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AZERBAIJAN CHEMICAL JOURNAL № 2 2023 ISSN 2522-1841 (Online)
ISSN 0005-2531 (Print)
UDC 665.7.03
INFLUENCE OF ADDITIVES ON THE QUALITY OF DIESEL FUEL
L.V.Pashayeva, S.A.Aliyev
Azerbaijan State Oil and Industry University
Received 30.11.2022 Accepted 27.01.2023
The influence of the physicochemical properties of diesel fractions on the effectiveness of the action of a cetane-enhancing additive, such as density, viscosity, sulfur content, boiling point (10%, 50%, 90%), molecular weight, and the choice of the required amount of additive for effective modification of the cetane number, were studied. To increase the cetane number, three different cetane improvers were used in this work. Three samples from various refinery units were used as the main base fuel:2-EGN(additives №1); № 2- AlH and № 3-AmH.For each sample, an increase in the cetane number of diesel fuel is shown depending on the concentration of additive № 2. It was noted that an increase in the amount of additives to 2.5% leads to an increase in the cetane number in all three samples. Of all the additives studied in the tested samples, additive № 1 turned out to be the best cetane-enhancing.The image of thecetane numbers of samples (№1 - № 3 with additives №1 - №3, are presented in the form of tables.The change in the cetane numbers of the samples is from 51 to 54. The scope of application is also indicated in the work: laboratories, and oil refineries, to obtain diesel fuel with specified cetane number parameters.
Keywords: diesel fuel, additives, cetane number, research samples, physical and chemical properties.
doi.org/10.32737/0005-2531-2023-2-104-110
Introduction
The world is currently aiming for a diesel engine. Therefore, diesel fuel is used more widely than gasoline. Using diesel engines has many advantages over gasoline engines, since diesel engines have a higher compression ratio than gasoline engines, they produce more power using the same amount of fuel. On the other hand, diesel fuel is cheaper than gasoline, since they are obtained mainly by direct distillation [1-5].
The quality of diesel fuel is evaluated by sulfur content, low temperature properties and cetane number. The cetane index is used to determine the performance of diesel fuel. This is an extremely complex property.In order to develop the optimal formulation for blending diesel fuel, as well as to effectively plan and manage its production, we need to develop methods for accurately calculating the cetane index of diesel fuel.
To improve the quality of diesel fuel, researchers often prepare additives such as cetane boosters, detergents, depressants, and anti-wear additives. Fuel additives improve the
initial properties of the fuel during storage, transportation and use, help to ensure the combustion process, reduce the harmful effects on mechanisms and equipment, allow the use of fuels at lower temperatures, etc.
The main operational and physico-chemical characteristics of diesel fractions are cetane number, fuel density, fuel viscosity, fractional composition, low-temperature properties, group composition of diesel fuels, diesel fuel additives, cetane improvers.
Specific requirements for diesel fuels are related with the peculiarities of the formation of the air-fuel mixture and its self-ignition in diesel engines. It is also used mainly for diesel engines (road, rail, waterways) and partly used for gas turbines (in power generation, construction, etc.) [6-8].
Thus, the purpose of this work is to select the most optimal cetane improver for diesel fuels depending on their physicochemical properties.
To achieve the goal, the following tasks were set:
• Research of physical and chemical properties of diesel fuels of various refineries;
• Choice of additives to increase the cetane number in accordance with the requirements;
• Selection of the most suitable additive for increasing the cetane number of diesel fuel and its amount, depending on the physical and chemical properties of diesel fuels.
The CN reflects not only the flammability of diesel fuel, but also its other qualities: the higher the cetane number, the better the starting qualities of the fuel, the shorter the self-ignition delay period, the greater the completeness of fuel combustion and the less tendency to carbon formation.
Bicyclic arenes, cycloalkanes, and bicycloalkanes occupy an intermediate position with the lowest CN, and finally, normal alkanes have the highest cetane characteristic. Branched alkanes have a lower CN than normal alkanes. The decrease in CN is also caused by the introduction of a double bond into the carbon molecule.
