Process for separating low api gravity oil from water

Claim 2

IN A PROCESS FOR TREATING WATER CONTAMINATED WITH LOW API GRAVITY OIL TO REMOVE THE OIL CONTAMINENT THEREFROM WHEREIN SAID CONTAMINATED WATER IS CONTACTED WITH FINELY DIVIDED GAS BUBBLES IN A FLOTATION CHAMBER TO FLOAT THE OIL TO THE SURFACE OF SAID WATER, OIL IS MECHANICALLY REMOVED FROM THE SURFACE OF PRISING A FILTER CHAMBER HAVING AT LEAST ONE FILTERING SURFACE, THE INTERIOR OF SAID CHAMBER BEING IN FLUID COMMUNICATION WHICH COMPRISES ADDING TO SAID CONTAMINATED WATER PRIOR TO ITS INTRODUCTION INTO SAID FLOTATION CHAMBER ABOUT 1 TO 10 VOLUMES OF A HIGH API GRAVITY CRUDE PETROLEUM PER VOLUME OF SAID LOW API GRAVITY OIL, SAID HIGH API GRAVITY CRUDE PETROLEUM HAVING AN API GRAVITY ABOVE ABOUT 35*.

Claim 3

The process defined in claim 1 wherein said low API gravity oil contaminant has an API gravity of less than about 20*.

Claim 4

A process for removing low API gravity oil from oil-contaminated water, which comprises; adding a high API gravity crude petroleum having an API gravity above about 35* to said oil-contaminated water in the proportion of about 1 to 10 volumes of said high API gravity crude petroleum per volume of low API gravity oil in said contaminated water; introducing said oil-contaminated water and high API gravity crude petroleum mixture into a flotation chamber; dispersing finely divided gas bubbles into said oil-contaminated water and high API gravity crude petroleum mixture in said flotation chamber whereby oil is floated to the surface of said water; removing oil and/or particulate solid material from the surface of said water; and withdrawing water having a reduced oil content from said flotation chamber.

Claim 5

A process for removing low API gravity oil from oil-contaminated water, which comprises; adding a high API gravity crude petroleum having an API gravity above about 35* to said oil-contaminated water in the proportion of about 1 to 10 volumes of said high API gravity crude petroleum per volume of low API gravity oil in said contaminated water; introducing said oil-contaminated water and high API gravity crude petroleum mixture into a flotation chamber; dispersing finely divided gas bubbles into said oil-contaminated water and high API gravity crude petroleum mixture in said flotation chamber whereby oil is floated to the surface of said water; removing oil and/or particulate solid material from the surface of said water; and withdrawing water having a reduced oil content from said flotation chamber.

Claim 6

The process defined in claim 3 wherein said high API gravity crude petroleum is admixed with a portion of said water withdrawn from said flotation chamber, and said gas is admixed with said high API gravity crude petroleum and water mixture at an elevated pressure so as to dissolve said gas in said mixture, and wherein said mixture containing dissolved gas is recycled to said flotation chamber maintained at a lower pressure and admixed with said contaminated water therein whereby finely divided gas bubbles are formed.

Claim 7

The process defined in claim 3 wherein said flotation chamber is maintained at substantially atmospheric pressure.

Claim 8

The process defined in claim 3 wherein said gas is natural gas or air.

Claim 9

The prOcess defined in claim 3 wherein said finely divided gas bubbles are mechanically dispersed into said oil-contaminated water and high API gravity crude petroleum mixture.

Claim 10

The process defined in claim 3 wherein gas is admixed with said oil-contaminated water and high API gravity crude petroleum mixture at an elevated pressure so as to dissolve said gas in said oil-contaminated water and high API gravity crude petroleum mixture, and wherein said mixture containing dissolved gas is introduced into said flotation chamber maintained at a lower pressure whereby finely divided gas bubbles are formed in said mixture.

Claim 11

The process defined in claim 7 wherein said mixture of oil-contaminated water and said high API gravity crude petroleum is passed through a plurality of successive contacting zones in said flotation chamber and wherein said mixture is contacted with finely divided gas bubbles in each of said contacting zones.

Claim 12

The process defined in claim 8 wherein said high API gravity crude petroleum is added to only a portion of said oil-contaminated water and wherein gas is dissolved in said mixture of high API gravity crude petroleum and said portion of said oil-contaminated water and wherein said portion containing dissolved gas and a gas-free portion of said oil-contaminated water are admixed in said flotation chamber.

Claim 13

A process for removing low API gravity oil from oil-contaminated water, which comprises: adding crude petroleum having an API gravity above about 35* to said oil-contaminated water in the proportion of about 2 to 5 volumes of said crude petroleum per volume of low gravity oil in said contaminated water; introducing said oil-contaminated water and crude petroleum mixture into a closed flotation chamber blanketed with natural gas maintained at a pressure slightly above atmospheric pressure; passing said oil-contaminated water and crude petroleum mixture through a plurality of successive contacting zones in said flotation chamber; dispersing finely divided bubbles of natural gas into said oil-contaminated water and crude petroleum mixture in each of said contacting zones whereby oil and/or particulate solid material is floated to the surface of said water; removing oil and/or particulate solid material from the surface of said water; and withdrawing a clarified effluent water of reduced oil content from the last of said contacting zones.

Claim 14

A process for removing low API gravity oil from oil-contaminated water, which comprises: adding crude petroleum having an API gravity above about 35* to said oil-contaminated water in the proportion of about 2 to 5 volumes of said crude petroleum per volume of low gravity oil in said contaminated water; introducing said oil-contaminated water and crude petroleum mixture into a closed flotation chamber blanketed with natural gas maintained at a pressure slightly above atmospheric pressure; passing said oil-contaminated water and crude petroleum mixture through a plurality of successive contacting zones in said flotation chamber; dispersing finely divided bubbles of natural gas into said oil-contaminated water and crude petroleum mixture in each of said contacting zones whereby oil and/or particulate solid material is floated to the surface of said water; removing oil and/or particulate solid material from the surface of said water; and withdrawing a clarified effluent water of reduced oil content from the last of said contacting zones.