Liquid separator

A separator device to separate a mixture of immiscible liquids of different densities wherein one of said liquids is in a discontinuous phase. The separator device includes a container having an inlet for the mixture of immiscible liquids and an outlet for removing one of the liquids after separation. A drain is provided to remove the discontinuous phase liquid after separation. Randomly arranged, loosely packed, coalescing medium within the container encourages coalescence and agglomeration of the discontinuous phase liquid.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention is directed to a gravity type liquid separator to 
separate a mixture of liquids of different densities. In particular, the 
present invention is directed to a gravity type liquid separator having a 
coalescing medium within the separator container. 
2. Prior Art 
The use of gravity type liquid separators to separate a mixture of liquids 
of different densities is longstanding. 
An important use of these liquid separators is in treatment of waste water 
discharge. Increasingly, governmental regulations specify the maximum 
amount of hydrocarbons that may be present in waste water discharge. The 
acceptable amount might typically be 10-15 parts per million (PPM). Other 
uses include removal of animal fat from water in food processing 
applications and removal of chemicals from water in industrial 
applications. 
In the simplest separators, an open tank or holding area is utilized. An 
example would be an oil/water separator where oil is floated to the 
surface of the tank. The lighter than water oil globules rise through the 
liquid mixture. The free oil is then skimmed off. 
Other separator designs include plates which are incorporated within the 
container or tank. It is known that separation of liquids is enhanced by 
using a coalescing process. One example is seen in Schmit et al. (U.S. 
Pat. No. 4,802,978) which provides a forced flow type oil/water separator 
utilizing arranged parallel plates with corrugated surfaces. Castelli 
(U.S. Pat. No. 4,897,206) discloses corrugated separator plates having 
corrugations running in orthogonal directions. Bleed holes are provided in 
both the crests and the valleys of the plates. 
A further separator design incorporates two stages. As an example, Aymong 
(U.S. Pat. No. 4,722,800) discloses a separator having two chambers, a 
small inlet chamber having a baffle to reduce and deflect inlet 
turbulence, and a relatively large separator chamber. 
All of the prior art separators which include a coalescing medium include 
structured plates or other medium which have a fixed structure and form. 
Accordingly, it is a principal object and purpose of the present invention 
to provide a liquid separator having a random packing coalescing medium. 
It is a further object and purpose of the present invention to provide a 
liquid separator having a coalescing medium that is loosely packed and not 
fastened to the tank or container. 
It is an additional object and purpose of the present invention to provide 
a coalescing medium within a separator having the maximum amount of 
surface area within a unit of volume. 
It is a further object and purpose to provide a liquid separator having a 
coalescing medium that is buoyant in water to facilitate cleaning by 
flushing the separator with clear water. 
SUMMARY OF THE INVENTION 
A gravity-type liquid separator of the present invention is suitable for 
separation of immiscible liquids having different specific gravities 
wherein one of the liquids is discontinuous and made up of discrete 
droplets. 
The separator may include a stand having legs in an arcuate cradle. A 
substantially cylindrical container sits within the cradle oriented with a 
horizontal axis. Straps secure the tank to the stand. 
The influent mixture of the immiscible liquids to be separate will enter 
the separator through an inlet pipe. The inlet pipe passes through an 
opening in the container and terminates in an open end within the tank. 
The flow of the influent mixture as it exits the end of the inlet pipe is 
directed toward on end of the tank. The ends of the tank have interior 
convex surfaces which serve to dissipate the kinetic energy of the 
influent mixture moving into the tank and to direct the flow in a reverse, 
horizontal direction. 
Cleaning drains may be located near the base of the tank and are normally 
in the closed position. When it is necessary to empty the tank or flush 
out accumulated solids, the drain valves may be opened. 
An outlet pipe commences within the tank at an open end near the base and 
passes through an opening in the tank. The outlet pipe terminates in an 
outlet nozzle. In an oil/water separator the outlet pipe would be used to 
remove the purified water. 
A drain pipe has an open end near the upper end of the tank and passes 
downward through an opening in the tank. The drain pipe terminates in a 
valve outside of the tank. The separated oil would be removed through the 
drain pipe. 
