WO2000037341A1

WO2000037341A1 - Arrangement for filling silos by using transport air, method utilizing the arrangement, and silo including the arrangement

Info

Publication number: WO2000037341A1
Application number: PCT/NL1999/000794
Authority: WO
Inventors: Beert Bakker
Original assignee: Polem B.V.
Priority date: 1998-12-23
Filing date: 1999-12-21
Publication date: 2000-06-29
Also published as: EP1140676A1; NL1010878C2

Abstract

An arrangement used for filling silos with a grain-like to powder-like material while using transport air, more specifically for filling feed silos with grain-like to powder-like feed, includes a filling pipe for filling the silo, an aeration/de-aeration facility which is also at least used for discharging the used transport air while the silo is being filled, and a dust filter co-operating with the aeration/de-aeration facility and obstructing feed particles carried along by the transport air during the filling of the silo. The dust filter is installed on top of an upper part of a silo and forms part of the said aeration/de-aeration facility. The invention also relates to a silo including the above-mentioned arrangement and to a method of filling the silo.

Description

Arrangement for filling silos by using transport air, method utilizing the arrangement, and silo including the arrangement.

The invention relates to an arrangement for filling silos by using transport air, of the type as described in the introductory part of claim 1. Arrangements of this type are widely known in practice, for example as feed silos at pig farms. This type of silos is generally provided with a facility used for de-aerating the silo, more particularly intended for discharging vapour from the silo so as to avoid condensation being developed inside the silo. The formation of conden- sation in a feed silo is highly undesirable, because pollution may occur in the silo as a result of the feed or feed remainders getting moist and also at least part of the stored feed may go bad. Sometimes the same system is used for both aerating the silo, which is necessary to avoid underpressure in the silo, and for de-aerating the silo. Arrangements of this type may comprise, for example, a vertical pipe erected beside the silo, which pipe is connected to the upper part of the silo by means of a branch and extends slightly more upward past the branch. The de-aeration and thus the discharge of condensation from the silo are doubtful in such a system, because air may flow through the pipe from bottom to top, but the air is not necessarily discharged from the silo, especially because de- aeration and aeration have to take place through the same branching pipe portion. In an improved embodiment a separate aeration pipe, which also partly extends vertically beside the silo, is connected to the upper part of the silo. In this way the aeration can take place through one pipe and the de- aeration through the other, as a result of which there is more certainty about the discharge of condensation from the silo. In the case of a silo including the outlined aeration and de-aeration system of the latter embodiment, the de- aeration pipe may at the same time be used for filling the silo with the aid of transport air. For this purpose the de- aeration pipe accommodates a manually operable valve which can shut off the upper part of the de-aeration pipe, so that only the bottom vertical part of the de-aeration pipe and the horizontal branch are connected to each other. When the silo is being filled, the aeration pipe may be used for discharging the transport air. This may be effected through a separate dust filter to be connected to the aeration pipe, so that the dust carried off from the silo by the transport air does not directly end up in the environment . The use of such a dust filter means an important improvement compared with the method often used in the past in which the dust occurring in the transport air was discharged to the exterior of the silo without being filtered, so that there used to be a considerable amount of pollution in the environment. Such pollution is highly undesirable, because at a later stage much effort is required to remove the dirt and, what is more, unwanted vermin is attracted.

Even the improved installations that may be provided with a dust sack do not function satisfactorily in every respect, however. For example, a certain degree of attention is required, firstly, to connect the separate dust filter to the silo in the right manner prior to the silo being filled and, secondly, to avoid the filter sack not being exchanged in time, because in that case an overpressure that may lead to undesired situations may develop inside the silo; the upper part of the silo may even be blown off. A further disadvantage is that the full dust sacks have to be carried off and preferably in the right manner. This may lead to problems of stor- age, problems of transhipment and possibly pollution problems and so on. In addition, feed loss occurs, the dust carried along, among which small grains, as the case may be, having the same composition as the rest of the feed and thus being suitable for consumption by the respective animals. The invention aims at improving an arrangement of the type defined in the opening paragraph and avoiding the said disadvantages and is characterised by the measures that are defined in the characterising part of claim 1. Different from the known state of the art, the dust filter in the arrangement according to the invention is installed in the upper part of the silo. This is understood to mean that the collected dust and possibly the collected small feed grains that are carried along to the exterior of the silo by the transport air are stopped at the upper part of the silo and may also fall back again into the silo. No separate dust filter is required, a dust sack is redundant and the obstructed material is used in the normal way for feeding the animals. Since it is an air- permeable dust filter, it may also serve as an aeration/de- aeration facility. For example, a separate aeration pipe can be connected to a silo and the de-aeration may be effected via the dust filter. This provides an effective means for avoiding the occurrence of condensation in the silo. The aeration pipe may also be used for filling the silo.

