Pneumatic material conveying system and method

Abstract

A pneumatic material conveying system (1) comprising a first gravity chute (4) which is fluidly connectable to a par-tial-vacuum generator (3), the first gravity chute (4) com-prising a number of first input points (6) via which a first material fraction is arranged to be fed into the first gravity chute (4), and arresting means (8) arranged between two first feed apertures (7) of the first input points (6). The arresting means (8) has two positions, a first position, in which the arresting means (8) extends into the channel space (5) of the first gravity chute (4) and prevents the displacement of the first material fraction fed from the first feed aperture (7) higher up past the arresting means (8) in the channel space (5), and a second position, in which the arresting means (8) allows the displacement of the first material fraction past the arresting means (8) in the channel space (5). The pneumatic material conveying sys-tem (1) comprises a second gravity chute (15), which is fluidly connectable to the partial-vacuum generator (3), the second gravity chute (15) comprising a number of second input points (17) via which second material frac-tion is arranged to be fed into the second gravity chute (15), a connecting channel (22) fluidly connecting the channel space (5) of the first gravity chute (4) to the channel space (16) of the second gravity chute (15), an air duct (19) connected to the channel space (16) of the second gravity chute (15) for ventilating the channel space (5) of the first gravity chute (4) and / or for conducting make-up air into the channel space (16) of the second gravity chute (15) and into the channel space (5) of the first gravity chute (4) via the channel space (16) of the second gravity chute (15) and the connecting channel (22).

