Natural Gas Temperature Adjustment for Gas Turbine Fuel Supply

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Solution Overview

Problem

Combined cycle power plants face challenges in maintaining efficient and stable combustion due to fluctuations in natural gas composition, which existing measurement devices, such as infrared and chromatography analyzers, fail to address effectively, leading to instability and inefficiency.

Innovation Solution

A method that uses infrared analysis to quickly measure the percentage content of key hydrocarbons and calculates nitrogen content to monitor natural gas composition, calculating an energy content index (NGI) to adjust the natural gas temperature optimally using look-up tables and heat exchangers, ensuring reliable operation and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If chromatography analyzers are used to measure natural gas composition including nitrogen content, then measurement completeness is improved, but response time deteriorates (takes minutes to analyze)

Engineering Contradiction:

Improvenatural gas composition measurement completenessVSAvoidresponse time

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The measurement task is segmented into two parts: infrared analyzers measure hydrocarbon components (CH4, C2H6, C3H8, C4H10, CO2) rapidly, while nitrogen content is calculated by complement to 100% rather than measured directly. This segmentation allows fast response for the majority of components while deriving nitrogen content without the slow chromatography process.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mechanical/chromatography-based direct measurement system is replaced with an optical infrared analysis system combined with a calculation algorithm. The infrared analyzers use optical radiation to detect hydrocarbon concentrations, and the nitrogen content is obtained through computational complement (100% - sum of measured components), substituting the slow physical separation process with faster optical detection and mathematical calculation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If natural gas composition changes are not detected quickly, then combustion stability deteriorates, but using fast infrared analyzers cannot measure nitrogen content which may be present in large amounts

Engineering Contradiction:

Improvecombustion stabilityVSAvoidnitrogen content measurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The calculation algorithm acts as an intermediary that bridges the gap between infrared measurement capabilities and complete composition analysis. By calculating nitrogen content as the complement to 100% of measured hydrocarbons and CO2, the system obtains accurate nitrogen values without requiring direct nitrogen measurement, thus maintaining combustion stability through fast overall response.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Quantity of substance

If natural gas with high inert content and lower heating value is supplied, then supply pressure must be increased, but this leads to changes in gas reactivity and mixing quality

Engineering Contradiction:

Improvenatural gas supply pressureVSAvoidgas reactivity and mixing quality

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The system implements continuous feedback by rapidly measuring natural gas composition via infrared analysis, calculating the energy content index in real-time, and adjusting the pre-heating temperature accordingly. This feedback loop allows the system to respond to changes in gas composition (including inert content variations) by modifying pre-heating parameters, thereby maintaining stable combustion dynamics and consistent gas reactivity despite supply pressure adjustments.

Inventive Principle:

Principle #23Feedback

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 allows for fast and reliable adjustment of natural gas temperature in response to composition changes, maintaining optimal efficiency and stability in gas turbine engines by pre-heating the gas to a maximum allowable temperature, thereby stabilizing combustion dynamics.

Implementation Method 1

measuring by infrared analysis the natural gas percentage content of methane, ethane, propane, butane, carbon dioxide

Methodology Applied

Scientific EffectInfrared radiation absorption: Absorption (EM radiation)

Implementation Method 2

pre-heating is achieved by heating the natural gas to a maximum allowable temperature using steam or feedwater from the steam cycle

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP2770182B1Method for adjusting a natural gas temperature for a fuel supply line of a gas turbine engine and gas turbine

Publication Date: 2015.10.14 GENERAL ELECTRIC TECH GMBH

Figure 1~2

AI summary

The method for adjusting a natural gas temperature for a fuel supply line (6) of a gas turbine engine (1) comprises measuring by infrared analysis the natural gas percentage content of methane (CH4), ethane (C2H6), propane (C3H8), butane (C4H10), carbon dioxide (CO2), calculating the nitrogen (N2) percentage content as the complement to 100 of the measured percentage content of methane (CH4), ethane (C2H6), propane (C3H8), butane (C4H10), carbon dioxide (CO2), calculating an index indicative of the natural gas energy content, adjusting the natural gas temperature on the basis of the index.