Packing and Tray Efficiencies for an Absorption Tower. An absorber in a petroleum refinery uses a lean oil to absorb butane from a natural gas stream. The composition of the key component butane in the gas phase is related to its composition in the liquid phase at equilibrium by y=mx=0.7x. At the tower's bottom, where the flows are largest, L=57.9lbm/ft3(927kg/m3). At the average tower temperature, L=1.4cp and the average molecular weight of the liquid is ML=245. Estimate the efficiency for a valve-tray tower and the HETP for Norton Intalox 2T structured packing