Performances of novel technologies for the exploitation of CO2-rich natural gas reserves

Natural gas is the fastest growing fossil fuel in future global energy scenarios. The consequent increase in the global demand for it has led to the need for the exploitation of those reserves that were left undeveloped in the past because of the high CO2 content. The selection of the best CO2 removal process is nowadays a critical concern, since each one has its own advantages and disadvantages when compared to the others. In particular, it is widely acknowledged that, for application to gas reserves characterized by a high CO2 content, conventional technologies based on chemical absorption are too energy-intensive because of the high energy required for solvent regeneration. Thus, new technologies have been recently proposed to treat the raw natural gas extracted from these reserves in a less energy-intensive and cost-effective way. Among these new technologies, low-temperature separation methods and hybrid technologies can be mentioned. The aim of this work is to compare the performances of a novel technology based on low-temperature distillation with those of a hybrid technology that combines a low-temperature distillation process aimed at performing a bulk CO2 removal with conventional chemical absorption into aqueous alkanolamines solutions as a finishing treatment. Simulations have been performed with Aspen Hysys® and Aspen Plus® and the comparison has been carried out by means of an energy analysis based on the “net equivalent methane” method. Different CO2 contents in the raw natural gas feed stream have been considered in order to establish the breakeven point between the two technologies in terms of CO2 inlet concentration that makes one process less energydemanding than the other one.