US2203666A - Method and mechanism for continuously forming liquid-impervious plugs in extraction units - Google Patents

Description

June 11, 1940. M BQNQTTQ 2,203,666

lit-mien Am) MECHANISM r011 CONTINUOUSLY FORMING LIQUID-IIPBRVIOUS PLUGS IN EXTRACTION UNITS Filed July 19, 1938 3 Sheets-Sheet 1 v 6 E T .J

0 m w 2 I 1 0 1 4m 1 m INVENTOR M cHELE Bozvorro Y 5 ATTORNEY June 11, 1940. M BQNQTTQ 2,203,665

' METHOD AND MICHANISM FOR CONTINUOUSLY FORMING LIQUID-IIPERVIOUS PLUGS IN EXTRACTION UNITS Filbd July 19, 1938 3 Sheets-Sheet 2 I -T E INVENTOR I MaHELE Bolvorm I J b ATTORNEY June 11, 1940. BQNQTTQ 2,203,666

METHOD AND ncmmlsu FOR CONTINUOUSLY FORMING LI uIn-IuPERvIoUs PLUGS Iu EXTRACTION unn's i-10d July 19, 1938 3 Sheets-Sheet 3 j 120 110 113 /fi a INVENTOR McHELE BONOTTO ATTOiRNEY Patented June 11,1940

OUSLY FORMING LIQUID-IMPERVIOUS PLUGS INJEXTRAGTION UNITS Michele Bonotto, Evansville, Ind., assignor to E:- tractol Process, Ltd., Wilmington, Del., a corporation of Delaware Application July 19, 1938, Serial lilo. 219,973

7 Claims.

This invention relates to improvements in methods and mechanisms for continuously forming liquid-impervious plugs in extraction units and constitutes an improvement in the method and apparatus of my prior application Serial No. 94,582, filed August 6, 1936.

In my saidearlier application, I have shown a plug-forming mechanism and described a plugforming method by which solvent-soaked solid material from an extraction unit is continuously fed by a conveyor screw of relatively small capacity, (thus feeding a relatively small feed of such solid material), into a packing conduit having a packing screw of larger capacity than the volume of said feed of solid material, and a plug is incrementally formed near the valved end of said packing conduit by continuously pressing, with said packing screw, the relatively small feed on one end of said plug in said packing section while continuously forcing the opposite end of said plug through said valved end of said relatively large capacity conduit to discharge material from the extraction unit, all of the work being done along a single axis.

In operating a device such as described in the application above-mentioned, I have found that a definite relationship exists between the capacity of the screw that feeds from the extraction tank into the packing conduit (which I shall hereinafter call the feeder-screw), and the capacity of the packing screw, and if for some reason the capacity of the packing screw is decreased, a choking action occurs in a 20min the packing conduit adjacent to the feed-opening between said packing conduit and the extraction tank. With some materials such a decrease in capacity in the packing screw does not take place, but withother material and especially with materials of sticky character, such as distillers grain, difficulty of that sort is apt to occur.

To avoid such difliculties in installations such as shownin said applicatioruthe diameter of the packing screw should be calculated to have a capacity of, say, four or five times that of the feeder-screw. However, in an extraction unit of, for example, say one hundred (100) tons per day output, the dimension of the packer-screw, in order to assure that the quantity of material passing through the said feed opening between the extraction tank and the packing conduit will be less than the quantity of material that the packer-screw is able to pack and expel, would be too big for practical operation, and the problem is presented of procuring the necessary increase in the capacity of the packer-screw over the feeder-screw without unduly increasing the size.

of 'the packer-screw. I have found that this problem can be solved by increasing the speed of the packer in relation to the speed of the feeder-screw, or by increasing both the relative speed and the relative diameter of the packerscrew over the feeder-screw. While this result may theoretically be accomplished if positioning of the feeder-screw and packer-screw are along the same axis, I have found that it is desirable that the two screws be mounted on independently-driven shafts positioned on different levels and preferably that the independently-driven shaft of the packer-screw be positioned in the same vertical plane as the feeder-screw shaft and in installations where the solid material being extracted is heavier than the solvent, it is desirable'that the packer-screw should be located directly beneath the feeder-screw, and in all cases an intermediate feed chamber or feed box should be provided. Obviously, in a construction where the capacity of the packer-screw is increased by increasing the speed thereof, the

packer and feeder-screws may be of the same or different diameters;

