GB2437516A

GB2437516A - Method and apparatus for purifying glycerine using filter membranes and a deionisation means

Info

Publication number: GB2437516A
Application number: GB0608190A
Authority: GB
Inventors: Bai Leng
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-04-26
Filing date: 2006-04-26
Publication date: 2007-10-31
Also published as: GB0608190D0

Abstract

A method for substantially purifying glycerine from liquids comprises passing the liquid through one or more filter membranes and a deionisation means. The filter membranes may be two or more membranes of different pore sizes and may be capable of micro-, ultra-, nano-or hyper-filtration. The deionisation means may use ion exchange, captive deionisation, electrodeionisation or decolourisation techniques. The method may further comprise steps of desalinising the liquid or adjusting parameters such as temperature, pressure, pH, hardness, softness and concentration and the liquid may be concentrated after purification by drying and/or reverse osmosis. An apparatus for substantially purifying glycerine from liquids comprises a first filter membrane located upstream of a deionisation means. The apparatus may further comprise a second membrane filter, a desalination device, conditioning means to adjust temperature, pressure, pH, hardness, softness, concentration, washing means to supply washing fluid to the filters and/or other components of the apparatus or heating or cooling means which may be coupled to a heat exchanger.

Description

DESCRIPTION

METHOD OF PURIFICATION

The present invention relates to a method and apparatus for purif'ing glycerine.

Distillation is a widely used technique for the purification of a number of liquids, including glycerine. Distillation of glycerine can produce high-grade glycerine of up to or over 99.9% of purity. To avoid decomposition of glycerine (which has a boiling point is 290 C) and also to reduce fuel costs, very high vacuum conditions are often employed to distil the glycerine at a lower temperature. However, providing such a vacuum is expensive to implement and service. Despite the boiling point of glycerine being lowered by means of a vacuum, the fuel costs are still remain high and it is the major costs (account for approximately 80-90%) of the total glycerine purification. Furthermore, high temperature distillations may also produce glycerine having "burnt" taste/smell and may therefore affect some applications, such as toothpastes and pharmaceuticals, It also widely believed that when glycerine is heated over 150 C, it decomposes and produces acrolein (acraldehyde, or prop-2-enal), which is knosn to be poisonous.

Glycerine is used in a number of industries, each of which requires different purity profiles. For example, the pharmaceutical industry requires extremely pure glycerine, whilst other non-food industries are less stringent.

Glycerine is produced as a by-product in a number of industries, such as during the production of soap, oligochemicals and bio-diesel. Rio-diesel production is the major source of crude glycerine and the quality varies widely from producer to producer. Crude glycerine from biodiesel productions contains higher organic and inorganic impurities. Ionic impurities can be as high as 7- 10%; water content can be as high as 15-20%, whilst organic impurities can be as high as 10% or over, It will be evident that the production of bio-diesel will increase dramatically over the course of the next few years as it is a more environmentally friendly fuel and reduces the dependence upon crude oil based fuels, and it follows that an increase in the production of surplus of glycerine will be experienced. Oleochemical production is the traditional source of crude glycerine and tends to produce glycerine of a high quality. Crude glycerine from oleochemical producers contains high glycerol with very low salinity and lower water content. Soap production is another traditional source of crude glycerine, but the quality is often very poor and yield quantity relatively small.

Artificially-composted glycerine and glycerine obtained from fermentation is (zymotechnics) are other sources of glycerine. Artificial-composted glycerine was made from fossil oil in 1960 -1990, but volumes have greatly reduced due to high costs and the availability of glycerine from bio-diesel. Fermentation (zymotechnics) was developed late last century and has not been widely adopted since, It uses agriculture waste, such as cobs of corns. Glycerine produced by zymotechnics contains low glycerine and large amount of bio and organic impurities and large amount of water, requiring further concentration and purification.

Residua left over from glycerine distillations fall into categories of either organic or inorganic materials, the mixture of both having almost no commercial value and are difficult to separate. The residua produced in industrial glycerine processing plants is often in fairly large quantities. Such waste presents an environmental problem due to its organic and inorganic content and often the waste has a high content of glycerine.

CZ284042 discloses a process of retrieving crude glycerine from industrial waste or solution containing very low levels of glycerine by means of a membrane.

It is an object of the present invention to provide a method of purifying glycerine, without the need for high temperature distillation and/or extreme low pressure vacuums. It is also an object of the present invention to provide a method of purifying glycerine which is preferably both energy efficient and environmental friendly. Furthermore, it would be advantageous if the method would be able to purify glycerine to a pre-determined purification profile.

In accordance with the present invention, there is provided a method for substantially purifying glycerine from liquids, the method comprising the steps of passing the liquid through one or more filter membranes and a deionisation means.

The present invention therefore provides for a low cost, energy efficient and environmentally friendly processing technique which can be used in the purification of glycerine as well as the treatment and recycling wastes.

