OnQ GradeManager
Reliable grade change
with minimal broke
Typical problems with grade change
Consistency and the level of paper quality are lower during a
grade change than under stable production conditions. Therefore, such paper is often not salable at all or only at a Bquality rating. Furthermore, quality parameters such as
moisture or ash content fluctuate far beyond the grade
change, meaning runnability is also reduced.
In addition, until the final paper quality is achieved the machine
operator has to adjust additional machine parameters, such
as the vacuums in the former, to reach the desired target
­quality. As a rule, this happens gradually over a longer period
of time.
Our solution
OnQ GradeManager coordinates the grade change exactly so
that the accumulating broke is minimized. Using historic data
on the target grade, optimal grade-dependent machine settings are determined and specified for the change. Furthermore, based on the current working point of the paper machine
and the new grade, OnQ GradeManager calculates precise
target values for the amount of high consistency stock, steam
pressure and filler addition using a physical model. In order to
start the new grade as quickly as possible with the highest
level of process stability, OnQ GradeManager also specifies
when and how the values are changed in the course of the
grade change.
Benefits
Initial situation
The grade change is dependent on the working point of the
machine before the change and on the new grade. The new
grade is started by simple ramping up/down of the nominal
values and correcting variables.
++ Quick grade change
++ Less broke
++ Optimized quality after grade change
++ Improved runnability due to stable moisture
++ Automatic calculation of machine settings
based on historic data
++ Easy operation
++ Comprehensive grade management
During the grade change and briefly thereafter, the moisture in
the finished paper deviates so severely that the paper produced during this time is unsalable due to its poor quality.
vpz no. 1036 | English | Design: kalteny | Content: wip | 2012-10-24 | Technical data and illustrations subject to change!
Practical example
Included in the delivery
Solution
OnQ GradeManager calculates the necessary target values for
thick stock, filler and steam pressure based on the current
working point of the machine and the new grade.
They are adjusted on the basis of a physical model so that
the basis weight and the ash content reach the required
nominal values as quickly as possible while the moisture
­
­remains stable.
++ OnQ GradeManager for optimization of the
grade change
++ Grade management
++ Automation system
++ OPC connection to an existing process control system
++ Engineering for hardware components
++ Start-up and optimization
++ Operator training
Practical example OnQ GradeManager Quick and precise control of all parameters
Basis weight
54
21,500
Moisture [%]
48
Amount of stock
20,500
6
19,500
Amount
of stock [l/min]
Dry weight
51
5
4
Moisture
150
Steam pressure
Model based
steam control
125
100
Contact
Asia: Kunshan, China
Europe: Heidenheim, Germany North America: Wilson (NC), USA South America: São Paulo, Brazil [email protected]
www.voith.com/paper
Tel:
Tel:
Tel:
Tel:
+86 512 5799
+49 7321 37
+1 252 265
+55 11 3944
3600
2487
4405
4966
Steam
pressure [kPa]
Weight [g/m2]
3 min
57