The use of fuel with a low cetane number (less than 40 units) leads to an increase in the ignition delay period and the occurrence of hard work, and the use of fuel with a cetane number above 55 units. It is impractical due to an increase in the specific fuel consumption due to a decrease in the completeness of its combustion.
Fractional composition serves as the main indicator of fuel, affecting the process of its combustion, as well as CC. The quality of its spraying and the completeness of combustion depend on the fractional composition. If there are a lot of light hydrocarbons in diesel fuel, then less oxygen is required for their combustion. For such fuel, the process of mixture formation proceeds more fully, however, the rigidity of the engine operation increases (the pressure increases sharply per degree of the angle of rotation of the crankshaft).
The optimal fractional composition is dictated by the design features of diesel engines and their operating conditions. For diesel fuels,
distillation temperatures of 50 and 96% by volume are controlled.
Generally, light gas oil distilled from crude oil meets the CN requirements for diesel fuel because it contains high levels of n-paraffin, which are high CN content components. However, in addition to the above process, diesel fuel can also be obtained from a catalytic treatment, such as a by-product of catalytic cracking. The diesel fuel products resulting from this process have a low CN and are of insufficient quality for use in diesel engines, even for slow vehicles. If you need to improve this index, you can use supplements, which can be divided into the following two groups:
-The first group includes alkyl nitrate types (isopropyl nitrate [IPN], n-butyl nitrate, amyl nitrate, cyclohexyl nitrate [CHN].
-The second group includes peroxide types (dialkyl and diaryl peroxides) [9-13].
The object of study in this work are various diesel fuels (three samples), cetane-boosting additives.
The subject of the study is the cetane index of diesel fuels, characterized by density, viscosity, fractional composition, molecular weight, and sulfur content.
Experimental part
The main performance characteristics of diesel fuel are: cetane number, density, fractional composition, viscosity, molecular weight, sulfur content.
The essence of the method for determining the density is to immerse the hydrometer in the test product, take readings on the hydrometer scale at the determination temperature and convert the results to density at a temperature of 200C [14].
The essence of the method for determining the viscosity of petroleum products is to measure the time of expiration of a certain volume of the tested petroleum product under the influence of gravity with a glass capillary viscometer. The kinematic viscosity is calculated as the product of the measured oil flow time and the viscometer constant.
Dynamic viscosity is calculated as the product of the kinematic viscosity and the
density of the oil at the same temperature. Pinkevich viscometers type VPZhT-4, VPZhT-2[15].
Determination of the molecular weight of petroleum fractions, petroleum products was carried out on the installation for cryoscopic determination of the molecular weight of KRION-1 and by calculation methods. The principle of operation of the installation is based on measuring the temperature depression - the difference in the crystallization temperatures of a pure solvent and a solution of the test substance, which is then used to calculate the molecular weight of the test substance.
The essence of the method for determining the fractional composition (10%, 50%, 90%) is the distillation of 100 ml of the test sample under conditions corresponding to the nature of the product, and constant monitoring of the thermometer readings and condensate volumes. The tests are carried out in the ARN-2 apparatus, which has: heating element, cooling bath, thermometer, etc. [16].
In the method for determining the sulfur content in petroleum products, the essence of the method lies in the fact that the test sample is placed in a beam of rays emitted by an X-ray tube. The resulting excited characteristic X-ray emission is measured and, to obtain a total sulfur content in percent by mass or milligrams per kilogram, the received signal of the pulse counter is compared with the signals obtained from testing pre-prepared calibration samples that cover the concentration range of interest: 0.0% mass. - 0.1% wt.; 0.1% wt. - 1.0% wt; 1.0% wt. - 5.0% wt.
In the determination, any energy-dispersive X-ray fluorescence spectrometers are used, if their design includes certain devices (X-ray source, removable cuvette, X-ray detector, filters, electronic devices for signal recognition and data processing, display and printer) and the results obtained on such a spectrometer, equivalents obtained on the samples of interest.
The calculated cetane index is a useful tool for estimating the cetane number when a test engine is not available to determine it, or when the amount of sample is too small to be
used in a test engine.
In the range of cetane numbers from 30 to 60 for distillate diesel fuels, the calculated cetane index coincides (with a 75% confidence probability) with the cetane number determined experimentally on test equipment, with a discrepancy within ± 2 cetane units [17].
