Exxon Research and Engineering Company

Rudolph R Savory

Douglas G Ryan

James D Eagan

Donald B Trust

A wash liquid distributor is described for applying liquid uniformly across a filter cake on a filter surface providing effective washing and exhibiting resistance to clogging and fouling. The wash liquid distributor consists essentially of, in combination, at least one elongated hollow distributor pipe mounted above the filter surface through which wash fluid is passed, each hollow distributor pipe having a multiplicity of closely, evenly spaced and axially aligned small holes located substantially along the top center line of said pipe and pointing away from the filter surface located beneath said pipe, an inner helical wire wrap around said pipe, the pitch of the winding of said wire being substantially the same as the spacing of the axially aligned holes and whereby each individual turn in the winding is spaced to pass substantially midway between adjacent pairs of the evenly spaced, axially aligned holes, a curved deflector plate located on top of the inner helical wire wrap and covers a portion of the circumference of said pipe, the center line of the deflector plate being substantially in alignment with the top center line of the pipe, and a final outer helical wire winding around the pipe holding the deflector plate in position, the pitch of the winding of this outer helix being substantially the same as the inner helix winding but about 180.degree. out of phase.

Drip pipe for application of wash liquid to filter surfaces

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.

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Chatham, NJ, United States of America

Rudolph R Savory