Aviation gas turbine fuel with improved low temperature operability

Abstract

The addition of biodiesel to petroleum-based kerosene jet fuels in very low concentrations can lower the temperature at which crystals appear in the fuel. The fuels can comprise a blend of a hydrocarbon base fuel component and, for example, up to 1000 ppm, v/v of the total fuel, of a biodiesel component comprising a lower alkyl ester of a fatty acid of natural origin having from 8 to 24 carbon atoms; these blends can be characterized by improved low temperature flow properties, especially of Cloud Point (ASTM D 2500), which can be lower than that of the petroleum fuel component without the alkyl ester, even in the presence of dissolved water up to the saturation level.

What is claimed is: 
     
         1 . A petroleum-based aviation gas turbine fuel comprising a blend of a hydrocarbon base petroleum fuel component and a sufficient non-zero amount, up to 1% by volume of the total fuel, of a lower alkyl ester of a fatty acid of natural origin having from 8 to 24 carbon atoms, such that the blend exhibits a Cloud Point (ASTM D 2500) at least 1° C. lower than that of the petroleum fuel component without the alkyl ester. 
     
     
         2 . An aviation gas turbine fuel according to  claim 1 , in which the amount of the lower alkyl ester is from 10 to 1000 ppm, v/v of the total fuel, and the blend exhibits a Cloud Point (ASTM D 2500) at least 3° C. lower than that of the petroleum fuel component without the alkyl ester. 
     
     
         3 . An aviation gas turbine fuel according to  claim 2 , in which the amount of the lower alkyl ester is from 10 to 50 ppm, v/v of the total fuel, and the blend exhibits a Cloud Point (ASTM D 2500) at least 3° C. lower than that of the petroleum fuel component without the alkyl ester. 
     
     
         4 . An aviation gas turbine fuel according to  claim 2 , in which the amount of the lower alkyl ester is from 100 to 300 ppm, v/v of the total fuel, and the blend exhibits a Cloud Point (ASTM D 2500) at least 3° C. lower than that of the petroleum fuel component without the alkyl ester. 
     
     
         5 . An aviation gas turbine fuel according to  claim 1 , in which lower alkyl ester comprises a methyl ester of a C 8  to C 22  fatty acid of natural origin. 
     
     
         6 . An aviation gas turbine fuel according to  claim 5 , in which lower alkyl ester comprises a methyl ester of a C 12  to C 22  fatty acid of natural origin. 
     
     
         7 . An aviation gas turbine fuel according to  claim 6 , in which lower alkyl ester comprises a methyl ester of a C 12  to C 18  fatty acid of natural origin. 
     
     
         8 . An aviation gas turbine fuel according to  claim 5 , in which lower alkyl ester comprises a methyl ester of a fatty acid derived from rapeseed oil. 
     
     
         9 . An aviation gas turbine fuel according to  claim 5 , in which lower alkyl ester comprises a methyl ester of a fatty acid derived from soybean oil. 
     
     
         10 . An aviation gas turbine fuel according to  claim 5 , in which lower alkyl ester comprises a methyl ester of a fatty acid derived from palm oil. 
     
     
         11 . An aviation gas turbine fuel according to  claim 5 , in which lower alkyl ester comprises a methyl ester of a fatty acid derived from tallow. 
     
     
         12 . An aviation gas turbine fuel according to  claim 5 , in which lower alkyl ester comprises a blend of methyl esters of fatty acids derived from rapeseed oil, soybean oil, palm oil, and tallow. 
     
     
         13 . An aviation gas turbine fuel according to  claim 1 , which conforms to the specification for Jet A and/or Jet A-1 (Def. Stan. 91-91 and/or ASTM D1655). 
     
     
         14 . An aviation gas turbine fuel according to  claim 1 , which conforms to the specification for JP-5 (MIL-T-5624 N). 
     
     
         15 . An aviation gas turbine fuel according to  claim 1 , which conforms to the specification for JP-8 (MIL-T-83133C). 
     
     
         16 . An aviation gas turbine fuel according to  claim 1 , which contains a total amount of water, wherein the petroleum component has a water saturation level, and wherein the total amount of water in the fuel is less than or equal to said water saturation level. 
     
     
         17 . An aviation gas turbine fuel according to  claim 1 , which contains free water in an amount up to 30 ppm, v/v of the total fuel. 
     
     
         18 . An aviation gas turbine fuel according to  claim 1 , which has a Freeze Point (ASTM D5972) within 1° C. of a Freeze Point of the petroleum fuel component without the alkyl ester. 
     
     
         19 . An aviation gas turbine fuel according to  claim 1 , which has a Cold Filter Plugging Point (ASTM D6371) within 1° C. of a Cold Filter Plugging Point of the petroleum fuel component without the alkyl ester. 
     
     
         20 . An aviation gas turbine fuel according to  claim 1 , which has a Cloud Point (ASTM D2500) at least 5° C. lower than a Cloud Point of the petroleum fuel component without the alkyl ester.