This invention relates to an equipment for contacting a coarse solid material, e.g. grist, granulate and the like with a liquid, particularly for extracting a solid with a liquid.

Various solvings (solutions) are known for the extraction of a solid with a liquid. Worldwide are used e.g. the so-called bulk flow (conveyor) system apparatus, the prin¬ ciple of which comprises conveying (transpor¬ ting) the solid by the means of .perforated or grated trays mounted to an endless con¬ veying element, mainly drag chain, in the cells between two neighbouring trays each; thus, the trays let pass the extraction liquid through. The extraction liquid passes countercurrently through the solid being present in the cells while moving (agitating) it. In the bulk flow (conveyor) systems of such type the motion of the solid is simple and no separate pump is necessary for flowing of the countercurrent liquid since the driving force therefor is supplied by the field of gravity. Thus, they are safe and have advantageous working (operation) properties where they can be used", their severe drawback consists therein, however, that any of the cells can be saturated because of either the agglutination of the

grist or granulate, or the axial mixing- -back, washing-back of the solid, whereby a "plug" hampering the flowing-through of the liquid can develop at these sites, which results in the break (interruppion) of the extraction process.

A bulk flow (conveyor) system equip¬ ment is described e.g. in the Unites States patent specification No. 3.279,890. This apparatus has a casing with an U-shaped tube; the upper ends of the vertical shanks of this tube are led to a chamber. One shank of the U-shaped tube down to about its lower third, the other shank up to its upper third are formed (built) with a double wall and a heat-transfer medium can be flown in the space between the two walls. The perforated disks mounted equidistantly one from another on the endless chain pass unidirectionally (e.g. in a counter-clockwise direction) at an uniform rate in the casing. The driving- -turning (conveying) mechanism bearing the wheels is placed in the upper chamber men¬ tioned above. A screw feeder is led into the U-shaped casing at the upper end of one of the shanks (where this shank is not duplicate and about the lower third of this shank has a double wall).

The screw continuously feeds the solid granular material, e.g. plant grist to be extracted into the cells between the neigh¬ bouring disks (trays). The extraction liquid

is fed into the upper part of the other shank of the casing and, while passing coun- tercurrently to the solid, it extracts the active agent content thereof. For removing the extract, a filter chamber built in beneath the site of feeding in the solid is provided, which is bounded by a filter mantle containing small-sized holes (of 1 mm or smaller). The disks transporting (conveying) the solid are fastened to the drag chain in their central region, i.e. centrally and fitted with roll pairs joining the outer wall poss¬ essing a greater radius) of the casing (tube). The perforations of the disks are relatively great, 10 to 30 times larger than that of the particle size of the plant grist. In order to safely convey the disks, both the rolls and disks are fitted with a cleaning device. A vibrator moving the extraction liquid is built into the lower section of the U-shaped casing (which connects the vertical shanks) in order to fill with the solid most completely (up to about 805ό) the working volume of the cells bounded by the disks (trays), i.e. to increase the performance (output) of the extraction equip¬ ment. The vibrator works at a frequency of 50-200/s; an amplitude of 0.05-0.15 mm corresponds to this frequency range in the casing.

In order to move the disks (trays) conveying the solid in the casing containing

curved sections beneath, the diameter of these disks should be smaller than that of the inner diameter of the tube therefore, a radial slit should be present between the edge of the disk and the wall of the casing; this slit is 15 mm in size when the inner diameter of casing is e.g. 300 mm. Since the disks are centrally fastened to the drag chain, they move radially inwards from the wall of casing in the lower, curved sections of the casing in spite of the roller support, whereby the value of slit size is lowest along the inner curve (of smaller radius) and highest along the outer curve (of longer radius). For the safe moving of the solid-conveying disks relatively great slit sizes are required; these slit dimensions and the liquid-transmitting orifices of the conveying disks determine the possibility of extracting a solid (gra¬ nular, ground, particulate, crushed solid and the like) in a bulk flow (conveyor) apparatus without causing any axial mixing- -back, which could result in the development of a "plug" accompanied by stopping of the extraction process in some cells. Thus, e.g. the equipment described in the United States patent specification No. 3,279,890 discussed above has been developed for the extraction of a crushed plant grist, sub¬ stantially periwinkle, containing no or only a very low percentage of powder par-

