Roxul Industrial Insulation Process - Manual (Page 72)

Insulation of boil
er
s
1.6.2 Supercritical steam generators
In the modern energy and heat economy,
super critical steam generators, which burn
fossil fuels such as mineral coal, brown coal,
anthracite etc. are used to generate steam to
operate steam turbines. In current utility steam
boilers, up to 3,600 t steam is generated per
hour under pressures of 4350 PSI (300 bar) and
steam temperatures of 1150 °F (620 °C). The
most common type is the Benson boiler, that is
operated by forced circulation (with boiler feed
pumps). In contrast to fire tube boilers, the water
or vapor is not located in the vessel, but in pipes,
which are fitted in gas-tight, welded tube-fin
constructions and form the walls of the boiler.
Generally constructed as single-pass or two-pass
boilers, these boilers reach levels of up to 560 ft
(160 m), depending on the fuel used. The bottom
contains the furnace, where finely ground fuel is
burned. The flue gases flow through the boiler
and heat the water in the pipes, thereby causing
it to evaporate. The boiler casing is suspended
on a frame and can compensate for any thermal
expansions that occur during operation (vertical
and horizontal expansions). These types of
expansions must be
considered during the design
of the insulation system. The following diagrams
show the most important technical
components in
the insulation of a boiler.
Buckstays (Girders)
Buckstays (sometimes referred to as Girders,
Stiffeners or Ribs) are fitted horizontally at regular
intervals around the boiler. Buckstays are
reinforcement elements, which prevent the boiler
from bulging. A distinction is made between hot
buckstays, which are located inside the insulation,
and cold buckstays, which are located outside the
insulation sections.
Dead spaces
Dead spaces are located in front of the boiler wall
or boiler roof, where installation components such
as collectors, distributors or pipes are fitted. The
dead spaces are located inside the insulation.
Insulation works on a fire tube boiler with
ProRox
® insulation
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