Abstract:
The present invention is a method for using a batch centrifuge to separate the granulated material of a container from whatever liquid residue remains within the container. Though this technology is suitable for many diverse applications, a primary objective is the separation of the recyclable plastic of a motor oil container from the remaining reusable motor oil within the container after the container has ostensibly been emptied. The apparatus may be utilized as a compact, free-standing size reduction and reclaiming device at the location where the container is used. It uses neither a solvent nor a wash process and reclaims the oil in a suitable state for reprocessing. In a second method, a rinsing mechanism is employed by which a residual liquid waste, such as soap, may be concentrated and separated without introducing this residual liquid waste in dilute form into the waste water treatment process. A further method provides for the re-orientation of the granulated material so that complete removal of the liquid waste is achieved during the centrifugal process.

Description:
BACKGROUND 
     1. Field of the Invention 
     This invention provides a method of centrifugally separating residual oil or other liquid contamination from shredded or granulated containers used to package the oil or other liquid. In principle, the apparatus consists of a shredder or cutter assembly at the in-feed area which reduces the container to chips or shreds. The chips or shreds are then fed into a centrifugal device which separates the oil (or other liquid) from the container material. The separated liquid is subsequently drained through a series of filters into a holding tank, while the chipped or shredded container material is discharged into a holding vessel. 
     With an understanding of the present need to protect both our natural environment and to optimize the use of natural resources, the importance of this apparatus should be readily apparent. In a first case, a mechanical separation of the residual liquid (most notably, motor oil) from its chipped or shredded container assures less pollutants introduced into the waste stream from cleaning operations in the form of an emulsion of water, detergents, and the specific material in the container. In a second case, a mechanical separation assures a greater return of product into its highest value usage with the least energy expended; that is, motor oil may be recovered in the form of pure motor oil rather than as an emulsion which requires expensive reprocessing for commercial reuse. 
     BACKGROUND 
     2. DESCRIPTION OF THE PRIOR ART 
     The technology of centrifugally separating residual liquid which was packaged within a container from the material proper of said container subsequent to shredding or comminution of the container has not heretofore been addressed in any patent available at the time of this application. This is particularly true of plastic containers in the form of blow molded bottles which have contained motor oils or similar non-water soluble liquids. 
     A new body of technology is growing for the purpose of reclaiming such plastic and other container materials. In most cases, however, the technology has used mechanical agitation in conjunction with washing and soaking bathes to remove said contaminant from the chipped or shredded container. 
     Centrifugal separation of a residual liquid contaminant of a container, and the shredded material proper from said container, is a novel innovation as suggested in this invention. 
     However, note must be taken of an older technology which uses centrifugal mechanical separation of cutting fluids and oils from metal chips, borings, and the like as encountered in machine shop operations. In this regard, the patents of Dudley et al. (U.S. Pat. Nos. 4,137,176 and 4,253,960), Areaux et al. (U.S. Pat. No. 4,186,096), Weininger et al. (U.S. Pat. No. 4,122,014), Steimel (U.S. Pat. No. 3,366,318), and Ziherl (U.S. Pat. No. 2,878,943) deserve attention. (Note that the two patents of Dudley and the patent of Areaux are refinements of the same practice.) 
     In reviewing the prior art, it is apparent that Dudley and Areaux (U.S. Pat. Nos. 4,137,176, 4,253,960, and 4,186,096) have devised a technology which is continuous. Furthermore, the above mentioned art loads the material at the bottom of the rotating sieve, and discharges it at the top. Whereas the present invention uses a batch process where the material is held within the rotating sieve throughout a single process run. The present invention further loads the material from the top of the rotating sieve and discharges it from the bottom with the aid of a dumping mechanism. 
     Ziherl (U.S. Pat. No. 2,878,943) is similar to Dudley and Areaux in that his process is continuous and the liquid discharge is at the top. However, Ziherl discharges the solid material at the bottom. Nonetheless, as regards the present invention, the differences between Ziherl and Dudley and Areaux are inconsequential. Refer to the arguments above as to the differences between the present invention and Dudley and Areaux as being similar to the differences between the present invention and Ziherl. 
