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The California Energy Commission and the U.S. Department of Energy, Office of Industrial Technologies BestPractices present: ENERGY SOLUTIONS FOR CALIFORNIA INDUSTRY: WAYS TO IMPROVE OPERATIONS AND PROFITABILITY AUGUST 2001 CASE STUDY BENEFITS Saves $17,000 in annual energy costs Improves equipment life Improves productivity Reduces maintenance costs APPLICATIONS Pump systems are widespread and consume a significant portion of the electricity used in industrial plants. In some cases, using Adjustable Speed Drives (ASDs) provides an effective means of matching pumping output to system requirements and can improve operational reliability. ABOUT THIS EVENT The purpose of the Energy Solutions for California events is to provide a professional, solutions-oriented environment for industrial electricity users who face serious challenges to remaining operational and profitable during the current energy crisis. Industrial electricity users have the opportunity to receive unbiased information and analytical tools that can increase reliability and manage short and long-term production costs. Pump System Improvement Saves Energy and Improves Production at a Construction Aggregates Company Summary In 2000, Teichert Aggregates, Inc., with assistance from its local electric utility, Sacramento Municipal Utility District (SMUD), improved the pumping system at its Perkins aggregate processing plant in Sacramento, California. The plant decided to evaluate its pumping system because it was having problems maintaining stable flow and had excessive maintenance requirements. Based on the evaluation, the plant implemented a project that improved the pumping system’s effectiveness by adding a magnetic induction Adjustable Speed Drive (ASD) to the system. The total cost of the project was $34,000. With annual energy savings of $17,000 (233,000 kWh), which represent 24% of the pumping system’s power costs, and a grant of $15,000 for advanced technologies from SMUD, the project’s simple payback was just under 13 months. The project also reduced maintenance costs, increased pump bearing life and improved the plant’s process control. ENERGY SOLUTIONS FOR CALIFORNIA INDUSTRY: Company/Plant Background Teichert Aggregates, Inc. is one of California’s largest aggregates companies. Established over a century ago, Teichert employs over 1,000 people. Teichert implements a full range of construction projects ranging from construction of residential driveways, to freeways, subdivisions and underground projects. The company also mines and produces a variety of construction materials such as sand, gravel, asphalt and concrete. Teichert Aggregates is one of the largest sand and gravel producers in the U.S. and maintains several plants, including the one in Sacramento, California. The Perkins plant in Sacramento, California is one of Teichert Aggregate Inc.’s largest construction aggregate facilities, producing concrete, processed sand, gravel, crushed rock, and asphalt for a wide variety of construction projects. The gravel production process uses a feedwater system to help separate and wash the different types and sizes of aggregates. Water is pumped up to the top of a 95-foot high wash-down tower where it mixes with the aggregates. As the aggregates flow down the tower, they pass across a series of screens and are separated into fractions. Project Overview The wash-down tower was having problems related to stability of water flow and excessive maintenance, so the plant had its pumping system evaluated by an outside consultant. The pumping system that feeds water into the wash-down tower is a 300-hp centrifugal pump that is rated for 5600 gpm. The wash-down tower’s optimal flow rate for reliable production is 4260 gpm. However, the plant had to throttle the pump down to this level with a control valve because full flow would flood the wash-down tower and interrupt production. However, throttling the pump down to that level resulted in unstable flow and caused the pump and its adjoining structures to shake violently. The evaluation found that the unstable flow was the result of the pump operating at a point that was far below the Best Efficiency Point (BEP) on its performance curve. The violent shaking was due to cavitation downstream around the discharge valve. The cavitation led to high maintenance costs because it put excessive stress on the pump’s bearings and could also erode the piping. The evaluation also found that the pump drew a peak level of 247 kW when throttled to the 4260- gpm levels. Ways to Improve Operations and Profitability Project Implementation The evaluation’s main recommendation was to install an ASD to match the pumping system’s output to the plant’s requirements. The project would replace the control valve operation with an ASD and was projected to save energy and reduce maintenance. The motor was moved back on its base and an actuator installed to allow for reduced pump speed and better process control. The plant manager decided on a special type of ASD that uses magnetic induction. The plant manager selected this type of ASD because it was at least as efficient as a Variable Speed Drive (VSD) at 90% or higher of motor speed, which is the level at which the plant manager expected to operate its pumping system. In addition, this ASD was very rugged and simple, did not require an inverter-duty motor, extensive wiring, or air conditioning. Project Results Thanks to the project’s implementation, the Teichert Aggregates plant achieved positive benefits in terms of energy savings, reliability and maintenance cost reductions. The ASD allowed the pumping system to run at 4258 gpm without any unstable flow. Running at this level reduced the pump’s annual electricity consumption by 233,000 kWh (24% of its annual consumption), which translates into annual energy savings of $17,000. Furthermore, the cavitation was eliminated, dramatically reducing the vibration and lowering long-term maintenance costs. The plant’s utility was so impressed with the reduction in energy consumption that they issued a $15,000 rebate for the project. Since the project’s cost was $34,000, the simple payback was slightly less than 13 months. In addition, the plant manager realized that if the impeller started to wear, it could maintain exact process flow to the wash-down tower by simply speeding up the pump. Lessons Learned Properly configuring a pumping system so that its capacity is suited to a plant’s production requirements is extremely important. Pumps allow for stable flow and consume the least amount of energy when they operate at the BEP on their performance curves. When they do not operate at the BEP, pumping systems can experience energy waste, unreliable production and high maintenance costs. Different systems should be evaluated to effectively match the available pumping capacity to production requirements, while keeping pump operation at the BEP. For the Perkins aggregates plant, a magnetic induction ASD was the appropriate and most costeffective solution for the pumping system’s problems. The implementation of this project led to important energy savings and allowed the plant’s pumping system to operate more effectively. United States Department of Energy’s Office of Industrial Technologies BestPractices BestPractices is part of the OIT’s Industries of the Future strategy, which helps the country’s most energy-intensive industries improve their competitiveness. BestPractices brings together the best-available and emerging technologies and practices to help companies begin improving energy efficiency, environmental performance, and productivity right now. California Energy Commission The California Energy Commission is the state’s primary energy policy and planning agency. It is the California Energy Commission’s mission to assess, advocate, and act through public/private partnerships to improve energy systems that promote a strong economy and a healthy environment. PROJECT PARTNERS Teichert Aggregates, Inc. Sacramento, CA Sacramento Municipal Utility District Sacramento, CA MagnaDrive Corporation Seattle, WA For Additional Information, Please Contact: U.S. Department of Energy OIT Clearinghouse Phone: (800) 862-2086 Fax: (360) 586-8303 E-mail: clearinghouse@ee.doe.gov Web: www.oit.doe.gov California Energy Commission Phone: (916) 654-4287 E-mail: energia@energy.ca.gov Web: www.energy.ca.gov FAQ | Contact Us | Home Copyright © 2008 MagnaDrive Corporation, All Rights Reserved.