A pneumatic conveying system and a method for collecting objects and transporting them to a collecting unit and use of same

Abstract

Pneumatic conveying system (1) and method for collecting objects (2) and transporting them to a collecting unit (3) through a discharge convey line (7), It comprises a loading unit (4) that receives the objects (2), and is connected to an inlet convey line (5), an outlet convey line (6). Air / gas passes through the inlet convey line (5), the loading unit (4) and the outlet convey line (6). A pressure blower (8) provides pressurized gas / air, and is by a first convey line (18) air / gas flow connected to an injector (11) and forms a negative air / gas pressure in the outlet convey line (6). The system (1) comprises an air / gas pump (9) that generates an air / gas flow through the inlet convey line (5) into the loading unit (4), A control system (10) controls the air / gas pressure in the system (1).

Description

[0001] A PNEUMATIC CONVEYING SYSTEM AND A METHOD FOR

[0002] COLLECTING OBJECTS AND TRANSPORTING THEM TO A

[0003] COLLECTING UNIT AND USE OF SAME

[0004] The present invention relates to a pneumatic conveying system for collecting objects and transporting them to a collecting unit through a discharge convey line, the system comprising

[0005] - at least one loading unit adapted to receive said objects through a receiving opening and in gas / air flow connection to an inlet convey line and an outlet convey line, air / gas flow allowed to pass through the inlet convey line, the loading unit(s) and the outlet convey line,

[0006] - said outlet convey line air / gas flow connected by convey lines to the discharge convey line,

[0007] - said system comprising an air / gas pump adapted to generate an air / gas flow through the inlet convey line into the loading unit,

[0008] - and that the system further comprises a control system.

[0009] The invention also relates to a method for collecting and transporting objects through a pneumatic conveying system from at least one loading unit through a discharge convey line to a collecting unit to which the objects are delivered, an air / gas flow is flowing from an inlet convey line into the loading unit(s), and an air / gas pump is pumping air / gas through the inlet convey line, and a control system is controlling the pressure in the pneumatic conveying system.

[0010] Further the invention relates to use of the pneumatic conveying system for performing the method.

[0011] Finally, the invention relates to use of the pneumatic conveying system for a container return system for waste material. This waste material may be items such as empty beverage bottles and cans of any size and material such as, plastic, steel, aluminum, glass, plastic said waste material is recycling waste material. Pneumatic conveying systems are used for transporting different kind of material such as food, com and granulates. Generally, air is blown through pipes via a pressure blower and similar in order to move the material through the pipe. In this way the material in question can be moved from one point to another point.

[0012] US 6164492 B discloses a pneumatic product vending and delivery system. The system transports products such as bottles from a remote storage location to a vending terminal where a costumer may select a specific bottle through a control panel. A blower assists in transporting the bottles through the tube. The system is not adapted for transporting empty packaging such as bottles and cans from a delivery station to a container.

[0013] US 4180354 A discloses a pneumatic tube transmission system for transmitting a carrier in which an object is placed from one terminal to a remote terminal to allow delivery of the carrier into an open remote terminal. When the carrier is being transferred from the first terminal to the remote terminal, the carrier is positioned in the first terminal and the blower is activated to de liver positive pressure air through the first airline. A second airline draws a partial vacuum on the second end of the transmission line at the remote terminal. This forces the carrier to move through the line to the remote terminal where the object is removed from the carrier. The system is not suitable for transporting objects continuously.

[0014] BE 710678 A discloses a pneumatic tube system where a suction in the tube sees to that objects such as bottles are transported through the tube. The system requires that each object is placed in the tube one by one.

[0015] A container return system is generally arranged to collect waste containers for recycling. This may include used emptied beverage bottles and cans, or other waste material. The container return system must collect large numbers of waste material for recycling in a short period of time. In many installations, the container return system delivers the received objects to a backroom receiving facility and the required space here can be considerable. Further it can also require means for sorting and storing the received objects. The space requirement and the complexity cause cost to the system.

[0016] In a typical installation, the crushed or compressed objects are transferred to a box and stored in plastic bags. The plastic bag is replaced when full. This also requires available space to store the full plastic bag and is time consuming. Further the container return system is often stopped when the box is full and an empty one is placed.

[0017] In order to handle recycling packages such as bottles and cans it is common to transport the objects on a transport band. This transport band runs from a delivery station where the customer puts the bottle / can and to a box where the bottles / cans are selected. Such system is known from EP 0612046 A.

