Research On The Properties And Structure Of The Electrostatic Sensor For Mearsuring The Pulverized Coal's Flowing Parameters

With the pneumatic conveying of the hot primary air, the pulverized coal is sent into the boiler furnace through the pipeline at a certain concentration and speed. Online measurement of these main flowing parameters could control the boiler combustion process better, and then ensure the safe operation of the boiler, improve the combustion efficiency of the pulverized coal, reduce the emission of Nox. However, the conveying process of the pulverized coal belongs to gas-solid two-phase flow and it's very difficult to measure the concentration and speed for the complexity and randomicity of the conveying process.The electrostatic sensor has lots of advantages, such as high sensitivity, the simple design of the structure, suitable for harsh industrial environments and mounted on the large pipeline easily. Therefore, it has a very broad application prospect in measuring the pulverized coal's concentration and speed. However, it still has some defects, such as the uneven distribution of sensitivity, and the effect of the weighted filtering. Based on the research on the sensing properties of the internal electrostatic sensor, this paper has selected proper parameters to design the electrostatic sensor. The specific contents are shown as follows:(1) By using the finite element software Comsol, the paper has built the dimensional finite element model of two internal electrostatic sensors(the ring and array type),simulated the electrostatic field, computed the sensitivity of the sensor. And then analysis of the influence of the two sensors' structure size and the material characteristics to the sensitivity.(2) This paper has carried out relevant research on the spatial filtering of the electrostatic sensor, and deduced its frequency characteristics. And then analysis of the influence of the two sensors' structure size and the material characteristics to its frequency response capability and bandwidth. It's aimed at optimizing the electrostatic sensor's performance from the frequency characteristics.(3) After the above analysis, for the actual conditions of the conveying pipeline, this paper has choosen some appropriate model parameters to design the electrostatic sensor,including the structural design of the sensor, the design of the devices for exporting the flow information and the design of the sensor installation process. At last, use thesoftware Solidworks to model and assemble the electrostatic sensor. After some testing,there is no interference in the process of sensor's assembly and installation.