     Weininger et al. (U.S. Pat. No. 4,122,014) must be reviewed because of certain apparent similarities with the present invention. Weininger is both a batch process, and feeds the material into the top, and discharges from the bottom, of the rotating sieve. However, as can readily be seen, Weininger primarily teaches the use of a moving distributing plate which in no way anticipates the unique claims of this invention. Nor, does Weininger anticipate the bottom dumping mechanism as developed in this invention. 
     OBJECTIVES OF THE INVENTION 
     This invention was developed with an understanding of the limitations of the present methodology used to dispose of, or reclaim containers with residual liquid waste (most notably plastic oil filled containers). Furthermore, it was designed with a number of other objectives considering its potential application. 
     1. It is the general objective of this invention to provide a means of mechanically separating residual liquid waste (motor oil) contamination from a chipped or shredded, plastic container. 
     2. Another objective of this invention is to remove said residual liquid waste (motor oil) without creating an emulsion by the addition of water or other chemicals. 
     3. Another objective of this invention is to salvage said residual liquid waste (motor oil) in a usable form for further use without significant product down-grading. 
     4. Another objective of this invention is to separate the residual liquid waste (motor oil) or other contaminant from the plastic product without introducing that contaminant into the waste water stream. 
     5. Another objective of this invention is to provide a compact and efficient unit which could be used in an automotive service station or the like. 
     6. Another objective of this invention is to provide an embodiment of the invention which may be used on a larger scale in a plastic reprocessing plant to separate residual liquid waste (motor oil or other liquid contaminants) from the plastic to be reprocessed. 
     7. A final objective of this invention is to utilize the technology of two previous patent applications to this oil separation methodology. That is, the application entitled CUTTER ENHANCEMENT FOR PLASTIC SIZE REDUCTION EQUIPMENT, Ser. No. 07/595,258, now U.S. Pat. No. 5,110,060 and the application entitled SECONDARY CUTTER APPARATUS FOR PLASTIC SIZE REDUCTION EQUIPMENT, Ser. No. 07/667677 now U.S. Pat. No. 5,143,307 and also U.S. Pat. No. 5,149,424. 
     These and other objectives and advantages of the present invention, and the manner in which they are achieved, will become apparent in the following specifications and claims. 
     SUMMARY OF THE INVENTION 
     In its preferred embodiment, the present invention is a centrifuge device for the purpose of separating chips or shreds of containers from whatever liquid residue remains within said containers. Though this technology is suitable to many diverse applications, one of its primary functions is the separation of the recyclable plastic contained in a motor oil container from the remaining re-usable motor oil within said container after the container has ostensibly been emptied. It is an objective to accomplish this in an economically advantageous manner which uses neither a solvent nor a wash process, and which reclaims the oil in a suitable form for reprocessing. 
     In its preferred embodiment, the present invention may be utilized in at least two primary applications. As a compact, free-standing unit, said invention may be used as a size reduction and reclaiming device at the location where the container is used. Such would be the case in automotive service stations, retail outlets, and the like where the end-user of motor oil products is required to properly dispose of the empty containers in an environmentally prudent manner. In a second application, production units may be used in plastic reclaiming plants where large quantities of a given plastic container are being centrally processed. (Chipping or shredding of the container may take place in a location distant from the centrifugal unit in this latter application.) In this case, not only does the device keep the separated liquid from the waste water treatment stream, it separates it while it is still in a salable form to oil recovery processing plants. 
     This invention operates as a batch process apparatus. In the preferred embodiment, a source of container chips or shreds from an appropriate cutter head is fed into the stationary or partially revolving rotating sieve. During the interval wherein the rotating sieve is being loaded, and subsequently during the duration of the centrifugal process, a discharge door which is located on the bottom of said rotating sieve is in the closed position. Thus, the rotating sieve can be driven at high enough angular rotation speed so that the residual liquid waste contaminant is thrown from the material and through the sieve screening. 