[0018] It comprises a front panel a receiving opening for the bottles / cans and a transfer conveyer to transport the bottles / cans to a collecting box.

[0019] These systems are quite time consuming for the customer as the system is fed one by one, that is the customer must wait for the bottle / can to disappear before a new one is fed to the system. Further the collecting boxes are filled in short time and must be replaced by a new one. This is also time requiring and requires staff just for emptying the boxes.

[0020] With other words it is desirable to be able develop an improved convey system for collecting and transporting waste material in such a way that the waste material can be handled without any delay. The waste material is transported away from the delivery station so fast that the user just can empty large portions of the waste material into the delivery station without any risk for overloading the system.

[0021] The present invention seeks generally to improve conveying system for collecting and transporting objects such that the abovementioned insufficiencies and drawbacks of today’s conveying systems are overcome or at least it provides a useful alternative.

[0022] Up to this day, prior art has failed to teach a simple and yet reliable and inexpensive conveying system which in a safe and reliable manner, without substantially increasing the cost of the system, is able to satisfy the abovementioned much desired characteristics of the mentioned conveying system.

[0023] According to the invention, a pneumatic conveying system is provided, as per the introductory part of this specification, and wherein

[0024] - it comprises a pressure blower for providing pressurized gas / air, said pressure blower air / gas flow connecting with the discharge convey line,

[0025] - the pressure blower is by a first convey line air / gas flow connected to an injector and arranged to form a negative air / gas pressure in the outlet convey line,

[0026] - and that the control system is configured to control the air / gas pressure from the pressure blower and the pressure from the air pump, by said pressure the objects pass from a bottom part of the loading unit(s) through the outlet convey line and further through the injector and the discharge convey line into the collecting unit.

[0027] The pressure blower may comprise any type of air-source such as a blower, air pump, fan, or other device capable of creating a pressure differential and for forcing air or other fluid, under pressure, through the convey line. As such, the pressure blower is configured to generate a positive air-pressure for purposes of introducing air into the first convey line and an air flow with a certain laminar flow velocity in the loading unit and for causing an underpressure in the outlet convey line. This causes the objects material introduced into the convey lines to travel through the convey lines. The pressure blower is configured to generate a negative air pressure within the outlet convey line below an ambient atmospheric pressure. The air / gas pump is required to generate a pressure in the inlet convey line. As the waste material - such as empty plastic bottles or cans - drop down in the loading unit and reaches the bottom part of this, the laminar flow in the loading unit caused by the pressure difference between the inlet convey line and the outlet convey line is sucked into the outlet convey line and passes through the injector and further to the discharge convey line. From here it is dropped down into the collecting unit which is typically a big container placed outside the building where the system is placed.

[0028] In this way the convey system can operate nearly through the whole day without any interruptions, as such a container can hold more than 150 times what a bag used in the known systems is capable of. Further the system does not require staff inside the building being responsible for watching the system being full and stopping it each time a box / bag is full. The full container - placed outside the building where the system is placed - is driven directly away without bothering any inside-staff. An additional benefit is that the plastic bags used in the existing systems are not necessary.

[0029] The system combines pneumatic vacuum transport and pneumatic overpressure transport and the control system controls the two pressures in such a way that we have nearly even pressure (0,9-1 bar) in the loading unit, and a laminar flow through the loading unit of around 10-40 m / second. The waste material is in this way pushed into the inlet convey line, where the under-pressure sucks the material to the discharge convey line from where it is dropped down into the container. The injector let the material pass through, while the injector also causes an under-pressure in the outlet convey line, as the pressurized air from the pressure blower passes through the injector.

[0030] There may be more than one loading unit. If two loading units are used, they are connected to each other by a pipe / tube and the inlet convey line is connected to the first loading unit while the outlet convey line is connected to the second loading unit.

[0031] According to one embodiment the injector is gas / air flow connected by a second convey line to the outlet convey line, the injector is further gas / air flow connected to the discharge line, said injector allowing the objects to pass through the injector and leave the injector through the discharge convey line. The pressurized air is passed through the injector and to the discharge convey line, to which it is directly connected. As the injector also have a connection to the outlet convey line of the collecting unit through the second convey line, the flow from the blower through the injector makes an underpressure in the second convey line and thereby in the outlet convey line of the loading unit.

