Drying of Rubber Wood Sawdust Using Tray Dryer

Abstract

The present study attempts to understand drying characteristics of rubber wood sawdust in a tray dryer as it is the simplest and oldest of the dryers known commercially. An increase in temperature, flow rate of the heating medium, and initial moisture content was found to increase the drying rate. However, an increase in the particle diameter and bed height was found to reduce the drying rate. The increase in drying rate with temperature and moisture content was attributed to increase in the diffusion coefficient, while the increase due to the flow rate is attributed to reduction in the external mass transfer resistance during early stages of drying while the drying rate was high. An increase in bed height as well as particle size increases the diffusion path length for moisture, which contributes to the reduction in drying rate. The experimental data were modeled using Fick's diffusion equation, and the effective diffusivity coefficient was evaluated by minimizing the error between the experimental data and the prediction using the model equation. The effective diffusion coefficient was found to increase with increase in temperature, initial moisture content, and the flow rate of the heating medium, while it was found to decrease with increase in particle size. The diffusion coefficient was not found to vary with the bed height=solid loading. The effective diffusion coefficient was found to vary within 9.1 Â 10 À9 to 22 Â 10 À9 m 2 =min. The standard deviation of error between the experimental data and prediction using the model, using the estimated effective diffusivity coefficient, was found to be less than 0.07 for the entire set of data, indicating the appropriateness of the model in predicting drying kinetics.

Drying Kinetics of Rice Straw under Isothermal and Nonisothermal Conditions: A Comparative Study by Thermogravimetric Analysis

“…According to this figure, it is clear that the Logarithmic model fits the drying curves of rice straw very well. 13 1.52 to 3.67 × 10 −10 m 2 /s for rubber wood sawdust drying at 40−60 °C; 14 1 to 10 × 10 −10 m 2 /s and 1 to 6 × 10 −8 m 2 /s for agriculture residues (rice husk and coconut husk, respectively) drying at 30−70 °C. 15 The activation energy was determined by eq 6.…”

“…8,18 On the other hand, drying studies and methods mainly focus on the massive, cylindrical, and spherical materials, such as wood, potato, rice. 8,11,14,19 However, scarce attention has been paid to powdered biomass. Therefore, a rapid and simple approach for determining the drying kinetics and effective moisture diffusivity of powdered biomass particles is an urgent necessity.…”

“…In recent years, the drying characteristics of biological materials have been extensively studied by numerical simulation methods or empirical mathematical models under isothermal conditions. − However, these existing methods may not be suitable for the determination of the drying kinetics and effective moisture diffusivity of powdered biomass particles. On one hand, achieving isothermal drying conditions is usually difficult and in some cases impossible.…”

Investigation on Convective Drying of Mixtures of Sewage Sludge and Sawdust in a Fixed Bed

“…This material is produced in large amount by the forest industry and also needs safe disposal solutions [18]. Usually, sawdust is applied in the manufacture of compressed biofuels or for making compressed wood boards [19], but new applications should be explored. A mixing machine can be added to the typical industrial sludge drying setup which consists of a belt dryer and sludge extruder.…”

Bioenergy Devices: Energy and Emissions Performance for the Residential and Industrial Sectors in Mexico

“…Drying is an important unit operation for industry purposes and different types of dryers are commercially available [29]. A dryer is specially designed for drying the biomass materials, such as wood sawdust, small wood chips, rice hull, sunflower husk, peanut shell, etc.…”