Fume Cleaning - Techne IFB-101 Operator's Manual

Fume Cleaning

When used for processing items which may emit toxic or inflammable fumes, it is
essential that an adequate fume extraction system be installed. A typical schematic diagram of
such a system is shown in the appendix; the system consists of the following components:-
Ductwork to connect the fluidised bath extract duct via the various fume treatment
equipment to the input of the fume extraction fan. The ductwork should include an air dilution
tee, positioned as close as possible to the fluidised bath. The dilution tee enables the fumes
within the system to be diluted with air. The ductwork should also include a damper valve which
is normally positioned adjacent to the extraction fan. This valve allows the extraction velocity to
be reduced. In general the ductwork may be manufactured out of galvanised mild steel;
however, in installations where PVC or other halogenated polymers are being processed, it is
recommended that stainless steel ducting is used.
The ductwork should be as short as possible and contain the minimum number of
bends and horizontal runs so as to reduce the possibility of a blockage.
A cyclone separator should be mounted directly after the dilution tee. The cyclone
removes any fluidised medium that may be present in the extracted fumes. The fluidised
medium is collected in the cyclone collection bin from where it may be returned to the fluidised
bath.
In applications where the components being cleaned are contaminated by polymers
which contain inorganic pigments or fillers such as titanium oxide, of a particle size less than
0.005mm diameter which will not be retained by the cyclone, it is recommended that a filtration
system be fitted after the cyclone.
In applications where the materials being treated produce acidic vapours during
thermal decomposition, it is recommended that a fume scrubber be utilised to ensure that the
final fume emission from the plant conforms with local regulations. A caustic dosing system
may also be required to ensure that the scrubbing liquid is maintained at an acceptable pH level.
An extraction fan is required in all applications to provide the motive force for the
exhaust. In applications where it is not permissible to emit visible smoke from the plant or
where local regulations specify the maximum fume concentrations that may be emitted from an
exhaust stack, an afterburner may be required. The afterburner heats the fumes to a point
where thermal incineration eliminates the visible content of the fumes while reducing the fume
concentration.Finally, an exhaust stack is required to direct the treated fumes away from the
working environment. The exhaust stack will generally be manufactured out of the same
materials as the ductwork system. However, in installations where an afterburner is fitted, the
exhaust stack should be manufactured out of insulated stainless steel.
The exact combination of fume treatment components required depends upon the
application and local conditions. Technical staff are available to discuss particular applications
and offer advice as to which combination is required.
Techne are able to offer the following fume treatment equipment:
Cyclone
Scrubber
Caustic Doser
Extraction Fan
Afterburner
I F B - 1 0 1 O P E R A T O R ' S M A N U A L
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