Refurbished pumps help improve cost savings

Riventa has identified annual savings of almost £20,000 (€23,600) for a food processor’s cooling system after refurbishing five pumps.
Sending chilled water from heat-exchangers, the pumps were all found to be showing significant signs of wear.
With an average load of 45% (equivalent to 2.2 pumps running at any one time), the five pumps had even more demands placed on them during warmer weather, sending their best efficiency point (BEP) even lower.
To evaluate the horizontal end-suction pumps, which are driven by a motor with an inverter drive (to allow control of the flow rate), Riventa utilised its specialist FREEFLOW technology to employ thermodynamic measurement technique (ISO 5198).
This included suction and discharge pressures either side of the pump, differential temperature, and motor input power. These measurements enabled Riventa to calculate differential head across the pump, hydraulic efficiency and volumetric flow.
The pumps were altered gradually. After each change, a test point was taken, while allowing enough time to obtain the best statistical average.
Tests also involved a routine of testing performance at an incumbent set point, followed by throttling the pump to reduce its flow rate. The latter action allowed other pumps running in parallel to increase in speed to compensate, with a final test point taken at this moment. By throttling, Riventa could carefully observe the maximum possible flow through each pump under test, without altering the overall flow to the plant.
Steve Barrett, managing director of Riventa, commented: “While pumps one to three achieved a good relationship between power and flow, pumps four and five were not performing when at lower flows. This indicated a high likelihood of internal recirculation – from high to low pressure parts of the impeller – being caused by high wear.”
He added: “As energy costs become more of a concern than ever before, food processors can make big savings on equipment such as pumps by having them tested properly. As well as reducing energy bills, companies can maximise reliability and minimise whole life costs.”

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