Biomass-coal cofiring has been commonly
performed by a number of coal
power plants in Europe
and America with
a primary motivation for reducing the environmental
impact of emissions. Currently the
percentage of cofiring biomass
with coal is
still small on average below 10%. It can also occur due to
a limited supply of wood pellets. But
in terms of operational
cofiring biomass-coal
fly ash will reduce
significantly. On the other
hand, if the percentage of biomass-coal cofiring
is added will
cause deposits on
boiler pipes that
will disrupt the
process of heat transfer in the furnace causing inefficient use of fuel with one
indicated by the
high temperature of the fluegas.
There are three
techniques commonly used in biomass-coal cofiring:
1.
Mixing of
biomass and coal in the fuel handling
system (then fed to the boiler).
2.
Setting up a separate biomass with
coal, and then inject
into the boiler.
3.
Gasification of biomass to produce a
gas which is then burned in the boiler directly
or using the integrated
gasification combined cycle (IGCC) system.Worldwide reported
more than 200 coal power plant that has
been tested with biomass (IEA 2010).
Several cofiring options are available on in coal
powerplant, among others:
-Cofire with a low percentage of biomass,
with a slight modification
of the equipment.
-Cofire with a high percentage of biomass,
by upgrading equipment.
- Convert/repower individual coal burners to be fired with
biomass
- Convert/repower entire coal plants to be fired with
biomass
- Cofire with torrefiedwood
Ash content in
coal and biomass
are generally differ quite large and moreover ash chemistry are also a lot of different.
This is factor that causes
a lot or at least a deposit in the boiler pipes. Percentage of cofiring biomass-coal up to 10% is generally acceptable. Optimal percentage that causes minimal boiler tube deposits and significant reduction in fly
ash can be searched based on the variable characteristics of coal and biomass are used.
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