Continuous process and apparatus for adsorbent bleaching of triglyceride oils

In a continuous process for bleaching oil with bleaching clay, the improvement comprising:

• heating the oil to bleaching temperature in the range of approximately 70.degree. C. to 180.degree. C., continuously introducing the heated oil tangentially into an upper region of a mixing vessel having a lower section of conical configuration, continuously introducing bleaching clay containing moisture onto the surface of the heated oil in said vessel and withdrawing the mixture of oil and clay from a lower region of said vessel, whereby moisture is vaporized from said clay and forms a layer of steam or water vapor over the oil in the vessel to protect it from atmospheric oxidation.

A continuous process for bleaching oil comprising:

• preheating a stream of oil to bleaching temperature, introducing said heated oil into a mixing zone having an outlet in a lower region thereof, introducing bleaching adsorbent containing moisture into the oil in said mixing zone, causing said oil and adsorbent to swirl through said mixing zone whereby the adsorbent is mixed with the oil and moisture is vaporized to form a protective layer above the surface of the oil in said zone, withdrawing the oil-adsorbent mixture through said outlet and introducing it into a bleaching zone comprising one or more static mixers, controlling the flow rate of the oil-adsorbent mixture through said bleaching zone such that no more than about 10% of the mixture remains in said bleaching zone for a time period greater than 1.5 minutes, and filtering the adsorbent from the bleached oil.

A continuous process for bleaching oil comprising:

• preheating a stream of oil to a temperature in the range of 70.degree. C. to 180.degree. C., introducing the heated oil tangentially into a conical mixing zone, having an outlet in a lower region thereof, in such manner as to cause the oil to vigorously swirl downwardly through said zone, continuously adding bleaching clay containing moisture to the surface of said swirling hot oil whereby the oil and clay are mixed in said zone by the swirling movement of the oil and water is vaporized from the clay to form a protective atmosphere of water vapor or steam over the surface of the oil to protect the oil from atmospheric oxidation, withdrawing the oil-clay mixture through said outlet and introducing said mixture into a deaeration zone, deaerating the mixture and adjusting the moisture content of the oil in the deaeration zone, pumping the oil-clay mixture from the deaeration zone through a bleaching zone comprising one or more static mixers such that the average residence time of the mixture in the bleaching zone is no greater than approximately one minute, and filtering the clay from the oil.

A continuous process for bleaching oil comprising heating a stream of oil to bleaching temperature, passing said stream of heated oil into a mixing zone, adding bleaching clay to said heated oil in said mixing zone, the residence time of the oil and clay in said mixing zone being less than about one minute, passing the resultant oil/clay mixture through a bleaching zone comprising one or more static mixers which are substantially free of elements that would cause backmixing and short circuiting, at a flow velocity such that there is substantially no settling of the clay in the oil and such that no more than about 10% of the flow passes through said bleaching zone in less than 0.5 minutes and no more than about 10% of the flow through said zone requires more than 1.5 minutes, and filtering the clay from the bleached oil, the total time between clay addition in the mixing zone and filtration of the clay after bleaching being no more than about 3 minutes.

Apparatus for the adsorbent bleaching of oils, comprising means for heating said oil to bleaching temperature, a mixing vessel having a bottom section of conical configuration, means for introducing hot oil from said heating means tangentically into said mixing vessel to cause said oil to swirl therein, means for metering powdered solid adsorbent continuously into the top of said vessel upon the surface of the oil therein, an outlet in a bottom region of said mixing vessel, bleaching means comprising at least one static mixer, and means for transferring oil/adsorbent mixture from said outlet to said bleaching means.