Sequential Combustor Fuel Flow Control for Power Jump Mitigation

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Solution Overview

Problem

Gas turbine power plants with sequential combustor assemblies experience uncontrolled power jumps during activation or deactivation of combustion stages, which can damage components, compromise emission compliance, and affect frequency response capabilities.

Innovation Solution

A method for operating a gas turbine power plant that involves varying the fuel flow rate to the first combustor while activating or deactivating the second combustor, keeping the power output within a defined compensation range to mitigate power jumps, by using a control device that adjusts fuel flow based on temperature measurements downstream of the first combustor and upstream of the second combustor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the second combustor is activated or deactivated by supplying minimum fuel flow rate, then the combustion stage can be switched on/off, but an uncontrolled power jump of several MW occurs

Engineering Contradiction:

Improvecombustion stage activationVSAvoidpower output stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The control device adjusts the fuel flow rate to the first combustor in advance before activating or deactivating the second combustor. By pre-modulating the first combustor's fuel flow, the system prepares to compensate for the upcoming power change, preventing sudden power jumps when the second combustor is switched on or off.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control device continuously monitors the power output and fuel flow rates, using this feedback to dynamically adjust the first combustor's fuel flow rate. This closed-loop control ensures that the power output remains within the compensation range by making real-time corrections based on actual system behavior during combustor activation/deactivation events.

Inventive Principle:

Principle #23Feedback

2Reliability

If the fuel flow rate to the first combustor is varied to compensate for power jumps, then power output stability is improved, but the control system complexity increases

Engineering Contradiction:

Improvepower output stabilityVSAvoidcontrol system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control device performs multiple functions: it normally controls fuel flow to both combustors for power generation, and additionally serves as the compensation mechanism for power jumps during second combustor activation/deactivation. By making the control device multi-functional, the patent avoids adding separate hardware while achieving power stability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If sequential combustor assemblies are used to increase operational flexibility, then emission compliance and operational range are improved, but uncontrolled power jumps damage components and reduce reliability

Engineering Contradiction:

Improveoperational flexibilityVSAvoidpower jump damage

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The control device sets up a cushioning mechanism by pre-adjusting the first combustor's fuel flow rate before the second combustor is activated or deactivated. This beforehand cushioning action compensates for the harmful power jumps, protecting components like the rotor and combustor assembly from thermal and mechanical stress caused by sudden power changes.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 approach reduces power output jumps, enhances the flexibility and reliability of the gas turbine plant, improves the lifetime of critical components, and maintains emissions within regulatory limits.

Implementation Method 1

supplying a first fuel flow rate to the first combustor and subsequently igniting or switching off at least one combustion stage of the second combustor

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 2

temperature measurements downstream of the first combustor and upstream of the second combustor

Methodology Applied

Scientific EffectTemperature measurement:

Data Source

PatentEP3683426B1Method for operating a gas turbine power plant and gas turbine power plant

Publication Date: 2023.05.03 ANSALDO ENERGIA SWITZERLAND AG

Figure 1
Figure 2a~2c
Figure 3a~3c

AI summary

A method for operating a gas turbine power plant; the gas turbine power plant (1) comprising a compressor (2), a sequential combustor assembly (3) and a turbine (4) arranged downstream the combustor assembly (3); the sequential combustor assembly (3) comprises a first combustor (10) and a second combustor (12) arranged downstream the first combustor (10); wherein between the first combustor (10) and the second combustor (12) a mixer (9) or a high pressure turbine is arranged; wherein the second combustor (12) comprises at least one combustion stage (7b, 7c); the method comprising: - operating the gas turbine power plant (1) at partial load; - during the partial load operation, supplying a first fuel flow rate to the first combustor (10) and subsequently igniting or switching off at least one combustion stage (7b, 7c) of the second combustor (12); - varying the first fuel flow rate when the combustion stage (7b; 7c) of the second combustor (12) is ignited or switched off so as to keep the variation of the power output of the gas turbine power plant (1) comprised in a compensation range; the compensation range being comprised between zero and an upper limit defined by the operative limits of the sequential combustor assembly (3) .