AU2008267751B2

AU2008267751B2 - Selective removal of a target liquid constituent from a multi-component liquid

Info

Publication number: AU2008267751B2
Application number: AU2008267751A
Authority: AU
Inventors: Hayden John Stein
Original assignee: GOMTECH Pty Ltd
Current assignee: GOMTECH Pty Ltd
Priority date: 2007-06-22
Filing date: 2008-06-20
Publication date: 2013-07-18
Anticipated expiration: 2028-06-20
Also published as: AU2008267751A1; WO2009000019A1

Abstract

A process and apparatus for selectively removing a target liquid constituent from a multi-component liquid is described. The process comprises the steps of: a) heating the multi-component liquid in a chamber to a temperature at which the target liquid constituent selectively evaporates to form a vapor rich in the target liquid constituent; b) bubbling a carrier gas through the multi-component liquid of step a); c) continuously removing a gas/vapor mixture from the chamber, the gas/vapor mixture comprising the vapor from step a) and the carrier gas from step b); d) condensing the gas/vapor mixture of step c) in a condenser to form a condensate rich in the target liquid constituent and thereby liberate the carrier gas from the gas/vapor mixture; and, e) returning the carrier gas from step d) for use in step b).

Description

WO 2009/000019 PCT/AU2008/000890 SELECTIVE REMOVAL OF A TARGET LIQUID CONSTITUENT FROM A MULTI COMPONENT LIQUID 5 FIELD OF THE INVENTION The present invention relates to the selective removal of a target liquid constituent from a multi-component liquid using an evaporative separation process. The present invention relates specifically, though not exclusively to the purification and reclamation of a target 10 liquid constituent of various types from multi-component liquids which are contaminated with both solid and liquid contaminants. BACKGROUND TO THE INVENTION 15 In urban areas where climate change and reduced rainfall over catchment areas has threatened long-term water security, using reclaimed water for indirect potable use is considered to be superior to other water supply augmentation methods. The term "wastewater" as used in this specification refers to any water which has been adversely affected in quality by human activities as opposed to water that comes from natural 20 environments without human influence. Wastewater includes liquid waste from domestic residences or commercial properties including sewerage and grey water, as well as liquid waste from industry or agriculture. As such wastewater can have a wide range of potential contaminants having a wide range of concentrations. For example, industrial wastewater may be contaminated with silt, sand, suspended particles of organic materials, alkalis, acids, 25 grease, oils, chemicals, surfactants, parasites, dyes, detergents, algae, fungi, biocides, herbicides, pesticides, slimes, bacteria, poisons, cyanide, thiocyanates, thiosulphates, ammonia, hydrogen sulphide, calcium, magnesium, silica, lead, copper, chrome, caustic or alumina. 30 Disposal of wastewater from an industrial plant is a difficult and costly problem. Most petroleum refineries, chemical and petrochemical plants and most mining operations have onsite facilities to treat their wastewater to comply with the local and/or national regulations regarding disposal of wastewater into community treatment plants or into rivers, lakes or oceans. Treated wastewater can be released into the environment or reused as drinking 35 water, used as process water in industry, or used in artificial recharge of aquifers or in agriculture.

WO 2009/000019 PCT/AU2008/000890 -2 Numerous processes are available in the prior art for cleaning up wastewater, depending on the type and extent of contamination. Such processes typically rely on a combination of physical, chemical and biological treatment processes. The highest quality reclaimed water is produced using reverse osmosis or other membrane filtration techniques. Other 5 processes include the use of filtration through activated carbon, clarification, sedimentation, disinfection, deionization, ion exchange, boiling, and distillation. The choice of method will depend on the quality of the water being treated, the cost of the treatment process and the quality standards expected of the processed water. 10 The impact of climate change on rainfall in Australia has led to an increase in interest in reclaiming fresh water from seawater. Desalination is a process whereby excess dissolved salt is removed from salty water such as brine, seawater, saline water or brackish water to obtain fresh water, optionally with salt as a by-product. Depending on quality, the water can be used as human or animal drinking water or for agricultural irrigation. Desalination plants 15 exist in the prior art. Such prior art desalination plants use distillation processes such as multi-stage flash distillation, membrane process such as reverse osmosis, freezing processes or crystallization processes. Multi-stage flash distillation is a prior art desalination process in which seawater is heated to flash water into steam in multiple stages. The steam is condensed on tubes of heat exchangers that run through each stage. 20 Vacuum distillation is a process by which salty water is boiled at a pressure below atmospheric pressure, the reduction in pressure being used to lower the temperature at which the water boils. Reverse osmosis desalination plants use high pressures to force seawater through a semi-permeable membrane that retains salt ions on one side and allows pure water to pass through to the other side. These processes are very energy intensive, 25 raising the cost of the water recovered from the salty water. The energy requirements of reverse osmosis can lead to an increase in harmful greenhouse gas emissions. Desalination is particularly expensive in places far from the sea. The costs include infrastructure costs, transportation cots, and the costs associated with the disposal of brine or salt. 30 Oil contamination of is the primary cause of wear and engine failure and the main reason why oil has to be changed. However, it is widely acknowledged that oil does not "wear out" mechanically, meaning that oil can be used over and over again, and still perform as new, as long as it is contaminant-free. In use, oil becomes contaminated by solid contaminants such as dirt, dust, bacteria, carbon from combustion and other foreign matter, and liquid 35 contaminants such as water and acids, which adversely affect the properties of the oil.

WO 2009/000019 PCT/AU2008/000890 -3 Many systems have been utilized in an attempt to purify and reclaim clean oil from waste oil. Typically, such prior art systems include filtration units to remove solid contaminants. Such filtration units are generally satisfactory but require additional equipment and transfer or handling operations. The liquid contaminants are generally more difficult to remove. For 5 example, a large number of processes have been developed to remove water from oil. Water present in the oil is typically removed using a dewatering process which relies on gravity separation of free water from oil in settling tanks. Separation of the remaining liquid contaminants is typically achieved using distillation systems to separate the liquid contaminants based on differences in boiling points. 10 WO 2001/007134 describes a continuous contacting apparatus for separating a liquid component from a liquid mixture. The apparatus comprises an evaporation chamber having first and second ends, an inlet and an outlet for a carrier gas, and an inlet and an outlet for a liquid mixture. The inlet for the liquid mixture and the outlet of the carrier gas are located on 15 the first end of the evaporation chamber. The apparatus further comprises a dew-formation chamber having an inlet and an outlet for a carrier gas and an outlet for the separable liquid component, wherein the inlet for the carrier gas of the dew-formation chamber is situated in a countercurrent manner to the inlet for the carrier gas of the evaporation chamber. A common heat transfer wall provides thermal communication between the evaporation 20 chamber and the dew-formation chamber. A feeding device is included for providing the liquid mixture onto the evaporation side of the heat transfer wall. An air mover is used for controlling a flow of a carrier gas through the chambers, wherein the gas flow in the evaporation chamber is countercurrent to the gas flow in the dew-formation chamber. A heating apparatus is provided for heating the carrier gas from the outlet of the evaporation 25 chamber, wherein the heated carrier gas is directed to flow into the inlet of the dew-formation chamber. Also described is a process for separating a liquid component from a liquid mixture in a continuous contacting manner comprising employing such an apparatus for such separation. This process in inefficient as it relies on heating of the carrier gas to heat the liquid mixture. 30 JP 61025602 describes a feed liquid being atomized from a nozzle before being brought into contact with a carrier gas from a passage and evaporated. Unevaporated mist is separated in a mist separator and then fed back to a feed liquid tank. The carrier gas containing the vapor is expanded adiabatically in a turbine, cooled to condense the vapor, which is 35 recovered in a mist separator. The carrier gas is then compressed adiabatically in a turbine WO 2009/000019 PCT/AU2008/000890 -4 to elevate the temperature and circulated. The feed liquid is being pumped through nozzles, would have to be filtered to remove particulate matter upstream of the nozzles. In addition to this the carrier gas must be compressed in a turbine to raise the temperature of the carrier gas. Relying on a heated carrier gas for heating the liquid is inefficient. 5 GB 2082310 describes a process for the recovery of solvents. A carrier gas stream laden with solvent vapours in an evaporation space is compressed by a compressor, cooled, e.g. by heat exchanger, and expanded by turbine with the production of work to condense solvent vapours and separate the solvent. The carrier gas stream low in solvent vapours is 10 returned into the evaporation space after being reheated e.g. by the exchanger. The work arising on expansion is used in mechanical coupling with the compressor for compressing the carrier gas stream laden with solvent vapours. The work produced on expansion is used in mechanical coupling with the compressor for compressing the carrier gas stream laden with solvent vapours. By compressing the carrier gas stream with laden vapours, there is a 15 risk that some of the vapours of certain products can reach combustion temperatures and explode. The use of a compressor and a turbine adds to the questionable safety of the device and increases the operating cost. US Patent 3,843,463 describes a method of evaporation featuring humidification, which is 20 effected in a chamber maintained at a progressively increasing temperature level. The liquid being treated and a vapour carrier gas are passed through the chamber where they are progressively heated and the carrier gas is enriched in vapour from the liquid. The enriched carrier gas exiting from the chamber is moved alongside the chamber and in heat transfer relation with the fluids within the chamber but in a direction countercurrent to the flow of 25 those fluids. Heat is. applied to the exit portions of the chamber to assure the desired temperature gradient. Condensation occurs on the outside of the chamber. This condensate and the concentrated liquid can be recovered. The heated liquid concentrate exiting the chamber may be further treated. The liquid and carrier gas in this patent is entered through the top. of a column and allowed to flow over multiple packing material to 30 increase the evaporation surface are of the concentrated liquid and thus allows the carrier gas to come into contact with more liquid surface area as in a conventional evaporator scrubber system. In addition the liquid and the carrier gas are heated by steam which is extremely expensive. 35 WO 2009/000019 PCT/AU2008/000890 -5 US Patent 3,280,009 describes a process for the separation and recovery of the components of a mixture consisting of a volatile component and a non volatile component said volatile component being selected from the group consisting of phthalic acid anhydride and maleic acid anhydride which comprises establishing a melt of said mixture introducing 5 said melt in regulated amounts in the form of multidinous fine drops into an evaporation zone so as to provide a large surface. area thereof contacting said melt in said evaporation zone with a gas which is heated to a temperature sufficient to vaporize volatile component said gas additionally serving as carrier for the vapors formed in said contacting and recovering the vapors from said carrier gas. The liquid is sprayed through nozzles to form fine drops in 10 a space as it falls through the carrier gas and the carrier gas is heated to a temperature to vaporise some components. All these operations are energy consuming and would require a tall vaporisation column to stop unwanted particles from carrying over to the treated product. US Patent 2,985,686 describes, in a carbonylation reaction between reactants consisting 15 essentially of carbon monoxide water and a gaseous hydrocarbon selected from the group consisting of olefins and acetylene in a liquid solvent mixture and in the presence of a metal carbonyl the improved process for separating the vaporizable product of said carbonylation reaction from other vaporizable components of the liquid reaction mixture which comprises contacting said liquid reaction mixture with carbon monoxide as a non condensable carrier 20 gas to entrain vapors of said vaporizable components at a temperature below the boiling point of said liquid reaction mixture countercurrently contacting said carbon monoxide containing said entrained components with condensate therefrom for fractional exchange of said components therebetween withdrawing liquid and vapor fractions from the zone of said countercurrent contacting wherein one of said fractions is enriched in said reaction product 25 and condensing vapors from said carbon monoxide after said countercurrent contacting to form said condensate. This system requires the liquid being separated to be heated in a boiler prior to separation. For many liquids, the temperature difference between the vaporisation point and the temperatures of the boiler creates pressure. This is undesirable in a transfer system and drastically slows down the reaction. This plant is also designed to 30 operate at a very high pressure (50 atmospheres and above) which places high demands on equipment costs and operational safety. There remains a need for an alternative process and system which is effective in providing selective removal of a target liquid constituent from a multi-component liquid in a more 35 efficient or more economical manner than prior art systems of this type.

