Differences between gasoline, diesel, and jet fuel
Gasoline is a fuel made from crude oil and other petroleum-based liquids, containing carbon numbers generally between 4 and 12, and exhibiting boiling points of up to 120 °C. Gasoline is primarily used as a fuel for vehicles. Petroleum refineries and blending facilities produce motor gasoline for sale at gas (or petrol) stations. Most of the gasoline that petroleum refineries produce is unfinished gasoline. This unfinished product requires blending with other liquids to control parameters such as octane rating and volatility to make gasoline meet the basic requirements for fuel that is suitable for use in spark ignition engines.
Near-infrared spectroscopy—an ASTM compliant tool to assess the quality of gasoline, diesel, and jet fuel
Near-infrared spectroscopy (NIRS) has been an established method for both fast and reliable quality control within the petrochemical industry for more than 30 years. However, many companies still do not consistently consider the implementation of NIRS in their QA/QC labs. The reasons could be either limited experience regarding application possibilities or a general hesitation about implementing new methods.
There are several advantages of using NIRS over other conventional analytical technologies. For one, NIRS is able to measure multiple parameters in just 30 seconds without any sample preparation! The non-invasive light-matter interaction used by NIRS, influenced by physical as well as chemical sample properties, makes it an excellent method for the determination of both property types.
In the remainder of this post, available turnkey solutions for gasoline, diesel, and jet fuel are outlined which have been developed according to the NIRS implementation guidelines of ASTM E1655 (method development), ASTM D6122 (method validation), and ASTM D8340 (results validation). Afterward is a discussion about the return on investment (ROI) of using NIRS as an alternative to the CFR Engine.
NIRS expedites and simplifies fuel quality control
Without high quality fuels (e.g., gasoline, diesel, and jet fuel), our daily lives would look much different. At the end of the production process as well as at various steps in the distribution chain, the quality of the product needs to be determined. Typically, key quality parameters such as RON/MON (research and motor octane numbers), cetane index, and flash point are determined in the laboratory by chemical and physical methods. These methods not only incur high running costs but they are also quite time consuming.
NIRS on the other hand requires neither chemicals nor sample preparation. This technique can even be used by non-technical people (no chemistry degree necessary) and it provides results in less than a minute. Furthermore, multiple chemical and physical parameters can be determined simultaneously. The combined benefits of this technology make NIRS the ideal solution for many daily QA/QC measurements or ad-hoc at-line analysis.
Turnkey solutions: available pre-calibrations for gasoline, diesel, and jet fuel
Table 1 lists all constituents covered by the pre-calibrations for these different fuels. Click on the fuel type in the table to learn more about its pre-calibrations offered by Metrohm.
Table 1. Pre-calibrations available for a variety of key quality parameters in gasoline, diesel, and jet fuel.
|Density||0.74–0.76 g/cm3||0.0024 g/cm3||0.797|
|Density||0.82–0.89 g/cm3||0.0021 g/cm3||0.968|
|CFPP||-22–(+19) °C||2.8 °C||0.963|
|T95||325–410 °C||7.04 °C||0.799|
|Flash Point||56–120 °C||2.7 °C||0.97|
|Kerosene / Jet Fuel||Cetane index||36–50||1.1||0.871|
|API gravity||38–48 °||0.56 °||0.931|
|T10||158–200 °C||4.1 °C||0.801|
|T20||165–205 °C||3.1 °C||0.88|
|T50||180–220 °C||4.1 °C||0.789|
|Density||0.78–0.83 g/cm3||0.003 g/cm3||0.936|
|Flash Point||38–65 °C||4.3 °C||0.62|
|Freeze Point||-65–(-40) °C||3. 5°C||0.576|
|Viscosity at 20 °C||3–7 cSt||0.33 cSt||0.804|
Application example: quality control of diesel with the NIRS DS2500 Petro Analyzer
The cetane index (ASTM D613), flash point (ASTM D56), cold filter plugging point (CFPP) (ASTM D6371), D95 (ISO 3405), and viscosity at 40 °C (ISO 3104) are among some of the key parameters to determine the quality of diesel. The primary test methods for these parameters are labor intensive and challenging due to the need for multiple analytical methods.
