WO1994005602A1

WO1994005602A1 - Liquid to liquid coalescing separator and method

Info

Publication number: WO1994005602A1
Application number: PCT/US1993/008087
Authority: WO
Inventors: Hadi Elmi
Original assignee: Modern Welding Co Inc
Current assignee: Modern Welding Co Inc
Priority date: 1992-08-27
Filing date: 1993-08-27
Publication date: 1994-03-17
Anticipated expiration: 1995-02-27

Abstract

Disclosed is a liquid to liquid coalescing separator (10) in which the liquid flows through sides of upright perforated tubes (20). One of the liquids coalesces on the inner walls of the tubes until large enough to break away and flow out of internal passages in the tubes, and the other liquid free of coalesced liquid flows through the tubes and to an outlet (22).

Description

Liquid to Liquid Coalescing Separator and Method

Field of the Invention This invention is in the field of liquid to liquid coalescing separation. Background of the Invention

Coalescers are employed for separation of liquid to liquid suspension. Examples include the coalescing of water out of petroleum based products or the coalescing of petroleum based products out of water. Coalescers can be used for separating a variety of liquids from liquids, such as removing suspended hydrocarbon or oils from water, such as from tank farms, petroleum marketing facilities, refineries, utilities, gasoline stations, vehicle repair an maintenance shops, petrochemical plants, truck stops, parking lots, steel mills, storm water run off, surface run off, street wash waters, and the like. Various state and federal acts and regulations prohibit the discharge of any pollutants to United States navigable waters, pollution fro natural storm water run off as well as illicit disposal in the storm sewers. Under current storm water regulations, drainage systems must be capable of removing contaminants, such as the petroleum hydrocarbons, from storm water run of at least down to 15 parts per million concentrations, which includes the removal of all free petroleum droplets equal t or greater than 20 microns in size.

Conventional methods of separating liquid droplet entrained in liquids, such as oil in water, include gravity separation, filtration, absorption, cohesion disposition, air floatation, microbiological, electrolytic, physical, chemical, and coalescing methods. The following patents are illustrative of the state of the art developed in a preliminary search.

U.S. Patent No. 2,651,414 illustrates a hydrocarbon separator apparatus which utilizes a cylindrical wall freely perforated or of expanded metal permitting relative free flow of liquid through it for separation.

U.S. Patent No. 3,830,371 illustrates a liquid to liquid separator by passing through confined particle material which has an affinity for one of the liquids. U.S. Patent No. 4,231,867 discloses a method and appartaus for separating heterogenous fluids by flowing a gas through a liquid phase in a plurality of substantially vertical conduit members over a manifold member through which the gas is supplied, the gas carrying the liquid bubbles to the surface and circulating downwardly on the outside of the tubes.

U.S. Patent No. 4,299,699 illustrates a back washable helical-media coalescer, the coalescer media composed of yarn-like material. U.S. Patent No. 4,479,875 illustrates an inlet distributor for a liquid-liquid separator including a distributor mounted within the separation zone provided with fluid openings having packing means disposed thereabout. U.S. Patent No. 4,919,777 discloses an electrostatic mechanical emulsion treating method and apparatus which includes an electrically grounded coalescing element comprising a multiplicity of longitudinally- extending downwardly inclined open ended tubes arranged in bundle fashion. U.S. Patent No. 5,028,323 discloses a filter for corrosive liquids which includes filter tubes formed from commercially available plastic tubes having multiple openings to provide for liquid passing between the inner and outer areas of the tubes. U.S. Patent No. 4,591,441 discloses a method and an apparatus for separating oil from water in which an oil water separating element consisting of specific porous material is used which includes a water insoluble hydrogel layer formed on the porous material surface and/or the surface of a fluid passage to be contacted with oil holding water.

U.S. Patents 4,359,329 and 4,722,800 disclose separators provided with deflecting baffles and manways to provide access to the separator tank.

