Refining models for control purposes

• Many studies have been carried out with the goalof improving pulp quality control in TMP refining processeswithout a deeper understanding about the physical conditionsinside the refining zone. The refiner is thereby considered as a black box where the chips are defibrated to fibers. In this paper, a non-linear model for the estimation of thermodynamic and defibration/fibrillation work is presented. It is shown that the model requires temperature measurements to span the energy balances and obtain reliable pressure gradients inside the refiningzone. Based on process data from a single disc refiner, it is shown that the defibration/fibrillation work varies substantially along the radius of the refining segments, even though the total work, i.e. the motor load, is almost the same over the specific time sequences. This is a consequence of variations in the concentration of the fiber pad built up inside the refining zone. Moreover, it is shown that the commonly used control concept, where the traditional specific energy is used as a control variableshould be reconsidered. Besides a deeper analysis about theassumptions made in the refiner modeling procedure, obtainedresults regarding estimated fiber concentration along the radius, consistency and steam efficiency are discussed.

Ämnesord

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

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

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik -- Kemiska processer (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering -- Chemical Process Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik -- Reglerteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering -- Control Engineering (hsv//eng)

Nyckelord

Steam efficiency

Quality optimization

Consistency

Refining models

Control

Fibre concentration

Publikations- och innehållstyp

art (ämneskategori)

ref (ämneskategori)