DESCRIPTION: Double drum cooking stove saves 10 to 15% fuel. Its insulated walls retain heat which keeps the stove warm for two to three- hours. It can be fabricated by blacksmiths with locally available metal sheet from empty drums.
CONSTRUCTION: Double drum stove is made of two cylindrical drums. The outer drum is 30 cm in diameter and 35 cm in height. The inner drum is 20 cm in diameter and 25 cm in height. The outer drum is filled with wooden pieces and cheap insulating material upto 5 cm height. The inner drum is placed in the outer drum so that there is 5 cm of empty space available all around. The space between two drums is filled with any cheap insulating material upto the height of 25 cm. This exposed portion should be properly covered with metallic sheets to avoid the loss of insulating material whilst tilting the drum to remove residue after operation. Two holes of 5 cm diameter are made in both the drums on lower-side. The hole is made 5 cm above from the bottom in the outer drum where as to the inner drum, it is just at the bottom since it is placed 5 cm above the bottom of the outer drum. Corresponding holes at the same heights would serve as air-inlet openings.
WORKING: Approximately 5 cm in diameter and 10 cm long pipe (or cylindrical object) is inserted into the air-inlet pipe. Another, same diameter pipe of 32 cm long is held at the centre of inner drum touching the bottom as well as the inner end of air-inlet pipe. Fuel (wood dust, rice husk or wood shavings) is filled in the inner drum and rammed so as to provide a compact semi-solid mass all around the pipes. The pipes are slowly rotated and removed gently so that hollow cavities are preserved. A 21 cm diameter metallic cover with 5 cm diameter hole in the centre is placed on the inner drum. This is also provided with three elevated points at equal distances so that cooking vessel can easily be placed. Now the stove is ready for operation and can be lighted using small wood chips, dry leaves or even pieces of paper. The flame will be practically smoke-free. Depending on the type of fuel, one filling can be used for a duration of 2½ - 4 hours.
SOURCE: Dr. V.P.S. Sorayan, Centre for Rural Development and Appropriate Technology, Indian Institute of Technology, New Delhi- 110 016