blog about Introduction to CFD and Flare Gas Modelling
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Introduction to CFD and Flare Gas Modelling

Posted by: Marc Laing Date: 14 May 2024

At TÜV SÜD National Engineering Laboratory, we use Computational Fluid Dynamics (CFD), a branch of fluid mechanics, to understand complex fluid behaviours. CFD can be used for a range of different industries such as aeronautical, oil and gas, power generation and renewable energy.

In this video, Marc Laing, Head of Computational Fluid Dynamics, and Dr Sandy Black, CFD Engineer, introduce you to CFD and how it can help you achieve more accurate metering of flare gas.


INTRODUCTION TO COMPUTATIONAL FLUID DYNAMICS

A common challenge faced by our clients is that they are unable to represent their problems at full scale as most test facilities are operated at lower temperatures and pressures due to safety and cost constraints. Using CFD modelling, they can better understand how their equipment is performing from a technical and business decision-making perspective.

CFD involves using numerical analysis to understand complex fluid behaviours. This normally involves building a three-dimensional model of a part or a component and analysing how a fluid or fluids interact. There are many models available in computational fluid dynamics which makes it very transferable between different industries such as aeronautical, oil and gas, power generation and renewable energy. Our CFD consultants help our clients to better understand the impact of real-world conditions by building a computerised model of the equipment or instrumentation and simulating at field conditions.

USING CFD TO IMPROVE FLARE GAS EMISSIONS ACCURACY

Flare gas emissions are tightly controlled in the UK and other parts of the world due to their detrimental impact on the environment. In order to determine the quantity of gas being flared, typically ultrasonic meters are used. But they require a set of ideal conditions to work properly, and this is rarely the reality.

When flare gas is released through a flare tip and ignited, a stable flame is the desired state of operation. However, environmental factors such as wind, humidity or temperature can impact the behaviour of this flame. For example, at high wind speeds, the flame might lean over and start attaching to the windshield. This can cause the flame to stretch and actually burn quite inefficiently (because it cools more) which results in higher quantities of methane being released to the environment than we intended.

It is difficult to measure this release because the flare tips are typically located hundreds of metres in the air. Deploying a drone or a probe is incredibly difficult and once a sample is taken its very hard to prove that the sample is representative of the overall flare.

By constructing a 3D CFD model of the system and simulating the differences between the ideal situation and an ‘as installed situation’, we can gain a better understanding of the metering error and provide correction factors to improve the accuracy of the reported flowrate.

We couple the model with detailed combustion chemistry and simulate different conditions and different scenarios as to what might happen which provides operators with an insight into exactly how efficient the combustion process is and therefore quantify the actual greenhouse gas emissions they are releasing to the environment.

Our CFD modelling approach provides an independent and impartial insight into problems involving fluid flow which helps our customers develop solutions for their business needs. We back up our CFD modelling with real-world experience and have access to a vast array of test data.

Find out more about our oil and gas flaring venting services.


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