Gas Turbine Start Control for Reliable Ignition

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Solution Overview

Problem

Gas turbine engines face variability in ignition conditions due to ambient temperature, fuel properties, and system repeatability, leading to unreliable start sequences and increased no-light-up trips, which can result in engine shutdown.

Innovation Solution

A control device coordinates turbine speed and fuel delivery to create a fuel/air mixture for ignition, allowing for purging of accumulated fuel after unsuccessful attempts, enabling repeated start sequences without danger and optimizing the light-up window by shifting or scaling speed and fuel/air ratio ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the turbine is accelerated quickly, then the light-up window duration is reduced, but the acceleration rate increases to compensate for fuel delivery limitations

Engineering Contradiction:

Improveturbine acceleration rateVSAvoidlight-up window duration

Core Design Contradiction:

SpeedVSDuration of action of moving object

Solution Approach 1:

The patent applies dynamics by making the turbine acceleration rate variable rather than constant. The control system adjusts the acceleration rate in real-time based on the actual turbine speed and fuel delivery rate, allowing the system to optimize the light-up window duration dynamically. This resolves the contradiction by enabling quick acceleration when fuel delivery is sufficient while extending the light-up window when fuel accumulation needs more time.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of acceleration rate from a fixed value to a variable parameter that depends on turbine speed and fuel delivery conditions. By continuously adjusting this parameter, the system can adapt the light-up window duration to match the actual fuel accumulation rate, thereby resolving the trade-off between acceleration speed and window duration.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the light-up window is extended to cover variations in optimum window, then the number of ignition opportunities increases, but the fuel accumulation rate may become dangerous

Engineering Contradiction:

Improveignition success probabilityVSAvoidexcess fuel accumulation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements feedback control by continuously monitoring the actual turbine speed and comparing it with the expected speed profile. Based on this feedback, the control system adjusts the fuel delivery rate and acceleration profile in real-time. This ensures the light-up window is extended only as much as safely permitted by the actual fuel accumulation rate, thereby increasing ignition reliability without creating dangerous fuel excess.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the light-up window duration based on real-time conditions rather than using a fixed extended window. The control algorithm modifies the window length adaptively, extending it when conditions permit and limiting it when fuel accumulation becomes dangerous, thus resolving the contradiction between reliability and safety.

Inventive Principle:

Principle #15Dynamics

3Duration of action of moving object

If the turbine acceleration rate is reduced to increase light-up window, then fuel delivery time is sufficient, but the number of ignition opportunities decreases

Engineering Contradiction:

Improvelight-up window durationVSAvoidignition opportunities per second

Core Design Contradiction:

Duration of action of moving objectVSProductivity

Solution Approach 1:

The patent makes both the acceleration rate and light-up window duration dynamic parameters that adjust together based on fuel delivery capabilities. This coordinated dynamic adjustment ensures that the light-up window is extended only when fuel delivery can keep pace, maintaining the product of window duration and ignition frequency (total ignition opportunities) while ensuring sufficient fuel accumulation time.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes multiple parameters simultaneously - both the acceleration rate and the light-up window duration are adjusted as coupled parameters. This allows the maintenance of an optimal relationship between window length and ignition frequency, ensuring sufficient fuel delivery time without excessively reducing ignition opportunities.

Inventive Principle:

Principle #35Parameter changes

4Reliability

If multiple start sequences are repeated after unsuccessful ignition, then the probability of successful ignition increases, but the risk of engine damage from accumulated fuel increases

Engineering Contradiction:

Improveignition success probabilityVSAvoidexcess fuel in combustion system

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the harmful accumulated fuel from the combustion system between start sequence attempts by implementing a purging operation. This removal of excess fuel eliminates the danger associated with repeated start attempts, allowing multiple sequences to be executed safely to increase ignition probability without risking engine damage from fuel accumulation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs a preliminary purging action before each subsequent start sequence attempt after an unsuccessful ignition. This preliminary removal of accumulated fuel prepares the system for the next attempt, ensuring that each sequence starts with a safe fuel level, thereby enabling multiple repetitions to increase success probability without danger.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method reduces no-light-up trips by allowing quick repetition of start sequences, increasing the number of ignition opportunities within the optimal window, thereby enhancing the probability of successful ignition and preventing engine damage from excess fuel.

Implementation Method 1

turbine speed and fuel delivery are coordinated so as to provide a fuel/air mixture at an ignition device allowing a successful ignition

Methodology Applied

Scientific EffectFuel/air mixture formation:

Implementation Method 2

a number of ignition opportunities appears, the actual number of which depends on the number of sparks that can be delivered per second by the igniter

Methodology Applied

Scientific EffectIgnition/Combustion: Combustion

Implementation Method 3

the speed of the gas turbine, which is during start driven by an auxiliary motor

Methodology Applied

Scientific EffectElectromagnetic motor conversion:

Implementation Method 4

the gas turbine engine is purged and, after the purging, the start sequence is repeated

Methodology Applied

Scientific EffectFuel purging:

Data Source

PatentEP2021601B1Gas turbine engine starting method and control device

Publication Date: 2016.06.15 SIEMENS AG

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AI summary

A method of starting a gas turbine engine (1) by use of a start sequence (105) is provided. Turbine speed and fuel delivery are coordinated so as to provide a fuel/air mixture at an ignition device allowing a successful ignition. If a successful ignition has not occurred by end of the start sequence (105) the gas turbine engine is purged (111) and the start sequence (105) is repeated after the purging of the gas turbine engine.