Chan, Chian W., Seville, J. P. K. (Jonathan P. K.), Fan, Xianfeng and Baeyens, Jan. (2009) Solid particle motion in a standpipe as observed by Positron Emission Particle Tracking. Powder Technology, Vol.194 (No.1-2). pp. 58-66. ISSN 0032-5910

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Abstract

Standpipes are commonly used in circulating fluidised beds (CFB) to gravitationally transport solids from a region of lower pressure at the apex of the cyclone to the higher pressure region of the riser, Positron Emission Particle Tracking (PEPT) is applied to observe and study the real-time particle motion in standpipes of 2.5 cm and 4.5 cm ID respectively. Experiments use a hopper connected to the top of the standpipe while the base is connected to a free-discharging L-valve. PEPT results confirm that the solids velocity profile is asymmetrical along the vertical axis of the standpipe at any given height, The average voidage of the standpipe, epsilon(a) and solids flow rate, Q(s) are dependent upon the discharge rate of the L-valve, expressed by its fractional opening, f. An empirical equation to predict epsilon(a) has been derived: epsilon(a)/D-0.4 = 2.25 (C-d/C-ds)(-0.2). The drag force on an individual solid particle can then be calculated and determines the actual motion of solids. Upward solids motion will be detected when the drag force exceeds the particle weight, whereas the motion will be downward with some degree of particle acceleration if the particle weight exceeds the drag force. The use of the design equations is finally illustrated in assessing the operation of standpipes of different diameter. (C) 2009 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Subjects:	T Technology > TD Environmental technology. Sanitary engineering T Technology > TP Chemical technology
Divisions:	Faculty of Science > Engineering
Library of Congress Subject Headings (LCSH):	Standpipes, Positrons -- Emissions, Fluidization, Chemistry, Technical, Chemical engineering
Journal or Publication Title:	Powder Technology
Publisher:	Elsevier Science SA
ISSN:	0032-5910
Official Date:	25 August 2009
Volume:	Vol.194
Number:	No.1-2
Number of Pages:	9
Page Range:	pp. 58-66
Identification Number:	10.1016/j.powtec.2009.03.032
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
URI:	http://wrap.warwick.ac.uk/id/eprint/27676

Data sourced from Thomson Reuters' Web of Knowledge

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