Abstract

Pressure screening, a process used in pulp and paper facilities, exposes workers to noise levels of 95 to 98 dB(A). The introduction of firmer pulp requiring a new type of screen is expected to result in a further increase of 6 dB(A). Scientific research has led to the development of the first-ever model to calculate the cylinder’s vibro-acoustic behaviour when subjected to relational forces. This model has made it easier to understand the physical phenomena governing mechanisms that trigger strong acoustic propagation in the case of pulp screen cylinders. In terms of technology, three source control solutions have been developed and field-tested: using a variable-thickness cylinder that is firmer around the perforations, which leads to a reduction of 8 dB(A); installing strategically placed rubber joints, which cuts noise levels by 10 dB(A); and installing a multi-layer external cylinder, which lowers the sound level by about 20 dB(A).