Description

PNEUMATIC MATERIAL CONVEYING SYSTEM AND METHOD Field of the invention The invention relates to a pneumatic material conveying system according to the preamble of claim 1. The invention also relates to a method for feeding and conveying material. Background of the inventionThe invention relates generally to material conveying systems, such as to pneumatic partial-vacuum conveying systems, particularly to the collection and conveying of wastes, such as to the conveying of household wastes. Such systems are presented e.g. in publications WO 2009 / 080880, WO 2009 / 080881, WO 2009 / 080882, WO 2009 / 080883, WO 2009 / 080884, WO 2009 / 080885, WO 2009 / 080886, WO 2009 / 080887 and WO 2009 / 080888.  Systems wherein wastes are conveyed in piping by means of a pressure difference or suction are known in the art. In these systems, the wastes are conveyed for long distances in the piping by vacuum. It is typical to these systems that a partial-vacuum generator is used to achieve the pressure difference, in which system a negative pressure is brought about in the conveying piping with partial-vacuum generators, such as with vacuum pumps or with an ejector apparatus. The conveying piping typically comprises at least one valve means which is opened and closed to regulate the replacement air coming into the conveying piping. Waste input points, for example waste chutes, are used in the systems at the waste material input end, into which waste input points the material, such as waste material, is fed and from which waste input points the material is conveyed into the conveying piping by opening a discharge valve means, in which case, by means of the vacuum achieved by means of a partial vacuum acting in the conveying piping and also by means of the surrounding air pressure acting via the waste chute, material such as for example waste material packed into bags, is conveyed from the waste chute into the conveying piping and onwards to a reception point, where the waste material to be transported is separated from the transporting air and conveyed for further processing or for example into a transport container. The pneumatic waste conveying system can be utilized particularly well in densely populated urban areas. These types of areas have tall buildings, in which the input of wastes into the pneumatic conveying system is performed via an input point arranged in the building.  The problem in the prior art configurations is that when feeding different material fractions in conveying systems in which one waste chute is used for transporting the different material fractions in a sorted manner, the user may have to wait at the input point that a specific material fraction may be fed for transportation. This is a particular problem especially in tall buildings or in vessels in which material is fed simultaneously into a common waste chute from different input points thereof.  The object of this invention is to provide a pneumatic material conveying system and method, by which the above problems may be reduced.  Brief description of the invention The object of the invention may be achieved by the pneumatic material conveying system according to claim 1 and a method according to claim 11. The pneumatic material conveying system according to the invention comprises a first gravity chute having a channel space and a delivery end which is fluidly connectable to a partial-vacuum generator. The first gravity chute comprises a number of first input points arranged at a vertical distance from each other, each first input point comprising a first feed aperture via which a first material fraction is arranged to be fed into the channel space of the first gravity chute. The first gravity chute comprises arresting means arranged between two first feed apertures, which are arranged at a vertical distance from each other, and / or below the lowermost first feed aperture. The arresting means has two positions, a first position, in which the arresting means extends into the channel space and prevents the displacement of the first material fraction fed from the first feed aperture higher up past the arresting means in the channel space, in which case the first material fraction collects in the channel space on the arresting means, and a second position, in which the arresting means allows the displacement of the first material fraction past the arresting means in the channel space towards the delivery end of the fist gravity chute. In the first gravity chute the first material fraction is configured to be conveyed from the first input points toward the delivery end by means of gravity and / or suction generated by a partial-vacuum generator. The pneumatic material conveying system further comprises a second gravity chute having a channel space and a delivery end, which is fluidly connectable to the partial-vacuum generator. The second gravity chute comprises a number of second input points arranged at a vertical distance from each other. Each second input point comprises a second feed aperture via which second material fraction is arranged to be fed into the channel space of the second gravity chute. The material conveying system comprises a connecting channel fluidly connecting the channel space of the first gravity chute to the channel space of the second gravity chute, an air duct connected to the channel space of the second gravity chute for ventilating the channel space of the first gravity chute and / or for conducting make-up air into the channel space of the second gravity chute and / or into the channel space of the first gravity chute via the channel space of the second gravity chute and the connecting channel. In the method for feeding and conveying material in a pneumatic material conveying system, a first material fraction is fed via the first feed apertures of the first input points into the channel space of the first gravity chute, the first material fraction is conveyed from the first apertures toward the delivery end of the first gravity chute by means of gravity and / or suction generated by a partial-vacuum generator of the pneumatic material conveying system. Second material fraction is fed via the second feed apertures of the second input points into the channel space of the second gravity chute, make-up air is conducted via the air duct, the channel space of the second gravity chute and the connecting channel into the channel space of the first gravity chute when first material fraction is being removed from the first gravity chute by means the partial-vacuum generator, and make-up air is conducted via the air duct into channel space of the second gravity chute when second material fraction is being removed from the second gravity chute by means of the partial-vacuum generator, and / or that the channel space of the first gravity chute is ventilated via the connecting channel(s), the channel space of the second gravity chute and the air duct. The solution according to the invention has many significant advantages.  By means of the connecting channel(s) the channel space of the first gravity chute may be ventilated when the hatches of the first input points of the first gravity chute are opened and material is fed into the first input point. Air is conducted via the open hatch, the channel space of the first gravity chute, the connecting channel(s), the channel space of the second gravity chute into the air duct of the second gravity chute. The ventilation reduces the amount of odour entering the building through the open hatch.  Moreover, make-up air may be conducted via the air duct of the second gravity chute, channel space of the second gravity chute and connecting channel(s) into the channel space of the first gravity chute during the removal of the first material fraction from the first gravity chute. If the first gravity chute comprises a number of arresting means on which first material fraction is collected, make-up air may be conducted through the connecting channel into the channel space part above the arresting means when said arresting means are moved from the first position to the second position and first material fraction is removed from the delivery end of the first gravity chute by the partial-vacuum generator. This is advantageous because the first material fraction, which collects on the arresting means, may prevent the conducting of the make-up air into the channel space via the air channel in the upper part of the first gravity chute. Make-up air conducted via the connecting channel(s) into the channel space of the first gravity chute also makes it easier for the first material fraction to fall to the lower part of the channel space of the first gravity chute when the arresting means are moved from the first position to the second position.  