An air vent extends upward from the top of the tank and terminates in a 
tube having an open end. 
The interior of the tank is filled with a coalescing medium which is 
randomly packed or distributed within the tank. The coalescing medium 
rests loosely within the tank and is not fixed or fastened to the tank. 
In the present embodiment, the coalescing medium consists of a series of 
rings. Each ring is cylindrical in shape and has an open top and an open 
bottom. The circumferential surface of each ring contains a plurality of 
slots. Additionally, across the diameter of the rings, a series of ribs 
extend. The rings are either covered with or composed of polyproplyene, 
which is known to enhance the coalescing process. 
The coalescing medium in the form of rings is prevented from entering the 
pipes within the tank. An inlet screen surrounds the end of the inlet 
pipe. An outlet screen surrounds the open end of the outlet pipe. 
Additionally, a drain screen surrounds the open end of the drain pipe. 
The coalescing medium enhances the operation of the separator. Initially 
the difference in the specific gravity of the water and the oil causes the 
oil droplets to rise. Small oil droplets (generally smaller than 15 
microns) combine into larger droplets about the coalescing medium. The use 
of the randomly packed, unfastened and unstructured packing medium has 
been found to provide an optimum amount of horizontal surface area for 
unit volume.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to the drawings in detail, FIG. 1 illustrates an end view of a 
gravity-type liquid separator 10 constructed in accordance with the 
present invention. The separator is suited for separation of various 
immiscible liquids having different specific gravities wherein one liquid 
is discontinuous and made up of discrete droplets. The separator is 
particularly suited for use as an oil/water separator wherein a 
discontinuous oil phase is separated from a continuous water phase. 
The liquid separator may include a stand 14 having legs 16 and an arcuate 
cradle 18. It will be understood that other supporting framework might be 
utilized. 
Within the cradle 18 is a substantially cylindrical container or tank 20. 
The tank 20 has its axis in a horizontal orientation. The tank 20 may be 
constructed of polyethylene or other non-metallic or metallic materials. 
The tank 20 ideally will be suited for containment of liquids which may be 
found in the hazardous waste field. 
FIG. 2 is a sectional view of the separator 10 taken along section line 
2--2. Straps 21 secure the tank 20 to the stand 14. 
The influent mixture of immiscible liquids to be separated will enter the 
separator 10 through an inlet pipe 22 having an inlet nozzle 24. The 
arrows 26 indicate the direction of flow of the influent mixture into the 
tank 10. 
The inlet pipe 22 passes through a opening 28 in the container 20 and 
terminates in an open end 30 within the tank. 
As best seen in FIG. 2, the tank 20 will be fluid packed during operation. 
For clarity, the accumulated oil is illustrated by the dashed lines within 
the tank 20 wile the water in the tank is not shown. 
It is known that inlet turbulence has a negative effect on the efficiency 
of the separator. In the present invention, this is addressed by directing 
the flow of the influent mixture as it exits at the end 30 of the inlet 
pipe toward one end 32 of the tank. The ends 32 have interior convex 
surfaces which serve to dissipate the kinetic energy of the influent 
mixture moving into the tank and direct the flow in a reverse, horizontal 
direction as best shown by arrows 34. 
Cleaning drains 36 located near the base of the tank are normally in the 
closed position. In the event it is necessary to empty the tank or to 
flush out accumulated solids, the drain valves may be opened. The 
separator may be backwashed with water to dislodge and flush out solids. 
An outlet pipe 38 commences within the tank at an open end 37 near the 
base, and passes through an opening 40 in the tank. The outlet pipe 
terminates in an outlet nozzle 42. In an oil/water separator, the outlet 
pipe 38 would be used to remove the purified water. 
A drain pipe 44 has an open end 46 near the uppe end of the tank and passes 
through an opening 47 in the tank. Drain pipe terminates in a valve 48 
outside of the tank 20. The separated oil would be drained through drain 
pipe 44. A container (not shown) could be placed under the valve 48 of the 
drain pipe 44, so that the valve may be left open. Alternatively, the 
valve could be placed in the closed position and periodically drained of 
the separated oil. 