New additives to diesel fuel have been developed by the authors of [18, 19]. Of interest are also works [20, 21], where additives for increasing the CN of diesel fuel were studied.
Method for determining the CI of diesel fractions by the calculation method according to the ASTM standardshown in [22].
Three samples were used as the main base fuel - sample №1 (from EUDS-AVQ), sample №2 (from a hydrocracking unit) and sample №3 - a mixture of diesel fuels.
Three new additives were prepared as additional components for samples (fractions) (№1-№3): 2-EGN, AlN va AmN. Table 1 lists some of the properties of the various fractions tested.
Results and discussion
According to the literature, diesel fuel is the most important product in refineries. The composition and properties of diesel fuel affect the cetane number and particulate emissions. The composition of diesel fuel in single, double and triple hydrocarbon compounds, as well as in aromatic rings, directly affects its physical and chemical properties. In general, there is a relationship between the molecular structure (paraffins, olefins, naphthenes and aromatics), chemical properties (cetane number, flash point, etc.) and physical properties (density, viscosity, surface tension, etc.) of diesel fuel. Therefore, in order to improve the properties of diesel fuel, we need to select the appropriate additives. Comparison of the cetane number calculation methods we carried out allows us to conclude that the most optimal method for determining the cetane index is the standard 27768-88 (CH = 46 -54).
The cetane index was compared according to the American standard test method (first method) and the calculated cetane index (second method) obtained by us. The method
consists in determining the density of diesel fuel at 150C according to the 3900-85 standard and the average boiling point of a 50% (by volume) diesel fuel fraction according to the 2177-82 standard. is 45, according to the second method 48.3. For fraction 2, these figures are 45.8 and 51.2, respectively; finally, for fraction 3, the figures are 70 and 55.6. It is known that additives are substances that are added in small amounts to the fuel and increase the cetane numbers of the product. In our study, the effect of the added additives leads to the following changes in the cetane number.
Table 1 lists some of the properties of the various fractions tested. All tested products comply with GOST in terms of cetane index, which should be atleast 45.
Table 2 clearly shows the increase in the cetane number of diesel fuel depending on the concentrations of additive № 1. It is shown that the addition of an additive with a concentration
of up to 1% leads to an increase in the cetane number. Therefore, the amount of additive 1% is maximum for addition in samples 1 and 2. In this case, for sample № 1, the maximum octane number is 53.4. For sample 3, the maximum amount of additive is 0.6%, and the highest octane number is 54. Further increase in the amount of additive, as can be seen from Table 1, does not affect the octane number.
Table 3 gives an image of the cetane numbers of samples with additive № 2. From the same table 3, it can be seen that an increase in the amount of additive from 0 to 2.5% leads to an increase in the cetane number in all three samples. Judging by the data in Table 2, it can be concluded that the maximum amount of additive 2% to be added in sample 1. For sample 2, the maximum amount of additive is 2.5%, and for sample 3, the maximum amount of additive is 1.5%.
