AU2008339863B2

AU2008339863B2 - Method and apparatus in pneumatic material conveying system

Info

Publication number: AU2008339863B2
Application number: AU2008339863A
Authority: AU
Inventors: Goran Sundholm
Original assignee: Maricap Oy
Current assignee: Maricap Oy
Priority date: 2007-12-21
Filing date: 2008-12-18
Publication date: 2013-04-18
Anticipated expiration: 2028-12-18
Also published as: EP2219979A1; WO2009080887A1; BRPI0820824A2; FI20085149L; KR20100101153A; AU2008339863A1; CA2708128A1; JP2011507778A; FI20085149A0; TW200932648A; CN101903267A; EP2219979A4; AR069954A1

Abstract

A method in a pneumatic material conveying system, such as a waste conveying system, which conveying system comprises at least one feed point (61) of material, particularly of waste material, a material conveying pipe (100) which is connectable to the feed point (61), a separator device (20) in which the material being conveyed is separated from conveying air, and means (3) for providing a pressure difference in the conveying pipe (100) at least during the conveyance of the material. At least a part of the conveying piping (100) is connectable as a section of a circuit in which conveying air is circulated at least during the conveyance of the material with a pump device (3) the suction side of which is connected to at least one separator device (20) and further to the conveying pipe (100) on its return side so that at least part of conveying air on the pressure side of the pump is led in the circuit on the supply side of the conveying pipe (100) via an ejector device (9).