The term "substantially purify" is intended to mean the removal of some or the majority of impurities in a given liquid containing glycerine, which may or may not also include solvents, if the liquid is a solution. The term is also intended to refer to the refining of liquids containing glycerine which may usually take place by means of distillation etc. The use of selective material separations of membrane filtrations enable glycerine purifications to be controlled precisely. The purified glycerine can be produced at different grades, such as industrial grade, technical grade, food and pharmaceutical grade, etc., so as to match customers' requirements. Such manageable product grade selectivity in glycerine purification allows the glycerine producers additional benefits in cost savings and production efficiency.

Additionally, the present invention also provides for a low Costs, energy saving and environment friendly method for the purification of glycerine requiring: (1) low investment cost; (2) low production cost; (3) significant energy saving; and (4) reduced waste (wastes separated during the method and turned to valuable commodities).

The liquid may be passed through two or more filter membranes having different pore sizes.

The method comprises the step of deionising the liquid to substantially remove ionic impurities (either monovalent and/or multivalent ions). It will be evident to one skilled in the art that the deionising step may be performed using a number of means, such as ion exchange, captive deionisation or electrodeioiiisation techniques. The precise deionisation method and equipment will be dependent upon the liquid being purified and cost/efficiency parameters.

It will also be evident that the costs/efficiency of deionisation will depend upon the content levels of salinity/total amount of salts in the liquid under purification.

For example, if the liquid is crude glycerine containing a very low salt content, such as commonly derived from oleochemical productions, ion-exchange is able to produce satisfactory deionisation results. The latest available commercially Capacitive Deionisation Technology (CDT) offers low running cost to deionisation on low salinity solutions. If, for example, the liquid is crude glycerine containing high and very high salts content, such as found in crude glycerine from bio-diesel productions, electrodeionjsation (ED!) techniques offer cost effective performances in deionisation. ED! and ED! based deionisation modifications are almost the first line of choice of deionisatjon for the solutions with high salinity, such as glycerine liquids derived from current bio-diesel productions.

Preferably, the deionisation should be capable of removing all ionic impurities from the liquid, whilst avoiding the use of an additional deionisation processing. Modifications of electrodeionisation, which are based on the electrodialysis (ED) process, include a number of variations such as ED! (ED plus ion exchange resin membrane), CEDI (continuous EDI), EDIR (ED! frequent reversal), CEDIR (continuous EDI frequent reversal), etc. may also be employed in accordance with the present invention.

The ion exchange process should be able to remove almost all of ionic impurities from a given liquid at higher deionisation costs. Ion exchange can also be use to decolourise the liquid. It will be apparent that using ion exchange process to remove colour (bleaching) is much cheaper than using other bleaching methods such as activated carbon, as ion exchange resins can be re-activated (re-generated) and re-used repeatedly over a long period of time. The configuration of the ion exchange system may be either single, twin, triple or multiple ion exchange column set(s). The inclusion of an ion exchange system in a deionisatjon process enables extremely pure glycerine to be produced. Should an ion exchange system be employed, it may also be able provide for fine deionisation after the initial purification (if required) or as a stand-by deionisation device. More than one ion exchange systems may be provided if a continuous process is required. Parallel or multiple ion exchange systems will allow switching between individual ion exchange systems. For example, if a first ion exchange system is under reconditioning, a second ion exchange system may be brought online so as to provide continuous deionisation, or vice versa. When an ion exchange set has completed its reconditioning, it can then be put on stand-by, so that it is ready to replace the other sets when due reconditioning.

Due to the nature of ion exchange resins, it is preferred that the ion exchange system must be reconditioned regularly when the ion exchange resins are saturated. Ion exchange are often employed to work in set groups of columns: (1) Two column set:-a cation exchange resin column and an anion exchange resin column; (2) Three column set:-a cation exchange resin column, an anion exchange resin column and a mixed column which contains both cation and anion exchange resins; and (3) One column set:-a single mixed column contains both cation and anion exchange resins.

Decolouring or product bleaching may be required if the glycerine is intended to be used in a number of industries, such as in food and pharmaceuticals.

Ion exchange resins may therefore be used to "absorb" or remove colours while they remove ions out of the solutions. During the ion exchange process in the glycerine purification, final remaining ions are removed, as well as the colours. Due to the "re-generation" properties of ion exchange resins, ion exchange resins can be used repeatedly hence to reduce the production costs in glycerine purifications. Activated carbon and bleaching may also be employed if is still an additional option in the glycerine purification if the decolourisation by ion exchange does not meet product requirement. Examples of bleaching include the use of chlorine or sulphur gas.

The method may also further comprise the step of substantially desalinising the liquid so as to substantially remove the content of salts in the liquid.

