TREATMENT OF NATURAL GAS BY ADSORPTION OF CO2

Abstract

Apart from burning, one of the possible uses of natural gas is as a fuel for motor vehicles. There are two types of fuel from natural gas — CNG (Compressed Natural Gas) or LNG (Liquefied Natural Gas). Liquefaction of natural gas is carried out for transport by tankers, which are an alternative to long-distance gas pipelines, as well as for transport over short distance, using LNG as a fuel for motor vehicles. A gas adjustment is necessary to get LNG. As an important part of the necessary adjustment of natural gas to get LNG, a reduction of CO₂ is needed. There is a danger of the carbon dioxide freezing during the gas cooling. This work deals with the testing of adsorption removal of CO2 from natural gas. The aim of these measurements was to find a suitable adsorbent for CO₂ removal from natural gas. Two different types of adsorbents were tested: activated carbon and molecular sieve. The adsorption properties of the selected adsorbents were tested and compared. The breakthrough curves for CO₂ for both adsorbents were measured. The conditions of the testing were estimated according to conditions at a gas regulation station — 4.0MPa pressure and 8 °C temperature. Natural gas was simulated by model gas mixture during the tests. The breakthrough volume was set as the gas volume passing through the adsorber up to the CO₂ concentration of 300 ml/m3 in the exhaust gas. The thermal and pressure desorption of CO₂ from saturated adsorbents were also tested after the adsorption.