Patent Publication Number: US-5423431-A

Title: Method and an apparatus for waste handling

Description:
The present invention relates to a method and an apparatus waste handling especially for sorting waste. 
     Steadily growing awareness is being paid to industrial and domestic waste, and considerable efforts have been made and are being made to process such waste in the best possible manner, inter alia to prevent injurious effects, to simplify handling of the waste and, as far as possible, to utilize the resource which such waste constitutes. 
     As a rule, waste from different collection points is allowed to be mixed and conveyed in common transport containers to plants for the separation of the waste or its deposition. Since the waste is allowed to become mixed on the way to the separation plants, the plants are supplied with a mixture of waste from which it is difficult to separate those fractions of the waste which allow for recovery and recycling. A number of experiments have been carried out in dividing up the waste at the source (sorting at source), but such experiments have not generally proved successful, because households lack the incentive to effect such sorting, because many households perceive the sorting and storage of separated waste as unpleasant, and because most buildings lack the space for storing of separated waste. The costs for transport of waste to its final deposition or to plants for the storage of separated waste also increase the sorting at the source, since such transports must be effected with the waste placed in separate containers. In turn, this requirement implies that the refuse collection vehicles must either be fitted with more than one collection receptacle, or that the refuse collection vehicles only collect one type of waste on each separate occasion. 
     An analysis of the composition of domestic waste and of the problems inherent in sorting the waste in the sorting plants shows that a sorting of the waste at the source into a wet fraction and a dry fraction entails considerable rationalization of the subsequent handling of the waste in the sorting plants, on condition that the waste sorted at the source can be transported to the sorting plants without the two fractions becoming intermixed. For economical reasons, this transport should also be effected in transport containers which are common to the waste. 
     The solution to the above problems will be attained by means of a method and an apparatus according to the present invention. 
     One of the advantages attained by application of the present invention is that existing refuse chutes in buildings can be employed in their present state. No special devices are required at the refuse chutes, such as indication buttons which are to be pressed to indicate the type of waste in order thereby to actuate means in the refuse storage chamber which cater for displacement of the waste to waste containers which correspond to the operating button which has been pressed. Such equipment is relatively bulky, for which reason many of the refuse storage chambers currently in use would need to be enlarged, and in addition all hatches to the refuse chute apart from that hatch being used must be blocked as long as any hatch for a special refuse chute is in the open position. 
     Furthermore, the present invention entails that refuse compactor vehicles which are already in service can be employed in their present state. Hence, no modification of the vehicles such that they are provided with different compartments for different types of waste is necessary. This circumstance is of major economical advantage, since it is obvious that the refuse collection vehicle fitted with a plurality of compartments will, in principle, be more complicated, and in particular if it is to be possible that the waste is compacted in each compartment. Furthermore, it must be expected that only one of the compartments will be completely filled, while the rest will remain only partly filled, which results in an inefficient utilization of the transport capacity of the vehicle. 
     Those refuse bags or containers which were closed in the household, for example by knotting need not, in the application of the present invention, be handled manually in the sorting plants, which entails an improved standard of hygiene. Those containers distributed to households, as a rule refuse bags or sacks, are, in certain cases of a size which renders the containers unuseable or at least difficult to use for newspapers or large packaging or wrapping. As a result, the households will be more inclined to place such waste in special collection containers within or adjacent to the buildings. This in turn will lead to an increased recovery of paper waste. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The nature of the present invention and its aspects will be more readily understood from the following description relating thereto, with particular reference to appended FIG. 1. 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     FIG. 1, which illustrates a preferred embodiment of the present invention, shows a first conveyor or storage feeder 1, a second conveyor 2, a distribution conveyor 3, and an identification conveyor 4, unloading means 5, identification means 6, recording and control means 7, first and second detecting means 81, 82, respectively, and separating means 9. 
     In the figure, the storage feeder 1 is shown as a conveyor belt 14 on which, for instance, a refuse collection vehicle tips collected waste. This waste consists of small containers 100, 101, which will hereafter be referred to as bags. As a rule, the conveyor belt is recessed in a shaft which is defined by side walls 10 which terminate at the top by means of flared inwardly guiding surfaces 11. Only one such side wall is shown in the figure. A discharge opening 13 is provided at the discharge end 15 of the conveyor belt. 
