This paper discusses the tank management optimization or automation of floating Storage Unit vessels in Peninsular Malaysia. The objective of automation is to determine which tanks need to be emptied for the incoming cargo (unloading process) and for the gas product from the regasification to be maximized. The FSU and jetty regasification unit (JRU) are in the same location, and both are offshore. Therefore, efficient production strategic planning is required.
Tank management of the FSU unit has two procedures that must be fulfilled during the unloading and send-out activities: (i) The calculation must be developed beginning with the unloading – send -out activity. The activity is conducted when new cargo comes and fill the tank in the FSU (unloading). Meanwhile, the send-out activity is also conducted to manage high boil off gas (BoG) generation (re-condensation of the BoG) resulting from the unloading activity. The send-out activity must be conducted from the tank to the regasification unit. (ii) The send-out activity occurs after the unloading-send-out activity (previous activity) to fulfill the requirement from the regasification unit (nomination). The liquified natural gas (LNG) storage does not allow for mixed cargo to be stored in the same tank.
Automation will provide an optimum send-out plan from each tank and each FSU. Currently, the range of cargo volumes that comes to the FSU is between 130 to 145 K M3. Using the proposed method, larger cargo could be scheduled and maximum gas from regasification at the JRU increases. Tank management automation will consider the first-in-first-out (FIFO) method regarding unloading time, boil off gas (BoG) temperature condition, and tank send-out sequence to ensure FSU balance. The FSU balance must be considered for the safety of the entire LNG regasification operation. Automation will provide an indication for the inter-tank transfer strategy when the volume of the incoming cargo requires more space compared to the available space.
This is the first concept developed to create the best strategy for utilizing FSU and JRU units. The same concept could be implemented around the world for different cases, such as FSUs located offshore and JRUs located onshore, different tank sizes, and different regasification units.