Description

1 METHOD AND APPARATUS IN PNEUMATIC MATERIAL CONVEYING SYSTEM Background of invention 5 The invention relates to a method according to the preamble of claim 1. The invention also relates to an apparatus according to claim 16. 10 The invention relates generally to pneumatic conveying systems, such as vacuum conveying systems, particularly to collecting and conveying waste, such as conveying household waste. Systems are known in which waste is conveyed in a piping by means of suction. In 15 these, waste is conveyed for long distances in the piping by suction. Apparatuses are utilised, inter alia, for conveying waste in different institutions. Typical for them is that a vacuum apparatus is used for achieving a pressure difference, in which apparatus underpressure in the conveying pipe is provided with vacuum generators, such as vacuum pumps or an ejector apparatus. In the conveying 20 pipe, there is typically at least one valve element by opening and closing of which make-up air coming in the conveying pipe is regulated. The vacuum conveying systems typically contain, inter alia, the following problems: high energy consumption, high air flow in the piping, problems with noise, dust and fine particles in the outlet pipe. Furthermore, prior-art apparatuses can have moisture 25 problems. In rainy weather, the prior-art apparatuses can suck even e.g. 1,000 litres of water per suction from outdoor air. This causes problems with corrosion and blockages. For example, waste paper or equivalent sticks to the piping when moist. Furthermore, large systems have required arranging several separate make-up air valves, which increases the complexity and costs of the systems. 30 The invention provides an arrangement in connection with material conveying systems by means of which the disadvantages of known arrangements are avoided. The invention also provides an arrangement applicable for vacuum conveying systems by means of which the noise problems of material feed can be 35 decreased. The invention decreases the production of moisture in the piping. The invention further provides an arrangement by means of which the number of make-up air valves required in the system can be minimised. The invention still 528 2 further provides anarrangement by means of which the volume of outlet air of the system and, at the same time, emissions of dust and fine particles and possible odour nuisances can be decreased. 5 Brief description of invention The invention is based on an idea in which at least a part of the material conveying pipe belongs to a circuit in which conveying air can be circulated. 10 The method according to the invention is mainly characterised in that at least a part of the conveying piping is connectable as a section of a circuit in which conveying air is circulated at least during the conveyance of the material with a pump device the suction side of which is connected to at least one separator device and further to the conveying pipe on its return side so that at least part of 15 conveying air on the pressure side of the pump is led in the circuit on the supply side of the conveying pipe via an ejector device. In addition, the method according to the invention is characterised by what is stated in claims 2-15. 20 The apparatus according to the invention is mainly characterised in that the apparatus comprises a circuit which comprises at least a part of the conveying piping, in which circuit conveying air is circulatable, and means which are arranged to circulate conveying air at least during the conveyance of the material with a 25 pump device the suction side of which is connected to at least one separator device and further to the conveying pipe on its return side so that at least part of conveying air on the pressure side of the pump is led in the circuit on the supply side of the conveying pipe and that the apparatus comprises an ejector device which is arranged in the circuit on the blowing side of the pump device between 30 the pump device and the conveying pipe. The apparatus according to the invention is further characterised by what is stated in claims 17-28. 35 The arrangement according to the invention has numerous significant advantages. By arranging the piping of the system to comprise a circuit where at least part of WO 2009/080887 PCT/F12008/050763 3 conveying air circulates, the volume of outlet air can be decreased. At the same time, the energy consumption of the system is minimised. By arranging an ejector device on the blowing side of the pump device of conveying air, the actuating medium of which is outlet air of the pump device, an extremely effective blowing 5 effect is provided in the circuit. By maintaining underpressure and simultaneously blowing, it is possible to provide an effective circulation of conveying air in the circuit and conveyance of material in the conveying pipe. With the arrangement according to the invention, it is possible to decrease the volume of outlet air substantially and simultaneously to decrease possible problems with dust and fine 10 particles in the outlet pipe. The arrangement according to the invention also substantially decreases the noise problem caused by prior art. Moisture accumulated in the piping is minimised and the piping can be dried by circulating air in the piping. As the volume of air being sucked inside decreases, also energy consumption decreases. By opening and closing the feed points of the system 15 according to the invention, the material is provided with an effective transfer into and conveyance in the conveying pipe when, at the same time, the noise effect caused by the operation of the system can be minimised. By arranging the conveying pipe of the material conveying system to consist of operating areas i.e. partial circuits, it is possible to effectively arrange the conveyance of the material 20 in the conveying piping and emptying the feed points into the conveying pipe. By arranging the conveying air circulation in the reverse direction, an effective removal of blockings is provided. In a circular piping, it is easily possible to arrange the change of the conveying air circulation in the reverse direction. 25 Brief description of figures In the following, the invention will be described in detail by means of an example with reference to the accompanying drawings in which 30 Fig. 1 schematically shows a system according to an embodiment of the invention, Fig. 1 a shows a part of a system according to the invention as simplified, Fig. 2 schematically shows a system according to an embodiment of the invention 35 in a second operating mode, WO 2009/080887 PCT/F12008/050763 4 Fig. 3 schematically shows a system according to an embodiment of the invention in a third operating mode, Fig. 4 schematically shows a system according to an embodiment of the invention 5 in a fourth operating mode, and Fig. 5 schematically shows a system according to an embodiment of the invention in a yet further operating mode. 10 Detailed description of invention Fig. 1 shows a pneumatic material conveying system according to an embodiment of the invention, particularly a waste conveying system, as a simplified schematic diagram. The figure shows a material conveying pipe 100 along which is arranged 15 at least one, typically several feed points 61. The feed point 61 is a feed station of material, particularly of waste material, intended to be conveyed, from which point the material, particularly waste material, such as household waste, intended to be conveyed is fed to the conveying system. The system can comprise several feed stations 61 from which the material intended to be conveyed is fed to a conveying 20 piping 100, 100A, 100B, 100C, 100D, 100E. The feed station 61 is designated in the figure with a point, whereby by opening and closing a gate element in connection with the feed station, such as a valve element 60, material can be conveyed from the feed point 61 to the conveying pipe 100. Fig. 1a shows a feed point 61 used in the system according to the invention and its outlet valve 60 in 25 more detail. The feed point is connected on the side of the valve to the conveying pipe 100 or a pipe being in connection with it. Typically, the conveying piping comprises a main conveying pipe 100 into which several branch conveying pipes can have been connected and into which again several feed stations 61 can have been connected. The fed material is conveyed along the conveying piping 100, 30 100A, 100B, 100C, 100D to a separator device 20 in which the material being conveyed is separated, e.g. due to dropping rate and centrifugal force, from conveying air. The separated material is removed, e.g. when required, from the separator device 20 to a material container, such as a waste container 51, or to further treatment. The material container can comprise, as in the embodiment of 35 the figures, a waste compactor 50, with which the material is compacted by compressing into smaller size, and from which the material is further conveyed to the waste container 51. In the embodiment of Fig. 1, the separator device 20 is WO 2009/080887 PCT/F12008/050763 5 provided with material outlet elements 21, 24. From the separating device 20, a conveying air channel 105 leads to means 3 for generating underpressure in the conveying pipe. In the embodiment of Fig. 1, the means for generating underpressure comprise a pump device 3, such as a vacuum pump unit. With the 5 means for generating underpressure, underpressure required for conveying the material is provided in the conveying piping 100 and/or its section. The vacuum pump unit 3 comprises a vacuum pump 30 which is operated by an actuator 31. The system comprises means for circulating conveying air in the circuit, a section of which is formed by at least a part of the conveying piping 100, 100A, 100B, 10 100C, 1OOD, 1OOD, 100E. In the embodiment of Fig. 1, the conveying piping 100 is dividable into operating areas or partial circuits 1O0A, 100B, 100C, 1OOD, 100E by valve elements VB, Vc, Vo i.e. area valves. Fig. 1 shows a situation in which the valve element VD is closed, whereby 15 conveying air is not able to circulate in the circuit. The suction side of the vacuum generator 3 being connected directly or by means of the conveying air channel 105 to at least one separator device 20, 20' in which again the delivery end of the conveying pipe 100 is connected, underpressure is provided in the conveying pipe to at least the section of the circuit which is in the material conveying direction 20 between at least one valve, in Fig. 1 the valve VD, and the separator device 20. The conveying direction of material and the travel direction of air are designated with arrows in Fig. 1. Underpressure prevails also in the section of the circuit between the separator device 20 and the vacuum generator 3, i.e. in the conveying air channel 105, in the embodiment of the figure also in the second 25 separator device 20' i.e. a dust separator and the section of the conveying air channel 105 extending from it to the vacuum generator 3. In a case according to the figure, when opening in the feed point 61 its valve element 60, a material portion intended to be conveyed is conveyed to the conveying pipe 100, in the figure to the section 100D of the conveying pipe, to be conveyed further to the 30 separator device 20. Possible make-up air in the conveying pipe comes e.g. via the feed point 61 when opening the valve 60 in the conveying pipe. The blowing side of the vacuum pump 30 of the pump device 3 in the embodiment of Fig. 1 is arranged to blow in an ejector device 9 in the operating mode in 35 question. The ejector device 9 is arranged between the pump device 3 and the conveying piping 100 so that an ejector nozzle 91 of the ejector device 9 is connected to the channel 110 coming from the blowing side of the pump device.

