Developing and evaluation of an electrical impedance tomography system for measuring solid volumetric concentration in dredging scale

Abstract

In this study, an electrical impedance tomography (EIT) system was developed for measuring of sediments flow properties in dredging pipes. Considering relatively large diameter of the dredger pipe, salinity of seawater and online commitment of the system, some trade-offs were considered. A finite element model (FEM) was established for 16 EIT sensor to study the detection sensitivity. In the first stage, the EIT system is embedded in the loop of flow with diameter of 610 mm for the laboratory experiments, then the system performance was investigated in real conditions on a Suction Hopper Dredger. The EIT system performance was evaluated at three levels of NaCl concentration (7.5, 11.59 and 13.68 gr/lit) and temperature (17, 25, 30.7 °C). The standard deviation (SD) and root mean squire error (RMSE) parameters were used to evaluate the system performance, behind some conceptual assessments. Analysis of variance (ANOVA) of measured data show that the changes in salinity and temperature of liquid phase have no significant effect on the measured concentration by the EIT-based system. The coefficient of determination was almost 0.98 to 0.99 in different levels of sediment concentration that shows a linear trend and acceptable correlation between the data obtained from the EIT-based system and the data measured by the sampling method.