Table 1. The results of the determination of physico-chemical properties
Index Fraction №1 Fraction №2 Fraction №3
Density of 15°C,Kg/M3 0.85 0.86 0.88
Kinematic viscosity, Pac 4.06 4.23 21.03
Dynamic viscosity,MM2/c 3.41 3.55 18.44
Sulfur content,% 0.22 0.51 0.86
Boiling point 171 152 75
10% 203 193 307
50% 262 261 348
90% 341 343 371
End boiling point 346 343 371
Cetane index by ASTM 45.04 45.49 69.98
Cetane index by GOST 48.13 50.78 55.17
Compliance with GOST 32511-2013 EURO diesel fuel Corresponds Corresponds It does not match
Table 2. Cetane numbers of samples with additive №1
№ solution Additive concept % about Sample 1 Sam ple 2 Sample 3
CN Ft,C CN Ft,C CN Ft,C
0 0 51 -17.8 51.8 -12.3 53.6 -4
1 0.1 51 -15.5 51 -10 54.0 -4
2 0.2 51 -13.9 51 -9.5 54.0 -4
3 0.3 52 -11.7 51.3 -8 53.5 -4
4 0.4 52 -10 54 -8 53.8 -4
5 0.5 52 -9.7 54 -5.8 53.8 -4
6 0.6 51.4 -8 54 -4.8 54 -3.9
7 0.7 54 -7.3 53.3 -4 54 -3.5
8 0.8 54 -5.4 53.8 -4 54 -3.1
9 0.9 54 -4.3 53 -4 54 -2
10 1 53.5 -4 53.2 -4 53.7 -2
Table 3. Image of cetane numbers of samples with additive №2
№ solution Additive concept, % ab. Sample 1 Sample 2 Sample 3
CN Ft, C CN Ft, C CN Ft, C
0 0 51 -15 50 -20.6 52 -10
1 1 53.4 -4.3 53 -7.4 54 -4
2 1.5 54.3 -4 54 -4 55 -4
3 2 55 -3.1 54.9 -4 55 -4
4 2.5 56 0 55 0 56 0
Table 4. Image of cetane numbers of samples with additive №3
№ Solution Additive conseptaabout% Sample 1 Sample 2 Sample 3
CN Ft,C CN Ft,C CN Ft,C
0 0 51 -17,8 51 -21,9 51,8 -12,2
1 0,1 51 -16,4 51 -18,1 52 -10
2 0,2 51 -14,8 52 -17,6 52 -9,5
3 0,3 52 -13,6 52 -15 53,3 -8
4 0,4 52 -10 51,1 -12,9 53 -8
5 0,5 52 -9,7 52 -10,6 53 -5,5
6 0,6 52,5 -8 52 -11 53 -4,8
7 0,7 53 -7,4 52 -8 53,2 -4
8 0,8 53 -5,2 53 -7,7 53,6 -4
9 0,9 53 -4,4 53 -6 54 -4
10 1 53,5 -4 53 -4,6 54,6 -4
Additive concentration in water, mg/l Toxicity index, T Degree of toxicity
10000.00 0.989 High*
100.00 0.986 High
1.00 0.650 Moderate**
0.50 0.480 Moderate
0.10 0.450 Moderate
0.01 0.226 Acceptable***
Permissible degree of toxicity 0.00<T<0.40 ** Moderate toxicity 0.40<T<0.70 * High degree of toxicity T>0.70
Finally, Table 4 shows that an increase in the concentration of the additive in the range from 0.5 to 1% in all three samples increases the cetane number. The amount of additive 1% is the maximum to add for all three samples. The maximum cetane number in this case is for sample 1 - (53.5), for sample 2 - (53.0), for sample 3 - (54.6).
Thus, analyzing the data obtained, we can say that additive № 3 (amyl nitrate) has a better effect on increasing the CN than additive №1 (2-ethylhexyl nitrate). With the addition of only 0.1% of the additive, the cetane number increases significantly (CN = 51-54) and meets the standards. With an increase in the concentration of additive № 2 (alkyl nitrate) to
0.5%, the cetane number increases rapidly, but does not meet the standards (CH > 54).
Table 5 shows the results of biotesting of the developed cetane-enhancing additive. The change in the indices and degrees of toxicity of the studied additive depending on its concentration in water is shown. The concentration of the additive was selected in such a way as to register an approximate transition from high to moderate, from moderate to acceptable degrees of toxicity.
As can be seen from Table 5, the toxicity index of the developed cetane-enhancing additive has an acceptable degree at concentrations of 0.1 mg/l and below.
Thus, the study of the toxicity of motor fuel additives by biotesting is a practically
important task in studying their approximately permissible level of environmental impact in order to determine the hazard class, predict hygienic standards for the content of individual components, information about which is not available. The results obtained can be used in compiling safety data sheets for both imported and domestic additives, which will guarantee their safe and confident use by consumers.
Conclusion
It was found that additive №1 had the greatest cetane-boosting effect on sample №1 and sample № 2. The CC for sample №1 increased from 51 to 53.4 and for sample №2 from 51.9 to 54.2. The greatest modification effect was achieved with an additive amount of 0.1% of the fuel volume.
