Environmental thermoeconomic performance analysis of gas turbine combined cycle under off-design conditions

Abstract

Although the gas turbine combined cycle (GTCC) system has better environmental performance, it still emits pollution gases such as CO2 and NOx. It is reasonable and necessary to add the environmental cost to the power production cost of the GTCC system. Based on the structure theory of thermoeconomics, through the reasonable pricing of pollutants (considering the environmental costs of CO2 and NOx emission), the system environmental thermoeconomic cost (ETC) model is developed in this study, which achieves absolute internalization of environmental costs. Taking GTCC with different gas turbine (GT) operation strategies as the research object, the influences of different operation strategies and environmental conditions on the GTCC system ETC are studied. The results of this study show that it is beneficial to maintain higher turbine inlet temperatures (T3) and turbine outlet temperatures (T4), thus ensuring better GTCC environmental thermoeconomic performance, and GTCC with the operation strategy (using inlet guide vane (IGV) control to maintain T3 at the design value and then to keep T4 at its maximum value (IGVT3-650-F) has the lowest ETC, which are 0.09429 $/kW·h at 75% gas turbine load rate (GTLR) and 0.10079 $/kW·h at 50% GTLR, respectively; reducing the emission of pollutants can reduce the unit ETC; for the combustion chamber, as the pollutant generation component of GTCC unit, it is most affected by the environmental damage cost; reducing the inlet air temperature can improve the system environmental thermoeconomic performance.