FR2485942A1 - COUNTERCURRENT EXTRACTOR AND PROCESS FOR EXTRACTING SOLUBLE OR DISPERSIBLE MATERIALS - Google Patents

Abstract

THE INVENTION RELATES TO A COUNTER-CURRENT EXTRACTOR INCLUDING AN EXTENDED HOUSING IN THE FORM OF A TROUGH OR A TUBE AND HAVING AN ENTRY AT ONE END AND AN EXIT AT THE OTHER, A SCREW CONVEYOR PROVIDED IN THE HOUSING AND ROTATING AROUND ITS LONGITUDINAL AXIS TO MOVE MATERIAL INTRODUCED IN THE HOUSING FROM ITS FIRST END TO THE OTHER, A MEANS OF INTRODUCING AN EXTRACTION LIQUID TO THE OTHER END OF THE HOUSING AND FORCING IT TO FLOW ALONG THE HOUSING UNTIL ITS FIRST END, AND A MEANS OF DRIVING TO FORCE THE CONVEYOR TO TURN. ACCORDING TO THE INVENTION, THE DRIVE MEANS 13 IS SUCH THAT THE DIRECTION OF ROTATION OF THE SCREW CONVEYOR 12 IS INTERMITTENTLY REVERSE. THE INVENTION APPLIES IN PARTICULAR TO THE PROCESSING OF FOOD PRODUCTS.

Description

The present invention relates to an improved extractor against

  current o is incorporated a screw conveyor as well as an improved process for the countercurrent extraction of a substrate, soluble or dispersible materials, using such an extractor. Countercurrent extractors are well known

  in the food processing industry for the extrac-

  continuous flow of liquids, solids and fine particulates from the associated solids. Such diffusers generally comprise two counter-rotating parallel screw conveyors which are mounted in an elongate and vertical or inclined housing, which is in the form of a trough or a totally closed tube. The material to be treated, such as chopped sugar beet, is brought to the lower end of the housing and is entrained upward by the rotation of the screw while an extraction liquid (usually water) is brought at the top of the housing and flows down under the effect of gravity. Single-screw countercurrent extractors are also known, but are known to be relatively ineffective because the solid tends to accumulate on one side of the housing while the liquor tends to flow, relatively without obstruction, down, on the other side. A similar problem can be encountered with double screws, but to a lesser extent, because the counter-rotation encourages a more even distribution of solids on

the entire width of the screws.

  Single screw conveyors offer the significant advantages of simplicity and low cost compared to twin screw extractors, and attempts have been made to improve the efficiency of such single screw extractors. The present inventors have found, surprisingly, that the operating efficiency of the countercurrent extractors could be substantially improved by the relatively simple means of intermittently reversing the direction of rotation of the screw conveyor. Inversion of the rotational direction of the screw conveyor forces the relatively compacted mass of material that is extracted to open to allow

  to the extraction liquid dty penetrate. The extractive liquid

  The mass is thus expressed when the screw conveyor returns to its original direction of rotation, carrying with it the dissolved and dispersed material

to be extracted.

  The present invention relates to an extractor against

  a current which comprises an elongated housing in the form of a trough or tube and having an inlet at or near one end and an outlet at or near the other end, a conveyor screw disposed in the housing and rotatable about its longitudinal axis to move a material introduced into the housing from its first end to its other end, a means for introducing an extraction liquid into the other end of the housing and to force it to flow along the housing to the first end, and drive means to force the screw conveyor to rotate, and according to the invention, the drive means is such that the direction of screw conveyor rotation

is reversed intermittently.

  According to another aspect, the present invention relates to the improvement of a process for extracting soluble or dispersible materials from a substrate, in a countercurrent extractor which consists in reversing the direction of rotation of a conveyor to screw in the extractor, intermittently. While the present invention will be described hereinafter with reference to countercurrent extractors using a single screw conveyor, it will be appreciated that the present invention may be used with countercurrent extractors having a number of conveyors.

  to screw. In addition, a further description will be

  limited to the use of screw diffusers for extracting components of plant material and the like, while in the practice of diffusers can be used for what can be described as the inverse of extraction, that is, for the impregnation of a solid material by means of a liquor, and such an application is also considered to be part of

of the scope of the invention.

  In a particularly preferred embodiment of the invention, the end of the flight of the screw conveyor which is not active to move the material towards the other end of the housing, is provided with a number of ribs arranged substantially radially at spaced locations along the length of the screw conveyor. These ribs serve to engage the substantially packed mass of solid substrate material in the extractor and assist in breaking it to allow free percolation of the extraction liquid into the mass of the solid material. If desired, such ribs may also be provided on the fly surface which serves to move the solid material from the first end to the other end of the fly.

housing.

