WO2008045002A1

WO2008045002A1 - Separation unit

Info

Publication number: WO2008045002A1
Application number: PCT/SG2007/000276
Authority: WO
Inventors: Yi Tan
Original assignee: Hyflux Membrane Manufacturing (S) Pte Ltd
Priority date: 2006-10-12
Filing date: 2007-08-24
Publication date: 2008-04-17
Also published as: TW200848142A

Abstract

A separation unit for forming a permeate stream and a retentate stream from a feed stream, wherein at least one of said permeate and retentate streams are enriched with at least one component present within said feed stream, the separation unit comprising: an enclosed chamber having a feed conduit for passage of said feed stream therein, a permeate conduit for passage of said permeate stream therefrom and a retentate conduit for passage of said retentate stream therefrom; and a plurality of removable membrane separation modules disposed within said enclosed chamber, each of said membrane separation modules comprising: a support body capable of being coupled to said enclosed chamber in an operating mode and uncoupled from said enclosed chamber when in an inoperative mode for removal of said separation membrane module from said enclosed chamber; and a plurality of porous ceramic membrane tubes coupled to said support body being in direct fluid communication with said enclosed chamber; wherein in use, at least a portion of said feed stream passes through the walls of said ceramic membrane tubes to form said permeate stream and wherein the remainder of said feed stream passes to said retentate stream.

Description

Separation Unit

Technical Field

The present invention generally relates to a separation unit for separation of ' fluid mixtures and solids suspended in fluid-

Background Separation units comprising ceramic membranes have ^" high resistance to most acidic, alkaline and organic solutions, are reliable and can withstand extreme operation conditions of high temperatures and pressures. Therefore, ceramic membranes are used in a variety of industries such as wastewater treatment, environmental, biotechnology and pharmaceutical, food and beverages, petrochemical and chemical industries to. separate solids, liquids or gases .

Ceramic membranes can either be in the form of plates or tubes. Consequently, they are assembled in enclosed tubular housings which have separate feed conduits, permeate conduits and retentate conduits. A known separation unit consists of an enclosed chamber comprising a plurality of ceramic membrane, tubes that are single tubes or tubes that are multi-channeled. .. Although multi-channel membranes can impart mechanical strength and support due to the large size and

.thickness of the walls, single tubular membranes are preferred and used in enclosed tubular hoμsings.. Single tubular membranes are typically more cost effective and have a better performance as compared to multi-channeled membranes . This is due to the increase in the surface area to volume, ratio of single tubular membranes as compared to multi-channel membranes leading to increased efficiency and permeability of these membranes. However,, due to the rigid connections between single tubular membranes and the enclosed tubular housing, any exposure to mechanical or thermal stresses by the tubular housings are imparted to the single tubular membranes . In

5 addition, any expansion or ■ contraction of the single tubular membranes that occur as a result of changes in the operational temperatures damage the rigidly connected tubular membranes. Therefore, as the tubular membranes are brittle, they can crack or break easily upon such

10 exposures.

Furthermore, as these single tubular membranes are housed in an enclosed tubular housing, they cannot be removed from the. tubular housing. This is particularly problematic when individual tubes need to be removed for 15 servicing or replacement without damaging the rest of the tubular membranes. For example, if there is a breakage in one of the tubes, permeate and retentate will inter-mix and thereby reduce, or completely nullify, the separation efficiency. Hence, because all of the membrane tubes are 20 mounted within the cylinder housing, they cannot be removed or isolated from the feed conduit stream. Hence,- the whole separation unit must be shut down while the tubes are serviced.

There is a need to provide a separation unit that 25 overcomes, or at least ameliorates, one or more of the disadvantages described above.

• There is a need to provide a membrane separation .module that overcomes, or at least ameliorates, one or more of the disadvantages described above. 30.

Summary

According to a first aspeσt, there is provided a separation unit for forming, a permeate stream and a retentate stream from a feed stream, wherein at least one of said permeate and retentate streams are enriched with at least one component present within said feed stream,, the separation unit comprising: an enclosed chamber having a feed conduit for passage of said feed stream therein, a permeate conduit for passage of said permeate stream therefrom and a retentate conduit for passage of said retentate stream therefrom;

^' and a plurality of removable membrane separation modules disposed within said enclosed chamber, each of said membrane separation modules comprising: a support body capable of being coupled to said enclosed chamber in an operating mode and uncoupled from said enclosed chamber when in an inoperative mode for removal of said separation membrane module from said enclosed chamber; and a plurality of porous ceramic membrane tubes coupled to said support body being in direct fluid communication with said enclosed chamber; wherein in use, at least a portion of said feed stream passes through the walls of said ceramic membrane tubes to form said permeate stream and wherein the remainder of said feed stream passes to said retentate stream. According to . a second aspect, there is provided a process for separating a feed stream into a permeate stream and a retentate stream, wherein at least, one of said permeate and retentate streams are enriched with at least one component present within said feed stream, the process comprising the steps of:. passing feed into said enclosed chamber having a plurality of membrane separation modules disposed within said enclosed chamber, each of said membrane, separation modules comprising a plurality of porous ceramic membrane tubes in direct fluid communication with said enclosed chamber; and creating a pressure differential between the enclosed chamber and the bores of said plurality of porous ceramic membrane tubes to thereby pass at least part of said feed stream, from a high pressure side to a low pressure side across the walls of said porous ceramic membrane tubes and thereby form said permeate stream while the remainder of said feed stream on said high pressure side forms said retentate stream.

