Mathematical modeling and experimental evaluation of electrostatic sensor arrays for the flow measurement of fine particles in a square-shaped pipe

Square-shaped pneumatic conveying pipes are used in some industrial processes, such as fuel injection systems in coal-fired power plants and circulating fluidized beds. However, a little research has been conducted to characterize the gas-solid two-phase flow in a square-shaped pneumatic conveying pipe. This paper presents mathematical modeling and experimental assessment of novel non-restrictive electrostatic sensor arrays for the measurement of pulverized fuel flow in a square-shaped pipe. The sensor arrays consist of twelve pairs of strip-shaped electrodes, which are uniformly embedded in the four flat pipe walls. An analytical mathematical model of the sensor arrays is established, and the induced charge and currents of different electrodes due to a point charge are then derived based on the model. Experimental tests were conducted on a 54-mm square-shaped pipe section of a pneumatic conveyor test rig under a range of flow conditions. The fuel velocity profile over the whole cross section of the pipe is measured. Mathematical modeling and experimental results demonstrate that the proposed non-restrictive electrostatic sensor arrays are capable of characterizing the local pulverized fuel flow in a square-shaped pneumatic conveying pipe.