Double pinch criterion for optimization of regenerative rankine cycles

Abstract

Systems and methods are disclosed herein that generally involve a double pinch criterion for optimization of regenerative Rankine cycles. In some embodiments, operating variables such as bleed extraction pressure and bleed flow rate are selected such that a double pinch is obtained in a feedwater heater, thereby improving the efficiency of the Rankine cycle. In particular, a first pinch point is obtained at the onset of condensation of the bleed and a second pinch point is obtained at the exit of the bleed from the feedwater heater. The minimal approach temperature at the first pinch point can be approximately equal to the minimal approach temperature at the second pinch point. Systems that employ regenerative Rankine cycles, methods of operating such systems, and methods of optimizing the operation of such systems are disclosed herein in connection with the double pinch criterion.

Description

technical field [0001] In some embodiments of the invention, the invention relates to a system using a regenerative Rankine cycle, a method of operating the system, and a method of optimizing a method of operating the system. In particular, the present invention relates to a double pinch criterion for optimizing a regenerative Rankine cycle. Background technique [0002] The well-known Rankine cycle and its variants such as the Kalina cycle or the organic Rankine cycle are used to generate about 80% of the world's electricity. The Rankine cycle can be applied to a wide range of energy sources, including fossil fuels, nuclear energy, geothermal energy, solar energy, and biofuels. The demand for electrical energy continues to grow, as does the use of the Rankine cycle. [0003] In a basic Rankine cycle, a working fluid such as water is pumped into a boiler where it is heated by an external heat source to produce steam. High-pressure steam is directed into a turbine, where i...

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Problems solved by technology

Although the introduction of steam creates a small loss in turbine output, the preheating of the charge yields a net increase in overall efficiency

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