PTQ Q3 2026 Issue

Process simulation and dispersion modelling for leaks risk assessment

An integrated approach using a naphtha reformer stabiliser shows how composition affects dispersion and flammability risk under consistent operating conditions

F ugitive emissions remain a persistent operational challenge in refining. These are unintentional releases of gases or vapours from pressurised equipment, including valves, flanges, pumps, and connec - tors.1 These releases contribute to product loss, introduce safety risks, and increase the complexity of emissions management. However, major process fluid leaks due to, for example, corrosion issues in process equipment and piping in a plant are more serious. In contrast with fugitive emissions, they can be hazardous, potentially causing explosions, or lethal to workers if they contain poisonous substances.2 Industry observations indicate that most emissions orig - inate from a set of components, which can account for a significant share of total emissions across a facility.3 This creates a practical challenge: while thousands of compo- nents can be potentially monitored, only a small fraction contributes to measurable emissions at any given time, making detection programs resource-intensive without necessarily improving risk visibility. While detection technologies have advanced signifi - cantly, they do not provide sufficient information on their own to assess risk. Detection systems indicate the pres - ence of a release but do not quantify composition or predict dispersion behaviour. As a result, operators cannot reliably distinguish between low-consequence leaks and releases that may lead to flammable or toxic vapour cloud formation. Rodolfo Tellez-Schmill and Michelle Wicmandy KBC (A Yokogawa Company)

This gap between detection and decision-making reflects a lack of context rather than a lack of data. From detection to decision Developments in digital tools, particularly the integration of process simulation with dispersion modelling, address this bespoke challenge. By linking process twins with disper - sion analysis, operators can evaluate leak composition and dispersion behaviour under operating conditions, enabling more consistent classification of hazard severity. This article examines an integrated approach using a naphtha reformer stabiliser case study, demonstrating how composition influences dispersion behaviour and flam - mability risk under consistent operating and atmospheric conditions. In practice, dispersion modelling extends beyond plume visualisation to include related safety calculations such as flare radiation, relief loads, and pollutant transport. These effects are often evaluated using separate tools, leading to inconsistencies in assumptions and delays in analysis. Integrating these calculations within a unified framework ensures that source conditions derived from the process model are applied consistently across all analyses. Case study: Naphtha reformer stabiliser A case study was conducted on a naphtha reformer stabiliser system to evaluate how composition influences dispersion

H recycle

RCY-1

Recycle gas compressor

Stabilised gas

Net gas

MIX-100

E-101

Reformer

Sep gas

Fresh feed 1

Net H

Separator feed

Combined reactor euent

Separator

Unstable reformate

To stabiliser

LPG

Naphtha reformer

Unstable ref

E-100

Reformate

Stabiliser

Figure 1 Naphtha reformer process twin in Petro-SIM simulation software

PTQ Q3 2026