Simulation study on electrical resistance tomography using metal wall for bubble detection

Industrial process pipelines are mostly known to be constructed from metal which is a conducting material. Bubbles or gas detection are crucial in facilitating the bubble columns performance. By employing the Electrical Resistance Tomography (ERT) technique, a simulation study using COMSOL has been conducted to investigate the effect of excitation strategy, bubble sizes and locations towards the metal wall system. As for the current excitation strategy, conducting boundary protocol has to be applied when it comes to metallic vessel to overcome the grounding effect. Bubbles with a greater size than 2 mm and especially the one that is located near the wall boundary are much easier to detect. Further potential improvements to the current design and image reconstruction of the ERT system are desirable to improve the detection of small and centred bubble

A review of ultrasonic tomography for monitoring the corrosion of steel pipes

Infrastructure development is currently taking place rapidly. Designing a dwelling or premises is currently implemented quickly while controlling construction costs in addition to providing guidance on planned development. The architecture uses steel as a main part of the pile and drainage system is connected from sources to consumer. This study focuses on steel pipes that are exposed to corrosion. This problem is considered serious because steel pipes are used not only for the delivery of water supply but also for the delivery of gas and oil to the oil and gas sector, where the same problem occurs. Impacts of the problem of corrosion of steel pipes contribute to the risk of loss to the owner of the premises or industry. An overview of leakage problems, which cause a reduction in the volume of materials or hazards to the environment and consumers, is given, and the occurrence of corrosion in pipelines is evaluated. Monitoring methods use ultrasonic tomography as a major contribution to the implementation of monitoring and assessing the status of pipe durability and ability. This paper looks at the concept of diverse ultrasonic tomography inventions used to assist the process of monitoring of the level of pipeline capacity that will suffer corrosion

Study and design of an ultrasonic flow tomographic front-end multi level measurement system

With the rapid evolution of electro-acoustical technology, ultrasonic tomography has made considerable progress in industry. An ultrasonic tomography system provides non-invasive and non-intrusive flow visualisation that enhances the understanding of fluid flow processes. The function of ultrasonic tomography is to continuously monitor the dynamics of liquid flow without interrupting the flow. The ultrasonic tomography technique is fully supported by a front-end hardware system. The front end is defined as all the hardware circuitries, including the ultrasonic transducer up to the Analogue-to-Digital Convertors (ADCs), even though the primary focus is the analogue signal processing components. We present here the challenges and trade-offs in the implementation of a front-end system by first explaining the basic operation of such a system, and then indicating what particular performance parameters are needed to ensure optimal system operation. Based on the results from our research studies, we propose an improved front-end multi-level solution that is more accurate than previous solutions and provides real-time measurement capability

Inspection by ultrasonic tomography (UT) leading trend in welding joint monitoring

Welding work is a connection process between the structure and the materials. This process is used in the construction, maintenance and repair especially mechanical engineering. This study discusses the type of welding used in the industry, mainly involving the pipeline welds. On-demand need to every work process when finishing weld requires quality tests to ensure compliance to the standards required. Monitoring through the display image has long been used in Non-Destructive Testing (NDT). Various methods of monitoring used in NDT focused on Ultrasonic Tomography (UT) as a method used in NDT and as an option for the future. Previous imaging result was in two-dimensional (2D) and then upgraded to a three-dimensional image (3D). Besides, there is potential of 3D imaging beyond the existing limits in terms of size, material thickness, especially for welding steel pipes. Achievement through research of existing pipe size so far outside diameter of 200 mm and a thickness of 5.8 mm should be limited in view of the obstacles to enhanced image resolution is less effective when compared to other tomography methods

Simulation of electrode for dual-modality electrical resistance tomography and ultrasonic transmission tomography for imaging two-phase liquid and gas

Accurate multiphase flow measurement of gas/liquid, liquid/solid and liquid/liquid flow is still challenging for researchers in process tomography. The reconstructed images are poor particularly in the center area because of ill-posed inverse problems and limited of measurements data. Dual-modality tomography has been introduced to overcome the problem by means each modality is sensitive to specific properties of materials to be imaged. This paper proposed combination of ultrasonic transmission tomography (UTT) and electrical resistance tomography (ERT) for imaging two phase gas/liquid. In the proposed combination, detection ability in the medium of interest improved because two different images in the same space can be obtained simultaneously. This paper presents 3D numerical modeling approach using COMSOL software for ERT excitation strategy and electrode pre-designed geometry. Electrical resistance tomography (ERT) can be implemented for gas/liquid flow if the liquid is conductive. The objectives of this work is to analyze the optimum electrode dimension and shape in order to improve the situation of: (1) gas bubble detection located in the centre of the medium, (2) potential distribution and current density in a conductive medium, the developed numerical model simulated the changes in resistivity of the conductive material, with variations of electrode sizes, with opposite current excitation implemented into the region of interest. Simulation results show that the electrode size of 12 mm (w) × 40 mm (h) is suitable, which gives a good detection of center gas bubble with diameter 10mm in 100-mm-diameter acrylic vessel. Finally the findings are verified with Image reconstruction using Linear Back Projection (LBP) which gives good indication of the 10mm gas bubble

