电容式气固两相流浓度测量系统

Capacitance-based system for solid concentration measurement in gas/solid two-phase flow

本文介绍一种电容式气固两相流浓度测量系统,给出了具体的测量电极和测量电路。并采用所设计的电容式浓度测量系统在自行搭建的气力输粉系统上以面粉为媒质、在水平管道上对稀相气固两相流浓度进行了在线测量,获得了5×10-5%体积百分比的面粉浓度分辨率。应用该系统对锅炉气力输粉管道中的气固两相流浓度进行实时在线检测与控制,对确保燃烧过程稳定,节能降耗和减少污染排放具有重大意义。

A capacitance based system for the concentration measurement of gas-solid flow used in pneumatically conveyed pulverized fuel in power stations is described. The capacitance sensor for solid concentration measurement uses spiral electrodes. An active sensor and a dummy sensor are used to form differential configuration. An AC- based interface circuit adopting correlated double sample （CDS） technique is used to ensure the measurement accuracy under very low solid air ratio. A laboratory scale pneumatic conveying test facility circulating pulverized fuel was fabricated for the evaluation of the measurement system. The test section is a quartz glass tube of 40 mm diameter on a horizontal pipeline. Flour is used as the solid phase. Results demonstrate that the system reaches the resolution of 5 × 10^-5% in volumetric fraction.