Results of tests on a dryer with a vibrated fluidized bed

Osinskii, V. P.; Сажин, Б. С.; Chuvpilo, E. A.

doi:10.1007/bf01371762

Cited by 4 publications

(3 citation statements)

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“…This is perhaps the reson for different researchers reporting widely varying acceleration optima. Several researchers [15][16][17][18] reported increase in drying rate due to vibrations. Marella et al, [9] used vibrofluidizations in order to increase the heat transfer coefficients in drying of dairy and agricultural foods grains.…”

Section: Journal Of Foodmentioning

confidence: 99%

Processing Aids for Improving Heat Transfer during Drying of Granular Food Materials

Marella¹,

Muthukumarappan²

2013

J Food Process Technol

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The comparative low price of energy in the past discouraged any emphasis on energy conservation in drying of food products. But under the circumstances of ever increasing energy prices, it is the need of the hour to look for improved energy utilization. In dairy and food industry a large number of products are dried. Previously this operation was carried out in a single stage, necessitating the dryer to operate at higher air out let temperatures. To improve this, dryers were developed with two and three stages. Additional stages brought about significant savings in the energy requirements. Fluidized beds have been included as second and third stage dryer in conventional dryers. Inclusion of vibrations, centrifugal beds, immersion heaters etc have been tried to improve the heat transfer characteristics of the air-material drying situations. In the present work, various processing aids that improve the heat transfer in drying of granular material are reviewed. In addition, data from drying of acid casein, wheat and shelled corn were also resented.

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Section: Journal Of Foodmentioning

confidence: 99%

Processing Aids for Improving Heat Transfer during Drying of Granular Food Materials

Marella¹,

Muthukumarappan²

2013

J Food Process Technol

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“…Compared with a conventional fluidized bed dryer, the microwave-assisted fluidized bed dryer can create temperature uniformity, hence enhancing the drying rate. 15 Another additional field assisted fluidized bed dryer, such as a vibration-assisted fluidized bed dryer, 18,19 an agitationassisted fluidized bed dryer, 20 and an acoustic-field assisted fluidized bed dryer, have been widely studied and reported to have a significant effect on improving the drying efficiency. Likewise, separation and upgrading of lignite with a fluidized bed has become a research hotspot in recent years.…”

Section: Introductionmentioning

confidence: 99%

Separation and Upgrading of Fine Lignite in Pulsed Fluidized Bed. 1. Experimental Study on Lignite Drying Characteristics and Kinetics

et al. 2017

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The pulsating flow was introduced into the gas–solid fluidized bed to enhance the diffusion and stratification of lignite particles and avoid channeling and short circuits with an attempt to achieve a better drying effect for fine lignite. A pulsed fluidized bed system was established, targeting the analysis of the drying and segregation characteristics of fine lignite. With the thermal input characterized by inlet temperature, thermal energy was transported into the fluidized bed and lignite particles, which accelerates the evaporation of surface water and interior water of lignite particles. Under the combination effect of thermal and pulsating energy, the drying efficiency was significantly improved. This paper mainly focuses on the influence of various operating factors on the drying characteristics of fine lignite in a pulsed fluidized bed and exploring the appropriate kinetic model for the drying process under different inlet temperatures in a pulsed fluidized bed. In the drying process, the drying rate was influenced dramatically in a positive way by the inlet temperature, gas velocity, and pulsating frequency, while the drying rate decreases with the increase of bed height. The increase of inlet temperature, gas velocity, and pulsation frequency reduced the moisture content and increased the drying rate. When the inlet temperature, air velocity, pulsating frequency, and bed height, which are 100 °C, 1.09 m/s, 3.06 Hz, and 120 mm, the water content of −6 + 3 mm lignite decreases dramatically from 31.66% to approximately under 8% after 12 min of drying. The water content of −3 + 1 mm lignite plummets from 29.99% to around 4% after 12 min of drying when inlet temperature, air velocity, pulsating frequency, and bed height are set as 100 °C, 0.61 m/s, 2.62 Hz, and 80 mm, respectively. An infinitesimal effect on the lignite drying can be detected when the gas velocity and the pulse frequency exceed a certain range. In the study of drying kinetics, fitting results under different temperatures combined with a thin layer drying model showed that the logarithmic model was the optimal model for interpreting the drying characteristic of fine lignite. After drying and separation, the calorific capacities of −6 + 3 mm lignite and −3 + 1 mm lignite increase by up to 60% and 67%, respectively. Hence, drying of fine lignite with a pulsed fluidized bed offers a feasible and economical method to enable further industrial application of lignite.

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“…Compared with a conventional fluidized bed dryer, the microwave-assisted fluidized bed dryer can penetrate the materials and create temperature uniformity, hence enhancing the drying rate. 15 Other additional field assisted fluidized bed dryers, such as vibration-assisted fluidized bed dryer, 18,19 agitation-assisted fluidized bed dryer, 20 and acoustic-field assisted fluidized bed dryer have been widely studied and reported to have a significant effect on improving the drying efficiency. Likewise, separation and upgrading of lignite with fluidized bed has become a research hotspot in recent years.…”

Section: Introductionmentioning

confidence: 99%

Separation and Upgrading of Fine Lignite in a Pulsed Fluidized Bed. 2. Experimental Study on Lignite Separation Characteristics and Improvement of Separation Efficiency

et al. 2017

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A pulsed fluidized bed system was established, targeting the analysis of the drying and separation characteristics of fine lignite. Experiments, involving factors of air velocity, pulsating frequency, and bed height were conducted under room temperature to analyze the influence of each factor on the separation characteristics of −6 + 3 mm lignite and −3 + 1 mm lignite in a pulsed fluidized bed, respectively. The combustible recovery and standard deviation of ash content were implemented to evaluate the separation efficiency. Results show three factors have a significant impact on the separation efficiency of fine lignite. Afterward, the thermal energy characterized by inlet temperature was imported into the pulsed fluidized bed system to study the influence of inlet temperature, air velocity, pulsating frequency, and bed height on the separation efficiency of fine lignite under thermal conditions. Results show that the ash content of the top layer product decreases significantly from 14.44% to 9.82% and from 15.52% to 7.31% when the pulsating frequency increases from 0 Hz to 3.93 Hz under room temperature and thermal conditions for −6 + 3 mm lignite, respectively. For −3 + 1 mm lignite, the ash content of the top layer product decreases from 17.22% to 10.25% and from 16.77% to 10.01% under room temperature and thermal conditions, respectively. Optimal operation parameters were determined. With the air velocity of 1.09 m/s, inlet temperature of 80 °C, pulsating frequency of 3.93 Hz, and bed height of 120 mm, the optimal separation efficiency was achieved for −6 + 3 mm lignite. For −3 + 1 mm lignite, the optimal is achieved when air velocity, inlet temperature, pulsating frequency, and bed height are 0.55 m/s, 100 °C, 3.49 Hz, and 80 mm. The separation efficiency of lignite with a pulsed fluidized bed was dramatically improved.

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Results of tests on a dryer with a vibrated fluidized bed

Cited by 4 publications

References 0 publications

Processing Aids for Improving Heat Transfer during Drying of Granular Food Materials

Processing Aids for Improving Heat Transfer during Drying of Granular Food Materials

Separation and Upgrading of Fine Lignite in Pulsed Fluidized Bed. 1. Experimental Study on Lignite Drying Characteristics and Kinetics

Separation and Upgrading of Fine Lignite in a Pulsed Fluidized Bed. 2. Experimental Study on Lignite Separation Characteristics and Improvement of Separation Efficiency

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