Commercial coalescers available on the market utilize mesh and plates to cause lighter oils to rise and coalesce into larger droplets which collect on the mesh or plates until they are large enough to break away and rise to the surface.

None of the foregoing patents or liquid to liquid coalescers available at present disclose, suggest, or use a liquid to liquid separator utilizing one or more upright or vertical coalescer tube assemblies of oleophilic, fiberglass composite or metallic materials having its side walls perforated so that the liquid flows into the tubes, small droplets of liquid coalesce on the inner walls of the tubes and increase in size until they break away thereby increasing the rate of rise of the droplets within the tubes, and liquid free of the coalesced droplets flows out of the tubes by which highly advantageous results are obtained.

Summary of the Invention

The present invention is directed to apparatus an methods for separating first liquid droplets in second liquids, such as oil droplets from water, utilizing at leas one coalescer assembly comprised of one or more tubes of geometric cross section having inner and outer walls and a passage therein and having perforations extending through the inner and outer walls of the tubes substantially along their lengths, the tubes being secured together in side by side relationship and formed of an oleophilic, fiberglass composite or metallic materials. The second liquid containing the first liquid droplets flows through the perforations in the outer wall into the internal passage, and coalesce on the inner wall until they are large enough to break away and flow upwardly in the interior passage thereby separating the first liquid droplets from the second liquid, such as oil droplets in water. The second liquid free of the coalesced liquid droplets flows through the perforations on the downstream side of the tube or tubes an out the bottoms of the tubes. Separate outlets in the separator are provided for removal of the second liquid fre of the coalesced droplets and for removal of the coalesced droplets.

The influent inlet of the separator has a discharge end angled to distribute the influent evenly over a 315° to 345°, and probably a 325° arc to provide even flo distribution through the coalescer tube assembly. In addition, sludge baffles, manholes for cleaning the tank, making repairs, replacements, and the like are provided. The liquid to liquid coalescing separator may be undergroun or above ground, horizontal or vertical, as desired.

The coalescer separation is based on Stokes Law, and advantageously the separator can be built in accordance with American Petroleum Institute (API) manual entitled Disposal of Refinery Waste, Chapter 6. Accordingly, it is an object of the present invention to provide an apparatus for separating liquid droplets from liquid by flowing through perforations in upstream side walls of one or more tubes of a material having an affinity for the liquid droplets, such as oleophilic, fiberglass composite, or metal materials depending on use, having inner passages therein, the liquid droplets to be separated coalescing on inner walls of the tubes until large enough to break away from the inner walls and flow in the inner passages out of the tubes, the liquid free of the coalesced liquid droplets flowing out of the inner passage through the perforations in downstream side walls and bottoms of the tubes thereby separating the two liquids.

A further object of the present invention is the provision of a liquid to liquid coalescing separator comprising a closed separator housing, inlet and outlet means in the housing for flow of the liquid-liquid into the closed housing and to discharge each of the liquids separately from the housing, and having at least one coalescer assembly disposed in the flow path in the housing between the inlet and outlet meanε, the coalescer assembly comprising at leaεt one or more upright perforated tubes of geometric cross section having an axial passageway therein formed of a material having an affinity for the liquid to be coalesced, one of the liquids coalescing in droplets on the inner walls of the perforated tubes which increase in size until the droplets are large enough to break away and rise within the passage, and the other of the liquids free of the coalesced liquid droplets flowing through the perforations in downstream walls of the perforated tubes and out their bottoms thereby separating the liquids.

A further object of the present invention iε to provide an improved coalescer assembly formed of one or more upright perforated tubes of geometric cross section having an internal passage formed of a material having an affinity for the liquid to be coalesced, such of oleophilics, fiberglass composite and water material, liquid flowing into the passage through the upstream side of the wall of the tubes, droplets coalescing on inner walls of the tubes which increase in size until they are large enough to break away from the inner walls and rise to the surface, and liquid free of the coalesced droplets flowing out of the perforations in the downstream wall of the tubes.

