tube dia of 2.5-7.5 cms, tube length of 75-200 cms and cylinderical drum dia of 1-6 metres are normally used.
area of central downtake is equal to 40 to 100% of total cross-sectional area of the surrounding tube.
liquor is inside the tube while the steam is outside the tube.
all (a), (b) & (c).
✅ The correct answer is option D.