Analysis of Periodic Phenomena in the Approach Flow Papermakers, 1997 Papermakers Conference Proceedings

In some approach flow systems, the combination of the mechanical problems of the rotating equipment, the incorrect layout of the equipment or the steady state pressure variation that can develop due to the occurrence of acoustic resonances can create a hydrodynamic condition that is characteristic to this part of the paper making process. Relevant frequency spectra acquired during various paper machines approach flow system tests, together with the explanation of the possible causes of the processes analyzed, are presented. The air entrainment in the water and stock lines, the incorrect operation of fan pumps and pressure screens, the inappropriate choice of headbox recirculation valve type and location and the parallel operation of rotating equipment of quasi similar rotational speeds are some of the potential sources of pulsation leading to undesirable flow patterns development. They must be viewed as incorrect operating conditions of the entire approach flow system, though not always problems of an individual mechanical component.