(371q) Detailed Dynamic Modeling and Simulation of Flare Networks

The flare networks for major plants represent a non-negligible part of the overall capital investment. Current industrial practice for their design is primarily based on steady-state analysis, as described in standards such as API 521 and supported by widely-used software tools. However, it is a widely recognized fact that the application of steady-steady considerations to what is fundamentally a dynamic system inevitably requires the use of conservative assumptions which often result in significant oversizing of flare headers and other components of the network. Another major contributor to capital cost is the use of special materials for the parts of the system that may be exposed to low-temperature fluids ? typically the tail pipes attached to high-pressure process vessels and also the parts of the main flare headers connected to them up to the point where heat transfer with the environment brings the temperature to a level that does not lead to the risk of embrittlement. Also, the relief of high temperature fluids (e.g. from vessels under fire) may require the introduction of thermal expansion loops, which also add to the capital cost. In both the cold and the hot relief cases, the key to being able to limit the additional capital expenditure is the accurate estimation of the length of piping that is subject to ?abnormal? temperatures.

This paper describes an advanced system for model-based flare system network design that addresses the above issues while being compatible with existing steady-state flare network technology. The system supports steady-state and dynamic analysis, wall temperature modeling and prediction of hydrate and ice formation within a single integrated framework.