If appropriate, the deionisation wastes may be additionally treated. Wastes produced from deionisation processes will tend to mainly comprise water and inorganic materials, such as salts. If a large amount of water exists in the deionisation waste, then the water may be used as the flashing agent in the is deionisation process. A Reverse Osmosis (RO) process may be used to remove excess water and is a low cost very efficient technology to separate water from organic and inorganic impurities. Water may therefore be collected from the waste via a RO process, purified and reused in the method or discharged into the environment if appropriate. If the waste contains large amount of glycerine, then the product itself may be used as the flashing agent in the deionisation process, and a further process required to retrieve the glycerine. The retrieved product may then be returned back to the deionisation process if efficient deionisation techniques are used, due to higher salinity. Otherwise, further out-of-line desalination processes may be required to remove salt contents from the glycerine, if the product recovery is considered necessary.

If the impurities removed from the liquid comprise inorganic materials (as can be produced from the purification of crude glycerine produced from bio-diesel and oleochemical productions), then inorganic materials recovered from the waste may be further processed into commercially valuable products. For example, recovered inorganic materials may be processed into an inorganic fertilizer (Potassium Sulphate, K2S04) or other commercially useful minerals.

Prior to, or during purification andlor deionisation, the liquid may be conditioned so as to adjust one or more parameters. The parameters may be selected from one or more of the following: temperature, pressure, p1-I, hardness, softness and concentration. It is therefore preferably that the liquid is checked and conditioned appropriately so as to ensure that the method is as efficient as possible, and in particular, that the filter membranes are operating at their fufl is efficiency. For example, a specific pH, temperature and working pressure may be required for a given filter membrane to operate. Other parameters, such as hardness of the liquid may also important for the correct operation of filter membranes (such as in reverse osmosis membranes).

It' the glycerine undergoing purification is required to be (or remains) in a solvent, then after the purification it may be concentrated if required. It will he apparent to one skilled in the art that a number of known concentration methods may be employed. For example, the glycerine may be concentrated by means of drying and/or reverse osmosis. Drying will not only remove water, but other evaporable liquid, such as methanol. As drying may be fairly costly, it is preferable that the glycerine is concentrated first by removing as much water as possible from the liquid before employing a heated evaporation drying process.

Reverse Osmosis (RO, and also referred to as Hyper-filtration) technique may be used to remove water out of a the liquid and such a technique can save a considerable amount of energy than the heated water evaporation. Furthermore, water produced from RO concentration can be further treated and turned into pure water if required.

If a dryer is used in accordance with the method, it is preferred that a vacuum dryer is used to evaporate the exceeding water at much lower temperature than 100 C and so as to help reduce energy costs. To avoid possible decomposition of the glycerine during the drying process, the product drying temperature must be controlled below the temperature which could cause the glycerine to decompose on all the heating surfaces making directly contact with the liquid.

If required, the step of deionising the liquid may occur prior to the liquid passing through the one or more filters and/or conditioning and/or concentration.

The two or more filters may be capable of micro-filtration, ultra-filtration, nano-filtration or hyper-filtration. Micro-filtration is intended to remove large molecules from the liquid and to prepare quality feed for the next membrane filter in the method. Pre-filtration improves working efficiency of membranes used in ultrafiltration, so that less clogs and flushes are experienced and to maintain membrane durability. I'raditionally used filtration techniques for the purification of glycerine employed the used of sands, activated carbon and ceramics filtering and these techniques may still be used if required or existing methods require -10-adaptation. However, such traditional techniques may prove to be more expensive (than membrane filters) in terms of production cost if the crude glycerine is of a poor in quality and more waste will be produced. The pore-sizes of the filter membranes can be selected to reject unwanted particles and molecules to prepare clean feed for ultrafiltration process. Well prepared feed material improves productivity, reduces operation costs and prolongs the durability of the filter membranes. The filter membrane pore size will be selected according to the quality of feed crude glycerine. The quality or cleanness of the filtrates will also be dependent upon the selection of pore sizes of filter membranes.

The micro-filtration is not essential and can be omitted in order to save costs of equipment and production. This may be appropriate, where the crude glycerine has a relatively low concentration of impurities, or the impurities are of a small particle size.

Ultra-filtration is intended to remove the majority of the organic impurities is and is capable of purifying the feed glycerine up to certain high degree of purity (such as for industrial use). The rejection of the particular size/molecular weight of impurities can be determined by the selection of the particular type of ultra-filter membranes and pore size. The quality of the filtrates will also largely depend upon the selection of the ultra-filter membranes. Productivity of the ultra-filtration will depend upon the selection of membrane pore size or molecular weight cut-off size, as well as the quality or cleanness of the feed crude glycerine.

For many applications, quality of purified glycerine produced by ultra-filtration alone is acceptable, after deionisation and drying. If required, an additional and filtration process can be employed, such as a nano-filtration process.

Ultrafiltration is a term describing a wide range of filtering. The pore size of ultra-filter membrane may selected in the range of 0.1 jim (100 nanometre) to 0.002 p.m (2 nanometre), or a molecular weight cut-off size from 300,000 Dalton down to 1,000 Dalton. For glycerine purification, ultrafiltration can either achieve industrial grade or pharmaceutical grade purities depending on the selection of membrane pore sizes or molecular weight cut-off sizes. For example, (a) a 0.002 p.m poresize (1,000 Dalton) may be used to obtain pharmaceutical grade purity (and nanofiltration may not be required); or alternatively, (b) a large pore size, for example 0.1 p.m (300,000 Dalton) will result in poorer purity which may require further fine filtration(s) for making pharmaceutical grade glycerine.

