A method for agglomeration detection and control in full-scale biomass fired fluidized beds

Nijenhuis, John; Korbee, R.; Lensselink, J.; Kiel, J.H.A.; Ommen, J. Ruud van

doi:10.1016/j.ces.2006.09.041

Cited by 66 publications

(45 citation statements)

References 9 publications

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“…This purge velocity was found to have no significant influence on the pressure signal recorded. Similar findings have been demonstrated by Nijenhuis et al [25]. The probe position in the bed corresponds to 19% of the initial static bed height and 33% of the final static bed height.…”

Section: Componentsupporting

confidence: 78%

The influence of vessel geometry on fluidized bed dryer hydrodynamics

Wormsbecker¹,

Ommen²,

Nijenhuis³

et al. 2009

Powder Technology

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Section: Componentsupporting

confidence: 78%

The influence of vessel geometry on fluidized bed dryer hydrodynamics

Wormsbecker¹,

Ommen²,

Nijenhuis³

et al. 2009

Powder Technology

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“…The pressure signal is measured in a bubbling fluidized bed of Geldart B particles. (Geldart andXie, 1992, van Ommen et al, 2004) and 1.0-2.0 m/s for Geldart B particles (Nijenhuis et al, 2007).…”

Section: Pitfalls In Measuring Pressure Fluctuationsmentioning

confidence: 99%

Measuring the Gas-Solids Distribution in Fluidized Beds -- A Review

Ommen¹,

Mudde²

2008

International Journal of Chemical Reactor Engineering

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In gas-solid fluidized beds, the distribution of the particles typically varies both in time and space. Since the gas-solids distribution and its variation have a strong influence on the performance of a fluidized bed for a given process, it is very important to accurately measure the gas-solids or voidage distribution. This paper reviews techniques for measuring the voidage distribution in gas-solid fluidized beds, with a focus on the developments during the last ten years. We will treat subsequently direct visualisation, tomography, optical probes, capacitance probes, and pressure measurements.Dense gas-solids flows are typically opaque to visible light. This makes optical techniques only of limited use in dense gas-solids flow. However, direct visualization can be useful for very dilute systems, pseudo 2-D beds, and the outer layer of dense, 3-D systems. Tomography is frequently used to obtain the voidage distribution in a horizontal cross-section of the bed. Electric capacitance tomography is fast, but its spatial resolution is limited and image reconstruction is still troublesome. Although some steps forward have been made, research is continuing at this point. For nuclear (X-ray and gamma-ray) tomography, the image reconstruction is much easier and the spatial resolution better, but its temporal resolution is typically much lower. Therefore, research efforts for nuclear tomography are mainly aimed at increasing the measurement frequency. Optical probes determine the voidage as a function of time in a small measurement volume, either by the degree of reflection or by the degree of transmission of a light bundle. Capacitance probes determine the voidage as a function of time in a small measurement volume by measuring the dielectric permittivity of the gas-solids suspension in the measurement volume. Both optical and capacitance probe techniques are reasonably well-developed; the current research effort spent at improving them seems * We would like to thank M.O. Coppens, J. Nijenhuis, R.W.S Bohlken, and M.A. Wormsbecker for useful suggestions during preparation of this manuscript. limited, especially for capacitance probes. Time-averaged pressure measurements are commonly used to determine the average bed density and bed height. By sampling the local pressure at a sufficiently high frequency (typically in the order of 200 Hz), much more information can be obtained about the fluidized bed hydrodynamics. However, obtaining quantitative voidage data from pressure fluctuations measurement remains a difficult task; in-bed pressure fluctuation (and acoustic) measurements are mostly used to determine changes in the voidage dynamics and distribution.

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“…Several intrusive and non-intrusive measurement techniques have been utilized for monitoring the hydrodynamics of fluidized beds. Measurement of pressure fluctuation have been used by many researchers for determining changes in the particle size (Davies and Fenton, 1997;Weinstein et al, 2000), predicting the onset of defluidization (Mettanant et al, 2009), detecting hydrodynamic changes (Ibrehem, 2009;Bartels et al, 2010;Mansourpour et al, 2014) and early detection of agglomeration (Schouten and van den Bleek 1998;van Ommen et al, 2000;Nijenhuis et al, 2007;Gheorghiu et al, 2004). Acoustic emissions have been applied in various fluidized beds to characterize the fluidization state or regime changes (Zukowski 1999;Tsujimoto et al, 2000;Salehi-Nik et al, 2009).…”

Section: Page 3 Of 30mentioning

confidence: 97%