Turbine Bypass Study

TRAX offers studies to help clients troubleshoot issues around specific equipment. In the instance showcased here, we helped an EPC firm validate the design for a turbine bypass system, boiler safety valves, and associated Balance of Plant (BOP) equipment by conducting a dynamic study with the ProTRAX software.

Learn more about ProTRAX software

TRAX can also provide engineering studies on dynamic plant process, such as furnace draft analyses, heat recovery steam generator (HRSG) cycling, and the integration of new or modified equipment.


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ProTRAX Modules: each module comes with full documentation, detailing the inputs, outputs, and processes contained within each component

TRAX software includes over 300 standard process modules representing a variety of equipment. Using existing process modules, we built a model for two identical circulating fluidized bed (CFB) boilers. The model included boiler safety valves at the drum, superheater, and reheater, while the BOP system included high pressure (HP), intermediate pressure (IP), and low pressure (LP) turbines, condenser, deaerator, feedwater heaters, condensate extraction pumps, boiler feed booster pumps, and boiler feed pumps. TRAX also modeled the relevant HP and IP/LP turbine bypass system and the control system modeling for this equipment.


Once a model accurately represents the physical equipment, TRAX can test severe scenarios to give the client new data. With the new CFB boiler models, TRAX tested scenarios to help EPC determine their best course of action. With plant operating at 102%, TRAX initiated a load rejection, which immediately closed all the HP turbine stop valves and the reheat stop valves. During this transient, the boiler load ramped down from 102% to 40% at a rate of 7% per minute.


TRAX confirmed for the client that none of the safety valves opened during the load rejection event.  TRAX also monitored conditions at the boiler feed pumps, boiler feed booster pumps, and condensate extraction pumps — none of these pumps experienced cavitation during the load rejection transient.  These pumps had sufficient capacity to keep levels in the steam drum, deaerator, and condenser at (or near) setpoint throughout the load rejection transient.

TRAX proved the bypass system was properly designed to handle the worst-case load rejection scenario without lifting any of the boiler safety valves, validating the EPC's design of the turbine bypass system.

To learn more about TRAX studies and the types of issues we specialize in, visit the Engineering section of our website.

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Turbine Bypass Study

August 17, 2022

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.