Upgrading of a Small Size Gas Turbine to HAT Cycle Operation: Thermodynamic And Economic Analysis

A detailed study is presented in this paper concerning the changes required to transform a GE/Nuovo Pignone PGT2 gas turbine into a humid air turbine (HAT). The PGT2 is a 2 MW single-shaft gas turbine with a two stage centrifugal compressor and single can combustor. These features of the compressor and the combustion chamber are very important, because they reduce to a minimum the modifications necessary to add all the components required for operation in HAT cycle mode. This paper shows the performance of the PGT2 gas turbine in three different modified configurations: 1) regenerated cycle, 2) intercooled-regenerated cycle and 3) HAT cycle with flue gas condensation. A detailed economic study is presented of the regenerated and the HAT cycles. The intercooled-regenerated cycle was not considered in the economic analysis, because it does not reach the performance of the HAT cycle but it has not the advantage of being a dry cycle. All the components being added to the PGT2 are sized to determine with a sufficient accuracy their cost. The economic analysis presents a detailed cost analysis of the optimal configurations for maximum efficiency, and allows the calculation of the capital cost of the modified gas turbine. Return of investment is also presented in different economic situations with varying electricity and fuel prices.