Dynamic simulation of brown stock washers and bleach plants

Dynamic process simulators of brown stock washers and multistage bleach plants were developed for process control. SIMNON, a dynamic simulation language, was employed as a platform for constructing the simulators. The washing process simulator was used to investigate dynamic behavior of a three-stage countercurrent washing plant and to evaluate process control strategies. Good understanding of interactions of the operating units and the dynamics of the washing system were achieved, and significantly improved washing by better control were shown. For dynamic modelling of the bleach plant, pulp flow patterns in the retention towers were modelled using tracer responses from different towers. A model consisting of a cascade of CSTR's and a PFR showed good correspondence with measurements. A linear relationship was derived to correlate delignification and brightening. Unit operation models for mixing, reactions and washing were formulated using mass balances on liquor, fibres, chromophores, chemicals, pH and dissolved solids. Bleaching kinetic models from the literature were evaluated and incorporated into the bleaching process simulator. Using the simulator and industrial conditions, a dynamic model of a CDEDED bleach plant was built and used to simulate responses of the CE kappa number and brightness to changes in the chemical charge, incoming kappa number and production rate. Dynamic characteristics of nonlinearity and long time delay were identified. This simulator could be applied to other bleaching sequences to study process dynamics and control strategies if the bleaching kinetics used in those sequences were known.

Name thesis:degree_name

Master of Applied Science - MASc

Level thesis:degree_level

master's

Discipline thesis:degree_discipline

Chemical and Biological Engineering

Grantor dc:publisher

University of British Columbia

Year dc:date

1993

Author dc:creator

• Wang, Roseanne Xiaohong

Statement dc:rights

• For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.

Language dc:language

eng

Handle dc:identifier

http://hdl.handle.net/2429/1530

OAI identifier oai:identifier

oai:circle.library.ubc.ca:2429/1530