The assets at Bayreuth sewage treatment plant operate almost continuously. When the time came to replace a motor at the site, operators seized the opportunity to specify an optimum replacement. Bauer Gear Motor was ready to offer an innovative permanent magnet synchronous motor (PMSM) solution that provided improved efficiency and increased cost-effectiveness.
In any industry, securing efficiency is important. For critical infrastructure such as wastewater treatment plants, where duty requirements are continuous, it is even more so. Therefore, selecting an optimum geared motor to efficiently meet these duty requirements can deliver a winning combination of cost-effectiveness and increased environmental protection. This is exactly what Bauer Gear Motor, a leading brand of Altra Industrial Motion Corp., has enabled for an eccentric screw pump at Bayreuth sewage treatment plant in Germany.
Bear Gear Motor is a world leader in technology for geared motors – always ahead of the curve in terms of delivering high performance and efficiency drives. Since the founding of the business in 1927, it has focused on providing optimum motor and gearbox solutions – allowing operators to access application reliability while safeguarding return on investment (ROI) and overall energy consumption.
This is of pertinence for the water treatment sector. At Bayreuth, the eccentric screw pumps are required to operate almost continuously 365 days of the year. Over such duty requirements, an improper motor can generate excessive costs for operators. Specifying an oversized motor, matching it to incorrect components, missing the operating point or improper gear selections can have a debilitating effect on long term energy efficiency. Specifying an optimum drive solution for this application, in conjunction with the pump manufacturer, was the challenge presented to Bauer by plant operators.
As is to be expected of a global technology leader, Bauer had a solution. Working with the pump manufacturer, Bauer discovered that the installed 15kW IE3 asynchronous motor (ASM) could be downsized to a 5.5 Kw IE3 drive with PMSM technology.
A downsized motor obviously provides improved energy efficiency, but the design of Bauer PMSM drives home the advantage. An exceptionally efficient rotor design features specialised permanent magnets, which provides power savings and improved environmental credentials compared to traditional motors. Heat losses from the rotor are eliminated and total losses reduced by 25%, which results in consistent motor efficiency improvements of over 10% compared to competitor drives. These characteristics ensure high efficiency even across varied duty requirements.
Other eccentric screw pumps at the plant were still operating ASM variants, which allowed Bauer and operators to conduct a direct comparison. Operating both ASM and PMSM variants at a constant speed of 25Hz, the PMSM was found to deliver continuous energy efficiency across the curve, especially at low load. When speed was varied, the PMSM was still more efficient under partial load. At low speed and load, the PMSM achieves 85% efficiency compared to 65% for the ASM. This illustrates the wide partial load operation and speed range offered by the inherently efficient PMSM.
Benefits to the application are many. Eccentric screw pumps operate at different speeds and operating points depending on requirement, which suits the wide partial load operation and speed range offered by the PMSM. Furthermore, this range offers a higher overload capability, which is advantageous if another pump fails on-site and the same duty requirements are spread across fewer pumps. If installed motors provide greater overload capability, this requirement is easily met, protecting uptime. A high starting torque is another inherent feature, which is important when pumping fluids. Downsizing the motor also eases future maintenance, as the smaller motor can be easily replaced if the need arises. Connecting cables were also half the thickness of the ASM equivalents, also reducing costs while ensuring easier handling and maintenance.
However, the principle benefits to operators was increased efficiency across all duty requirements. A minimum 10% overall efficiency improvement extending over yearly operating cycles delivered considerable cost savings of up to € 9.000 per pump per year and environmental advantages on top. As well as reducing energy bills, operators could easily meet targets for CO2 emissions, which are tightening in all aspects of industry. This matched with the inherent performance and reliability of the PMSM, means the operators reached the goldilocks zone of efficiency created by an optimum motor designed for varied duty requirements.
Wastewater Treatment with Ultrafiltration Membrane Modules
This videoclip features state of the art treatment of wastewater with ultrafiltration modules manufactured by CUT Membrane Technology. A clean and very efficient method to minimize the wastewater fraction which in this example emerges from a cottage resort relying on decentralized water and wastewater management.
Air/oil separation in an air compressor
Fresh fragrance on feminine hygiene products
Smallest quantities sprayed continuously but flexibly
A new project of Visctotec Asia at the end of 2019 was the application of a fragrance on top of feminine hygiene products. Before implementation, dosing tests were carried out for the customer. A preeflow Eco-Spray dispenser was employed for this. The aim of the tests was to check the dosing accuracy and repeatability of the Eco-Spray for the small quantities. A particular challenge was to achieve precise results for various different products. Various quantities were to be tested for several products in the customer portfolio: 1.5, 1.8 and 2.5 mg per part – to allow flexible automated production. The in-depth dosing tests consistently demonstrated the accuracy and consistency of the small volumes required for the process. With the preeflow spray dispenser, Visctotec Asia is able to spray with less than 1 % deviation from the nominal value.
An example from the customer’s portfolio: The parts to be dispensed run in a roll form under the Eco-Spray. The speed of the roll is over 1,500 parts per minute. At the final stage, the customer wants to apply a small amount of <1.6 mg of fragrance to each product. The material is gravity fed from a container suspended about 2.5 meters above the floor. The method used up to now could not precisely dose such a small volume in each part and had poor repeatability. In conclusion, the customer decided to purchase the Eco-Spray from preeflow to integrate the spray dispenser into the existing line.
The key to success: The dosing tests proved that the customer required volume accuracy and consistency for product model could be achieved. In addition, the change from a pressure tank or gear pump tank, which was previously used, to product being fed by a gravity tank was convincing. An analog signal with PLC now also makes it possible to link the speed of the production line with the flow rate of the dispenser. This means that the amount of liquid to be sprayed can be dynamically adjusted according to the speed of the roll.