An embodiment of the invention that is advantageous in this respect is characterised in claim 2. The pipe portion forms a space on the roof of a silo. The arrangement may be provided such that the dust filter can be installed and removed in a simple manner. This may require the removal of the rain hood. Another advantageous embodiment is characterised in claim 3. The said pipe portion may extend, for example, in vertical direction on top of a silo and the vertical wall of the pipe portion offers a good place for connecting the filling pipe, which may also be the aeration pipe, to a silo. The filling pipe is bent down inside the pipe portion and runs down a small distance along the central axis of the pipe portion as far as the nozzle. The feed can thus be poured into a silo in bulk at a central location.

Claim 4 describes a further advantageous embodiment of the invention. Herein the pipe portion and the rain hood are arranged concentrically, so that a ring-shaped interspace is left between the pipe portion and the enveloping part of the rain hood. In this ring-shaped interspace is installed a grid or a perforated plate or the like that has no noticeable effect on the flow-resistance of air passing through, but is suitable for obstructing birds and the like.

According to claim 5, the shut-off element can at the same time be used in an advantageous manner for connecting the rain hood to the pipe portion. A preferred embodiment has the characteristic features of claim 6. If too high a pressure unexpectedly arose in a silo, the arrangement according to the invention would simultaneously act as a safety device that provides that the overpressure inside the silo remains below a certain prede- fined unsafe overpressure. Such overpressure may occur, for example, because the driver of a vehicle that transports the feed from a feed plant to the silo has the storage tank of the vehicle blown empty. This happens when the tank is practically empty and no more than feed remainders have to be removed from the tank. As a result of the bulk tank being blown empty, there is a sudden pressure surge in the filling pipe which in the past did give rise to the upper part of the odd silo being blown off. In the latter embodiment of the invention the safety device will automatically start to operate in a case like that. In a case like that the air leaving through the safety device will not first pass through the filter, it is true, but this is a matter of a relatively small volume of air and, moreover, an exceptional case.

The invention is also pre-eminently suitable for use in a method which likewise forms part of the invention and is described in claim 7. This method relates to filling a silo that is located on an industrial site such as a farmyard while an arrangement of the type described above is used from a road vehicle that includes a filling unit. Such road vehicles hav- ing a storage tank for cattle feed are often called bulk feed trucks. Therefore, this name will be used henceforth in the course of the description.

Endeavours have increasingly been made to extend the feed silo filling pipe to outside the industrial site, espe- cially so as to avoid contagion. As is known, the pig industry has been struck by many cases of swine fever the past few years. Swine fever is a highly contagious disease that may cause enormous damage in pig breeding and pig feeding farms . To provide maximum safety against contagious diseases result- ing from germs coming from other farms, it is an interesting idea to extend the filling pipe to outside the farmyard, because in that case it may be avoided that the bulk feed truck has to drive up the farmyard. The invention provides this option and is extremely suitable for this. There is no longer any need for carrying off sacks of dust, which used to be done by the driver of the bulk feed truck. Nor can any mistakes be made with the dust sack, for example, because it is forgotten to exchange the dust sack in time. When pressure surges in the filling pipe occur, the silo will not incur any damage. Since the filling pipe is longer than usual, because it is extended to outside the farmyard, work will be done with a higher pressure of the transport air, and thus the chance of occurrence of pressure surges will become greater and, moreover, the amplitude of the pressure surges can become larger. In accordance with claim 8 the invention likewise relates to a silo including the new arrangement that is described in claim 1.

