Abstract
An updraft tower cooling system is assessed for elimination of water use associated with power plant heat rejection. Heat rejected from the power plant condenser is used to warm the air at the base of an updraft tower; buoyancy-driven air flows through a recuperative turbine inside the tower. The secondary loop, which couples the power plant condenser to a heat exchanger at the tower base, can be configured either as a constant-pressure pump cycle or a vapor compression cycle. The novel use of a compressor can elevate the air temperature in the tower base to increases the turbine power recovery and decrease the power plant condensing temperature. The system feasibility is evaluated by comparing the net power needed to operate the system versus alternative dry cooling schemes. A thermodynamic model coupling all system components is developed for parametric studies and system performance evaluation. The model predicts that constant-pressure pump cycle consumes less power than using a compressor; the extra compression power required for temperature lift is much larger than the gain in turbine power output. The updraft tower system with a pumped secondary loop can allow dry cooling with less power plant efficiency penalty compared to air-cooled condensers.
Highlights
Utility scale power plants must reject a huge amount of heat based on the second law of thermodynamics
Even compared to the traditional water-cooled cooling tower, the pumped loop can produce a net power benefit if a tower higher than approximately 480 m is constructed, due to the heat recovery by the updraft tower turbine. This is consistent with the result of the constant-pressure pump secondary loop shown in Figure 14; note that Figure shows the net power consumed by the cooling system, which is offset from Figure by 2 MW due to the power required by the water-cooled cooling tower
The performance of the system is evaluated based on the net power needed to drive the system, which depends on the refrigerant type, component sizing, and operating conditions
Summary
Utility scale power plants must reject a huge amount of heat based on the second law of thermodynamics. The updraft tower system with a constant-pressure pump cycle is one possible design This technology is known as the natural draft dry cooling tower and has been analyzed in the literature and applied in large power plants. An innovative indirect dry cooling method is analyzed that uses an updraft tower, combined with a secondary loop with vapor compression cycle, to reject the power plant condenser heat and increase the energy recovered from the turbine. A traditional natural draft cooling system couples the updraft tower to the power plant using a constant-pressure pump cycle; this requires a larger heat transfer area to reject the condensing heat. A realistic updraft tower system design is formulated based on the results of these parametric studies For this design, the constant-pressure pump secondary loop system performance is evaluated and compared to the vapor compression secondary loop system. The penalty in power generation efficiency using a dry cooling updraft tower system is compared to a power plant using air-cooled condensers
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
