The present invention is relevant to a method for the treatment of a composition and a plant for performing such method.

The preset invention finds advantageous application in the field of oils and/or fats, to which the following description makes explicit reference.

BACKGROUND OF THE INVENTION

The stripping processes with vapour (or gas) at pressures between approximately 25mmHg (33.33mbar) and 0. ImmHg (0.13mbar) have long been commonly used in industry to remove volatile minor components, undesired or of particular interest, from substrates of various nature.

The vapors (or gases) currently used as stripping fluids, or sparging fluids, in this type of processes are typically steam, inert gases (such as nitrogen and argon) and light hydrocarbons (gaseous at ambient temperature and atmospheric pressure) . Among the applications of the steam (or gas) stripping we can recall: the deodorization and the deacidification of oils and/or fats (examples of base compositions to be treated) .

The deacidification (also called physical refining) and the deodorization are part of the processes of refining of oils and/or fats.

The deacidification of oils and/or fats is a process in which the content of free fatty acids is reduced and it is used as preparatory to a subsequent chemical neutralization or to bring the acidity directly to values suitable for successive uses (for example, below 0.2% - mass of fatty acids compared to total mass - for industrial uses and below 0.1% for food uses )

The deodorization is usually the last operation done in the refining of oils and/or fats. In this process are removed volatile substances, often malodorous or having undesirable characteristics (sometimes valuable); among these we can remember: pesticides, free fatty acids, aldehydes, ketones, alcohols, hydrocarbons, tocopherols, sterols. Sometimes the deodorization and the deacidificat ion are realized simultaneously.

The deodorization and the deacidification of oils and/or fats are generally carried out using steam or an inert gas as stripping fluid.

It should be noted, however, that the use of steam as the stripping fluid has several disadvantages:

(relatively high) energy cost related to the vaporization of water;

production of polluted water, which increases considerably if, as often happens, the water vapor is extracted from the stripping zone by means of steam-jet ejectors and condensed in mixing condensers, usually barometric condensers, in which the steam is condensed by direct contact with a large flow of water at low temperature; and hydrolysis of glycerides and formation of emulsions.

Several ways have been tried to overcome the environmental problems related to the discharge of polluted water, for example by treating, cooling and recycling the water output from the mixing condensers or (see for example G.B.

Martinenghi (1964) GB1080057) eliminating the ejectors upstream of the condensers and using surface condensers where the steam deposites on elements cooled down to temperatures below -20°C. In the latter type of equipment the consumption of steam, necessary to supply the ejectors, and the production of polluted water, deriving from the condensation of the steam, are greatly reduced. What proposed is, however, complex and expensive, in particular because of the system of "dry condensing" of the steam, which requires the use of very low temperatures (as already mentioned, below -20°C) and (in order to maintain the efficiency of the heat exchange) the frequent (in some cases continued) cleaning the surfaces of the condensers, which must be freed from the ice that forms.

Relatively recent patents suggest the use of non-condensable inert gases as stripping fluid. In particular, we cite here patents US 5,241,092 and US 5,374,751 (relevant to the deodorization of the oils and/or fats), which, however, retain the use of steam-jet ejectors to generate the vacuum; and the U.S. patent application with publication number 2004/0253353 Al, disclosing the use of a vacuum system that does not use steam ("non-steam vacuum source"), which must have high flow rate and, therefore, high cost and energy consumption. These methods solve some of the problems related to the use of steam, for example the hydrolysis of the glycerides and the formation of emulsions, but not that of the energy cost, and therefore the indirect environmental impact, of the evacuation of the stripping fluid from the stripping zone by means of pumping systems.

DE102008007843 discloses the separation of organic impurities from fat or fish oil by short-path distillation. Short-path technology implies that distillation and condensation are realized by the same device, substantially in the same zone or in any case with the condensation that is obtained within a space where the distillation takes place.

The device described in this document has several drawbacks. In particular, we note that: it is necessary to operate in all cases at pressures below 1 mbar (higher pressures are not suitable for short-path technology) , and therefore spend a considerable amount of energy (with the consequence of an increase in costs) ; structure and geometry of the device are relatively inflexible and expensive (in order to operate at high vacuum) ; using the short-path technology only a poor deodorizing (removal of malodorous endogenous substances) of oils and/or fats is achieved.

US2004 /0253353 Al (already mentioned above) discloses a deodorization process, which uses non-condensable gases (in particular, nitrogen; see for example line 5 of paragraph [0050], line 2 of paragraph [0051] and line 7 of paragraph [0055]) as the stripping fluid, such non-condensable gases are, by definition, never condensed. Note, also, that the condensers foreseen by this document are dimensioned only to condense the substances distilled from the oil and not the stripping fluid.

US3622466 relates to a method for recovering water-free fatty acids by selective condensation. However the conditions at which the different components of the apparatus are able to operate are not clearly described, nevertheless it seems that the a relatively high pressure, exceeding 25mmHg (more precisely exceeding 1 inch of mercury, as indicated in column 3, lines 22-25) is maintained inside the device.

US4089880 discloses a process for refining of fatty oils. In this case the stripping fluid is condensed downstream of the suction device 70 (specifically in the condenser 71 - see in particular from line 58 of column 11 to line 7 of column 12). The condenser 75 therefore is not dimensioned and does not have the heat exchange capacity to allow the condensation of the stripping fluid. GB1080057 (already mentioned above) relates to a process for the refining of glyceride oils.

However the conditions at which all the components of the equipment can operate are not clearly described. Inter alia, note that the condensation of the distillate is carried out at very low temperatures (below -20°C - page 3, lines 115-121). The condenser described in GB1080057 is, therefore, unsuitable to operate at higher temperatures.

None of the patents mentioned above provides or suggests a solution that allows reducing drastically the cost of evacuating the stripping fluid from the stripping zone at pressures between approximately lOmmHg (13.33mbar) and 0. ImmHg (0.13mbar). It is therefore still open the request by the industry, of a process, with reduced environmental impact, which can be carried out with simple and inexpensive equipment. In particular, it is felt the need to operate at low pressures at low cost.

In this respect, it should be noted that realizing the stripping at low pressures allows reducing the quantity of stripping fluid employed and the stripping temperature and consequently the operating cost of the plant, as well as the losses of end products along with improving the quality of the latter .

Aim of the present invention is to provide a method for the treatment of a composition and a plant for performing such a method, which overcome at least partially the drawbacks of the state of the art and are, at the same time, simple and inexpensive to produce and manage.

SUMMARY

In accordance with the present invention, a method for the treatment of a base composition and a plant are proposed as recited in the following independent claims and, preferably, in any one of the subsequent claims depending, directly or indirectly, on the independent claims. Unless explicitly specified to the contrary, the following terms have the meaning indicated below.

By oils and/or fats we mean fatty substances of vegetable origin (for example, but not limited to rapeseed oil, coconut oil, soybean oil, palm oil, olive oil) or of animal origin (for example, but not limited to tallow, lard) or biologically synthesised from other living beings. The oils and/or fats can be liquid or solid at ambient temperature. According to some embodiments, the oils and/or fats can be by-products of processing or waste (for example, but not limited to, used cooking oils and/or fats) . In particular, it should be noted that oils and fats are normally complex mixtures of different products and are mainly made up, in terms of weight (usually in a percentage higher than 90%, more precisely higher than 95%), of lipids (usually triglycerides) and their hydrolysis products .

