Compact wet end systems for superior papermaking

28 ❘ ❘ ❘ 105:4 (2004) T 83 Pulp & Paper Canada aper machine designs have historically included large volume wet end processes as a necessary part of an efficient and productive papermaking facility. The conventional large volume processes, as shown in Figure 1, provide mixing and blending of thick stock components and control of entrained air from the forming section white waters. When designed properly, these systems initially perform to an acceptable level. However, as production rates, operating speeds or grade structures change, performance can deteriorate. Results can include poor stock blending and increased levels of entrained air in the headbox white waters, which can negatively impact machine efficiency, productivity and quality. Other problems associated with large volume wet end systems include: • Low operating efficiencies with frequent grade change • Poor attenuation of low frequency variations • Accelerated bacteria and scale growth • Process variability from compression of entrained air Compact wet end systems, as shown in Figure 2, have been developed to address these operating issues and to improve wet end performance over what is available with conventional systems.