     The second conveyor 2 is provided with an infeed portion 21 which is disposed in the region of the discharge opening 13. The conveyor also includes a discharge portion 22 and, in the embodiment illustrated in FIG. 1, the conveyor is provided with a conveyor belt 20. The discharge portion of the conveyor is, as a rule, located at a higher level than its infeed portion. 
     The discharge portion 22 of the second conveyor connects to the distribution conveyor 3 which is shown in the figure as a conveyor belt 30. The distribution conveyor has an infeed portion 31 and a discharge portion 32. The orientation of the second conveyor and the orientation of the distribution conveyor are interrelated such that, seen from above, the direction of displacement of the bags in the transitional region makes a relatively large angle, as a rule of the order of approx. 90°. 
     The discharge portion 32 of the distribution conveyor 3 connects to an infeed portion 41 of the identification conveyor 4. Also at this transitional region, the direction of displacement of the bags is, as a rule, changed relatively abruptly, as a rule by approx. 90°. The identification conveyor has a discharge portion 42. In the embodiment illustrated in FIG. 1, the distribution conveyor includes a conveyor belt 40. 
     The unloading means 5 is provided with an infeed portion 51 and a discharge portion 52. The discharge portion 42 of the identification conveyor connects to the infeed portion 51 of the unloading means. In FIG. 1, one embodiment of the discharge means is shown in which this comprises a conveyor belt 50 and a distribution device 53 which is disposed in association with the discharge portion in order to ensure that bags which leave the conveyor belt 50 from the one 55a or the other 55b edge area of the conveyor belt are separated from one another. The distribution device is shown with guide surfaces 54a, 54b disposed at an angle to one another and substantially immediately merging into one another along the upper edge of each respective guide surface. This edge is located substantially vertically beneath the centre line 56 of the conveyor belt 50. 
     Collection receptacles 110, 111 are disposed beneath the distribution device 53 for receiving bags which have left the conveyor belt 50 from its one 55a, or its other 55b edge region, respectively. 
     In the region of the identification conveyor, there is disposed at least one identification means 6 and at least one first detector means 81. The identification means includes the detector 60 and, as a rule a light source 61. In a preferred embodiment, the first detector means consists of an ultrasonic transmitter/ultrasonic receiver and is, in certain embodiments, placed upstream, while in other embodiments, downstream of the identification means 6. 
     The separating means 9 is disposed in the area of the discharge portion 42 of the identification conveyor and/or the infeed portion 51 of the unloading means, the separating means being switchable between at least two sorting positions. The separating means is provided with drive means 90 for switching of the separating means to its separating positions. In the illustrated embodiment, the separating means 9 is provided with an arm 91, which, through a shaft 92, is connected to the drive means 90. The shaft 92 is secured to the arm at its one end region 93 which is placed substantially in the area of the centre line 56 of the conveyor belt 50, and, as a rule, between the centre line and the one edge of the belt. The arm makes an oblique angle with the longitudinal axis of the conveyor belt and has, when it is located in the operative position, its opposing end region 94 located in the region of one of the opposite edges 55a, 55b of the conveyor belt 50. At that end region 93 which connects to the shaft 92, the arm is located more proximal to the discharge portion 52 of the unloading means than the opposing end region 94 thereof. In FIG. 1, the arm is shown as located above the conveyor belt 50 of the unloading means 5, but it will be obvious to one skilled in the art that in certain embodiments the separating means is disposed in association with the conveyor belt 40 of the identification conveyor 4 and, in this instance, is located downstream of the identification means 6, and, in embodiments including the first detector means 81, also downstream of the detector means. 
     In one embodiment of the present invention, a second detector device 82 is disposed in association with the separating means 9, In certain embodiments, said means is set to detect bags which are undergoing displacement past the separating means, while in other embodiments, said means is set to detect that a bag has passed the separating means. 
     The recording and control means 7 is connected, through a first signal transmission means 71, to the identification means 6, through a second signal transmission means 72 to the first detector means 81, through third and fourth signal transmission means 73, 74 to the separating means 9, and, through a fifth signal transmission means 75, to the second detector means 82. 
