High Efficiency Gas Turbine/Organic Rankine Cycle Combined Power Plant

The use of an organic Rankine cycle system operating on the exhaust heat from a gas turbine results in a very significant improvement in the combined plant efficiency. For example, a current technology regenerated gas turbine with 36.6 percent efficiency, is improved to 47.1 percent by addition of the organic Rankine cycle bottoming plant. It has been determined that, because of the desirable thermodynamic properties of selected organic working fluids, the organic bottoming cycle invariably results in a substantially higher efficiency than the equivalent steam bottoming cycle. In addition, the non-corrosive properties of the organic working fluid, coupled with its desirable turbine expansion characteristics, results in a competitive capital cost. Preliminary studies indicate that the complete organic system cost is in the vicinity of $150/kwe from the organic system. For a base-loaded combined plant, the organic bottoming plant is estimated to produce power at an incremental cost of 0.370¢/kwhre.