WO2008088293A1

WO2008088293A1 - Membrane contactor

Info

Publication number: WO2008088293A1
Application number: PCT/SG2008/000019
Authority: WO
Inventors: Zan-Guo Peng; Tong Zhou; Jyh-Jeng Shieh; Kam-Chern Lee
Original assignee: Hyflux Membrane Manufacturing (S) Pte Ltd
Priority date: 2007-01-18
Filing date: 2008-01-16
Publication date: 2008-07-24
Also published as: TW200846070A

Abstract

A membrane contactor comprising an enclosed chamber having an inlet conduit and outlet conduit extending through at least one chamber sidewall, a plurality of selectively permeable hollow fiber membranes passing through said enclosed chamber for allowing fluid to pass therethrough from an inlet end to an outlet end sealingly separated from said enclosed chamber, and a porous distributor cover substantially covering said plurality of membranes passing through said chamber and being disposed between said membranes and said at least one chamber sidewall to define a fluid feed region therebetween in fluid communication with said enclosed chamber inlet.

Description

Membrane Contactor

Technical Field

The present invention generally relates to a membrane contactor.

Background

Membrane contactors are devices through which a liquid and a gas are either separated in a degassing operation or combined in a gassing operation using a membrane permeable to the gas being transferred.

A hollow fiber porous membrane is a tubular filament comprising an outer diameter and an inner diameter, with a porous wall thickness between them. The inner diameter defines the hollow portion of the fiber and is used to carry one of the fluids .

In "shell side contacting", the liquid phase

^• surrounds the outer diameter and outer surface of the fibers and the gas phase flows through the lumen. For example, in a^' degassing process involving the removal of oxygen from ultrapure water by gas stripping with a vacuum, the vacuum is applied to the lumen side of the hollow fibers while the water feed containing the gas is supplied to the shell side of the hollow fibers in an enclosed chamber.

The membrane contactors can 'be used for liquid- liquid extraction between two liquid phases such as extraction of metal ions, organic acid and biomolecules. Another major application of membrane contactors is to achieve mass transfer between a gas and a liquid phase.

There are two types of mass transfer applications, namely (a) stripping gas from liquid or (b) adding gas into liquid. Examples of mass transfer applications involving stripping gas from liquid include degassing of oxygen and/or carbon dioxide, stripping of volatile organic compound (VOC) , and recovering of aromatic compounds. Examples of mass transfer applications by adding gas into liquid include absorption of flue gas, and carbonation or nitrogenation to beverages .

Similarly, when fluid passes through the lumen side of the hollow fiber membranes ("lumen side contacting") , the fluid flow rate is limited by the pressure -drop due to the fluid flow inside the hollow fiber membranes, and thereby limiting the mass transfer to laminar flow conditions . ■

Several attempts have been made to overcome these problems associated with lumen side contacting. The diameter of the hollow fiber membranes could foe increased to increase the contact surface area while reducing pressure drop. However, the contact surface area of the hollow fiber membranes within the membrane contactor would still be limited by the -smaller number of the hollow fiber membranes that could be accommodated within the enclosed chamber. Alternatively, the length of the hollow fiber membranes could be increased to increase the contact surface area. However, the pressure drop of the membrane contactor is also increased, and for instances when the fluid is flown through the shell -side of the hollow fiber membranes, the channeling of fluid flow is more severe .

The high pressure drop problems associated with lumen side contacting can be overcome with shell side contacting operations. A known spiral-type hollow fiber membrane contactor comprises an enclosed chamber having a bundle of hollow fiber membranes spirally wound around the longitudinal axis of a perforated tube. Flow- directing baffles are disposed within the chamber to increase the cross-current flow of liquid therein. However, the liquid feed is fed from a central conduit placed at one end of the enclosed chamber, which results in the formation of "dead zones", which are regions that are relatively low in gas content. Gas is not efficiently removed from the dead zones and the uneven flow distribution results in inefficient mass transfer of the gas from the liquid phase.

Therefore, there is a need to provide a membrane contactor that overcomes, or at least ameliorates, one or more of the disadvantages described above.

More importantly, there is a need to fabricate a novel structural design for membrane contactors to improve mass transfer.

Summary

Ac-cording to a first aspect, there is provided a membrane contactor comprising: an enclos-ed chamber having an inlet conduit and outlet conduit extending through at least one chamber sidewall; a plurality of selectively permeable hollow fiber membranes passing through said enclosed chamber for allowing fluid to pass therethrough from an inlet end to an outlet end sealingly separated from said enclosed chamber; and a porous distributor cover substantially covering said plurality of membranes passing through said chamber and being disposed between said membranes and said at least one chamber sidewall to define a fluid feed region therebetween in fluid communication with said enclosed chamber inlet.

According to a second aspect, there is provided a system for separating one or more fluids from a fluid mixture of two or more fluids by passing the fluid mixture through a membrane contactor according to the first aspect, wherein the outlet ends of said hollow fiber membranes are in fluid communication with a pressure source; wherein in use, said pressure source forms a partial pressure difference between said hollow fiber membranes lumen side and said membranes outer surface for removing one or more fluids s-electively permeable through said hollow fiber membranes.

According to a third aspect, there is provided a system for degassing a liquid by flowing the liquid through a separation chamber according to the first aspect, wherein the outlet ends of said hollow fiber membranes are in fluid communication with a negative pressure source; wherein in use, said negative pressure source forms a vacuum within said hollow fiber membranes, thereby creating a partial pressure difference between the shell side and lumen side of said hollow fiber membranes for removing the dissolved gas in the liquid flowing therethrough, thereby degassing the liquid.

According to a fourth aspect of the invention, there is provided a separation system comprising: a plurality of membrane contactor according to the first aspect in series and/or parallel fluid flow with respect to each other; a vacuum pump in fluid communication with said outlet ends of said hollow fiber membranes; a capture unit in fluid communication with the vacuum pump for containing at least one fluid extracted by the vacuum pump therein; and a storage tank in fluid communication with said outlet conduits of said plurality of membrane contactor to contain fluid product therein, wherein the fluid product can be used directly or recycled into the system for further separation.

According to a fifth aspect of the invention, there is provided a method for separating one or more fluids from a fluid feed comprising a mixture of two or more fluids by passing said fluid feed through a membrane contactor according to the first aspect.