The use of the arrangement as well as the implementation of the method according to the invention as a whole of- fers a plurality of characteristic advantages, that is to say:

- contamination of the silo due to the occurrence of condensation is avoided,

- dust and other feed particles carried along by the transport air are obstructed effectively, - the dust and particles carried along are added to the contents of the silo, so that there is no loss of feed, overpressure in the silo is limited to a permissible value,

- the filling pipe can be extended without any disad- vantageous effects to outside the farmyard, so that a factor of possible contagion by germs coming from other pig farms is eliminated.

The invention will now be described by way of non- limiting example with reference to the drawing which shows an example of an embodiment to which the invention is not restricted, and wherein:

Figure 1 is a diagrammatic side elevation of a silo, more specifically, a feed silo for grain-like to powder-like feed, for example pig feed, including an arrangement according to the invention,

Figure 2 shows a detail of the arrangement according to the invention of the silo shown in Figure 1, in cross section and on an enlarged scale,

Figure 3 shows in plan view, partly in cross section, a part of the arrangement according to the arrows 3-3 in Figure 2 , and

Figure 4 shows in side elevation a detail of a safety device present in the arrangement as shown in Figures 2 and 3.

Like component parts are referenced by like numbers in the various Figures. Figure 1 shows in general and in a diagram a substantially cylindrical silo 1 having a substantially cylindrical casing 3, an upper part 5 mounted thereon and a funnel-shaped portion 7 at the bottom. The silo is supported by three verti- cal columns 9. At the bottom there is a connection flange 11 for connecting a discharge pipe.

The arrangement 12 for filling the silo with a grainlike to powder-like material 13 by utilising transport air includes the upper part 5 of the silo, a filling pipe 15 con- nected to the silo 1, an aeration and/or de-aeration facility 17 connected to the silo, which is also used for carrying off the transport air used when the silo is being filled, and a dust filter 19 co-operating with the aeration and/or de- aeration facility 17 for obstructing the feed particles 23 carried along by the transport air when the silo 1 is being filled. Reference is made to Figures 2 and 3 for the dust filter. In the Figures 1 and 2 the arrow F shows the direction in which the feed and the transport air are blown through the filling pipe 15 when the silo is being filled. Figures 1, 2 4 and 5 further symbolically show how the transport air finally leaves the silo (arrows 23) .

As may very distinctly be seen in Figure 2, the dust filter 19 is installed in accordance with the invention on the upper part 5 of the silo 1, that is, in the middle on top of the upper part 5, aligned to the central axis 25. As will be discussed in more detail hereinafter, a further particular feature of the invention is that the dust filter 19 is used not only for obstructing feed particles 21 carried along by the transport air in the direction of the arrows 23, but also forms part of the aeration/de-aeration facility 17.

In the middle and on top of the upper part 5 of the silo 1 a pipe portion 27 is installed. The pipe portion is mounted in the middle of the upper part 5 of the silo and is aligned to the central axis 25. In the embodiment shown in the drawing the pipe portion 27 is screwed onto the upper part 5 of the silo by means of a fastening flange 29, but, in essence, other ways of fastening may also be used which guarantee a substantially sealing fastening of the pipe portion 27 to the upper part 5 of the silo, such as welding, sealing etc. The pipe portion 27 covers an opening 31 in the centre of the upper part 5 of the silo, which opening in the embodiment drawn has practically the same diameter as the inside diameter of the pipe portion 27. The open section of the pipe portion 27 has a surface that is at least twice as large as the sur- face of the open section of the filling pipe 15. In consequence, the transport air can escape to the environment through the pipe portion 27 in upward direction through the filter 19 at a rate that is considerably lower than the rate in the filling pipe 15. The dust filter 19 is installed on the upper part of the pipe portion 27. The upper part of the dust filter 19 is covered by a rain hood 33. The use of the latter is obviously to avoid rain reaching the filter 19 and thus possibly even reaching the inside of the silo. Between the dust filter 19 and the rain hood 33 there is an interstice, referenced number 35, for allowing air to pass through the filter 19, as is symbolically shown by the arrows 23, which air is flowing between the inside of the silo and the exterior.

