WO2020087127A1

WO2020087127A1 - Apparatus and process for the continuous steam distillation of sandalwood

Info

Publication number: WO2020087127A1
Application number: PCT/AU2019/051202
Authority: WO
Inventors: John NORTIER; Andrew Brown; Patrick JENNINGS; Randall WIGGINS; Gerhard Burger; Victor SALES
Original assignee: Quintis (australia) Pty Ltd
Current assignee: Quintis (australia) Pty Ltd
Priority date: 2018-10-31
Filing date: 2019-10-31
Publication date: 2020-05-07
Anticipated expiration: 2021-04-30
Also published as: AU2019373095A1; AU2019373095B2

Abstract

An apparatus and process for the continuous steam distillation of sandalwood to produce high quality sandalwood oil with improved efficiency.

Description

APPARATUS AND PROCESS FOR THE CONTINUOUS STEAM DISTILLATION OF SANDALWOOD

TECHNICAL FIELD

[0001 ] The present invention provides an apparatus and process for the continuous steam distillation of sandalwood for the production of sandalwood oil.

BACKGROUND ART

[0002] The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.

[0003] Sandalwood oil is extracted from the heartwood and roots of Santalum species commonly known as sandalwood trees. The oil produced is one of the most valuable essential oils, and is sought after by perfumers as it provides a deep, rich, woody base note to perfumes and acts as a natural fixative.

[0004] While sandalwood oils come from a range of Santalum species, the quality and characteristics vary widely between the oils of the different species. The key species used in the production of sandalwood oil are Santalum album, Santalum spicatum, Santalum lanceolatum, Santalum austrocaledonicum, Santalum paniculatum and Santalum yasi. However, the vast majority of sandalwood oil produced globally at the present time, is derived from East Indian sandalwood ( Santalum album), native to southern India and the Malayan archipelago, and West Australian sandalwood ( Santalum spicatum), native to the arid areas of south west Australia.

[0005] In addition to acting as a feedstock for the production of the essential oil, sandalwood is also valued for carving, and furniture making, and for the manufacture of incense. Sandalwood trees are very slow growing, requiring up to 60 years before they are ready for harvest, and the manner in which they must be harvested, to provide heartwood and roots, is completely destructive to the tree. [0006] These factors, combined with increasing demand and very high prices for both the wood itself and the essential oil, have contributed to a notable increase in uncontrolled and illegal harvesting and destruction of the natural resource.

[0007] Methods of extracting sandalwood oil known in the art consist of batch hydrodistillation or steam distillation approaches where a finite amount of wood or biomass is processed at any given time, depending on distillation vessel size.

[0008] Heartwood and roots of sandalwood species are chipped and pulverized to a coarse grind before being placed in the batch distillation vessel. Oil yield varies greatly depending on the plant part, species, age of the tree and environmental and genetic factors. Roots sometimes yield up to 10% oil by mass, and heartwood up to 4%.

[0009] This batch process approach is inefficient in terms of oil extraction rates and yields which vary from the start of the process to the end. Invariably the process is stopped before the Sandalwood oil is completely extracted as the time to extract reduced concentrations of Sandalwood oil from the biomass increases exponentially and the energy input remains constant throughout. Spent sandalwood pulp is a valuable by-product of these distillation processes as it is used in the manufacture of incense.

[0010] Batch hydrodistillation or steam distillation typically takes 48 to 192 hours, and is terminated when the yield and/or quality of the oil ceases to be economically viable. Higher pressure and temperature steam distillation provides higher yields and reduced distillation times but invariably at the cost of reduced oil quality due to chemical or thermal degradation of desired compounds, and co-extraction of undesired compounds.

[001 1 ] As reported in Diaz-Chavez, M.L. et al. , “Biosynthesis of Sandalwood Oil: Santalum album CYP76F Cytochromes P450 Produce Santalols and Bergamotol”, PLoS ONE, 2013, Vol. 8, Issue 9, e75053, the contents of which are hereby incorporated by reference in their entirety, approximately 90% of S. album essential oil is composed of the sesquiterpene alcohols a-, b-, and ep/-p-santalol and a -exo- bergamotol. The a- and b-santalols are the most important contributors to sandalwood oil fragrance. Lanceol and a-bisabolol are also found in modest concentrations. Further minor constituents of sandalwood oil include a-, b-, and ep/^-santalene and a -exo- bergamotene. [0012] The primary alcohol compounds comprising approximately 90% of sandalwood oil are susceptible to elimination and substitution reactions, particularly under acidic conditions and in the presence of heat. All of the abovementioned compounds (including the minor constituents) of sandalwood are subject to the potential for double bond isomerisations and/or oxidation under the normal conditions encountered during steam or hydrodistillation.

[0013] The desirable constituents of sandalwood oil are particularly susceptible to thermal or chemical degradation, isomerisations and/or oxidation when freely exposed to air at vapor temperature. Increasing steam temperature and pressure increases yields and/or reduces distillation times but reduces oil quality due to chemical and/or thermal degradation of desired compounds, and co-extraction of undesired compounds. Similarly, increasing the distillation time in an attempt to increase yields invariably results in decay and breakdown of the sandalwood feedstock, leading to the release and co-extraction of undesirable compounds which are adverse to the olfactory quality of the oil. Taken together, these factors account, at least in part, for the high variability observed in the quality of commercially available sandalwood oil.

[0014] For these reasons, the quality assessment of sandalwood oil is subject to International Quality Standards (ISOs), for example West Australian sandalwood oil is subject to ISO 22769:2009 and East Indian sandalwood oil is subject to ISO 3518:2002, both of which specify physical and chemical characteristics such as density, refractive index, optical rotation, solubility, ester number and minimum alcohol (santalol) content, all of which must be met in order for the product to be marketed and sold as high quality sandalwood oil.

[0015] Processes for the extraction of sandalwood oil using chemical agents or solvents such as subcritical carbon dioxide, benzene, diethyl ether or ethanol are also known in the art, and comparisons of their extraction efficiencies and the quality of the oil produced have been published, for example in Nautiyal, O. H.“Process optimization of sandalwood ( Santalum album) oil extraction by subcritical carbon dioxide and conventional techniques”, Indian Journal of Chemical Technology, Vol. 21 , July 2014, pp 290-297, the contents of which are hereby incorporated in their entirety.

[0016] Such methods are capable of providing sandalwood oil of a comparable quality to steam or hydrodistillation methods. However these methods are too expensive to be economically viable on an industrial scale. In the case of subcritical carbon dioxide extraction, the very high pressures required impart significant extra cost, including maintenance costs, related to the high pressure equipment involved, and also bring additional hazards to the production environment. The use of organic solvents to perform the extraction also gives rise to significant extra costs, particularly associated with the need to completely extract the solvent from the oil product, the need to recycle the solvent (due to its high cost), potential fire hazards due to the flammability of such solvents, the toxicity of such solvents, and the potential for unfavorable chemical reactions between the solvent and the sandalwood oil.

[0017] Previously known continuous distillation processes for the extraction of other (non-sandalwood) oils from other (non-sandalwood) vegetable or biomass sources suffer from operational extremes which, if applied to the extraction of sandalwood oil, would be economically unviable due to the required energy inputs, or resultant extraction efficiencies, or would result in the production of poor quality product, not falling within the various ISO specifications for sandalwood oil, due to chemical or thermal degradation of the delicate aromatic constituents of the oil, or due to the co-extraction of undesirable compounds from the feedstock.

[0018] Previously known continuous distillation processes for the extraction of other (non-sandalwood) oils from other (non-sandalwood) vegetable or biomass sources also fail to limit and/or prevent the infiltration of air into the distillation vessel, resulting in excessive exposure of the volatilized oil to air at vapor temperature which, if applied to the extraction of sandalwood oil, would be economically unviable due to the production of poor quality product, not falling within the various ISO specifications for sandalwood oil, arising from air contamination, chemical and/or thermal degradation and isomerization and/or oxidation of the delicate aromatic constituents of the oil.

[0019] Unlike many other biomass and vegetable oil extraction methods, temperature control throughout the reaction chamber is critical to avoid co-extraction of undesirable compounds present in the sandalwood which would negate or diminish the aromas and quality of the sandalwood oil.

[0020] The production of high quality sandalwood oil is an important factor in supporting the economics of sandalwood as a high value commodity and a diminishing natural resource. If large quantities of poor quality sandalwood oil were produced, this would have the potential to substantially undermine the value of sandalwood giving rise to a significant negative economic impact, particularly in countries currently investing in plantations of sandalwood to address the increasingly unsustainable scarcity of the feedstock.

[0021 ] Further, for a given sandalwood feedstock there is an optimal period of time at a specified uniform temperature and pressure before which the undesirable compounds in the sandalwood begin to be released in any appreciable amount, in either solid, liquid or volatilized form, due to the accelerated deterioration of the sandalwood during the distillation process. Overexposure to steam results in the breakdown of the woody biomass feedstock leading to the release and co-extraction of undesirable compounds which are adverse to the olfactory quality of the oil.

[0022] Attempts to increase the yield of sandalwood oil by reducing the particle or chip size of the sandalwood feedstock are invariably limited by the fact that smaller particle or chip size feedstock requires a higher pressure of steam to produce the required steam flow rate for sandalwood oil extraction, and higher steam pressures result in higher steam temperatures. A practical limitation arises where the required temperature and pressure of steam for a smaller particle or chip size feedstock is so high that the quality of the oil is negatively affected, due to thermal degradation and/or an increased rate of chemical degradation of the desirable components in the sandalwood oil.

[0023] Because of the high degree of variability in the properties of available sandalwood feedstocks, due to factors including but not limited to particle or chip size, species, plant part, age of the tree and environmental and genetic factors, there is no single optimal set of conditions for steam distillation of sandalwood that balances the interests of achieving an economically viable yield with an acceptable level of quality in the oil produced.

[0024] The present invention seeks to overcome, or at least ameliorate, one or more of the deficiencies of the prior art mentioned above, or to provide an improved alternative to existing inefficient approaches to the steam distillation of sandalwood.

[0025] It is against this background that embodiments of the present invention have been developed. SUMMARY OF INVENTION

[0026] The invention herein described enables the efficient extraction of sandalwood oil with properties conforming to one or more of the properties listed within the relevant ISO standards for sandalwoods, from a sandalwood feedstock, in a continuous operation over a variable time period depending on the amount and quality of the sandalwood feedstock available to be processed.

