Design criteria and optimization of heat recovery steam cycles for integrated reforming combined cycles with CO2 capture

One option for pre-combustion CO2 capture in power plants is the integrated reforming combined cycle (IRCC). IRCCs have previously been studied from multiple viewpoints: thermo-economic analysis, process optimization, environmental impact, and plant flexibility. This paper is focused on the design of the heat recovery steam cycle (HRSC), including the heat recovery steam generator (HRSG), and aims to define the optimal steam cycle configurations for plant efficiency and dual-fuel flexibility. A recently developed optimization algorithm was successfully applied to obtain a set of flexible and efficient designs for IRCCs. Results showed that the preferred designs consisted of a dual-pressure level HRSG with reheat and limited supplementary firing in duct burners, high-pressure evaporators and economizers in the syngas coolers, limited high-pressure level (140–154 bar), and feedwater preheating. The most attractive optimized dual-pressure designs showed improvements of approximately 0.5% points in the net plant efficiency compared to the non-optimized base case. The resulting net plant efficiency was about 45.8% with a net power output of around 425 MW for the best cases.

► HRSCs for integrated reforming combined cycles are analyzed and numerically optimized. ► HRSG and steam network are simultaneously optimized for efficiency and flexibility. ► Feedwater pre-heating and supplementary firing in HRSG are advantageous for efficiency. ► A single pressure level recovers all the available heat with close to optimal efficiency. ► HRSC optimization boosts up the plant electric efficiency preserving good flexibility.