GB2145697A - Container for storing breakable pneumatically conveyed bulk material - Google Patents

Abstract

A container for storing breakable bulk materials is in the form of a buried silo or tank (1) with a base inclined downwardly to the horizontal in the direction of an outlet aperture (2). The base has a perforated ventilated region (7) through which compressed air can be supplied into the tank (1) to assist flow of bulk material therealong towards the outlet aperture (2). This reduces the number of pressure vessel stations conventionally required, reduces the stoppage times of road transport discharging material into the tank (1) and the bulk material is transported particularly gently through the tank (1) to its place of use. <IMAGE>

Description

SPECIFICATION Container for storing breakable, pneumatically conveyed bulk material This invention relates to a container for storing breakable bulk material, with at least one filling aperture at the top and an outlet aperture in the bottom region.

Containers of this type are widely known in the form of silos. The silos are filled from the bulk material transport means such as a road tanker, through a pneumatic conveying pipe. The material is usually discharged from the silo by gravity, aided if necessary by appropriate auxiliary means.

While this type of storage has proved to be appropriate for the majority of bulk materials, namely those suitable for pneumatic conveyance in flight, this does not apply to breakable bulk materials, which have to be conveyed in a dense flow in order to minimise the conveying speed and thus the danger of breakage. In this case the bulk material cannot be conveyed directly from the means of transport delivering it, e.g. via a cellular wheel sluice or a suction pipe, into the conveying pipe leading to the silo. Instead it has to be supplied, free flowing from the means of transport, to at least one pressure vessel station arranged in an underground pit. This station is usually equipped with two pressure valves, since it is not otherwise possible to obtain a throughput which would give an acceptable stoppage time for the means of transport, e.g. a road tanker.The pressure vessel station is connected to the conveying pipe leading to the silo or silos. Again the material can only be emptied out of the silo via a further pressure vessel station, connected to the conveying pipe which leads to the place of use, e.g. a weighing container.

There is thus a need to simplify the storage of breakable bulk materials.

According to the invention there is provided a container for storing breakable bulk material, with at least one filling aperture at the top and a discharge outlet aperture in the bottom region, which container is in the form of a tank buried in the ground with a base inclined downwardly to the horizontal in the direction of the outlet aperture, and which tank has a peforated bottom region connectibleto a source of compressed gas whereby gas under pressure can be supplied into the bottom of the tank to assist movement of the bulk material therealong towards the outlet aperture.

The buried tank may be filled directly from the means of transport delivering the material, e.g. from the road tanker, even through more than one filling aperture simultaneously, provided that the tanker has a plurality of outlet pipe connections. In this way the expensive stoppage times for the tanker can be kept very short. At the same time the invention dispenses with the pressure vessel station hitherto required, and with the downstream pneumatic conveying pipe to the silo, as well as the additional pressure vessel station downstream of the silo outlet. This resuits in a smaller capital investment, less damage to the material and lower energy consumption. There is also considerably less outgoing air to be filtered. The silo foundations previously required of course become unnecessary.

Finally, with the container in the form of a buried tank, the space requirement above ground and the conspicuousness of the installation are much diminished.

Four a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example to the accompanying drawings, in which Figure 1 is a diagrammatic view of an installation equipped with a container according to the invention, and Figure 2 is a diagrammatic cross-sectional view through the container of Figure 1.

As shown in Figure la a container according to one embodiment of the invention is a silo or tank 1 which is buried or embedded in the ground below ground level inclined downwardly to the horizontal towards its discharge outlet aperture 2, and which has a plurality of filling apertures 3. The tank 1 can be filled with breakable bulk material 5 to be stored, from a road tanker 4, through the apertures 3 either in succession or simultaneously. It is further provided with an excess pressure valve 6 and a perforated base 7. The base 7 can be supplied with compressed air from a compressed gas source 9 from the underside via pipes 8 (see Figure 2), to enhance the flowing movement of the bulk material 5 down the tank towards the discharge aperture 2.

The part of the tank 1 containing the discharge aperture 2 extends into a pit 10, from which the tank 1 is accessible, e.g. through a manhole, and which may also accommodate auxiliary means for emptying the tank. The outlet aperture 2 of the container or tank is located at or adjacent its lowermost point is connected by a pneumatic conveying pipe 11, generally to a plurality of separators, of which only one is illustrated (at 12). From the separator 12 the breakable bulk material can be conveyed, e.g. through a conveying screw 13, directly into the container of a container-type weighing balance 14. The separator 12, conveying screw 13 and balance 14 do not form part of the invention.

However, it should be emphasised that it is only the tank 1 that makes it possible to charge the separator 12 with bulk material without using one or more pressure vessel stations, so apart from the capital costs saved a particularly gentle method is obtained fortransporting the material from the tanker 4 to its place of use.

Figure 2 shows that each filling aperture 3 of the tank 1 includes a hopper 3a and a stop valve 3b. The perforated base 7 is supplied with compressed air from a compressed air pipe 8 and a plurality of branch pipes 8a, 8b and 8c. The compressed air pipe 8 is also connected to the conveying pipe 11, and the distribution of the volume of air of the base 7 and to the pipe 11 is adjusted as desired by valves 15a and 15b.

A cellular wheel sluice may be arranged between the outlet 2 of the tank 1 and the conveying pipe 11, specially for dense flow conveying, which is preferable for breakable bulk materials. The sluice enables the conveying process in the pipe 11 to be controlled particularly accurately in respect of the quantity and state of the material.

Claims (3)

1. Acontainerforstoring breakable bulk material, with at least one filling aperture at the top and a discharge outlet aperture in the bottom region, which container is in the form of a tank buried in the ground with a base inclined downwardly to the horizontal in the direction of the outlet aperture, and which tank has a perforated bottom region connectible to a source of compressed gas whereby gas under pressure can be supplied into the bottom of the tank to assist movement of the bulk material therealong towards the outlet aperture.

2. A container according to claim 1, wherein the buried tank is a silo with its longitudinal axis inclined to the horizontal and with the outlet aperture at or adjacent its lowermost point, and wherein a pneumatic bulk material conveying pipe is connected to the outlet aperture.

3. A container for storing breakable bulk material, substantially as hereinbefore described with reference to the accompanying drawings.