Thermo chemical conversion involves the biological, chemical, and thermal breakdown of biomass. Pyrolysis is the thermal decomposition of biomass through heating in the absence of oxygen, producing biochar, bio-oil, and gases. Pyrolysis can occur through slow or fast processes, with fast pyrolysis taking seconds and yielding mainly bio-oil, while slow pyrolysis takes hours and produces primarily biochar. Pyrolysis is dependent on temperature and particle size, and can convert biomass into easily stored and transported liquid fuels or soil amendments like biochar.

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.