Gas Turbine Exhaust Heat Recovery by Hybrid Steam/Ternary Aqueous Immiscible Liquid Cycle
The concept of the dual pressure steam/pure organic hybrid immiscible liquid cycle applied to recover exhaust heat from gas turbines is extended to include organic mixtures. Thermodynamics of the resulting ternary working fluid cycle is presented. For the cycle arrangement analysed it is calculated that the ternary steam/nonane/decane cycle with the organic very nonane rich produces about 2% more work than the corresponding all steam cycle for a typical gas turbine exhaust temperature. It is estimated that this advantage can be raised to about 4% by adding additional heaters at the stack end of the heat recovery generator. The analysis shows that it is unnecessary to use a pure alkane organic. A mixture containing up to about 5% of alkanes with higher boiling points than nonane is adequate.