[0027] The invention herein described enables the efficient extraction of sandalwood oil with properties conforming to one or more of the properties listed within the relevant ISO standards for sandalwoods, wherein the ISO standards and their listed properties are as follows:

[0028] (a) East Indian Sandalwood oil (ISO 3518:2002)

Appearance: Clear, slightly viscous liquid.

Colour: Almost colourless to golden yellow.

Odour: Characteristic, sweet woody and persistent.

Physical characteristics:

Density: 0.968 to 0.983 @ 20°C Refractive index @ 20°C: 1.503 to 1.509 Optical rotation@ 20°C : -12 to -21 °

Solubility in 70% ethanol (v/v) @ 20°C: < 5 volumes of 70% ethanol/volume of oil Chemical characteristics:

Ester value: max 10

Total primary alcohol content, calculated as santalol: 90% minimum [0029] (b) Australian Sandalwood oil (ISO 22769:2009)

Aspect: Clear, viscous liquid at 20°C.

Colour: Almost colourless to yellow Odour: Sweet, woody and persistent.

Physical characteristics:

Density: 0.945 to 0.980 @ 20°C Refractive index @ 20°C: 1.500 to 1.517 Optical rotation@ 20°C : -16 to +4°

Acid number: maximum 5

[0030] The skilled artisan will be aware that aside from conforming with one or more parameters of the abovementioned ISO standards, in order for a particular sample of sandalwood oil to be useful to the fragrance and perfumery industries, it must also exhibit the desired odour profile. Desirable odour profiles are typically determined and defined by the buyer. Examples of desirable odour profiles for Santalum album (East indian sandalwood oil) and Santalum spicatum (Australian sandalwood oil) are provided below:

(a) East Indian Sandalwood oil (Santalum album) odour profile

The olfactory character of Indian sandalwood oil is sweet, nutty and diffuse in the top notes. The lactonic, slight hay, woody and sweet heart notes complement the woody, slightly spicy base. The oil has a true sandalwood character, the nuttiness being sustained throughout the whole chord, and the dry-down is tenacious, sweet and woody.

(b) Australian Sandalwood oil (Santalum spicatum) odour profile

The olfactory character of Australian Sandalwood oil is powerful, sweet and diffuse in the top notes. The woody, smoky and sweet heart notes complement the warm and rich balsamic base. It has a true sandalwood character throughout the whole chord, with a tenacious woody dry-down. [0031 ] The inventors have recognised a need to maximize the efficiency and quality of extraction of sandalwood oil from sandalwood; a valuable and diminishing natural resource.

[0032] In one aspect, the continuous steam distillation apparatus of the invention comprises means by which the continuous throughput of sandalwood feedstock and efficient extraction of quality sandalwood oil therefrom can be achieved while maintaining desired optimal extraction conditions within the distillation vessel, and without substantial fluctuations in temperature gradients, operating pressure or steam flow rate within the distillation vessel.

[0033] The inventors have recognised a need to address the high degree of variability in the properties of available sandalwood feedstocks, due to factors including but not limited to species, plant part, age of the tree and environmental and genetic factors, and the resultant fact that there is no single, optimal set of conditions for steam distillation of sandalwood that balances the interests of achieving an economically viable yield with an acceptable level of quality in the oil produced.

[0034] The inventors have recognised a need to provide an apparatus and process for the continuous steam distillation of sandalwood that allows process parameters such as but not limited to temperature, operating pressure and distillation time to be monitored, varied and optimized in real time to provide maximum yield of sandalwood oil and efficiency of extraction, to account for the high degree of variability in available feedstocks due to species, environmental and genetic factors, while minimizing chemical and thermal degradation of the desirable and highly sought after aromatic compounds of the oil product, and also minimizing the co-extraction of undesirable compounds.

[0035] In one aspect, the continuous steam distillation apparatus of the invention comprises a fully integrated control system, adapted to be programmable, for optimising a continuous sandalwood steam distillation and oil extraction process, with process parametric feedback to ensure that the extraction rate for sandalwood oil and the yield and quality thereof, may be optimised whilst avoiding temperature and operating pressure extremes which would cause deterioration of the sandalwood oil quality. [0036] In one aspect, the invention comprises a method for the continuous steam distillation of sandalwood, wherein a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam at a substantially constant temperature, a substantially constant operating pressure and a substantially constant steam flow rate, wherein the temperature, operating pressure and steam flow rate have been previously optimised for the particular sandalwood feedstock to provide a high sandalwood oil extraction rate and yield whilst avoiding temperature and operating pressure extremes which would cause deterioration of the sandalwood oil quality.

[0037] In one aspect, the invention comprises a method for the continuous steam distillation of sandalwood oil from a sandalwood feedstock containing sandalwood oil, the method comprising the steps of:

Introducing the sandalwood feedstock into an inlet sub-chamber of a steam distillation apparatus;

Adjusting the pressure of the inlet sub-chamber to a predetermined operating pressure;

Heating the sandalwood feedstock in the inlet sub-chamber to a predetermined temperature;

Introducing the sandalwood feedstock from the inlet sub-chamber into a distillation vessel, wherein the operating pressure and temperature of the distillation vessel are substantially the same as the predetermined operating pressure and temperature;

Passing the sandalwood feedstock through the distillation vessel;

Passing steam through the distillation vessel in a direction concurrent or counter- current to the sandalwood feedstock, thereby extracting sandalwood oil from the feedstock and providing a sandalwood oil-enriched steam and a sandalwood oil- depleted spent sandalwood feedstock by-product;

Passing the sandalwood oil-enriched steam from the distillation chamber into a first outlet sub-chamber;

Adjusting the pressure of the first outlet sub-chamber to atmospheric pressure; Passing the sandalwood oil-enriched steam at atmospheric pressure from the first outlet sub-chamber to a heat exchanger or condenser;

Condensing the sandalwood enriched steam to produce a mixture of sandalwood oil and water;

Separating the mixture of sandalwood oil and water;

Collecting the separated sandalwood oil;

Optionally, recycling the separated water to a steam generation apparatus for producing further steam for passing through the distillation vessel in a direction concurrent or counter-current to the sandalwood feedstock;

Passing the sandalwood oil-depleted spent sandalwood feedstock by-product from the distillation chamber into a second outlet sub-chamber;

Adjusting the pressure of the second outlet sub-chamber to atmospheric pressure; and

Collecting the sandalwood oil-depleted spent sandalwood feedstock by-product from the second outlet sub-chamber.

[0038] In a preferred form of the invention, the method steps are performed in a continuous manner.

[0039] In one form of the invention, the predetermined temperature is a temperature within the range 95.1 °C to 120.2°C.

[0040] In a preferred form of the invention, the predetermined temperature is a temperature within the range 98°C to 117°C.

[0041 ] In a preferred form of the invention, the predetermined temperature is a temperature within the range 100.2°C to 1 16.5°C.

[0042] In a particularly preferred form of the invention, the predetermined temperature is a temperature within the range 105°C to 1 15°C.

[0043] In a particularly preferred form of the invention, the predetermined temperature is a temperature within the range 105°C to 1 12°C. [0044] In one form of the invention, the predetermined operating pressure is a pressure within the range 101 kPa to 200 kPa.

[0045] In a preferred form of the invention, the predetermined operating pressure is a pressure within the range 101 kPa to 175 kPa.

[0046] In a particularly preferred form of the invention, the predetermined operating pressure is a pressure within the range 101 kPa to 165 kPa or 101 kPa to 140 kPa.

[0047] In a particularly preferred form of the invention, the predetermined operating pressure is a pressure within the range 1 15 kPa to 145 kPa.

[0048] In a particularly preferred form of the invention, the predetermined operating pressure is a pressure within the range 120 kPa to 140 kPa.

[0049] In one form of the invention, the step of passing the sandalwood feedstock through the distillation vessel comprises passing the sandalwood feedstock through the distillation vessel at a predetermined rate, such that the sandalwood oil extraction rate is between 0.01 and 15 grams per kilogram of steam per hour.

[0050] In a preferred form of the invention, the sandalwood oil extraction rate for a specific sandalwood grade containing 18% heartwood on average is between 0.01 and 10 grams per kilogram of steam per hour.

[0051 ] In a particularly preferred form of the invention, the sandalwood oil extraction rate for a specific sandalwood grade containing 18% heartwood on average is between 0.01 and 5 grams per kilogram of steam per hour.

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Further features of the present invention are more fully described in the following description of several non-limiting embodiments thereof. This description is included solely for the purposes of exemplifying the present invention. It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above. The description will be made with reference to the accompanying drawings in which: Figure 1 is a schematic diagram of an apparatus for continuous steam distillation of sandalwood according to an embodiment of the invention, depicting an inlet sub-chamber for inlet of sandalwood (1 ); control valves (2); distillation vessel (3); thermal boundaries (4); powered mechanical stirrer mixer and shaft (5); powered mechanical device (6); outlet sub-chamber for outlet of sandalwood (7); inlet for steam supply and controlling valve (8); outlet for steam and sandalwood oil (9); control system (10); and control system electrical connections to the various equipment control units and parametric feedback sensors (1 1 ).

Figure 2 is a Gas Chromatographic analysis trace of Sample 10 of the continuous distillation process of Example 1.

Figure 3 is a Gas Chromatographic analysis trace of Sample 36 of the continuous distillation process of Example 2.

Figure 4 is a Gas Chromatographic analysis trace of Sample 50 of the continuous distillation process of Example 3.

Figure 5 is a Gas Chromatographic analysis trace of Sample 2 of the prior art batch distillation process of Example 3.

DETAILED DESCRIPTION OF THE INVENTION

[0053] The following description of the invention represents a preferred apparatus and method but is in no way intended to limit the scope of the invention as a plurality of alternatives and modifications, known to people experienced in the art, exist.

[0054] Only the core aspects of the invention required to enable it are described here and no elaboration is made with respect to other peripheral equipment which may be purchased off the shelf, for example, in regards to materials handling and steam generation, condensation and flow control, which make this invention viable.

[0055] In one aspect, the apparatus of the invention comprises a distillation vessel for the continuous steam distillation of sandalwood, in which the steam and sandalwood pass through the vessel in a counter-flow manner. [0056] In one aspect, the apparatus of the invention comprises a distillation vessel for the continuous steam distillation of sandalwood, in which the steam and sandalwood flow in the same direction, in a concurrent-flow manner.