In this application, the mainly vertical gravity chute may also mean a gravity chute arranged in a direction different from the vertical direction, or it may have parts differing from the vertical direction.  Brief description of the figures The invention will now be described in more detail by way of example with reference to the accompanying drawings, in which Fig. 1 shows a pneumatic material conveying system according to an embodiment of the invention,  Fig. 2 shows a first gravity chute and a second gravity chute of the pneumatic material conveying system of fig. 1 when the first gravity chute is ventilated via the second gravity chute, Fig. 3 shows the first gravity chute and the second gravity chute of the pneumatic material conveying system of fig. 1 when first material fraction is being removed from the first gravity chute, Fig. 4 shows the first gravity chute and the second gravity chute of the pneumatic material conveying system of fig. 1 when third material fraction is being removed from the first gravity chute,  Fig. 5 shows the first gravity chute and the second gravity chute of the pneumatic material conveying system of fig. 1 when second material fraction is being removed from the second gravity chute, and Fig. 6 shows three gravity chutes which can be used in the pneumatic material conveying system of fig. 1.   Detailed description of the inventionFig. 1 is a simplified diagram illustrating a pneumatic material conveying system 1 according to an embodiment of the invention. The pneumatic material conveying 1 system is arranged to convey different material fractions, such as waste material fractions, from gravity chutes 4, 15 to containers 2.1-2.3, such as waste containers or transport containers, by means of suction / negative pressure generated by the partial-vacuum generator 3. The material fractions may be packed into bags. Each material fraction is conveyed to a different container 2.1-2.3. The pneumatic material conveying system 1 comprises one or more containers 2.1-2.3 for each material fraction. The pneumatic material conveying system 1 also comprises one or more partial-vacuum generators 3. The partial-vacuum generator 3 may be a blower, vacuum pump or ejector apparatus. The pneumatic material conveying system 1 may comprise a dust cyclone 31 arranged upstream of the partial-vacuum generator(s) 3 and downstream of the containers 2.1-2.3. The dust cyclone 31 separates particles from the air flowing from the containers 2.1-2.3 to the partial-vacuum generator(s) 3. The pneumatic material conveying system 1 also comprises conveying piping 25 which fluidly connects the gravity chutes 4, 15 to the containers 2.1-2.3 and the containers 2.1-2.3 to the partial-vacuum generator(s) 3. The conveying piping 25 is provided with valves 32 for guiding different material fractions to respective containers 2.1-2.3. The pneumatic material conveying system 1 comprises a first gravity chute 4, such as a first gravity pipe. The first gravity chute 4 comprises a channel space 5 and a delivery end 33, which is fluidly connected / connectable to one or more containers 2.1-2.3 and the suction side of the partial-vacuum generator 3 via the material conveying piping 25. Moreover, the first gravity chute 4 comprises a number of first input points 6 arranged at a vertical distance from each other. The first input points 6 are arranged on the different floors of a building or vessel. The first input points 6 may be arranged in connection with the vertical wall. Each first input point 6 comprises a first feed aperture 7 via which a first material fraction is arranged to be fed into the channel space 5 of the first gravity chute 4. Moreover, each first input point 6 comprises an openable and closable first hatch 26 or the like. In the closed position the first hatch 26 blocks the connection from the outside of the input point 6 via the first feed aperture 7 to the channel space 5 of the first gravity chute 4. In the open position the first hatch 26 enables the feeding of first material fraction from the outside of the first input point 6 via the first feed aperture 7 into the channel space 5 of the first gravity chute 4.  The part of the first gravity chute 4, which comprises the first input points 6 and the first feed apertures 7, is mainly vertical or vertical. Thus, the first material fraction is conveyed from the first input points 6 toward the delivery end 33 by means of gravity and / or suction generated by a partial-vacuum generator 3. The suction side of the partial-vacuum generator 3 is in fluid flow connection with the first gravity chute 4. The first material fraction may be waste material, such as domestic waste. The first gravity chute 4 comprises at least one arresting means 8 arranged between the first feed apertures 7 of two first input points 6, which are arranged at a vertical distance from each other. Typically, the first gravity chute 4 comprises a number of arresting means 8 arranged at a vertical distance from each other, typically in the sections between each two first feed apertures 7, which are arranged at a vertical distance from each other, and / or below the lowermost first feed aperture 7. The arresting means 8 has two positions, a first position, in which the arresting means 8 extends into the channel space 5 and prevents the displacement of the first material fraction fed from the first input point 6 higher up past the arresting means 8 in the channel space 5. In this case, first material fraction is collected in the channel space 5 on the arresting means 8 so that first material fraction is supported by the arresting means 8. Moreover, the arresting means 8 has a second position, in which the arresting means 8 allows the displacement of the first material fraction past the arresting means 8 in the channel space 5 towards the delivery end 33 of the fist gravity chute 4. The arresting means 8 may comprise drive device and a valve, plate, rod, fork, spike or pipe, which is movable by the drive device.  The arresting means 8 are configured to displace from the first position to the second position in phases, starting from the lowermost arresting means 8 that is in the first position and transferring always from the preceding to the next lowermost arresting means 8 until all the arresting means 8 of the first gravity chute 4 have been moved from the first position into the second position. The first gravity chute 4 may comprise a number of third input points 9 arranged at a vertical distance from each other. The third input points 9 are arranged on the different floors of a building or vessel. The third input points 9 may be arranged in connection with the vertical wall. Each third input point 9 comprises a feed-in container 10 and a third feed aperture 11 via which third material fraction is arranged to be fed into the channel space 5 of the first gravity chute 4. The feed-in container 10 is configured to temporarily store third material fraction before being fed into the channel space 5 via the third feed aperture 11. Each feed-in container 10 comprises a stopper 12 which prevents in a first operating position the passage of the third material fraction from the feed-in container 10 via the third feed aperture 11 into the channel space 5 of the first gravity chute 4 and in a second operating position allows the third material fraction to pass from the feed-in container 10 via the third feed aperture 11 into the channel space 5 of the first gravity chute 4. The stopper 12 may comprise an actuator and a plate, rod, fork or pipe, which is movable by the actuator. Moreover, each third input point 9 may comprise an openable and closable third hatch 28 or the like. In the closed position, the third hatch 28 blocks the connection from the outside of the third input point 9 via the third feed aperture 11 to the channel space 5 of the first gravity chute 4. In the opened position the third hatch 28 enables the feeding of third material fraction from the outside of the third input point 11 via the third feed aperture 11 into the channel space 5 of the first gravity chute 5 or at least enables the feeding of third material fraction from the outside of the third input point 11 into the feed-in container 10. The first gravity chute 4 may comprise an air channel 13 connected to the upper end of the channel space 5 of the first gravity chute 4. The air channel 13 is configured to ventilate the channel space 5 