According to a sixth aspect of the invention, there is provided a method for separating one or more fluids from a fluid feed comprising a mixture of two or more fluids comprising the steps of:

(a) passing said fluid feed through an inlet conduit of a membrane contactor comprising an enclosed chamber;

(b) distributing said fluid feed to a fluid feed region disposed between a porous distributor cover and at least one chamber sidewall;

(c) passing said fluid feed through an array of holes substantially evenly distributed along the length of said porous distributor cover toward a plurality of selectively permeable hollow fiber membranes;

(d) applying a pressure source to the lumen side of said membranes to form a partial pressure difference between the shell side and the lumen side of said membranes for separating one or more fluids that are selectively permeable through said membranes from said fluid feed, thereby obtaining a fluid product substantially free of said one or more fluids that are selectively removed; and

(e) removing said fluid product through an outlet conduit of said enclosed chamber. According to a seventh aspect of the invention, there is provided a fluid product as prepared by the method according to the sixth aspect.

Definitions

The following words and terms used herein shall have the meaning indicated:

The term "substantially spirally wound around an axis" is to be interpreted broadly to refer to hollow fiber membranes that are disposed in a plane curve traced by a point circling about the center but at increasing distances from the center and to a helically dispos-ed hollow fiber membranes that are disposed in a curve disposed from the axis at a constant or varying angle.

The term "substantially" does not exclude "completely" e.g. a composition which is "substantially free" from Y may be completely free from Y. That is, the term "substantially" is to be interpreted as "completely" or "partially". Where necessary, the word "substantially" may be omitted from the definition of the invention.

Unless specified otherwise, the terms "comprising" and "comprise", and grammatical variants thereof, are intended to represent "open" or "inclusive" language such that they include recited elements but also permit inclusion of additional, unrecited elements.

As used herein, the term "about", in the context of concentrations of components of the formulations, typically means +/- 5% of the stated value, more typically +/- 4% of the stated value, more typically +/- 3% of the stated value, more typically, +/- 2% of the stated value, even more typically +/- 1% of the stated value, and even more typically +/- 0.5% of the stated value.

Throughout this disclosure, certain embodiments may be disclosed in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosed ranges. Accordingly, the description of a range should be considered to have specifically disclo-sed all the possible sub-ranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

Description of Optional Embodiments

The selectively permeable hollow fiber membrane may be a hydrophobic or hydrophilic microporous polymeric membrane that may be non-coated or coated by one or several types of gas-permeable or gas-selective polymer on its outer surface.

Exemplary hydrophilic polymers may be selected from the group consisting of poly alkyl (acrylic) acid, polyacrylamide, polyethylene glycol, polyalkylene oxide, poly alkyl vinyl ether, poly styrene sulfonic acid, poly vinyl alcohol, poly alkylene imine, poly vinylamine, poly vinyl carboxylic acid, polyamine, derivatives, salts and combinations thereof. Exemplary types of hydrophilic polymers are disclosed in US patent number 5,985,354. Exemplary hydrophobic polymers include poly alkyl acrylate, polydiene, polyolefin, polylactone, polysiloxane, polyoxirane, polypyridine, polycarbonate, poly vinyl acetate, polysulfone, polypropylene (PP) , polytetrafluoroethylene (PTFE), polyethylene (PE), polyvinylidenefluoride (PVDF) , polymethylpentene (PMP) , polydimethylsiloxane, polybutadiene, polystyrene, polymethylmethacrylate, perfluoropolymer, poly(2-alkyl or phenyl oxazolines) , derivatives, salts and combinations thereof.

Exemplary microporous polymers include polyvinylidene fluoride, polyethylene, polyvinyl chloride, polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride-hexafluoropropylene copolymer, ethylene-acrylic acid copolymer, ethylene-styrene copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, polydiene, polyalkane, polyacrylic, polyvinyl ether, polyvinyl alcohol, polyacetal, polyvinyl ketone, polyvinyl halide, polyvinyl nitril, polyvinyl ester, polystyrene, polyphenylene, polyoxide, polycarbonate, polyester, polyanhydride, polyurethane, polysulfonate, polysulfide, polysulfone, polyamide, derivatives, salts and combinations thereof. Exemplary types of ^' microporous polymers are disclosed in US patent number 5,254,354. In one embodiment, the hollow fiber membrane comprises a microporous inner polymer layer, such as a hydrophobic polymer layer, and an external coating on the microporous inner polymer layer. The external coating may be formed by surface modification of the microporous inner polymer layer. In one embodiment, the external coating may be a polymer such as polydimethylsiloxane. Polydimethylsiloxane is a type of polymer known in the art to be selectively permeable for gaseous volatile organic compounds . Advantageously, the type of hollow fiber membrane can be chosen depending on the fluid that is to ^• be separated from the fluid feed. The fluid feed refers to any mixture of two or more fluids. It may comprise of a mixture of one or more liquids and/or one or more gases. For example, the fluid feed may be water containing dissolved oxygen. Alternatively, the fluid feed may be water comprising a volatile organic compound. Yet alternatively, the fluid feed may be an aqueous solution containing one or more solutes dissolved therein. The • intention may then be to remove the water and thereby obtain a concentrated aqueous solution.

In a particular embodiment, the hollow fiber membrane is a hydrophobic polyolefin membrane, selected from the group consisting of polypropylene, polyethylene, polytetrafluoroethylene, polymethylpentene and polyvinylidene fluoride. In another particular embodiment, the hydrophobic polyolefin membrane is polypropylene for removing dissolved oxygen in water. The dimensions of the hollow fiber membranes may be varied to suit the various applications. The pore size may range from about 0.01 to about 0.2 microns, more preferably from about 0.01 to about 0.05 microns. The porosity may range from about 20 to about 70 per cent, more preferably from about 30 to about 50 percent. The outer diameter may range from about 300 to about 800 microns, more preferably from about 400 to about 500 microns. The thickness may range from about 30 to about 80 microns. Preferably, the total surface area of the plurality of hollow fiber membranes ranges from about 0.5 m² to about 50 m². In a particularly preferred embodiment, the total surface area of the plurality of hollow fiber membranes is about 3 m² to about 5 m². Advantageously, the membrane contactor comprises a porous distributor cover substantially covering the plurality of hollow fiber membranes passing through the enclosed chamber. In one embodiment, the porous distributor cover completely covers the plurality of hollow fiber membranes . The porous distributor cover is disposed between the hollow fiber membranes and the enclosed chamber to define a fluid feed region therebetween. This fluid, feed region is in fluid communication with the enclosed chamber inlet for allowing the fluid feed flow toward the sidewall of the enclosed chamber.

