Chemical absorption of CO2 with aqueous NH3 was numerically analyzed in an Eulerian manner for steady 1D spray towers in which gas velocity and liquid flow were uniform, and the results were formulated into a universal correlation. The capture efficiency eta predicted by the proposed correlation is a sort of upper bound, and can be used as a base to evaluate the optimality of each design. Drop-size poly dispersity was considered; a spray of poly dispersed droplets was found to be equivalent in eta to a spray of monodispersed droplets of an equivalent diameter, and a general formula for the equivalent size was attained in terms of mean size and geometric standard deviation. Total mass transfer coefficient was linearly proportional to the gas liquid flow rate ratio, and the efficiency correlation agreed well with published results.