According to a third aspect, there is provided a fluid separation system for forming a permeate stream and a retentate stream from a feed stream, wherein at least one of said permeate and retentate streams are enriched with at least one component present within said feed stream, said system comprising: a separation unit having an enclosed chamber, a feed conduit for passage of said feed stream therein, a permeate conduit for passage of said permeate stream therefrom and a retentate conduit for passage of said retentate stream therefrom; and a plurality of removable membrane separation modules disposed within said enclosed chamber, each of said membrane separation modules comprising: a support body capable of being coupled to said enclosed chamber in an operating mode and uncoupled from , said enclosed chamber when in an inoperative mode for removal of said membrane separation module from said enclosed chamber; a plurality of porous ceramic membrane tubes coupled to said support body being in direct fluid communication with said enclosed chamber; an inlet chamber disposed at an inlet end of said ceramic membrane tubes for containing fluid therein to feed said ceramic membrane tubes; and an outlet chamber disposed at an outlet end, opposite to said inlet end, of said ceramic membrane tubes for containing fluid therein that has passed through said ceramic membrane tubes; wherein in use, at least a portion of said feed stream passes through the walls of said ceramic membrane tubes to form said permeate stream and wherein the remainder of said feed stream passes to said retentate stream.

According to a fourth aspect, there is provided a membrane separation module for forming a permeate stream and a retentate stream from a feed stream, wherein at least one of said permeate and retentate streams are enriched with at least one component present within said feed stream, the membrane separation module comprising: a support body; a plurality of porous ceramic membrane tubes coupled to said support body and not substantially enclosed by one or more side walls; an inlet chamber disposed at an inlet end of said ceramic membrane tubes for containing fluid therein to feed said ceramic membrane tubes; and an outlet chamber disposed at an outlet end, opposite to said inlet end, of said ceramic membrane tubes for containing fluid therein that has passed through said ceramic membrane tubes; wherein in use, at least a portion of said feed stream passes through the walls of said ceramic membrane tubes to form said permeate stream and wherein the remainder of said feed stream passes to said retentate stream. According to a fifth ^' aspect, there is provided an oil made in a process comprising the step of passing an oil feed containing color contaminants and non-color contaminants into an enclosed chamber having a plurality 5 of membrane separation modules disposed within said enclosed chamber, each of said membrane separation modules comprising a support body and a plurality of porous ceramic membrane tubes in direct fluid communication with said enclosed chamber; and

10. creating a pressure differential between the enclosed chamber and the bores of said plurality of ceramic membrane tubes to thereby pass at least part of said oil feed across the walls of said porous ceramic membrane tubes from a high pressure side to a low pressure side,

15 wherein said high pressure side is in one of the enclosed chamber or the bores of said. tubes while the low pressure side is in the other of said enclosed chamber or the bores of said tubes, and thereby form an oil permeate stream having less color contaminants and non-color contaminants

20 relative to said oil feed while the remainder of said oil feed on said high pressure side forms an oil retentate stream.

In one embodiment, the high pressure side is in- the bores, of said tubes while the low pressure side is in the

25 enclosed chamber.

^■ According to a sixth aspect, there is provided a dewatered organic solvent made in a process comprising the

■ step of passing an organic solvent feed comprising, a mixture of one or more organic solvents miscible with

30 water into an enclosed chamber having a plurality of membrane separation modules disposed within said enclosed chamber, each of ■ said membrane separation modules comprising a support body and a plurality of porous ceramic membrane tubes in direct fluid communication with said enclosed chamber; and creating a pressure differential between the enclosed chamber and the bores of said plurality of ceramic membrane tubes to thereby pass at least part of said organic solvent feed across the walls of said porous ceramic membrane tubes from a high pressure side to a low pressure side, wherein said high pressure side is in one of the enclosed chamber or the bores of said tubes while the low pressure side is in the other of said enclosed chamber or the bores of said tubes and thereby form a permeate stream of water vapor on said low pressure side while the remainder of said organic solvent feed remains on said high pressure side to form an organic solvent retentate stream having less water relative to said organic solvent feed.

In one embodiment, the high pressure side is in the enclosed chamber while the low pressure side is in the bores of said tubes.

Definitxons

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

The terms "feed" and "feed stream" refer to a mixture of fluids or solids suspended in a fluid or mixture of fluids. For example, a feed stream may comprise a mixture of ethanol and water or a feed stream may comprise oil comprising contaminants which may be in fluid form or solid form. The term "permeate fluid", in the context of this specification, is to be interpreted broadly to include any. fluids, liquid or gas, that have passed through the walls of a membrane that is selective for the desired components to be separated. The term "retentate fluid", in the context of this specification, is to be interpreted broadly to include any fluids that have not passed through the walls of a membrane that is selective for the desired components to be separated. It should be noted that the retentate fluid may include solids suspended therein which have not passed through the membrane.

The term "oil", as used herein, is to be 'interpreted broadly to include all kinds of chemical or biological synthetic and mineral oil including crude oil, lubricating oil and fuel oil for a combustion engine, turbine engine, generator and heater, hydraulic transfer oil, edible oil and the like.

The term "used oil" is to be interpreted broadly to include any oil that contains color contaminants and non- color contaminants which can be at least partly removed: to regenerate the oil and permit its re-use.

