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Agitated pulp chests provide attenuation of high‐frequency disturbances in pulp properties ahead of many pulping and papermaking unit operations. The effect of process and design variables on the extent of non‐ideal flows was examined in a laboratory‐scale pulp chest. Dynamic tests were made using the frequency‐modulated random binary input of a brine solution with the pulp feed to determine the magnitude of non‐ideal flows (channeling, recirculation and stagnant zones). Results showed that the degree of upset attenuation is a function of impeller momentum flux and fibre mass concentration and that existing design criteria underpredict the power needed to produce a fully mixed system.

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Trajectory Based Operations (TBO) is a key component of both the US Next

This paper introduces a mechanism for testing multivariable models employed by model-based controllers. Although external excitation is not necessary, the data collection includes a stage where the controller is switched to open-loop operation (manual mode). The main idea is to measure a certain "distance" between the closed-loop and the open-loop signals, and then trigger a flag if this "distance" is larger than a threshold level. Moreover, a provision is made for accommodating model uncertainty. Since no hard bounds are assumed with respect to the noise amplitude, the model invalidation mechanism works in a probabilistic framework.