Methods of Shutting Down a Blast Furnace May05

Methods of Shutting Down a Blast Furnace...

Methods of Shutting Down a Blast Furnace A blast furnace, after it is blown in and the production of hot metal starts, runs for a large number of years  before it is put down for relining. This continuous run of the blast furnace is known as campaign life. In modern blast furnaces  a campaign life of 15 years to 20 years is expected. When a furnace has reached the end of its campaign, it was usually blown out/blown down. Between the blown in to blown out/blown down, the blast furnace may have to be shut down for short periods due to various reasons. The various types of shut downs of a blast furnace are described below. (Fig 1) Fig 1 Important methods of shutting down a blast furnace  Fanning Very often while running of the blast furnace, a situation can arise when the full productive capacity of the furnace is not required for a period of time. This can be due to some problems which may arise in downstream or upstream facilities. When this occurs, the problem can be solved either by the shutting the blast furnace down or curtailing the operation of the blast furnace by reducing the quantity of hot blast. The hot blast rate is usually reduced until the hot blast pressure at the tuyeres is very low. However, it is a must that a positive pressure is kept in the hot blast system to assure that there is no danger of blast furnace gas coming back from the blast furnace into the blower system. The technique of reducing the hot blast volume to less than 20 % to 25 % of normal is known as fanning. Fanning has the advantages of keeping the blast furnace gas system pressurized and furnishing...