Page 59 - Industrial Plants

Wet electrostatic scr ubber (WES)

development for the abatement

of submicronic particles

A new modern electro-filter technology jointly developed in recent
years to fight PM emissions

Luigi Amato, Project Leader, R&D
Matteo Giavazzi, Head of Operations and Technology Development, Air Pollution Control Division,
Boldrocchi Group

Francesco Di Natale, Professor of Unit Operations and Sustainable Process Design,
University of Naples Federico II

ncreasingly frequent alarms due to the outbreak
of threshold limits for fine particles in the
atmosphere have been recorded in recent years.
Particulate matters (PM) consist of solid or liquid
particles suspended in the air having many
Ishapes, sizes and chemical composition (10 nm
– 100 μm). The largest of these can also be seen with
the naked eye, whereas others can only be seen
through powerful microscopes. These suspended
particles come from different sources such as natural
phenomena or anthropic processes as combustion
processes, industrial emissions, household activities,
etc.
Generally, particulate matters are classified according as power plants and industrial activities, and air quality F igure 1 - Diseases
to their size: coarse or PM (2.5-10 μm), fine or PM standards exclusively refer to the mass of PM and correlated to the level
10 2.5 2.5
(<2.5 μm), submicronic (PM ) and ultrafine (UFP, <0.2 PM , despite the danger of the finest particulate of particles
1 10 penetration into the
μm). Usually, PM and PM are used to define air matters. Although the restriction of the particulate mass
10 2.5 respiratory system.
quality, but recent studies have revealed the high concentration is not enough to limit the toxicity
toxicity of submicronic powders, suggesting the need significantly, the governmental entities comprehend the
to consider them as responsible for a significant risk to existence of a technological limitation in capturing a
exposed people. Toxicological studies have long high number of submicronic particles with existing
understood how toxicity depends on the surface area commercial solutions, especially if the economical
and the size of the particles, rather than their mass. competitiveness of industrial applications has to be
Ultrafine particles can cross cellular membranes preserved.
reaching blood circulation and giving rise to severe
damages to many organs (Figure 1)
This recognised toxicity is the reason why the most
advanced regulations on particulate control, i.e. those Electrostatic precipitators and
in force for motor vehicles, limit both the mass and Wet Scrubbers for PM removal
number of particles emitted, as it was considered the
best way to hold emissions within acceptable toxicity Two of the most consolidated technologies for
limits. particulate abatement in the industrial field are
Current regulations for stationary combustion sources, electrostatic precipitators and wet scrubbers.

INDUSTRIAL PLANTS - September 2021
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