Question

Why are heavy impurities provided in the process of ball and race mill?

(a) To resist upward thrust caused by secondary air stream

(b) To resist downward thrust caused by primary air stream

(c) To resist upward thrust caused by primary air stream

(d) To resist downward thrust caused by secondary air stream

I had been asked this question during an online interview.

I want to ask this question from Pulverised Mills topic in portion Steam Power Plant of Energy Engineering

Answer 1

Right option is (c) To resist upward thrust caused by primary air stream

Explanation: The mill is provided with a means of separating heavy impurities from the coal and thus reducing wear and possible damage to the grinding element. These heavy particles resist the upward thrust caused by the primary air stream and collect in a compartment in the base of mill, and then they are removed periodically.