Techno-economic analyses of CO2 liquefaction: Impact of product pressure and impurities

As a first step towards identifying the optimal transport conditions for shipping CO2, this study investigates the impact of post-liquefaction delivery pressure on the design and cost of CO2 liquefaction for (a) pure CO2 (b) three impurity scenarios (c) two purity requirements. For pure CO2, the highest liquefaction cost is obtained at 7 bar amongst the range considered (7 to 70 bar), while a minimum lies around 40-50 bar. When different potential impurity scenarios are considered, impurities need to be purged for the low-pressure cases as these are not necessarily soluble in the liquefied CO2 stream. As a consequence, the liquefaction cost increases significantly for low-pressure cases (up to 34% compared to the pure CO2), and wider differences between the pressure levels are obtained. Purity requirements also have a significant impact on comparisons of delivery pressures, although this impact depends on both the impurities present and the purity requirement considered. (C) 2019 Elsevier Ltd and IIR. All rights reserved.