关键词: 气固两相流, 微弱电容传感器, 信号滤波, 互相关, 多管道煤粉传输, 数模混合电路

Abstract:

The flow rate of pulverized coal in the pulverized coal injection process of industrial blast furnaces is difficult to monitor, and the problem of uneven input and clogging of boiler pulverized coal is likely to occur. In order to monitor the accurate flow rate in the transportation pipeline in real time, this paper proposed a high-precision coal flow monitoring system based on cross-correlation and capacitance detection. The system mainly contained two parts: weak capacitance detection circuit and capacitance sensor. Two-layer shielded capacitive sensors were designed based on field test results, and a high-precision, low-noise digital-analog hybrid capacitance detection circuit was built. Filtered the interference signal while preserving the characteristic fluctuations required by the cross-correlation algorithm using a filtering algorithm that preserved the cross-correlation feature. Combining the current velocity given by cross-correlation algorithm and concentration converted from capacitance detection system’s output, multi-pipe accurate flow rate could be obtained finally with CAN bus. The experimental results showed that the error in the practical application of the system could be controlled at about 5%, indicating the method had higher accuracy and met the needs of complex engineering environments.

Key words: the gas-solid two-phase flows, weak capacitance sensor, signal filtering, cross correlation, multi-pipe pulverized coal transmission, digital-analog hybrid circuit