A New Approach for Managing Process Risks and the Effective Communication of Those in a 3D Virtual Environment

Consequences and risks from unwanted process releases have been quantified for many years using a variety of tools from quick and simple 2D analytical and semi-empirical techniques to advanced 3D simulation methods based on Computational Fluid Dynamics (CFD). A 2D analytical modelling approach does have benefits including calculation speed and ease of use but it is accepted as not being accurate in and very limited when assessing the effects from complex physics such as explosion, fire or dense gas dispersion. The limitations of the semi-empirical tools with regards to the consequence predictions have not however prevented this simplified approach from being widely used to conduct Quantitative Risk Analysis (QRA) studies. One of the drawbacks is that more and more detailed inputs are required to counteract the empirical approximations used in the calculations. These QRA studies have become very complicated, time consuming and difficult to understand. Besides the specific outputs are often difficult to communicate out to non-safety experts.

With a 3D CFD modelling approach, an analysis requires more computer time to run typically but less specific and constraining simplifying inputs by the analyst as the physics are actually modelled instead of being approximated. It makes use of the 3D geometry data, which is also key to producing meaningful results. Any 3D analysis will produce far more comprehensive and accurate results, useful in removing uncertainty. Getting accurate results is crucial to the decision making process when it comes to safety matters, design issues or modification of existing facilities or process. However another additional benefit, often overlooked, is the powerful visualization capabilities from 3D CFD tool such as FLACS®. The realistic outputs makes it easier for engineers to understand the impacts of different options and control measures, which can be quantified and justified. Engineers can reliably evaluate the performance of control measures using the 3D computer model without the time, expense, and disruption required to make actual changes onsite.

It has been very common to post-process CFD results to generate risk based predictions thereby avoiding unrealistic and impractical design solutions based on worst case scenarios. This practice is standard for projects in the North Sea (applying Norsok Z-13) using FLACS® as the tool of choice for CFD consequence prediction. Many companies have developed their own probabilistic approach using FLACS® and implemented it through the scripting facility available in the standard FLACS® software.

There are many excellent applications of why 3D CFD modelling has been be selected ahead of a 2D semi-empirical approach such as: smoke and gas dispersion prediction, validation of hypothesis on accident investigation, location of gas detection, optimization of separation between equipment and also facilities, specification of passive fire protection, location of safety equipment or HSECEs, etc.

Gexcon, the developer of FLACS®, recognised the need for a standard risk tool based on and integrated with the FLACS® pre-processor, solver and postprocessor to optimize the setup, simulation runs and interpretations of the results. As a result the FLACS-Risk add-on has been developed to address the needs of engineers who are seeking to calculate accurately the baseline risk picture for a given design option and quantify the impact of mitigations. FLACS-Risk can not only produce exceedance curves at key locations based on multiple scenarios but it allows users to get much more insight in the anticipated risk through extensive 2D and 3D risk visualization. Being able to setup multiple runs quickly, solve in parallel, post-process the results efficiently and compare the impact of design options in a very graphical and intuitive interface is key to speed up the evaluation of risk reduction measures and thus improve the design of assets.

FLACS-Risk benefits from the powerful post-processing capabilities of FLACS permitting detailed visualization of multiple results in three dimensions.

Predicting accurately and improving the understanding of the process risks are key Gexcon objectives with FLACS-Risk but Gexcon has also developed an environment where those risks can be communicated effectively to a much wider audience, following any analysis. Gexcon has developed an interactive 3D Virtual Environment (VR) where the FLACS® analysis results can be coupled and displayed in a surrounding matching the real physical plant facilities. This 3D hosting environment can be used for a wide range of applications from reviewing risk analysis work as part of a project to training staff on site e.g. emergency preparedness and site evacuation.

Gexcon will present both the latest developments of the FLACS-Risk tool for risk predictions and show an example of an integration of FLACS results into a VR application for an onshore facility.