Distillate fuel with improved seal swell properties

Abstract

The invention provides a distillate fuel blend with improved seal swell properties comprising at least one highly paraffinic distillate fuel fraction having a mass swelling ratio less than 9% when measured according to ASTM D1414 or ASTM D471 at 50° C. and for 20 days when using an NBR (nitrile butadiene rubber) O-ring with a hardness of 70 that has been de-plasticised; and about 0.5 volume percent to about 15 volume percent of at least one component selected from a group of aromatic ethers wherein the blend exhibits a mass swelling ratio of at least 10% when measured according to ASTM D1414 or ASTM D471 at 50° C. and for 20 days when using an NBR (nitrile butadiene rubber) O-ring with a hardness of 70 that has been de-plasticised. The invention extends to the use of an aromatic ether fraction in a blend with a synthetic middle distillate fraction for the purposes of achieving seal swell characteristics more comparable with those characteristic of crude-derived middle distillate fuel product.

1 - 16 . (canceled) 
     
     
         17 . A distillate fuel blend with improved seal swell properties comprising:
 at least one synthetic paraffinic middle distillate fuel fraction derived from a Fischer-Tropsch process or a biological source, the synthetic paraffinic middle distillate fuel fraction having a mass swelling ratio less than 9% when measured according to ASTM D1414 or ASTM D471 at 50° C. and for 20 days when using a nitrile butadiene rubber O-ring with a hardness of 70 that has been de-plasticised; and   about 0.5 volume percent to about 15 volume percent of at least one component selected from the group consisting of aromatic ethers.   
     
     
         18 . The distillate fuel blend of  claim 17 , wherein the synthetic paraffinic middle distillate fuel fraction has a mass swelling ratio less than 6.5% when measured according to ASTM D1414 or ASTM D471 at 50° C. and for 20 days when using a nitrile butadiene rubber O-ring with a hardness of 70 that has been de-plasticised. 
     
     
         19 . The distillate fuel blend of  claim 17 , wherein the distillate fuel blend comprises about 0.5 volume percent to about 10 volume percent of at least one component selected from the group consisting of aromatic ethers. 
     
     
         20 . The distillate fuel blend of  claim 17 , wherein the distillate fuel blend comprises about 0.5 volume percent to about 6 volume percent of at least one component selected from the group consisting of aromatic ethers. 
     
     
         21 . The distillate fuel blend of  claim 17 , wherein the distillate fuel blend has a total aromatic content of less than 8 mass %. 
     
     
         22 . The distillate fuel blend of  claim 17 , having seal swell characteristics comparable with those characteristic of crude-derived middle distillate fuel products. 
     
     
         23 . The distillate fuel blend of  claim 22 , wherein the synthetic paraffinic middle distillate fuel fraction is highly paraffinic. 
     
     
         24 . The distillate fuel blend of  claim 22 , wherein the synthetic paraffinic middle distillate fuel fraction is a jet fuel or a kerosene fraction. 
     
     
         25 . The distillate fuel blend of  claim 22 , wherein the synthetic paraffinic middle distillate fuel fraction is derived or partly derived from Fischer-Tropsch product. 
     
     
         26 . The distillate fuel blend of  claim 22 , wherein an aromatic ether fraction of the distillate fuel blend comprises a single aromatic ether species. 
     
     
         27 . The distillate fuel blend of  claim 22 , wherein an aromatic ether fraction of the distillate fuel blend comprises a combination of aromatic ether species. 
     
     
         28 . The distillate fuel blend of  claim 22 , wherein an aromatic ether fraction of the distillate fuel blend has a boiling point or boiling point range that lies in a middle distillate boiling point range.