Concentration profiles of dry powders in a gravity conveyor using an electrodynamic tomography system
TL;DR: In this article, a tomographic system using an array of electrodynamic sensors is presented, where sensitivity maps are derived for individual sensors and then used by a back-projection algorithm to calculate concentration profiles from measured sensor values.
Abstract: This paper presents results for a tomographic system using an array of electrodynamic sensors. Sensitivity maps are derived for the individual sensors and then used by a back-projection algorithm to calculate concentration profiles from measured sensor values. Limitations in linearity over the sensing area are reduced by applying a filter to the images. The filtered back-projection algorithm is tested both on uniformly and on artificially produced non-uniformly distributed solids' flows.
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TL;DR: In this article, the effect of geometric and material parameters of an electrostatic sensor array (ESA) on the spatial sensitivity and temporal frequency response of a single particle having a unity charge was investigated.
46 citations
TL;DR: Two methods, the back-projection (BP) method and the least-squares (LS) method, were applied to the electrodynamic tomography system.
Abstract: Two methods, the back-projection (BP) method and the least-squares (LS) method, were applied to the electrodynamic tomography system Electrostatic charges were assumed to exist in the sensing zone, and their images were reconstructed using these methods The reconstructed images were compared with the original ones The BP method is accurate in detecting the position of the electrostatic charge and is capable of detecting the size of the object The BP method could not distinguish two charges at separate points in the sensing zone The LS method could differentiate two points of charge, but the reconstructed images were of poor quality due to the large pixel size A reconstruction algorithm combining the two methods produced better results
41 citations
TL;DR: A comprehensive review of the electrostatic sensors and sensing systems that have been developed for the measurement and monitoring of a range of process variables and conditions, and their signal conditioning electronics, signal processing methods as well as possible new applications are discussed.
41 citations
TL;DR: In this article, the authors describe measurements made on a gravity drop conveyor using two arrays of axially spaced electrodynamic sensors to measure axial velocities close to the wall of the conveyor and velocity profiles both of flowing sand and of plastic beads.
Abstract: This paper describes measurements made on a gravity drop conveyor using two arrays of axially spaced electrodynamic sensors to measure axial velocities close to the wall of the conveyor and velocity profiles both of flowing sand and of plastic beads. The level of correlation obtained using pixels is investigated. The velocity profile is combined with a tomographic concentration profile to estimate the mass flow profile, which is summed over the measurement cross section to estimate the mass flow rate. A calibration of the tomographically determined mass flow rate versus the actual mass flow rate is presented.
39 citations
TL;DR: A new image reconstruction method – Least squares with regularization (LSR) will be introduced to reconstruct the image of material in a gravity mode conveyor pipeline for electrical charge tomography and results show that the accuracy of the reconstruction images obtained was enhanced and similar to the image captured by a CCD Camera.
Abstract: Electrical charge tomography (EChT) is a non-invasive imaging technique that is aimed to reconstruct the image of materials being conveyed based on data measured by an electrodynamics sensor installed around the pipe. Image reconstruction in electrical charge tomography is vital and has not been widely studied before. Three methods have been introduced before, namely the linear back projection method, the filtered back projection method and the least square method. These methods normally face ill-posed problems and their solutions are unstable and inaccurate. In order to ensure the stability and accuracy, a special solution should be applied to obtain a meaningful image reconstruction result. In this paper, a new image reconstruction method - Least squares with regularization (LSR) will be introduced to reconstruct the image of material in a gravity mode conveyor pipeline for electrical charge tomography. Numerical analysis results based on simulation data indicated that this algorithm efficiently overcomes the numerical instability. The results show that the accuracy of the reconstruction images obtained using the proposed algorithm was enhanced and similar to the image captured by a CCD Camera. As a result, an efficient method for electrical charge tomography image reconstruction has been introduced.
36 citations
Cites background from "Concentration profiles of dry powde..."
...From equation (1) and is derivation it shows that the total charge induced into the sensor, Q is given by equation (2) [14]: /2 V 2 2 3/2 /2 qxW d Q = 4π [(y-a) +x ] l...
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TL;DR: In this paper, the surface contact electrodes are located in a closed loop or rosette array on one planar or nominally planar, skin surface of a body to be investigated, and electrically connected to data acquisition and processing equipment.
Abstract: In an APT method, the surface-contact electrodes are located in a closed loop or rosette array on one planar, or nominally planar, skin surface of a body to be investigated, and electrically connected to data acquisition and processing equipment. The invention also includes apparatus for carrying out this method, comprising an array of surface-contact electrodes (8), adapted to be applied to the skin of a body to be investigated, the electrodes (8) being arranged on a flexible carrier (10) in a closed loop, or rosette formation on one common plane, or nominal plane.
735 citations
TL;DR: Theoretical and experimental studies of cross correlation techniques applied to non-restrictive velocity measurement of pneumatically conveyed solids using ring-shaped electrodynamic flow sensors are presented in this article.
Abstract: Theoretical and experimental studies of cross correlation techniques applied to non-restrictive velocity measurement of pneumatically conveyed solids using ring-shaped electrodynamic flow sensors are presented. In-depth studies of the electrodynamic sensing mechanism, and also of the spatial sensitivity and spatial filtering properties of the sensor are included, together with their relationships to measurement accuracy and the effects of solids' velocity profiles. The experimental evaluation of a 53 mm bore sensing head is described, including trials using a calibrated pneumatic conveyor circulating pulverized fuel and cement. Comparisons of test results with the mathematical models of the sensor are used to identify important aspects of the instrument design. Off-line test results obtained using gravity-fed solids flow show that the system repeatability is within +or-0.5% over the velocity range of 2-4 m s-1 for volumetric concentrations of solids no greater than 0.2%. Results obtained in the pilot-plant trials demonstrate that the system is capable of achieving repeatability better than +or-2% and linearity within +or-2% over the velocity range 20-40 m s-1 for volumetric concentrations of solids in the range 0.01-0.44%.
200 citations
TL;DR: In this paper, the first application of a non-invasive capacitance tomographic technique to monitoring the behaviour of industrial-scale pneumatic conveyors was described, and the results showed that particle breakage rates are inversely related to the solids loading factor.
78 citations
TL;DR: In this article, the theoretical response of capacitance sensors to permittivity impulse signals is derived and compared with experimental data, where a machine is used to drive a plastic bead through both types of electrodes to obtain the impulse response for comparison with theoretical predictions.
Abstract: Capacitance sensors are finding increased application in the measurement of two-component flow. An important parameter in these measurements is the frequency bandwidth of the ring and parallel plate types of sensing electrodes. In this paper the theoretical response of these electrodes to permittivity impulse signals is derived and compared with experimental data. A machine is used to drive a plastic bead through both types of electrode to obtain the impulse response for comparison with theoretical predictions. Experimental results are presented for beads travelling along the central axis of the sensor and near to its wall. For electrodes with an active length greater than 40 mm theory and experiment agree, for shorter lengths an electrode length coefficient is introduced. This gives the minimum effective length of this type of electrode as 30 mm, which is attributed to field fringing effects.
73 citations
TL;DR: In this paper, four different sensing techniques are discussed based on capacitive, electrostatic, microwave and nucleonic principles with regard to their homogeneous sensing characteristics, and the mass flow rate of randomly distributed solids flowing in pneumatic conveyors is measured.
41 citations