BRIEF DESCRIPTION OF THE FIGURES

The invention is now described with reference to the accompanying drawings, which show non-limiting embodiments thereof, wherein:

- figure 1 schematically shows a plant made according to the present invention;

- figure 2 schematically shows a further embodiment of a plant made according to the present invention;

figure 3 schematically shows a further embodiment of a plant made according to the present invention.

EMBODIMENTS OF THE INVENTION

In figure 1, the number 1 indicates as a whole a plant for the treatment of a base composition (in particular, a mixture of oils and/or fats). The plant 1 is advantageously used for the deodorization and/or deacidification of an oil and/or fat, of a base composition (an oil and/or a fat) . The plant 1 comprises a degasser (of type known per se and not shown), which is designed to degas (reduce the presence of air and any traces of humidity) the base composition (preferably degummed) ; and a duct 2 to feed the base composition (preheated - from the degasser) to a heater 3. Typically, degassing takes place at a temperature lower than 100°C to avoid phenomena of oxidisation. Advantageously, degassing takes place at a pressure lower than 1 atm.

In particular, the base composition (degummed) has a phosphorus content lower than 25ppm, advantageously lower than lOppm. The iron content in the base composition (degummed) is, advantageously, lower than 0.2ppm. The copper content in the base composition (degummed) is, advantageously, lower than 5ppb . The heater 3 is designed to bring the base composition to a temperature from approximately 150°C (in particular, from approximately 160°C; more precisely from 190°C) to approximately 280°C (in particular, to 260°C). The pressure inside the heater 3 is usually kept below or equal to lOmmHg (13.33mbar) (advantageously, up to 6mmHg (8mbar); more advantageously, up to 4mmHg (10.67mbar); even more advantageously, up to 2mmHg (2.67mbar) in particular, from 0. lmmHg (0.13mbar)). In use, fractions of the base composition that have possibly evaporated leave the heater 3 in the gaseous phase. Said fractions are sent through a duct 8' (connected to a duct 8) to a condenser 9.

The plant 1 furthermore comprises a stripping device 4 which operates at a temperature from approximately 150°C (in particular, from approximately 160°C; more precisely, from 190°C) to approximately 280°C (in particular, to 260°C) . A duct 5 fluidly (i.e. hydraulically ) connects the heater 3 to the stripping device 4 to convey the base composition to said stripping device 4.

According to some embodiments, advantageously, the condenser 9 and the stripping device 4 are two distinct devices. The condenser 9 and the stripping device 4 do not have a common volume .

According to the depicted variants, it should be noted that the condenser 9 and the device 4 are not inside each other.

Advantageously, the condenser 9 and the device 4 do not comprise a short-path type distiller. The plant 1 also comprises an evaporator (or heater) 6, which is designed to evaporate a stripping fluid, which is conveyed to the device 4 (through a duct 7) . The evaporator 6 brings the stripping fluid (for example, glycerin) to a pressure higher than or equal to the pressure within the stripping device 4 and to a temperature equal to or higher than the boiling temperature of the stripping fluid at said pressure.

For example, when the stripping fluid is glycerin, the temperature must be at least approximately 87°C at the pressure of 0. lmmHg (0.13mbar) and at least approximately 157°C at the pressure of 6mmHg (8mbar). In particular, the evaporator 6 brings the stripping fluid to a temperature up to 220°C. According to some embodiments, the stripping fluid is substantially waterless.

The device 4 comprises structures for increasing the exchange surface between liquid and gas. In particular, the stripping device 4 comprises a packed column or tray column. According to the depicted embodiment, the device 4 comprises a tray column which operates in cross-flow (of per se known type), the base composition (in liquid state) is fed from the top to the device 4, and the stripping fluid (in gaseous state) is fed in the area of one or more trays of said device 4. The pressure inside the stripping device 4 is usually maintained lower than or equal to lOmmHg (13.33mbar) (advantageously, lower than or equal to 6mmHg (8mbar); more advantageously, lower than or equal to 4mmHg (5.33mbar); even more advantageously, lower than or equal to 2mmHg (2.67mbar); in particular, from 0. lmmHg (0.13mbar)) . In particular, the pressure inside the stripping device 4 is substantially equal to the pressure inside the heater 3. According to some embodiments, the stripping fluid (in the gaseous state or in the liquid state) is introduced into the device 4 directly in the base composition (for example by means of bubbling - when the stripping fluid is in the gaseous state) .

Advantageously, the stripping fluid is introduced in the liquid state (preferably heated to a temperature lower than its boiling temperature) . In this case, the evaporator 6 is absent or does not bring the stripping fluid to a temperature such as to be in the gaseous phase (in this case, therefore, it acts as a simple heater) at the internal pressure of the device 4.

In use (inside the device 4), the base composition releases to the gaseous phase (or to the stripping fluid) a first portion of itself (in this example, containing free fatty acids and other volatile substances) . The treated base composition (deodorized and/or deacidified oil) leaves the stripping device 4 from the bottom (in the liquid phase) . In particular, the treated base composition leaves the device 4 through a duct 4a. A separating mixture comprising the stripping fluid and the above-mentioned first portion of the base composition leaves the stripping device 4 from the top (in the gaseous phase) . Such a mixture is conveyed through a duct 8 to a condenser 9.

Advantageously, between the device 4 and the condenser 9 is not interposed any device deesigned to vary the pressure (in particular, designed to increase the pressure in the condenser 9 with respect to the device 4) (the device 4 and the condenser 9 are directly connected) .

According to the depicted embodiment, the condenser 9 is of the counter-current mixing type with recirculation of part of the condensed fluid.

The temperature of the condenser 9 is such as to cause the condensation of at least part of the separating mixture (more precisely, at least part of the stripping fluid and at least part of the first portion of the base composition) . The temperature of the condenser 9 is such as to cause the condensation of at least the majority, in particular (almost) all, of the stripping fluid and at least part (the majority; in particular, almost all) of the first portion of the base composition contained in the separating mixture.

The temperature of the condenser 9 is such as to cause the condensation of any condensable substances coming from the heater 3.

Typically, inside the condenser 9 (in particular, at the outlet of the gaseous phase) the temperature is from 4°C. In particular, inside the condenser 9 (in particular, at the outlet of the gaseous phase) the temperature is at least 12°C. Inside the condenser 9 (in particular, at the outlet of the gaseous phase) the temperature is up to 160°C (in particular, up to 150°C) . Advantageously, the temperature of the liquid phase leaving the condenser is at least approximately 50°C (so as to avoid solidification of the fatty acids) .

The pressure inside the condenser 9 is usually kept lower than or equal to lOmmHg (13.33mbar). Advantageously, the pressure inside the condenser 9 is kept lower than or equal to 6mmHg (8mbar) . More advantageously, the pressure inside the condenser 9 is kept lower than or equal to 4mmHg (5.33mbar) (even more advantageously, lower than or equal to 2mmHg (2.67mbar); in particular, from O.OlmmHg (O.Olmbar)). In particular, the pressure inside the condenser 9 is lower than or equal to the pressure inside the stripping device 4 (and the heater 3) . In this way, it is not necessary to provide any equipment for setting a different (in particular, higher) pressure in the condenser 9 with respect to the device 4. This determines a reduction in construction and operating costs of the plant 1 with respect to the plants in use.