tides the characteristic size of the par¬ ticle aggregation is several millimeters, the aggregation is leaf-like in its character and contains dry particles, too. When it is tried to extract a grist . aggregation with a liquid, the powder content (particles of 0.1-0.2 mm in size) of which exceeds about 5% and/or its fat content (e.g. ergot, dried-crushed animal organs and the like) is high or the solid is not in a dry state (e.g. marrow), the axial mixing-back may be significant and therefore, as well as because of agglutination of the particles, a plug could eventually and unexpectedly develop in some cells. Thus, the extractor described in the United States patent spec¬ ification No. 3,279,890 is unsuitable to extract such materials, i.e. the field (area) of its utilization is rather restricted. Its further disadvantage appears therein that as a consequence of the central fixation to the drag chain of the conveying trays as well as the forked wheels of the conveying mechanism, the cleaning of the trays (per¬ forated disks) is difficult, the structure of the cleaning devices (purifiers) is com¬ plicated and their failure (breakdown) may cause severe operation (working) disturbances. The OLIER type countercurrent, con¬ tinuously operating solid/liquid extractor also belongs to the bulk flow system equip¬ ments. This extractor contains a casing

with several successive U-shaped sections passing into one another. Also here, the solid is conveyed by conveying disks (trays) fastened tc chains and fitted with a filter surface. The height of the U-shaped casing sections increases in the direction of pas¬ sage of the solid. In order to increase the performance of extraction, no vibrator is used .for this solving; it is tried to ensure the extraction performance desired by in¬ creasing the path length, i.e. the residence time. This extractor also has the drawback that the range of its utilization is very restricted (it can be used only for the extraction of poppy-head grist and other grists of this sort, so-called grits) and, on the other hand, its cleaning is even more complicated than that described in the solving published in the United States patent . spe¬ cification No. 3,279,890 since a lower drive (by forked wheels) is also used in the OLIER extractors.

The present invention is aimed to de¬ velop a continuously operating, bulk flow type countercurrent solid/liquid extractor where, while maintaining the advantages arising from the simple movement of the phases (con¬ veyance of the solid in cells bounded by trays, flowing of the liquid by the gravity), the range of utilization of the equipment can be extended for the solving of practically all tasks involving the extraction of a solid with a liquid, i.e. the equipment should

be useful for the extraction of e.g. any type of solid, dry grists, granulated, granular, powder-containing aggregations with hete¬ rogeneous partizle size as well as wet, fat- -containing and similar materials of any kind with a good efficiency and safe operation. The invention is based on the recog¬ nition that the extension of the utilization range of an extractor and its safe operation can be achieved by eliminating the formation of a plug, substantially by avoiding the axial mixing-back, furthermore by bringing into vigorous movement the solid, e.g. grist or granulate being present in the cells between the conveying trays. Furthermore, it has been recognized that the mixing-back can be eliminated by elastically deformable, mobile sealing as well as by the excentric fastening (along the inner edge) of the drag chain to the trays whereas the strengthening of the movement of liquid within the cells can be achieved by pulsation of the liquid. It is known that, during extraction of a solid with a liquid, the active agent or an other component of the solid phase is transferred to the extraction liquid. The rate of extraction of the solid is sub¬ stantially defined by the concentration dif¬ ference between the concentration in the extraction liquid and that in the solid. This process is influenced inter alia by the me¬ chanical and chemical decomposition of the solid, the geometrical dimensions of its

particles, the temperature of extraction and the like. It has been recognized that, in addition to these, the extraction process can preferably and decisively influenced also by flowing the extraction liquid in a defined rate range (interval) around the solid particles of the material. The advan¬ tageous effect of this measure appears therein that an amount of the active agent flows out from the solid in a greater amount than commonly during the time unit and this proceeds more rapidly. This can be attributed thereto that the boundary layer developing in the environment of the solid particle during extraction can be eliminated by using the optimum (best) flowing rate mentioned above. The behaviour of the boundary layer during extraction is similar as if the geometrical dimensions of the solid particle were increased by the thickness of the boundary layer. According to our measurements, this boundary layer cannot be neglected: in the case of grists with a leaf-like structure, this di¬ mension represents about a half of the leaf- -thickness. This increase in the dimension exerts an effect on the extraction process in such a way as if the characteristic size of the solid particle were greater than the actual one and therefore, the active agent had to pass from the solid to the liquid through a longer path and by overcoming a higher resistance.

