Safe Operation of Combined Cycle Gas Turbine and Gas Engine Systems Using Hydrogen Rich Fuels

This paper describes work performed by a consortium led by the UK Health and Safety Laboratory(HSL)to identify the safe operating conditions for combined cycle power generating systems running on high hydrogen fuels. The work focuses on hydrogen and high hydrogen syngas and biogas waste-stream fuel mixtures, which may prove hazardous in the event of a turbine, or engine flame out, resulting in a flammable fuel mixture entering the hot exhaust system and igniting. The paper describes the project, presenting some initial results from this work, including the development of large scale experimental facilities on the550 acre HSL site near Buxton, Derbyshire, UK. It describes the large scale experimental facility which utilises the exhaust gas from a Rolls-Royce Viper jet-engine (converted to run on butane) feeding into a 12 m long, 0.60 m diameter instrumented tube at a pre-combustion velocity of 22 m/s. A variable geometry simulated heat exchanger with a 40 %2blockage ratio is present in the tube. Flammable mixtures injected into the tube close to the Viper outlet, together with make-up oxygen, are then ignited. Extensive optical, ionisation, temperature and pressure sensors are employed along the length of the tube to measure the pressures and flame speeds resulting from the combustion event. Some preliminary results from the test programme are discussed including deflagration to detonation transitions at high equivalence ratios.