SCIMM Conference: 28th September, 2010:

Venue: The Centre, Birchwood Park, Warrington

Abstracts

Presenter company: Kadant

Presenter: Benno Duller

Paper Title: Dryer System Management

Significant improvements in dryer section operation and energy efficiency have been achieved through the close integration of supervisory control and steam system design. Supervisory control of all system setpoints is used to optimize system operation and provide ease of use for the operators. Steam pressures, flows, and differentials are managed under all machine operating conditions including sheet breaks, tail threading, grade changes, and start-ups.

The control system accomplishes this without the need for operator intervention. System designs can be simplified and a very wide operating pressure range is produced.

Supervisory control assures that the dryer operation is consistent for different machine operating conditions and machine crews. 

This improved consistency results in better dryer section runnability by producing the same dryness curve as the sheet progresses through the dryer section. 

The concept of an improved dryer control system is to utilize modern control capabilities to provide supervisory control over the steam control and dryer drainage system. There are many benefits that can be realizedwith this approach. Consistent dryer operation is produced over the entire machine operating range and for every machine operating crew. Drying conditions are controlled in a manner that produces consistent machine direction sheet moisture, constant draws, and improved runnability. Upsets such as sheet breaks, grade changes, and wash-ups are handled efficiently by the control system. This produces improved machine efficiency.

 

Presenter Company: ABB

 

 

Presenter: Andreas Zehnpfund

Paper 1:  Process Fingerprints

Process Optimization through Data Variation Analysis

Reducing sheet variations has been the goal of paper makers for a long time. Sheet
variations increase sheet breaks, reduce product quality, limit machine speed, extend
transition times, and stand in the way of converting and production. These variations
may have their source in bad valves, poor mixing, faulty transmitters, excessive
mechanical vibration, or improperly tuned controllers. All of these variations can be
"seen" with the basis weight, moisture, and caliper sensors. This paper will discuss
methods for using sensor data to categorize product variation based on steady state
and transient data analysis techniques. Once product variation has been properly
measured, then the source can easily be found and corrective action taken.

Paper 2: Multi Variable Control

A supercalender is critical machinery to develop the smoothness and gloss needed for high-quality printing paper. The supercalender stack could affect several sheet properties simultaneously including caliper, smoothness, top and bottom gloss. In order to ensure all quality specifications are met at the same time, a multivariable control technique is needed. This paper will illustrate the challenges of the supercalender process, the responses of supercalenders, the balance of quality specifications, and control techniques to achieve the desired sheet qualities. The results and benefits of applying a multivariable control technique to production machines will also be discussed.

 

Paper 1: Charge Control for Improved Tissue Production

Online charge control strategies are well accepted in coated fine paper and DIP-containing grades. BTG Mütek, together with European and Australian tissue producers has developed further control solutions for various grades in tissue production using new approaches and new instrumentation products. 

Tissue customers expect products with high quality in softness or wet strength. These properties can be achieved through chemical additives. Wet end chemistry is mainly driven by reactions within the huge surfaces of colloidal material and the absorption characteristics of the fibres. 

The cationic demand of a water phase and the surface charge of the fibre are checked in order to get a closer look on how these additives perform within the pulp suspension. Following these investigations, the next step is to control charge automatically.    

Paper 2: The Benefits of Refiner Control

In today's highly competitive marketplace, proper control of the refiner operation is critical to ensure high quality, uniform pulp. This paper briefly discusses accepted refiner control strategies, with particular emphasis on automatic freeness control. To illustrate actual mill situations, we summarise some examples using on-line drainage analyzers at different mill sites.

The stock process, the control strategy, and the results are discussed and associated benefits highlighted. 

·         quality and uniformity

·         productivity

·         energy costs

·         operation. 

Refining is an essential step in almost all papermaking operations and has a substantial impact on all downstream operations. In today's highly competitive marketplace, customers expect product uniformity and high quality - at a reduced cost. The benefits of proper refining are higher wet web and sheet strength, faster paper machine speed, faster drainage, and less drying energy.