WO2005084509A1

WO2005084509A1 - Refuse collection device and system and method of collecting refuse

Info

Publication number: WO2005084509A1
Application number: PCT/SG2005/000079
Authority: WO
Inventors: Kong Chuan Cheong; Chin Chia Tee; Chuen Siang Lim; Kan Por Wong
Original assignee: Sembcorp Environmental Management Pte Ltd
Priority date: 2004-03-10
Filing date: 2005-03-10
Publication date: 2005-09-15
Also published as: SG125945A1

Abstract

A scalable pneumatic suction system uses separate (split) suction units (200) and refuse units (300). The suction units (200) are combined in series and/or parallel to produce a combined airflow of a desired speed and pressure. The combined airflow is linked to a parallel arrangement of refuse units (300), to fill those units from a refuse source, one by one.

Description

Refuse Collection Device and System and Method of Collecting Refuse

Technical Field The present invention relates to pneumatic refuse collection and transfer from a collection point to an apparatus for further disposal.

Background In many urban environments, people tend to live and work in multi-storey, if not high-rise, buildings. In such densely populated environments, common facilities are usually provided, for example, for removing unwanted materials or waste for further disposal.

Figure 1 is a schematic view of a multi-storey building 10 with a known refuse disposal and collection system 20. A common refuse chute or riser 22 is provided to serve homes located in a vertical section ofthe building. Each home accesses the refuse riser 22 through its own chute opening 24. At the base of each chute/riser 22, a collection chamber 26 is provided. Each collection chamber 26 is connected to a suction system 30, via a pipe 28 with a valve 29 between the collection chamber 26 and the pipe 28. A single clearing pipe 28 may service several such collection chambers 26. The suction system 30 is located at a refuse collecting centre 14 and connects to the clearing pipe 28 by a docking port 34. A controller 32 controls the operation ofthe suction system 30 and valves 29. In use, the refuse accumulated at each collection chamber is periodically sucked through the clearing pipe 28 into a refuse bin 16 located in the refuse collecting centre 14 for temporary storage and further disposal. The refuse bin 16 may typically be a large container, which, once full, is hauled away by a hook-lift truck.

These known refuse collection and transfei: systems are expensive and once they are built, they are even more expensive to upgrade or replace. There is a need for more adaptable methods of collecting and disposing of refuse, in which the capacities are scalable according to the needs.

Summary According to one aspect ofthe present invention, there is provided a refuse suction device. The refuse suction device comprises: a suction pump, a pre-pump inlet duct and a post-pump outlet duct, the pre-pump inlet duct and the post-pump outlet duct being in fluid communication with each other through the pump. The refuse suction device also comprises at least one pre-pump or post-pump external port in fluid connexion with the pump; and a refuse collection compartment comprising a refuse and air inlet port and an outlet, the refuse and air inlet port and the outlet being in fluid communication with each other through the refuse collection compartment. The refuse collection compartment outlet is in fluid communication with the pre-pump inlet duct. The at least one pre-pump or post-pump port is operable to connect to a port, pre the pump, of another, similar refuse suction device.

According to a second aspect ofthe present invention, there is provided a refuse collection system comprising a plurality of individual refuse suction devices, each as defined in the first aspect. The devices are connected in parallel to add airflows together and/or in series to add suction pressures together.

According to a third aspect ofthe present invention, there is provided a refuse collection system comprising a plurality of interconnected individual refuse suction devices. Each ofthe refuse suction devices comprises: a suction pump, a pre-pump inlet duct and a post-pump outlet duct, the pre-pump inlet duct and the post-pump outlet duct being in fluid communication with each other through the pump, at least one pre-pump external port and at least one post-pump external port in fluid connexion with the pump. At least one pre-pump external port or at least one post-pump external port of one ofthe devices is connected to at least one post-pump external port of another one ofthe devices.

According to a fourth aspect ofthe present invention, there is provided a system according to the third aspect, wherein one or more of the suction devices is as defined in the first aspect.

According to a fifth aspect ofthe present invention, there is provided a system for collecting refuse comprising a plurality of suction devices. The suction devices are connected together in parallel, to add airflows together, in series with a refuse collecting line.

According to a sixth aspect ofthe present invention, there is provided a system for collecting refuse comprising a plurality of suction devices. The suction devices are connected together in series, to add suction pressures together, in series with a refuse collecting line.

According to a seventh aspect ofthe present invention, there is provided a method of providing a refuse collection system comprising providing a system according to any one ofthe second, fifth and sixth aspects.

According to an eighth aspect ofthe present invention, there is provided a method of collecting refuse comprising providing a system according to any one ofthe second, fifth and sixth aspects and activating one or more ofthe suction devices ofthe system to suck up refuse.

According to a ninth aspect ofthe present invention, there is provided a method of collecting refuse comprising connecting a plurality of suction devices. The suction devices are connected in parallel to add airflows together, in series with a source of refuse through a refuse collecting line. The method further comprises activating one or more ofthe suction devices to suck refuse from the source of refuse, through the refuse collecting line. According to a tenth aspect ofthe present invention, there is provided a method of collecting refuse comprising connecting a plurality of suction devices. The suction devices are connected in series to add suction pressures together, in series with a source of refuse through a refuse collecting line. The method further comprises activating one or more ofthe suction devices to suck refuse from the source of refuse, through the refuse collecting line.

According to a eleventh aspect of the present invention, there is provided a method of assembling a refuse collecting system comprising connecting together a plurality of refuse collection devices as defined in the first aspect, in parallel to add airflows together and/or in series to add suction pressures together.

Brief Description of the Drawings This invention is now described by way of non-limiting examples, with reference to the accompanying drawings, in which:- Figure 1 schematically illustrates a known refuse disposal and collection system in a multi-storey building; Figure 2 is a schematic internal side view of a combination refuse suction unit of the present invention; Figure 3 is a schematic internal top plan view ofthe refuse suction unit of Figure 2; Figure 4 is a schematic perspective view of two combination suction units linked together; Figures 5 A and 5B illustrate two parallel arrangements of two combination suction units; Figures 6 A and 6B illustrate a series arrangement of two combination suction units; Figure 7 is a schematic internal side view of a split suction unit ofthe present invention; Figure 8 is a schematic internal top plan view ofthe refuse suction unit of Figure 7; Figure 9 is a schematic internal side view of a refuse unit of the present invention; Figures 10A and 10B illustrate a parallel and series arrangement, respectively, of two split suction units; Figures 11A and 11B illustrate scaled-up arrangements of pairs of split suction units; Figure 12 illustrates an arrangement of multiple refuse units and multiple suction units; and Figures 13A and 13B illustrate valve positions ofthe multiple refuse units of Figure 12. Detailed Description

Figure 2 is a schematic side view of a combination refuse suction unit 100 according to a first embodiment ofthe present invention. Figure 3 is a schematic internal top plan view of the refuse suction unit of Figure 2.

The combination suction unit 100, in non-limiting summary, is a mobile pneumatic combination suction and refuse storage unit 100 having a housing with two compartments 102, 104. The first compartment 102 is an air suction compartment and contains a blower or vacuum pump 112 and has pre-pump, inlet ports 114 and post- pump, outlet ports 116. The second compartment 104 is a refuse storage compartment and has a refuse collection portion and an inlet port 122 and an outlet. An interconnecting duct 124 connects the outlet ofthe second compartment 104 to the inlet ofthe first compartment 102. An input hose 126 connects the inlet port 122 ofthe second compartment 104 to a source of refuse. When the vacuum pump 112 is turned on, it draws refuse and air along the input hose 126 into the second compartment 104. The refuse drops onto the floor ofthe second compartment 104 and the air passes out to the first compartment 102 and to the vacuum pump. A plurality of such suction units can be connected in series and/or in parallel, using post-pump and pre-pump ports as appropriate. A series connexion allows the suction pressure to be scaled up according to need. A parallel connexion allows the air flow to be scaled up according to need. The capacity ofthe pneumatic system made up of such units is thus flexible and scalable.