[0032] According to one embodiment the discharge line comprises at least one first portion with a diameter d1 placed directly in connecting with the injector, and a second portion with a diameter d2 placed in a distance to the injector said d2>d1.

[0033] By changing the diameter of the discharge line making it bigger the pressure in the line / tube is reduced. The laminar velocity is around 10-15 m / sec in the region with the diameter d2. Hereby the material falls down into containers in a regulated manner, and without it being pushed out of the system with too much force. It falls quite easily into the container.

[0034] The two regions are connected by a conic transition tube.

[0035] According to one embodiment the control system is adapted to control the pressure in the system in such a way, that a laminar airflow in the loading unit is around 10-40 m / s preferably 20-30 m / s.

[0036] According to one embodiment the pressure in the outlet convey line is below a value of x bar of an ambient atmospheric pressure, and the pressure in the inlet convey line is essentially above same value x bar of an ambient atmospheric pressure.

[0037] The control system sees to that the air flow velocity in the loading unit is suitable, that is around 10-40 m / s, preferably 20-30 m / s and more preferably 25-30 m / s. This is done by regulating the pressure in the inlet convey line and the outlet convey line. When the waste material leaves the loading unit the under-pressure in the outlet convey line sees to, that the waste material is sucked up to the injector and from her is pushed out caused by the airflow from the pressure blower passing through the injector.

[0038] According to one embodiment the loading unit comprises a horizontal tube comprising the bottom part of the loading unit connecting the pneumatic inlet and outlet convey lines directly with each other, and the loading unit further comprises a hopper placed above the tube and connected to the tube and with an opening in the bottom allowing the objects to drop down into the tube through an opening in said tube.

[0039] The tube is typically an integrated part (made in one) of the inlet and outlet conveying lines with an opening in the top for receiving the objects to the bottom part. The loading unit comprises a hopper comprising an opening in the bottom matching the opening of the tube. The hopper is typically connected to the tube by welding the lower edge of the hopper to the outside wall of the tube.

[0040] According to one embodiment the receiving-opening of the loading unit points in the opposite direction of gravity.

[0041] According to one embodiment the loading unit comprises guide plate(s), said guide plate(s) is / are adapted to regulate a flow of air / gas in the bottom part.

[0042] According to one embodiment the guide plate(s) is a displaceable guide plate DGP adapted to be able to be moved in a vertical direction, whereby a part of the DGP is placed in the bottom part, and / or the guide plate is a guide plate adapted to be firmly anchored to the bottom part -a firmly guide plate FGP.

[0043] According to one embodiment comprises the DGP a plate which in an end pointing towards the bottom part is formed semicircular, i.e., essentially congruent with the bottom part, and the DGP by means is adapted to be slidable fastened to a wall of the loading unit and be fixed in a specific position.

[0044] According to one embodiment FGP comprises a plate with a surface parallel to a longitudinal direction of the bottom part and firmly fixed to the inside of the bottom part.

[0045] The DGP comprises a flat and plane plate with one end congruent with the design of the bottom part that is semicircle shaped. The DGP is fastened slidable to a wall of the loading unit and with an attack surface substantially perpendicular or with a certain angle to the flow direction. A longitudinal recess is placed in the DGP and a bolt is placed through the recess and fastened to the wall this making the DGP slidable. By the regulation of the DGP up and down to a specific position the air flow through the loading unit is regulated. Turbulence is then avoided and the DGP contributes to that the air flow is laminar and a flow of supplied objects flows continuously through the loading unit. The DGP may work alone or together with the other guide plate FGP.

[0046] The FGP may also work alone or together with the DGP. The FGP is fixed to the inside of the bottom part. It comprises a plate and a surface of the guide plate is arranged parallel to the longitudinal direction of the bottom part. It is placed close to the outlet convey line. It also contributes to the laminar flow of air in the bottom part in the same way as the DGP does and that turbulence is avoided in the loading unit.

[0047] The guide plates contribute to a laminar flow in the loading unit whereby turbulence is avoided.

[0048] According to one embodiment that the outlet convey line comprises openings placed at the lower part of the wall of the outlet convey line and, in a region, close to the loading unit.

[0049] The system may be contaminated by residues from the waste material.

