Numerical simulation research on the ash pollution measurement sensor based on coplanar capacitance principle

摘要

According to the requirement of online monitoring of fouling and slagging in waste heat boiler of coal gasifier, a method based on coplanar capacitance principle for measuring the pollution thickness is proposed. A capacitance sensor constituting with a circular positive electrode and an annular negative electrode is designed in current study. The sucrose is selected as the deposition medium to substitute the gasification slag. The capacitance and space electric field of sensor are simulated by employing the ANSYS Maxwell. The effects of structural parameters and shielding layers on the capacitance and measurement sensitivity of sensor are analyzed. The results show that with the medium thickness increasing, the capacitance firstly increases then stabilizes and the sensitivity sharply decreases. The sensor with the larger positive radius or the smaller negative radius behaves better sensor performance. The inter electrode and edge shielding has little effect on the capacitance, however, the bottom shielding may improve clearly the capacitance signal strength.