Furnace

A furnace, comprising a shaft loading hopper located above the combustion chamber, a heated air supply to the combustion chamber, an exhaust pipe provided with an adjustable exhaust system characterized in that an expansion chamber is located behind the combustion chamber, so that long axes of the expansion chamber and combustion chamber are coincident, the cross-section area of the expansion chamber exceeding the cross-section area of the combustion chamber, the heated air supply to the combustion chamber provides a supplied air temperature as close as possible to that of a gas from said expansion chamber and includes frontal, lateral and lower air supply, the frontal air supply to a combustion chamber includes several pipes located in an internal space of the expansion chamber, one end of each pipe is open to the atmosphere, while the other end communicate with an inlet of a corresponding through channel, which is located inside and along walls of the combustion chamber, the outlet of the channel communicates with an internal space of the combustion chamber, the lateral air supply to the combustion chamber is designed in the form of several through holes in lateral walls of the combustion chamber, allowing for the internal space of the combustion chamber communication with frontal air supply channels, the lower air supply to the combustion chamber includes several pipes located in the internal space of the expansion chamber, one end of each pipe is open to the atmosphere, while the other end communicates with the inlet of one of the corresponding through channels located inside and along a lower wall of the combustion chamber, each of the corresponding through channels communicating with the internal space of the combustion chamber via the through holes located in between.