WO2006080878A1

WO2006080878A1 - Dewatering of waste

Info

Publication number: WO2006080878A1
Application number: PCT/SE2006/000090
Authority: WO
Inventors: Christer Kihlström
Original assignee: Envac Centralsug Ab
Priority date: 2005-01-27
Filing date: 2006-01-20
Publication date: 2006-08-03
Also published as: KR20060086580A; CN101124132B; CN101124132A; EP1843956A4; EP1843956A1; KR101203878B1

Abstract

A method for providing an early separation and removal of a liquid content from waste that has been introduced into a waste chute (1) of a vacuum operated waste collection system, com- prises steps for temporarily supporting the introduced waste on a liquid-permeable member (11,12) at or upstream of a discharge valve (7) of the waste chute, and for separating, collecting and removing the liquid content by means of vacuum applied to the waste. This early separation and removal of the liquid content from the waste at the discharge valve not only secures the correct operation of the vacuum transport system but also takes considerable load off the discharge valve.

Description

TITLE: DEWATERING OF WASTE

TECHNICAL FIELD

The present invention relates generally to the dewatering of waste, and specifically relates to a method and a system for the dewatering of household and/or kitchen waste prior to the discharge thereof into a waste suction transport system.

BACKGROUND

It is known to employ vacuum operated systems for the collection and transport of refuse or waste from a number of insertion points to a central collecting station. In the most common applications such systems are used for collecting and transporting relatively dry household waste that is packed in bags. Examples of such general systems are disclosed in our earlier

International Patent Applications Nos. WO 02/102686 Al and WO 00/46130. However, in some geographical areas as well as in some applications it is desirable to use such systems also for the collection and transport of loose, i.e. unpacked, household waste and/or kitchen waste having a significant liquid content.

In the conventional system a relatively high liquid content of the waste would cause considerable problems, and would certainly increase the overall load put on the system and its sections and components. Specifically, a stronger vacuum would be required in order to secure an appropriate and efficient transport of such "wet" waste in the transport pipes or ducts of the system, and this would in turn increase the power consumption thereof. An additional problem encountered when handling such wet^{^}waste is that even with an increased vacuum level, the risk of blockage in or clogging of the transport system cannot be completely eliminated.

In most systems considerable quantities of waste may be collected and temporarily stored in the lower area of insertion chutes of the system, directly on top of a waste discharge valve. Such discharge valves are provided at the lower end of such chutes to control the discharge of the temporarily stored waste into the transport duct of the system. Such a temporary storage of waste having a considerable liquid content would put a very heavy load on the discharge valves. This would in turn cause an undesirable increase of the system maintenance and service costs. SUMMARY

The invention overcomes the above problems in an efficient and satisfactory manner.

It is a general object of the invention to provide a solution to the problem of handling waste having a considerable liquid content in a vacuum operated waste collection system. In particular, it is an object of the invention to provide a method of effectively separating the liquid content from waste introduced into such a system, thereby generally unloading the system as well as its components.

Briefly, the above object is achieved by arranging an early separation and removal of the liquid content from the waste. Specifically, this is accomplished by temporarily supporting the introduced waste on a liquid-permeable member at or upstream of a discharge valve, and by separating, collecting and removing the liquid content during said temporary support by means of vacuum applied to the waste. Accordingly, the invention provides a method where the early separation and removal of the liquid content from the waste at the discharge valve secures the correct operation of the vacuum transport system.

hi an embodiment of the invention, the steps of temporary supporting the waste as well as of separating and collecting the liquid content are all integrated in the discharge valve, thereby providing for a very easily controlled and thus efficient method.

hi a further embodiment of the invention, the temporary support of the waste as well as the separation and collection of the liquid content is performed by means of the liquid permeable upper member- and a lower, generally concave member,^" together forming a pivotal valve member of the discharge valve, whereby the dewatered waste is discharged into the waste transport system by pivoting said valve member to an open position.

Another object of the invention is to provide a waste dewatering system intended for use in vacuum operated waste collection systems and allowing for the introduction of wet waste into such systems without unduly loading said systems or components thereof.

