IDEA experience in combustion improvements in large scale cooking and rural industries.
R.M.AmerasekeraExecutive DirectorIntegrated Development Associatio(IDEA)
IDEA experience in combustion improvements in large scale cooking and rural industries.
Hotels and Restaurants
Hospitals
Domestic Income generating activitiesCurd MakingTreacle makingSweetmeatLarge scale food preparation
Brick Clamps
Bakeries
Basic improvement in institutional stoves is the introduction of features such as
grate, baffle, chimney, sturdy construction, better insulationfor
improved combustion efficiency, ease of operation, less time consumptionimproved cooking hygieneLess firewood consumption
The stove dimension basically depends on the pot size which guides the grate size and primary air considerations
In general standardised and portable designs are not favoured since cooking tasks differ from place to place due to the varying nature and size of the tasks. Institutional stoves are mostly heavy mass stoves.
Prior to designing, a deep insight of the nature and requirements of the cooking task is required which calls for tailor made solutions and a good rapport with the users.Popularising institutional stoves require dissemination of stovedesigning technology through training of artisans.
Milk: 12 lts
Traditional Stove:
Firewood: 2.5 Kg
Time: 50 MtsImproved Stove:
Firewood : 1.6kg
Time: 31 Mts
Chimney, Bricks and Mud, Iron GrateNo fly ash contamination. Other biomass could be used
Using improved stove
BEFORE AFTERBiomassWeightTime
12.5 kg155 mts
6.5kg55mts
WoodWeightTime
8.5kg145mts
4.5kg50mts
24 kg of Paddy
Clay improvements:Only clay with moderate sand % is suitable
Mix clay with 20 - 30% of rice husk/sawdust
Keep the mixture at least for 2 days to dry
Make the bricks using the moulds.
Dry the unfired bricks for at least 3 days.
Stacking and firing improvements.Method of stacking bricks modified
Additional Firing channels are provided
The interlayer gaps are filled with rice husk
Firing methods are changed
Fuel Used
Firing with rice husk only.
Firing with firewood. Additional channels used
Firing with fire wood and rice husk
Stacking depends on the method of firing
AdvantagesLow cost of production
Better quality of bricks
Less or no firewood used
Less clay used
Light weight bricks with high porosity
Less labour intensive due to better drying, easy demoulding, less tending of fire and easy handling
Less breakage
Major disadvantage
Ash management and disposal
Modifications
A hopper to feed the rice husk and blower powered with a 1.5 hp motor or with a hand tractor. Additional opening is made opposite the normal opening or on the side.
Two chimneys 16 ft tall are provided above the two openings
Cost USD 800. Subsidy provided: USD 250
To start the oven next day ignite the rice husk settled on the oven floor with a little dry biomass. When it ignites blow the rice husk using the motor/blower or a hand tractor. When the temperature rise to 350oC stop blowing. Remove the ash and the oven is ready for baking again.
After modifications use firewood as usual for the first firing. Bring up the temperature to 3500 C. Remove all ash. Bake the bread at around 3000 C.
After the baking is over remove the bread and allow it to cool to around 200 C. Blow a little bit of rice husk into the chamber. Close it. Leave it overnight.
Ash disposal ?Fly ash is an environmental and health hazard. Partly carbonised(black) ash could be used as fertiliser. Water is poured on the hot ash before it cools down and forms white ash.
BEFORE BEFORE BEFORE --- FIREWOODFIREWOODFIREWOODAfter After After --- ElectricityElectricityElectricity
Rice husk Rice husk Rice husk --- No costNo costNo cost
Rs 100 - 200 55%
Rs 200 - 300 35%
Rs 300 - 500 15%
< Rs 25 80%
Rs 25 - 50 15%
Rs 50 - 75 5%
20 bakeries converted