The carriers reduce transport costs and good combustion characteristics allowing
them to be utilised in engines and turbines because of their high density (Yaman
2004). Thermochemical biomass conversion processes include carbonisation, gasification, liquefaction and pyrolysis. Carbonisation, gasification and liquefaction
produce activated charcoal, syngas and bio-oil, respectively. But, pyrolysis produces
bio-char, bio-oil and syngas simultaneously (Bridgwater 2012). Hence, pyrolysis
received attention in bio-energy research.
Pyrolysis is the process of heating at high temperature and pressure in the absence
of or limited oxygen. Temperature and residence time decide the quality and
proportion of product. Longer residence time and lower process temperatures are
optimum for charcoal production. Short residence time and moderate temperature
favour the production of bio-oil. Longer residence time and higher temperature
enhance syngas synthesis. But, all the three products are always produced with
varied composition and process parameters (French and Czernik 2010). A more
comprehensive understanding of the physical and chemical properties of thermal
reactions allowed the improvement of nuclear reactors (Carlson et al. 2008).
Teak (Tectona grandis) is native to South and Southeast Asian countries such as
India, Sri Lanka, Indonesia, Malaysia, Thailand, Myanmar and Bangladesh. It is also
cultivated in some parts of Africa. It is one of the crucial lignocellulosic biomass
valued for its water resistance and durability (Ismadji et al. 2005). It contains
predominantly hemicellulose, cellulose and lignin. Being a species of hardwood, it
contains more cellulose and lignin and less hemicellulose. The mechanism of
biomass pyrolysis is explained as follows: Moisture evaporates completely at around
120
C and then decomposition of hemicellulose starts at around 250
C followed by
cellulose and lignin at around 350 and 500
C, respectively. When temperature
reaches 500
C during heating, the pyrolysis reactions are nearly completed (Miura
et al. 2004).
Hence, the present work aims at developing a mathematical model for pyrolysis
of teak sawdust. The objectives of the present work are to (1) perform experimental
studies to collect data on weight loss of teak sawdust as a function of time at different
temperatures, (2) develop a mathematical model for pyrolysis of teak sawdust and
(3) evaluate activation energy for teak sawdust pyrolysis.
12.2 Materials and Methods
12.2.1 Materials
Waste teak biomass was collected from Forest College and Research Institute,
Mettupalayam, Coimbatore district, Tamil Nadu, India. It was dried to constant
weight in hot air oven (Narang scientific works Private Limited, New Delhi) at
60
C for 48 h. It was crushed into small pieces in jaw crusher (Almech Enterprises,
Coimbatore) and then sieved to obtain (À52 + 60) mesh particles in gyratory sieve
shaker (Lawrence and Mayo (India) Private Limited, Mumbai). Finally, particles are
transferred to airtight cover for further experimental studies.
326
S. Aswin et al.
them to be utilised in engines and turbines because of their high density (Yaman
2004). Thermochemical biomass conversion processes include carbonisation, gasification, liquefaction and pyrolysis. Carbonisation, gasification and liquefaction
produce activated charcoal, syngas and bio-oil, respectively. But, pyrolysis produces
bio-char, bio-oil and syngas simultaneously (Bridgwater 2012). Hence, pyrolysis
received attention in bio-energy research.
Pyrolysis is the process of heating at high temperature and pressure in the absence
of or limited oxygen. Temperature and residence time decide the quality and
proportion of product. Longer residence time and lower process temperatures are
optimum for charcoal production. Short residence time and moderate temperature
favour the production of bio-oil. Longer residence time and higher temperature
enhance syngas synthesis. But, all the three products are always produced with
varied composition and process parameters (French and Czernik 2010). A more
comprehensive understanding of the physical and chemical properties of thermal
reactions allowed the improvement of nuclear reactors (Carlson et al. 2008).
Teak (Tectona grandis) is native to South and Southeast Asian countries such as
India, Sri Lanka, Indonesia, Malaysia, Thailand, Myanmar and Bangladesh. It is also
cultivated in some parts of Africa. It is one of the crucial lignocellulosic biomass
valued for its water resistance and durability (Ismadji et al. 2005). It contains
predominantly hemicellulose, cellulose and lignin. Being a species of hardwood, it
contains more cellulose and lignin and less hemicellulose. The mechanism of
biomass pyrolysis is explained as follows: Moisture evaporates completely at around
120
C and then decomposition of hemicellulose starts at around 250
C followed by
cellulose and lignin at around 350 and 500
C, respectively. When temperature
reaches 500
C during heating, the pyrolysis reactions are nearly completed (Miura
et al. 2004).
Hence, the present work aims at developing a mathematical model for pyrolysis
of teak sawdust. The objectives of the present work are to (1) perform experimental
studies to collect data on weight loss of teak sawdust as a function of time at different
temperatures, (2) develop a mathematical model for pyrolysis of teak sawdust and
(3) evaluate activation energy for teak sawdust pyrolysis.
12.2 Materials and Methods
12.2.1 Materials
Waste teak biomass was collected from Forest College and Research Institute,
Mettupalayam, Coimbatore district, Tamil Nadu, India. It was dried to constant
weight in hot air oven (Narang scientific works Private Limited, New Delhi) at
60
C for 48 h. It was crushed into small pieces in jaw crusher (Almech Enterprises,
Coimbatore) and then sieved to obtain (À52 + 60) mesh particles in gyratory sieve
shaker (Lawrence and Mayo (India) Private Limited, Mumbai). Finally, particles are
transferred to airtight cover for further experimental studies.
326
S. Aswin et al.