Model based control and optimization of  continuous digester

• Continuous pulp digesters are large reactors with significant residence time. They play a critical role in shaping the pulp qualities achieved at the product-end.  For this reason, there is a big drive towards developing fundamental dynamic models to be used for better process understanding and control (especially in the development of model based controllers).In this paper we discuss the use of physical models for diagnostics and process optimization of a continuous digester.   Accurate diagnostics are not possible without the use of a pressure-flow net. The pressure-flow net also makes it possible to validate pressure and flow sensors in the circulation around the digester.  For control purposes however, the pressure-flow net is not so important. Two dynamic physical models were built for a continuous digester, one with a pressure-flow net and one without.  The model without the pressure-flow net has been tuned and tested with good results at Ngodwana mill.  It was not possible to get the model which included  the pressure-flow net running with as many digester section blocks as we wanted due to the he system becoming stiff. However, for a lower number of sections results were obtained. With an adjustment of the boundary conditions, higher number of sections should be possible to test as well.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Pappers-, massa- och fiberteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Paper, Pulp and Fiber Technology (hsv//eng)

Nyckelord

modelling

simulation

on-line

digester

Cellulose and paper engineering

Cellulosa- och pappersteknik

Energy- and Environmental Engineering

energi- och miljöteknik

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)