second step: the mathematical model obtained according to the first step
design advance compensator transfer function matrix
, make
become diagonally dominant matrix, its step is as follows:
1) existing drafting transport function is run
the software in the rare high forest belt of lattice, inputs transport function in the interface that software ejects
, inputted rear click and run, interface has obtained the nyquist diagram with the rare high forest belt of lattice, makes
become diagonally dominant matrix;
2) utilize existing diagonal dominance software, calculate advance compensator transfer function matrix
; Draw out
the rare high forest belt of lattice, the open cycle system after being compensated reaches diagonal dominance;
3rd step, adds acid tank transport function
single loop Compensation Design, due to
reach diagonal dominance, univariate method for designing therefore can be adopted to compensate design to three single loops, get
for pi regulator, gather examination by a few subparameter, obtain dynamic compensator transfer function matrix
value;
4th step, draws
with the nyquist diagram in the rare high forest belt of lattice, according to Nai Shi stability criterion, ensure that closed-loop system is stablized, obtain acid concentration feedback gain value
.
In the described first step, the sectional area value of three acid adding tanks is:
, the departure value of the acid adding flow that technique allows is:
; Substitution formula (7), then acid adding tank transfer function matrix
value:
（8）
Second step, can calculate advance compensator transfer function matrix
:
（9）
3rd step, gather examination by a few subparameter, can obtain:
（10）
4th step, obtains acid concentration feedback gain F (s) value:
;
;
.
In described 4th step, acid concentration feedback gain F (s) value is:
。（11）
5th step, adjustment acid concentration feedback gain
, make the step simulation curve of closed-loop system, adjustment acid concentration feedback gain
, complete multivariate Close-loop Control System Design.
6th step, closed-loop control system emulates, and can be obtained the unit-step nsponse curve of system, adjustment System parameter: comprise input parameter setting value, advance compensator transfer function matrix by existing simulation software
, dynamic compensator transfer function matrix
with acid concentration feedback gain
, make each main channel there is no over-control, meet steady-state error and the response speed requirement of system.
A kind of cold-rolling pickling acid concentration control device, comprises acid concentration analyzer, sensor, instrument setting and display system, controller, topworks; Described sensor comprises conductivity sensor and temperature sensor, and conductivity sensor measures the electrical conductivity of solution of production line acid circulation groove endpiece, the solution temperature of temperature sensor measurement acid tank endpiece; The signal of temperature sensor and conductivity sensor exports to acid concentration analyzer, calculates the concentration of solution in descaling bath in acid concentration analyzer, and this concentration is fed controller;
Described controller is multivariable controller, multivariable controller comprises dynamic compensation controller and Compensatory Control device, the acid concentration signal that multivariable controller inputs according to operating personnel and the acid concentration actual value that sensor measurement obtains carry out multivariable decoupling calculating, calculate control variable and export to topworks; Topworks controls infusion pump on each acid adding tank and fluid-delivery valve respectively, and each acid adding tank interconnects, and carries out transport acid hydraulic control system to circulation acid tank acid concentration.
Described acid adding tank is three, lays respectively at the centre position that steel plate enters the porch of acid tank, exit and descaling bath.
The present invention is by directly calculating out acid concentration to the real-time measurement of cold-rolling pickling production line circulation acid tank conductivity and temperature, Multivariable Decoupling Control method is adopted to realize acid concentration closed-loop control and optimization, thus save hydrochloric acid consumption, reduce acid regeneration quantity, reduce environmental pollution.
Cold-rolling pickling acid concentration control device of the present invention adopts multivariable controller, achieves free of discontinuities continuous coverage, can realize Automatic continuous and control; Apparatus structure is simple, and sour circulation groove concentration controls stable, not only ensures strip pickling quality, but also can save the consumption of acid.
Accompanying drawing explanation
Fig. 1 is cold-rolling pickling acid concentration Controlling Technology schematic flow sheet;
Fig. 2 is cold-rolling pickling acid concentration control device schematic diagram of the present invention;
Fig. 3 is acid concentration multivariable controller modeling schematic diagram of the present invention;
Fig. 4 is acid concentration multivariable controller schematic diagram of the present invention;
Fig. 5 is Nai Shi Array Method design cycle schematic diagram of the present invention;
Fig. 6 is acid concentration multivariate closed loop controller system chart of the present invention.
