---

About MagnaDrive Drives Couplings News Links Home

Breakthrough Technology For Speed Control Daishowa America Port Angeles, WA Field Testing the MagnaDrive Adjustable Speed Drive on Northwest Industrial Applications Report on Pulp and Paper Test Site The Daishowa America Port Angeles Mill in Port Angeles, Washington, is a unit of Daishowa Paper Mfg. Co. Ltd. of Japan. The plant manufactures about 160,000 tons of paper annually using wood and recycled pulp. The paper is sold primarily to publishers of telephone directories throughout the United States. Application Overview Two 100 HP 1175 RPM motors operated in parallel running vertical shaft pumps. These pumps move wastewater from the main pump station to a clarifier. A third pump is used as a spare or during extreme process upsets when the two main pumps cannot keep up with the incoming flow rate. Prior to the MagnaDrive Adjustable Speed Drive (ASD) installations, the two motors ran continuously to meet a maximum flow rate of 7,000 gallons per minute (GPM). However, typical plant operation results in 7 million gallons per day (MGD) flow to the clarifier, or an average of 4800 GPM. On average, 2,200 GPM were diverted through a bypass valve. The system was controlled with a level-control valve downstream from the discharge of the pumps and a bypass valve working in tandem to maintain a level in the sump. As the level rose in the sump, the level-control valve was opened and the bypass valve was closed. As the level fell, the level-control valve closed and the bypass valve opened. Controlling sump level with these valves wasted energy. Vibration created maintenance problems and shortened equipment life. Variable Frequency Drive technology was ruled out for these applications due to limited space and the high infrastructure costs. Test Site Daishowa America Port Angeles, Washington Field test site for MagnaDrive Adjustable Speed Drive (ASD) pulp and paper wastewater application. Problem Starting and stopping large pumps created flow surges and water hammer that damaged process piping. Long duration of locked rotor currents on start-up could cause motor overheating. Bypass and level-control valves used to control sump level wasted energy. Cavitation and vibration caused process-piping fatigue and shortened equipment life. Solution MagnaDrive ASDs were installed on two motors driving vertical shaft pumps that ran in parallel pumping wastewater from the main pump station sump to a clarifier. The drives were chosen in preference to Variable Frequency Drives due to space limitations and higher costs associated with the VFDs. The motors can now be started uncoupled, reducing locked rotor currents and the associated water hammer and piping damage. Energy-wasting level-control and bypass valves could be deactivated and the sump level maintained by varying the speed of the pumps. Benefits Vibration and water hammer were eliminated, reducing noise and saving $15,000/year in maintenance costs. Duration of locked rotor current on start-up was reduced, potentially prolonging motor life. Energy savings of over 700,000 kWh/year were achieved. Breakthrough Technology For Speed Control Pumping Schematic Before Installation of MagnaDrive Adjustable Speed Drives The above schematic shows the mill sump controls before the MagnaDrive ASDs were installed. The level-control valve and bypass valve worked in tandem. As level increased in the sump, the level-control valve would open and the bypass valve would close. An average 7 MGD (4800 GPM) flowed to the clarifier and an average 2200 GPM flowed back into the sump through the bypass valve. Pumping Schematic using MagnaDrive Adjustable Speed Drives The above schematic shows the mill sump controls with the MagnaDrive ASDs installed. The level-control valve is locked in the open position and the bypass valve is closed. Regulating the speed of the pumps through the MagnaDrive ASDs controls level. As level increases, the pumps speed up and as level falls the pumps slow down. This maintains the sump level utilizing variable speed rather than bypassing flow. Impressive Results with the MagnaDrive Adjustable Speed Drives Regulating the speed of the pumps through MagnaDrive ASDs is significantly more energy efficient than controlling level through a bypass valve. The drives maintain the same 4800 GPM flow to the clarifier while reducing energy demand from 142 to 62 kW, a savings of 80 kW. With continuous operation, this translates to a savings of over 700,000 kWh per year. In addition, the MagnaDrive ASDs eliminate damaging vibration and water hammer, resulting in equipment and maintenance cost savings of approximately $15,000 per year. “We are extremely pleased with the energy savings we are getting with the MagnaDrive Adjustable Speed Drives. With the stability, reliability and reduced maintenance cost requirements of the system, we are excited about moving forward with other applications in the mill.” Rex Springer, Pulp and Utilities Manager The graph above shows instantaneous motor energy demand in kW versus flow rate to the clarifier in GPM. The blue line represents two pumps running using a level-control and bypass valve to maintain level in the mill sump. The red line represents the energy savings potential using the MagnaDrive ASDs to control level and flow with variable speed. Using the drives to maintain an average flow rate of 7 MGD (4800 GPM) to the clarifier, the customer experiences an average of 80 kW demand savings over the original system configuration. How the MagnaDrive ASD Operates The MagnaDrive ASD operates on the principle of magnetic induction. It consists of two independent components that have no physical contact. A precision rotor assembly containing high-energy permanent magnets is mounted on the load shaft. A conductor assembly with copper rings is connected to the motor shaft. Relative motion between the magnets and copper rings creates a magnetic field that transmits torque through the air gap between the drive’s components. Varying the width of the gap changes the coupling force, producing a controlled and continuously variable output speed. [BACK] FAQ | Contact Us | Home Copyright © 2008 MagnaDrive Corporation, All Rights Reserved.