WO 2009/080887 PCT/F12008/050763 6 Then, as the actuating medium of the ejector 9 operates conveying medium, typically air, of the blowing side of the pump device 3, such as a vacuum generator. The ejector device 9 comprises an ejector pipe 92 in which the ejector nozzle 91 is arranged to direct a medium spray. The ejector device comprises a 5 chamber space 94 in which the ejector nozzle 91 and the first end of the ejector pipe 92 and a fitting 93, via which is openable and closable a connection outside the chamber space 94, are arranged. When the ejector nozzle 91 sprays the medium in the ejector pipe 92, suction is provided which draws extra air along with it via the fitting 93. A blowing side 95 of the ejector device 9 is connected to the 10 conveying pipe 100 or the channel 110 leading to the conveying pipe. The operating principles of the ejector device are considered known as such to those skilled in the art and they will not be examined in more detail. From the influence of the ejector 9, a considerable increase is provided in the main flow blown by the pump device 3 due to an extra air flow via the fitting 93, typically in the range of 15 20-60%. With the combination of the pump device 3 and the ejector 9, an increase is thus provided in the conveying air flow by means of which it is possible to effectively provide overpressure on the blowing side of the pump and/or underpressure and/or a suction effect on the suction side of the pump device. In the fitting 93 is arranged a valve element 96 and a filter element 97, such as a dust 20 filter. In certain cases, the fitting 93 can also operate as an outlet channel. From the blowing side of the ejector 9 is arranged a connection, e.g. via the air channel 110, to the conveying pipe 100 on its supply side. In the air channel 110 of the blowing side is arranged the valve element 122 which, when closed, 25 prevents a connection of the blowing side to the usual supply side of the conveying pipe 100. The operation of the system is controlled so that, for emptying the feed points of a desired operating area, at least one valve is open in the material conveying 30 direction in relation to the operating area of the conveying pipe 100 and on the supply side of the conveying air i.e. on the side of suction, whereby the suction is able to affect the conveying pipe of the operating area. Let us assume that, in the arrangement according to the figure, the feed points 61 of the conveying pipe area 100D are to be emptied. Then, all area valves between the separator element 20 35 and the operating area in the conveying pipe 100 (the section 1OOD of the conveying pipe in the figure) in the conveying direction are open (the valve 126 in the figure). Then, suction provided by at least one vacuum generator 3 prevails in WO 2009/080887 PCT/F12008/050763 7 the conveying piping 100D in the operating area. At least one valve VD on the blowing side of the conveying pipe 100 is closed, whereby only suction prevails in the operating area. The feed points 61 of the operating area or at least part of them are emptied so that the connection of the feed point 61 (1) closest to the 5 delivery end in the conveying direction of the conveying pipe, i.e. in the embodiment according to the figure closest to the separator device 20, to the conveying pipe 1 OOD is opened first, whereby the material is able to convey from the first feed point to the conveying pipe, and before the connection of the first feed point (1) to the conveying pipe closes, the connection of the next feed point 61 10 (II) to the conveying pipe is opened. In the embodiment of the figure, this is, when travelling against the material conveying direction, the next feed point 61 (II) intended to be emptied. After this, the connection of the first feed point 61 (1) is closed to the conveying pipe. Equivalently, the connection of the third feed point 61 (111) intended to be emptied to the conveying pipe is opened before the 15 connection of the second feed point 61 (II) to the conveying pipe is closed. This operation is repeated until all desired feed points have been emptied. In the figure, it has been considered emptying all the feed points 61 of the conveying pipe area 100D, whereby their emptying sequence to the conveying pipe 100, 100D is designated in the figure by numerals within parentheses: (I), (II), (III), (IV), (V), (VI), 20 (VII), (VIII), (IX), (X), (XI), and (XII). When the passage of the last feed point 61 (XII) intended to be emptied in the operating area to the conveying pipe 100 has been opened, the material has conveyed to the conveying pipe 100, 1OOD, and the passage of the feed point to the conveying pipe is closed, a connection is opened in the conveying pipe 100D of the operating area from the blowing side by opening 25 at least one valve element VD which is between the operating area and the pump device 3 blowing to the conveying pipe 100. Then, an intensified conveying effect (suction and blowing together) is provided for the material being conveyed transferred in the conveying pipe 100, 1O0A, 100B, 100C, 1OOD. The conveying air circulates on a route designated with arrows in the figure, whereby material 30 portions conveyed from the feed points to the conveying pipe convey in the conveying piping further to the separator device 20 in which the material being conveyed is separated from conveying air. In the figure, the area valve VE of the conveying pipe 100E of the operating area is closed, whereby conveying air is not able to access the conveying pipe 1 OOE of the operating area but circulates on the 35 route of the conveying pipe of the area via 1O0A, 100B, 100C, 100D. In connection with the emptying of different operating areas, the material conveying route from WO 2009/080887 PCT/F12008/050763 8 the operating area to a delivery station, such as to the separator element 20, can be optimised by keeping the area valves open along the desired conveying route. Fig. 2 shows an operating mode of a system according to the invention in which 5 conveying air is able to circulate in the circuit, a section of which is formed by at least a part of the conveying pipe 100 and in which in the embodiment of the figure belong the separator device 20, the conveying air channel 105, a possible second separator device 20' and from the blowing side of the vacuum generator the air channel 110 on the supply side of the conveying pipe 100. The vacuum generator 10 3 is arranged to circulate air in the circuit and to provide a suction effect in the conveying pipe 100, at least its delivery end, i.e. in the conveying direction at the end on the side of the separator element 20. According to the embodiment of the figure, the vacuum generator 3 is also arranged to provide a blowing effect in the conveying pipe, in the figure via the air channel 110 and the ejector device 9. One 15 or more area valves of the conveying pipe 100, in the figure area valves VB, VC, VD and the valves 122 and 126, are in the open position, whereby conveying air is able to circulate in the circuit, a section of which is formed by at least a part of the feed pipe 100, whereby material portions fed in the conveying pipe from one or more feed stations 61 move towards the separator device 20. In the ejector 20 device, to a main flow produced by the pump device is combined an additional flow coming from the fitting 93 which is led, due to the suction provided by the ejector device, from the fitting 93 to the ejector in which it is mixed with the main flow. Then, with the pump device together with the ejector, an extremely effective blowing effect is provided in the circuit on its supply side and a suction effect on 25 the side of the separator element i.e. on the return side. Fig. 3 shows an operating mode in which materials accumulated in the separator device are emptied. In the embodiment of the figure, at least two valve elements in the circuit on different sides of the separator device are closed, whereby 30 conveying air does not circulate via the separator devices. In the embodiment of the figure, there are two separator devices 20, 20'. When the separator device 20, 20' has become full, the valves 126, 127 of the circuit close and control valves 23, 23' open, whereby the actuator 24, 24' of the outlet hatch 21, 21' of the separator device opens the outlet hatch 21, 21' and the material accumulated in the 35 separator device is emptied directly or via a conveyor device 27 to the compactor device 50 and further to the waste container 51. In the figure, into connection with the second separator device 20' i.e. the dust separator is arranged the conveyor WO 2009/080887 PCT/F12008/050763 9 device 27 which conveys material emptied from the second separator to the compactor device 50. The outlet hatch 21, 21' of the separator device 20, 20' is closed and the valves 5 126, 127 opened. Fig. 4 shows an operating mode of the system in which a connection to the outlet channel, which is in the embodiment of the figure the fitting 93 of the ejector 9, is closed by means of the valve 96. Then, there is a connection from the blowing 10 side of the pump device 3 via the air channel 110 on the supply side of the conveying pipe 100. The pump device circulates air in the circuit a section of which is formed by the conveying piping. In the embodiment of the figure, there has also been arranged at least one fitting 107, 107' in which there is a valve 128, 128' by opening of which extra air can be brought on the suction side of the pump device 3 15 from outside the circuit. By opening the valve 128, 128', it is possible to raise the pressure of air in the conveying pipe if required and to provide an increased blowing effect in the circuit. In the embodiment of the figure, the valve 128, 128' of at least one fitting 107, 107' is open, whereby it is possible to bring extra air on the suction side of the pump device 3 from outside the circuit. By opening the valve 20 128, 128', it is then possible to raise the pressure of air in the conveying pipe if required and to provide an increased conveying rate of conveying air. The embodiment of Fig. 3 is particularly well applicable in the air flushing of the piping. With the embodiment of the figure, it is also possible to dry the piping. With the vacuum generator is then advantageously provided a greater flow rate to the 25 pressure side than the suction side. Air heats up when compressing, whereby the drying process is also intensified. Fig. 5 shows a further embodiment of a system according to the invention in which there is an operating mode by which the circulation direction of conveying air can 30 be reversed at least in a section of the circuit. This can be utilised e.g. in a possible malfunction situation in which a blockage has been formed in the conveying piping 100, 100A, 100B, 100C, 100D, 100E. In the conveying pipe is arranged on the supply side at a distance from the separator device 20 a valve element 126, at the reverse side of which in relation to the separator element is 35 arranged an air channel 113 in which the blowing side of the pump device 3 is connectable. Equivalently, in the air channel 110 of the blowing side is arranged the valve element 122 which, when closed, prevents a connection of at least the WO 2009/080887 PCT/F12008/050763 10 blowing side of the pump device 3 to the usual supply side of the conveying pipe 100. From the blowing side of the vacuum unit is arranged a medium passage 113 to the conveying piping 100 on its reversed supply side. In the conveying pipe 100 is formed a channel section 114 which is connected to the conveying pipe in a 5 section between the valve element 126 and the separator device 20 or directly to the separator device, whereby the circulation direction of conveying air is reversed only in a section of the circuit, mainly in the section of the conveying pipe 100. Then, possible blockages are sucked "backwards" in relation to the normal circulation direction. 10 The invention thus relates to a method in a pneumatic material conveying system, such as a waste conveying system, which conveying system comprises at least one feed point 61 of material, particularly of waste material, a material conveying pipe 100 which is connectable to the feed point 61, a separator device 20 in which 15 the material being conveyed is separated from conveying air, and means 3 for providing a pressure difference in the conveying pipe 100 at least during the conveyance of the material. At least a part of the conveying piping 100 is connectable as a section of a circuit in which conveying air is circulated at least during the conveyance of the material with a pump device 3 the suction side of 20 which is connected to at least one separator device 20 and further to the conveying pipe 100 on its return side so that at least part of conveying air on the pressure side of the pump is led in the circuit on the supply side of the conveying pipe 100 via an ejector device 9. 25 According to a typical embodiment, at least part of conveying air is circulated via the ejector device 9 in which extra air is brought to the circuit. At least part of blowing air of the pump device 3 is employed as the actuating medium of the ejector device 9. 30 According to an advantageous embodiment, in the material feed stage, underpressure is provided from the feed point to the conveying pipe to at least a part of the conveying piping 100 with the pump device, whereby the outlet air channel of the blowing side of the pump device 3, such as a fitting 93, is open. 35 WO 2009/080887 PCT/F12008/050763 11 According to an advantageous embodiment, in the conveying stage, at least the main part of air on the blowing side of the pump 3 is circulated in the circuit on the supply side of the conveying pipe 100. 5 According to an advantageous embodiment, in the method, in the circuit is brought make-up air via at least one air inlet 107, 107', 93 which advantageously comprises a valve element 128, 128', 96. According to an advantageous embodiment, the method comprises an operating 10 mode in which air is removed from the circuit via at least one air outlet, such as the fitting 93, which advantageously comprises a gate/regulating element, such as the valve element 96. According to a yet further advantageous embodiment, the circulation of air in the 15 circuit, which comprises at least a part of the conveying piping 100, is regulated and/or controlled and/or opened or closed by gate/regulating elements, such as valve elements 122, 124, 125, 126, 127, VA, VB, Vc, VD, which are arranged in the circuit. 20 According to a typical embodiment, in the method, underpressure is provided in the circuit with at least one pump device 3 the suction side of which is connected to the separator element 20 or to the conveying pipe 100 via the air channel 105 leading to it. 25 According to a yet further embodiment, in the method, pressure is provided in the circuit with at least one pump device 3 the blowing side of which is connected to blow in the circuit. According to an advantageous embodiment, the method comprises an operating 30 mode in which conveying air circulation is connected in the reverse direction at least in a section of the circuit, which section is formed by at least a part of the conveying pipe 100, advantageously for removing a blockage. According to a further advantageous embodiment, the method comprises an 35 operating mode in which at least a part of the conveying piping 100 is flushed and/or dried with air by circulating the conveying air in the circuit, particularly by blowing in the circuit with the pump device 3.

