Abstract
In this paper, the rebound characteristics of coal ash particles impacting on a stainless steel surface are studied experimentally with the background of ash deposition on the heating surface of the boiler. The impact processes of coal ash particles with different incident angles were recorded by high-speed digital camera technology. The evolution of the normal restitution coefficient with incident normal velocity was obtained. Three different static contact theories are used to establish the equations of motion to predict the critical capture velocity of particles. The results show that the normal restitution coefficient first increases and then decreases with the increase of incident normal velocity. The critical capture velocity of particles under the three models was predicted. It is found that the prediction results of the Brach and Dunn (BD) model for the critical capture velocity are close to the experimental results. Taking the particle of size 23 μm as an example, the maximum critical capture velocity predicted by BD model is 1.0611 m/s at 0° incident angle. The minimum value is 0.7940 m/s when the incident angle is 45°.The critical capture velocity of particles decreases with the increase of incident angle and with the increase of particle diameter.
Highlights
0.7940 m/s when the incident angle is 45◦ .The critical capture velocity of particles decreases with the increase of incident angle and with the increase of particle diameter
In the field of energy and environment, various particle diameters of fly ash will be produced in the process of coal-fired power generation, which is easy to deposit on the heating surface, resulting in slagging, ash deposition, corrosion, and other problems leading to the reduction of boiler efficiency and the decrease of the lifespan of the heat exchange tube
The impact process of coal ash particles with the stainless steel surface at different incident filmed by high-speed digital technology, and the
Summary
An experimental device for coal ash particles impacting the stainless steel surface was developed. The collision process coal ash particles and The the stainless steel surface was in thein computer subsequent data analysis. In this experiment, the coal ash particle mesh number is less than mesh, machine. Figure coal ure 3 shows the of whole process of coal ash particles bouncing back after the incident from the direction perpendicular to the stainless steel surface and impacting the target surface. Duringdata dataprocessing, processing,coal coalash ashparticles particlesimpacting impactingon onthe thestainless stainlesssteel steelsurface surfaceininaa direction perpendicular to the horizontal plane were manually selected. Using measure incident velocity asas an an example, the position of pixels of coal ash particles on three images is measured by example, the position of pixels of coal ash particles on three images is measured by Adobe
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