Process Analysis of Selective Exhaust Gas Recirculation for CO2 Capture in Natural Gas Combined Cycle Power Plants Using Amines

Abstract

Post-combustion CO2 capture from natural gas combined cycle (NGCC) power plants is challenging due to the large flow of flue gas with low CO2 content (~3-4%vol.) that needs to be processed in the capture stage. A number of alternatives have been proposed to solve this issue and reduce the costs of the associated CO2 capture plant. This work focuses on the selective exhaust gas recirculation (S-EGR) configuration, which uses a membrane to selectively recirculate CO2 back to the inlet of the compressor of the turbine, thereby greatly increasing the CO2 content of the flue gas sent to the capture system. For this purpose, a parallel S-EGR NGCC system (53% S-EGR ratio) coupled to an amine capture plant using MEA 30%wt.was simulated using gCCS (gPROMS). It was benchmarked against an unabated NGCC system, a conventional NGCC coupled with an amine capture plant (NGCC+CCS), and an EGR NGCC power plant (39% EGR ratio) using amine scrubbing as the downstream capture technology. The results obtained indicate that the net power efficiency of the parallel S-EGR system can be up to 49.3% depending on the specific consumption of the auxiliary S-EGR systems, compared to the 49.0% and 49.8% values obtained for the NGCC+CCS and EGR systems, respectively. A preliminary economic study was also carried out to quantify the potential of the parallel S-EGR configuration. This high-level analysis shows that the cost of some scenarios. However, further benefits with respect to the EGR configuration will depend on future advancements and cost reductions achieved on membrane-based systems.

Techno-Economic Optimization of Multistage Membrane Processes with Innovative Hollow Fiber Modules for the Production of High-Purity CO2 and CH4 from Different Sources

“…The process configuration required for high effective separation of CO 2 and CH 4 mixtures, which must be able to attain simultaneously high recovery and purity values for both gases, must include more than one membrane unit in order to achieve the imposed restrictions successfully. Different membrane network superstructures can be defined and screened by an optimization technique to identify the optimal process configuration, and several examples of this approach have been reported. ,,,, This approach can derive in the design of quite complex systems, with a high number of stages, such as processes with more than five stages , or the presence of several recirculation and by-pass streams. ,, Nevertheless, the application of innovative membranes with enhanced separation characteristics allows the design of much more simple process configurations, with just two stages with permeate connection in series and without recirculation or by-pass streams . The schematic diagram of the membrane system configuration developed in this work is shown in Figure .…”

Carbon Capture Systems for Building-Level Heating Systems—A Socio-Economic and Environmental Evaluation

“…However, membrane separation requires a higher percentage of CO 2 in the inflow (over 20%), which is considerably higher than that of the flue gas composition (less than 10%) of natural gas building heating systems. Although flue gas recirculation is a possible solution [79,80], it may need considerable modifications in the existing heating systems that require further research. Adsorption technology has a lower performance compared to all of the above factors.…”