The hollow fiber membranes may be readily removable from the enclosed chamber. In one embodiment, the enclosed chamber comprises a cartridge having two removable end caps, said cartridge comprising a plurality of hollow fiber membranes therein. Advantageously, the cartridge can be easily and readily removed from the enclosed chamber of the membrane contactor, thereby allowing the replacement of hollow fiber membranes upon fouling.

The porous distributor cover has an array of holes that are evenly or unevenly distributed along the length of the porous distributor cover so that the fluid feed can be evenly distributed to the plurality of hollow fiber membranes therein.

The holes may be of any shape. In one embodiment, the holes may be square-shaped. In another embodiment, the holes may be circular-shaped. In yet another embodiment, the holes may be rectangular-shaped.

The size of the holes may be in the range of 0.1 mm to 2 mm. In cases where the sizes of the holes are varied, the average size of the holes may be in the range of 0.1 mm to 2 mm. In one embodiment, when the hole is square-shaped, the size range disclosed above refers to the length of the hole. In another embodiment, when the hole is circular-shaped, the size range disclosed above refers to the diameter of the hole. In yet another embodiment, when the hole is rectangular-shaped, the size range disclosed above refers to the length or breadth of the hole.

The distance between the holes may be in the range of 0.1 mm to 1 mm. The porous distributor cover may be made of any material that is resistant to the operation conditions. Such material may be acid resistant or alkaline resistant such that the porous distributor cover does not corrode or disintegrate in situations where extreme pH conditions are used. Further, the material may be resistant to high temperatures that may be employed during operation of the membrane contactor. As an example, such high temperature may be above 100⁰C. The material may be inert and may not substantially react with the reactant fluids during operation of the membrane contactor. Exemplary materials that may be suitable for fabrication of the porous distributor cover include polymers such as polypropylene, polyethylene or nylon.

The porous distributor cover may enclose the plurality of hollow fiber membranes and the ends of the porous distributor cover may be sealed with melt, glue, epoxy or polyurethane resin. It is to be appreciated that other methods to seal the ends of the porous distributor cover such that it substantially encloses the plurality of hollow fiber membranes will be known to a person skilled in the art.

The plurality of hollow fiber membranes may form a woven fabric of hollow fiber membranes . The woven fabric may consist of weft of hollow fiber knitted by warp yarn. The warp yarn may be selected from the group consisting of polypropylene and polyethylene. In one embodiment, the woven fabric may consist of from about 3.9 to about 19.6 weft aligning fiber per cm of said fabric (about 10 to about 50 weft aligning fiber per inch of said fabric) and from about 1.5 to .about 3.9 weft aligning fiber per cm of said fabric (about 4 to about 10 warp yarn per inch of said fabric) .

One or more fluids may be separated from a fluid feed comprising a mixture of two or more fluids by creating a partial pressure difference between the lumen side and the shell side of the hollow fiber membranes. This may be achieved by connecting the outlet ends of the hollow fiber membranes to a pressure source. In a preferred embodiment, a negative pressure is applied to ^' form a vacuum on the lumen side of the hollow fiber membranes. Advantageously, this pressure difference may allow the removal of a dissolved fluid from a fluid feed to obtain a fluid product that is substantially free of the dissolved fluid.

In another embodiment, a positive pressure is applied to the lumen side of the hollow fiber membrane wherein the positive pressure is created by a fluid source being pumped into the hollow fiber membranes. This allows the addition of a fluid to a fluid feed.

The fluid product that may be stripped of one or more fluids or that may have one or more fluids being added therein through the hollow fiber membranes may be collected via the outlet conduit of the enclosed chamber. The outlet conduit of the enclosed chamber may further comprise a perforated tube extending through the enclosed chamber. The perforated tube may have an array of perforated holes for receiving fluid that has passed through the porous distributor cover and the plurality of hollow fiber membranes . Advantageously, the outlet at the other end of the perforated tube is sealingly separated from the enclosed chamber. In one embodiment, there is provided a stopple that may have a female thread for securing the perforated tube to the enclosed chamber and thus, may facilitate this sealing. The perforated tube may be surrounded by the plurality of hollow fiber membranes that are axially wound thereon. Advantageously, this exposes the hollow fiber membranes to a relatively high surface area of the perforated tube surface.

First and second tube sheets may be coupled respectively to the inlet and outlet ends of the plurality of hollow fiber membranes to advantageously hold the hollow fiber membranes in place.

Advantageously, the enclosed chamber has a Length (L) to diameter (d) ratio ranging from about 2 to about 10. The enclosed chamber having a length to diameter ratio within the range as defined above may result in more efficient mass transfer and fluid distribution within the enclosed chamber of the membrane contactor. The length to diameter ratio of the enclosed chamber may be subject to variation for the purpose of achieving a substantially radial flow pattern within the chamber with the aim of minimizing the incursion of any dead zone. The optimized L/d ratio may range from about 2.5 to about 4.5 for the membrane contactor design.

Advantageously, the membrane contactor as disclosed herein allows the fluid feed flow to pass through the porous distributor cover and across the hollow fiber membranes in a cross-current flow direction toward the perforated tube, while the inlet and outlet ends of the hollow fiber membranes are sealingly separated from the enclosed chamber. This allows for a substantially even distribution of the fluid in the enclosed chamber to avoid or at least reduce the incidence of dead zones in which an uneven region of low concentration of one fluid

(such as air or oxygen) in the fluid mixture builds up within the enclosed chamber. Furthermore, the use of the porous distributor cover allows for a substantially even distribution of the fluid within the enclosed chamber without the use of baffles.

In another embodiment, the fluid feed from the inlet end enters the perforated tube. The fluid feed flow passes through the holes of the perforated tube and across the hollow fiber membranes in a cross-current flow direction outward toward the wall of the enclosed chamber .

Brief Description Of Drawings

The accompanying drawings illustrate a disclosed embodiment and serves to explain the principles of the disclosed embodiment. It is to be understood, however, that the drawings are designed for purposes of illustration only, and not as a definition of the limits of the invention.