WO 2009/080887 PCT/F12008/050763 12 Typically in the method, material is fed from the material feed points 61 which are waste feed points, such as waste bins or waste chutes. 5 Typically between the material feed point 61 and the conveying pipe 100, there is at least one valve element 60 by opening and closing of which the feed of material and/or make-up air to the conveying pipe is regulated. According to an advantageous embodiment, the valve element 60 between the 10 material feed point 61 and the conveying pipe 100 is closed advantageously after a certain time from opening so that the valve 60 of the previous feed point is still open when the valve of the next feed point 61 is opened. The invention also relates to an apparatus in a pneumatic material conveying 15 system, such as a waste conveying system, which comprises at least one feed point 61 of material, particularly of waste material, a material conveying pipe 100 which is connectable to the feed point 61, a separator device 20 in which the material being conveyed is separated from conveying air, and means 3 for providing a pressure difference in the conveying pipe 100 at least during the 20 conveyance of the material. The apparatus comprises a circuit which comprises at least a part of the conveying piping 100, in which circuit conveying air is circulatable, and means which are arranged to circulate conveying air at least during the conveyance of the material with a pump device 3 the suction side of which is connected to at least one separator device 20 and further to the 25 conveying pipe 100 on its return side so that at least part of conveying air on the pressure side of the pump is led in the circuit on the supply side of the conveying pipe 100 and that the apparatus comprises an ejector device 9 which is arranged in the circuit on the blowing side of the pump device 3 between the pump device 3 and the conveying pipe 100. 30 According to an advantageous embodiment, the actuating medium of the ejector device 9 is blowing air of the pump device 3. Typically, the ejector device 9 comprises a fitting 93 for leading another medium 35 flow in the actuating medium flow. The other actuating medium flow is advantageously a gas flow, such as an air flow, for bringing extra air in the circuit.