It is a further object of the present invention to provide a coalescing liquid-liquid separation which is economical, effective, and which obtains improved results over the prior art. It is a further object of the invention to provide such a liquid to liquid coalescing separator operated by gravity flow.

Other features and advantages of the present invention appear throughout the specification and claims. Brief Description of the Drawings

Figure 1 is a side view, in section, illustrating a liquid in liquid coalescing separator according to the invention. Figure 2 is a perεpective view of a coalescer assembly according to the invention utilized in the separator of Figure 1.

Figure 3 is a top view of the coalescer assembly of Figure 2. Figure 4 is a side view of the tubular coalescer tubes illustrated in Figureε 2 and 3. Description of Preferred Embodiments

Referring now to Figure 1, a separator 10 is shown as located beneath the surface of the ground 12. The separator 10 comprises a closed housing 14, here shown as a horizontal cylindrical tank, having an influent inlet 16 whose outlet end is angled toward the inlet end of the closed housing 14 to distribute the influent evenly over a 315° to 345°, and preferably a 325° arc at the inlet side of the separator 10. This flow pattern enhances solids settlement and even flow distribution through one or more coalescer tube aεsemblies 20, here shown aε a pair of spaced coalescer tube aεsemblies 20, dispoεed in the path or flow of the influent in the closed housing 14. Any number or arrangement of coalescer tube asεemblies 20 can be utilized to meet the conditions of use.

An outlet 22 iε provided adjacent the diεcharge end of the tank 14 to diεcharge liquid free of coaleεced droplets, such aε oil droplets εeparated from waεtewater. A εludge baffle 24 iε dispoεed adjacent the bottom of the tank 14 between the coaleεcer 20 and the outlet 22. As indicated in the drawing, an outlet 26 for petroleum product, such as oil, removal from the closed housing 14 is provided and a conduit 28 for an oil level control, not shown, is also provided. A closed manhole 30 is provided for entry into the tank for cleaning, making repairs and replacements, and the like.

Referring now to Figure 2, the coalescer assembly 20 is illustrated which includes a plurality of tubes 32 of desired geometric cross section, here illustrated as tubular. The walls 34 of the tubes 32 have the perforations 36 spaced along their lengths and have internal passages 38 extending axially in the tubes 32 for flow of upstream influent through the perforation 36 into the interior passages 38. Droplets of one of the liquids coalesce on the inner walls 40 of the tubes 32 where the coalesced droplets increase in size until the droplets are large enough to break away from the inner walls 38 and rise by gravity to the surface in the passages 38 within the perforated tubes 32. The influent free of the coalesced droplets flowε out of the perforations 36 on the downstream side of a tube 20 into the next tube where the coalescing as described is repeated, and so on until it flows out of the coalescer assembly 20, the first liquid in the second liquid, such as oil droplets in water, have coalesced and flow to the surface and the second liquid, such as water free of the coalesced droplets, flows out of the coalescer assembly 20. The liquid free of coalesced oil droplets, such as water, flows out the outlet 22, and the εeparated oil is removed from the tank 10 in the outlet 26. The tubes may be of any desired cross sectional configuration, but preferably are of round cross section. Preferably, the coalescer tube asεembly 20 provideε a service area equivalent to one square foot per one gallon per minute of flow. For efficient results, the openings in the tubes 32 can range from 1/4" to about 3/4", preferably 1/2", and the diameter of the tubes can range from 1" to 4", preferably 2".

The tubes 32 are contained in an open sided and open top and bottom container 42 which haε an expanded metal plate in the top and bottom 44 εo that the liquid in liquid influent can flow through the coalescer assembly 20, the coaleεced droplets can flow out the tops of the tubes 32, and the liquid free of the coalesced dropletε can flow through the downεtream sides of the tubes 32, and the solids can flow through the bottoms of tubes 32 of the coalescer asεembly 20.