Fig. IA shows a cross-sectional side view through a membrane contactor in accordance with one embodiment disclosed herein.

Fig. IB shows a cross-sectional side view through a ^' membrane contactor in accordance with another embodiment disclosed herein.

Fig. 1C shows a cross-sectional side view through a cartridge comprising hollow fiber membranes that may be enclosed within a membrane contactor in accordance with one embodiment disclosed herein. Fig. 2 shows a woven fabric hollow fiber being spirally wound around a perforated tube for use in the membrane contactor of Fig. 1.

Fig. 3A shows a cross-sectional view of a first end cap for use in the membrane contactor of Fig. 1.

Fig. 3B shows a cross-sectional view of at an end of a tube sheet for use in the membrane contactor of Fig. 1.

Fig. 3C shows a perspective view of a first end cap with a plurality of pores for use in the membrane contactor of Fig. 1.

Fig. 3D shows a perspective view of a first end cap with holes disposed on the circumference for use in the membrane contactor of Fig. 1.

Fig. 4A shows a separation system comprising four membranes contactors of Fig. 1 suitable for use in degassing operations.

Fig. 4B shows a separation system comprising four membranes contactors of Fig. 1 suitable^' for use in stripping of volatile organic compounds. Fig. 4C shows a separation system comprising four membranes contactors of Fig. 1 suitable for use in vacuum membrane distillation.

Fig. 5 shows the percentage of oxygen removal (%) as a function of feed flow rate (slpm) for a single membrane contactor of Fig. 1 and a pair of membrane contactors of Fig. 1 in series fluid flow with each other and a prior art membrane contactor not in accordance with the disclosed embodiment.

Fig. 6 shows the pressure drop (bar) across a membrane contactor with respect to feed flow rate (slpm) for a single membrane contactor of Fig. 1 and two membrane contactors of Fig. 1 in series fluid flow with each other and a prior art membrane contactor not in accordance with the disclosed embodiment.

Fig. 7 shows the percentage of oxygen removal (%) as a function of feed flow rate (slpm) for a single membrane contactor of Fig. 1, two membrane contactors of Fig. 1 in series fluid flow with each other at different L/d ratios and a single bundle packed membrane contactor.

Detailed Disclosure of Embodiments

Referring to Fig. IA, there is shown a membrane contactor 10 for de-aerating water. The membrane contactor 10 comprises an enclosed chamber in the form of chamber 12 enclosed by a sidewall in the form of cylinder wall 18, a pair of end cap walls (28' ,30'), which respectively form part of a first tube sheet 28 and a second tube sheet 30 which are at opposite ends of the chamber 12. The membrane contactor 10 further comprises a first end cap 15 and a second end cap 17 that allow fluid to enter and leave the membrane contactor 10, respectively. The hollow fiber membranes 20 are sealingly separated from the enclosed chamber 12 at their inlet ends and outlet ends respectively by first tube sheet 28 and second tube sheet 30. The chamber 12 includes an inlet conduit 14 and an outlet conduit 16 extending through the respective end cap walls (28', 30'), which are sealed to the cylinder wall 18 using O-rings (not shown) .

The membrane contactor 10 also comprises a plurality of selectively permeable hollow fiber membranes 20 axially wound around a perforated tube 34 extending through the enclosed chamber 12. The perforated tube 34 has an array of perforated holes 36 extending through its shell and along the length of the perforated tube 34.

The membrane contactor 10 further comprises a porous distributor cover 22 covering the membranes 20 passing through the enclosed chamber 12 and being disposed between the membranes 20 and the cylinder wall 18 to define fluid feed region in the form of aerated water distributor region 24 therebetween. Region 24 is in fluid communication with the inlet conduit 14. The aerated water is fed into the enclosed chamber 12 via the inlet conduit 14 in the feed inlet flow direction shown by arrow 13. The aerated water is then distributed radially outward in the directions shown by arrows (19a, 19b) toward the region 24 in the directions shown respectively by arrows (19c, 19d) between the cylinder wall 18 and the porous distributor cover 22.

The holes 26 of the cover 22 allow for the distribution of the aerated water evenly along the length of the region 24 (and therefore along the length of the chamber 12) before flowing across the hollow fiber membranes 20.

The hollow fiber membranes 20 are selectively permeable to allow air to pass through the walls of the membranes 20 and into the lumen side thereof. Hence, the fluid conduit 32 is connected to a negative pressure source to form a vacuum in the lumen side of the hollow fiber membranes 20. The vacuum creates a partial pressure difference between the lumen side and the shell side of the hollow fiber membranes 20. This allows for mass transfer across the hollow fiber membranes 20 at its shell side. Accordingly, air which is permeated through the hollow fiber membranes 20 in preference to liquid water can be stripped away from water resulting in the water becoming de-aerated or ^λΛde-gassed" . The air in the lumen side of the hollow fiber membranes 20 leaves the membrane contactor 10 as shown by the arrow 43. Since the air that is removed from the water is not toxic to the environment, this air can be released to the atmosphere without further treatment or purification. It should be noted however that in other applications, such as those involving removal of volatile organics such as toluene from water, the degassed air can be contained within a container for further treatment. The outlet at one end of the perforated tube 34 is sealingly separated from the enclosed chamber 12 by a stopple 38. The stopple 38 is connected to the first tube sheet 28, and one face of the stopple 38 has a female thread 40, which is exposed on the side of the first tube sheet 28 opposite to the chamber 12. The female thread 40 is used to secure the perforated tube 34 within the enclosed chamber 12 by fitting it to the first end cap 15.

The array of holes 26 and perforated holes 36 respectively extending along the porous distributor cover 22 and the perforated tube 34 advantageously promote cross-current flow in the direction as shown by the arrows 42. This ensures an even distribution of the aerated water from the region 24 toward the hollow fiber membranes 20 within the enclosed chamber 12 in the cross- counter direction 42.

The hollow fiber membranes 20 strip the aerated water of air to form de-aerated water. This de-aerated water then flows into the perforated tube 34 by passing through the perforated holes 36 thereon. The de-aerated water can then be collected from the outlet conduit 16 out of the membrane contactor 10 in a direction shown by the arrow 41. In operations when the water is degassed and contains, for example volatiles that cannot be released to the atmosphere and must be collected, the volatiles can be collected from the fluid conduit 32. In another embodiment (not shown) , the plurality of hollow fiber membranes 20 are not embedded in the first tube sheet 28. This may allow for a sweeping gas to pass through the lumen of the hollow fiber membranes 20.