With these and other objects in view, the invention comprises the combination of members and arrangements of parts so combined as to co-act and cooperate with each other in the performance of the functions and the accomplishment of the resultsherein contemplated, and comprises in one of its adaptations the species or preferred form illustrated inthe accompany drawings, in which:

Fig. 1 is a vertical section partly broken away, of an extraction unit for use with a solvent of specific gravity lower than the extracted material and showing my improving plug-forming mechanism embodied therein;

Fig. 1 is a similar fragmentary section of the outer end of the packing mechanism shown in Fig. 1;

Fig. 2 is a fragmentary view showing a modifled form of the packing mechanism shown in Fi Fig. 3 is a horizontal section on the line 3-3 of Fig. l, partly broken away. of the feeding and packing mechanism shown in Fig. 1;

Fig. 4 is a vertical section on the line 4-4 of Fig. 1, looking in the direction of the arrows;

Fig. 5 is a vertical section, partly broken away,

of an extraction unit showing another slightly modified form of feeding and packing mechamsm;

Fig. 6 is a vertical section, partly broken away,

of still another modified form of feeding and packing mechanism embodying my invention;

Fig. 7 is a section on the line |--1 of Fig. 6, looking in the direction of the arrows;

Fig. 8 is an enlarged fragmentary vertical section of the end of a packing conduit and adjacent parts employed by me, and Fig. 9 is a section on the line 0-8 of Fig. 8.

Referring now to these drawings which illustrate a preferred embodiment of my invention, one way to avoid the difficulties and accomplish the results hereinabove described is to modify the mechanism described in application Serial No, 94,582, in such manner that the speed of the packer-screw will be higher than the speed of the feeder-screw, so that the packer-screw, by such increased speed, will handle more material than the feeder-screw is able to feed through the said feed opening, and in Figs. 6 and 7 I have illustrated an extraction unit, (which will hereinafter be more particularly described), having, in a manner similar to that described in my said application, the feeder and packer-screws arranged along a single axis but being modified to permit the packer-screw to be rotated at a speed increased over that of the feeder-screw. However, an arrangement of that kind will require a bearing inside the packing conduit with the consequent danger of causing a choke. But apart from that difilculty, a modiflcation of this kind will theoretically solve the problem.

From the practical operating point of view, however, it is preferable in order to enable the speed of the packer-screw to be increased and run at a higher rate than the speed of the feeding screw, that instead of the action described in my application Serial No. 94,582, taking place along a single axis of the shaft driving the packer-screw and the feeder-screw, such action shall take place on two levels, with the packerscrew being positioned below the feeder-screw, and with this end in view I preferably provide, in the extraction tank, a feeder-screw of given size ordiameter and preferably driven by an independent motor at a rate of speed which represents the working capacity of the extractor, and I feed the exhausted and discharged material from the extraction tank into and through a packer-feed chamber or box preferably located outside the extraction tank and then into the packer-oonduit on a packer-screw positioned in said packer-conduit below and in the same vertical plane as the said feeder-screw, the packerscrew being mounted on a shaft also preferably driven by an independent motor at such a speed as to assure, at any given moment, that the ma terial passing through the material discharge or feeding opening and into the feed box may be readily evacuated from said box and pushed against the cone valve and thereafter discharged into a suitable hopper from which such material will go to the dryers.

In Figs. 1 to 5, I have illustrated several constructions showing mechanisms with the screws disposed apertures 3'. The discs are mounted on a central shaft I and preferably revolve in a horizontal plane without causing the solid material to revolve therewith, and to prevent such movement of material with the discs, I preferably provide within the tank I, scraper arms I which are suitably supported within the tank to provide a positive stop against such revolving movement of material with the revolving discs. This mechanism more particularly forms the subject-matter of a still earlier application Serial No. 48,646, filed Novemberl, 1935, and is here illustrated merely to show one form of extraction unit in which the solid material to be extracted and the solvent are caused to be moved continuously in counter-current through the extraction section and in oonnectionwith which the solid exhausted material is formed into an impervious plug at the discharge'end thereof. In the embodiment illustrated, the packer-screw is of larger diameter than the feeder-screw and said screws are mounted at different levels, one below the other, but in the same vertical plane. In the unit shown, after the material passes through the zones a, b, etc., it is caused to pass through a bottom expansion chamber l which is preferably, as illustrated more particularly in Figs. 3 and 4,

provided with inclined sides 8', 8', mer ing intoa trough or casing 8', within which is mounted a horizontally-disposed conveyor screw II which is preferably perforated and mounted on a horizontal shaft II which is rotated independently of the rotation .of the packer-screw hereinafter described, from any suitable source of power. As shown, the shaft II is rotated through beveled pinions II, II the latter of which is connected with a vertical shaft 5 preferably extending to an independent source, not shown. As illustrated, a packer feed-box F is suitably supported and disposed outside the extraction tank in alignment with the discharge aperture l' of said extraction tank and the shaft II' is supported at its inner end in a bearing ll connected to the lower end of the extraction tank, while the outer end of said shaft Il' extends into and passes through a feed chamber 1 of said feed box F and is supported in a bearing ll on the outer surface of said box.

