Yang Yiguang, Zhang Lianyong, Wang Chenlong, Chen Lijun, Xu Hao, Song Shihao
School of Automation Engineering, Northeast Electric Power University, Jilin 132011, China.
Guoneng Hebei Dingzhou Power Generation Company Limited, Hebei 073099, China.
Sensors (Basel). 2025 Jun 11;25(12):3657. doi: 10.3390/s25123657.
Pulverized coal mass concentration in the primary air pipe is one of the essential parameters for promoting furnace combustion efficiency. However, attaining accurate, real-time, and online detection for pulverized coal mass concentration remains challenging due to factors such as large pipe diameter and high flow rate. This study introduces a quasi-open microwave resonant cavity sensor. The principle and model were analyzed using the perturbation method, and the design and optimization were conducted with the simulation. A prototype and its test system were constructed, and the test results demonstrated good agreement between the simulations and experiments. The simulation revealed that the resonant frequency decreased monotonically from 861 to 644 MHz as mass concentration increased within 20%~80%, resulting in a change of about 3.62 MHz/1% under static mixture. The resonant frequency showed a drop from 21 MHz to 9 MHz with an increase in mass concentration under pulverized coal flow. Prediction models were developed and validated, showing the absolute values of the relative errors to be within 4% under operational scenarios. Additionally, the impact of the sensor on pulverized coal flow was evaluated, and it was found that the sensor structure had minimal impact on the flow in terms of velocity and the distribution of continuous flow. Finally, the long-term stability was assessed by examining the wear of the antennas and barriers. With inner barriers experiencing up to 2/3 wear, the resonant frequency drift ratio remained below 1.5%, corresponding to a mass concentration deviation of less than 3.2%.
一次风管内的煤粉质量浓度是提高炉膛燃烧效率的关键参数之一。然而，由于管径大、流速高等因素，实现对煤粉质量浓度的准确、实时和在线检测仍具有挑战性。本研究介绍了一种准开放式微波谐振腔传感器。采用微扰法对其原理和模型进行了分析，并通过仿真进行了设计和优化。构建了一个原型及其测试系统，测试结果表明仿真和实验结果吻合良好。仿真结果表明，在20%~80%的质量浓度范围内，随着质量浓度的增加，谐振频率从861 MHz单调下降至644 MHz，在静态混合情况下，质量浓度每变化1%，谐振频率变化约3.62 MHz。在煤粉流动情况下，随着质量浓度的增加，谐振频率从21 MHz下降至9 MHz。建立并验证了预测模型，结果表明在运行工况下相对误差的绝对值在4%以内。此外，评估了传感器对煤粉流动的影响，发现传感器结构对流速和连续流分布的影响极小。最后，通过检查天线和障碍物的磨损情况评估了长期稳定性。当内部障碍物磨损达2/3时，谐振频率漂移率仍低于1.5%，对应的质量浓度偏差小于3.2%。
