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Approximately 20% of installations are relevant to hydrogen firing greater than 50% concentration in the
fuel blend.
Maximum reported hydrogen content is 85%.

Figue 18 – Macchi Industrial Hydrogen experience

What’s the future? Conclusion
Many analysts predict a growth of hydrogen use in the Environment needs urgent solution to reduce carbon
next future. Similarly to other industrial application (like dioxide to atmosphere. From boiler manufacturer’s
gas turbine), efforts are continuously made to maximize point of view, the combustion of hydrogen in steam
the hydrogen content in fuel stream and adapt boiler generators may give tangible contribution to
design accordingly. decarbonisation. Technology and experience, to
Experiences up to 80% hydrogen content are available achieve co-firing with high fraction of hydrogen, is
but research and firing at maximum capacity is still an
on-going activity.
Even though the gap seems small, fuel blend properties Macchi is researching and studying
substantially change passing from 80% to 100%. In this MILD - flameless combustion where
respect, Macchi is making research and studies on a prototype burner has been tested
MILD - flameless combustion where a prototype burner and patented. The adoption of this
has been tested and already patented. The adoption of combustion technology permits
this combustion technology permits the achievement of the achievement of very low NOx
very low NOx emission levels without use of external emission levels without use of
flue gas recirculation or steam injection. We believe that external flue gas recirculation or
MILD will play important role in achieving 100% H steam injection
2
combustion.
available and supported by applications in large
Experiences of burning hydrogen scale. Burners may not be of conventional type and
concentrations of up to 80% are special fuel injection shall be considered; furnaces
available but research shall be enlarged progressively as hydrogen content
and development to reach increase but use of flue gas recirculation shall be
full firing at maximum evaluated to avoid excessive combustion chamber
capacity is still on-going dimensions and costly design.
NOx can be easily controlled with Ultra-Low NOx
burner and adopting external flue gas recirculation

IndustrIal Plants - May 2020
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