hotblast

Hot blast is a metallurgical technique in which air used for combustion in a blast furnace is preheated before it enters the furnace. By raising the temperature of the incoming air, the chemical reactions inside the furnace proceed more rapidly, improving fuel efficiency and allowing higher production rates. The practice is central to modern ironmaking, facilitating the use of coke or coal instead of charcoal.

Origins and development: The hot-blast process was developed in the early 19th century. James Beaumont Neilson is commonly credited with inventing and patenting the method in the 1820s, introducing heated blast air into furnaces and using heat recovered from flue gases to warm the air. The invention significantly reduced fuel consumption and enabled widespread use of coke in iron production, contributing to industrial growth in Britain and elsewhere.

Principle and equipment: In a hot-blast system, air is drawn from the atmosphere, heated in specialized devices such as hot-blast stoves or regenerative heat exchangers, and then blown into the blast furnace through tuyeres. The heated air promotes more efficient combustion of the fuel and accelerates ore reduction, increasing furnace productivity. Modern implementations often employ multiple stoves in a regenerative cycle to sustain high air temperatures and continuous operation.

Impact and legacy: The hot-blast method marked a turning point in ironmaking, enabling larger, more efficient furnaces and reducing reliance on charcoal. Over time, preheating of blast air became a standard feature in blast furnace technology, with refinements in heat exchange and stove design contributing to advances in steel and iron production.