The filling pipe 15 extends sideways through the pipe portion 27, that is to say, in a direction that is at least substantially perpendicular to the central axis 25 of the silo and thus also of the pipe portion 27. The filling pipe ends in a nozzle 35 running downward at least substantially along the central axis 25. Since the nozzle 35 is pointed down and runs along the central axis 25 of the silo, the silo is filled with feed 13 in a symmetrical way. This guarantees a proper, uniform and maximum filling of the silo. It is also advantageous for the nozzle 35 to be at a high position in the silo, so that the silo may have a high degree of filling, or in other words so that only little space is wasted in a fully filled silo.

Another advantage of the embodiment shown is that the upper part 5 of the silo, together with the aeration/de- aeration facility 17 and the part of the filling pipe 15 con- nected to the facility can be manufactured separately and beforehand as one unit in order to be mounted on the cylindrical portion 3 of the silo as a complete arrangement 12 at a later stage. The arrangement 12 can therefore be supplied as desired by a specialised supplier. The remaining part of the filling pipe 15 can be coupled to the upper part of the filling pipe at a later stage, for example, by means of flanges 37.

The rain hood 33 has the shape of an upside down pot with a cylindrical wall 39 and a conical roof 41. The rain hood 33 too is aligned to the central axis 25 of the silo and concentrically covers the pipe portion 27 while allowing for the above-mentioned interspace 34. In downward direction the rain hood 33 extends to a level that lies below the level of the dust filter 19. As can particularly well be seen in Figure 2, the dust filter 19 has the shape of an upside down flat- bottomed round bowl, at least in the situation that is represented in Figure 2, that is to say, during the filling operation in which the transport air passes through the filter. The filter may be made of, for example, a suitable filter cloth made of threads of natural and/or synthetic material suitable for this purpose. Such filter materials are already known from practice, so that a further description hereof will be omitted in this context .

In the interspace 34 between the pipe portion 27 and the cylindrical wall 39 of the rain hood 33 there is a shut- off element 43. In the embodiment drawn the shut-off element 43 substantially has an annular shape and consists of perforated metal plate. The shut-off element has air vents 45 which have a cross section that is small enough to largely prevent vermin entering the silo. For example, the air vents comprise square 10 x 10 mm perforations. The number of perforations and the total cross sectional area are large enough to allow air to pass with a pressure drop that is considerably smaller than the pressure drop that occurs when the transport air flows through the dust filter 19. Thus, in essence, the shut-off element 43 forms no obstruction for discharging the transport air from the silo. The shut-off element 43 has at its circumference a flange edge 47 over which the cylindrical wall 39 of the rain hood 33 fits with only a slight clearance. By means of this flanged edge 47 the rain hood 33 can be attached to the shut-off element 43, for example, by a plurality of nuts and bolts not shown in the drawing. More to the inside, the shut-off element 43 is rigidly fastened to the pipe portion 27 by welding. In this way the shut-off element 43 also acts as the carrier of the rain hood. For removing and/or exchanging the dust filter 19 the rain hood can be lifted from the shut- off element 43 by releasing the bolt connections mentioned above. For reaching the upper part of the silo, any suitable means such as stepladders or ladders etc. can be used. If nec- essary, the silo may be provided with fixed steps on the outside .

As can be clearly seen particularly in Figure 4, the filter holder is ring-shaped, the cross section of the ring- shaped portion having the form of an angle cross-section with an upright part 51 and a horizontal part 53. To the upper edge of the upright part 51 is welded a ring 55 that has a circular section. The lower part of the filter 19 is mounted on the upright part 51 of the filter holder 49 by means of a fastening element 57 just below the ring 55. This fastening element may have an arbitrary suitable shape and comprise, for example, an annular clamp, a wire or a band or the like.

