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Case study: Paper mill power plant optimization—balancing steam venting with mill demand, TAPPI Journal June 2020
ABSTRACT: Most Power departments are tasked with generating steam to support mill wide operations, generate electricity, and reduce operating costs. To accomplish these tasks, power boilers generate high pressure steam that is reduced to intermediate and low pressures for process utilization in the mill by means of steam turbine generator extraction or pressure reducing valves. The most economical method to reduce steam pressure is the use of steam turbine generators, as electricity is generated from the steam when it is reduced in pressure. Electricity that is produced by these generators provides a substantial financial benefit and helps offset overall operational costs. To achieve tangible financial gains, the mill must evaluate the overall cost of steam production and the price of electricity.The current work provides a case study of power plant optimization that evaluated electricity production and steam production costs balanced with mill steam demand. Process and cost optimization led to a significant reduc-tion in low pressure steam venting, resulting in reduced fuel consumption and reduced operating cost.
Journal articles
Magazine articles
Over the Wire, Paper360º March/April 2020
Over the Wire, Paper360º March/April 2020
Journal articles
Magazine articles
The European Industry: Plenty of Challenges and Opportunities, Paper360º March/April 2020
The European Industry: Plenty of Challenges and Opportunities, Paper360º March/April 2020
Journal articles
Magazine articles
Paptic: Paper Products to Help Save the World, Paper360º March/April 2020
Paptic: Paper Products to Help Save the World, Paper360º March/April 2020
Journal articles
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Quick Evaluation of Fillers and Fines in Paper and Board, Paper360º March/April 2020
Quick Evaluation of Fillers and Fines in Paper and Board, Paper360º March/April 2020
Journal articles
Magazine articles
Preventive Maintenance Cards, Anyone?, Paper360º March/April 2020
Preventive Maintenance Cards, Anyone?, Paper360º March/April 2020
Journal articles
Magazine articles
2020 TAPPI/PIMA Awards:, Paper360º May/June 2020
2020 TAPPI/PIMA Awards:, Paper360º May/June 2020
Journal articles
Magazine articles
Long-Term or Short-Term Results?, Paper360º May/June 2020
Long-Term or Short-Term Results?, Paper360º May/June 2020
Journal articles
Magazine articles
Multifunctional barrier coating systems created by multilayer curtain coating, TAPPI Journal November 2020
ABSTRACT: Functional coatings are applied to paper and paperboard substrates to provide resistance, or a barrier, against media such as oil and grease (OGR), water, water vapor as measured by moisture vapor transmission rate (MVTR), and oxygen, for applications such as food packaging, food service, and other non-food packaging. Typical functional barrier coatings can be created by applying a solid coating or extruded film, a solvent based-coating, or a water-based coating to the paper substrate using various means of coating applicators.This paper focuses on water-based barrier coatings (WBBC) for OGR, water, MVTR, and oxygen barriers. The main goal was to create coated systems that can achieve more than one barrier property using multilayer curtain coating (MLCC). Curtain coating has emerged as the premier low-impact application me thod for coated paper and paperboard. This paper provides examples using MLCC to create coating structures that provide multiple barrier properties in a single coating step. Barrier polymer systems studied include styrene butadiene, styrene acrylate, vinyl acrylic, and natural materials, as well as proprietary additives where required to give desired performance. The paper also shows how the specific coating layers can be optimized to produce the desired property profile, without concern for blocking, as the addition of a non-blocking top layer can be applied in the MLCC structure as well. Experiments on base sheet types also shows the importance of applying the multilayer structure on a pre-coated surface in order to improve coating thickness consistency and potentially allow for the reduction of more expensive layer components.
Journal articles
Magazine articles
Numerical analysis of slot die coating of nanocellulosic materials, TAPPI Journal November 2020
ABSTRACT: Nanocellulosic coatings as a food packaging material are of commercial interest due to their nontoxic nature, renewability, and excellent barrier properties. Complex shear-thinning rheology poses challenges in designing and sizing equipment to pump, mix, and process the suspension and actual coating process. This study aims to determine the effectiveness of computational fluid dynamics (CFD) in predicting nanocellulosic suspension flow in light of existing rheological data. We employ and compare three distinct rheological models to characterize the rheology and flow of nanocellulose suspensions through a slot die coater, where the model parame-ters are established from existing slot rheometry measurements. A volume-of-fluid (VoF) based finite volume meth-od is employed to simulate the flow in a slot die operated in an unconventional metering mode. Results with the Casson model predict the presence of unyielded regions in the flow, which was not captured using the power law model. These stagnation regions will incur coatability issues stemming from flow intermittencies and lead to poten-tial defects in the coating layer, including fracture. The results suggest that a rheological model that includes yield stress should be considered while modeling such flows. A need for better rheological data to model nanocellulosic flows, especially at high consistencies and shear rates, is also highlighted.