The material of which the tubeε 32 can be formed includeε any material which attractε or has an affinity for the droplets to be coaleεced and can withstand the conditions of use. For example, for droplets of hydrocarbon or petroleum based products, an oleophilic material is used such as polyethylene or polypropylene for ambient temperatureε up to about 150°F. For temperature above 150°F, preferably metal material iε uεed. For corroεive liquidε, fiberglass composite can be used.

If desired, to enhance coaleεcing within the vertical tubeε 20, materialε, not εhown, such as polyethylene and/or polypropylene may be added. Thiε increases the surface area within the tube asεembly and therefore increaεeε the efficiency of coaleεcing.

The polyethylene and/or polypropylene materialε may conεiεt of ε all diameter hollow tubeε with internal configurations and known in the industry as pall rings, or may conεiεt of a meεh type material of varying coarseness, which may be packed within the coalescer tubes 20.

The method of the invention for separating first liquid dropletε in a second liquid, such as oil in water, compriεeε flowing them through perforations in upstream side walls of one or more tubes having inner passages therein, and formed of a material which attracts or on which the first liquid dropletε coaleεce, the firεt liquid dropletε coaleεcing on inner wallε of the tubeε 32 until they are large enough to break away from the inner wallε and flow in the inner paεεageε out of the tubeε thereby separating the first liquid droplets from the second liquid, the second liquid free of the coalesced first liquid droplets flowing out of the inner passage through the perforationε in the downstream side of the walls of the tubes and their bottoms. Aε in the apparatuε of the invention, the tubeε are formed of a material attracting the dropletε or on which they coaleεce, and in the caεe of droplets of hydrocarbon based products in water, they are formed of polyethylene or polypropylene.

One or more coaleεcing unitε 20 may be employed, if necessary or desired. Also, level control devices for controlling the level of liquid in the separator 10 may be provided for automatic oil removal, and means for sludge draw off such as a pump may also be provided for withdrawing sludge from the bottom of the closed container 14. Emulsified liquid can be treated by utilizing an emulεion treatment, such as by lowering the pH of the liquid, heating the liquid, filtration or chemical addition, and the like prior to flow through the coalescer asεembly 20. All of the foregoing are readily available on the open market, and no detailed description is given thereof or deemed necessary. Advantageously, the separator can operate on a gravity principle and be located underground, aε previously set forth.

Coalescer liquid-liquid εeparators according to the invention can be deεigned for a wide variety of uεeε and capacitieε. For example, for εeparation of oil dropletε from water, coaleεcing εeparatorε according to the invention can be deεigned for capacitieε based on an influent of freεh water with a maximum free oil concentration of 200,000 mg/1 with a εpecific gravity of 0.75-0.95 at a minimum temperature of 40°F, and for a minimum oil capacity equivalent to about 50 percent of the total tank volume. The total volume can range from 560 to 50,000 gallons having up to 50 percent hydrocarbon based waεtewater, εubεoil, capacity or 230 to 25,000 gallonε at flow rates from 50 to 2,000 gallonε per minute. The preεent invention therefore iε well adapted and suited to attain the objects and ends and has the advantageε and features mentioned as well aε otherε inherent therein.

While presently preferred embodiments of the invention have been given for the purpose of disclosure, modifications may be made therein which are within the spirit invention as defined by the appended claimε. What iε claimed iε:

Claims

Claimε

1. Apparatuε for εeparating firεt liquid dropletε in a second liquid comprising, a closed housing, inlet and outlet means in the housing for flow of the second liquid containing the first liquid droplets into the closed housing and flow of the second liquid substantially free of the first coalesced liquid droplets out the outlet means, one or more coalescer assemblies disposed in the housing between the inlet and the outlet means, the coalescer assembly comprising one or more upright, open ended, perforated tubes of geometric crosε section having internal pasεageε therein formed of a material on which the first liquid droplets will coalesce positioned in the flow of the second liquid containing the first liquid droplets effective for flow thereof through the perforations, the first liquid dropletε coaleεcing on inner walls of the perforated tubes and increaεing in εize until the droplets are large enough to break away from the inner wallε and riεe to the surface in the internal passages in the perforated tubes, and means for removing the coalesced liquid droplets from the cloεed houεing.

