Plant operators ‘have much to consider’ before implementing refrigeration terminal solutions
Despite the production and pricing challenges seen in 2020, liquefied petroleum gas (LPG) exports remain strong in 2021, according to Chris Niemeyer, process technology manager at Burns & McDonnell.
He said propane exports are still topping one billion barrels (bbl) per day, and a rise in ethane crackers in China is leading to an increase in demand for exported ethane.
He added: “For grassroots and revamped export terminals, thoughtful optimisation is key to minimising installed capital. Optimisation maximises terminal and dock utilisation, while still reducing operation costs and overcoming plot constraints.
“Once forecasts are made, pipeline capacity from a fractionation facility to the terminal will need to be built or expanded.”
But managing both total installed cost (TIC) and operational efficiency is a difficult balance to maintain, according to Niemeyer: “A major consideration in planning for these drivers is the decision to install a tank or use a direct load system. While a significant investment upfront, tanks can help plants manage inventory and uncertainties in ship scheduling.
“Product supply into the tank is steady, with the tank level effectively managing load swings. This allows use of a smaller supply pipeline diameter and smaller refrigeration equipment installed at the plant. Having a tank at the terminal at least the size of the ship load provides the ultimate flexibility; however, there are other factors for operators to consider.”
But he said operators will also have to make the decision between using a double-wall or single-wall tank: “With external containment, single-wall tanks are appropriate for LPG products such as propane or butane. A disadvantage to using single-wall tanks is that the containment will take considerable plot space. Although an increase in capital investment, double-wall tanks can be designed for full containment, greatly reducing the plot space required.”
Additionally, plant operators have the option to use a direct load concept to batch material from a fractionator or storage cavern to load a ship upon arrival at the dock. This eliminates the need for a tank and greatly simplifies the plant design.
However, Niemeyer added: “For the same average production rate this requires significantly greater pipeline capacity to account for idle time between loading ships. Larger diameter pipelines and larger, higher horsepower (HP) refrigeration equipment will then be used. The ultimate decision on whether to employ a tank is therefore dependent on several considerations and can vary from project to project.”
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28th April 2021