  It is preferred that filter means be provided for filtering the extracted liquid prior to removal from the first end of the housing. The filtering means preferably includes a plate that extends

  transversely through the housing at its first

  or near it, and through which protrudes a shaft leading from the screw conveyor. The plate is provided with at least one opening through which the extraction liquid can pass and a filter disc is provided in close juxtaposition with the plate on its distal side with respect to the other end of the housing, and is arranged to rotate with the drive shaft of the screw conveyor beyond this opening or openings in the plate and

therefore self-clean.

  Means are preferably provided for recycling the extraction liquid from the first end of the housing, heating it to a desired desired temperature, and the oil. return to the dwelling at a point in time, and at the other end of the dwelling, the exhausted liquida of extraction to the point of departure.

  of the accommodation and the use of a room by a staff member

  of independent heat o. They will be shifted and circulated to the dwelling on the third floor of the first day of the first day of the eighth century. is to get one. hot-air heating of the sea and the sea

  early treatment, the liquor is

  It should be understood that the frequency of the error is greater than or equal to about 1/4 of the value of the logger at one end. In another refinement the eqtractor is It also provides a means for securing a predetermined level of the extraction liquid in the housing's inner rulers, since it has been found that the contact $ olide / liquid

  was favored if the extraction system could

  to a controlled extent-at preo of the loading point of the solids. An appropriate means of control will detect, for example, the level of the island and compensate for changes in the flow rate to the outside and / or the intake of the extraction liquid. The extractor is preferably provided with a jacket through which fluid can pass, in this way the temperature of the housing, and to a certain extent the temperature of its contents, can be controlled. The extractor may comprise any suitable reversible drive. It is preferred that the drive means comprise an electric motor or a hydraulic motor which is reversible. In another embodiment, a reverse gear boot may be interposed between the motor and the drive. aiming conveyor In the same way as with diffusers that work

  with a continuous advance movement of the screw, the perfor-

  The basis of the diffusers operating according to the principles described above will be influenced by many factors, such as the nature of the charge, its temperature, the liquor flow, the inclination of the screw, the rotational speed of the screw and the helix angle of the screw, and the individual operators will vary these factors to meet the particular conditions. Nevertheless, the present invention has another feature which is the recognition that, for maximum efficiency, there is an optimal relationship between the time when the screw (s) operate forward and the reverse operation time. In general, preferably the net advance operating time of the screw should not exceed about 75% and better it should not exceed about 50%

  and even better it should not exceed about 25%.

  In this description, the net time in advance

is defined by: TF - TR x 100

TF + TR

  o TF = total running time of the screw with a feedrate TR = total running time of the screw with

a reverse movement.

  It will be found that the yield of the recovered SS will increase with the decrease of the net time in advance, but it is clear that there will be a decrease

  concomitant flow rate to be taken into consideration

  when determining the optimum conditions

  from the economic point of view.

  The. liquid. Extraction will frequently be water

  although other liquids including organic liquids

  organic aqueous solutions or solutions may be used. The process can be used for the extraction of soluble or dispersible materials from fruits or vegetable matter such as sugar beet, sweet sorghum, grapes, grape marc, tea, lemon, lemon zest, apples, pears and animal materials such as fish heads and fish of inferior quality. Residues such as apple peels, apple peels, lemon peels and grape pomace can also be exhaustively extracted to recover valuable ingredients.

  soluble which are normally evacuated with these residues.

  Soluble sugars recovered from peel or apple peels and cores can be used for

  preparation of syrups in boxes or fermented in alcohol.

  Other residues contain materials such as flavoring colors or specific useful materials such as pectins that can be recovered. For a satisfactory extraction, it is preferable that the materials are in particulate form, the shape of the particles being such that the diffusion path for the migration of the soluble material out of the particles is short.

at least in one direction.

  The material of the extracted substrate is evacuated from the housing through the outlet at the other end of this housing. The outlet is preferably disposed in a side wall of the housing above the level of the screw conveyor. An evacuation conveyor is preferably provided to move the extracted substrate material laterally and upwardly from the base of the housing, to the outlet. In a particularly preferred embodiment of the invention, the evacuation conveyor passes, at its lower end around a pulley which is journalled on an extension of the shaft extending longitudinally of the screw conveyor, a motor means being designed to drive the evacuation conveyor independently of the

screw conveyor.

