Process Digital Twin Reduces Combustion Emissions While Lifting Profits

Mar 10, 2022   Written by Rodolfo Tellez-Schmill, Ph.D. and Ghoncheh Rasouli, Ph.D.

Fossil fuels have been in use since the 19th century. Because these widely used materials produce undesirable emissions, they are heavily scrutinized. To minimize the environmental impact of carbon emissions, companies must take action. They need to employ methods that balance environmental needs with technical feasibility to meet the ever-increasing regulatory compliance requirements and stakeholders' profit expectations.

Regulations Squeeze ROI

To satisfy legal's environmental standards and stakeholder's profit expectations, companies must create eco-friendly designs that accommodate all liquid or gas fuel, all by-products, any combustion asset, and any burner design while returning a profit. Thus, companies must update standard operating procedures and implement ways to curb emissions. These efforts include installing expensive and often duplicate monitoring devices such as setting conservative design limits, mounting monitors below the chimney crowns, installing remote community monitors to measure emissions in all wind directions, and replacing ‘dirtier’ fuel oils with 'cleaner' alternatives such as natural gas. Thus, companies are working harder to cover these additional costs to ensure the operational variability and combustion by-products adhere to legal and self-imposed boundaries.

Typical causes of operational variability include the following:

  • Inconsistent fuel quality results in variable fuel composition.
  • Faulty technology or weather-related issues lead to unreliable data collection.
  • Stronger regulations facing all industries lead to restricted outlets or increased flow of low-quality fuel, storage constraints, blending specifications or combustion limitations.

Combustion by-products include the following:

  • Carbon dioxide (CO2) emissions. An EPA study shows that CO2 is the most important gas to target for efficient climate control as it accounts for about 80% of greenhouse gases in the atmosphere.
  • Carbon monoxide (CO) emissions depend on combustion efficiency.
  • Sulfur oxides (SOx) is produced from sulfur in the fuel. For example, SOx emissions come mainly from the presence of hydrogen sulfide in fuel gas and the presence of sulfur odorants in natural gas.
  • Nitrogen oxides (NOx) forms from thermal NOx, fuel NOx, and prompt NOx.
  • Volatile organic compounds (VOC). The rate of VOC emissions depends on combustion efficiency. Minimizing VOC emissions depends on combustion practices that promote higher combustion temperatures, longer residence time at those temperatures, and turbulent mixing of fuel and combustion air.
  • Particulate matter (PM). The measurement of small solid particles and liquid droplets released into the air.

Software Satisfies Opposing Needs

Operators can use digital twins designed for specific equipment or an entire processing facility to implement an easy and scalable solution. Digital twins offer automated reporting, 24/7 data connectivity, analysis and adjustment capabilities to optimize environmental performance. Because stakeholders also expect optimal business performance, significant iteration time and data manipulation between the different systems may be necessary. Finally, the digital twin must connect to the production management systems and serve as inputs for supply chain optimization to balance the process limitations with business performance.

The Emissions Utility is a new fully integrated tool within Petro-SIM® v7.2. It calculates and optimizes business processes using real-time combustion data and efficiencies. Then, the Emissions Utility tool automatically delivers real-time data about combustion performance, data reliability, operation profitability, and regulatory compliance.

To assess the reliability of the information, Petro-SIM’s data reconciliation feature compares raw data with historical data located in the information management system. This data assessment includes raw mass balancing of sulfur and nitrogen as well.

In addition, the Petro-SIM process simulator validates utility performance by comparing reconciled data with the process simulation results. The Emissions Utility report calculates CO, NOx, PM, and VOC emissions using emissions factors and data sources such as EPA’s AP-42 bulletin. These emission factors represent the maximum amount of a specific chemical species such as CO, NOx, PM and VOC by fuel volume in either gas or liquid form. Once the operator enters these factors, the Petro-SIM digital twin calculates the respective flowrate using the following assumptions:

  • CO2 and SOx are calculated assuming all C and S in the fuel reacts with combustion air.
  • SOx emissions are calculated by a simple mass balance, and its value can be compared against maximum legal limits.

The Bottom Line

Companies must know the capital costs and production conditions in order to select the right power source that expedites and optimizes the design task.

Once the selected compressor drivers are operating, the identical process simulation model can estimate the driver's daily and cumulative emissions as an automated digital twin. The digital twin will work 24/7 to cover the entire asset, including all of the equipment with quick deployment and easy maintenance.

The inclusion of the Emission Utility report within Petro-SIM process simulator allows operators the ability to compare results against instant and time-dependent regulatory compliance standards. Then, the combustion design and operations can be adjusted accordingly. This information enables the company to optimize business performance in the ever changing environments and legal constraints.

Download the 5-page report to learn how the Petro-SIM process simulator examined different emissions generated by three different compressor drivers on a floating, production, storage and offloading vessel.