[daiskex16]

Hi guys! We have this problem from our problem set in Material Balance

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Ethylene chlorohydrin and glycol are produced from chlorine, water and sodium bicarbonate in the following process:

Chlorine and ethylene are absorbed in a water tower and react to yield the chlorohydrin:

C₂H₄ + Cl₂ + H₂O  ClC₂H₄OH + HCl

The exit-tower solution contains 5% by weight chlorohydrin, along with traces of ethylene dichloride as a by-product.
The dichloride is separated by decantation. This solution is now fed into a still and the chlorohydrin-water azeotrope, which contains 42% chlorohydrin and no HCl is taken as the overhead distillate product.
The still bottoms contain 1% chlorohydrin and all the HCl.
This distillate is then taken into an autoclave where the hydrolysis takes place at 150 degrees Celsius. A stoichiometric amount of bicarbonate is used:

ClC₂H₄OH + NaHCO₃  NaCl + CO₂ + HOC₂H₄OH

The Hydrochlorination reaction proceeds with a yield of 95% based on ethylene. The 5% by-product may be taken to be the dichloride. The hydrolysis yield is 90%; the other 10% of the chlorohydrin is converted to the ethylene oxide via

ClC₂H₄OH + NaHCO₃  NaCl  H₂O + CO₂ + C₂H₄O

4 kg of ethylene glycol is to be produced in a bench-scale equipment. Make a complete material balance for the system.

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I am really confused in making the figure for this problem. my first attempt was:


C2H4 ---->                     ClC₂H₄OH; HCl                               42% ClC₂H₄OH
Cl2 ------>WATER TOWER ------------->DISTILLATION TOWER------------------->
H₂O ----->          |                                      |
                          |                                     |
                          |                                     |
                       C₂H₄                       1% ClC₂H₄OH; all HCl


But my question is for the 42% chlorohydrin in the distillate and 1% in the bottom, where is the remaining 57%?

plus, I could not get this part of the problem:

The Hydrochlorination reaction proceeds with a yield of 95% based on ethylene. The 5% by-product may be taken to be the dichloride. The hydrolysis yield is 90%; the other 10% of the chlorohydrin is converted to the ethylene oxide via

ClC₂H₄OH + NaHCO₃  NaCl  H₂O + CO₂ + C₂H₄O

Help please, thank you!

[skbuncks]

But my question is for the 42% chlorohydrin in the distillate and 1% in the bottom, where is the remaining 57%?

Given that..

This solution is now fed into a still and the chlorohydrin-water azeotrope, which contains 42% chlorohydrin and no HCl is taken as the overhead distillate product.

...to what do you think the 42% refers to. Hint, it is not yield.

skb

[skbuncks]

The Hydrochlorination reaction proceeds with a yield of 95% based on ethylene. The 5% by-product may be taken to be the dichloride. The hydrolysis yield is 90%; the other 10% of the chlorohydrin is converted to the ethylene oxide via

ClC2H4OH + NaHCO3  right arrow NaCl  H2O + CO2 + C2H4O

4 kg of ethylene glycol is to be produced in a bench-scale equipment. Make a complete material balance for the system.

First things first. You need to make 4 Kg of ethylene glycol. How much ethylene would be required given that the stage yields are 95% and 90% respectively?

skb