The plant 1 furthermore comprises a suction unit 10 (in particular, a vacuum unit comprising a pumping system) which is suited to bringing the pressure inside the condenser 9 and the stripping device 4 (and the heater 3) to the values indicated above. More precisely, the suction unit 10 is connected (via a duct 11) to the condenser 9 which, therefore, is interposed between (the device 3) the device 4 and the suction unit 10. According to some embodiments, the suction unit 10 (of per se known type) comprises at least a pump (typically, a lobe pump Roots) : more precisely, the suction unit 10 comprises several mechanical pumps and condensers positioned in series or a system of steam-jet ejectors and condensers (and liquid ring pump) positioned in series (in this example the suction unit 10 comprises two steam-jet ejectors positioned in series, a condenser, a water ring pump with heat exchanger for cooling the water and a separator designed to separate the gaseous phase from the liquid phase, which is partly recycled in the pump) (and/or a combination of pumps and ejectors) .

In use, the gases (and/or vapours) that are not condensed under the conditions present inside the condenser 9 (in this example, components of the air and any vapours of relatively low boiling (bad-smelling) substances) are conveyed, through the duct 11, towards the suction unit 10 leaving the condenser 9 from the top. Advantageously, the condenser 9 is provided with a demister through which said gases flow before leaving the condenser 9. The substances condensed inside the condenser 9 (the stripping fluid and, in this example, mainly fatty acids - and unsaponifiable matter) leave the condenser 9 from the bottom thereof.

According to some embodiments, the heater 3 and the stripping device 4 (and the condenser 9) are bundled in one piece of equipment.

Advantageously, the condenser 9 is completely arranged downstream of the stripping device 4. In particular, the condenser 9 is arranged completely between the stripping device 4 and the suction unit 10.

The plant 1 furthermore comprises a separator 12, which is designed to receive the substances condensed by the condenser 9 (through a duct 13) and to separate (or dissociate) the stripping fluid from other components (in particular, the part - in this example mainly fatty acids and unsaponifiable matter of the first portion of the base composition still associated to it). The separator 12 can be of any known type designed to the purpose (considering the type of base composition, the stripping operating conditions and stripping fluid used) . In this example, the separator 12 comprises a decanter, inside which a phase separation (simply) takes place between a phase consisting (mainly) of glycerin and a phase consisting mainly of fatty acids (and unsaponifiable matter) . In addition, or alternatively to the above, the separator 12 is designed to separate the stripping fluid (by known methods) for example by means of distillation, centrifugation, crystallisation and/or (membrane) filtration. The matter separated from the stripping fluid is removed from the separator 12 via a duct 12a.

The duct 12a leads to a storage of products (sometimes undesired, sometimes of particular interest).

In some cases, the condenser 9 and the separator 12 are bundled in one piece of equipment.

According to the depicted embodiment, the plant 1 also comprises a recirculation duct 14 which fluidly connects the separator 12 to the evaporator 6. In this way, the (at least part of the) stripping fluid coming from the separator 12 is returned (in liquid state) to the evaporator 6 and (subsequently) re-used for the stripping.

According to the depicted embodiment, a reservoir 15 of stripping fluid is fluidly connected to the evaporator 6 (in particular, via the duct 14). Said reservoir 15 is designed to restore the losses (and/or spillages) of stripping fluid which occur during work. In particular, the reservoir 15 is fluidly connected to the duct 14 by means of a duct 16. Advantageously, the stripping fluid introduced into the circuit is substantially waterless and degassed (in pressure and temperature conditions near to those present in the above- mentioned degasser - arranged upstream of the duct 2 - for the incoming oil and/or fat). In this regard, it is important to underline that (small) parts of the stripping fluid can be spilled and/or lost for example during condensation, separation and/or stripping. Small fractions of the stripping fluid may also degrade and/or react during operation of the plant 1.

According to some embodiments (along the duct 14; for example, in the area of a by-pass of a length of the duct 14) other purification devices can be present (for example, absorption, distillation, cooling and/or centrifugation, crystallisation and/or (membrane) filtration devices) to purify the stripping fluid of impurities. Examples of impurities are: degradation products (e.g. of the stripping fluid itself and/or of the base composition); reaction products (e.g. between the stripping fluid and the base composition) ; impurities from the base composition. In this example, the impurities from the base composition can be, for example: pesticides, polychlorobiphenyls , dioxins, aromatic hydrocarbons, monoglycerides .

The plant 1 is provided with a return duct 17 to feed part of the stripping fluid coming from the separator 12 (in particular, from the duct 14) to the condenser 9. Advantageously, a cooler 18 is arranged along the duct 17 to lower the temperature of the stripping fluid (substantially to the (desired) temperature of the gases leaving the condenser 9) . More precisely, the cooler 18 lowers the temperature of the stripping fluid to a value a few degrees - from 2°C to 10°C - below the temperature of the gases leaving the condenser 9. In this example, preferably from 35°C, to maintain the fluidity of the glycerin, to approximately 80°C, to condense the fatty acids. The heat recovered by the cooler 18 can be used inside other parts of the plant 1 (for example to contribute to heating of the stripping fluid that enters the circuit and/or of the above-mentioned degasser of the incoming oil and/or fat) .

In use, the stripping fluid returned to the condenser 9 is used as condensation fluid (moving in counter-current with respect to the low boiling gases/vapours).

According to some embodiments not shown, the stripping fluid is chosen so that it is possible to condense the majority of the (in particular all the) stripping fluid in the condenser 9, without any component of the first portion of the base composition condensing. The first portion is therefore removed from the plant via the pumping unit 10. In said embodiments, the plant does not require the separator 12, the stripping fluid condensed in the condenser 9 is (directly) partly sent to the evaporator 6 and partly recycled, via the cooler 18, in the condenser 9.

According to some embodiments not shown, along the duct 4a a cooling device is arranged, in the area of which the composition coming from the device 4 is cooled (and possibly, when it is desirable to complete the deodorisation of the base composition, treated under a vacuum with small quantities of stripping fluid) , advantageously by thermal exchange with the base composition to be treated coming from the degasser of the incoming oil and/or fat and going to the heater 3.

According to some embodiments the device 4 (the cooling device) and the heater 3 are bundled in one piece of equipment .

The variant of figure 2 relates to a plant 1', the layout of which is similar to that of the plant 1, from which it differs due to the fact that the device 4 works in counter-current and the stripping fluid is fed from the bottom of the device 4 ; due to the fact that the evaporator 6 is replaced by a mixer (and heater) 6' connected to the duct 4a by means of a duct 4' a; due to the fact that a duct 17' and the cooler 18 respectively recycle (drawing from a duct 13' ) and cool (directly) part of the condensate of a condenser 9' (which is conveyed to a storage, via the above-mentioned duct 13' , without passing through a separator) ; due to the fact that a duct 14' directly connects a condenser 9" to the mixer (and heater) 6' ; due to the fact that the separator 12 is not present; and due to the fact that a tank 20 is present, for collecting the spilled stripping fluid, connected to the duct 14' by means of a duct 19.

