Passive Combustion Bypass Valve for Gas Turbine Emissions
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Solution Overview
Problem
Gas turbines face challenges in maintaining emissions compliance during load reductions, as combustion systems struggle to control NOx and CO emissions at reduced power output levels, requiring efficient adjustment of air-fuel ratios and combustion temperatures.
Innovation Solution
A combustion bypass passive valve system is introduced, featuring temperature- and pressure-sensitive passive bypass valves that selectively extract a portion of compressor discharge air to adjust combustor temperatures, ensuring emissions compliance and efficient operation across varying load conditions without the need for control connections or sensor signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If compressor discharge air is bypassed around combustors to maintain acceptable fuel-to-air ratios at reduced load, then emissions compliance is improved, but combustion temperature control becomes more complex
Solution Approach 1:
The passive bypass valve utilizes the existing temperature and pressure conditions within the combustor system to automatically regulate air bypass. The valve contains a temperature-sensitive element that expands or contracts in response to combustor temperature changes, and a pressure-sensitive diaphragm that responds to pressure differential changes, enabling the valve to self-regulate without external control signals or sensors
Solution Approach 2:
The passive bypass valve acts as an intermediary mechanism between the compressor discharge air source and the combustor chamber. It mediates the air flow by selectively bypassing portions of the compressed air around the combustor based on real-time temperature and pressure conditions, thereby indirectly controlling the fuel-to-air ratio and combustion temperature
2Device complexity
If passive bypass valves are used to extract compressor discharge air, then control connections and sensor signals are eliminated, but valve actuation reliability depends on temperature and pressure sensitivity
Solution Approach 1:
The invention replaces electronic control systems and sensor signals with a purely mechanical passive valve actuation mechanism. The valve uses a temperature-sensitive element that physically expands or contracts with temperature changes, and a pressure-sensitive diaphragm that moves in response to pressure differential changes, converting thermal and pressure energy directly into mechanical valve motion without any electronic intermediaries
Solution Approach 2:
The passive bypass valve exploits changes in physical parameters (temperature and pressure) to control valve actuation. As combustor temperature increases, the temperature-sensitive element expands, and as pressure differential changes occur during load transitions, the pressure-sensitive diaphragm moves, causing the valve to automatically adjust its opening degree in response to these parameter changes
3Object-generated harmful factors
If compressor discharge air is bypassed to maintain fuel-to-air ratios, then NOx and CO emissions are controlled, but combustion efficiency may be reduced
Solution Approach 1:
The passive bypass valve provides dynamic adjustment of air bypass in real-time response to changing combustor conditions. Unlike fixed bypass arrangements, the valve automatically opens or closes based on instantaneous temperature and pressure measurements, enabling the system to maintain optimal fuel-to-air ratios across varying load conditions and thereby preserve combustion efficiency while controlling emissions
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
The system effectively manages emissions by allowing air bypass at low-load conditions, maintaining high combustion temperatures to minimize NOx emissions while preventing excessive CO emissions, thus ensuring operational stability and efficiency across part-load conditions.
Implementation Method 1
a temperature-sensitive element, such as a bellows, that expands or contracts in response to changes in combustor temperature
Implementation Method 2
a pressure-sensitive diaphragm that responds to changes in pressure differential between the compressor discharge and the combustor
Data Source
AI summary
A combustor for a gas turbine, including: a combustor chamber; a casing enclosing the combustor chamber and defining an area therebetween for passing compressor discharge air into the combustor chamber for use in combustion; and at least one passive bypass valve for selectively extracting a portion of the compressor discharge air from the area between the combustor chamber and the casing to adjust a temperature in the combustor.