The horizontal part 53 of the filter holder 49 abuts on a sealing edge 59 that is formed by the upper edge of the pipe portion 27. Especially the Figures 4 and 5 clearly show a safety device of the arrangement according to the invention, which resiliently loads the filter holder 49 in the direction of the sealing edge 59. This safety device comprises a plurality of U-shaped brackets 61 welded mutually equidistant at the top of the pipe portion 27 to the inside of the pipe portion 27. The legs of the U then leave such an opening as to leave a screwed rod 63 freely movable with some clearance. At the top the screwed rod projects through an opening in the horizontal part 53 of the filter holder 49. The screwed rod has a nut 65 screwed on at the top and a nut 67 screwed on at the bottom.

Between the bottom nut 67 and the bracket 61 a pressure spring 69 is mounted which is pre-compressed to a certain compression by tightening the bottom nut 67. At the top the compression spring presses against the bracket 61 via a locking ring 71. The compression spring 69 resiliently loads the sealing edge 59 with a pre-compression, which pre-compression is selected such that, when there is an unsafe air overpressure in the silo, the filter holder 49 is pushed away from the sealing edge 59. Figure 4 shows by arrows 23 how with normal operation of the aeration/de-aeration facility 17 transport air flows upward from a silo through the pipe portion 27 and flows to the exterior through the material of the dust filter 19. Figure 5 shows the situation in which for some reason or other, for example, because the air filter 19 is no longer capable of venting enough air to the exterior, for example when there is a pressure surge in the inside of a silo, the filter 49 is pushed away from the sealing edge 59, so that there is an interstice-like opening 73 between the top of the pipe portion 27 and the bottom of the filter holder 49, for allowing air to pass through to the exterior. As a consequence, the compression spring 69 is slightly more compressed between the bottom nut 67 and the U-shaped bracket 61 and the screwed rod 63 moves up between the legs of the bracket 61 over a distance that is equal to the height of the interstice-like opening 73. The air overpressure that is necessary for pushing the filter holder 49 up away from the sealing edge 59 is determined by the dimensioning of the springs 69 and by the extent to which the nuts 67 have been tightened. It will be evident that in this manner a suitable adjustment is possible of the value of air overpressure at which the safety device of the arrangement according to the invention is to become operable.

Figure 1 likewise illustrates the method according to the invention, which advantageously uses the arrangement 12 according to the invention. It shows that a silo 1, which is present on an industrial site 75 such as a farmyard, is filled with feed from a bulk feed truck 77. The bulk feed truck 77 includes a filling unit, which is not shown in the Figure but is well known from practice, to which is associated a filling hose 79. According to the invention the bulk feed truck 77 stayes outside the farmyard. In Figure 1 the boundary of the farmyard is diagrammatically indicated by a partition, fence, wall or the like indicated by reference number 81. The filling pipe 15 is extended to outside the farmyard by an extension 15' which may be temporary or not and is diagrammatically shown in the drawing by a dashed line. The extension 15' is coupled by flanges 83 to the filling pipe 15 and coupled by flanges 85 to the filling hose 79. During the filling operation powder feed to grain feed is pumped from the bulk feed truck 77 by means of transport air through the filling hose 79 and the filling pipe 15' - 15 into the silo, during which op- eration the transport air can escape through the aeration/de- aeration facility 17 as indicated by the arrows 23. The environment cannot be polluted then because of the presence of the dust filter 19 underneath the rain hood 33. Nor does contami- nation of the farmyard 75 by the bulk feed truck 77 occur, so that a considerable risk factor of contamination of the farmyard by pathogenic organisms of, for example, foot-and-mouth disease is eliminated without the farmyard being polluted, because the bulk feed truck 77 remains outside the farmyard, or without any other undesired situation occurring, such as the build-up of an impermissibly high overpressure in the silo 1 with the risk of the upper art 5 of the silo being blown off, or without the silo being damaged in some other way.

Although the invention is elucidated with reference to a single example of an arrangement, a method and a silo only, the invention is by no means construed as being limited thereto. In contrast, the invention extends to any embodiment within the scope of the appended independent claim 1, claim 7 and claim 8. For example, more specifically the aeration/de- aeration facility 17 may be formed differently, it may be positioned at another spot on the upper part of the silo, the filling pipe may not be led through the aeration/de-aeration facility 17, and so on.

