Doctoral Degrees (Forest and Wood Science)

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Process control of chemicals in fibre furnishes
(Stellenbosch : Stellenbosch University, 1994-12) Durgueil, Eric Jacques; Gerischer, G. F. R.; Stellenbosch University. Faculty of AgriSciences. Dept. of Forest & Wood Science.
ENGLISH SUMMARY: In a competitive and environmentally concerned business atmosphere, the role of wet end chemistry has become extremely important to a paper mill's profitability and long term viability. In the past decade, understanding of the papermaking chemistry has improved and sensors for measurement of the various variables on-line have been developed. Some of these variables are reviewed as well as the instruments which have been evaluated or developed for on-line measurement during this investigation. Process control loops to maintain control over the wet end chemistry during stock preparation are presented as well as an overall strategy to combine all the control variables. The primary thrust behind the control of the chemicals added is to minimise process variability and improve product uniformity as illustrated in this investigation. A reduction in chemical cost and paper losses coupled with improved customer satisfaction are some of the benefits obtained. More work is still required to fully master the multiple interactions and changing states of wet end chemistry and this will be attained with the improvement of existing or development of new on-line sensors.