[0057] In one aspect, the apparatus of the invention comprises a means by which the continuous addition of fresh sandalwood feedstock into the distillation vessel and the continuous removal of spent sandalwood feedstock from the distillation vessel, is accomplished without substantially altering the temperature gradient within the distillation vessel.

[0058] In one aspect, the apparatus of the invention comprises a means by which the continuous addition of fresh sandalwood feedstock into the distillation vessel and the continuous removal of spent sandalwood feedstock from the distillation vessel, is accomplished without substantially altering the operating pressure within the distillation vessel.

[0059] In one aspect, the apparatus of the invention comprises a means by which the continuous addition of fresh sandalwood feedstock into the distillation vessel and the continuous removal of spent sandalwood feedstock from the distillation vessel, is accomplished without substantially altering the steam flow rate within the distillation vessel.

[0060] In one aspect, the apparatus of the invention comprises a means by which the continuous addition of fresh sandalwood feedstock into the distillation vessel and the continuous removal of spent sandalwood feedstock from the distillation vessel, is accomplished without substantially altering the temperature gradient, operating pressure or steam flow rate within the distillation vessel.

[0061 ] In one aspect, the apparatus of the invention comprises a means by which the continuous movement of sandalwood feedstock through the distillation vessel, is accomplished whilst maintaining substantially isothermal conditions within the distillation vessel.

[0062] In one aspect, the apparatus of the invention comprises a means by which the continuous movement of sandalwood feedstock through the distillation vessel, is accomplished whilst maintaining substantially isobaric conditions within the distillation vessel. [0063] In one aspect, the apparatus of the invention comprises a means by which the continuous movement of sandalwood feedstock through the distillation vessel, is accomplished whilst maintaining substantially homogeneous steam flow conditions within the distillation vessel.

[0064] In one aspect, the apparatus of the invention comprises a means by which the continuous addition of fresh sandalwood feedstock into the distillation vessel and the continuous removal of spent sandalwood feedstock from the distillation vessel, is accomplished without substantially altering the temperature gradient, operating pressure or steam flow rate within the distillation vessel wherein the means of not substantially altering the temperature gradient, operating pressure or steam flow rate is provided by one or more inlet sub-chambers and one or more outlet sub-chambers, wherein the sub-chambers are adapted to allow for external atmospheric conditions to be purged and equalised with the internal temperature and operating pressure conditions of the distillation vessel when the sub-chambers are isolated from the internal distillation vessel, in order to prevent changes to the internal distillation vessel conditions when the sub-chambers are subsequently opened to the internal distillation vessel to allow for feedstock throughput, thereby maintaining the temperature gradient, operating pressure and steam flow rate inside the distillation vessel.

[0065] In a preferred aspect, the apparatus for the continuous steam distillation of sandalwood in accordance with the invention comprises; a distillation vessel for the continuous steam distillation of sandalwood, in which the steam and sandalwood pass through the vessel in a concurrent or counterflow manner; and a means by which the continuous throughput of sandalwood feedstock, comprising the continuous addition of fresh sandalwood feedstock into the distillation vessel and the continuous removal of spent sandalwood feedstock from the distillation vessel, is accomplished without substantially altering the temperature gradient, operating pressure or steam flow rate within the distillation vessel; wherein the means of not substantially altering the temperature gradient, operating pressure or steam flow rate is provided by one or more inlet sub-chambers and one or more outlet sub-chambers, wherein; the one or more inlet sub-chambers are adapted to allow for the external atmospheric conditions to be isolated from the inlet sub-chambers, so that the inlet sub chambers may be purged and/or equalised with the internal temperature and operating pressure conditions of the distillation vessel when the inlet sub chambers are isolated from the external atmospheric conditions and the internal distillation vessel, in order to prevent changes to the internal distillation vessel conditions when the inlet sub-chambers are subsequently opened to the internal distillation vessel to allow for feedstock throughput, thereby maintaining the temperature gradient, operating pressure and steam flow rate inside the distillation vessel; and the one or more outlet sub-chambers are adapted to allow for the internal temperature and operating pressure conditions of the distillation vessel to be isolated from the outlet sub-chambers, so that the outlet sub-chambers may be purged and/or equalised with the external atmospheric conditions when the outlet sub-chambers are isolated from the internal distillation vessel, in order to prevent changes to the internal distillation vessel conditions when the outlet sub chambers are subsequently opened to the external atmospheric conditions to allow for feedstock throughput, thereby maintaining the temperature gradient, operating pressure and steam flow rate inside the distillation vessel; and wherein the one or more inlet sub-chambers and one or more outlet sub-chambers each comprise two or more control valves, adapted to isolate the sub-chambers from the external atmospheric conditions and/or the internal distillation vessel conditions during purge, equalisation or feedstock throughput stages.

[0066] Advantageously, the one or more inlet sub-chambers and one or more outlet sub-chambers each comprising two or more control valves, adapted to isolate the sub chambers from the external atmospheric conditions and/or the internal distillation vessel conditions during purge, equalisation or feedstock throughput stages perform the function of limiting and/or preventing the infiltration of air into the distillation vessel, thereby preventing excessive exposure of the volatilized oil to air at vapor temperature which would otherwise result in air contamination, chemical and/or thermal degradation and isomerization and/or oxidation of the delicate aromatic constituents of the oil. Advantageously, the one or more inlet sub-chambers and one or more outlet sub chambers each comprising two or more control valves, also prevent and/or limit the escape of any positive pressure of steam from within the distillation vessel, thereby preventing and/or limiting the escape of any valuable volatilized sandalwood oil.

[0067] In one aspect, the apparatus of the invention comprises a means by which continuous movement of sandalwood feedstock into and out of the distillation vessel, is accomplished whilst maintaining substantially isothermal or substantially isobaric conditions within the distillation vessel, wherein the means of maintaining substantially isothermal or substantially isobaric conditions during movement of sandalwood feedstock through the distillation vessel is provided by one or more inlet sub-chambers and one or more outlet sub-chambers, wherein the sub-chambers are adapted to allow for external atmospheric conditions to be purged and equalised with the internal temperature and operating pressure conditions of the distillation vessel when the sub chambers are isolated from the internal distillation vessel conditions, in order to prevent changes to the internal distillation vessel conditions when the sub-chambers are subsequently opened to the internal distillation vessel to allow for feedstock throughput, thereby maintaining the substantially isothermal or substantially isobaric conditions within the distillation vessel.

[0068] In one aspect, the one or more inlet sub-chambers and one or more outlet sub chambers of the aforementioned aspects of the invention comprise control valves, adapted to isolate the sub-chambers from the external atmospheric conditions and/or the internal distillation vessel conditions during purge, equalisation or feedstock throughput stages.

[0069] In one aspect, the one or more inlet sub-chambers of the aforementioned aspects of the invention comprise control valves, adapted to isolate the inlet sub chambers from the internal distillation vessel conditions as fresh feedstock enters the inlet sub-chambers.

[0070] In one aspect, the one or more inlet sub-chambers of the aforementioned aspects of the invention comprise control valves, adapted to isolate the inlet sub chambers from both the external atmospheric conditions and from the internal distillation vessel conditions as the conditions within the isolated inlet sub-chambers containing fresh feedstock are equalised with the internal distillation vessel conditions.

[0071 ] In one aspect, the one or more inlet sub-chambers of the aforementioned aspects of the invention comprise control valves, adapted to isolate the inlet sub chambers from the external atmospheric conditions as fresh feedstock enters the distillation vessel from the inlet sub-chambers.

[0072] In one aspect, the one or more inlet sub-chambers of the aforementioned aspects of the invention comprise control valves, adapted to isolate the inlet sub chambers from the internal distillation vessel conditions as the inlet sub-chambers are purged of the internal distillation vessel conditions subsequent to having dispensed fresh feedstock into the distillation chamber.

[0073] In one aspect, the one or more outlet sub-chambers of the aforementioned aspects of the invention comprise control valves, adapted to isolate the outlet sub chambers from the external atmospheric conditions as spent feedstock exits the distillation vessel and enters the outlet sub-chambers.

[0074] In one aspect, the one or more outlet sub-chambers of the aforementioned aspects of the invention comprise control valves, adapted to isolate the outlet sub chambers from both the internal distillation vessel conditions and from the external atmospheric conditions as the conditions within the isolated outlet sub-chambers containing spent feedstock are equalised with the external atmospheric conditions, prior to disposal of spent feedstock from the outlet sub-chamber.

[0075] In one aspect, the one or more outlet sub-chambers of the aforementioned aspects of the invention comprise control valves, adapted to isolate the outlet sub chambers from the internal distillation vessel conditions as spent feedstock exits the outlet sub-chambers.

[0076] In one aspect, the one or more outlet sub-chambers of the aforementioned aspects of the invention comprise control valves, adapted to isolate the outlet sub chambers from both the internal distillation vessel conditions and from the external atmospheric conditions as the conditions within the isolated outlet sub-chambers containing spent feedstock are equalised with the internal distillation vessel conditions. [0077] In one aspect, the addition of fresh sandalwood feedstock to the distillation vessel is assisted by gravity.

[0078] In one aspect, the addition of fresh sandalwood feedstock to the distillation vessel is assisted by mechanical means, such as but not limited to a conveyor belt or auger.

[0079] In one aspect, the removal of spent sandalwood feedstock from the distillation vessel is assisted by gravity.

[0080] In one aspect, the removal of spent sandalwood feedstock from the distillation vessel is assisted by mechanical means, such as but not limited to a conveyor belt or auger.

[0081 ] In one aspect, the apparatus of the invention comprises a distillation vessel for the continuous steam distillation of sandalwood, in which the steam and sandalwood come into contact with each other in a manner, wherein the sandalwood feedstock passes through the distillation vessel along the longitudinal axis of the distillation vessel, while the steam passes through the distillation vessel in the direction concurrent or counter-current to the feedstock,.

[0082] In one aspect, the distillation vessel of the apparatus of the invention comprises one or more thermal boundaries surrounding the distillation vessel, adapted to insulate the interior of the distillation vessel from the external ambient temperature and further maintain substantially isothermal conditions within the distillation vessel.

