OPEN PARA LA SEGURIDAD Y EL RENDIMIENTO
Mejore la seguridad y el rendimiento de su planta gracias a la gestión de alarmas, la supervisión de rendimiento y de activos, la visualización web de datos, la optimización, el control avanzado y la sintonía con la nueva herramienta TaiJi.
Repiensen sus métodos de trabajo y obtengan resultados inmediatos gracias a nuestros servicios, nuestra capacitación y nuestra pericia en asesoría. Manejen el cambio inteligentemente con nuestras soluciones probadas.
February 2005
In this issue
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About us |
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Classes and seminars |
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Trick for this month |
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To contact us |
See our previous issues :
http://www.topcontrol.com/techinfo/news.php
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See our 2005 calendar, Classes & Seminars :
See at : http://www.topcontrol.com/training/tcalendar.php
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Classes & seminars
Bangkok, February 16-18
SE-100-3 - Seminar on modern control methods
http://www.topcontrol.com/training/printable.php?id=6&type=cours
Mexico, March 15-17
SE-100-3 - Seminario en métodos de control modernos
http://www.topcontrol.com/training/printable.php?id=90&type=cours
Montreal, March 24-25
SE-120-2 - Seminar on performance assessment techniques using PlantTriage
http://www.topcontrol.com/training/printable.php?id=29&type=cours
New-York, March 27, Easter, March 29-31
SE-130-3 - Seminar on advanced tools in process control
http://www.topcontrol.com/training/printable.php?id=28&type=cours
Montreal, April 19-21
EX-501-3 - Detailed Loop Analysis with ExperTune
http://www.topcontrol.com/training/printable.php?id=13&type=cours
See us at Exfor 2005, Montréal February 8-10; our booth is 2010.
Michel Ruel (Top Control) and Jean-Guy Lagacé (Kruger Wayagamack) will present on Tuesday February 8, at 14 :00:
- Case story : Using Performance Monitoring and Optimization Tools for a Paper Machine Start-up
Seminar at ATCP, Concepcion,Chile, 4 de marzo 2005.
"Control de Procesos de Producción"
See at : http://www.atcp.cl/Curso.asp?Cu_Id=200533001
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Trick for this month : Level control?
To optimize a level loop, we must decide what is the goal? Do we want to maintain level at set point or do we want to prevent a spill or dry-out? If the objective is average control (not control at set point but ensure enough inventory), the tuning parameters are selected to reduce impact on the process. For example, if the controller manipulates outflow and inflow is wild, then our goal is to reduce outflow changes when inflow varies; the tank absorbs disturbances.
First we need to convince operation to accept errors on that loop; they should see on the screen not an arrow as set point mark but a band for acceptable values. To tune an averaging control loop, we must know the maximum allowable error.
Kp (proportional gain) is the opposite of the maximum error. For example, if SP=60%, minimum leve=10%, maximum level=90%, hence maximum error is 30%, Kp is 1÷30% = 1÷0.3=3.33. If Kp is higher, control will be too tight and the tank will not absorb disturbances. Integral action is not required but a small amount will return the level close to SP. Integral time should be long (minutes), a rule of thumb easy to remember is to use the tank residence time.
Formulas to tune level loops are well known.
For example Kp and TI are calculated based on arrest time (time to
reverse direction after a disturbance),. For Ideal ou Series
controllers:
TI= 2 x tarrest
Kp= (TI x Tresidence)÷( tarrest x tarrest)
Using the same example, and assuming 10 minutes for residence time, hence an arrest time of 30% x 10 minutes:
TI= 2 x tarrest = 6 minutes.
Kp= (TI x Tresidence)÷( tarrest x tarrest)=(6min x 10min) ÷(3min x 3min)=6.6
Stay tuned!
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Comments, suggestions and requests are welcomed. Please e-mail us at: info@topcontrol.com
You are welcomed to visit our web site :http://www.topcontrol.com
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49 Bel-Air Street, Lévis, QC
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1020 James Drive, Suite A
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