The combination suction unit 100 has a housing 132, in the form of a mobile container, shaped and sized to be mounted onto a vehicle, such as a lorry or truck or railway wagon. The housing 132 is substantially a parallepipedon having a length of between about 2m and 8m, and a width and a height of about 3m in each direction. It may, for instance be shaped and sized as a standard freight container. The sides ofthe housing 132 are enclosed with side and top and bottom panels 134. Some of these panels 134 are fixed whilst others may be detachable, openable or hinged in whole or in part. Some of these panels 134 have openings and others have ventilation louvres (not shown). The refuse combination suction unit 100 has two compartments, a first, air suction compartment 102, and a second, refuse storage unit 104, at opposing first and second ends ofthe housing 132. The two compartments are separated by a partition wall 136.

The first compartment 102 has a vacuum pump 112 situated in a main duct, which extends between a water scrubber 138 and a first air filter 140, also in the first compartment 102. The water scrubber 138 is mounted at the base ofthe housing 132, near the partition wall 136. The first air filter 140 is mounted at the top ofthe housing 132 near the first end of the housing, at the opposite end of the first compartment 102. The first air filter 140 exhausts air to the atmosphere.

A pump inlet portion 142 ofthe main duct, between the pump 112 and the water scrubber 138 has two pre-pump branch ducts 144 extending off it, one to each side ofthe first compartment 102. A pump outlet portion 146 ofthe main duct, between the pump 112 and the first air filter 140 also has two post-pump branch ducts 148 extending off it, also one to each side ofthe first compartment 102. An outlet portion 150 ofthe main duct extends from where the two post-pump branch ducts 148 branch off, to the first air filter 140.

The pump inlet portion 142 ofthe main duct rises vertically from the water scrubber 138 to about half the height ofthe housing 132, then extends in a horizontal direction to the pump 112. The pre-pump branch ducts 144 extend from the main duct in this horizontal portion. The pump outlet portion 146 ofthe main duct extends horizontally from the pump 112, close to the end ofthe housing 132, then turns vertically upward to the first air filter 140. The post-pump branch ducts 148 extend from the main duct at the elbow where this horizontal portion joins the vertical portion.

The two pre-pump branch ducts 144 extend through panels on either side ofthe housing 132 and each terminates with a flanged pre-pump side port 114. The pre-pump side ports 114 are closeable with matching flange plates. Likewise the two post-pump branch ducts 148 extend through panels on either side ofthe housing 132 and each terminates with a flanged post-pump side port 116. The post-pump side ports 116 are closeable with matching flange plates. The pre-pump side ports 114 and post-pump side port 116 are ofthe same size and have the same cover fittings. The flanges on the pre- pump side ports and the post-pump side ports 116 act as connectors for connecting hoses thereto, for connexion to connectors or ports of other suction units.

A pre-filter valve 156 sits in the vertical portion ofthe pump outlet portion 146 of the main duct, above the post-pump branch ducts 148. The pre-filter valve 156 is operable to open or close the pump outlet portion 146 ofthe main duct, between the post- pump branch ducts 148 and the first air filter 140. A pre-pump branch valve 158 sits in each ofthe pre-pump branch ducts 144, between the pump inlet portion 142 ofthe main duct and the pre-pump side ports 114. A post-pump branch valve 160 sits in each ofthe post-pump branch ducts 148, between the pump outlet portion 146 ofthe main duct and the post-pump side ports 148. Each ofthe branch valves 158, 160 is independently operable to open or close the respective branch duct 114, 148. ' An engine 162 is also mounted in the first compartment 102 for running the vacuum pump 112. Other types of primer may be used for running the pump, for example an electric motor or a fluid motor, as appropriate. The second compartment 104 has a compactor plate 164 within it. The compactor plate 164 extends substantially across the width ofthe second compartment 104. The compactor plate 164 is operated by means of actuators (not shown) which push (or pull) it from its rest position by the partition wall 136 to an extended position nearer an opposing wall ofthe second compartment 104, at the second end ofthe housing 132.

The second compartment 104 has an inlet port 122 in its ceiling, to which is attached the outlet of a refuse inlet hose 126. A mesh filter 166 extends across much of the rest ofthe ceiling ofthe second compartment 104 and is enclosed above the ceiling by an end of an interconnecting duct 124. The interconnecting duct 124 extends between from above the ceiling ofthe second compartment 104, through the ceiling ofthe first compartment 102, beside the partition wall 136, and terminates just above the water level in the water scrubber 138. A flexible rubber flap 168 extends down from the end ofthe interconnecting duct 124 into the water in the water scrubber 138. The water scrubber 138 is provided to clean incoming air of dust. The water scrubber 138 also includes a second filter 170, in this example of plastic material, above the water. The second air filter 170 acts as a barrier to prevent water droplets in the air coming off and out of the water from escaping the water scrubber 138.

The combination suction unit 100 provides a closed fluid path from the second end ofthe inlet hose 126 to the ends ofthe four branch ducts 114, 148 and to the output ofthe first air filter 140.

When the primer is turned on, the vacuum pump 112 sucks air in from the pump inlet portion 142 ofthe main duct. Provided the two pre-pump branch ducts 144 are closed, this, in turn reduces the pressure in the water scrubber 138. Air is then drawn down the interconnect duct 124 and through the water scrubber 138. This, in turn takes air from the second compartment 104, which, in turn draws air into the refuse inlet hose 126. Thus, there is a suction or vacuum at the second end ofthe refuse inlet hose 126. Water from the water scrubber 138 is not drawn up into the pump inlet portion 142 ofthe main duct due to the presence ofthe rubber flap which flexes and allows air to pass over the water if the pressure difference is sufficiently large.

Air from the pump 112 is expelled through the pump outlet portion 146 ofthe main duct. Assuming the post-pump branch ducts 148 are closed and the pre-filter valve 156 is open, the air passes to the first air filter 140 and thence to the atmosphere. The first air filter 140 typically includes activated charcoal to remove odours.

The first air filter 140 and the water scrubber 138 can be at interchanged positions. In that case the second filter may not be necessary, as it may not matter if there water in the air being exhausted. The aim is to remove the dust and odours before the air is exhausted. Alternatively, the first air filter 140 and the water scrubber 138 may be at the same end (before or after the pump 112).

In use, as shown in Figure 2, the vacuum generated by the vacuum pump 112 draws in air and refuse through the flexible hose 126 into the second compartment 104. Due partly to the decrease in the velocity ofthe air stream CI as air is sucked into the second.compartment 104, and partly due to the effect of gravity, the refuse or waste materials separate from the air stream CI and accumulate at the bottom ofthe second compartment 104. The air C2, mostly devoid of refuse, is then evacuated at the top ofthe second compartment 104 through the mesh filter 166 to the inlet ofthe interconnect duct 124, the interconnect duct 124, the second air filter 170, the water scrubber 138, the vacuum pump 112 and the first air filter 140.

The end panel ofthe second compartment 104 has a tailgate 172, for external access. The tailgate 172 is pivoted along its top edge and is openable by means of actuators (not shown in Figure 3). The tailgate 172 allows the refuse collected in the second chamber 104 to be discharged and allows cleaning and maintenance of at least the second compartment 104. On the underside ofthe combination suction unit 100, near both ends ofthe housing 132 is a pair of rollers 174. These rollers 174 are arranged along a common axis parallel to the width ofthe housing 132 but are spaced apart so that each roller 174 is near the edge ofthe housing 132. At the end ofthe housing 132, on the outside ofthe end ofthe first (suction) compartment 102, is a lug 176 for mechanical handling ofthe combination suction unit 100. There is also a similar lug 176 on the other (refuse compartment) end, for improved flexibility of handling.

The combination suction unit 100 is typically used to replace both the suction system 30 and bins 16 at the refuse collecting centre 14 (ofthe system shown in Figure 1). The free end ofthe hose 126 is connected to the docking port 34 at the bin end ofthe pipe 28 to allow refuse to be sucked out from the collection chambers 26. The combination suction unit 100 may either be left at the refuse collecting centre 14 until it is full, or else driven to the location, filled up and taken away, without having to be lowered to the ground.

