(117a) What Is the Impact of Dynamic Flare System Design on Cost, Safety, and Environment?

In the context of process safety equipment design, dynamic flare analysis can have a significant impact on project capital cost, safety, and environmental impact. Despite these clear benefits, steady-state analysis remains the industry standard.

A flare system is an essential safety component in various industries such as Oil & Gas and Chemical processing plants. It is designed to safely burn hazardous material that cannot be processed or used due to economic or technical reasons. The flare system is a network of pipes, knockout drums (KO drums), and flare tips designed to gather hazardous fluids from various sources such as relief valves, blowdown valves, pressure control valves, and manual vents. In essence, it collects and directs the gases to be safely burned off at a distant and secure location. Flare systems have been designed and applied to industry for more than 40 years.

A critical examination of traditional methods used in the design of flare systems and pressure relief devices will be discussed. The limitations of these methods, particularly the over-reliance on simplifying assumptions and approximations, such as constant relief flows, steady-state flare network modeling, constant heat of vaporization, or a lumped-approach representation of process segments, often lead to excessive overdesign. The study then introduces dynamic analysis as an alternative design method.

The application of dynamic analysis in flare system design has significant implications on capital expenditure (CAPEX) and emissions, while still adhering to industry standards (such as API 521). Use cases demonstrate the potential advantages of dynamic analysis, including more accurate and cost-effective solutions, enhanced safety measures, and minimized environmental impact. Flare systems designed using dynamic simulations can reduce the flare network size and associated equipment significantly, and more accurately determine the location of material specification breaks (e.g., from stainless steel to low-temperature carbon steel). This often leads to an overall reduction in CAPEX as well as purge flow requirements.

An alternative flare system design approach is presented by showcasing the value of dynamic analysis over traditional methods.