DD270978B5

DD270978B5 - METHOD FOR DETERMINING THE SHOOTING DENSITY OF A FOERDERSTROMES

Info

Publication number: DD270978B5
Application number: DD28864386A
Authority: DD
Inventors: Christian Dr-Ing Krone; Rolf Dr-Ing Schubert; Willfried Balzar; Corinna Decker
Original assignee: Ver Energiewerke Ag
Priority date: 1986-04-02
Filing date: 1986-04-02
Publication date: 1993-10-28
Also published as: DD270978A1

Description

The invention relates to a method for determining the bulk density of a flow during its weighing on a

radiometrischen Bandwaage nach dem Durchstrahlungs- und Absorptionsprinzip mittels mehrerer Gamma-Strahlenquellen und -Strahlendetektoren zur Flächenmassemessung, die an mehreren, über den Horizontalteil der Bandmuldung verteiltenradiometric belt scale according to the transmission and absorption principle by means of several gamma radiation sources and radiation detectors for mass measurement, which are distributed over several, over the horizontal part of the Bandmuldung

Supporting points form measuring channels whose measured values are determined by means of the polynomial approximation in a computing unit Mass determination are linked. In the case of radiometric belt weighers, it has hitherto always been assumed that the balance is at the measuring location with test material

kalibriert wird, wobei Einflüsse des Meßgutes und der Meßgeometrie berücksichtigt werden müssen. Diese Kalibrierung ist sehr kostenaufwendig. Die Bereitstellung der Prüfgutmenge ist häufig mit sehr großen Schwierigkeiten verbunden. Werden radiornetrische Förderbandwaagen ohne Prüfgut kalibriert, wirkt sich eine schwankende Schüttdichte des Meßgutes aufgrund der Querschnittsform der Fördergutschicht erheblich auf den Meßwert aus, da die Extrapolationsbedingungen verändsrt werden.is calibrated, whereby influences of the material to be measured and the measuring geometry must be taken into account. This calibration is very expensive. The provision of the Prüfgutmenge is often associated with very great difficulties. If radiornetric belt weighers are calibrated without test specimens, a fluctuating bulk density of the test object due to the cross-sectional shape of the conveyed material layer has a significant effect on the measured value, since the extrapolation conditions are changed.

For radiometric mass determination on conveyor belts has already been proposed by means of some radiation sources

und Detektoren übe - die Gurtbandbreite verteilt Meßstützstellen zu schaffen und aus dem Meßwerten dieser Meßstützstellen mitand detectors übe - to create the Gurtbandbreite distributed Meßstützstellen and from the measured values of these Meßstützstellen with

Help the polynomial approximation to determine the complete bulk material profile. When calibrating the measuring device is a

die Geometrie des Fördergutes im Meßfeld hinreichend beschriebendes Polynom zugrunde gelegt.the geometry of the conveyed in the measuring field sufficiently descriptive polynomial basis.

To determine the bulk density has also been proposed, in the area of a support point for the Measuring the surface mass with another measuring device to measure the layer thickness of the conveyed material, from both measured values

die Schüttdichte zu ermitteln und als Rechengröße für die Bestimmung der Flächenmasse über die gesamte Breite desTo determine the bulk density and as a calculation size for the determination of the basis weight over the entire width of the

To be used. A disadvantage of this solution is that a deviating from the radiometry measurement method (laser, Ultrasound, mechanics) must be used, which is structurally extremely unfavorable. Another proposed method for the radiometric mass determination of bulk solids involves the simultaneous Radiation of the Meßgutschicht in the vertical direction to determine the contour of the bulk profile and in horizontal Direction through the Bandmuldung to determine the bulk density of the transported material. Unfavorable here is the required

konstruktive Mehraufwand, da zusätzlich ein Sonden- und ein Strahlerteil erforderlich sind.additional design effort, since in addition a probe and a radiator part are required.