Referring to Fig. IB, there is shown an alternative membrane contactor 10" of Fig. IA. Here, the reference numerals of membrane contactor 10" is similar to that of Fig. IA but with a prime (") symbol. The difference between membrane contactor 10" of Fig. IB and membrane contactor 10 of Fig. IA is the shapes of the first end cap 15" and second end cap 17". The slanted edges of the first end cap 15" may allow the feed fluid to flow along the slanted edges and enter through the holes 26" of the porous distributor cover 22".

Referring to Fig. 1C, there is shown a cartridge 100 that may be disposed within a membrane contactor, such as the membrane contactor 10 of Fig. IA or the membrane contactor 10" of Fig. IB.

The cartridge 100 comprises an enclosed chamber in the form of chamber 112 enclosed by a sidewall in the form of cylinder wall 180, a pair of end cap walls (128' , 130'), which respectively form part of a first tube sheet 128 and a second tube sheet 130 which are at opposite ends of the chamber 112.

The cartridge 100 further comprises a first end cap 150 and a second end cap 170 that allow fluid to enter and leave the cartridge 100, respectively. The hollow fiber membranes 120 are sealingly separated from the enclosed chamber 112 at their inlet and outlet ends respectively by first tube sheet 128 and second tube sheet 130.

The cartridge 100 further comprises a plurality of selectively permeable hollow fiber membranes 120 axially wound around a perforated tube 134 extending through the enclosed chamber 112. The perforated tube 134 has an array of perforated holes (not shown) extending through its shell and along the length of the perforated tube 134. The chamber 112 includes an inlet conduit 114 and an outlet conduit 116 extending through the respective end caps (150,170), which are sealed to the cylinder wall 180 using 0-rings (not shown) . The cylinder side wall 180 has screw threads (102a, 102b, 104a, 104b) at its two ends to mate with corresponding threads on the first end cap 150 and second end cap 170 at their respective ends.

When in use, the hollow fiber membranes 120 can be readily removable from the cartridge 100 by screwing open either one or both of the first end cap 150 and second end cap 170. This allows for the replacement of hollow fiber membranes 120 with ease upon fouling.

As shown in Fig. 2, the hollow fiber membranes 20 are woven into a fabric 60 using warp yarn 64. The woven fabric 60 is then spirally wound around the longitudinal axis 62 of the perforated tube 34 to form a plurality of hollow membrane fibers 20 surrounding the perforated tube 34.

Additional optional features may be included to the design of the membrane contactor 10 to promote the distribution of the fluid feed flow into the region 24.

Referring now to Fig. 3A, there is shown a cross- sectional view of the end of the first end cap 15 which includes four flow distributors 46 obtained along axis 44 of Fig. 1. The flow distributors 46 connect with respective holes (not shown) placed in the cylinder wall 18 of the membrane contactor 10. The flow distributors 46 function to promote even distribution of the aerated water passing through the inlet conduit 14 in the flow direction 13 by forcing the aerated water flow towards the regions between the flow distributors 46 as shown by arrows 19a, 19b. Although four flow distributors 46 are shown in this embodiment, it is to be appreciated that a plurality of flow distributors 46 can be used to provide for more evenly distribution of fluid flow. The number of flow distributors 46 used may depend upon the size of the end cap. In some embodiments, the end cap 15 may contain 3 to 20 flow distributors 46.

Referring to Fig. 3B, there is shown a cross- sectional view of the end of the tube sheet 28, opposite to side wall 28' obtained along axis 44 of Fig. 1. Here, there is provided an alternative embodiment of positioning the flow distributors 48 that function in the same way as the flow distributors 46 of Fig. 3A. The stopple 38 is shown together with a female thread 40. As can be seen from Fig. 3B, a series of flow distributors 48 protrude from the first tube sheet 28 and are placed along the length of the first tube sheet 28. As aerated water enters the inlet conduit 14 as shown by the direction of arrow 13, the aerated water flows along the surface of the stopple 38 and first tube sheet 28. The aerated water is directed to the sides of the first tube sheet 28 and passes into the regions between the flow distributors 48. Therefore, the flow distributors 48 function to assist in distributing aerated water along the length of the region 24.

Although four flow distributors 48 are shown in this embodiment, it is to be appreciated that a plurality of flow distributors 48 can be used to provide for more evenly distribution of fluid flow. The number of flow distributors 48 used may depend upon the size of the end cap. In some embodiments, there may be 3 to 20 flow distributors 48 protruding from and along the length of the first tube sheet 28.

Fig. 3C shows a perspective view of a first end cap 15 with a plurality of pores 86 for use in the membrane contactor 10 of Fig. 1. The plurality of pores 86 disposed through the first end cap 15 allow the feed fluid to be fed evenly through the pores into the enclosed chamber 12. The size of the pores may be in the range of about 1 mm to about 5 mm. In some embodiments, the material of the first end cap 15 of Fig. 3C may be made from polypropylene, unplasticised polyvinyl chloride or acrylonitrile butadiene styrene.

Fig. 3D shows a perspective view of a first end cap 15 with pores 88 disposed on the circumference for use in the membrane contactor of Fig. 1. The plurality of pores 88 disposed on the circumference of the first end cap 15 allows feed fluid to be fed into the region 24 bounded by the porous distributor cover 22.

Accordingly, the uniform distribution of the feed fluid into and through the enclosed chamber 12 is promoted by the end cap 15, porous distributor cover 22 and the perforated tube 34.

There is shown in Fig. 4A, a separation system 70 comprising four membrane contactors (1OA, 1OB, 1OC, 10D) as described above with respect to membrane contactor 10. The separation system 70 of Fig. 4A is used for degassing operations, such as removing air from water. The membrane contactor pairs (1OA, 10C) and (1OB, 10D) are connected in parallel fluid flow with each other and membrane contactor 1OA is in series flow with 1OC and membrane contactor 1OB is in series flow with 10D.

A vacuum pump 72 is connected to the fluid conduits 32 of the membrane contactors (1OA, 1OB, 1OC, 10D) . The fluid conduits 32 being in fluid communication with the outlet ends of hollow fiber membranes 20 as shown in Fig. 1.