Nano-filtration is intended to remove organic and inorganic impurities.

By employing nano-filtration, extremely pure glycerine can be produced. The rejection of organic and some of inorganic impurities during the nano-filtration process will depend upon the selection of the membranes according to the purity requirements of the purified product. Nano-filtration may be carried out either prior to, or after deionisation depending on the requirements for the purified glycerine.

Hyper-filtration is intended to remove excess water from the glycerine and is described herein above.

Preferably, the liquid is passed through the two or more filters sequentially. If required, the one or more filters may be conditioned with a wash solution prior to purification. Such a wash solution may simply be water so that the filters are wetted prior to the fluid being processed. -12-

The glycerine may be heated or cooled to a pre-determined temperature prior to or during purification. The pre-determine temperature of the glycerine will be dependent upon the operational temperature range of the membrane, but preferably, the pre-determined temperature is within the range of 45 C to 190 C.

More preferably, the pre-determined temperature is within the range of 50 C to 180 C. It will be apparent that the crude glycerine may be in a cold or hot/warm format, depending upon how it is supplied. For example, the two conditions when the crude glycerine has been delivered are either: (a) cold, after storage or transportation over a period of time; or (b) hot or warm, if piped in directly out of a production plant.

If the crude feed glycerine is cold, or at a temperature below the lower temperature limit required by a given protocol optimised for the purification of glycerine, then it requires heating. By exchanging the remaining heat from purified glycerine which requires cooling, the liquid feed can be heated without the need for, or greatly reducing the requirement of additional energy. The crude liquid is then purified according to the method when it has reached the minimum temperature requirement.

Alternatively, if the crude feed glycerine is hot, or its temperature is higher than the upper temperature limit required by a given protocol optimised for the purification of a glycerine, then it requires cooling. If the temperature of the hot feed is not much higher than the limit defined in the protocol, the exceeded heat can be used either to maintain the temperature of the feed in production, or to warm up the cold feed if such heat is needed. If the temperature of the hot feed is -13 -much higher than the upper limit of the protocol, the exceeded heat it carries can be used in one or all of following purpose(s): a) as a heat source for a heat exchange device so as to heat up the purified glycerine prior to being dried. Utilising the heat remains in the hot feed s to pre-heat the final product helps in energy saving product pre-heating process; b) to adjust feed concentration:-feeding the hot crude glycerine into a vacuum dryer to remove an initial amount of water. Removing part or the majority of water from the feeds will reduce feed volume hence saving energy in pumping and processing efforts in the production and the concentrationldrying of the final product; and c) if the temperature of the feed still higher than the upper limit of the protocol, the heat can be used to keep the feed warm in production. This can be achieved by lining up the pipes close to each other. The manner of "counter-current" piping arrangement gives better heat exchange efficiency between the Is neighbouring pipes. Other pipe arrangement can also be considered.

It is preferred that the glycerine is not heated to its boiling point (290 C) as the method is intended to replace the requirement of distillation during the purification. It is also preferred that the glycerine is heated or cooled by means of heat recovery from within a step in the method. A number of heat recovery means may be employed and these will be apparent to the skilled addressee, for example, the heat recovery may be by means of heat-exchangers.

With regard to the preferred temperature of the crude glycerine to be purified, it will be evident that the precise temperature will be dependent upon the constituents of the crude glycerine, preferred operational temperature of the filter membranes and purification protocol. As crude glycerine has a lower freezing point when it contains water, the crude glycerine will be able to pass through the one or more filter membranes as far as the temperature is higher than its freezing point. As glycerine has a higher viscosity at lower temperature, it therefore requires more effort to pass the glycerine through the filter membranes, It follows that potentially any temperature between the freezing point of the glycerine and the maximum temperature allowed by the filter membranes can be employed, It will also be evident that should a number of different materials be used to make filter membranes, then the temperature of the crude glycerine may be limited to that of the filter membrane with (he lowest temperature tolerance. It has been noted that crude glycerine shows a satisfactory lower viscosity and high liquidity when above 50 C and at around 80 C or higher, the liquidity of glycerine is very similar to that of water. Therefore, by maintaining glycerine at a certain working temperature, the viscosity is reducedlliquidity increased and it is easier to pass the Is liquid through the filter membrane(s).