of the first gravity chute 4 and / or to conduct make-up air into channel space 5 of the first gravity chute 4 when first material fraction and / or third material fraction is being removed from the first gravity chute 4 by means of the partial-vacuum generator 3. The air channel 13 may be in flow connection with ambient air. The air channel 13 may be provided with a fan which is configured to suck air from the channel space 5 of the first gravity chute 4. The fan is arranged to keep the channel space 5 of the first gravity chute 4 under a negative pressure and to ventilate it. The air channel 13 may be provided a channel valve 13.1 by which the air flow through the air channel 13 can be adjusted, for example prevented and allowed. The first gravity chute 4 may comprise a replacement air channel 14 which may be provided with a valve means, such as a flap arrangement. The replacement air channel 14 may be arranged at a lower part of the first gravity chute 4, for example below the lowermost arresting means 8 and / or below the lowermost first input point 6. The pneumatic material conveying system 1 further comprises a second gravity chute 15, such as a second gravity pipe. The second gravity chute comprises a channel space 16 and a delivery end which is fluidly connected / connectable to one or more containers 2.1-2.3 and to the suction side of the partial-vacuum generator 3 via material conveying piping 25. The second gravity chute 15 further comprises a number of second input points 17 arranged at a vertical distance from each other. The second input points 17 are arranged on the different floors of a building or vessel. The second input points 17 may be arranged in connection with the vertical wall. Each second input point 17 comprises a second feed aperture 18 via which second material fraction is arranged to be fed into the channel space 16 of the second gravity chute 15. The part of the second gravity chute 15, which comprises the second input points 17, is mainly vertical or vertical. Thus, the second material fraction is conveyed from the second input points 17 toward the delivery end by means of gravity and / or suction generated by the partial-vacuum generator 3. The second material fraction may be waste material, such as biowaste. The second material fraction is different from the first material fraction. The inner diameter of the second gravity chute 15 may be smaller than that the first gravity chute 4. The second gravity chute 15 is arranged at a horizontal distance from the first gravity chute 4.  Each second input point 17 may comprise a second feed-in container 20 in which second material fraction is temporarily stored before being fed into the channel space 16 of the second gravity chute 15 via the second feed aperture 18. Each second feed-in container 20 comprises a second stopper 24 which prevents in a first operating position the passage of the second material fraction from the second feed-in container 20 via the second feed aperture 18 to the channel space 16 of the second gravity chute 15 and in a second operating position allows the second material fraction to pass from the second feed-in container 20 via the second feed aperture 18 to the channel space 16 of the second gravity chute 16. The second stopper 24 may comprise an actuator device and a plate, rod, fork or pipe, which is movable by the actuator. Moreover, each second input point 17 may comprise an openable and closable second hatch 27 or the like. In the closed position, the second hatch 27 blocks the connection from the outside of the second input point 17 via the second feed aperture 18 to the channel space 16 of the second gravity chute 15. In the opened position the second hatch 27 enables the feeding of second material fraction from the outside of the second input point 17 via the second feed aperture 18 into the channel space 16 of the second gravity chute 15 or at least into the second feed-in container 20. The second gravity chute 15 may comprise a make-up air channel 21 which may be provided with a valve means, such as a flap arrangement. The make-up air channel 21 may be arranged at a lower part of the second gravity chute 15, for example below the lowermost second input point 17.  The pneumatic material conveying system 1 further comprises at least one connecting channel 22, such a connecting pipe, which fluidly connects the channel space 5 of the first gravity chute 4 above the arresting means 8 to the channel space 16 of the second gravity chute 15. If the first gravity chute 4 comprises a number of arresting means 8 arranged at a vertical distance from each other, the pneumatic material conveying system may comprise 1 a number of connecting channels 22 arranged at a vertical distance from each other, for example a separate connecting channel 22 for each arresting means 8. In this case, the connecting channels 22 fluidly connect the channel space parts of the first gravity chute 4 between each two arresting means 8 and / or the channel space part above the uppermost arresting means 8 to the channel space 16 of the second gravity chute 15. Each connecting channel 22 may be provided with a control device 23, such a control valve or damper, by which the air flow through the connecting channel 22 may be adjusted, e.g. prevented and allowed.  The second gravity chute 15 comprises an air duct 19 connected to the upper end of the channel space 16 of the second gravity chute 15. The air duct 19 may be in flow connection with ambient air. The air duct 19 may be provided with a second fan arranged to suck air from the channel space 16 of the second gravity chute 15. The second fan is configured to keep the channel space 16 of the second gravity chute 15 and / or the channel space 5 of the first gravity chute 4 under a negative pressure, i.e. at a pressure which is lower than the air pressure outside the first input point 6, third input point 9 and the second input point 17. Thus, the first gravity chute 4 is ventilated when the first hatch 26 and / or third hatch 28 of the first gravity chute 4 is opened. Air is sucked via the first hatch 26 / third hatch 28 into the first gravity chute 4 and via the connecting channel(s) 22 into the second gravity chute 15 and removed from the second gravity chute 15 via the air duct 19. The second gravity chute 15 is ventilated when the second hatch 27 of the second gravity chute 15 is opened. Air is sucked via the second hatch 27 into the second gravity chute 15 and removed from the second gravity chute 15 via the air duct 19. The air duct 19 may be provided a duct valve 19.1 by which the air flow through the air duct 19 can be adjusted, for example prevented and allowed. Make-up air is arranged to be conducted into the channel space 5 of the first gravity chute 4 via the air duct 19, the channel space 16 of the second gravity chute 15 and the connecting channel(s) 22 when arresting means 8 are moved from the first position to the second position and / or during the removal the first material fraction from the first gravity chute 4 by means of the partial-vacuum generator 3. Moreover, make-up air is arranged to be conducted into the channel space 16 of the second gravity chute 15 via the air duct 19 during the removal the second material fraction from the second gravity chute 15 by means of the partial-vacuum generator 3. The channel space 5 of the first gravity chute 4 is ventilated via the connecting channel(s) 22, the channel space 16 of the second gravity chute 15 and the air duct 19 when first and third material fractions are not removed from said channel space by the partial-vacuum generator 3. The channel space 16 of the second gravity chute 15 is ventilated by via the air duct 19 when second material fraction is not removed from said channel space. As shown in fig. 6, the pneumatic material conveying system 1 may comprise a further first gravity chute 4’ having a similar structure as the first gravity chute 4. The pneumatic material conveying system 1 may comprise at least one second connecting channel 29, such a second connecting pipe, which fluidly connects the channel space 5’ of the further first gravity chute 4’ above the arresting means 8’ to the channel space 16 of the second gravity chute 15. If the further first gravity chute 4’ comprises a number of arresting means arranged at a vertical distance from each other, the material conveying system 1 may comprise a number of second connecting channels 29 arranged at a vertical distance from each other, for example a separate second connecting channel 29 for each arresting means. In this case, the second connecting channels 29 fluidly connect the channel space parts of the further first gravity chute between each two arresting means and / or above the uppermost arresting means to the channel space 16 of the second gravity chute 15. Each second connecting channel 29 may be provided with a second control device 30, such a control valve or damper, by which the air flow through the second connecting channel 29 may be adjusted, e.g. prevented and allowed.  