In figure: 11-117 valve, 21-23 well heater, 31-311 flowmeter, 41-411 pump, 5,51-53 acid adding tank; 1 roll, the sour head of 2 spray, 3 run-down pipes, 4 band steel; 6 sensors (acid concentration measurement mechanism), 7 acid concentration analyzers, 8 topworkies, 9 Compensatory Control devices, 10 dynamic compensation controllers, 100 production lines acid circulation groove (acid tank, descaling bath).
Embodiment
Below in conjunction with the drawings and specific embodiments, the invention will be further described.
See Fig. 1 and Fig. 2, a kind of cold-rolling pickling acid concentration control device, comprise acid concentration analyzer 7, sensor 6, instrument setting and display system, multivariable controller, topworks 8; Sensor 6 comprises conductivity sensor and temperature sensor, and conductivity sensor is measured production line acid circulation groove 100(and is called for short acid tank) electrical conductivity of solution of endpiece, the solution temperature of temperature sensor measurement acid tank endpiece.The signal of temperature sensor and conductivity sensor exports to acid concentration analyzer 7, the concentration that analytical calculation obtains solution in acid tank 100 is carried out in acid concentration analyzer 7, this concentration is fed multivariable controller, and multivariable controller comprises dynamic compensation controller 10 and Compensatory Control device 9.Production operation personnel can be set multivariable controller parameter by instrument setting and display system, the acid concentration signal that multivariable controller inputs according to operating personnel and the acid concentration actual value that sensor measurement obtains carry out multivariable decoupling calculating, calculate control variable and export to topworks 8, topworks 8 controls infusion pump on each acid adding tank 5 and fluid-delivery valve respectively, each acid adding tank 5 interconnects, transport acid hydraulic control system is carried out to circulation acid tank 100 acid concentration, and keeps acid concentration consistent.
See Fig. 1, on cold-rolling pickling production line, the general acid concentration by three points on production control line acid circulation groove 100, ensure that in whole production line, in acid tank, the concentration of solution meets the requirement with production technology, on pickling lines, be configured with three acid adding tanks 51 for this reason, 52, 53, each acid adding tank 51, 52, 53 and production line on descaling bath 100 between the pipeline that refluxes of acid solution on, an i.e. series connection acid concentration measurement mechanism 6(and sensor in run-down pipe 3), by this acid concentration measurement mechanism 6 measure obtain acid tank 100 internal acid solution on production line actual acid concentration value through acid concentration analyzer 7 rear feed to multivariable controller, compare in the inner acid concentration value given with technological requirement of controller, its difference is as the input value of controller model.Measurement point is typically chosen in the centre position that band steel 4 enters the porch of acid tank 100, exit and descaling bath.Because band steel 4 enters descaling bath 100 from entrance, export from outlet with certain speed, therefore the acid solution of acid tank 100 inside flows from entrance to Way out.Three acid adding tanks 51,52,53 interconnect, ortho acid flows into from No. three acid adding tanks 53, acid tank 100 porch and No. two acid adding tanks 52 are flowed to respectively after dilution in No. three acid adding tanks 53, flow to middle part and an acid adding tank 51 of acid tank 100 after again diluting in No. two acid adding tanks 52 respectively, again dilute in an acid adding tank 51 and flow to descaling bath 100 and waste acid pot respectively.Therefore the acid concentration between three acid adding tanks 51,52,53 is interactive, and it is inter-related for namely measuring the acid concentration value obtained, and shows that acid concentration controller is a multivariable controller, see Fig. 4.