Our researches and investigations have been aimed to determine the minimum and op¬ timum, respectively liquid rate eliminating this boundary layer. It has been found that the material transfer coefficient (being characteristic of flowing out of the active agent) can be elevated by about 400?ό, i.e. the extraction process can favourably and definitely be influenced by maintaining the flow rate of the extraction liquid around the solid particles at a value of 500-700 cm/min preferably about 600 cm/min.

Our investigations were extended to state the practical possibilities of increasing the rate of the extraction liquid and to achieve the rate range defined above, chiefly a the optimum value of 600 cm/min. Firstly, it has been inventigated if this rate could be ensured by an unidirectional flow of the liquid. It has turned out that an about 35- -fold surplus amount of solvent would be required thereto, which would raise insolvable problems in the practice, i.e. on industrial scales.

Of course, the eventual utility of vibrating the liquid used in the bulk flow (conveyor) system for achieving the best rate of about 600 cm/min has also been stu¬ died. According to our experiments, disturbing swings of the exterior casing and cavitation phenomena in the liquid were induced by increasing the amplitude in the liquid phase over a defined limit (in a given defined

frequency range). It has been stated that a liquid rate being higher than an average rate of 28 cm/min could not be achieved- by vibration; this rate is rather far from the rate range of 500-700 cm/min, most preferably 600 cm/min defined above.

Finally, it has been recognized during our experiments and researches that an average rate of about 600 cm/min being most prefera¬ ble from the viewpoint of the efficiency of extraction can be ensured around the solid particle by pulsating instead of vibrating the liquid, which results in a frequency by two orders less, as well as in an amplitude by two or three orders higher than by vibration in the liquid space. By this mean (average) rate, the same material transfer coefficient could be achieved by using a small amount of the extraction liquid as if a great volume of liquid had unidirectionally been flown through the extractor. No harmful phenomena observed during vibration (swinging, eavi- tation) occurred by using such liquid rate achieved by the pulsation.

Based on the above recognitions, the task of the invention can be solved by a bulk flow (conveyor) extraction equipment having a tube-shaped casing, where an endless drag chain connected to a drying mechanism is present (situated), to which trays fitted with a filter sheet are interspacedly fastened; a loading (feeding) device (feeder) used to feed in the granular solid to be extracted

leads to the casing; a feeding orifice is provided in the wall of casing for introducing the extraction liquid into the casing; and the equipment possesses a filter unit in¬ corporated to the casing, used for separating the liquid containing the material extracted as well as a discharging outlet for removing the extracted solid, the principle of this equipment comprising: joining the chain links of the drag chain one to another by inserting rolls; fastening the trays rigidly to the central part of each chain link in the region of one of their circumferential sites and to the longitudinal geometrical centre line of the chain link; fastening a sealing element, which is widening outwards to the hind part of trays from the viewpoint of direction of passing, is elastically deformable and joins the inner surface of the casing during the passage of the trays; a pulsator for strengthening the movement of the liquid, which is connected to the casing, preferably in the region of its lowest situation.

The rigid and perpendicular mounting of the tray to the drag chain link results therein that the tray takes place radially, perpendicularly to the casing wall in all sections (both in the vertical and curved parts) of the casing. The pulsator is suitably a slow plunger pump with a great stroke-

-length. It is of purpose to use a pulsator with a piston establishing in the liquid preferably a frequency of 1.0-5.0 1/s suitably about 1.5 1/s and an amplitude (stroke) of 30-100 mm, preferably about 45 mm. By using such a pulsator, an average liquid rate of 500-700, preferably about 600 cm/min, being most advantageous for the extraction, can be accomplished around the solid particles without any problem.

According to an other criterion, the equipment according to the invention contains a sealing element bearing slits of generatrix direction. The structure material of the sealing element may be spring steel. The slits of the sealing element suitably have a radially widening form and start from the holes being at their inner root. The width of the slit may be about 0.1 mm in average. A further embodiment of the equipment is characterized thereby that the chain links have two parallel interspaced chain link elements prepared grom plate (sheet) material, the ends of which contain penetrating holes, the neighbouring chain links are connected one with the other by axes led through these holes and the rolls are revolvably mounted to the exes between the chain link elements. An embodiment exists, _^ accoxding to which the drag chain with its rolls is led in the casing along with the wall surface having a curve of smaller radius than the radius of the opposite surface.

