A novel high pressure-high temperature experimental apparatus to study sequestration of CO₂-SO₂ mixtures in geological formations

A novel experimental set-up to investigate the sequestration of non-pure carbon dioxide (CO₂) streams in geological formations through mineral trapping is discussed. The system includes a gas manifold system, a gas booster, a fluid reservoir, a high pressure-high temperature reactor, and auxiliary elements to ensure safe and reliable operation under the high temperatures and pressures required for the experiments. The apparatus described here is inspired by previously reported batch equipment, but has the versatility of co-injecting gas mixtures. The capacity of the vessel is 600 mL and the system is capable of applying pressures from ambient to 5000 psi (345 bar), and temperatures from ambient to 350 °C under batch continuous stirring conditions. These ranges of pressure and temperature can cover and even exceed the conditions relevant for the majority of subsurface sequestration studies. The interior wetted parts of the vessel are all in Hastelloy C276 (a Ni-Cr-Mo alloy) to be resistant to the corrosiveness of gases such as SO ₂. The system was tested by studying the sequestration of CO ₂-SO₂ mixtures in ferric (Fe^III) iron-containing sediments, as SO₂ has been shown to reduce Fe ^III to Fe^II and permanently trap CO₂ as the mineral siderite (FeCO₃). A series of batch trials were conducted to demonstrate the experimental apparatus design efficacy along with the systeḿs behavior. The apparatus functioned well during the course of the experiments proving that this set-up is a useful research tool to investigate the effect of impurities present in the flue gas from fossil fuel combustion in the geological storage of CO₂.