The pneumatic material conveying system 1 may be operated as follows.  The arresting means 8 are moved to the first positions. First material fraction is fed from the first feed apertures 7 of the first input points 6 into the channel space 5 of the first gravity chute 4. The first material fraction is collected in the channel space 5 on the arresting means 8 such that the first material fraction is supported by the arresting means 8. Third material fraction is fed into the feed-in containers 10 of the third input points 9 and temporarily stored in the feed-in containers 10. As shown in fig. 2, the control devices 23 of the connecting channels 22 are in open positions, i.e. the air flow through said connecting channels 22 is allowed. The channel space 5 of the first gravity chute 4 is ventilated via the connecting channels 22, the channel space 16 of the second material conveying pipe 15 and the air duct 19 when the first hatch 26 and / or third hatch 28 is open. The channel space 5 of the first gravity chute 4 is ventilated via the connecting channels 22 when first and / or third material fractions are not removed from the first gravity chute 4 by the partial-vacuum generator 3. The channel space 16 of the second gravity chute 15 is ventilated via air duct 19. The channel space 16 of the second gravity chute 15 is ventilated when second material fraction is not removed from the second gravity chute 15 by the partial-vacuum generator 3. As shown in fig. 3, when the first material fraction is removed from the channel space 5 of the first gravity chute 4, the arresting means 8 are moved from the first position to the second position in phases, starting from the lowermost arresting means 8 that is in the first position and transferring always from the preceding to the next lowermost arresting means until all the arresting means 8 of the first gravity chute 4 have been moved from the first position into the second position. The first material fraction is removed from the first gravity chute 4 by the partial-vacuum generator 3. Thereafter, the first material fraction is conveyed via the material conveying piping 25 into the first container 2.1. When the first material fraction is being removed from the first gravity chute 4, make-up air is conducted via the air duct 19, the channel space 16 of the second gravity chute 15 and the connecting channel(s) 22 into the channel space part of the first gravity chute 4, which is between the uppermost arresting means 8, which is in the second position, and the lowermost arresting means 8, which is in the first position. The control devices 23 of the upper or other connecting channels 22 may be in closed positions, i.e. the air flow through said connecting channels 22 is prevented. Make-up air is also conducted into the channel space 5 of the first gravity chute 4 via the replacement air channel 14 and / or the air channel 13.  Thereafter, as shown in fig. 4, third material fraction is fed from the feed-in containers 10 of the third input points 9 into the channel space 5 of the first gravity chute 4 by moving the stoppers 12 from the first operating position to the second operating position. Third material fraction is removed from the first gravity chute 4 by the partial-vacuum generator 3. Thereafter, the third material fraction is conveyed via material conveying piping 25 into the third container 2.3. When third material fraction is being removed from the first gravity chute 4, the control devices 23 of the connecting channels 22 are in closed positions, i.e. the air flow through the connecting channels 22 is prevented. Make-up air is conducted into the channel space 5 of the first gravity chute 4 via the air channel 13 and / or the replacement air channel 14.  As shown in fig. 5, second material fraction is fed from the second feed-in containers 20 of the second input points 17 into the channel space 16 of the second gravity chute 15 by moving the second stoppers 24 from the first operating position to the second operating position. Second material fraction is removed from the channel space 16 of the second gravity chute 15 by the partial-vacuum generator 3. Thereafter, the second material fraction is conveyed via material conveying piping 25 into the second container 2.2. When second material fraction is being removed from the second gravity chute 15, the control devices 23 of the connecting channels 22 are in closed positions, i.e. the air flow through the connecting channels 22 is prevented. Make-up air conducted into the channel space 16 of the second gravity chute 15 via the air duct 19 and / or the make-up air channel 21. If the pneumatic material conveying system comprises a further first gravity chute 4’, material fractions may be removed the further first gravity chute 4’ in a similar manner as from the first gravity chute 4. Thereafter, the material fractions are conveyed via the material conveying piping 25 into their respective containers. When the material fractions are being removed from the further first gravity chute, make-up air is conducted via the air duct 19, the channel space 16 of the second gravity chute 15 and the second connecting channels 29 into the channel space of the further first gravity chute 4’. The channel space of the further first gravity chute 4’ is ventilated via the second connecting channel 29, the channel space 16 of the second gravity chute 15 and the air duct 19.  The invention relates to a pneumatic material conveying system 1 comprising a first gravity chute 4 having a channel space 5 and a delivery end 33 which is fluidly connectable to a partial-vacuum generator 3. The first gravity chute 4 comprises a number of first input points 6 arranged at a vertical distance from each other, each first input point 6 comprising a first feed aperture 7 via which a first material fraction is arranged to be fed into the channel space 5 of the first gravity chute 4. The material conveying system 1 comprises arresting means 8 arranged between two first feed apertures 7, which are arranged at a vertical distance from each other, and / or below the lowermost first feed aperture 7. The arresting means 8 has two positions, a first position, in which the arresting means 8 extends into the channel space 5 and prevents the displacement of the first material fraction fed from the first feed aperture 7 higher up past the arresting means 8 in the channel space 5, in which case the first material fraction collects in the channel space 5 on the arresting means 8, and a second position, in which the arresting means 8 allows the displacement of the first material fraction past the arresting means 8 in the channel space 5 towards the delivery end 33 of the fist gravity chute 4. In the first gravity chute 4 the first material fraction is configured to be conveyed from the first input points 6 toward the delivery end 33 by means of gravity and / or suction generated by a partial-vacuum generator 3. The pneumatic material conveying system 1 further comprises a second gravity chute 15 having a channel space 16 and a delivery end 34, which is fluidly connectable to the partial-vacuum generator 3. The second gravity chute 15 comprises a number of second input points 17 arranged at a vertical distance from each other, wherein each second input point 17 comprises a second feed aperture 18 via which second material fraction is arranged to be fed into the channel space 16 of the second gravity chute 15. The material conveying system comprises a connecting channel 22 fluidly connecting the channel space 5 of the first gravity chute 4 to the channel space 16 of the second gravity chute 15, an air duct 19 connected to the channel space (16) of the second gravity chute 15 for ventilating the channel space 5 of the first gravity chute 4 and / or for conducting make-up air into the channel space 16 of the second gravity chute 15 and / or into the channel space 5 of the first gravity chute 4 via the channel space 16 of the second gravity chute 15 and the connecting channel 22. According to an embodiment, make-up air is arranged to be conducted into the channel space 5 of the first gravity chute 4 via the air duct 19, the channel space 16 of the second gravity chute 15 and the connecting channel 22 during the removal the first material fraction from the first gravity chute 4 by means of the partial-vacuum generator 3, and make-up is arranged to be conducted into the channel space 16 of the second gravity chute 15 via the air duct 19 during the removal the second material fraction from the second gravity chute 15 by means of the partial-vacuum generator 3.  