Gas Turbine Compressor Airflow Control at Partial Loads

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Gas turbines face efficiency and emission challenges when operating over wide power ranges, particularly at low loads, due to aeromechanical stresses, increased NOx and CO emissions, and constraints from heat recovery steam generators, which affect their ability to comply with emission standards and maintain optimal performance across varying ambient conditions.

Innovation Solution

The implementation of a turndown subsystem, hibernation subsystem, and combined cycle isotherm subsystem, along with a control subsystem, which manage airflow, fuel ratios, and exhaust gas temperatures to maintain compressor airflow above minimum flow rates, avoid aeromechanical stresses, and optimize heat recovery, enabling operation at extended turndown ranges while complying with emissions limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If gas turbines operate at low loads to meet varying demand, then flexibility and adaptability improve, but efficiency deteriorates and emissions increase

Engineering Contradiction:

ImproveflexibilityVSAvoidefficiency

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The system dynamically adjusts operational parameters including compressor inlet temperature, fuel-to-air ratio, and exhaust gas temperature to maintain efficient operation across varying load conditions. By changing these parameters in real-time, the system achieves both flexibility and efficiency that would be impossible under fixed operating conditions.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If gas turbines operate at low loads, then adaptability improves, but harmful emissions (NOx and CO) increase

Engineering Contradiction:

ImproveflexibilityVSAvoidemissions

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The control system continuously monitors emissions levels and operational parameters, using feedback loops to adjust the fuel-to-air ratio and compressor inlet temperature in real-time. This feedback mechanism ensures emissions remain within regulatory limits while maintaining operational flexibility across different load conditions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

By dynamically adjusting the fuel-to-air ratio and compressor inlet temperature, the system modifies combustion parameters to reduce NOx and CO emissions during low-load operation, thereby maintaining both flexibility and environmental compliance.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If gas turbines operate at extended turndown ranges, then flexibility improves, but aeromechanical stresses on compressor increase

Engineering Contradiction:

ImproveflexibilityVSAvoidaeromechanical stresses

Core Design Contradiction:

Adaptability or versatilityVSStress or pressure

Solution Approach 1:

The system adjusts compressor inlet temperature as a key parameter when operating at extended turndown ranges. By controlling the temperature of air entering the compressor, the system reduces aeromechanical stresses on compressor blades and components, enabling flexible low-load operation without compromising structural integrity.

Inventive Principle:

Principle #35Parameter changes

4Adaptability or versatility

If heat recovery steam generator operates at low gas flow rates, then adaptability improves, but heat transfer efficiency deteriorates

Engineering Contradiction:

ImproveflexibilityVSAvoidheat transfer efficiency

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The system controls exhaust gas temperature as a critical parameter to the heat recovery steam generator, ensuring optimal heat transfer efficiency even at low gas flow rates. By maintaining appropriate temperature levels and adjusting operational parameters, the system recovers heat effectively across the full turndown range, preserving energy efficiency while achieving operational flexibility.

Inventive Principle:

Principle #35Parameter changes

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 solution extends the turndown range of gas turbines, reduces maintenance costs, improves efficiency, and allows operation at low loads while meeting emissions standards, enhancing flexibility and reducing operational complexity.

Implementation Method 1

maintain compressor airflow above minimum flow rates, avoid aeromechanical stresses

Methodology Applied

Scientific EffectAeromechanical stresses:

Implementation Method 2

optimize heat recovery, enabling operation at extended turndown ranges

Methodology Applied

Scientific EffectHeat recovery: Heat Exchanger

Data Source

PatentEP2597288B1Method and Apparatus for Optimizing the Operation of a Turbine System Under Flexible Loads

Publication Date: 2020.06.17 GENERAL ELECTRIC CO

Figure 1
Figure 2
Figure 3

AI summary

A gas turbine system (1) includes a compressor protection subsystem (5); a hibernation mode subsystem (7); and a control subsystem (1) that controls the compressor subsystem (5) and the hibernation subsystem (7). At partial loads on the turbine system (1), the compressor protection subsystem (5) maintains an air flow through a compressor (13) at an airflow coefficient for the partial load above a minimum flow rate coefficient where aeromechanical stresses occur in the compressor (13). The air fuel ratio in a combustor (15) is maintained where exhaust gas emission components from the turbine (17)are maintained below a predetermined component emission level while operating at partial loads.