2. The apparatuε of claim 1 where, the material from which the tubeε are formed iε εelected from the group consisting of oleophilic, fiberglasε compoεite and metal material.

3. The apparatuε of Claim 1 where, the material from which the tubes are made is selected from the group consisting of polyethylene and polypropylene.

4. The apparatuε of Claims 1, 2, or 3, including, means adjacent the bottom of the closed housing downstream of the one or more coalescer asεemblies effective to remove sludge from the second liquid.

5. The apparatus of Claimε 1, 2, 3, or 4, where, the inlet meanε includes means to distribute the flow of the second liquid containing the first liquid droplets in a 315° to 345° arc into the closed housing.

6. The apparatus of Claims 1, 2, 3, 4, or 5 where, the first liquid droplets compriεe oil and the second liquid comprise water.

7. A coalescer assembly for separating dropletε of a second liquid from a first liquid comprising, one or more tubes of geometric croεε section having inner and outer wallε, interior passageε therein, and having perforationε extending through the inner and outer wallε of the tubeε substantially along their lengths, the tubes secured together in side by side relationεhip, the tubeε formed of a material, upon which the εecond liquid droplets coalesce, whereby the first liquid containing the droplets of the εecond liquid flowε through the perforationε in the outer wallε and the dropletε coaleεce on the inner wallε until they are large enough to break away from the inner walls and flow in the interior paεsages in the tubes thereby separating the droplets from the firεt liquid, the first liquid free of the coalesced droplets flowing through the perforations out of the tubes.

8. The coalescer assembly of Claim 7 where, the material of the tubes is selected from the group consisting of oleophilic, fiberglass composite and metal material.

9. The coalescer assembly of Claim 8 where, the oleophilic material is selected from the group consisting of polyethylene and polypropylene.

10. The coalescer assembly of Claim 7 where, the outer wall's εurface of the tubes is equivalent to one square foot per one gallon of flow per minute of the first liquid containing the droplets through the perforations.

11. The coalescer assembly of Claims 7, 8, 9, or 10 where, the firεt liquid comprises water and the droplets compriεe petroleum baεed productε.

12. A method of εeparating firεt liquid dropletε in a second liquid therein compriεing, flowing the liquidε through perforations in upstream side walls of one or more tubeε having internal passageε therein and formed of a material on which the firεt liquid dropletε will coaleεce, the droplets coalescing on inner walls of the tubes until they are large enough to break away from the inner wallε and flow in the inner paεsages out of the tubes thereby separating the dropletε from the second liquid, the second liquid free of the coalesced droplets flowing out of the inner passage through the perforations in downstream side walls and bottoms of the tubes.

5 13. The method of Claim 12 where, the material of which the tubes are formed i selected from the group consisting of oleophilic, fiberglass composite and metal material.

14. The method of Claim 12 where,

10 the material of which the tubes are formed is selected from the group consisting of polyethylene and polypropylene.

15. The method of Claim 10 where, the first liquid droplets comprise petroleu 15 based products and the second liquid comprises water.

AMENDED CLAIMS

[received by the International Bureau on 4 January 1994 (04.01.94); original claim 4 cancelled; original claim 1 amended; claims 5-7, 10 and 12 amended renumbered as claims

4-5, 9 and 11; other claims unchanged but renumbered (5 pages)]

