Advancement of ammonia based post-combustion CO2 capture using the advanced flash stripper process

The energy consumption associated with absorbent regeneration remains the most critical challenge for the industrial implementation of chemisorption based CO2 capture processes. Aimed at reducing the energy consumption, this paper proposes a promising process modification of the ammonia (NH3) based CO2 capture process that involves an advanced flash stripper with a cold rich split. We investigated the techno-economic performance of the advanced NH3 process integrated with a 650 MW coal-fired power plant, and evaluated it technical and energy performance using a rigorous, rate-based model in Aspen Plus. A sensitivity study was also performed to optimise the modelling parameters, i.e. the stripper pressure and the absorbent NH3 concentration, and minimize the regeneration duty. A very competitive regeneration duty of 1.86 MJ/kg CO2 was achieved for an optimised stripper pressure of 12 bar and an NH3 concentration of 10.2 wt%, with a total equivalent work of 0.164 MW h/t CO2 for absorbent pumping, NH3 regeneration and CO2 compression. We also used a validated economic model to estimate the capital investment of the advanced NH3 process and its corresponding economic performance. With its significant reduction in energy consumption, the proposed process was economically competitive with CO2 avoided cost was as low as US$40.7/t CO2. This was 34% and 44% less than the reference NH3 and monoethanolamine (MEA) processes, respectively. The advanced NH3 based flash stripper also had technical and economic advantages over other amine absorbents, such as MEA and piperazine (PZ), as well as other advanced stripper modifications, such as inter-heating process, revealing its process viability in commercial application.