The utilization of heat of reaction and energy optimization within ethoxylation reactive distillation(ERD)column

which involves reactions with highly thermal effect

was studied by using the mathematical model and simulation method.A typical ethoxylation system

the synthesis of ethylene glycol monobutyl ether(EGMBE)from ethylene oxide(EO)and n-butanol was employed as example. Firstly

the conventional column design

into which a reactive section was superimposed onto a stripping section

was used as a base case for analysis

and detailed simulations were carried out to investigate the influence of heat of reaction on the process performance.The results obtained showed that

by the adoption of the conventional design of ERD column

the heat of reaction was finally removed from condenser by cooling medium

i.e.

the heat of reaction could not be directly utilized in ERD column for improving the separation operation or reducing the heat duty of reboiler.Based on this

the approaches to utilizing heat of reaction was analyzed

and an internally heat-integrated ethoxylation reactive distillation structure

IHIERD

was proposed to maximize the energy efficiency of system

into which the reactive section and stripping section was partitioned into two parts with different operating pressures.In such arrangement

the heat of reaction can be allowed as heat resource to be drawn from reactive section to supply stripping section

and therefore the heat duty of reboiler in IHIERD can be reduced.The saving effectiveness of different designs was analyzed and compared by using simulations.The results obtained demonstrated that the IHIERD leads to a reduction of the reboiler temperature from 462.5 K to 420.0 K

a reduction of the heat duties of condenser and the total energy input by 11% and 14%

respectively

which indicated that the energy saving was obvious.