Problem 6.8) The tank field and unloading dock system shown below stores oil from wells in Algeria. The oil flows from the fields at a rate of 600 bbl/min into 5 tanks, each with a capacity of 1,000,000 bbl.
Ships with a capacity of 1,000,000 bbl come to offload the oil at an average of one ship per day, distributed exponentially. The offloading lines can pump oil into each of the tankers at a rate of 8000 bbl/min. It requires between 100 and 140 minutes to dock the ships at the loading dock, with a sigma of 40/6 minutes, and between 10 to 30 minutes to cast off, with a sigma of 20/6 minutes, both distributed normally. Up to three ships can dock at the unloading dock at a time.
Storms entering the area will disrupt docking and/or loading. One third of the storms coming through the area (large storms) are of such magnitude that both docking and unloading operations are affected. You have enough warning that if loading or docking has commenced, they may continue. If not, these operations must not begin until the storm has passed. Smaller storms merely require that docking operations be delayed, and resumed after the storm passes (i.e. loading of a docked tanker may continue during the smaller storms.) Storms hit the area exponentially distributed about every month, with large storms lasting for a mean of three days, with a sigma of one day. Smaller storms last for a mean of one day with a sigma of 1/2 day.
Our problem is that the pipeline cannot be shut down for any reason. If shut down, the oil cools and solidifies in the pipeline, and we will never get it flowing again. Study the tank farm for three months, and determine if 5 tanks appear to be enough to prevent having to shut down the incoming pipeline because of the tanks getting full. If the tanks ever get full, you may shut down the simulation since the result is unacceptable. Please assume that the tanks are 1/2 full when you start your analysis. You may assume that oil comes into the facility in chunks of 600 barrels per minute, rather than continuously.