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Chemistry and Technology of Fuels and Oils, Vol. 37, No. 4, 2001

USED OILS – COMPONENTS OF DIESEL FUELS

V. S. Azev, P. V. Chulkov, S. R. Lebedev, and V. V. Luneva UDC 665.521.4.004.82

____________________________________________________________________________________________________State Scientific-Research Institute of the Russian Federation Ministry of Defence. Translated from Khimiya

i Tekhnologiya Topliv i Masel, No. 4, pp. 11 – 13, July– August, 2001.

0009-3092/01/3704–0232$25.00©2001Plenum Publishing Corporation

An effective method is proposed for the utilization of used motor and industrial oils (UMO and UIO) asadditives to diesel fuels. As a result of investigation of diesel fuel L-0,5-40 with 5% of UMO and UIO, themaximum degree of variation was established in the concentration of actual resins in the fuel, its ashcontent, and carbon residue. A high-end-point distillation curve and an increase in viscosity are noted,i.e., degradation of quality as compared with requirements of GOST 305–82, which, however, is withinstandard limits set forth by TU 38.001355–86 for a diesel fuel with a high-end-point distillation curve.Results of testing of fuels with additives by motor methods, and also positive foreign experience enable usto propose that the method in question for utilization of UMO and UIO may find practical application.

Used motor and transmission oils, which when replaced in the engines and power plants of automobiles,tractors, and ships, often run-off into the ground or water bodies. In the best case, used oils from truck fleets andnaval base stations are collected in special tanks from which they are periodically drained, and transported to oiltank farms for utilization or regeneration. Additional environmental pollution occurs during all of these opera-tions as a result of random spillage and careless handling with the container being used, hoses, and other hard-ware components.

Weak economic interest is one of the basic causes of this relation between transportation establishmentsand bases for river and marine fleets and the collection and transfer of used oils. In the transfer to oil tank farms,used motor and industrial oils do not, as a rule, correspond to established requirements (Table 1) with respect toflash point. They are used primarily as mixtures of used petroleum products (MUPP) priced four times below theprice of furnace fuel. The low purchases prices do not justify the expenditures associated with the collection a ofused oils and their delivery to the receiving stations of petroleum-selling organizations.

According to GOST 21046–86, used petroleum products can be utilized in the following manner: motor

TABLE 1

Standards of GOST 21046–86 for groups Indexes

UMO UIO MUPP Test method

Viscosity at 50°Ñ, mm2/s >35 5 – 35 – GOST 33—82 Flash point (open cup), °Ñ, min 100 120 – GOST 26378.4—84

Content

mechanical impurities. wt. %. max 1 1 1 GOST 26378.2—84

water. wt. %. max 2 2 2 GOST 26378.1—84

contaminants None GOST 26378.2—84

cuts <340°Ñ, %, max 10 10 – GOST 2177—82

Solid point of cuts >340°Ñ, °Ñ, max –10 –10 – GOST 20287—74

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oils (UMO) – as a raw material for regeneration; industrial oils (UIO) – as a raw material for regeneration andtreatment; mixtures of petroleum products (MUPP) – as petroleum flushing fluids, and cylinder and transmissionoils for the heat treatment of metals; petroleum and liquid oil fuels recovered from sewage works – for reprocessingat oil refineries and mixture with petroleum, and as a component for boiler fuel.

In our country, used oils are regenerated at several oil-consuming establishments primarily by the removalof mechanical contaminants and water. Oil refineries mix used oils assigned for regeneration with their own trappingproducts, and use the mixture as an additive to furnace fuel oils, while petroleum-product suppliers abroad basicallydeliver used oils at very low prices.

Use of UMO and UIO as conservation materials is specified by instructions issued by several departments;as a rule, however, the demand for these materials is low. It is permitted to add no more than 10% of MUPP toatmospheric resid for burning in low-output boilers. In the best case, therefore MUPP can only be realized in fullvolume at points of collection.

