Techno-economic comparisons of CO2 compression and liquefaction processes with distillation columns for high purity and recovery

Abstract

CO2 compression and liquefaction (CCL) requires recovery to be optimized under purity constraints for transportation and storage to minimize costs. CCL processes that operate at 1 million t/y were techno-economically analyzed to evaluate the levelized cost of CO2 liquefaction (LCCL) and to examine the effect of carbon taxes on the LCCL. The processes included multistage compressors, temperature swing adsorption (TSA) for dehydration, and distillation columns for impurity removal. The same purity constraints were applied to four CCL processes that produce liquid CO2 at 80 bar and 40 °C: (i) a CCL process without a distillation column (Reference case), and CCL processes with distillation columns placed after (ii) the seventh compressor (Case 1), (iii) the sixth compressor (Case 2), and (iv) the TSA unit (Case 3). The reference case failed to meet purity requirements, delivering an LCCL of $16/t-CO2. On the other hand, Case 1 was the most cost-efficient among the three cases, delivering a minimum LCCL of $22/t-CO2 at a recovery of 93 %, which is consistent with usual costs ($13–25/t-CO2). Charging a carbon tax of $100/t-CO2 on CO2 emissions during the CCL process increased the minimum LCCL to $25/t-CO2 for Case 1 and shifted the optimum recovery to 96 %.