Rotork is on the site of the La Dehesa and La Flordia solar plant installations in the state of Badajoz, Spain, for a retrofit project on the plants’ HTF (Heat Transfer Fluid) pipework.

The HTF pipes carry the heat transfer oil between the parabolic mirrors, the steam plant and the power generation circuits. At each site Rotork is now installing 168 actuators and four Pakscan P3 master stations for the automation of 3in globe valves, to introduce remote control of the HTF temperature. The linear stroke of each valve is 30mm and the requirement is to move a minimum of only 1% of this stroke, resulting in discrete movements of only 0.3mm.

To achieve this, Rotork is supplying a linear version of the IQTF multi-turn actuator, which operates at a relatively low output speed to provide maximum resolution and accuracy. The positional monitoring and control signal is provided by the Pakscan P3 system, using Modbus RTU protocol, over a two-wire, twisted pair bus loop. Automatic, inbuilt redundancy of the field network is an integral part of the Pakscan design, ensuring that control is maintained even in the event of equipment or cable failure.

Data loggers within the IQTF units facilitate valve diagnostics by recording historical operating data and valve torque trends. The Rotork IQ-Insight software can analyse the data on a PC to predict any potential operating issues, enabling maintenance to be planned in advance without interruption to normal plant operations.