Thermo chemical conversion

1. THERMO CHEMICAL CONVERSION

2.  Biomass origin - Resources – Biomass
estimation.
 Thermo chemical conversion – Biological
conversion, Chemical conversion
 Hydrolysis & hydrogenation, solvolysis,
biocrude, biodiesel power generation gasifier,
biogas, integrated gasification.

26.  Pyrolysis is the thermal decomposition of biomass
occurring in the absence of oxygen.
 It is the fundamental chemical reaction of both the
combustion and gasification processes and occurs
naturally in the first two seconds.
 The products of biomass pyrolysis include biochar, bio-
oil and gases including methane, hydrogen, carbon
monoxide, and carbon dioxide.
 Which can be successfully used for the production of
heat, power and chemicals.

27.  Depending on the thermal environment and the final
temperature, pyrolysis will yield mainly biochar at low
temperatures, less than 4500C, when the heating rate is
quite slow
 Mainly gases at high temperatures, greater than 8000C,
with rapid heating rates.
 At an intermediate temperature and under relatively
high heating rates, the main product is bio-oil.
 Pyrolysis offers a flexible and attractive way of
converting solid biomass into an easily stored and
transported liquid

29.  The efficiency and nature of the pyrolysis process is
dependent on the particle size of feedstocks.
 Most of the pyrolysis technologies can only process
small particles to a maximum of 2 mm keeping in
view the need for rapid heat transfer through the
particle.
 The demand for small particle size means that the
feedstock has to be size-reduced before being used
for pyrolysis.

30.  Pyrolysis processes can be categorized as slow
pyrolysis or fast pyrolysis.
 Fast pyrolysis is currently the most widely used
pyrolysis system.
 Slow pyrolysis takes several hours to complete and
results in biochar as the main product.
 Fast pyrolysis yields 60% bio-oil and takes seconds for
complete pyrolysis. In addition, it gives 20% biochar
and 20% syngas.

31.  Very high heating and heat transfer rates, which require
a finely ground feed.
 Carefully controlled reaction temperature of around
500oC in the vapour phase
 Residence time of pyrolysis vapours in the reactor less
than 1 sec
 Quenching (rapid cooling) of the pyrolysis vapours to
give the bio-oil product.

32.  Biochar can increase the available nutrients for plant
growth, water retention and reduce the amount of
fertilizer by preventing the leaching of nutrients out of
the soil.
 Biochar reduces methane and nitrous oxide emissions
from soil, thus further reducing GHGs emissions.
 Biochar can be utilized in many applications as a
replacement for other biomass energy systems.
 Biochar can be used as a soil amendment to increase
plant growth yield.

33.  Produces few air emissions due to limited use of
oxygen
 Replaces coal and natural gas as viable fuel sources,
causing a reduction in climate change
 Produces useful products for multiple applications
 Can be easily implemented in combined heat and
power
 More efficient than the Thermal power plant (70% vs.
40%)
 Pyrolysis plants are flexible and easy to operate
because they are modular.

34.  The pyrolysis process is complex and requires high
operational and investment costs.
 Further, an air purification installation is necessary in
order to further treat flue gases from the pyrolysis.
 Produced ashes contain a high heavy metal content,
depending on the concentrations in the to-be-processed
flow.
 These ashes are regarded as dangerous waste and must
also be disposed of.