(421d) Energy Savings and Improved Mixing Performance with Modified Impeller Technology in Paper Pulp Mixing

Pulp and paper plants use stock chests with partial mixing and recirculation loops to reduce the magnitude of consistency fluctuations in pulp production. Minimizing these fluctuations provides smooth, uniform surfaces; improves final sheet properties; and, most importantly, offers substantial, measurable cost savings.

At present, most stock chests are only partially mixed with side-entry mixers. Maximum consistency is limited to less than 6.5% due to mixing limitations. New data shows that by mixing the entire volume of the stock chest, consistency fluctuations can be minimized. This was not feasible in the past due to lack of suitable mixing technology. However, with the proper application of modified impeller technology combined with zonal mixing, the entire chest can be uniformly mixed using only 50% of the power required by traditional side-entry mixers. This technology will allow for uniform mixing of paper pulp up to 14% consistency. Independent estimates of savings due to improved sheet profiles, increases in production efficiencies and energy savings vary, but can exceed $100,000.00 per month (USD).