WO 2009/000019 PCT/AU2008/000890 -6 SUMMARY OF THE INVENTION According to one aspect of the present invention there is provided a process for selectively removing a target liquid constituent from a multi-component liquid comprising the steps: 5 a) heating the multi-component liquid in a chamber to a temperature at which the target liquid constituent selectively evaporates to form a vapor rich in the target liquid constituent; b) bubbling a carrier gas through the multi-component liquid of step a); c) continuously removing a gas/vapor mixture from the chamber, the gas/vapor 10 mixture comprising the vapor from step a) and the carrier gas from step b); d) condensing the gas/vapor mixture of step c) in a condenser to form a condensate rich in the target liquid constituent thereby liberate the carrier gas from the gas/vapor mixture; and, e) returning the carrier gas from step d) for use in step b). 15 According to a second aspect of the present invention there is provided a system for selectively removing a target liquid constituent from a multi-component liquid, the system comprising: a) a heater for heating the multi-component liquid in a chamber to a temperature at 20 which a target liquid constituent selectively evaporates to form a vapor rich in the target liquid constituent; b) a gas diffuser for bubbling a carrier gas through the heated multi-component liquid in the chamber; c) a gas circulation system for continuously removing a gas/vapor mixture from the 25 chamber, the gas/vapor mixture comprising the vapor from step a) and the carrier gas from step b); d) a condenser for condensing the vapor of the target liquid constituent from the gas/vapor mixture to form a condensate rich in the target liquid constituent; and, e) means for returning the carrier gas from step d) for use in step b). 30 Advantageously, the carrier gas is sourced from the gas present in the chamber above the multi-component liquid when operation of the process commences. The carrier gas may be one or more of the gases selected from the group consisting of: atmospheric air, dry air, oxygen, nitrogen, argon, helium, carbon dioxide. In one embodiment, the carrier gas is 35 atmospheric air at a temperature in the range of 25-35*C. Advantageously, the multi- WO 2009/000019 PCT/AU2008/000890 -7 component liquid includes solid and liquid contaminants when it is fed into the chamber overcoming the need for a separate filtration step. In one embodiment, the heater is arranged towards the bottom of the chamber and the gas 5 diffuser is arranged such that the carrier gas is directed to flow downwardly towards the bottom of the chamber as it exits the carrier gas. The heater may be arranged to direct heat into a lower portion of the chamber. The heater may be external or internal to the chamber. The gas/vapor mixture may be removed from the chamber by drawing a vacuum in the range of 10 - 5OkPa. 10 In one embodiment, the gas diffuser includes a feeder tube provided with a plurality of space-apart apertures arranged at regular intervals along the length of the feeder tube to optimize the distribution of gas through the multi-component liquid. The gas diffuser may be arranged within the chamber such that the spaced-apart apertures are immersed in the 15 multi-component liquid in use. If desired, the multi-component liquid may be fed into the chamber through the feeder tube of the gas diffuser. Advantageously, step e) may be conducted without reheating the carrier gas prior to its re use for step b). The gas circulation system may comprise a vacuum pump or gas blower 20 downstream of the condenser. In one embodiment, the vapor of the target liquid constituent is condensed through heat exchange with a cooling medium. Alternatively condensation can be achieved using expansion. 25 Advantageously, the process may further comprise the step of removing a first target liquid constituent then a second target liquid, the first target liquid having a lower boiling point than the second target liquid constituent. When the multi-component liquid comprises a plurality of target liquid constituents, a first target constituent may be separated from the multi 30 component liquid in a first chamber with a second target constituent may be separated from the multi-component liquid in a second chamber in series. Alternatively or additionally, when the multi-component liquid comprises a plurality of target liquid constituents, the heater may be used to heat the multi-component liquid to a corresponding plurality of different temperatures in series in a single chamber. 35 WO 2009/000019 PCT/AU2008/000890 -8 Advantageously, the viscosity of the multi-component liquid may be reduced by the addition of a low viscosity additive. In this scenario, the low viscosity additive may report to the condensate with the target liquid constituent during a first pass, and the condensate from the first pass may be selectively evaporated in a second pass using a lower temperature on the 5 second pass to recover the low viscosity additive from the condensate. In one embodiment, two or more target liquid constituents are removed simultaneously by heating the multi-component liquid to a temperature at which the two or more target liquid constituents selectively evaporate together. In this scenario, both or all of the target liquid 10 constituents condense in the condenser to form a multi-component condensate rich in both or all of the target liquid constituents and the multi-component condensate may be subjected to further processing to selectively separate the target liquid constituents from each other in another pass conducted at a lower temperature than the first pass. 15 Preferably, the multi-component liquid is heated to a temperature 25-50'C below the boiling point of the target liquid constituent. When the target constituent is fresh water, step a) may be conducted at a temperature in the range of 45-85*C or at a temperature in the range of 55-75*C or at a temperature in the range of 60-70*C. 20 In one embodiment the multi-component liquid is contaminated oil and the target constituent is clean oil and the multi-component liquid is heated to a temperature in the range of 80 to 1200C. Step a) may be conducted at a temperature in the range of 45-70*C to remove water from the contaminated oil. 25 In one embodiment, step a) is conducted at a temperature in the range of 120-130*C to reclaim kerosene from the contaminated oil or step a) is conducted at a temperature in the range of 135-145*C to reclaim diesel from the contaminated oil or step a) is conducted at a temperature in the range of 225-250*C to reclaim heavy hydrocarbons from the contaminated oil. 30 Step a) may be conducted at a temperature in the range of 130-140*C to remove a light hydrocarbon fraction from the contaminated oil or step a) may be conducted at a temperature in the range of 150-1550C to reclaim an intermediate hydrocarbon fraction from the contaminated oil or step a) may be conducted at a temperature in the range of 175 35 1900C to reclaim a heavy hydrocarbon fraction from the contaminated oil.

WO 2009/000019 PCT/AU2008/000890 -9 In one form, the heater is provided in the form of a heat exchanger having an inlet, an outlet, at least one side wall, a base and an upper heat transfer surface in abutting contact with a lower heat transfer surface of the chamber and the process further comprises the step of circulating a heat transfer fluid through the heat exchanger to heat the multi-component 5 liquid in the chamber. According to a second aspect of the present invention there is provided a system for selectively removing a target liquid constituent from a multi-component liquid, the system comprising: 10 a) a heater for heating the multi-component liquid in a chamber to a temperature at which a target liquid constituent selectively evaporates to form a vapor rich in the target liquid constituent; b) a gas diffuser for bubbling a carrier gas through the heated multi-component liquid in the chamber; 15 c) a gas circulation system for continuously removing a gas/vapor mixture from the chamber, the gas/vapor mixture comprising the vapor from step a) and the carrier gas from step b); d) a condenser for condensing the vapor of the target liquid constituent from the gas/vapor mixture to form a condensate rich in the target liquid constituent; and, 20 e) means for returning the carrier gas from step d) for use in step b). In one form, the heater, the chamber, the gas diffuser and the condenser are arranged in a vessel having one or more wall(s), the vessel further comprising a cooling jacket for cooling an outer peripheral portion of the wall(s) of the vessel, and a flow diverter arranged within 25 the vessel for directing the flow of the gas/vapor mixture towards the cooled outer peripheral portion of the wall(s) of the vessel. In one form, the system comprises a plurality of vessels arranged in series for selectively removing a plurality of target liquid fractions from a multi-component liquid, whereby 30 selective removal of each of these fractions is achieved at progressively higher operating temperatures for each of the vessels in the series. Preferably each of the vessels is provided with a heater in the form of a counter-current heat exchanger as this is an arrangement which can be used to recover waste heat from process streams. In one form, a heat transfer fluid is caused to flow counter-currently relative to the flow of multi 35 component liquid through the plurality of vessels.

WO 2009/000019 PCT/AU2008/000890 -10 According to a third aspect of the present invention there is provided a process for selectively removing a target liquid constituent from a multi-component liquid substantially as herein described with reference to and as illustrated in the accompanying representations. 5 According to a fourth aspect of the present invention there is provided a system for selectively removing a target liquid constituent from a multi-component liquid substantially as herein described with reference to and as illustrated in the accompanying representations. BRIEF DESCRIPTION OF THE DRAWINGS 10 In order to facilitate a more detailed understanding of the nature of the invention several embodiments of the improved causticisation process and apparatus will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a simplified conceptual flow diagram of a basic implementation of the 15 system of the present invention for batch operation; Figure 2 is a simplified conceptual flow diagram of a basic implementation of the system of the present invention for continuous operation; Figure 3a illustrates a side and bottom view of one embodiment of the gas diffuser used in the system of the present invention; 20 Figure 3b illustrates a bottom view of three alternative embodiments of the gas diffuser used in system of the present invention; Figure 4 is a simplified conceptual flow diagram of an embodiment of a multi chamber system for selectively removing a plurality of target liquids from a multi-component liquid; 25 Figure 5 is a simplified conceptual flow diagram of a multi-chamber system for processing a large volume of the multi-component liquid; Figure 6 is a simplified conceptual flow diagram of a basic implementation of the system of the present invention for recovering heat from a heat transfer fluid; Figure 7 is a cross-sectional diagram illustrated an embodiment of the present 30 invention in which condensation of vapor is encouraged to occur within a vessel; and, Figure 8 is a simplified conceptual flow diagram of a basic implementation of the system of the present invention for removing a plurality of target liquids from a multi component liquid whilst recovering heat from a heat transfer fluid. 35 WO 2009/000019 PCT/AU2008/000890 -11 DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Throughout this specification various terms are used and, in the interests of clarity, the following terms used throughout this specification are now defined. 5 The term "vapor pressure" is the pressure of a vapor in equilibrium with its non-vapor phases. It relates to the tendency of molecules and atoms to escape from a liquid or a solid. A substance with a high vapor pressure at ambient temperature is referred to as "volatile". 10 The "boiling point" of a liquid is bulk phenomenon which occurs at a specific temperature at which a substance changes state from a liquid to a gas throughout a liquid for a given pressure. A liquid boils when its vapor pressure is equal to the ambient pressure. The higher the vapor pressure of a substance at a given temperature, the lower its boiling point. 15 The term "evaporation" refers to surface phenomenon in which molecules located near a gas/liquid surface change state from a liquid to a gas at any temperature below the boiling point of a liquid. Liquids with higher vapor pressures will tend to evaporate faster than liquids with lower vapor pressures. Evaporation is encouraged by increasing the kinetic energy of the liquid molecules. 20 The term "condensation" refers to the change in state of a substance from a gas to a liquid. Condensation commonly occurs when a vapor is subjected to a decrease in temperature, an increase in pressure (for example, compression) or a combination of the two. The term "condensate" refers to a liquid which has been condensed from a vapor. A "condenser" is a 25 device used to condense a vapor or gas to a liquid. The term "distillation" refers to a method of separating chemical substances based on differences in their boiling points. 30 The term "cracking" refers to a process whereby carbon-carbon bonds in a starting material are caused to break (for example, cracking of heavy hydrocarbons to form light hydrocarbons or breaking large alkanes into smaller alkanes or alkenes). The term "upstream" refers to something located before a device. The term "downstream" 35 refers to something located after a device.

