Pulp & Paper

Paper and related products such as cardboard are manufactured from wood pulp in highly automated and large paper mills. The pulp is conditioned and speed onto high speed rolls where it is heated and processed into rolls of paper.

There are two sources of wood pulp:

• Virgin pulp which is produced from newly chopped trees. The resulting paper mills are situation close to the source of trees and a low cost source of electricity such as hydro. Hence the many large plants in Canada and Finland.

• Recycled paper from the paper that consumers and industry recycle. It is estimated that paper fibres may be recycled 7 times before they become too short to make paper. These plants are increasingly being built adjacent to centres of population where the recycled paper is collected, hence the many plants in the UK, Germany etc.

The challenge the industry faces is the cost of energy as, in addition to pulp, this is the major cost. Hence as oil and energy prices rise, so does paper prices. The measurement challenges are measuring the slurries of pulp.

As pulp is essentially a solid / liquid matrix, process tomography can add value to many unit processes in the pulp and paper sector, such as:

• Mixing injection of gas (such as chlorine or ozone for bleaching) into pulp slurries
• Separation, including filtration and drying
• Flow of slurries

Publications:

 W.Yenjaichon, G. Pageau, M.Bhole , C.P.J Bennington and J.R Grace (2011) Assessment of mixing quality for an industrial pulp mixer using electrical resistance tomography, The Canadian Journal of Chemical Engineering, Vol. 9999, pp1-9

Hui, L.K., Bennington, C.P.J. and Dumont, G.A. (2009) Cavern formation in pulp suspensions using sideentering
axial-flow impellers, Chemical Engineering Science, Vol. 64, pp 509-519

Q.F. Lee and C.P.J. Bennington (2008) Liquor Flow in model kraft batch digester, Chemical Engineering Journal, In Press

Ruzinsky and Bennington (2007) Aspects of Liquor Flow in a Model Digester Measured using Electrical Resistance Tomography, Chemical Engineering Journal, Vol. 130, Issues 2-3, 67-74

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