According to an embodiment, the connecting channel 22 fluidly connects the channel space 5 of the first gravity chute 4 above the arresting means 8 to the channel space 16 of the second gravity chute 15. According to an embodiment the first gravity chute 4 comprises a number of arresting means 8 arranged at a vertical distance from each other, typically in sections between each two first feed apertures 7, which are arranged at a vertical distance from each other, and / or below the lowermost first feed aperture 7.  According to an embodiment, the material conveying system comprises 1 a number of connecting channels 22 fluidly connecting the channel space 16 of the second gravity chute 15 to the channel space parts of the first gravity chute 4 between each two arresting means 8 and / or to the channel space part above the uppermost arresting means 8.  According to an embodiment, the arresting means 8 are configured to displace from the first position into the second position in phases, starting from the lowermost arresting means 8 that is in the first position and transferring always from the preceding to the next lowermost arresting means 8 until all the arresting means 8 of the first gravity chute 4 have been moved from the first position to the second position. According to an embodiment, the first gravity chute 4 comprises a number of third input points 9 arranged at a vertical distance from each other, wherein each third input point 9 comprises a third feed aperture 11 and a feed-in container 10 via which third material fraction is arranged to be fed into the channel space 5 of the first gravity chute 4. According to an embodiment, each feed-in container 10 comprises a stopper 12 which prevents in a first operating position the passage of the third material fraction from the feed-in container 10 via the third feed aperture 11 to the channel space 5 of the first gravity chute 4 and in a second operating position releases the third material fraction to pass from the feed-in container 10 via the third feed aperture 11 to the channel space 5 of the first gravity chute 4. According to an embodiment, the material conveying system 1 comprises a further first gravity chute 4’ having a similar structure as the first gravity chute 4, and at least one second connecting channel 27 fluidly connecting the channel space 5’ of the further first gravity chute 4’ above the arresting means 8’ to the channel space 16 of the second gravity chute 15.  According to an embodiment, the further first gravity chute 4’ comprises a number of arresting means 8’ and material conveying system 1 comprises a number of second connecting channels 27 fluidly connecting the channel space 16 of the second gravity chute 15 to the channel space parts of the further first gravity chute 4’ between the arresting means 8’, which are arranged at a vertical distance from each other, and / or to the channel space part above the uppermost arresting means 8’.  The invention also relates to a method for feeding and conveying material in a pneumatic material conveying system 1, in which method first material fraction is fed via the first feed apertures 7 of the first input points 6 into the channel space 5 of the first gravity chute 4, the first material fraction is conveyed from the first apertures 7 toward the delivery end (33) of the first gravity chute 4 by means of gravity and / or suction generated by a partial-vacuum generator 3 of the pneumatic material conveying system 1. Second material fraction is fed via the second feed apertures 18 of the second input points 17 into the channel space 16 of the second gravity chute (15), make-up air is conducted via the air duct 19, the channel space 16 of the second gravity chute 15 and the connecting channel 22 into the channel space 5 of the first gravity chute 4 when first material fraction is being removed from the first gravity chute 4 by means the partial-vacuum generator 3, and make-up air is conducted via the air duct 19 into channel space 16 of the second gravity chute 15 when second material fraction is being removed from the second gravity chute 15 by means of the partial-vacuum generator 3, and / or that the channel space 5 of the first gravity chute 4 is ventilated via the connecting channel(s) 22, the channel space (16) of the second gravity chute 15 and the air duct 19. According to an embodiment, the first gravity chute 4 comprises an arresting means 8 arranged between two first feed apertures 7, which are arranged at a vertical distance from each other, and / or below the lowermost feed aperture 7, which arresting means 8 has two positions, a first position, in which the arresting means 8 extends into the channel space 5 and prevents the displacement of the first material fraction fed from the feed aperture 8 higher up past the arresting means 8 in the channel space 5, in which case the first material fraction is collected in the channel space 5 on the arresting means 8, and a second position, in which the arresting means 8 allows the displacement of the first material fraction past the arresting means 8 in the channel space 5 towards the delivery end 33 of the fist gravity chute 4. The arresting means 8 is moved from the first position to the second position, and the first material fraction is removed from the first gravity chute 4 by means of the partial-vacuum generator 3. According to an embodiment, that the first gravity chute 4 comprises a number of arresting means 8 arranged at a vertical distance from each other, typically in sections between each two first feed apertures 7, which are arranged at a vertical distance from each other, and / or below the lowermost first feed aperture 7, and that the arresting means 8 are moved from the first position into the second position in phases, starting from the lowermost arresting means 8 that is in the first position and transferring always from the preceding to the next lowermost arresting means 8 until all the arresting means 8 of the first gravity chute 4 have been moved from the first position into the second position, and the first material fraction is removed from the first gravity chute 4 by means of the partial-vacuum generator 3. According to an embodiment, the first gravity chute 4 comprises a number of third input points 9 arranged at a vertical distance from each other, wherein each third input point 9 comprises a third feed aperture 11 and a feed-in container 10 via which third material fraction is fed into the channel space 5 of the first gravity chute 4. According to an embodiment, the third material fraction is temporarily stored in the feed-in containers 10, and the third material fraction is fed from the feed-in containers 10 via third feed apertures 11 in the channel space 5 of the first gravity chute 4 by moving the stoppers 12 from the first operating position to the second operating position, and third material fraction is removed from the first gravity chute 4 by the partial-vacuum generator 3. According to an embodiment, that the material conveying system 1 comprises a further first gravity chute 4’ having a similar structure as the first gravity chute 4, at least one second connecting channel 30 fluidly connecting the channel space of the further first gravity chute 4’ above the arresting means to the channel space 16 of the second gravity chute 15, and make-up air is conducted via the air duct 19, the channel space 16 of the second gravity chute 15 and the second connecting channel 30 into the channel space of the further first gravity chute 4’ when material fraction is being removed from the further first gravity chute 4’ by the partial-vacuum generator 3..According to an embodiment, channel space of the further first gravity chute 4’ is ventilated via the second connecting channel 30, the channel space 16 of the second gravity chute 15 and the air duct 19. It is obvious to a person skilled in the art that the invention is not limited to the above-described embodiments, but it may be modified within the scope of the accompanying claims. Features possibly presented in the description together with other features may also be used separately, if needed.

