WASTE PRODUCT FEEDER

Abstract: A waste product feeder for use in an incinerator plant includes a hopper 1 connected to a horizontal trough 3 in which there is a conveyor screw 2. The conveyor screw trans­ ports waste products from the hopper to a discharge 5. A scraper 9 connected to a rotary shaft 8 is located in the dis­ charge 5 and arranged to scrape or cut off waste products which have been transported to the discharge end of the conveyor screw at a predetermined rate.

Description: The present invention relates to a waste product or refuse feeder, e.g. for use in an incinerator plant and is concerned with that type of feeder which includes a hopper communicating with a trough and a substantially horizontal conveyor screw within the trough for transporting waste products from the hopper to a discharge area, a space being defined in the trough above the conveyor screw over its entire length. Figure 21 is a schematic side sectional view of a waste product feeder, on which the precharacterising portion of claim 1 is based, connected to an incinerator plant 7. The feeder includes a hopper 1 whose lower end is connected to a trough 3 in which there is a feed screw 2. Waste products are charged through the hopper 1 into the trough 3, are forced to move laterally, i.e. horizontally, by rotation of the screw 2 and are discharged from a discharge port 5. The discharge waste products 4 are charged through a chute into the incinerator and burned. In practice various kinds of waste products are introduced into such a waste product feeder so that controlling the quantity of the waste products discharged is very difficult. More specifically, when the waste products, which tend to be large or viscous, are forced by the screw 2 to the discharge port 5, they are cut off relatively smoothly at the lower portion of the leading end of the screw 2 but scarcely cut at all at the upper portion. As the waste products are successively forced toward the discharge port 5, those of them which have not been cut off accumulate and are compressed in the trough 3 above the leading end of the screw 2. As a result, a large mass 4' of waste products is formed which then drops into the incinerator 7. This causes a temporary lack of oxygen in the incinerator 7, resulting in incomplete combustion which causes smoke pollution. This applies particularly in the case of a fluidised-bed type incinerator since the burning speed of such an incinerator is extremely high and the quantity of air cannot be instantaneously controlled. US-A-3776150 discloses a waste product feeder having a rotatable scraper located in the discharge area at the end of the conveyor screw. In use, a substantial pressure differential is maintained between the ends of the screw conveyor. It is an object of the present invention to provide a waste product feeder of the type referred to above which can suitably retard the waste products to be discharged so that a predetermined quantity of the waste products is cut or scraped off. According to the present invention a waste product feeder of the type referred to above is characterised in that a rotatable scraper, opposed to but spaced from the end of the conveyor screw, is located in the discharge area and that the scraper, as it rotates, extends to a higher level than the conveyor screw so as to scrape away the waste products transported to the discharge end of the conveyor screw. The scraper preferably occupies a substantial proportion of the area of the waste product trough or channel and thus constitutes a blockage or restriction which retards the movement of the waste products and allows them to be suitably compressed by the conveyor screw. The scraper is rotated by any convenient motor and scrapes or cuts off waste products which can thus fall down in or otherwise pass through the discharge at a rate which is determined substantially only by the geometry of the scraper and its speed of rotation. It is preferred that guide means are situated in the trough above the discharge end of the conveyor screw arranged to guide the waste products transported by the screw towards the scraper. The guide means may constitute a single central guide connected to the roof of the trough or a guide occupying each upper corner of the trough. The scraper is carried by a rotatable shaft, which in use is connected to a motor, and this shaft may extend parallel to the axis of the conveyor screw or perpendicular to the axis of the conveyor screw and in the latter case the shaft may extend either horizontally or vertically. If the rotatable shaft extends parallel to the conveyor screw it may include