When in use, the vacuum pump 72 creates a suction force to remove air that is permeable through the hollow fiber membranes 20 from the aerated water. If there are no toxic substances present in the water source, the air removed from the aerated water can be released to the environment .

The de-aerated water is removed from the separation system 70 via the product line 76.

There is shown in Fig. 4B, a separation system 70' comprising ^' four membrane contactors (10A' ,10B' ,10C ,10D' ). The separation system 70' is similar to that in Fig. 4A and like reference numerals are used to denote the similar units but with a prime symbol ('). The separation system 70' of Fig. 4B is used for stripping of volatile organic compounds from water.

A vacuum pump 72' is connected to the fluid conduits 32' of the membrane contactors (10A', 1OB', 10C, 10D'). The fluid conduits 32' being in fluid communication with the outlet ends of hollow fiber membranes 20 as shown in Fig. 1.

When in use, the vacuum pump 72' creates a suction force to remove air containing volatile organic compounds that are permeable through the hollow fiber membranes 20 from the water source. A capture unit 74 is placed in fluid flow connection to the vacuum pump 72' for containing any volatile organic compounds contained within the air that is extracted by the vacuum pump 72' therein. The stripped volatile organic compounds are either recovered or eliminated by the capture unit 74 before treatment by a volatile recovery system (not shown) . After the vapor is removed from the feed solution, the treated water is recycled back to the shell side of the hollow fiber membranes 20 via a -recycling line 78. The recycled solution can be stored in a storage tank 80 that is in fluid flow communication to a pump 82. The pump 82 pumps the recycled -solution from the storage tank 80 into the membrane contactors (10A'_r 1OB', 10C, 10D') for further separation operations .

The treated water that is not recycled is removed from the separation system 70' via the product line 76' . The separation system by Fig. 4B can be carried out at ambient temperatures of around 25°C.

"Suitable applications of the above separation system can be used to treat water contaminated by halocarbon compounds such as tri-chloroethylene (TCE) , tetrachloroethylene (PCE) or other types of organics such as toluene and chloroform.

There is shown in Fig. 4C, a separation system 70" comprising four membrane contactors

(10A", 1OB", 1OC", 10D") . The separation system 70" is similar to that in Fig. 4A and like reference numerals are used to denote the similar units but with a quotation symbol (") . The separation system 70" of Fig. 4C is used for vacuum membrane distillation operations to concentrate feed solutions. • A feed solution is heated up to about 50⁰C to about 90⁰C by heat exchanger 84. Such feed solutions can be acidic solutions, alkaline solutions, chemical solutions or biomolecular solutions . A vacuum pump 72" is connected to the fluid conduits 32" of the membrane contactors (10A", 1OB",

1OC", 10D") . The fluid conduits 32" being in fluid communication with the outlet ends of hollow fiber membranes 20 as shown in Fig. 1.

When in use, the vacuum pump 72" creates a suction force to remove vapor that is permeable through the hollow fiber membranes 20 from the feed solution. The distilled vapor by vacuum is condensed and collected by capture unit 90 placed in fluid flow connection to the vacuum pump 72".

After the vapor is removed from the feed solution, the resultant feed solution is recycled back to the shell side of the hollow fiber membranes 20 via a recycling line 96. The recycled solution can be stored in a storage tank 92 that is in fluid flow communication to a pump 94. The pump 94 pumps the recycled solution from the storage tank 92 directly through the heat exchanger 84 into the membrane contactors (10A", 1OB", 1OC", 10D") for further separation operations.

The treated feed solution that is not re-cycled is removed from the separation system 70" via the product line 76".

Suitable applications of the above s-eparation system can be used to concentrate ammonia salt at 80⁰C for at least 6 months without fouling or leaking.

The membrane material used in separation system 70" can be polypropylene, polyethylene or polyvinylidene fluoride. It is to be appreciated that the number of membrane contactors 10 in Fig. 4A, Fig. 4B or Fig. 4C is dependent on the scale of the operation, such as for example, industrial scale or experimental scale. Here, only four membrane contactors 10 are shown in the above figures for simplicity but more than four membrane contactors 10 in various configurations (parallel or serial) can be used.

Example

The separation system 70 described above was used to degas aerated water. A woven fabric of hollow fiber membranes made of polypropylene was packed inside the enclosed chamber 12 of the membrane contactors 10. The hollow fiber membranes had the following physical properties:

• Outside diameter = 440 μm;

• Pore size = 0.03 μm;

• Porosity = 40%; and • Total membrane area = 3.7 m².

The degassing operation was carried out at ambient temperature of about 25 ⁰C. The vacuum pump 72 was set at -30 mmHg. The aerated water had an initial oxygen concentration of about 7.0 ppm. Fig. 5 shows the results of the abovementioned degassing operation, namely the percentage of oxygen removal (%) as a function of feed flow rate (slpm) . Curve H' shows the degassing performance of a single membrane contactor made in accordance with the disclosed membrane contactors 10. Curve C shows the dega-ssing performance of a single commercial membrane contactor

(Liqui-Cel® -2.5x8) under the same vacuum condition.

Curve H" shows the degassing performance of two membrane contactors in series fluid flow with each other for the membrane contactors made in accordance with the disclosed membrane contactors 10. Curve C" shows the degassing performance of two membrane -contactors (Liqui-Cel-® 2.5x8) in series fluid flow with each other under the same vacuum condition. Referring to curves H' vs C and H" vs C" in Fig. 5, the percentage of oxygen removal is comparable between the membrane contactor disclosed herein and the commercially available membrane contactor (Liqui-Cel®) . Furthermore, line H' shows that the percentage of oxygen removal can reach over about 80% to about 99% after passing through a single membrane contactor 10 using a water flow ranging from about 1 to about 7 slpm. When two membrane contactors are used in series fluid flow, line H" shows that the percentage of oxygen removal can be improved to 95% to 99% using a water flow ranging from about 1 to about 7 slpm.

Accordingly, a higher fluid feed flow rate ranging from about 4 slpm to about 7 slpm can be used to achieve similar separation effects by passing the fluid feed through two membrane contactors 10 in series fluid flow with each other as compared to a single pass through a single membrane contactor.

