WO2015187917A1

WO2015187917A1 - Packed polymer fibers for removal of water immiscible material

Info

Publication number: WO2015187917A1
Application number: PCT/US2015/034136
Authority: WO
Inventors: Philip A. BURCLAFF
Original assignee: Siemens Energy, Inc.
Priority date: 2014-06-04
Filing date: 2015-06-04
Publication date: 2015-12-10

Abstract

A system (10) is provided for removing a water immiscible material, such as emulsified oil, from an aqueous fluid (12) including the water immiscible material. The system (10) includes a vessel (18) having a bed (22) of randomly arranged polymer fibers (24) packed within the vessel (18) such that void spaces (26) remain between adjacent fibers (24) sufficient to collect water immiscible material from the fluid (12) within the void spaces (26) after the fibers (24) have initially been coated with water immiscible material.

Description

PACKED POLYMER FIBERS FOR REMOVAL OF WATER IMMISCIBLE

MATERIAL

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of the June 4, 2014 filing date of U.S. Provisional Application No. 62/007,495, which is incorporated by reference herein.

FIELD

The present disclosure relates generally to the treatment of fluids, and more particularly to systems and methods for separating a water immiscible material from an aqueous fluid comprising the water immiscible material.

BACKGROUND

By way of example, in the oil and gas industry, it is desirable to have solids and oils removed to varying degrees from produced water so that the water can be reused or released. Produced water generally refers to water that is produced as a byproduct in the recovery of oil and gas. The majority of the oil in such produced water is free oil, which is easy to remove with known systems. However, emulsified oil may also be present in the produced water, which is more difficult to remove. Emulsified oil consists of a dispersion of oil droplets in water. These emulsions must be treated to remove the dispersed oil and associated inorganic salts to meet specifications for transportation, storage, and export, and/or to reduce corrosion and catalyst poisoning in downstream processing facilities. Known solutions for removing emulsified oil include the addition of chemicals or the use of high pressure systems to break the emulsion, each of which may become costly, time consuming, and complex. In addition, known filtration systems for emulsified oil are typically non-regenerable and/or become increasingly costly as flow rates increase. Additionally, filters in known system can easily clog with solids, thereby creating issues with high pressure build up and subsequent flow reduction. SUMMARY

The present inventor has developed improved solutions for removing water immiscible material from an aqueous fluid comprising the water immiscible material. In accordance with one aspect, an apparatus, system, and method are provided herewith which include a vessel having a bed of randomly arranged polymer fibers packed therein such that void spaces remain between adjacent fibers sufficient to collect water immiscible material within the void spaces after the fibers have initially been coated with the water immiscible material. The large surface area and void spaces of the bed are effective to provide the vessel with a relatively large loading capacity for the water immiscible material, thereby dispensing the need to provide coalescing agents and added pressure to the vessel. While not wishing to be bound by theory, it is believed that the oleophilic properties of the polymeric fibers initially attract water immiscible material to a surface thereof. Once coated with water immiscible material, additional water immiscible material may be attracted to the coated fibers and may settle within the void spaces of the polymeric bed. In certain embodiments, this results in a separation process with excellent efficiency and which is capable of producing an effluent stream having less than about 1 .0 mg/L of water immiscible material therein. Due to the collection efficiency of the apparatus, systems, and methods described herein, aspects of the present invention may dispense with the need for coalescing steps and floatation processes of the prior art, particularly in the case of emulsified oil.

In accordance with one particular aspect, there is provided method for removing water immiscible material from an aqueous fluid comprising the water immiscible material. The method comprises contacting the aqueous fluid with a bed of free flowing polymer fibers packed such that void spaces remain between adjacent fibers sufficient to collect water immiscible material within the void spaces after the fibers have initially been coated with water immiscible material. In accordance with another aspect, there is provided a vessel for removing water immiscible material from an aqueous fluid comprising the water immiscible material. The vessel includes a feed inlet for receiving the aqueous fluid into the vessel. In addition, the vessel includes a bed of randomly arranged polymer fibers packed within each vessel such that void spaces remain between adjacent fibers sufficient to collect water immiscible material from the fluid within the void spaces after the fibers have initially been coated with water immiscible material. Further, the vessel includes an outlet for dispensing an effluent from the vessel having a reduced amount of water immiscible material therein relative to the fluid entering the feed inlet.

In accordance with still another aspect, there is provided a system for removing water immiscible material from aqueous fluid comprising the water immiscible material. The system comprises one or more vessels, wherein each vessel includes: a feed inlet for receiving the aqueous fluid comprising the water immiscible material into the vessel; a bed of randomly arranged polymer fibers packed within the vessel such that void spaces remain between adjacent fibers sufficient to collect water immiscible material from the fluid within the void spaces after the fibers have initially been coated with water immiscible material; and an outlet for dispensing an effluent from the vessel having a reduced amount of water immiscible material therein relative to the fluid entering the feed inlet.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in the following description in view of the drawings that show:

FIG. 1 is a schematic illustration of a separation system in accordance with an aspect of the present invention.