WO 2009/000019 PCT/AU2008/000890 - 12 The term "oil" refers to any liquid petroleum product (generally distilled from crude oil) that is suitable for burning for the purpose of generating heat. Oils comprise long hydrocarbon chains, particularly alkanes, cycloalkanes and aromatics and are generally heavier than petrol (referred to in the United States as "gasoline"). For example, fuel oils have a boiling 5 point generally ranging from 175 to 600*C depending on the length of the carbon chain, its composition and its purpose. Fuel oils can include amounts of pollutants, particularly sulfur which forms sulfur dioxide upon combustion. Types of fuel oil include: kerosene or paraffin oil, diesel, biodiesel, turbodiesel, low sulfur diesel, ultra-low sulfur diesel, heating oil, distillate, heavy distillate, light fuel oil, medium fuel oil, intermediate fuel oil, heavy fuel oil, 10 residual fuel oil, marine gasoil, and marine diesel oil. An "engine oil" or "motor oil" is any liquid petroleum product that is suitable for use in an engine to generate power. The term "gasoline" or "petrol" is a petroleum-derived liquid mixture used as fuel in internal combustion engines which consists mostly of hydrocarbons with between 5 and 12 carbon 15 atoms per molecule, enhanced with benzene or iso-octane to increase octane ratings. The boiling point of an alkane is primarily determined by weight and as a rule of thumb, the boiling point rises 20 - 30 *C for each carbon added to the chain. At ambient pressure and temperature, the alkanes from CH 4 to C 4

