Table of Contents
- 1 What is hot air blast?
- 2 What heats a blast furnace?
- 3 Why limestone is used in blast furnace?
- 4 Is hot blast same as convection?
- 5 Why carbon is used in blast furnace?
- 6 Why molten iron is the lower layer?
- 7 How is carbon monoxide produced in a blast furnace?
- 8 How is iron extracted from a blast furnace?
What is hot air blast?
Hot blast refers to the preheating of air blown into a blast furnace or other metallurgical process. Hot blast also allowed higher furnace temperatures, which increased the capacity of furnaces.
What is the purpose of hot air and coke?
Step 1 – Hot air (oxygen) reacts with the coke (carbon) to produce carbon dioxide and heat energy to heat up the furnace….Raw materials for the reaction.
| Raw material | Contains | Function |
|---|---|---|
| Air | Oxygen (O 2) | Provides oxygen to allow the coke to burn, and so produces heat |
What heats a blast furnace?
At the bottom of the blast furnace, the hot air of 1200℃ heats the materials and fuels. The hot air with a force of 4.0bar triggers such a force that the materials fly up in the air. Because of the heat, coke chemically dissolves the raw materials.
How do blast furnaces get so hot?
Basically, the blast furnace is a countercurrent heat and oxygen exchanger in which… The bosh is the hottest part of the furnace because of its close proximity to the reaction between air and coke. The iron oxides in the ore are chemically reduced to molten iron by carbon and carbon monoxide from the coke.
Why limestone is used in blast furnace?
Limestone is also used to remove impurities from the blast furnace when making iron. The impurities are mostly silicon dioxide (also known as sand). The calcium carbonate in the limestone reacts with the silicon dioxide to form calcium silicate (also known as slag).
What is hot blast function?
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Is hot blast same as convection?
HotBlast™ technology has introduced a new way of cooking, offering families a quicker and higher quality culinary experience. Fast, powerful hot air is blasted downwards directly onto the food from 52 equally distributed air holes, cooking food up to 50% quicker than a traditional convection oven.
Why is limestone used in a blast furnace?
Why carbon is used in blast furnace?
Blast furnaces operate on the principle of chemical reduction whereby carbon monoxide, having a stronger affinity for the oxygen in iron ore than iron does, reduces the iron to its elemental form.
How does a blast furnace make steel?
Hot air reaching 1200℃ is blown in from the bottom through tuyeres and chemically reacts with the materials as they fall to the bottom of the blast furnace. This process oxidizes the coke and reduces the sintered ore, creating molten iron. The molten iron is then further processed to make steel.
Why molten iron is the lower layer?
The molten iron from the bottom of the furnace can be used as cast iron. Cast iron is very runny when it is molten and doesn’t shrink much when it solidifies. It is therefore ideal for making castings – hence its name. However, it is very impure, containing about 4% of carbon.
Why was the development of the hot blast furnace important?
Hot blast also allowed higher furnace temperatures, which increased the capacity of furnaces. As first developed, it worked by alternately storing heat from the furnace flue gas in a firebrick-lined vessel with multiple chambers, then blowing combustion air through the hot chamber.
How is carbon monoxide produced in a blast furnace?
The hot air blast to the furnace burns the coke and maintains the very high temperatures that are needed to reduce the ore to iron. The reaction between air and the fuel generates carbon monoxide.
What’s the difference between an air furnace and a blast furnace?
In contrast, air furnaces (such as reverberatory furnaces) are naturally aspirated, usually by the convection of hot gases in a chimney flue. According to this broad definition, bloomeries for iron, blowing houses for tin, and smelt mills for lead would be classified as blast furnaces.
How is iron extracted from a blast furnace?
The purpose of a blast furnace is to chemically reduce and physically convert iron oxides into liquid iron called “hot metal”. The blast furnace is a huge, steel stack lined with refractory brick, where iron ore, coke and limestone are dumped into the top, and preheated air is blown into the bottom.