Vaakapulpperin virtaussimulointi

Pulpers are energy intensive equipment that have been used in paper industry for a long time. The energy efficiency and pulping performance of pulpers has improved over the years, but only a few articles have been published on the subject. The objective of this thesis was to perform a series of CFD simulations for a horizontal pulper and evaluate the factors affecting performance of the pulper. Rheological properties of paper pulp were modeled with Herschel-Bulkley material model. Also turbulence was modeled in all simulations. Both stationary and transient simulations were conducted. Six quantities were defined for pulper performance analysis. These quantities were used to evaluate different pulper configurations. Also analytical and CFD based sensitivity analysis of the material model was conducted. Pulper simulation results to this extent have not been published before. Also the quantities defined in this work are published for the first time in a pulper related study. The defined quantities need to be further reviewed. The strengths and weaknesses of different rotors and simulation methods were identified. High pump blades increased rotor efficiency by 3 % when compared to the base case. Also pulping performance was improved. Using completely different rotor geometry increased rotor efficiency over 14 % compared to the base case