The method may also utilise pre-heating as an energy saving measure can offer additional energy saving in the glycerine drying process. Due to the properties of the filter membranes and the ion exchange resins, the temperature of deionised liquid will usually be low. Therefore, heat exchanges may be used to extract as much heat as possible from other heat recoverable sources prior to a heated evaporation drying process. Sources of such heat may be from the initial crude glycerine (if the crude glycerine is supplied to the method already in a hot state), a hot final product (after the liquid has been subjected to a dryer is hot, heating apparatus (such as a dryer, hot steam or hot oil), and/or multi-level heat exchanges in order to maximize the heat recovery and minimize the loss of the heat. The final product may also be cooled down, or partially cooled down by passing its heat to a coolant. If required, the final product may also be subjected to further heating/drying so as to remove the majority or all of the solvent content.

If appropriate, then additional glycerine may be recovered from waste material and residua. By the nature of the method, the filtration processes will produce a small amount of residua or wastes which may contain certain amount of glycerine. Glycerine recovery may be possible from such waste material and the method may also incorporate the step of recovering product from waster materials and residua.

It has also been found in experimental procedures that dilution of the crude glycerine greatly increases the filtration efficiency and deionisation work load and therefore it is also preferred that the crude glycerine is diluted to a pre-determined factor prior to undergoing purification.

In accordance with a further aspect of the present invention, there is provided an apparatus for substantially purifying glycerine from liquids, the apparatus comprising a first filter membrane located upstream of a deionisation means.

The apparatus may further comprise a second membrane filter, wherein the first and second filter membranes have different pore sizes and are arranged to allow the sequential passage of fluid through the filters. Preferably, the first filter membrane has a pore/molecular weight cut off size greater than that of the second filter membrane. If more than two filter membranes are employed in the -16-apparatus, then preferably the pore /molecular weight cut off sizes of the filter membranes become successively smaller.

If appropriate, one or more of the filter membranes may be replaced with chemical or sephadex filters. The apparatus therefore can be used to implement the method as herein above described.

Preferably, the apparatus further comprises a deioniser for substantially removing mono-valent and multi-valent ions from the liquid. The apparatus may further comprise a desalination device for substantially removing salts from the liquid. Additionally, the apparatus may further comprise a conditioning means to adjust one or more parameters of the liquid selected from the following: temperature, pressure, pH, harness, softness and concentration. It will be evident that the conditioning means may be more than one device, such as a heater to increase the temperature, or a device for supplying reagent (for example a pH buffer) to the liquid. A concentration device may also be provided to remove moisture and excess water from the liquid, either prior to, during, or after the two or more filters. Many concentration devices may be employed in the present invention, such as a dryer or a reverse osmosis filter for example. The deioniser, desalination device, conditioning means and concentration device may be located either upstream, between, or downstream of the first and second filters.

The two or more filters may be capable of performing one or more of the following types of filtration: micro-filtration, ultra-filtration, nano-filtratjon and hyper-filtration. As herein above described with reference to the method, filters used for micro-filtration may be capable of removing large molecules from the liquid and to prepare quality feed for the next membrane filter. Ultra-filtration -17 -may be capable of removing the majority of organic impurities and therefore purifying thefeed liquid up to certain high degree of purity (such as for industrial use, or pharmaceutical grade depending upon the selection of membrane pore sizes). Nano-filtratjon may be capable of removing organic and inorganic impurities so as to produce extremely high pure liquids. Hyper-filtration may be capable of removing excess water from the liquid.

The apparatus may further comprise a washing means adapted to supply a washing fluid to the filters and/or other components of the apparatus if required.

Such a washing means may be needed to clean the filter membranes or various components of the apparatus and are often referred to also as "flush fluids".

The apparatus may further comprise a heating or cooling means for heating or cooling the liquid. It is preferred that the heating and/or cooling means is coupled to a heat exchanger and this will therefore allow the apparatus to operate efficiently and reduce the requirement for external energy to power the apparatus. The heating means may comprise a heater, boiler, or similar device. A heater may be selected from one or more of the following: an oil heater (using hot oil as heating media, provides heat at normal pressure); a steam boiler (using hot steam as heating media, operating under high pressure); and an electrical heater (producing heat by using electricity). The heating means used will of course largely be dictated by liquid being purified and efficiency requirements etc. In yet another aspect of the present invention, there is provided glycerine purified from a liquid as purified according to the method as herein above described. -18-

A specific embodiment of the present invention will now be described, by way of example only, with reference to the following figure(s) in which: Figure 1 is a schematic flow diagram of a possible method of purifying glycerine in accordance with the present invention; and Figure 2 is a schematic diagram of an apparatus that can be used to implement the method of the present invention.

With reference to Fig. I, there is provided a schematic flow diagram illustrating the purification of glycerine from a crude glycerine source. The processing is characterised into three stages, the main process 10, energy saving stages 12 and waste treatment stages 14.

