Page 52 - Biofuels Refining and Performance

Energy and Its Biological Resources 35

Dumping
ground Cold fuel gas
for Refuse
municipal
refuse Ribbon conveyor Hot fuel gas Fuel gas and oil
Motor
Dry refusel
Drier
Vibrating Pyrolysis
separator
Motor or Furnace
Big stones
and fine ash Steam Hot air
Kiln
Water
Quencher
and fuel gas oil
Blowers—hot air
Figure 1.12 Flowchart of refuse processing plant.

above 1000 C, mostly in the absence of air. The starting materials may
be any kind of organic matter, preferably waste materials like cotton and
jute sticks, corn cobs, bagasse, and many other plant and vegetation
products. In India, annually 16 million tons of rice husk, 160 million tons
of paddy straw, 2 million tons of jute sticks, and 2.2 million tons of
groundnut shells are available as agricultural by-products.
The gas can be directly used as fuel or used to drive irrigation pump
sets. Several designs are available.
Pyrolysis, a thermochemical conversion, also performed in absence
of air at a temperature of 500–600 C, yields gaseous components, hydro-
carbons, carbon monoxide, hydrogen, methane, butane, some liquids,
tars, and a little coke, all of which have very high energy content.
Starting materials are similar to those mentioned under gasification.
The vegetable matter in the municipal refuse (as much as 50%) is also
good feed for pyrolysis. Very optimistic economic analysis for the
pyrolytic process has been put forward by investigators, and a properly
designed plant, say capable of handling 250 tons of organic refuse per
day, will be fully paid off at the end of 5 years. There are 20 domestic or
family-size models suggested by organizations. As per the available
information, large-scale use of either gasifier or pyrolyser has not been
noticed so far. But for the municipalities, the responsibility of quick dis-
posal of the refuse and the environmental issues will prompt installa-
tion of such plants in the near future. One such flowchart of a model
plant is given in Fig. 1.12.

1.15 Bioluminescence
A typical natural phenomenon, probably a unique mating signal by the
“firefly,” also exists in other living species, namely, bacteria, protozoa,
fungi, and worms, in the forms that emit visible light. In most cases, the