On-line Sizing of Pneumatically Conveyed Particles Through Acoustic Emission Detection and Signal Analysis

Abstract

Accurate measurement of the particle size distribution of pneumatically conveyed pulverized fuel is critical to achieving optimal combustion efficiency and minimum pollutant emissions at coal and biomass-fired power plants. This paper presents a prototype instrumentation system for the on-line continuous measurement of particle size distribution through acoustic emission (AE) detection. The proposed method extracts particle size information from the impulsive AE signals arising from impacts of particles with a metallic waveguide protruding into the flow. The relationship between the particle size and the peak AE voltage is established through mathematical modeling of the particle impact process. Identification of the peak AE voltage is achieved with an energy-based peak detection algorithm. Experimental results obtained with glass beads demonstrate the capability of the system to discriminate particles of different sizes from the recorded AE signals. The system performs better in terms of accuracy for higher speed, lower concentration particles as the impact signals are stronger and better separated in the time domain.Index Terms-Acoustic emission (AE), Hertz theory of contact, particle size, particle size distribution, particle size measurement, particle sizing, peak detection.

Optical Detection of Impact Contact Times with a Beam Deflection Probe

“…Accurate measurements of the contact time are not only important in the basic studies of contact mechanisms in order to assess the validity of the proposed theory [2], [3], they are also important in a wide range of different applications related to, for example, contact mechanics, tribology, shot peening, wear, erosion, rock falls, military ballistics, measurements of hardness at high strain rates and granular matter research. Due to its linear dependence on the radius, the contact time of spherical particles impacting thick plates is, for instance, a good criterion for their size [4], [5], [6], [7], [8] whereas particle sizing is an important requirement in many areas of industrial processing and manufacture [8]. If the velocity of the particle is known with some uncertainty, the size of the particle can be determined via its impact with another solid more accurately by measuring the contact time than the maximum force [5], [6], [8], because the contact time has a more gentle dependence on the approach velocity as opposed to the maximum force.…”

“…Due to its linear dependence on the radius, the contact time of spherical particles impacting thick plates is, for instance, a good criterion for their size [4], [5], [6], [7], [8] whereas particle sizing is an important requirement in many areas of industrial processing and manufacture [8]. If the velocity of the particle is known with some uncertainty, the size of the particle can be determined via its impact with another solid more accurately by measuring the contact time than the maximum force [5], [6], [8], because the contact time has a more gentle dependence on the approach velocity as opposed to the maximum force. A sphere drop on a stationary plate or a block is also often used as a standard acoustic source of ultrasonic waves.…”

Pharmaceutical Application of Process Understanding and Optimization Techniques: A Review on the Continuous Twin-Screw Wet Granulation

“…The previous research has demonstrated that AE, a non-destructive ultrasonic technique, is a reliable predictor of Gaussian PSD [64][65][66][67]. The maximum amplitude of the time-domain AE signal, generated by the collision of a moving particle with a rigid surface, is correlated with particle size to estimate a single descriptor, typically d 50 .…”

An acoustic emission activity detection method based on short-term waveform features: Application to metallic components under uniaxial tensile test

“…A last matter to considering is that owing to the high data rates required to process the AE phenomenon, these advanced methods are computationally expensive, so usually they are implemented under an offline framework (first capturing the data from the survey, to later separating the AE events). Although some efforts has been made in order to implement hardware architectures that can operate under an online approach [18][19][20], strategies that can lead to faster and efficient implementations (this particularly necessary for long surveys), are desirable.…”