Process for producing low pour point transformer oils from paraffinic crudes

Claim 2

A process for producing a low pour point transformer oil which comprises: a. solvent extracting a waxy distillate fraction of a paraffinic crude, said fraction having a 5 to 95% boiling range of 595° to 755° F at atmospheric pressure, to produce an extract and a raffinate; b. solvent dewaxing said raffinate at a temperature of from about -10° to -40° F under liquid-liquid immiscible conditions to form a three-phase slurry containing a solid waxy phase, an oil-rich liquid phase and a solvent-rich liquid phase; c. filtering said slurry at a temperature of from about -10° to about -40° F to form a filtrate substantially comprising the solvent-rich phase which contains the desired transformer oil, and a wax cake containing the oil-rich phase; and d. recovering a low pour point transformer oil from said filtrate only by removing solvent from same.

Claim 3

The process of claim 1 wherein the waxy distillate fraction has a viscosity of 40 to 70 SUS at 100° F.

Claim 4

The process of claim 2 wherein the waxy distillate has a 5 to 95% boiling range of 600° to 735° F at atmospheric pressure.

Claim 5

The process of claim 1 wherein both the dewaxing and filtration occur at from -20° to -30° F.

Claim 6

The process of claim 1 wherein the liquid-liquid immiscible conditions are achieved by adjusting the dewaxing solvent composition.

Claim 7

The process of claim 1 wherein the liquid-liquid immiscible conditions are achieved by adjusting the dewaxing temperature.

Claim 8

The process of claim 1 wherein the dewaxing step includes scraped-surface chilling after mixing the solvent and raffinate.

Claim 9

The process of claim 1 wherein the dewaxing solvent comprises at least two ketones selected from the group consisting of ketones having from 3 to 6 carbon atoms.

Claim 10

The process of claim 8 wherein the dewaxing solvent is selected from the group consisting of MEK/MIBK and acetone/MIBK.

Claim 11

The process of claim 1 wherein the dewaxing solvent is selected from the group consisting of ketones having from 3 to 6 carbon atoms and mixtures thereof and a single ring aromatic solvent.

Claim 12

The process of claim 10 wherein the dewaxing solvent comprises a mixture of MEK and toluene.

Claim 13

The process of claim 9 wherein the acetone ranges from 55 to 95 LV% and the MEK ranges from 45 to 95 LV%.

Claim 14

The process of claim 1 wherein the dewaxing solvent comprises an autorefrigerant and a binary mixture of ketones having 3 to 6 carbon atoms.

Claim 15

The process of claim 13 wherein the autorefrigerant is selected from the group consisting of propylene and propane.

Claim 16

The process of claim 1 wherein the recovered transformer oil has a pour point of less than -40° F.

Claim 17

A process for producing a low pour point transformer oil from paraffinic oils which comprises: a. solvent extracting a waxy distillate fraction of a paraffinic crude, said fraction having a 5 to 95% boiling range of 595° to 755° F atmospheric pressure, to produce an extract and a raffinate; b. solvent dewaxing said raffinate at a temperature of from about -10° to -40° F under liquid-liquid immiscible conditions to form a three-phase slurry containing a solid waxy phase, an oil-rich liquid phase, and a solvent-rich liquid phase, the solvent-rich liquid phase containing the desired transformer oil; c. filtering said slurry at a temperature of from about -10° to about -40° F to form a filtrate comprising the solvent-rich liquid phase which contains the desired transformer oil and a wax cake containing the oil-rich liquid phase; and d. only removing solvent from said filtrate and thereby recovering a transformer oil from same having a pour point below about -40° F.

Claim 18

A process for producing a low pour point transformer oil from paraffinic oils which comprises: a. solvent extracting a waxy distillate fraction of a paraffinic crude, said fraction having a 5 to 95% boiling range of 595° to 755° F atmospheric pressure, to produce an extract and a raffinate; b. solvent dewaxing said raffinate at a temperature of from about -10° to -40° F under liquid-liquid immiscible conditions to form a three-phase slurry containing a solid waxy phase, an oil-rich liquid phase, and a solvent-rich liquid phase, the solvent-rich liquid phase containing the desired transformer oil; c. filtering said slurry at a temperature of from about -10° to about -40° F to form a filtrate comprising the solvent-rich liquid phase which contains the desired transformer oil and a wax cake containing the oil-rich liquid phase; and d. only removing solvent from said filtrate and thereby recovering a transformer oil from same having a pour point below about -40° F.