Boiling free fractionation of hydrocarbon streams utilizing a membrane cascade

A process for fractionating a liquid hydrocarbon stream into boiling point fractions, comprising:

• providing a liquid hydrocarbon stream;
• selecting a first stage membrane effective to separate a liquid hydrocarbon feed into a first stage permeate and a first stage retentate;
• wherein the heaviest molecule in the first stage permeate has a boiling point in the kerosene boiling range;
• selecting a second stage membrane effective to separate a liquid hydrocarbon feed into a second stage permeate and a second stage retentate;
• wherein the heaviest molecule in the second stage permeate has a boiling point in the diesel boiling range;
• selecting a third stage membrane effective to separate a liquid hydrocarbon feed a third stage permeate and a third stage retentate;
• wherein the heaviest molecule in the third stage permeate has a boiling point in the gas oil boiling range;
• selecting a fourth stage membrane effective to separate a liquid hydrocarbon feed into a fourth stage permeate and a fourth stage retentate;
• wherein the heaviest molecule in the fourth stage permeate has a boiling point in the naphtha boiling range;
• and
• feeding the liquid hydrocarbon stream to one of the first, second, third, and fourth stage membranes under effective separation conditions;
• feeding the applicable stage permeate and retentate to either a downstream refinery process or to another membrane stage;
• and
• repeating the preceding act until each of the first, second, third, and fourth stage membranes has performed a separation on the liquid hydrocarbon stream, permeate from a previous membrane stage, or retentate from a previous membrane stage;
• and
• wherein the selecting a membrane for any of the stages comprises:
• obtaining compositional data of the liquid hydrocarbon stream;
• said compositional data comprising one or more of API gravity, average molecular weight, aromaticity, average boiling point, density, total sulfur and nitrogen content, pour point, viscosity, metal content, total acid number (TAN), reid vapor pressure, Micro Carbon Residue content, C7 asphaltenes content, paraffin-naphthene-aromatic content, carbon to hydrogen ratio, and STAR-7 analysis;
• determining a desired diffusion of molecules through the membrane;
• selecting a membrane based on a relationship of diffusion of molecules through membrane based on temperature, viscosity of the feed, molecular weight and size/radius of molecules;
• wherein determining the relationship comprises;
• obtaining a liquid hydrocarbon feed of known composition;
• obtaining a membrane;
• performing a separation experiment by contacting the liquid hydrocarbon feed of known composition with the membrane thereby forming a control permeate and a control retentate;
• analyzing the control permeate and the control retentate via one of simulated distillation, elemental analysis, and START analysis;
• and
• establishing at least one parameter unique to the membrane as an input to relationship of diffusion of molecules on temperature, viscosity, molecular weight and size/radius of molecules.