In order to can accurately production control line acid circulation groove 100 inside acid concentration, the present invention is by the coupled relation between the acid concentration of finding out three measurement points, set up the mathematical model of production line acid circulation groove, and carry out the calculation of multivariable decoupling total, multivariable control system is converted into single variable control system.The present invention in order to founding mathematical models, by Fig. 1 cold-rolling pickling acid concentration Controlling Technology process flow diagram, the cold-rolling pickling acid concentration control device schematic diagram of composition graphs 2
,be equivalent to the acid concentration multivariable controller modeling schematic diagram of Fig. 3, obtain the mathematical model of controlled device according to Fig. 3
, utilize
carry out Multivariable Controller Design.In Multivariable Controller Design, adopt Nyquist array method, fundamental design idea is: first before controlled device, introduce an advance compensator
, weaken the coupling between each loop, make the open-loop transfer function matrix of system become diagonally dominant matrix, the design of whole multi-variable system is reduced to the Compensation Design of one group of single-variable system; Secondly according to univariate method for designing, design dynamic compensator
.Be acid concentration multivariable controller schematic diagram see Fig. 4, Fig. 4.After multivariable controller calculation process, calculate control variable and export to topworks, topworks controls infusion pump on each acid adding tank and fluid-delivery valve respectively, controls circulation acid tank acid concentration.
A kind of cold-rolling pickling acid concentration control method, the steps include:
The first step, sets up the multivariable model of controlled device descaling bath on pickling lines
Be acid concentration multivariable controller modeling schematic diagram see Fig. 3, Fig. 3, in figure:
be
the sectional area of individual acid adding tank, the sectional area of known acid adding tank is uniform;
for
moment acid adding tank
middle liquid level;
for
moment acid adding tank
to acid adding tank
flow;
for
moment acid adding tank
the flow of the liquid exported;
for
moment is input to acid adding tank
the flow of liquid;
Get: the flow velocity flowing into acid adding tank liquid is
for the input quantity of system;
The liquid level of acid adding tank
for the output quantity of system;
The flow of acid adding tank output liquid
for the external interference amount of system;
So, by the philosophy of physics, the general expression of the differential equation describing this system can be derived:
（1）
Wherein:
Order
Wherein:
,
,
,
be respectively
,
,
,
specified steady-state value;
,
,
,
, be respectively
,
,
with
relative to the variable quantity of specified steady-state value;
,
;
So, can obtain: relative to the little differential equations with deviating arguments of specified steady-state value:
（2）
Conveniently, if interference
be zero. the little differential equations with deviating arguments of specified steady-state value (2) can be write as:
(3)
Wherein:
System transter matrix is:
（4）
Its inverse is:
（5）
Wherein:
Will
, A and
substitution formula (5) obtains general expression:
（6）
describe the dynamic perfromance that system carried out by acid adding tank.
When
time:
Acid adding tank transport function can be obtained:
（7）
Wherein:
be the sectional area of three acid adding tanks, three acid adding volumes are identical,
,
be the departure of the acid adding flow that technique allows, substitute into formula (7), then
（8）
Second step: the mathematical model obtained according to the first step
design advance compensator transfer function matrix
, make
becoming diagonally dominant matrix, is acid concentration multivariable controller schematic diagram see Fig. 4 and Fig. 5, Fig. 4, and Fig. 5 is Nai Shi Array Method design cycle schematic diagram; Step is as follows:
1) drafting is run
the software (on sale in this software market, to be prior art) in the rare high forest belt of lattice, inputting mathematical model in the interface that software ejects
, inputted rear click and run, interface has obtained the nyquist diagram with the rare high forest belt of lattice, makes
become diagonally dominant matrix;
2) utilize diagonal dominance software (on sale in this software market, to be prior art), calculate advance compensator transfer function matrix
:
（9）
Draw out
the rare high forest belt of lattice, the open cycle system after being compensated reaches diagonal dominance.
3rd step,
single loop Compensation Design.Due to
reach diagonal dominance, the design of univariate method for designing therefore can be adopted to compensate design to three single loops.According to manufacturing technique requirent, the overshoot of acid concentration is little, and transient response process is short, and closed loop steady-state error is zero.So get
for pi regulator.Gather examination by a few subparameter, obtain:
（10）
4th step, draws
with the nyquist diagram in the rare high forest belt of lattice.According to Nai Shi stability criterion, ensure that closed-loop system is stablized, acid concentration feedback gain
value:
;
;
.In order to make system have larger stability margin, acid concentration feedback gain
get:
。（11）
5th step, adjustment acid concentration feedback gain
.Make the step simulation curve of closed-loop system, adjustment acid concentration feedback gain
, complete multivariate Close-loop Control System Design.Closed-loop control system block diagram after completing as shown in Figure 6.
