Gas Turbine Combustor Oxygen Concentration Control
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Solution Overview
Problem
In gas turbine combustors, initial startup conditions often result in unstable combustion due to low turbulent burning velocity and the presence of inert gases like carbon dioxide, leading to flame extinction, especially when oxygen flow rates are minimal and carbon dioxide is introduced as a cooling and dilution medium.
Innovation Solution
A method involving a controller-regulated flow of fuel and oxidant to maintain a predetermined oxygen concentration in the circulating gas, adjusting equivalence ratios to ensure stable combustion conditions by introducing a mixed gas containing oxygen before ignition and maintaining it throughout the startup phase, ensuring sufficient oxygen supply to the flames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If carbon dioxide is introduced as a cooling and dilution medium, then cooling effect is improved, but combustion stability deteriorates
Solution Approach 1:
The patent applies preliminary action by introducing a mixed gas containing oxygen into the combustor before ignition occurs. This pre-filling of oxygen-rich gas creates a reservoir of oxidant that compensates for the flame-stabilizing effect being reduced by carbon dioxide introduction. The oxygen is introduced in advance through the carbon dioxide supply system, ensuring combustion stability is maintained despite the presence of inert gas.
2Productivity
If oxygen flow rate is set to minimum for complete combustion, then efficiency is improved, but combustion stability deteriorates
Solution Approach 1:
The patent introduces oxygen into the combustor before ignition occurs, creating a pre-filled oxygen reservoir. This preliminary introduction of oxygen compensates for the minimal oxygen flow rate used during combustion, ensuring sufficient oxidant is available to maintain stable flames even when the oxygen supply rate is optimized for efficiency rather than stability.
3Temperature
If carbon dioxide circulation is initiated before combustion, then cooling function is improved, but flame extinction risk increases
Solution Approach 1:
The patent introduces a mixed gas containing oxygen into the combustor before ignition occurs. This preliminary oxygen introduction creates a protective oxygen-rich environment that counteracts the flame-extinguishing effect of carbon dioxide circulation. The oxygen is introduced through the carbon dioxide supply system in advance, ensuring flame stability is maintained despite early carbon dioxide circulation for cooling.
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 stabilizes combustion during the initial turbine startup phase by maintaining a stable flame and preventing extinction, even at low turbulent burning velocities, by ensuring a consistent oxygen concentration in the circulating gas, thus enabling efficient operation.
Implementation Method 1
The circulated carbon dioxide is heated by exchanging heat with the combustion gas discharged from the turbine through a regenerative heat exchanger, for example.
Implementation Method 2
The combustor liner 330 is constituted by a cylindrical member in which a fuel and an oxidant are combusted.
Data Source
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AI summary
In a method for operating a combustor 10 of an embodiment, before ignition in the combustor 10, a mixed gas containing oxygen is circulated through the combustor 10 as a circulating gas. Then, in an operating time from the time of ignition in the combustor 10 to the time of a rated load of a turbine, from the time of ignition until reaching stable combustion conditions allowing stable combustion, a combustion gas in which a controller 100 controls a flow rate of a fuel supplied from a fuel supply part 40 and a flow rate of an oxidant supplied from an oxidant supply part 50 to maintain the same oxygen concentration as an oxygen concentration in the mixed gas is circulated as the circulating gas.