A review on electrical capacitance tomography sensor development

Electrical Capacitance Tomography (ECT) detects changes in the distribution of transparency in enclosed areas or pipes. Until now, various methods have been used to determine the optimum ECT sensor for a particular application. Some important parameters that affect the sensitivity of the sensor cannot be ignored. Design factors discussed in this paper study the needs in industry by producing the best image, without affecting the operation of the process. From previous studies many parameters influence the quality and effectiveness of an ECT sensor. The parameters that play important roles in ECT sensor design include the thickness and type of material in the pipe wall between the electrodes and the sensing zone, the thickness and material of the pipe wall separating the electrodes and the screen, the size of the electrodes, the guarding used, example radial guards or plane axial guards, and whether end guards are used. Other matters of concern regarding the dimension and the distance between the electrodes with guardians it is important design factor. Electrodes positioned either inside or outside the vessel will affect the cost factor design to the type of system to be used. This overview of the study is a basic guide for the essential requirements for an ECT sensor system design

Image reconstruction of metal pipe in electrical resistance tomography

This paper demonstrates a Linear Back Projection (LBP) algorithm based on the reconstruction of conductivity distributions to identify different sizes and locations of bubble phantoms in a metal pipe. Both forward and inverse problems are discussed. Reconstructed images of the phantoms under test conditions are presented. From the results, it was justified that the sensitivity maps of the conducting boundary strategy can be applied successfully in identifying the location for the phantom of interest using LBP algorithm. Additionally, the number and spatial distribution of the bubble phantoms can be clearly distinguished at any location in the pipeline. It was also shown that the reconstructed images agree well with the bubble phantoms

Hardware Development of Dual-Modality Tomography Using Electrical Resistance and Ultrasonic Transmission Tomography for Imaging Liquid and Gas

In decades, single-modality technique focuses on particular application such as liquid/gas, gas/solid, liquid/liquid and liquid/solid which has drawbacks in imaging complex flow with multiple components. This paper focuses on the development of dual-modality tomography system (DMT) integrating ultrasonic tomography and electrical resistance tomography (ERT) to visualize cross-sectional images of two-phase liquid/gas in vertical column. A combination of soft-field and hard-field tomography system measures different physical parameters of two-phase liquid/gas specific of two different material properties which are conductivity (σ) and acoustics impedance (Z). A DMT system is developed with 16 units of ultrasonic transceiver sensors, and 16 units of ERT electrode positioned alternately on a single-plane arrangement to perform measurement simultaneously. The reconstructed tomographic images obtained from measurement data from these two modalities are then fused into a single tomographic image by employing discrete wavelet transform (DWT)

Application study on bubble detection in a metallic bubble column using electrical resistance tomography

Electrical resistance tomography (ERT) has been chosen as the field of study because of its advantages of being low cost, suitable for various kinds and sizes of pipes and vessels, having no radiation hazard, and being non-intrusive. In the development of ERT systems for metallic bubble column, prior knowledge of the fundamental process of the ERT system whilst improving the design and operation of the process equipment is essential. The fabricated electrodes need to be electrically insulated from the metal wall. Besides that, conducting boundary strategy is implemented to overcome the grounding effect of the metallic vesse

Hardware Development of Dual-Modality Tomography Using Electrical Resistance and Ultrasonic Transmission Tomography for Imaging Liquid and Gas

In decades, single-modality technique focuses on particular application such as liquid/gas, gas/solid, liquid/liquid and liquid/solid which has drawbacks in imaging complex flow with multiple components. This paper focuses on the development of dual-modality tomography system (DMT) integrating ultrasonic tomography and electrical resistance tomography (ERT) to visualize cross-sectional images of two-phase liquid/gas in vertical column. A combination of soft-field and hard-field tomography system measures different physical parameters of two-phase liquid/gas specific of two different material properties which are conductivity (σ) and acoustics impedance (Z). A DMT system is developed with 16 units of ultrasonic transceiver sensors, and 16 units of ERT electrode positioned alternately on a single-plane arrangement to perform measurement simultaneously. The reconstructed tomographic images obtained from measurement data from these two modalities are then fused into a single tomographic image by employing discrete wavelet transform (DWT)