chapter, there are some aspects being described such as experimental setup, the
procedures to conduct the experiment and analysis method. In this experiment,
the main sample that being used is crude oil which is about 20g of crude oil
and the crude oil is being tested for the viscosity and the wax appearance
temperature (WAT) at vary temperature from 5°C to 20°C where the interval
between each temperature is about 5°C. The result of the tested samples been
analyzed by comparing with the properties of WAT of crude oil and the viscosity
of crude oil. The data is being tabulated in manually form by plotting graph and
Research Surface Methodology (RSM).
The main material that was used
in this experiment is the crude oil that is obtained from Sabah, Malaysia.
Thus, the type of crude oil is known as Malaysian crude oil where they contain
higher fractions of asphaltene compared to the wax fraction.
wax inhibitor that had been using is ethylene vinyl acetate (EVA). EVA is a
type of polymer that can increase adhesion process to the surface of wax
molecules. Thus, the size of the wax particles can be prevented from growing
and forming a big structure of crystals that can cause heavy deposition. EVA
that been used in this experiment is EVA with 40% wt vinyl acetate. This is
because past researchers commonly used EVA 32%wt and 40wt% and the availability
of EVA 40wt% is higher than the others EVA.
Figure 3.1: The type of EVA that used for this
used solvent for the EVA for this experiment is Methylcyclohexane (MCH).The
melting point of EVA40 is at around 46-47.5?. Thus to ensure EVA fully dissolved in the organic
solvent as the reaction occurs at very high temperature, the boiling point of
the organic solvent should be more than the melting point of the EVA. So, MCH
is the one of suitable organic material as they have a higher boiling point
which is at 84°C.
Figure 3.2: The
(MCH) used in this
The most appropriate inhibitor forasphaltene
is toluene but in this experiment, butanol is actually used together so that
the comparison of the aromatic and non-aromatic compounds can be studied on the
effect on viscosity and the WAT temperature. These types of solvents were used
to decrease the formation of crystals of asphaltene and increase the adhesion
process to the surface of the asphaltene so that flocculation was prevented on
the surface of the crude oil.
The main equipment is viscometer
and they play a vital role in this experiment results. The viscometer is used
to obtain the results for the viscosity of the crude oil samples that are being
mixed with the different formulation of inhibitors. The viscometer used is the
Brookfield Programmable Viscometer DV-II + PRO. The standard settings of the
equipment are as below.
1.1: Standard settings of viscometer
proper method to obtain accurate reading ensures that the viscometer is
auto-zeroed before testing the new samples and at different temperature
intervals. The viscometer should be left around 10 minutes before using them as
a pre-warm up for the device so accurate readings can be obtained at the end of
the experiment. The spindle for the viscometer should be handled carefully
because it is very sensitive and can break if being handled carelessly beside
ensure the calibration of the crude oil is not affected.
Figure 3.3: The DVII + Pro
used to measure viscosity.
next equipment used is Binder Oven. This oven is used to heat the crude oil
pre-night until they reach 90°C before mixing with the inhibitors the next day.
Figure 3.4: Diagram of Binder Oven for
heating the crude oil
The function of hot plate stirrer in
this experiment is to provide a temperature of 70 -90? during the mixing of EVA, MCH and toluene and
butanol, and also during the mixing process of crude oil and the different
formulation of inhibitors.
Figure 3.5: The cimarec hot
important equipment that was used in this experiment is water bath. The role of
the water bath is to decrease the temperature of the samples gradually as
intervals around 5°C between the two temperatures and the temperature range is
between 5°C and 20°C during the experiments. The type of thermometer used to
measure the temperature of the samples is digital temperature.
Figure 3.6: Water bath used to control
A mass balance is used to measure the
weight of EVA which is around 20 g so that a more accurate weight of EVA is
obtained. The digital micropipette is used to obtain the accurate readings for
the solvents that come in liquid form.
Figure 3.7: The micropipette used for
Preparation of Chemicals and Crude Oil
The pre-step for the experiment
is that the crude oil is heated in the Binder oven at the temperature about 90? for an overnight. This step is to melt any deposition
of wax crystals that had been formed earlier and the structure of asphaltene
that being agglomerates in the crude oil. The preliminary step before this
experiment being conducted is the apparatus that will be using such as the
spindle of viscometer, measuring cylinder and pipette were heated to 60? so that the precipitation of wax and asphaltene at
the point of contact between the hot crude oil and cold apparatus can be
avoided and to obtain accurate results. Before mixing of the inhibitor together
EVA, MCH and toluene or butanol are heated in a water bath to increase the
temperature to 60?.
3.4 Preparation of inhibitor
The inhibitors were prepared by
conducting them on a hot plate at a temperature of about 90?. Instead of using the oven, using hot plate can help
to save time and space for the experiment to be conducted as the limitation of
lab equipments in preparing the chemicals. The individual chemicals, EVA, MCH
and Toluene are measured separately of its respective volume and weight in
accordance with the manipulated percentage composition. The unit for the EVA is
grams of mass while MCH is in mL and toluene and butanol in mL. The total
volume of inhibitor used is 0.4g. Thus, for example, if the percentage
composition of the samples prepared are 50% EVA, 10% MCH and 40% Toluene, then
0.2 g EVA is measured using a mass balance, 0.04 mL of MCH is measured using a
micropipette and 0.16 mL of Toluene is measured using a micropipette.
precaution step here is to replace the tube for the micropipette for each new
sample that was taken so that contamination can be avoided and accuracy of the
results obtained can be improvised .Care is taken to replace the micropipette
tube for both chemicals to avoid contamination.
The purpose of the reaction to be in high temperature which is 90 °C is
to ensure that the EVA pellets is completely melted in the inhibitors. After
complete melting of EVA occurred, then the crude oil that were placed in the
oven overnight should be mixed with the EVA and the inhibitor solutions. If the
crude oil is placed overnight, then complete dissolved wax crystal will obtained
at the next day. Later, the samples obtained should be shaken around 30 seconds
or around a minute. This is to ensure the crude oil and the inhibitors
completely mixed. Then, the samples are placed again in the oven for 15 minutes
to allow the reaction to take place.
Figure 3.8: The prepared samples
Figure 3.9: The samples heated
3.5 Experimental Procedure
prepared were tested for viscosity by using viscometer. Moreover, in this
experiment, the samples were tested for the optimum temperature for the
efficient reduction of wax and asphaltene appearance on the surface of the
crude oil. The viscosity of the samples was taken from the temperature range
from 5° C and 20° C with each every 5? intervals. The
control sample in this experiment is blank crude oil that is free from
inhibitors. The viscosity of the blank crude oil is measured after taken from
the oven at room temperature. The temperature of the sample is observed by
using the digital thermometer and the decrease in temperature gradually is
observed carefully. The step is repeated at every 5? interval until the sample temperature drops exactly
sample is immersed in an iced water bath so that the temperature can reduce to
the expected temperature. The precaution step here is during handling the
spindle of the viscometer and the temperature reading should be taken in eye
meniscus level to avoid parallax error in readings. The procedure is repeated
for each of the other samples that contain the different formulation of
inhibitors with various percent of the composition of solvents and polymers.
Before starting a new sample each time, the spindle and temperature probe is
lightly cleaned to avoid contamination of the samples.