FIG. 2 is a schematic illustration of a separation system employing a regeneration circuit in accordance with an aspect of the present invention. FIG. 3 is a schematic illustration of a separation system employing the use of a solvent and a gas in accordance with an aspect of the present invention.

FIG. 4 is a schematic illustration of a separation system comprising more than one vessel in parallel in accordance with an aspect of the present invention.

FIG. 5 is a schematic illustration of a separation system further comprising an activated carbon station in accordance with an aspect of the present invention.

DETAILED DESCRIPTION

Referring now to the figures, there is shown in FIG. 1 a separation system 10 (system 10) for removing water immiscible material, e.g., emulsified oil, from an aqueous fluid 12 (fluid 12) comprising the water immiscible material. The system 10 comprises a source 14 of the fluid 12 and a removal circuit 16 comprising one or more vessels 18 (vessels 18) for treating the fluid 12. For ease of illustration, one vessel 18 is shown in FIG. 1 , although it is understood that the present invention is not so limited.

In an embodiment, each vessel 18 may comprise at least one feed inlet 20 (inlet 20) for receiving the fluid 12 into the vessel 18. In the embodiment shown, the feed inlet 20 is disposed at a bottom portion 21 of the vessel 18 such that the fluid 12 flows through the vessel 18 in a direction counter to the direction of gravity. This configuration may be useful when the vessel is regenerated with a solvent and/or backwash solution as will be described below. In particular, when the fluid 12 is fed into the bottom portion 21 , the fluid 12 may push remaining solvent (which is likely to be less dense than the fluid 12) from the regeneration out a top portion of the vessel 18 to allow for further filtration. Moreover, if a backwash solution is used in regeneration, feeding the fluid 12 into the bottom portion 21 may leave solids at the bottom portion, which may make them easier to remove when a backwash solution is flowed through the vessel in a direction from a top portion 23 to the bottom portion 21 . Alternatively, the feed inlet 20 for the fluid 12 may be disposed at a top portion 23 of the vessel 18 such that the fluid 12 flows in a direction of gravity downward through the vessel 18, or the vessel 18 may be arranged such that the fluid 12 flows there through in any other desired direction.

A bed 22 comprised of polymer fibers 24 is packed within the vessel 18 such that void spaces 26 are present between adjacent fibers 24 to collect water immiscible material from the fluid 12 after the fibers 24 have initially been coated with water immiscible material. In an embodiment, the fibers 24 comprise randomly arranged fibers. In this way, the fibers 24 are not in the form of a uniform fabric, weave, foam, or the like, and collectively provide large surface area exposure to an incoming stream or to a fluid generally, as well as a greater amount of void space for the collection of water immiscible material therein. In particular embodiments, the fibers 24 may be randomly arranged relative to a horizontal or vertical axis extending through the vessel 18. Still further, in certain embodiments, the polymer fibers 24 may be entangled with one another.

In addition, each vessel 18 may include at least one outlet 28 for dispensing an effluent 30 from the vessel having a reduced amount of water immiscible material therein after contact with the bed 22. The effluent 30 may be directed to a suitable vessel for storage or for transport to a location for further processing. Further processing may include a further treatment directed at the effluent 30, such as reverse osmosis, to remove further suspended solids, further water immiscible material such as finer emulsified oil particles, and water soluble salts.

In certain embodiments, the fluid 12 may undergo at least some processing prior to introduction to the vessel 18. For example, prior to introduction to the vessel 18, the fluid 12 may be directed to an API separator, such as those available from Siemens Energy Inc., to filter bulk water immiscible material and suspended solids from the stream 12. Thus, in an embodiment, the source 14 may, in fact, comprise an API separator. The fluid 12 may be any aqueous stream comprising an amount of water immiscible material therein. In an embodiment, the water immiscible material comprises a petroleum-based oil. In particular embodiments, the water immiscible material may include emulsified oil, which also may be petroleum-based. It is understood that not all water immiscible material within the fluid 12 need be in the form of emulsified oil. When present, the emulsified oil may be in the size range of at least about 20 μιτι, for example, such as from about 20 to about 1000 μιτι. As used herein, the term "about" refers to plus or minus 10% of the referenced number.

