Energy investigation of pressure pulsation and flow instability in centrifugal pumps used in biodiesel plants

Abstract

Centrifugal pumps (CPs) are widely used in biodiesel plants, where performance degradation caused by leakage, vibration, and corrosion can significantly reduce efficiency and reliability. This study investigates the causes of abnormal pressure loss and flow instability in a CP used for biodiesel loading operations in Indonesia. Experimental monitoring of pressure, flow rate, vibration, noise, and power consumption was carried out under both abnormal and repaired (normal) conditions over a 24-hour period. Results showed that under abnormal conditions, the Best Efficiency Point (BEP) shifted to a flow rate of 65,000 kg/h with a head of only 3.39 m and an efficiency of 51.7%, compared to 90.4% efficiency at 57,000 kg/h and 8 m head under normal operation. Although a peak efficiency of 90.1% was observed at 14,000 W and 4.2 mm/s vibration, this condition was unstable and highly fluctuating. Mechanical inspection revealed impeller scraping, bearing corrosion, and drive coupling damage as the primary causes of performance deterioration. The correlation between vibration, noise, and pressure drop further confirmed the relationship between mechanical faults and hydraulic instability. These findings provide deeper insights into energy losses in CPs used for biodiesel handling and emphasize the importance of predictive maintenance and vibration-based condition monitoring. The study offers practical guidance for improving CP reliability, minimizing downtime, and enhancing energy efficiency in biodiesel production facilities.