Question

Where does the maximum temperature is generated in a blast furnace?

• A. In the mantle region
• B. In the hearth region
• C. In front of the tuyeres
• D. In the bottom stack region

Hint:

Heat is generated by combustion. To find the hottest spot in any furnace, locate the primary combustion zone. In a blast furnace, this is where the fuel (coke) meets the injected hot air (tuyeres).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
A blast furnace has a distinct vertical temperature profile, with the temperature being lowest at the top where raw materials are charged and highest near the bottom where combustion and melting occur. The question asks for the specific location of the peak temperature.

Step 3: Detailed Explanation:
The generation of heat in a blast furnace is dominated by the combustion of coke and auxiliary injectants (like pulverized coal).

• This combustion happens where the fuel (coke) meets the oxidant (hot blast).

• The hot blast is injected into the furnace through water-cooled nozzles called

tuyeres, located around the circumference of the furnace at the top of the hearth.

• In the space immediately

in front of the tuyeres, a highly turbulent, high-temperature zone called the "raceway" is formed. Here, the carbon in the coke reacts exothermically with the oxygen in the hot blast: \( \text{C} + \text{O}_2 \rightarrow \text{CO}_2 + \text{Heat} \).

• This reaction releases a massive amount of energy, generating the highest temperatures in the entire furnace, which can exceed 2000°C (3600°F).
Let's consider the other regions:

• Hearth region: This is below the tuyeres and is a collection zone for molten iron and slag. It is very hot, but slightly cooler than the raceway above it.

• Mantle region and bottom stack region: These zones are above the tuyeres. The temperature decreases as you move up from the tuyere level because the hot gases are transferring their heat to the descending burden.

Step 4: Final Answer:
The maximum temperature in a blast furnace is generated in the raceway zone, located directly in front of the tuyeres, due to the intense combustion of coke.