[0083] In one aspect, the distillation vessel of the apparatus of the invention comprises one or more thermal boundaries surrounding the distillation vessel, adapted to thermally regulate the interior of the distillation vessel and isolate it from the external ambient temperature thereby further maintaining substantially isothermal conditions within the distillation vessel.

[0084] In one aspect, the one or more thermal boundaries surrounding the distillation vessel, comprise means to circulate heated fluids within the thermal boundary, thereby providing an isothermal barrier in the periphery of the distillation vessel to assist with maintaining substantially isothermal conditions within the distillation vessel. [0085] In one aspect, the apparatus of the invention comprises an internal mechanical stirrer mixer adapted to eliminate or minimise the development of detrimental steam blow holes and cavities in the feedstock within the distillation vessel, which result in inhomogeneous steam flow through the distillation vessel, reducing the distillation efficiency.

[0086] In one aspect, typical steam operating temperatures for the apparatus of the invention range from 95.1 °C to 120.2°C inside the distillation vessel, varying according to the type of sandalwood feedstock and distillation rate required.

[0087] In a preferred form of the invention, the steam operating temperature for the apparatus of the invention is a temperature within the range 98°C to 1 17°C.

[0088] In a preferred form of the invention, the steam operating temperature for the apparatus of the invention is a temperature within the range 100.2°C to 116.5°C.

[0089] In a particularly preferred form of the invention, the steam operating temperature for the apparatus of the invention is a temperature within the range 105°C to 1 15°C.

[0090] In a particularly preferred form of the invention, the steam operating temperature for the apparatus of the invention is a temperature within the range 105°C to 112°C.

[0091 ] As used herein and throughout this specification, the term“operating pressure” refers to the absolute internal pressure of the distillation vessel of the apparatus, and is measured with reference to a complete vacuum being equal to zero kPa. Therefore, an operating pressure of 101 kPa, is an operating pressure that is equivalent to the external atmospheric pressure at Standard atmospheric Temperature and Pressure (STP). This is achieved by supplying steam to the distillation vessel, wherein the steam is supplied at a pressure sufficient to provide the operating pressure within the distillation vessel.

[0092] In one form of the invention, typical operating pressures for the apparatus of the invention range from 101 kPa to 200 kPa inside the distillation vessel, varying according to the type of sandalwood feedstock and distillation rate required.

[0093] In a preferred form of the invention, the typical operating pressure for the apparatus of the invention is a pressure within the range 101 kPa to 175 kPa. [0094] In a particularly preferred form of the invention, the typical operating pressure for the apparatus of the invention is a pressure within the range 101 kPa to 165 kPa, 101 kPa to 140 kPa.

[0095] In a particularly preferred form of the invention, the typical operating pressure for the apparatus of the invention is a pressure within the range 1 15 kPa to 145 kPa.

[0096] In a particularly preferred form of the invention, the typical operating pressure for the apparatus of the invention is a pressure within the range 120 kPa to 140 kPa.

[0097] In one form of the invention, the throughput of the sandalwood feedstock passing through the distillation vessel occurs at a predetermined rate, such that the sandalwood oil extraction rate is between 0.01 and 15 grams per kilogram of steam per hour, varying according to the type of sandalwood feedstock and distillation rate required.

[0098] In a preferred form of the invention, the sandalwood oil extraction rate for a specific sandalwood grade containing 18% heartwood on average is between 0.01 and 10 grams per kilogram of steam per hour.

[0099] In a particularly preferred form of the invention, the the sandalwood oil extraction rate for a specific sandalwood grade containing 18% heartwood on average is between 0.01 and 5 grams per kilogram of steam per hour.

[00100] In one aspect, the one or more thermal boundaries, in the periphery of the distillation vessel of the apparatus of the invention can be controlled to between -5°C to 55°C higher than the internal temperature of the distillation vessel by circulating heated fluids through the one or more thermal boundaries.

[00101 ] In one aspect, steam is generated through a standard steam generation device and is regulated to the distillation vessel of the apparatus of the invention via a steam supply inlet equipped with a control valve, at the required temperature and pressure for the specific type of sandalwood feedstock and appropriate extraction rate.

[00102] In one aspect, exhaust of the steam carrying the dissolved gaseous or near gaseous sandalwood oil is channelled from the outlet of the distillation vessel of the apparatus of the invention through to a commercially available or custom built heat exchanger or condenser and the collection and separation method of sandalwood oil from the condensate is achieved with standard commercially available equipment or equipment previously known in the art.

[00103] In one aspect, the apparatus for the continuous distillation of sandalwood of the invention comprises a control system, adapted to monitor various physical chemical and temporal parameters of the continuous sandalwood distillation process in real time.

[00104] In one aspect, the apparatus for the continuous distillation of sandalwood of the invention comprises a control system, adapted to log various physical chemical and temporal parameters of the continuous sandalwood distillation process in real time.

[00105] In one aspect, the apparatus for the continuous distillation of sandalwood of the invention comprises a plurality of parametric feedback sensors, adapted to operably communicate with a control system to provide parametric feedback to the control system regarding various physical, chemical and temporal parameters of the continuous sandalwood distillation process in real time.

[00106] In one aspect, the apparatus for the continuous distillation of sandalwood of the invention comprises a plurality of parametric feedback sensors, adapted to operably communicate with a control system to provide parametric feedback to the control system regarding various physical, chemical and temporal parameters of the continuous sandalwood distillation process in real time, wherein the sensors are adapted to provide feedback in relation to one or more parameters selected from but not limited to the group comprising inlet sub-chamber pressure, inlet sub-chamber temperature, distillation vessel temperature, distillation vessel operating pressure, outlet sub-chamber pressure, outlet sub-chamber temperature, rate of addition of fresh sandalwood feedstock, rate of removal of spent sandalwood feedstock, flow rate of sandalwood feedstock through distillation vessel, dwell time of feedstock within distillation vessel, steam supply inlet pressure, steam supply inlet temperature, steam and sandalwood oil outlet pressure, steam and sandalwood oil outlet temperature, flow rate of steam through distillation vessel, mixing rate of mechanical stirrer mixer, temperature of fluids circulating through one or more thermal boundaries, rate of circulation of fluids circulating through one or more thermal boundaries, rate of condensation of sandalwood oil at heat exchanger or condenser, colour of sandalwood oil at collection and separation point, refractive index of sandalwood oil at collection and separation point, alpha and/or beta santalol content of sandalwood oil at collection and separation point and optical rotation of sandalwood oil at collection and separation point.

[00107] In one aspect, the apparatus for the continuous distillation of sandalwood of the invention comprises one or more equipment control units, adapted to control one or more mechanically, electrically or physically actuated means within the apparatus.

[00108] In one aspect, the apparatus for the continuous distillation of sandalwood of the invention comprises one or more equipment control units, adapted to control one or more mechanically, electrically or physically actuated means within the apparatus, said mechanically, electrically or physically actuated means being selected from, but not limited to, the group comprising; actuation means for inlet sub-chamber control valves, actuation means for outlet sub-chamber control valves, pumping means for circulating heated fluids within one or more thermal boundaries surrounding the distillation vessel, temperature control means for controlling the temperature of heated fluids circulating within one or more thermal boundaries surrounding the distillation vessel, actuation means for pressure control valve at outlet for steam and sandalwood oil, actuation means for control valve at inlet for steam supply, drive means for powered mechanical stirrer mixer and shaft, drive means for mechanically assisted addition of fresh sandalwood feedstock to the distillation vessel, and drive means for mechanically assisted removal of spent sandalwood feedstock from the distillation vessel.

[00109] In one aspect, the apparatus for the continuous distillation of sandalwood of the invention comprises a control system, adapted to adjust various physical chemical and temporal parameters of the continuous sandalwood distillation process in real time, by issuing control commands to one or more equipment control units and thereby provide optimal extraction rates and yields for sandalwood oil whilst avoiding temperature and operating pressure extremes detrimental to the sandalwood oil quality.

[001 10] In one aspect, the apparatus for the continuous distillation of sandalwood of the invention comprises a control system, adapted to log various physical chemical and temporal parameters of the continuous sandalwood distillation process in real time, and thereby produce a database relating the various physical chemical and temporal parameters to the conditions of the continuous sandalwood distillation process, and to the particular qualities of the sandalwood feedstock used, and the resultant yield and quality of the sandalwood oil product produced, wherein the database may be used to optimise future extraction processes involving the same or similar sandalwood feedstock, for optimal yield and quality of sandalwood oil.

[001 1 1 ] The inventors have found that it is particularly advantageous to log various physical chemical and temporal parameters of the continuous sandalwood distillation process in real time, and thereby produce a database relating the various physical chemical and temporal parameters to the conditions of the continuous sandalwood distillation process, and to the particular qualities of the sandalwood feedstock used, and the resultant yield and quality of the sandalwood oil product produced, wherein the database may be used to optimise future extraction processes involving the same or similar sandalwood feedstock, for optimal yield and quality of sandalwood oil. The advantages of storing such data for future use and for the optimisation of future runs are many and include but are not limited to, the ability to reproduce similar yields, and or produce sandalwood oil of a similar quality when conducting runs with similar feedstocks, and the ability to satisfy a particular sandalwood odour profile as determined and defined by a particular buyer, with a particular purpose for the sandalwood oil in mind.

[001 12] In one aspect, the apparatus for the continuous distillation of sandalwood of the invention comprises a control system, adapted to receive parametric feedback from one or more parametric feedback sensors, and based on the information received, adjust various physical chemical and temporal parameters of the continuous sandalwood distillation process in real time, by issuing control commands to one or more equipment control units and thereby provide optimal extraction rates and yields for sandalwood oil whilst avoiding temperature and operating pressure extremes detrimental to the sandalwood oil quality.

[001 13] In one aspect, the apparatus for the continuous distillation of sandalwood of the invention comprises a control system that may be programmed to provide optimal extraction rates and yield and quality of sandalwood oil from a particular sandalwood feedstock, based on previously logged data in relation to the same or similar sandalwood feedstock.

[001 14] In one aspect, the apparatus for the continuous distillation of sandalwood of the invention comprises a control system that may be programmed to provide optimal extraction rates and yield and quality of sandalwood oil from a particular sandalwood feedstock, based on previously logged data in relation to the same or similar sandalwood feedstock, wherein the logging of data and the programming of the control system for optimal extraction rates and yield and quality of sandalwood oil from a particular sandalwood feedstock may occur simultaneously so that the continuous distillation process may be continually optimised throughout an entire run of the same or similar sandalwood feedstock.

