TOP‐LIT‐UPDRAFT (TLUD) TYPE GASIFIER FOR CARBONIZED COAL

by Alexis Belonio, Immanuel Ginting, Djoewito
Atmowidjojo, and Bony Minang
Coal is a promising fuel to supplement other fuel sources
for domestic cooking. This is especially true in Indonesia
where coal is available in large quantity, about 12 billion
metric tons. Carbonizing coal increases its carbon content
and, at the same time, reduces the presence of harmful
substances in it, which is very evident when the coal is
used in an ordinary directcombustion stove. This
carbonized coal was successfully developed by a group of
researchers at the Center for Metallurgy in PUSPIPTEC,
Serpong, Tangerang, Indonesia. And in order to utilize
this carbonized coal for domestic cooking, a top-lit up-draft
(TLUD) type gasifier stove was designed and developed by
the Research and Development Division, PT. Minang
Jordanindo Approtech, Jakarta Selatan,
Indonesia. The performance of the stove was
evaluated with the assistance of Franciscus Trya
Garleman and Daniel Belonio.
The TLUD Type gasifier stove for carbonized
coal is basically a modified version of the stoves
developed by Dr. Tom Reed and Dr. Paul
Anderson of USA for wood fuel. It consists of
the following basic components: (1) Gas Burner,
(2) Fuel Reactor, (3) Insulation, (4) Cover, (5)
Grate, (6) Ash Chamber, and (7) Fan. The gas
burner is a modified version of the burner usedfor the rice husk gas stove, where secondary
air is injected from the peripheryof the burner plate. The fuel reactor is an 8-cm diameter by
20-cm high stainless steel tube, where the fuelis gasified by introducing limited amount of
air. The reactor is providedwith insulation, using rice huskask and cement mixture as
refractory material. The cover isused to close the reactor. Beneath the reactor is a grate,
made of stainless steel perforated sheet, to hold the fuel. The ash chamber is where the byproduct of gasification is discharged right after operation, and issubsequently disposed. And
the fan is used to supply the air needed for gasification.
The stove was tested using direct carbonized coal (DCC) and indirect carbonized coal (ICC)
as fuel. The direct carbonized coal was obtained by carbonizing raw coal at about 600 to 700°
C flame temperature, whereas the indirect carbonized coal was obtained by burning the coal
inside a metal container of the same temperature to control the removal of volatile matters.
Schematic Drawing of the Stove
1
2
3
4
5
7 6
Results show that either type of carbonized coal
can be successfully gasified in the TLUD gasifier,
with pinkish-blue flame color. Fuel consumption
rate of the stove ranges from 0.58 to 0.72 kg/hr and
is found to be higher for ICC as compared with that
of DCC. The specific gasification rates of the stove
are 115 kg/hr-m
2
and 143 kg/hr-m
2
for DCC and
ICC, respectively. It was also found out that both
types of carbonized coal are quite difficult to ignite
when using either
paper or kerosene as
igniter. Using 20
grams of small
pieces of wood
charcoal, however,
was found to be a
good igniter for the
coal, which only
takes 1 to 2 minutes
to ignite. The
temperature of the
burning coal, which
was measured inside
the reactor using
pyrometer, ranges
from 700 to 900°C. On the other hand, the flame temperature which was measured at the
bottom of the pot ranges from 400 to 600°C and was found higher for DCC. The thermal
efficiencies of the stove using carbonized coal are 26.7% for DCC and 28.0 % for ICC. One
and a half liters of water can be boiled within 9 and 8 minutes for DCC and ICC, respectively.
During the testing, undesirable odor was smelled from the gas emitted when operating the
stove using DCC but no undesirable odor was smelled when using ICC.
The stove costs about Rp120.000,00 per unit (1US$=9630Rp), which is competitive with the
prices of similar stoves in Indonesia. Comparing with other conventional stoves, the
carbonized coal gasifier stove has an operating cost of Rp1,189.86 per hour while Rp1,552.42
per hour and Rp1678.11per hour for kerosene and LPG stoves. The investment cost for the
stove can be recovered within 6 months.
Further information regarding the stove canbe obtained from the President Director, PT
Minang Jordanindo Approtech, ADHI GRAHA Bldg., 15
th
Floor Suite 1502A, Jl Gatot Subroto Kav.
56, Jakarta Selatan 12950, Indonesia. Telephone: 62-21-5262545, Fax: 62-62-215262416; and
Email: mjapprotech@yahoo.com  while info regarding carbonized coal can be obtained from the
Head, Extractive Metallurgy Division, Metallurgy Research Centre, Indonesian Institute of
Science, Serpong, Indonesia. Telephone: 62-21-7560911, Fax: 62-21-7560553, Email:
immanuel1951@yahoo.com.