Particle removal efficiency of gravitational wet scrubber considering diffusion, interception, and impaction

A method of predicting the particle removal efficiency of gravitational wet scrubbers and the particle size distribution properties, that considers di ffusion, interception, and impaction, is presented to study the particle re moval mechanisms of gravitational wet scrubbers. This method assumes a logn ormal size distribution of aerosol particles as well as three additive coll ection efficiencies. Thus, the overall collection efficiency is described a s the sum of all three. It is represented as a U-shaped curve with a minimu m in the region of around 1.0 mum in particle diameter. This allows aerosol s in the diffusion- and in the impaction-dominant regions to be removed at a higher rate compared with aerosol in the intermediate region. As aerosols pass through the gravitational wet scrubber, the geometric standard deviat ions of the size distribution of polydispersed aerosols decrease. The geome tric mean diameter of aerosol in the diffusion-dominant region increases, w hereas it decreases in the impaction-dominant region. The present study als o shows that in optimum operation conditions such as low droplet falling ve locity, small droplet size, and high liquid-to-gas flow ratio, the gravitat ional wet scrubber has sufficient ability to remove particles whose diamete rs are much smaller than 1.0 mum.