Design & Manufacturing of Press Fabrics for Improved Dewatering Chad A. Hume & Dr. David W. Rosen George W. Woodruff School of Mechanical Engineering Renewable Bioproducts Institute Georgia Institute of Technology
RBI Dewatering Project Press Fabric Design Goal: Design features, such as holes and grooves, for inner layer of multi-layer fabric to: Facilitate dewatering Prevent/reduce rewetting Inner Layer Manufacturing Goal: Develop 2D and 3D ink-jet printing testbeds to fabricate designed inner layers using high viscosity fluids such as thermoplastic polyurethane (TPU) Georgia Institute of Technology 3
Agenda 2020 Drier Web Roadmap High Priority R&D Area Next-generation nip/press design for single-direction flow eliminate rewet High Priority Projects Develop adaptive felt materials or structures that have high permeability at high nip-loads and low permeability at low loads Identify or develop a membrane that will support unidirectional or preferential flow of water away from the fiber web Georgia Institute of Technology 4
Outline Press Fabric Introduction Press Fabric Flow Modeling Passive Active Inkjet Printing Prototyping High viscosity droplet generator Process modeling Conclusions Georgia Institute of Technology 5
Paper Machine Overview 1% 20% 50% 95% Increasing Dry Solids d. s. = m fiber m fiber + m water Georgia Institute of Technology 6
Recent trends and directions Non-woven bases Research observed better pressure uniformity, higher solids, less marking, and less rewet Inclusion of polymer membranes and layers New manufacturing techniques Additive manufacturing can build optimized geometry for polymer layer 7
Outline Press Fabric Designs Press Fabric Flow Modeling Passive Active Inkjet Printing Prototyping High viscosity droplet generator Process modeling Conclusions Georgia Institute of Technology 8
Press Fabric Design Focus on barrier layer FEA & CFD to simulate deformation and flow Various designs are studied including woven, nonwoven, conical, etc., as well as active geometries 9
Data Available Stream Lines Velocity/Pressure Pressure Drop This is related to flow resistance Georgia Institute of Technology 10
3D Results Can we design a hole that opens for forward flow and closes to prevent rewet 145% increase in resistance to back flow 11
Outline Press Fabric Designs Press Fabric Flow Modeling Passive Active Inkjet Printing Prototyping High viscosity droplet generator Process modeling Conclusions Georgia Institute of Technology 12
Inkjet Printing 3D Printing High Resolution Fast Scalable just add more nozzles Multiple materials $15-20B industry and growing Georgia Institute of Technology 13
Fabric Prototyping Prototype fabric designs were fabricated using the Stratasys Connex to explore both passive and active designs Georgia Institute of Technology 14
Georgia Tech Inkjet System Print high viscosity (>100cP) and complex fluids (non-newtonian, suspensions/colloids) Ultrasonic droplet generation technology New approach to printing. Excite at resonant frequency + acoustic focusing in nozzle causes ejection of droplet. Easily scaled for printing repeated patterns. 4 mm droplets Georgia Institute of Technology 15
Droplet Modeling Efficiently model how different machine parameters and material affect print quality Georgia Institute of Technology 16
Closure 1 st order approximation for how hole design affects flow. Promising new design to facilitate unidirectional flow. Investigating variants. Inkjet printing proposed as manufacturing process with high viscosity materials Developing process simulation to predict asfabricated geometries Georgia Institute of Technology 17
Design & Manufacturing of Press Fabrics for Improved Dewatering Chad A. Hume & Dr. David W. Rosen George W. Woodruff School of Mechanical Engineering Renewable Bioproducts Institute Georgia Institute of Technology
Pressing Overview: Basic Physics Water movement occurs only with pressure differential Pressure must be higher in the sheet than felt If hydraulic pressure exists, saturation must exist at least locally There must be a continuum of fluid To move fluid: Voids must exist in the felt, or Voids must exist beyond the felt, or Water must flow in MD or CD, or Sheet explodes (Crushing) Georgia Institute of Technology 19
Flow Modeling: 2D and 3D 2D Simulations 3D Simulations 20
3D Results Investigation of passive geometries 21
Summary 1 st order approximation for how hole design affects flow Various designs tested and one proposed which improves through flow and resists backflow Phase 2: How can we manufacture these membranes? Inkjet Printing! Georgia Institute of Technology 22