The function of the feeder-screw II is to unload the exhausted material from the bottom of the extraction tank into the chamber I ofthe box F and, as only a relatively small amount of horse power will be necessary to do this work, I preferably apply, to the shaft S, an independent motor which will have a rate of speed, as aforesaid, suflicient to operate the screw at a 'rate commensurate with the discharge capacity of the extractor.

In-said preferred form of my invention shown in Figs. 1 and 1' I provide, below the feed screw Ill' and preferably in the same vertical plane as said screw, a packer-screw l2 revolving within one end of a packer conduit I! which is connected with the feed chamber 1 by a feed opening I. The packer-screw i2 is mounted independently of the feed-screw ll and is supported at one end in a bearing b and the other end in a bearing b, on a hopper H connnected with the outer end of the packing conduit l2 and through which said shaft extends, and at all of the bearings I preferably provide conventional stumng boxes to maintain fluid-tight Joints with the shafts. The packer-shaft II is, as shown, driven independently of the shaft il' through pinions l2, li by shaft 8' which is preferably driven by an independent motor.

The horizontally-disposed and perforated conveyor screw it is thus rotated in its trough 8" 7i aaoaooo and conveys or moves all solid material that. passes to the bottom of the tank by gravity,

through the opening I" in the tank I and into the chamber for the box F from which, in accordance with my present invention, the material ls'fed by gravity through the opening I into the packing conduit l2 and on a rear portion the screw i2 situated below said opening I. In the form shown in Fig. 1, the packer-screw is thus not only independently supported and driven independently from the screw it but is, as aforesaid, larger or greater in diameter than the feed screw I Exhausted solid material from the extraction column or tank sometimes has a tendency to flow too freely through the opening I" and into the chamber! of the box F and in order to stop such free flow of material, I have, in the form of my 'of conduit will take the place and serve the function of the baffle B shown in Figs. 1 to 4.

The material passing through the feed openin I on the rear portion of the screw l2 is then moved forwardly and packed into an incrementally-packed liquid impervious plug near the outer end of said packer-conduit i2, and, as shown, in a plug-forming chamber i3 disposed in said packer-conduit between the end of the packerscrew l2 and a conical valve l4 slidably mounted on the shaft II and arranged to exert pressure against the outward movement of the solid material through the packer-conduit to form a plug and then to provide, at the outer end of the plug, a yielding pressure to permit discharge of the outer end of said plug into the hopper H.

.Controlled pressure on the valve is to force the same toward its seat at the outer end of the packer-conduit is preferably supplied by hydraulic means, such as'an oilcylinder IS. the hollow piston stem l5 of which abuts the end of said valve H as shown in Fig. 1 The hydraulic cylinder I5 is of conventional construction and is shown more or less schematically with inlet and outlet ports l5, l5, but it will be understood that the usual pressure-controlling and indicating means, not shown, may be provided- The bore of the packer cylinder is preferably provided with a series of straight ribs or strips l6 extending parallel to the axis of the shaft l2 so as to provide a slight space between a cylinder and the screw to permit return or rearward movement in the packing conduit of liquid squeezed from the material, and these ribs also assist the forward movement in the conduit of the solid material when the same has a tendency to pack between the flights of the packer-screw.

It is desirable that the portion of the shaft l2 which extends through the packing chamber l3, be tapered outwardly toward the valve it. Such taper is desirable because there is a tendency for the liquid in the material, at the packing side of the plug, to form a channel surrounding the shaft and thus to pass through the plug and in order to overcome this difficulty and to avoid formation of such a channel the said shaft is, as aforesaid, provided with a taper at il In the embodiment of my invention shown in Fig. 1, I preferably provide a solvent-return channel F communicating between the feed box F and the extraction tank I to permit solvent squeezed out of the material evacuated and being formed into a plug to return to the tank, and said unit is provided with a solvent inlet 1, a solvent pump P, a miscella outlet 0 and a feedhopper FH. The shaft 4 is rotated through pinions I, l and shaft S connected with any suitable power source.

