In order to acquire fuel property details of diesel fuel, GTL fuel and HVO fuel, three instruments were used in this research to determine fuel distillation characteristics (TGA), elemental composition (CHNS analyser) and chemical compositions (GC-MS) A thermogravimetry instrument manufactured by METLLER TOLEDO was used to measure the mass change of fuels and lube oils when they were exposed to
temperature from 30°C to 600°C. Pure white diesel, pure GTL fuel, pure HVO fuel, fresh engine lube oil and used engine lube oil were tested. The photo of the experimental TGA analyser in shown in figure 3-16, and the specification of instrument is provided in table 3-15. [Metller-toledo,2015].
Figure 3- 16 The experiment METLLER TOLEDO thermogravimetric analysis instrument.
Table 3- 15 The specification of experiment METLLER TOLEDO thermogravimetric analysis instrument.
Mode of instrument TGA/DSC 3+
Temperature data
Temperature range RT to 1100°C
Temperature accuracy ± 0.25k
Furnace temperature resolution 0.001 K
Heating time 5 min (RT to 1100 °C)
Cooling time 20 min (1100 to 100 °C)
Cooling time with helium ≤10 min (1100 to 100 °C)
Heating rate 250 K/min
Cooling rate –20 K/min (≥150 °C)
Balance data
Sample volume ≤100 µL
Measurement range ≤1 g
Resolution 1.0 µg
Weighing accuracy 0.005%
Repeatability <0.001 mg
Typical Minimum Weight 0.19 mg
Blank curve reproducibility better than ±10 μg over the whole temperature range
Calorimetric data
Sensor type DSG 3+
Surface material ceramic
Number of thermocouples 6
Signal time constant at 900 °C 14 s
sensitivity 0.1 mW
One Thermo Scientific FLASH 2000 HT Elemental Analyzer was used to measure the carbon, hydrogen, nitrogen, sulphur weight percentages and heat capacity of diesel fuel, GTL fuel, HVO fuel. The tests were repeated by two times and the final data in the fuel specification was the average value from two repeated tests. The elemental analyser is shown in figure 3-17 and its specification is listed in table 3-16. [Thermo Scientific, 2014].
Table 3- 16 The specifications of Thermo Scientific FLASH 2000 HT Elemental Analyzer.
Instrument description
• Base unit FLASH 2000 HT elemental analyzer (two furnaces)
• Eager 300 software
• MAS 200R autosampler for solids with 32-sample tray
• Standard outfit for H&O and N&C determination for approx. 1000 analyses each Gases
Helium 99.999% purity
Oxygen 99.995% purity
External Precision for Isotope Ratios C, N, S, O, H, (n = 10), δ-Notation Urea or Acetanilide at Natural Abundance
for C and N – IRMS. 50 µg C, N
13C/12C 0.15‰;15N/14N 0.15‰
Urea or Acetanilide at Natural Abundance for C and N – IRMS. 5 µg C or 10 µg N
13C/12C 0.2‰;15N/14N 0.2‰
Sulfanilamide at Natural Abundance for S.
50 µg S
34S/32S 0.2‰
Benzoic Acid at Natural Abundance for H and O – IRMS. 50 µg O, 25 µg H
18O/16O 0.4‰; D/H 3‰
Pure Water at Natural Abundance. 0.5 µL. 18O/16O 0.2‰; D/H 2‰
External Precision for Elemental Concentration (RSD), Mass Traces
50 µg C, N (urea) C 1%; N 1%
50 µg O, 25 µg H (benzoic acid) 0 2%; H 2%
Power supply 230 V, 50/60 Hz, 1400 VA
Dimensions and Weight 590 x 580 x 500 mm (w x d x h) 67 kg (net value)
Figure 3- 17 The experiment Thermo Scientific FLASH 2000 HT Elemental Analyzer.
To acquire the organic compound distribution of diesel fuel, GTL fuel and HVO fuel, one Shimadzu gas chromatograph-mass spectrometer was used in this research.
The GC-MS analysis consisted of two part: the GC analysis, which allowing the
compounds of test sample to be separated from each other; and the MS analysis, which allowing the compounds of test sample to be identified and quantified. In the GC
analysis, first the sample was diluted with n-pentane in 100 dilution ratio, meaning 10 µl of tested fuel was diluted with 990 µl of n-pentane. Then the sample prepared was injected in to the GC analyser. The inject temperature was 250 °C. After the liquid sample was vaporised in the hot inlet, the gas sample travelled through the GC column, and different compounds were separated due to their different chemical characteristics.
The gas chromatography column used for the test was manufactured by Agilent technologies and the size was 25m×0.25mm×0.25µm. The column oven temperature program was set from 40°C to 320°C with 10°C/mins increasing rate. The compounds with higher carbon fractions would travel slower and had longer retention time (the time compound takes to pass through the GC column). Finally, the separated compounds were ready to be send to MS for identification and quantification. [Elscience, 2016].
In the MS analysis, first, the separated compounds were broken into ionised fragments with high energy beam. The ion source temperature and interface temperature of the mass spectrometer was respectively 200°C and 250°C. Then the fragments travelled through a tunnel exposed to magnetic field and hit the detection plate. Since each fragment had certain mass and charge, therefore the mass to charge ratio (m/z) of different compounds was different. This would affect the deflection of fragments in the magnetic field. After that, the mass to charge ratio and the amount of fragments (relative abundance) were calculated in the MS analyser based on the signal received from the detection plate. Finally, a GC software was used to calculated mass spectrum and matched for a peak with the spectra in a database library. A hit number is given when the compounds were identified. The number is generally out of 100, and the closer to 100, the better the match. Thus, the compounds were identified and quantified. The database used is called NIST 11 mass spectral database, which contained 243,893
experiment GCMS instrument is shown in figure 3-18 and its specifications is explained in table 3-17. [Shimadzu, 2018].
Figure 3- 18 Shimadzu gas chromatograph-mass spectrometer QP-2010 SE used in this research.
Table 3- 17 The specifications of Shimadzu gas chromatograph-mass spectrometer QP-2010 SE.
GC
Model Shimadzu GC-2010 Plus
Oven temperature Up to 450˚C
Injector port temp Up to 450˚C
AFC pressure range 0 to 970 kPa
MS
Type Direct connection with capillary column
Temperature 50 to 350˚C
Ion source temperature 140 to 300˚C
Filament Dual (Automatic Switching)
Electron energy 10 to 200 eV
Emission current 5 to 250 µA
Power requirement
Frequency 50/60 Hz
GC 1800 VA (115 VAC)/*2600 VA (230 VAC) * High-power oven
MS 1000 VA (100 – 230 VAC)
Environment
Temperature Constant temperature between 18 and
28˚C
Humidity 40 to 70 % (No condensation)
Size and Weight
GC/MS 74 Kg
Rotary pump 10 Kg