Apparatus for the steam extraction of essential oils from vegetable material

An extraction enclosure is connected by a pipe in its upper region to a source of steam. A drawer having a grill base for containing vegetable materials to be extracted permits the introduction of vegetable materials into the extraction enclosure. The base of this latter enclosure communicates with a subjacent refrigerated or cooling enclosure, provided with discharge means. There is thus avoided or minimized risk of overheating and/or of the hydrolysis of the essential oil in the course of extraction and there is eliminated or minimized all obstacles of flux of vapors and of liquid at the refrigerant level. The charging and discharging of the extraction enclosure are also simplified.

The present invention relates to a process and apparatus for the steam 
extraction of essential oil from vegetable material. 
The usual known process consists in directing steam through the material 
from the bottom to the top and subsequently condensing the mixture of 
steam and oil emitted above the vegetable material in a refrigerant. 
This process has the disadvantage of giving rise to condensation of water 
in the vegetable material with localized squeezing or consolidation of 
this matter, creation of steam channels in other areas and hydrolysis 
affecting the quality of the essential oil. 
According to the present invention there is provided a process for steam 
extraction of the essential oil from a vegetable material, characterized 
in that in an extraction enclosure steam is directed over the said 
material from the top to the bottom and wherein the extraction enclosure 
is in communication with a refrigerated or cooling enclosure provided 
below the extracting enclosure, and in that the condensate formed of 
essential oil and water is recovered at the bottom of the said 
refrigerated or cooling enclosure. 
Conventional known installations for steam extraction of vegetable essences 
comprise stills having swannecks which are connected to a refrigeration 
device. The vegetable materials to be treated are generally introduced 
from the top and disposed on a grill provided inside this apparatus. 
Alternatively, the materials can be disposed in a basket which is 
suspended inside the still. After closure of the apparatus steam is 
injected under pressure below the grill or the base of the basket. After 
condensation in the refrigeration device, the mixture of water and 
essential oil is recovered in a decanting recipient separating the 
essential oil from the water. 
These known installations present, in addition to the disadvantages 
mentioned above, the risk of damaging the vegetable material by 
overheating during the pressure of steam from the bottom to the top in the 
still. After exhaustion of the vegetable material, it is necessary to open 
the apparatus to withdraw the material which results in losses in time and 
in heat. 
Also according to the present invention there is provided an apparatus for 
extracting oil from vegetable matter comprising passing steam from top to 
bottom over said material in an enclosure and subsequently condensing oil 
and water therebelow and recovering such comprising an extraction 
enclosure connected to a source of steam and to a refrigerated or cooling 
enclosure, characterized in that steam inlet means is provided at the top 
of the extraction enclosure and the extraction enclosure is in 
communication in its base region with the refrigerated or cooling 
enclosure.

The apparatus represented in the drawing comprises a parallelepipedical 
enclosure 1 divided into two superposed compartments 2, 3, communicating 
one with the other. The upper compartment 2 has an opening 4 in one of its 
vertical walls by means of which there may be introduced a drawer 5, 
loaded with vegetable material from which it is desired to extract the 
essential oils. The drawer 5 is mounted on rollers 6 which have a support 
14 adjacent the compartment 2 of the enclosure 1. The base of the drawer 5 
is constituted by a grill 7 and the drawer 5 also has an edge 8 along its 
upper edge permitting its engagement by the rollers 9 when it is 
introduced into the compartment 2 of the enclosure 1. 
Steam under pressure is introduced into the top of the compartment 2 
through a tube 10 and traverses from top to bottom the vegetable material 
contained in the drawer 5. A distributor 11 formed by perforated tubes 
connected directly or indirectly on the tube 10 extends at a right angle 
with respect to the tube 10 and is provided with perforations orientated 
towards the base of the compartment 2, thus ensuring an equal distribution 
of steam over the vegetable material contained in the drawer 5. 
The mixture of steam and essential oil extracted from the vegetable 
material subsequently passes through the grill 7 constituting the base of 
the drawer 5 and into the compartment 3 of the enclosure 1. This 
compartment 3 is traversed by tubes 12 connected to a source of cold 
water, adapted to condense the mixture of steam and essential oil. The 
condensate is recovered at the base of the refrigerated or cooled 
compartment 3 in a discharge means 13 and the essential oil can be 
separated from the water, in a manner known per se. 
The refrigerating or cooling tubes 12 are preferably of polygonyl 
cross-section--especially of square or hexagonal cross-section--so as to 
present maximum surface contact to the steam charged with essence to be 
condensed. 
The grill 7 constituting the base of the drawer 5 is preferably pivoted 
along the lower edge of one of its vertical walls, so as to be able to be 
lowered when the carriage is withdrawn from the enclosure in a manner to 
accelerate the discharge of the exhausted or used up vegetable material. 
Preferably, the base of the refrigerated compartment 3 is inclined and 
communicates with the discharge means 13 located at the base and extending 
substantially over the whole of the width of one of its walls in a manner 
to avoid or minimize all obstacles, throttling or eddies in the flux of 
the condensate at the outlet of the refrigerated compartment. The 
condensate of essential oil and water is recovered in a gutter (not shown) 
and directed towards a decanting device. 
Amongst the particular advantages of the apparatus described, it is to be 
noted the elimination of the throttling during the passage of vapours and 
liquid from the extraction enclosure into the refrigerated or cooling 
enclosure and of this latter towards the collector adapted to direct the 
condensate towards the decanting device. There results a notable 
acceleration in the extraction process of essential oil. Also the risk of 
hydrolysis of this latter is substantially reduced, resulting in an 
improvement in the quality of the essential oil produced. 
In the case where the vegetable material to be extracted comprises fine 
particles such as pollen or other pulverulent material, the grill 7 can be 
covered with fibres or a cloth for retaining fine material.