Paper: Inlet Air Chilling System Design for 4000-MW Combined-Cycle Project

System designed to increase power output from power plant in desert


The 4000-MW Qurayyah IPP project (QIPP) in the Kingdom of Saudi Arabia has six 2-on-1 combined-cycle blocks with 12 turbine generating units, 12 heat recovery steam generators (HRSGs), 6 steam turbine generators, and 6 seawater cooled condensers. The plant is designed to endure harsh site conditions from heavy sand storms to temperatures that can exceed 50ºC (120ºF).

Measures to offset the extreme heat include a specially designed inlet chilling system. Each combustion turbine is quipped with inlet air chilled water coils. Chilled water is supplied to the coils from two chilling plants consisting of a 10-million-gallon thermal energy storage tank, eight 5,760-refrigeration-ton chiller modules, and 10 secondary chilled water pumps.

The system is designed to lower the turbine inlet air temperature to 15 ºC (59 ºF) over a wide range of ambient conditions to increase the plant power output. This paper explores some of the unique design aspects of the QIPP chilled water system including:

  • Chilled water is used for cooling the 18 generators in addition to the inlet air
  • Turbine inlet air coil condensate is collected and reused as chiller cooling tower make up water
  • Chilled water secondary loop and controls are designed so that both the inlet air coils and generators receive the proper amount of flow at the correct temperature under all operating conditions
  • Chiller system cooling tower blowdown is reused for HRSG quench water
  • Chiller make-up water system is optimized to meet fluctuating demand
  • Chiller system sizing basis and use of the thermal energy storage tank are optimized for yearlong operation including during peak demand
  • Measures were taken to prevent water hammer occurences during multiple pump trips

David G. Rice, William D. Edgar – Sargent & Lundy
PO Lim – Samsung C&T
Curtis Lovelace – Stellar Energy

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