(7b) Unified Evaluation of Complex J-T Induced Thermal, Flow and Phase Dynamics for Capacity Increase of Offshore Flare System

A case study reveals unique benefits from integrated multi-physics analysis, when re-evaluating an existing flare system after increased process loads are added.
The system includes one flare header and stack, shared via a bridge which connects separate offshore process and drilling platforms and their very different relieving compositions. Multidisciplinary analysis includes comparison of steady state and dynamic evaluations for each of metal temperature profile along the existing carbon steel bridge line, liquids dropout rate, multiphase slip flows, and their combined transient effects on increased flare tip radiation loads.

In some ways, a steady-state evaluation is still shown to be beneficial. But in other ways, dynamic evaluation is shown to add a large amount of extra Return on (Engineering) Investment – particularly when it is now integrated within this new, efficient workflow.

Therefore, the authors recommend utilizing these newest and most efficient interdisciplinary workflows to simultaneously re-check all of header and stack capacity, J-T effects, potential cold-wall-temperature metal embrittlement, liquid dropout rate, multiphase slip flow, and flare stack radiation. Analysis of the new workflow shows that it does now accomplish this ambitious scope in one integrated manner.

This efficiently combines the benefits of both steady-state and dynamic workflows, as permitted by the governing Relief System Codes (but often ruled out for presumed high cost).

In the current case study, such integrated, multi-physics, steady-state and dynamic analysis was required to prevent costly flare system upgrades while still satisfying all applicable safety codes.