DE19650217A1 - Central=cone silo with pneumatically assisted discharge for storing e.g. cement, fly ash, quicklime, hydrated lime, alumina - Google Patents

Abstract

The silo for storing and homogenising powder-form, fluidisable material has at least two discharge apertures in a central cone, and pneumatic aerating elements at the bottom. There is an output chamber (3) with several input apertures (5) inside the silo in front of each discharge aperture. A relief line (8) runs into the upper space of the silo. The bottom of the output chamber has the pneumatic aerating elements in it. The output chamber may be formed by two angled side walls. The spacing between which increases radially, forming a saddle with its greatest height against the silo wall.

Description

The invention relates to central cone silos with pneumatic discharge aids for storage and Homogenization of powdery, fluidizable materials such as raw meal Cement production, cement, fly ash, quick lime, hydrated lime, alumina.

The state of the art in the pneumatic emptying of large silos is characterized by central cone silos with many individual outlets (DE 30 07 113), mixing chamber silos with a central, separately vented mixing chamber (DE-AS 2 121 616), large silos with roof-shaped covers (DE 36 14 962), mixing silos with an annular chamber (DE patent application 195 21 882.5) or central cone silos with walk-in tunnel-shaped internals (DE patent application 195 21 881.7)
All silos of the "mixing chamber" type have the advantage that the mixing chamber has large openings and a separate vent, but necessarily only one discharge opening. The amount of air supplied does not need to be regulated according to the outlet mass flow, as is the case with central cone silos (Harder, Buchfink: Schüttgut 1 ( 1995 ) Issue 2, April / June, pp. 271-280). If only a small quantity of material is drawn off in central cone silos without a mixing chamber, the outlet speed of the bulk material / air mixture would always be greater in comparison to a large mass flow without an air quantity regulation. This is the case since the blower system is designed according to the requirements of the largest outlet mass flow. The result is increased wear and tear, particularly with changing fume cupboards.

Another disadvantage of the central cone silo is the high number of discharge openings corresponding extraction and metering devices. This is necessary to at the periphery of the To have as few dead areas as possible. This disadvantage is caused by the one set of tunnel-shaped internals minimized, but these internals can be the previously written disadvantage of the high air and bulk material speed can not be eliminated.  

A major advantage of the central cone silos is the low construction effort and the low air requirement, since only the area between the silo wall and the cone base is ventilated is tested.

A disadvantage of the mixing chamber silos as well as the ring chamber silos is the high air consumption, because a large part of the chamber is strongly ventilated. In addition, with a conventional A horizontal, statically unfavorable silo bottom can be provided in the mixing chamber In an annular chamber, high chamber walls are also required. The mixing chamber itself must also be very high since the bulk material is placed in the fluidized bed and as a result of the Silo pressure the fluidized bed height can be up to 10 m. The construction effort for a Mixing chamber silo is in any case larger than for a central cone silo.

In order to increase the mixing effect of a silo, the silo activity, i. H. that actively silo volumes involved in homogenization can be increased. This can be achieved through the increase in the number of outlet troughs in the silo room. For central cone silos means that an increase in the number of discharge openings and thus the equipment mass Conveying and dosing devices.

The invention is based, with a central cone silo the silo activity Reduction in air consumption without increasing the number of discharge openings need to increase with appropriate extraction and metering devices, a wide one Control range for the outlet mass flow without regulating the amount of loosening air to realize a lower construction effort compared to mixing chamber silos and to reduce the wear of the discharge and metering units.

This object is achieved with the features of claim 1. Advantage adhesive refinements of the invention are specified in the subclaims.

According to the invention, a combination between a pure central cone silo and a mixing chamber silo with an outlet in front of each discharge opening in the central cone  Chamber with low height is connected upstream, the several inlet openings to Main silo room, is ventilated with a constant amount of air and with a Ent power line for the blown air is provided. The discharge chamber is made up of each Weil formed two inclined side walls, the distance between them increases radially and the the greatest height on the inner wall of the silo.