It should furthermore be noted that the plant 1' (instead of one single condenser 9) comprises two condensers 9' and 9" arranged in series (one downstream of the other) between the stripping device 4 and the suction unit 10.

The parts of the plant 1' are marked with the same reference numbers as those that distinguish the corresponding parts of the plant 1.

Furthermore, when not specified otherwise, the operating conditions (for example pressure and temperature) and if necessary the operation of parts of the plant 1' are the same as the corresponding parts (if necessary identified by the same reference number) of plant 1.

The stripping device 4 comprises a (structured) packed column. This type of column is particularly suited to deacidification . The packed columns can be used for deodorization in combination with portions of tray column and/or cooling sections in which the oil remains at length, being treated with small quantities of stripping fluid, in vacuum conditions . The condenser 9' is substantially identical to the condenser 9 of plant 1, the condenser 9" is a surface condenser. The condenser 9" is maintained at a temperature lower than the temperature at which the condenser 9' is maintained.

The plant 1' is advantageously used for the deacidification (physical refining) of an oil and/or fat (base composition) . The oil and/or fat is, advantageously, degummed.

According to some embodiments (for example if the base composition is oil and/or fat and the stripping fluid is dodecane), the condenser 9' operates at a temperature from 60°C to 80°C. The condenser 9" operates at a temperature between 15°C and 50°C and such as to cause condensation of the dodecane at the pressure present in the condenser. The condensers 9' and 9" are fluidly connected to each other by means of a duct 11' . The condenser 9" is fluidly connected to the suction unit 10 via a duct 11.

In use, a part of the first portion of the base composition (in this example, mainly fatty acids) condenses in the area of the condenser 9' and is taken from the (bottom of the) condenser 9' and conveyed through the duct 13' , where a portion is taken from the duct 17' and recycled (from the top) in the condenser 9' via the cooler 18, which substantially lowers the temperature thereof to the temperature (advantageously, a few degrees lower) of (desired for) the gases leaving the condenser 9' . The stripping fluid and the non-condensed fractions of the first portion of the base composition leave (the head of) the condenser 9' and are conveyed, via the duct 11' , to the condenser 9" where the stripping fluid is condensed while components of the air and any vapours of relatively low boiling (bad-smelling) substances are conveyed, through the duct 11, towards the suction unit 10. Advantageously, the condenser 9" is provided with a demister through which said components of the air and any vapours flow before leaving the condenser 9". The stripping fluid leaves the condenser 9" from the bottom. The (part of the) stripping fluid reaches the mixer (and heater) 6' via the duct 14'.

It should be noted that the product conveyed to the storage area through the duct 13' is at times of lesser interest and at times of greater interest. In use, a portion of the treated base composition reaches, through the duct 4'a, the mixer (and heater) 6' where it is mixed under pressure with the stripping fluid in the liquid state. The mixture (heated to a temperature near the temperature - in particular, from 160°C to 260°C - at which the base composition is introduced into the device 4) under pressure, at a pressure (higher than the vapour pressure of the stripping fluid at the temperature of the mixture) sufficient to prevent vaporisation of the stripping fluid, reaches, via the duct 7, the device 4 where the stripping fluid vaporises.

According to some not shown embodiments, (part of) the spilled stripping fluid, collected in the tank 20, is purified by known methods (for example absorption, distillation, cooling and/or centrifugation, crystallisation and/or (membrane) filtration ) and conveyed to the reservoir 15 of stripping fluid.

According to some not shown embodiments, along the duct 2 a heat exchange device is arranged in the area of which, advantageously, the base composition to be treated, coming from the degasser (of the incoming oil and/or fat) and going to the heater 3, is heated by thermal exchange with the treated base composition coming from the device 4 (along the duct 4a) . It should be noted that the descriptions of the plants 1 and 1' are schematic (limited to the parts of the plant through which, flows the base composition and/or portions of the latter and/or the stripping fluid) and that, among other things, to allow correct operation of the plants 1 and 1', one or more controls, valves etc. are foreseen.

According to one aspect of the present invention, a method for the treatment of a base composition is provided. The base composition is preferably defined as described above.

In particular, the method can be suited to purify the base composition and/or to separate from the base composition (minor) products of interest (e.g. sterols, squalene, tocopherols, fatty acids) . More specifically, the method can be suited to deacidify (and/or to deodorize) a base composition (oils and/or fats).

The method comprises a stripping step, during which the base composition (in liquid state) and the stripping fluid are placed in contact with each other and at least part of (substantially all) the stripping fluid forms together with a first portion (relatively volatile) of the base composition a separating mixture, which separates out in gaseous phase from the base composition in liquid phase in the area of a stripping zone.

Where the stripping fluid is introduced (or input) in liquid state into the base composition, it is possible to improve mixing with the latter and, consequently, make the removal of the first portion more efficient. In particular, the efficiency is given by the ratio between quantity of first portion removed and quantity of stripping fluid used. The introduction of the stripping fluid in gaseous state avoids cooling of the base composition, due to absorption from the latter of the evaporation heat by the stripping fluid. If the stripping fluid is introduced in liquid state, it is possible to provide heating systems for heating the base composition (for example (superheated) steam coils or electric heaters, near the point - or points - where the stripping fluid is introduced into the base composition) .

According to some embodiments, the stripping fluid is lower boiling than (the majority of) the components of the first portion of the base composition.

The method also comprises a condensation step, during which the separating mixture in gaseous state is brought to a temperature and a pressure such that at least part of the first portion of the base composition and at least part of (in particular, the majority of; more precisely, substantially all) the stripping fluid condenses in the area of a condensation zone different from the stripping zone. In particular, the stripping zone and the condensation zone are not inside each other.

According to the embodiments illustrated, the volumes constituting the stripping zone and the condensation zone are physically distinct.

Said method can be carried out in semi-continuous, continuous or batch type plants. Advantageously, the method of the invention is carried out in continuous or semi-continuous plants and does not present limitations with respect to the respective directions (or ways) of the fluids in the stripping zone (in particular, in a stripping device; typically, a stripping column (or a system with several vessels) ) which can be, for example, of the equicurrent, counter-current, cross- flow or mixed type.

According to specific embodiments, said method is carried out in one of the plants described above with reference to the figures from 1 to 3. In particular in figures 1 and 2, the stripping device 4 defines the stripping zone and the condenser 9 (the condensers 9' and 9") defines the condensation zone.

The stripping step takes place at a temperature from approximately 150°C to approximately 280°C, advantageously from approximately 160°C to approximately 260°C.

The pressure, during the stripping step, is lower than or equal to lOmmHg (13.33mbar). Advantageously the pressure, during the stripping step, is lower than or equal to 6mmHg (8mbar), in particular lower than or equal to 4mmHg (5.33mbar) . Advantageously the pressure, during the stripping step, is lower than or equal to approximately 2mmHg (2.67mbar) . Normally, the stripping step takes place at a pressure of at least approximately 0.05mmHg (0.07mbar) (in particular, at least approximately O.lmmHg (0.13mbar)). More precisely, the stripping step takes place at a pressure of at least approximately 0.75mmHg (lmbar).

