Change of the Mineral Wool Cupola Operating Conditions During the Transition from the Open Gas Flow Mechanism to the Closed One

The widespread industrial use of cupola-type shaft furnaces requires controlling their gas-dynamic and thermal behavior. When a cupola operates with an open top, its thermal regime is characterized mainly by the peripheral flow of gases with a significant difference in the ratio of the heat capacity of gas flows to material thermal capacity. The use of forced removal of exhaust gases from the shaft furnace contributes to an earlier transition from a peripheral to a predominantly central gas flow mechanism. By increasing the degree of rarefaction at the furnace top to 0.71 – 0.73 bar, it is possible to increase the melt temperature, pressure in the furnace cavity, temperature and air blast flow, as well as exhaust gas temperature while improving the conditions of heat transfer between gases and heated materials. A continuous decrease in the productivity of the unit accompanies this process, while the melting process stability improves. A further increase in the degree of rarefaction at the top contributes to a gradual transition from the peripheral to the central gas flow mechanism with a deterioration in cupola melting performance.