     By means of an appropriately designed slinger arrangement on the rotating sieve, working in unison with the configuration of the liquid waste containment housing, the residual liquid waste material (notably motor oil) is slung against the inside wall of said containment housing and filtered and pumped into a collection vessel. Air blast means are provided for tumbling (re-orienting) the chips or shreds during the process which will expose all surfaces of said chips or shreds to the centrifugal action. 
     In yet another application, a solvent may be injected into the rotating sieve during high speed operation. In so doing, the contaminant is removed from the chip or shred material at a high concentration level. In this manner, the centrifugal process of this invention alleviates the need of reclaiming the soluble and solid materials from large volumes of waste water such as are encountered with a typical wash process. Plastic detergent bottles and the like are examples of plastic container materials which are encountered in this latter process. Initial removal of residual soap is done centrifugally to remove the soap in high concentration levels prior to subsequent washing processes which put the remainder of the soap into the waste water stream at a low level of concentration. 
     At the termination point of the separation process, the rotating sieve is slowed or stopped and the discharge door is opened. The liquid-free material (notably plastic container chips or shreds) are then emptied into the receiver vessel for subsequent reclamation processing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a sectional view of the centrifuge and cutter head. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     To simplify the description, symmetrical parts, or portions of a single part where divided by a sectional view, will be designated with a prime (&#39;). The description of the part(s) having primed reference characters will be limited to a minimum. 
     Referring now to FIG. 1, the concept of the preferred embodiment is shown in a sectional assembly view. The entire apparatus is comprised of two sub-assemblies. At the top of the unit a shredding or granulating sub-assembly is provided such as illustrated by the cutter head 1. (This is the assembly described in the application entitled CUTTER ENHANCEMENT FOR PLASTIC SIZE REDUCTION EQUIPMENT, Ser. No. 07/595,258 now U.S. Pat. No. 5,110,060 and the application entitled SECONDARY CUTTER APPARATUS FOR PLASTIC SIZE REDUCTION EQUIPMENT, Ser. No. 07/667677 now U.S. Pat. No. 5,143,307.) Oil, or other liquid contaminated containers are fed into the cutter head 1 for reduction into chips or shreds as indicated by 2. Said chips or shreds 2 are conveyed by means of a guide chute 3 to the chute discharge 4 and into the centrifugal separation sub-assembly. 
     The centrifugal separation sub-assembly comprises components including a rotating sieve 5 where the residual liquid waste component is separated from the container chips or shreds 2, a liquid waste containment housing 6 where the residual liquid waste is entrapped, and the receiver vessel 7 where the liquid-free chip or shred material is collected. 
     The rotating sieve 5 assembly consists of a central shaft 8 to which a top 9 and bottom 10 sieve support structure is attached. The top sieve support 9 is formed with an airfoil as shown at 11 which carries the material from the chute discharge 4 into the rotating sieve screen 12 area. The direction of rotation of the rotating sieve 5 as indicated by arrow 13 is established such that the airfoil 11 of the top sieve support 9 forces the material in this said downward direction. Said top and bottom sieve support structures are affixed at their outer periphery to a top 14 and bottom 15 sieve bell which is in each case formed of an impervious metal sheet. An annular top 16 and bottom 17 slinger ring directs the flow of the residual liquid waste into the liquid waste containment housing 6. 
     The rotating sieve 5 assembly further consists of a discharge door 18 which, in the closed position (shown as 18&#39;) seals against the open area of the bottom sieve bell 15 providing a closed container in which the process material is held. In the opened position (as indicated by 18) said discharge door is sufficiently withdrawn from the bottom sieve bell 15 that material may be emptied from the stationary rotating sieve 5 as indicated by arrow 19. Said discharge door is provided with a sieve baffle 20 which directs the material away from the discharge door 18 for complete emptying of the processed chip or shred material. 
     Finally, the rotating sieve 5 assembly is positioned within the apparatus by means of anti-friction bearings 21 mounted between the shaft 8 and the main support structure (not shown) of the unit. A shaft slinger 22 prevents chip or shred material from passing the point of shaft 8 entrance into the receiver vessel 7. 