The quantity of stripping fluid necessary can be calculated, using known formulas, according to the initial and final concentrations of the component/s to be removed. For example, for batch or cross-flow plants, the so-called "Bailey formula" can be used, a non-simplified (and completed by other authors) version of which is given below:

PO V, P wherein

S = quantity of stripping fluid [mol]

P = total pressure in the system [pressure units]

0 = quantity of oil processed [mol] P _v = vapour pressure of the volatile component in the pure state [same pressure units as P]

V _s = quantity of volatile component before stripping [mol] V _e = quantity of volatile component after stripping [mol]

E = vaporisation efficiency (defined as the ratio between the partial pressure (P _vs ) of the volatile component in the separating mixture and the partial pressure (P _Vf ) which the same volatile component would have at equilibrium with the base composition) , it is a function of the nature of the volatile component, the distance covered by the stripping fluid bubbles through the base composition and the dimensions of the bubbles; it can be obtained experimentally and is expressed by the equation:

PVS _K L in which

Pvs = partial pressure of the volatile component in the separating mixture

P _Vf = partial pressure which said volatile component would have at equilibrium with the base composition

L = thickness of the layer of base composition crossed by the stripping fluid bubbles

D = diameter of the bubbles

K = constant characteristic of the volatile component determined by its diffusion rate in the vapour state. A method for measuring the vaporization efficiency is indicated in "Laboratory Deodorizer with a Vaporization Efficiency of Unity", Szabo Sarkadi, D. , J. Am. Oil Chem. Soc. 35:472475 (1958). The value of the vaporization efficiency is normally (in modern stripping devices, correctly sized) between 0.7 and 0.9. There are, however, cases in which the vaporization efficiency is greater than 1. Said "Bailey formula" can be used to obtain approximate indications also for continuous systems in counter-current and equicurrent .

In practice, for the design of plants, reference can often be made to tables obtained experimentally. The specific operating parameters of the process can be regulated according to experimental tests.

According to some embodiments, the stripping step takes place in the stripping device 4.

The condensation step takes place at temperatures lower than the temperature at which the stripping step takes place. The condensation step can be divided into several sub-steps (operating at decreasing temperatures) . Each of the condensation sub-steps takes place at a temperature such that the vapour pressure of the substances which condense in it is substantially lower than the pressure present in the device 4.

The vapour pressures as a function of the temperature of many volatile compounds present in oils or fats, removed in deodorization and otherwise, are available in the specialist literature. For example in: Stage, H. 1956, "Fette, Seifen, Anstrichmittel" ed in "Bailey' s Industrial Oil and Fat Products" Sixth Edition, Vol. 5, page 345. According to some embodiments, the maximum temperature at which (at least part of) the condensation step can take place can be calculated via the Clausius-Clapeyron equation.

In particular, the temperature at which the condensation step (during which at least part of the stripping fluid condenses) takes place is lower than the temperature indicated (in K) by the following expression (obtained by integration of the Clausius-Clapeyron equation assuming: ΔΗ = constant in the interval of T and P considered; molar V condensed phase = negligible; molar V gaseous phase = RT/P - i.e. ideal gas):

1

wherein Ti indicates the temperature during the stripping step (in K) , Pi indicates the pressure during the stripping step, P ₂ indicates the pressure during the condensation step (Pi and P ₂ are expressed in the same unit of measurement), R indicates the constant of the ideal gases (8,314 J mol ^~1 K ^"1 ) and AH _vap indicates the molar enthalpy of vaporization (in J mol ^-1 ) of the stripping fluid. The values of the vaporization enthalpy of glycerin and some glycols, in the temperature range of interest, are available in the "Dortmund Data Bank". Further vaporization enthalpy data, for example for various hydrocarbons, are reported in "Perry's Chemical Engineers' Handbook", 8th Edn , McGraw-Hill, New York, 2008. The vaporization enthalpy can be estimated, from experimental data, using an equation of the vapour pressure, derived from the Clausius-Clapeyron equation. There are also predictive methods which allow estimation of the vaporization enthalpy value at the normal boiling temperature, based on the knowledge of critical constants, which can in turn be calculated via group contribution methods. A critical collection of methods for calculation of the vaporization enthalpy at normal boiling temperature is presented in

"Evaluation of correlations for prediction of the normal boiling enthalpy", I. Cachadina , A. Mulero, Fluid Phase Equilibria , Volume 240, n° 2, 24 February 2006, pp. 173-178. Applying the Watson correlation, it is possible to obtain the vaporization enthalpy value at temperatures different from the normal boiling temperature starting from the vaporization enthalpy value at the latter.

In addition or alternatively, the temperature at which the condensation takes place is lower than the temperature determined (for at least one component of the separating mixture; in particular, a component of the stripping fluid) by means of the Antoine equation. The equation is written (isolating the temperature):

B

T = C

A - log ₁₀ P°

wherein :

" P° is the vapour pressure of the pure component;

• T is the temperature to be determined;

• A, B and C are constants that depend on the nature of the component;

» T and P° are indicated in the same units used in calculation of the constants (normally tabulated for mmHg and °C and for the use of decimal logarithms) .

The values of the parameters (A, B and C) of the Antoine equation can be calculated when experimental data are available. There are also various databases containing the parameters of the Antoine equation and/or data for calculating them, for example the "Dortmund Data Bank" contains experimental data, molecular structures and auxiliary parameters for over 20,000 chemical substances of industrial interest. The "Yaws' Handbook of Antoine Coefficients for Vapor, Pressure (2nd Electronic Edition)" (Yaws, Carl L; Narasimhan, Prasad, K. ; Gabbula, Chaitanya, 2009) and Landolt- Bornstein: Numerical Data and Functional Relationships in Science and Technology - New Series, Subvolume 20B "Vapor Pressure and Antoine Constants for Oxygen Containing Organic Compounds" are cited several times in literature as sources of data concerning the components of oils and fats. The Antoine parameters for dodecane are provided by various sources, including "Vapor-Liquid Equilibria for Pentane + Dodecane and Heptane + Dodecane at Low Pressures" (Humberto N. Maia de Oliveira , Francisco W. Bezerra Lopes, Afonso A. Dantas Neto, and Osvaldo Chiavone-Filho) and "TRCHP TABLES, Selected Values of Properties of Hydrocarbons and Related Compounds" (Table 23-2 (1.101) -kP page 2), API Research Project 44, June 1974, Texas A&M. Values of the Antoine parameters for 5000 organic compounds (including glycerin, dodecane and various fatty acids) are available on the website "Iranian Chemical Engineers Portal". Also the website of the American "National Institute of Standards and Technology" contains Antoine parameters for various chemical compounds.

Advantageously, the temperature of the condensation step is lower than the temperature determined with the Antoine equation for one or more components (in particular, at least part of the stripping fluid) which define the majority of the separating mixture.

In some cases, the temperature of the condensation step is lower than the temperature determined with the Antoine equation for the majority of (in particular all) the components of the separating mixture.

In particular, the condensation step takes place at a temperature of (at least 4°C, advantageously) at least 12°C (more precisely, at least approximately 15°C) .

Advantageously, the condensation step takes place at a temperature of at least approximately 45°C (more precisely, at least approximately 50°C) . In this way, when the base composition is an oil and/or fat, the solidification of fatty acids is avoided. Furthermore, cooling at these temperatures can be performed without using refrigeration pumps (by simple direct or indirect thermal exchange with the environment). If it is desirable to perform (part of) the condensation at temperatures that cannot be obtained by (simple) thermal exchange with the environment, a refrigeration device can be used which, directly or indirectly, lowers the temperature in the condenser (9; 9', 9").

