Rotork actuators are fulfilling the all-electric specification for valve control on new gas dehydration units in Transylvania. The plants have been built for Romgaz, the largest natural gas producer in Romania.
Dehydration plants use triethylene glycol to remove the water from natural gas in order to prevent downstream processing problems such as freezing, corrosion and the formation of hydrates.
The specification for the new plants ruled out the use of air instruments and compressors, dictating the use of explosion-proof electric actuators for isolating and control valve duties in the hazardous areas.
This has been achieved with ATEX certified Rotork IQT isolating valve actuators and CVA control valve actuators.
Both designs feature intrinsically safe, non-intrusive setting and configuration technologies; data logging for diagnostics and preventative maintenance planning; and double-sealed watertight environmental protection. The CVA offers a highly accurate and responsive method of automating control valves without the complexity and cost of a pneumatic supply, says the company. With resolution figures better than 0.1% and the ability to eliminate position overshoot, the CVA helps to maximise product quality and plant capacity.
The electrical supply to the dehydration units is secured by means of a three-tier failsafe system comprising mains power supported by a 30kVA uninterruptable power supply and a 45kVA natural gas powered generator. Centralised control is provided by a Cytect SCADA system and ABB PLC, housed in a control room adjacent to each plant.
An Eex-e certified PC with mimic panel and identical graphical interface is located within each plant, enabling operators to work on the system in the field as well as the control room.