Pilot-scale evaluation of AMP/PZ to capture CO2 from flue gas of an Australian brown coal–fired power station

Monoethanolamine (MEA) is a well-established absorption liquid used in post-combustion capture (PCC) technology that has a high rate of reaction with CO2. However, an absorption liquid with improved properties, such as less degradation, less corrosion and a lower energy requirement for solvent regeneration, would greatly benefit the PCC process. An alternative to MEA is an aqueous solution of 2-amino-2-methyl-1-propanol (AMP), promoted with piperazine (PZ). This absorption liquid is expected to improve CO2 recovery and reduce reboiler heat duty for solvent regeneration in PCC plants. This paper evaluates the pilot-scale performance of an aqueous mixture of 25 wt% AMP and 5 wt% PZ (AMP/PZ) with a total amine concentration of 30 wt% compared with the baseline performance of aqueous MEA (30 wt%). We evaluated the reboiler heat required for solvent regeneration and CO2 recovery for AMP/PZ and MEA as both a function of CO2-lean loading at a similar liquid to gas (L/G) ratio, and as a function of L/G ratio at a similar CO2-lean loading. Our results show that AMP/PZ is a promising alternative to MEA. At a similar L/G ratio, both MEA and AMP/PZ required lower reboiler heat duty when CO2-lean loading was reduced. At higher CO2-lean loadings, neither absorption liquid showed any changes in reboiler heat duty as a function of L/G ratio. One exception occurred for AMP/PZ at lower CO2-lean loadings (0.03 and 0.08 mol CO2/mol amine), when reboiler heat duty dropped as the L/G ratio rose. In most experiments with AMP/PZ, the condenser heat and sensible heat were the major contributors to the reboiler heat duty at lower CO2-lean loadings (<0.1 mol CO2/mol amine). For MEA, the condenser heat had the highest portion in the reboiler heat duty at a CO2-lean loading of <0.18 mol CO2/mol amine. Increasing condenser heat was associated with an increase of heat for water evaporation to generate steam for CO2 stripping. The reboiler heat duty to capture ∼80% and ∼85% CO2 was similar for both absorption liquids; yet, to capture this proportion of CO2, AMP/PZ required a higher L/G ratio than MEA.