WO 2009/080887 PCT/F12008/050763 13 In the material feed stage, underpressure is provided from the feed point to the conveying pipe to at least a part of the conveying piping 100 with the pump device 3, whereby the outlet air channel of the blowing side of the pump device 3, such as the fitting 93, is arranged to open. 5 According to an advantageous embodiment, in the circuit, which comprises at least a part of the conveying piping 100, are arranged gate/regulating elements, such as valve elements 122, 124, 125, 126, 127, VB, Vc, VD, by means of which the circulation of conveying air can be regulated and/or controlled and/or opened 10 or closed. According to a yet advantageous embodiment, the apparatus comprises at least one air inlet 107, 107', 93 which advantageously comprises a valve element 128, 128', 96 for bringing air in the circuit from outside it. 15 According to a further advantageous embodiment, the apparatus comprises at least one outlet 93 which advantageously comprises a gate/regulating element, such as the valve element 96, for removing at least part of air from the circuit. 20 Typically, the means for providing a pressure difference comprise at least one pump device 3 the suction side of which is connected to the separator element 20 or the air channel 105 leading to it. There can be several pump devices and they can be connected in the circuit in parallel or in series, whereby the suction side of the first pump device is connected to the separator device 20 and the blowing side 25 to feed air on the suction side of the second pump device. The blowing side of the second pump device is then arranged to blow in the ejector device 9. According to another embodiment, the means for providing a pressure difference comprise at least one pump device 3 and means 110, 122; 113, 124 for 30 connecting the blowing side of at least one pump device to blow in the circuit. According to another advantageous embodiment, the apparatus comprises means 113, 114, 122, 124, 125, 126 for connecting the conveying air circulation in the reverse direction in at least a section of the circuit, at least part of which is formed 35 by the conveying pipe 100.

