Environmental Engineering Reference
In-Depth Information
With regards to the fluid processing-related industry, measurement and control
of liquid parameters play an important role in industrial applications, for example,
in the petrochemical industrial processing. In this field, additional stringent require-
ments frequently deal with the spatial localization of non-miscible-layered liquids
and with the depth estimation of different layers of liquid. As an example, during
the refinery industrial processing, a portion of water is often present in the bottom
of the tanks, as a non-miscible fraction, and its continuous monitoring is crucial.
For this purpose, typically, various flow meters are used for fiscal and quality pur-
poses; nevertheless, the a-priori knowledge of the permittivity of the involved fluid
components, and the associated sample calibration are mandatory for the practical
implementation of such methods.
Starting from these considerations, in this chapter, first, a time domain-based
approach for the simultaneous estimation of the dielectric characteristics of liquid
materials and of their level is presented. It is shown that the analysis of time domain
reflectometry (TDR) data allows, in one shot, the measurement of liquid levels,
the determination of multiple interfaces in layered media, as well as the evalua-
tion of dielectric properties. Experimental results demonstrate the robustness and
reliability of the proposed method. As reported in [21], which compares the perfor-
mance of different liquid level sensors, TDR fares well with respect to other sensing
technologies.
Secondly, an enhancement of the simultaneous measurements of liquid levels and
dielectric permittivity is achieved through the implementation of the TD/FD com-
bined approach described in subsection 3.6.4. The proposed combined approach al-
lows the evaluation of the Cole-Cole parameters of the considered samples. Indeed,
accuracy enhancements are obtained also through some novel strategies that include
i) an appropriate probe design; ii) the realization and the adoption of a custom-made
fixture for allowing calibration measurements to be performed; and, most impor-
tantly, iii) a targeted optimization routine that renders the method extremely robust.
Results deriving from simple TDR technique are compared with those achieved, in
frequency domain, both through the fast Fourier transform (FFT)-based processing
of TDR data and through direct measurements with vector network analyzer (VNA).
The comparison between the reference and the frequency-domain extrapolated val-
ues of permittivity and levels shows a very good agreement.
Finally, in this chapter, the estimation of the Cole-Cole parameters through BMR
is applied to edible liquids: in particular, an interesting test-case for vegetable oils
is presented. Also in this case, starting from TDR measurements, the proposed ap-
proach allows the accurate estimation of the Cole-Cole parameters of the considered
oils, thus providing a method useful for qualitative and anti-adulteration control pur-
poses (which are regarded as crucial issues in the specific sector).
The common important feature of the proposed approaches is the possibility
of automating the necessary data-processing, thus providing results in real time.
On such bases, the proposed procedures can be considered as excellent candi-
dates for qualitative and quantitative liquid monitoring applications, with relevant
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