Abroad, the basic mass (up to 90%) of used petroleum products is utilized as fuel [1]. Prior to aggravationof fuel-energy crisis in the 1970s, up to 18% of lube oils consumed was regenerated in the United States. Today,motor oils are regenerated in relatively limited volumes; this is explained by the low economic effectiveness ofthis operation.

Profit amounts to approximately 20%, whereas the profit from use of these oils as additives to fuelreaches 120%. Of the volume of oil produced, the fraction of regenerated oils amounts to 5%, 4%, and 10% inJapan, United States, and England, respectively. The following are reasons for the limited secondary use of lubeoils: high outlays for regeneration, environmental pollution by the wastes of this process, difficulties encounteredwith the latter in connection with the use of numerous additives to the lube oils, and stiffening of requirementsrelative to the quality of commercial lube oils.

A promising trend in the utilization of used oils is their use as a diesel-fuel component. The greatesteconomic effect is achieved in this case, since the cost of diesel fuel is twice that of boiler fuel. Moreover, theneed for transportation of used oil to receiving stations is eliminated.

In the United States, nearly half the companies engaging in truck maintenance prepare mixtures of usedoil and diesel fuel for use as a motor fuel. The price of diesel fuel exceeds the price of used oil delivered tocollection points by a factor of 10 on average, i.e., if the used oils are utilized as a fuel component, and are notdelivered to receiving stations, the economic effect is increase by an order on average.

Utilization of used oils as additives to diesel fuel in the United States had preceded a significant volumeof testing. Bench tests were conducted on mixtures of diesel fuel with 5, 10, and 15% of used oil. It was establishedthat the composition of exhaust gases and their smokiness are markedly altered, and the parameters of the workingprocess of supercharged engines are downgraded when the oil content in the mixture is greater than 10% [2].

The Caterpillar Company has run vehicles a distance of 160,000 km on a mixture of 97% of diesel fueland 3% of used oil. Neither increased wear of engine components and deposits, nor increased fuel consumptionwas noted during the runs [3]. Based on these tests, some companies permit use of a 10% mixture of used oil withfuel in their turbo charged diesel engines.

For their non-supercharged diesels, however, the Cummins and Racow Companies recommend a mixturecontaining no more than 5% of used oil. The companies, which service vehicles, prepare these mixtures at specialplants equipped with pumps for the mixing of components, and with filters for cleaning the mixtures of mechanical

TABLE 2

Indexes UMO UIO Viscosity at 50°Ñ, mm2/s 39 30

Flash point (open cup), °Ñ, min >110 >120

Content mechanical impurities, wt. %, max 0.18 0.4

contaminants None cuts <340°Ñ, %, max 5 7

Solid point of cuts >340°Ñ, °Ñ, max –23 –20

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impurities immediately prior to use.A method of mixing crankcase motor oil with diesel fuel directly in the vehicle has also been proposed in

the United States. In that case, the used oil is not drained, but is introduced to the fuel system of the operatingengine via an automated metering device, maintaining an optimal oil-change regime. At maximum oil feed during

