BELT WASHER

Abstract: A conveyor belt washer comprises a plurality of nozzles (12) for ejecting water jets towards an upper side of a foraminous conveyor belt (5). A tank (2) is positioned under the foraminous conveyor belt for receiving water ejected from said nozzles, said tank having a foraminous top side (17) for separating particles accompanying said water, an outlet opening (16) in a lower part (9) thereof and a ventilating opening in an upper part (8) thereof. The conveyor belt washer further comprises a pump (24) having an inlet and an outlet (29), and pipings (27, 28) connecting said outlet opening of the tank to said inlet of the pump, and said outlet of the pump to said plurality of nozzles, such that the water is recirculated and air entrained by the water through the foraminous top side of the tank escapes through the ventilating opening thereof.

Description: BELT WASHER The present invention relates to a conveyor belt washer for cleaning a foraminous conveyor belt. In the food industry, belt conveyors are used for the transportation of food during processing thereof or between separate processing units. This often results in a buildup of food debris and processing media on the conveyor belt, requiring repeated cleaning. Thorough cleaning of the foraminous conveyor belt with water requires high-pressure water jets which pro- duce splashing water and render the separation of water from food debris difficult. Also, when recirculating the water, air entrained by the water jets causes cavitation in a pump used for producing the high-pressure water jets. Therefore, one object of the present invention is to provide a conveyor belt washer which eliminates cavi¬ tation in the pump for recirculating the water to pro¬ duce the high-pressure water jets. Another object of the present invention is to pro- vide a conveyor belt washer capable of effective separa¬ tion of debris from the cleaning water. A further object of the present invention is to re¬ duce the splashing of water in a conveyor belt washer. According to the present invention, a conveyor belt washer comprises a plurality of nozzles for ejecting wa¬ ter jets towards an upper side of a foraminous conveyor belt; a tank positioned under the foraminous conveyor belt for receiving water ejected from said nozzles, said tank having a foraminous top side for separating partic- les accompanying said water, an outlet opening in a lower part thereof and a ventilating opening in an upper part thereof; a pump having an inlet and an outlet; and pipings connecting said outlet opening of the tank to said inlet of the pump, and said outlet of the pump to said plurality of nozzles, such that the water is recir¬ culated and air entrained by the water through the fo¬ raminous top side of the tank escapes through the venti- lating opening thereof. Preferably, the ventilating opening is positioned in the top side of the tank and outside the conveyor belt. Further, in a preferred embodiment, an upstanding channel connects or communicates with the ventilating opening. The foraminous top side of the tank comprises a filter screen, advantageously a 60 mesh screen having an open area of about 37%. In a preferred embodiment, the filter screen is mounted in a frame which forms a sepa- rate unit and is removable from the tank. In order to allow the conveyor belt to pass along a return path through the belt washer, the tank has an up¬ per compartment and a lower compartment interconnected by a vertical duct on one side of the conveyor belt, said outlet opening being positioned in the lower com¬ partment. The conveyor belt washer according to the invention further may comprise at least one air curtain after the nozzles in the direction of travel of the conveyor belt. The invention will be described in more detail be¬ low, reference being had to the accompanying drawings. Fig 1 is a front view of a preferred embodiment of a conveyor belt washer according to the present inven¬ tion. Fig 2 is a side view of a part of the conveyor belt washer shown in Fig 1. Fig 3 is a top view of a filter included in the conveyor belt washer shown in Figs 1 and 2. Fig 4 is a side view of the filter shown in Fig 3. Referring now to the drawings, a conveyor belt washer according to the present invention comprises a stand 1 for a tank 2, a spray head 3 and a fan 4. A fo¬ raminous conveyor belt 5 travels through the stand 1 along an upper belt path on rails 6. The belt 5 travels in the opposite direction through the stand 1 along a lower belt path on rails 7. In the lower belt path, the foraminous conveyor belt 5 is encompassed by the tank 2, which has an upper compartment 8 and a lower compartment 9 interconnected by a duct 10 outside the foraminous conveyor belt 5 in the lower belt path. A tubular spray head 11 is mounted in the stand 1 above the foraminous conveyor belt 5 in its upper belt path. The spray head 11 extends over the full width of the foraminous conveyor belt 5 in its upper belt path and has a plurality of nozzles 12 communicating with the interior of the spray head 11 and directed towards an upper side of the foraminous conveyor belt 5 in its up¬ per belt path. The fan 4 is driven by a fan motor 13 and has a funnel-shaped inlet 14 of circular cross-section, and a funnel-shaped outlet 15 of rectangular cross-section which forms a splash guard. The opening of the fan out¬ let 15 is directed towards the upper side of the forami¬ nous conveyor belt 5 in its upper path. Also, the fan outlet 15 extends over the full width of the foraminous conveyor belt and is positioned after the spray head 11 in the direction of travel of the foraminous conveyor belt 5 in its upper path. The lower compartment 9 of the tank 2 is completely closed, except for an outlet opening 16 in its side op- posite to its connection with the duct 10. The top side of the upper compartment 8 is forami¬ nous. More precisely, the top side of the upper compart¬ ment 8 is covered by a filter screen 17 mounted in a rectangular frame 18. This frame 18 is slideably re- ceived on top of