one or more cutting blades which, in use, at least partially cut off the waste products of the discharge end of the conveyor screw. If the rotatable shaft is perpendicular to the conveyor screw the scraper may comprise one or more rectangular flat plates. Alternatively, it may comprise one or more twisted plates and if the rotatable shaft extends vertically the scraper may comprise a helical formation, e.g. a screw similar to that of the screw conveyor. Further features, details and advantages of the present invention will be apparent from the following description of certain preferred embodiments which is given by way of example with reference to the accompanying schematic drawings, in which: Figure 1 is a side sectional view of a first embodiment; Figure 2 is a front view of the scraper of Figure 1; Figure 3 is a side sectional view of a second embodiment; Figure 4 is a front view of the scraper of Figure 3; Figures 5 and 6 are front views of the scrapers of third and fourth embodiments of the invention; Figure 7 is a side sectional view of a fifth embodiment; Figure 8 is a side sectional view of a sixth embodiment; Figure 9 is a scrap plan view thereof; Figure 10 is a side sectional view of a seventh embodiment; Figure 11 is a scrap plan view thereof; Figure 12 is a side sectional view of an eighth embodiment; Figure 13 is a scrap plan view thereof; Figure 14 is a scrap plan view of a ninth embodiment; Figure 15 is a side sectional view of a tenth embodiment; Figure 16 is a scrap plan view thereof; Figure 17 is a side sectional view of an eleventh embodiment; Figure 18 is a side sectional view of a twelfth embodiment; and Figures 19 and 20 are transverse sectional views on the line Z-Z in Figure 18. The same numerals are used in all the Figures to designate the same components. Referring firstly to Figure 1, a rotary shaft 8 extends horizontally from outside the feeder into the discharge area 5 of the trough 3 at a height slightly above that of the axis of the screw conveyor 2. A scraper 9 is attached to the inner end of the shaft 8 and is opposed to but spaced from the end of the conveyor screw 2. In use, the screw 2 is rotated in the direction X by a motor (not shown) while the scraper 9 is rotated in the opposite direction Y by a further motor. As best seen in Figure 2, the scraper 9 comprises a pair of blades 10, each shaped somewhat like a bird's beak, which are curved in opposition to the direction Y and are symmetrical about the axis of the rotating shaft 8, i.e are angularly spaced apart by 180°. The waste products 4 are successively transported by the screw 2 along the trough 3 to the discharge and are continuously cut or scraped off at a predetermined rate by the rotation of the scraper 9. The scraper 9 is spaced from the discharge end of the screw 2 by a suitable distance which depends on the nature of the waste products so that an appropriate braking and squeezing action is applied to the waste products. The quantity of the waste products cut off at the discharge end of the screw 2 can thus be suitably controlled. The formation and growth of a body 4' of waste products (see Figure 21) is thus prevented so that incomplete combustion in the incinerator can be eliminated. The screw 2 and the scraper 9 may be rotated in the same direction but in this case it is preferable that the rotational speed of the scraper 9 is greater than that of the screw so shearing forces are readily produced between the waste products and the scraper 9. In the first embodiment, the rotating shaft 8 is above the screw shaft. The reason for this is that the blades 10 of the scraper 9 pass the upper portion of the discharge end of the screw 2 where the body 4' of waste products tends to form, so that the waste product body 4' can be efficiently cut off or scraped. If the blades 10 are sufficiently large, the shaft 8 may extend in line with the axis of the screw 2. Referring now to Figures 3 and 4, a scraper 9A is provided comprising a disk-shaped support plate 11 attached to the inner end of the shaft 8 at right angles thereto and provided with a pair of blades 12 whose edge is concave in the direction opposite to the direction of rotation of the supporting plate 11. This embodiment has the advantage over the first embodiment that the area of the waste products 4 to be scraped is increased. Figures 5 and 6 show alternative constructions of the scraper. The scraper 9B of Figure 5 has an elliptical support plate 11 in Figure 4. The scraper 9C has a support plate 11 whose shape is similar to that of the pair of blades 10 in Figure 2. The waste products 4 can thus be scraped