On-line mass flow measurement in flowing two component systems

Abstract

Apparatus and process for measuring mass flow of a slurry mixture of two components of materials, such as a flow of catalyst solid particles (the first component) or droplets in a fluid carrier (the second component). The slurry mixture is added to a process stream (10) or batch reactor. The flow velocity and the volume fraction of one component are measured and combined with the known specific gravity, of the component being measured, and the physical dimensions of the pipe, in which the slurry mixture is flowing, to determine the mass flow of the component. The flow velocity is measured by correlating signals at two separated locations along the flow path, and the volume fraction is measured by combining the known dielectric constants of each of the materials in the mixture and the measured capacitance of the mixture. The capacitance is measured from electrodes which may be isolated from the flowing materials in some applications, but not isolated from the flowing materials in other applications. The temperature (9) and pressure (11) are compensated in the final calculation, and the mass flow result is used to control, via feedback, the amount of such materials delivered. Also, a subtraction technique to remove interfering power line noise is implemented to improve sensitivity.