Fuel L-0,5-40

in ef fect

Indexes

in a

cc

ord

an

ce

w

ith

G

OS

T 3

05

–8

2

an

d S

QA

M

wi th no addit ives

wi th wt .5% of

UMO

wi th 5wt . % of UIO

Cetane number min 45 53 55 54

Distillation, °C

IBP – 161 187 181

10 % – 233 235 235

50 % max 280 280 286* 285*

90 % – 342 357* 353*

96 % (EP) max 360 360 360 360

Viscosity at 50°C, mm2/s 3 – 6 5.8 6.3** 6 .3**

Solid point, °C max –10 –12 –18 –17

Cloud point, °C max –5 –5 – –

Flash point (closed cup), °C min 40 40 41 43

Sulfur content, wt. % max 0.5 0.39 0.4 0.36

Copper plate test Passed

Actual gums, mg/100 cm3 max 40 23 1300 1200

Acid number, mg KOH/100 cm3 (430)*** ( 510)***

Iodine number, g I2/100 g max 5 0.5 1.5 1.3

Ash, % max 6 0.6 0.6 0.6

Coke of 10% resid, % max 0.01 0.005 0.01 0.009

Filterability index max 0.3 0.08 0.58 0.39

Density at 20°C, kg/m3 max 3 2.5 2.2 2.2

Optical density max 860 840 843 843

Corrosion aggressiveness (at water condensation), g/m2 – 0.12 0.55 0.66

Filterability temperature limit, °C max 10 3.1 1.8 3.2

Atomizer-bench test max –5 –5 –5 –5

Thickness of lacquer film, µm max 2 0.3 0.5 0.5

Needle-extraction force, N max 150 1 1 1

Deposition on edge filter, mg max 4 1 1 3

Tendency to deposition in combustion chamber (PZI), mg max 60 28 50 42

Notes. * For HDC fuel: 50% – no higher than 290°C; 90% – no higher than 360°C.

** For HDC fuel – no more than 6.5 mm2/s.

*** In accordance with procedure for HDC fuel – 250°C.

TABLE 3

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mixing, its concentration is only 1.3% in the fuel.The total distance run of machines with Cummins, Detroit Diesel, and Mack engines fitted-out with these

devices has amounted to 16 million km. Tests have indicated that the service lives of the engines, fuel injectors,and pumps were lengthened in this case, obviously owing to additional lubrication of components.

In this study, we invest igated the effect of used-oi l addit ives to summer-grade L diesel fuel(GOST 305–82) on its basic properties, which can be assessed by standard methods and a set of qualification-assessment methods (SQAM). Two fuel mixtures were tested: with 5% of UMO, and with 5% of UIO. The used-oilsamples were submitted by the Moskomnefteprdukt. The quality indicators of these samples corresponded toGOST 21046–86 (Table 2).

The test results (Table 3) suggest that the addition of 5% of used oil to the fuel effects a change in thegreater part of its indicators, which are normalized in GOST 305–82. The concentration of actual resins, ashcontent, and carbon residue of the 10% resid are elevated to the maximum extent. The one-order increase in thelast indicators is explained by the high boiling point of the used oils, which do not evaporate from the fuel whenit is determined in accordance with the standard procedure, and also in accordance with the procedure for the fuelwith its high-end point distillation curve – HDC (at 250°C). Today, this indicator in the TU for an HDC fuel isreplaced by the “color” index in TsNT units.

The observed high-end point of the distillation curve and increase in the viscosity of the mixtures underinvestigation differ from the requirements set forth in GOST 305–82, but correspond to standards of the TechnicalSpecifications for HDC fuel. The carbon residue of the 10% resid of the mixtures under consideration exceededthe established norm by 30 – 100%. The UMO additive exerted a greater effect on this indicator than the UIO.

A certain decrease is noted in the solid point of the mixture, obviously, in connection with the depressoreffect of the oil additives while maintaining the limiting filterability temperature. No increased tendency of thefuel mixtures to form deposits on the engine injectors is observed.

When 5% of UMO and UIO is added to diesel fuel L-0,5-40, therefore, some of its quality indicators arelowered as compared with standards set forth in GOST 305–82. The degradation of these indicators, with theexception of the carbon residue of the 10% resid, however, did not go beyond the limits of the requirements setforth in the TU for HDC fuel. The increase in carbon residue did not lead to an increase in the tendency of the fuelmixtures to carbonization and deposits on the injectors by values exceeding SQAM standards.

Considering the results of preliminary tests, and also foreign experience, it is expedient to test a mixtureof diesel fuel (GOST 305–82) with 5% of UMO and UIO at motor-transport establishments engaging in intercityhauls and encountering certain difficulties in utilizing used oils. Development of rational methods of preparingmixtures of diesel fuel with used oils is required concurrently with these tests, utilizing actual technical potentials.

REFERENCES1. A. S. Amirov, A. V. Vlasov, and E. A. Mikheev, Collection And Use of Used Petroleum Products Abroad

[in Russian], TsNIITEIMS, Moscow (1981).2. R. L. Bechtold and S. S. Lestz, Combustion characteristics of diesel fuel blends containing used lubrication

oil, SAE 760116 (1976).3. Commercial Gas J., 97 – 103 (May, 1981).