H

10 are gaseous, the alkanes from C 5

HI

2 to C 17

H

3 20 are liquids; and the alkanes after C 18

H

3 are solids. A straight chain alkane will have a boiling point higher than a branched chain alkane due to the greater surface area in contact, thus the greater van der Waals forces between adjacent molecules. On the other hand, cyclic alkanes tend to have higher boiling points than their linear counterparts due to the locked conformations of the molecules which give a plane of intermolecular contact. 25 The term "fresh water" refers to water having less than 0.05 weight percent of dissolved salt. The term "brackish water" refers to water having between 0.05-3 weight percent of dissolved salt. The term "saline water" refers to water having between 3-5 weight percent of dissolved salt. The term "brine" refers to water having greater than 5 weight percent of 30 dissolved salt. The term "ppm" refers to "parts per million". 35 WO 2009/000019 PCT/AU2008/000890 - 13 Specific embodiments of the present invention are now described in detail. The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. The process and system of the present invention is applicable to the separation of a target constituent from any multi-component liquid. The 5 multi-component liquid may be a two-component mixture such as an oil/water mixture, or even a solution such as seawater or another salt solution which is being treated to recover fresh water during desalination. The system and method of the present invention can be used to separate a target liquid constituent such as water from oil or to separate fresh water from salty water, or to separate a plurality of hydrocarbon fractions from dirty fuel oil. 10 A first embodiment of a system for selectively removing a target liquid constituent from a multi-component liquid (generally designated by reference numeral (10) is illustrated in Figure 1. In this embodiment, a multi-component liquid is being treated on a batch basis. Broadly speaking, the system (10) comprises a heater (12) for heating the multi-component liquid in a chamber (14) to a temperature at which a target liquid constituent selectively 15 evaporates to form a vapor rich in the target liquid constituent. A gas diffuser (16) is. provided for bubbling a carrier gas through the heated multi-component liquid in the chamber (14). The system (10) further comprises a gas circulation system (18) for continuously removing a gas/vapor mixture from the chamber (14), the gas/vapor mixture comprising the vapor of the target liquid constituent and the carrier gas. A condenser (20) is used for 20 condensing the vapor of the target liquid constituent from the gas/vapor mixture to form a condensate rich in the target liquid constituent. The system (10) further comprises a means (22) for returning the carrier gas to the chamber (14). In the embodiment illustrated in Figure 1, the chamber (14) is a horizontal, preferably 25 cylindrical closed container. However, the chamber need not be cylindrical. Thus, a rectangular, oval or hexagonal configuration could be contemplated. Similarly, the chamber need not be horizontal but could equally be vertical. There is no requirement for the multi component liquid to be filtered upstream of the chamber (14) and thus the multi-component liquid added to the chamber (14) may include both solid and liquid contaminants. Solid 30 contaminants such as sand, silt and metal components, if present, migrate under gravity towards a lowermost portion (24) of the chamber (14). Using the process of the present invention, the heat input from the heater (12) is adjusted so as to regulate the temperature of a multi-component liquid in such as way as to selectively WO 2009/000019 PCT/AU2008/000890 -14 cause target liquid constituents present in the multi-component liquid to evaporate. The vapors so produced are continuously drawn out of the chamber (14) towards the condenser (20) using the gas circulation system (18). Evaporation is more energetically favorable for target liquid constituents within the multi-component liquid which have the lowest 5 intermolecular forces holding that constituent in the liquid. In general, this means that evaporation occurs first for that constituent which has the greatest volatility and lowest solubility. For example, the lighter (more volatile) petroleum products such as gasoline evaporate faster than diesel fuel, heating oils, and kerosene, which are less volatile than gasoline. When there is more than one target liquid constituent to be removed, the target 10 liquid constituent with the highest volatility is removed first, with the temperature being raised by increasing the heat input from the heater (12) to remove the next most volatile target liquid constituent in sequence as described in greater detail below with reference to Figure 4. The heater (12) is used to heat the multi-component liquid so as to cause a target liquid 15 constituent present in the multi-component liquid to change state from a liquid to a vapor within the chamber (14). The heater (12) can apply heat to the multi-component liquid directly or indirectly and may be arranged internal or external to the chamber (14). In the embodiment illustrated in Figure 1, the heater (12) is preferably arranged to direct heat towards the lowermost portion (24) of the chamber (14). By way of example, the heater (12) 20 can be a low watt electric, oil fed, gas flame, induction or solar heater or a source of waste heat or sensible heat which comes from outside of the system (10). Using the process of the present invention, the temperature of the multi-component liquid is maintained at all times below the boiling point of the multi-component liquid. To automate the 25 process, heat input from the heater (12) to the chamber (14) is controlled using an adjustable thermostat (26) regulated by a temperature probe (28) which measures the temperature of the multi-component liquid in the chamber (14). Liquid over-temperature safety is provided if desired such that the system (10) shuts down automatically if the temperature measured by the temperature probe (28) exceeds a predetermined high 30 temperature limit. The vapor produced when the multi-component liquid is heated is extracted from the chamber (14) on a continuous basis through a suction -outlet (30) located in an upper portion (32) of the chamber (14). In the embodiment illustrated in Figure 1, the gas circulation WO 2009/000019 PCT/AU2008/000890 -15 system (18) comprises a vacuum pump, which is arranged to draw the vapor out of the chamber (14) through the suction outlet (30). The vacuum pump (18) performs the secondary function of returning a carrier gas back into the chamber (14) in the manner described in greater detail below. The discharge pressure of the vacuum pump (18) is in 5 the range of 0.1 to 0.5 bar (10 to 5OkPa). Whilst a vacuum pump has been used in this embodiment, the gas circulation system may equally rely on the use of a gas blower, gear pump or diaphragm pump, provided only that the gas circulation system (18) causes movement of the vapor out of the chamber (14) on a continuous basis. Using the process of the present invention, the vacuum pump (18) is located downstream of the condenser (20) 10 (between the condenser (20) and the chamber (14). Locating the vacuum pump (18) downstream of the condenser (20) reduces the possibility of vapor condensing in the vacuum pump (18) which could reduce the working life of the vacuum pump (18). An added advantage of placing the condenser (20) upstream of the vacuum pump (18) is that this reduces the capacity requirements of the gas circulation system (18), as a partial vacuum is 15 created during condensation of the vapor by reason of the reduction in the volume of the low pressure vapor which occurs as the vapor condenses. Utilization of this principle within the system (10) of the present invention enables the use of a vacuum pump (18) that only has to pull a vacuum high enough to initiate the start of the process. Once the process is initiated and condensation of the vapor begins to occur, the vacuum created in the condenser (20) is 20 sufficient to allow recycle of the carrier gas through the system (10) to occur with only nominal input from the vacuum pump (18). Thus, by positioning the condenser (20) upstream of the vacuum pump (18), the present invention is capable of efficient operation with a small capacity vacuum pump while at the same time minimizing the danger of damage to the vacuum pump from corrosion. 25 Advantageously, the system and process of present invention operate at a much lower pressure than prior art systems. One of the reasons for this is that the system (10) is closed such that there is no venting of gas or vapor from the system, reducing losses and emissions. 30 The vapor extracted from the chamber (14) using the vacuum pump (18) is directed to flow through the condenser (20) in which it is cooled or expanded to form a condensate rich in the target liquid constituent. In one preferred embodiment, the gas/vapor mixture is directed to flow through a tangential inlet (19) into the condenser (20) to create a vortex to improve WO 2009/000019 PCT/AU2008/000890 -16 efficiency of condensation occurring therein. The condensate is then collected in a condensate storage tank (34). The condensate storage tank (34) is a cylindrical upright sealed container provided with a discharge port (54) for discharge of purified liquid located towards the lowermost end (56) of the condensate storage tank (34). The condensate 5 collected in the condensate storage tank (34) is substantially liberated from contaminants and is temporarily stored in the condensate storage tank (34) prior to being reclaimed for re use. The condenser (20) can be any of many types, such as a refrigeration type, water cooled, or 10 air cooled, provided only that a sufficient temperature differential is provided by a cooling medium to cause the vapor present in the gas/vapor mixture to condense. In the embodiments illustrated in Figures 1 and 2, a water cooled condenser (20) is utilized, with cooling water being circulated from a cooling medium storage tank (21) through the condenser (20) using a circulating pump (23). In the embodiment illustrated in Figure 1, a 15 condensate flow regulator (25) is provided between the condenser (20) and the condensate storage tank (34), the condensate flow regulator (25) being arranged to reduce the flow rate of the condensate as it enters the condensate storage tank (34) so as to encourage excess vapor to condense out of the condensate. This is done to minimize carry-over of vapor from the condensate storage tank (34) to the vacuum pump (18). In one form of the present 20 invention, the condensate flow regulator (25) includes a delivery tube (27) provided with a plurality of space-apart condensate distribution apertures (29) arranged at regular intervals along the length of the delivery tube (27). The condensate distribution apertures (29) are used to regulate the flow rate of the condensate as it enters the condensate storage tank (34) for optimum recovery of vapor from the gas/vapor mixture. The particular shape of the 25 delivery tube (27) can vary. For best results, the delivery tube (27) and condensate distribution apertures (29) are arranged to direct the flow of the condensate towards the internal side wall(s) (31) of the condensate storage tank (34) to further encourage condensation of any excess vapor. 30 To encourage evaporation of the target liquid constituent in the chamber (14), a carrier gas is injected into the heated multi-component liquid using the gas diffuser (16) so as to form a homogeneous distribution of micro-bubbles in the multi-component liquid. As best seen in Figure 3a, the gas diffuser (16) comprises a feeder tube (50) provided with a plurality of small diameter space-apart apertures (52) arranged at regular intervals along the length of WO 2009/000019 PCT/AU2008/000890 -17 the feeder tube (50) to optimize the distribution of the carrier gas through the multi component liquid. The particular shape of the gas diffuser (16) can vary, with three illustrative examples shown in Figure 3b. When the chamber (14) has a cylindrical shape, a circular-shaped arrangement for the gas diffuser (16) is considered to the most suitable for 5 providing a homogeneous distribution of the micro-bubbles in the multi-component liquid. The gas diffuser (16) is arranged within the chamber (14) such that the apertures (52) are always immersed in use in the multi-component liquid. In the embodiment illustrated in Figure 2, the apertures (52) are located such that the carrier gas is injected into the multi component liquid at a level below the low liquid level set point. 