  The invention will be better understood and other purposes, features, details and advantages thereof

  will become clearer during the description

  explanatory text which will follow with reference to the accompanying schematic drawings given solely by way of example illustrating an embodiment of the invention and in which:

  FIG. 1 is a schematic diagram of an extractor against

  248594i current according to the present invention; FIG. 2 is a semi-diagrammatic and plan view of a countercurrent extractor according to the invention; - Figure 3 is a cross-sectional view of the housing, taken along the line III-111 of Figure 2; - Figure 4 is a longitudinal sectional view of the lower end of the housing and the screw extractor of Figure 2; FIG. 5 is a graph showing the effect of the intermittent inversion of the direction of rotation of the screw conveyor of a countercurrent extractor according to the invention, the time in minutes being indicated on the abscissa axis; and the flow in ml / min as well as the evacuation B on the ordinate axis, a indicating continuous and b indicating contrearotation added, - Figure 6 is a graph comparing the liquid levels in the housing of an extractor counter-current during continuous rotation in one direction and during an intermittent inversion, the dashed curve indicating the continuous rotation and the solid line indicating the opposite rotation, the distance along the screw being indicated on the x-axis with the entry of the solids at 0 cm and the exit at 120 cm, and the depth of the liquid in the aigeindicated on the y-axis; FIG. 7 is a graph showing the improved contact efficiency of a countercurrent extractor according to the invention, the time being indicated on the abscissa axis and the outlet of the juice on the ordinate axis; dashed curve indicating continuous rotation and the solid line indicating rotation

reversed; -

  FIG. 8 is a graph showing the influence of the time of a reverse rotation to the direct screw conveyor on the recovered yield of soluble solids,

  the y-axis, using a counter-puller

  current according to the invention; and FIG. 9 shows. ## EQU1 ##

  made along line IX-IX of FIG.

  As can be seen in FIG. 1, 1 exb L-, countercurrent 10 comprises an elongated extension member which is arranged in a conveyor belt. ies 2 qa is arranged for 'our a-'our longitudinal axis by a means dvenctea ment 13. The housing is p dtune

  inlet hopper 14 for l: itroduotion of matariau ..

  extract. The hopper 14 is placed on top of the bottom of the board, which is attached to the top and to the bottom of the board. This is a 15 year old stable that has been erected. Drainage line 1, st preVue for? the vacuatitOn of the Eizt raoti n e_t,. t

  introduced in the i gema, it is in line with this line 17.

  A heat exchanger 18 is pre-empted on the

  pass 19, to heat the liquid & tvacué and the ramenier by a pipe 21 to the rmisé lower the logemernt

  11 to heat the material that is being treated.

  An inverter means 22 is pre between the drive means 13 and the riser conveyor 12 to reverse

  intermittently the direction of rotation of the conveyor 12.

  FIGS. 2 and 4 show an extrac- tional pattern that is similar to that of FIG. 1 and the same references are used to identify

analogous parts.

  The extractor 10 comprises the trough-shaped housing 11 which is arranged in a rotatable conveyor 12.

  around its longitudinal axis in housing 11.

  A motor 13 is adapted to drive the wis conveyor 12 and includes an inverting means 22 for intermittently reversing the direction of rotation of the screw. The motor 13 is operative and connected to. laxe 23 of the con. 12 with two aligned sun gear wheels 24 and 25 and a chain 26, the gear ratio of the sprockets 24 and 25 being chosen so that the screws 23 and 12 are turned to about 1 ton. mn when the motor 13 operates at an appropriate speed. The axis 23 is supported in bearings 27 and 28 which are mounted at each

end of housing 11.

  The screw conveyor 12 comprises a helical flight 29 which is disposed about the axis 3. The flight 29 is provided with circumferentially directed slits 30 and a number of radially extending ribs 31 which are disposed on the side of the stolen 29 which is not active to move the material to be extracted from the entrance

at the exit of housing 11.

  The material to be extracted is introduced into the housing 11 through the inlet hopper 14. The extracted material is

  evacuated through the exit opening 15. An evacuation conveyor

  50 comprising two continuous chains 51 carrying slats 52 is provided to transfer the material extracted from the bottom of the housing 11 by a side wall 53 thereof to the outlet opening 15. The chains

  51 are supported by three groups of toothed pulleys.

  A group 54 is journalled on the conveyor shaft 2: 3

  to screw 12 and is free to turn relative to him.

  The other two groups 55 and 56 are journalled on shafts parallel to the shaft 23. An electric motor 57 is incorporated in a speed adjusting means,

  designed to drive the pulleys 55 by a belt 58.

  In this way, the material can be evacuated at a constant pace regardless of the pace or direction of

rotation of the shaft 23.

