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Pilot scale black liquor concentration using pressure driven membrane separation, TAPPI Journal April 2023
ABSTRACT: Black liquor concentration using pressure driven membrane separation has long been proposed as a means of achieving energy savings and breaking production bottlenecks. To date, limitations in membrane performance and stability under black liquor process conditions have prevented those promises from being realized out-side of tightly controlled laboratory settings. In this work, we describe the first successful pilot scale field deployments of a membrane system for black liquor concentration. Using a purpose-built system and commercial sized, spiral wound graphene oxide membrane elements, we have logged nearly 6000 h of runtime across deployments to multiple mill sites. We demonstrate concentration of black liquor from 14% to >20% total solids, while generating permeate water comparable in quality to that of evaporator condensate and an 81% reduction in energy consumption relative to evaporation. At a commercial scale, these results translate to $2 M/year in net energy savings for a typical mill, as well as an opportunity to support production increases or mill expansions. These results represent a significant leap forward in the ability of membrane systems to deliver substantial value via black liquor concentration.
Journal articles
Magazine articles
Web lateral instability caused by nonuniform paper properties, TAPPI Journal January 2022
ABSTRACT: Lateral or cross-machine direction (CD) web movement in printing or converting can cause problems such as misregistration, wrinkles, breaks, and folder issues. The role of paper properties in this problem was studied by measuring lateral web positions on commercial printing presses and on a pilot-scale roll testing facility (RTF). The findings clearly showed that CD profiles of machine direction (MD) tension were a key factor in web stability. Uneven tension profiles cause the web to move towards the low-tension side. Although extremely nonuniform tension profiles are visible as bagginess, more often, tension profiles must be detected by precision devices such as the RTF. Once detected, the profiles may be analyzed to determine the cause of web offset and weaving problems.Causes of tension profiles can originate from nonuniform paper properties. For example, by means of case studies, we show that an uneven moisture profile entering the dryer section can lead to a nonuniform tension profile and lateral web movement. Time-varying changes in basis weight or stiffness may also lead to oscillations in the web’s lateral position. These problems were corrected by identifying the root cause and making appropriate changes. In addition, we developed a mathematical model of lateral stability that explains the underlying mechanisms and can be used to understand and correct causes of lateral web instability.
Journal articles
Magazine articles
Addressing production bottlenecks and brownstock washer optimization via a membrane concentration system, TAPPI Journal July 2021
ABSTRACT: Advancements in membrane systems indicate that they will soon be robust enough to concentrate weak black liquor. To date, the economic impact of membrane systems on brownstock washing in kraft mills has not been studied and is necessary to understand the viability of these emerging systems and their best utilization.This study investigated the savings that a membrane system can generate related to brownstock washing. We found that evaporation costs are the primary barrier for mills seeking to increase wash water usage. Without these additional evaporation costs, we showed that our hypothetical 1000 tons/day bleached and brown pulp mills can achieve annual savings of over $1.0 MM when operating at higher dilution factors and fixed pulp production rate. We then investigated the impact of increasing pulp production on mills limited by their equipment. In washer-limited mill examples, we calculated that membrane systems can reduce the annual operating cost for a 7% production increase by 91%. Similarly, in evaporator-limited mill examples, membrane systems can reduce the annual operating cost for a 7% production increase by 86%. These results indicated that membrane systems make a production increase significantly more feasible for these equipment-limited mills.
Towards Overcoming the Brightness Ceiling of Mechanical Pulps Prepared from Blue-Stained Lodgepole Pine Chips, 2008 Engineering, Pulping and Environmental Conference
Towards Overcoming the Brightness Ceiling of Mechanical Pulps Prepared from Blue-Stained Lodgepole Pine Chips, 2008 Engineering, Pulping and Environmental Conference
PARAMETERS INFLUENCING FLEXO PRINTING ON WHITE TOP LINER BOARD, 2008 PAPERCON Conference
PARAMETERS INFLUENCING FLEXO PRINTING ON WHITE TOP LINER BOARD, 2008 PAPERCON Conference
New Calendering and Coating Tools to Improve Coated Fine Paper Quality, 2008 PAPERCON Conference
New Calendering and Coating Tools to Improve Coated Fine Paper Quality, 2008 PAPERCON Conference
Developing Numeric Nutrient Criteria: Impacts on the Pulp and Paper Industry, 2008 Engineering, Pulping and Environmental Conference
Developing Numeric Nutrient Criteria: Impacts on the Pulp and Paper Industry, 2008 Engineering, Pulping and Environmental Conference
Mixed Brazilian Eucalyptus and Pinus Species - Bleaching Evaluation, 2008 Engineering, Pulping and Environmental Conference
Mixed Brazilian Eucalyptus and Pinus Species - Bleaching Evaluation, 2008 Engineering, Pulping and Environmental Conference
Polymer-Based Peroxide Stabilizer for Recycle Fiber Bleaching, 2008 Engineering, Pulping and Environmental Conference
Polymer-Based Peroxide Stabilizer for Recycle Fiber Bleaching, 2008 Engineering, Pulping and Environmental Conference
Characterization of Ink Adhesion Failure; Effect of Pre-dampening of Carbonate Containing Coatings , 2008 Advanced Coating Fundamentals Symposium
Characterization of Ink Adhesion Failure; Effect of Pre-dampening of Carbonate Containing Coatings , 2008 Advanced Coating Fundamentals Symposium