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close this book Boiling Point No. 17 - December 1988
View the document Fault finding and fixing
View the document Stove Problems - Causes &: Solutions
View the document Is It "Fixed" ? Test It.
View the document Solving Potters' Problems
View the document Clay Properties & Formulations for Ceramic Charcoal Stove Manufacturing In Thailand
View the document "A Watched Pot Never Boils"
View the document Appropriate energy stoves - for residues plus charcoal
View the document Village Biomass Energy Needs and Tree Planting
View the document The Mesquite Tree
View the document Stove profiles - Magan Chula
View the document Subsidies: Why, Who, When, Where, How ?
View the document Supply of Metal for Jikos (Stoves) in Kenya
View the document New Stoves In Zimbabwe
View the document Carpet Makers Adopt Efficient Dye Stoves
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Carpet Makers Adopt Efficient Dye Stoves

by Andreas Bachmann

Nowadays Nepal has an estimated workforce of 50,000 people involved in carpet manufacturing. This cottage industry has become a good source of income for many families and is a remarkable foreign exchange earner for the country.

Handmade rugs have a long history. A great expansion began in the early 1960's, when several production centres were set up in the hills and some in the Kathmandu valley. Many problems had to be solved, such as the development of appropriate looms, preparing of the raw wool by carding, cleaning, and spinning.

Handmade Rugs

Initially, many traditional carpet designs were used. Then, to keep pace with a changing market reality, new designs were created by skillful artists to attract more buyers from abroad. The continued flow of raw wool, yarn, and dye is an important task even today. Carpets are made in natural colours and also in a range of many colour variations.

Dying is done in large vessels, similar to those used for cheesemaking. Contents vary from approximately 400 litres to 700 litres. These containers are filled with water, which needs to be brought to boiling point and kept at high temperature for a while in order to ensure a thorough dying process. Fuel for these operations was always wood, cut to standard length by the woodcutter.

Typically, manufacturers used a simple structure made of bricks or stones to hold the load of the vessel and its heavy contents. A great chamber beneath the vessel housed the fire.

Some also had a chimney as large as the surface of the dye pot. Smaller manufacturers used simple containers, such as half-cut oil barrels over a fireplace. However, as there were no fire grates, no door, and no damper for the airflow control, these small factories consumed a lot of firewood. Initially this did not seem to matter, since wood was always easily and cheaply available in those days.

As firewood became more expensive, fuel efficiency became more important. The improved stoves used in Swiss cheese making in mountainous places were adapted to the dye process. The design could be simplified since the dying required less demanding criteria. Much attention was given to exposing greater pot surface to the heat, but also reducing the size of the firechamber. In order to have the doors always kept closed during the firing process, the depth of the firechamber was made according to the standard length of the wood logs, ea. at least one meter, so people were not required to further cut the length of the wood. However, splitting the wood to reduce the large circumferences was a must for improved combustion.

Greater Savings

The base structure, including the firechamber, and a 3-meter chimney were made of local standard fired bricks. Each such improved fireplace also required metal parts: one large door with a frame, a cast-iron grate, and a damper. These items were standardised and made available from local workshops. Masons were trained in the specialised design and assembly of proper stove designs, incorporating these metal parts. Along with the metal parts, one stoker is supplied to enable a thorough attention to the fire and for ash removal. Stove operators had no problem with the proper understanding of these new constructions. It was easily understood that a damper had a most valuable function in regulating the flow of smoke, ie. to reduce heat loss through the chimney.

Results were quite encouraging. The performance of such stoves was further improved. As a novelty, secondary airflow pipes were introduced, fitted at levels above the fire. This was to recover even more heat from the same firewood. When the fire was left to burn to its end, a white, dusty ash was all that was left! Within a limited period several dozens of such large- sized cooking stoves were made at dye works in the Kathmandu valley. Soon the masons were travelling to Pokhara and other centres to work on proper installations. The initial costs are reasonable, and the saving of wood is reported to be easily between 50 and 65 percent as compared to the previous methods. The cost of one truck-load of firewood, nowadays about 13,500 rupees, makes the updating of such stoves quite worthwhile.

Larger manufacturers installed several of such new stoves. With their requirements of several truckloads of wood in a single month, more stoves meant a multiplying saving factor on expenditures on firewood.

This development was based on a small trial made a few years back. It was not part of a project or of an organisational structure. With a straight and direct technology transfer from one place to another a quite satisfactory and quick spreading solution has been possible. However, it shall not be considered to be the final answer to a great problem. It is hoped that even better methods will be developed in the near future and made available to the people. At any rate, it is a practical example of using already existing experiences in making an appropriate selection of design and materials. The manufacturers recognised the direct benefits and put them to use.

Positive Results

As small as the beginning may be, it is a positive sign for conservation from the commercial sector, and the environment will benefit from such developments.

Reproduced from VITA NEWS, April l988 Andreas Bachmann, a long-time VITA volunteer, has worked in Nepal for many years for UNICEF and other agencies. This article is taken from the February 2, 1988, issue of The Rising Nepal.