According to some embodiments, the condensation step takes place at a temperature up to 150°C (more precisely, up to 140°C) . Advantageously, (at least part of) the condensation step takes place at a temperature up to 100°C (more precisely, up to 80°C) .

The condensation step is performed at a pressure lower than (or equal to) the pressure at which the stripping step is carried out. The pressure, during the condensation step, is lower than 20mmHg (26.66mbar), in particular lower than or equal to lOmmHg (13.33mbar). Advantageously, the pressure during the condensation step is lower than or equal to approximately 6mmHg (8mbar) (more precisely, lower than or equal to 2mmHg (2.67mbar)). Normally, the condensation step takes place at a pressure of at least approximately O.OlmmHg (O.Olmbar) (in particular, at least approximately 0.05mmHg (0.07mbar); more precisely, at least approximately O.lmmHg (0.013mbar) ) . In some cases, the condensation step takes place at a pressure of at least 0.75mmHg (lmbar).

Advantageously, the stripping step and the condensation step are performed substantially at the same pressure. However, according to some embodiments (such as those illustrated in figures 1 and 2, for example), the condensation step takes place at a pressure (slightly) lower than the pressure at which the stripping step takes place. This happens because the condenser 9 (or 9' and 9") is interposed between the suction unit 10 and the stripping device 4. Therefore, the vacuum generated by the suction unit 10 diminishes (due to pressure loss) passing (through the duct 8 and) through the condenser 9 (or 9' and 9") . Therefore, the condensation step takes place at a pressure lower than or equal to the pressure at which the stripping step takes place. During (at the end of) the condensation step (at least the majority of) the stripping fluid goes to the liquid phase.

According to specific embodiments, during (at the end of) the condensation step the (at least part of the) first portion goes to the liquid phase.

Advantageously, the stripping fluid is substantially waterless. In particular, the stripping fluid comprises (more precisely, consists of) an organic fluid.

It is important to note that the sum of the partial pressures of the stripping fluid and the components of the base composition in the separating mixture is higher than the pressure of the stripping step (applied by the vacuum system) . In other words the stripping fluid is selected so that, at the stripping temperature, the sum of the partial pressures of the stripping fluid and the components of the separating mixture in the base composition is higher than the pressure of the stripping step (applied by the vacuum system) .

The stripping fluid has a vapour pressure (measured at the temperature at which condensation of the stripping fluid takes place; more precisely, at a temperature from approximately 4°C (in particular, from approximately 12°C) to approximately 150°C) , lower than the pressure at which the condensation step takes place (in particular, at 12°C - advantageously, at 20°C - it has a vapour pressure lower than lOmmHg (13.33mbar) ) .

Advantageously, the stripping fluid has a vapour pressure (measured at the temperature at which the stripping step takes place; more precisely, at a temperature from approximately 150°C to approximately 280°C) , equal to or higher (more precisely higher) than the pressure at which the stripping step takes place (in particular, higher than 0.05mmHg (0.07mbar) at the temperature of 280°C (in some cases, at the temperature of 260°C) ) . More precisely, the stripping fluid has a vapour pressure of at least 0.75mmHg (lmbar).

Advantageously, the stripping fluid has a vapour pressure, (measured) at a temperature from approximately 4°C (in particular, from approximately 12°C) to approximately 150°C (more precisely at the temperature at which condensation thereof takes place) lower than the pressure at which the stripping step takes place (more precisely, lower than approximately lOmmHg (13.33mbar) ) .

If the datum is not available in literature, the vapour pressure can be measured using the method described in the AST E1194 - 07 and/or ASTM D 2879 standard. Where it is not possible with these or other techniques to measure the vapour pressure at a given temperature, the vapour pressure at that temperature can be calculated via the Antoine equation already referred to. In this case P° is the vapour pressure to be determined and T is the temperature at which said vapour pressure must be determined.

The stripping fluid is substantially stable in the plant operating conditions. Advantageously, the stripping fluid is substantially stable up to at least 200°C (from 4°C, in particular from 12°C). More precisely, the stripping fluid is substantially stable up to at least 180°C. Advantageously, the stripping fluid is substantially non reactive with the components of the base composition. Advantageously, the use of operating conditions and/or the presence of substances which can cause or catalyse degradation reactions of the stripping fluid or undesired reactions between the latter and the base composition (for example reactions of alcohols or polyols with fatty acids) should be avoided. If said reactions are a problem, and the use of the products leaving the plant allows it, inhibitors of the reactions can be used.

Advantageously (since the quantity of stripping fluid necessary is directly proportional to its molecular weight), the stripping fluid has a low molecular weight.

Advantageously, the stripping fluid is easily separable from the remaining part of the separating mixture.

Advantageously, the stripping fluid is compatible for use with food . Non-exhaustive examples of substances that can be used as stripping fluids (in particular in the deacidification and deodorization of oils and/or fats) are:

diols, triols and tetrols with a number of carbon atoms lower than or equal to 12 and their Ci-C ₆ alkyl-ethers

- alcohols with a number of carbon atoms from 6 to 16

ketones with a number of carbon atoms from 7 to 16 ethers with a number of carbon atoms from 8 to 16

hydrocarbons with a number of carbon atoms from 10 to 18 (in particular, 16)

- C4-C16 polyoxyalkylene glycols, having from 2 to 6 oxyalkylene units bound to one another (via the oxygen atom) .

The polyoxyalkylene glycols have a terminal alkyl group or a terminal hydrogen bound to an oxyalkylene unit (via the oxygen) and a terminal alkyl or a terminal hydroxyl opposite the terminal alkyl group or terminal hydrogen.

The polyoxyalkylene glycols (in other words) have at one end of the chain a hydroxyl group or an alkoxy group bound to (a carbon of) an oxyalkylene unit, and at the other end of the chain a hydrogen or an alkyl group bound (both the hydrogen and the alkyl group) to the oxygen of an oxyalkylene unit.

In this text "C _x -C _y " refers to a group or molecule which is understood to have from x to y atoms of carbon. In some cases, the stripping fluid comprises (is) at least one compound chosen from the group consisting of: C ₂ -C _li! dioxygenated compounds, C3-C13 trioxygenated compounds, C ₄ -C ₁₂ tetraoxygenated compounds, C 10-C16 aliphatic or cycloaliphat ic hydrocarbons (straight or branched) , C i ₀ -C i ₆ ethers, C ₄ -C i ₆ polyoxyal kylene glycols (and, if necessary in particular cases, C ₆ -Ci6 alcohols or C ₇ -Ci ₆ ketones) .

According to some embodiments, the dioxygenated compounds have the following structure:

OR ¹ OR ² wherein R ¹ and R ² are selected, each irrespective of the other, within the group consisting of: H, C 1-C6 alkyl;

R ³ and R ⁴ are selected, each irrespective of the other, within the group consisting of: H, C1 -C12 alkyl;

R ⁵ is selected from the group consisting

between the two adjacent carbons, C 1 -C 12 alkyl

According to some embodiments, the trioxygenated compounds have the following structure: wherein R ¹ , R ² and R ⁶ are selected, each one irrespective of the others, within the group consisting of: H, C 1-C6 alkyl;

R ⁷ and R ¹⁰ are selected, each irrespective of the other, within the group consisting of: H, C 1 -C 10 alkyl;

R ⁸ and R ⁹ are selected, each irrespective of the other, within the group consisting of: direct bond between the two adjacent carbons, C 1 -C 10 al kylene .

