Question

Why is the middle portion in a continuous kiln widened?

(a) To accommodate more fuel

(b) To collect lime at bottom

(c) To allow the flow of limestone from top

(d) To accommodate hot gases of combustion

The question was asked in a national level competition.

My doubt stems from Calcination and Slaking of Lime in division Materials for Construction of Basic Civil Engineering

Answer 1

Right option is (d) To accommodate hot gases of combustion

To elaborate: The kiln has two sections – upper one to store limestone and lower one to collect lime.  As burning continues, hot gases are releases.  These are then accommodated in the middle portion.