     The liquid waste containment housing 6 consists of a circumferential enclosure surrounding the rotating sieve 5, with the rotating sieve slinger rings (16 and 17) contained within said containment housing. In the preferred embodiment, the containment housing 6 has an outer wall 23 which intersects with a containment housing bottom 24 forming an acute angle collection area 25 wherein the residual liquid waste accumulates. At some point on the periphery of the containment housing 6, said collection area 25 is tapped with a drain pipe 26. In the preferred embodiment, the residual liquid waste (such as motor oil) is directed from the drain pipe 26 through a wye strainer 27 into a motor driven fluid pump 28 and subsequently pumped through a fine filtration media filter 29 (generally of the spin-on cartridge type) and out the discharge pipe as indicated at 30 to a holding vessel which is not shown. 
     The containment housing 6 may further incorporate a series of radially mounted vertical baffles 31 which cause the liquid thrown from the rotating sieve 5 to flow downward by gravity to the collection area 25 at the base of said containment housing. 
     The receiver vessel 7 sub-assembly is essentially a receiving vessel for the chipped or shredded material as well as being the structural member for the completed assembly. A screen floor 32 with a drain pan 33 is provided on the bottom of said receiver vessel to trap any residual liquid waste which might inadvertently enter the chip or shred receiving area. Some discharge means (which is not shown) would normally be provided from the drain pan 33 to the drain pipe 26 so that residual liquid waste in this area could also be filtered and salvaged. 
     In some embodiments, an auger 34 discharge is provided integrally within the receiver vessel 7 to convey cleaned shred or chip material to either a bagging device or to a subsequent part of an in-plant process. 
     OPERATION 
     In all embodiments, some means of delivering chips or shreds 2 to the guide chute 3 is achieved. In an embodiment for use in such locations as an automotive service station and the like, the chips or shreds 2 would be generated within the same assembly from a cutter head 1. (In an industrial setting, the chips or shreds may be generated remotely from the centrifuge unit and conveyed to it for processing.) For ease of description in the following embodiments, unless specifically required to identify otherwise, the source of chips or shreds 2 will be described as coming from a cutter head 1 which is integral to the assembly. 
     Chips or shreds 2 contaminated with a residual liquid waste material (notably motor oil) are delivered into the guide chute 3, and are thereafter discharged into the rotating sieve 5 as indicated at 4. However, because this apparatus functions as a batch processes, the discharge from the cutter head 1 will be interrupted when the rotating sieve 5 is processing. Because further liquid contamination of the batch would ensue, a guide chute shutter 35 is used to prevent contamination of the batch. (This same guide chute shutter 35 allows the cutter head 1 to discharge material before coming to a complete rest.) 
     Material delivery of chips or shreds 2 into the rotating sieve 5 may be done with said rotating sieve either stationary or in motion. It is the purpose of the airfoil 11 on the top sieve support 9 to guide the chips or shreds 2 into said rotating sieve while it is in motion. The air movement created by the airfoil 11 in cooperation with the natural air flow through the sieve screen 12 also moves the material into a process position as well as aids in carrying the residual liquid waste from the chips or shreds 2 into the liquid waste containment housing 6. 
     During the centrifugal process, it may be necessary to tumble the chips or shreds 2 so that they re-orient, allowing the residual liquid waste to be stripped from all surfaces of said chips or shreds. An air blast bar 36 is provided which periodically reverse-pulses air into the screen as indicated by the arrows 37. Said air blast will continue at intervals throughout the process as required to achieve chips or shreds 2 free of residual liquid waste contamination. In some cases, said air blast may coincide with a deceleration of the rotation speed of the rotating sieve 5 to allow greater tumbling action of the chips or shreds 2. 
     The top 16 and bottom 17 slinger rings, which are immediately adjacent to the upper and lower extremities of the rotating sieve screen 12, guide the residual liquid waste into the liquid waste containment housing 6 and its baffles 31, preventing said liquid from being thrown out of the area adjacent to the guide chute 3 or inadvertently contaminating the material in the receiver vessel 7. 
     In an embodiment of the apparatus of this invention which is more typically used in plant processing, a solvent spray may be used to wash the residual liquid waste contaminant from the chips or shreds 2 during the centrifugal process. In this embodiment, a spray head 38 is so mounted that the solvent may be directed against the inside of the load. 