According to an other criterion of the invention, the trays possess a circular (ring-like), cylindrical side wall as well as suitably several reinforcing ribs (fastened in the inner part of the ring) as well as a filter sheet, preferably a screen covering one of its orifices, and the sealing element contains in addition to its" conic part also a cylindrical part joining the outher surface of the side wall and fastened to the side wall.

According to an other embodiment of the invention, the equipment is fitted with cleaning devices (purifiers) provided for cleaning the rolls and filter sheets of the trays. These devices are in a chamber, where the casing ends from beneath and the forked wheels modifying the movement direction of the drag chain are also situated. It is preferable to fit a brush-type, revolving purifier for cleaning the rolls as well as to provide the purifier with swinging, scraping plates operated by an articulate-rodding driving mechanism controlled by a serrate control disk fastened to the axis of the forked wheel deflecting the drag chain.

The invention will be illustrated - hereinafter in detail on the basis of the drawings enclosed showing a preferred embodi¬ ment and several partial structural solvings.

Figure 1 shows the front view of the equip¬ ment together with a breakout of a part of the casing and chamber wall',

Figure 2 shows a section of higher scale taken along the line ^-A signed in Figure i;

Figure 3 shows the part B _^ signed in Figure 1 in a section of higher scale;

Figure 4 represents a section of a tray of the conveying mechanism taken along the line C_-C_ signed in Figure 5 by using a higher scale;

Figure 5 is a section taken along the line E_-E signed in Figure 4 with the breakout of the filter sheet at the site given;

Figure 6 shows part F_ signed in Figure 4 by using a higher scale;

Figure 7 is a view from direction of arrow signed in Figure 6*,

Figure 8 illustrates the part j _^ signed in Figure 1 in a vertical section of higher scale;

Figure 9 is a view from direction of the arrow I_ signed in Figure 8.

The extraction equipment shown in Figure 1 has a casing signed as a whole by the re¬ ference number 1, with a geometric central axis _. The casing is prepared from an U- -shaped tube having a circular cross-section. The casing parts la and lb corresponding to the vertical shanks of U are connected beneath by the curved casing part lc. This latter one contains the curved sections 14 connected by the lowest, straight tube piece 15. The casing parts la, lb and lc of the casing 1 (except the tube piece 15 and filter unit 10) are duplicate in their region beneath

the horizontal plane s_ signed by point-line, i.e. they have a double wall and a heat- -transfer (cooling and/or heating) medium can be flown in the spaces between the two walls; the fittings used for feeding in and removing the heat-transfer medium .are uniformly signed by the reference number 18 in Figure 1. The casing parts la and lb lead with their upper (not duplicate) ends to the common chamber 7. An endless drag chain 2 is led through the casing 1 and chamber 7, which trays 3 (ram plates) are equidistantly fastened to; the datailed discussion of the structural formation will later again be propounded. The neighbouring trays 3 bound cells 19 one with another and with the casing wall 1, which continuously move in the direction of arrow _f signed in the upper part of Fig¬ ure 1 since the drag chain 2 conveyes the trays 3 at an uniform rate. For the sake of a better survey, the driving mechanism (e.g. known per se) moving the drag chain 2 is not shown in Figure 1. Two forked wheels 16a and 16b are built in to the chamber 7 (where the driving mechanism mentioned may also be placed), which the drag chain 2 is led through and which play also the role of a deflecting plate as the motion path of drag chain 2 is modified by them. The driving mechanism is in a functional connection with one of the forked wheels, e.g. 16a. The direction of rotation of the forked wheels 16a and 16b is indicated by the sign v.

Into the upper, not duplicate region

(section) of the casing part lb a feeding device (feeder) is led, which is used for feeding in the granular (e.g. crushed, ground) solid previously treated mechanically and/or chemically to the casing 1, more particularly to the cells 19. The feeder 4 is suitably represented by a feeding screw; the granular solid is signed by the reference number 20 in Figure 1. The feeder 4 is connected to the feeding orifice 4a. The solid is fed in to casing 1 as shown by arrow .

The conduit 5 and feeding orifice 5a are aimed to introduce the extraction liquid to the casing 1, i.e. cells 19. The orifice 5a ends at the upper (not duplicate) section of the casing part la, oppositely to the feeding orifice 4a used for introducing the solid; the feeding in of the extraction liquid is shown by the arrow ja signed on the conduit 5. Thus the solid being present in the cells 19 and the extraction liquid passing through trays 3 broken through by orifices will move in a counterflow. In the casing 1 the motion of liquid is shown by the arrow jc, that of the solid by the arrow _d.

