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Odour Control
The control of odorous emissions is one of
the largest environmental issues for the regulating authorities,
our clients and
the public at large. It is no surprise then that a large
component of our business is designing and installing systems
for odour reduction purposes.
To this end we have acquired
and developed a range of technologies. These include:
The selection of the correct
technology to use depends on a variety of factors including
the gas flow, the nature
of
the pollutants, the pollutant concentration, the odour
reduction requirements, the location of the installation
and others.
Using these technologies we have installed
dozens of odour control systems across a broad range of applications
and
end uses. More than just about any other application
type, successful odour control relies upon the experience
and
expertise of the system designer. In most cases the exact
composition
of the inlet gas stream is un-quantified and un-quantifiable.
Experience and knowledge are paramount. EGL has developed
the necessary level of experience and knowledge to be
able to design and install systems that will achieve the
results
expected of them.
The list here includes hydrochloric acid, hydrofluoric
acid, hydrobromic acid, chlorine, bromine, fluorine, sulphur
dioxide,
hydrogen sulphide, hydrogen cyanide, chlorine dioxide,
nitrogen oxides and more. There are applications for these
in just
about every industry sector. Applications vary from very
low flow, low concentration clean applications from storage
tank vents using water only as the scrubbing liquid through
to high flow, high concentration, particle laden applications
using a high strength slurry as the scrubbing liquid. EGL
has experience across the board.
Equipment used ranges through
standard packed tower scrubbers, venturi scrubbers, eductor
venturi scrubbers to
DynaWave® scrubbers. The scrubbing liquid can
range from water through a solution of sodium hydroxide
or sodium carbonate
to a slurry of lime or limestone. Other chemicals are used
for certain applications. The choice of scrubbing liquid
can affect the equipment selection just as much as the
nature of the gas stream itself. Special designs are also
available
for applications such as emergency chlorine systems and
low temperature NOx systems.
Nitrogen oxides (NOx) from
high temperature sources such as acid plants and gas turbines
is an application in itself.
In these applications selective
catalytic reduction (SCR) is often an appropriate choice. EGL has supplied
systems of this type for nitric acid plants in Australia.
Alkaline
Gases
The main gases of interest here are ammonia and amines.
These are typically treated in a packed tower scrubber
using an
acidic scrubbing solution. The choice of acid solution
is important as scrubbing with some acids that are reactive
with these gasses can have un-desirable side effects.
Volatile
Organic Compounds (VOC’s)
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Most VOC’s have very
low solubility is water or chemical scrubbing solutions and
as such scrubbing is not usually
an appropriate solution for these types of emissions. This
applies to compounds such as benzene, toluene, styrene,
many chlorinated solvents and the like. EGL offers
Activated
Carbon Adsorption (ACA) technology
for dealing with such applications:
EGL has applied
this technology on a variety of applications. ACA has especially
been applied widely to sewage transport
and treatment plant applications.
Mists
Mists in this context are composed of very fine liquid
droplets, typically less than 5 micron in size. These are
much harder
to collect with high efficiency than liquid entrainment,
which is taken to mean larger droplets. Mists include:
- Acid
mists from various sources - sulphuric acid, oleum, nitric
acid, chromic acid
- Organic mists – condensed
organics from asphalt handling, plastic coating operations
etc
Very
fine mists of this type are not efficiently collected by
conventional packed tower scrubbers, mesh pads or the
like. A high efficiency, purpose designed mist eliminator
is required. EGL use both Kimre pads
and Monsanto
Mist Eliminators for this purpose
and have supplied both for a variety of applications.
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