Wet scrubbers for particulate control at coal-fired power plants are used in a few coal-fired plants with most of these installations located in the USA to capture fly ash in addition to sulphur dioxide (SO2). In the most widely used venturi scrubber, water is injected into the flue gas stream at the venturi throat to form droplets. Fly ash particles impact with the droplets forming a wet by-product which then generally requires disposal. Wet scrubbing for particulate removal depends on particle size distribution. The system efficiency is reduced as the particle size decreases. The process can also have a high energy consumption due to the use of sorbent slurry pumps and fans. The forceful contact resulting from the droplet dispersal (spray tower), contraction of the gas stream (venturi) or counter current flow (collision), removes some of the particles as well as SO2 from the flue gas. Many of the wet particulate scrubbers are designed to control both SO2 and particulates by utilising the alkaline fly ash as sorbent. Lime is frequently used to boost SO2 removal efficiencies.
Removal efficiency 90-99.9%
Particle size range 0.5 – >100 µm
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