In this turnkey solution, diesel samples were measured in transmission mode with a NIRS DS2500 Petro Analyzer over the full wavelength range (400–2500 nm). The built-in temperature-controlled sample chamber was set to 40 °C to provide a stable sample environment. For convenience reasons, disposable vials with a pathlength of 8 mm were used (Figure 1), which made a cleaning procedure unnecessary.
Figure 1. Quality control of diesel fuel as performed by the Metrohm NIRS DS2500 Petro Analyzer.
Figure 2. Correlation plots and figures of merit (FOM) for the different constituents tested in diesel.
Want to learn more? Download our free Application Note.
Return on investment: CFR Engine vs. NIRS
Gasoline requires intensive checks on several quality parameters which must be within certain specifications before commercialization. These parameters which can also be controlled by NIRS analysis include the research octane number (ASTM D2699) and motor octane number (ASTM D2700), also known as RON/MON.
The importance of measuring these values precisely is not only to comply with regulations, but also because of the further potential to save costs for manufacturers. As an example, RON values exceeding the stated requirements will still be accepted by the market, but these products will then include a higher amount of lucrative long-chain organic molecules. This so-called «RON giveaway» is estimated at approximately 0.5 RON per barrel, resulting in $2.25 million USD/month in lost revenue for a production process of 100,000 barrels per day.
Figure 3. CFR® F1/F2 Octane Rating Unit Combination Research & Motor Method. (Source: CFR Engines Inc.)
Ready-to-use NIRS systems are also available for monitoring several gasoline quality parameters which cover varied ranges and their respective precisions (Table 1). Additionally, the manufacturers of NIRS analyzers usually offer application support to extend these ranges or improve upon the precision.
An overview of estimated costs for the analysis of RON and MON with a CFR Engine compared to the Metrohm NIRS DS2500 Petro Analyzer is shown in Table 2. The full payback is achieved within two years if considering only 50% of the primary analysis method (CFR Engine) is replaced by NIRS. This calculation is based on 2000 analyses per year (1000 RON + 1000 MON), with total running costs of approximately $32.50 per analysis (chemicals, maintenance, and labor).
Table 2. Cost of ownership CFR engine vs. DS2500 Petro Analyzer.
|Total analyses RON + MON per year||2000||2000|
|Cost of operator per hour||$25.00||$25.00|
|Cost of Analyzer||CFR Engine||NIRS DS2500 Petro Analyzer|
|Total initial costs||$0.001||$55,000.00|
|Running costs consumables / chemicals / maintenance|
|Chemicals per year (ASTM D2699/D2700)||$20,000.00||$0.00|
|Maintenance cost per year||$20,000.00||$1,500.00|
|Chemicals plus maintenance cost per analysis||$20.00||$0.75|
|Total running costs per year||$40,000.00||$1,500.00|
|Time spent per analysis||30 minutes||< 1 minute|
|Labor cost of 1000 analyses of RON (ASTM D2699)||$12,500.00||$416.50|
|Labor cost of 1000 analyses of MON (ASTM D2700)||$12,500.00||$416.50|
|Labor cost per analysis||$12.50||$0.42|
|Total labor costs per year||$25,000.00||$833.00|
|Total running costs per year||$65,000.00||$2,333.00|
1Assumption that the instrument had previously been purchased, and therefore this cost is not included in the ROI calculation.
Near-infrared spectroscopy is very well suited for the analysis of key quality parameters in gasoline, diesel, and jet fuel. Available pre-calibrations are developed and validated in accordance with the ASTM guidelines. Positive aspects of using NIRS as an alternative technology are the short time to result (less than one minute), no chemicals or other expensive equipment needed, and ease of handling so that even shift workers and non-chemists can perform these analyses in a safe manner.
Future installments in this series
This blog article was dedicated to the topic of gasoline, diesel, and jet fuel and how NIR spectroscopy can be used as the ideal QC tool for the petrochemical / refinery industry. Future installments will be dedicated to other important applications in this industry. These topics will include:
For more information
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