The objective of this project is to reduce electrical energy in the preparation of pulp fibers both for chemithermomechanical pulps (CTMP) by use of oxidative treatments, for refining of pulp fibers by improving refining homogeneity and by upgrading waste paper by optimizing fractionation and beating techniques.
Significant savings in energy demand were achieved at all of the stages investigated. Pre-treatment of wood chips achieved 5-10% energy savings, whilst savings of up to 30% were demonstrated in the pulp refining process. An added benefit was the improvements observed to the pulp brightness following pre-treatment. Further energy savings in the upgrading of waste paper also benefited from the improvements to the quality of the recovered pulp and therefore an increase in pulp value. These results show that not only can targeted efficiency actions reduce energy demand, they can also improve the value of the finished product.
Chemithermomechanical pulps (CTMP) With the use of oxidative treatments, especially in gaseous form, a more efficient chemical treatment than common sulphonation of the wood may be possible for improving swelling of the wood. This oxidation of the lignin holding fibres together may, as in sulphonation, facilitate fibre separation and, by that, lower the energy demand in the mechanical preparation of the fibres to fullfil paper making requirements.
The use of an oxidative treatment, especially in a gaseous form combined with a liquid chemical impregnation of the chips will be evaluated for effects on softening properties, reological characteristics and pulp properties after refining.
Refining of pulps fibers : The project involves improving refining homogeneity by control of fibre flocculation and dedicated filling designs in order to increase refining efficiency. This involves development of a model to describe the hydromechanical forces in a refiner, to characterize fibre properties and develop techniques by which fibre floc formation and dispertion is controlled in high shear systems. Upgrading waste paper : In view of the heterogeneity of waste paper and the typically high energy consumption of the fibre refining process, secondary fibre pulps should conveniently first be separated into at least two fractions. Only the fraction with the highest potential of improvement should be treated by refining.
A novel fractionating technique will be studied in order to separate fibres by their flexibility.
This aims at investigating whether this technique alone or in combination with traditional fractionation processes is capable of giving a more selective separation in terms of the fibrillation state of the fibres.
Finally, technical and economic evaluation will be made to assume the success of the three activities.
Funding SchemeCSC - Cost-sharing contracts
KT22 7RU Leatherhead