Transactions of the Institute of Measurement and Control

doi: 10.1177/0142331220907716pmid: N/A

doi: 10.1177/0142331220907715pmid: N/A

Paglianti, Alessandro; Maluta, Francesco; Montante, Giuseppina

doi: 10.1177/0142331219842318pmid: N/A

Salt particles dissolution in slurry stirred tanks provides an ambitious challenge for the application of Electrical Resistance Tomography in the process industry, because the presence of high loadings of inert particles requires a purposely developed post-processing method of the experimental data. For the optimization of the working conditions of the dissolution process, two characteristic times are required: the time for the liquid homogenization in the tank and the time required for the complete dissolution of the salt particles. The former time has been experimentally determined in previous investigations both in stirred tanks working with single-phase and with multiphase mixtures. The latter characteristic time has not been analyzed so far, due to the lack of experimental procedures for distinguishing it from the former. In this work, a novel approach for the simultaneous identification of the two characteristic times is presented. The impact of the new procedure is significant for the production processes, since it offers a tool for identifying when the soluble particle size has an impact on the dissolution dynamics, and when the stirred tank dynamics is influenced by the liquid homogenization only, and therefore a reduction of the particle size does not speed up the process accomplishment.

Tu, Qiuya Y; Wang, Haigang G

doi: 10.1177/0142331219851913pmid: N/A

With the increase of capacity, most of the circulating fluidized beds (CFB) risers are constricted to have rectangular cross section. Therefore, it is important to find out the cross-sectional aspect ratio effect on the gas-solids flow characteristics. In this study, a lab-scale CFB with two rectangular risers, which have the aspect ratio of 1:1 and 3:1, respectively, were studied by the electrical capacitance tomography (ECT), with the aided of pressure measurements and computational particle fluid dynamics (CPFD) simulation. Key issues related with ECT sensor design and image reconstruction, such as sensitivity map and excitation frequency, are also discussed. The results show that ECT image quality is affected by the sensitivity map and excitation frequency, and high excitation frequency and voltage are not equivalent of high image quality. In the riser bottom region, cross-sectional aspect ratio has big effect on ECT measured particle distribution and pressure drop, fewer particles are brought away from the bottom when the aspect ratio is larger. Multiple bubbles exist in the bottom region at Ve= 2.7 m/s, and bubble size decreases in the rectangular riser with larger cross-sectional aspect ratio. Static bed height influences the bubble behaviour that bubbles with smaller size scattered around and behave collapse or coalescence in the moving process when the static bed height is high.

Liu, Hao; Tan, Chao; Dong, Feng

doi: 10.1177/0142331219853073pmid: N/A

Two-phase flow is a regime that commonly existed in many applications of process industry, on which the technique of ultrasonic tomography (UT) could provide reliable measurement with benefits of non-invasion, non-radiation and low-cost. In order to provide considerable visualization of low acoustic impedance contrast configurations in two-phase flow, a regular weighted simultaneous algebraic reconstruction technique (RW-SART) using continuous-wave excitation is proposed and presented in detail. With measurement strategy and formulized reconstruction model introduced, the measurement system is introduced with modification on continuous-wave excitation module and fan-beam angle transducers. A regularized weighted least square (RWLS) framework combining total variation (TV) regularization and SART reconstruction is derived and presented in detail to address the problem that under-determined and ill-conditioned situation couldn’t be resolved simultaneously. Both numerical simulation and experimental investigation are conducted to validate the feasibility of continuous-wave excitation and the improvement of proposed reconstruction strategy, from which the distribution of oil-water two-phase flow is effectively reconstructed. The implementation of measurement system provides an option of continuous high-voltage excitation and measurement in UT. By utilizing both the geometric information and penalty constraint, the proposed reconstruction approach provides a framework that introduces regularization information to the algebraic iteration reconstruction. Consequently, it has better reconstruction result than TV, Landweber, L1, filtered back projection (FBP) and SART method.

Rymarczyk, Tomasz; Kozłowski, Edward; Kłosowski, Grzegorz

doi: 10.1177/0142331219857374pmid: N/A

The article presents non-destructive testing based on electrical impedance tomography (EIT) for spatial (3D) monitoring of flood embankments. Therefore, to solve the inverse problem of the EIT, an effective algorithm based on multiple elastic nets has been developed. The originality of the solution is based on the application of many elastic net algorithms as functions, each of which, based on the vector of all measurements, generates the value of a single pixel for the reconstructed image. In this way, the set of elastic nets is equal to the resolution of the image output. Such an approach, although requiring more computing power, yields high resolution images. In addition, the presented algorithms are characterized by high noise immunity and distortion of measurement data. Five different electrode systems were tested in the samples and compared with each other in two measurement variants (stimulations). A reconstruction made on the basis of actual measurements obtained from the physical model was also presented.The presented solution provides a visual analysis of seepages and leaks, which allows for quick and effective intervention and possible prevention of dangers. The research proved that the use of tomographic measurement techniques in combination with the image reconstruction algorithm based on elastic net allows for non-invasive and very accurate spatial assessment of leaks and damages of flood embankments. The received results confirm the effectiveness of the presented research.

