Finger-Type Slug Catcher and Inlet Receiving Design Considerations for Onshore LNG Facilities

A multiple-pipe type slug catcher otherwise known as a finger-type slug catcher is located at the inlet of a gas processing / LNG facility and is intended to separate the incoming pipeline gas and liquid into separate phases and to provide temporary storage for the liquids received. The separated liquids are further sent to downstream units for processing. Finger-type slug catchers, although simple in design, can occupy significant plot space and are expensive compared to vessel-type slug catchers.

Once a finger-type slug catcher is selected, several parameters are to be defined including liquid storage volume, design pressure, two-phase vs. three-phase separation, design factor, materials selection, solids handling, emergency depressuring and impact to flare design. A transient simulation of the arrival scenarios (such as pigging and flow ramp-up) is typically performed to determine the slug arrival duration, volume and other relevant information. This paper highlights some of the important design issues surrounding the selection of a finger-type slug catcher in an onshore LNG facility.

A rigorous transient model helps to eliminate assumptions regarding the conditions at the interface between offshore and onshore facilities. A well-integrated model can also be used to establish operational strategies. The trade-offs established during design between capital cost and operational flexibility can also be verified. This paper presents a case study where a rigorous pipeline model is linked with a dynamic process simulation model of the onshore LNG plant. This integrated model is then used to test various arrival scenarios that can impact the operability of the LNG plant.