Thus it can operate in a hybrid fashion, on the ground or on a truck. For use on the truck, the combination suction unit 100 may be provided with a drive input to drive the pump 112, rather than using the internal primer ofthe combination suction unit 100. The hybrid operational capability enables a combination suction unit 100 to be used more efficiently than if it were stationary. For example if the access to the refuse it at different points (i.e. there are multiple docking stations), as happens in larger developments or several small developments, the one combination suction unit 100 on a truck can be driven round to each of them in turn. The refuse from all the multiple docking stations can be emptied into the combination suction unit 100 before it proceeds to the dump, transfer station or incineration plant. This contrasts with a separate unit sitting by each single docking station and remaining idle most ofthe time. The suction unit 100 does not kept operate continuously but is used occasionally as necessary. After each use, the compactor plate 164 is driven in the lengthwise direction ofthe second compartment 104 to compact the refuse therein.

When the second compartment 104 of a combination suction unit 100 is filled up with refuse, or otherwise to be removed from the refuse collecting centre 14, the combination suction unit 100 is hoisted up, for example by a hook-lift truck. This can be in a single action or by lifting up one end by way of one ofthe lugs 176 and dragging the unit 100 over the end of a truck with the help ofthe rollers 174 supporting the lower end ofthe unit. A hook lift truck can also be used to deliver the combination suction unit 100 and push it into place on its rollers 174.

The suction units 100 not only can be used alone, but can also be used in pairs (or in greater numbers if necessary). Figure 4 shows a parallel arrangement of two suction units 100A, 100B, side by side. In this arrangement, the pre-pump and post-pump ports 114, 116 ofthe suction units 100 A, 100B, which are on the outside sides ofthe combinations units (i.e. on the sides not directly facing the other suction unit) are closed by their flanges (and/or by their branch valves). A connector station 182 is sited between the two suction units 100A, 100B, at a position roughly in the centre between the four pre-pump and post- pump ports 114, 116 on the inside sides ofthe two suction units 100A, 100B. The inside side (right side) pre-pump port 114A and the post-pump port 116A of the first suction unit 100A are connected to the connector station 182. The connexion is via a first, three-way connector hose 184A. The inside side (left side) pre-pump port 114B and the post-pump port 116B ofthe second suction unit 100B are also connected to the connector station 182. The connexion is via a second, three-way connector hose 184B. The first connector hose 184 A has a first pre-pump inlet 188 A and a first post- pump inlet 190 A, connected to the pre-pump port 114A and the post-pump port 116 A, respectively, ofthe first suction unit 100A. The second connector hose 184B has a second pre-pump inlet 188B and a second post-pump inlet 190B, connected to the pre- pump port 114B and the post-pump port 116B, respectively, ofthe second suction unit 100B. The input hose 126 of one ofthe suction units (in the case of Figure 4, the input hose 126 A ofthe first suction unit 100A) has its free end attached to a port on the top of the connector station 182. The input hose 126 ofthe other suction unit (in the case of Figure 4, the input hose 126B ofthe second suction unit 100B) has its free end attached to a port on the top of a docking station 192.

The connector station 182 is a generally cuboid block with four ports to it: one in each of two opposing sides and one in one ofthe other sides and one in the top. Within the block the ports all interconnect, such that there can be fluid flow between any and all of them. Any port can be closed from the outside by way of a cover plate. Alternatively, closeable gates may be provided at each port to close the port even when a hose is connected to the outside ofthe port. The docking station 192 is similar, except that it lacks the additional port in one ofthe sides and may have a port in its underside instead of or in addition to that in the top side. Connector stations and docking stations may even be the same, except in their use.

Figures 5 A, 5B, 6A and 6B are top plan views ofthe arrangement of Figure 4. The valves in the suction units (and gates in the connector station, where present) are opened and closed in particular arrangements to obtain parallel and series airflows through the suction units, as described below. In each Figure, in the arrangement being exemplified, the air flow is shown by way of arrows through those portions ofthe various hoses that are not closed off at one end. The solid arrow lines in Figures 5 A and 5B represent airflow in a parallel arrangement (as described). The dashed arrow lines in Figures 6A and 6B represent airflow in a series arrangement (as described).

The dotted arrow lines in Figures 5A and 5B and the combined dotted and dashed arrow lines in Figures 6 A and 6B represent airflow routes from the connector station 182 that may be used as alternatives to using the input hoses 126A, 126B, as are also described later.

In Figures 5A and 5B a higher flow of air, compared with that achieved by a single suction unit, can be achieved to convey waste materials through the refuse collection system, by arranging the various gates and valves to provide a parallel suction arrangement. The pre-pump branch valve 158 A and the post-pump branch valve 160 A ofthe first suction unit 100A are closed, as is the post-pump branch valve 160B ofthe second suction unit 100B. The pre-pump branch valve 158B ofthe second suction unit 1 OOB is open. The pre-pump branch valve 158 A of the first suction unit 1 OOA is shown in dotted lines because, in the alternative arrangement of Figure 5 A, described later, it is open.

In Figure 5 A, the flow of air between the two suction units 100A, 100B, is: i) through the input hose 126B of the second suction unit 1 OOB; ii) from the left side pre-pump port 114B ofthe second suction unit 100B; iii) through the pre-pump inlet 188B of the second connector hose 184B, to a side port ofthe connector station 182; iv) through the connector station 182, to the top port ofthe connector station 182; v) through the input hose 126 A ofthe first suction unit 100 A; and vi) to the input port of the first suction unit 1 OOA.

There is further airflow within the two suction units 100 A, 1 OOB. Within the - second suction unit 100B, the airflow splits at the pre-pump branch duct, with some air passing out through the left side pre-pump port 114B, as mentioned above. The rest of the air passes through the main duct ofthe second suction unit 100B, including through the blower 112B and the outlet portion 150B. In the first suction unit 100A, all the air passes through the main duct, including through the blower 112A and the outlet portion 150A.

There is no airflow through the first connector hose 184A, since it is closed at both connexions to the first suction unit 100A (alternatively, it could be due to the relevant port at the connector station being closed). The pre-filter valves ofthe first and second suction units 100A, 100B are open. With this arrangement, the suction ofthe first suction unit 100A is added in parallel to the suction ofthe second suction unit 100B, joining together in the pre-pump duct ofthe second suction unit 100B, for increased airflow in the input hose 126B ofthe second suction unit 100B. Refuse 194 is drawn into and deposited in the refuse storage compartment ofthe second suction unit 100B. All that passes through to the refuse storage compartment ofthe first suction unit 100A is air. Once the refuse storage compartment 104 ofthe second suction unit 100B is

(sufficiently) full of refuse 194, the free ends ofthe two input hoses 126 are swapped over, to the position shown in Figure 5B. That is that the input hose 126 A ofthe first suction unit 100A is connected to the top port ofthe docking station 192 and the input hose 126B ofthe second suction unit 100B is connected to the top port ofthe connector station 182. The only valve and gate positions that are different are those to the pre- pump inlets 188A, 188B ofthe first and second connector hoses 184A, 184B. The pre- pump inlet 188 A ofthe first connector hose 184A is open while the pre-pump inlet 188B ofthe second connector hose 184B is closed. The pre-pump branch valve 158B ofthe second suction unit 100B is shown in dotted lines because, in the alternative arrangement of Figure 5B, described later, it is open.

The flow of air in the parallel arrangement of Figure 5B, between the two suction units 100A, 100B, is: i) through the input hose 126A of the first suction unit 1 OOA; ii) from the right side pre-pump port 114 A of the first suction unit 1 OOA; iii) through the pre-pump inlet 188 A of the first connector hose 184A, to a side port ofthe connector station 182; iv) through the connector station 182, to the top port of the connector station 182; v) through the input hose 126B ofthe second suction unit 100B; and vi) to the input port ofthe second suction unit 100B.

