Modern gas turbines require precise control of the fuel system. For example, a pressure drop across the fuel nozzles must be carefully maintained within a specified range in order to avoid combustor damage. In general, it may be difficult to operate a modern gas turbine on a normal, high-energy fuel (for example, natural gas) and a high hydrogen, low energy fuel (for example, syngas). What is desired, therefore, is a “dual gas” turbine fuel system that may both accommodate and carefully control a high-energy fuel, a low energy fuel, and a mix of high and low energy fuels.
The design of such a “dual gas” fuel system may be complicated by the different characteristics of the fuels. Operating a gas turbine with a low energy fuel requires a significantly higher volumetric flow rate than does operating a gas turbine with a high-energy fuel. Furthermore, a low energy fuel, which is typically derived from a gasification process, often may be supplied at a high temperature. These characteristics necessitate fuel system hardware that can accommodate and control large variations in both fuel temperature and volumetric flow rate. Unfortunately, this hardware may be large, complicated, and expensive. What is desired, therefore, is a method of operating a “dual gas” turbine system that uses smaller, standard, simplified hardware so as to save hardware costs, maintenance costs, and floor space.