Solid Concentration Measurement in Horizontal Gas–Solid Flows: An Adaptive Model Matching Strategy Using Array Capacitive Sensor

The accurate measurement of solid concentration in horizontal gas–solid flows is very important to guarantee production efficiency and process control. However, gravity causes uneven particle distribution, which creates a strong nonlinear relationship between sensor signals and solid concentration. When particle distribution changes, a single linear measurement model cannot provide enough detection accuracy. This paper proposes an adaptive model matching strategy for solid concentration measurement in horizontal gas–solid flows by using array capacitive sensor. The array capacitive sensor works with two excitation modes. The concave-ring excitation mode collects particle distribution information, and the multi-electrode excitation mode obtains solid concentration. These two types of signals build a dynamic matching relationship between particle distribution features and measurement models. In detail, signals from concave-ring excitation are input into the BP-Adaboost algorithm to classify particle distribution states. Multiple linear measurement models between multi-electrode signals and solid concentration are built through K-means clustering. After recognizing the particle distribution type, the Euclidean distance is used to automatically select the corresponding measurement model. A 3D simulation model combining gas–solid two-phase flow and electrostatic field is set up to test the feasibility of the proposed measurement method. Laboratory experiments are also conducted to prove its reliability. The test results show that the method can adapt well to various particle distribution states. Within the solid concentration range of 0.34–14.08%, the average relative measurement error is 4.41%. This method effectively improves the measurement accuracy of solid concentration in horizontal gas–solid two-phase flow.