There is further airflow within the two suction units 100A, 100B. Within the first suction unit 100A, the airflow splits at the pre-pump branch duct, with some air passing out through the right side pre-pump port 114 A, as mentioned above. The rest ofthe air passes through the main duct ofthe first suction unit 100A, including through the blower 112A and the outlet portion 150A. In the second suction unit 100B, all the air passes through the main duct, including through the blower 112B and the outlet portion 150B.

In Figure 5B, there is no airflow through the second connector hose 184B, since it is closed at both connexions to the second suction unit 100B (alternatively, it could be due to the relevant port at the connector station being closed). With this arrangement, the suction ofthe second suction unit 100B is added in parallel to the suction ofthe first suction unit 100A, joining together in the pre-pump duct ofthe first suction unit 100A, for increased airflow in the input hose 126A ofthe first suction unit 100A. Refuse 194 is drawn into and deposited in the refuse storage compartment ofthe first suction unit 100A. All that passes through to the refuse storage compartment ofthe second suction unit 100B is air.

Figures 6A and 6B show a series arrangement for increased suction pressure. The greater suction pressure can be achieved to convey waste materials through the refuse collection system, by arranging the various gates and valves to provide a series suction arrangement. For these arrangements the post-pump branch valve of one ofthe post-pump ducts leading to one of post-pump inlets of one ofthe connector hoses is open, whilst the pre-pump branch valves ofthe pre-pump ducts leading to both pre-pump inlets of both connector hoses are closed.

In Figure 6A, the second connector hose 184B is connected between a side port ofthe connector station 182 and the post-pump port 116B ofthe second suction unit 100. The pre-pump branch valve 158A and the post-pump branch valve 160 A ofthe first suction unit 100A are closed, as is the pre-pump branch valve 158B ofthe second suction unit 100B. The post-pump branch valve 160B ofthe second suction unit 100B is open. The pre-pump branch valve 158 A ofthe first suction unit 100A is shown in dotted lines because, in the alternative arrangement of Figure 6A, described later, it is open.

In Figure 6 A, the flow of air between the two suction units 100A, 100B, is: i) through the input hose 126B ofthe second suction unit 100B; ii) from the left side post-pump port 116B of the second suction unit 1 OOB; iii) through the post-pump inlet 190B ofthe second connector hose 184B, to a side port of the connector station 182; iv) through the connector station 182 to the top port ofthe connector station 182; v) through the input hose 126A ofthe first suction unit 100A; and vi) to the input port ofthe first suction unit 100A.

There is further airflow within the two suction units 100A, 100B. Within the second suction unit 100B, the air passes through the main duct including through the blower 112B, as far as the left side post-pump port 116B. In the first suction unit 100A, all the air passes through the main duct, including through the blower 112A and the outlet portion 150A.

In Figure 6A, there is no airflow through the first connector hose 184A, since it is closed at both connexions to the first suction unit 100A (alternatively, it could be due to the relevant port at the connector station being closed). Further the pre-filter valve ofthe second suction unit 100B is also closed. The pre-filter valve ofthe first suction unit

100A is open. With this arrangement, the suction ofthe first suction unit 100A is added in series to the suction ofthe second suction unit 100B, coming into the second suction unit 100B at the post-pump duct. Thus the pump ofthe second suction unit 100B is further increasing the suction pressure (reducing the absolute pressure). Refuse 194 is drawn into and deposited in the refuse storage compartment ofthe second suction unit 100B. All that passes through to the refuse storage compartment ofthe first suction unit lOOA is air. Once the refuse storage compartment ofthe second suction unit 100B is (sufficiently) full, of refuse 194 the free ends ofthe two input hoses 126 are swapped over, to the position shown in Figure 6B. That is that the input hose 126 A ofthe first suction unit 100A is connected to the top port ofthe docking station 192 and the input hose 126B ofthe second suction unit 100B is connected to the top port ofthe second connector station 184A. The only difference in valve and gate positions are that the post-pump branch valve 160 A ofthe first suction unit 100A is open, while the post-pump branch valve 160B ofthe second suction unit 100B is closed. The pre-pump branch valve 158B ofthe second suction unit 100B is shown in dotted lines because, in the alternative arrangement of Figure 6B, described later, it is open.

The flow of air in the series arrangement of Figure 6B, between the two suction units 100A, 100B, is: i) through the input hose 126 A ofthe first suction unit 100A; ii) from the right side post-pump port i 16 A of the first suction unit 1 OOA; iii) through the post-pump inlet 190A ofthe first connector hose 184 A, to a side port ofthe connector station 182; iv) through the connector station 182, to the top port of the connector station 182; v) through the input hose 126B ofthe second suction unit 100B; and vi) to the input port ofthe second suction unit 100B.

There is further airflow within the two suction units 100A, 100B. Within the first suction unit 100A, the air passes through the main duct including through the blower 112 A, as far as the right side post-pump port 116A. In the second suction unit lOOB, all the air passes through the main duct, including through the blower 112B and the outlet portion 150B.

In Figure 6B, there is no airflow through the second connector hose 184B, since it is closed at both connexions to the second suction unit 100B (alternatively, it could be due to the relevant port at the connector station being closed). With this arrangement, the suction ofthe second suction unit 100B is added in series to the suction ofthe first suction unit 100A, coming into the first suction unit 100A at the post-pump duct. Thus the pump ofthe first suction unit 100A is further reducing the pressure. Refuse 194 is drawn into and deposited in the refuse storage compartment ofthe first suction unit 100A. All that passes through to the refuse storage compartment ofthe second suction unit 100B is air.

In the arrangements of Figures 4 to 6, the input into every suction unit is via its input hose. In alternative arrangements, the air input for the secondary suction unit, that is the one whose input hose is not connected to the docking station, is via the pre-pump port, via the pre-pump inlet to the relevant connector hose. This is the arrangement that is illustrated by way of the dotted arrow lines in Figures 5 A and 5B and the combined dotted and dashed arrow lines in Figures 6 A and 6B. The valves to the relevant ports in each Figure is shown in different dotted lines to indicate that for these alternative arrangements, those valves would be open rather than closed. The input hose ofthe secondary suction unit in each case is disconnected from the connector station and the top port closed with a plate. Alternatively, the gate to the top port is closed instead.

With the alternative arrangement of Figure 5 A, airflow is: i) through the input hose 126B ofthe second suction unit 100B; ii) from the left side pre-pump port 114B ofthe second suction unit 100B; iii) through the pre-pump inlet 188B ofthe second connector hose 184B, to a side port ofthe connector station 182; iv) through the first connector hose 184A (and out through the pre-pump inlet 188 A); and v) through the pre-pump port 114A of the first suction unit 1 OOA, without passing through the second compartment ofthe first suction unit 100A.

With the alternative arrangement of Figure 5B, airflow is: i) through the input hose 126 A of the first suction unit 1 OOA; ii) from the right side pre-pump port 114A of the first suction unit 100 A; iii) through the pre-pump inlet 188 A ofthe first connector hose 184 A, to a side port ofthe connector station 182; iv) through the second connector hose 184B (and out through the pre-pump inlet 188B); and v) through the pre-pump port 114B ofthe second suction unit 100B, without passing through the second compartment ofthe second suction unit 100B.

For the alternative arrangements of Figures 5 A and 5B, the only difference between them is the input hose that is connected to the docking station. The positions of the valves and gates are unchanged between them.

With the alternative arrangement of Figure 6 A, airflow is: i) through the input hose 126B ofthe second suction unit 100B; ii) from the left side post-pump port 116B of the second suction unit 1 OOB; iii) through the post-pump inlet 190B ofthe second connector hose 184B, to a side port of the connector station 182; iv) through the first connector hose 184A (and out through the pre-pump inlet 188A); and v) through the pre-pump port 114 A of the first suction unit 1 OOA, without passing through the second compartment ofthe first suction unit 100A.