Claims

1. A pneumatic material conveying system (1) comprising a first gravity chute (4) having a channel space (5) and a delivery end (33) which is fluidly connectable to a partial-vacuum generator (3), wherein the first gravity chute (4) comprises a number of first input points (6) arranged at a vertical distance from each other, each first input point (6) comprising a first feed aperture (7) via which a first material fraction is arranged to be fed into the channel space (5) of the first gravity chute (4), and arresting means (8) arranged between two first feed apertures (7), which are arranged at a vertical distance from each other, and / or below the lowermost first feed aperture (7), which arresting means (8) has two positions, a first position, in which the arresting means (8) extends into the channel space (5) and prevents the displacement of the first material fraction fed from the first feed aperture (7) higher up past the arresting means (8) in the channel space (5), in which case the first material fraction collects in the channel space (5) on the arresting means (8), and a second position, in which the arresting means (8) allows the displacement of the first material fraction past the arresting means (8) in the channel space (5) towards the delivery end (33) of the fist gravity chute (4), and in which first gravity chute (4) the first material fraction is configured to be conveyed from the first input points (6) toward the delivery end (33) by means of gravity and / or suction generated by a partial-vacuum generator (3), characterized in that the pneumatic material conveying system (1) comprises a second gravity chute (15) having a channel space (16) and a delivery end (34), which is fluidly connectable to the partial-vacuum generator (3), which second gravity chute (15) comprises a number of second input points (17) arranged at a vertical distance from each other, wherein each second input point (17) comprises a second feed aperture (18) via which second material fraction is arranged to be fed into the channel space (16) of the second gravity chute (15), a connecting channel (22) fluidly connecting the channel space (5) of the first gravity chute (4) to the channel space (16) of the second gravity chute (15), an air duct (19) connected to the channel space (16) of the second gravity chute (15) for ventilating the channel space (5) of the first gravity chute (4) and / or for conducting make-up air into the channel space (16) of the second gravity chute (15) and into the channel space (5) of the first gravity chute (4) via the channel space (16) of the second gravity chute (15) and the connecting channel (22).

2. The pneumatic material conveying system (1) according to claim 1, characterized in that make-up air is arranged to be conducted into the channel space (5) of the first gravity chute (4) via the air duct (19), the channel space (16) of the second gravity chute (15) and the connecting channel (22) during the removal the first material fraction from the first gravity chute (4) by means of the partial-vacuum generator (3), and make-up is arranged to be conducted into the channel space (16) of the second gravity chute (15) via the air duct (19) during the removal the second material fraction from the second gravity chute (15) by means of the partial-vacuum generator (3).

3. The pneumatic material conveying system (1) according to claim 1 or 2, characterized in that the connecting channel (22) fluidly connects the channel space (5) of the first gravity chute (4) above the arresting means (8) to the channel space (16) of the second gravity chute (15).

4. The pneumatic material conveying system (1) according to any the preceding claims, characterized in that the first gravity chute (4) comprises a number of arresting means (8) arranged at a vertical distance from each other, typically in sections between each two first feed apertures (7), which are arranged at a vertical distance from each other, and / or below the lowermost first feed aperture (7).

5. The pneumatic material conveying system (1) according to any the preceding claims, characterized in that the material conveying system comprises (1) a number of connecting channels (22) fluidly connecting the channel space (16) of the second gravity chute (15) to the channel space parts of the first gravity chute (4) between each two arresting means (8) and / or to the channel space part above the uppermost arresting means (8).

6. The pneumatic material conveying system (1) according to claim 4 or 5, characterized in that the arresting means (8) are configured to displace from the first position into the second position in phases, starting from the lowermost arresting means (8) that is in the first position and transferring always from the preceding to the next lowermost arresting means (8) until all the arresting means (8) of the first gravity chute (4) have been moved from the first position to the second position.