The term "color contaminants" is to be interpreted broadly to include any non-oil components that cause or promote discoloration of the oil and include, but are not limited to, carbon residue that is a by-product of the combustion process, metal oxides such as iron oxide (ie rust) and degraded or oxidized organic additives present in the oil. The term "non-color contaminants" is to be interpreted broadly to include any non-oil components, such as components which may be present in the oil as byproducts of its use, and which do not affect the color of the oil. For example, where the use of the oil is in a combustion engine, the products may be ash, solid particulates, debris, metal particles, water and compounds that can also cause odor. Exemplary contaminants include metal particles due to wear or corrosion of engines, anti- wear additives, water from engines and storage vessels, dissolved gasoline and gas-oil, solvents, aroraatics and cleaning fluids, external dust, sediments consisting of carbonaceous particles resulting from combustion of motor fuels, polymeric additives for viscosity improvement or sludge dispersion, lead from gasoline and anti-knock additives, anti-oxidant and detergent-dispersing additives. In one embodiment, the main non-color contaminants is ash.

The term "regenerated oil" includes any oil in which contaminants have been removed to such a level that the oil is capable of being re-used, such as oil for use as a lubricant in a combustion engine.

The term "organic solvent" is to be interpreted broadly to include any organic liquid (ie comprising at least one or more of carbon, hydrogen, oxygen, nitrogen and sulfur atoms) that has a carbon backbone and is capable of dissolving solutes that are in the solid, liquid or gaseous phase. Exemplary organic solvents include alcohols, glycols, weak acids, ethers, esters, ketones, aldehydes, amines, nitriles, halogenated hydrocarbons, liquid hydrocarbons and their derivations. One exemplary alcohol solvent,, such as ethanol, has water dissolved therein. Alcohol solvents may include, but are not limited to, methanol, ethanol, propanol, isopropyl alcohol, butanol, pentanol and hexanol.

The term "pressure differential", in the context of this specification, is to be • interpreted broadly to indicate a difference in pressure values when measured across a membrane boundary. The word "substantially" does not exclude "completely" e.g. a composition which is "substantially free" from Y may be completely free from Y. 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 disclosed 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 specificallydisclosed 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, 2₇ 3, 4, 5, and 6.. This applies regardless of the breadth of the range:

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. 1 is a schematic cross-seetional diagram of a separation unit for separation of fluids.

5 Fig. 2 is a perspective view of a membrane separation module used in the separation unit of Fig. 1.

Fig. 3 is a top view of the membrane separation module of Fig. 2.

Fig. 4 is a side cross-sectional view of the membrane 10. separation module of Fig. 2.

Fig. 5 is an enlarged view of region B of Fig. 4.

Fig. 6 is a schematic cross-sectional diagram of a separation unit for pervaporation of fluids.

15 Detailed Disclosure of Embodiments

Exemplary, non-limiting embodiments of a separation unit for separating a feed stream into a permeate stream and a retentate stream,, wherein at least one of said permeate and retentate streams are enriched with at least 20 one component present within said feed stream will now be disclosed.

Fig. 1 is a schematic diagram of a separation unit 100 ^' for separating used oil containing color and non-color contaminants. The separation unit 1.00 includes an enclosed

25 permeate chamber 48 having a feed conduit 4 for passage of a feed stream of used oil into the chamber 48. The chamber 48 also includes five removable membrane separation modules (2A, 2B, 2C, 2D,2E) detachably mounted therein. The separation unit 100 also includes a permeate

30 conduit 8 extending into the chamber 48 for passage of an . oil permeate stream containing a lower weight concentration of contaminants compared to the feed oil entering feed stream conduit 4. The separation unit 100 also includes a retentate conduit 6 for passage of a retentate oil stream from the removable membrane separation modules (2A,2B,2C,2D, 2E) , which contains a higher weight concentration of contaminants relative to the feed oil entering feed stream conduit 4.

Referring now to Fig. 2, there is provided a perspective view of the membrane separation module 2, which is the same as membrane separation modules

(2A,2B,2C,2D,2E) but which, for convenience, will be designated with the numeral "2" . The membrane separation module 2 consists of a plurality of porous ceramic membrane tubes 12 having an inlet end 24 disposed adjacent to, and in direct fluid communication with, an inlet chamber 20 and an outlet end 22 disposed adjacent to, and in direct fluid communication with, an outlet chamber 18.

The module 2. also comprises four support bars

(14A, 14B, 14C, 14D) disposed on the four corners of the module 2 to provide a support for the ceramic membrane tubes 12. In Fig. 2, only three support bars are shown as 14A, 14B and 14C while 14D is at the corner edge adjacent to 14A and 14C but opposite to 14B.. The four support bars

(14A, 14B, 14C, 14D) are disposed between a top cover plate 16A arid a base cover plate l€B. Exemplary methods of manufacturing ceramic membranes are disclosed in United States Patent numbers 6,632,360 and 5,932,;361.

As will be described further below, the top cover plate 16A and base cover plate 16B both have respective holes extending therethrough for receiving the inlet ends and outlet ends of the ceramic membrane tubes 12. The base cover plate 16B is directly connected to the inlet chamber 20 supported by a base cap 52B. The inlet chamber 20 holds the used oil feed therein as it is fed to the plurality of porous ceramic membrane tubes 12. The top cover plate 16A is directly connected to the outlet chamber 18 supported by a top cap 52A for holding fluid to be removed from the porous ceramic membrane tubes 12. Referring to Fig. 3, Fig. 3 shows a top view of the top cover plate 52A with the outlet end 22 of the membrane separation module 2 of Fig. 2.

The base cap 52B and top cap 52A each have respective holes (not shown) extending therethrough and being aligned and dimensioned for passage of the ceramic membrane tubes

12. The base cover plate 16B is attached to the base cap

52B by a number of connections such as nuts and bolts coupling with a flange and specialty o-ring seals (not shown) disposed therebetween for fluid sealing between the base cover plate 16B and the base cap 52B. The top cover plate 16A is also attached to the top cap 52A by a number of connections such as nuts and bolts coupling with a flange and specialty o-ring seals disposed therebetween- for fluid sealing between the top cover plate 16A and the base cap 52A.

