Surge Mitigation In a Marine Fuel Oil Terminal
AFT Impulse™ Technical Paper
Authors: Dylan Witte, Purple Mountain Technology Group, USA, David Jackson, Sealaska, USA, and Trey Walters, P.E., Applied Flow Technology, USA
Presented at the 13th International Conference on Pressure Surges 2018, Bordeaux, France, November 14-16, 2018
Abstract
Surge modeling of complex systems such as marine fuel oil terminals requires the use of accurate computer modeling techniques to help insure the best possible response to surge events. Various surge mitigation techniques can be pursued that often require information that manufactures rarely provide and have behavior that is problematic to replicate in a computer model.
This paper provides guidance with one such device, the surge relief valve, and offers a case study in how they were used in conjunction with valve stroking to mitigate significant surge events at a terminal in the gulf coast region of the United States.
CONCLUSION
The use of both methods working together was successful at preventing pressure rising above the MASP in this project. Finally, the use of dual rate closure and similar SRVs without a controlled closure rate is presented. Without the controlled closure the SRVs have a high potential to chatter. When this occurs rapid changes in pressure and flow occur. The primary concern is the rapid closure on this newly introduced flow path. When this occurs secondary surges greater than the primary surge caused by the closing gate valve can occur.
Various mitigations methods can be used to prevent surge within marine terminals. Two methods, the installation of nitrogen-backed SRVs with a controlled closure rate and the use of a dual-rate valve actuation, are discussed within this paper.
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Introduction
Transient modeling and analysis of hydraulic surges at marine terminals is one of the most important tasks to be completed when considering original construction, operational changes, or expansions to a terminal site. The potential damage from failure is high and the complex piping networks and specialty equipment used at these sites makes a detailed computer simulation necessary to capture how the system will likely respond to a transient event.
The marine terminal considered in this paper is in the gulf coast region of the United States and can import and export fuel oil from multiple connected pipelines or multiple ship docks. This ability to send and receive allows for more economic flexibility as production rates and prices vary globally but creates many complications for the engineer concerned with surge mitigation.
For example, surge valve setpoints used for importing may not be appropriate for exporting as the pressure at the valve location will almost certainly be different upon a flow reversal. Other surge mitigation equipment sized for a specific case has the potential to cause a worse surge response if they are active during an unanticipated surge event for which they were not designed.
The marine terminal must be considered on a whole and one surge mitigation strategy for one situation may not be appropriate for the next. Often a strategy may work well, but can require the purchase, installation, and maintenance of costly and complex equipment. This paper considers a compromise between an increase in the amount of surge mitigation equipment, especially nitrogen backed surge relief valves, and the use of a dual rate closure similar to the valve stroking method from Swaffield and Boldy (1).