Exxon Research and Engineering Company

Other

Douglas G Ryan

Robert J Chimenti

Anthony E Cerkanowicz

Milton D Leighton

Donald B Trust

James D Bushnell

Donald J Mintz

Lloyd E Reid

Keith C Yao

Rudolph R Savory

Derek J Watridge

Roy V Comeaux

Steven Ackerman

In a lube oil dewaxing plant in which waxy lube oil is firstly conditioned to promote wax crystallization, such as by adding an oil solvent and chilling the resulting admixture, and then filtered in at least one rotary drum filter (213), the filter includes at least one spray header (92') including a plurality of charge injectors (300) which inject charge by field emission into a field which is sprayed from orifices (246) in the underside of the header onto the filter drum (20). The injected charge has the effect of enhancing separation of haze from the lube oil in the rotary drum filter (213). The charge carrier fluid may for example be solvent-diluted waxy oil or oil solvent liquid alone.

Removing haze from dewaxed hydrocarbon oil mixture boiling in the

For removing haze from dewaxed hydrocarbon oil mixture boiling in the lubricating oil range which is hazy, the hazy oil mixture is filtered in the filtration stage (201) of a dewaxing plant which is concurrently filtering undewaxed hydrocarbon oil mixture boiling in the lubricating oil range. Prior to filtering, the hazy dewaxed oil mixture is subjected to pretreatment (in pretreatment stage 204) such as to promote removal of haze from the dewaxed oil mixture during filtering. This pretreatment is carried out independently of the undewaxed oil mixture and can involve dilution/chilling with an oil solvent (e.g. liquid propane) and/or introduction of free excess electric charge, for example by charge injection. As an alternative to the pretreatment, the temperature conditions under which filtration takes place may be low enough to promote wax crystallization. The filtration stage may comprise a rotary drum filter (213) in which the undewaxed oil mixture is introduced into the filter vat (10), whereas the pretreated dewaxed oil mixture is sprayed onto the wax cake formed on the rotary filter drum.

Process for removing haze from dewaxed hydrocarbon oil mixture boiling

Haze in lube oil is firstly precipitated as wax and ice crystals to form a slurry which is introduced, through inlet (18), into a separation vessel (15) containing a bed of packed aggregate (20) which preferably comprises wax balls, or asphalt or ice chunks. The slurry is indirectly charged with free excess charge which is net unipolar by means of a charge injector 11. The injected charge causes the wax and ice crystals to be electrically driven to and deposited on the aggregate. Periodically, the wax and ice-soiled aggregate is replaced by fresh aggregate and the soiled aggregate can be supplied as feed to a conversion process, which can for example be a catalytic cracking process.

Removing haze from hydrocarbon oil mixture boiling in the lubricating

In solvent de-waxing of lube oil, a stream (3) of chilled waxy oil and solvent is introduced into a centrifugal separation device (2) which separates a quantity of wax from the waxy oil and solvent. The dewaxed oil (DWO) and solvent leaving the centrifuge (2) contains a small proportion of wax fines. By introducing free excess charge which is net unipolar into the stream (3), for example by injecting the charge into a stream (9) of cold solvent introduced into stream (3), enhanced deposit of wax on the centrifuge bowl is achieved, thereby substantially removing the wax fines from the dewaxed oil (DWO) and solvent. Alternatively, a bead separator (22), itself employing charge injection with a charge injection (26) for enhanced wax separation, is used for substantially removing the wax fines in the dewaxed oil and solvent from the centrifugal separation device (2). Preferably, both introduction of free excess charge into the stream (3) admitted to the centrifugal separation device (2) and a bead separator (22) are employed, which can lead to higher throughput in the equipment with minimal wax content of the dewaxed oil and solvent leaving the bead separator.

Method and apparatus for centrifugal separation of dispersed phase from

In order to separate wax from lubricating oil, it is necessary both to introduce free excess charge which is net positive or net negative into the wax-laden oil, preferably by charge injection, and to reduce the solubility for the wax (for example by cooling the lubricating oil) sufficiently so that dissolved wax forms a dispersion of wax particles and crystals in the oil. The resulting electrophoretic effect results in wax particle agglomeration and particle size growth in the oil itself and/or on collector surfaces in contact with the charged oil. The charge injection and the wax solubility reduction such as by cooling can occur simultaneously, or one before the other in either order. Cooling can conveniently be effected wholly or in part by mixing with the oil an auto-refrigerant liquid which vaporizes to reduce the oil temperature. Ideally the auto-refrigerant liquid additionally has oil solvent properties, propane being an example of a suitable such liquid additive. The cooling can also be at least partially effected by heat exchange with a cooling fluid, for example, using a cooling jacket surrounding a separation vessel in which the wax agglomeration and growth occurs or a heat exchanger in the wax-laden oil feed to the separation vessel.