6th step, closed-loop control system emulates.The unit-step nsponse curve of system can be obtained, adjustment System parameter: comprise input parameter setting value, advance compensator transfer function matrix by existing simulation software
, dynamic compensator transfer function matrix
with acid concentration feedback gain
, make each main channel there is no over-control, meet steady-state error and the response speed requirement of system.
Main innovate point in cold-rolling pickling acid concentration control method of the present invention is finally summed up as the determination for parameter each in acid concentration multivariable controller models, and parameter comprises by control object acid adding tank transfer function matrix
, advance compensator transfer function matrix
, dynamic compensator transfer function matrix
with acid concentration feedback gain
; Multivariable controller arithmetical unit, the parameter of acid concentration multivariable controller determine after closed-loop control system block diagram see Fig. 6.
The actual acid concentration value of acid solution in acid tank on production line is obtained by the measurement of three acid concentration measurement mechanisms, through acid concentration analyzer rear feed to multivariable controller, acid concentration value given with technological requirement in multivariable controller compares, and its difference is as the input value of multivariable controller models; After multivariable controller calculation process, calculate control variable and export to topworks, topworks controls infusion pump on each acid adding tank and fluid-delivery valve respectively, controls circulation acid tank acid concentration.
These are only preferred embodiment of the present invention, be not intended to limit protection scope of the present invention, therefore, all any amendments done within the spirit and principles in the present invention, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (6)
1. a cold-rolling pickling acid concentration control method, it is characterized in that: on the sour circulation groove of pickling lines, configure three acid adding tanks, interconnect between three acid adding tanks, series connection acid concentration measurement mechanism on the acid solution reflux line of each acid adding tank and acid tank, the actual acid concentration value obtaining acid solution in acid tank on production line by the measurement of acid concentration measurement mechanism through acid concentration analyzer rear feed to multivariable controller, acid concentration value given with technological requirement in multivariable controller compares, and its difference is as the input value of multivariable controller models; Because the acid concentration between three acid adding tanks is interactive, namely it is inter-related for measuring the acid concentration value obtained, therefore the coupled relation between the acid concentration must finding out three measurement points, set up the mathematical model of production line acid circulation groove, and carry out the calculation of multivariable decoupling total, multivariable control system is converted into single variable control system; Concrete steps are:
The first step, sets up the multivariable model of controlled device descaling bath on pickling lines
The expression formula of controlled device acid adding tank transfer function matrix G (s) of production line acid tank is:
The inverse function G of acid adding tank transfer function matrix G (s)
-1s () expression formula is:
In formula:
A
1, a
2, a
3be the sectional area of three acid adding tanks, three acid adding volumes are identical, β
1, β
2, β
3it is the departure of the acid adding flow that technique allows;
Second step: design advance compensator transfer function matrix K according to the mathematical model G (s) that the first step obtains
ps (), makes K
ps () G (s) becomes diagonally dominant matrix, its step is as follows:
1) software in the rare high forest belt of existing drafting transport function G (s) lattice is run, transport function G (s) is inputted in the interface that software ejects, input rear click to run, interface has obtained the nyquist diagram with the rare high forest belt of lattice, makes K
ps () G (s) becomes diagonally dominant matrix;
2) utilize existing diagonal dominance software, calculate advance compensator transfer function matrix K
p(s); Draw out K
pthe rare high forest belt of lattice of (s) G (s), the open cycle system after being compensated reaches diagonal dominance;
3rd step, adds acid tank transport function G (s) single loop Compensation Design, due to K
ps () G (s) reaches diagonal dominance, univariate method for designing therefore can be adopted to compensate design to three single loops, get K
ci(i=1,2,3) are pi regulator, gather examination, obtain dynamic compensator transfer function matrix K by a few subparameter
c(s) value;
4th step, draws G (s) K
c(s) K
ps (), with the nyquist diagram in the rare high forest belt of lattice, according to Nai Shi stability criterion, ensures that closed-loop system is stablized, obtains acid concentration feedback gain value F (s).