The inlet end 24 extends into the inlet chamber 20 to. allow feed fluid to be fed therein and which is connected to the. feed conduit 4. The outlet end 22 extends into the inlet chamber 18 to allow retenta^'te fluid to flow therefrom.

It is to be appreciated that any material may be chosen for the support bars (14A, 14B, 14C, 14D) , top cover plate 16A, top cap 52A, outlet chamber 18, base cover plate 16B, base cap 52B or inlet chamber 20 of the membrane ^• separation module 2 as long as it is strong enough to withstand operation pressure and temperature conditions. In addition, the material chosen should not react with the fluids used. In one embodiment, the material for the support bars (14A, 14B, 14C, 14D) , top cover plate 16A, top cap 52A, outlet chamber 18, base cover plate 16B, base cap 52B and inlet chamber 20 is stainless steel such as 316L stainless steel.

The top cap 52A, top cover plate 16A, base cap 52B and base cover plate 16B are capable of being removed from the membrane separation module 2 by loosening the nuts and bolts coupling. Therefore, individual ceramic membrane tubes 12 that are damaged or fouled can be removed easily from the membrane separation module 12 separately and without contacting with the rest of the ceramic membrane tubes 12. If the tubes are damaged, it is possible to place a blank within the respective holes of the top cap 52A, top cover plate 16A, base cap 52B and base cover plate -16B to prevent flow of permeate fluid from the enclosed permeate chamber 48 to the inlet chamber 20 and outlet chamber 18, and vice versa.

The ceramic membrane tubes 12 of the membrane separation module 2 are not enclosed by any side walls.

Advantageously, the absence of any side walls allows the tubes to be visually inspected while residing in the enclosed permeate chamber 48, which greatly assists maintenance. Also, due to the unobstructed view, the worker is able to insert and align a new ceramic membrane^' tube 12 without damaging the other ceramic membrane tubes

12. This is not possible in conventional membrane modules that are. enclosed in a membrane housing because the enclosed housing prevents the interior of the module from being capable of being visually inspected.

Referring back to. Fig. 1, a feed stream of used oil is pumped • (pump not shown) at speeds of about lms^"1 to 10ms^"1 into the feed conduit 4 of the enclosed permeate chamber 48. The used oil is heated to a temperature in the region of about 30⁰C to about 300⁰C to reduce the viscosity of the used oil so that it is about 20 cSt to about 200 cSt (as measured at 40⁰C) to facilitate its passage through the membrane modules 2. The feed conduit

4 is in fluid communication with the individual inlet chambers • 20 of the membrane separation modules

(2A, 2B,2C,2D,2E) . The feed stream collects in the inlet chambers 20 and the high pressure generated by the pump allows passage of a portion of the feed stream to pass through the walls of the ceramic membrane tubes 12 to form permeate fluid in the enclosed permeate chamber 48. The permeate fluid discharges from the five compartments in the enclosed permeate chamber 48 via permeate fluid conduit 8. The retentate fluid collects in the individual outlet chambers 18 of the membrane separation modules

(2A, 2B,2G,2D, 2E) and discharges via retentate conduit 6.

The ceramic membrane tubes 12 act as filters to prevent, or- at least inhibit, passage of contaminants contained within the oil from reaching the permeate oil located within the enclosed permeate chamber 48.

As discussed above, the ceramic membrane tubes 12 are not enclosed within side walls in the membrane separation modules (2A,2B,2C, 2D,2E) . Advantageously, this results in the discharge of permeate fluid directly into the enclosed permeate chamber 48. The modular design of the modules 2 allows a number of modules 2 to be mounted within the enclosed permeate chamber 48 to allow them to be selectively removed or taken off-line should they malfunction. This reduces the operating downtime of the membrane separation module 2.

The enclosed permeate chamber 48 also includes four baffle plates 10 that are individually located between adjacent membrane separation modules (2A, 2B, 2C, 2D, 2E) .

The baffle plates 10 function as. partitions to separate the enclosed permeate chamber 48 into compartments that bind the membrane separation modules (2A, 2B,2C,2D,2E) .

5 This allows individual membrane separation modules

(2A, 2B, 2C,2D,2E) to be removed if needed without interfering with the separation process. A series of access holes (not shown) extend through the top cover of the enclosed permeate chamber 48 and are located directly0 above the individual membrane separation modules (2A, 2B>2C,2D,2E) . The access holes are each covered with

, an access door to allow the modules to be individually removed from the enclosed permeate chamber 48, typically via a hand-operated crane. Furthermore* the side walls of5 the enclosed permeate chamber 48 may also include inspection holes covered with a thermally resistant glass plate (not shown) to allow inspection of the membrane modules in use. by operators of the membrane separation unit 100. .This allows operators to visually inspect the 0 ceramic membrane tubes 12 of each membrane module (2A_r2B,2C,2D,2E) and determine if they need to be isolated and taken off line in the event of failure (ie such as rupture of the ceramic membrane tube walls) .