This further object is achieved by means of a waste dewatering system having a waste dewatering means consisting of an upper liquid permeable member for temporarily supporting the introduced waste, a collecting member for collecting liquid content separated from the introduced waste, a vacuum source connected to said collecting means and a fluid line for applying said vacuum and for removing said separated liquid content.

These and further objects of the invention are met by the invention as defined in the appended patent claims.

Advantages offered by the present invention, in addition to those described above, will be readily appreciated upon reading the below detailed description of embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with further objects and advantages thereof, may best be understood by referring to the following description taken together with the accompanying drawings, in which:

Fig. 1 is a partly schematical illustration of an embodiment of the waste dewatering system of the invention as applied to a known, separate waste insertion chute;

Fig. 2 A is a partly sectioned side view of a waste discharge valve flap of the waste insertion chute of Fig. 1, having integrated waste dewatering means;

Fig. 2B is a top plan view of the waste discharge valve flap of Fig. 2 A;

Fig. 2C is an exploded perspective view of the waste discharge valve flap of Figs. 2A and B;

Fig. 3 A is a schematic view of the waste dewatering system of Fig. 1, in a first vacuum application phase of the waste dewatering process of the invention;

Fig. 3B is a schematic view of the waste dewatering system of Fig. 1, in a second drainage phase of the waste dewatering process of the invention;

Fig. 3 C is a schematic view of the waste dewatering system of Fig. 1, in third and fourth liquid discharge phases of the waste dewatering process of the invention; and

Fig. 4 schematically illustrates an exemplifying embodiment of a method according to the invention, for dewatering collected waste. DETAILED DESCRIPTION

The invention will now be explained with reference to exemplifying embodiments of the inventive system and method, respectively, which are illustrated in the drawing figures. The illustrated, exemplifying embodiments relate to an application of the inventive solution to a type of free-standing separate waste insertion chute that is disclosed in our earlier International Patent Application WO 02/102686 Al. However, it shall be emphasized that the invention is in no way restricted to such an application.

Fig. 1 schematically illustrates a separate insertion chute 1 of the type that was referred to above and that is part of a vacuum operated refuse collection system of a general kind where the invention may advantageously be employed. In such a system, such as the one that is described further in said WO 02/102686 Al, separate insertion chutes 1 are connected to a transport pipe or duct 2. The insertion chute 1 illustrated in Fig. 1 consists of an upper chute portion 3 and a lower chute portion 4 that are connected to each other through an interface (not illustrated). The upper chute portion 3 has a waste insertion opening 5 and an upper waste channel 3 A, both very schematically illustrated, for connection to a corresponding lower waste channel 4A in the lower chute portion 4. The lower chute portion 4, which is normally positioned under the ground level G or below a floor F of a building, is received in a branching 6 of the transport pipe 2. For further details of the exemplifying embodiment of the insertion chute as such, we refer to the above mentioned International Patent Application.

The lower chute portion 4 is further provided with a chute discharge valve 7. Said valve 7 is basically of a conventional flap type having a flap 8 that through Support arms 7A is pivotally supported for pivoting about an axis PA, which is fixed relative to the lower chute portion 4. In a closed position, see fig. 3 A, the flap 8 sealingly engages a valve seat 4B at a lower end of the lower chute portion 4 and in an open position it allows free passage of waste from the lower waste channel 4A and into the transport pipe 2. Movement of the valve flap 8 between open and closed positions is controlled by means of an operating means 10, here a fluid cylinder, through a transmission that is not specifically illustrated.

In contrast to the conventional flap type valve, for the purposes of the present invention, the discharge valve flap 8 is here provided with a waste dewatering means 9 forming a double wall structure of the flap 8, as will be explained with specific reference to Figs 2A-C. Said waste dewatering means 9 consists of a first upper liquid-permeable waste support and liquid drainage section or member 11, 12 and a second lower collecting section or member 18. The first upper section 11, 12 of the dewatering means 9 is formed by a perforated and thus liquid-permeable area 12 of the flap 8 of the chute discharge valve 7 and a separate, liquid-permeable line mesh filter material 11. The second, lower section 18 is a generally funnel-shaped plate formed of fluid-tight material. The main portion thereof is spaced from the first upper section to form a collecting space 20 there between. Said space 20 serves the purpose of collecting liquid that is drained from the waste WW and through the first upper section 11, 12. The plate 18 is secured with its open top edge to the underside of the flap 8, as seen in its closed position, such as by welding.

