Adsorptive Removal of Methanol from LPG

Abstract

Liquefied natural gas (LNG) is mixed with liquefied petroleum gas (LPG) at LNG terminals to adjust its calorific value in line with the stringent gas quality criteria. One method used for adding LPG to LNG is liquid/liquid calorific value adjustment, in which both LPG and LNG are maintained in the liquid phase. In this method, impurities present in LPG, such as water and methanol, may precipitate in an LNG/LPG mixture. In the present study, liquid-phase adsorption using a Na-X type zeolite was investigated for removal of methanol from low-temperature LPG. Pilot scale experiments were conducted to evaluate the effects of variation of process conditions. As the result, it was showed that variations of LPG flow rate and methanol concentration had little effect on adsorption capacity and the width of the adsorption band, known as the mass transfer zone. The results obtained demonstrated adequate performance for the purpose of a designing a practical system.