  At the lower end of the housing 11 is a filter for filtering the extracted liquid before it is discharged from the housing 11. The filter comprises an end plate 34 which is provided with openings 35. A screw 36 and a support plate 37 are provided. behind the end plate 34 and they are connected to the axis 23 to rotate with it. The extracted and filtered liquid is discharged through the evacuation line 16 to the heat exchanger 18 where it passes through the exchanger plates 38 where it flows countercurrently with the water. feeding in the line 17, and then it passes through the plates 39 d heat exchanger o it flows against the current with the cooling water in the line 41. The product

  cooled is removed from the extractor via line 16.

  Part of the juice extracted in the line 16 is diverted towards the line 19, passing through the plate 42 of heat exchanger, where this part is heated by a countercurrent passage with the hot water of the line 43, and is then removed polur be brought back to the housing 11 to heat the frankly introduced material to be extracted. Line 19 with heated recycled liquid discharges into housing 11 at a distance

  between one-tenth and one-quarter of the length of this dwelling 11.

  The feed water line 17, after passing through the heat exchanger plate 38, passes into the heat exchanger plate 44 where it flows countercurrently with the hot water in the line 45. The line 17 unloads

  in the housing 11 at its upper end.

  The housing 11 is provided with an insulated hot water jacket 46. The hot water passes into the jacket by the

  lines 47 and exit by lines 48.

  In use, the material to be extracted is introduced at the lower end of the housing 11 and the screw conveyor 12 rotates to begin the movement of the material along the housing 11. Heated feedwater is fed into the housing 11 by line 17 and this feed water, with the juice flowing freely from the material, and the extracted substances as well as the particulate matter, passes through the filter for recycling through the exchanger plate 42 in order to be

  brought back to dwelling 11 by line 19.

  While the material to be extracted progresses along the housing 11, it is compressed by the fly 29 to form

  a packed mass of partially extracted material.

  When the direction of rotation of the screw conveyor 12 is reversed, the ribs 13 bite into the packed mass to force it to open and admit fresh water

  Power. When the conveyor 12 returns to its direction

  248594k original rotation, the material that is extracted is recompressed and the feed water, with extracted material, is expressed This opening of the packed mass of the material that is extracted contributes significantly to the performance of the extractor and gives better

yields of extracted material.

  The results obtained are shown graphically in Figure 5 where they were obtained using a single-screw diffuser (length, 2 m, diameter: 20 Oem, helix angle: 15, tilt: 3.5). Initially, being loaded with sliced apples, the screw was entralée

  continuously forward at a speed of 1 rpm.

  When a state of equilibrium was reached (and ended by the analysis of the liquor of tevaucation), the screw was operated for a certain time during which the direct feed was stopped every 15 seconds and the screw was reversed on 1/20 of revolution. Finally, the screw could again operate in continuous mode in advance. It can be seen in FIG. 5 that immediately upon the resumption of the inversion action, there is an increase in the liquor discharge rate, indicating an opening of the mass of the apple to give a drainage of the liquid of this mass at the top of the screw. then

  from a return to a continuous and uniform rotation, the

  the liquor ceases during a period such that the extraction water can not flow freely

  Pommem mass is maintained in the tissue. THE INCREASE

  significant concentration of sugar (Brix) concentration of the waste liquor during the rotation period

  against the current will also be noted.

  The data presented in FIGS. 6 to 8 were obtained using similar equipment but automatically controlling the movement of the screw so that the counter-current rotation periods consist of a 100-second sequence of direct feed alternating with seconds. reverse advance. Sliced apples were brought into the 325 g batch extractor every 2 weeks.

  five minutes and water (65 C) was fed. e.

  7793 g / min at the top end of laio visi ...

  Mass flow and concentrations of liquor and soot were determined in this way. In this case, it was felt that the sound of the sound of the sound of the film was too great. The film was reworked on the same day. -a9si sz m, which they have been grouped with. $ Figure 6 is the first one for the ltquerr t.) the eld ame e with a movement VLverse ap The effect of solid / liquid oil has been shown to be that the concentrations of soluble solids, measured in Bx, were higher with a higher oxygen content. n ° 4o applied to the screw (Figure 7), and the solubility of the solubes of the variaton of the ratio aqv7e / inverses of the aoment the screw was eherc, é ena o d. ra! si of Shiraze and the results are given in the following examples. donated

below.

2 ffle 7.

  The effect. The Gordo grapes, which are difficult to grind because of their slippery nature, were taken at the end of a grapple drip tray and fed at a rate of 600 kg / hl. through the extrusion with 4m5 m screw diameters of 0O5 m co The production of the extractor and a traditional grappie auger are included in the table which follows 9'19 9 '0

7c '81

0I '01I

96'0 / 1'6 ?, sapTios

UO T% 6nov ..

