Performance and energy efficiency of two types of dryers for fish feed are compared. The first dryer was a belt dryer located at a fish feed production facility in Norway. The second dryer was a ...counterflow multideck dryer at a fish feed production facility in Chile. In both dryers there was only a slight decrease in drying rate over the dryer. Product samples showed a standard deviation of 0.45% on an average moisture content of 10.2% (wb) for the belt dryer and 0.49% on an average of 8.6% (wb) for the counterflow dryer. Mass and heat balances showed good accuracy. In order to compare the energy use of both dryers, normalized energy consumption and efficiency were calculated for equal feed and air inlet temperatures using two methods: the primary energy method and the energy difference method. The average normalized specific energy consumption for the belt dryer was 3,386 kJ/kg water evaporation (primary energy method) and 2,970 kJ/kg (energy difference method), with efficiencies of 56 and 64%, respectively. For the counterflow dryer the average specific energy consumption was 2,893 kJ/kg (primary energy method) and 2,393 kJ/kg (energy difference method), with efficiencies of 70 and 85%, respectively.
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Forage grass seeds have a high economical importance in the Brazilian bovine cattle breeding and seed drying is a fundamental stage of processing to guarantee their stability and allow their storage ...for long periods. In this context, the objective of this work was to develop a pilot-scale belt dryer, which operates also as a fixed and fluidized bed. Brachiaria brizantha seeds dehydration was analyzed under different air velocities and temperatures. Experimental data of moisture content variation along the drying time was successfully fit to a one-term exponential model. The experimental drying rate points were calculated by approximating the derivatives to finite differences. Its behavior was accomplished fitting curves of the drying rate versus water content and time. Finally, fissure, germination, and vigor rates were analyzed as a function of the drying conditions so that the experimental conditions combine the best process efficiency with the best physiological quality maintenance.
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A conveyor-belt dryer for picrite has been modeled mathematically in this work. The necessary parameters for the system of equations were obtained from regression analysis of thin-layer drying data. ...The convective drying experiments were carried out at temperatures of 40, 60, 80, and 100°C and air velocities of 0.5 and 1.5 m/sec. To analyze the drying behavior, the drying curves were fitted to different semi-theoretical drying kinetics models such as those of Lewis, Page, Henderson and Pabis, Wang and Singh, and the decay models. The decay function (for second order reactions) gives better results and describes the thin layer drying curves quite well. The effective diffusivity was also determined from the integrated Fick's second law equation and correlated with temperature using an Arrhenius-type model. External heat and mass transfer coefficients were refitted to the empirical correlation using dimensionless numbers (J
h
, J
D
= m · Re
n
) and their new coefficients were optimized as a function of temperature. The internal mass transfer coefficient was also correlated as a function of moisture content, air temperature, and velocity.
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24.
Drying Hipple, Jack
Chemical Engineering for Non-Chemical Engineers,
2017, 2017-01-20
Book Chapter
At the start of a drying process, there is usually substantial moisture on the surface of the solid. In general, the rate of drying will be proportional to the temperature differential between the ...drying heat source and the temperature of the material being dried as well as the area of the material being exposed to the drying medium and inversely proportional to the heat of vaporization. The contact area can be increased by agitation, tumbling within batch dryers, and baffling inside rotating equipment. There are a number of commercial type dryers, such as rotary dryers, belt dryer, and freeze dyers. Rotary dryers can be either continuous or batch and can be direct heat fired or the water/solvent evaporated with the assistance of vacuum. Batch processing would be typically used in specialty and pharmaceutical applications where lot control is important.
Design of an integrated dryer and conveyor belt for woody biofuels Alamia, Alberto; Henrik StrmauthorDivision of Energy Technology, SwedenDivision of Fluid Dynamics, Chalmers University of Technology, Sweden; Henrik ThunmanauthorDivision of Energy Technology, Sweden
2015
Journal Article
The design is bio-fuel raw material drying equipment which is cross-flow belt dryer based on high-temperature hot water as the medium. According to the drying experiments, obtained the drying curve ...of materials at different temperatures. Through the experimental data, the general parameters of dryer were determined. The features of this design is that heat from the high-temperature hot which comes from biomass boiler system; through the heater to heat the air; cross-flow drying; low energy consumption; high efficiency, and a continuous cycle of drying.
Simulation of plum drying in deep bed Techasena, O. (Institut National de la Recherche Agronomique, Massy, France); Lebert, A.M; Bimbenet, J.J
Drying technology,
01/1991, Volume:
9, Issue:
4
Journal Article
Peer reviewed
Thin layer air drying of plum was studied. The drying conditions in this study are : dry bulb temperature ranging from 60 to 100 °C, air moisture content ranging from 0.008 to 0.089 kg water/kg dry ...air and air velocity ranging from 0.5 to 2 1x11s. An exponential model was used to describe the drying curve. The heat and moisture balances on the air were used to calculate the outlet air temperature and its moisture content. The heat balance on the product was used to calculate the product temperature. These equations were used to predict the drying of plum in deep bed. A good agreement between the experimental and calculated product moisture content, the product temperature and the outlet air temperature were obtained
Drying of sugar beet fiber with hot air or superheated steam Bernardo, A.M.M. (Ecole Nationale des Industries Agro-Alimentaires, Massy, France); Dumoulin, E.D; Lebert, A.M ...
Drying technology,
(1990), 1/1/1990, 1990-01-00, 1990, Volume:
8, Issue:
4
Journal Article
Peer reviewed
A comparative study of drying thin layers of sugar beet fiber with hot air or with superheated steam in a specially designed pilot dryer is reported. Our present interests are focused on drying rate ...and on the quality of the dried product. Steam superheated at 130-150°C yields 90 % of dry matter (DM), however steam condensation on the cold product at the beginning of the process may penalize the drying time. The color of the fiber is not modified until reaching 80 % DM. Drying with air heated at temperatures lying in the 40 to 105°C range does not alter the white color up to 90 % DM. The water retention capacity of the original fiber, 14 g water/g DM remains unchanged whatever drying agent is used. The scaling up of the primary hot air drying set up to a ten times larger experimental dryer introduce no modification of drying time, water retention capacity or fiber color. Thick layer drying experiments permit to define parameters of a belt dryer for an industrial fiber processing plant.
A mathematical model of the heat and mass transfer and the phase transformations in colloidal capillary-porous materials and a numerical method for calculating the dynamics of these processes in the ...indicated materials and the shrinkage of them in their drying in a continuous-belt drier have been developed for the purpose of optimization of the drying process. An energy-efficient, resource-conserving convective-condensation method of drying thermolabile materials, which makes it possible to decrease the drying time, is presented.
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