In addition, the fluid 12 may further comprise an amount of suspended solids therein. In a particular embodiment, the fluid 12 comprises produced water from an oil or a gas recovery process. The fluid 12 may be introduced into the vessel 18 as a moving stream at a suitable flux rate, although it is understood the invention is not so limited. As shown, at least one pump (P) and valve (V) may direct and regulate flow of the fluid 12 into the vessel 18.

The removal circuit 16 may include one vessel 18 or a plurality of like vessels 18 to remove an amount of water immiscible material, such as emulsified oil, from the fluid 12. Each vessel 18 may comprise a body formed from a relatively inert and rigid material such as stainless steel, aluminum, or a polymeric material such as polyvinyl chloride. In addition, each vessel 18 includes a cavity 19 having an internal volume sized for accommodating an effective amount of polymer fibers 24 for contact with the fluid 12. For example, in an embodiment, the vessel 18 may have an internal volume of from about 25 mL to about 10,000 L. Larger or smaller internal volumes may be provided, however, depending on the particular application.

The polymer fibers 24 may be formed from any material having oleophilic properties. In some embodiments, the fibers 24 are formed from a polymeric material. In other embodiments, the fibers 24 may comprise a non- polymeric material coated with a polymeric material. Without limitation, the fibers 24 may comprise a material selected from the group consisting of a polyester, polystyrene, polypropylene, polyethylene, polyamide, aramid, polyurethane material, and the like. The inventor found that polyester in particular exhibited excellent results for removing emulsified oil from an emulsified oil-containing stream. Thus, in an embodiment, the polymeric material comprises polyester. By way of example, polyester fibers for use in the vessel 18 herein are commercially available under the trademark Poly- Fil®.

The polymer fibers 24 may be selected to have a size, such as length and diameter, effective to create the desired void spaces 26 between adjacent fibers 24. In an embodiment, the polymer fibers 24 have a fiber diameter in the range of about 1 to about 1000 μιτι, and in a particular embodiment from about 10 to about 100 μιτι, and in a more particular embodiment from about 45 to about 50 μιτι. Assuming that the size of the void spaces 26 can be kept the same or substantially similar throughout the bed 22, it is believed that increasingly thinner fibers 24 would provide a correspondingly greater surface area for exposure to the fluid 12. On the other hand, increasingly thicker fibers 24 would be expected to reduce the amount of surface area for exposure to the fluid 12. In addition, the fibers 24 may be of any suitable length, e.g., longitudinal length, to define the void spaces 26.

In certain embodiments, the fibers 24 may be packed within the vessel 18 such that the void spaces 26 total a predetermined volume (total void space) in the cavity 19 of the vessel 18. For example, in an embodiment, the total void space may comprise at least about 75 vol. %, and in another embodiment at least about 80 vol. %, and in yet another embodiment, at least about 90 vol. %. It is appreciated that the amount of fibers 24 and the void space volume are preferably sufficient to prevent channeling as a result of insufficient media in the vessel 18. In addition, it may be desirable that the total void space is not so small such that the bed 22 becomes plugged as a result of too much media and/or suspended solids overwhelming the void spaces 26.

To achieve the desired total void space volume, the polymer fibers 24 may be packed into the vessel 18 to a desired bulk density. In an embodiment, the bulk density may be provided in an amount of from about 10 to about 500 g/L, and in particular embodiments from about 100 to about 300 g/L. The desired bulk density may be acquired by compressing the bed 22 to a desired degree by any suitable method or structure. In certain

embodiments, fibers 24 may be added to the cavity 19 of the vessel 18, the added fibers 24 compressed, then further fibers 24 may be added and compressed, and so forth, as desired.

The fibers 24 may be maintained within the cavity 19 of the vessel 18 by any suitable method or structure. In certain embodiments, the fibers 24 may be contained within the cavity 19 of the vessel 18 between a first retention plate 32 positioned adjacent the top portion 23 of the vessel 18 and a second retention plate 34 positioned adjacent the bottom portion 21 of the vessel 18. The retention plates 32, 34 may have any structure suitable, such as a screen or a perforated plate, to retain the polymeric fibers 24 within the cavity 19 while allowing the stream 12 to enter and exit the vessel 18. Thus, in some embodiments, the retention plates 32, 34 may define any inlet and/or any outlet, respectively, for this vessel 18.

As indicated above, it is believed that as the fluid 12 is fed into the vessel 18 or is otherwise contacted with the fibers 24, the polymeric fibers 24 first attract water immiscible material to a surface thereof and are thus able to extract a quantity of water immiscible material from the fluid 12. Once coated with the water immiscible material, additional water immiscible material may be attracted to the now water immiscible material coated fibers and settle within the void spaces 26 in the bed 22. Solids may also trapped within the void spaces 26.

