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Refiner optimization and control Part IV: Long term follow up of control performance in TMP processes

Anders Karlström (Institutionen för signaler och system, Reglerteknik) ; K. Eriksson ; J. Hill
Nordic Pulp & Paper Research Journal (0283-2631). Vol. 30 (2015), 3, p. 426-435.
[Artikel, refereegranskad vetenskaplig]

This paper focuses on three important issues; Process understanding in relation to control of nonlinear processes; Natural decoupling by using internal state measurement devices; Long term follow up procedures of process control investments. As an example, a new control system for Thermo Mechanical Pulp (TMP) refiners is used, based on a cascaded control structure. The internal states, in this case the refining zone temperature profiles, are controlled in the inner loop whereas the outer loop handles pulp properties. The characteristics of the temperature profile dynamics makes it possible to introduce a decoupling scheme where the anti-diagonal elements in the transfer function matrix describing the process, can be eliminated naturally. The system can handle several pulp propertied simultaneously but in this study mean fiber length (MFL) is the target variable. The process is followed about 200 days in manual mode control and 200 days in automatic mode. It is shown that the standard deviations in the pulp property variables freeness (CSF) and MFL were decreased about 40 and 60%, respectively. Significant reductions in variability of shives and a motor load standard deviations was achieved. On top of this, an increased production was obtained and the control system runnability was raised from 50% to 98%, levels that are far from commercial MPC-control concepts in TMP refining control.

Nyckelord: Refining control, Filtering, Temperature, pulp and paper industry, Decoupling

Denna post skapades 2015-10-21. Senast ändrad 2016-09-14.
CPL Pubid: 224573


Institutioner (Chalmers)

Institutionen för signaler och system, Reglerteknik


Pappers-, massa- och fiberteknik

Chalmers infrastruktur