The perforated area 12 is provided directly underneath the filter material 11, is preferably formed in, and thereby integral with, the actual metal flap 8 chute valve 7, and may consist of essentially evenly distributed holes punched or otherwise formed in a central area covering the major part of the surface of the flap 8. The holes shall be formed with a diameter and/or in a number sufficient to allow free flow of liquid therethrough. However, the perforated area 12 must also maintain sufficient strength and stability to serve its main purpose as a support plate for backing up the filter material 11 by supporting the weight of the wet waste WW (see Fig. 3A) gathered on top of the discharge valve 7. In an alternative embodiment, the central area may also be formed by a separate perforated steel plate (not illustrated) that is secured in an open central area of the valve flap 8.

The separate filter material 11 is secured to the top of the valve flap, completely covering the perforated area 12, by means of a clamping ring 14 that is fastened to the flap 8 by means of bolts 16 introduced into through bores 15 of the ring 14 and screwed into corresponding bores 13 in the flap 8. Depending upon the application, the filter material 11 may be chosen from a variety of materials, such as wire mesh, or cloth material woven from synthetic or natural fibers, serving the purposes of holding back or blocking solid waste and of allowing liquid content L of the wet waste WW to pass therethrough. In the application intended for handling kitchen waste it is normally appropriate to use a filter material 11 having a wire mesh size of approximately 200 μm.

The second lower section 18 has a generally concave or conical shape and a diameter at the open top that is sufficient for covering all of the perforations or holes of the perforated central area 12. It serves to collect liquid passing through the liquid-permeable upper first member 11, 12. At the vertex or low point thereof that points away from the flap 8, the concave or conical plate 18 is provided with an outlet 19. A first end of a drainage line 25, such as a hose or pipe, is connected to the outlet 19. Through said hose or pipe 25 and through a drainage valve 40 therein, a high vacuum may be applied to the waste WW to suck liquid content L thereof through the liquid-permeable upper first member 11, 12 and to the collecting member 18, and to remove collected liquid L from the dewatering means 9 and to conduct it to an upper area of a device 26 for separating air from liquid. This will be described further below, in association with Figs. 3 A-C.

Spaced from the hose 25, a first end of a vacuum application pipe or hose 27 is likewise connected to an upper area of the separating device 26. The purpose of this separating device is to secure that liquid does not enter the vacuum supply system. A second end of the vacuum application pipe 27 is connected to a vacuum supply line 29. A high vacuum V, in the present application normally in the order of V > 80 % and preferably approximately 90 %, may be applied to the device 26 from a vacuum source 31, through the supply line 29 and through a vacuum application valve 41 in the pipe 27. Ih the present embodiment, the vacuum source 31 is a vacuum pump 31 that is separate from means for supplying the vacuum of the basic waste transport system.

A first end of a liquid discharge pipe or hose 28 is connected to a bottom area of the separating device 26 and a second end thereof is connected to a outlet line 30 leading to a tank or sewer

32 or other means for handling the waste liquid L. The discharge of liquid L from the separating device 26 and into the outlet line 30 is controlled by a liquid discharge valve 42 provided in the liquicl discharge pipe 28. In the present application the vacuum supply line 29 as well as the liquid outlet line 30 is preferably extended along the transport duct 2 of the transport system and to a central location of the transport system.