Due to the very large surface area provided by the fibers 24 and the void space volume provided between adjacent fibers 24, there is provided herein a recovery apparatus and system with a very high loading capacity for water immiscible material, such as oil and including emulsified oil. In certain embodiments, the bed 22 may have a loading capacity of at least 1 g water immiscible material per in³ of media, and in certain embodiments from about 1 to about 10 g/in³. In addition, in certain embodiments, the vessel 18 may be effective to remove from 50 % to over 99 % by mass of water immiscible material in the stream 12. Further, the vessel 18 may be effective to provide an effluent comprising less than 1 mg/L of water immiscible material therein.

It is appreciated that the water immiscible material removal efficiency of the vessel 18 may be dependent on the flux of the stream 12 entering the vessel 18, the amount of media (fibers 24), the individual and total volume of void spaces 26, and the bulk density of the bed 22, for example. Thus, at least any one or more of these parameters may be modified to achieve a desired removal efficiency.

It is further appreciated that, at a certain point, the bed 22 may become saturated with water immiscible material so as to affect its removal efficiency and/or impede ability of the fluid 12 to travel through the bed 22 when the fluid 12 is a moving fluid. Thus, in an embodiment, suitable sensors can be placed in the system 10, such as at an inlet 20 and/or an outlet 28 of the vessel 18, to determine if a pressure drop across the bed 22 exceeds a predetermined value. Alternatively, it may be desired to replace the bed 22 or vessel 18, or regenerate the bed 22 after a suitable time has elapsed or after a known volume of the fluid 12 has traveled through the vessel 18.

In accordance with another aspect, the systems and methods described herein provide for extended use of the vessel 18 via backwashing with a backwash solution, which may in some embodiments comprise a portion of the effluent 30 from the vessel 18. This backwashing step may take place at predetermined intervals in the separation processes described herein, after a predetermined volume of fluid has traveled through the bed 22, and/or via sensors which provide an indication to initiate a backwashing step. While not wishing to be bound by theory, it is believed that the backwashing will remove at least an amount of collected solids and water immiscible material from within the void spaces 26. In other embodiments, the bed 22 may be further regenerated by flow of a solvent through the vessel 18 for the water immiscible material, such as an organic solvent, e.g., naphtha or hexane. While not wishing to be bound by theory, it is believed the solvent may be more effective than the backwash solution in removing at least some water immiscible material from a surface of the polymer fibers 24.

Referring now to FIG. 2, there is shown a system 10B having a regeneration circuit 36 for a system 10B which utilizes one or more suitable regeneration liquids to wash the bed 22 to ready the bed 22 for additional separation of water immiscible material from an aqueous fluid comprising the same. In an embodiment, the regeneration liquid comprises a backwash solution. Thus, in an embodiment, the regeneration circuit 36 may comprise a backwash source 38 and a backwash solution 40. As shown, at least one pump (P) and valve (V) may direct and regulate flow of the fluid 12 into the vessel 18 packed with fibers 24. The fluid 12 may exit the vessel 18 as effluent 30 having a reduced amount of water immiscible material therein. In the embodiment shown, the effluent 30 may travel to a storage tank which may define a backwash source 38. In this way, a portion of the effluent 30 may be utilized as a backwash solution 40 for the bed 22. The regeneration liquid may comprise an effluent 30 from the same bed 22 or a distinct bed 22 from the bed being backwashed.

As shown, from the backwash source 38, backwash solution 40 may be delivered to the vessel 18. In certain embodiments, the backwash solution 40 travels through the vessel 18 in the opposite direction that the fluid 12 flowed through the vessel so as to improve regeneration efficiency. It is understood however that the present invention is not so limited. Flow of the fluid 12 and the backwash solution 40 to the vessel 18 may also be

accomplished by at least one pump (P) and valve (V) as shown, or as otherwise would be appreciated by the skilled artisan.

In an alternate embodiment, the backwash solution 40 may comprise another suitable fluid distinct from the effluent 30, and thus the backwash source 38 may be independent of the effluent 30. The backwash solution 40 preferably has less water immiscible material than the incoming fluid 12 to the bed 22 such that the backwash solution 40 does not add further contaminants to the bed 22. When valves (V) allow flow of the stream 12 to the vessel 18, the system 10B may be said to be in a recovery mode. Conversely, when the same valves (V) are closed and valves (V) between the backwash source 38 and the vessel 18 are opened such that the backwash solution 40 flows to the vessel 18, the system 10B may be said to be in a regeneration mode.