Separating wax from hydrocarbon mixture boiling in the lubricating oil

In order to separate wax particles and/or water droplets from lubricating oil, free excess electric charge which is net positive or net negative is introduced into the wax/water-laden oil, preferably by charge injection. Wax particle/water droplet agglomeration and particle/droplet size growth within the oil mixture due to the electrophoretic effect arising from the electric charge introduction is allowed to occur. In this way, wax particles or water droplets normally considered to be of insufficient size to be separated effectively by filtration can be removed by filtration if the lube oil is electrically pretreated as described. The filtration, conveniently, can be effected by passing the oil mixture containing the grown wax particles/water droplets through a bed of collector beads of low electrical conductivity or through a settler or, in the case of the wax, through a filter screen.

Method and apparatus for separating wax/water from hydrocarbon oil

Used oils, especially used lubricating oils which are normally considered waste and are discarded or burned, are reclaimed for reuse by a re-refining procedure involving the steps of:

Used oil re-refining

Corrosion of the process equipment in solvent extraction units utilizing N methyl-2-pyrrolidone as the selective extraction solvent is significantly reduced by means of a sacrificial metal contacting zone or bed containing a metal or metal alloy with a higher electro chemical potential than the metals used in the extraction unit vessels and lines. Preferred sacrificial metals are magnesium, zinc, calcium, barium, and strontium, most preferably magnesium, as metal strips, shavings, ribbons, sponge, filings, chips, blocks, bricks, etc.

Removal of corrodants from NMP solvent by contacting with sacrificial

An improved rotary drum filter is described. The filter includes a liquid collection means communicating with at least a plurality of fluid conduits. The collection means collect and discharge residual liquid remaining in the fluid conduits during each rotation of the filter drum to decrease the erosive effects of the residual liquid on the filter cloth.

Rotary drum filter

A liquid-vapor contacting apparatus comprising a vertical, mechanically agitated, elongated tower containing a plurality of vertically spaced, horizontally disposed stages therein and means for separating said stages, each of said stages comprising: (a) liquid tray means; (b) a liquid space and a vapor space above said liquid space; (c) weir means capable of maintaining a predetermined amount of liquid on said liquid tray means; (d) a first liquid downcomer means capable of providing a path for liquid from a stage or location immediately above said stage to the liquid space of said stage; (e) a second liquid downcomer means capable of providing a flowpath for the liquid in said stage to the next, lower, successive stage; (f) means capable of removing vapor from said vapor space including vapor downcomer means capable of providing a path for said vapor from said vapor space to the next lower, successive stage in a manner such that said vapor removed from said stage does not pass through liquid presenting any stage; (g) means for introducing liquid or vapor from a source external to said apparatus into or above the liquid space of said stage; and (h) means for mixing said liquid or vapor introduced into said stage with liquid present in said stage.

Mechanically agitated liquid-vapor contacting apparatus

An improved rotary filter is described. A baffle means is disposed between the filter drum and the filter cloth in substantial alignment with at least some of the circumferential openings in the filter drum to decrease the erosive effects on the filter cloth of fluid discharged through the circumferential openings in the filter drum.

A continuous autorefrigerant solvent dewaxing process is disclosed wherein a waxy oil is prediluted with a non-autorefrigerative solvent, such as ketone, preferably a mixture of MEK/MIBK, and then passed, at a temperature above its cloud point, to the top of a chilling zone, which is an autorefrigerant chilling zone operating on a continuous basis, and comprises a vertical, multi-staged tower, operating at constant pressure. In this chilling zone, wax is precipitated from the oil to form a waxy slurry and the so-formed slurry is further chilled down to the wax filtration temperature by stagewise contact with liquid autorefrigerant preferably propylene, which is injected into a plurality of said stages and evaporated therein so as to cool the waxy slurry at an average rate of between about 0.1.degree. to 20.degree. F. per minute with an average temperature drop across each stage of between about 2.degree. and 20.degree. F. Some of the propylene remains in the oil which serves to further dilute and reduce the viscosity of the slurry. The dewaxed oil-containing slurry may then be fed directly to wax filters without having to pass through scraped-surface chillers and filter feed drum.

Continuous autorefrigerative dewaxing process and apparatus

A continuous, combination ketone-autorefrigerant solvent dewaxing process is disclosed wherein a waxy oil is partially solvent dewaxed to within from about 30.degree. to 110.degree. F. of the final wax filtration temperature in a first chilling zone, preferably comprising a plurality of agitated stages in the presence of a ketone dewaxing solvent to form a slurry containing solid wax particles, partially dewaxed oil and solvent. This ketone-containing slurry is passed to a second chilling zone, which is an autorefrigerant chilling zone, preferably employing liquid propylene operates on a continuous basis, and comprises a vertical, multi-staged tower, operating at constant pressure, wherein additional wax is precipitated from the slurry. In the second chilling zone the slurry is chilled down to the wax filtration temperature by stagewise contact with liquid propylene which is injected into a plurality of said stages and evaporated therein so as to cool the waxy slurry at an average rate of between about 0.1.degree. to 20.degree. F. per minute with an average temperature drop across each stage of between about 2.degree. and 20.degree. F. Some of the propylene remains in the oil which serves to further dilute and reduce the viscosity of the slurry. The dewaxed oil-containing slurry may then be fed directly to wax filters without having to pass through scraped-surface chillers and filter feed drum.

Combination dewaxing process

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.

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Rockaway, NJ, United States of America

Douglas G Ryan