In the main process 10, the crude glycerine from a given source is used as the feed input 16. The temperature of the feed input 16 is first assessed 18 and if it is too hot, then it is cooled down. Alternatively, it the feed input is too cold 20, it is warmed up 22 to the appropriate temperature. The crude glycerine then undergoes conditioning (to control the pH, hardness, softness etc.), micro-filtration 24 and ultra-filtration 26. If the glycerine is required in an ultra-pure form 28, then it undergoes nano-filtration 30. The glycerine then undergoes a deionisation and decolourisation 32 and the quality control checked 34. If the quality control check is not satisfactory, then the glycerine is deionised and decolourised 32 again. If concentration is required 36, then the glycerine undergoes concentration 38 after which the glycerine is then put through a heat exchanger 40 so as to adjust the temperature of the product to that required and the final product is released 42. For example, if the product requires drying, then it can be heated, whereas a hot feed may be cooled down. -19-

In the energy saving stage 12, the glycerine can enter a heat-exchanger 40 so as to reduce the heat of the glycerine and transfer the heat to glycerine in another part of the process. Additionally, a dryer 44 can be employed to dry the glycerine if required. Also, the pre-concentratjon 46 of the glycerine can be adapted prior to the glycerine undergoing conditioning and mciro-filtration 24.

During the waste treatment stage 14, waste in the form of residua is further processed so as to extract glycerine from the waste and to divide waste into commercially usable products. Residua from controlling and micro-filtration can be treated for residua separation 48, the liquids returned to the main process and solids disposed of. Residua from the ultra-filtration 26 (and nano-filtration 30 if required) then undergoes residua separation and materials recovery 50 and again, the liquids returned to the main process 10 for further processing and solid wastes disposcd of accordingly. Waste materials from the deionisation and decolourisation 32 undergoes water purification, separation of rejections 52 so as is remove the waste into pure water, organic and inorganic by-products 56, or recovered feed to go back to deionisation and decojourisation 32. The last step in the waste treatment stage 14 is wastes treatment (including solid waste), which divides waste material into pure organic & inorganic by-products 56 and waste 58.

After deionisation, the product may also be feed through an ion exchange process, to perform further decolourisation, as well as fine and final deionisation.

Decolourisation removes inorganic impurities, in audition to removing colours.

In the case of complete deionjsatjon (i.e. all salt removed), if the removal of colour in the glycerine is still required, then the ion exchange may be used for this -20 -purpose. Decolourisation is ideally carried out after the primary deionisation, but also be carried out immediately after the filtrations, such as: a. immediately after filtrations and acts as "deionisation plus decolourisation" in the cases of very low inorganic impurities (very low salt contents), or b. immediately after the filtrations and acts as primary deionisation (plus decolourisation) with high salt content if there is no concerns in production and/or operation costs.

Electrodejonjsatjon (EDI) is able to remove colour because it utilises an ion exchange resin embedded membrane. Therefore it follows that the ion exchange resin embedded in the EDI may be able to remove colour in addition to performing deionisation and such an ion exchange resin may be used as an additional option, reserve/stand-by device.

With reference to Fig. 2, the schematic diagram shows the outline of an apparatus that can be used to purif' crude glycerine and common features to that show in Fig. 1 are shown with the reference number prime.

At the crude glycerine feed entrance point 16' of the glycerine purification process, the quality of feed crude glycerine is monitored and feed conditioning are carried out when necessary. Feed material quality monitoring and conditioning are achieved by quality monitoring and control devices. The major concern on the feed crude glycerine quality is the pH and temperature: (a) the pH of feed crude glycerine are checked and the feed are neutralized at this point making the feed pH to meet the equipment specifications; and (b) the temperature is checked and hot or cold crude glycerine feed is pumped into the processing system according to system configuration.

Device A is the concentrator and this device utilises the heat contained by the crude glycerine feed to remove some or majority part of water content from the feed. It is an energy saving procedure I measurement.

Device B is the heat exchanger and this device warms up the crude glycerine feed if the feed temperature is below the temperature required by the next processing equipment.

Device C is the pre-treatment device and this device is designed to remove very large size particles, flocks and remaining fatty acid.

Device D is the ultra-filtration system and this system consists of ultrafilter membrane modules, pumping and control devices. It removes majority of organic impurities from the feed crude glycerine. The filtrates of ultrafiltration are also essential quality feed if required further fine filtration process. The filtrates of ultrafiltration can then either feed into deionisation and decolourjsatjon process or nanofiliration for extreme pure separation process. Rejections or residua from the ultrafiltration processes are processed and fed back to the system.

Device E is the nano-filtration system and the system consists of nanofilter membrane modules, pumping and control devices. Nanofiltration process makes extremely pure glycerine possible, after the further processes of removing ionic impurities and water. There is a relatively high rejection rates of nanotiltration, include glycerine itself, depending on the selection of molecular weight cut-off rates. Therefore, total surface area of the nanofiltratiori membrane must be -22 -provided to cope with the production capacity. Recovery of rejections is necessary to avoid production loss.

Device F is the deionisation and decolourisation system. Ion exchange resins also decolour the glycerine while performing deionisation. The Primary deionisation device is an electrodeionisation system, including any such kind of alternatives or modifications of electrodejonisatjon devices is considered to be the primary deionisation device at this stage of processing. The primary concern of using electrodeionisatjon system is to deionise the crude glycerine from biodiesel productions of which very high ionic impurities are common. It will be evident to the skilled addressee that should better deionisation technologies be available, they should be used to replace the electrodeionisation system if appropriate. If the crude glycerine feed contains very low ionic impurities, deionisation process can be either processed by this device or by-passing this device to use ion exchange system.

