AWS Bedford Water Recycling Centre

Pump Replacement Project Overview

The original pumps were selected to for a duty flow of 638.9l/s (2300m3/hr) at a duty head of 22.43m, but as the actual head is about 15m causing the pumps to deliver more than the head works can take. The pumps were also on VSD drives which were controlled from the flume flow meter at the head works. The pump impeller curves were not suited to the pipeline low head system and with the delay in receiving the signal from the flow meter the pumps were continually ramping up and down on the VSD’s causing inconsistent flows to the works and excessive strain/overheating of the pump motors.
The site operators had lost confidence in the pumping station due these problems and they were running two pumps together to ensure the station can deliver the flows into the works in the event of a duty pump failing. The proposed work was to upgrade the pumping station to give more reliability, smoother flows and improved power consumption. For the system to work a hard wired control signal from the Doppler flow meters at the headworks back to the pump controller was required to assist in smoothing the forward flow to treatment, along with the main work of changing the pumps and optimisation.