With the alternative arrangement of Figure 6B, airflow is: i) through the input hose 126 A of the first suction unit 1 OOA; ii) from the right side post-pump port 116A of the first suction unit 1 OOA; iii) through the post-pump inlet 190A of the first connector hose 184A, to a side port of the connector station 182; iv) through the second connector hose 184B (and out through the pre-pump inlet 188B); and v) through the pre-pump port 114B ofthe second suction unit 100B, without passing through the second compartment ofthe second suction unit 100B.

The interconnections between the pre-pump and post-pump ports ofthe suction . units may be direct, rather than through an intervening connector station.

The arrangements of Figures 4 to 6 show just two suction units together. It is possible to use more in series or parallel, or even in a combination of both, but may be economically disadvantageous compared with the further embodiments described below. The use of three such suction units is more likely where a pipe to the docking station 192 is blocked. For example, where two suction units on the ground are joined in series (for example as in Figure 6A) and a third suction unit is brought along on a truck. The input hose ofthe additional suction unit is then added in series, connected to the outside (left side) post-pump port of the first suction unit 1 OOA. The connexion would be in a similar manner to the connexion ofthe input hose 126 A ofthe first suction unit 100A to the left side post-pump port 116B ofthe second suction unit 100B.

In the arrangements of Figures 4 to 6, a two three-way hoses 184A, 184B and a single connector station 182 are used. The two three-way hoses 184A, 184B may be replaced with two two-way hoses. Thus when changing arrangements to that of either one of Figures 6A and 6B, the ends ofthe hoses connected to the one or both ofthe connector station 182 stay in place, but the other end of one or both hoses will have to be moved to the other ofthe relevant pre-pump or post-pump output port. In another alternative arrangement, there are two connector stations, one connected to both pre- pump ports and the other connected to both post-pump ports. A connector hose runs between an additional side port in the two connector stations.

The hoses between suction units and the connector station and the docking station are generally flexible (although they can be rigid).

Figure 7 is a schematic internal side elevation of a separate, split suction unit 200, according to a second embodiment ofthe invention. Figure 8 is a schematic internal top plan view ofthe split suction unit 200 of Figure 7. The split suction unit 200 of Figures 7 and 8 is similar to the combination suction unit 100 described above, except that it lacks the second compartment 104 and has no pre-pump side ducts and pre-pump ports, except a single inlet.

The split suction unit 200, in non-limiting summary,- is a mobile pneumatic suction unit 200 having a housing with a single compartment 202. The compartment 202 is an air suction compartment and contains a vacuum pump 212 and has post-pump, outlet ports 216. An interconnecting duct 224 connects an input hose 226 to the inlet of the compartment 202. When the vacuum pump 212 is turned on, it draws air along the input hose 226 to the vacuum pump. A plurality of such suction units can be connected in series and/or in parallel, using post-pump and pre-pump ports as appropriate, usually by way of suitably positioned connector stations. A series connexion allows the suction pressure to be scaled up according to need. A parallel connexion allows the air flow to be scaled up according to need. The capacity of the pneumatic system made up of such units is thus flexible and scalable. A scalable pneumatic suction system uses separate (split) suction units 200 and refuse units 300. The suction units 200 are combined in series and/or parallel to produce a combined airflow of a desired speed and pressure. The combined airflow is linked to a parallel arrangement of refuse units 300, to fill those units from a refuse source, one by one.

The split suction unit 200 has a housing 232, in the form of a mobile container, shaped and sized to be mounted onto a vehicle, such as a lorry or truck or railway wagon. The housing 232 is substantially a parallepipedon having a length of about 6.5m (a standard container size) and a width and a height of about 3m in each direction. It may, for instance be shaped and sized as a standard freight container. The sides ofthe housing 232 are enclosed with side and top and bottom panels 234. Some of these panels 234 are fixed whilst others may be detachable, openable or hinged in whole or in part. Some of these panels 234 have openings and others have ventilation louvres (not shown).

The compartment 202 has a vacuum pump 212 situated in a main duct, which extends between a water scrubber 238 and a first air filter 240, also in the compartment 202. The water scrubber 238 is mounted at the base ofthe housing 232, near an end wall ofthe suction unit. The first air filter 240 is mounted at the top ofthe housing 232 near the first end ofthe housing, at the opposite end ofthe compartment 202. The first air filter 240 exhausts air to the atmosphere.

A pump inlet portion 242 extends from the water scrubber 238 to the pump 212. A pump outlet portion 246 ofthe main duct, between the pump 212 and the first air filter - 240 has two post-pump branch duets 248 extending off it, one to each side ofthe compartment 202. An outlet portion 250 ofthe main duct extends from where the two post-pump branch ducts 248 branch off, to the first air filter 240. The pump inlet portion 242 ofthe main duct rises vertically from the water scrubber 238 to about half the height ofthe housing 232, then extends in a horizontal direction to the pump 212. The pump outlet portion 246 ofthe main duct extends horizontally from the pump 212, close to the end ofthe housing 232, then turns vertically upward to the first air filter 240. The post-pump branch ducts 248 extend from the main duct at the elbow where this horizontal portion joins the vertical portion.

The two post-pump branch ducts 248 extend through panels on either side ofthe housing 232 and each terminates with a flanged post-pump side port 216. The post- pump side ports 216 are closeable with matching flange plates. The flanges on the post- pump side ports 216 act as connectors for connecting hoses thereto, for connexion to ports of connectors or other suction units.

A pre-filter valve 256 sits in the vertical portion ofthe pump outlet portion 246 of the main duct, above the post-pump branch ducts 248. The pre-filter valve 256 is operable to open or close the pump outlet portion 246 ofthe main duct, between the post- pump branch ducts 248 and the first air filter 240. A post-pump branch valve 260 sits in each ofthe post-pump branch ducts 248, between the pump outlet portion 246 ofthe main duct and the post-pump side ports 248. Each ofthe branch valves 260 is independently operable to open or close the respective branch dud 248.

An engine 262 is also mounted in the compartment 202 for running the vacuum pump 212. Other types of primer may be used for running the pump, for example an electric motor or a fluid motor, as appropriate.

The interconnecting duct 224 extends through the ceiling ofthe compartment 202, beside an end wall ofthe suction unit, and terminates just above the water in the water scrubber 238. A flexible rubber flap 268 extends down from the end ofthe interconnecting duct 224 into the water in the water scrubber 238;

The water scrubber 238 is provided to clean incoming air of dust. Above the water ofthe water scrubber 238 is a second air filter 270 to clean the air of any components that passed between the rubber flap 268 and the water, and to reduce the water content ofthe air coming off and out ofthe water scrubber 238.

The suction unit 200 provides a closed fluid path from the free end ofthe inlet hose 226 to the ends ofthe two branch ducts 248 and to the output ofthe first air filter 240.

When the primer is turned on, the vacuum pump 212 sucks air in from the pump inlet portion 242 ofthe main duct. This, in turn, reduces the pressure in the water scrubber 238. Air is then drawn down the interconnect duct 224 and through the free end ofthe inlet hose 226. Thus, there is a suction or vacuum at the second end ofthe inlet hose 226.

Air from the pump 212 is expelled through the pump outlet portion 246 ofthe main duct. Assuming the post-pump branch ducts 248 are closed and the pre-filter valve 256 is open, the air passes to the first air filter 240 and thence to the atmosphere. The first air filter 240 typically includes activated charcoal to remove odours.

