In thischapter, there are some aspects being described such as experimental setup, theprocedures 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 oiland the crude oil is being tested for the viscosity and the wax appearancetemperature (WAT) at vary temperature from 5°C to 20°C where the intervalbetween each temperature is about 5°C. The result of the tested samples beenanalyzed by comparing with the properties of WAT of crude oil and the viscosityof crude oil. The data is being tabulated in manually form by plotting graph andResearch Surface Methodology (RSM). 3.
2 ExperimentalSetup 3.2.1 Materialsand Chemicals The main material that was usedin 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 containhigher fractions of asphaltene compared to the wax fraction. Thewax inhibitor that had been using is ethylene vinyl acetate (EVA). EVA is atype of polymer that can increase adhesion process to the surface of waxmolecules. Thus, the size of the wax particles can be prevented from growingand forming a big structure of crystals that can cause heavy deposition. EVAthat been used in this experiment is EVA with 40% wt vinyl acetate.
This isbecause past researchers commonly used EVA 32%wt and 40wt% and the availabilityof EVA 40wt% is higher than the others EVA. Figure 3.1: The type of EVA that used for thisexperiment Theused solvent for the EVA for this experiment is Methylcyclohexane (MCH).
Themelting point of EVA40 is at around 46-47.5?. Thus to ensure EVA fully dissolved in the organicsolvent as the reaction occurs at very high temperature, the boiling point ofthe organic solvent should be more than the melting point of the EVA. So, MCHis the one of suitable organic material as they have a higher boiling pointwhich is at 84°C. Figure 3.2: TheMethylcyclohexane (MCH) used in thisexperiment The most appropriate inhibitor forasphalteneis toluene but in this experiment, butanol is actually used together so thatthe comparison of the aromatic and non-aromatic compounds can be studied on theeffect on viscosity and the WAT temperature. These types of solvents were usedto decrease the formation of crystals of asphaltene and increase the adhesionprocess to the surface of the asphaltene so that flocculation was prevented onthe surface of the crude oil.
3.2.2 Equipment The main equipment is viscometerand they play a vital role in this experiment results. The viscometer is usedto obtain the results for the viscosity of the crude oil samples that are beingmixed with the different formulation of inhibitors.
The viscometer used is theBrookfield Programmable Viscometer DV-II + PRO. The standard settings of theequipment are as below. Table1.1: Standard settings of viscometer Spindle Size 63 Rotational Speed 100 rpm Units cgs Theproper method to obtain accurate reading ensures that the viscometer isauto-zeroed before testing the new samples and at different temperatureintervals. The viscometer should be left around 10 minutes before using them asa pre-warm up for the device so accurate readings can be obtained at the end ofthe experiment. The spindle for the viscometer should be handled carefullybecause it is very sensitive and can break if being handled carelessly besideensure the calibration of the crude oil is not affected. Figure 3.
3: The DVII + Proviscometer used to measure viscosity. Thenext equipment used is Binder Oven. This oven is used to heat the crude oilpre-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 inthis experiment is to provide a temperature of 70 -90? during the mixing of EVA, MCH and toluene andbutanol, and also during the mixing process of crude oil and the differentformulation of inhibitors.
Figure 3.5: The cimarec hot plate stirrer Theimportant equipment that was used in this experiment is water bath. The role ofthe water bath is to decrease the temperature of the samples gradually asintervals around 5°C between the two temperatures and the temperature range isbetween 5°C and 20°C during the experiments. The type of thermometer used tomeasure the temperature of the samples is digital temperature. Figure 3.6: Water bath used to control temperature intervals A mass balance is used to measure theweight of EVA which is around 20 g so that a more accurate weight of EVA isobtained.
The digital micropipette is used to obtain the accurate readings forthe solvents that come in liquid form. Figure 3.7: The micropipette used for liquid solvents 3.3 Pre-experimentalPreparation of Chemicals and Crude Oil The pre-step for the experimentis that the crude oil is heated in the Binder oven at the temperature about 90? for an overnight. This step is to melt any depositionof wax crystals that had been formed earlier and the structure of asphaltenethat being agglomerates in the crude oil. The preliminary step before thisexperiment being conducted is the apparatus that will be using such as thespindle of viscometer, measuring cylinder and pipette were heated to 60? so that the precipitation of wax and asphaltene atthe point of contact between the hot crude oil and cold apparatus can beavoided and to obtain accurate results.
Before mixing of the inhibitor togetherEVA, MCH and toluene or butanol are heated in a water bath to increase thetemperature to 60?. 3.4 Preparation of inhibitor The inhibitors were prepared byconducting them on a hot plate at a temperature of about 90?. Instead of using the oven, using hot plate can helpto save time and space for the experiment to be conducted as the limitation oflab equipments in preparing the chemicals.
The individual chemicals, EVA, MCHand Toluene are measured separately of its respective volume and weight inaccordance with the manipulated percentage composition. The unit for the EVA isgrams of mass while MCH is in mL and toluene and butanol in mL. The totalvolume of inhibitor used is 0.4g.
Thus, for example, if the percentagecomposition of the samples prepared are 50% EVA, 10% MCH and 40% Toluene, then0.2 g EVA is measured using a mass balance, 0.04 mL of MCH is measured using amicropipette and 0.16 mL of Toluene is measured using a micropipette. Theprecaution step here is to replace the tube for the micropipette for each newsample that was taken so that contamination can be avoided and accuracy of theresults obtained can be improvised .Care is taken to replace the micropipettetube for both chemicals to avoid contamination.
The purpose of the reaction to be in high temperature which is 90 °C isto ensure that the EVA pellets is completely melted in the inhibitors. Aftercomplete melting of EVA occurred, then the crude oil that were placed in theoven overnight should be mixed with the EVA and the inhibitor solutions. If thecrude oil is placed overnight, then complete dissolved wax crystal will obtainedat the next day. Later, the samples obtained should be shaken around 30 secondsor around a minute.
This is to ensure the crude oil and the inhibitorscompletely mixed. Then, the samples are placed again in the oven for 15 minutesto allow the reaction to take place. Figure 3.8: The prepared sampleswith labels Figure 3.9: The samples heatedin the oven prior 3.
5 Experimental Procedure The samplesprepared were tested for viscosity by using viscometer. Moreover, in thisexperiment, the samples were tested for the optimum temperature for theefficient reduction of wax and asphaltene appearance on the surface of thecrude oil. The viscosity of the samples was taken from the temperature rangefrom 5° C and 20° C with each every 5? intervals. Thecontrol sample in this experiment is blank crude oil that is free frominhibitors.
The viscosity of the blank crude oil is measured after taken fromthe oven at room temperature. The temperature of the sample is observed byusing the digital thermometer and the decrease in temperature gradually isobserved carefully. The step is repeated at every 5? interval until the sample temperature drops exactlyto 5?.Thesample is immersed in an iced water bath so that the temperature can reduce tothe expected temperature. The precaution step here is during handling thespindle of the viscometer and the temperature reading should be taken in eyemeniscus level to avoid parallax error in readings.
The procedure is repeatedfor each of the other samples that contain the different formulation ofinhibitors with various percent of the composition of solvents and polymers.Before starting a new sample each time, the spindle and temperature probe islightly cleaned to avoid contamination of the samples.