Similar to additive №1, cetane booster №2 had an effect on sample №1 and sample №2. The CC for sample №1 increased from 51 to 56 and for sample №2 from 51 to 54. The greatest modification effect was achieved with an additive amount of 0.5% of the fuel volume. The worst result of increasing the CN was observed on sample №3. Additive №3 had a slight effect on increasing the CN in samples №1 and №2.
Thus, it can be concluded that additive №1 is the best cetane-enhancing additive to add to the tested samples. It has been shown that the physicochemical characteristics of the fuel are the most important characteristics of diesel fuel and a change in their properties affects the effect of the cetane additive.
References
1. Topliva i masla. Metody uluchsheniya ikh eksplua-tatsionnykh svoystv: Uchebnoye posobiye T.F. Ganiyeva, R.Z.Fakhrutdinov, H.Y.Bashkirtseva. SPb. Prospekt Nauki. 2017. 160 P.
2. Anisimov A.S. Sposoby uluchsheniya eksplua-tatsionnykh svoystv dizel'nogo topliva. Molodoy uchenyy. 2016. No 26. V. 130. P. 1-3.
3. Rand S.Dzh. Analiz nefteproduktov. Metody, ikh naznacheniye i opredeleniye: per. s angl. 8-go izd. / S.Dzh. Rand i dr.;pod red. Novikova Ye.A., Nekhamkinoy L.G. TSOP «Professiya»; Spb. 2012. 664 P.
4. Danilov A.M. Primeneniye prisadok v toplivakh. SPb. Khimizdat, 2010. 368 P.
5. Neft' i nefteprodukty. Metody opredeleniya plotnosti. M.: Standartinform, 2012, 36 P.
6. Danilov A.M. Development and application of additives to fuels in 2006-2010. Chemistry and technology of fuels and oils. 2008. No 2. P. 41-50.
7. Nefti i nefteprodukty. Metod opredeleniya fraktsionnogo sostava v apparate APH-2
8. Zuikov A.V., Chernysheva E.A., Sidorov Yu.V., Khavkin V.A., Gulyaeva L.A. Features production of low sulfur diesel fuel with a low content of polycyclic aromatic hydrocarbons. Oil refining and petrochemistry. 2013. No 1. S. 11-15.
9. Pat. 2002130569 RF.. Organic cetane improver. Jordan Frederick L. No. 2002130569/04; bid. 12.04.2001;publ. 25.10.2001.
10. Pat.4,585,461US,C10L1/24.Method of manufacturing a dieselfueladditiveto improve cetane rating. Jeremy W. Gorman, 1984.
11. Standartu ASTM. Metodopredeleniya TSI dizel'nykh fraktsiy raschetnym metodom.
12. Petrukhnova Ye.V., Plaksina R.V., Kornishina L.Ye., Volkova M.M. Import o zameshcheniye prisadok, uluchshayushchikh svoystva dizel'nogo topliva YEVRO. Neftepererabotka i neftekhimiya. 2011. No 7. P. 21-24.
13. Danilov A.M. Otechestvennyye prisadki k dizel'-nym toplivam. Mirnefteproduktov. 2010. No 1. P. 9.
14. Neft' i gaz tekhnologii i produkty pererabotki imeni V.Ye.Agabekov, V.K. Kosyakov.2011.P.97.
15. Nefteprodukty. Opredeleniye kinematicheskoy vyazkosti i raschet dinamicheskoy vyazkosti. M.:Standartinform. 2005. P. 20.
16. GOST 1101-85 oil and oil products. Method for determining the fractional composition in the apparatus ARN -2.2002.P.4-9.
17. Opredeleniye tsetanovogo indeksa. M.: Izdatel'-stvo standartov. 1988. P. 24.
18. Pat.2280068 RF. Prisadka k dizel'nomu toplivu, dizel'noye toplivo. Lanchakov G.A., Kabanova Ye.N., Bashkatova S.T., Vinokurov V.A., Kabanov O.P., Zhuravlev A.N., Likhterov. 2006.
19. Pat. 2002130569 of the Russian Federation, IPC, C10L1 / 18.Organic cetane improver.Jordan Frederick L. No. 2002130569/04; bid. 12.04.2001; publ. 25.10.2001.P.10-14
20. Standard Test Method for High Temperature Stability of Middle Distillate Fuels, ASTM International: West Conshohocken. 2008 .P. 85-91.
