Flexible Operation of an IGCC Plant Coproducing Power and H2 with CO2 Capture through Novel PSA-based Process Configurations

Abstract

The coproduction of power and H2 in an integrated gasification combined cycle (IGCC) plant with CO2 capture demonstrated to entail interesting potentials in terms of flexible operations. The possibility to shift between the two energy products allows operating the plant in a load-following mode, where the reduction in net power output is counterbalanced by an increased H2 throughput. Within this framework, pressure swing adsorption (PSA) as gas separation technology showed to offer advantages in comparison to the common process layout involving an absorption process for capturing CO2. Two novel PSA-based process configurations are presented in this sense (i.e. Two-train PSA and One-train PSA) and their performance reported. The objective of this paper is to investigate the degree of flexibility achievable by the two novel process configurations. Some limitations arose in the capability of the One-train PSA process configuration to meet the ultrapure H2 specifications (99.99+% vol. purity) in the different cases tested. The flexibility can be realized if more relaxed purity specifications apply. Process simulations of the Two-train PSA process configuration demonstrated the plant capability to significantly reduce its load (about 31% reduction), while processing a constant coal feed. At the different plant loads tested, the H2 specifications were met and the plant efficiency was only slightly decreasing, thus the flexibility was realized. The simulation of similar loads reduction in a reference IGCC plant for power generation with CO2 capture, showed a more significant decrease in efficiency, confirming the effectiveness of the novel process configuration proposed.