Flow measurement of pneumatically conveyed biomass and coal particles using multi-channel electrostatic sensors

Key parameters such as particle velocity and concentration of biomass-coal flow in fuel injection pipelines are useful to power plant operators to detect fuel supply problems at an early stage. This paper presents the use of a multi-channel electrostatic sensor with circular and arc-shaped electrodes for the on-line, continuous measurement of "local" and "mean" characteristics of the biomass-coal mixture flow. Experimental tests were conducted on a laboratory-scale particle flow test rig under various flow conditions. The results suggest that, due to physical differences between biomass and coal particles, the characteristics of the flow depend on the biomass proportion in the mixture. It is found that pure coal particles travel faster and carry more electrostatic charge than those of pure biomass particles. As more biomass is added to the coal flow, the overall velocity of the flow slows down, the electrostatic charge level decreases, and the flow becomes less stable compared to the pure coal flow.