Membrane method of removing oil-soluble metals from hydrocarbons

Abstract

A method of removing an oil-soluble metal from a hydrocarbon feedstock comprises passing the hydrocarbon feedstock through a nanofiltration membrane or a reverse osmosis membrane to produce a permeate stream having at least a vanadium concentration less than an initial vanadium concentration in the hydrocarbon feedstock, and a retentate stream having at least a vanadium concentration greater than the initial vanadium concentration in the hydrocarbon feedstock.

Description

BACKGROUND[0001]The present disclosure generally relates to methods of removing vanadium and other oil-soluble metals from hydrocarbons, and more particularly, to membrane methods of removing vanadium and other oil-soluble metals from hydrocarbons.[0002]Various petroleum feedstocks and products, such as crude petroleum oils, heavy vacuum gas oils, shale oils, oils from bituminous sands, topped crudes, atmospheric or vacuum residual fractions, and residual-grade fuel oils contain varying amounts of non-metallic and metallic impurities. The non-metallic impurities usually include nitrogen, sulfur, and oxygen. The metallic impurities usually include nickel, vanadium, iron, sodium, copper, zinc, and arsenic. Most metallic impurities are present as inorganic sulfides, oxides, and water-soluble constituents, while the remainder is usually in the form of relatively thermally stable organometallic complexes such as metal porphyrins and derivatives thereof.[0003]When combusted in a turbine, ...

AI Technical Summary

Benefits of technology

[0007]In one embodiment, a method of removing an oil-soluble metal from a hydrocarbon feedstock, the method comprises passing the hydrocarbon feedstock through a nanofiltration membrane or a reverse osmosis membrane to produce a permeate stream having at least a vanadium concentration less than an initial vanadium concentration in the hydrocarbon feedstock, and a retentate stream having at least a vanadium concentration greater than the initial vanadium concentration in the hydrocarbon feedstock.

[0008]In one embodiment, a method of removing an oil-soluble metal from a hydrocarbon feedstock, the method comprises passing the hydrocarbon feedstock through a microfilter to produce a pre-filtered stream; passing the pre-filtered stream through an ultrafiltration membrane to produce an ultrafiltration stream; passing the ultrafiltration stream through a nanofiltration membrane or a reverse osmosis membrane to produce a permeate stream having at least a vanadium concentration less than an initial vanadium concentration in the hydrocarbon feedstock, and a retentate stream having at least a vanadium concentration greater than the initial vanadium concentration in the hydrocarbon feedstock.

Problems solved by technology

When combusted in a turbine, various inorganic impurities in the fuel (e.g., sodium-, potassium-, lead-, mercury-, and vanadium-containing compositions) can cause hot corrosion of the various parts of the turbine.

While fuel washing, centrifuging, and the like can treat alkali metals, vanadium and other oil-soluble metals are chemically bound to fuel and cannot be removed by traditional methods.

Vanadium pentoxide is particularly damaging to the various parts of the turbine, since it is in a liquid state at normal combustion temperatures of the turbine.

Although several corrosion mechanisms can occur, one frequently observed manifestation is surface oxidation and / or pitting of the various turbine parts caused by low melting point (i.e., having a melting point lower than the operating temperatures to which they are exposed) ash deposits originating from these inorganic impurities in the fuel.

Unfortunately, over extended periods of operation, these and other deposits can build up and partially block the flow of hot gas through the turbine.

Further, various corrosion inhibitors are also not suitable for some turbine applications.

For example, use of magnesium as an inhibitor is not a solution for aero-derivative turbines, since it forms magnesium oxide at aero-derivative turbine operating temperatures.

Images