A number of membrane . holders (not shown)5 corresponding to the number of membrane separation modules

(2A,2B,2C,2D,2E) are attached to the base of the enclosed permeate chamber 48. Advantageously, the membrane holders allow, the membrane separation modules (2A,2B,2C,2D, 2E) to be attached to or removed from the enclosed permeate 0 chamber 48 as required. An attachment means such as a clamp and clip locking arrangement is provided on the membrane holders which clamp the support bars

(14A, 14B,14C,14D) so that the membrane separation modules

(2A,2B,2C,2D,2E) are securely fastened to the enclosed permeate chamber 48. In other embodiments, the membrane holder can be a hole disposed on the base of the enclosed permeate chamber 48 with dimensions corresponding to the exterior length and width of the inlet chamber 20 of each membrane separation modules <2A,2B, 20,2D, 2E) . In other embodiments, the membrane separation modules

(2A, 2B,2C,2D,2E) are attached to the- membrane holder using a nuts and bolts configuration.

A plurality of valves (not shown in Fig. 1) are disposed between the feed conduit 4 and the. feed stream to the individual membrane separation modules

(2A,2B,2C,2D, 2E) as well as between the retentate conduit

6 and the retentate stream from the individual membrane separation modules (2A, 2B₁.2C, 2D, 2E) . A plurality of valves are also disposed between the individual permeate outlet of each compartment and the permeate conduit 8.

Advantageously, the valves act to separate the individual membrane separation modules (2A,2B, 2C, 2D, 2E) from the feed stream, retentate stream and permeate conduit 8 so that individual membrane separation modules (2A, 2B, 2C, 2D, 2E) can be removed as needed from the enclosed permeate chamber 48 without disruption to the process.

It is to be appreciated that more than^' one feed conduit 4 can be connected to membrane separation modules (2A, 2B,2C,2D,2E) such that the feed fluid in each membrane ' separation modules (2A, 2B, 2C,2D, 2E) may be different. Subsequently, more than one retentate conduit ^'6 can extend from membrane separation modules (2A, 2B,2C,2D, 2E) . Advantageously, this may result in a desired mixture of permeate fluid in the enclosed permeate chamber 48 without the need for an additional mixing .unit.

In use, as the used oil feed is pumped into the inlet chamber 20, the high pressure created forces part of the used oil feed though the walls of the ceramic membrane tubes 12 such that a permeate oil stream containing less color contaminants and non-color contaminants as compared to the feed stream collects in the enclosed permeate chamber 48. This oil is known as Regenerated oil' and can be re-used. Any contaminants present in the oil feed that are bigger than the pore size of the ceramic membrane ^• will not be able to pass through the ceramic membrane tubes 12 and hence collects in the outlet chamber 18 with the remainder of the used oil feed that did not permeate through. the ceramic membrane tubes 12 for removal via the retentate conduit 6. The retentate fluid is then disposed or recycled back to the separation unit 100 for further processing. Fig. 4 shows a side cross-sectional view of the membrane separation module 2 of Fig. 2. It can be seen that both the top cover plate 16A and base cover plate 16B have a plurality of openings that allow the inlet and outlet ends of the plurality of ceramic membrane tubes 12 to extend and slot into.

Fig. 5 shows the enlarged view of region B of Fig. 4. The ceramic membrane tube 12 is not in direct contact with the top cover plate 16A. Instead, the ceramic^' membrane tube 12 is indirectly connected to the top cover plate 16A through a number of connections such as screw sleeve gasket 26, O-rings (28A, 28B), washers (3OA, 30B) and rubber washers (32A, 32B) . The ceramic membrane tube 12 is fixed to the .top cover plate 16A using O-rings (28A, 28B) by tightening the screw sleeve gasket 26 through washers (3OA, 30B) . The O-rings (28A, 2.8B) and rubber washers (32A, 32B) are in direct contact and mounted on the top cover plate 16A to ensure that the ceramic membrane tube 12 is not in direct connection with the top cover plate 16A. Advantageously, these sealing means ensure that any damage incurred by the ceramic membrane tubes 12 is minimized because any thermal or mechanical disruption or shock that is applied to the top cap 52A or top cover plate 16A is not transmitted to the ceramic membrane tubes 12. Furthermore, the sealing means provide enough flexibility to the ceramic membrane tubes 12 to release stress that is caused by thermal expansion or contraction. The individual ceramic membrane tubes 12 are also attached to the base cover plate 16B and base cap 52B through a number of similar connections such as screw sleeve gasket, O-rings, washers and rubber washers.

The connections., in particular, the O-rings (28A, 28B) and rubber washers (32A, 32B) mounted on the top cover plate 16A, prevent any flow of fluid from the outlet chamber 18 to the enclosed permeate chamber 48 of Fig. 1. Consequently, any retentate fluid from the ceramic membrane tube 12 passes directly into the retentate fluid chamber 18 and discharges via outlet end 22. The same principle applies to the bottom of the ceramic membrane tube 12 whereby the feed fluid in the inlet chamber 20 passes directly into the ceramic membrane tube 12. Advantageously, this results in negligible contamination of permeate fluid with the feed fluid or retentate fluid. Fig. 6. shows a similar separation unit 100' of Fig. 1 but used for pervaporation. The components of the separation unit 100' are denoted by the same reference numerals but with a prime symbol C). Pervaporation is a process whereby permeation through a membrane module is accompanied by a phase change such that a permeate vapor is formed. This occurs because the operating conditions are such that the permeate fluid is volatile and hence forms a vapor after it is separated from a feed stream. In Fig. 6, a feed stream of a mixture of fluids, such as ethanol and water, is fed via feed conduit 34 to an enclosed feed chamber 50 at ambient, pressure. The absence of side walls in the membrane separation module 2 allows the mixture of ethanol and water in the enclosed feed chamber 50 to be directly exposed to the porous ceramic membrane tubes 12 such that water that has permeated through the walls of the porous ceramic membrane tubes 12 forms in the bores of the ceramic membrane tubes 12 as water vapor. The remainder of the mixture of ethanol and water that has not passed through the walls of the porous ceramic membrane tubes 12 forms the retentate fluid. The retentate fluid discharges from the enclosed feed chamber 50 via retentate conduit 36. Gas conduit 56 allows passage of gas into the inlet chambers 20 of the membrane separation modules (2A, 2B, 2C, 2D, 2E).. Permeate . conduit 40 allows passage of gas from the outlet chambers 18 of the membrane separation modules (2A, 2B, 2C, 2D, 2E) . The gas that exits the membrane separation modules (2A,.2B,2C,2D,2E) is a mixture of gas that enters via gas conduit 56 and water vapor.