The backwash solution 40 may be provided to each vessel 18 in the system 10 at any suitable flux rate effective to remove a quantity of water immiscible material and collected solids from the bed 22. In certain embodiments, the backwash solution 40 may be provided at a flow rate to a selected vessel 18 that is at least about 1 .5 times the flow rate that the fluid 12 is delivered to the same vessel 18, and in particular embodiments at least about twice the flow rate that the fluid 12 is introduced to the same vessel 18

In accordance with another aspect, the regeneration fluid may or instead comprise a solvent for the water immiscible material. Referring to FIG. 3, there is shown a system 10C, wherein a vessel 18 may instead or also be washed with a solvent 42 delivered from a suitable solvent source 44 to extract water immiscible material from the bed 22. For ease of viewing, the source 14 and flow therefrom is not shown. When used in combination with the backwash solution 40, it is believed that the backwash solution 40 may be effective to reduce an amount of water immiscible material in the bed 22 by removing water immiscible material and solids from the void spaces 26 between the fibers 24. However, water immiscible material that is more closely attached to the fibers 24 may require a different method for

regeneration thereof. In this instance, the solvent 42 may be effective to further extract water immiscible material from the bed 22.

The solvent 42 may be delivered at a suitable flux rate, and in some embodiments, is lower than a flux rate of the fluid 12 entering the vessel 18. Without limitation, the solvent 42 may comprise any suitable material for solubilizing or carrying at least an amount of the water immiscible material, which may be emulsified oil, therein. In an embodiment, the solvent 42 comprises an organic solvent selected from the group consisting of naphtha, kerosene, gasoline, other non-polar hydrocarbons such as hexane, heptane, toluene, and the like. The inventor has found that these solvents are particularly suitable for regeneration of a bed 22 comprised of polymer fibers 24 as described herein for further use thereof.

Referring again to FIG. 3, in accordance with another aspect of the present invention, the vessel 18 may be purged with a gas 46 from a suitable gas source 48 for a predetermined amount of time prior to flow of the backwash solution 40 or solvent 42 through the bed 22. In certain

embodiments, the gas 46 comprises air. In certain embodiments, this gas purge improves removal efficiency, e.g., oil removal efficiency, by the backwash solution 40 and/or solvent 42 when performed prior to the introduction of such fluids. The gas 46 may be introduced into the vessel 18 at a suitable flow rate such that the fiber integrity of the bed 22 is not significantly disturbed, such as from about 1 m³/sec to about 10 m³/sec.

As with the backwash solution 40, flow of the solvent 42 and gas 46 to the vessel 18 may also be accomplished by one or more pumps (P) and/or valves (V) as shown, or as otherwise would be appreciated by the skilled artisan. In addition, though the solvent 42 and gas 46 are illustrated as entering the vessel 18 at a top portion 23 thereof, it is appreciated that the invention is not so limited. To accomplish the switching of modes, flow rates, analysis of data (e.g., sensor data), and intermittent switching of selected valves to open and closed positions, one or more controllers comprising a processor and a memory may be employed in the system 10 to control the system components to carry out their intended function. The controller(s) may be in wired or wireless connection with the sensors, pumps, valves, or the like, for example

In certain embodiments, the introduction of the fluids (backwash solution 40, solvent 42, and/or gas 46) may be initiated upon the expiration of a suitable time period, upon a suitable indication from one or more sensors, or upon suitable instruction from a controller. Thus, in a particular embodiment, the system 10 may be in a recovery mode when the system 10 is removing water immiscible material from the fluid 12 and the system 10 may be switched to a regeneration mode after a predetermined amount of time operating in the recovery mode. In one embodiment, for example, the system 10 may be in operation for a period of 1 -24 hours, for example, and the system 10 intermittently switches from a recovery mode to a regeneration mode during the operation, such as about every 10-60 minutes. Alternatively, as mentioned, any system described herein may include a pressure sensor, e.g., sensor 25 shown in FIG. 3, configured to measure pressure drop across the bed 22. The introduction of any one or more of fluids 40, 42, and 46 may be commenced upon an indication from the sensor 25 that the pressure drop in the bed 22 exceeds a predetermined value. Alternatively, one or more controllers may initiate a command to switch one or more vessels 18 the system 10 from operation in one mode to another.

It is appreciated the systems described herein may include more than one vessel 18 to accomplish a desired removal efficiency. Thus, although one vessel 18 was described above, it is clear the systems may comprise more than one vessel and the above descriptions may apply to each vessel 18 in the system. When multiple vessels 18 are provided, in an embodiment, at least one vessel 18 may operate in a recovery mode while at least one other vessel 18 operates in a regeneration mode. In this way, the fluid 12 may be continuously and more efficiently treated.

