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CONTROL OF FLOCCULATION OF CELLULOSE FIBRE AND MINERAL SOLIDS IN PAPERMAKING STOCKS.

Objective


The project, which has now been completed, resulted in the following developments.
Online flocculation sensors (transmission and reflection) have been developed and their application demonstrated on a pilot and full scale paper machine.
2 industrial prototype actuation devices (sonic shaker and ultrasonic transducer) have been investigated.
Models have been produced to correlate flocculation state to end product quality.
The actuation in conjunction with the sensors have formed part of a pilot scale control system.
The investigation in to the flocculation behaviour of paper making stocks has been undertaken and led to the deployment of a laboratory scale pulp viscometer. The work has been carried out in parallel to the sensor, actuator and modelling development providing a fundamental understanding of the phenomena operating in these areas.

The next development is an industrial version of the flocculation control system on a full scale paper making machine, and its integration into the existing mill control environment. This will lead to a control system that is able to optimize flocculation without disturbing other process parameters resulting in a significantly improved product quality.

The flocculation control system consists of a series of prototype optical reflection sensors, actuators and controllers. It is designed such that sensors positioned before the head box and on the wire section are used to monitor the flocculation process. The signals from the sensors allow the actuators to be regulated by a combination of feed forward and feed back control. Precise control of the flocculation process with rapid response time is achieved.
Flocculation of a papermaking stock is subject to continuous change during its passage through the papermaking system. It will be increased by raising the concentration of fibres and by the addition of chemicals usually supplied in the fan pump, the approach to the flowbox and in the flowbox itself; Once leaving the flowbox, flocs will form during formation and drainage. These flocs result in micro or macro variation in grammage. Their distribution is commonly referred to as formation. This project aims ultimately to control by controlling the flocculation characteristics of the stock.

Coordinator

PIRA International
Address
Randalls Road
KT22 7RU Leatherhead
United Kingdom

Participants (3)

Asociacion de Investigacion Tecnica de la Industria Papelera Espanola
Spain
Address
Avenida Padre Huidobro
28040 Madrid
Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek
Netherlands
Address

2595 CL Den Haag
UNIVERSIDAD COMPLUTENSE DE MADRID
Spain
Address
Ciudad Universitaria
28040 Madrid