Model-Based Safety

State-of-the-art tools for optimal flare system design

Conventional methods for calculating relief loads are generally conservative and can lead to overly sized relief and flare-system designs.

API Standard 521 (Clause 5.22)

PSP brings a new set of tools to design of flare systems and related blowdown analysis.

PSE's Advanced Model Library for Pressure Relief Systems (AML:PRS) uses the power of gPROMs to provide a whole range of functionality never before available to process engineers:

both steady-state and dynamic analysis from the same models
the ability to incorporate all relevant parts of the system or process in the flare system design
mix-and-match between standard and distributed models to allow, for example, detailed 3-D wall temperature modelling while taking into account upstream and downstrem effects
advanced optimisation techniques to calculate optimal pipe sizes etc. directly, removing the need for trial-and-error simulation.
and many more.

All of this functionality is provided within a state-of-the-art graphical flowsheeting environment, with rapid and robust solution of the underlying numerics.

Benefits

PSE's approach brings many benefits to flare system design, overcoming the significant limitations of current approaches. For example:

gPROMS provides an integrated modelling environment that can incorporate all relevant equipment and phenomena being investigated, leading to better flare and blowdown system designs.
Many many different types of analysis can be performed using the same model, allowing the design space to be explored fully and cost-effectively.
Different levels of model within the same framework allow detailed analysis of certain areas within the context of the entire pressure-flow network, meaning that areas of concern – for example low-temperature areas where brittle fracture is a concern – can be investigated fully.
gPROMS's inherent dynamic capabilities and high-fidelity models mean that design can be based on realistic scenario analysis, reducing costly overdesign while maintaining safety.
gPROMS's custom modelling capabilities mean that it is possible to model the exact physical configuration of the system without always having to rely on "off-the-shelf" solutions.
Distributed modelling allows high-accuracy analysis of key variables such as peak pressures and vessel wall temperatures within a flowsheeting context.
Full dynamic modelling means that the effect of sequential events can be modelled – for example the potential for hydrate formation when a warm wet stream follows a cold dry blowdown event.

Example

The following example illustrates the type of problem that can be addressed using the AML:PRS. Of course the real situation can be many times more complex.

Key

process behaviour
back-pressure constraints
optimised pipe sizes
dynamic modelling
distributed pipe for detailed wall modelling
dynamics of PRV
dynamics of metal temperature

PSE provides …

Dynamic simulation provides an alternative method to better define the relief load and improves the understanding of what happens during relief.

API Standard 521 (Clause 5.22)

PSE provides a combination of software tools and services:

The gPROMS Advanced Process Modelling environment, which provides all the essential capabilities – simulation and optimisation within a flowsheeting environment – identified above.

The gPROMS Advanced Model Library for Pressure Relief Systems (AML:PRS), a set of advanced models that executes within the gPROMS framework.

PSE's expert ModelCare configuration and consulting services.

Who does the work?

Many EPCs have teams of process and safety engineers capable of flare system design using traditional steady-state modelling tools.

However when it comes to dynamic (transient) design and optimisation, skills are thinner on the ground. With this in mind of this, PSE provides:

Tools and training. If you have personnel in your teams with suitable skill levels, we can train them in the effective application of the AML:PRS to familiarise them with the basic principles of operation and also to ensure that they are familiar with the full extent of its capabilities.
Typically this involves:
- one day's general gPROMS training
- two days of hands-on AML:PRS application
- up to two days' subsequent call-off assistance as required. This is particularly useful for assistng progress and ensuring success on initial projects.
On-the-job training and coaching. Supplied as part of a ModelCare agreement, this is a very effective way of delivering a quality-assured project rapidly while having your team members trained by working alongside modelling experts.
Project services. Fast and effective, PSE's Consulting service is geared to delivering rapid results, working as part of your team or within our offices as appropriate.