(562am) Innovative Water Recycle Strategies for Reducing Water and Energy Use in Pulp and Paper Industry

Innovative water recycle strategies for
reducing water and energy use in pulp and paper industry

The pulp and paper
industry is one of the largest consumers of water in the US industrial sector.
Application of water in the industry ranges from a chemical reactant, solvent
and use in physical application as a conveyor of final or intermediary
material. In recent years, there has been an increase in the industry for
adoption of waste minimization strategies covering various aspects and avenues
in mill operations. Process modelling and simulations is an effective approach
for identifying innovative strategies for improving the industry’s water
efficiency and productivity while strengthening its economic sustainability. In this study, WinGEMS (Windows General Energy and Mass balance
System) is used as the software tool for modelling bleaching and the paper
machine sections of an integrated bleached Kraft mill in the United States. The
project entails modelling the replacement of fresh water use for final bleaching
stage shower washer with white water from paper machine and assess the change
within the bleaching and paper machine operations. Current study simulates the
bleaching section of an Elemental Chlorine Free (ECF) sequence D₀EopD1EpD2
for a softwood Kraft pulp kappa number 30.  The chlorine dioxide
delignification reaction is a combination of fast reaction followed by a slow
reaction and the asymptotic value of kappa number linked to the floor lignin
(asymptote for both kappa number and brightness). The simulation included the
effect of carry-over from brownstock washers (BSW) and extraction stage washer.
Table below shows the data for the base simulation of ECF bleaching modelled in
WinGEMS.

The values of brightness,
Kappa number and COD are in close proximity with the actual industrial values.
Future work includes modelling the base case for paper machine and integrating
it with bleaching process capturing non-process elements (NPEs) flows in
adequate detail and examine its effects on the final paper brightness and paper
machine operations.

Key Words: WinGEMS, modelling, simulation, white
water, bleaching, paper machine, brightness