Optimized Deaeration Leads to Substantial Process and Quality Improvements in Paper Manufacturing, 2002 Technology Summit Proceedings

R. Rauch & T. Burke

High air or gas contents in pulp suspensions constitute a serious problem area in papermaking. They are responsible for higher pump energy demand, deposits, pinholes, foaming, and several other problems. An underestimated source of these problems is dissolved gases.

High contents of dissolved gases mainly originate from a decomposition of calcium carbonate where carbon dioxide is formed. In comparison to air and its components, carbon dioxide is far more easily dissolved in water. The immense pressure drop at the wire and at the foils leads to dissolved gases being released.

The measurement results achieved in various mills show that determining the levels of entrained and dissolved gases online enables the optimization of prevention measures as well as mechanical and chemical deaeration. The results also show that online control of deaerator chemicals based on the measurement values leads to substantial cost reductions, process improvements, and quality enhancements in paper manufacturing.