(668a) Cryogenic CO2 Removal From Natural Gas by Desublimation in Staged Heat Exchanger

A new and novel method is proposed for removal of CO₂ in raw natural gas streams by cooling the natural gas stream to -130 °C at near ambient pressures, causing CO₂ in the natural gas stream to desublimate. Desublimation occurs in a novel desublimating heat exchanger with a low vapor pressure contact liquid and/or liquefied natural gas (LNG). The heat exchanger is staged, with the raw natural gas feed bubbled through contact liquid and/or LNG. The desublimating solid CO₂ is entrained in the contact liquid and/or LNG and subsequently separated through filtration. The cold purified CO₂ and natural gas products then return through a regenerative heat exchanger to cool incoming natural gas and melt the purified solid CO₂ stream. The overall energy efficiency of this system exceeds that of competing desublimation technologies by reducing the required pressure of operation and eliminating the significant losses of a distillation tower in reboiling and condensing.