An inert atmosphere or vacuum is generated in the bores of each ceramic membrane tube 12. leading to a lower vapor partial pressure of the permeate phase in the bores as compared to the vapor partial pressure in the enclosed feed chamber 50 so that a pressure difference is generated at- the membrane boundary. This leads to preferential permeation of a fluid, such as water, across the membrane boundary. As water preferentially adsorbs onto the membrane surface and diffuses through the membrane boundary driven by the difference in vapor pressure, a phase change occurs. The water vapor that forms passes through the permeate conduit 40 to a tank 42 which is chilled to allow the condensation of the water vapor into water in the liquid phase..

In one embodiment, the feed stream is a mixture of at least one organic solvent and water . Exemplary organic 5. solvents in a solution with water that can undergo pervaporation are disclosed in "Performance evaluation of microporous inorganic membranes in the dehydration of industrial solvents" by S. Sommer and T. Melin, Chemical Engineering and Processing, 44 (2005) , pages 1138 to 1156.0 Some exemplary organic solvents include alcohols, glycols, weak acids, ethers, esters, ketones, aldehydes,, amines, nitriles, halogenated hydrocarbons, liquid hydrocarbons and their derivations. The organic solvents are miscible, or at least partially miscible, with water. 5 A region of low pressure relative to. the enclosed chamber 50 is generated . in the bores of the ceramic membrane tubes 12 by either sweeping an inert gas, such as nitrogen, through the bores via gas conduit 56 and permeate conduit 40 or by creating a vacuum in the bores0 of the ceramic membrane tubes 12. . In Fig. 6, a vacuum pump 44 is connected to tank 42 to create a vacuum, or at least a partial vacuum, in the bores of the ceramic membrane tubes 12.

In Fig. 6_r four baffle plates 10 are located in the5 enclosed feed chamber 50 between adjacent membrane separation modules (2A, 2B,2C,2D,2E) to . form five compartments. The baffle plates 10 function to direct the flow of feed stream that enters the enclosed feed chamber

50 via the feed conduit 34. Therefore, the retentate0 fluid becomes more concentrated in the fluid that does not permeate into the bores of the ceramic membrane tubes 12 as the retentate fluid moves across the enclosed feed chamber 50 from one. membrane separation module . to the next. The arrows (54A, 54B, 54C, 54D) denote the movement of the retentate fluid across the enclosed feed chamber 50 from left to right. The retentate fluid leaves the enclosed feed chamber 50 via the retentate conduit 36. In one embodiment, the feed stream is a mixture of 95 wt% ethanol and 5 wt% water. The feed mixture of ethanol and water is introduced into the enclosed feed chamber 50 at ambient pressures and temperature. A partial vacuum is introduced into the bores of the ceramic membrane tubes 12 by the action of the vacuum pump 44. The ceramic membrane tubes 12 are made from zeolite A type crystals and aluminosilicates. Water from the feed mixture is preferentially adsorbed onto the ceramic membrane tubes 12 and permeates into the bores of the ceramic membrane tubes 12. Due to the partial vacuum created in the bores, water in the liquid phase undergoes a phase change to form water vapor. As water is removed from the feed mixture, the concentration of ethanol in the feed mixtures increases. Therefore, as the feed mixture moves across the enclosed feed chamber. 50 from left to right as denoted by the arrows (54A, 54B, 54C, 54D) , the concentration of ethanol in

• the feed mixture increases and the retentate fluid, made up of 99.5 wt% of ethanol, discharges from the enclosed feed chamber 50 via the retentate conduit 36. Water vapor. discharges via the permeate conduit 40 and condenses to form water (liquid) in cooling tank 4.2.

Applications

The disclosed membrane separation modules are individually connected to the feed conduit and therefore can be individually isolated from the other membrane separation modules. Furthermore, the tubes of the membrane separation modules are in direct fluid communication with the chamber, it is possibly to produce permeate fluid directly in the chamber or, in other embodiments, feed fluid from the chamber into the tubes of the modules. Hence, if one module breaks down, the separation unit can still function.

The disclosed membrane separation modules are removable and therefore can be removed from the chamber and replaced if necessary. This facilitates maintenance and reduces operating downtime. The membrane separation modules disclosed herein may be used to separate components from fluids. Moreover, they may be used to separate fluids from a mixture of fluids. For example, a gas may be separated from a mixture of gases or from a mixture of liquids. The membrane separation modules disclosed herein may be cost effective and may be easy to manufacture and assemble. Membrane installation may be employed on a large, scale at a low cost.

The membrane separation modules disclosed herein may be packed into a large chamber to carry out large scale, production of permeate fluid.

The membrane separation modules disclosed herein may be taken apart easily so that maintenance or repair of broken or cracked ceramic membrane tubes may be carried out conveniently without damaging the rest of the ceramic membrane tubes .