The first air filter 240 and the water scrubber 238 (together with the second air filter 270) can be at interchanged positions. The aim is to remove the dust and odours before the air is exhausted. Alternatively, the first air filter 240 and the water scrubber 238 may be at the same end (before or after the pump 212). With such an arrangement, the second air filter may not be necessary. On the underside ofthe suction unit 200, near both ends ofthe housing 232 is a pair of rollers 274. These rollers 274 are arranged along a common axis parallel to the width ofthe housing 232 but are spaced apart so that each roller 274 is near the edge of the housing 232. At the end ofthe housing 232, by the interconnecting duct 224, on the outside, is a lug 276 for mechanical handling ofthe suction unit 200. There is also a similar lug 276 on the other interconnecting duct end, for improved flexibility of handling. Figure 9 is a schematic internal side elevation of a refuse unit 300. The refuse unit 300 is similar to the second compartment 104 ofthe combination suction unit 100 described earlier. The refuse unit 300 has a closed housing 332 with a refuse storage compartment

304 containing a compactor plate 364. The compactor plate 364 extends substantially across the width ofthe refuse storage compartment 304. The compactor plate 364 is operated by means of actuators (not shown) which push (or pull) it from its rest position by a first internal wall 336, near a first end ofthe refuse unit 300 to an extended position nearer an opposing, second end ofthe refuse storage compartment 304.

The refuse storage compartment 304 has an inlet port 322 in the first end wall 320. The inlet port 322 has mountings for attachment thereto of an inlet hose, whose other end is connected to a refuse source. An inlet duct 330 extends into the refuse storage compartment 304 and passes down through a mesh filter 366 extending across most ofthe ceiling ofthe refuse storage compartment 304. The first internal wall 336 is spaced a short distance from the first end wall 320 ofthe first end ofthe refuse unit 300. The space between the first internal wall 336 and the first end wall 320 ofthe refuse unit 300 forms an outlet duct 324, which joins up with the space above the mesh filter 366 and below the top ofthe refuse unit 300. The outlet duct 324 exits the refuse unit 300 at an outlet port 350. The outlet port 350 has mountings to allow attachment ofthe free end of an input hose of a suction unit.

In use, if the inlet port 322 ofthe refuse unit 300 is connected to a refuse source and the outlet port 350 is connected to a suction source, the vacuum generated by the suction source draws in air and refuse through the inlet port 322 into the refuse storage compartment 304. Due partly to the decrease in the velocity ofthe air stream as air is sucked into the refuse storage compartment 304, and partly due to the effect of gravity, the refuse or waste materials separate from the air stream and accumulate at the bottom ofthe refuse storage compartment 304. The air, mostly devoid of refuse, is then evacuated at the top ofthe refuse storage compartment 304 through the mesh filter 366 to the outlet port 350, and thence to the suction source. The end panel ofthe refuse storage compartment 304 has a tailgate 372, for external access. The tailgate 372 is pivoted along its top edge and is openable by means of actuators (not shown). The tailgate 372 allows the refuse collected in the second chamber 304 to be discharged and allows cleaning and maintenance of at least the refuse storage compartment 304.

On the underside ofthe combination suction unit 300, near both ends ofthe housing 332 is a pair of rollers 374. These rollers 374 are arranged along a common axis parallel to the width ofthe housing 332 but are spaced apart so that each roller 374 is near the edge ofthe housing 332.

At the first end ofthe housing 332 is a lug 376 for mechanical handling ofthe combination suction unit 300. There is also a similar lug 376 on the other (tailgate) end, for improved flexibility of handling.

A set including at least one split suction unit 200 and at least one refuse unit 300 is typically used to replace both the suction system and bins at the refuse collecting centre (ofthe system shown in Figure 1). The free end ofthe Met hose of a suction unit 200 is connected to the outlet port of a refuse unit 300. The free end of an inlet hose to the refuse unit 300 is connected to a docking port at the bin end of the pipe to allow refuse to be sucked out from the collection chambers. The refuse unit 30Q may either be left at the refuse collecting centre until it is full, or else driven to the location, filled up and taken away, without having to be lowered to the ground. Thus it can operate in a hybrid fashion, on the ground or on a truck. Such an arrangement requires an accessible docking port for the refuse unit 300 and an additional hose to pass between the refuse unit 300 and the docking port.

The refuse unit 300 does not operate continuously but is used occasionally as necessary. After regular use, the compactor plate 364 is driven in the lengthwise direction ofthe refuse storage compartment 304 to compact the refuse therein.

When the refuse storage compartment 304 of a refuse unit 300 is filled up with refuse, or otherwise to be removed from the refuse collecting centre, the refuse unit 300 is hoisted up, for example by a hook-lift truck. This can be in a single action or by lifting up one end by way of one ofthe lugs 376 and dragging the unit 300 over the end of a truck with the help ofthe rollers 374 supporting the lower end ofthe unit. A hook lift truck can also be used to deliver the refuse unit 300 and push it into place on its rollers 374.

The split suction units 200 may be connected in parallel and/or series, based on similar principles to the parallel and series arrangements ofthe combination units described above. Figure 10A is a schematic view of a parallel pair arrangement 400 of two split suction units 200. Figure 10B is a schematic view of a series pair arrangement 420 of two split suction units 200.

In Figure 10A, the input hoses 226 A, 226B of two suction units 200 are connected to separate ports of a modulator unit 402. The modulator unit is made up of four connector stations: first and second output connector stations 404A, 404B; and joining connector station 406; and an input connector station 408. The input hose 226A ofthe first suction unit 200A is connected to the top port ofthe first output connector station 404A. The input hose 226B ofthe second suction unit 200B is connected to the top port ofthe second output connector station 404B. There is no connexion between the post-pump ports ofthe suction units. The two output connector stations 404A, 404B connect to separate side ports of the joining connector station 406. A third side port of the joining connector station 406 connects to a side port ofthe input connector station 408. Thus, when botii suction units are operating, they draw air in parallel, through the input connector station 408 to the joining connector station 406, where the airstream splits, some going to the first output connector station 404A and thence to the first suction unit 200A, the rest going to the second output connector station 404B and thence to the second suction unit 200B.

In Figure 10B, the input hose 226A ofthe first suction unit 200A is connected to the top port of a first connector station 282. A post-pump port of the second suction unit 200A is connected by a connector hose to a side port ofthe first connector station 282. The input hose 226B ofthe second suction unit 200B is connected to the top port of an input connector station 422. Thus, when both suction units are operating, they draw air in series, through the input connector station 422 to the second suction unit 200B, through the pump ofthe second suction unit 200B and thence through the first suction unit 200A. Figure 11A shows an exemplary scaled up arrangement 410 of suction units in parallel. Four parallel pair arrangements 400A, 400B, 400C, 400D, each of two split suction units 200 are themselves arranged in parallel. The first and second parallel pair arrangements 400A, 400B are arranged in parallel through a first second-level modulator unit 412 A. The input connector stations 408 A, 408B ofthe two first-level modulator units 402A, 402B act as the output connector stations to the first second-level modulator unit 412 A. Likewise the third and fourth parallel pair arrangements 400C, 400D are arranged in series through a second second-level modulator unit 412B. The input connector stations 408C, 408D ofthe two first-level modulator units 402C, 402D act as the output connector stations to the second second-level modulator unit 412B. A final joining connector station 414 connects the two second-level modulator units 412A, 412B. An airstream input line 416 provides an input to the final joining connector station 414.

In use, when all the suction units ofthe scaled up arrangement 410 are operating, the air flows add up in parallel to generate a large airflow at the final joining connector station 414, which is then split up over different levels to the individual suction units. Various ofthe ports and connector stations can be closed, as and if appropriate to reduce the airflow to what is necessary at any particular occasion. Figure 1 IB shows an exemplary scaled up arrangement 430 of suction units in series and pairs of series suction units in parallel. Four series pair arrangements 420A, 420B, 420C, 420D, each of two split suction units 200 are themselves arranged in parallel. The first and second series pair arrangements 420A, 420B are arranged in parallel through a first first-level modulator unit 402A. The input connector stations 422 A, 422B ofthe first and second series pair arrangements 420 A, 420B act as the output connector stations to the first first-level modulator unit 402A. Likewise the third and fourth series pair arrangements 420C, 420D are arranged in parallel through a second first-level modulator unit 402B. The input connector stations 422C, 422D ofthe third and fourth series pair arrangements 420C, 420D act as the output connector stations to the second first-level modulator unit 402 A. A final joining connector station 414 connects the two first-level modulator units 402A, 402B. An airstream input line 416 provides an input to the final joining connector station 414.