Wang, Zhilong; Zhao, Tong; Kanzawa, Masanori; Liu, Kai; Takei, Masahiro

doi: 10.1177/0142331219857414pmid: N/A

This paper investigated the particle dispersion behaviours of Lithium-ion battery (LIB) slurry by using electrical impedance spectra-tomography (EIST) method from the perspective of experiment and simulation. In the experiment, an EIST system composed of Field—Programmable Gate Array (FPGA), multi-plexer, switch circuit and 8-electrode sensor is developed to measure the frequency response of LIB slurry under two different conditions, which are rotation speed n=0rpm with rotation time t=0min and n=100rpm with t=6min. In the simulation, four different geometry structure models, which are (a) Carbon Black (CB) linear formation, (b) CB aggregation, (c) CB & LiCoO2 aggregation and (d) network dispersion, are established. Six frequencies, which are f=1 kHz, f=10 kHz, f=50 kHz, f=100 kHz, f=250 kHz and f=500 kHz, are used for the reconstructed conductivity images of LIB slurry in both the experiment and the simulation. The numerical simulation is used to verify the correctness of the experiment results. After combining the experiment and the simulation, it is concluded that the agglomeration behaviours of CB and LiCoO2 particles appear within LIB slurry in the case of n=0rpm with t=0min, while CB path and part LiCoO2 particles coated by CB particles appear in the case of n=100rpm with t=6min. Moreover, high frequencies are suitable to distinguish high conductive CB components from LIB slurry. Furthermore, the developed EIST system has the capability of monitoring particle dispersion behaviours in LIB slurry, which has the potential to be used for the on-line measurement of LIB slurry in order to improve the performance of LIB.

Suppan, Thomas; Neumayer, Markus; Bretterklieber, Thomas; Puttinger, Stefan

doi: 10.1177/0142331219884808pmid: N/A

Pneumatic conveying systems have become a standard technique for the transport of bulk materials such as powdery or granulates. The spatial dependence of the material density and the stream velocity in such transport systems require a volumetric measurement principle for flow measurement. In this paper we analyse the capability to estimate the volume fraction from capacitive sensing data using electrical capacitance tomography (ECT). In particular, we investigate the capability of back-projection type imaging algorithms. The ill-posed nature of the imaging problem of ECT require the incorporation of prior knowledge in the design of the estimator. We analyse the different flow profiles in pneumatic conveying in order to generate specific sample-based prior information to improve the estimation performance and robustness. We discuss the construction of different linear image reconstruction algorithms and present a framework, which allows a detailed statistical analysis of the estimator performance. Simulation studies show the estimation behaviour of different algorithms with respect to the incorporated prior information. We demonstrate, that the incorporation of specific prior knowledge leads to an improved estimator behaviour; for example, reduced variance and unbiased estimates. We implemented laboratory experiments in order to analyse the presented approach for the application in real pneumatic conveying processes. We demonstrate the improved robust estimation behaviour by means of comparative reconstruction results obtained with different algorithms and priors. Furthermore, the uncertainty of the estimated volume fraction is analysed in steady state conveying processes. Hereby, it is demonstrated, that appropriate prior information improves the estimation performance also for measurements coming from real pneumatic conveying processes, making ECT a suitable tool for the volume fraction estimation in such transport systems.

Che, Hanqiao; Wang, Haigang; Ye, Jiamin; Yang, Wuqiang

doi: 10.1177/0142331219875349pmid: N/A

Wurster fluidised bed is commonly used for coating pellets in the pharmaceutical industry. Normally, the control in a Wurster fluidised bed for coating is based on point-based measurement, that is, pressure and optical probes. However, the point-based measurement methods only provide local flow information and cannot reveal the cross-sectional flow dynamics characteristics and it is difficult to control the whole process with limited data. In this paper, electrical capacitance tomography (ECT) is applied to reconstruct the solids distribution in a lab-scale Wurster fluidised bed for coating pellets and the measurements are used in a control loop of the process. The flow regime is identified from the ECT images using a simple but efficient approach. The objective of control is to keep stable minimum fluidisation and avoid undesired flow regime in the region between the outside wall and the Wurster tube, such as intermittent, plug and defluidisation. To achieve this target, a PID controller is applied to keep a low volume fraction in the annular region by adjusting the fluidisation air rate, and bang-bang control is applied to a peristaltic pump used for spraying coating solutions based on the detected flow regime. It has been found that the proposed control scheme based on the ECT measurement is effective for keeping a stable flow regime, reducing the degree of pellets agglomeration and avoiding defluidisation.

Knott, Andy J; Robinson, Ian A

doi: 10.1177/0142331219880700pmid: N/A

This paper describes the characterisation of the dynamic response of a range of pressure transducer systems. The transducers were subjected to virtually instantaneous pressure step inputs in the National Physical Laboratory’s shock tube facilities. The magnitudes of these pressure steps were derived from ideal gas theory, with prior commissioning tests having been performed to demonstrate the theory’s validity in this application. The results demonstrate a significant variation in response obtained from various combinations of transducer, instrumentation settings, and mounting arrangement.