Date of Award


Degree Name

Bachelor of Science


Paper Science and Engineering

First Advisor

Dr. Raja Aravamuthan


In order to comply with new environmental regulations, the Menasha Corporation's Paperboard Division installed a 150 ton capacity blow tank and non-condensable gas collection system at the Otsego, MI mill. Concerns over the potential changes in pulp quality resulting from the hot storage time created a need for this study.

The objectives of the study were to determine the effects of hot storage under alkaline conditions on the refinability, fiber characteristics, and brightness of a semichemical mixed hardwood pulp. An experiment was designed to duplicate in the laboratory the internal conditions of the blow tank. Pulp was then stored at varying time periods from 2 to 8 hours and refined in a PFI Mill Laboratory refiner at three freeness levels (630, 400, 200 mL CSF). The pulp brightness was tested and compared against a control. Finally, the samples were tested for fiber characteristics by a Pulmac Z-span 3000 and given a pulp strength index value.

The results proved to be beneficial at the industrial level. The refinability of the pulp samples after hot storage was increased by 2.5% after two hours and 7.1% after eight hours. The potential annual energy saving in the beater room is $106,500. The pulp strength index after hot storage increased. There is no correlation between storage time and change in PSI although the average strength increase across all storage times and refining levels was 8.3%. Pulp brightness was unaffected at the 2 and 4 hour storage times however, after 6 and 8 hours the pulp darkened by 10.3 % to 18% as a result of alkali darkening.