PREDICTING FLAMEHOLDING FOR HYDROGEN AND NATURAL GAS FLAMES AT GAS TURBINE PREMIXER CONDITIONS

摘要

Lean premixed gas turbines are one of the most common methods for stationary power generation. By creating a homogeneous mixture of fuel and air upstream of the combustion chamber, temperature variations are reduced within the combustor, which reduces emissions of nitrogen oxides. However, by premixing fuel and air, a potentially flammable mixture is established in a part of the engine not designed to contain a flame. If the flame propagates upstream from the combustor (flashback), significant engine damage can result. While significant effort has been put into developing flashback resistant combustors, these combustors are only capable of preventing flashback during steady operation of the engine. Transient events (e.g. auto ignition within the premixer, pressure spikes during ignition) can trigger flashback that cannot be prevented with even the best combustor design. In these cases, preventing engine damage requires designing premixers that will not allow a flame to be sustained. Experimental studies were conducted to determine under what conditions premixed flames of hydrogen and natural gas can be anchored in a simulated gas turbine premixer. Tests have been conducted at pressures up to 9 atm, temperatures up to 750 K, and free stream velocities between 20 and 100 m/s. Flames were anchored in the wakes of features typical of premixer passageways, including cylinders, steps and airfoils. The results of this study have been used to develop tools that predict when a flame remains anchored to a particular feature.