Need help with my design !!

[distillerboy]

Here is the diagram of my still, packed column with raschig rings, 10 inch column, i use 750 Kg Boiler for the heat source.

The problem is, when I try to distill my cassava wash at about 5-10% wash, i always hit at temp. 80 C, and continue to go up, and in 10 minutes, it will hit 96 C, and the automatic temp control is useless, the temp keep going up, and I only got about 70 % product and keep going down and at 96 C, it only 20%, what is the problem with my still, pls help