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Summary

Energy-Efficient Repulper Rotor

Paper Mill Repulping Rotor: Energy-efficient vs. Conventional

A tank with an efficient rotor in the bottom used to repulp bales of pulp and mix the pulp fibers with water prior to making paper.

Synopsis:

Non-integrated paper mills must purchase pulp in the form of dried one-ton bales. These bales go into the repulper, which is a tank with a mixer in the bottom. A horizontal drive motor is connected by shaft to a right-angle gearbox with the output shaft driving the repulper rotor. Bales are added to water in the repulper tank and the rotor blades draw the dried pulp below the water surface, defiber the pulp bales, and mix the fibers with water before the pulp is used to make paper.   


Energy-efficient repulper rotors are available and can reduce annual repulper energy use. The most efficient rotor design may depend on pulp characteristics such as fiber length (freeness) and percentage of hardwood versus softwood. It is crucial that the rotor does not degrade product (paper) quality. 


The Wisconsin Focus on Energy conducted tests at Wausau Paper to determine the energy savings due to using an efficient Voith HM instead of the baseline HOG rotor. They investigated energy savings, defibering time, freeness and final product attributes. The efficient rotor defibered the pulp furnish to the same degree as the conventional rotor with no effect on product quality. Metering established a 23% reduction in energy use. Most rotors run continuously, but while operating only 60% of the time, the 500-horsepower motor-driven rotor at the Wausau Paper plant produced savings of 560,000 kWh/year. Because repulper rotors are rebuilt or replaced periodically, facility staff have the opportunity to upgrade with new efficient rotors. 

Energy Savings: 23%
Energy Savings Rating: Limited Assessment  What's this?
LevelStatusDescription
1Concept not validatedClaims of energy savings may not be credible due to lack of documentation or validation by unbiased experts.
2Concept validated:An unbiased expert has validated efficiency concepts through technical review and calculations based on engineering principles.
3Limited assessmentAn unbiased expert has measured technology characteristics and factors of energy use through one or more tests in typical applications with a clear baseline.
4Extensive assessmentAdditional testing in relevant applications and environments has increased knowledge of performance across a broad range of products, applications, and system conditions.
5Comprehensive analysisResults of lab and field tests have been used to develop methods for reliable prediction of performance across the range of intended applications.
6Approved measureProtocols for technology application are established and approved.

Status:

Details

Energy-Efficient Repulper Rotor

Paper Mill Repulping Rotor: Energy-efficient vs. Conventional

A tank with an efficient rotor in the bottom used to repulp bales of pulp and mix the pulp fibers with water prior to making paper.
Item ID: 454
Sector: Industrial
Energy System: Process Loads & Appliances--Industrial Processes

Synopsis:

Non-integrated paper mills must purchase pulp in the form of dried one-ton bales. These bales go into the repulper, which is a tank with a mixer in the bottom. A horizontal drive motor is connected by shaft to a right-angle gearbox with the output shaft driving the repulper rotor. Bales are added to water in the repulper tank and the rotor blades draw the dried pulp below the water surface, defiber the pulp bales, and mix the fibers with water before the pulp is used to make paper.   


Energy-efficient repulper rotors are available and can reduce annual repulper energy use. The most efficient rotor design may depend on pulp characteristics such as fiber length (freeness) and percentage of hardwood versus softwood. It is crucial that the rotor does not degrade product (paper) quality. 


The Wisconsin Focus on Energy conducted tests at Wausau Paper to determine the energy savings due to using an efficient Voith HM instead of the baseline HOG rotor. They investigated energy savings, defibering time, freeness and final product attributes. The efficient rotor defibered the pulp furnish to the same degree as the conventional rotor with no effect on product quality. Metering established a 23% reduction in energy use. Most rotors run continuously, but while operating only 60% of the time, the 500-horsepower motor-driven rotor at the Wausau Paper plant produced savings of 560,000 kWh/year. Because repulper rotors are rebuilt or replaced periodically, facility staff have the opportunity to upgrade with new efficient rotors. 

Baseline Example:

Baseline Description: HOG Repulper Rotor
Baseline Energy Use: 2434780 kWh per year per unit

Comments:

Wisconsin Focus on Energy conducted tests at Wausau Paper to determine the energy savings due to using an energy-efficient Voith HM repulper rotor instead of using the baseline HOG rotor. Metering established a 23% reduction in energy use after the new repulping rotor was installed. The 500 hp motor-driven rotor at the Wausau Paper plant operated an estimated 74% of the time (many operate continuously). Baseline energy use was 2,434,780 kWh/year with energy savings exceeding 560,000 kWh/year.

Manufacturer's Energy Savings Claims: Currently no data available.
Best Estimate of Energy Savings:

"Typical" Savings: 23%
Energy Savings Reliability: 3 - Limited Assessment

Comments:

Energy Use of Emerging Technology:
1,874,780.6 kWh per unit per year What's this?

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.))

Technical Potential:
Units: unit
Currently no data available.
First Cost: Currently no data available.

Cost Effectiveness:

Simple payback, new construction (years): N/A

Simple payback, retrofit (years): N/A

What's this?

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.

Reference and Citations:

Jerry Aue, 06/15/2009. Voith Hight Efficiency HM Rotor Energy Data: A Repulper Rotor DEsign Case Study
Proceedings of the 27th Industrial Energy Technology Conference

Klaas Kramer, 01/01/2009. Energy efficiency Opportunities in the U.S. Pulp and Paper Industry
Lawrence Berkeley National Laboratory

Bill Fineran, 06/01/2006. Energy-Efficient Repulper Rotor Blade: Case Study at Wausau Paper – Rhinelander, WI
2006 Forum on Energy

Wisconsin Focus on Energy, 07/08/2010. Energy-Efficient Repulper Rotor – Best Practices
Wisconsin Focus on Energy

Rank & Scores

Energy-Efficient Repulper Rotor

There is no TAG available for this technology.
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