2. cold-rolling pickling acid concentration control method according to claim 1, is characterized in that: in the described first step, and the sectional area value of three acid adding tanks is: a
1=a
2=a
3=1.8m
2, the departure value of the acid adding flow that technique allows is: β
1=0.6; β
2=0.5; β
3=0.36; Substitution formula (7), then acid adding tank transfer function matrix G (s) value:
Second step, calculates advance compensator transfer function matrix K
p(s):
3rd step, gather examination by a few subparameter, can obtain:
3. cold-rolling pickling acid concentration control method according to claim 1 and 2, is characterized in that:
4th step, adjustment acid concentration feedback gain F (s), makes the step simulation curve of closed-loop system, and adjustment acid concentration feedback gain F (s), completes multivariate Close-loop Control System Design.
4. cold-rolling pickling acid concentration control method according to claim 3, is characterized in that:
5th step, closed-loop control system emulates, and can be obtained the unit-step nsponse curve of system, adjustment System parameter: comprise input parameter setting value, advance compensator transfer function matrix K by existing simulation software
p(s), dynamic compensator transfer function matrix K
cs () and acid concentration feedback gain F (s), make each main channel not have over-control, meet steady-state error and the response speed requirement of system.
5. a cold-rolling pickling acid concentration control device, comprise acid concentration analyzer, sensor, instrument setting and display system, controller, topworks; It is characterized in that: described sensor comprises conductivity sensor and temperature sensor, conductivity sensor measures the electrical conductivity of solution of production line acid circulation groove endpiece, the solution temperature of temperature sensor measurement production line acid circulation groove endpiece; The signal of temperature sensor and conductivity sensor exports to acid concentration analyzer, calculates the concentration of solution in descaling bath in acid concentration analyzer, and this concentration is fed controller;
Described controller is multivariable controller, multivariable controller comprises dynamic compensation controller and Compensatory Control device, the acid concentration actual value that multivariable controller obtains according to the acid concentration signal sets value of input and sensor measurement carries out multivariable decoupling calculating, calculates control variable and exports to topworks;
Topworks controls infusion pump on each acid adding tank and fluid-delivery valve respectively, and each acid adding tank interconnects, and carries out transport acid hydraulic control system to circulation acid tank acid concentration.
6. cold-rolling pickling acid concentration control device according to claim 5, is characterized in that: described acid adding tank is three, lays respectively at the centre position that steel plate enters the porch of acid tank, exit and descaling bath.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110231135.5A CN102929303B (en) | 2011-08-12 | 2011-08-12 | Method and device for controlling concentration of acid for acid washing in production process of cold-rolled strip steel |
Applications Claiming Priority (1)
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| CA2890620C (en) * | 2012-11-30 | 2018-08-28 | Baoshan Iron & Steel Co., Ltd. | Acid concentration control method and device for cold rolling pickling production line |
| CN111519194B (en) * | 2020-03-27 | 2022-02-11 | 佛山津西金兰冷轧板有限公司 | Cold-rolled sheet manufacturing process |
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| CN1280633A (en) * | 1997-11-06 | 2001-01-17 | 住友金属工业株式会社 | Method of measuring acid concentration, and automatic control method and apparatus |
| CN1462321A (en) * | 2001-04-27 | 2003-12-17 | 住友金属工业株式会社 | Continuous pickling method and continuous pickling device |
| EP1373600A1 (en) * | 2001-03-30 | 2004-01-02 | Alcan International Limited | Method of controlling solution concentration in strip cleaning line |
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| JP5050410B2 (en) * | 2006-05-30 | 2012-10-17 | Ｊｆｅスチール株式会社 | Acid concentration control method / apparatus for pickling process, and steel plate manufacturing method using them |
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| EP1373600A1 (en) * | 2001-03-30 | 2004-01-02 | Alcan International Limited | Method of controlling solution concentration in strip cleaning line |
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