Microwave Sensing System for Real-Time Monitoring of Solid Contaminants in Gas Flows

The presence of undesired solid contaminants, such as black powder (BP), in natural gas flows diminishes the integrity of the pipeline network. The success of any efficient integrity management program applied to the affected pipeline requires real-time monitoring of the amount of BP traversing the given pipeline and its distribution in the network. In this paper, a new microwave-based system for real-time BP monitoring is introduced and its performance is thoroughly analyzed. The proposed system utilizes custom-designed hermetically sealed probe to interrogate the flow mixture with low-power microwaves in the industrial, scientific, and medical frequency band and monitors the signals reflected from the flow and transmitted through it. Based on extensive simulation and measurement results, it will be shown that the presence of the BP, even in small quantities within the flow, is manifested with considerable variations in the microwave transmission and reflection properties of the flow rendering high overall sensor detection sensitivity and specificity. Experimentally, it will be shown that the developed system can detect flowing BP as well as other contaminants, such as sand, in subgram quantities within 101 mm-ID pipe while utilizing simple detection scheme.