[001 15] In one aspect, the invention comprises a process for the production of sandalwood oil, using the apparatus of any of the aforementioned aspects of the invention.

[001 16] In one aspect of the invention, the spent sandalwood feedstock produced by the continuous sandalwood distillation process is a valuable, high quality by-product.

[001 17] In one aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam at a substantially constant temperature, a substantially constant operating pressure and a substantially constant steam flow rate, wherein the temperature, operating pressure, and steam flow rate have been previously optimised for the particular sandalwood feedstock to provide a high sandalwood oil extraction rate and yield whilst avoiding temperature and operating pressure extremes which would cause deterioration of the sandalwood oil quality.

[001 18] In one aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam at a substantially constant temperature in the range 95.1 °C to 120.2°C inside the distillation vessel.

[001 19] In a preferred aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam at a substantially constant temperature in the range 100.2°C to 1 16.5°C inside the distillation vessel.

[00120] In a preferred aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam at a substantially constant temperature in the range 98°C to 117°C inside the distillation vessel.

[00121 ] In a particularly preferred aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam at a substantially constant temperature in the range 105°C to 1 15°C inside the distillation vessel.

[00122] In a particularly preferred aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam at a substantially constant temperature in the range 105°C to 112°C inside the distillation vessel.

[00123] In one aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam at a substantially constant operating pressure in the range 101 kPa to 200 kPa.

[00124] In a preferred aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam at a substantially constant operating pressure in the range 101 kPa to 175 kPa.

[00125] In a particularly preferred aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam at a substantially constant operating pressure in the range 101 kPa to 165 kPa, or 101 kPa to 140 kPa.

[00126] In a particularly preferred aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam at a substantially constant operating pressure in the range 1 15 kPa to 145 kPa.

[00127] In a particularly preferred aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam at a substantially constant operating pressure in the range 120 kPa to 140 kPa. [00128] In a particularly preferred aspect, the invention comprises a method for the continuous steam distillation of sandalwood to produce sandalwood oil, characterised in that a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam at a substantially constant temperature, a substantially constant operating pressure and a substantially constant steam flow rate, wherein the temperature, operating pressure and steam flow rate have been previously optimised for the particular sandalwood feedstock to provide a high sandalwood oil extraction rate and yield whilst avoiding temperature and operating pressure extremes which would cause deterioration of the sandalwood oil quality; wherein the flow of steam is at a substantially constant temperature in the range 95.1 °C to 120.2°C, or in the range 100.2°C to 1 16.5°C, or in the range 98°C to 1 17°C, or in the range 105°C to 1 15°C, or in the range 105°C to 1 12°C inside the distillation vessel; and wherein the flow of steam is at a substantially constant operating pressure in the range 101 kPa to 200 kPa, or in the range 101 kPa to 175 kPa, or in the range 101 kPa to 165 kPa, , or in the range 101 kPa to 140 kPa, or in the range 1 15 kPa to 145 kPa, or in the range 120 kPa to 140 kPa inside the distillation vessel.

[00129] In one aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam such that the sandalwood oil extraction rate is between 0.01 and 15 grams per kilogram of steam per hour.

[00130] In a preferred aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein the sandalwood oil extraction rate for a specific sandalwood grade containing 18% heartwood on average is between 0.01 and 10 grams per kilogram of steam per hour.

[00131 ] In a particularly preferred aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein the sandalwood oil extraction rate for a specific sandalwood grade containing 18% heartwood on average is between 0.01 and 5 grams per kilogram of steam per hour. [00132] In one aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein the particular sandalwood feedstock is derived from Santalum album.

[00133] In one aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein the resultant sandalwood oil product exhibits one or more properties selected from the group comprising the following properties;

Density: 0.968 to 0.983 @ 20°C;

Refractive index @ 20°C: 1.503 to 1.509;

Optical rotation @ 20°C : -12 to -21 °;

Solubility in 70% ethanol (v/v) @ 20°C: < 5 volumes of 70% ethanol/volume of oil Ester value: max 10; or

Total alcohol content, calculated as santalol: 90% minimum.

[00134] In one aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein the resultant sandalwood oil product conforms to ISO 3518:2002.

[00135] In one aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein the particular sandalwood feedstock is derived from Santalum spicatum.

[00136] In one aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein the resultant sandalwood oil product exhibits one or more properties selected from the group comprising the following properties;

Density: 0.945 to 0.980 @ 20°C;

Refractive index @ 20°C: 1.500 to 1.517;

Optical rotation@ 20°C: -16 to +4^o;

Solubility in 70% ethanol (v/v) @ 20°C: < 5 volumes of 70% ethanol/volume of oil;

Acid number: maximum 5. [00137] In one aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein the resultant sandalwood oil product conforms to ISO 22769:2009.

[00138] In one aspect, the invention comprises a method for the continuous steam distillation of sandalwood wherein the resultant sandalwood oil product conforms to an odour profile, determined by the buyer.

[00139] It is to be understood that this invention could be employed in the oil extraction of alternative plant products other than sandalwood oil, to produce alternative high quality plant oil extracts in an efficient manner.

EXAMPLE OF THE APPARATUS OF THE INVENTION

[00140] The entire assembly of the distillation vessel and condensation and oil separation surfaces of the apparatus of the invention, including all peripheral materials handling equipment in contact with the sandalwood feedstock prior to the point at which spent feedstock is discharged from the apparatus, is preferably constructed of stainless steel 316 grade as a minimum requirement. Although this is the preferred material for construction, other materials known to the skilled addressee as suitable materials, may be substituted.

[00141 ] With reference to the integers of figure 1 of the specification, inlet sub-chamber 1 comprises control valves 2, which are mechanically actuated and controlled by the control system 10, in a sequence that ensures that the integrity of the internal distillation vessel conditions within the distillation vessel 3, is maintained and sustained. Further the sequence of actuation of inlet sub-chamber control valves 2, is time controlled by a control system operator or program to achieve the desired fresh sandalwood feedstock input rate.

[00142] The distillation vessel, 3, can be built as a single entity, as a multi-part entity, or as multiple entities operating as a single distillation unit. It is surrounded by one or more thermal boundaries 4, through which heated fluids may be circulated for optimum thermal isolation between the internal distillation vessel conditions and the external atmospheric conditions, and to assist with maintaining a desired thermal gradient or substantially isothermal conditions within the distillation vessel. The temperature and flowrate of heated fluids circulating through thermal boundaries 4 may be controlled by the control system 10 to achieve the desired thermal gradient or substantially isothermal conditions within the distillation vessel.

[00143] Thermal boundaries 4 may be further insulated with insulation material to enhance thermal isolation and reduce energy costs. Thermal boundaries 4 can be uniformly temperature controlled or of varying temperature in specific sectors to maintain desired internal temperatures and/or thermal gradients.

[00144] The powered mechanical stirrer mixer and shaft 5, assists with prevention of steam blow holes forming above it and cavities forming below it thereby assisting to maintain substantially homogeneous steam flow conditions within the distillation vessel. The powered mechanical stirrer mixer and shaft 5 may be controlled by the control system 10 to achieve the desired mixing rate required to maintain substantially homogeneous steam flow conditions within the distillation vessel.

[00145] In a particular implementation of the invention, the powered mechanical stirrer mixer and shaft 5 are driven by a VSD controlled, Delta™ VFD-E series 3 phase, 2.2 kW electric motor (shown in figure 1 ) with reduced rotation speed supplied through a BuddyBox™ gearbox (not shown in figure 1 ).

[00146] The powered mechanical device 6, removes the spent sandalwood feedstock and drops it into outlet sub-chamber, 7. The powered mechanical device may be controlled by the control system 10 to achieve the desired rate of discharge of spent sandalwood feedstock from the distillation vessel 3.

[00147] In a particular implementation of the invention, the powered mechanical device 6 is a custom designed and built auger, driven by a VSD controlled, Delta™ VFD-E series 3 phase, 2.2 kW electric motor (shown in figure 1 ) with reduced rotation speed supplied through a BuddyBox™ gearbox (not shown in figure 1 ).

[00148] The outlet sub-chamber control valves 2, in the outlet sub-chamber 7, operate and are controlled in a similar manner to inlet sub-chamber 1 and its control valves, in which they are mechanically actuated and controlled by the control system 10, in a sequence that ensures that the integrity of the internal distillation vessel conditions within the distillation vessel 3, is maintained and sustained and that ingress of air into the distillation vessel 3 is prevented and/or limited. Further the sequence of actuation of outlet sub-chamber control valves 2, is time controlled by a control system operator or program to achieve the desired spent sandalwood feedstock output rate.

[00149] In a particular implementation of the invention, the inlet sub-chamber control valves 2 and the outlet sub-chamber control valves 2, are Orbinox™ AVK I26 type knife gate valves pneumatically actuated with 6 bar of pressure.

[00150] Steam supply is provided from a steam generation facility to the distillation vessel via a steam supply inlet equipped with a control valve 8, which is controlled by control system 10, to provide optimal steam temperature, operating pressure and/or flow rate, depending on sandalwood feedstock type and the appropriate or desired extraction rate required.

[00151 ] In a particular implementation of the invention, steam supply is provided from a wood fired boiler which delivers steam to the steam supply inlet control valve 8 at a pressure in excess of 300kPa.

[00152] The steam and sandalwood oil outlet, 9, is piped to a heat exchanger or condenser apparatus for condensation and a separator for sandalwood oil capture and recovered water recirculation to the steam generation facility and/or the thermal boundary heated fluid circulation system.

[00153] In a particular implementation of the invention, throughput of feedstock into and out of the apparatus of the invention is achieved via means of materials handling equipment comprising 5” augers and aero-mechanical conveying Floveyor™ systems. Incoming sandalwood feedstock is discharged into a holding hopper and transferred to a biomass control scale feeder hopper via a Floveyor™. The controlled biomass scale feeder transfers the incoming sandalwood feedstock to a second Floveyor™ via an auger. The second Floveyor™ transfers the incoming sandalwood feedstock to the first of the inlet sub-chamber control valves 2 on top of the apparatus. The powered mechanical device 6 comprising a custom designed and made auger, operating in tandem with the powered mechanical stirrer mixer and shaft 5, draws the outgoing sandalwood feedstock towards the first of the outlet sub-chamber control valves, 2, underneath the apparatus. Another 5” auger transfers the spent sandalwood feedstock to a skip. [00154] The continuous steam distillation apparatus includes a plurality of parametric feedback sensors, which provide feedback to the control system about the present operating state of the apparatus, including information about the current operating temperatures, operating pressures, feedstock throughput rates and dwell times, steam flow conditions, mixing rates and oil extraction rates. Parametric feedback sensors may also be employed to provide qualitative information to the control system about the quality of incoming sandalwood feedstock and/or the quality of sandalwood oil arriving at the condensation and oil separation stages of the apparatus.

