Chemistry: analytical and immunological testing – Lubricant – grease – mineral oil – hydrocarbon oil product – or...
Patent
1992-04-24
1995-01-03
Bhat, Nina
Chemistry: analytical and immunological testing
Lubricant, grease, mineral oil, hydrocarbon oil product, or...
436169, 436171, 436177, 208 46, 44600, G01N 2178, G01N 3328
Patent
active
053786327
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method of testing oils for potential instability and to test kits for applying the test method.
Unstable oils undergo chemical degradation reactions which, over periods of time, produce small but insignificant changes in their properties. The amount of insoluble matter and/or sediment in the oil is one such property. These materials can plug the fuel channels in fuel filters and reduce or alter the spray pattern from engine injector nozzles. In both cases the required flow and delivery of fuel to the engine combustion chamber cannot be maintained and poor engine performance and possible mechanical damage may result.
Chemical reactions associated with unstable oils may also occur at an accelerated rate when the oil is heated. For example, hot metal components in fuel systems heat the fuel and may result in forming insoluble matter. This matter can form an organic deposit or varnish on such surfaces. The deposits may reduce the rate of heat exchange through the metal surface or alter the flow of fuel from those of the design requirements.
Concern with respect to the storage stability of oils is increasing as relative demand for the possible range of refinery product from crude oil has resulted in increased use of refinery cracking processes to convert part of the heavier ends to lighter middle distillate fuels. The cracked products, which contain higher amounts of chemically unstable species, are blended with more stable straight run streams to produce commercial fuels.
The strong influence of these unstable species in cracked refinery streams on deposit formation from the fuel is recognised by the oil industry, which frequently uses further refinery processing in the form of hydrogenation to reduce the concentration of these unstable species. Alternatively, or in addition, stabilizing additives may be added to the fuel which propose to reduce the extent of deposit formation.
The chemical reactions which produce insoluble materials in fuel are slow at ambient temperature and very little change can be detected even in a very unstable fuel during the short storage time at the refinery. It is believed that one important mechanism by which sediments are formed is reaction between trace compounds present in the oils to form solid or gummy products. Therefore even repeated filtration of the oils may not solve the problem of sediment formation. "Fuel" 67 (August 1988) 1124-1130 and 68 (January 1989) 27-31 suggest one of the principal reactions involved in sediment formation in diesel oils is the reaction between phenalanones (I) or Phenalenones (also known as perinaphthenones) (II), which are themselves produced by oxidation of phenalenes (also known as perinaphthalenes or benzonaphthenes) (III), ##STR1## and indoles to form sediment precursor compounds of formula (IV) where R is alkyl and n is 1 to 3: ##STR2## In formula (I) to (IV), the tricyclic ring compounds may be substituted, for example by one or more alkyl groups. Phenalenes, phenalanones, phenalenones and indoles are believer to be introduced in the course of modifying the oils by incorporation of catalytically cracked oils.
The 1989 article describes reactions between synthesised phenalanones or phenalenones and indoles under acid conditions to yield intensely blue indolyl phenalene salts.
A number of methods have been developed to increase the rate at which deposits are formed so that meaningful amounts may be measured. The most common is the use of American Society for Testing and Materials (ASTM) Method D2274, which uses an elevated temperature of 95.degree. C. for 16 hours and the bubbling of oxygen gas through the fuel. A recent experimental test method is to heat the fuel at 90.degree. C. in an oxygen pressure bomb with an oxygen gas pressure of 794 kPa for 16 hours. This method is known as the oxygen overpressure test. Concern has arisen from those practising this art that the high temperatures and the presence of oxygen result in different chemical sediment producing reactions than occur at ambient temperatures. Gravim
REFERENCES:
patent: 4181597 (1980-01-01), Yan et al.
patent: 4556326 (1985-12-01), Kitchen, III et al.
patent: 5059303 (1991-10-01), Taylor et al.
patent: 5114436 (1992-05-01), Reid
Fuel "Storage Stability of Petroleum-Derived Diesel Fuel" vol. 67, Aug. 1988 pp. 1124-1130.
Fuel "Storage Stability of Petroleum-Derived Diesel Fuel" vol. 68, Jan. 1989, pp. 27-31.
ASTM Method "Standard Test Method For Oxidation Stability of Distillate Fuel Oil (Accelerated Method)" D 2274-88, pp. 123-127.
DEF STAN 05-50 "Methods for Testing Fuels, Lubricants and Associated Products Part 40: Storage Stability of Diesel Fuels" Issue 1, 2 Dec. 1987.
Beranek Ludek A.
Hiley Robin W.
Marshman Shiela J.
Pedley Joanna F.
Power Alan J.
Bhat Nina
The Commonwealth of Australia
The Secretary of State for Defence in Her Britannic Majesty's Go
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