Micro gas turbine configurations with carbon capture – Performance assessment using a validated thermodynamic model

Abstract

The expected increase in distributed power generation, especially in Europe, and the necessity for a reduction in greenhouse gas emissions requires an evaluation of carbon capture application at small-scale combined heat and power plants. In this regard, a micro gas turbine (MGT), a Turbec T100, has been selected for further investigation as a baseline. A thermodynamic model validated against data obtained from a test rig has been extended to enable modeling of a CO2 capture unit. In addition, two innovative cycles, an exhaust gas recirculation (EGR) cycle and a humid air turbine (HAT) cycle, have been investigated using the selected micro gas turbine model with a focus on improved carbon capture efficiency. The thermodynamic performance indicators of all cycles, namely, the baseline MGT cycle, the EGR cycle, and the HAT cycle, all with capture unit, are presented. The results show a considerable improvement in cycle efficiency for the HAT cycle (25.8%), compared to the baseline MGT (23.0%) and EGR (22.5%) cycles. However, the surge margin is reduced markedly for the HAT cycle. It is shown that the effect of EGR on the operation of the micro gas turbine is marginal. The effects of varying ambient air temperature on the performance of all cycles as well as the effect of different recirculation percentages on the performance of the EGR cycle have also been investigated. The results confirm that the performance in the EGR cycle is less sensitive to the change in ambient temperature, compared to the other cycles. The marginal effect of various recirculation percentages on the performance of the EGR cycle is also shown in this paper.