Drop size measurements in Venturi scrubbers

Venturi scrubbers are high efficiency gas cleaners in which suspended particles are removed from gas streams by drops formed by liquid atomisation, usually in the Venturi throat. The size of the drops formed are of fundamental importance to the performance of the equipment, both in terms of pressure drop and dust removal efficiency. In this study, drop sizes in a cylindrical laboratory-scale Venturi scrubber were measured using a laser diffraction technique. Gas velocity and liquid to gas ratios varied from 50 to 90m/s and 0.5 to 2.0l/m3, respectively. Water was injected using two different arrangements: either as jets in the throat or as a flim just upstream of the convergence. Drop size measurements were performed at three positions in the case of jet injection: two located along the throat, and the last one at the end of the diffuser. The present data shows that the Sauter mean diameter of the spray can be well correlated by the equation of Boll et al. (J. Air Pollut. Control Assoc. 24 (1974) 932). Drop size distributions are satisfactorily represented by a Rosin–Rammler function. This paper also provides a simple method for calculating the parameters of the Rosin–Rammler function. As a result of this work, drop sizes in Venturi scrubbers can be estimated with much higher accuracy.