Evaluation of steam and water injection effects on gas turbine operation using explicit analytical relations

Abstract

The changes in performance of a gas turbine resulting from the injection of steam or water into the combustion chamber are evaluated using explicit analytic relations. From the values of performance parameters at an operating point without injection, the changes in fuel amount, power output, and efficiency are evaluated. The difference in behaviour of the case of water and steam injection are highlighted and explained. It is shown that the movement of the operating point on the compressor map, for single and twin shaft turbines, can also be predicted. Comparison with predictions of computer models show that the deviations are predicted accurately. Design data from a large number of commercial gas turbines are used to show the range of variation of parameter deviations and provide some general guidelines as to the size of expected parameter deviations for any gas turbine, when water or steam are injected between the compressor exit and the turbine inlet.