Methods and systems are provided herein utilizing a membrane cascade to separate a hydrocarbon feed into boiling point fractions. Also provided herein are methods for selecting membranes for said cascades to achieve the desired boiling point fraction separation.

A method for selective removal of polycyclic aromatic hydrocarbons from oils obtained as a result of petroleum processing, including two separate processes: filtration through a porous carbon-containing bed comprising and filtration through microfiltration membranes. The method is particularly useful for purifying oils selected from unconverted oils obtained in hydrocracking processes, products of further processing of these oils, engine oil and used engine oil.

Methods for conserving the use of fresh wash water in crude oil desalting are described. A crude oil stream including salt mixes with a wash water stream to form an emulsion. The emulsion flows to a desalter, and the wash water coalesces to reform the wash water stream and to transfer at least a portion of the salt from the crude oil stream to the wash water stream. The crude oil stream with reduced salt content separates from the wash water stream. The effluent, which includes the wash water stream, flows from the desalter to a processing unit. The effluent is processed to reduce a concentration of salt in the effluent to be substantially equal to or less than a concentration of salt in the wash water stream. At least a portion of the processed effluent mixes with the crude oil stream before the emulsion flows to the desalter.

Methods for conserving the use of fresh wash water in crude oil desalting are described. A crude oil stream including salt mixes with a wash water stream to form an emulsion. The emulsion flows to a desalter, and the wash water coalesces to reform the wash water stream and to transfer at least a portion of the salt from the crude oil stream to the wash water stream. The crude oil stream with reduced salt content separates from the wash water stream. The effluent, which includes the wash water stream, flows from the desalter to a processing unit. The effluent is processed to reduce a concentration of salt in the effluent to be substantially equal to or less than a concentration of salt in the wash water stream. At least a portion of the processed effluent mixes with the crude oil stream before the emulsion flows to the desalter.

The invention relates to the oil-refining industry, in particular, to methods for purifying a fuel from sulfur-containing compounds. The method for purifying liquid hydrocarbon motor fuels from sulfur and for further reducing the sulfur dioxide content in exhaust gases up to zero during combustion of the fuels by modifying the sulfur-containing fuel molecules in a fully-developed cavitation mode, by separating the sulfur-containing modified molecules from the remainder of the fuel molecules on polymer membranes and by activating the fuel purified up to 20 ppm in the fully-developed cavitation mode prior to the combustion. What is novel is that the reduction of the sulfur content in the fuel is achieved by means of treating the fuel or a fuel fraction in the fully-developed cavitation mode with addition of a hydrogen peroxide aqueous solution and/or a strong aqueous solution of iron oxides to the fuels, followed by separating the obtained emulsion into a fuel fraction and a water-paraffin emulsion, followed by separating the fuel fraction on the membranes under the temperature of from 90 C. to 180 C. under the atmospheric pressure into a fuel fraction having a low sulfur content and a fuel fraction having an increased sulfur content. Reduction of the sulfur dioxide in the exhaust gases during combustion of the purified fuels up to zero by means of activation of the fuels having the low sulfur content in the fully-developed cavitation mode is performed without addition of other chemical substances. Production of a reduced oil-water emulsion from the water-paraffin emulsion and the fuel fraction having the increased sulfur content that increases the efficiency of reduced oils combustion is performed in boiler units. Reduction of the sulfur content in the fuel or fuel fractions is performed up to the required level of 20 ppm or less. Treatment of the initial fuel or fuel fraction by the cavitation is performed under the pressure of 1.0-0.5.0 atm and the temperature of 20 C.-70 C.

Methods for conserving the use of fresh wash water in crude oil desalting are described. A crude oil stream including salt mixes with a wash water stream to form an emulsion. The emulsion flows to a desalter, and the wash water coalesces to reform the wash water stream and to transfer at least a portion of the salt from the crude oil stream to the wash water stream. The crude oil stream with reduced salt content separates from the wash water stream. The effluent, which includes the wash water stream, flows from the desalter to a processing unit. The effluent is processed to reduce a concentration of salt in the effluent to be substantially equal to or less than a concentration of salt in the wash water stream. At least a portion of the processed effluent mixes with the crude oil stream before the emulsion flows to the desalter.

Methods for conserving the use of fresh wash water in crude oil desalting are described. A crude oil stream including salt mixes with a wash water stream to form an emulsion. The emulsion flows to a desalter, and the wash water coalesces to reform the wash water stream and to transfer at least a portion of the salt from the crude oil stream to the wash water stream. The crude oil stream with reduced salt content separates from the wash water stream. The effluent, which includes the wash water stream, flows from the desalter to a processing unit. The effluent is processed to reduce a concentration of salt in the effluent to be substantially equal to or less than a concentration of salt in the wash water stream. At least a portion of the processed effluent mixes with the crude oil stream before the emulsion flows to the desalter.

Methods for conserving the use of fresh wash water in crude oil desalting are described. A crude oil stream including salt mixes with a wash water stream to form an emulsion. The emulsion flows to a desalter, and the wash water coalesces to reform the wash water stream and to transfer at least a portion of the salt from the crude oil stream to the wash water stream. The crude oil stream with reduced salt content separates from the wash water stream. The effluent, which includes the wash water stream, flows from the desalter to a processing unit. The effluent is processed to reduce a concentration of salt in the effluent to be substantially equal to or less than a concentration of salt in the wash water stream. At least a portion of the processed effluent mixes with the crude oil stream before the emulsion flows to the desalter.

Methods for conserving the use of fresh wash water in crude oil desalting are described. A crude oil stream including salt mixes with a wash water stream to form an emulsion. The emulsion flows to a desalter, and the wash water coalesces to reform the wash water stream and to transfer at least a portion of the salt from the crude oil stream to the wash water stream. The crude oil stream with reduced salt content separates from the wash water stream. The effluent, which includes the wash water stream, flows from the desalter to a processing unit. The effluent is processed to reduce a concentration of salt in the effluent to be substantially equal to or less than a concentration of salt in the wash water stream. At least a portion of the processed effluent mixes with the crude oil stream before the emulsion flows to the desalter.

A liquid hydrocarbon fuel containing dissolved oxygen is at least partially deoxygenated with a membrane device comprising a composite hollow fiber membrane that is comprised of an ultra-thin amorphous fluoropolymer layer superimposed on a porous PEEK polymer substrate.