The advantages of the silo according to the invention are that with a high mixing effect of the material in the silo, the outlet mass flow through the metering units is freely set that can be done without having to regulate the air supply. By the fiction solution, the construction effort of the silo is reduced compared to a mixing silo and reduces the equipment mass on conveying and dosing devices. At the same time the silo is operated with a smaller amount of air that is discharged from the system, that the wear on the dosing devices is reduced.

The invention is explained in more detail using exemplary embodiments. In the associated show drawings:

Fig. 1 a longitudinal section of the silo according to the invention in section;

Fig. 2 shows a cross section of the silo.

The silo according to the invention is provided with a central cone 1 , which in this special case has four discharge openings 2 for the removal of the material stored in the silo. The number of discharge openings 2 depends on the size of the silo and is equal to or greater than two. An outlet chamber 3 is arranged in front of or above each discharge opening 2 . The outlet chamber 3 has the shape of a saddle and is formed in each case by two inclined side walls, the distance between which increases radially and the greatest height of which is on the inner wall of the silo. Each outlet chamber 3 is filled with pneumatic Auflockerungsele elements 4 and has several inlet openings 5 to the main silo room, so that distributed over the silo cross section a large number of outlet flow is generated, sixteen in the case shown.

The floor of the main silo room is also covered with pneumatic loosening elements 6 . These loosening elements 6 are not all vented at the same time, but one after the other in order to save air. A sector 7 can, for example, be the group of ventilation elements in front of one side of the outlet chamber 3 or only a part of it or the groups on both sides of the outlet chamber 3 , depending on the size of the silo.

The operation of the silo according to the invention is as follows. The bulk material is pressed from the ventilated sector 7 into the ventilated outlet chamber 3 and is partially relieved of the silo pressure there, but without being displaced into the free fluidized bed. In contrast to the simple central cone silo, the air can now escape through a relaxation line 8 , which is advantageously mounted on the silo wall. It does not need to be pushed through the discharge opening at high speed, which would cause high wear on the dosing devices. The expansion line 8 is connected to the silo upper space, so that the air is discharged via the dust removal system of the silo.

The outlet mass flow can be freely adjusted by suitable metering devices without to regulate the air supply. Even with large silos, you usually come along four discharge openings, with conventional central cone silos up to twelve openings would be necessary.

The outlet chambers 3 can be built lower than in mixing chamber silos, since the bulk material is not placed in the fluidized bed. Only as much air is blown in as is necessary to destroy bulk material bridges due to the bulk material cohesion.

Reference list

1

Central cone

2nd

Discharge opening

3rd

Outlet chamber

4th

Loosening element

5

Inlet opening

6

Loosening element

7

sector

8th

Relaxation line

Claims (4)

1. Central cone silo with pneumatic discharge aids for the storage and homogenization of powdery, fluidisable substances with at least two discharge openings in the central cone and pneumatic loosening elements arranged on the bottom, characterized in that in the silo interior in front of each discharge opening ( 2 ) of the central cone ( 1 ) an outlet chamber ( 3 ) with several inlet openings ( 5 ) and egg ner relaxation line ( 8 ), which leads into the silo upper room, is arranged, and that the bottom of the outlet chamber ( 3 ) with pneumatic loosening elements ( 4 ) is seen ver. 2. Central cone silo according to claim 1, characterized in that the outlet chamber ( 3 ) is formed from two inclined side walls, the distance between which increases radially, so that a saddle is formed, the greatest height of which is present on the silo wall. 3. Central cone silo according to claim 1 and 2, characterized in that the expansion line ( 8 ) is attached to the silo wall. 4. central cone silo according to claim 1 to 3, characterized in that the pneumatic loosening elements ( 6 ) are combined in sectors ( 7 ) which are ventilated separately according to a control algorithm.