[00155] The control system 10, is specifically configured and programmed for the sandalwood distillation process control, parameter logging and monitoring via electrical wiring 1 1. The control system 10, can run in a number of modes, to allow for either fully automatic, partially automated or fully manual control of the distillation apparatus and process for specific purposes. It also has various capability levels for slowing the process, whilst drifting parameters are brought back into specification, stopping the process if parameter conditions reach threshold values which could be detrimental to the sandalwood oil quality or equipment operation and stopping the process in emergency situations, such as when breaches in the integrity of the operation occur.

[00156] In a particular implementation of the invention, control system 10, comprises a Delta™ DVP Series Slim CPU DVP-12SE Programmable Logic Controller with all I/O cards to suit, and a Delta™ DOP-B series Human Machine Interface (HMI), touchscreen.

[00157] In a particular implementation of the invention, parametric feedback sensors of the continuous steam distillation apparatus of the invention include Sick™ UM30 ultra sonic level sensors, IFM™ SM7004 magnetic-inductive flow meters, Sick™ LBV31 1 vibrating level sensors, PT100 temperature transducers and WIKA™ S20 pressure transducers. EXAMPLES OF THE PERFORMANCE OF THE APPARATUS OF THE INVENTION Example 1 :

[00158] Sandalwood feedstock was processed and prepared in the same manner as generally employed for prior art batch or pot distillation methods. Sandalwood trees were debarked and cut into appropriate lengths to be fed into a wood chipper and reprocessed until the wood chips pass through a US mesh 10 size sieve.

[00159] Sandalwood feedstock, containing on average 18% heartwood was used in a trial with the equipment control set in user supplied parameters mode, that is, sandalwood feed rates and steam rates were manually entered or set in the programmable logic control (PLC) system.

[00160] The Sandalwood was fed into the continuous distillation apparatus at various rates, depending on laboratory oil yield tests for user determined sub-batches of sandalwood, of between 55kg and 85 kg per hour. The resultant continuous operation extraction rate varied between 1.0 and 2.6 grams of oil per kilogram of steam per hour, over an operational period of not less than 1 week. The operating pressure was periodically varied between 1 15kPa and 145kPa absolute and the apparatus internal temperature ranged between 98°C and 1 15°C.

[00161 ] Results of the yield and quality of oil produced in this run are presented below:

[00162] Table 1 : Santalol content and Yield of Sandalwood oil samples from Ex. 1.

[00163] Gas Chromatographic analysis of Sample 10 of Ex. 1 is presented in Fig. 2. [00164] Table 2: Quality assessment and ISO compliance of Sandalwood oil from Ex. 1

Example 2:

[00165] An alternative run of the apparatus was performed, with an emphasis on producing Sandalwood oil of a higher quality. Using the same method for processing and preparing Sandalwood feedstock as Example 1 .

[00166] Sandalwood chips were prepared, at US mesh 10 size sieve, from sandalwood having an average content of 27% heartwood. The Sandalwood feedstock was supplied to the apparatus at a feed rate varying in the range 35kg to 55kg per hour. Operating pressure ranged between 120kPa and 140kPa absolute, whilst the apparatus internal temperature ranged between 105°C and 1 12°C. The resultant extraction rate ranged between 0.4 grams per kilogram of steam per hour and 1.7 grams per kilogram of steam per hour over an operational period of not less than 2 weeks.

[00167] Results of the yield and quality of oil produced in this run are presented below:

[00168] Table 3: Santalol content and Yield of Sandalwood oil samples from Ex. 2

[00169] Gas Chromatographic analysis of Sample 36 of Ex. 2 is presented in Fig. 3.

[00170] Table 4: Quality assessment and ISO compliance of Sandalwood oil from Ex. 2

Example 3:

[00171 ] A further alternative run of the apparatus was performed, distilled at a much slower rate, to investigate the quality of the sandalwood oil obtained and to provide a means for comparison to prior art batch distillation processes for the distillation of sandalwood, using the same method for processing and preparing Sandalwood feedstock as Example 2, and with the same type of feedstock as Example 2.

[00172] Sandalwood chips were prepared, at US mesh 10 size sieve, from sandalwood having an average content of 27% heartwood. The Sandalwood feedstock was supplied to the apparatus at a feed rate varying in the range 25kg to 35kg per hour. Operating pressure ranged between 101 kPa and 140kPa absolute, whilst the apparatus internal temperature ranged between 100°C and 1 12°C. The resultant extraction rate during the period in which the samples in Table 5 were taken ranged between 0.4 grams per kilogram of steam per hour and 0.6 grams per kilogram of steam per hour, and the continuous distillation was performed over an operational period of not less than 2 weeks.

[00173] Using the same feedstock as prepared for the continuous distillation process of the invention, a prior art batch distillation process was also conducted in order to compare and evaluate the performance of the continuous process, both in terms of the yield and the quality of oil produced. The initial steam flowrate for the prior art batch/pot distillation was the same as for the continuous distillation process, varying by approximately 5% throughout the run due to the inherent design limitations of the prior art apparatus and process. Internal temperatures and pressures were not monitored. The pot geometry, being different to the continuous distillation vessel, results in a steam supply pressure that varies as the steam passes through the vessel, and with time as the sandalwood biomass becomes increasingly hydrated due to saturation with steam and begins to disintegrate. The resultant average extraction rate over the period of the distillation process ranged between 0.2 grams per kilogram of steam per hour and 0.24 grams per kilogram of steam per hour. The prior art distillation process was run over an operational period of 144 hours. [00174] Table 5: Santalol content and Yield of Sandalwood oil samples from Ex. 3 continuous distillation process

[00175] Gas Chromatographic analysis of Sample 50 of the continuous distillation process of Ex. 3 is presented in Fig. 4.

[00176] Table 6: Santalol content and Yield of Sandalwood oil samples from Ex. 3 prior art batch distillation process

[00177] Gas Chromatographic analysis of Sample 2 of the prior art batch distillation process of Ex. 3 is presented in Fig. 5.

[00178] Table 7: Quality assessment and ISO compliance of Sandalwood oil from Ex. 3 continuous distillation process compared to prior art batch distillation process

[00179] The results from Examples 1 to 3 demonstrate that the continuous distillation apparatus and process of the present invention provides several surprising advantages over prior art batch distillation processes.

[00180] Examples 1 to 3 demonstrate that the continuous distillation apparatus and process of the present invention is capable of consistently producing sandalwood oil more efficiently than prior art batch distillation processes, producing sandalwood oil at a faster rate, and utilising significantly less energy in the form of steam. Example 1 demonstrates the production of high quality ISO compliant sandalwood oil at rates of up to 2.6 grams of oil per kilogram of steam per hour, as compared to the typical prior art batch process of Example 3, producing sandalwood oil at an average rate of only 0.2 grams of oil per kilogram of steam per hour.

[00181 ] Even when the continuous process of the invention is conducted at a substantially slower rate, comparable to prior art batch distillation processes as in Example 3, the continuous process of the invention is up to 3 times more efficient, producing high quality ISO compliant sandalwood oil at rates of up to 0.6 grams of oil per kilogram of steam per hour.

[00182] Examples 1 to 3 also demonstrate that the continuous distillation apparatus and process of the present invention is surprisingly capable of consistently producing sandalwood oil of a higher quality than prior art batch distillation processes. Odour profiles of samples from the continuous distillation process of the invention contain descriptors characteristic of the qualities highly sought after in the perfume and fragrance industry, including“light woody and sweet” (Example 1 ),“woody and sweet” (Example 2), and “terpenic woody, floral, dry woody, musty earthy” (Example 3), compared to “spicy, dry powdery, cardboard, woody, dry tobacco, musty, punky, pungent, wet wood, dusty nutty” (prior art batch distillation process of Example 3). Odour profile descriptors such as“punky”, “pungent”, and“wet wood” are generally characteristic of the release and extraction of undesirable compounds from the sandalwood chips due to breakdown and decay of the woody biomass during the distillation process.

[00183] Even when the continuous process of the invention is conducted at a substantially slower rate, comparable to prior art batch distillation processes as in Example 3, the continuous process of the invention extracts a comparable amount of a- santalol (46.6% vs 46.8% for the prior art batch process), while producing significantly higher amounts of desirable b-santalol (20.4% vs 19.4% for the prior art batch process).

[00184] Without wishing to be bound by theory, it is believed that the higher quality sandalwood oil produced by the present invention is a result of the fact that the distilled sandalwood feedstock is withdrawn from the distillation vessel continuously, thereby reducing the probability of wood decay and minimising the liberation of the resultant undesirable compounds, as well as the fact that the inlet and outlet sub-chambers of the invention prevent and/or limit excessive exposure of the volatilised sandalwood oil within the distillation vessel to air, thereby preventing air contamination and limiting the resultant undesirable oxidation and/or isomerisation by-products associated with excessive air exposure.

GENERAL

[00185] Those skilled in the art of sandalwood oil extraction will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. The invention includes all such variations and modifications. The invention also includes all of the steps, features, formulations and compounds referred to or indicated in the specification, individually or collectively and any and all combinations or any two or more of the steps or features.

[00186] Each document, reference, patent application or patent cited in this text is expressly incorporated herein in its entirety by reference, which means that it should be read and considered by the reader as part of this text. That the document, reference, patent application or patent cited in this text is not repeated in this text is merely for reasons of conciseness.

[00187] Any international standards (ISO), or manufacturer’s instructions, descriptions, product specifications, and product sheets for any products mentioned herein or in any document incorporated by reference herein, are hereby incorporated herein by reference, and may be employed in the practice of the invention.

