Retention control system for the wet-end section in a paper machine

We introduced a retention control system for the wet-end section of a paper machine using two intelligent pulp and filler (ash) low consistency sensors. When we tried to control the white water (WW) total consistency by the retention aid dosage using the "proportional plus integral (PI) feedback controller", we experienced a strong interaction with the existing paper ash content control of the QCS (quality control system). To alleviate this interaction problem, we utilized a "decoupling controller" together with the "PI feed-back controller".