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Indexed by:期刊论文

Date of Publication:2013-07-01

Journal:ENERGIES

Included Journals:SCIE、EI、Scopus

Volume:6

Issue:7

Page Number:3245-3262

ISSN No.:1996-1073

Key Words:ash deposition; rebound characteristics; impaction experiments; normal restitution coefficient

Abstract:This paper presents the results of a comprehensive program of experiments in which fly ash particles were impacted under controlled conditions against a flat steel surface. The overall aim of these experiments was to gain an understanding of the ash deposition process in a pulverized coal boiler system. A continuous nitrogen flow carrying fly ash particles was used to examine the effect of particle incident velocity and particle diameter (d(p)) on the normal restitution coefficient, and of the particle diameter on the critical velocity. The effect of the incident normal velocity and particle diameter on the normal restitution coefficient was also examined. The results show that the normal restitution coefficient increases rapidly with increasing incident velocity when this incident velocity is less than the yield velocity, and rapidly decreases with increasing incident velocity when the incident velocity is greater than the yield velocity. The critical velocity, determined solely by the first-contact energy loss, is proportional to d(p)(-5/6) and therefore becomes larger for smaller particles. For instance, in the present work, the velocity nu(c) of a particle with diameter of 85 mu m is 0.19 m/s, which increases to 0.42 m/s for particles with a diameter of 65 mu m.