Wet sugar that contains 20 wt-% water is sent through a dryer in which 75 % of the water is removed. (a.) Taking a basis of 100 kg feed, calculate the mass fraction of sugar in the product that leaves the dryer. (b.) Calculate the ratio (kg removed/kg wet sugar leaving the dryer)

The mass fraction of sugar that leaves the dryer is 94%wt.

Explanation:

If the sugar contains 20%wt of water, for every 100kg of feed we have 80 kg of sugar and 20 kg of water.

The dryer will remove 75% of the water present in the feed. This equals to:

W_removed=0.75*0.20*100=15 kg of water.

Then, the output is 80 kg of sugar with 5 kg of water. That adds a total of 85 kgs.

Then, the mass fraction of sugar that leaves the dryer is:

m_s=80/85=0.94

The mass fraction of sugar that leaves the dryer is 94%wt.