In Fig. 2, I have shown, in fragmentary section, a construction in which pressure on the valve at the end of the packer-conduit I2 is provided by spring It the degree of pressure being variable by the nut ll" mounted on a rear reduced and threaded portion I290! the shaft I2 said shaft preferably being supported in the same way shown in Figs. 1 and 1.

In Fig. 5, I have shown a plug-forming mechanism in which a packer-screw IZ has a smaller diameter than the feeder-screw i ii and the feeder i0 may therefore have very slow speed in comparison with that of the packer-screw Il A combination such as this is'clesirable when the material to be withdrawn from the extractor is of very light specific gravity and which, for that reason, has a tendency to be set in motion by the vortex which would be created by a fast revolving feeder-screw. In such a case, the smalldiameter fast-revolving feeder-screw would not be able to unload through the discharge opening I" because the feeder would merely act as an agitator in thebottom of the extractor.

To avoid such vortices, when the exhausted material is of very light specific gravity, I utilize a packer-screw of relatively small diameter as in Fig. 5 and this packer-screw being of smaller diameter than the feeder-screw must be run at afaster speed.

The speed at which the packer should be revolved is also determined by the nature of the;

material treated in the extractor because, if the chamber f is allowed to become about empty, the packer will act. also as an agitator. From the above, it will be understood that the speed of the feeder-screw and the speed of the packer-screw have a certain relationship which can only be fixed for each material by actual exper ments, and which will be different for the same kind of material when the moisture percentage varies As a general rule, the ideal working condition will be when the unloading capacity of the feederwalls of the cylinder, including the ribs, or to the screw per se.

One of the main reasons for such decrease of capacity of thepacker-screw is a certain backslipping which occurs between the flights of the packer-screw, and that back-slipping is also different for different materials. By back-slipping I mean the tendency of the material to work itself backwards. starting from the point adjacent to-the end of the packer-screw, where the packing of the plug starts to take place. As will be seen, the theoretical displacement-capacity per revolution of the screw is decreased. by this fact.

Another reason which contributes to a. reduction in the capacity of the packer-screw is the pressure per square inch necessary to be applied by means of the-valve H to the outetrend of the plug in order to counterbalance the weight of the solvent in the extraction column.

While, therefore, I am unable to state the minimum capacity of the packer-screw in relation to the feeder-screw, it will be possible to state that the capacity of the packer-screw in relation to the feeder-screw should be such that, taking into consideration all the conditions of slipping, specific weight of the material, pressure of the valve etc., the chamber I should always be full of solids.

For the preferred dimension of a twenty-five (25) ton per day extraction column, I suggest a 6 inch diameter, 7 inch pitch feeder-screw, and a 9 inch diameter, 4 inch pitch packer-screw; the revolution of the feeder-shaft being twelve (12) per minute and the revolution of the packershaft being fifteen (15) per minute, for material having specific gravity of soybeans, cotton seed, corn germ, etc., with moisture around eleven (11) percent.

In commercial installations, it will be a very simple matter to find the right relationship between these screws if both the packer-shaft and the feeder-shaft are individually driven and a variable speed reducer is inserted between the motor and the shaft of each screw.

In Figs. 6 and 7, I have shown a modified form of mechanism in which the shaft llll of the feeder-screw l0! and the shaft H2 of the packer-screw 2 are on the same line but independently driven. Fig. 7 shows the preferred position of anchor brackets H3 for the joint bearin'g-ll3' for the two shafts H0 and H2.

The same general considerations will apply to this arrangement. Thus the opposite end of the shaft H0 is supported in a bearing H5 connected to the bottom of the extraction tank I and is driven independently of the packer-screw shaft H2 through pinions H6 and II! with shaft S" which in turn is connected to a suitable source of power such as a motor, not shown, while the opposite end of the shaft H2 is supported in a bearing H8 and rotated through pinions H9 and J20 from shaft S which is connected with any suitable source of power, such as an electric motor, not shown. In the construction shown in Figs. 6 and '7, the feeder-screw, as shown, has a single enlarged flight I III at its outer end and feeds solid material into an intermediate packer feed chamber i corresponding to the chamber 1 of the box F from which chamber f the packerscrew H2 will take such material and pack the same against the spring-pressed valve into a liquid-impervious plug, as hereinabove described.

