Model-based emissions management systems: the path from regulatory reporting to managing energy and emissions from gas processing
Energy use and emissions of pollutants to air are tightly linked in all economic activity. The natural gas production and processing sector faces the challenge of increased pressures from all stakeholders to improve their environmental performance while remaining economically attractive for investors. Emissions reduction is one of the most serious challenges this industry is currently facing and there is a need for decision support tools to assist operating companies and governments in the identification of the most promising opportunities for improvement.
The integration of process simulation models with internet technologies can result in emissions management systems that enable rapid analysis and identification of emissions reduction opportunities. Using simulation software such as Aspen HYSYS, chemical species of interest such as benzene, methane, H2S, and others can be traced based on their thermodynamic and transport properties as the hydrocarbon resources are produced and processed at each location. The availability of this information in secure online databases can then assist in the integration and accessibility of such information to produce wider perspectives on the operations.
The potential for emissions reductions is very significant once reliable and actionable information is available. Currently available systems have been instrumental in improving emissions reporting with reasonable assumptions for aggregated representations; however, these tools (usually based on average emission factors) do not have the resolution required for opportunity identification and are likely to result in misleading conclusions. Simulation models can, however, provide the resolution to capture the opportunities and avoid incorrect assumptions. Process Ecology has developed an innovative methodology to implement these concepts with some promising results for the management of BTEX emissions from natural gas glycol dehydration. Reporting emissions from dehydration units to various stakeholders is done on a timely and consistent basis while simultaneously providing management with a set of tools to prioritize efforts in energy efficiency and emissions reductions programs.
Based on updated operating data and accurate representations of the plant configuration it is possible to evaluate emissions from combustion and venting while considering control technologies that may be in place or that could be considered to reduce emissions. Simulation models allow rapid and rigorous evaluations of what-if analysis that enable faster and improved decision making. Opportunities to reduce glycol circulation rates, addition of flash tanks, changes in feed composition, installation of condensers on the still vents are some of the alternatives that can be evaluated using this approach on a consistent basis and throughout the company’s operations.
Estimating and reporting emissions from oil & gas operations can be readily accomplished using conventional workflows, however it is time to move ahead and start managing emissions instead of simply reporting them.
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