Modelling of hot surface ignition within gas turbines subject to flammable gas in the intake

Controlling risks associated with fires and explosions from leaks of flammable fluids at oil and gas facilities is paramount to ensuring safe operations. The gas turbine is a significant potential source of ignition; however, the residual risk is still not adequately understood.

A model has been successfully developed and implemented in the commercial Computational Fluid Dynamics (CFD) code ANSYS CFX. This model is based on a combination of standard models, User Defined Functions (UDFs) and the CFX Expression Language (CEL). Prediction of ignition is based on a set of criteria to be fulfilled while complex kinetics is handled computationally easy by means of a reaction progress variable.

The simulation results show a good agreement with the trends experimentally observed in other studies. It is found that the hot surface ignition temperature (HSIT) increases with increase in velocity and turbulence but decreases with increase in initial mixture temperature and pressure.

The model shows a great potential in reliable prediction of the risk of hot surface ignition within gas turbines in the oil and gas industry. In the future, a dedicated experimental study will be performed not only to improve the understanding of the risk of hot surface ignition but also to collect experimental data under well-defined conditions to further validate or refine the model.