Fast and Precise Soft-Field Electromagnetic Tomography Systems for Multiphase Flow Imaging

Abstract

In the process industry, measurement systems are required for process development and optimization, as well as for monitoring and control. The processes often involve multiphase mixtures or flows that can be analyzed using tomography systems, which visualize the spatial material distribution within a certain measurement domain, e.g., a process pipe. In recent years, we studied the applicability of soft-field electromagnetic tomography methods for multiphase flow imaging, focusing on concepts for high-speed data acquisition and image reconstruction. Different non-intrusive electrical impedance and microwave tomography systems were developed at our institute, which are sensitive to the local contrasts of the electrical properties of the materials. These systems offer a very high measurement and image reconstruction rate of up to 1000 frames per second in conjunction with a dynamic range of up to 120 dB. This paper provides an overview of the underlying concepts and recent improvements in terms of sensor design, data acquisition and signal processing. We introduce a generalized description for modeling the electromagnetic behavior of the different sensors based on the finite element method (FEM) and for the reconstruction of the electrical property distribution using the Gauss-Newton method and Newton's one-step error reconstructor (NOSER) algorithm. Finally, we exemplify the applicability of the systems for different measurement scenarios. They are suitable for the analysis of rapidly-changing inhomogeneous scenarios, where a relatively low spatial resolution is sufficient.

Electric Fields in Energy and Process Engineering

“…The removal of pollutants in flue gas [3] is mainly focused on volatile organic compounds (VOC) and nitric oxides (NO x ) as well as particulate matter (PM, for which electrostatic precipitators (ESP) [4] are applied). Furthermore, an overview, regarding the usage of plasma and electric fields for measuring process parameters in technical systems, which is deepened in a contributed article [5], is provided. A special topic is the usage of laser-based techniques, providing insights into plasma processes and electro-hydrodynamic effects [6].…”

“…Mallach et al [5] provide a detailed overview of different non-intrusive soft-field electromagnetic tomography systems. They are utilized for multiphase mixture and flow imaging in pipes for application in the process industry.…”

Study on a New Electromagnetic Flow Measurement Technology Based on Differential Correlation Detection

“…Since the traditional EMF cannot distinguish between the actual flow signal and interference noise, thereby only eliminating one type of interference, interference noise cannot be removed synchronously. Inappropriate noise elimination even introduces new interference to the system, leading to a lower measurement accuracy [5][6][7]. Therefore, great significance is attached to improving the signal-to-noise ratio, distinguishing interference components, and eliminating interference.…”

Gas Void Fraction Measurement of Gas-Liquid Two-Phase CO2 Flow Using Laser Attenuation Technique

“…Moreover, the impurities in pipelines will contaminate the probe and increase the measurement error. The visualization method, based on high-speed cameras and tomography algorithms [18,19], has been well developed to measure the gas void fraction. However, the disadvantages of a high cost, complex construction and unsuitability in harsh environments restrict its applications.…”