Ethylene glycols $($monoethylene glycol, diethylene glycol and triethylene glycol$)$ are prepared by

a process involving a two$-$stage reaction system, the first being the direct oxidation of ethylene

with air or oxygen followed by absorption of ethylene oxide in an aqueous stream and the second

being the reaction of ethylene oxide with water. Ethylene glycols produced in this second reactor

are first passed through an evaporator where the water vapour is removed. The glycols taken

from the evaporator are then fed to a distillation train where monoethylene glycol, diethylene

glycol and triethylene glycol are produced.

Your task in this assignment is to make a preliminary design of the process for producing high

purity MEG and DEG $($min$.99\mathrm{.}8$mol$\%$ each$).$ The feed to the distillation train coming from the

evaporator has the following composition:

$0\mathrm{.}06$mol$\%$ water

$90\mathrm{.}98$mol$\%$ monoethylene glycol $(MEG)$

$8\mathrm{.}52$mol$\%$ diethylene glycol $(DEG)$

$0\mathrm{.}44$mol$\%$ triethylene glycol $(TEG)$

To avoid reactions of glycols in the columns, it is recommended to keep column temperatures

below $170C.$ Doing preliminary calculations on the columns, draw a flowchart of the process and

label all streams with approximate flowrates, compositions, temperatures and pressures. Explain

and justify all your choices.