Dual Fuel Conversion Study

Dual Fuel Conversion Study

TRAX has delivered a dual-fuel conversion project, using digital twin technology to closely examine power plant subsystems. One part of the project was designed to closely examine the flue gas flow as part of the conversion project. The second part of the project included a full-plant training simulator capturing all major plant subsystems.

The utility has two coal-fired units — one older 530 MW unit commissioned in the 1970s and a newer 825 MW unit commissioned in 2012. To take advantage of lower fuel costs and reduced emissions, the utility decided to equip both units for co-firing with natural gas — one firing up to 40% on gas and the other firing up to 100% on gas.

The utility contracted TRAX to examine the impact of adding natural gas valves and burners, as well as modification of the controls to accommodate gas firing. The primary goals were to provide a recommendation for gas valve stroke times, as well as to predict the behavior of the unit in its future configuration and to determine if any draft system pressures exceeded set limits during severe transient events. TRAX recommended controls mitigations that would help the utility achieve those goals and ensure compliance with NFPA recommendations.

The changes described in the detailed plant examination were also rolled into the overall plant modeling. Each unit simulator was updated with the pre-commissioned controls, including all the new gas and co-firing controls. The digital twin was used to troubleshoot the new controls prior to site installation, shortening the site commissioning time and improving the controls strategy. Finally, TRAX conducted training with the pre-commissioned controls prior to site installation so operators were prepared for gas firing and co-firing operation prior to plant startup.

Dual Fuel Conversion Study

April 8, 2020

TRAX has delivered a carbon capture simulator for a 150 MW coal-fired unit that models the capture of the full flue gas stream.  The system provides both CO2 and SO2 capture, delivering the captured CO2 to a pipeline for industrial use and underground storage.

TRAX Carbon Capture Model Included:

—CO2 and SO2 capture
—Sulfuric acid plant
—CO2 and SO2 amines filtration and purification
—CO2 compression
—CO2 pipeline and cavern

As shown below, TRAX built a modular simulation replicating the plant layout using our software, ProTRAX.  ProTRAX contains a full suite of modules specific to carbon capture functions and can model a wide variety of processes.  TRAX also virtually replicated the user interface that appears in the plant.  

Model Scope

ProTRAX is a modular software that can easily integrate multiple models for larger projects.


TRAX organizes the simulator model to match the layout of the site or process being modeled.


Depending on the Absorber module selected, the module can remove water vapor (H2O), carbon dioxide (CO2), and/or sulfur dioxide (SO2) from an air or gas stream.


Each ProTRAX module is backed by comprehensive documentation, including a general description, module inputs and outputs, and mathematical formulae.


The training value of a simulator occurs in the interactive screens that replicate the site equipment.

Upon initial delivery, the TRAX simulator was used to debug control logic and processes prior to site installation and to provide operations training prior to plant startup.  There was a clear need to begin training operators as early as possible since they had multiple unfamiliar systems to learn.

Thanks to the ProTRAX simulator, our customer gained considerable insight into control functionality and system interactions, resulting in modification to some control logic and correction of simple errors.  TRAX was able to assist with controls tuning, and helped in development of initial plant Operating Procedures.

The latest upgrade brings the model into alignment with the as-built plant condition by updating and tuning the simulator models to match the current plant dynamics. In addition, TRAX has updated the simulator controls and HMI graphics to the as-built state.  Keeping the simulator aligned with the current plant condition is critical to maintaining a positive training value, and is of paramount importance to the customer.