Research On Pneumatic Conveying Flow State Using Pressure Loss And Electrostatic Method

Pneumatic conveying system is widely used in power generation, steel production field and other industrial areas and many scholars and experts are focus on security and stability in conveying process. The pipeline flow state of the gas-solid two-phase flow is a very important parameter to describe the state of pneumatic conveying process. Because of the gas-solid two-phase flow condition is very complex, which makes the measurement of its flow state to become difficult. But in the actual industrial field, security and stability of pneumatic conveying system is very important. Therefore, from the traditional pressure loss analysis and electrostatic signal analysis, this paper explores the pipeline flow state of the dilute phase gas-solid two-phase flow for qualitative analysis.This paper researched the each performance of traditional pressure loss signal and electrostatic signal on the pipeline flow state of the gas-solid two-phase flow. The electrostatic signal mainly represents micro-characteristic of interaction between gas phase and solid phase particles and interaction of each solid particles. The pressure signal mainly represents the macroscopic property of the interaction between gas phase and solid phase. Using these two modes to analyze the pipeline flow state of the gas-solid two-phase flow can be more accurate. The main work of this paper is shown as followed:1. Based on the model of additional pressure, calculated the pressure loss on gas-solid two-phase flow experimental device in Tianjin University, and measured the pressure signal at the straight horizontal pipeline. Then analyzed the flow state of the gas-solid two-phase flow according to the measurement results.2. Analyzed mathematical model of arc array electrostatic sensor, and then explore the influence of the electrostatic sensor's spatial sensitivity.3. Measured the velocity distribution of pipeline based on electrostatic method, and compared with synchronous pressure loss signal. According to these signal, analyzed the flow state of the gas-solid two-phase flow.4. Analyzed the flow state of pipeline based on randomness of electrostatic signal. Because of the advantages of electrostatic method in the measurement of solid particles velocity and sensitive area of electrostatic electrodes which are setup at different position are different, took speed compensation for standard deviation of electrostatic signal, proved that this method can reflect the change of flow state and the concentration distributions of the solid material in different area of pipeline.5. Introduced the R/S analysis method, represented the complexity degree of particle phase movement by Hurst index of electrostatic signal. Through experiments of belt electrostatic induction apparatus, establish the relationship between Hurst index of electrostatic signal and the complexity degree of particle phase movement. Through the experiments of gas-solid two-phase flow experimental device in Tianjin University, a conclusion is reached that Hurst index of electrostatic signal can reflect the flow state of the gas-solid two-phase flow.