A Dual-Modality Integrated Sensor for Electrical Capacitance Tomography and Electromagnetic Tomography

Process tomography techniques play an important role in visualizing and monitoring industrial processes, which help to produce high quality product without affecting the work flow in plants. The industrial process tomography techniques, i.e., electrical tomography and computerized tomography, have been widely applied. Such tomographic tools can be used to investigate various types of multi-phase flows, in which the components may differentiate in density, conductivity, and permittivity. In a gas-liquid-solid flow, however, it is usually difficult for the existing tomographic tools to visualize the distributions of all three phases. In addition, it is necessary to assume some simplifications, i.e., by viewing two disperse phases as one unified phase. The objective of this research is to provide a dual-modality imaging tool by combining electrical capacitance tomography (ECT) and electromagnetic tomography (EMT). First, an integrated dual-modality sensor was designed and implemented on the same cross-section of the process vessel. Subsequently, dual-modality tomographic measurements were collected by a custom-built multi-channel impedance measurement system. The performance of the dual-modality sensor was verified by numerical simulations and experimental tests, showing that it can produce reliable ECT and EMT measurements at a satisfying signal-to-noise ratio. The complementary tomographic images can be obtained from ECT and EMT, and the distributions of two disperse phases, i.e., gas and solid phases, can be observed. The preliminary image fusion results were also given by combining the information from both the ECT and EMT images.