Mokveld delivered the first local pressure control loop with a pressure transmitter directly connected to the control valve in the Far East almost 10 years ago. A back-pressure control application, with a conventional gas driven actuator.
Building on this solution we recently commissioned the first electric driven ‘self-acting’ control valve in a (European) gas plant, at a pressure reduction station. The pressure transmitter is directly connected to the electric drive. The PID controller in the drive controls the downstream pressure. In this specific case a remote setpoint allows modification of the controlled pressure depending on the requirements from the central command centre (e.g. in summer lower pressure than in winter).
Mokveld replaced a natural gas driven control loop for a solution with virtually no emissions. The carbon footprint is vastly reduced, but also the lifecycle cost improved.
The volume downstream of the control valve is very big which allows for the control loop to be stay-put upon loss of electric power. In case of electric power failure a generator is started and the client’s service engineer is warned and will go directly to site.