Fig. 6 shows the pressure drop (bar) across a membrane contactor with respect to feed flow rate (slpm) for a single membrane contactor and two membrane contactors in series fluid flow with each other for the membrane contactors made in accordance with the disclosed membrane contactors 10 and a commercially availabl-e membrane contactor (Liqui-Cel® 2.5x8). Curves H', C , H" and C" are used to denote the same configuration and type of membrane contactors as described above.

From the results shown in Fig. 6, it can be seen that there is no comparable difference in the pressure drop between membrane contactors made in accordance with the disclosed membrane contactors 10 and commercial membrane contactor (Liqui-Cel® 2.5x8) for operations comprising either a single membrane contactor or two membrane contactors in series fluid flow with each other when conducted under the same experimental conditions .

Accordingly, it is shown that the pressure drop across the membrane contactor 10 made in accordance with the disclosed embodiment is not affected by the porous distributor cover 22.

Moreover, the results in Fig. 5 and Fig. 6 show that the performances of the disclosed membrane contactor 10 are similar to that of the commercial membrane contactor (Liqui-Cel®) . The disclosed membrane contactor 10 differs from the commercial membrane contactor (Liqui- Cel®) in the sense that the disclosed membrane contactor 10 does not contain baffles. Accordingly, the disclosed membrane contactor 10 could be manufactured in a fewer number of steps due to the absence of baffles as compared to the commercial membrane contactor (Liqui-Cel®) and provide substantially the same performance as the commercial membrane contactor (Liqui-Cel®) .

Curve Hl' and Hl" show the relation of the percentage of oxygen removal (%) vs feed flow rate (slpm) of a single membrane contactor 10 of Fig. 1 and two membrane contactors 10 of Fig. 1 in series fluid flow with each other at a L/d ratio of 3.9.

Curve H2' and H2" show the relation of the percentage of oxygen removal (%) vs feed flow rate (slpm) of a single membrane contactor 10 of Fig. 1 and two membrane contactors 10 of Fig. 1 in series fluid flow with each other at a L/d ratio of 5.9. Curves Hl' vs Hl" and H2' vs H2" show that the percentage of oxygen removal is improved when two membrane contactors 10 are used as compared to when a single membrane contactor 10 is used. Curves Hl' vs H2' and Hl" vs H2" show that the percentage of oxygen removal is improved when the L/d ratio is smaller. This is because as the diameter of the membrane contactor 10 increases, more hollow fiber membranes can be packed in the membrane contactor 10, leading to better performance.

Curve H3' shows the relation of the percentage of oxygen removal (%) vs feed flow rate (slpm) of a single bundle-packed module at a L/d ratio of 7.9.

The hollow fiber membranes 20 of curves Hl' , Hl", H2' and H2" are knitted into woven fabric while the hollow fiber membranes 20 of curve H3' are bundled together. Therefore, due to the different configurations of the hollow fiber membranes 20 within the enclosed chamber 12, significant differences in the performance of the respective membrane contactors 10 can be seen. Accordingly, the percentage of oxygen removal (%) in curve H3' is appreciably much lesser than that of the above curves. This is due to the lack of perforation or distribution within the membrane contactor 10 employing bundled hollow fiber membranes 20.

Applications

It will be appreciated that the disclosed membrane contactor can be used for separating one or more fluids from a fluid feed comprising two or more fluids. It will be appreciated that the disclosed membrane contactor can be used for removing dissolved oxygen or carbon dioxide from water.

It will be appreciated that the disclosed membrane contactor can be used for removing volatile organic compound from water.

It will be appreciated that the disclosed membrane contactor can be used for recovering aroma compounds .

It will be appreciated that the disclosed membrane contactor can be used for removing water from an aqueous solution.

It will be appreciated that the disclosed membrane contactor can be used for carrying out vacuum membrane distillation to concentrate solutions. Furthermore, this process may be carried out for at least six months without fouling or leaking.

It will be appreciated that the plurality of hollow fiber membranes can be readily removed from the disclosed membrane contactor. This allows for the easy replacement of the hollow fiber membranes upon fouling. It will be appreciated that the disclosed membrane contactor can be used to enhance mass transfer rates between fluids to be separated.

It will be appreciated that the disclosed membrane contactor can be used for adding a gas to a liquid. It will, be appreciated that the disclosed membrane contactor comprises a distribution porous cover that allows an even distribution of the fluid feed throughout the enclosed chamber. It will be appreciated that the disclosed membrane contactor comprises a distribution porous cover that promotes cross-current flow of the fluid feed across the plurality of hollow fiber membranes. It will be apparent that various other modifications and adaptations of the invention will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the invention and it is intended that all such modifications and adaptations come within the scope of the appended claims .

Claims

1. A membrane contactor comprising: an enclosed chamber having an inlet conduit and outlet conduit extending through at least one chamber sidewall; a plurality of selectively permeable hollow fiber membranes passing through said enclosed chamber for allowing fluid to pass therethrough from an inlet end to an outlet end sealingly separated from said- enclosed chamber; and a porous distributor cover substantially covering said plurality of membranes passing through said chamber and being disposed between said membranes and said at least one chamber sidewall to define a fluid f-eed region therebetween in fluid communication with said enclosed chamber inlet.

2. A membrane contactor according to claim 1 wherein said hollow fiber membrane is a- hydrophobic or hydrophilic microporous polymeric membrane.

3. A membrane contactor according to claim 2 wherein said hollow fiber membrane is non-coated.

4. A membrane contactor according to claim 2 wherein said hollow fiber membrane is coated by one or several types of gas-permeable or gas-selective polymer on its outer surface.

5. A membrane contactor according to claim 2 wherein said hollow fiber membrane is a hydrophobic polymeric membrane .

6. A membrane contactor according to claim 5 wherein said hydrophobic polymeric membrane is selected from the group consisting of polyolefin, polypropylene, polyethylene, polytetrafluoroethylene, polymethylpentene and polyvinylidene fluoride.

7. A membrane contactor according to claim 4 wherein said coating polymer is polydimethylsiloxane.

8. A membrane contactor according to claim 1 wherein the pore size of said hollow fiber membrane is from 0.01 to 0.2 microns or from 0.01 to 0.05 microns.

9. A membrane contactor according to claim 1 wherein the porosity of said hollow fiber membrane is from 20 to

70 per cent or from 30 to 50 percent.

