Method and apparatus for gravimetric metering of powdery bulk material
The present invention concerns a method and an apparatus for gravimetric metering of a powdery bulk material, said system comprising a storage container accommodating the bulk material, a feeding pipe for feeding bulk material from the storage container to a dosing container, a dosing discharge device for continuously discharging bulk material from the dosing container to a discharge pipe and on to a discharge line, wherein said dosing container is mounted on at least one weighing cell, and wherein the feeding pipe is provided with a first flexible tube member and the discharge pipe is provided with a second flexible tube member, and wherein the first flexible tube member comprises a first compensator and a second compensator with a tubular member there between.
1. An apparatus for gravimetric metering of a powdery bulk material, said system comprising:
a storage container accommodating the bulk material;
a mounting frame;
a dosing container fixedly supported by the mounting frame;
a feeding pipe for feeding bulk material from the storage container to a dosing container, the feeding pipe having a first flexible tube member, the first flexible tube member comprising a first compensator and a second compensator with a rigid tubular member arranged between the first compensator and the second compensator, the rigid tubular member being fixed to the mounting frame;
a discharge pipe fixedly supported by the mounting frame;
a dosing discharge device for continuously discharging bulk material from the dosing container to the discharge pipe; and
at least one weighing cell, the dosing container being mounted on the at least one weighing cell and the discharge pipe is provided with a second flexible tube member.
2. The apparatus according to claim 1 , further comprising a pneumatic feeding system, the pneumatic feeding system being fixedly supported on the mounting frame.
3. The apparatus according to claim 1 , wherein a breather pipe is provided between an upstream end of the discharge pipe and a top end of the dosing container.
4. The apparatus according to claim 1 , wherein the feeding pipe is provided with a sluice.
5. The apparatus according to claim 1 , wherein the dosing discharge device is a screw conveyor adapted for continuously providing a predetermined volumetric amount of bulk material.
6. The apparatus according to claim 5 , wherein the screw conveyor is adapted to provide a predetermined rotational speed in order to achieve the predetermined volumetric amount of bulk material.
7. The apparatus according to claim 1 , wherein a plurality of feeding pipes is provided connecting a plurality of dosing containers to a common storage container.
8. A method of gravimetric metering of a powdery bulk material, said method comprising the steps of:
batch feeding bulk material from a storage container through a feeding pipe to a dosing container mounted on at least one weighing cell;
continuously discharging bulk material from the dosing container to a discharge pipe by a dosing discharge device for further processing of the bulk material;
recording the gravimetric weight of the dosing container by the at least one weighing cell;
whereby the feeding pipe is made axially flexible to compensate for any external displacement of the storage container and the feeding pipe, the feeding pipe being provided with a first flexible tube member and the discharge pipe being provided with a second flexible tube member, wherein the first flexible tube member comprises a first compensator and a second compensator with a tubular member therebetween, and wherein the tubular member is fixed to a mounting frame, which also fixedly supports the storage container and the discharge pipe.
9. The method according to claim 8 , further comprising a pneumatic feeding system, the pneumatic feeding system being fixedly supported on the mounting frame.
10. The method according to claim 8 , whereby any pressure difference between upstream end of the discharge pipe and the top end of the dosing container is equalized by a breather pipe.
11. The method according to claim 8 , wherein the feeding pipe is provided with a sluice.
12. The method according to claim 8 , wherein the dosing discharge device is a screw conveyor adapted for continuously providing a predetermined volumetric amount of bulk material.
13. The method according to claim 8 , wherein said screw conveyor is adapted to provide a predetermined rotational speed in order to achieve the predetermined volumetric amount of bulk material.
14. The method according to claim 8 , wherein the storage container is feeding a plurality of feeding pipes connecting a plurality of dosing containers.