Energy Conversion and Management: X (Apr 2024)
Advanced configurations of amine based post-combustion carbon capture process applied to combined cycle gas turbine
Abstract
The increasing share of renewables in the energy mix, combined with a lack of storage facilities and a strong need of security in electricity supply, brings the need to keep back-up power plants based on fossil fuel in the field of electrical power generation. Due to high operational flexibility and high efficiency, Combined Cycle Gas Turbines (CCGTs) are great candidates to fulfill this role. However, these large combustion power plants need to switch to low-carbon emissions to reach the environmental objectives of carbon neutrality. To this end, Amine based carbon capture is the most promising and well-proven Post-Combustion Capture (PCC) technology to retrofit large combustion power plants. Nevertheless, this process is known to lead to significant amounts of thermal and electrical power consumptions, resulting in a significant energy penalty for the CCGT. To make the PCC economically competitive when integrated in gas-fired power plants, this energy penalty needs to be considerably reduced. Hence, four advanced configurations focusing on the regeneration process have been investigated to increase its energy efficiency: Lean Vapor Recompression (LVR), LVR combined with Overhead Gas Recompression (OGR), LVR combined with Rich Solvent Preheating (RSP) and Rich Vapor Recompression (RVR) combined with Cold Solvent Split (CSS). A base model was first established in Aspen Plus and validated against experimental data of a pilot scale facility. This PCC model was then scaled-up to a 770 MWe CCGT integrated with 35% Exhaust Gas Recirculation (EGR). Furthermore, key operating parameters of the proposed advanced configurations have been optimized enabling a fair comparison of their performance. LVR combined with RSP, using the reboiler condensate, turned out to be the most efficient advanced configuration for gas-fired power plants. This configuration enables to reduce the impact of the PCC unit on the CCGT net power down to 1.199 MJe/kgCO2 which represents a gain of 7.3 % compared to the conventional PCC process. Moreover, in gas-fired power plants, LVR has proven to be more efficient than the combination of RVR and CSS, unlike in coal-fired power plants. The next step will be to study the behaviour of LVR under part-load operations.