WO 2009/080887 PCT/F12008/050763 14 According to a yet further advantageous embodiment, the apparatus comprises means for flushing at least a part of the conveying piping 100 with air and/or for drying by circulating the conveying air in the circuit, particularly by blowing. 5 According to an advantageous embodiment, the material feed points 61 are waste feed points, such as waste bins or waste chutes. Between the feed point 61 and the conveying pipe 100, there is at least one valve element 60 by opening and closing of which the feed of material and/or make-up 10 air to the conveying pipe is regulated. The suction provided by the vacuum unit 3 to the conveying pipe 100, in the figure from the side of the separator element 20, is advantageously greater than the blow, whereby conveyance takes place in underpressure. The suction being 15 greater than blowing, underpressure is provided in the piping, whereby waste can be sucked inside the piping from a funnel of the feed station 61. The suction being greater than the blowing, which is the target in the system according to the invention, material fed to the conveying pipe, particularly waste 20 material, will not be compressed and compacted, but will be able to travel "freely" in the pipe conveyed by conveying air. Then, the potential of the material being conveyed to form blockages is considerably lower than in a situation in which the blowing is greater than the suction, whereby there is a risk that the material being conveyed will accumulate and block the conveying pipe. Furthermore, 25 underpressure decreases the power required to convey the material, because even partial underpressure in relation to the material portion being conveyed on the side of the conveying direction considerably decreases air drag, among others. In the figure, arrows designate the direction of motion of air in the piping in the operating mode. 30 The outlet valve 60 of the feed point 61 is opened and closed so that material portions of suitable size are conveyed from the feed point 61 to the conveying pipe 100. Material is fed from the feed point 61, such as a waste container, when after the container is full, the outlet valve 60 is opened either automatically or manually. 35 The system typically operates as follows: An outlet hatch 21, 21' of at least one separator device 20, 20' is closed and a valve 126 between the main conveying WO 2009/080887 PCT/F12008/050763 15 pipe 100 and the separator device 20 is open. The pump unit 3 maintains underpressure in the main conveying pipe 100. All outlet valves 60 in the vicinity of the feed points 61 i.e. waste containers are 5 closed. In the start situation 100, the valve VD is closed. Let us assume that a waste container of the feed point 61 belonging to the circuit of the operating area 100D of the conveying pipe 100 is to be emptied. Based on an emptying signal, the outlet valve 60 is momentarily opened, e.g. for 2-10 10 seconds, whereby the material being conveyed, such as waste material, conveys from the effect of underpressure to the conveying pipe 100D. The outlet valve 60 is typically closed after a few seconds after the start situation. The vacuum pump unit 3 maintains desired underpressure. The valve VD is opened, whereby in the circuit of the piping is provided air circulation and possibly also a blowing effect i.e. 15 pressure effect and suction effect which conveys the material portion being conveyed along the piping to the separator device 20. One or more feed points 61 are emptied. According to an advantageous embodiment, the one of the feed points of the desired operating area which is in the conveying direction closest to the separator device 20 is emptied first, and then the next closest feed point and 20 so on until the desired feed points have been emptied. When the separator device 20 is full, the valve 126 of the conveying pipe 100 closes and a control valve 23 opens, whereby the actuator 24 of the outlet hatch 21 of the separator device opens the outlet hatch 21 and the material accumulated 25 in the separator device is emptied in the compactor device 50 and further in the waste container 51. The outlet hatch 21 of the separator device 20 is closed and the valve 126 opened. After this, the start situation is reverted and the emptying process can be repeated 30 or the emptying of some other feed point/feed points can be implemented. The waste container 51, such as a waste freight container, is replaced or emptied when it is full. 35 The system can also comprise several separator devices 20, 20' in which material conveyance is controlled, e.g. based on the sort of the material or the capacity of the system.

