The diagram shows three temperature zones inside a blast furnace, labelled X near the top, Y in the middle and Z near the base where hot air enters. At whic...
Question 1 Report
The diagram shows three temperature zones inside a blast furnace, labelled X near the top, Y in the middle and Z near the base where hot air enters. At which labelled zone is the temperature highest?
Answer Details
The temperature inside a blast furnace is highest where the fuel is burning fastest, which is at the base where the hot air blast enters through the tuyeres. There the coke burns in a plentiful supply of oxygen, C + O2 → CO2, a strongly exothermic reaction that raises the temperature to roughly 1500 ℃, hot enough to keep the iron and slag molten so they can be tapped off.
The zone near the base is therefore the hottest, and the temperature falls steadily towards the top as the rising gases give up their heat to the descending ore and limestone.
Choosing a higher zone usually comes from thinking hot gases rise and so must be hottest above; they cool as they climb.
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