The GT24/26 Combustion Technology and High Hydrocarbon (“C2+”) Fuels

Abstract

In 1998 ALSTOM launched a development program to burn fuels containing high hydrocarbons in the GT24/26 gas turbines. These fuels are found in different parts of the world as for example in Brazil, Algeria or in the gulf of Bengal and Thailand. After validation in the GT26 gas turbine in the ALSTOM power plant in Birr (Switzerland) the combustion of fuel gases with up to 16 Vol% of high hydrocarbons was released in 2001. First field engines started to operate in 2001 and today 18 units are running commercially successful burning high hydrocarbon fuel gases. The engines operate without any hardware modifications compared against standard natural gas fuel, however with an advanced engine control system based on a fast gas composition monitoring system. This achievement is particularly remarkable in view of the sequential combustion system with a high pressure (30bar) first combustor stage, and a high inlet temperature (1000°C) second combustor stage. The paper discusses fundamental aspects of burning high hydrocarbon fuels and in particular its impact on the ignition process. It outlines the careful development and validation procedure which has been applied at ALSTOM. Finally, evidence is given of today’s reliable engine operation with 200’000 operating hours on high hydrocarbon fuel supplies at remarkably low emission levels.