The described valves 40-42 for the liquid drainage, the vacuum supply and the liquid discharge, respectively, will in most cases be supplemented by an atmospheric air inlet valve 43 connected to a top portion of the separating device 26. Said atmospheric air valve 43 connects the interior of the separating device 26 with the atmosphere to enhance the discharge of liquid L therefrom. All valves 40-43 are connected to and controlled by a common control unit 44. The method of the invention will now be explained with reference to a basic embodiment thereof, illustrated in Figs. 3A-C and 4. In said embodiment the valves 40-43 for the liquid drainage, the vacuum supply, the liquid discharge and the inlet of atmospheric air, respectively, are controlled in accordance with a fixed program. In said basic embodiment the dewatering of the wet waste WW is initiated at a predetermined time before each emptying cycle of a respective chute 1. Prior to the beginning of a first phase I (Fig. 3A) of the dewatering process, all fluid valves 40-43 as well as the chute discharge valve 7 are in their closed positions. The wet waste WW in the chute 1 is supported on the filter material 11, assisted by the perforated area 12. Practical tests have shown that with the fine mesh size of the filter material 11 that is required for i.e. kitchen waste, virtually no liquid content will pass through the filter material 11 during this period.

In the first phase I of the dewatering process, the vacuum application valve 41 is then opened to evacuate air from the separating device 26 to create the high vacuum therein. Next, in a second phase II (Fig. 3B) of the process, the liquid drainage valve 40 is opened fully so that the high vacuum of between approximately 80 and 90 % is abruptly applied to the wet waste WW through the dewatering means 9. This causes liquid L to be separated from the waste WW and to be drawn through the filter material 11 and the perforated area 12 and into the collecting space 20 formed by the funnel-shaped plate 18. The chute 1 itself is ventilated to the atmosphere so that air will pass through the waste WW at a sufficient rate to guarantee sufficient flow of liquid L and air through the dewatering means 9 and into the separating device 26. Air is separated from the liquid L in a well known manner and the liquid L is collected in the bottom region of the device 26.

In a third phase^~Iir(Fig. 3CX the vacuum application valve 41 is closed after a predetermined dewatering time. In the applicable case, the atmospheric air inlet valve 43 is then opened to secure that the interior of the separating device is pressureless. In a fourth phase IV (FIG. 3C) the liquid drainage valve 40 maybe closed, although this is not vital for the process, and the liquid discharge valve 42 is opened to discharge the collected liquid L into the outlet line 30 and to the tank 32. The chute discharge valve 7 is then opened to discharge the now dry waste DW into the transport duct 2. Finally, all of the valves 40-43 are closed so that the system is ready for a new dewatering cycle.

In alternative embodiments of the invention the valves 40-43, and thus the dewatering process may be controlled in accordance with an optional program that activates a dewatering cycle based upon different selected parameters, such as the detected weight of the wet waste that is supported on the discharge valve/dewatering means. In this way, the load applied to the chute discharge valve by temporarily supported wet waste may be controlled to reduce wear of said valve. Likewise, the length of time that the high vacuum is applied to the waste may be controlled based upon detected parameters, such as the weight reduction of the supported waste.

The invention has been described in connection with what is presently considered the most practical and preferred embodiments, but it is to be understood that the invention is not to be limited to the disclosed embodiments. Thus the invention is not restricted to configurations where the waste dewatering means is integrated in the actual chute discharge valve, but also covers embodiments where said dewatering means is a separate unit that is supported by the valve flap and pivots with said flap or that is provided just upstream of the discharge valve and is independently pivoted. In other variants, the upper section may consist of only one element serving both the purpose of draining off the liquid from the waste and the purpose of carrying the weight of the temporarily supported waste. Such variants may comprise only a perforated plate, wire mesh, grate, or only a fine mesh filter material and may specifically be preferred for applications where the size of the smallest solid particles is large and/or where the weight of the temporarily supported waste is low. Also, the system has been disclosed in an embodiment where the strong vacuum for the liquid drainage is provided by means of a separate vacuum pump. However, this does not preclude the use of the standard system vacuum also for this liquid drainage purpose. Likewise the drained off liquid may be collected and/or managed in different ways.

