Numerical analysis and optimization of double products recovery process for CO₂-EOR associated gas

Using HYSYS software, simulated analysis was carried out on cryogenic fractional distillation process for CO₂-EOR associated gas (88.15% CO₂ molar fraction) to realize double products recovery. Three kinds of pressurization scheme were designed and analyzed to determine the optimal scheme. The relationships between cold/heat load and the CO₂ output and column bottom temperature of ethane recovery tower and additive recovery tower were analyzed. The influence of additive circulation flow rate on CO₂ product output and purity was also analyzed. Under the simulated conditions, the numerical results indicated that column bottom optimal temperature was 130 ℃ for ethane recovery tower and 135 ℃ for additive recovery tower respectively, optimal additive circulation flowrate was 64.64 kmol/h and CO₂ product purity was up to 99.04%.