[0050] Waste containers returned for recycling, such as empty beverage bottles or cans, often contain residual liquids, which may come into contact with the system. In order to clean the system, the outlet convey line has 10-20 openings with a diameter each of 1 -5 mm placed at the lower part of the wall of the outlet convey line. When water is dropped down in the loading unit it is sucked into the outlet convey line and due to the small openings, air from the outside is also sucked into the outlet convey line, working as an injector. This causes the water to atomize and is sucked further into the system cleaning it.

[0051] According to one embodiment the pneumatic conveying system further comprises a compactor adapted to compress and / or puncture the objects before the objects reach the loading unit.

[0052] Before the material is dropped into the loading unit is may be compressed, depending on what material we are talking about. Further, sometimes it is necessary to puncture the material into small pieces, which also can be done before dropping it down into the loading unit.

[0053] According to one embodiment the collecting unit is a container with a spacevolume of at least 2 m3preferably more than 2 m3more preferably more than 10 m3placed at an outlet of the discharge line for catching the objects falling down in said container.

[0054] Using big containers - normally placed outside the building where the system is placed - removes the need to collect the material in bags. The material simply drops down in the container as it is, that is compressed or not compressed. The need to stack bags with the material for recycling is hereby removed.

[0055] The containers the containers can be as large as 6, 5*2, 5*3 m3that is 48,75 m3The container may also be a big plastic bag attached to the outlet. According to one embodiment all the convey lines including the inlet convey line, the outlet convey line and discharge convey line are pneumatic transfer tubes.

[0056] By pneumatic transfer tubes is to understand, that the tubes are transporting under-pressure or over-pressure gas / air and are able to withstand the different pressures.

[0057] According to one embodiment the objects are bottles and cans in can bottle and can deposit recycling systems.

[0058] Deposit recycling means recycling of materials where consumers pay a deposit.

[0059] The invention also concerns a method for collecting and transporting objects through a pneumatic conveying system as described in the introductory part of the description, and where a suction is provided in an outlet convey line connected to the collecting unit, said suction is provided by a pressure blower to which the outlet convey line is air / gas flow connected, the pressure blower blows air / gas through a first convey line through an injector causing the suction in the outlet convey line, a control system is controlling the pressure in the conveying lines so the pressure in the inlet convey system is above an ambient atmospheric pressure, and the pressure in the outlet convey system is below an ambient atmospheric pressure thereby providing an air / gas flow velocity in the loading unit, whereby the objects are moved through the conveying lines into the collecting unit.

[0060] According to one embodiment a second convey line between the injector and the outlet convey line provides the suction in the outlet convey line as the pressurized air from the pressure blower flows through the injector.

[0061] According to one embodiment openings in the outlet convey line provides suction of air from the outside through the openings and the sucked air works as an injector in the lines.

[0062] According to one embodiment a negative pressure or equal pressure is provided in the upper part of the loading unit.

[0063] By having a slight negative pressure in the upper part of the loading unit odor will be sucked out with the material flow.

[0064] According to one embodiment a laminar airflow is obtained around 10-40 m / s preferably 20-30 m / s, and the pressure in the outlet convey line is below x bar of an ambient atmospheric pressure, and the pressure in the inlet convey line is essentially x bar above of an ambient atmospheric pressure.

[0065] According to one embodiment the objects are fed into the loading unit in a continuous stream.

[0066] Brief description of the drawings

[0067] FIG. 1 is a perspective view of a pneumatic conveying system according to the invention.

[0068] FIG. 2A,B is a perspective view of a loading unit used in the pneumatic conveying system shown in fig 1 .

[0069] FIG. 3 is a sectional view through an injector used in the pneumatic conveying system shown in fig 1 .

[0070] Fig 4 A,B shows a top view of the loading unit comprising two different types of guide plates fig 4C,D shows a perspective view of the loading unit comprising one guide plate a displaceable guide plate DGP. fig 4 E shows a top view of the loading unit comprising one guide plate a firmly placed guide plate FGP.

[0071] The invention will be explained with reference to fig. 1 . This shows the system 1 according to the invention, where an object 2 such as a plastic bottle is thrown down in a loading unit 4 for being transported through conveying lines / tubes. The object 2 is typically delivered from a deliverstation placed in a store, where the customer delivers his bottles / cans back to the store in order to have the waste objects 2 recycled. An object 2 is also seen in fig. 1 leaving the system through an outlet 14 of a discharge convey line 7. The objects 2 - delivered to the system 1- are delivered in a continuous flow. The customer may simply empty a whole sack of objects 2 into the deliver-station as the system 1 is able to receive and handle the objects 2 without any delay as the objects 2 leave the loading unit 4 fast one by one.