Although the invention has been described and illustrated with specific reference to an application for a separate insertion chute for household waste that is often positioned outdoors, the invention is in no way restricted to such applications. The basic principles of the invention may be applied to most waste insertion chutes in vacuum operated systems, such as also to the traditional multi-story insertion chute as well as to systems for managing and processing kitchen or food waste on a larger scale, for example in commercial and institutional kitchens and restaurants, such as the system disclosed in our International Patent Application No. WO03/057603.

The invention is therefore intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

PATENT CLAIMS

1. A method of dewatering waste (WW) introduced into a waste chute (1) of a vacuum operated waste collection system, where the discharge of the introduced waste into a waste transport duct (2) of the system is controlled by a discharge valve (7), characterized by the following steps:

— temporarily supporting the introduced waste on a liquid permeable upper, first member (11 , 12) at or upstream of the discharge valve;

— separating a liquid content (L) from the temporarily supported waste at said position at or upstream of the discharge valve, by;

— applying a vacuum (V) to the temporarily supported waste, through said liquid permeable member;

— collecting said separated liquid content downstream of said liquid permeable member; and

— removing said collected liquid content from the waste chute by means of said applied vacuum.

2. A method according to claim 1, characterized by integrating said upper first member (11, 12) in said discharge valve (7), by collecting the separated liquid content (L) on a lower, second generally concave member (18) and by integrating also the second member in the discharge valve.

3. A method according to claim 2 characterized by forming a fixed unit (9) comprising the liquid permeable upper, first member (11, 12) and the lower, second generally concave member

(18) and constituting a pivotal valve member (8) of the discharge valve (7) and by discharging the dewatered waste (DW) into the waste transport duct (2) of the system by pivoting said valve member to an open position.

4. A method according to claim 3, characterized by forming said second generally concave member (18) from a liquid-tight material and by connecting a vacuum source (31) to a low point

(19) of said concave member.

5. A method according to claim 4, characterized by connecting said vacuum source (31) to the concave member (18) through a separating device (26) for separating the liquid content (L) from an air stream produced by said vacuum (V).

6. A method according to claim 5, characterized by discharging the liquid (L) separated from the air stream to a separate liquid discharge line (30).

7. A system for dewatering waste (WW) introduced into a waste chute (1) of a vacuum operated waste collection system, said waste chute having a waste discharge valve (7) for controlling the discharge of the introduced waste into a waste transport duct (2) of the system, characterized by,

— a first upper, liquid-permeable member (11, 12) for temporarily supporting the introduced waste, and being provided at a position at or upstream of the waste discharge valve (7); — a collecting member (18) for collecting liquid content (L) separated from the introduced waste (WW) and being provided downstream of the upper liquid-permeable first member;

— a vacuum source (31) connected to said collecting member for applying a liquid separating vacuum (V) to the introduced waste (WW) through said first upper, liquid permeable member; and — a drainage line (25) connected to said collecting member for applying said liquid separating vacuum and removing said separated liquid content (L) therethrough.

8. A system according to claim 7, characterized in that said collecting member (18) has a generally concave shape and in that the first upper, liquid permeable member (11, 12) and the second lower collecting member are integrated in the waste discharge valve (7).

9. A system according to claim 8, characterized in that said first upper, liquid permeable member (11, 12) and said second lower collecting member (18) together form a double- walled pivotal valve member (8) of the discharge valve (7).

10. A system according to any of claims 7-9, characterized in that the first upper, liquid- permeable member (11, 12) consists of a layer of liquid-permeable filter material (11) and a likewise liquid-permeable support plate (12) provided directly underneath the filter material.

11. A system according to claim 10, characterized in that the filter material (11) is a woven cloth material having a mesh size of approximately 200 μm

12. A system according to claim 9, characterized in that said generally concave second lower collecting member (18) consists of a liquid-tight material, in that one end of the drainage line (25) is connected to an outlet (19) at a low point of said concave surface and in that the vacuum source (31) is connected to another end of said drainage line (25).

13. A system according to claim 10, characterized by a separating means (26) being provided in said drainage line (25) for separating the drained liquid content (L) from an air stream produced by said vacuum (V).

14. The use of the system according to any of claims 7-11 for dewatering unpacked household and/or kitchen waste.