both by the supporting plate 11 and the pair of blades 12. The fifth embodiment shown in Figure 7 has a scraper 9D which includes a support plate 11 similar to those shown in Figures 4,5 and 6. However, the surface of the support plate 11 of the scraper 9D is somewhat curved. As a result, the blades 12 of the fifth embodiment can scrape a larger area. The sixth embodiment shown in Figures 8 and 9 includes a scraper 9E mounted on a rotary shaft 8. The shaft 8 extends horizontally but perpendicular to the axis of a screw 2. The scraper comprises a pair of rectangular flat blades 13 carried by the rotating shaft 8. In the seventh embodiment shown in Figures 10 and 11 there is a pair of scrapers 9E disposed side by side on vertical shafts 8 which scrape the waste products 4 independently. In the eighth embodiment of Figures 12 and 13 there is a scraper 9T comprising a twisted or parthelical blade 14 carried by a shaft 8 mounted to rotate about a vertical axis. In the ninth embodiment of Figure 14 there is a pair of scrapers 9F mounted one above the other to rotate about horizontal axies which extend perpendicular to the axis of the screw In both the eighth and ninth embodiments the blade or blades 14 serve not only to scrape off waste products 4 but also to force the same downwardly. Figures 15 and 16 show the tenth embodiment which includes two scrapers 9G each comprising a pair of blades 14 similar in construction to that of the ninth embodiment which are attached to a rotary shaft 8. The ability of this construction to force the waste products downwardly is much better than that of the ninth embodiment. In the embodiment shown in Figure 17 there is a scraper 9H of screw construction comprising a helical blade 15 carried by a vertical rotary shaft 8. This embodiment can also ensure a positive scraping of the waste products 4 and forcing of them downwards. In the constructions shown in Figures 18 to 20 there are guide members 16 (see Figure 19) in the upper corners of the trough 3 (see Figure 19) or a single guide member 17 connected to and extending along the centre line of the upper wall of the trough 3 (see Figure 20). The guide member or members guide the waste products 4 during their transport by a screw 2 toward the scraper.

Claims: A waste product feeder including a hopper communicating with a trough (3), a substantially horizontal conveyor screw (2) within the trough for transporting waste products (4) from the hopper to a discharge area (5), a space being defined in the trough above the conveyor screw over its entire length, characterised in that a rotatable scraper (9), opposed to but spaced from the end of the conveyor screw, is located in the discharge area (5) and that the scraper, as it rotates, extends to a higher level than the conveyor screw (2) so as to scrape away the waste products transported to the discharge end of the conveyor screw. A feeder as claimed in claim 1, characterised by guide means (16;17) situated in the trough above the discharge end of the conveyor screw (2) and arranged to guide the waste products transported by the screw (2) towards the scraper (9). A feeder as claimed in claim 1 or claim 2, characterised in that the scraper (9) is carried by a rotatable shaft (8) which extends parallel to the axis of the conveyor screw (2). A feeder as claimed in claim 3, characterised in that the scraper (9) includes one or more blades (10) arranged to at least partially cut off the waste products at the discharge end of the conveyor screw. A feeder as claimed in claim 4, characterised in that the blades (10) extend outwardly from the shaft (8) and are curved rearwardly in the direction in which the shaft (8) is rotated. A feeder as claimed in claim 1 or claim 2, characterised in that the scraper (9) is carried by a rotatable shaft (8) which extends horizontally but perpendicular to the axis of the conveyor screw (2). A feeder as claimed in claim 1 or claim 2, characterised in that the scraper (9) is carried by a rotatable shaft (8) which extends vertically and perpendicular to the axis of the conveyor screw (2). A feeder as claimed in claim 6 or claim 7 characterised in that the scraper (9) comprises rectangular flat plates (13). A feeder as claimed in claim 6 or claim 7 characterised in that the scraper (9) comprises one or more twisted plates (14). A feeder as claimed in claim 7 characterised in that the scraper (9) comprises a helical formation (15).

Inventors: KIYOTOMO, MIKIO, NARISOKO, MINORU
Applicants: ISHIKAWAJIMA-HARIMA  JUKOGYO KABUSHIKI KAISHA
Application year: 1986
Main classification: F23G5
IPC codes: F23K3, F23G5, B65F5