Device G is a deionisation system, such as an ion-exchange system and provides an option for the deionisation and decolourisation process. The ion exchange system can be configured into single, twin, triple or multiple/parallel ion exchange column sets filled with either single or mixed ion exchange resins.

Continuous production is made available by multiple/parallel ion exchange sets, but not the single ion exchange column. An ion exchange system may be required for producing extreme pure glycerine, unless device F is able to produce the same.

Device H is the concentration system and this system utilises the membrane technology to remove part of water out of the glycerine and saves energy costs on the later heated drying process. A Reverse Osmosis (RO, or [-lyperfiltration) system is used to concentrate the glycerine.

Device I is a heat exchange device and can raise the temperature of the glycerine by utilising recoverable heat from other heat sources rather than the heat directly from heater/boiler. This device serves as an energy saving and recovery measure. If no energy saving is required, this process can be by-passed. This device has following principle inputs and outputs: i. hot crude glycerine feed delivered at the processing entrance point; ii. hot final product which is to be cooled; iii. Heating media came from the drier; and iv. (optionally) heating media directly from the heater/boiler, if necessary.

Multi-level heat exchange modules allow the best recovery of heat from all of the recoverable heat sources at low, medium and higher temperatures. The final product can then flow out from this device and it serves as a cooling device for it.

If the glycerine is dried directly at the dryer, there is no need to feed the product through this device, nor the installation of this device.

Device J is the dryer and this device dries the glycerine by evaporating the water content out of the glycerine. A vacuum condition may make water evaporate at lower temperature, hence saving energy and production costs.

Alternatively, or additionally, a multi-stage drying process may provide better cost effective drying. Many types of dryers are able to serve the product drying purpose, such as steam, hot oil, electrical dryers. In-flow: product and heating media if any. Out-flow: dried product and hot heating media if any. Oil requires -24 -very low working pressure. Steam requires a high working pressure. Electrical dryer requires no working pressure. The temperature must be well controlled to be below possible decomposition temperature of glycerine on all direct or indirect contact surfaces with the glycerine inside the dryer.

Device K is a heating device and the heating device provides heated media for product drying process. The heated media can be: (a) hot oil -no high working pressure required, equipment is less expensive; (b) steam -high working pressure required, equipment is expensive; or JO (c) any other possible heating media which is able to produce the temperature required by the drying process of glycerine.

Device L is the pure water supply tank, which provides pure water for various processing stages, which require pure water, such as deionisation processes or waste treatment etc. Devices Ml and M2 are chemical supply tanks, which store chemicals, acid and alkaline solutions required for crude glycerine feed, p1-1 conditioning and ion exchange system reconditioning.

There are a number of essential processing quality control points in the glycerine purification process. They are: (a) feed crude glycerine quality monitoring and conditioning, located at the entrance point of the crude glycerine feed, as described earlier; (b) feed crude glycerine temperature monitoring and flow controls -located at the crude glycerine entrance point after the control point, It also checks -25 -the temperature of the feed and divers feed to different processing route accordingly; (c) flow rate control before Device D. This control point controls the flow rate according the specifications of Device D; (d) deionisation quality controls. The two quality control points are at the out-flows of Device F and Device G and they serve the same purpose on deionisation quality monitoring and controls by checking product resistivities.

Any QC failed flow is returned to the system and re-processed.

(e) product dryness control. This control point monitors and controls the quality of product drying. Any quality control failed product is returned back to drying process.

(f) symbols: indicates flow sensor / meter indicates pH sensor indicates temperature sensor / thermometer indicates resistivity/conductivity sensor indicates water content sensor Glycerine Recovery and Waste Treatment -all filtration devices produce rejections of organic impurity and deionisation devices produce ionic concentrates. Water is produced by concentrators and the dryer. Glycerine recovery and wastes treatment systems: a. System 100 processes rejections and wastes produced by microfiltration and ultrafiltration processes. Glycerine content are separated from the waste and returned back to the -26 -microfiltration process if any, or ultrafiltration process.

Organic impurities can be further processed and turned into organic fertilizer.

b. System 102 processes rejections from nanofiltration. Glycerine are returned back to nanofiltration process and organic impurities can be further processed and turned into organic fertilizer.

c. System 104 receives and processes ionic impurities and water.

Water is extracted from the rejections by RU process and the ionic concentrates rejected by RO process can be further processed and turned into inorganic fertilizer or mineral by-products.

d. System 106 indicates a water purification system. It purified the water collected from concentrators, dryer and waste treatment. RU device separates water from ionic impurities or inorganic salts. An small deionisation device removes the ions from water, and pure water is produced. The pure water is then pumped into the pure water supply tank for production uses or for sale.

e. Methanol Recovery -there is very small amount of methanol in the glycerine from biodiesel productions. Methanol is able to go through all of the filtration and deionisation processes due to -27 -its molecular weight is smaller than glycerine. However, methanol evaporates from the glycerine under the heat in the dryer. A condenser installed with the dryer is able to collect methanol from the low temperature distillates come out of the dryer.

