Projects - Ex-Tank Pump Temperatures

Tierney Strachan interfaces Transco LNG Isle of Grain Ex-Tank pump temperature devices to iFIX SCADA system

At the Transco LNG Storage Isle of Grain site, two thermocouple probes are fitted in each of seven ex -tank pumps. Each of the ex-tank pumps must be sufficiently cooled to LNG temperatures before being operated. The purpose of the thermocouple probes is to ensure that ‘Cool Down’ is successful before the pumps are operated.

Beka Indicator Unit

Each of the fourteen thermocouple devices are wired to a central location on the ex-tank pump platform, and interface through a rotary selector switch to a Beka indicator device. Thus it was only possible to view the temperatures locally to the pumps. The objective of this project was the integration of the temperature data from the thermocouple devices to the existing iFIX SCADA system whilst retaining the use of the local indicator.

IS-RPI Equipment Panel

The interface system selected is Pepperl & Fuchs Intrinsically Safe Remote Process Interface (IS-RPI) system and is extremely compact with the advantage of being able to be located in Zone 1 hazardous areas. This provides significant advantages in terms of cabling and the ability to interface sensors locally. The data is then passed through a ControlNet network back to the Central Control Room area. Here, an Allen Bradley SLC500 PLC scans the remote process equipment and gathers the temperature data for hand-off to the iFIX SCADA system.

The iFIX SCADA system provides process graphical displays and trending of the thermocouple temperature data to monitor the progress of the ‘Cool Down’ procedure and will provide the ability to optimise repeat ‘Cool Down’ requirements.

The system provides each thermocouple with a parallel connection to both the selector switch and the IS-RPI equipment thus retaining local temperature indication. The IS-RPI equipment was installed with a view to interfacing additional I/O in the future. For this reason the ControlNet bus system uses a 16-core fibre optic cable as opposed to copper cable providing extensive expansion capacity.