Improvement of the Energy Efficiency of Hot Blast Stove Performance

Abstract

Steady thermal performance of a blast furnace determining its productivity and specific fuel consumption for one ton of hot metal depends on many factors. One of the main factors is the use of blast heated up to a high temperature. A continuous supply of hot blast to the blast furnace is provided by operation of the system consisting of three or four regenerative hot stoves. Energy efficiency of thermal performance of blast heating equipment significantly affects the technical and economic features of blast furnace smelting. In the total consumption of fuel equivalent, the share of thermal resources for blast heating is 10–12%. The hot blast stoves consume up to 30–35% of blast furnace gas. At present, most blast furnaces use hot blast at the temperature of 1150–1250°C; blast furnaces use hot blast stoves of different designs: stoves with an internal combustion chamber, stoves with an external combustion chamber, and top combustion or shaftless stoves (Kalugin design). The analysis of different thermal conditions in stoves has shown that Kalugin shaftless stoves are the most advanced and promising stoves in terms of energy efficiency and minimum environmental impact. The tendency for increased hot blast temperature was implemented in Kalugin stoves by means of energy efficiency improvement through the recovery of thermal energy of combustion products which are formed during checkerwork heating. The use of this energy in heat pipes for heating blast furnace gas and air supplied to the stove pre-chamber has resulted in an increase of the blast temperature and reduction of the BF gas consumption for heating. Moreover, the specific coke consumption for iron smelting was also reduced. These findings have been confirmed by heat balance analysis and by experience of commercial stove operation.