Computational Fluid Dynamics (CFD) Exhaust Dispersion Study

Requirements

We carried out a Computational Fluid Dynamics (CFD) Exhaust Dispersion Study for the ICHTHYS Field Development Project Floating Production Storage and Offloading (FPSO) vessel, to be located in the Browse Basin off Western Australia, approximately 440 km north of Broome and 800 km southwest of Darwin.

The ICHTHYS natural gas field, located in the Timor Sea, was discovered in 2000 and developed by Inpex. Its total proven reserves are around 12.8 trillion cubic feet (366 billion cubic meters), and production estimated to be around 350 million cubic feet/day (10 million cubic meters/day).

Solutions

The main objectives of the analysis were to:

• Evaluate the temperature rise around the helideck due to dispersion of hot exhaust gases and unburned hydrocarbon concentration from the Main Power Generator / Waste Heat Recovery Unit, Heating Medium Heater, Firewater Generator  and Emergency Diesel Generator in accordance with CAP 437
• Assess the impact of the exhausts on personnel operations and sensitive receptor locations (i.e. lifeboats, life rafts, personnel access/escape and HVAC air intakes) with respect to NOHSC (Australian Standards) exposure limits for toxic gas and NIOSH exposure limits for temperature
• Assess the impact of the exhausts on crane cabins (i.e. pedestal crane cabins and knuckle boom crane cabin) and operations (i.e. restrictions on boom rotation, grease and wire integrity) with respect to the maximum premissable limit (i.e. 80 °C) of heat exposure
• Propose design modifications, mitigation measures or operational restrictions to reduce the risk to personnel safety, crane and helicopter operations

Benefits 

A CFD exhaust dispersion study was carried out to establish the temperature rise and toxic gas concentration for a range of wind speeds and directions that had the potential to affect helicopter, personnel and crane operations.