In use, when all the suction units ofthe scaled up arrangement 430 are operating, the series air flows add up in parallel to generate a greater pressure and large airflow at the final joining connector station 414, which is then split up over different levels to the individual suction units. Various ofthe ports and connector stations can be closed, as and if appropriate to reduce the pressure and airflow to what is necessary at any particular occasion.

For the above scaled up arrangements, the inputs are intended to be air only, without any refuse. The refuse is removed upstream. These arrangements just exemplify variations in providing the necessary suction using scaling of smaller suction units.

The above scaled up arrangements are exemplary and may involve more or fewer parallel and series pairs, or triplets of suction units in series or parallel, and other combinations of series and parallel. The use of three suction units in parallel is seldom necessary, except when to clear a blockage. Usually, it is more useful to provide a greater airflow. The use ofthe split suction units 200 is preferred, but the arrangements would work using large numbers ofthe combination units.

Figure 12 illustrates a combined arrangement, with a string of refuse units 300 arranged in parallel connected to an airstream inlet line 416, leading to two series pair arrangements 420 A, 420B mounted in parallel. The airstream inlet line 416 is connected up, in parallel to each ofthe outlet ports ofthe refuse units 300. The inlet ports ofthe refuse units 300 are all mounted on a common refuse intake line 442, which connects to a clearing pipe of a refuse disposal and collection system. Arrows are shown in various ofthe pipes. These do not represent simultaneous airflow, but the direction in which the air flows in each pipe. In the exemplary arrangement shown in Figure 13, the refuse intake line 442 branches several times, one branch for each refuse unit 300, except the last refuse unit 3 OOA in the arrangement, into which the line 442 leads without a branch. A first, branch valve 444 is provided in each branch between the refuse unit 300 and the line 442 (except the branch to the last suction unit). The branch valves 444 are used to close off the respective refuse units 300 from the line 442. Additionally, each refuse unit except the last one has a second, line valve 446 in the line 442, immediately downstream ofthe respective branch, to close off the line 442 to the refuse units 300 behind a closed second valve 446.

In use, amongst the refuse units 300 that are not full, the refuse unit 300 that is furthest alone the intake line 442 from the clearing pipe is selected as the next refuse unit 300 to fill. All the branch valves 444 upstream ofthe selected refuse unit 300 are closed (those downstream ofthe selected refuse unit 300 may also be closed). The branch valve 444 ofthe selected refuse unit 300 is kept open. Further all the line valves 446 upstream ofthe selected refuse unit 300 are opened, whilst the line valve 446 ofthe selected refuse unit 300 is closed (those downstream ofthe selected refuse unit 300 are also generally closed). By closing all the branch valves 444 upstream ofthe selected refuse unit 300, refuse is not sucked into any ofthe upstream refuse units 300. By closing the line valve 446 ofthe selected refuse unit 300, refuse is not able to pass through the line 442 to any downstream refuse units. Thus refuse is only able to enter into the selected refuse unit 300. When the selected suction unit 300 has filled up, the branch valve 444 ofthe next upstream suction unit is opened and its line valve 446 closed. The branch valve 444 of the just filled suction unit 300 is closed. The just filled suction unit 300 can then be taken away for emptying.

The various branch and line valves 444, 446 (and the pumps ofthe suction units) can be controlled automatically to allow automatic emptying of a clearing pipe.

Figures 13 A and 13B illustrate the valve positions and associated degree of emptiness ofthe refuse unit arrangement of Figure 12. Figure 12 has four refuse units 300. Therefore four refuse units 300 are shown in solid lines in Figures 13 A and 14A. However a fifth refuse unit 300 is shown in dotted lines to indicate that the series can be of other numbers of refuse units, more than five or fewer than five. Figure 13 A illustrates the arrangement 440 of refuse units 300 with all refuse units 300 empty. Thus, all the branch valves 444 are closed and all the line valves 446 are open. Figure 13B illustrates the same arrangement 440 of refuse units 300 but with the end two refuse units 300A, 300B full. Thus the branch valve 446 for the third last suction unit 300C is open, whilst all the others are closed. Additionally, the line valves 446 for the second last and third last refuse units 3 OOB, 300C are also closed.

Although the arrangements of Figures 11 to 13 show specific numbers of units (suction and refuse), other embodiments would have similar arrangements but with different numbers of units as appropriate. Embodiments ofthe present invention are well suited to growing developments, where it is preferred to reduce the initial capital outlay where possible, or where the final size is not yet known. The number of refuse units and suction units present depends on the actual size ofthe development. As the development grows, so additional units, especially refuse units can be added. The only planning necessary is that there should be space available to lay out the various units and that all refuse pipes can be laid out to the same area. The available layouts enable efficient and organised use of land space

The above embodiments show all the units side by side. However, the invention is not so limited. Various units maybe mounted on top of each other, for instance in stacks of two or more.

Variations in the use ofthe split suction units may also apply to the use ofthe combination suction units, and vice versa.

The embodiments ofthe present invention are able to provide refuse systems, for instance as shown, whose capacity can be scaled up or adjusted according to what is needed. Further, these suction and refuse collection units are mobile units and can be moved to a site as and when required, for example, when an existing pneumatic system might have broken down. Such suction and refuse collection units can be hooked up to an existing system without interruption to the refuse collection system. Suction and refuse collection units can also be hooked up to an existing system as a back-up system, for example during maintenance. While various embodiments of a refuse suction unit and their method of use have been described and illustrated in detail, it is to be understood that many changes, modifications and variations could be made to the present invention without departing from the scope of this invention.

Claims

1. A refuse suction device comprising: a suction pump, a pre-pump inlet duct and a post-pump outlet duct, the pre-pump inlet duct and the post-pump outlet duct being in fluid communication with each other through the pump; at least one pre-pump or post-pump external port in fluid connexion with the pump; and a refuse collection compartment comprising a refuse and air inlet port and an outlet, the refuse and air inlet port and the outlet being in fluid communication with each other through the refuse collection compartment; wherein the refuse collection compartment outlet is in fluid communication with the pre- pump inlet duct; and the at least one pre-pump or post-pump port is operable to connect to a port, pre the pump, of another, similar refuse suction device.

2. A device according to claim 1, wherein the at least one pre-pump or post-pump port is operable to connect to a port ofthe refuse and air inlet of another, similar refuse suction device.

3. A device according to claim 1 or 2, wherein the at least one pre-pump or post- pump port comprises at least one post-pump external port.

4. A device according to claim 3, wherein the at least one postrpump port is operable to connect to the inlet of the refuse and air inlet port of another} similar refuse suction device.

5. A device according to claim 3 or 4, further comprising a valve between the post- pump inlet duct and each ofthe at least one post-pump ports.

6. A device according to any one of claims 3 to 5, further comprising an air filter on the post-pump duct, after the at least one post-pump port.

7. A device according to claim 6, further comprising a valve for closing the air filter off from the post-pump duct

8. A device according to any one ofthe preceding claims, wherein the at least one pre-pump or post-pump port further comprises at least one pre-pump external port.

9. A device according to claim 8 when dependent on at least claim 3, wherein at least one post-pump port is operable to connect to at least one pre-pump port of another, similar refuse suction device.

10. A device according to claim 8 or 9, wherein the at least one pre-pump port is operable to connect to at least one pre-pump port of another, similar refuse suction device.

11. A device according to any one of claims 8 to 10, wherein the at least one pre- pump port is operable to connect to the inlet ofthe refuse and air inlet port of another, similar refuse suction device.

12. A device according to any one of claims 8 to 11, further comprising a valve between the pre-pump inlet duct and each of the at least one pre-pump ports.

13. A device according to any one of the preceding claims, further comprising an input hose connected in series with the refuse and air inlet port.

14. A device according to any one of the preceding claims, housed in a container of a size and shape corresponding to a standard freight container.

15. A device according to any one ofthe preceding claims, which is mobile and is operable on a vehicle and operable on the ground and/or further comprising roller means on its underside.