For the radiometric determination of bulk solids on conveyor belts using forward scattering

von Quantenstrahlen ist es bekannt, bei jedem Meßzyklus unabhängig von der Vorwärtsstreuung zusätzlich die Schichtdicke zu bestimmen und die zu dieser Schichtdicke gehörige aktuelle Eichkurve aus einer vorher ermittelten Eichkurvenschar auszuwählen und zur Auswertung heranzuziehen (DD 159816). Es soll damit der Einfluß von Schichtdickenschwankungen auf die Bewegung der Gammaquanten bei der Vorwärtsstreuung kompensiert werden. Eine Flächenmassebestimmung ist bei dieser Lösung nicht vorgesehen.It is known from quantum beams to additionally determine the layer thickness for each measuring cycle independently of the forward scattering and to select the actual calibration curve belonging to this layer thickness from a previously determined calibration curve family and to use it for evaluation (DD 159816). It is intended to compensate for the influence of layer thickness fluctuations on the movement of the gamma quanta in the forward scattering. A basis weight determination is not provided in this solution.

The invention is based on the object in the determination of the bulk density of a flow on a radiometric Belt scales, in which at several nodes measuring channels are formed, the measured values with the aid of Polynomial approximation for mass determination, the influence of fluctuating bulk density on the extrapolation

der Meßwerte der Stützstellen zu vermeiden.to avoid the measured values of the interpolation points.

This is achieved in that in the inclined part of the Bandmuldung the basis weight of the Meßgutschicht in a separate

radiometrischen Meßkanal bestimmt wird, die Meßwerte dieser Flächenmasse mit den Erwartungswerten aus derradiometric measuring channel is determined, the measured values of this basis weight with the expected values from the

Polynomial approximation of the measuring channels in the horizontal part of the band toleration are compared, from both values of Basis weight for a defined absolute area of the basis weight with moving averaging a factor is formed,

der als Soll-Größe für die iterative Führung des Rechenwertes Schüttdichte des Meßgutes für die Berechnung der Bandbelegung aus dem Flächenpolynom herangezogen wird.the bulk density of the material to be measured is used as the set value for the iterative guidance of the calculated value for the calculation of the band assignment from the area polynomial.

The invention will be explained in more detail below using an exemplary embodiment. The accompanying drawing shows the Schematic diagram of an arrangement for determining the bulk density of a flow on a radiometric Belt weigher. The Fördergutschicht 1 to be measured is located between a radiator part 2 and a probe part 3 of the radiometric Measuring device with a plurality of radiometric measuring channels 4.1 to 4.4, preferably three measuring channels 4.1 to 4.3 im Horizontal part and a measuring channel 4.4 are arranged in the inclined part of Bandmuldung. From the probe part 3 lead Signal lines 6 to a microcomputer. When working with the radiometric belt weigher, the pulse rate from the measuring channels 4.1 to 4.4 in Microcomputer evaluated as basis weight. The results of the measurements are used to calculate the contour of the Bulk profiles of Fördergutschicht 1 for a given bulk density of the transported material. For the position of the measuring channel 4.4, a basis weight is calculated therefrom and determined with the basis weight determined in the measuring channel 4.4

verglichen. Aus beiden Werten ergibt sich in Abhängigkeit von der realen Schüttdichte ein Faktor, der über eine gleitendecompared. From both values, depending on the real bulk density, there is a factor that has a sliding

Averaging as a set value for the iterative guidance of the calculated value Bulk density of the material to be measured for the calculation of the Band assignment is taken from the area polynomial. With the method according to the invention, continuous measurement with minimal effort has the influence

schwankender Schüttgutdichte eliminiert und damit eine hohe Meßgenauigkeit bei der Massebestimmung an radiometrischenfluctuating bulk density and thus eliminates a high measurement accuracy in the mass determination of radiometric

Conveyor belt trolley reached.

Claims

Method for determining the bulk density of a flow when weighing it on a radiometric belt weigher according to the transmission and absorption principle by means of several gamma radiation sources and radiation detectors for surface mass measurement, which form at several, distributed over the horizontal part of Bandmuldung support points measuring channels, the measured values with the aid of Polynomial approximation in an arithmetic unit for mass determination are linked, characterized in that in the inclined part of Bandmuldung the basis weight of the Meßgutschicht is determined in a separate radiometric measuring channel, the measured values of this basis mass are compared with the expected values from the Polynomapproximation the Meßkanäle in the horizontal part of Bandmuldung, from both Values of the basis weight for a defined absolute range of the mass per unit area with moving averaging a factor is formed, which is as a set size for the iterative guidance of the rake value of bulk density of the material to be measured is used for the calculation of the band allocation from the area polynomial.

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