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Abstract:In the oil industry, huge saving may be made if suitable multi-interface level measurement systems are employed for effectively monitoring crude oil separators and efficient control of their operation. A number of techniques, e.g. externally mounted displacers, differential pressure transmitters and capacitance rod devices, have been developed to measure the separation process with gas, oil, water and other components. Because of the unavailability of suitable multi-interface level measurement systems, oil separators are currently operated by the trial-and-error approach. In this paper some conventional techniques, which have been used for level measurement in industry, and new development are discussed.

Gas-solids fluidised beds are commonly used in particle-related processes, e.g. for coal combustion and gasification in the power industry, and coating and granulation process in the pharmaceutical industry. Because the operation efficiency depends on the gas-solids flow characteristics, it is necessary to investigate the flow behaviour. This paper is about application of process tomography, including electrical capacitance tomography (ECT) and microwave tomography (MWT), in multi-scale gas-solids fluidisation processes in the pharmaceutical and power industries. This is the first time that both ECT and MWT are applied for this purpose with multi-scales and complex structure. To evaluate the sensor design and image reconstruction and to investigate the effects of sensor structure and dimension on the image quality, a normalised sensitivity coefficient is introduced. In the meanwhile, computational fluid dynamic (CFD) analysis based on a computational particle fluid dynamic (CPFD) model and a two-phase fluid model (TFM) is used. Part of the CPFD-TFM simulation results are compared and validated by experimental results from ECT and/or MWT. By both simulation and experiment, the complex flow hydrodynamic behaviour in different scales is analysed. Time-series capacitance data are analysed both in time and frequency domains to reveal the flow characteristics.

Most existing portable capacitance meters are not stray-immune, i.e., their measurements are affected by stray capacitance between the measurement terminals and earth. Therefore, it is difficult to measure small capacitance, say less than 10 pF, using those meters. This article describes a portable stray-immune capacitance meter based on a four-phase charge transfer measuring circuit. It has two measurement ranges, 2 and 20 pF. The resolution for the two different measurement ranges is 0.001 and 0.01 pF, respectively. Together with a current-to-voltage converter, it can also be used as an industrial capacitance transducer with 0–20 mA current output.