10 For best results, the chamber (14) is provided with a bottom heater (12) and the gas diffuser (16) is arranged such that the carrier gas is directed to flow downwardly towards the bottom of the chamber (14) as it exits the gas diffuser (16). As the liquid present in the chamber (14) is hottest adjacent to the heater (12), the micro-bubbles expand rapidly as they form in 15 the liquid, with further expansion occurring as the bubbles travel upward through the multi component liquid, providing a greater surface area for enhanced evaporation. Moreover, the hottest portion of the liquid is also the most energetically favorable for micro-bubble initiation. When the bubbles reach the surface of the liquid, they break, discharging the carrier gas and any entrained vapor, further encouraging evaporation of the target liquid 20 constituent by increasing the effective gas/liquid interfacial area. At the same time, the micro-bubbles are too small to allow solid contaminants present in the multi-component liquid to be carried over out of the chamber through the suction outlet (30). It is understood that the presence of solid contaminants which settle towards the lowermost portion (24) of the chamber (14) further encourages nucleation of micro-bubbles, increasing the efficiency 25 of evaporation in the system (10). The system (10) of the present invention is closed in that the carrier gas is sourced from the atmospheric air which is present in the chamber (14) above the multi-component liquid when operation of the process commences. It is to be understood, that it is equally possible to 30 evacuate the atmospheric air from the system (10) before commencing operation so as to fill the chamber (14) with an inert gas, such as nitrogen, helium, argon or another carrier gas such as oxygen if desired. In any event, the carrier gas is not vented or otherwise consumed during operation of the process, reducing emissions to the atmosphere compared with prior art methods. The carrier gas is simply re-circulated throughout the closed system WO 2009/000019 PCT/AU2008/000890 -18 (10). Depending on the temperature of operation of the system (10), any water vapor present in the atmospheric air will be removed in the form of steam during start-up as the temperature of the multi-component liquid reaches a level at which water starts to evaporate to form steam. When the vapor is extracted from the chamber (14) and enters the 5 condenser (20), the steam condenses out of the gas/vapor mixture. In this way, any water present in the atmospheric air which filled the chamber at start-up is removed as condensate in the condensate storage tank (34). Once the start-up phase has been completed, the carrier gas being circulated around the system will be dry air. This overcomes the need for a separate drying process used in the prior art. Having dried the carrier gas in this manner, 10 the heat input from the heater (12) can then be increased so that the temperature of the multi-component liquid is raised to a level at which a different target liquid constituent selectively evaporates. As described above, a target liquid constituent is selectively removed from the multi 15 component liquid in the form of a vapor by heating the multi-component liquid. The vapor is removed from the chamber (14) under the effect of the exhaust conditions established by a vacuum pump (18) in the manner described above. The carrier gas which is circulated through the system (10) is removed at the same time as the vapor, in the form of a gas/vapor mixture. In the condenser (20), the vapor condenses out of the gas/vapor 20 mixture, whereby the carrier gas is essentially liberated making it available for recycle through the gas diffuser (16) into the chamber (14) via means (22). The carrier gas present in the gas/vapor mixture remains un-condensed during its passage through the condenser (20) and thus remains available for recycle back into the chamber (14) through the gas diffuser (16) using the vacuum pump (18). The gas diffuser (16) thus acts as the 25 means (22) for returning the carrier gas to the chamber (14). The carrier gas being returned into the chamber (14) has been cooled during its passage through the condenser (20) and is not heated prior to its injection into the chamber (14). Consequently, the carrier gas will be colder than the heated multi-component liquid, which 30 further encourages rapid expansion of the micro-bubbles once formed. In the embodiment illustrated in Figure 2 for which like reference numerals refer to like parts, the multi-component liquid is fed into the chamber (14) on a continuous basis from a reservoir or tank (36) through an inlet (38) located in a side wall (40) or a top wall (42) of the WO 2009/000019 PCT/AU2008/000890 - 19 chamber (14). The level of the multi-component liquid in the chamber (14) is regulated within set limits using a level gage (44) having upper and lower liquid level set points in co operation with a float operated level control valve (46). The level control valve (46) shuts off liquid entry into the chamber (14) when the liquid level in the chamber (14) exceeds a high 5 liquid level set point. When the level gage (44) senses that the liquid level in the chamber (14) is reaching a low liquid level set point, additional multi-component liquid is automatically directed to flow into the chamber (14) from the reservoir (36) through the inlet (38). The multi-component liquid can be caused to flow into the chamber (14) under influence of gravity if desired, or a centrifugal pump (48) can be used to regulate the flow of the liquid 10 into the chamber (14) in a steady state, if preferred. In the embodiment illustrated in Figure 2, the level of the condensate in the condensate storage tank (34) is monitored so as to cause the system (10) to shut down in the event that a high liquid level set point is exceeded. The level of the condensate in the condensate storage tank is monitored using high and low liquid level gauges (58) and (60), respectively. 15 When the level reaches the high liquid level gauge (58), a normally closed discharge valve (62) is activated to allow condensate to be pumped from the condensate storage tank (34) using a circulation pump (61) until the discharge valve (62) is shut when the condensate level reaches the low liquid level gauge (60). In the embodiment illustrated in Figure 2, a pressure gauge (64) which measures the pressure of the carrier gas is positioned at the 20 discharge side of the vacuum pump (18). The pressure measurement taken by the pressure gauge (64) is used to regulate the duty of the vacuum pump (18). A concentrated waste product is left behind in the chamber (14) when the target liquid constituent evaporates. This waste product can be discarded or subjected to further 25 processing if desired. Evaporation occurs at any temperature below the boiling point of a liquid provided only that individual molecules of the liquid are a) located near a gas/liquid interface, b) are moving in the proper direction to allow the molecules to escape the liquid and form a vapor, and c) 30 have sufficient kinetic energy to overcome liquid-phase intermolecular forces (eg. dipole dipole attraction, instantaneous-dipole induced-dipole attractions, and hydrogen bonds). The standard enthalpy change during evaporation is always positive, making it an endothermic process and subsequently, a cooling process. - Boiling, on the other hand, occurs when liquid molecules have enough thermal energy to overcome the liquid-phase intermolecular forces WO 2009/000019 PCT/AU2008/000890 -20 and allow a bulk change of state at a given temperature and pressure. Normally, the change of state which occurs during evaporation is a surface phenomenon which occurs very slowly. 5 Using the system and process of the present invention, the evaporation rate is enhanced using one or more of the following principles: a) increasing the temperature of the liquid to increase the kinetic energy of the molecules within the liquid; b) increasing the gas/liquid interfacial area by the introduction of the carrier gas using 10 the gas diffuser so as to provide more opportunities for the molecules to escape; c) increasing the contact time between the gaseous and liquid phases by the introduction of the carrier gas using the gas diffuser; d) optionally, adding liquids with high vapor pressure to the multi-component liquid to reduce viscosity and increase the mobility of the molecules; 15 e) increase in the amount of gas/liquid interface as the micro-bubbles continuously expand whilst floating upward which increases the contact between the carrier gas and the target constituent; and, f) extracting the vapor to reduce the concentration of the vapor in the air above the multi-component liquid. 20 If the multi-component liquid being treated is particularly thick, the viscosity of the multi component liquid can be reduced by the addition of a low viscosity additive to make it easier to bubble the carrier gas through the multi-component liquid. When this option is taken, the low viscosity additive can be added to the multi-component liquid via an inlet (17) before it 25 enters the chamber (14) or after it enters the chamber (14). For best results, the low viscosity additive is added to the multi-component liquid via the gas diffuser (16) along with the carrier gas being injected into the chamber (14). The low viscosity additive will report to the condensate with the target liquid constituent. The condensate can then be passed through the process a second time using a lower temperature on this second pass to 30 selectively evaporate the low viscosity additive therefrom for re-use if desired. When the multi-component liquid comprises a plurality of target liquid constituents, the system may comprise a corresponding plurality of chambers (14) serially connected together such that a first target constituent is selectively separated from the multi-component liquid in WO 2009/000019 PCT/AU2008/000890 -21 a first chamber (90) with a second target constituent being separated from the multi component liquid in a second chamber (92), and so on and so forth, until the multi component liquid reaches the last chamber in the-series. Such an arrangement is illustrated in Figure 4 for which like reference numerals refer to like parts. In Figure 4, only two 5 chambers (14) are shown but it is to be understood that any number of chambers can be used. An example of the use of such a system is described in greater detail below in Example 4. It is equally possible to use a single chamber system (10) such as that illustrated in Figure 1 or Figure 2 to remove a plurality of target liquid constituents, simply by using the heater to heat the multi-component liquid to a corresponding plurality of different 10 temperatures in series. Alternatively, two or more target liquid constituents can be removed simultaneously if desired by heating the multi-component liquid to a temperature at which the two or more target liquid constituents selectively evaporate together. In this scenario, both or all of the target liquid 15 constituents will condense in the condenser (20) to form a multi-component condensate rich in both or all of the target liquid constituents. The multi-component condensate can then be used as is or subjected, if desired, to further processing to selectively separate the target liquid constituents from each other in another pass through the .system (10) operating at a different temperature. If, by way of example, the multi-component liquid comprises 20 constituents A + B + C, the first chamber (90) can be used to remove a multi-component condensate rich in constituent A + B on a first pass, leaving C behind in the first chamber (90). The multi-component condensate rich in A + B can then be subjected to a second pass through the first chamber (90) or directed to the second chamber (92) operating at a lower temperature to selectively evaporate a condensate rich in A, leaving B behind in the 25 second chamber (92). Figure 5 (for which like reference numerals refer to like parts) illustrates a multi-chamber system (10) for use in processing a large quantity of multi-component liquid. In this embodiment, the system (10) comprises a plurality of chambers (14) in a vertically stacked 30 arrangement with a heater (12) being arranged to direct heat input into the base of each chamber (14) in the stack. Using this stacked arrangement, heat losses are minimized as adjacent chambers in the stack pick up heat from each other. A distribution system (37) is used to direct and regulate the flow of multi-component liquid from the reservoir or tank (36) to each chamber (14) in the manner described above for the embodiment illustrated in WO 2009/000019 PCT/AU2008/000890 -22 Figure 2. The distribution system (37) can, by way of example, be used to take one of the plurality of chamber (14) off-line for maintenance whilst distributing the multi-component liquid to flow only to the other chambers (14). 5 In the embodiment illustrated in Figure 5, the gas/vapor mixture from each chamber (14) is extracted using a shared gas circulation system (18) arranged to direct the gas/vapor mixture to a shared condenser (20). The condensate which forms in the condenser (20) is collected in a shared condensate storage tank (34). The carrier gas liberated from the gas/vapor mixture in the condenser (20) is re-circulated back into each chamber (14) using a 10 gas diffuser (16) arranged in each chamber in an analogous manner as described above for Figures 1 and 2. Figure 6 illustrates a further embodiment of the present invention for which like reference numerals refer to like parts. In this embodiment, a multi-component liquid is treated on a 15 batch basis. The heater (12) for heating the multi-component liquid is provided in the form of a heat exchanger having an inlet (70), an outlet (72), at least one side wall (74), a base (76) and an upper heat transfer surface (78) in abutting contact with a lower heat transfer surface (80) of the chamber (14). In use, a heat transfer fluid is circulated through the heat exchanger (12) to heat the multi-component liquid in the chamber (14). To achieve this, the 20 operating temperature of the heat transfer fluid at the inlet (70) of the heat exchanger (12) must be greater than the temperature at which the target liquid constituent selectively evaporates. Suitable heat transfer fluids for use in the process and apparatus of the present invention 25 include: glycol (such as ethylene glycol, diethylene glycol, triethylene glycol, or a mixture of them), glycol-water mixtures, methanol, propanol, propane, butane, ammonia, formate, tempered water or fresh water or any other fluid with an acceptable heat capacity that is commonly known to a person skilled in the art. The heat transfer fluid can be a gas or a liquid or a slurry. It is equally possible to use the heat exchanger (12) to recover waste heat 30 from a fluid, such as a flue gas or exhaust gas generated using another industrial process as discussed in greater detail below. If desired, a second heat exchanger (not shown) can be used to transfer waste heat from the flue gas or exhaust gas to the circulating heat transfer fluid in circumstances where a flue gas of exhaust gas is too corrosive or too hot for introduction into the heater (12).

