design of cold box and investigating the effect of demethanizer pressure on ethane recovery

Separation of ethane from natural gas is a major step in treatment of gas which is conducted in demethanizer column. ethane is a valuable product in gas plants due to its application in petrochemical units. therefore, recovery of ethane as much as possible is desirable. one of the most important factors in ethane recovery is pressure of demethanizer. in this paper, a typical gas plant which contain cold box and demethanizer column is simulated and the effect of column pressure and temperature profile of column on ethane recovery is investigated. cold box is simulated by aspen edr. it was found that reducing of pressure from 30 bar to 28 bar along with decreasing of the temperature of reboiler, could enhance the ethane recovery by 11%.