Systems and methods for producing aviation fuel

A method to produce aviation fuel, the method comprising:

• supplying a hydrodeoxygenated renewable diesel feedstock to a fractionator;
• fractionating the hydrodeoxygenated renewable diesel feedstock into a C8− fraction, a C8-18 fraction, and a C18+ fraction;
• providing the C8-18 fraction to an isomerization reactor to produce an aviation fuel product;
• supplying at least a portion of the C18+ fraction to a hydrocracking reactor to produce a hydrocracked product, the hydrocracking reactor cracking one or more heavy compounds of the C18+ fraction into two or more lighter compounds;
• and
• recycling at least a portion of the hydrocracked product to the fractionator for fractionating along with the hydrodeoxygenated renewable diesel feedstock.

A system to produce aviation fuel, the system comprising:

• a fractionator having a first inlet to receive a renewable diesel feedstock, a first outlet, a second outlet, and a third outlet, the fractionator operable to fractionate the renewable diesel feedstock into a C8− fraction output through the first outlet, a C8-18 fraction output to the second outlet, and a C18+ fraction output to the third outlet;
• a hydrocracking reactor having a second inlet and a fourth outlet, the second inlet connected to and in fluid communication with the third outlet to receive the C18+ fraction, the hydrocracking reactor operable to hydrocrack the C18+ fraction into a hydrocracked product, and the fourth outlet connected to recycle the hydrocracked product to the fractionator;
• and
• an isomerization reactor having a third inlet and a fifth outlet, the third inlet connected to and in fluid communication with the second outlet to receive the C8-18 fraction, and the isomerization reactor operable to isomerize the C8-18 fraction into an aviation fuel product output to the fifth outlet.