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These liquid-ring pumps feature two drives

| By Chemical Engineering

Edwards Vacuum

The ELRi range of liquid ring pumps (photo) is designed for use in applications that are wet, humid and corrosive. The stainless-steel impeller, endplates, liquid reservoir and heat exchanger make this pump highly resilient against corrosion and harsh process gases. The internal injection channels reduce the risk of leakage while the horizontal motor-flange arrangement saves time on maintenance. ELRi pumps are equipped with two variable-speed drives (VSDs). While the main VSD matches the speed of the pump to vacuum level by adjusting its speed, the second VSD regulates the water flow through the centrifugal pump according to the operating conditions to avoid risks of cavitation. A patented algorithm maintains synchronicity between the two VSDs. In addition, pumps are protected against automatic seizure, so pump failure is not a concern after long periods of inactivity. The ELRi series is available with pumping capacity from 750 to 1,050 m3/h. All pumps are also fitted with spray nozzles as standard, which are particularly useful for high-steam-load applications. Moreover, manual and automatic flushing modes allow operation in dirty applications with minimal downtime. — Edwards Vacuum, Burgess Hill, U.K.