1. Apparatus for separating a coalescent liquid contained in a firεt liquid comprising, a closed housing, inlet and outlet means in the housing for flo of the coalescent and first liquids into the close housing in a flow path in the housing and flow of the first liquid free of coalesced droplets of the coalescent liquid out the outlet means, one or more coalescer assemblies disposed in the housing between the inlet and outlet means and in the flow path comprising one or more tubes of geometric cross section having perforated upstream and downstream sides to the flow path, internal passages therein throughout their lengths with ope tops and open bottoms formed of a material on whic the coalescent liquid will coalesce, the one or more tubes positioned in the flow path with the open bottoms spaced from the housing bottom and the open tops spaced from the housing's top, whereby the coalescent and first liquids flow through the upstream perforated sides of the tubes into the internal passages therein, the first coalescent liquid coalesces into the coalesced droplets on inner walls of the internal passages o the tubes increasing in εize until the coalesced dropletε are large enough to break away from the inner wallε and riεe by gravity in the internal passages out the open tops of the tubes, the secon liquid free of the coalesced droplets flows throug the downstream perforated εideε of the tubeε, εlud from the second liquid flows by gravity out the op bottom of the tubes, means for removing the coalesced droplets from the closed housing, and means for removing the εludge from the bottom of the houεing.

2. The apparatuε of claim 1 where, the material from which the tubes are formed is selected from the group consisting of oleophilic, fiberglasε composite and metal material.

3. The apparatuε of Claim 1 where, the material from which the tubeε are made is selected from the group consisting of polyethylene and polypropylene.

4. The apparatus of Claims 1, 2, or 3 where, the inlet means includes means to form the flow path of the second liquid containing the first liquid droplets in a 315° to 345° arc into the closed housing and then into the upstream perforated sides of the tubeε.

5. The apparatuε of Claimε 1, 2, 3, or 4 where, the coaleεcent liquid is selected from the group consisting of petroleum based products and the first liquid compriεes water.

6. A coalescer asεembly for separating a coalescent liquid from a first liquid comprising, one or more tubes of geometric cross section having inner and outer wallε, interior passageε having open topε and bottomε therein, and having perforationε extending through the upstream and downstream walls of the tubes εubεtantially along their lengthε, the tubes εecured together in εide εide relationεhip, the tubeε formed of a material, upon which th coalescent liquid coalesces, whereby the coalescent and first liquids flow through the perforations in the upstream walls int the interior passageε and coalesce into coalesced dropletε on inner wallε until they are large enoug to break away from the inner wallε and flow by gravity in the interior paεεageε and out the open tops of the tubes thereby separating the coaleεced dropletε from the firεt liquid, the firεt liquid free of the coalesced droplets flowing through the perforations in the downstream side out of the tubes, sludge from the εecond liquid flowing out t open bottoms.

7. The coalescer assembly of Claim 6 where, the material of the tubes is selected from th group consisting of oleophilic, fiberglass composi and metal material.

8. The coalescer assembly of Claim 7 where, the oleophilic material is εelected from the group conεisting of polyethylene and polypropylene

9. The coaleεcer aεεembly of Claim 6 where, the tubeε' outer wall'ε εurface iε equivalen to one εquare foot per one gallon of flow per minu of the first liquid containing the coalescent liqu through the perforationε.

10. The coalescer asεembly of Claimε 6, 7, 8, or where, the firεt liquid compriseε water and the coalescent liquid is selected from the group of petroleum baεed productε.

11. A method of separating a coalescent liquid in first liquid comprising, flowing the liquids through perforationε in upstream side walls of one or more tubes having internal paεsages with an open top and an open bottom formed of a material on which the coalescen liquid will coalesce in coalesced dropletε on inne walls of the tubes until they are large enough to break away from the inner walls and flow by gravit in the inner pasεageε out of the upper open endε o the tubeε thereby separating the coaleεced droplet from the firεt liquid, flowing the firεt liquid fr of the coaleεced dropletε out of the inner paεsage through the perforations in downstream side walls and bottoms of the tubeε, and flowing εludge from the first liquid out of the bottomε of the tubeε.

12. The method of Claim 11 where, the material of which the tubeε are formed iε selected from the group consiεting of oleophilic, fiberglaεε compoεite and metal material.

13. The method of Claim 11 where, the material of which the tubeε are formed i εelected from the group conεiεting of polyethylene and polypropylene.

14. The method of Claim 11 where, the coalescent liquid is selected from the group consiεting of petroleum based products and the first liquid comprises water.