Effect of acoustic field on minimum fluidization velocity and drying characteristics of lignite in a fluidized bed

Chen, Si; Wu, Jianjun; Wang, Yong; Zhang, Yixin; Liu, Guangjun

doi:10.1016/j.fuproc.2014.11.031

Cited by 19 publications

(7 citation statements)

References 18 publications

(19 reference statements)

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“…This technique greatly improves the fluidization hydrodynamics of ultrafine powders [26,27,[35][36][37][38]. Similarly, the use of acoustic vibrations has also been reported in the literature [28][29][30][39][40][41]. These vibrations promote deagglomeration and eliminate bed nonhomogeneities, thus improving the gas-liquid phase contact.…”

Section: Introductionmentioning

confidence: 81%

Enhancement of CO2 Removal Efficacy of Fluidized Bed Using Particle Mixing

2018

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The present study proposes a cost-effective assisted fluidization technique of particle mixing to improve the carbon capture effectiveness of a fluidized bed containing fine adsorbent powder. Using activated carbon as the adsorbent, we mixed external particle of Geldart group B classification in different fractions to examine the effectiveness of the proposed strategy of particle mixing. Four different particle-mixing cases were considered by varying the amount of added particle—0, 5, 10, and 30 wt %—on external particle-free basis. The inlet flow of the nitrogen was fixed, while two different flows of carbon dioxide were used. The adsorption experiment consisted of a three step procedure comprising purging using pure nitrogen, followed by adsorption with fixed inlet CO2 concentration, and finally the desorption step. Inlet flows of both nitrogen and CO2 were separately controlled using electronic mass flow controllers with the help of data acquisition system (DAQ). The CO2 breakthrough was carefully monitored using the CO2/O2 analyzer, whose analog output was recorded using the DAQ. Best results were obtained with 10% external particles. This is in conformity with the results of our previous study of bed hydrodynamics, which pointed to clear improvement in the fluidization behavior with particle mixing.

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Section: Introductionmentioning

confidence: 81%

Enhancement of CO2 Removal Efficacy of Fluidized Bed Using Particle Mixing

2018

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“…Among the assisted fluidization technique is the pulsation of the inlet flow to the fluidized bed, which has been shown to improve the fluidization hydrodynamics of ultrafine powders [18][19][20][21]. Another extensively employed technique is the introduction of acoustic vibrations during fluidization [22][23][24]. This technique helps to lower the minimum fluidization velocity and eliminate non-homogeneities in a bed of ultrafine powder [22].…”

Section: Introductionmentioning

confidence: 99%

“…This technique helps to lower the minimum fluidization velocity and eliminate non-homogeneities in a bed of ultrafine powder [22]. Si et al [24] used this technique for drying lignite by varying the sound pressure level and frequency and reported the fluidization quality. The rate of drying and drying completion time improved at high sound pressure levels.…”

Section: Introductionmentioning

confidence: 99%

Improving Fluidization Hydrodynamics of Group C Particles by Mixing with Group B Particles

2018

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We have developed a new particle-mixing strategy for improving the fluidization hydrodynamics of Geldart group C powders by mixing with small proportions of group B particles. Two different group C particles with widely different physical properties, i.e., 1 μm calcium hydroxide powder and 27 μm porous activated carbon, were selected for investigation in the present work. A carefully sieved sample of inert sand was used as external group B particles for mixing. Fluidization experiments were carried out, and the quality of the fluidization was assessed using the fluidization index. For the monocomponent fluidization of fine calcium hydroxide powder, pressure drop was sometimes as much as 250% higher than the effective weight of the bed. The proposed strategy of particle mixing substantially improved its fluidization hydrodynamics. On the other hand, the development of channels and cracks during the monocomponent fluidization of the activated carbon led to gas bypassing, resulting in low pressure drop and poor contact of phases. Particle mixing was found to improve fluidization behavior, and the chi-squared test showed that the best results were obtained with 13 wt% particle mixing.

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“…When possible, fluid viscosity and density could be modified to alter the flow regime by adequate selection of the gas [26], temperature and pressure [27,28], and even working under supercritical conditions, common in the pharmaceutical [29,30] and energy sectors [31,32]. There are also many ways to supply an additional source of energy in so-called "assisted fluidization" technologies, for example with direct solar irradiation [33,34], using microwaves in fast biomass pyrolysis [35], or introducing radio frequency [36,37] and ultrasound [38,39] in the design of fluidized bed dryers.…”

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confidence: 99%