     When the present invention is put into practice, a first division of the waste is effected in that the waste is divided, for instance in the household, into at least two types of waste in which each type of waste is placed in a special container or bag 100, 101, which is designed specifically for the waste type in question. As a rule, the container is designed as a bag and is formed of flexible and strong material which, for example, makes it possible to close the bag by a knot. Practical experiments have shown that it is possible to combine flexibility and strength such that the bags are capable of withstanding those stresses to which they are subjected during their subsequent handling, including any possible compaction of waste in refuse collection vehicles. Hereinafter, the designation bag will be employed without implying any limitation, for the flexible containers. 
     Each bag is provided with at least one marking which indicates the type of waste for which the bag is intended. In certain embodiments this marking consists of a colour marking, for example a plurality of regions of the bag (or the whole bag) are of a predetermined colour and/or provided with special print, embossed printing may also be relevant, which indicates the waste type for which the bag is intended. In a simple embodiment of the present invention, markings are employed for but two types of waste, viz. one marking for &#34;wet&#34; waste and one marking for &#34;dry&#34; waste. For many reasons, it is desirable that also paper waste, for example newspaper waste, be sorted out from the waste at the source and, in a preferred embodiment of the present invention, the bags have consequently been dimensioned in terms of volume so as to render the deposition of newspapers therein difficult. In the employment of conveyor belts, the belts carry, in certain embodiments, a colour which corresponds to the colour marking of one of the bags. In embodiments in which, for instance, two different colours are employed to distinguish, from the set of bags, bags marked with these colours and separate from one another and from other bags, the colour of the belt is selected so as to deviate from the colours employed for both of the bag types. 
     The bags are thereafter placed in the refuse storage chamber of the building, for example are deposited in the refuse chute and are collected on the occasion of the normal refuse collection. Even if each bag contains a specific waste type, the bags are mixed together with one another and are transported to a sorting plant common to a plurality of households. In the plant, the bags are tipped onto the storage feeder 1 and are displaced thereby, via the discharge opening 13, to the second conveyor 2. As a rule, this operates at a higher displacement speed than the storage feeder 1, and in the illustrated embodiment it also inclines upwardly in the direction of movement of the bags. The level difference between the infeed portion and discharge portion of the second conveyor 2 implies a certain levelling out of the thickness of the layer of bags being displaced by the conveyor, in that the bags slide towards the conveyor belt 20 and when there is also a layer of bags lying on subjacent bags. Naturally, this sliding tendency is determined by the friction between the bags and the belt, mutually between the bags, and also by the inclination of the belt. However, it has proved appropriate in a preferred embodiment of the present invention to allow the bags generally to slide along the belt but provide the belt with guiding means (not shown in FIG. 1) which retard or prevent the sliding movement and carry the refuse bags on movement of the belt. It will hereby be possible to even out those bag accumulations which occasionally occur on the discharge of bags by the storage feeder. 
     It is obvious that when a refuse collection vehicle has emptied its load into the storage feeder, an excessively large accumulation of bags may occur at the infeed portion 21 of the second conveyor 2. Consequently, in certain embodiments of the present invention, there are provided in association with the infeed portion of the second conveyor, &#34;level guards&#34;, for example transmitters and receivers of infra red light which stop and start the movement of the conveyor belt 14 of the storage feeder 1 in accordance with the variations of the thickness of the bag layer in the region of the infeed portion 21 of the second conveyor. When the thickness of the layer exceeds a predetermined level, the conveyor belt of the storage feeder is stopped and when the thickness falls below a predetermined level, the belt is started. 
     Via the discharge portion 22 of the second conveyor, the bags are transferred to the distribution conveyor 3 which, as a rule, operates at a displacement speed which exceeds the displacement speed of the second conveyor. As a result of the angle which the two conveyors make in relation to one another, in combination with the difference in displacement speed, a further spread of the bags in their direction of displacement will take place on the distribution conveyor. From the discharge portion 32 of the distribution conveyor, the bags are fed to the identification conveyor 4 which, as a rule, works at a higher displacement speed than the distribution conveyor. As a result, the bags will be substantially aligned. It will be obvious to one skilled in the art that in certain embodiments of the present invention in which large volumes of bags are simultaneously fed to the storage feeder, problems may arise at the identification conveyor, because the bags are located too close to one another or abut against one another on the identification conveyor. It will further be obvious to one skilled in the art that, in certain embodiments of the present invention, both the number of conveyors preceding the identification conveyor and the speed changes at the transitions between the conveyors may be adapted in accordance with the relevant volume of bags supplied from the storage feeder on each occasion. 