     The advantage of a solvent spray during the process is realized in the removal of the soluble liquid contaminant at high concentration levels. This alleviates a low concentration contamination of subsequent wash cycle solvents (typically water) which must be treated in large volume to remove said contaminant. This is evident with such waste materials as soap (as will be found when reprocessing soap and detergent bottles) and the like, wherein a concentrated soap solution can be removed with the spraying action. 
     As a further refinement of said spraying process, the drain pipe 26 may be diverted for multiple stage rinsing. That is, a first light rinse may be used to remove a high concentration of waste material, which would be processed in its concentrated form. Subsequent rinses may consist of heavy usage of the rinse solvent (most likely water) being diverted to the main waste water stream. As a further aid to increasing the concentration of the first rinse, the solvent may be recirculated from the drain pipe 26 back into the spray head 38 for a predetermined period of time. 
     Within the liquid waste containment housing 6 are a series of vertical baffles 31 radially located around the interior periphery of said housing. The baffles 31 reduce the swirl of the air/oil (or other residual liquid waste) entrainment and thus aid the dispersion of said liquid to the collection area 25 of the containment housing 6. To further augment the dissipation of the air velocity within the containment housing 6 an air exhaust stack 39 is provided which allows the escape of the air moving at high velocity and separates the residual liquid waste allowing it to return to the collection area 25. 
     The discharge door 18 consists of multiple elements. The discharge door 18 proper consists of an impervious material so that residual liquid waste cannot enter the receiver vessel 7. However, said door is so mounted that the portion closest to the shaft forms a catch basin 40 (by forming an acute angle between the plane of the shaft 8 and the discharge door 18) for residual liquid waste which will drain into it through the sieve baffle 20 when the rotating sieve 5 is stationary. Inasmuch as a leak-free seal area 41 is provided between the closed discharge door 18 and the bottom sieve bell 15, residual liquid waste which has drained into the catch basin 40 will be carried up the slope of the discharge door 18, through the sieve baffle 20, over the seal area 41, across the bottom sieve bell 15, and through the sieve screen 12 for eventual discharge during the centrifugal process. 
     The function of the sieve baffle 20 becomes evident, however, when the discharge door is opened as indicated by arrow 42. For the material to properly discharge from the stationary rotating sieve 5 as indicated by arrow 19, it is necessary for it to pass over an obtuse angle (as formed by the sieve baffle 20 in relationship to the shaft 8). 
     The discharge door 18 has a central hollow mounting tube 43 which moves vertically on the shaft 8. It further has a spring loaded compressive means 44 which forces said door assembly shut against the seal area 41. Not shown, but indicated by the arrow 42 is an opening mechanism for the discharge sequence. 
     Pertinent functions of the receiver vessel 7 and the auger 34 have already been described in a previous section. 
     Of necessity, this apparatus will include a drive means consisting of an electric motor or other motive device which is not shown. Said motor drive would be coupled to the shaft 8 at an appropriate location. In addition, control and timing devices are also incorporated into the design of this apparatus which are outside of the concern of these particular specifications. 
     Centrifugal testing has been conducted to determine the ideal angular velocity for the apparatus. The tests were done with high density polyethylene (HDPE) oil container material contaminated with 30-weight viscosity motor oil. It was determined that acceptable stripping of the oil from the plastic commences at a centrifugal force proportional to an acceleration of 330 g. It was also determined that performance of the apparatus is improved as the angular velocity is increased. A range of tests were conducted to a centrifugal force upper limit proportional to an acceleration of 1,225 g. (Speed tests higher than this were deemed unadvisable for safety and mechanical considerations.) Required process dwell time is reduced proportionately as the higher radial forces are applied. 
     While the present invention has been described in conjunction with a single centrifugal embodiment, (through comprising two diverse applications) it is to be understood that various modifications and other embodiments of the present invention may be made without departing from the scope of the invention as described herein and as claimed in the appended claims. 
     The embodiments of the invention in which an exclusive property or privilege is claimed are defined below.