Method and apparatus for separating oil and water

Oil and water separation apparatus comprising a reaction chamber having an inlet through which a mixture of oil and water may be introduced. A reaction that extends upwardly from an intake opening therein located in the reaction chamber and out of the chamber. The apparatus also has an ozone generator and a conduit through which ozone may be channeled from the ozone generator into the upwardly extending reaction tube. A pump is provided for pumping water and oil upwardly through the reaction tube entrained with ozone and out of the reaction chamber. A filter is provided for oil oxidized to particulate form by the ozone.

TECHNICAL FIELD 
This invention relates generally to methods and apparatuses for separating 
oil and water, and particularly to methods and apparatuses for separating 
the oil and water discharge condensate from compressed air systems. 
BACKGROUND OF THE INVENTION 
Mixtures of oil and water are usually separated by utilizing their 
differences in specific gravity, advantageously. Since most oils have a 
specific gravity substantially less than that of water, with time they 
separate and stratify into a surface layer of oil upon an underlying body 
of water. Once this occurs the oil may be skimmed off the water. By 
sequentially treating the residual water in this manner, the oil content 
of the mixture becomes less and less. 
Oil-water separators are used in treating the condensate of compressed air 
systems. As air is compressed in oil lubricated compressors, part of the 
lubricating oil becomes entrained in the water condensate discharge. This 
type of oil is finely dispersed. The specific gravity of some of these 
oils is quite high, even approaching that of water. Thus, even if the 
condensate is allowed to settle in holding tanks for hours, such does not 
guarantee separation by stratification alone. 
A commercially available oil-water separator used to separate the oil and 
water constituents of compressed air systems is the Ecosep series WT 
separator sold by Zander Filter Systems, Inc. of Norcross, Ga. It has a 
series of compartments through which oil and water is flowed in series 
with the liquid being drawn from a lower portion of each compartment and 
surface oil skimmed away. More specifically with the Zander unit the 
condensate from air compressors is reduced to atmospheric pressure and 
passed through a series of settling chambers by liquid displacement. Oil 
is drawn from the surface of the condensate in each chamber and residual 
water passed from the bottom of each chamber and then through an activated 
carbon filter which filters any remaining oil residue. 
Though the just described type of oil and water separators have performed 
effectively, their activated carbon filters have had to be monitored and 
replaced frequently. This has been attributable to the fact that some of 
the oils used in air compressor systems tend to remain emulsified and do 
not rise to the surface of the liquid in the settling chambers. Similarly, 
other oils with specific gravity approaching that of water rise so slowly 
that they remain dispersed in the water that is displaced from chamber to 
chamber. 
The just described problem could perhaps be solved with the use of fibrous 
membrane filters. However, oil and water separators that employ these are 
structurally complex and very expensive. 
Accordingly, it is seen that a need remains for an oil and water separator 
and separation process that can be used and maintained in a more cost 
effective manner, and which is particularly well suited for use in 
processing the condensate from compressed air systems. It is to the 
provision of such therefore that the present invention is primarily 
directed. 
SUMMARY OF THE INVENTION 
In a preferred form of the invention an oil and water separation apparatus 
comprises a settling chamber into which a mixture of oil and water may be 
introduced. The settling chamber have a drain at a selected elevation 
through which surface oil may be drained and a scavenger tube in a lower 
portion thereof. The apparatus also has a reaction chamber having an inlet 
in its upper portion coupled with the settling chamber scavenger tube. 
Means are provided for introducing ozone into the reaction tube for 
reaction with residual oil unseparated from the water in the settling 
chamber. 
In another preferred form of the invention oil and water separation 
apparatus comprises a reaction chamber having an inlet through which a 
mixture of oil and water may be introduced and separated. A reaction tube 
extends upwardly from an intake opening therein located in the reaction 
chamber and out of the chamber. An ozone generator is provided and a 
conduit through which ozone may be channeled from the ozone generator into 
the upwardly extending reaction tube. Pump means are included for pumping 
water and oil remaining unseparated in the separation chamber from the 
reaction chamber upwardly through the reaction tube entrained with ozone. 
In yet another form of the invention a method of separating oil and water 
from a mixture thereof comprises the steps of introducing the mixture into 
a settling chamber, removing oil from the surface of the mixture in the 
settling chamber, removing water and residual oil from a lower portion of 
the settling chamber, and reacting the water and residual oil with ozone.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference now in more detail to the drawings, there is shown an 
oil-water separator comprising a settling chamber 10, a reaction chamber 
11, a particulate filter 12 and an activated carbon filter 13 as four 
structurally discrete units. The settling chamber 10 has a condensate 
intake tubular connector 15 that extends into a collector tube 16 that has 
a set of side holes and an unshown bottom hole. The collector tube is 
mounted above a collection plate 17 that has a drain hole 18, and below a 
bed of activated carbon 20. The bed 20 is supported upon a screen beneath 
a chamber lid 21 that has a number of small holes therethrough so that the 
air pressure within the settling chamber is essentially that of ambient 
air pressure. 
