Exxon Research and Engineering Company

James D Bushnell

Milton D Leighton

John H Blume

Douglas G Ryan

Biddanda U Achia

Bruce M Sankey

Robert J Fiocco

David H Shaw

Alexandr P Glivicky

Thomas M McDonald

A method for increasing the production of deasphalted oil is described. The method comprises passing a hydrocarbon feedstock into a first distillation zone wherein the feedstock is separated into a first distillate and a first residuum. First residuum is passed to a second distillation zone wherein the fraction is separated into a second distillate and a second residuum. Second distillate and residuum are passed to a deasphalting zone and contacted with a solvent to produce a deasphalted oil. This method may produce increased quantities of acceptable quality deasphalted oil where the deasphalting zone is rate-limiting.

Method for increasing deasphalted oil production

An improved cascade weir type extraction zone is described in which at least one of the weir means is disposed above the associated tray. This improved extraction zone is of particular utility in lube oil processing operations.

Extraction zone

An improved tray means and an extraction zone utilizing the tray means are disclosed. The tray means comprises a tray deck, a channel means, and a weir means. The tray deck and channel means cooperate to form a fluid conduit through which fluid flows from beneath the tray deck to the weir means. The tray means is useful in cross flow liquid-liquid extraction zones, with particular applicability to extractive purification of lube oils.

Extraction zone tray

An improved process for removing H.sub.2 S from a hydrofiner tail gas wherein said tail gas is passed into a scrubbing zone wherein it is contacted with liquid NMP to remove most of the H.sub.2 S from the gas to form an H.sub.2 S-rich NMP solution and the H.sub.2 S-rich NMP solution is heated and passed into a stripping zone to remove most of the H.sub.2 S from the NMP to form an H.sub.2 S-lean NMP solution, extracting a hydrocarbon oil with an NMP solution, recovering hot liquid, NMP from said extracted oil and combining it with said H.sub.2 S-lean NMP solution and wherein said combined solution comprises at least a portion of said NMP solution used to extract said oil, wherein the improvement comprises heating the H.sub.2 S-rich NMP solution to the required stripping temperature by indirectly contacting same, in heat exchange relationship, with at least a portion of said combined NMP solution. This process is especially useful for scrubbing H.sub.2 S from hydrofiner tail gas for use as once-through stripping gas in the solvent recovery section of a lube oil extraction process employing NMP as the extraction solvent, and in a preferred embodiment, the spent stripping gas from the lube oil solvent recovery is used as the stripping gas in the stripping zone of this invention.

Removing H.sub.2 S from gas with recycled NMP extraction solvent

In a DILCHILL* dewaxing process employing rotary drum wax filters, the waxy slurry in the filters must be periodically dumped and the filters washed with hot solvent to remove wax fines which plug the cloth. The dumped slurry contains useful oil which can be recovered, with no detriment to the subsequent filter rate, by mixing the dumped slurry with the hot filter washings and recycling this mixture back into the DILCHILL dewaxing zone at one or more points therein wherein the temperature of the recycled mixture is from about 5.degree. to 50.degree. F. lower than the bulk temperature of the oil in the dewaxing zone and in an amount ranging from about 0.02 to 0.4 volumes of recycle per volume of feed.

Recovering useful oil from wax filter hot washings and dumped slurry

An asphalt containing mineral oil is simultaneously deasphalted and extracted in a combination zone by contacting the oil with a solvent comprising N-methyl-2-pyrrolidone (NMP) containing from 0-5 LV% water and a light hydrocarbon to produce a raffinate and extract phase, with the raffinate phase containing the desired oil, most of the hydrocarbon solvent and some NMP. The raffinate is then passed to a reduced pressure zone to remove most of the hydrocarbon solvent therefrom. The remaining raffinate oil and NMP solution is then chilled to produce bulk liquid-liquid immiscibility between the oil and NMP. The chilled oil and NMP are then passed to a settling zone wherein the NMP is separated from the oil and recycled back into the combination zone.

Simultaneous deasphalting-extraction process

N-methyl-2-pyrrolidone is recovered from the raffinate and extract phases produced by its use in hydrocarbon extraction processes, particularly lube oil extraction, through the use of flash evaporation and/or distillation followed by gas stripping. Water buildup in the recovered solvent is prevented by employing solvent dehydration means in the solvent recovery line after gas stripping. Proper control of process parameters enables the dehydration means to remove excess water without requiring additional heat input to the process.

Solvent recovery process for N-methyl-2-pyrrolidone in hydrocarbon

Autorefrigerative and ketone solvents are separated and recovered from dewaxed oil and wax through the use of high and low pressure flashes followed by steam stripping. Water buildup in the recovered solvent is prevented by the use of a decanter and deketonizer wherein the overheads from the strippers are sent directly to the deketonizer and the overhead therefrom sent to the decanter, thereby substantially reducing the size of the deketonizer required. Water is removed from the recovered solvent in the deketonizer and may be sent to sewerage.

Method of solvent recovery in autorefrigerant/ketone dewaxing processes

Lubricating oil stocks are upgraded by contacting same with a solvent comprising a mixture of n-methyl-2-pyrrolidone (NMP) and phenol. The solvent may also contain a minor amount of water. The phenol concentration in the solvent ranges between about 20 and 80 LV% based on the total amount of NMP, phenol and water in the solvent, while the water concentration in the solvent ranges between 0 and about 10 LV% based on the total amount of NMP, phenol and water in the solvent and preferably between about 1 and 4 LV%. At least a portion of the solvent is recovered from the thus-formed extract and raffinate phases by heating same to temperatures in the range of about 500.degree. to 700.degree. F., thereby flashing off the bulk of the solvent; remaining solvent may be stripped out from the extract and raffinate phases with an inert gas such as nitrogen, light hydrocarbons or hydrogen at superatmospheric pressures. The hot, stripped raffinate may be sent directly to a hydrofiner reactor, if desired, for further improvement of color, carbon residue, viscosity characteristics, sulfur removal, etc.

Lube extraction with NMP/phenol/water mixtures

An asphalt-containing mineral oil is deasphalted by contacting the oil at elevated temperature and elevated pressure with a deasphalting solvent comprising acetone and a three carbon atom containing-hydrocarbon, such as propylene, for a time sufficient to remove a substantial portion of the asphaltenes from the oil. Utilization of propylene-acetone as the deasphalting solvent permits utilization of higher treating tower temperatures, which may be desirable in those instances where air cooling of the solvent is provided. This process is particularly suited for the preparation of lubricating oils of low asphalt content.

Deasphalting process

A dewaxing process is provided in which a mixture of a solvent comprising propylene-acetone and a waxy petroleum oil is contacted with a cold aqueous solution of acetone and methanol. The aqueous acetone-methanol solution, which is immiscible in the waxy oil-solvent mixture, cools the mixture thereby crystallizing a substantial portion of the wax in the mixture.

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Berkeley Heights, NJ, United States of America

James D Bushnell