7. The pneumatic material conveying system according (1) to any of the preceding claims, characterized in that the first gravity chute (4) comprises a number of third input points (9) arranged at a vertical distance from each other, wherein each third input point (9) comprises a third feed aperture (11) and a feed-in container (10) via which third material fraction is arranged to be fed into the channel space (5) of the first gravity chute (4).

8. The pneumatic material conveying system (1) according to claim 7, characterized in that each feed-in container (10) comprises a stopper (12) which prevents in a first operating position the passage of the third material fraction from the feed-in container (10) via the third feed aperture (11) to the channel space (5) of the first gravity chute (4) and in a second operating position releases the third material fraction to pass from the feed-in container (10) via the third feed aperture (11) to the channel space (5) of the first gravity chute (4).

9. The pneumatic material conveying system (1) according to any of the preceding claims, characterized in that the material conveying system (1) comprises a further first gravity chute (4’) having a similar structure as the first gravity chute (4), and at least one second connecting channel (27) fluidly connecting the channel space (5’) of the further first gravity chute (4’) above the arresting means (8’) to the channel space (16) of the second gravity chute (15).

10. The pneumatic material conveying system (1) according to claim 9, characterized in that the further first gravity chute (4’) comprises a number of arresting means (8’) and material conveying system (1) comprises a number of second connecting channels (27) fluidly connecting the channel space (16) of the second gravity chute (15) to the channel space parts of the further first gravity chute (4’) between the arresting means (8’), which are arranged at a vertical distance from each other, and / or to the channel space part above the uppermost arresting means (8’).

11. A method for feeding and conveying material in a pneumatic material conveying system (1) according to any of the preceding claims 1-10, in which method first material fraction is fed via the first feed apertures (7) of the first input points (6) into the channel space (5) of the first gravity chute (4), the first material fraction is conveyed from the first apertures (7) toward the delivery end (33) of the first gravity chute (4) by means of gravity and / or suction generated by a partial-vacuum generator (3) of the pneumatic material conveying system (1), characterized in that second material fraction is fed via the second feed apertures (18) of the second input points (17) into the channel space (16) of the second gravity chute (15), make-up air is conducted via the air duct (19), the channel space (16) of the second gravity chute (15) and the connecting channel (22) into the channel space (5) of the first gravity chute (4) when first material fraction is being removed from the first gravity chute (4) by the partial-vacuum generator (3), and make-up air is conducted via the air duct (19) into channel space (16) of the second gravity chute (15) when second material fraction is being removed from the second gravity chute (15) by the partial-vacuum generator (3), and / or that the channel space (5) of the first gravity chute (4) is ventilated via the connecting channel(s) (22), the channel space (16) of the second gravity chute (15) and the air duct (19).

12. The method according to claim 11, characterized in that the first gravity chute (4) comprises an arresting means (8) arranged between two first feed apertures (7) , which are arranged at a vertical distance from each other, and / or below the lowermost feed aperture (7), which arresting means (8) has two positions, a first position, in which the arresting means (8) extends into the channel space (5) and prevents the displacement of the first material fraction fed from the feed aperture (8) higher up past the arresting means (8) in the channel space (5), in which case the first material fraction is collected in the channel space (5) on the arresting means (8), and a second position, in which the arresting means (8) allows the displacement of the first material fraction past the arresting means (8) in the channel space (5) towards the delivery end (33) of the fist gravity chute (4), and in which method arresting means (8) is moved from the first position to the second position, and the first material fraction is removed from the first gravity chute (4) by the partial-vacuum generator (3).

13. The method according to claim 12, characterized in that that the first gravity chute (4) comprises a number of arresting means (8) arranged at a vertical distance from each other, typically in sections between each two first feed apertures (7), which are arranged at a vertical distance from each other, and / or below the lowermost first feed aperture (7), and that the arresting means (8) are moved from the first position into the second position in phases, starting from the lowermost arresting means (8) that is in the first position and transferring always from the preceding to the next lowermost arresting means (8) until all the arresting means (8) of the first gravity chute (4) have been moved from the first position into the second position, and that the first material fraction is removed from the first gravity chute (4) by the partial-vacuum generator (3).

14. The method according to any of claims 11-13, characterized in that the first gravity chute (4) comprises a number of third input points (9) arranged at a vertical distance from each other, wherein each third input point (9) comprises a third feed aperture (11) and a feed-in container (10) via which third material fraction is fed into the channel space (5) of the first gravity chute (4).

15. The method according to claim 14, characterized in that the third material fraction is temporarily stored in the feed-in containers (10), and the third material fraction is fed from the feed-in containers (10) via third feed apertures (11) in the channel space (5) of the first gravity chute (4) by moving the stoppers (12) from the first operating position to the second operating position, and third material fraction is removed from the first gravity chute (4) by the partial-vacuum generator (3).

16. The method according to any of claims 11-15, characterized in that the material conveying system (1) comprises a further first gravity chute (4’) having a similar structure as the first gravity chute (4), at least one second connecting channel (30) fluidly connecting the channel space of the further first gravity chute (4’) above the arresting means to the channel space (16) of the second gravity chute (15), and make-up air is conducted via the air duct (19), the channel space (16) of the second gravity chute (15) and the second connecting channel (30) into the channel space of the further first gravity chute (4’) when material fraction is being removed from the further first gravity chute (4’) by the partial-vacuum generator (3)..

17. The method according to claim 16, characterized in that channel space of the further first gravity chute (4’) is ventilated via the second connecting channel (30), the channel space (16) of the second gravity chute (15) and the air duct (19). 

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