Cross draft long-stick wood gasification technologies have reached the
pointwhere the first simple applications withminimal technical risks are
becoming commercial. The development of the technology has moved
beyond the element of the “gasifier” to the critical area of the supply of a
“clean gas,” free of particulates and tar. If this will be achieved, then the
power market will be slowly but steadily penetrated on condition that
sufficient feed stocks can be secured. The experience of gasifier userswith
regard to the effort and energy needed for wood chip preparation in a
typical gasifier has led us to the development of a gasifier suitable to work
with long-stick woody biomass as the feed material. In the spirit of using
an energy plantation for such a gasifier system, it is preferable to obtain
such sticks from the branches of trees, which can be replenished at the
plantation site in a shorter time-span as compared to big trees being cut.
For themodelling, the gasifier was divided into a fuel reserve, aflaming
pyrolysis zone, and a char reduction zone. In all the zones, the gasifier
conditions showa fairly good fit between the theoretical and experimental
values. The flaming pyrolysis time for fuel in the gasifier is 1.6 min. Eq.
(2) has the proper functional dependence on particle size, shape, density
etc. to describe the flaming pyrolysis time. The times predicted could be
too short because oxygen is not present during part of the pyrolysis. The
quality of the gas was also better in the cross draft mode due to the
cracking of tar The efficiency of the cross draft long-stick wood gasifier
was found to be 79%. The gasifier designed in the present work can be
implemented at pilot level in a small village at awood consumption rate of
10 kg/h. Thus it isworked out to be 100 kg for 10 h in twobatches per day.
The gasifier described in the present work can furnish the need of a small
village. This can operate with 3Wof blower power or other air supply to
produce 8–10 kW thermal for cooking. It is simple and inexpensive to
build. The gasifierwill bring a litre ofwater to boil in 4–10 min and can be
turned down to the simmer level for longer cooking and increased
efficiency.With the fairly satisfactory performance and ease of construction
alongwith the convenience of feed preparation, it is feel that the cross
draft gasifier with long-stick wood as feed would find abundant avenues
of applications in a rural setting for thermal, mechanical and electrical
energy delivery.
Nomenclature
Ag Cross sectional area of the gasifier (c