     When the containers or bags pass the identification means 6, this identifies the marking or markings which indicate the type of waste for which the bag is intended and transmits, via the first signal transmission means 71, corresponding information to the recording and control means 7. Via signal transmission means (not shown), the recording and control means 7 receives information on the displacement speed of the conveyor belt 40 of the identification conveyor 4 and of the conveyor belt 50 of the unloading means. The recording and control means calculates the time which elapses for the displacement of the bag to the separating means 9 and ensures, via the signal transmission means 73, 74, that the obliquely inclined arm of the separating means is in a position which is adapted in correspondence to the marking of the bag. On occasions when the immediately preceding bag carries a marking corresponding to the same waste type as the actually relevant type, the recording and control means is, as a rule, operative solely to check that the orientation of the obliquely inclined arm 91 is the correct one. When the bag passes the separating means 9, it is moved by the obliquely inclined arm 91 towards one of the edge regions of the conveyor belt 50 of the unloading means 5. When the bag passes the discharge portion 52 of the conveyor belt, the bag falls down into one of the receptacles 110, 111. The obliquely inclined guide surfaces 54a, 54b of the distribution device 53 ensure that the bag is guided down into one of the receptacles 110, 111, even if the bag is located relatively close to the centre line 56 of the belt 50. 
     In a preferred embodiment, the first detector means 81 is disposed in the region of the identification means 6 in order to ensure the presence of bags 100, 101 in this region. Information hereon is transferred via the second signal transmission means 72 to the recording and control means 7. The first detector means 81 supplements the information from the identification means 6 and, in those embodiments of the present invention in which the detector means is included in the apparatus according to the invention, switching of the separating means 9 is, as a rule, effected based on the point in time of the identification by the detector means of the presence of a bag on the conveyor belt 40 of the identification conveyor 4. 
     In certain embodiments there is provided, in association with the separating means 9, means 82 which establishes when a bag passes the separating means, or that a bag has passed. This information is transferred via the fifth signal transmission means 75 to the recording and control means 7 which, thereafter, via the third transmission means 73, transmits a signal of the separating means for switching thereof if such switching is required, for displacement of a subsequent bag to the correct side of the conveyor belt 50. In certain embodiments, the separating means 9 is provided with means which establish the presence of a bag in the region of the separating means. According to a simple embodiment, such is effected in that the separating means registers that one or more bags abut against its obliquely inclined arm 91. Information hereon is transmitted to the recording and control means via the fourth signal transmission means 74. In certain cases the separating means 9 is operative so as to maintain its adjusted position as long as a bag is under displacement past the separating means, for example abuts against its obliquely inclined arm 91. In certain embodiments this function is attained in that the separating means is blocked against receipt of signals from the recording and control means 7 as long as the bag has not passed the separating means, while in other embodiments the separating means receives the signal but does not effectuate received information on switching until after the bag has passed. In certain embodiments, the separating means 9 includes means for registration and transmission of signals indicating the current position (location) of the separating means. 
     The first and second detector means 81, 82, respectively, are employed in certain embodiments to count the number of bags passing through the sorting plant. Since the identification means 6 only emits signals for bags marked for a certain type or types of waste, information will be received on the total number of bags only with the aid of signals from the detector means 81, 82, for example the signals from the first detector means 81. As a rule, the purpose of the recording and control means 7 is to execute the requisite storage of information about and calculation on the number of bags of a specific type of waste. 
     The present invention allows the sorting of bags (containers) of different sizes, shapes and weights. In certain embodiments it may be employed to sort out recoverable material, for example material which may be composted, glass, aluminum foil, etc. 
     The above detailed description has referred to but a limited number of embodiments of the present invention, but one skilled in the art will readily perceive that the present invention encompasses a large number of embodiments without departing from the spirit and scope of the appended claims.