A more efficient rotating airfoil that keeps a screen separating pulp from contaminants at a recycled paper mill from becoming plugged up by using negative pressure pulses to backflush the narrow slots in the screen.
In 2006, Advanced Fiber Technologies developed an advanced low energy pulp screen rotor. Paper mills use pressure screens to separate contaminants from pulp produced from recycled product. A motor is used to spin the rotor at a high velocity. The pulp is forced through narrow slots or apertures that serve as a barrier to debris, stickies, contaminates, and uncooked or undeveloped bundles of wood fibers (shives). This makes contaminate-free pulp available for further processing. The rotor airfoil produces a negative pressure pulse that keeps slots from plugging by backflushing the apertures.
Several new rotor designs were developed with aerodynamic designs resulting in less drag. Power requirements are also reduced by operating the rotor at the lowest possible speed while keeping throughput or pulp feed rate constant and without screen slots plugging. A new high-capacity low-energy rotor was found to produce 52% energy savings when compared to conventional rotors. Power requirements for one rotor were reduced by over 60 kW while producing the same tonnage with equivalent shive removal efficiency.
BC Hydro estimates that the 300 pulp screen rotors in the province could provide an aggregate energy savings of about 153 million kWh per year if all were upgraded with advanced pulp screen rotors.
The cost of the low-energy rotor is comparable to that of rotors currently in use. Maintenance costs should be reduced as the optimized rotor runs at a slower speed. Reduced rotor and screen wear should extend the useful life of the rotor.
Status:
Baseline Description: Conventional Pulp Screen Rotor Baseline Energy Use: 935200 kWh per year per unit
ATF's new high-capacity low-energy Gladiator rotor was tested and found to produce 52% energy savings when compared to conventional rotors. Test trials established the lowest possible speed that the rotor could be operated at while keeping throughput or pulp feed rate constant and without screen aperature plugging. The 52% energy savings reduced power requirements by 60.8 kW while producing the same pulp tonnage with an equivalent contaminate removal efficiency. The baseline annual energy use of 935,200 kWh assumes 8000 hours/year of operation.
"Typical" Savings: 52% Energy Savings Reliability: 3 - Limited Assessment
Energy Use of an Emerging Technology is based upon the following algorithm. Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))
Simple payback, new construction (years): N/A
Simple payback, retrofit (years): N/A
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.
Brian Lin, 01/01/2013. No Pulp Fiction University of British Columbia
UBC, 03/13/2010. Synergy Awards for Innovation University of British Columbia
Mei Feng, 05/05/2005. Numerical Simulation and Experimental Measurement of Pressure Pulses Produced by a Pulp Screen Foil Rotor Journal of Fluids Engineering