Pilot-scale evaluation of concentrated piperazine for CO2 capture at an Australian coal-fired power station: Nitrosamine measurements

Concentrated piperazine is a promising new solvent under consideration for post combustion capture (PCC) of CO2. As it is a secondary amine, one of the concerns when applying this solvent to flue gases is the potential formation of nitrosamines. Secondary amines will form stable nitrosamines, which are generally considered to be carcinogens. The Tarong CO2 capture pilot plant was recently used to evaluate the concentrated piperazine process on a real coal flue gas. During duration operation completed at the plant, solvent samples were regularly collected and analysed for their nitrosamine content. Mononitrosopiperazine (MNPZ) concentration in the solvent was noted to increase with operating time, reaching a steady state level of approximately 7.5 mmol/kg when operating with a regeneration temperature in the stripping column of 125 °C. The concentration of MNPZ in the solvent was noted to decrease sharply to 2.5 mmol/kg when the regeneration temperature was increased to 155 °C. The results provided here suggest that the concentration of MNPZ formed in the solvent can be controlled through the choice of plant operating conditions.