[China Instrument Network Instrument R&D] On May 6, the Chinese Academy of Sciences revealed that new progress has been made in the development of a gas-solid fluidized bed reactor measurement and control system developed by the Engineering Thermophysics Institute. Gas-solid fluidization is a complex multi-phase flow system widely used in energy, chemical, pharmaceutical, food and other fields. On-line monitoring of flow characteristics is the key to improving process efficiency and ensuring the safe and stable operation of the system.
System R&D test platform
Gas-solid fluidization presents non-stationary and multi-scale effects in time and space, and involves multi-parameter information fusion. Therefore, online monitoring of key parameters is an international research hotspot and difficulty in the field of parameter detection. Due to the limitation and deficiency of the detection method in the traditional single point measurement model, it is difficult to reflect the internal fluid dynamics characteristics of the complex area, and the internal parameters of the flow system cannot be obtained.
In response to the above problems, the CFB Laboratory of the Institute of Engineering Thermophysics, Chinese Academy of Sciences, takes complex gas-solid fluidization as the main line, and conducts capacitance and microwave process tomography, numerical simulation of complex gas-solid flow processes, and online identification of flow parameters. The three aspects of theoretical research and signal processing are integrated with key technologies to form a multiphase flow on-line monitoring theory and method that can be applied to complex gas-solid flow systems, providing test platforms and means for gas-solid flow related industrial processes.
Through the implementation of the project, the researchers carried out early research on capacitive and microwave dual-mode tomography at the international level. By combining the difference in capacitance and microwave response characteristics of dielectric constant and conductivity, the researchers integrated the two information into complex gas. The solid flow process, especially the medium with a large range of dielectric conductivity variation and significant differences in dielectric constant, provides image analysis and provides a new model for on-line measurement of solid particle humidity.
Test site
Based on the principle that the capacitance tomography can measure the solid particle concentration distribution and the microwave Doppler can measure the speed, the project researchers have combined the capacitance and microwave Doppler measurement methods for the first time in the world, providing a kind of online gas-solid flow measurement. In the new mode, this measurement method has the characteristics of no interference and fast measurement speed. Through the above theoretical research and development of key technologies, a non-linear imaging algorithm for tomography under complex gas-solid flow conditions has been formed and applied to the large-scale gas-solid flow process optimization control; a combined capacitive sensor has been developed and correspondingly constructed. The imaging algorithms and evaluation systems provide an online, nondestructive monitoring method for gas-solid flow-related process control.
At present, some achievements of the instrument development project have been tested on the marine multiphase flow experimental platform of the Shenzhen Graduate School of Tsinghua University and the coal powder multiphase flow experimental system of the Aerospace Changzheng Chemical Co., Ltd., and good results have been achieved.
The project was supported by the major research equipment development project of the Chinese Academy of Sciences. Based on the experimental platform and test system in the previous part, the researchers conducted a measurement of the drying process of the fluidized bed with wet particles. The research results were recently received and published by the international journals Powder Technol. and Meas. Sci. Technol. and won the 2015 China Engineering Thermophysics. The Annual Meeting of Multiphase Flow "Young Scholar Chen Xuejun Outstanding Paper Award" applied for 2 invention patents.
(Original title: Advances in the Development of a Measurement and Control System for Gas-solid Fluidized Bed Reactors in Engineering Thermophysics)
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