Referring to FIG. 4, for example, there is shown a recovery system 10D comprising a first vessel 18A and a second vessel 18B operating in parallel, although it is appreciated more vessels could be provided. As noted previously, a source 14 of a fluid 12, which may comprise emulsified oil and suspended solids for example, may be fluidly connected to each of the first vessel 18A and the second vessel 18B. The backwash source 38 delivering backwash solution 40 may, in turn, be fluidly connected with the first vessel 18A and the second vessel 18B and deliver a suitable backwash solution thereto as described previously. It is appreciated that system 10D may further include delivery of a solvent 42 and/or gas 46 to each vessel 18A, 18B as was previously described herein. Thus, while one of vessels 18A, 18B is receiving a fluid 12 from source 14 in a recovery mode, the other of vessels 18A, 18B may be receiving one of a backwash solution 40, solvent 42, or gas 46 for regeneration of the associated vessel 18B in a regeneration mode.

The apparatus, methods, and systems described herein may be suitable for any number of applications for removing at least a quantity of a water immiscible material from an aqueous fluid comprising the same, including but not limited to applications for removing emulsified oil from an emulsified oil-containing stream. For example, the apparatus, systems and methods described herein may be suitable for use in a polishing step after a prior standard oil removal process. In addition, the apparatus, systems, and methods described herein may be utilized in lieu of ultrafiltration or a coalescing process. Further, the apparatus, systems and methods described herein may replace or be utilized downstream of a walnut shell filter as is known in the art. In certain embodiments, the loading capacity for the vessels provided herein may be effective to provide a vessel, system, and/or method with an effluent having a water immiscible material (e.g., emulsified oil) concentration of less than 1 mg/L.

In a specific embodiment, the apparatus, systems and methods described herein may be suitable for the treatment of flowback water.

Flowback water typically includes dissolved organic molecules that need removal along with oil, which is often in the form of very tight emulsions. It has been found that standard flotation processes or even walnut shell filters do not work very well for removal of either of these components. Moreover, while activated carbon columns may be utilized to remove oil and dissolved organic molecules, such processes require a significant amount of activated carbon material, which cost-wise and space-wise may not be feasible.

In accordance with one aspect, the apparatus, systems, and methods described herein may be utilized to remove oil from a fluid, such as flowback water, prior to delivery of the fluid to a source of activated carbon, such as one or more granular activated carbon columns. In this way, a substantial amount of oil may first be removed from the fluid by the polymer fibers described herein, thereby allowing the activated carbon to primarily remove dissolved organic molecules from the flowback water and reducing the amount of activated carbon needed for the overall treatment of a fluid such as flowback water. For example, as shown in FIG. 5, an effluent 30 may be delivered from a selected vessel 18 to a dissolved organics removal station 50 in fluid communication with the vessel 18. The station 50 comprises one or more sources (columns or the like) of activated carbon, e.g., granulated activated carbon, for removal of the dissolved organics from the effluent 30.

The function and advantages of these and other embodiments of the present invention will be more fully understood from the following examples. These examples are intended to be illustrative in nature and are not considered to be limiting the scope of the invention

EXAMPLES

Example 1

1 .5 cm-diameter columns and a 2 inch columns were separately filled with 50 mL polyester fibers. The fibers were then compacted to provide the desired bulk density of fibers. For the large columns, the bulk density was calculated as being 150-170 g/L. In the process of packing the 2 inch columns, which had a bed volume of 2L, the amount of fibers used were measured, allowing for calculating the density. This was repeated for each large column packed, resulting in the range measured.

The bulk packed density of the fibers for the smaller 50 cm columns were calculated to be 250-300 g/L. In some instances, this was calculated using a tared 10 mL graduated cylinder packed with fibers in the same way as the columns. The higher bulk density values for the smaller fibers is likely due to the smaller fibers being easier to handle and compact, leading to more force per unit of volume on the fibers. Example 2

A 1 .5 cm diameter column using a 50 ml_ bed volume was tested for oil removal efficiency. Flow was directed upward through the column at 10 mL/min (1800 gfd) using a peristaltic pump to regulate flow rate. The feed was Arabian Heavy Crude (API=26.4) in water, using a blender to mechanically emulsify the oil; initially the feed oil concentration targeted 20 mg/L to test the fibers as a polishing step.

This first column proved that polyester fibers could work very well at filtering oil from water, polishing the water stream to undetectable

concentrations of oil in the effluent (using the Turner Design Hydrocarbons hand-held oil-in-water TD-500 D field instrument which measures based on fluorescence, the limit of quantitation is 1 mg/L oil). Also, the oil loading was high, holding 670 mg oil per g fiber (3.1 g oil/in³). Table 1 has the feed and effluent oil concentrations for this first column.

Table 1 : Feed and effluent concentrations along with oil loading for initial test in 50 ml_ column.