[0072] The system 1 comprises the loading unit 4 that receives the objects 2. The loading unit 4 is explained in detail with reference to fig 2a, b. The loading unit 4 is physically connected to an inlet convey line 5 - a tube - and an outlet convey line / tube 6. Air / gas is flowing through the inlet convey line 5, the loading unit 4 and the outlet convey line 6. The outlet convey line 6 is flow connecting with an injector 11 through a second convey line 12, which is also air / gas flow connected to the discharge convey line 7. A pressure blower 8 provides pressurized gas / air and is through a first convey line 18 air gas connected with the injector 11 and thereby the discharge convey line 7.

[0073] The pressure blower 8 forms a negative air / gas pressure in the outlet convey line 6 due to the established gas / air flow lines through the injector 11.

[0074] An air / gas pump 9 generates an air / gas flow through the inlet convey line 5 into the loading unit 4. A laminar airflow is then obtained in the loading unit 4: around 10-40 m / s, due to the pressure in the outlet convey line 6 is below x bar of an ambient atmospheric pressure (suction), and the pressure in the inlet convey line 5 is above x bar of an ambient atmospheric pressure. Thereby the objects 2 pass from a bottom part 33 of the loading unit 4 through the outlet convey line 6 and further through the injector 11 and the discharge convey line 7, through the outlet 14 of the discharge convey line 7 into the collecting unit 3. The pressure is controlled by a control system 10.

[0075] The discharge convey line 7 comprises a first portion 15 with a diameter d1 of the tube of around 200 mm placed directly in connecting with the injector 11 . A second portion 16 with a diameter d2 of the tube of around 400 mm is placed in a distance to the injector 11 . The two pieces are connected to each other with a conic transition-tube. By increasing the diameter of the tube close to the outlet 14 the flow velocity of the air / gas is reduced and the objects simply falls down into the container placed under the outlet 14.

[0076] The construction of the loading unit 4 and its relation to the inlet and outlet conveying lines 5,6 will be explained with reference to fig 2a, b. It comprises a hopper 20 physically connected to a horizontal tube 19 comprising the bottom part 33. The horizontal tube 19 comprises the two convey lines 5,6 connecting them directly with each other. The hopper 20 is placed above the tube 19 and is connected directly to the tube 19 and with an opening in the bottom allowing the objects 2 to drop down into the tube 19 to the bottom part 33 through an opening in the tube 19. The whole construction is supported by a frame 21 . The tube 19 act as the bottom of the loading unit / hopper 4,20.

[0077] The outlet convey line 6 comprises openings 17 placed at the lower part of the wall of the outlet convey line 6. They are placed in a region close to the loading unit 4. Air is sucked into the tube 6 due to the under-pressure, and when water is dropped down in the loading unit the water is atomized and sucked through the whole system cleaning it. The loading unit 4 may also comprise one or two guide plates 35 placed in the bottom part 33. This is explained with reference to fig 4a-e. Fig 4 a,b shows a top view of the loading unit 4 comprising two different types of guide plates 35: a displaceable guide plate DGP 36 and a firmly anchored guide plate FGP 37. They may both be placed in relation to the bottom part 33 or only one is placed.

[0078] The DGP 36 is placed close to the inlet convey line 5. This is also shown in fig 4c, d showing a perspective view of the loading unit 4. The guide plate 35,36 comprises a flat and plane plate with one end congruent with the design of the bottom part 33 that is semicircle shaped. The plate 36 is fastened slidable to a wall 27 of the hopper 20. A longitudinal recess 38 is placed in the DGP 36 and a bolt is placed through the recess 38 and fastened to the wall 27 this making the DGP 36 slidable.

[0079] By the regulation of the DGP up and down to a specific position the air flow through the bottom part 33 is regulated. Turbulence is then avoided and contributing to that the air flow is laminar and the flow of supplied objects 2 continuous and without the risk of the system jamming. The DGP may work alone or together with the other guide plate FGP 37.

