Particle Collection in Wet Scrubbers

Particle Collection In Wet Scrubbers

Wet scrubbers capture relatively small dust particles with large liquid droplets. In most wet scrubbing systems, droplets produced are generally larger than 50 micrometres (in the 150 to 500 micrometres range). As a point of reference, human hair ranges in diameter from 50 to 100 micrometres. The size distribution of particles to be collected is source specific.

For example, particles produced by mechanical means (crushing or grinding) tend to be large (above 10 micrometres); whereas, particles produced from combustion or a chemical reaction will have a substantial portion of small (i.e. less than 5 micrometres) and submicrometre particles.

The most critical sized particles are those in the 0.1 to 0.5 micrometres range because they are the most difficult for wet scrubbers to collect.

Droplets are produced by several methods:

1. Injecting liquid at high pressure through specially designed nozzles
2. Aspirating the particle-laden gas stream through a liquid pool
3. Submerging a whirling rotor in a liquid pool.

These droplets collect particles by using one or more of several collection mechanisms such as impaction, direct interception, diffusion, electrostatic attraction, condensation, centrifugal force and gravity. However, impaction and diffusion are the main ones.