Density measuring device

Abstract

The invention relates to a desity measuring device which is used to measure a density, rho, of a flowable medium and comprises measuring device electronics (ME) and a measuring transducer (MW) electrically connected to the measuring device electronics. The measuring transducer comprises a measuring tube (10), a vibration exciter (41) for exciting and maintaining vibrations, and a vibration sensor (51) for sensing vibrations of the at least one measuring tube. The measuring device electronics are designed to adjust, by means of a vibration measurement signal (s1) and an exciter signal (e1), a driving force that causes useful vibrations, namely vibrations having a specified useful frequency, fN, of the measuring tube, in such a way that a phase shaft angle, phi N, by which a velocity response, VN, of the measuring tube is phase shafted with respect to a useful force component, FN, of the driving force is less than -20 and greater than -80 degrees during a specified phase control interval, and / or the useful frequency has a frequency value that is more than 1.00001 times but less than 1.001 times a frequency value of an instantaneous resonance frequency of the measuring tube. Furthermore, the measuring device electronics are designed both to determine at least one frequency measured value, xf, representing the useful frequency for said phase control interval on the basis of the vibration measurement signal (s1) present during the phase control interval and to generate a density measured value, x rho, representing the density, rho, by using the frequency measured value, xf.

Description

technical field [0001] The invention relates to an electro-vibratory density measuring device for measuring the density p of flowable media, in particular fluids flowing in pipelines. Background technique [0002] As a rule, in industrial measurement technology, especially also with regard to the control and monitoring of automated manufacturing processes, in order to determine with high precision the density of a medium such as a liquid and / or gas flowing in a process line such as a pipeline, the application is by means of measuring device electronics Components (most often by means of at least one processor) and an oscillating measuring transducer that are electrically connected to the measuring device electronics and flow through during operation of the medium to be measured form a vibrating density measuring device. Such density measuring devices have been known for a long time, for example in the form of so-called four-conductor devices or so-called two-conductor device...

AI Technical Summary

Problems solved by technology

The disadvantage of such a correction based on measuring the viscosity of the medium guided in at least one measuring tube or on the attenuation of the desired oscillation depending thereon is in particular that the attenuation not only depends on the viscosity but also to a certain extent on the actual to-be-measured so that initially unknown medium density

Consequently, the density measurement determined by applying the viscosity or attenuation values ​​generated by means of the electronics of the measuring device may in practice still have considerable, if not intolerable, measurement errors

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