[0080] The FGP 37 may also work alone. This guide plate 37 is shown in fig 4a, b Fig 4e shows a top view of the loading unit 4 with the guide plate FGP 37 placed in the bottom part 33. The FGP 37 works together with the DGP 36 or as shown in fig. 4 e works alone. It comprises a plate fastened to the inside of the bottom part 33 and a surface of the guide plate 35,37 parallel to the longitudinal direction of the bottom part 33. It is placed close to the pneumatic outlet line 6. It contributes to the laminar flow of air in the bottom part 33 in the same way as the DGP 36 does and that no turbulence takes place in the loading unit 4.

[0081] Fig 3 is a sectional view through the injector 11. The arrows show the airflow through the injector 11 and it also shows an object 2 passing through the injector 11 caused by the suction provided by the airflow - from the pressure blower 8 - through the injector 11 . When the object 2 has passed the injector 11 is pressed out of the conveying line due to the pressurized air / gas from the pressure blower 8.

[0082] The objects may be compressed or punctured by a device such as a compactor / dual roller before they are dropped down in the loading unit 4. This device is not shown in the figures.

Claims

Claims1. A pneumatic conveying system (1 ) for collecting objects (2) and transporting them to a collecting unit (3) through a discharge convey line (7), the system (1 ) comprising- at least one loading unit (4) adapted to receive said objects (2) through a receiving opening and in gas / air flow connection to an inlet convey line (5) and an outlet convey line (6), air / gas flow allowed to pass through the inlet convey line (5), the loading unit(s) (4) and the outlet convey line (6),- said outlet convey line (6) air / gas flow connected by conveying lines to the discharge convey line (7),- said system (1 ) comprising an air / gas pump (9) adapted to generate an air / gas flow through the inlet convey line (5) into the loading unit (4),- and that the system (1 ) further comprises a control system (10) characterized in that it further comprises- a pressure blower (8) for providing pressurized gas / air, said pressure blower (8) air / gas flow connecting with the discharge convey line (7),- the pressure blower (8) is by a first convey line (18) air / gas flow connected to an injector (11 ) and arranged to form a negative air / gas pressure in the outlet convey line (6), and the control system is configured to control the air / gas pressure from the pressure blower (8), and the pressure from the air pump (9), by said pressure the objects pass from a bottom part (33) of the loading unit(s) (4) through the outlet convey line (6) and further through the injector (11 ) and the discharge convey line (7) into the collecting unit (3).

2. A pneumatic conveying system (1 ) according to claim 1 characterized in that the injector (11 ) is gas / air flow connected by a second convey line (12) to the outlet convey line (6), the injector (11 )is further gas / air flow connected to the discharge line (7), said injector (11 ) allowing the objects (2) to pass through the injector (11 ) and leave the injector (11 ) through the discharge convey line (7).

3. A pneumatic conveying system (1 ) according to claim 1 or 2 characterized in that the discharge convey line (7) comprises at least one first portion (15) with a diameter d1 placed directly in connecting with the injector (11 ) and a second portion (16) with a diameter d2 placed in a distance to the injector (11 ) said d2>d1 .

4. A pneumatic conveying system (1 ) according to any of the previous claims characterized in the control system (10) is adapted to control the pressure in the system (1 ) in such a way, that a laminar airflow in the loading unit (4) is around 10-40 m / s preferably 20-30 m / s,5. A pneumatic conveying system (1 ) according to any of the previous claims characterized in the pressure in the outlet convey line (6) is below a value of x bar of an ambient atmospheric pressure, and the pressure in the inlet convey line (5) is essentially above same value x bar of an ambient atmospheric pressure.

6. A pneumatic conveying system (1 ) according to any of the previous claims characterized in that it comprises a horizontal tube (19) comprising the bottom part (33) of the loading unit (4) and connecting the inlet and outlet convey lines (5,6) directly with each other, and the loading unit (4) further comprises a hopper (20) placed above the tube (19) and connected to the tube (19) and with an opening in the bottom, allowing the objects (2) to drop down into the tube (19) through an opening in said tube (19).

