Lime kiln designs
Practical Action
kiln, and the kiln is charged through a gate on the housing, by means of a bridge (5).
Limestone is supplied by a road vehicle from the quarry. The kiln draught is produced by a
chimney (4), 10 metres high and 0.6 metre diameter, located at the top of the housing. The
burners (6) are located 4 metres up the kiln, making the heights of the zones 5.5 metres
preheating, 2.5 metres burning, and 4 metres cooling.
There are four burners (6), two at each side, which are somewhat displaced out of directly
opposite alignment. Other features of note are the burner inspection platform (7), and the
four kiln discharge channels (8).
16 Ton per Day Kiln
(Figure 3)
The shell of this kiln is
cylindrical and made out of
sheet metal (1). An
electricity supply is
required for this kiln to
operate a forced draught
system; hence it is really a
low production, and not a
low cost kiln.
Limestone is loaded by a
pulley-operated skip hoist
(2), and the rate of charging
of stone into the kiln is
controlled by a load cell.
Discharge is by a special
gate (5), which can be
sealed against air leakage
when closed so the kiln can
be left open at the top.
Flue gas is discharged by a
chimney (3). Another
feature of this kiln is a pipe
(4) to recycle some of the
flue gas into one of three
combustion chambers (6).
The lengths of the
preheating, burning and
cooling zones are 5.5,2.5
and 4.0 metres
respectively.
Figure 3: 16 ton per day kiln.
The combustion chambers (6) are fed with fuel oil, air and recycled flue gas. The fuel oil is
gasified by the heat in the combustion chambers without the need form atomisation with
steam. A fan (8) supplies air to the combustion chamber, another fan (9) recycles flue gas to
the combustion chamber, while a third fan (7) feeds cooling air into the kiln. By controlling
the relative amounts of cooling air and recycled flue gas entering the kiln, good control over
temperature in the kiln can be obtained.
This type of kiln is very efficient in terms of its energy usage, consuming only 1100 kcal per
kilo of quicklime.
4