According to some embodiments, the tetraoxygenated compounds have the following structure:

in which R ¹ , R ² R ⁶ and R ¹¹ are selected, each one irrespective of the others, within the group consisting of: H, Ci-C _e alkyl; R ¹² and R ¹⁶ are selected, each irrespective of the other, within the group consisting of: H, Ci-C ₈ alkyl;

R ¹³ , R ¹⁴ , and R ¹⁵ are selected, each one irrespective of the others, within the group consisting of: direct bond between the two adjacent carbons, i-C ₃ al kylene . According to some embodiments, the ethers have the structure R ^A -0-R ^B , in which R ^A and R ^B are alkyls.

According to some embodiments, the polyoxyalkylene glycols have the following structure: R ^x -0- (R ^Y -0) _m -R ^z , in which

R ^x and R ^z are selected, each irrespective of the other, within the group consisting of: H, C ₁ -C ₁₂ alkyl;

m is an integer from 2 to 5;

each R ^Y , independently of the other R ^Y , is a C ₂ -C ₃ alkylene. According to some advantageous embodiments, the stripping fluid comprises (is) a compound chosen from the group consisting of: ethylene glycol, propylene glycol, glycerin, diethylene glycol ( 3-oxa- 1 , 5-pentanediol ) , dodecane.

Advantageously, the stripping fluid comprises (is) glycerin.

The base composition comprises a second portion, which presents a vapour pressure (measured) at a temperature from approximately 150°C to approximately 280°C (more precisely, at the temperature at which the stripping step takes place) lower than the stripping pressure, in particular lower than 0. lmmHg (0.13mbar) (more precisely, lower than 0.05mmHg (0.07mbar)).

More precisely, the base composition comprises chemical species (mainly triglycerides) which have a vapour pressure (in the base composition or in the second portion), (measured) at a temperature from approximately 150°C to approximately 280°C (more precisely, at the temperature at which the stripping step takes place), substantially null (i.e. they are substantially non-volatilizable in said conditions) . Said chemical species constitute (or define) the second portion of the base composition.

The second portion corresponds to the treated base composition and is recovered after the separating mixture has been removed.

Advantageously, the second portion is a major portion of the base composition. In other words, the second portion is present, in the base composition to be treated, in a quantity by weight higher than the first portion.

The first portion (in other words) is a minor portion of the base composition. In other words, the first portion is present in a quantity by weight lower than the second portion.

According to some embodiments, the base composition is mainly a mixture of lipids and products of their hydrolysis. In particular, as mentioned above, the base composition is an oil (or a fat) (of biological origin) . Alternatively (or in addition), the base composition is a mixture of oils and/or fats (of biological origin) .

In these cases, normally, the method is used to reduce the acidity and/or the odour of the base composition (and/or to extract undesired components from it - for example PCB, dioxins, pesticides etc. - or components of particular interest - for example sterols, tocopherols, squalene) . According to some embodiments, (a large part of) the fatty acids and/or (a large part of) the bad-smelling compounds contained in the base composition are separated out from the base composition. In some instances, the method comprises also (at least) a dissociation step, during which the separating mixture is treated so that the first portion of the base composition (the portion that has been separated out from the base composition, i.e. - when the base composition is an oil and/or a fat - a mixture of fatty acids and volatile compounds) and the stripping fluid are separated from each other. According to some embodiments, the dissociation step is subsequent to the condensation step and entails treatment of the separating mixture in the liquid state. More precisely, only the part of the first portion that has condensed simultaneously with the stripping fluid (in the same sub-step) is separated from the latter during the dissociation step. The other components have already been separated during the condensation step (as they did not condense - or condensed in different sub-steps) . The dissociation step takes place in the area of a dissociation zone (which is, in some cases, defined by the separator 12) and by means of any one of the known methods (for example as identified above with reference to the separator 12 ) .

According to some embodiments (with particular reference to the plant 1' ) , the method comprises a first condensation sub- step during which at least the majority of the first portion is condensed, and at least a second condensation sub-step during which the stripping fluid is (at least mainly) condensed. The second condensation sub-step takes place at a temperature lower than the temperature at which the first condensation sub-step takes place. The two condensation sub- steps take place at approximately equal pressures (and at a temperature below the temperature at which the stripping step takes place) . More precisely, the second condensation sub-step takes place at a pressure lower than that of the first condensation sub-step.

The first condensation sub-step takes place in the area of a first condensation sub-zone (which is defined by the condenser 9' ) ; the second condensation sub-step takes place in the area of a second condensation sub-zone (which is defined by the condenser 9") different from the first condensation sub-zone. In other words, the condensation zone comprises a first condensation sub-zone, in the area of which at least part of said first portion condenses; and a second condensation sub- zone, which is different from the first condensation sub-zone and in the area of which the stripping fluid condenses, passing into the liquid phase.

According to embodiments not shown, there can be more, than two condensation sub-steps. The different condensation sub-steps take place at temperatures (lower than the stripping temperature) in decreasing sequence. In other words, in one condensation sub-step there is a temperature lower than that of the sub-step/s upstream and higher than that of the sub- step/s downstream. The different condensation sub-steps take place at pressures (lower than the stripping pressure) in decreasing sequence.

Advantageously, the condensation zone is (completely) interposed between the stripping zone and a suction device. The suction device maintains said pressures during the steps of stripping and condensation in the stripping zone and in the condensation zone respectively.

Advantageously, the method comprises a recirculation step during which (at least part of) the stripping fluid, at least partially separated from the first portion, is re-conveyed to the stripping zone.

Advantageously, the method furthermore comprises a purification step, during which the stripping fluid (which is in the liquid state) is separated from impurities (e.g. degradation products of the stripping fluid and/or reaction products between the stripping fluid and the base composition and/or impurities from the base composition) . In particular, the purification step takes place after the stripping fluid has been at least partially separated from the first portion and before the stripping fluid is re-conveyed to the stripping zone. The subject matter of the present invention offers considerable advantages with respect to the state of the art. In particular, and merely by way of example, the following can be cited:

- the costs of construction of the plants and implementation of the method are relatively low; in particular, the method can be carried out in plants where steam is not available (in particular, motive steam) and which therefore do not require a boiler house to produce it;

- implementation of the method has a modest environmental impact (in particular, because little energy is consumed and minimum quantities of effluents are produced) . More specifically, the subject of the present invention has the following advantages:

• (it does not make use of or) it uses very little steam (in particular, motive steam);

• it uses little electricity;

· it produces minimum quantities of effluents (in particular, because it is possible to operate in an almost closed circuit);

• it does not cause hydrolysis of the glycerides;

• it requires low investments for construction of the plants and the latter are of low complexity.

It is particularly interesting to note that in the state of the art it is not possible to identify solutions that entail a comparable combination of the above-mentioned advantages. Further characteristics of the present invention will become clear from the following description of some merely illustrative and non-limiting examples.

