Roxul Industrial Insulation Process - Manual (Page 78)

1. System solutions
Insulation of
flue gas duct
s
1.7 Insulation of flue gas ducts
Burning fossil fuels produces flue gases, which
are guided through flue gas ducts through the
various cleaning stages, such as denitrification
(DENOX) desulfurization (DESOX) and dust
removal (EN), discharged into the atmosphere.
Large sections of flue gas ducts are often located
outdoors. They are subject to an extent to both
internal and external extreme conditions.
The effects of external atmospheric influences,
such as wind and rain, as well as varying ambient
temperatures on the flue gas duct, can lead to
intense cooling of the flue gases internally, and
therefore to the accumulation of sulphuric acids,
which facilitate corrosion.
Insulation systems on flue gas ducts have the
following purposes:
Reduce heat losses in the flue gas, thereby
preventing sub-dew point (acid or water dew
point) conditions in the flue gas on the interior
surfaces of the flue gas duct. This also
minimizes the corrosion risk. This also applies
to areas with structural thermal bridges, such
as support constructions, reinforcements etc.
Reduce the heat losses in flue gas channels of
heat recovery systems
Personal protection
Adherence to technical specifications with
regard to noise
Designs are so varied in terms of their size and
geometry, as well as the materials and layers
used, that the examples of use below cannot fully
take into account the particular circumstances of
the construction-related factors.
Determine whether the products and construction
described are suitable for the corresponding
application in each individual case. If in doubt,
consult the ROXUL
® Technical Services Team.
Furthermore, the applicable standards and
regulations must be observed.
A few examples follow:
ASTM C1696 "Standard Guide for Industrial
Insulation Systems"
ASME "Boiler and Pressure Vessel Code"
MICA "National Commercial & Industrial
Insulation Standards"
DIN 4140 (Insulation works on industrial plants
and building services installations)
AGI Q101 (Insulation works on power plant
components)
CINI manual: Industrial insulation
BS 5970 (Code of practice for thermal insulation
of pipe work, equipment and other industrial
installations)
PIP (Process Industry Practices)
1.7.1 Installation of the insulation
systems for flue gas ducts
ProRox ® insulation have been a proven solution for
rectangular flue gas ducts for many years. They are
flexible and can fit onto different geometries and
surface structures. ProRox
® insulation products
are non-flammable, have high maximum service
temperatures and exhibit a low thermal
conductivity across the total temperature range.
Secure the insulation to the rectangular ducts
with welding pins and spring clips. Before the
welding pins are fitted, a bonding procedure
should be determined by the plant manufacturer
and insulator, which does not damage any
corrosion coating present on the inside and
outside of the flue gas duct. For example, it may
be advisable to fit the welding pins before
installing the corrosion coating.
ProRox ® insulation should be secured to flat
surfaces with at least minimum 5 pins per board
(or 6 pins per m
2 ), and a minimum of 8 pins per
board (or 10 pins per m 2 ) on the underneath.
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