A pulsator 6 is built in to the casing part lc of casing 1, to the straight tube piece 15 connecting the curved sections 14. By the means of the pulsator, the motion of liquid around the solid particles being present in cells 19 may be strengthened and the rate of liquid can be increased to its

best (optimum) value, i.e. 600 cm/min.

The extraction of the active agent from the solid 20 occurs by the aid of the extraction liquid introduced through the feeding orifice 5a to casing 1, in the section between the feeding orifice 5a and the removal of the extract, i.e. the outlet orifice 13a. Within the path length of extraction, in the section beneath the horizontal plane z_ signed by two-point and line proceeds an extraction by soaking. The outlet orifice 13a mentioned above leads out from the lower part of the collecting chamber 11 of the filter unit signed as a whole by the reference number 10; the conduit 13 is aimed to remove the extract (see the arrow Ih signed on the conduit). Within the collecting chamber 11, a tube forming a not duplicate section of the casing part lb is shaped in the form of a filter mantle representing a part of the filter unit 10.

From the upper chamber 1 , beneath the forked wheel 16a, the throat 17 leads out; the solid extracted, containing no active agent leaves through the discharge orifice 17a of the throat 17 in the way signed by the arrows e_. In the region of chamber 7 over the throat 17, there are built in a cleaning device (purifier) 8 for cleaning the rolls of drag chain 2 and a cleaning device 9 for cleaning the trays 3.

A detail of the filter mantle 12 of the filter unit 10, which is curved

in a horizontal section and a detail of the collecting chamber 11 can be seen on a higher scale in Figure 2. According to this, the filter mantle 12 is formed from a slotted wall constructed of filter elements 12a formed from vertical rods with a lengthy, trapezoidal cross-section, between which outwards .widening slits 12b are present. The orifices 12c on the inner side have a significantly smaller width _i than those of orifices on the outer side (the difference may be 3- to 6-fold), whereas the width j_ of the filter elements 12a may be even the 10-fold of the size i_. Figure 3 shows a detail of a preferred embodiment of the pulsator 6 according to Figure 1 in a section of a higher scale. In this case (according to an example) a plunger pulsator is used, of which the piston- -housing 21 leads from above to the straight tube piece 15 forming a part of the casing 1 with the geometrical central axis _y_ of the extractor. The piston-housing is in separate connection with the cells 19 passing through in the direction of arrow Jf. The piston rod 23 of piston 22 moving in the piston-housing 21, fitted with a suitable sealing, which is connected with a driving mechanism (not shown on the Figure), makes an alternating movement (upwards - downwards) according to the double arrow J<. In the extractor according to the invention a pulsator 6 is used, which is capable to establish a pulsation system showing the following char-

acteristics: frequency: 1-5 1/s, suitably about 1.5 1/s', amplitude: 30-100 mm, suitably about 45 mm ("Amplitude" means the average displacement of liquid within casing 1 of the extractor.) An advantageous embodiment of trays 3 of the extraction equipment according to Figure 1 is illustrated in detail in Fig¬ ures 4-7.

In the case of this example the tray 3 is circular from a view from above (Figure 5 ) and its cylindrical annular side wall 29 is reinforced by the ribs 25, 26 and 27, 28 prepared from sheet material. The space bounded by the cylindric side walls on one side being in the direction of passing of the drag chain 2 (arrow jf_, Figure 1) (above on Figures 4-6 ) is covered by a filter sheet 30, e.g. screen getting to a direct contact with the transported solid. The filter sheet 30 may be prepared e.g. from metal or an other material, mainly e.g. plastic, its whole size is conveniently between 0.5 and 1.5 mm. Practically, the granular solid cannot penetrate through the holes of such size whereas the extraction liquid can freely flow through the filter sheet 30 in a direction opposite to that of the solid. (The flow of the liquid is ensured by the hydrostatical pressure arising from the height difference between the feeding orifice 5a signed in Figure 1 and orifice 12c (Figure 2) on the inner side of the filter mantle 12. The

elastic sealing element ("collar") which is capable of an elastic deformation and is signed as a whole by the reference number 31, is connected to the other lower edge of side wall 29 (annular) according to Fig¬ ures 4-6. The sealing element has a cylindric part 32 and a conic part (truncated cone) 33; the former one joins from outside the outer mantle surface of the cylindrical side wall 29. This cylindric part 32 is from outside overlapped by the edge of the filter sheet 30 wrapped onto the side wall 29 and in the area of overlapping fastening elements, e.g. screws are led through the filter sheet 30 and cylindric part 32 as well as side wall 29; thus, both former structural parts are fastened to the latter one.

