Hot blast

Hot blast refers to the preheating of air blown into a blast furnace or other metallurgical process. As this considerably reduced the fuel consumed, hot blast was one of the most important technologies developed during the Industrial Revolution.Hot blast also allowed higher furnace temperatures, which increased the capacity of furnaces.James Beaumont Neilson, previously foreman at Glasgow gas works, invented the system of preheating the blast for a furnace. He found that by increasing the temperature of the incoming air to 300 degrees Fahrenheit, he could reduce the fuel consumption from 8.06 tons to 5.16 tons with further reductions at even higher temperatures. He, with partners including Charles Macintosh, patented this in 1828. Initially the heating vessel was made of wrought iron plates, but these oxidized, and he substituted a cast iron vessel.For steel the hot blast temperature can be from 900 °C to 1300 °C (1600 °F to 2300 °F) depending on the stove design and condition. The temperatures they deal with may be 2000 °C to 2300 °C (3600 °F to 4200 °F). Oil, tar, natural gas, powdered coal and oxygen can also be injected into the furnace at tuyere level (near the base) to combine with the coke to release additional energy which is necessary to increase productivity.