ABSTRACT
Reactive distillation, being an
intensified process of combining reaction and distillation in a single vessel,
is an ongoing research. This work considered the use of this novel process to
investigate the esterification of a fatty acid methyl ester, an alternative
fuel, biodiesel, which is a potential economic bedrock via modelling,
simulation and sensitivity analysis in Aspen Plus. The selection of FAME was
conducted based on the source of the oil for quality biodiesel and on its
compatibility with the software; these led to the selection of oleic acid as
the fatty acid of the process. A reactive distillation process for a reaction between
oleic acid and methanol was then set up in the Aspen environment and tested for
convergence, after a successful simulation, two operating parameters (reflux
ratio and reboiler duty) were varied from 2.0-5.5 and 1350-1800 W,
respectively. Afterwards, graphical representations of composition profiles,
temperature profiles and sensitivities of mole-fraction to reboiler duty at
different reflux ratios were obtained. Results obtained showed that a reflux
ratio of 2.0 was most compatible with a reboiler duty of 1800 W to produce a
methyl oleate mole fraction of 0.7627 in the bottom product. Given the novelty
of this process in comparison with the conventional independent reaction and
separation, more experiments should be carried out to help show any discrepancy
between reality and simulation world.
CHAPTER ONE
1.0 INTRODUCTION
Modelling and simulation may enhance
the insight, clarify dependencies, predict behaviour, explore the system
boundaries; however, they will not reveal knowledge that is unknown. A model is
a reflection of the experiments that have been performed and a good trade-off
between realism and simplicity (Diran, 1999) Process engineering offers the
knowledge about an application. Understanding a process is always the basis of
modelling and control. A rigorous dynamic process model should be developed to
increase the understanding about the operation fundamentals and to test the
control hypothesis. Experimental model verification is essential to be aware of
all uncertainties and peculiarities of the process (Luyben, 1996) Generally, a
model intended for a simulation study can be a type developed with the help of
simulation software. Mathematical model classifications include deterministic
(input and output variables are fixed values) or stochastic (at least one of
the input or output variables is probabilistic), static (time is not taken into
account) or dynamic (time-varying interactions among variables are taken into
account). The solutions of modelling are often referred to as simulations, that
is, they simulate or reproduce the behaviour of physical systems and processes.
Typically, simulation models are stochastic and dynamic (Maria, 1997)
The art of foretelling and predicting
the future with the use of computers has become increasingly popular, as the
speed and memory of the machines have increased. In addition, the desire to
understand what happens in systems in which measurements are impossible or
impractical has brought about the development of many computational models.
Regardless of the aims of these computer models, they all suffer the same
drawback: uncertainty (Ekberg, 1999)
To further increase the thoroughness
of the investigation, a computer-simulated model is subjected to different
conditions of process parameters. The response and reaction of the model to
these parameters reveal parameters upon/to which the model is independent,
unresponsive or insensitive, and those to which it is easily affected or
reactive, that is, sensitivity analysis.
Attunement of the computer model to these parameters in itself is an
experiment, which helps to manifest the permissive of operating conditions
applicable to the real life version of the model
The recent shortcomings of
conventional petroleum have increased the research for alternative energy
sources, which offer a lot of promise economically and otherwise. Biodiesel is
a prominent subject in this area of research, hence the reason this project
studies. Biodiesel is considered as a “direct-pour” alternative fuel to
petroleum diesel, as it requires almost no modification to most modern diesel
engines. It can be produced locally and, therefore, reduces foreign oil
dependence. It has been reported that biodiesel combustion can result in less
air pollutant emissions, such as carbon monoxide, sulphur di- oxide, particulate
matter, hydrocarbons, but with slightly higher nitrogen oxides. Since the
feedstock of biodiesel is mostly renewable, it significantly reduces carbon
dioxide emission during its whole life cycle
Fatty acid methyl esters (FAME),
valuable oleo-chemicals and main constituent of biodiesel, can be manufactured
in a continuous process using reactive distillation. (Dimian, 2007)
Reactive distillation (RD) is the
process in which chemical reaction and separation are carried out
simultaneously within a fractional distillation apparatus. It may be
advantageous for liquid-phase reaction systems when the reaction must be
carried out with a large excess of one or more of the reactants, when a
reaction can be driven to completion by removal of one or more of the products
as they are formed, or when the product recovery or by-product recycle scheme
is complicated or made infeasible by azeotrope formation (Perry et al 1997).
With regards to fatty acid ester
production and purification, and more specifically to large-scale production of
biodiesel, it would appear that reactive distillation could provide an
efficient and integrated approach to obtain the desired fatty acid esters.
Biodiesel is a renewable, clean-burning diesel replacement that is reducing
U.S. dependence on foreign petroleum, creating jobs and improving the
environment. Technically, biodiesel is defined as a fuel comprised of
mono-alkyl esters of long chain fatty acids derived from vegetable oils or
animal fats, designated B100, and meeting the requirements of ASTM D 6751.
Computer simulations have become
increasingly popular in many different areas over the years, owing mainly to
more effective and cheaper machines. In many cases, the trend seems to be that
computer simulations are replacing experiments, at least in areas in which
experiments are very difficult, expensive or impossible. One such area is that
of attempting to foresee what will happen in the future (Ekberg, 1999)
1.1 Problem Statement
Industrially, some operators do not
operate at optimal process conditions because they are unaware of the
dependency of the process outputs upon certain parameters. To gain insight into
the favourable conditions and to make performance predictions of industrial
processes of the subject matter to different operating conditions, the
sensitivity of a simulated model process needs to be analysed.
1.2 Aim
The aim of this research is to
ascertain the behaviour of an ASPEN PLUS simulated model of a fatty acid methyl
ester reactive distillation process, when subjected to different operating
parameter conditions.
1.3 Objectives Of Study
The objectives intended to be achieved
in this work include:
1. Developing the model of the process
in Aspen PLUS environment,
2. Subjecting the model to different
operating conditions of deciding variables, and
3. Examining, discovering and
interpreting the functional response of a reactive distillation process of a
fatty acid methyl ester to these variables.
TOPIC: MODELLING, SIMULATION AND SENSITIVITY ANALYSIS OF A FATTY ACID METHYL ESTER (FAME) REACTIVE DISTILLATION (RD) PROCESS USING ASPEN PLUS
Chapters: 1 - 5
Delivery: Email
Delivery: Email
Number of Pages: 70
Price: 3000 NGN
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