According to the sense, the outer dia¬ meter D, of the cylindric part 32 of the sealing elemment 31 (Figure 4) is smaller than the inner diameter J of casing 1 in Figure 1. Suitably, the difference is such that the slit between the casing wall and the outer edge of tray 3 is radially 0.05xJ mm. The angle of mantle of the conic part 33 is selected in such a way (Figure 6) that, in an undeformed (free) state, the longest diameter D_ of the conic part 33 drawn in Figure 6 be greater than the inner diameter J of casing 1 (Figure 1); D„ is suitably 1.15x mm.

The sealing element 31 (eventually only its conic part 33) may be prepared e.g.

from plastic and in this case it can be pro¬ duced in one piece, in a compressed form in such a way that the mantle of truncated conic form (i.e. the conic part 33) be e- lastically deformed during its passage through the tube (i.e. in the casing 1, Figure 1). The occurrence of the elastic deformation can be promoted by forming the conic part 33 with the slits 37 of generatrix direction, which is more necessitated in the case of a sealing element 31 ("collar") prepared from a metallic substance, e.g. stainless spring steel. A sealing element 31 prepared from stainless spring steel can be seen in Figures 6 and 7; the slits 37 divide the sheet of truncated conic form ("collar") to blades (tongues) 35. At the inner end of slits 37, in the region where the conic part 33 passes into the cylindric part 32, wholes 36 are present, the role of which is to eliminate the tensions eventually de¬ veloping in the root in the course of a longitudinal cutting. During the production of the conic part 33 prepared from spring steel, it should be considered that the blades (tongues) 35 be situated in the direction of rolling, i.e. along the grain (in the preferred orientation) (arrow 1_, Figure 7). The blades (tongues) can be prepared either from metallic or nonmetallic structural ma¬ terials', a substantial demand against the substance lies therein that it should be capable of elactic deformation and to return

to its original form after ceasing of the load directed inwards.

Each tray 3 is fitted with one chain link signed as a whole by the reference number 38 (Figure 4), by rigid fastening (fixation), and each chain link 38 possesses two chain link elements 38a, 38b each, which are fastened to the reinforcing ribs 25, 27 on the outer end thereof by an interspace n one from another (Figure 5). The chain links 38 of j; height are in a perpendicular position to the plane of the filter sheet 30 of tray 3 and extend in opposite directions (upwards and downwards, according to Figure 4) with the same interspace _t, from the upper plane of the filter sheet 30 as well as from the lower edge of the sealing element 31. Between the chain link elements 38a, 38b in the region of one end of them a revolvable roll 40 fastened to the axis 39 is mounted whereas there is a hole 41 on their other end for leading through such an axis 39 (Figure 4). It is obvious that the endless drag chain 2 shown in Figure 1 forming together with the trays 3 (ram disks) a bulk flow (conveyor) transport (conveying) system can be developed by uniting such neighbouring chain links 38, which is in every case accompanied by inserting one roll 40 each and leading one axis 39 each through the hole 41 (and by an assurance known in se against outsliding).

An essential characteristic of the conveying mechanism according to the invention

consists therein that, as it is shown in Figure 1, the drag chain 2 is situated in casing 1 containing the curved section 14 in such a manner that the rolls 40 abut the inner surface of casing 1 along the inner side thereof, where the radius f^, of the curved sections 14 is smaller (the greater radius of the outer curve is signed by R_„ in Figure 1). Due to this arrangement and to the perpendicular position of chain links 38 in relation to the plane of the respective trays 3 (filter sheet 30), the trays 3 will take place perpendicularly to the geometrical central axis (Figure 1) at any site (i.e. in the curved sections 14, too) in the casing 1 and the slit size between the edge of trays 3 and the inner wall surface of casing 1 always remains constant (unchanged). This is one of the preconditions therefor that the truncated cone-shaped, i.e. conic part 33 of the sealing element 31 (Figures 4- -7), ensures the sealing during a radial displacement in any direction. This truncated cone-shaped, moving seal is deformed while passing in the tube-shaped casing 1, functions (operates) as a moving seal ring and inhibits that a granular solid (e.g. grist) at any time get back from a former cell to the next cell (in relation to the direction of passing; arrow d in Figure 1) through the slit between the tray and the casing wall. In short: due to the solving according to the invention, the sealing element 31 (collar) completely