WO 2009/000019 PCT/AU2008/000890 - 23 In the embodiment illustrated in Figure 6, the temperature of the multi-component liquid is maintained at all times below the boiling point of the multi-component liquid by regulating one or both of the flow rate and temperature of the fluid introduced into the heat exchanger (12) through the inlet (70) using the signal from the adjustable thermostat (26) regulated by 5 the temperature probe (28) which measures the temperature of the multi-component liquid in the chamber (14) Liquid over-temperature safety is provided if desired such that the system (10) shuts down automatically if the temperature measured by the temperature probe (28) exceeds a predetermined high temperature limit in an analogous manner as described above for the embodiment illustrated in figure 2.. 10 The heat exchanger (12) and the chamber (14) are sized in such a way that the upper heat transfer surface (78) of the heat exchanger (12) and the lower heat transfer surface (80) of the chamber (14) are of equivalent size and shape. The heater (12) and the chamber (14) operate in an analogous manner to that described above for other embodiments of the 15 present invention, the main difference being that source of heat in this embodiment is a hot fluid directed to flow through the inlet (70) into the heater (12). Heat transfer across the upper and lower heat transfer surfaces, (78) and (80) respectively is encouraged by generating turbulent flow of the heat transfer fluid as it is circulated through the heat exchanger. Heat transfer across the upper and lower heat transfer surfaces, (78) and (80) 20 respectively is further encouraged when the carrier gas is injected into the heated multi component liquid using the gas diffuser (16) and the gas diffuser (16) is arranged such that the carrier gas is directed to flow downwardly towards the bottom of the chamber (14) as it exits the gas diffuser (16). The carrier gas being returned into the chamber (14) has been cooled during its passage through the condenser (20) and is not heated prior to its injection 25 into the chamber (14). Consequently, the carrier gas will be colder than the heated multi component liquid, which further encourages heat transfer between the heater (12) and the chamber (14). Depending on the type of heat transfer fluid used and the amount of heat transferred from 30 the heater (12) to the chamber (14), condensation of the heat transfer fluid from a gas to a liquid can occur within the heater (12). When this occurs, the heater (12) condensate may be discarded or may be subjected to further processing to selectively separate one or more target liquid constituents from each other in a chamber (14) using the process of the present invention. By way of example, when the heat transfer fluid is.a flue gas, water and other WO 2009/000019 PCT/AU2008/000890 -24 condensable substances can condense from the flue gas as it cools during its passage through the heater (12). This condensate is collected and transferred to a second chamber (14) to selectively remove fresh water leaving a concentrated waste product containing flue gas contaminants such as carbon, sulfur and fluorine behind in the chamber (14) as the 5 water evaporates. This waste product can be discarded or subjected to further processing if desired. In this way, the system (16) of the present invention is effectively being used to scrub and cool a flue gas whilst making use of heat being recovered from the flue gas which would otherwise be wasted. Advantageously, this leads to a reduction of emissions from a flue gas to the environment of up to 90%. Exhaust gases from an engine can be treated in 10 an analogous manner. The heater exchanger (12) of the present embodiment is particular suited for use in the system of Figure .5 with a plurality of chambers (14) in series (and preferably in a vertically stacked arrangement) with a heater exchanger (12) being arranged to direct heat input into the base of each chamber in the stack. 15 A further embodiment of the present invention is illustrated in Figures 7 and 8, for which like reference numerals refer to like parts. This embodiment is particularly suited to a system for selectively removing a target hydrocarbon fraction from used or contaminated oil, but can equally be used for removal of other target liquid constituents from other multi-component liquids. The system (10) includes a plurality of closed vessels (100) in series, each vessel 20 (100) comprising a bottom heater (12) for heating the multi-component liquid held in a chamber (14) located in a lower portion (102) of the vessel (100), a gas diffuser (16) for bubbling a carrier gas through the heated multi-component liquid in the chamber (14), and a condenser (20) which is integral to the vessel (100) such that condensation of the gas/vapor mixture to form a condensate rich in the target liquid constituent occurs within the vessel 25 (100). To facilitate condensation of the vapor from the gas/vapor mixture within the vessel (100), each vessel (100) is provided with an external or internal cooling jacket (104) for cooling an outer peripheral portion (106) of the wall(s) (108) of the vessel (100). A flow diverter (110) is arranged within the vessel (100) for directing the flow of the gas/vapor mixture towards the cooled outer peripheral portion (106) of the wall(s) (108) of the vessel 30 (100). The vessel (100) illustrated in cross-section in Figure 7 is a horizontal, preferably cylindrical closed container, like a pressure vessel, to allow for the system to operate under a vacuum if desired. The cooling jacket (104) is provided with a plurality of evenly distributed pipes (112) WO 2009/000019 PCT/AU2008/000890 -25 through which a cooling medium is circulated in a continuous- closed loop. The cooling jacket (104) can be any of many types, such as a refrigeration type, water cooled, or air cooled, provided only that a sufficient temperature differential is provided by a cooling medium to cause the vapor present in the gas/vapor mixture to condense as it comes into 5 contact with the cooled outer peripheral portion (106) of the vessel (100). The flow diverter (110) can be solid or hollow with a plurality of evenly distributed pipes (113) through which a cooling medium is circulated in a continuous closed loop in an analogous manner to the way in which a cooling medium is circulated through the pipes (112) of the cooling jacket (104). 10 In use, the heater (12) is used to heat the multi-component liquid in the chamber (14) to a temperature at which a target liquid constituent selectively evaporates to form a vapor rich in the target liquid constituent. The heater (12) illustrated in Figure 7 is a heat exchanger, having an upper heat transfer surface (78) in abutting contact with a lower heat transfer surface (80) of the corresponding chamber (14) as described above in relation to Figure 6. 15 A cooling medium is caused to flow in a continuous closed loop through the pipes (112) of the cooling jacket (104) so as to cool the outer peripheral portion (106) of the wall(s) (108) of the vessel (100). The gas diffuser (16) bubbles a carrier gas through the heated multi component liquid in the chamber (14), forming a gas/vapor mixture within the vessel (100). 20 The gas circulation system (18) continuously draws the gas/vapor mixture from the chamber (14) upwards through the vessel (100) towards the suction outlet (30) located in an upper portion (114) of the vessel (100). As the gas/vapor mixture from the chamber (14) travels upwards towards the suction outlet (30), the flow diverter (110) directs the gas/vapor mixture to flow towards the cooled outer peripheral portion (106) of the wall(s) (108) of the vessel 25 (100), causing some or all of the vapor present in the gas/vapor mixture to condense to form a condensate rich in the target liquid constituent. Thus, in contrast with the other embodiments, the gas/vapor mixture removed through the suction outlet (30) in this embodiment comprises the carrier gas and any remaining vapor of the target liquid constituent which remains uncondensed, which may be negligible. As for the other 30 embodiments of the present invention, the system (10) further comprises means for returning the carrier gas to the chamber (14) (not shown). The condensate which forms within the vessel (100) flows downwardly under the influence of gravity until it is collected in a drain or gutter (118) arranged within a lower portion (102) of WO 2009/000019 PCT/AU2008/000890 - 26 the vessel (100) and adjacent to the wall(s) (106). The condensate collected in the gutter (118) is then directed to flow out of the vessel (100) and into a condensate storage tank (34). As described above for other embodiments of the present invention, the condensate collected in the condensate storage tank (34) is substantially liberated from contaminants 5 and is temporarily stored in the condensate storage tank prior to being reclaimed for re-use. In the embodiment illustrated in Figure 7, the gas circulation system (18) comprises a vacuum pump, which is used to draw the carrier gas (and any remaining uncondensed vapor) out of the vessel (100) through the suction outlet (30). Whilst a vacuum pump has 10 been used in this embodiment, the gas circulation system (18) may equally rely on the use of a gas blower, gear pump or diaphragm pump, provided only that the gas circulation system (18) causes movement of the carrier gas out of the chamber (14) on a continuous basis. The vacuum pump (18) performs the secondary function of returning a carrier gas back into the chamber (14) in the manner described above. 15 As previously described for other embodiments of the present invention, the system (10) of the present invention is closed in that the carrier gas is sourced from the atmospheric air (or other uncondensed gas) which is present in the chamber (14) above the multi-component liquid when operation of the process commences. It is to be understood, that it is equally 20 possible to evacuate the atmospheric air from the system (10) before commencing operation so as to fill the chamber (14) with an inert gas, such as nitrogen, helium, argon or another carrier gas such as oxygen if desired. In any event, the carrier gas is not vented or otherwise consumed during operation of the process; reducing emissions to the atmosphere compared with prior art methods. The carrier gas is simply re-circulated throughout the 25 closed system. The use of the plurality of vessels illustrated in Figure 8 to selectively remove a plurality of target hydrocarbon fractions from contaminated oil is now described. As before, like reference numerals refer to like parts. - As stated above, evaporation is more energetically 30 favorable for target hydrocarbon fractions within a contaminated oil which have the lowest intermolecular forces holding that constituent in the liquid. In general, this means that evaporation occurs first for that constituent which has the greatest volatility and lowest solubility. When there is more than one target hydrocarbon fraction to be removed from the contaminated oil, the target hydrocarbon fraction with the highest volatility is removed first at WO 2009/000019 PCT/AU2008/000890 -27 the lowest operating temperature, with the operating temperature within the next vessel in the series being raised to remove the next most volatile target hydrocarbon fraction in sequence. Thus in Figure 8, a series of seven vessels (100) is shown a first vessel (120) for removing water from the contaminated oil; a second vessel (122) for removing a 5 kerosene fraction from the partially purified oil which exits the first vessel (120); a third vessel (124) for removing a diesel fraction from the partially purified oil which exits the second vessel (122); a fourth vessel (126) for removing a light hydrocarbon fraction from the partially purified oil which exits the third vessel (124); a fifth vessel (128) for removing a medium hydrocarbon fraction from the partially purified oil which exits the fourth vessel 10 (126); a sixth vessel (130) for removing a heavy hydrocarbon fraction from the partially purified oil which exits the fifth vessel (128); and, a final vessel (132) for removing a bituminous product from the partially purified oil which exits the sixth vessel (130). Selective removal of each of these fractions is achieved at progressively higher operating temperatures for each of the vessels (120), (122), (124), (126), (128), (130) and (132) in the 15 series. In the embodiment illustrated in Figure 8, each of the vessels (120), (122), (124), (126), (128), (130) and (132) is provided with a heater (12) in the form of a counter-current heat exchanger. A hot heat transfer fluid, by way of example a hot or heated oil, is introduced 20 into the final vessel (132) in the series (as this vessel has the highest operating temperature of the series of vessels), to heat the partially purified oil in the chamber (14) of the final vessel (132) to a temperature at which a bituminous product is selectively evaporated. In the process, the hot heat transfer fluid is cooled slightly as it is circulated through the heater (12) of the final vessel (132). The partially cooled heat transfer fluid is then directed to flow into 25 the next vessel in the series, in this example, the sixth vessel (130), and so on, until finally being circulated through the first vessel (120) (which has the lowest operating temperature in the series). The heat transfer fluid continues to lose heat as if flows counter-currently relative to the flow of partially purified oil through the system (10), with useful heat being recovered from the heat transfer fluid by each of the vessels (100) in the series. In this way, 30 the system of Figure 8 can be used to replace the heat trains used in oil refineries, other refineries or mills such as pulp mills, making use of otherwise wasted sensible heat to purify contaminated multi-component liquids. With reference to Figure 8, the plurality of closed vessels (100) share a common gas circulation system (18) with a backpressure regulator (140) being provided on each vessel (100) to facilitate independent control of the pressure in WO 2009/000019 PCT/AU2008/000890 -28 each vessel in the series. The advantages of the various aspects and embodiments of the present invention are further described and illustrated by the following examples and experimental test results. These 5 examples and experimental test results are illustrative of a variety of possible implementations and are not to be construed as limiting the invention in any way. The present invention is also not limited by the particular number nor type of evaporation chamber, condenser, heater or pump described in the following examples. 10 In Examples 2, 3, 4 and 5 given below, exemplary fuel oils are treated. It will be readily appreciated by persons skilled in the art that there is no one typical composition of a fuel oil, each particular type of oil having different fractions of alkanes, different additives etc. depending on a number of factors, most notably the nature of the use to which the oil is to be put. Although other types of fuel oils may equally be used to practice or test the various 15 aspects of the present invention, the description to follow is limited for convenience and clarity to kerosene, diesel and DFO. The present invention is equally applicable to the treatment of other fuel oils. Example 1: Description of Testing Apparatus 20 A bench-scale testing apparatus was assembled to conduct trials. The chamber was constructed using the lid and body of a 5.5 liter capacity Prestige @ Pressure Cooker (210mm diameter, 150mm high) with all other fittings stripped. The suction outlet was constructed using a %" male flair fitting attached to the lid of the chamber and offset from the centre of the lid. Insulation, in the form of a towel, was provided around the chamber to 25 minimise loss of heat. Heating was supplied to the Pressure Cooker using a Sunbeam @ Model FP220D electric frying pan as the heater, which was rated at a maximum temperature of 2000C having a power rating of 10 amps. A 220mm hole was cut into the lid of the frypan to accommodate the body of the pressure cooker. 