In Fig. 8, 'I have shown, in an enlarged fragmentary vertical section, the-end of the packing conduit and adjacent parts and particularly my ing through the packer-conduit is compressed,

as hereinabove stated, it forces the valve outwardly to'slide onthe shaft to open position. When material is being continuously discharged between the valve and its seat, the compressed material continuously presses the valve back into the working position shown in the full lines in-said Fig. 8. In said closed and opened positions, the valve I4 is held against rotation with the shaft l2 by the friction of the spring or by other pressure-applying device. Usually the hollow cylindrical plug or stick of material, due to the pressure of the spring, disintegrates when the valve is pressed back to said positionshown in full lines. The valve is, by the compressed plug, at times pushed beyond the fully-open position so shown. in full lines, and I preferably provide means positioned adjacent to the fullyopen'position for causing the valve to be rotated by the shaft when such larger opening occurs. Such rotation of the valves is accomplished by fastening, on the shaft, a collar C rotatable with the shaft, mounting on the collar one or more clutch teeth T and providing the valve with gear teeth T. The rotating action of the valve packing screw conveyor, moving said packingscrew conveyor at a different velocity than the feeding conveyor and at a rate of speed that will provide, in said packing screw conveyor, greater capacity than the feeding conveyor, and continuously packing a plug of said exhausted material within said packing conveyor against a yieldable valve. i

2. A method of continuously forming liquidimpervious plugs in extraction units, which consists in continuously feeding, by a feeding conveyor of given capacity, exhausted solid material from an extraction unit into a feed chamber on the same level as said feeding conveyor, then causing the movement of said material to a different level and into contact with a packing screw conveyor, moving said packing screw conveyor at a different velocity than the feeding conveyor and at a rate of speed that will pro vide, in said packing screw conveyor, greater capacity than the feeding conveyor, and continuously packing a plug of said exhausted maactuating said packer-conveyor-screw at a different velocity than the actuation of the feederconveyor.

4. Apparatus for continuously forming liquidimpervious plugs for extraction units employed in the solvent extraction of oil-bearing solid materials, comprising, in combination, an extraction tank, a packer-conduit of uniform diameter connected with said extraction tank, a feeding conveyor in said tank for conveying exhausted solid material out of said tank and feeding the same into said packer-conduit, means for actuating said feeding conveyor, a packer-conveyor-screw of uniform diameter in said packer-conduit and a packer-valveat the end thereof, said packerconduit and packer-conveyor-screw being located on a different level than said feeder-conveyor, a feeder-box connected to said feeder conveyor and leading to said packer conduit, and means for actuating said packer-conveyor-screw at a different velocity than the actuation of the feeder-conveyor.

5. Apparatus for continuously forming liquidimpervious plugs for extraction units employed in the solvent extraction of oil-bearing solid materials, comprising, in combination, an extraction tank, a packer-conduit of uniform diameter connected with said extraction tank, a feeding conveyor in said tank for conveying exhausted solid material out of said tank and feeding the same into said packer-conduit, means for actuating said feeding conveyor, a packer-conveyor-screw of uniform diameter in said packer-conduit and a packer-valve at the end thereof, means for actuating said packer-conveyor-screw at a different velocity than the actuation of the feeder-conveyor, and hydraulic means for exerting a controlled pressure on said packer-valve.

6. Apparatus for continuously forming liquidimpervious plugs for extraction units employed in the solvent extraction of oil-bearing solid materials, comprising, in combination, an extraction tank, a packer-conduit of uniform diameter connected with said extraction tank, a feeding conveyor in said tank for conveying exhausted solid material out of said tank and feeding the same into said packer-conduit, means for actuating said feeding conveyor, a packer-conveyor-screw of uniform diameter in said packer-conduit and a packer-valve at the end thereof, means for actuating said packer-conveyor-screw at a different velocity than the actuation of the feederconveyor, and ribs disposed in the bore of said packer-conduit parallel to the axis thereof.

7. Apparatus for continuously forming liquidimpervious plugs for extraction units employed in the solvent extraction of oil-bearing solid materials, comprising in combination, an extraction tank, a packer-conduit of uniform diameter connected with said extraction tank, a feeding conveyor in said tank for conveying exhausted solid material out of said tank and feeding the same into said packer-conduit, means for actuating said feeding conveyor, a packer-conveyor-screw of uniform diameter in said packer-conduit and a packer-valve at the end thereof, means for actuating said packer-conveyor-screw at a different velocity than the actuation of the feederconveyor, resilient means for forcing said valve toward the end of said packer-conduit to form the plug and normally to disintegrate the same, and supplemental means for positively connecting said valve to the shaft to assist in disintegration of the plug being discharged from the Packer-conduit. A

MICHELE BONO'I'I'O.

Images