Study on Natural Gas Decarbonization Process Based on CO ₂ Desublimation Characteristics

ABSTRACT Natural gas decarbonization is a crucial processing step. In this study, the snow separation technology for removal of carbon dioxide in natural gas based on CO 2 desublimation characteristics was introduced. The phase equilibrium calculation of CH 4 ‐CO 2 and N 2 ‐CO 2 system was carried out by using cubic equations of states (EOSs), and identified the SRK‐EOS as the most accurate model under low‐temperature, low‐pressure conditions ( T < 250 K, p < 3.2 MPa) for N 2 ‐CO 2 system and the PR‐EOS for CH 4 ‐CO 2 system. Analysis of the CH 4 ‐CO 2 system's frosting characteristics defined the operational window for CO 2 desublimation, leading to the development of a novel experimental separation system, and the process consistently reduced the CO 2 content in the top product gas to below 3% (molar fraction) under pressures of 0.7–1.2 MPa. This study conducted numerical simulation on the CO 2 desublimation process, which cannot be tested experimentally. Numerical simulations revealed that the nucleation rate and supersaturation increased with higher system pressure and feed CO 2 mole fraction, accelerating CO 2 ice crystal growth and consumption of gas‐phase CO 2 . Conversely, higher temperatures exhibited an opposing effect. These results confirm the technical feasibility of the CO 2 desublimation process for efficient natural gas decarbonization.