NATURAL GAS DEHYDRATION USING TRIETHYLENE GLYCOL (TEG)

Abstract

Water vapour in natural gas stream, poses threat to process facilities if the dew point temperature is not properly controlled. Hydrate formation is imminent at temperatures below the dew point. It becomes very important to reduce the water content in the gas stream to below or within the tolerated limit of 6-7lb/MMSCFD. This work “Dehydration of Natural Gas Using Triethylene Glycol (TEG)” as the dehydrating agent, examined the amount of water removed from the natural gas stream when the dehydrating agent and the gas, flow in counter current manner in a contacting column. Adsorption and absorption are methods use to reduce the water content in a natural gas stream, in this work absorption was employed. Natural gas dehydrating plant was designed and simulated using HYSYS software. Process conditions of 92bar and 30 o C and gas flow rate of 10MMSCFD, were inputted into the software and simulated. Six different TEG flowrates were used for the simulation. Results obtained show that for a TEG flow rate of 25.47m 3 /h, the water content was reduced to 4.783lb/MMSCF from an initial value of 19.84lb/MMSCF. This value is well below the tolerated limit. The percentage composition of methane recovered at this flow rate was 82%. For a TEG flow rate of 3.5m 3 /h, 6.8lb/MMSCF of water was obtained in the processed gas stream. Again, this value is within the tolerated limit. The hydrate formation temperature of the dry gas stream was tested with the hydrate utility in the software, which was -18.663 o C at the stream pressure of 92bar. This value is well below the dry gas stream temperature of 37.96 o C. This means that the dry gas can be transported to region of