Ultrasonic flow measurement identifies scope for 84% energy saving
Using a Micronics ultrasonic non-invasive portable flow meter in a process application has led to a 75 kW pump being replaced with an 11 kW unit. Annual energy consumption has been reduced from £5698 to £926 for a capital cost of £1500 — a payback of just four months. David Leigh of Micronics explains that pumps for industrial process and building-services applications are frequently oversized and that non-invasive monitoring can identify the potential for significant savings without disruption. On this project, the pump was supplied from a high-level suction tank and process water was delivered through a 2-stage condenser to a balance tank. It was noted that a flow-control valve in the discharge pipework was only 20% open and that the flow requirement was fairly constant. The flow required to the condenser was recorded using a Micronics Portaflow 300 flowmeter. Pressure gauges were fitted at the pump to determine the pressure head generated and before and after the condenser to determine the pressure required. Analysis of the data established that the pump was too large for the required flow and that its operating point was in an inefficient area of the pump characteristic curve. 33 m of head was being removed by the control valve, representing 66% waster energy. The head requirement was 17 m, compared with 50 m provided by the pump. The inevitable recommendation was to replace the pump.