The ceramic membrane tubes are not directly connected to the membrane separation ^• modules and so, may not experience thermal or mechanical stresses or shock. Furthermore, the ceramic membrane tubes may expand or contract without damage.

The separation unit and ceramic membrane module can be easily integrated into various chemical processes. For example, these processes include membrane reactors for wastewater treatment, chemical, gas or biological reactions; membrane evaporation or distillation for desalination or purification of chemical fluids; membrane clarification for fermentation broth, beverage, dairy and pharmaceutical stream or solutions, catalyst recovery or recycling processes, etc.

It will be apparent that various other modifications and adaptations of the invention such as shape, dimensions, adapters, connections, configurations, etc. 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 separation unit for forming a permeate stream and a retentate stream from a feed stream, wherein at least one of said permeate and retentate streams ^• are enriched with at least one component present within said feed stream, the separation unit comprising: an enclosed chamber having a feed conduit for passage of said feed stream therein, a permeate conduit for passage of said permeate stream therefrom and a retentate conduit for passage of said retentate stream therefrom; and a plurality of removable membrane separation modules disposed within said enclosed chamber, each of said membrane separation modules comprising: a support body capable of being coupled to said enclosed chamber in an operating mode and uncoupled from said enclosed chamber when in an inoperative mode for removal of said separation membrane module from said. enclosed chamber; and a plurality of porous ceramic membrane tubes coupled to said support body being in direct fluid communication with said enclosed chamber; . wherein in use, at least a portion of said feed stream passes through the walls of said ceramic membrane tubes to form said permeate stream and wherein the remainder of said feed •stream passes to said retentate stream. -

2. A separation unit as claimed in claim 1, comprising an inlet chamber disposed at an inlet end of said ceramic membrane tubes for containing fluid therein to feed said ceramic membrane tubes .

3. A separation unit as claimed in claim 2, comprising an outlet chamber disposed at an outlet end, opposite to said inlet end> of said ceramic membrane tubes for containing fluid therein that has passed through said ceramic membrane tubes.

4. A separation unit as claimed in claim 1, comprising a pressure conduit in fluid communication with said ceramic membrane tubes for creating a pressure differential, across the walls of said ceramic membrane tubes.

5. A separation unit as claimed in claim 3, wherein each membrane separation module comprises an isolation means for isolating fluid flow into said inlet chamber or isolating fluid flow out of said outlet chamber.

6. A separation unit as claimed in claim 1, wherein said separation unit has one or more access cover plates adjacent to at least one or more of said membrane separation modules.

7. A separation unit as claimed in. claim 7, wherein said access cover plates are disposed, on the top of said enclosed chamber-.

8. A separation unit as claimed in claim 1, comprising a- plurality of membrane separation module holders attached to said enclosed chamber for holding said membrane separation modules during said operating mode.

9. A separation unit as claimed in claim 8, wherein said support body of each membrane separation module comprises attachment means for attachment to corresponding attachment means provided on said membrane module holders .

10. A separation unit as claimed in claim 1, wherein each of said membrane separation modules comprises at least one cover plate' having the plurality of porous ceramic membrane tubes extending therethrough for. supporting said porous ceramic membrane tubes.

11. A separation unit as claimed in claim 10, wherein a base cover plate is disposed adjacent to the inlet end of said plurality of porous ceramic membrane tubes.

12. A separation unit as claimed in claim 10, wherein a top cover plate is disposed adjacent to the outlet end of said plurality of porous ceramic membrane tubes .

13. A separation unit as claimed in claim 10, comprising a sealing means disposed between said porous ceramic membrane tubes and said cover plate.

14. A separation unit as claimed in claim 1, comprising one or more baffles disposed within said enclosed permeate chamber.

15. A separation unit as claimed in claim 14,. wherein a plurality of baffles are disposed within said enclosed permeate chamber between adjacent • membrane separation modules.

16. A separation unit as claimed in claim 15, wherein an isolation means is disposed adjacent to said plurality of baffles for isolating fluid flow out of said separation unit.

17. A separation unit as claimed in claim 1, wherein the support body comprises support bars extending between the inlet chamber and the outlet chamber.

18. A process for separating a feed stream into a permeate stream and a retentate stream, wherein at least one of said permeate and retentate streams are enriched with at least one component present within said feed stream, the process comprising the steps of: passing feed into said enclosed chamber having a plurality of membrane separation modules disposed within said enclosed chamber, each of said membrane separation modules comprising a plurality of porous ceramic membrane tubes in direct fluid communication with said enclosed chamber; and creating a pressure differential between the enclosed chamber and the bores of said plurality of porous ceramic membrane tubes to thereby pass at least part of said feed stream from a high pressure side to a low pressure side across the walls of said porous ceramic membrane tubes and thereby form said permeate stream while the remainder of said feed stream oh said high pressure side forms said retentate stream.

19. A process as claimed in claim 18, wherein said creating step comprises the step of: forming said high pressure side in the bores of said porous ceramic membrane tubes.

20. A process as claimed in claim 18, wherein said creating step comprises the step of: forming said high pressure side in the enclosed chamber.

21. A process as claimed in .claim 18, wherein said creating step comprises the step of: creating at least a partial vacuum on said low pressure side.

22. A process as claimed in claim 21, wherein said vacuum is located within said bores of said porous ceramic membrane tubes.

23. A process as claimed in claim 18, comprising the step of: passing inert gas into said low pressure side.

24. A process as claimed in claim 18, comprising the step of: passing said feed stream into said enclosed chamber to form said permeate stream in the bores of said plurality of porous ceramic membrane tubes .