Examples

In all the examples described here below, the acidity of the oil is expressed in percentage by weight of oleic acid with respect to the total mass of the treated oil and it was measured, before and after the stripping, using method NGD C 10-76.

Example 1

This example describes a test of deacidi fication of a vegetable oil carried out without stripping fluid.

PREPARATION OF THE APPARATUS: a glass distillation apparatus consisting inter alia, by:

A. 2000 ml 3-necked round-bottom flask;

B. device to feed the glycerin in liquid state into the mass of oil, consisting of a gas inlet tube with valve and from a burette connected to it

C. mercury column vacuometer D. Vigreux column

E. graduated cylinder for collecting the condensed formed in Vigreux column

F. bubble condenser

G. graduated cylinder for collecting the condensed formed in bubble condenser

H. vacuum pump

I. vapour thermometer

L. heating bath

M. oil thermometer

The apparatus was assembled, so as to obtain the plant schematically illustrated in Figure 3, and carefully insulated to avoid heat losses which would have caused the condensation of stripped substances and/or of the stripping fluid in inappropriate areas.

PREPARATION OF THE OIL SAMPLE TO BE DEACIDIFIED: in a 1000 ml volumetric flask, 10 ml of bidistilled olive oil fatty acids were added to 990 ml of edible refined peanut oil. Following suitable homogenization of the sample, the acidity was measured using the above-mentioned NGD method. The value of the acidity is reported in Table 1.

PROCEDURE: the oil sample to be deacidified was introduced in the 2000 ml round-bottom 3-necked flask (A) , the apparatus was closed, and a vacuum of 4mmHg (5.33mbar) absolute pressure was produced inside it by means of the vacuum pump (H) . This vacuum, measured using the mercury column vacuometer (C) , was maintained throughout the duration of the experience. The oil was heated slowly, so it had time to release any contained gases, by means of the heating bath (L) and then maintained at a temperature of 240°C ±10. After 2 hours at this temperature no trace of condensate was visible in the two cylinders for collecting the condensate (E and G) ; it was decided therefore to stop the heating. Once cooled the oil at T below 50°C and brought the pressure inside the equipment to equilibrium with the ambient one, the apparatus was opened and a sample of oil taken to determine its acidity which, measured with the above- mentioned NGD method, turned out to be unchanged, as shown in Table 1. OBSERVATIONS:' the absence of any trace of condensate in the cylinders of collection and the acidity of the oil unchanged after 2 hours of treatment, allowed to conclude that the operating conditions in the equipment, without the use of the stripping fluid, were not such as to allow ^' the reduction, even partial, of the acidity of the treated oil.

Example 2

This example describes the deacidification of a vegetable oil carried out using glycerin (introduced in liquid status) as stripping fluid.

PROCEDURE: as soon as the sample for the measurement of the acidity of the oil in the experience described in Example 1 had been collected, the apparatus was closed and, after bringing the vacuum inside it to 5mmHg (6.67 mbar) absolute pressure, the oil was heated slowly to bring its temperature to 240°C ± 10. Once reached this temperature, the very slow introduction of glycerin by means of the specific device (B) begun .

Very soon a liquid that separated into two phases started to collect in the graduated cylinder (E) .

The experiment was stopped after having introduced about 40 ml of glycerin, in approximately 30 minutes. Once cooled down the oil at T below 50°C and brought the pressure inside the equipment to equilibrium with the ambient one, the apparatus was opened and a sample of oil taken to determine its acidity, which, measured with the above-mentioned NGD method, turned out to be drastically reduced, as shown in Table 1. OBSERVATIONS: in spite of the poor quality of the vacuum compared to the one used currently in the industry, it was easy to obtain the reduction of the acidity of the oil to an acceptable value, for example, for its subsequent use in the production of biodiesel.

The total reciprocal insolubility of glycerin and fatty acids allowed their separation by simple decantation. Liquid glycerin entering into contact with the hot oil generated explosive vaporizations within the latter, therefore in subsequent experiences we opted for introducing the stripping fluid in vapour state. However, presumably just because of the introduction of glycerin in liquid state the stripping efficiency was particularly good in this case. In fact a variation of oil acidity higher than that of Example 3 was obtained by using a lower quantity of glycerin. Such a difference in efficiency does not seem justifiable with the only difference of temperature of the oil (10°C higher in this example, compared to example 3, as reported in Table 1) during the stripping. Example 3

This example describes the deacidification of a vegetable oil carried out using glycerin (introduced in gaseous state) as stripping fluid. PREPARATION OF THE APPARATUS: it was used the glass distillation apparatus described in Example 1. The system of introduction of the stripping fluid in liquid form (B) , used in Example 2, was replaced with a system of introduction of the stripping fluid in vapour form (B' ) (not shown) similar to the introduction system of the stripping fluid in liquid form (B) from which it differed in that the burette was replaced with a small round-bottom flask, heated by means of an oil bath.

PREPARATION OF THE OIL SAMPLE: the sample was prepared and treated according to what described in Example 1. The measured value of the acidity of the sample is shown in Table 1.

PROCEDURE: the same procedure described in Example 2 was followed, with the exceptions that the oil was brought to 230°C ± 10 (instead of at 240°C ± 10) and that 60 ml (instead of 40 ml) of glycerin were introduced in gaseous state (instead of liquid state). The value of the acidity of the sample measured after the treatment is shown in Table 1.

Example 4

This example describes the deacidificat ion of a vegetable oil carried out using decane (introduced in gaseous state) as stripping fluid.

As regards the preparation of the apparatus, the preparation of the sample and the procedure was followed what described in Example 3, with the exceptions that the pressure inside the flask (A) was maintained at 7mmHg (9,33mbar) (instead of 5mmHg (6.67mbar)), that the oil was brought to 240°C ± 10 (instead of at 230°C ± 10) and that 120 ml of decane (instead of 60 ml of glycerin) were used.

A portion of the employed decane was collected in cylinder (G)

The measured values of the acidity are shown in Table 1. Example 5

This example describes the deacidification of a vegetable oil carried out using diethylene glycol (EDG) (introduced in gaseous state) as stripping fluid. As regards the preparation of the apparatus, the preparation of the sample and the procedure was followed what described in Example 4, with the exceptions that the pressure inside the flask (A) was maintained at 6mmHg (8mbar) (instead of 7mmHg (9.33mbar)) and that 100 ml of diethylene glycol (instead of 120 ml of decane) were used.

A portion of the employed diethylene glycol (DEG) was collected in cylinder (G) . The measured values of the acidity are shown in Table 1.

Table 1

Initial acidity Final acidity

(% Oleic acid) (% Oleic acid)

Example 1 1.00 1.00

Example 2 1.00 0.11

Example 3 0.99 0.18

Example 4 1.19 0.34 Example 5 1.25 0.21

In Table 2 the different working conditions for the examples described above are reported.

Table 2

Stripping Stripping Temperature Pressure Time fluid fluid (°C) (mmHg) / (mbar ) (min) quantity (ml)

Example 1 none 240 ± 10 4 / 5.33 120

Example 2 glycerin 40 240 + 10 5 / 6.67 30

Example 3 gl cerin 60 230 ± 10 5 / 6.67 35

Example 4 decane 120 240 ± 10 7 / 9.33 32

Example 5 DEG 100 240 + 10 6 / 8 40