  09'81 '0 & q6'68 UO766umTV UOTI.eBI.UeZTIy i.ueJnoo-ail.uoo q Jnnelouzixa ç' 0 ç1'9Z 9ú'ú1 06'ú1

OZ 'G1

56'65 G '1, l

 O'O 9 Z

  septus UOTUnouBA UOTU%. u oTladduis op Te q aTuszi sePTToS sap 99UTeip SUTS-TJ ep selqnTos uoTq.eEdno.z% seTqnT -osuT / selqnlos SOPTIOS%, JodduH% selqnTosuT S PTTOg% sT.qnTos

9SPTTOS

  In another test, 4250 kg of Shiraz grapes were extracted, and the recovery of soluble desolders was 82%. Mass are

indicated in the table below.

  _5 Component Feed = Evacuation Juice Solid Solids Solids% 25,9 14,2 20,0 Quantity, kg 4250 1290 4,500 Total

solid solids

pounds, kg 1100 183 900

Example XI.

  The traditional process for the preparation of

  Lime juice in the West Indies takes about 30 days.

  However, by using the countercurrent extraction process to extract the fruit in slices, the time for lime juice production can be reduced to one and a half hours In one case, lime juice production was equal to weight of files brought. This "juice" gives an excellent drink when it is diluted with 4 volumes of water and an appropriate amount of sugar is added

for the balance of perfumes.

Example III.

  Using a process similar to that of limes, kg of citrow produced a "juice" which, when supplemented to obtain 400 kg, by adding water and

  30. 32 kg of sugar, gave an excellent lemon drink.

2485-i

Claims (11)

CLAIMS V E N D I C A T IO N S   1. A countercurrent extractor of the type comprising an elongate housing in the form of a trough or tube and having an urn-end or proximal inlet thereof and an outlet at the other end or at a pressure-free end. imitated thereof, a screw conveyor disposed i said said element and rotatable about its longitudinal axis to move a material introduced into said housing fromo the first end to the other end, u yen pa introduce a extraction fluid at the other end of said housing and forcing it to flow from said housing to said first end, and driving means for forcing said screw conveyor to rotate, characterized in that said driving means (13) is such that the direction of rotation of said screw conveyor   (12) is reversed intermittently.   2. Extractor according to claim 1, characterized in that the side of the screw conveyor which is not active to move the aforementioned material to the other end of the aforementioned housing is provided with a number of ribs (31) arranged substantially radially and at locations spaced along the length of said screw conveyor.   3. Extractor according to any one of the claims   1 or 2, characterized in that filter means (34 ', 35) are provided for filtering the extracted liquid prior to its removal from the first end of said housing. 4. Extractor according to claim 3, characterized in that the aforesaid filtering means comprise a closure means (34) with opening, which passes through the aforementioned housing at its first end or close thereto, and by o protruding a drive shaft (23) for the aforesaid screw conveyor, a filter member being provided in close juxtaposition with the opening or the apertures 7; _ open circuit, of this w7en do farneture su z es :: t, -T   distal -ar to the other o: rt-it & dzidIt lIv = n. -   arranged to rotate between 1 and 2 minutes.   or openings so that the orgy do Lfiis be self-cleaning   5. Extractor according to any of the rerLadica-   Previously, the means (19) are provided for a portion of the extraction liquid from the first m3it of the aforesaid housing, the heating of which is predefined and the control of said housing in accordance with the present invention. 7 Doiat, nts'e l Uxtr 4 = Mited 6. The sintering extractor 5 has been characterized in that the recycled liquid precipitates and extends to the aforesaid housing at a point where it is a v-ingtime and an art of the length of said lo3emet from its first end,   7. Extractor according to some of the claims   previous requirements: means shall be provided to provide a level of extraction liquid at the above-mentioned level (referred to above) as the aforesaid extract-1r fonrione   8. Extracurring the number of claims   Previously, careato-6 & re re quire The exhaust duct (50) is provided with the above-mentioned housing, to move the material through the wall (53) of the housing up to the exit. 9. Extract according to claim 8, characterized in that the aforementioned evacuation conveyor is filleted on a pulley (54) tourillo 9e to the shaft of said conveyor to screw.   10. Process for exractio: zaatei; olub!   dispersible from a substrate in a co-trench extractor   characterized in that the direction of rotation of said conveyor in the axle is intermittently reduced. 11. Method according to claim 10, characterized in that the direction of rotation of the aforementioned conveyor is reversed intermittently so that the net time of advance does not exceed 75% and preferably does not exceed 50%.