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Case study: Screening Optimization
Benefits obtained from installing
MultiSimplex control systems on pulp screens and screening lines.
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Results: MultiSimplex Screening
Controller
• 50%
reduction of Freeness variation
- 10-15 % reduction of shive content at unchanged
freeness levels.
• Possibillity to reduce reject
rate
System
specifications
·
Control
variable 1: Dilution water flow, Primary Screen (s)
·
Control
variable 2: Dilution water flow, Secondary Screen (s)
·
Control
variable 3: Reject rate Primary Screen (s)
·
Control
variable 3: Reject rate Secondary Screen (s)
·
Response
variable 1: Freeness (Target)
·
Response
variable 2: Shive content (Minimization)
·
Response
variable 3: Long fiber content (Maximization)
·
Response
variable 3: Total reject rate (Minimization)
Control variable set points are
optimized using the patented MultiSimplex algorithm.
Response variables are combined
and priorotized using the fuzzy logic feature in the MultiSimplex algorithm.
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Screening optimization –
objectives
When optimizing a screening
system, you want to achieve certain pulp/fiber properties at lowest possible
reject ratio while maintaining or increasing the availability of the screening
system.
MultiSimplex Screening Controller is a supervisory control and
optimization system that automates the control and optimization of
screening systems.
MultiSimplex effectuates the optimization by controlling
the screens based on response variables such as pulp quality and reject rate
(energy cost).
Users can prioritize different optimization
criteria. MultiSimplex offers the possibillity to change/modify
the optimization goals for different products,production runs, etc.
MultiSimplex will adaptively raise
the "bar" for the optimization, when conditions are good.
Mill
specific objectives
The objectives with the installation of
the MultiSimplex
Screening Controller New Company TMP mill were: Lower variations in pulp
quality by minimizing the shive content at a target freeness level.