30 n VARIABLE-SPEED DRIVES January 2024 www.drivesncontrols.com VSD supplier change improves sludge machine reliability Yangzhou Maoyuan Environmental Protection Technology (MYEP) is a Chinese machine-builder that specialises in sludge dewatering and treatment machinery, as well as other wastewater treatment equipment. It was established in 2014 and has a factory in Yangzhou, about 280km from Shanghai. MYEP holds several key patents, and uses an advanced production management system. This supports a product portfolio which includes e cient screw press sludge dewatering lines, low-temperature sludge dryers, belt press sludge dewatering machines, and sludge suction machines. An important area where the company’s dewatering equipment is applied is for municipal sewage and domestic sewage treatment. A few years ago, MYEP developed a spiral sludge dewatering machine for more e cient solid-liquid separation, based on screw extrusion. Using a tiny gap between moving and xed rings, the machine uses high-pressure extrusion to achieve high levels of sludge dehydration. The spiral technology oers benets including reduced clogging, continuous operation, low civil engineering and running costs, and a phosphorus removal function. Sludge dewatering is very demanding due to the harsh conditions, corrosive materials and the physical characteristics of sludge where water content levels can uctuate, making precise control di cult. The new spiral technology presented even greater challenges due to the high pressures involved. Reliability and quality are essential in sludge dewatering operations because the process needs to keep operating around the clock. Cost pressures in the competitive market made it a di cult balancing act for MYEP to get the high reliability and performance end-users want, but at a cost that they are willing to pay. A further concern was service and repairs, which MYEP wants oer rapidly in the event of any issues. In 2020, the company decided to change the supplier of the drives it uses for the spiral sludge dewatering systems, replacing the old drive from a dierent supplier with ABB ACS180 machinery drives. This has increased reliability signicantly, and the compact drives handle the machine’s motor speed and torque adjustments precisely, with a low failure rate. About 800 of the drives have been installed on the machines, without any problems. “These drives give us the high quality and high reliability that we need for running the spiral sludge dewatering machine e ciently,” says Feng Zhaoqing, electrical control support manager at MYEP. “The ACS180’s vector control gives the machine the required high starting torque, while also allowing improved dewatering e ciency for the best sludge treatment, even when the water content varies.”The drives’ coated PCBs also make them ideal for the applications involving harsh, corrosive environments. Wang ZhongCen, sales director for infrastructure and the transportation industry at ABB Motion in China, points out that the drives’ high reliability even under harsh conditions, makes them especially suitable for equipment such as the spiral sludge dewatering machines. “Using the ACS180 also helps cut energy use and reduce noise, since the spiral design adjusts the pressing load by controlling the speed of the screw conveyor,” he adds. “And if any manual intervention is needed, the control panel is easy to operate, allowing operators to change the settings to adapt to changing dewatering conditions.” n A Chinese manufacturer of sludge dewatering machines has improved their reliability and performance by changing the drives it uses. The new VSDs allow the control of the demanding dewatering process to be ne-tuned to cope better with uctuating water content levels. The new drives controlling MYEP’s spiral sludge dewatering machines use vector control to give a high starting torque, while also improving dewatering e ciency
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