528 16 It is obvious to those skilled in the art that the invention is not limited to the embodiments described above, but it may be varied within the scope of the enclosed claims. When necessary, the features possibly described in this 5 specification together with other features may also be used separately from each other. In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary 10 implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 15 It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

Claims

1. A method in a pneumatic material conveying system, such as a waste conveying system, which conveying system comprises at least one feed point of 5 material, particularly of waste material, a material conveying pipe which is connectable to the feed point, a separator element in which the material being conveyed is separated from conveying air, and means for providing a pressure difference in the conveying pipe at least during the conveyance of the material, wherein at least a part of the conveying piping is connectable as a section of a 10 circuit in which conveying air is circulated at least during the conveyance of the material with a pump device the suction side of which is connected to at least one separator device and further to the conveying pipe on its return side so that at least part of conveying air on the pressure side of the pump is led in the circuit on the supply side of the conveying pipe via an ejector device. 15

2. A method according to claim 1, wherein at least part of conveying air is circulated via the ejector device in which extra air is brought to the circuit.

3. A method according to claim 1 or 2, wherein at least part of blowing air of the 20 pump device is used as the actuating medium of the ejector device.

4. A method according to any one of claims 1-3, wherein, in the material feed stage, underpressure is provided from the feed point to the conveying pipe to at least a part of the conveying piping with the pump device, whereby an outlet air 25 channel, such as a fitting, of the blowing side of the pump device is open.

5. A method according to any one of claims 1-4, wherein, in the conveying stage, at least the main part of air on the blowing side of the pump is circulated in the circuit on the supply side of the conveying pipe. 30

6. A method according to any one of claims 1-5, wherein, in the method, in the circuit is brought make-up air via at least one air inlet which advantageously comprises a valve element. 35

7. A method according to any one of claims 1-6, wherein the method comprises an operating mode in which air is removed from the circuit via at least one air 528 18 outlet, such as the fitting, which advantageously comprises a gate/regulating element, such as a valve element.