25. A process as claimed in claim 18, comprising the step of: passing said feed stream into the bores of said plurality of porous ceramic membrane tubes to form said permeate stream in the enclosed chamber.

26. A process as claimed in claim 18, comprising the step of; providing one or more baffles within said enclosed chamber to direct flow of fluid therein.

27. A process as claimed in claim 26, wherein said baffle ^• is provided between adjacently disposed membrane separation modules.

28. A process as claimed in claim 18, comprising the step oft independently isolating one or more of said membrane separation modules from fluid flow, to prevent production of said permeate stream therefrom.

29. A process as claimed in claim 18, wherein said feed stream is in the liquid phase.

30. A process as claimed in. claim 29, wherein said liquid phase feed stream comprises a mixture of one or more organic solvents miscible with water.

31. A process as claimed in claim 29, wherein said feed stream of organic solvents miscible with water is fed to said enclosed chamber to form said permeate stream within the bores of said porous ceramic membrane tubes.

32. A process as claimed in claim 31, wherein said permeate stream is in the vapor phase.

33. A process as claimed in claim 32, comprising the step of condensing said vapor permeate stream to form a liquid permeate stream.

34. A process as claimed in claim 29, wherein said organic solvent is an alcohol.

35. A process as claimed in claim 34, wherein said alcohol is ethanol.

36. A process as claimed in claim 29, wherein said liquid phase feed stream comprises an oil containing one or more contaminants therein.

37. A process as claimed in claim 36, wherein said oil contaminants comprise at least one of color contaminants and non-color contaminants.

38. A process as claimed in claim 36, comprising the step of: feeding said oil to the bores of said porous ceramic membrane tubes to form said permeate stream in said enclosed chamber.

39.. A fluid separation system for forming a permeate stream and a retentate stream from a feed stream, •• wherein at least one of said permeate and retentate streams are enriched with at least one component present within said feed stream, said system comprising: a separation unit having an enclosed chamber, a feed conduit for passage of said feed stream therein,- a permeate conduit for passage of said permeate stream therefrom and a retentate conduit for passage of said retentate stream therefrom; and a plurality of removable membrane separation modules disposed within said enclosed chamber, each of said ^• membrane separation modules comprising: a- support body capable of being coupled to said enclosed chamber in an operating mode and uncoupled from said enclosed chamber when in an inoperative mode for removal of said membrane separation module from said enclosed chamber; a plurality of porous ceramic membrane tubes coupled to said support body being in direct fluid communication with said enclosed chamber; an inlet chamber disposed at an inlet end of said ceramic membrane tubes for containing fluid therein to feed said ceramic membrane tubes; and an outlet chamber disposed at an outlet end, opposite to said inlet end, of said ceramic membrane tubes for containing fluid therein that has passed through said ceramic membrane tubes; wherein in use, at least a portion of said feed stream passes through the walls of said ceramic membrane tubes to form said permeate stream and wherein the remainder of said feed stream passes to said retentate stream.

40.. A membrane separation module for forming a permeate stream and a retentate stream from a feed stream, wherein at least one of said permeate and retentate streams are enriched with at least one component present within said feed stream, the membrane separation module comprising: a support body; a plurality of porous ceramic membrane tubes coupled to said support body and not substantially enclosed by one or more side walls; an inlet chamber disposed at an inlet end of said ceramic membrane tubes for containing fluid therein to feed said ceramic membrane tubes; and an outlet chamber disposed at an outlet end, opposite to said inlet end, of said ceramic membrane tubes, for containing fluid therein that has passed through said ceramic membrane tubes; wherein in use, at least a portion of said feed stream passes through the walls of said ceramic membrane tubes to form said permeate stream and wherein the remainder of said feed stream passes to said retentate stream.

41. An oil made in a process, comprising the step of passing an oil feed containing color contaminants and non-color contaminants into an enclosed chamber having a plurality of membrane separation. modules disposed within said enclosed chamber, each of said membrane separation modules comprising a support body and a plurality of porous ceramic membrane tubes in direct fluid communication with said enclosed chamber; and creating a pressure differential between the enclosed chamber and the bores of said plurality of ceramic membrane tubes to thereby pass at least part of said oil feed across the walls of said porous ceramic membrane tubes from a high pressure side to a low pressure side, wherein said high pressure side is in one of the enclosed chamber or the bores of said tubes while the low pressure side is in the other of said enclosed chamber or 5 the bores of said tubes, and thereby form an oil permeate stream having less color contaminants and non-color contaminants relative to said oil feed while the remainder of said oil feed on said high pressure side forms an oil retentate stream.

10

42. A dewatered organic solvent made in a process comprising the step of passing an organic solvent feed comprising a mixture of one or more organic solvents miscible with water into an enclosed

15 chamber having a plurality of membrane separation modules disposed within said enclosed chamber, each of said membrane separation modules comprising a support body and a plurality of porous ceramic membrane tubes in direct fluid

2.0 communication with said enclosed chamber; and creating a pressure differential between the enclosed chamber and the bores of said plurality of ceramic membrane tubes to thereby pass at. least part of said organic solvent feed across the walls

25 of said porous ceramic membrane tubes from a high pressure side to a low pressure side, wherein said high pressure side is in one of the enclosed chamber or the bores of said tubes while the low ^• pressure side is in the other of said enclosed

30 chamber or the bores of said tubes and thereby form a permeate stream of water vapor on said low pressure side while the remainder of said organic solvent feed remains on said high pressure side to form an organic solvent retentate stream having less water relative to said organic solvent feed.