16. A refuse collection system comprising a plurality of individual refuse suction devices, each as defined in any one ofthe preceding claims, wherein the plurality of devices are connected in parallel to add airflows together and/or in series to add suction pressures together.

17. A system according to claim 16, wherein the individual refuse suction devices are each as defined in any of claims 3 to 7 or any of claims 8 to 15 when dependent on at least claim 3, wherein the plurality of devices are connected in series, with at least one post-pump port of one ofthe devices connected to a port, pre the pump, of another one of the devices.

18. A system according to claim 16 or 17, wherein the individual refuse suction devices are each as defined in any of claims 8 to 12 or in claim 13, 14 or 15 when dependent on at least claim 8, wherein the plurality of devices are connected in series, with at least one post-pump port of one ofthe devices connected to a pre-pump port of another one ofthe devices.

19. A system according to any one of claims 16 to 18, wherein the plurality of devices are connected in parallel, with at least one port, pre the pump of one ofthe devices connected to a port, pre the pump, of another one ofthe devices.

20. A system according to claim 19, wherein the individual refuse suction devices are each as defined in any of claims 8 to 12 or in claim 13, 14 or 15 when dependent on at least claim 8, wherein the plurality of devices are connected in parallel, with at least one pre-pump port of one ofthe devices connected to pre-pump port of another one ofthe devices.

21. _. A system according to any one of claims 16 to 20, wherein the individual refuse suction devices are each as defined in any of claims 3 to 7 or any of claims 8 to 15 when dependent on at least claim 3, wherein at least two ofthe devices are connected in series, with at least one post-pump port of one ofthe devices connected to a port, pre the pump, of another one of the devices and at least two of the devices are connected iri parallel, with at least one port, pre the pump of one ofthe devices connected to a port, pre the pump, of another one of the devices, and wherein one of the devices connected in series is also one ofthe devices connected in parallel.

22. A refuse collection system comprising a plurality of interconnected individual refuse suction devices, wherein each ofthe refuse suction devices comprises: a suction pump, a pre-pump inlet duct and a post-pump outlet duct, the pre-pump inlet duct and the post-pump outlet duct being in fluid communication with each other through the pump, at least one pre-pump external port and at least one post-pump external port in fluid connexion with the pump; and at least one pre-pump external port or at least one post-pump external port of one ofthe devices is connected to at least one post-pump external port of another one ofthe devices.

23. A system according to claim 22, wherein a plurality ofthe refuse suction devices are connected in parallel, to add airflows together.

24. A system according to claim 23, wherein parallel connexions comprise the pre- pump external ports of two refuse suction devices connected together.

25. A system according to any one of claims 22 to 24, wherein a plurality ofthe refuse suction devices are connected in series, to add suction pressures together.

26. A system according to claim 25, wherein series connexions comprise the pre- pump external port of one refuse suction device connected to the post-pump external port of another refuse suction device.

27. A system according to any one of claims 22 to 26, wherein the plurality of interconnected individual refuse suction devices are connected in series with a refuse collecting line from a source of refuse.

28. A system according to any one of claims 22 to 27, further comprising at least one refuse collection compartment in series connexion with a pre-pump port of at least one of the refuse suction devices.

29. A system according to claims 27 and 28, wherein the at least one refuse collection compartment is mounted in series between the plurality of interconnected individual refuse suction devices and the refuse collecting line.

30. A system according to claim 28 or 29, wherein the at least one refuse collection compartment comprises a plurality of refuse collection compartments mounted together in parallel.

31. A system according to any one of claims 28 to 30, wherein the or each refuse collection compartment comprises an individual refuse unit.

32. A system according to any one of claims 22 to 31, wherein one or more ofthe suction devices is as defined in any one of claims 1 to 15.

33. A system according to any one of claims 22 to 32, wherein individual refuse suction devices further comprises an input hose connected in series wdth the pre-pump port ofthe device.

34. A system according to any one of claims 16 to 33, further comprising one or more individual connector stations within the connexion between ports of different devices.

35. A system according to claims 33 and 34 or according to claim 34 when dependent on at least claim 16, comprising one or more series connexions, where the input hose of one suction device is connected to the post-pump port of another suction device through a connector station.

36. A system accordingto claim 35, according to claims 33 and 34 or according to claim 34 when dependent on at least claim 16, comprising one or more parallel connexions, where the input hose of one suction device is connected to the pre-pump port of another suction device through a connector station.

37. A system according to claim 36, wherein the input hose of one suction device is connected to the pre-pump port of another suction device through a connector station and the input hose ofthe another suction device.

38. A system according to claim 36, wherein the input hose of one suction device is connected to the pre-pump port of another suction device through two connector stations and the input hose ofthe another suction device.

39. A system according to any one of claims 16 to 38, wherein each ofthe suction devices comprises an independent housing.

40. A system according to any one of claims 16 to 39, wherein each ofthe suction devices is independently mobile.

41. A system for collecting refuse comprising a plurality of suction devices connected together in parallel, to add airflows together, in series with a refuse collecting line.

42. A system for collecting refuse comprising a plurality of suction devices connected together in series, to add suction pressures together, in series with a refuse collecting line.

43. A system according to claim 42, further comprising a plurality of suction devices in parallel with the suction devices connected together in series, to add airflows together.

44. A system according to any one of claims 41 to 43, further comprising a plurality of refuse collection devices connected together in parallel, in series between the suction devices and refuse collecting line.

45. A system according to any one of claims 41 to 44, being a system as defined in any one of claims 16 to 40.

46. A method of providing a refuse collection system comprising providing a system according to any one of claims 16 to 45.

47. A method of collecting refuse comprising providing a system according to any one of claims 16 to 45 and activating one or more ofthe suction devices ofthe system to suck up refuse.

48. A method of collecting refuse comprising connecting a plurality of suction devices together in parallel to add airflows together, in series with a source of refuse through a refuse collecting line, and activating one or more ofthe suction devices to suck refuse from the source of refuse, through the refuse collecting line.

49. A method of collecting refuse comprising connecting a plurality of suction devices together in series to add suction pressures together, in series with a source of refuse through a refuse collecting line, and activating one or more of the suction devices to suck refuse from the source of refuse, through the refuse collecting line.

50. A method according to claim 49, further comprising connecting a plurality of further suction devices in parallel with the suction devices connected together in series, to add airflows together, to the refuse collecting line.

51. A method according to any one of claims 48 to 50, further comprising sucking the refuse into a plurality of refuse collection devices connected together in parallel, in series between the suction devices and refuse collecting line.

52. A method according to any one of claims 48 to 51 , wherein individual suction devices comprise a pump and are mounted in an independent mobile housing

53. A method of assembling a refuse collection system comprising connecting together a plurality of refuse suction devices as defined in any one of claims 1 to 15, in parallel to add airflows together and/or in series to add suction pressures together.

54. A method according to claim 53, comprising fluidly connecting the pre-pump duct of at least one ofthe devices with the pre-pump duct of at least another one ofthe devices.

55. A method according to claim 53 or 54, comprising fluidly connecting the post- pump duct of at least one ofthe devices with the pre-pump duct of at least another one of the devices.

56. A refuse suction device constructed and arranged to operate substantially as hereinbefore described, with reference to and as illustrated in accompanying Figures 2 to 13.

57. A refuse collection system constructed and arranged to operate substantially as hereinbefore described, with reference to and as illustrated in accompanying Figures 2 to 13.

58. A system for collecting refuse constructed and arranged to operate substantially as hereinbefore described, with reference to and as illustrated in accompanying Figures 2 to 13.

59. A method of providing a refuse collection system substantially as hereinbefore described, with reference to and as illustrated in accompanying Figures 2 to 13.

60. A method of collecting refuse substantially as hereinbefore described, with reference to and as illustrated in accompanying Figures 2 to 13.

61. A method of assembling a refuse collection system substantially as hereinbefore described, with reference to and as illustrated in accompanying Figures 2 to 13.