Vertical Shaft Brick Kiln Technology
Introduction
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
For further information please contact
Technology Bureau for Small Enterprises
APCTT Building, Qutub Institutional Area
P.O. Box – 4575
New Delhi – 110016, India
