12.2.2 Experimental Studies
Fast pyrolysis reaction was carried out in chemical vapour deposition (CVD) tubular
furnace (VB ceramic consultants, Chennai) with an inert nitrogen gas atmosphere
maintained at a heating rate of 10
C/min. 1 g of teak sawdust was pyrolysed, and the
loss in weight of biomass was noted down as function of time at different
temperatures. The experiment was conducted till biomass weight reaches constant
value.
12.2.3 Modelling of Pyrolysis of Steak Sawdust
Biomass pyrolysis products are a complex combination of the products from the
individual pyrolysis of cellulose, hemicellulose and extractives, each of which has its
own kinetic characteristics. In addition, secondary reaction products result from
cross-reactions of primary pyrolysis products and between pyrolysis products and
original feedstock molecules. Pyrolysis of each constituent is itself a complex
process that is dependent on many factors (Collard and Blin 2014). Pyrolysis
modelling is classified into three different types: (1) one-step global models,
(2) one-step multi-reaction models and (3) two-stage semi-global models (oochit
et al. 2017; Bridgwater 2015).
The first category of models considers pyrolysis as a single-step first-order
reaction:
Primary interaction:
Virgin biomass ! gases + volatiles
Virgin biomass ! char
Secondary interaction:
Gases + volatiles + char ! char + gases
The second category of models discusses those mechanisms, which consider
simultaneous and competing first-order reactions in which virgin wood decomposes
into different constituents of pyrolysis products, namely, tar, gases and char.
The third-class models consider pyrolysis to be a two-stage reaction, in which the
products of the first reaction (tar and gases) further react with the char produced by
the second reaction to produce tar and gases and char of different compositions.
Thus, the primary pyrolysis products participate in secondary interactions causing a
modified final product distribution. As particle size increases, the residence time of
the volatiles inside the solid increases and the effect of secondary reactions also
increases (Venderbosch 2015).
During pyrolysis, biomass (B) produces tar and gases (G) and char (C), which is
represented as follows:
12 Modelling and Simulation of Pyrolysis of Teak (Tectona Grandis) Sawdust
327
Fast pyrolysis reaction was carried out in chemical vapour deposition (CVD) tubular
furnace (VB ceramic consultants, Chennai) with an inert nitrogen gas atmosphere
maintained at a heating rate of 10
C/min. 1 g of teak sawdust was pyrolysed, and the
loss in weight of biomass was noted down as function of time at different
temperatures. The experiment was conducted till biomass weight reaches constant
value.
12.2.3 Modelling of Pyrolysis of Steak Sawdust
Biomass pyrolysis products are a complex combination of the products from the
individual pyrolysis of cellulose, hemicellulose and extractives, each of which has its
own kinetic characteristics. In addition, secondary reaction products result from
cross-reactions of primary pyrolysis products and between pyrolysis products and
original feedstock molecules. Pyrolysis of each constituent is itself a complex
process that is dependent on many factors (Collard and Blin 2014). Pyrolysis
modelling is classified into three different types: (1) one-step global models,
(2) one-step multi-reaction models and (3) two-stage semi-global models (oochit
et al. 2017; Bridgwater 2015).
The first category of models considers pyrolysis as a single-step first-order
reaction:
Primary interaction:
Virgin biomass ! gases + volatiles
Virgin biomass ! char
Secondary interaction:
Gases + volatiles + char ! char + gases
The second category of models discusses those mechanisms, which consider
simultaneous and competing first-order reactions in which virgin wood decomposes
into different constituents of pyrolysis products, namely, tar, gases and char.
The third-class models consider pyrolysis to be a two-stage reaction, in which the
products of the first reaction (tar and gases) further react with the char produced by
the second reaction to produce tar and gases and char of different compositions.
Thus, the primary pyrolysis products participate in secondary interactions causing a
modified final product distribution. As particle size increases, the residence time of
the volatiles inside the solid increases and the effect of secondary reactions also
increases (Venderbosch 2015).
During pyrolysis, biomass (B) produces tar and gases (G) and char (C), which is
represented as follows:
12 Modelling and Simulation of Pyrolysis of Teak (Tectona Grandis) Sawdust
327