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Vertical
Shaft Brick Kiln Technology
Vertical shaft brick kiln technology developed
in China is an energy efficient, environment friendly and
economically viable means to produce quality bricks. It consists
of one or more shafts located inside a rectangular brick structure.
The shafts are 1 metre wide with nominal lengths of 1m, 1.5m,
1.75m or 2.0m. The inside surface is a brick wall, sometimes
lined with refractory bricks. The gap between the shaft wall
and outer kiln wall is filled with insulating materials -
clay and rice husk, etc. The shaft is loaded from the top
with a number of batches of bricks for firing. Each batch
contains four layers of bricks set in a predetermined pattern.
The stack of bricks rest on square support bars (which can
be removed or inserted) resting on a pair of horizontal beams
across the arches on the unloading tunnel. During operation,
one batch of dried is loaded at the top at a time. A weighed
quantity of powered coal (<6mm) is spread on each layer
uniformly to fill the gaps. The brick unloading is done from
the bottom using a trolley which runs on rails along the length
of the unloading tunnel. Lifting and lowering of the trolley
is done using single screw unloading mechanism. For unloading,
the trolley is lifted so that the whole stack of bricks in
the shaft rests on it. The stack is then lowered till the
layer with openings appears, through which the support bars
are then reinserted. On further lowering, the load of the
stack is taken by the support bars except for the batch being
unloaded which comes down along with the trolley which finally
rests on a pair of rails. The trolley is later pulled to along
the rails and the bricks subsequently unloaded and sorted
out for despatch.
The next batch is loaded at the top using
green bricks lifted upto the loading platform. The frequency
of unloading-loading varies from 90 to 150 minutes. The skill
in operation is to keep the firing zone in the middle of the
shaft. The draught of air moving up from the bottom cools
the fired bricks in the cooling zone and itself gets heated.
Maximum temperatures of upto 1000 degree centigrade are attained
in the central firing zone. The hot gases moving upwards dry
and heat up the green bricks in
the preheating zone. This recovery of sensible heat accounts
for the high energy efficiency of the vertical shaft brick
kiln technology.
Environmental
Aspects: Environmentally sound technology. Conventional
burnt clay bricks will continue to be the main walling material
required in meeting the huge demand for housing, in the foreseeable
future notwithstanding substantial efforts to develop alternatives.
Current technologies for brick production such as clamps,
downdraught kilns and Bull's trench kilns consume large quantities
of fuel such as coal, firewood and other biomass. The devastating
effect of the pollution caused by huge amount of emissions
from the brick industry has attracted the attention of regulatory
agencies who have issued deadlines after which the polluting
kilns are to "clean up or close down".
Performance
guarantee available: Yes
Construction
- High Energy efficiency
- Less polluting emissions
- Better quality bricks compared to clamps
- Occupies less space - low land requirement
- Can work throughout the year subject
to availability of green bricks and market.
- Minimal maintenance requirements
- Flexibility in volume of production
- Highly suitable where part of fuel
is traditionally mixed with clay
- Construction and operation easy to
learn.
- Cost:Rs.2.50 Lakh for a 2 shaft
kiln
Production Capacity: 4000
bricks/day 1batches/day depending upon shaft size. Can be
downscaled or upscaled to suit requirement.
Stage of Development:
Commercialised
Inputs Required
Raw Materials Clay, water and aggregate
Transfer Forms: Know-how,Training,Consultancy,Production
Equipment,Technical Assistance
Main Application:
Construction/Mining/Transport
Source: Technology
Bureau for Small Enterprises
APCTT Building, Qutub Institutional Area
P.O. Box – 4575
New Delhi – 110016, India
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