Centrifugal Compression Value, 1997 Papermakers Conference Proceedings

A simple pressing test, independent of many complicating variables, has been developed as a research tool for intrafber dewatering studies. In the centrifugal compression value (CCV) test a pulp pad is placed between a press felt and brass weight and then centrifuged under controlled conditions. The centrifugal force drives the weight against the pad and continuously removes the expressed water from the felt. The CCV is the moisture ratio of the pad after centrifuging. In the CCV test a number of variables such as pressure, grammage and time can be easily changed, and at the maximum pressure, 6.1 MPa, a solids content over 60% is obtainable. In this study the most important variables were analyzed and the CCV test conditions were optimized. The CCV was found to be independent of felt design and felt and pad initial moisture content. Rewetting was negligible. At any given combination of centrifugal speed and mass, other factors being constant, the CCV depends only on the total pressure on the pad. At 15 minutes equilibrium is reached, after which the CCV is independent of time. After optimizing the test conditions, the CCV test was found to be precise, flexible and fast.