Optimal design and operating strategy of a carbon-clean micro gas turbine for combined heat and power applications. (September 2019) - Giorgetti, S.
Highlights: Sankey and Grassmann diagrams of a mGT/mHAT with EGR and CC are presented. mGT working in full CHP and integrated with CC is the most efficient layout. In part load, flue gas heat recovery significantly reduces the CC reboiler duty. Humidification of the mGT is not as efficient as direct CC heat recovery. Abstract: As a distributed energy production technology, micro gas turbines (mGTs) offer a great potential for small-scale combined heat and power (CHP) production, adding flexibility to the electricity system. Nevertheless, due to the evident climate change, a very low greenhouse gas (GHG) emission is a fundamental requirement for our future energy systems. For this purpose, combining an mGT with a carbon capture (CC) plant might offer an effective carbon clean energy production. In the literature, several studies are available, addressing individual aspects of this attractive energy solution; however, an in-depth analysis focusing on the energy integration and strategy optimisation of an mGT working in CHP mode with CC has never been performed. This work is the continuation of the previous thermodynamic analysis in which an mGT and a micro Humid Air Turbine (mHAT) have been directly connected with a CC unit without heat recovery. In the current study, the aim is to find the best plant layout and the best operating strategy based on the electrical, thermal and global cycle performance. Results show that the full CHP operation of the mGT offers the highest global efficiency between all plant layouts. Contrary to what may be expected from previous analyses on cycle humidification, the mHAT does not entail a better performance when the turbine cycle and the CC unit are energetically integrated. Direct heat recovery, which reduces the CC thermal demand, is a preferable measure which involves a lower energy degradation. Sankey and Grassmann diagrams are presented to support the numerical results.