Steam Alternatives for Natural Gas Combined Cycle with Piperazine

Abstract

Natural Gas Combined Cycle (NGCC) power plants are one of the largest anthropogenic point sources of atmospheric CO₂. The most promising near-term strategy for mitigating CO₂ emissions from these facilities is the post-combustion capture of CO₂ using the piperazine with subsequent geologic sequestration. In this work, the steam cycle for an NGCC power plant is modelled. The steam cycle is comprised of two triple-pressure heat recovery steam generators (HRSGs) and one steam turbine. The focus of this study is on the design of the triple and single-pressure HRSGs with combined and simple cycle gas turbines (CCGT & SCGT) respectively, which aims to define the required steam conditions for plant efficiency, fuel flexibility, and economic operations. Pinch temperature, heat duty, and conductance (UA) are the main design parameters. Results revealed that the steam turbine power drops by 41.7% due to steam extraction, while NGCC gross power output reduces from 424.6 MW to 363.3 MW without and with steam extraction respectively. More importantly, the total heat input for solvent regeneration and compressor is 129 MWt, while at 100% load, SCGT can provide steam at a pinch temperature and UA of  262 °K, and 2.2 MW/K respectively.