8. A method according to any one of claims 1-7, wherein the circulation of air in 5 the circuit, which comprises at least a part of the conveying piping, is regulated and/or controlled and/or opened or closed by gate/regulating elements, such as valve elements, which are arranged in the circuit.

9. A method according to any one of claims 1-8, wherein, in the method, 10 underpressure is provided in the circuit with at least one pump device the suction side of which is connected to the separator element or to the conveying pipe via an air channel leading to it.

10. A method according to any one of claims 1-9, wherein, in the method, 15 pressure is provided in the circuit with at least one pump device the suction side of which is connected to blow in the circuit.

11. A method according to any one of claims 1-10, wherein the method comprises an operating mode in which conveying air circulation is connected in the reverse 20 direction at least in a section of the circuit, which section is formed by at least a part of the conveying pipe, advantageously for removing a blockage.

12. A method according to any one of claims 1-11, wherein the method comprises an operating mode in which at least a part of the conveying piping is flushed 25 and/or dried with air by circulating conveying air in the circuit, particularly by blowing in the circuit with the pump device.

13. A method according to any one of claims 1-12, wherein, in the method, material is fed from the material feed points which are waste feed points, such as 30 waste bins or waste chutes.

14. A method according to any one of claims 1-13, wherein, between the material feed point and the conveying pipe, there is at least one valve element by opening and closing of which the feed of material and/or make-up air in the conveying pipe 35 is regulated. 528 19

15. A method according to any one of claims 1-14, wherein the valve element between the material feed point and the conveying pipe is closed, advantageously after a certain time after opening, so that the valve of the previous feed point is still open when the valve of the next feed point is opened. 5

16. An apparatus in a pneumatic material conveying system, such as a waste conveying system, which comprises at least one feed point of material, particularly of waste material, a material conveying pipe which is connectable to the feed point, a separator element in which the material being conveyed is separated from 10 conveying air, and means for providing a pressure difference in the conveying pipe at least during the conveyance of the material, wherein the apparatus comprises a circuit which comprises at least a part of the conveying piping, in which circuit, conveying air is circulatable, and means which are arranged to circulate conveying air at least during the conveyance of the material with a pump device the suction 15 side of which is connected to at least one separator device and further to the conveying pipe on its return side so that at least part of conveying air on the pressure side of the pump is led in the circuit on the supply side of the conveying pipe and that the apparatus comprises an ejector device which is arranged in the circuit on the blowing side of the pump device between the pump device and the 20 conveying pipe.

17. An apparatus according to claim 16, wherein the actuating medium of the ejector device is blowing air of the pump device. 25

18. An apparatus according to claim 16 or 17, wherein the ejector device comprises a fitting for leading another medium flow to the actuating medium flow.

19. An apparatus according to any one of claims 16-18, wherein, in the material feed stage, underpressure is provided from the feed point to the conveying pipe to 30 at least a part of the conveying piping with the pump device, whereby an outlet air channel, such as the fitting, of the blowing side of the pump device is arranged to open.

20. An apparatus according to any one of claims 16-19, wherein, in the circuit, 35 which comprises at least a part of the conveying piping, are arranged gate/regulating elements, such as valve elements, by means of which the 528 20 circulation of conveying air can be regulated and/or controlled and/or opened and closed.

21. An apparatus according to any one of claims 16-20, wherein the apparatus 5 comprises at least one air inlet which advantageously comprises a valve element for bringing air in the circuit from outside of it.

22. An apparatus according to any one of claims 16-21, wherein the apparatus comprises at least one outlet which advantageously comprises a gate/regulating 10 element, such as the valve element, for removing at least part of air from the circuit.

23. An apparatus according to any one of claims 16-22, wherein the means for generating a pressure difference comprise at least one pump device the suction 15 side of which is connected to the separator element or an air channel leading to it.

24. An apparatus according to any one of claims 16-23, wherein the means for providing a pressure difference comprise at least one pump device and means for connecting the blowing side of at least one pump device to blow in the circuit. 20

25. An apparatus according to any one of claims 16-24, wherein the apparatus comprises means for connecting the conveying air circulation in the reverse direction at least in a section of the circuit which section is formed by at least a part of the conveying pipe. 25

26. An apparatus according to any one of claims 16-25, wherein the apparatus comprises means for flushing at least a part of the conveying piping with air and/or drying by circulating conveying air in the circuit, particularly by blowing. 30

27. An apparatus according to any one of claims 16-26, wherein the material feed points are waste feed points, such as waste bins or waste chutes. 21

28. An apparatus according to any one of claims 16-27, wherein, between the feed point and the conveying pipe, there is at least one valve element by opening and closing of which the feed of material and/or make-up air in the conveying pipe 5 is regulated.