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 Steam
generators to 300,000 lb/h capacity
Steam
pressure up to 1500 psig
Steam
temperatures from saturation to 1000 F
Oil
and gas fired applications
Custom
designed boilers with low operating
costs and high efficiency
Convective
superheaters with longer life and higher reliability
Pictures show ABCO Packaged steam generators with front,rear and side walls of completely water cooled membrane walled design.The advantages of this design /construction feature are discussed below. |
Advantages
of ABCO Water cooled Furnaces
 One
of the recent improvements in packaged boiler design is the water cooled
furnace that offers several advantages over refractory lined furnaces.
The furnace side walls,front and rear walls and floor are of membrane wall
construction.This results in a leak proof enclosure,eliminating gas leakage
and corrosion of casing as seen in boilers with refractory.
Refractory
maintenance concerns are eliminated. Plant engineers are familiar with
the annual cost of refractory maintenance and the associated downtime.
Startup
rates can be faster without concern for refractory limited heat up rates
and hence fuel cost per startup is also reduced.The entire furnace expands
and contracts as a unit. This eliminates relative expansion problems that
occur between water cooled walls and refractory lined casings.
For
a given volume,the ABCO design has lower heat release rates on area basis
due to the larger furnace effective projected area; hence heat fluxes are
lower. Depending on the furnace dimensions,the improvement can be 5 to
15 %.The furnace exit gas temperature is also lower.
Cooling
of the flame and reradiation from refractory impact local combustion temperatures
and hence NOx formation.The contribution to NOx from the front refractory
lined wall is signifcant .A cool environment at the flame front due to
the water cooled front wall design,on the other hand, helps to lower the
emissions.
Refractory
on the floor is another design feature which has been carried over from
the last generation of boiler designs.There is no need for it.The
effective furnace projected area is reduced,increasing the furnace exit
gas temperature,thereby causing problems for the superheater if present,in
addition to increasing the redradiation from the floor which increases
the NOx.There are hundreds of boilers designed without floor refractory,which
are working fine.The problems in oil fired furnaces due to higher furnace
exit gas temperature can be more severe,such as possible slagging and corrosion
of superheaters. |
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