An air vent 50 extends upward from the top of the tank and terminates in a 
tube 52 having an open end. 
The interior of the tank 20 is filled with a coalescing medium 53 which is 
randomly packed or distributed within the tank. The coalescing medium 
rests loosely within the tank and is not fixed or fastened to the tank in 
any way. In one embodiment, the coalescing medium consists of a series of 
rings 54. Alternately, coalescing medium having different shapes might be 
employed. 
FIG. 3 is a simplified view of the interior of the tank 20 showing the 
rings 54. The separated oil is illustrated by the dashed lines 55. Each 
ring is cylindrical in shape and has an open top and an open bottom. The 
circumferential surface of each ring contains a plurality of slots 56. 
Additionally, across the diameter of the rings, a series of ribs 58 
extend. The rings in the present embodiment are either covered with or 
composed of polyproplyene, which is known to enhance the coalescing 
process. Rings 54 of different sizes might be utilized although rings of 
1" diameter are used in the present embodiment. 
Since the rings themselves are buoyant in water, cleaning is facilitated 
since the rings will be agitated if the separator is emptied and then 
backwashed with water. 
The coalescing medium enhances the operation of the separator in a number 
of ways. Initially, the difference in the specific gravity of the water 
and oil causes the oil droplets to rise. The coalescing medium of the 
present invention provides a substantial amount of horizontal surface area 
to intercept rising droplets. Small oil droplets (generally smaller than 
15 microns) combine into larger droplets 60. 
Additionally, the inertia of the droplets, either through inertial 
impaction, direct interception or coalescing from random directions, 
causes droplets to coalesce on the rings. 
It is known that the removal of oil droplets by droplet rise onto a 
horizontal surface is a major factor in overall oil removal. Accordingly, 
the amount of horizontal surface area per unit volume is a critical 
factor. It will also be recognized that only the horizontal surface facing 
downward is effective for upward impingement of oil droplets. In one 
example, the use of the random packed coalescing medium provides over 25 
square feet of downwardly facing horizontal surface area per cubic feet of 
media. 
Returning to a consideration of FIG. 2, the coalescing medium in the form 
of rings 54 is prevented from entering pipes within the tank. An inlet 
screen 66 surrounds the end 30 of the inlet pipe 22. Outlet screen 68 
surrounds the open end 37 of the outlet pipe 38. Drain screen 70 surrounds 
the open end 46 of the drain pipe. In operation, the separator tank 20 is 
filled with clean water upon installation. The influent mixture of 
immiscible liquids is delivered to the separator through inlet nozzle 24 
and inlet pipe 22 If the level of the inlet nozzle 24 is installed below 
the level of the source of the influent mixture, the separator will be 
gravity fed. Alternately, the influent mixture may be pumped to the 
separator 10. 
An inlet mixture containing up to 10,000 parts per million (PPM) of oil is 
easily handled. The difference in the specific gravity of the liquids to 
be separated should be at least 0.05. Accordingly, oils having specific 
gravity of up to 0.95 will be easily separated from water. 
The size of the tank 20 will be a matter of choice although larger tanks 
can be used at lower flow rates for more emulsified or heavy oils while 
smaller ones can be used at higher flow rates. 
Once inside of the tank 20, the majority of solids in the mixture will 
rapidly settle to the bottom of the tank. The kinetic energy of the 
influent mixture is partially dissipated by being directed against the 
convex interior of the end of the tank. The direction of the mixture will 
then move horizontally toward the outlet pipe. The oil droplets will rise 
and impinge upon the horizontal surface of the coalescing medium. The 
upper portion of the tank serves as an oil holding reservoir. 
Purified water flows up the outlet pipe 38 and out of the outlet nozzle 42. 
If the inlet nozzle is below the level of the influent source, the 
separator will be gravity fed. 
Whereas, the present invention has been described in relation to the 
drawings attached hereto, it should be understood that other and further 
modifications, apart from those shown or suggested herein, may be made 
within the spirit and scope of this invention.