eliminates the danger of mixing-back, i.e. "falling-back" from one cell to the next one in any section of casing 1 in each phase of movement; thus, no plug can be developed and the extraction liquid freely flows in a countercurrent direction to the solid. In Figures 8 and 9, where the structural elements dicussed above are signed by the same reference numbers as used above, the cleaning devices 8 and 9 are shown, which are illustrated only schematically in Figure

1. The cleaning device 8, used for cleaning the rolls 40 of drag chain 2 is placed beneath the forked wheel 16a driving the drag chain

2, directly over the end of casing part la at chamber 7 and has a disk-shaped brush 42, which can be rotated by the axis 43 in the direction of arrow w, ', for this rotation, the driving disk 46 connected with the driving mechanism (not shown in the Figure) is provi¬ ded, which rotates the disk 42a of brush 42 by intermediation of the drive belt 45. The axis of the driving disk 46 is signed by the reference number 44. It can clearly be seen in Figure 8 that the brush 42 is in direct connection with a roll 40. The roll 40 purified from solid material can unimpededly be attached to the forked wheel 16a and smoothly joins the saddle 51 formed on the front surface of the teeth thereof. Due to such cleaning of rolls 40, no solid can be deposited on the toothed part of the. forked wheel 16a, the joining of roll occurs

unimpededly therefore, the undisturbed opera¬ tion of the drag chain of the bulk flow (conveyor) system is ensured.

The cleaning of trays 3 conveying the granular solid, particularly the cleaning of filter sheets 30- forming a part thereof are necessary since the solid is deposited on the surface of the filter sheet in the ascending branch of the extractor (in the casing part la, Figure 1) and can clog the holes of the filter sheet, whereby the movement of liquid countercurrently passing through the solid is impeded. This problem is elimi¬ nated by the cleaning. As shown in Figures 8 and 9, the mechanical cleaning device 9 contains an articulate rodding driving me¬ chanism signed as a whole by the reference number 54 as well as scraping plates 53 being in a free swinging movement along the surfaces of trays 3, which are operated by the driving mechanism mentioned, which latter is in func¬ tional connection with the toothed control disks 55 wedged to the axis 52 of the forked wheel 16a. The articulate rodded driving mechanism 54 possesses horizontal rods 56 and vertical rods 47; the scraping plates 53 are turnably mounted to the upper end of rods 47. There are springs 48 on the rods 56 and springs 49 on the rods 47; both these springs are provided for return into the normal position. The operation of the cleaning device 9 is synchronized with the rotation of the forked wheel 16a by intermediation

of the control disks 55: namely, as the control disks 55 rotate in the direction of the arrow v* together with the axis 52, they lift and draw inwards the horizontal rods 56, whereby the vertical rods 47 are also lifted up whereas the scraping plates 53 turn away. When the tooth of the control disk 55, lifting the rods 56, turns beyond at their end, the springs 48 again compel these rods outwards to the starting position similarly as the springs 49 press back the vertical rods 47 downwards to their starting position and therefore, the scraping plates 53 clean the filter sheet 30 of the disks 3 contacting with them. The movement of rods during the processes described above are shown by the double arrows _j i and o_ in Figures 8 and 9 whereas the motion of the scraping plates 53 is indicated by the double arrow £ in Figure 9. The swinging motion of the scraping plates 53 over the trays 3 can be made safely operating by blocking solvings (not shown, known per se) .

It should be noted that the cleaning of the filter can be solved by blowing in air or an inert gas instead of mechanical cleaning of the filter sheet and/or a washing with a washing fluid is also possible. It is suitable to use the cleaning device 9 shown in Figure 8 and 9 (or a mechanical cleaning with an other system) when the extrac¬ tion liquid is a solvent or a liquid mixture containing valuable ingredients (components);

namely, in the case of an organic solvent, the gas used for blowing off can only be an inert gas whereas in the case of washing with a liquid, the liquid introduced makes the subsequent treatment of the extracted material (liberation from solvents, drying) difficult.

