Method and vortex flow measuring device for monitoring and/or measuring wall flow of a medium of two or more phases flowing in a pipeline

摘要

A method for monitoring and/or measuring an, at least at times, two-phase medium flowing in a pipeline, and having a first phase, especially a gaseous first phase, with a first density and a second phase, especially a liquid second phase, having a second density different from the first density. The method is performed with a vortex flow measuring device, which has at least one measuring tube inserted into the pipeline, a bluff body and a vortex sensor. In such case, the vortex sensor includes a sensitive section that responds to pressure fluctuations, and that is arranged at least partially adjoining the wall of the measuring tube. In the method, a wall flow of a second phase of a two or more phase medium is detected by the vortex flow measuring device, when a measurement signal which contains characteristic features for an interaction of a wall flow of the second phase of a flowing medium flowing along a wall of the measuring tube with the sensitive section of the first vortex sensor is registered by the vortex sensor.

主权项

1. A method for monitoring and/or measuring a two-phase medium flowing in a pipeline and including a first phase, with a first density and a second phase, with a second density different from the first density, said method comprising:
using a bluff body protruding into the flowing medium for producing Kármán vortices in the flowing medium at least near a vortex sensor placed downstream the bluff body, said vortices being shed by the bluff body with a vortex shedding frequency dependent on an instantaneous flow velocity of the flowing medium; permitting at least a portion of the second phase of the flowing medium to flow along a wall near the vortex sensor; using said vortex sensor registering periodic pressure fluctuations caused by the Kármán vortices in the flowing medium and for producing a sensor signal corresponding to the pressure fluctuations; selecting from the sensor signal a wanted signal component, signal component exhibiting a frequency band containing the vortex shedding frequency; and using the wanted signal component selected from the sensor signal for detecting the presence of the second phase of the flowing medium.