Optimized Combination of a Cooling Pond and Cooling Tower System for Condenser Cooling at a Steam Cycle Power Plant
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Date
1995Author
Kirchhoff, Joerg
Publisher
University of Wisconsin-Madison
Metadata
Show full item recordAbstract
The performance of the condenser cooling cycle of a steam cycle power plant is examined
for the Columbia Generating Station of the Wisconsin Power & Light Company located near
Portage, Wisconsin. The Columbia station is a coal fired power plant with a capacity of
1000 MW. A closed circuit cooling system is used for heat rejection that consists of a cooling
pond and two cooling towers. Pond and towers are connected in a parallel arrangement.
To study the behavior of the cooling system, computer models of the components are
developed. The cooling tower model is based on the analogy approach of a cooling tower and
an heat exchanger. An effectiveness-Ntu method is employed to predict the cooling tower
performance with respect to ambient and load conditions. For the calculation of cooling
capacity of the cooling pond surface, a semi-empirical approach is selected that is based on the
combination of free and forced convection. The water flow in the pond is approximated by a
plug flow model. From the energy transfer and flow model a simulation program is developed
that is capable of predicting cooling pond temperatures dependent on meteorological conditions
and heat load on the pond.
The possibility of adding different cooling devices to the system is examined. A simple
model of an atmospheric cooling spray is employed. A comparison between cooling tower and
cooling spray performance is performed to study if the addition of a cooling spray can be an
advantage for the system performance. The impact of dredging the pond to a greater depth is
evaluated.
To link the cooling system to the steam cycle performance a condenser model is introduced
that predicts the condenser back pressure for a given circulating water temperature and plant
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load. From an empirical relation the influence of condenser back pressure on the steam cycle
heat rate is determined. The performance of the cooling system is then evaluated economically.
The modular system simulation program TRNSYS is used to analyze the behavior of the
cooling system in combination with the power generation unit. Transient simulations are
performed in hourly time steps to examine the impact of weather conditions on the whole system
and to study diurnal fluctuations. A simulation program usable by the plant operators is a
product of this work.
Using the simulation program the cooling system is examined under different operation
modes utilizing the available equipment. Dependent on weather conditions the best plant
operation mode is found. Recommendations are given for the most cost effective alteration of
the cooling towers and pond.
Subject
Thesis (M.S.)--University of Wisconsin--Madison, 1995.
Dissertations Academic Mechanical Engineering.
University of Wisconsin--Madison. College of Engineering.
Permanent Link
http://digital.library.wisc.edu/1793/7801Description
Under the supervision of Professors William Beckman and John Mitchell.
Citation
Kirchhoff, J. (1995). Optimized Combination of a Cooling Pond and Cooling Tower System for Condenser Cooling at a Steam Cycle Power Plant. Master's Thesis, University of Wisconsin-Madison.