Tackling a Critical Turbine Performance Issue

Gas turbine operators face constant pressure to maintain reliability while minimizing downtime and extending equipment life. One of the most significant operational challenges is exhaust gas temperature (EGT) spread—a key indicator of combustion balance and turbine health.

Excessive EGT spread can trigger alarms or automatic shutdowns and significantly reduce the lifespan of turbine components.

In this case study, Fern Engineering was tasked with analyzing the fuel distribution system for a refinery’s gas turbine fleet to identify the root causes of temperature variation and evaluate potential solutions.

What You’ll Learn

Inside this engineering case study, you’ll discover how Fern Engineering:

• Investigated the root causes of gas turbine exhaust temperature spread
• Modeled complex fuel piping systems feeding turbine combustion chambers
• Evaluated how piping geometry and component tolerances affect fuel flow
• Simulated multiple operating scenarios to understand performance impacts
• Used engineering modeling to predict and reduce turbine performance risks

The Engineering Challenge

Most gas turbines distribute fuel to multiple combustion chambers through a network of fuel nozzles arranged around the turbine perimeter.

Even small variations in fuel flow to individual nozzles can create uneven combustion conditions, increasing the exhaust gas temperature spread.

Fuel supply piping networks are often complex systems containing:

• Numerous bends and fittings

• Different tubing lengths and diameters

• Orifices and restrictions

• Manufacturing tolerances that influence flow distribution

These variables can make accurate analysis extremely difficult using traditional hand calculations alone.

The Solution: Detailed System Modeling

To address the challenge, Fern Engineering built a detailed system model using Datacor’s Arrow software.

The model replicated the fuel piping, manifolds, and nozzle branches of a Rolls-Royce Avon gas turbine, including key piping elements such as bends, fittings, and area changes.

Engineers constructed a model containing 91 pipes and 92 junctions to simulate the full fuel distribution network and evaluate how variations in piping geometry and component tolerances influenced fuel delivery to each nozzle.

Multiple simulation scenarios were run to estimate how these variations affected turbine performance and EGT spread.

Model Validation and Results

Before building the full turbine model, the team validated the software by comparing predicted flow results with test-rig measurements of sonic flow and orifice pressure.

The simulation results closely matched the physical test data, providing engineers confidence in the model’s accuracy and predictive capability.

This modeling approach allowed the engineering team to analyze complex flow networks that would have been impractical to evaluate using manual methods.

Who Should Read This Case Study

This resource is designed for professionals responsible for turbine performance and power plant reliability, including:

• Gas turbine engineers

• Power plant operations managers

• EPC and consulting engineers

• Reliability and maintenance engineers

• Combustion and fuel system specialists

Download the Case Study

Learn how engineering teams used advanced modeling to analyze turbine fuel systems, reduce exhaust temperature variation, and improve operational reliability.

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