Generation of Hot Air Blast and Hot Blast Stoves Apr18

Generation of Hot Air Blast and Hot Blast Stoves...

Generation of Hot Air Blast and Hot Blast Stoves            A hot blast stove is a facility to supply continuously the hot air blast to a blast furnace. Before the blast air is delivered to the blast furnace tuyeres, it is preheated by passing it through regenerative hot blast stoves that are heated primarily by combustion of the blast furnace top gas (BF gas). In this way, some of the energy of the top gas is returned to the blast furnace in the form of sensible heat. This additional thermal energy returned to the blast furnace as heat reduces the requirement of blast furnace coke substantially and facilitates the injection of auxiliary fuels such as pulverized coal as a replacement for expensive metallurgical coke. This improves the efficiency of the process. An additional benefit resulting from the lower fuel requirement is an increase in the hot metal production rate. All of these have a significant effect in terms of reducing the hot metal cost. History of hot blast stoves The use of blast furnaces dates back as far as early as fifth century B.C. in China. However, it was not until 1828 that the efficiency of blast furnaces was revolutionized by preheating them using hot stoves in conjunction with the process, an innovation created by James Beaumont Nielson, previously foreman at Glasgow gas works. He invented the system of preheating the blast for a furnace. He found that by increasing the temperature to 300 deg F (149 deg C), he could reduce the fuel consumption from 8.06 tons to 5.16 tons with further reductions with higher temperatures. In 1860, the cooperative use of hot stoves with blast furnaces was further transformed by Edward Alfred Cowper by recycling the top gas...