The report gives results of an analysis of typical wet scrubber models to determine the effects of surface tension on particle removal efficiency. Particle capture (removal) is a two-step process: collision of a particle with a spray droplet, and coalescence with the droplet. A change in surface tension of the scrubber water can influence both steps. The coalescence process (after a particle collides with a scrubber droplet) has been described by a film-thinning model that assumes that coalescence is controlled by the thinning rate of an air or vapor layer trapped between an impacting particle and droplet. If the film thins and ruptures before the particle rebounds, coalescence occurs. The thinning model predicts that a reduction in droplet surface tension allows deeper particle penetration into the droplet. The escaping vapor film therefore has a longer more resistive path, resulting in longer thinning times, thus reduced coalescence probability. When the surface tension of a scrubber liquid is modified, collection efficiency may be slightly improved or degraded depending on the spray droplet sizes and the sizes of particles being removed.

Prepared for Environmental Protection Agency, Office of Research and Development. Contract no. 68-02-2109, program element no. EHE624A. June 1978. Includes bibliographical references.