7. A pneumatic conveying system (1 ) according to any of the previous claims characterized in that the receiving-opening of the loading unit (4) points in the opposite direction of gravity.A pneumatic conveying system (1 ) according to any of the previous claims characterized in that the loading unit (4) comprises guide plate(s) (35), said guide plate(s) (35) is / are adapted to regulate a flow of air / gas in the bottom part (33). A pneumatic conveying system (1 ) according to claim 8 characterized in that the guide plate(s) (35) is / are a displaceable guide plate DGP (36) adapted to be able to be moved in a vertical direction, whereby a part of the DGP (36) is placed in the bottom part (33), and / or the guide plate (35) is a guide plate (35) adapted to be firmly anchored to the bottom part (33) -a firmly guide plate FGP (37). A pneumatic conveying system (1 ) according to claim 8 or 9 characterized in that the DGP (36) comprises a plate which in an end pointing towards the bottom part (33) is formed semicircular, i.e. , essentially congruent with the bottom part (33), and the DGP (36) by means (38) is adapted to be slidable fastened to a wall of the loading unit (4) and be fixed in a specific position. A pneumatic conveying system (1 ) according to claim 8,9 or 10 characterized in that the FGP (37) comprises a plate with a surface parallel to a longitudinal direction of the bottom part (33) and firmly fixed to the inside of the bottom part (33). A pneumatic conveying system (1 ) according to any of the previous claims characterized in that the outlet convey line (6) comprises openings (17) placed at the lower part of the wall of the outlet convey line (6) and in a region, close to the loading unit (4). A pneumatic conveying system (1 ) according to any of the previous claims characterized in that the pneumatic conveying system (1 ) further comprises a compactor such as a dual roller adapted to compress and / or puncture the objects (2) before the objects (2) reachthe loading unit (4). A pneumatic conveying system (1 ) according to any of the previous claims characterized in that the collecting unit (3) is a container with a space-volume of at least 2 m3, preferably more than 2 m3, more preferably more than 10 m3, placed at an outlet (14) of the discharge convey line (7) for catching the objects (2) falling down in said container (3). A pneumatic conveying system (1 ) according to any of the previous claims characterized in that all the convey lines including the inlet convey line (5), the outlet convey line (6) and discharge convey line (7) are pneumatic transfer tubes. A pneumatic conveying system according to any of the previous claims characterized in that the objects (2) are bottles and cans in can bottle and can deposit recycling systems. Method for collecting and transporting objects (2) through a pneumatic conveying system (1 ) from at least one loading unit (4) through a discharge convey line (7) to a collecting unit (3) to which the objects are delivered, an air / gas flow is flowing from an inlet convey line (5) into the loading unit(s) (4) and an air / gas pump (9) is pumping air / gas through the inlet convey line (5), and a control system (10) is controlling the pressure in the pneumatic conveying system (1 ) characterized in a suction is provided in an outlet convey line (6) connected to the loading unit (4) said suction is provided by a pressure blower (8) to which the outlet convey line (6) is air / gas flow connected,and the pressure blower (8) blows air / gas through a first convey line (18), through an injector (11 ) causing the suction in the outlet convey line (6), the control system (10) is controlling the pressure in the conveying lines so the pressure in the inlet convey system (5) is above an ambient atmospheric pressure, and the pressure in the outlet convey line (6) is below an ambient atmospheric pressure providing an air / gas flow velocity in the loading unit (4), whereby the objects (2) are moved through the conveying lines into the collecting unit (3). Method according to claim 17 characterized in that a second convey line (12) between the injector (11 ) and the outlet convey line (6) provides a suction in the outlet convey line (6) as the pressurized air from the pressure blower (8) flows through the injector (11 ). Method according to claim 17 or 18 characterized in that openings (17) in the outlet convey line (6) provides suction of air from the outside through the openings (17) and the sucked air works as an injector in the lines. Method according to claim 17,18 or 19 characterized in that a negative pressure or an equal pressure is provided in the upper part of the loading unit (4). Method according to claim 17, 18, 19 or 20 characterized in that a laminar airflow is obtained around 10-40 m / s preferably 20-30 m / s, and the pressure in the outlet convey line (6) is below x bar of an ambient atmospheric pressure, and the pressure in the inlet convey line (5) is essentially x bar above of an ambient atmospheric pressure. Method according to claim 17,18,19,20 or 21 characterized in that the objects (2) are fed into the loading unit (4) in a continuous stream.

23. Use of the pneumatic conveying system (1 ) according to claims 1 -16 for performing the method according to claims 17-22 24. Use of a pneumatic conveying system (1 ) according to claim 1 -23 for a container return system for waste material such as empty beverage bottles and cans of any size.

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