Study of the Ability of an Electromagnetic Flowmeter Based on Step Excitation to Overcome Slurry Noise

Abstract

An electromagnetic flowmeter (EMF) can be used to measure the speed of slurry fluid. In this paper, according to Maxwell's equations and the dB/dt vortex electric field, a step excitation scheme is proposed. The original excitation process of the primary excitation current rise time is divided into a two-step excitation process. Without increasing the excitation current rise time, the equivalent excitation frequency is increased by increasing the primary dB/dt. This method can enhance the EMF's ability to overcome slurry noise. The paper analyzes the design parameters of the step excitation scheme and designs the software and hardware. After that, the paper compares the step excitation scheme with the three-value rectangular wave excitation scheme based on wavelet transform signal processing. Experiments show that the step excitation EMF has a lower steady-state fluctuation rate when measuring mortar and has a stronger ability to overcome slurry noise. Additionally, the step excitation EMF and Yokogawa AXF 040G EMF are compared experimentally. Through flow calibration, clean water measurement, mortar measurement and dynamic response experiment, it is verified that the step excitation EMF has the ability to enhance the resistance to slurry noise at the same excitation frequency.

Keywords

• Electromagnetic flowmeter
• slurry noise
• Maxwell’s equations
• step excitation
• slurry noise overcoming method