30 The gas diffuser was constructed using a 425mm length of %/" diameter copper tube with 12 x 1/16" apertures having 1/" -2"' centers on the bottom of the tube. The copper tube was bent in a circle to fit inside the chamber with a centre feeder tube joining to a %" male flair fitting attached to the centre of the lid of the chamber with 1/4" flare nut. The inlet end of the copper feeder tube was open to allow entry of the carrier gas into the gas diffuser with the 35 opposite end of the copper feeder tube sealed to force the carrier gas to flow out of the WO 2009/000019 PCT/AU2008/000890 -29 apertures. The condenser was constructed using a 447mm length of Y 4 " copper tubing flared both ends with flare nuts to connect the suction outlet to the condenser. The condenser was 5 constructed using three pieces of thin wall of mild steel tube, arranged concentrically to form a water-cooled condenser having three chambers - the outer chamber and the inner chamber were arranged to receive cooling water with the gas/vapor mixture being directed to flow through the central chamber to maximize cooling efficiency. Specifically, the outermost tube had a 38mm OD, the middle tube had a 25mm OD and the inner tube had a 16mm OD. 10 The condensate (and liberated carrier gas) was transferred from the condenser to the condensate storage tank along a 500mm long, %" copper tube flared both ends with flare nuts. The condensate storage tank was constructed using 90mm thin wall steel tube, 200mm long 15 with dish ends welded ends of vessel, 2 x %" male flare fittings positioned 60mm apart on top dish entering the vessel, bottom dish drain valve %4". The vacuum pump used to return the carrier gas to the chamber and draw the gas/vapor mixture from the chamber had a capacity of 75 litres per minute. The carrier gas was 20 delivered from the vacuum pump to the chamber using 2 x %" female flare flexible refrigeration charging hoses. Water cooling of the condenser was achieved by pumping water from a 25 litre capacity Plastic bucket through a garden hose to the condenser and back again using a submersible 25 pump (%" 950 litres per hour at 1.8m head). Example 2: Dirty Kerosene Sample 1 litre of dirty (used) kerosene was charged into the chamber. As soon as heating commences, the vacuum pump was actuated to commence drawing the carrier gas from the 30 space in the chamber above the dirty kerosene. As the temperature of the dirty kerosene rises, a gas/vapor mixture is removed from the top of the chamber via the suction outlet and the rate of gas injection through the gas diffuser matches the rate of extraction of the gas/vapor mixture. The extracted gas/vapor mixture is expanded and cooled upon entry into the condenser at a velocity drop of approximately 10:1 with the contact surfaces of the 35 condenser operating between 20-30*C due to the cooling effects of cooling water being WO 2009/000019 PCT/AU2008/000890 -30 passed through the outer and inner chambers of the condenser. The carrier gas flows out of the suction outlet of the chamber and then through the condenser to the condensate storage tank. The carrier gas then flows back through the 5 vacuum pump for injection into the dirty kerosene in the chamber through the gas diffuser. The temperature of the carrier gas upon injected into the kerosene through the gas diffuser is around ambient temperature (20 - 30*C) and at a flow rate of about 1.5 litres per second. The vapor which. condenses on the contact surfaces of the downwardly inclined condenser 10 form a condensate which flows along the central chamber of the condenser and into the condensate storage tank. The condensate settles under gravity towards the lower portion of the condensate storage tank whilst the carrier gas is drawn through the vacuum pump back into the chamber through the gas diffuser. The submersible pump is used to circulate cooling water through the inner and outer chambers of the condenser. 15 The heater was used to raise the temperature of the dirty kerosene into the range of 65 to 85 0 C to remove any water present. The water which evaporated in this temperature range was collected in the condensate storage tank and reused as cooling water. 20 The temperature was then raised to the range of 120-130*C (preferably held at 1250C to selectively evaporate clean kerosene, leaving behind a sludge rich in contaminants. Any solids present in the multi-component liquid sample fed into the chamber remained in the chamber as a sludge which can be separately treated for disposal. 25 At the conclusion of the test, the composition of the clean kerosene condensate was evaluated and compared with the composition of the original sample. The results are shown in the Table I below. It is clear from this analysis that the condensate is essentially pure with over 95% of the original sample reporting to the condensate. 30 Table 1: Analysis of Feed and Condensate Composition for Dirty Kerosene Sample Analysis Feed Condensate Oil Properties KF Moisture ppm (ASTM D4928) 50 27 Water & Sediment % vol (D1796) 1.0 <0.05 WO 2009/000019 PCT/AU2008/000890 -31 Ash Content 5 mass (D482) 0.1891 0.001 Wear Metals D6185 (ppm, mg/L) Iron (Fe) 128 <1 Chromium (Cr) <1 <1 Copper(Cu) 115 <1 Lead (Pb) 25 <1 Tin (Sn) 6 <1 Contaminants D5185 (ppm, mg/L) Silicon (Si) 597 4 Aluminium (Al) 29 <1 Sodium (Na) 13 <1 Additives D5185 (ppm, mg/L) Calcium (Ca) 54 <1 Zinc (Zn) 29 <1 Phosphorus (P) 35 <1 Example 3: Dirty Diesel Sample The test described above for Example 2 was repeated using I litre of dirty (used) diesel (which is essentially a mixture of liquid hydrocarbon fuel oils), with water being removed as a 5 first step in the manner described above for Example 2. Thereafter the sample was heated to a temperature in the range of 140-145 0 C. At the conclusion of the test, the composition of the clean kerosene condensate was evaluated and compared with the composition of the original sample. The results are shown in the Table 2 below. It is clear from this analysis that the condensate is essentially pure with over 95% of the original sample reporting to the 10 condensate. Table 2: Analysis of Feed and Condensate Composition for Dirty Diesel Sample Analysis Feed Condensate Oil Properties KF Moisture ppm (ASTM D4928) 9180 37 Water & Sediment % vol (D1796) 2.0 <0.05 Ash Content 5 mass (D482) 0.105 0.0015 Wear Metals D5185 (ppm, mg/L) Iron (Fe) 47 <1 Chromium (Cr) <1 <1 Copper (Cu) 15 <1 Lead (Pb) 9 4 Tin (Sn) <1 <1 Contaminants D5185 (ppm, mg/L) WO 2009/000019 PCT/AU2008/000890 -32 Silicon (Si) 37 <1 Aluminium (Al) 11 <1 Sodium (Na) 29 <1 Additives D5185 (ppm, mg/L) Calcium (Ca) 98 <1 Zinc (Zn) 58 <1 Phosphorus (P) 70 <1 Example 4: Dirty Fuel Oil (DFO) Sample The test described above for Example 2 was repeated using 1 litre of dirty (used) heavy hydrocarbon fuel oil, with water being removed as a first step in the manner described above 5 for Example 2. Thereafter the sample was heated to a temperature in the range of 175 195 0 C. At the conclusion of the test, the composition of the clean fuel oil condensate was evaluated and compared with the composition of the original sample. The results are shown in the Table 3 below. It is clear from this analysis that the condensate is essentially pure with over 95% of the original sample reporting to the condensate. 10 Table 3: Analysis of Feed and Condensate Composition for Dirty Fuel Oil Analysis Feed Condensate Oil Properties KF Moisture ppm (ASTM D4928) 3865 45 Water & Sediment % vol (D1796) 1.2 <0.05 Ash Content 5 mass (D482) 0.325 0.006 Wear Metals D5185 (ppm, mg/L) Iron (Fe) 48 2 Chromium (Cr) <1 <1 Copper (Cu) 14 2 Lead (Pb) 12 1 Tin (Sn) <1 <1 Contaminants D5185 (ppm, mg/L) Silicon (Si) 52 2 Aluminium (Al) 12 <1 Sodium (Na) 29 <1 Additives D5185 (ppm, mg/L) Calcium (Ca) 551 <1 Zinc (Zn) 266 <1 Phosphorus (P) 289 <1 WO 2009/000019 PCT/AU2008/000890 - 33 The test was repeated using a higher viscosity contaminated gear box oil and operating at a temperature in the range of 225-250*C. During this test, a small amount of clean kerosene (reclaimed using the process described above in Example 2) was gravity fed through the gas diffuser to lower the viscosity of the dirty fuel oil in the chamber to accelerate evaporation. 5 The condensate produced on the first pass through the chamber was clean fuel oil mixed with kerosene. This mixture was then subjected to a second pass through the chamber using the method described in Example 2 to reclaim the kerosene from the fuel oil. It was observed that clean diesel performs in the same way in lowering the viscosity, the clean diesel being reclaimed from the condensate rich in both the fuel oil and the diesel being 10 separated in a second pass using the method described in Example 3 above. In both cases, it was confirmed during tests that the kerosene or diesel being added as the low viscosity additive to the heavy hydrocarbon sample being treated worked equally well if added in clean or contaminated (used) form, any contaminants being present being left 15 behind in the chamber. Example 5: Crude Oil The test described above for Example 2 was repeated using I litre of crude oil (direct from a wellhead), with water being removed as a first step in the manner described above for 20 Example 2. Thereafter the sample was heated in three passes to the following temperatures: a) Condensate 1: to a-temperature in the range of 130-140 0 C (preferably 135 0 C); b) Condensate 2: to a temperature in the range of 150-155 0 C. 25 c) Condensate 3: to a temperature in the range of 175-190 0 C. At the conclusion of the test, the composition of the clean fuel oil condensate samples were evaluated and compared with the composition of the original crude oil sample. The results are shown in the Table 4 below. It is clear from this analysis that the condensate is 30 essentially pure with over 95% of the original sample reporting to the condensate. 35 WO 2009/000019 PCT/AU2008/000890 - 34 Table 4: Analysis of Feed and Condensate Composition for Crude Oil Sample Analysis Condensate Condensate Condensate 3 1 2 Oil Properties KF Moisture ppm (ASTM D4928) 75 80 87 Water & Sediment % vol (D1796) <0.05 <0.05 <0.05 Ash Content 5 mass (D482) <0.0002 <0.0002 <0.0002 Wear Metals D5185 (ppm, mg/L) Iron (Fe) 2 <1 <1 Chromium (Cr) <1 <1 <1 Copper (Cu) <1 3 3 Lead (Pb) <1 <1 <1 Tin (Sn) <1 <1 <1 Contaminants D5185 (ppm, mg/L) Silicon (Si) 1 <1 1 Aluminium (Al) <1 <1 <1 Sodium (Na) <1 <1 2 Additives D5185 (ppm, mg/L) Calcium (Ca) <1 <1 <1 Zinc (Zn) <1 <1 <1 Phosphorus (P) <1 <1 <1 5 Example 6: Potable Water from Salty Water The test described above for Example 2 was repeated using 1 litre of dirty salty water sourced directly from the Swan River in Perth. The sample was heated to a temperature in the range of 60-80 0 C (preferably 65 0 C) to form a condensate which is substantially fresh water, leaving behind in the chamber a concentrated waste sludge rich in contaminants. At 10 the conclusion of the test, the composition of the condensate was evaluated and compared with the composition of the original salty water sample. The results are shown in the Table 5 below with all units in mg/L (equivalent to g/m 3 ) unless otherwise stated. It is clear from this analysis that the condensate is essentially pure with over 95% of the original sample reporting to the condensate. 15 Table 5: Analysis of Feed and Condensate Composition for Example 6 Test Feed Condensate pH 7.90 6.54 Conductivity at 25"C (mS/m) 5150 2 Colour (@400nm) (Hazen) 6 1 WO 2009/000019 PCT/AU2008/000890 -35 Turbidity (NTU) 0.4 0.2 Aluminium 0.75 <0.008 Iron 0.045 0.004 Manganese <0.002 <0.002 Calcium 390 0.30 Potassium 360 0.3 Magnesium 1270 0.15 Sodium 10900 1.2 Sulfate 2620 0.8 Hardness as CaCO 3 6180 1.4 Total Alkalinity 120 8 Silicon (as Si0 2 ) <2.2 <2.2 Total Anions (CI) 18000 1.7 Alkalinity as HCO 3 144 9.5 Nitrogen - NO 2 + NO3 <0.5 0.39 Example 7: Potable Water from Industrial Lake Water 1 litre of lake water from an alumina refinery operating a Bayer process was charged into the system described above in Example 1. An analysis of the lake water being treated is 5 provided below in Table 6. As soon as heating commences, the vacuum pump was actuated to commence drawing the carrier gas from the space in the chamber above the lake water. As the temperature of the lake water rises, a gas/vapor mixture is removed from the top of the chamber via the suction 10 outlet and the rate of gas injection through the gas diffuser matches the rate of extraction of the gas/vapor mixture. The extracted gas/vapor mixture is expanded and cooled upon entry into the condenser at a velocity drop of approximately 10:1 with the contact surfaces of the condenser operating between 20-30*C due to the cooling effects of cooling water being passed through the outer and inner chambers of the condenser. 15 Table 6: Analysis of Feed Composition for Example 7 Feed Property/Constituent Sodium Hydroxide 0.5 - 1% Sodium Oxalate <0.1% Water >60% Alkaline Salts <5% Aluminium Oxide <1% Sodium Sulfate <1% WO 2009/000019 PCT/AU2008/000890 -36 Sodium Chloride <0.1% Appearance Red-Brown Liquid Odour Slight Odour pH 12.5 Specific Gravity 1.02 The carrier gas flows out of the suction outlet of the chamber and then through the condenser to the condensate storage tank. The carrier gas then flows back through the vacuum pump for injection into the lake water in the chamber through the gas diffuser. The 5 temperature of the carrier gas upon injected into the lake water through the gas diffuser is around ambient temperature (20 - 300C) and at a flow rate of about 1.5 litres per second. The vapor which condenses on the contact surfaces of the downwardly inclined condenser form a condensate which flows along the central chamber of the condenser and into the 10 condensate storage tank. The condensate settles under gravity towards the lower portion of the condensate storage tank whilst the carrier gas is drawn through the vacuum pump back into the chamber through the gas diffuser. The submersible pump is used to circulate cooling water through the inner and outer chambers of the condenser. 15 The lake water was heated to a temperature in the range of 60-80*C (preferably 650C) to form a condensate which is substantially fresh water, leaving behind in the chamber a concentrated waste sludge rich in contaminants. At the conclusion of the test, the composition of the condensate was evaluated and 20 compared with the composition of the original lake water sample. The results are shown in the Table 7 below with all units in mg/L (equivalent to g/m 3 ) unless otherwise stated. Table 7: Analysis of Condensate Composition for Lake Water Sample Property/Composition Condensate pH 7.09 Conductivity at 25"C (mS/im) 2 Turbidity (NTU) 0.7 Aluminium 0.14 Iron 0.006 Manganese <0.002 Calcium 0.15 WO 2009/000019 PCT/AU2008/000890 -37 Potassium <0.1 Magnesium <0.1 Sodium 2.0 Sulfate 0.3 Hardness as CaCO3 0.4 Total Alkalinity as CaCo 3 8.0 Silicon (as Si02) <2.2 Total Anions (Cl) <0.6 Alkalinity as HCO3 10.1 Nitrogen - N02 + N03 0.060 It is clear from this analysis that the condensate is essentially pure with over 95% of the original sample reporting to the condensate. 5 Now that the preferred embodiments of the present invention have been described in detail, the present invention has a number of advantages over the prior art, including the following: a) the process of the present invention is safer than distillation because the multi component liquid is not heated above the boiling point of any of target liquid constituents; 10 b) the present invention maximizes the reclamation of purified target liquid constituents from a contaminated multi-component liquid without creating conditions potentially harmful to the target liquid being reclaimed by avoiding the use of excessive temperatures which can alter the chemistry of the target liquid constituents; c) the present invention permits water to be efficiently removed from a multi 15 component liquid in a multi-stage process using one apparatus, thus eliminating the need for a separate dehydration stage present in prior art systems. d) by condensing the gas/vapor mixture after it leaves the chamber and recycling the carrier gas to the chamber, the present invention is capable of efficient operation with much smaller capacity vacuum pump than those of the prior art; 20 e) through encouraging evaporation of a target liquid constituent liquid from a contaminated multi-component liquid, the solid contaminants are essentially left behind in the chamber thus eliminating the need for a separate filtration stage which is an essential feature of prior art systems; f) compared to distillation and cracking process, the power consumption using the 25 present invention is approx. 60% less due to elimination of losses associated with latent heat; g) the present invention provides a closed system in that there is no need for venting WO 2009/000019 PCT/AU2008/000890 -38 of non-condensibles which yield a loss in prior art processes; and, h) the present invention yields a waste product which is less that 5% of the starting material, compared to the usual 20 - 25% achieved using prior art distillation or cracking processes. 5 It will be apparent to persons skilled in the chemical engineering arts that numerous variations and modifications to the process and system of the present invention can be made without departing from the basic inventive concepts. For example, if desired, the multi component liquid can be pre-heated to an intermediate temperature upstream of the 10 chamber 14. One method of achieving this is to provide solar heating to heat the multi component liquid whilst it is being stored in the reservoir or tank 36. By way of further example, the vacuum pump can be caused to operate at a higher vacuum (with the discharge pressure of the vacuum pump 18 being in the range of 90 to 100kPa) to encourage evaporation of the target liquid from the multi-component liquid to occur at a 15 lower temperature to reduce the heating requirements of the process. All such modifications and variations are considered to be within the scope of the present invention, the nature of which is to be determined from the foregoing description and the appended claims. It will be clearly understood that, although a number of prior art publications are referred to 20 herein, this reference does not constitute an admission that any of these documents forms part of the common general knowledge in the art, in Australia or in any other country. In the statement of invention and description of the invention which follow, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, 25 i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims

1. A process for selectively removing a target liquid constituent from a multi-component liquid comprising the steps of: 5 a) heating the multi-component liquid in a chamber to a temperature at which the target liquid constituent selectively evaporates to form a vapor rich in the target liquid constituent; b) bubbling a carrier gas through the multi-component liquid of step a); c) continuously removing a gas/vapor mixture from the chamber, the gas/vapor 10 mixture comprising the vapor from step a) and the carrier gas from step b); d) condensing the gas/vapor mixture of step c) in a condenser to form a condensate rich in the target liquid constituent and thereby liberate the carrier gas from the gas/vapor mixture; and, e) returning the carrier gas from step d) for use in step b). 15

2. The process of claim 1 wherein the carrier gas is sourced from the gas present in the chamber above the multi-component liquid when operation of the process commences.

3. The process of claim 1 or 2 wherein the carrier gas is one or more of the gases 20 selected from the group consisting of: atmospheric air, dry air, oxygen, nitrogen, argon, helium, carbon dioxide.

4. The process of any of the preceding claims wherein the carrier gas is atmospheric air at a temperature in the range of 25-35 0 C. 25

5. The process of any one of the preceding claims wherein the multi-component liquid includes solid and liquid contaminants when it is fed into the chamber.

6. The process of any one of the preceding claims wherein a heater is arranged 30 towards the bottom of the chamber and the gas diffuser is arranged such that the carrier gas is directed to flow downwardly towards the bottom of the chamber as it exits the carrier gas.

7. The process of any one of the preceding claims wherein the gas/vapor mixture is removed from the chamber by drawing a vacuum in the range of 10 - 50kPa. 35 -40

8. The process of claim 6 or 7 wherein the heater is arranged to direct heat into a lower portion of the chamber.

9. The process of any one claims 6 to 8 wherein the heater is external to the chamber. 5

10. The process of any one of the preceding claims wherein the gas diffuser includes a feeder tube provided with a plurality of space-apart apertures arranged at regular intervals along the length of the feeder tube to optimize the distribution of gas through the multi component liquid. 10

11. The process of claim 10 wherein the gas diffuser is arranged within the chamber such that the spaced-apart apertures are immersed in the multi-component liquid in use.

12. The process of claim 10 or 11 wherein the multi-component liquid is fed into the 15 chamber through the feeder tube of the gas diffuser.

13. The process of any one of the preceding claims wherein step e) is conducted without reheating the carrier gas prior to its re-use for step b). 20

14. The process of any one of the preceding claims wherein the gas circulation system comprises a vacuum pump or gas blower downstream of the condenser.

15. The process of any one of the preceding claims wherein the gas/vapor mixture is not vented to atmosphere. 25

16. The process of any one of the preceding claims further comprising the step of removing a first target liquid constituent then a second target liquid, the first target liquid having a lower boiling point than the second target liquid constituent. 30

17. The process of any one of the preceding claims wherein the multi-component liquid comprises a plurality of target liquid constituents and a first target constituent is separated from the multi-component liquid in a first chamber with a second target constituent being separated from the multi-component liquid in a second chamber in series. 35 -41

18. The process of any one of the preceding claims wherein the multi-component liquid comprises a plurality of target liquid constituents and the heater is used to heat the multi component liquid to a corresponding plurality of different temperatures in series in a single chamber. 5

19. The process of any one of the preceding claims wherein the viscosity of the multi component liquid is reduced by the addition of a low viscosity additive.

20. The process of claim 19 wherein the low viscosity additive reports to the condensate 10 with the target liquid constituent during a first pass, and the condensate from the first pass is selectively evaporated in a second pass using a lower temperature on the second pass to recover the low viscosity additive from the condensate.

21. The process of any one of the preceding claims wherein two or more target liquid 15 constituents are removed simultaneously by heating the multi-component liquid to a temperature at which the two or more target liquid constituents selectively evaporate together.

22. The process of claim 21 wherein both or all of the target liquid constituents condense 20 in the condenser to form a multi-component condensate rich in both or all of the target liquid constituents and the multi-component condensate is subjected to further processing to selectively separate the target liquid constituents from each other in another pass conducted at a lower temperature than the first pass. 25

23. The process of any one of the preceding claims wherein the multi-component liquid is heated to a temperature 25-50 0 C below the boiling point of the target liquid constituent.

24. The process of any one of the preceding claims wherein the target constituent is fresh water and step a) is conducted at a temperature in the range of 45-85 0 C or at a 30 temperature in the range of 55-75"C or at a temperature in the range of 60-700C.

25. The process of any one of the preceding claims wherein the multi-component liquid is salty water, the target constituent is fresh water and the heater heats the salty water to a temperature in the range of 45-85*C or at a temperature in the range of 55-75*C or at a 35 temperature in the range of 60-70*C. -42

26. The process of any one of the preceding claims wherein the multi-component liquid is used oil and the target constituent is clean oil and the multi-component liquid is heated to a temperature in the range of 80 to 1200C. 5

27. The process of any one of the preceding claims wherein step a) is conducted at a temperature in the range of 45-70 0 C to remove water from the contaminated oil.

28. The process of any one of the preceding claims wherein step a) is conducted at a temperature in the range of 120-130 0 C to reclaim kerosene from the contaminated oil. 10

29. The process of any one of the preceding claims wherein step a) is conducted at a temperature in the range of 135-1450C to reclaim diesel from the contaminated oil.

30. The process of any one of the preceding claims wherein step a) is conducted at a 15 temperature in the range of 225-2500C to reclaim heavy hydrocarbons from the contaminated oil.

31. The process of any one of the preceding claims wherein step a) is conducted at a temperature in the range of 130-140 0 C to remove a light hydrocarbon fraction from the 20 contaminated oil.

32. The process of any one of the preceding claims wherein step a) is conducted at a temperature in the range of 150-155*C to reclaim an intermediate hydrocarbon fraction from the contaminated oil. 25

33. The process of any one of the preceding claims wherein step a) is conducted at a temperature in the range of 175-190*C to reclaim a heavy hydrocarbon fraction from the contaminated oil. 30

34. The process of any one of the preceding claims wherein the heater is provided in the form of a heat exchanger having an inlet, an outlet, at least one side wall, a base and an upper heat transfer surface in abutting contact with a lower heat transfer surface of the chamber and the process further comprises the step of circulating a heat transfer fluid through the heat exchanger to heat the multi-component liquid in the chamber. 35 -43

35. A system for selectively removing a target liquid constituent from a multi-component liquid, the system comprising: a) a heater for heating the multi-component liquid in a chamber to a temperature at which a target liquid constituent selectively evaporates to form a vapor rich in the target 5 liquid constituent; b) a gas diffuser for bubbling a carrier gas through the heated multi-component liquid in the chamber; c) a gas circulation system for continuously removing a gas/vapor mixture from the chamber, the gas/vapor mixture comprising the vapor from step a) and the carrier gas from 10 step b); d) a condenser for condensing the vapor of the target liquid constituent from the gas/vapor mixture to form a condensate rich in the target liquid constituent; and, e) means for returning the carrier gas from step d) for use in step b). 15

36. The system of claim 35 wherein the heater, the chamber, the gas diffuser and the condenser are arranged in a vessel having one or more wall(s), the vessel further comprising a cooling jacket for cooling an outer peripheral portion of the wall(s) of the vessel, and a flow diverter arranged within the vessel for directing the flow of the gas/vapor mixture towards the cooled outer peripheral portion of the wall(s) of the vessel. 20

37. The system of claim 36 comprising a plurality of vessels arranged in series for selectively removing a plurality of target liquid fractions from a multi-component liquid, whereby selective removal of each of these fractions is achieved at progressively higher operating temperatures for each of the vessels in the series. 25

38. The system of claim 37 wherein each of the vessels is provided with a heater in the form of a counter-current heat exchanger.

39. The system of claim 37 or 38 wherein a heat transfer fluid is caused to flow counter 3 0 currently relative to the flow of multi-component liquid through the plurality of vessels.

40. A system for selectively removing a target liquid constituent from a multi-component liquid substantially as herein described with reference to and as illustrated in the accompanying representations. 35