The embodiment shown is based on a silo having a di- ameter of about 2 metres. The diameter of the filling pipe 15 is about 10 cm. The diameter of the pipe portion 27 is about 64 cm. The diameter of the rain hood 33 is about 80 cm. The perforations in the ring-shaped plate that forms the shut-off element 43 consist of square 10 x 10 mm openings. The springs 69 are dimensioned such that in the case of a 200 - 250 mm water column overpressure in the silo the filter holder 49 is lifted off the sealing edge 59. The material of the dust filter 19 is polyester cloth having a weight of 400 grammes/m² and an air permeability of 200 l/dm²/20 mm water column. The dimensions, materials used etc. may differ from those of the above example, depending on the requirements to be made .

Claims

1. An arrangement (12) for filling silos with a grain-like to powder-like material by using transport air, more particularly for filling feed silos (1) with grain-like to powder-like feed (13), including:

- a filling pipe (15) for filling a silo (1) ,

- an aeration/de-aeration facility (17) which is at least also used for discharging (23) the used transport air when a silo is being filled, as well as

- a dust filter (19) co-operating with the aeration/de-aeration facility (17) for obstructing feed particles (21) carried along by the transport air during the filling of the silo, characterized in

- that the dust filter is installed on top of an upper part of a silo, and

- that the dust filter also forms part of the said aeration/de-aeration facility.

2. An arrangement (12) as claimed in claim 1, characterized in that the said upper part (5) includes a pipe portion (27) having an open section whose surface is at least twice the surface of the open section of the filling pipe,

- that the dust filter (19) is located at the top of the pipe portion (27) ,

- that the dust filter (19) is covered by a rain hood (33), and

- that there is an interspace (34) between the dust filter (19) and the rain hood (33) for allowing air flowing between the inside of a silo (1) and the environment to pass through the filter (19) .

3. An arrangement (12) as claimed in claim 2, characterized in

- that the filling pipe (15) extends out of the said pipe portion (27) in a direction that is at least substantially perpendicular to the central axis (25) of the said pipe portion (27) , and - that the filling pipe (15) ends in a nozzle (35) that runs downward at least substantially along the central axis (25) of the said pipe portion (27) .

4. An arrangement (12) as claimed in claim 2 or 3 , characterized in

- that the rain hood (33) concentrically encloses the said pipe portion (27) while leaving an interspace (34) free,

- that the rain hood (33) extends downward to a level that lies below the level of the dust filter (19) and - that in the interspace (34) a shut-off element (43) is present which is provided with air vents (45) which have a transverse section that is small enough to largely avoid vermin entering a silo (1) but whose number, as well as the total surface of the cross section, are large enough to allow air to pass (23) with a pressure drop that is considerably smaller than the pressure drop of the dust filter (19) .

5. An arrangement (12) as claimed in claim 4, characterized in that the shut-off element (43) is connected to both the pipe portion (27) and the rain hood (33) and also serves as a carrier of the rain hood (33) .

6. An arrangement (12) as claimed in one of the preceding claims, characterized in

- that the dust filter (19) is mounted on a filter holder (49) , - that the filter holder (49) abuts on a sealing edge

(59) in a sealing fashion and

- that a safety device is present which resiliently loads the filter holder (49) in the direction of the sealing edge (59) with a pre-compression that is selected so that when an unsafe air overpressure occurs in the silo, the filter holder (49) is pushed off the sealing edge (59) to allow air to pass through (23) to the environment.

7. A method of filling a silo (1) including an arrangement (12) as claimed in one of the preceding claims and which is located on an industrial site (75) such as a farmyard from a road vehicle (77) that includes a filling unit characterized in

- that the road vehicle (77) remains outside the industrial site, - that the filling pipe, either or not by a temporary extension (15') extends to outside the industrial site (75),

- that the filling pipe (15, 15') outside the industrial site (75) is coupled to the filling unit of the road vehicle (77) .

8. A silo (1) including an arrangement (12) as claimed in one or more of the claims 1 to 6.