Feed Oil Effluent Oil

Volume of Concentrati Concentrati Cumulative Oil Load per

Feed on on Oil Load Mass of Media

(mg oil/mg

(L) (mg/L) (mg/L) (g) media)

0 0 0

.8 44 0.3 0.03 2.52

3.1 43.4 0.1 0.13 9.71

5.7 7.1 0 0.15 1 1 .02

14.8 90.8 0.2 0.98 70.88

49.0 22.1 0.1 1 .73 125.20

56.9 1 1 .6 0.4 1 .82 131 .59

65.8 83.6 0.2 2.56 185.18

74.8 3.2 0.2 2.59 187.13

80.7 48.5 0.2 2.88 207.71

90.8 37.3 0 3.25 234.91

102.2 72.8 0.3 4.08 294.58

1 10.4 23.1 0.2 4.27 308.14

130.1 13.8 0.2 4.54 327.49

152.4 32.3 0.2 5.25 379.17

243.4 23.9 1 .5 7.29 526.35

248.8 17.5 1 .8 7.37 532.41

249.5 9.8 0.9 7.38 532.89

250.5 9.2 0.7 7.39 533.51

258.3 148.8 0.3 8.55 617.14

273.6 58.7 8.1 9.32 673.04

Example 3

To test the regeneration of the 50 mL column, small amounts of fibers (0.4-0.7 g) were swirled in oily water - again Arabian Heavy Crude. The initial and final concentrations of oil in the water were measured. Thus, along with the volume used, the oil adsorbed by the fibers could be calculated. The oily fibers were transferred to another beaker in which they were swirled in hexane, naphtha or boiling water. The fibers were dried, the solvents evaporated in a fume hood while the water was dried in an oven, and weighed to find the oil remaining. The results (Table 2) of this experiment demonstrated that the adsorbed oil could be removed with solvents. Both hexane and naphtha successful in removing over 90% of the adsorbed oil from the fibers.

Table 2: Regeneration beaker tests with three initial test solutions.

Hot

Hexane Naphtha Water

Mass of fibers (mg) 405.5 676.9 715.1

Volume of feed (ml_) 400 500 450

Concentration of

(mg/L) 300.3 656.1 656.1 feed

Concentration

(mg/L) 91 .6 245.6 207.8 after

Mass of oil

(mg) 83.5 205.3 201 .7 adsorbed

Volume used for

(ml_) 70 100 300 regeneration

Mass of dry fibers (mg) 410.9 695.3 859.7

Mass of oil

(mg) 5.4 18.4 144.6 remaining

% oil removed 94% 91 % 28%

While various embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.

Claims

CLAIMS The invention claimed is:

1 . A method for removing water immiscible material from an aqueous fluid (12) comprising the water immiscible material, the method comprising:

contacting the aqueous fluid (12) with a bed (22) of randomly arranged polymer fibers (24) packed such that void spaces (26) remain between adjacent fibers (24) sufficient to collect the water immiscible material within the void spaces (26) after the fibers (24) have initially been coated with the water immiscible material.

2. The method of claim 1 , wherein the water immiscible material comprises emulsified oil, and wherein the contacting is done in the absence of added chemicals or added pressure to coalesce the emulsified oil.

3. The method of claim 1 , wherein the method is effective to produce of an effluent having concentration of water immiscible material of less than about 1 mg/L.

4. The method of claim 1 , wherein the void spaces (26) define a total void space of at least about 75 % by volume of the bed.

5. The method of claim 1 , wherein the void spaces (26) define a total void space of at least about 90 % by volume of the bed.

6. The method of claim 1 , wherein the polymer fibers (24) comprise polyester.

7. The method of claim 1 , further comprising backwashing the bed with a regeneration liquid (40, 42) to remove water immiscible material collected in the void spaces (26) or on the fibers (24) in order to regenerate the bed for subsequent use.

8. The method of claim 7, wherein the regeneration liquid (40, 42) comprises an effluent (30) from the contacting.

9. The method of claim 8, wherein the backwashing is done at a flux rate which is at least about twice a flux rate at which the fluid (12) is introduced to the bed (22).

10. The method of claim 7, further comprising delivering an amount of gas (46) through the bed prior to the backwashing.

1 1 . The method of claim 7, wherein the regeneration liquid (40, 42) further comprises a solvent (42), and further comprising delivering the solvent to the bed (22) to remove water immiscible material from the bed (22) and to regenerate the bed (22) for subsequent use.

12. The method of claim 7, further comprising providing a plurality of vessels (18) packed with the fibers (24), wherein a first selected vessel (18A) is configured to operate in a regeneration mode such that the selected vessel (18A) is regenerated via delivery of the regeneration liquid (40, 42) to the selected vessel (18A) while a distinct second vessel (18B) operates in a recovery mode and removes water immiscible material from the fluid (12).