The settling chamber 10 also has a funnel 23 mounted beneath drain hole 18, 
and a generally U-shaped feed tube 24 that depends from the funnel. A 
drain tube 25 is mounted above the outlet end of the feed tube 24. A 
scavenger tube 26, having four angularly spaced sets of holes, is mounted 
adjacent the bottom of the settling chamber 10 from which a conduit 27 
extends out of the chamber to a top portion of the reaction chamber 11. 
The reaction chamber 11 has a submersible, centrifugal pump 30 mounted on 
its bottom floor about which a suction screen 31 projects and from which a 
reaction tube 32 upwardly extends. The reaction tube includes a venturi 
tube 33 from which an ozone supply tube 34 extends to an ozone generator 
35 such as that sold by Ozone Pure Water, Inc., Sarasota, Fla., which is 
mounted to the outside wall of the reaction chamber. The reaction tube 32 
also has a recirculation T joint 37 located above the venturi tube 33. 
The reaction chamber further has pump control means for turning on the pump 
when the level of liquid therein approaches the top of the chamber and for 
turning it off when the level approaches the bottom of the chamber. This 
control means includes a slide rod 40 mounted uprightly to the inside wall 
of the chamber on which an upper switch contact 41 and a lower switch 
contact 42 are rigidly mounted. A switch actuator float 43 is slidable 
mounted on the slide rod between the two switch contacts. The two switch 
contacts are in a conventional circuit that couples the pump 30 and the 
outlet control valve of the ozone generator 35 with a source of electrical 
power. 
The reaction tube 32 extends out of the reaction chamber to the particular 
filter 12. The filter 12 is in turn placed in fluid communication with the 
activated carbon filter 13 by means of a conduit 46. The activated carbon 
filter 13 has a bed of activated carbon 48 supported upon a screen 49 
above a drain tube 50. 
In operation, pressurized condensate from a compressed air system is 
introduced into collector tube 16 of the settling chamber. Here, its 
pressure is reduced to atmospheric pressure with the activated carbon 20 
preventing condensate from escaping the apparatus to ambience through the 
holes of the lid 21. The condensate drains from the collection tube onto 
the collection plate 17 and then through its drain hole 18 into the funnel 
23 and feed tube 24. Due to the U-shape configuration of tube 24, the 
condensate is introduced into the main body of the settling chamber in an 
upward direction of flow. As the specific gravities of the oils are less 
than that of water, this direction of entry aids in allowing the oils to 
raise rapidly to the surface which is shown darkened to indicate a 
concentrated layer of oil. When the surface of the oil is above the inlet 
end of the drain tube 25, the oil is drawn from the apparatus. 
Flow through the structurally discrete units of the oil-water separator is 
accomplished by liquid displacement. As a quantity of condensate enters a 
unit an equivalent quantity is discharged, usually in a non-continuous, 
batch-like manner. Within the settling chamber 10 a majority of the oil is 
separated from the water. The cleaner condensate located at the bottom of 
the chamber is drawn into the scavenger tube 26 and fed to the reaction 
chamber 11. 
Residual oil remaining either mixed with the water or emulsified in it 
within the reaction tube is now removed by reaction with ozone. In 
response to the level of liquid within the reaction chamber being 
sufficiently high to switch on the pump 30 and valve open the ozone 
generator 35, liquid is pumped upwardly through the reaction tube 32. This 
causes ozone to be drawn into this flow by the venturi action of the 
venturi tube 33. Once entrained in this upward flow the ozone oxidizes its 
oil content causing such to precipitate and to assume the form of solid or 
semi-solid particulates. The water and particulates are then pumped out of 
the reaction chamber and into the particulate filter 12. As this occurs 
some of the ozone and liquid is recirculated back into the main body of 
the reaction chamber through the T-joint 37 where the ozone can also react 
with the oil content. 
With the residual oils now oxidized and precipitated out of solution and 
into particulate form, the particulate filter filters the particulates 
from the stream. The effluent from the filter is then directed onto the 
bed of activated carbon where final purification of the water occurs prior 
to discharge from the apparatus through drain tube 50. 
With the just described method and apparatus a more efficient cost 
effective separation of oil and water may be accomplished. With the 
heavier oils and emulsified oils converted to particulate form, they are 
substantially removed by the particulate filter rather than by the 
activated carbon. In this manner the life of the activated carbon is 
greatly enhanced since its pores do not become clogged with oil. This 
leaves it free to remove trace impurities and for the particulate filter 
the task of filtering the oxidized oil precipitates and other impurities. 
That the apparatus has structurally discrete units also facilitates system 
monitoring and servicing. 
It should be understood that the foregoing describes only the preferred 
embodiment of the present invention being used to treat the condensate of 
compressed oil system. The invention however is not limited to this 
particulate application. Numerous changes and modifications to the 
apparatus itself may be made without departing from the spirit and scope 
of the invention as set forth in the following claims.