Optimizing turbine cycle heat rate against cooling tower operations
- Knight Piesold Energy LLC, Denver, CO (United States)
Partly due to regulated electricity market mechanisms, cooling towers have become the Cinderellas of power plants. They are often overlooked or at the bottom of the pile when annual budgets are decided. Yet, as the single largest heat exchanger available to conventional steam generating units, one would rightfully expect them to have a significant impact on generation efficiency and that one should be able to optimize their operations against the turbine cycle heat rate. Due largely to the complexity of the interaction of an evaporative cooling tower with ever changing ambient conditions and the turbine cycle, the optimization of cooling tower operations has not yet been fully exploited. A cooling tower interacts with the turbine cycle through heat rejection to the circulating water at the condenser. Thereby the turbine back-pressure is reduced which improves turbine efficiency in a push-me-pull-you fashion. Generally speaking, the colder the re-cooled water temperature, the lower the back-pressure, the lower the turbine cycle heat rate. However, the ambient wet bulk temperature, cold water temperature, condenser back-pressure and turbine cycle heat rate do not interact linearly. Rather, points are reached for every combination of operating variables, at which a reduction in cold water temperature produced by the cooling tower would cost more to achieve than the benefits one would gain from the turbine cycle heat rate. That sets the stage for an optimization exercise, the objective being to minimize fuel costs or to maximize net saleable power. This paper will present a case study for the optimization of cooling tower operations at a steam turbine generating unit and will show how, with the availability and affordability of computerized methods, one can take out the guess work for plant operators and do so with rapid pay-back of costs.
- Research Organization:
- Illinois Inst. of Tech., Chicago, IL (United States)
- OSTI ID:
- 696752
- Report Number(s):
- CONF-990410-PROC.-Vol.2; TRN: IM9946%%137
- Resource Relation:
- Conference: 61. American power conference annual meeting, Chicago, IL (United States), 6-8 Apr 1999; Other Information: PBD: 1999; Related Information: Is Part Of Proceedings of the American power conference: Volume 61-2; McBride, A.E. [ed.]; PB: 485 p.
- Country of Publication:
- United States
- Language:
- English
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