Processing procedures and Flows -brief outlines of pipelines layout marked with flow directions indicate the production procedures and the flows of processing. This serves as a general guidance for the glycerine purification processing techniques.

Equipment and Devices -all equipment andlor devices are given as guidance. Actual equipment and/or devices to be installed will be determined by individual producers to their choices. Production operating parameters should follow the specifications and operating guidance issued by manufacturers of the installed equipment andlor devices.

The invention is not restricted to the details of the forgoing embodiment.

Claims

-28 -

CLAIMS

I. A method for substantially purifying glycerine from liquids, the method comprising the steps of passing the liquid through one or more filter membranes and a deionisatjon means.

2. A method as claimed in claim 1, wherein the liquid is passed through two or more filter membranes having different pore sizes.

3. A method as claimed in either claim I or claim 2, wherein the deionising means utilises ion exchange, captive deionisation, electrodeionisation or decolourisation techniques.

4. A method as claimed in any one of claims I to 3, wherein the method further comprises the step of desalinising the liquid to substantially remove salts.

5. A method as claimed in any one of claims 2 to 4, wherein prior to, or during purification and/or deionisation and/or desalination, the liquid is conditioned so as to adjust one or more parameters.

6. A method as claimed in claim 5, wherein the parameters are selected from one or more of the following: temperature, pressure, p1-I, hardness, softness and concentration.

7. A method as claimed in any preceding claim, wherein after purification, the concentration of the glycerine is adjusted to a pre-determined value.

8. A method as claimed in claim 7, wherein the liquid is concentrated by means of drying and/or reverse osmosis.

-29 - 9. A method as claimed in 8, wherein the step of deionising and/or desalinising the liquid occurs prior to the liquid passing through the one or more filters and/or conditioning and/or concentration.

10. A method as claimed in any one of claims 2 to 9, wherein the two or more filters are capable of micro-filtration, ultra-filtration, nano-filtration or hyper-filtration.

11. A method as claimed in claim 10, wherein micro-filtration removes large molecules from the liquid.

12. A method as claimed in either claim 10 or 11, wherein ultra-filtration removes the majority of the organic impurities.

13. A method as claimed in any one of claims 10 to 12, wherein nana-filtration removes organic and inorganic impurities.

14. A method as claimed in any one of claims 10 to 13, wherein hyper-filtration removes excess water from the liquid.

15. A method as claimed in any one of claims 10 to 14, wherein the liquid is passed through the two or more filters sequentially.

16. A method as claimed in any preceding claim, wherein the method further comprises conditioned one or more filters with a wash solution prior to purification.

17. A method as claimed in any preceding claim, wherein the liquid is heated or cooled to a pre-determined temperature prior to or during purification.

18. A method as claimed in claim 17, wherein the liquid is not heated to its boiling point.

19. A method as claimed in claim 17 or 18, wherein the liquid is heated or cooled by means of heat recovery from within a step in the method.

20. A method as claimed in claim 19, wherein the heat recovery is at least partially achieved by means of heat-exchangers.

21. An apparatus for substantially purifying glycerine from liquids, the apparatus comprising a first filter membrane located upstream of a deionisatjon means.

22. An apparatus as claimed in claim 21, wherein the apparatus further comprises a second membrane filter, wherein the first and second filter membranes have different pore sizes and are arranged to allow the sequential passage of fluid through the filters..

23. An apparatus as claimed in either claim 21 or 22, wherein the apparatus further comprises a desalination device.

24. An apparatus as claimed in any one of claims 21 to 23, wherein the apparatus further comprises a conditioning means to adjust one or more parameters of the fluid selected from the following: temperature, pressure, pH, harness, softness and concentration.

25. An apparatus as claimed in any one of claims 21 to 24, wherein the apparatus further comprises a concentration device to remove moisture and excess water from the liquid.

26. An apparatus as claimed in claim 25, wherein the concentration device comprises a dryer or a reverse osmosis filter.

27. An apparatus as claimed in any one of claims 22 to 26, wherein the two or more filters are selected from one or more of the following types of filters: micro-filtration, ultra-filtration, nano-filtration and hyper-filtration.

28. An apparatus as claimed in any one of claims 21 to 27, wherein the apparatus further comprises a washing means adapted to supply a washing fluid to the filters and/or other components of the apparatus.

29. An apparatus as claimed in any one of claims 21 to 28, wherein the apparatus further comprises a heating or cooling means for heating or cooling the liquid.

30. An apparatus as claimed in claim 29, wherein the heating andlor cooling means is coupled to a heat exchanger.

31. A liquid as purified according to the method as claimed in any one of claims I to 20.