Study On Measurement Ethod Of Solid Mass Flow In Gas-solid Two-phase Flow

In modem industrial production,such as power,building materials,metallurgy,chemical,semiconductor,pharmaceutical and food processing,there are a wide range of gas-solid two-phase flow parameters.Real-time online measurement of key parameters of gas-solid,two-phase flow in the transmission pipeline is directly related to the product.The production efficiency and the safe and efficient operation of the system are of great significance for energy conservation and environmental protection.The electrostatic sensor is used for the measurement of gas-solid two-phase flow,which has the advantages of simple structure,good stability and high reliability.By analyzing the induced charge mechanism of electrostatic sensors,the relationship between mass flow rate,volume concentration and flow rate measurement methods was studied.The experimental test platform was built to explore the internal laws of particle electrostatic signals and measurement parameters,and the algorithm design and hardware fabrication were completed.And verification of measurement methods.The main research work includes the following aspects:The waveform characteristics of electrostatic signals under different volume concentrations were explored.The relationship between signal energy and power spectral density of electrostatic signals and particles with different volume concentrations were studied by theoretical analysis and experimental verification.The experiment found that the signal energy of the particle electrostatic signal is positively correlated with the volume concentration of the particle;the useflul signal power of the particle electrostatic signal is positively correlated with the volume concentration of the particle.A mathematical model for measuring the mass flow rate of solid particles was established.The model analysis showed that the particle volume concentration and flow rate were the two main parameters affecting the particle mass flow.Therefore,by measuring the particle flow rate and the volume concentration,the particle mass flow rate can be measured.Through the experiment,the variation of particle volume concentration with the energy of electrostatic signal is obtained.Two cubic spline interpolation methods based on electrostatic signal energy and least squares curve fitting method based on electrostatic signal energy are designed.Two FFT-based methods are used.The cross-correlation algorithm realizes the measurement of the flow velocity.Finally,the software and hardware implementation of the particle mass flow is completed and the experimental test is carried out on the experimental platform.The experimental results show that the electrostatic signal energy method is feasible to measure the mass flow.The mass flow measurement method of gas-solid two-phase flow based on BP neural network is studied.Through the analysis of the characteristics of the solid phase mass flow,there is a complex nonlinear relationship between the particle mass flow rate and the flow velocity and volume concentration of the particles flowing through the pipeline.Using the excellent nonlinear mapping ability of the BP neural network,the experimental data is taken as a sample.The training of the 3-layer BP network is carried out,and the online estimation of the mass flow of the gas-solid two-phase flow is realized.The soft flow model of mass flow based on BP network is established.The estimated value of the mass flow is obtained by experimentally testing the BP neural network model.The estimated value is compared with the actual value of the mass flow.The experimental results show that it is feasible to measure mass flow based on BP neural network method.