An Unconventional Method to Separate Carbon Dioxide from Wellhead Natural Gas

Abstract

A new method to removal carbon dioxide from natural gas was proposed in this paper. Combining the nucleation and growth model, the droplet surface tension of carbon dioxide, models of methane–carbon dioxide mixture gas in the supersonic nozzle was established. The influence of inlet pressure on the supersonic condensation process was investigated. Under computational conditions that the pressure and temperature of inlet gas mixture are 6 MPa and 273 K, and the content of carbon dioxide is 20%, the results show that the Wilson point is x = 143.27 mm, the maximum nucleation rate, droplet radius and droplet number are 2.60 × 1021 m−3 s−1, 3.90 × 10−7 m and 7.42 × 1014 kg−1, respectively. The outlet liquid mass fraction of the nozzle is 23.18%. With the increase of the inlet pressure, the condensation position moves forward, the nucleation rate and the droplet number decrease, while the droplet radius and the humidity of carbon dioxide increase. In the actual production, the liquefaction efficiency of the Laval nozzle will be improved by adjusting the inlet pressure.