Chilled Coil Control and Field Performance for Turbine Inlet Air Chilling

Abstract

Ambient conditions greatly affect the combustion turbine performance. The Absorption Refrigeration Cycle Turbine Inlet Chilling (ARCTIC) system can chill the inlet air of the turbine to maintain optimum performance at all ambient temperatures. However, turbine characteristics, bell-mouth icing concerns, economics and performance guarantees require maintaining the inlet air temperature within a narrow range throughout the year. These considerations require strict control of the Turbine Inlet Air Chilling (TIAC) coil performance over a wide range of operating conditions. This paper describes the field performance and control of the chilling coil for a Mars 100 turbine. The controls logic had been developed from previously published empirical model of the chilling coil and model of the chilling loop performance at the various ambient conditions. Since commissioning at the end of summer 2020, the ARCTIC has provided inlet air chilling over a range of ambient conditions. Typically, the inlet air is maintained at 7.2∘C (45∘F) by controlling the TIAC chilled water flow rate and temperature. On cooler days, if the inlet air temperature drops to 5.6∘C (42∘F) the chilled water pump turns OFF automatically to prevent bell-mouth icing. Thus, the chiller accommodates chilling load variations down to zero load. On colder days, the ARCTIC continues operating till the ambient temperature drops below 1.7∘C (35∘F) and then turns OFF. The chiller turns back ON when the 8 h average inlet air temperature exceeds 10∘C (50∘F). These parameters can be adjusted remotely by the operator and help maintain performance guarantees while minimizing chiller cycling. Quasi-steady state data were analyzed to quantify the chilling load and coil performance over a range of operating conditions.