Which of the following is categorized as an indirectly fired furnace ?
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Answer: A. By-product coke oven
Explanation
By-product coke ovens heat coal indirectly through solid refractory walls separating the flues and chambers. Indirect heating ensures that combustion gases never come into direct contact with the coal charge. This separation allows the recovery of valuable volatile by-products driven off during the carbonization process. Indirectly fired furnaces isolate the heating medium from the material being processed to prevent contamination. Coke oven batteries consist of narrow vertical chambers heated by gas combustion in adjacent flues. Refractory bricks must possess high thermal conductivity and structural integrity at elevated temperatures.
Metallurgical coke production requires strict isolation of coal from combustion products to yield quality coke. Capturing chemical by-products from coking gases provides important feedstocks for the chemical industry. Proper temperature regulation across the refractory walls prevents localized overheating and structural damage. Calcination kilns often operate as directly fired units where combustion gases contact the minerals. Sintering furnaces utilize direct ignition and down-draft combustion through the raw material bed. Open hearth furnaces directly expose the steel bath to burning fuel flames and roof radiation.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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