Transportation of waxy hydrocarbon mixture as a slurry

Abstract

Hydrocarbon mixtures containing 1-80% wax, e.g. shale oil, can be transported in a pipeline by distilling the mixture into an overheads fraction and a bottoms fraction, cooling the overheads fraction to a temperature above its pour point, but to a temperature sufficiently low so that when it is admixed with the bottoms fraction, the composite temperature of the mixture will be at or below the temperature at which the mixture is to be transported, and admixing the overheads fraction with the bottoms fraction (at a temperature above that at which wax crystals form) while imparting to the mixture a shear rate less than about 20 sec -1 to form a pumpable slurry. The slurry is preferably transported in a pipeline at conventional temperatures.

What is claimed is: 
     
       1. A process of transporting and/or storing a waxy hydrocarbon mixture containing 1 to about 80% by weight of wax comprising fractionating the hydrocarbon mixture into at least an overheads fraction and a bottoms fraction (contains at least a majority of the wax), mixing at a shear rate less than about 20 sec -1  at least a portion of the overheads fraction which has been cooled to a temperature sufficiently low so that when it is slurried with the bottoms fraction the resulting temperature will be at least below that at which the hydrocarbon mixture will be transported, with at least a major portion of the bottoms fraction which has been heated to a temperature above that at which wax crystallization is effected, to obtain a slurry and thereafter storing or transporting the slurry. 
     
     
       2. The process of claim 1 wherein the shear rate is less than about 10 sec -1 . 
     
     
       3. The process of claim 1 wherein the shear rate is less than about 5 sec -1 . 
     
     
       4. The process of claim 1 wherein the resulting slurry is transported in a conduit at a temperature below the solution temperature of the dispersed bottoms fraction in the overheads fraction. 
     
     
       5. The process of claim 1 wherein the hydrocarbon contains about 5 to about 65% by weight of wax. 
     
     
       6. The process of claim 1 wherein the hydrocarbon contains about 10 to about 50% by weight of wax. 
     
     
       7. The process of claim 1 wherein the overheads fraction has a viscosity less than about 10 cp. at the seasonably minimum temperature of the transportation system. 
     
     
       8. The process of claim 1 wherein the resulting slurry contains about 5 to about 55% of wax. 
     
     
       9. The process of claim 1 wherein the resulting slurry contains about 10 to about 45% of wax. 
     
     
       10. The process of claim 1 wherein the overheads fraction is cooled to a sufficiently low temperature such that when mixed with the bottoms fraction, the resulting temperature of the mixture is less than about 5° C. below the temperature at which the slurry is to be transported. 
     
     
       11. The process of claim 1 wherein external cooling is used during mixing to remove a portion of the heat from the bottoms fraction. 
     
     
       12. The process of claim 1 wherein the waxy hydrocarbon mixture is a waxy crude oil, shale oil, or hydrogenated shale oil. 
     
     
       13. A process of transporting a waxy hydrocarbon mixture containing about 5 to about 65% by weight of wax comprising distilling the hydrocarbon mixture into at least an overheads fraction and a bottoms fraction (contains at least a majority of the wax), mixing at a shear rate less than about 10 sec -1 , the overheads fraction which has been cooled to a temperature sufficiently low so that when it is mixed with the bottoms fraction the temperature of the mixture will be below the temperature at which the mixture is to be transported, with at least a major portion of the bottoms fraction which is at a temperature at least above that at which wax crystallization occurs in the bottoms fraction, to obtain a slurry suitable for transportation, and thereafter transporting the slurry in a pipeline. 
     
     
       14. The process of claim 13 wherein the slurry contains about 10 to about 45% by weight of wax. 
     
     
       15. The process of claim 13 wherein the hydrocarbon mixture is a waxy crude oil, shale oil or hydrogenated shale oil. 
     
     
       16. A method of preparing a waxy hydrocarbon slurry suitable for storage and/or transportation wherein the waxy hydrocarbon mixture contains about 1 to 80% by weight of wax, comprising fractionating the hydrocarbon mixture into at least an overheads fraction and a bottoms fraction, the bottoms fraction containing at least a majority of the wax, admixing at a shear rate less than about 20 sec -1  the overheads fraction which has been cooled to a sufficiently low temperature such that when admixed with the bottoms fraction, the temperature of the resulting slurry will be less than the temperature at which the slurry is transported, with at least a major portion of the bottoms fraction which is at a temperature above that at which substantial wax crystallization is effected, to obtain a pumpable slurry. 
     
     
       17. The process of claim 16 wherein the pumpable slurry contains about 5 to about 55% by weight of the wax. .Iadd. 
     
     
       18.  The process of claim 1 wherein the shear rate is less than about 15 sec -1 . .Iaddend. .Iadd.19. A process of transporting a waxy hydrocarbon mixture containing about 5 to about 65% by weight of wax comprising distilling the hydrocarbon mixture into at least an overheads fraction and a bottoms fraction (contains at least a majority of the wax), mixing at a shear rate less than about 20 sec -1  the overheads fraction, which has been cooled to a temperature sufficiently low so that when it is mixed with the bottoms fraction the temperature of the mixture will be below the temperature at which the mixture is to be transported, with at least a major portion of the bottoms fraction which is at a temperature at least above that at which wax crystallization occurs in the bottoms fraction, to obtain a slurry suitable for transportation, and thereafter transporting the slurry in a pipeline.