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The Future of Barrier Coatings, 2011 PaperCon Conference

The Future of Barrier Coatings, 2011 PaperCon Conference

GENERAL ANALYSIS OF WATER RECYCLE AT PULP AND PAPER MILLS, 2011 PEERS Conference

GENERAL ANALYSIS OF WATER RECYCLE AT PULP AND PAPER MILLS, 2011 PEERS Conference

New Optical Sensors - Real-Time Measurement of Ash and Total Contistency Throughout the Papermaking Process, 2011 PEERS Conference

New Optical Sensors - Real-Time Measurement of Ash and Total Contistency Throughout the Papermaking Process, 2011 PEERS Conference

Pulp and Paper Education at the University of Washington, 2011 PEERS Conference

Pulp and Paper Education at the University of Washington, 2011 PEERS Conference

Treatment of Lap Pulp Colloidal Stickies to Improve Paper Machine Runnability, 2011 PEERS Conference

Treatment of Lap Pulp Colloidal Stickies to Improve Paper Machine Runnability, 2011 PEERS Conference

RECENT ADVANCES IN PROCESS WATER OPTICAL ANALYSIS, 2011 PEERS Conference

RECENT ADVANCES IN PROCESS WATER OPTICAL ANALYSIS, 2011 PEERS Conference

Risk Management for the Paper Industry, 2011 PEERS Conference

Risk Management for the Paper Industry, 2011 PEERS Conference

Nonlinear modeling of batch digester discharge dynamics with rheology-driven hydraulic transport and drainability coupling, TAPPI Journal September 2026

ABSTRACT: Batch digester blowdown constitutes a strongly nonlinear transient transport process governed by the coupled evolution of pulp consistency, slurry density, hydraulic resistance, liquid inventory, and discharge line dynamics. A control-oriented nonlinear formulation is developed by coupling dry fiber and free liquor mass balances with phase volume reconstruction, consistency-dependent hydraulic resistance, channeling and drainability effects, and a power law head flow relationship derived within a lumped hydraulic inertance framework. A fixed-gain PI controller obtained from local linearization is employed as the conventional benchmark, whereas an integral sliding mode controller (SMC) explicitly compensates the nonlinear time-varying hydraulic structure and bounded disturbances. Both strategies are evaluated under identical actuator constraints and sequential perturbations involving opposing head, hydraulic resistance, channeling, drainability, and dilution. Numerical results demonstrate lower rootmean- square error, integral absolute error, and peak flow-tracking error for the SMC, with rapid recovery toward the prescribed sliding boundary layer and improved robustness to variations in the nonlinear flow exponent n. Cumulative electrical energy and batch-specific specific energy consumption remain comparatively similar, indicating that the principal SMC benefit is enhanced hydraulic regulation rather than substantial batch energy reduction. Specific energy consumption is an established metric for energetic assessment of slurry transport. Model-based hydraulic demand, electrical power, and sliding manifold surfaces further characterize the nonlinear operating domain. The resulting framework provides a computational proof-of-concept for modeling and control of transient batch digester discharge systems.

Pressure drop characteristics of steam condensation flow in triangular channels for multi-channel cylinder dryers, TAPPI Journal September 2026

ABSTRACT: This study investigates the condensation pressure drop characteristics of steam in the channels of multi-channel drying cylinders, which remain insufficiently understood. An experimental system was established using a horizontal mini-channel with a triangular cross-section and a hydraulic diameter of 4.09 mm. Flow visualization combined with a high-precision data acquisition system was employed to systematically examine the effects of steam mass flux (10•60 kg/(m²·s)), inlet temperature (110°C•140°C), and cooling water flow rate (100•500 kg/h) on the frictional pressure drop during condensation. The results indicate that the two-phase frictional pressure drop increases with rising steam mass flux but decreases with increasing saturation temperature, while the effect of cooling water flow rate becomes more pronounced under lower temperature conditions. In addition, several existing two-phase flow pressure drop correlations were evaluated against the experimental data. Based on a comparative assessment of eight existing correlations, a new predictive model was developed through regression analysis, achieving a mean absolute percentage error (MAPE) of 19.56%. These findings elucidate the pressure drop mechanism of steam condensation in triangular channels and establish a high-precision predictive model, providing theoretical guidance and a critical tool for the engineering design and energy consumption optimization of multi-channel drying cylinders.

Redefining Sustainability Leadership in Sanitary Paper, TAPPICon26