the upper compartment 8 and is, in ope¬ ration of the conveyor belt washer, fixed by a beam 19 at the end of the upper compartment 8 opposite to the duct 10, and by locking pins 20 at the external side of the duct 10. As shown in Fig 3, the filter screen 17 may consist of an upper screen and a lower screen in contact with each other. In a preferred embodiment, the upper screen consists of a 60 mesh screen having an open area of about 37%, and the lower screen consists of a 10 mesh screen having an open area of about 56%. In that part of the frame 18 which extends outside the foraminous con¬ veyor belt 5 in its upper path, there is a ventilating opening 21 formed in a plate 22. A vertical channel 23 connects with the ventilating opening 21 and is fixed to the plate 22. A pump 24 is positioned outside a separation wall 25 and has a pump motor 26. Pipings 27, 28 connect the outlet opening 16 of the lower compartment 9 to an inlet of the pump 24 and also connect an outlet 29 of the pump 24 to the tubular spray head 3. The pump 24 is a heavy- duty pump capable of producing a pressure at the outlet 29 of at least 11 bar at a water feed rate of several hundred litres per minute. The duct 10 comprises a second filter screen 30 in the form of an open box positioned between the upper compartment 8 and the lower compartment 9. When the frame 18 is removed from the conveyor belt washer, the second filter screen 30 may be lifted up through the duct 10 for rinsing. In operation, water is recirculated by the pump 24 through the pipings 28 and the spray head 3 out of the nozzles 12, such that high-pressure water jets are di¬ rected towards the foraminous conveyor belt 5 in its up¬ per belt path and mechanically clean the belt 5. The re¬ latively tight filter screen 17 dissipates a major part of the energy of the water jets and prevents the water from bouncing off the bottom of the upper compartment 8. However, the water jets entrain huge amounts of air into the upper compartment 8. By the arrangement according to the present invention of a ventilating opening 21 in the upper part of the tank 2, these huge amounts of air are allowed to escape, such that the water will reach the outlet opening 16 in the lower compartment 9 in a slow and uniform travelling condition, entraining substan¬ tially no air. Thereby, any cavitation in the pump 24 is eliminated. The absence of air in the water reaching the outlet opening 16 thus is a consequence of the ventilat¬ ing opening 24 and the long distance between the outlet opening 16 and the filter screen 17. It should be noted that the filter screen 17 is self-cleaning. The self-cleaning mechanism employs water flowing in the opposite direction through the screen to float the debris away to a discharge area situated out¬ side the ventilating channel 23. It will be seen that the objects hereinbefore set forth may be attained. Since various modifications may be made to the above embodiment of the invention without departing from the scope thereof, it is intended that the above description and accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims: CLAIMS 1. A conveyor belt washer, comprising a plurality of nozzles (12) for ejecting water jets towards an upper side of a foraminous conveyor belt (5) ; a tank (2) positioned under the foraminous conveyor belt for receiving water ejected from said nozzles, said tank having a foraminous top side (17) for separating partic¬ les accompanying said water, an outlet opening (16) in a lower part (9) thereof and a ventilating opening (21) in an upper part (8) thereof; a pump (24) having an inlet and an outlet (29) ; and pipings (27, 28) connecting said outlet opening of the tank to said inlet of the pump, and said outlet of the pump to said plurality of nozzles, such that the wa- ter is recirculated and air entrained by the water through the foraminous top side of the tank escapes through the ventilating opening thereof. 2. A conveyor belt washer as claimed in claim 1, wherein the ventilating opening (21) is positioned in the top side of the tank (2) . 3. A conveyor belt washer as claimed in claim 2, wherein the ventilating opening (21) is positioned out¬ side the conveyor belt (5) . 4. A conveyor belt washer as claimed in claim 3, wherein the ventilating opening (21) connects with an upstanding channel (23) . 5. A conveyor belt washer as claimed in claim 1 or 2, wherein the foraminous top side of the tank (2) com¬ prises a filter screen (17) . 6. A conveyor belt washer as claimed in claim 5, wherein the filter screen (17) comprises a 60-mesh screen having an open area of about 37%. 7. A conveyor belt washer as claimed in claim 1 or 2, wherein the tank (12) has an upper compartment (8) and a lower compartment (9) interconnected by a vertical duct (10) on one side of the conveyor belt (5) , said outlet opening (16) being positioned in the lower com¬ partment (9) . 8. A conveyor belt washer as claimed in claim 1, further comprising means (4, 15) for establishing at least one air curtain after the nozzles (12) in the di¬ rection of travel of the conveyor belt (5) . 9. A conveyor belt as claimed in claim 1, further comprising a splash guard (15) on the top side of the tank (4) and after the nozzles (12) in the direction of travel of the conveyor belt (5) . 10. A conveyor belt washer as claimed in claim 1, wherein the nozzles (12) are positioned in a row across the width of the conveyor belt. 11. A conveyor belt washer as claimed in claim 5, wherein the filter screen (17) is mounted in a frame (18) which is removable from the tank (2) . 12. A conveyor belt washer as claimed in claim 7, further comprising a removable filter screen (30) in said vertical duct (10) .

Inventors: HOCKER JON A, HOGAN DONALD L, MALMBERG JONNY, STRONG JOHN R, HOCKER, JON, A., HOGAN, DONALD, L., MALMBERG, JONNY, STRONG, JOHN, R.
Applicants: FRIGOSCANDIA FOOD PROCESS SYST, HOCKER JON A, HOGAN DONALD L, MALMBERG JONNY, STRONG JOHN R, FRIGOSCANDIA FOOD PROCESS SYSTEMS AB
Application year: 1992
Main classification: B65G45
IPC codes: B08B3, B65G45