Rotork’s innovative CVA electric control valve actuation technology has been selected for a demanding duty involving continuous modulation at what is described as a “new generation” waste water treatment plant in southwest France.
The plant is one of the largest in France as well as one of the most energy efficient. Designed for increased rainwater and effluent treatment capacity with improved treatment quality and reduced environmental impact, the plant incorporates a range of integrated energy saving and energy recovery processes. These include solar water heating, heat pumps, heat recovery from final effluent and biogas production from sludge digestion processes. Significant biogas production generates the daily equivalent of 27,000kWh, which is used as the energy source for a district heating scheme in the local area.
The biogas is produced in a process which uses a combination of solids filtration and biological aeration to remove pollutants including ammonia. The Rotork CVA actuators are installed on butterfly valves to regulate the continuous supply of air to the process. Accurate air regulation enables the plant to run efficiently and reduces air wastage.
On previous installations pneumatic actuation was used for this application, but the more accurate positional performance available with the CVA has enabled the adoption of the electrical solution on this site. Engineers from Rotork and the local Rotork distributor SERIC explained that the CVA offers very precise control valve operation, with repeatability and resolution performance within 0.1% of full scale.
