Batch distillation with chemical reaction when takes place in the same unit is referred to
as batch reactive distillation process. The combination reduces the capital and operating
costs considerably. Among many different types of batch reactive distillation column
configurations, (a) conventional (b) inverted (c) semi-batch columns are considered
here.
Three reaction schemes such as (a) esterification of methanol (b) esterification of
ethanol (c) hydrolysis of methyl lactate are studied here. Four different types of
dynamic optimisation problems such as (a) maximum conversion (b) maximum
productivity (c) maximum profit and (d) minimum time are formulated in this work.
Optimal design and or operation policies are obtained for all the reaction schemes.
A detailed rigorous dynamic model consisting of mass, energy balances, chemical
reaction and thermodynamic properties is considered for the process. The model was
incorporated within the dynamic optimisation problems. Control Vector
Parameterisation (CVP) technique was used to convert the dynamic optimisation
problem into a nonlinear programming problem which was solved using efficient SQP
(Successive Quadratic Programming) method available within the gPROMS (general
PROcess Modelling System) software.
It is observed that multi-reflux ratio or linear reflux operation always led to better
performance in terms of conversion, productivity for all reaction schemes compared to
that obtained using single reflux operation.
Feed dilution (in the case of ethanol esterification) led to more profit even though
productivity was found to be lower. This was due to reduction in feed price because of
feed dilution. Semi-batch reactive distillation opertation (for ethanol esterification) led
to better conversion compared to conventional batch distillation, however, the total
amount of acetic acid (reactant) was greater in semi-batch operation. Optimisation of
design and operation (for ethanol esterification) clearly showed that a single cloumn
will not lead to profitable operation for all possible product demand profile. Also
change in feed and /or product price may lead to adjust the production target to
maximise the profitability.
In batch distillation, total reflux operation is recommended or observed at the begining
of the operation (as is the case for methnaol or ethanol esterification). However, in the
case of hydrolysis, total reflux operation was obseved at the end of the operation. This
was due to lactic acid (being the heaviest) was withrawn as the final bottom product. / Libyan Petroleum Institute
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/4296 |
| Date | January 2010 |
| Creators | Edreder, E.A. |
| Contributors | Mujtaba, Iqbal M., Emtir, M. |
| Publisher | University of Bradford, School of Engineering, Design and Technology |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Thesis, doctoral, PhD |
| Rights | <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>. |
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