Process for removing haze from dewaxed hydrocarbon oil mixture boiling

Abstract

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.