Measurement and Control of the Fourdrinier Drainage Process, 1991 Papermakers Conference Proceedings

The process of forming a web of paper on the wet end of a paper machine is critical to the characteristics of the final product. It has been only in recent years that equipment has become available to measure the drainage process and determine sheet consistencies and quantity of water removed by each element or group of elements along the fourdrinier. The sensor now available (used worldwide) employs a nuclear backscatter technique of mass measurement. The small size and portability of the equipment permits on line measurements without disruption of the normal operation of the machine. An extension of this technique now includes permanently mounting the gauge at strategic locations on the forming section of the machine. Positions include ahead of top formers and fourdriniers, before secondary headboxes and ahead of dandy rolls, although many other possibilities exist. The measurement of mass and/or calculated consistency is presented to the machine operator for either manual or closed loop control of consistency to the point of measurement.