[00188] The present invention is not to be limited in scope by any of the specific embodiments described herein. These embodiments are intended for the purpose of exemplification only. Functionally equivalent products, formulations and methods are clearly within the scope of the invention as described herein. [00189] The invention described herein may include one or more ranges of values (e.g. temperature, pressure, et cetera). A range of values will be understood to include all values within the range, including the values defining the range, and values adjacent to the range which lead to the same or substantially the same outcome as the values immediately adjacent to that value which defines the boundary to the range. Throughout this specification, a specified range of values will also be understood to include all possible sub-ranges within the specified range.

[00190] Other definitions for selected terms used herein may be found within the detailed description of the invention and apply throughout. Unless otherwise defined, all other scientific and technical terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the invention belongs.

[00191 ] Throughout this specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims

1. An apparatus for the continuous steam distillation of sandalwood comprising; a distillation vessel for the continuous steam distillation of sandalwood, in which the steam and sandalwood pass through the vessel in a concurrent or counterflow manner; and a means by which the continuous throughput of sandalwood feedstock, comprising the continuous addition of fresh sandalwood feedstock into the distillation vessel and the continuous removal of spent sandalwood feedstock from the distillation vessel, is accomplished without substantially altering the temperature gradient, operating pressure or steam flow rate within the distillation vessel; wherein the means of not substantially altering the temperature gradient, operating pressure or steam flow rate is provided by one or more inlet sub-chambers and one or more outlet sub-chambers, wherein; the one or more inlet sub-chambers are adapted to allow for the external atmospheric conditions to be isolated from the inlet sub-chambers, so that the inlet sub chambers may be purged and/or equalised with the internal temperature and operating pressure conditions of the distillation vessel when the inlet sub chambers are isolated from the external atmospheric conditions and the internal distillation vessel, in order to prevent changes to the internal distillation vessel conditions when the inlet sub-chambers are subsequently opened to the internal distillation vessel to allow for feedstock throughput, thereby maintaining the temperature gradient, operating pressure and steam flow rate inside the distillation vessel; and the one or more outlet sub-chambers are adapted to allow for the internal temperature and operating pressure conditions of the distillation vessel to be isolated from the outlet sub-chambers, so that the outlet sub-chambers may be purged and/or equalised with the external atmospheric conditions when the outlet sub-chambers are isolated from the internal distillation vessel, in order to prevent changes to the internal distillation vessel conditions when the outlet sub- chambers are subsequently opened to the external atmospheric conditions to allow for feedstock throughput, thereby maintaining the temperature gradient, operating pressure and steam flow rate inside the distillation vessel; and wherein the one or more inlet sub-chambers and one or more outlet sub-chambers each comprise two or more control valves, adapted to isolate the sub-chambers from the external atmospheric conditions and/or the internal distillation vessel conditions during purge, equalisation or feedstock throughput stages.

2. The apparatus of any preceding claim wherein internal operating pressure is within the range from 101 kPa to 200 kPa inside the distillation vessel, varying according to the type of sandalwood feedstock and distillation rate required.

3. The apparatus of any preceding claim wherein the internal operating pressure is a pressure within the range 101 kPa to 175 kPa.

4. The apparatus of any preceding claim wherein the internal operating pressure is a pressure within the range 101 kPa to 165 kPa, or within the range 101 kPa to 140 kPa.

5. The apparatus of any preceding claim wherein the internal operating pressure is a pressure within the range 1 15 kPa to 145 kPa, or within the range 120 kPa to 140 kPa.

6. The apparatus of any preceding claim comprising a means by which the continuous movement of sandalwood feedstock through the distillation vessel, is accomplished whilst maintaining substantially isothermal conditions within the distillation vessel.

7. The apparatus of any preceding claim comprising a means by which the continuous movement of sandalwood feedstock through the distillation vessel, is accomplished whilst maintaining substantially isobaric conditions within the distillation vessel.

8. The apparatus of any preceding claim comprising a means by which the continuous movement of sandalwood feedstock through the distillation vessel, is accomplished whilst maintaining substantially homogeneous steam flow conditions within the distillation vessel.

9. The apparatus of any preceding claim wherein the one or more inlet sub-chambers comprise control valves, adapted to isolate the inlet sub-chambers from the internal distillation vessel conditions as fresh feedstock enters the inlet sub-chambers.

10. The apparatus of any preceding claim wherein the one or more inlet sub-chambers comprise control valves, adapted to isolate the inlet sub-chambers from both the external atmospheric conditions and from the internal distillation vessel conditions as the conditions within the isolated inlet sub-chambers containing fresh feedstock are equalised with the internal distillation vessel conditions.

1 1. The apparatus of any preceding claim wherein the one or more inlet sub-chambers comprise control valves, adapted to isolate the inlet sub-chambers from the external atmospheric conditions as fresh feedstock enters the distillation vessel from the inlet sub-chambers.

12. The apparatus of any preceding claim wherein the one or more inlet sub-chambers comprise control valves, adapted to isolate the inlet sub-chambers from the internal distillation vessel conditions as the inlet sub-chambers are purged of the internal distillation vessel conditions subsequent to having dispensed fresh feedstock into the distillation chamber.

13. The apparatus of any preceding claim wherein the one or more outlet sub-chambers comprise control valves, adapted to isolate the outlet sub-chambers from the external atmospheric conditions as spent feedstock exits the distillation vessel and enters the outlet sub-chambers.

14. The apparatus of any preceding claim wherein the one or more outlet sub-chambers comprise control valves, adapted to isolate the outlet sub-chambers from both the internal distillation vessel conditions and from the external atmospheric conditions as the conditions within the isolated outlet sub-chambers containing spent feedstock are equalised with the external atmospheric conditions, prior to disposal of spent feedstock from the outlet sub-chamber.

15. The apparatus of any preceding claim wherein the one or more outlet sub-chambers comprise control valves, adapted to isolate the outlet sub-chambers from the internal distillation vessel conditions as spent feedstock exits the outlet sub-chambers.

16. The apparatus of any preceding claim wherein the one or more outlet sub-chambers comprise control valves, adapted to isolate the outlet sub-chambers from both the internal distillation vessel conditions and from the external atmospheric conditions as the conditions within the isolated outlet sub-chambers containing spent feedstock are equalised with the internal distillation vessel conditions.

17. The apparatus of any preceding claim wherein the addition of fresh sandalwood feedstock to the distillation vessel is assisted by gravity.

18. The apparatus of any preceding claim wherein the addition of fresh sandalwood feedstock to the distillation vessel is assisted by mechanical means, such as but not limited to a conveyor belt or auger.

19. The apparatus of any preceding claim wherein the removal of spent sandalwood feedstock from the distillation vessel is assisted by gravity.

20. The apparatus of any preceding claim wherein the removal of spent sandalwood feedstock from the distillation vessel is assisted by mechanical means, such as but not limited to a conveyor belt or auger.

21. The apparatus of any preceding claim wherein the apparatus comprises a distillation vessel for the continuous steam distillation of sandalwood, in which the steam and sandalwood come into contact with each other in a manner, wherein the sandalwood feedstock passes through the distillation vessel along the longitudinal axis of the distillation vessel, while the steam passes through the distillation vessel in the direction concurrent or counter-current to the feedstock.

22. The apparatus of any preceding claim wherein the distillation vessel comprises one or more thermal boundaries surrounding the distillation vessel, adapted to insulate the interior of the distillation vessel from the external ambient temperature, and/or adapted to thermally regulate the interior of the distillation vessel and isolate it from the external ambient temperature; optionally wherein the one or more thermal boundaries surrounding the distillation vessel, comprise means to circulate heated fluids within the thermal boundary, thereby providing an isothermal barrier in the periphery of the distillation vessel to assist with maintaining thermal conditions within the distillation vessel.

23. The apparatus of any preceding claim comprising an internal mechanical stirrer mixer adapted to eliminate or minimise the development of detrimental steam blow holes and cavities in the feedstock within the distillation vessel, which result in inhomogeneous steam flow through the distillation vessel.

24. The apparatus of any preceding claim wherein steam operating temperatures for the apparatus range from 95.1 °C to 120.2°C or from 98°C to 1 17°C inside the distillation vessel.

25. The apparatus of any preceding claim wherein steam operating temperatures for the apparatus range from 100.2°C to 1 16.5°C inside the distillation vessel.

26. The apparatus of any preceding claim wherein the steam operating temperatures for the apparatus range from 105°C to 1 15°C, or from 105°C to 1 12°C inside the distillation vessel.

27. The apparatus of any preceding claim wherein the throughput of the sandalwood feedstock passing through the distillation vessel occurs at a predetermined rate, such that the sandalwood oil extraction rate is between 0.01 and 15 grams per kilogram of steam per hour, varying according to the type of sandalwood feedstock and distillation rate required.

28. The apparatus of claim 35 wherein the sandalwood oil extraction rate is between 0.01 and 10 grams per kilogram of steam per hour.

29. The apparatus of claim 35 wherein the sandalwood oil extraction rate is between 0.01 and 5 grams per kilogram of steam per hour.

30. The apparatus of any one of claims 25 to 37 wherein the one or more thermal boundaries, in the periphery of the distillation vessel of the apparatus can be controlled to between -5°C to 55°C higher than the internal temperature of the distillation vessel by circulating heated fluids through the one or more thermal boundaries.

31. The apparatus of any preceding claim wherein steam is generated through a standard steam generation device and is regulated to the distillation vessel via a steam supply inlet equipped with a control valve, at the required temperature and operating pressure for the specific type of sandalwood feedstock and for the appropriate extraction rate.

32. The apparatus of any preceding claim comprising a control system, adapted to monitor various physical chemical and temporal parameters of the continuous sandalwood distillation process in real time.

33. The apparatus of any preceding claim comprising a control system, adapted to log various physical chemical and temporal parameters of the continuous sandalwood distillation process in real time.

34. The apparatus of any preceding claim comprising a plurality of parametric feedback sensors, adapted to operably communicate with a control system to provide parametric feedback to the control system regarding various physical, chemical and temporal parameters of the continuous sandalwood distillation process in real time.