10. A membrane contactor according to claim 1 wherein the outer diameter of said hollow fiber membrane is from 300 to 800 microns or from 400 to 500 microns.

11. A membrane contactor according to claim 1 wherein the thickness of said hollow fiber membrane is from 30 to 80 microns.

12. A membrane contactor according to claim 1 wherein the total surface area of said plurality of membranes is from 0.5 m² to 50 m² or 3 m² to 5 m².

13. A membrane contactor according to claim 1 wherein said porous distributor cover has an array of holes that are substantially evenly distributed along the length of said porous distributor cover.

14. A membrane contactor according to claim 13 wherein the size of said holes is in the range of 0.1 mm to 2 mm.

15. A membrane contactor according to claim 13 wherein the distance between said holes is in the range of 0.1 mm to 1 mm.

16. A membrane contactor according to claim 1 wherein said porous distributor cover is made from a polymer selected from the group consisting of polypropylene, polyethylene and nylon.

17. A membrane contactor according to claim 1 wherein the ends of said porous distributor cover is sealed using a material selected from the group consisting of melt, glue, epoxy and polyurethane resin.

18. A membrane contactor according to claim 1 wherein said plurality of membranes form a woven fabric of hollow fiber membranes.

19. A membrane contactor according to claim 18 wherein said fabric of membranes consists of weft hollow fiber knitted by warp yarn.

20. A membrane contactor according to claim 19 wherein said warp yarn is selected from the group consisting of polypropylene and polyethylene.

21. A membrane contactor according to claim 19 wherein said fabric consists of 3.9 to 19.6 weft aligning fiber per cm of said fabric (10 to 50 weft aligning fiber per inch of said fabric) and 1.5 to 3.9 weft aligning fiber per cm of said fabric (4 to 10 warp yarn per inch of said fabric) .

22. A membrane contactor according to claim 1 wherein said outlet end of said plurality of membranes is in fluid communication with a pressure source.

23. A membrane contactor according to claim 22 wherein said pressure source is a negative pressure to form a vacuum.

24. A membrane contactor according to claim 1 wherein said enclosed chamber outlet conduit comprises a perforated tube extending through said enclosed chamber having an array of perforated holes for receiving fluid from said chamber, and an outlet at one end of said tube that is sealingly separated from said enclosed chamber.

25. A membrane contactor according to claim 24, wherein said tube is surrounded by said plurality of membranes.

26. A membrane contactor according to claim 24 wherein said plurality of membranes are axially wound on the perforated tube.

27. A membrane contactor according to claim 1 further comprising a first tube sheet for coupling said inlet ends of said plurality of membranes.

28. A membrane contactor according to claim 27 further comprising a second tube sheet for coupling said outl-et ends of said plurality of membranes .

29. A membrane contactor according to claim 1 wherein said enclosed chamber has a length to diameter ratio of 2 to 10 or 2.5 to 4.5.

30. A membrane contactor according to claim 1 wherein said inlet conduit is in fluid communication with an end cap to allow flow of fluid therethrough.

31. A membrane contactor according to claim 30 wherein a plurality of flow distributors is disposed on said end cap to assist in directing fluid flow therethrough.

32. A membrane contactor according to claim 31 wherein 3 to 20 flow distributors are disposed on said end cap.

33. A membrane contactor according to claim 30 wherein a plurality of pores is disposed through said end cap.

34. A membrane contactor according to claim 33 wherein the size of said pores is in the range of 1 mm to 5 mm.

35. A membrane contactor according to claim 33 wherein the material of said end cap is selected from the group consisting of polypropylene, unplasticised polyvinyl chloride and acrylonitrile butadiene styrene.

36. A membrane contactor according to claim 1 wherein said chamber comprises a g-enerally longitudinal cylinder housing having two removable end caps at opposite ends thereof.

37. A membrane contactor according to claim 36 wherein said plurality of hollow fiber membranes and said porous distributor cover are mounted on a generally cylindrical cartridge capable of being mounted within said cylinder housing.

38. A membrane contactor according to claim 36 wherein said cylinder housing is removable from the membrane contactor.

39. A system for separating one or more fluids from a mixture of two or more fluids by passing the fluid mixture through a membrane contactor according to claim 1, wherein the outlet ends of said hollow fiber membranes are in fluid communication with a pressure source; wherein in use, said pressure source forms a partial pressure difference between said hollow fiber membranes lumen side and said membranes outer surface for removing one or more fluids selectively permeable through said hollow fiber membranes.

40. A system for degassing a liquid by passing the gas- containing liquid through a separation chamber according to claim 1, wherein the outlet ends of said hollow fiber membranes are in fluid communication with a negative pressure source; wherein in use, said negative pressure source forms a vacuum within said hollow fiber membranes, thereby creating a partial pressure difference between the shell side and lumen side of said hollow fiber membranes for removing the dissolved gas in the liquid flowing therethrough, thereby degassing the liquid.

41. A separation system comprising: a plurality of membrane contactor according to claim 1 in series and/or parallel fluid flow with respect to each other; a vacuum pump in fluid communication with said outlet ends of said hollow fiber membranes; a capture unit in fluid communication with said vacuum pump for containing at least one fluid extracted by said vacuum pump therein; and a storage tank in fluid communication with said outlet conduits of said plurality of membrane contactor to contain fluid product therein, wherein the fluid product can be used directly or recycled into the system for further separation.

42. A separation system according to claim 41, further comprising a heat exchanger in fluid communication with said fluid product for recycling.

43. A method for separating one or more fluids from a fluid feed comprising a mixture of two or more fluids by passing said fluid feed through a membrane contactor according to claim 1.

44. A method for separating one or more fluids from a fluid feed comprising a mixture of two or more fluids comprising the steps of:

(a) passing said fluid feed through an inlet conduit of a membrane contactor comprising an enclosed chamber; (b) distributing said fluid feed to a fluid feed region disposed between a porous distributor cover and at least one chamber sidewall;

(e) removing said fluid product through an outlet conduit of said enclosed chamber.

45. A fluid product as prepared by the method according to claim 44.

46. A method for separating one or more fluids from a fluid feed according to claim 44 wherein step (d) comprises the step of: (dl) passing said fluid product through an array of perforated holes on the body of a perforated tube extending substantially through the length of said enclosed chamber, wherein said perforated tube is axially surrounded by said membranes.

47. A fluid product as prepared by the method according to claim 46.