Measuring Techniques in Gas—Liquid and Gas—Liquid—Solid Reactors

Abstract

This article oers an overview of the instrumentation techniques developed for multiphase ow analysis either in gas/liquid or in gas/liquid/solid reactors. To characterise properly such reactors, experimental data have to be acquired at dierent space scale or time frequency. The existing multiphase ow metering techniques described give information concerning reactor hydrodynamics such as pressure, phases holdups, phases velocities, ow regime, size and shape of dispersed inclusions, axial diusion coecients. The measuring techniques are presented in two groups: the non-intrusive techniques that deliver global, cross-section-averaged or local data, and the intrusive probes that are dedicated to local measurements. Eventually some examples of multiphase instrumentation development are reported (trickle-bed and slurry bubble column at semi-industrial scale) in the renery or petrochemical area.

Bed height and material density effects on fluidized bed hydrodynamics

“…Therefore, it is important to classify these techniques according to the purpose of the analysis. Boyer et al (2002) classified the measurement procedures distinguishing between time averaged and transient measurements and between local and global measurements.…”

“…However, there were some limitations; for example, for gas holdup measurements, the precision was low compared to other techniques and required a larger experimental setup effort. (Boyer et al, 2002) Heat transfer probes may be used to describe the liquid phase within two-phase flows that have a moderate gas holdup. Hot film anemometry measures gas fraction and liquidphase characteristics, like mean velocity and RMS fluctuating velocity.…”

“…Optical and resistive probes cannot be used in all organic liquids because there are small differences in the refraction index with the gas phase, and also the low conductivity is sometimes very small for impedance probes (Boyer et al, 2002). For ultrasound probes, the limitation arises under high gas holdup conditions, causing a loss of effectiveness in the measurements.…”

Comprehensive experimental investigation of counter-current bubble column hydrodynamics: Holdup, flow regime transition, bubble size distributions and local flow properties

“…Among the different techniques, we employed needle probes. In general, two types of needle probes have been previously used for measurement in bubble columns: optical fiber and impedance/conductive probes (Boyer et al, 2002). Optical and impedance probes operate based on the differences in the refractive index or conductivity, respectively, of the liquid and gas phases.…”

Characteristic lengths and maximum entropy estimation from probe signals in the ellipsoidal bubble regime

“…More recently Boyer et al (2002) reviewed the application of these techniques to the case of two (gas/liquid) and three phase flows (gas/liquid/solid).…”