Industrial Methane Measurement Conference - Abstract

Abstract Information :

Flaring and venting are two of the main causes of greenhouse gas emissions, however, there both critical safety components of any oil and gas producing facility, allowing for the safe disposal of unplanned or excess gases. Flare and vent gas is comprised of a mix of methane and other hydrocarbons which can be vented; or flared by converting the gas to carbon dioxide through combustion.rnMethane is understood to have a shorter atmospheric lifetime but a much higher global warming potential than carbon dioxide and therefore, paradoxically, flaring and venting of any methane emissions that would otherwise reach the atmosphere reduces the environmental impact of hydrocarbon production.rnAccurate flare and vent gas metering is important to report the correct quantities of methane flowing to the vents or flares. This is important to meet regulatory requirements, but to also ensure that the flare systems are sufficiently purged to avoid flashback or burn-back issues.rnTo reduce emissions, flaring and venting must be kept to a minimum. Under flaring and venting conditions, an incorrect meter reading could result in higher quantities of greenhouse gases being released into the atmosphere or a serious safety concern such as the flare system operating below the minimum purge requirement.rnOperating the flare systems at such low levels maybe out-with the design specification of the flare system, this can result in insufficient purge of the flare gas to overcome the meteorological conditions, potential combustion inside the flare tip resulting in potential damage to the flare tip and likelihood of flashback to the flare knockout drum.rnTo address these issues, TV SD National Engineering Laboratory NEL have been working with bp to perform Computational fluid Dynamics CFD modelling on their global production flare and vent systems, with the aim of understanding, verifying and ultimately reducing bps overall methane intensity in a safe and efficient manner from all of bps global upstream production assets. This is part of bps Aim 4 plans in support of delivering its net zero ambition.rnThe CFD simulations are focussed on two main areas:rnultrasonic and thermal mass flare and vent meter correctionrnCombustion and destruction removal efficiency analysis of the flare tip.rnWhich are both used to evaluate how efficiently the flare system is operating and how efficient the flare systems are in reducing the greenhouse gases are being emitted.rnThe ultrasonic and thermal mass flare and vent meter correction is focussed on ensuring that even in a non-ideal installation the flow meter provides accurate flare and vent gas flowrates. This is done by calculating the flowrate the flare vent meter would measure in situ and then providing an appropriate k-factor correction factor to correct the output of the flare vent meter across its operating range. rnFor the combustion and destruction removal efficiency analysis, a detailed combustion mechanism is modelled using CFD. The model accounts for different external influences such as humidity, wind speed, wind direction, gas composition and many more. The analysis is used to determine the combustion efficiency CE and the methane destruction amp; removal efficiency DRE, but also to evaluate flare tip safety issues such as flashback potential and areas likely to thermal fatigue. These two parameters are key to determining how efficiently the flare system is operating and how efficient the flare systems are in reducing the greenhouse gases are being emitted.rnThis paper demonstrates this approach on several of bps assets as a valuable method to increase flaring and venting knowledge of existing assets and help significantly reduce the impact on the environment from flaring and venting.rn