Estimation of tray efficiency in dehydration absorbers

In triethylene glycol (TEG) dehydration, a bubble cap tray efficiency between 25 and 40% has normally been recommended in literature. Measured Murphree efficiencies, based on performance data from literature and improved phase equilibrium data, have been calculated to values between 51 and 76%. The AIChE method has been used to estimate tray efficiencies under the same conditions. The estimated Murphree efficiencies varied between 57 and 70%, the estimated overall efficiencies between 31 and 62%. The AIChE method seems to give reasonable efficiency estimates for TEG absorbers. Both measured and estimated efficiencies indicate that the actual efficiencies are higher than recommended in literature. The Murphree efficiencies are less sensitive to changes in parameters than the overall efficiencies. A general design recommendation is suggested: using 50% Murphree efficiency based on accurate phase equilibrium data should give a conservative design at normal high pressure dehydration conditions.