Retention Control System of Paper Machine for Many Grades Production

A retention control system trial was performed for the wet part of a papermaking machine. By introducing two intelligent pulp and ash (filler) low consistency sensors (Kajaani : RM-200 M) to the stock supply line of head box and the white water (WW) filtrate line of wire part, we can monitor its wet end process conditions continuously. The retention control system using these sensors stabilizes the wet part process by controlling WW consistency, that is by an appropriate action of the retention aid dosage using a gap added PI (Proportional plus Integral) controller. As many grades production is running and grade changes are run frequently in this paper machine, it is difficult to determine the target set value (SV) of WW consistency. So we developed a new algorithm to judge the process stability by itself and to determine the SV target value of WW consistency automatically.