21. Grishina I.N., Zavaruhina Yu.B., Bashkatova S.T., Kolesnikov I.M. Development of a range of the additives improving properties of Russian diesel fuels.Materials of 18 International Congress of Chemical and Process Engineering. 2008. P. 243246.
22. Pat. 2309975 RF. Additive for increasing the cetane number of diesel fuel. Novatsky G.N., Vodolazhsky S.V., Sokolov B.G., Somov V., Zalishchevsky G.D., Shadrin A.V. 2007.
A§QARLARIN DÍZEL YANACAGININ KEYFÍYYOTÍNO TOSÍRl L.V.Pa^ayeva, S.O.Oliyev
Dizel fraksiyalarinin fiziki-kimyavi xassalarinin - sixligin, özlülüyün, kükürdün miqdarinin,qaynama temperaturunun (10%, 50%, 90%), molekul kütlasinin, setanartirici alavanin effektivliyina tssiri va setan adadinin effektiv modifikasiyasi ügün lazim olan alavanin miqdarinin tayini tadqiq edilmi§dir. Setan adadini artirmaq ügün baxilan i§da üg müxtalif setanartinci alavadan istifada edilmi§dir: 2-EQN(a§qar №1); №2- alkilnitril и №3- amilnitril. Osas baza yanacagi kimi neft emali zavodunun müxtalif qurgularindan üg nümuna götürülmüijdür. Har bir nümuna ügün 2 nömrali alavanin konsentrasiyasindan asili olaraq dizel yanacaginin setan sayinin artmasi göstarilir. Qeyd olunub ki, alavalarin miqdarinin 2.5%-a qadar artmasi har üg nümunada setan sayinin artmasina sabab olur.Sinaqdan kegirilmi§ nümunalarda tadqiq edilan bütün alavalardan setan artiran an yax§isi 1 nömrali a§qar olub.Nümunalarin (№1-3) setan adadlarinin tasviri,uygun a§qarlarla № 1-3, birlikda, cadvallar §aklinda taqdim olunmu§dur.Nümunalarin setan saylarinda dayi§iklik 51-dan 54-a qadardirí§da, tatbiq sahasi kimi,qabaqcadan verilmi§ setan adadina uygun dizel yanacagi almaq ügün, müxtalif laboratoriyalar, neft emali zavodlarida taklif edilmi§dir.
Agar sözlzr: dizel yanacagi, a§qar, setan 3d3di, tsdqiqat mmmalari, fiziki-kimyavi xassalar.
ВЛИЯНИЕ ДОБАВОК НА КАЧЕСТВО ДИЗЕЛЬНОГО ТОПЛИВА Л.В.Пашаева, С.А.Алиев
Изучено влияние физико-химических свойств дизельных фракций на эффективность действия цетаноповышающей добавки, таких как: плотность, вязкость, содержание серы, температура кипения (10%, 50%, 90%), молекулярная масса и выбор необходимого количества присадки для эффективного модифицирования цетанового числа. Для повышения цетанового числа в данной работе использовалось три различные цетаноповышающие добавки: 2-ЭГН(присадок №1); №2- АлН и №3- АмН. В качестве основного базового топлива использовали три образца из различных установок нефтеперерабатывающего завода. Для каждого образца показано увеличение цетанового числа дизельного топлива в зависимости от концентрации присадки №2. Отмечено, что увеличение количества добавок до 2-5% приводит к увеличению цетанового числа во всех трех образцах. Из всех исследованных добавок в тестируемые образцы лучшей цетаноповыщающей оказалась добавка №1. Изображение цетановых чисел образцов (№1- 3) с присадками №1 -3, представлены в виде таблиц. Изменение цетановых чисел образцов составляет от 51 до 54. В работе также указана область применения: лаборатории, и нефтеперерабатывающие предприятия, для получения дизельного топлива с заданными параметрами цетанового числа.
Ключевые слова: дизельное топливо, присадки, цетановое число, образцы исследования, физико- химические свойства.