It has to be remarked that the cross- -section of the tube-shaped casing 1 (see alsoFigure 1) can be not only a circle but practically any other form, however, the forms of tray 3 and sealing element 31 must follow the form of the cross-section given. The cleaning device 9 (and also cleaning device 8) according to Figures 8 and 9 can be used at all cross-section forms of the casing 1.

The process of extraction is carried out by using the equipment according to Fig¬ ure 1 as follows.

The endless drag chain is started, which passes together with the trays 3 mounted thereto at an uniform rate in the casing 1, in the direction of arrow _f, which, accor¬ ding to the sense, corresponds to the arrows ^j due to the reversing effect of the forked wheel 16b and agrees with the passage direction of the solid. The mechanically/chemically pretreated solid 20 to be extracted is con¬ tinuously fed into the moving cells 19 (arrow ^) by the means of the screw feeder 4,* the extraction liquid is also continuously intro¬ duced through the conduit 5 (arrow b_) . The

countercurrent (arrow c) liquid extracts the active agent from the solid 20 then, due to the hydrostatic head difference H, (liquid column), the liquid containing the active agent, i.e. the extract comes out from the casing 1 in the filter unit 10 and leaves through the filter mantle 12 and conduit 13 (arrow ) . The instantaneous value of the driving force FL, (hydrostatic head difference) may vary between Jj, and (H.-0.5 _H_„) depending on the selected volume flow of the extraction liquid and position of the granular solid.

The geometrical dimension JH- is the height difference between the stump 5a used for introducing the extraction liquid and the bottom of orifices 12c on the inner side of the filter mantle 12.

The geometrical dimension ]„ is the geometric height of the orifices 12c on the inner side of the filter mantle 12. The value of _H_„ is equal to (1.2-3)g, where g means the interspace of trays 3 (Figure 1). According to the invention, the ex¬ traction process is extremely preferably strengthened (intensified) by pulsing the liquid with the pulsator 6 in the frequency and amplitude ranges defined above, whereby a rate of about 600 cm/min can be achieved around the particles of the solid 20 being present in the cells 19. The ranges of mixing- -back and fall-back of the solid being present between the neighbouring cells 19 has com-

pletely been eliminated by the sealing solu¬ tion according to Figures 4-7, i.e. by using the moving sealing element 31 (collar). The extract leaves the filter unit 10 through the filter mantle 12 previously discussed in detail and illustrated on a higher scale in Figure 2. This filter mantle 12, the vertical orifices 12c thereof are continuously cleaned, scanned by the sealing elements 31 fastened to the trays 3; thus, due to the slits widening downwards, the material forced into the slits is whirled out together with the liquid. Thus, the danger of clogging of the filter unit 10 is completely eliminated.

The method of cleaning trays 3 and rolls 40 by using the cleaning devices 8 and 9 has previously been described in detail. The solid 20 exempted from its active agent content (or most part thereof) is discharged into the throat 17 in the upper chamber 7, at the turning site of trays 3 at the forked wheel 16a and leaves the equipment through the discharage orifice 17a according to the arrow e.

The advantageous effects connected with the invention are summarized hereinafter. The most important advantage of the equipment according to the invention lies therein that the mixing-back and washing- -back of the solid from a cell to the next one are impeded with a complete safety. In this way the formation of "plugs" and

therefore, the danger of interruption of the extraction process are eliminated. Due to the pulsation, the parameters of extraction (low proportion of liquid, higher efficiency of extraction beside a shorter duration of extraction) become more favourable.

An other, additional favourable effect appears therein that peculiar materials, which are otherwise difficult to treat and cannot be extracted by the extractors known can also be extracted by the equipment fitted with a pulsator.- Materials of this type are e.g.: fat-containing grists containing particles adhering one to another (ergot, dried animal organs); powder-containing grists (where particles smaller than 0.125 mm in size are present in an amount of 10- -20?o ^" within the aggregation); granulates with small particles of a great volume (plas¬ tics), and gel-like solids (marrow). By using the equipment according to the invention all solid/liquid extractions can be inten¬ sified, where the continuous phase is a liquid and the disperse phase is a granular solid. The invention can be used both as a novel apparatus (equipment) as well as for the transformation of an existing equip¬ ment.

It will be appreciated that the in¬ vention is not restricted to the embodiment discussed above in detail, but can be accom¬ plished in several various ways within the scope of protection defined in the claims.