35. The apparatus of any preceding claim comprising a plurality of parametric feedback sensors, adapted to operably communicate with a control system to provide parametric feedback to the control system regarding various physical, chemical and temporal parameters of the continuous sandalwood distillation process in real time, wherein the sensors are adapted to provide feedback in relation to one or more parameters selected from but not limited to the group comprising inlet sub-chamber pressure, inlet sub-chamber temperature, distillation vessel temperature, distillation vessel operating pressure, outlet sub-chamber pressure, outlet sub-chamber temperature, rate of addition of fresh sandalwood feedstock, rate of removal of spent sandalwood feedstock, flow rate of sandalwood feedstock through distillation vessel, dwell time of feedstock within distillation vessel, steam supply inlet pressure, steam supply inlet temperature, steam and sandalwood oil outlet pressure, steam and sandalwood oil outlet temperature, flow rate of steam through distillation vessel, mixing rate of mechanical stirrer mixer, temperature of fluids circulating through one or more thermal boundaries, rate of circulation of fluids circulating through one or more thermal boundaries, rate of condensation of sandalwood oil at heat exchanger or condenser, colour of sandalwood oil at collection and separation point, refractive index of sandalwood oil at collection and separation point, alpha and/or beta santalol content of sandalwood oil at collection and separation point and optical rotation of sandalwood oil at collection and separation point.

36. The apparatus of any preceding claim comprising one or more equipment control units, adapted to control one or more mechanically, electrically or physically actuated means within the apparatus.

37. The apparatus of any preceding claim comprising one or more equipment control units, adapted to control one or more mechanically, electrically or physically actuated means within the apparatus, said mechanically, electrically or physically actuated means being selected from, but not limited to, the group comprising; actuation means for inlet sub-chamber control valves, actuation means for outlet sub-chamber control valves, pumping means for circulating heated fluids within one or more thermal boundaries surrounding the distillation vessel, temperature control means for controlling the temperature of heated fluids circulating within one or more thermal boundaries surrounding the distillation vessel, actuation means for pressure control valve at outlet for steam and sandalwood oil, actuation means for control valve at inlet for steam supply, drive means for powered mechanical stirrer mixer and shaft, drive means for mechanically assisted addition of fresh sandalwood feedstock to the distillation vessel, and drive means for mechanically assisted removal of spent sandalwood feedstock from the distillation vessel.

38. The apparatus of any preceding claim comprising a control system, adapted to adjust various physical chemical and temporal parameters of the continuous sandalwood distillation process in real time, by issuing control commands to one or more equipment control units and thereby provide optimal extraction rates and yields for sandalwood oil whilst avoiding temperature and operating pressure extremes detrimental to the sandalwood oil quality.

39. The apparatus of any preceding claim comprising a control system, adapted to log various physical chemical and temporal parameters of the continuous sandalwood distillation process in real time, and thereby produce a database relating the various physical chemical and temporal parameters to the conditions of the continuous sandalwood distillation process, and to the particular qualities of the sandalwood feedstock used, and the resultant yield and quality of the sandalwood oil product produced, wherein the database may be used to optimise future extraction processes involving the same or similar sandalwood feedstock, for optimal yield and quality of sandalwood oil.

40. The apparatus of any preceding claim comprising a control system, adapted to receive parametric feedback from one or more parametric feedback sensors, and based on the information received, adjust various physical chemical and temporal parameters of the continuous sandalwood distillation process in real time, by issuing control commands to one or more equipment control units and thereby provide optimal extraction rates and yields for sandalwood oil whilst avoiding temperature and operating pressure extremes detrimental to the sandalwood oil quality.

41. The apparatus of any preceding claim comprising a control system that may be programmed to provide optimal extraction rates and yield and quality of sandalwood oil from a particular sandalwood feedstock, based on previously logged data in relation to the same or similar sandalwood feedstock.

42. The apparatus of any preceding claim comprising a control system that may be programmed to provide optimal extraction rates and yield and quality of sandalwood oil from a particular sandalwood feedstock, based on previously logged data in relation to the same or similar sandalwood feedstock, wherein the logging of data and the programming of the control system for optimal extraction rates and yield and quality of sandalwood oil from a particular sandalwood feedstock may occur simultaneously so that the continuous distillation process may be continually optimised throughout an entire run of the same or similar sandalwood feedstock.

43. The apparatus of any preceding claim, when used to distil sandalwood oil from a sandalwood feedstock.

44. A process for the production of sandalwood oil, using the apparatus of any one of the preceding claims.

45. The process of claim 44 wherein the spent sandalwood feedstock produced by the continuous sandalwood distillation process is a valuable, high quality by-product.

46. A method for the continuous steam distillation of sandalwood to produce sandalwood oil, characterised in that a particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam at a substantially constant temperature, a substantially constant operating pressure and a substantially constant steam flow rate, wherein the temperature, operating pressure and steam flow rate have been previously optimised for the particular sandalwood feedstock to provide a high sandalwood oil extraction rate and yield whilst avoiding temperature and operating pressure extremes which would cause deterioration of the sandalwood oil quality; wherein the flow of steam is at a substantially constant temperature in the range 95.1 °C to 120.2°C, or in the range 100.2°C to 1 16.5°C, or in the range 98°C to 1 17°C, or in the range 105°C to 1 15°C, or in the range 105°C to 112°C inside the distillation vessel; and wherein the flow of steam is at a substantially constant operating pressure in the range 101 kPa to 200 kPa, or in the range 101 kPa to 175 kPa, or in the range 101 kPa to 165 kPa, or in the range 101 kPa to 140 kPa, or in the range 1 15 kPa to 145 kPa, or in the range 120 kPa to 140 kPa inside the distillation vessel.

47. The method of claim 46 wherein the particular sandalwood feedstock is subjected to a concurrent or counter-current flow of steam such that the sandalwood oil extraction rate is between 0.01 and 15 grams per kilogram of steam per hour, or between 0.01 and 10 grams per kilogram of steam per hour, or between 0.01 and 5 grams per kilogram of steam per hour.

48. The method of any one of claims 46 to 47 wherein the particular sandalwood feedstock is derived from Santalum album.

49. The method of any one of claims 46 to 48 wherein the resultant sandalwood oil product produced by the method exhibits one or more properties selected from the group comprising the following properties;

Density: 0.968 to 0.983 @ 20°C;

Refractive index @ 20°C: 1.503 to 1.509;

Optical rotation @ 20°C : -12 to -21 °;

Solubility in 70% ethanol (v/v) @ 20°C: < 5 volumes of 70% ethanol/volume of oil

Ester number: max 10; or

Total alcohol content, calculated as santalol: 90% minimum.

50. The method of claim 49 wherein the resultant sandalwood oil product conforms to ISO 3518:2002.

51. The method of any one of claims 46 to 47 wherein the particular sandalwood feedstock is derived from Santalum spicatum.

52. The method of any one of claims 46 to 47 wherein the resultant sandalwood oil product produced by the method exhibits one or more properties selected from the group comprising the following properties;

Density: 0.945 to 0.980 @ 20°C;

Refractive index @ 20°C: 1.500 to 1.517;

Optical rotation@ 20°C : -16 to +4^o;

Solubility in 70% ethanol (v/v) @ 20°C: < 5 volumes of 70% ethanol/volume of oil; Acid number: maximum 5.

53. The method of claim 52 wherein the resultant sandalwood oil product conforms to ISO 22769:2009.

54. The method of any one of claims 46 to 53, wherein the method is performed using the apparatus of any one of claims 1 to 43.

55. A method for the continuous steam distillation of sandalwood oil from a sandalwood feedstock containing sandalwood oil, the method comprising the steps of:

Passing the sandalwood feedstock through the distillation vessel;

Adjusting the pressure of the first outlet sub-chamber to atmospheric pressure;

Passing the sandalwood oil-enriched steam at atmospheric pressure from the first outlet sub-chamber to a heat exchanger or condenser;

Separating the mixture of sandalwood oil and water;

Collecting the separated sandalwood oil;

Collecting the sandalwood oil-depleted spent sandalwood feedstock by-product from the second outlet sub-chamber; wherein the method steps are performed in a continuous manner.

56. The method of claim 55 wherein the predetermined temperature is a temperature within the range 95.1 °C to 120.2°C, or within the range 100.2°C to 1 16.5°C, or within the range 105°C to 115°C, or within the range 98°C to 1 17°C, or within the range 105°C to 112°C.

57. The method of any one of claims 55 to 56 wherein the predetermined operating pressure is a pressure within the range 101 kPa to 200 kPa, or within the range 101 kPa to 175 kPa, or within the range 101 kPa to 165 kPa, or within the range 101 kPa to 140 kPa, or within the range 115 kPa to 145 kPa, or within the range 120 kPa to 140 kPa.

58. The method of any one of claims 55 to 57 wherein the step of passing the sandalwood feedstock through the distillation vessel comprises passing the sandalwood feedstock through the distillation vessel at a predetermined rate, such that the sandalwood oil extraction rate is between 0.01 and 15 grams per kilogram of steam per hour, or between 0.01 and 5 grams per kilogram of steam per hour, or between 0.01 and 5 grams per kilogram of steam per hour.

59. The method of any one of claims 55 to 58 wherein the sandalwood feedstock is derived from Santalum album.

60. The method of any one of claims 55 to 59 wherein the resultant sandalwood oil product produced by the method exhibits one or more properties selected from the group comprising the following properties;

Density: 0.968 to 0.983 @ 20°C;

Refractive index @ 20°C: 1.503 to 1.509;

Optical rotation @ 20°C : -12 to -21 °;

Ester number: max 10; or

Total alcohol content, calculated as santalol: 90% minimum.

61. The method of claim 60 wherein the resultant sandalwood oil product conforms to ISO 3518:2002.

62. The method of any one of claims 55 to 58 wherein the particular sandalwood feedstock is derived from Santalum spicatum.

63. The method of any one of claims 55 to 58 or claim 62 wherein the resultant sandalwood oil product produced by the method exhibits one or more properties selected from the group comprising the following properties;

Density: 0.945 to 0.980 @ 20°C;

Refractive index @ 20°C: 1.500 to 1.517;

Optical rotation@ 20°C : -16 to +4^o;

Acid number: maximum 5.

64. The method of claim 63 wherein the resultant sandalwood oil product conforms to ISO 22769:2009.

65. The method of any one of claims 55 to 64, wherein the resultant sandalwood oil product conforms to an odour profile, determined by the buyer.

66. The method of any one of claims 55 to 65, wherein the method is performed using the apparatus of any one of claims 1 to 43.

67. The apparatus of any one of claims 1 to 43, when used to perform the method of any one of claims 55 to 66.