13. The method of claim 7, wherein the regeneration liquid (40, 42) comprises an effluent (30) of the fluid (12) that has passed through randomly arranged polymer fibers (24) in the same bed (22) as or in a distinct bed (22) from the bed (22) being regenerated.

14. The method of claim 1 , wherein the bed (22) is disposed within a vessel (18), and wherein the fluid (12) is passed through the vessel (18) in a direction counter to a direction of gravity.

15. The method in any of claims 1 to 14, further comprising following contact with the polymer fibers (24), contacting the fluid (12) with activated carbon for removal of dissolved organic compounds.

16. The method in any of claims 1 to 15, wherein the water immiscible material comprises a petroleum-based oil.

17. The method in any of claims 1 to 16, wherein the water immiscible material comprises emulsified oil.

18. The method of claim 17, wherein the emulsified oil has a particle size of about 20 to about 1000 μιτι.

19. A vessel (18) for removing water immiscible material from an aqueous fluid (12) comprising the water immiscible material, the vessel (18) comprising:

a feed inlet (20) for receiving the fluid (12) and allowing travel of the fluid (12) into the vessel (18);

a bed (22) of randomly arranged polymer fibers (24) packed within the vessel (18) such that void spaces (26) remain between adjacent fibers (24) sufficient to collect water immiscible material from the fluid (12) within the void spaces (26) after the fibers (24) have initially been coated with water immiscible material; and

an outlet (28) for dispensing an effluent (30) from the vessel (18).

20. The vessel (18) of claim 19, wherein the water immiscible material comprises emulsified oil, and wherein the vessel (18) does not include added chemicals or added pressure in order to coalesce the emulsified oil.

21 . The vessel of claim 19, wherein the vessel (18) is effective to produce of an effluent (30) having a concentration of water immiscible material of less than about 1 mg/L.

22. The vessel (18) of claim 19, wherein the bed (22) comprises a bulk density of from about 100 to about 300 g/L.

23. The vessel (18) of claim 19, wherein the bed (22) comprises a loading capacity for the water immiscible material of from about 1 to about 10 g/in³.

24. The vessel (18) of claim 19, wherein the void spaces (26) define a total void space of at least about 75 % by volume of the bed.

25. The vessel (18) of claim 24, wherein the void spaces (26) define a total void space of at least about 90 % by volume of the bed.

26. The vessel (18) of claim 19, wherein the polymer fibers (24) comprise polyester.

27. The vessel (18) of claim 19, wherein the water immiscible material comprises emulsified oil.

28. A system (10) for removing a water immiscible material from an aqueous fluid (12) comprising the water immiscible material, the system (10) comprising:

one or more vessels (18), each vessel (18) comprising:

an outlet (28) for dispensing an effluent (30) from the vessel

(18).

29. The system (10) of claim 28, further comprising a regeneration circuit (36) in fluid communication with the one or more vessels (18) configured to provide at least one regeneration liquid (40, 42) from a regeneration liquid source (38, 44) to a selected one of the one or more vessels (18) for regeneration of an associated bed (22).

30. The system (10) of claim 28, wherein the system (10) comprises a plurality of vessels (18A, 18B), and wherein a selected vessel (18A) is configured to operate in a regeneration mode such that the selected vessel (18A) is regenerated via delivery of the at least one regeneration liquid (40, 42) to the selected vessel (18A) from the regeneration circuit (36) while a distinct vessel (18B) operates in a recovery mode and removes water immiscible material from the fluid (12).

31 . The system (10) of claim 30, wherein the void spaces (26) define a total void space of at least about 75 % by volume of the bed.

32. The system (10) of claim 31 , wherein the void spaces (26) define a total void space of at least about 90 % by volume of the bed.

33. The system (10) of claim 28, wherein the water immiscible material comprises emulsified oil, and wherein the system (10) does not include added chemicals or added pressure in order to coalesce the emulsified oil.

34. The system (10) of claim 28, wherein the system (10) is effective to produce of an effluent (30) having a concentration of water immiscible material of less than 1 mg/L.

35. The system (10) of claim 28, wherein the bed (22) comprises a bulk density of from about 100 to about 300 g/L.

36. The system (10) of claim 28, wherein the bed (22) comprises a loading capacity for the water immiscible material of from about 1 to about 10 g/in³.

37. The system (10) of claim 28, wherein the polymer fibers (24) comprise polyester.

38. The system (10) of claim 28, further comprising a dissolved organics station (50) comprising a source of activated carbon for removal of dissolved organic compounds in the effluent (30).

39. The system (10) in any one of claims 28 to 38, wherein the water immiscible material comprises emulsified oil.