T. Theppaya

Optimization of Rubber Wood Drying by Response Surface Method and Multiple Contour Plots

Abstract By adopting the central-composite experiment design, the response surface methodology was used to optimize operating conditions of rubber wood drying. The independent variables are initial moisture content of rubber wood, and three drying environment parameters namely, temperature, relative humidity, and air velocity. The investigating responses are final moisture content, drying time, and energy consumption. The restriction of the optimization is the designated final moisture content, which is not greater than 16%. The third-order polynomial models with transformed responses were developed from experiment data to generate 3-D response surfaces and contour plots. The analysis of variance (ANOVA) was performed to identify the significant parameters affecting the rubber wood drying. Drying temperature and holding relative humidity are those two influential operating parameters that significantly control the final moisture of rubber wood and affect the drying time and energy. The multiple contour plots of drying responses show that the optimum operating regions are located mainly at high temperature drying zone. The high temperature drying practice can save energy and drying time by 44 and 25% respectively, in comparison to the conventional temperature drying.

PARAMETERS INFLUENCING DRYING BEHAVIOR OF RUBBER WOOD (HEVEA BRAZILLIENSIS) AS DETERMINED FROM DESORPTION EXPERIMENT

ABSTRACT In this study, the drying properties of rubber wood, which are the basic parameters for kiln scheduling design, were determined from desorption experiment. Equilibrium moisture content expression was developed. The diffusion coefficients at different drying environments were evaluated. It is more appropriate to determine the diffusion coefficients by the optimum scheme in comparison to other schemes; the logarithmic, square-root and half-fraction of evaporable moisture schemes. Finally, the diffusion coefficient of rubber wood was described by, instead of wood moisture content, the drying temperature and relative humidity, which are the parameters controlling the drying kiln operation.

Development of an energy-efficient brick kiln

Brick making in developing countries, which relies on biomass fuel, is facing energy shortage. This paper reports a study aiming to develop an energy-efficient brick kiln. The drying, preheating, firing and cooling of bricks were studied by computer simulation of a fixed bed model and resulted in a new design of downdraft brick kiln. The new kiln has four chambers to serve the four processes separately but simultaneously. A heat recovery feature was incorporated in the kiln operation. A kiln was constructed for full-scale experimentation. The experiments showed that the specific energy consumption could be as low as 2·3 MJ kg−1 of brick, which was only half of that presently consumed in traditional open top updraft kilns. The energy efficiency of the new kiln was 62·6% on average.

Continuous Transesterification for Ethyl Ester Production from Refined Palm Oil through Static Mixer

In this study, the commercial grade of ethanol was used to produce the biodiesel from refined palm oil (RPO) through the continuous static mixer system. The ethanol, an alternative alcohol to adopt in the ethyl ester production, can be used instead of methanol, and this alcohol is more eco-friendly than methanol. The 6-meter in length of SUS304 static mixer reactor is an essential part of mixing the RPO and solution of ethanol and potassium hydroxide to accelerate the base-catalyzed transesterification. The ethanol were varied at the volumetric flow rate of 30, 40, 50, 60 vol.%, KOH as base-catalyst was varied with the weight to volume of oil of 10,12,14 gKOH.L-1, to investigate the suitable condition which can converted the glycerides to the maximum purity of ethyl ester. The results showed that all varied conditions, the ethyl ester conversion was rapidly increased from 0 to over 95 wt.% when the flowing mixtures flowed through the 1 meter of static mixer. Furthermore, the highest purity of ethyl ester from RPO was succeeded when the condition: the 60 vol.% ethanol, the 14 gKOH.L-1 of catalyst, 5-meter of static mixer, and 75 oC temperature of RPO, was used in the continuous static mixer.

CFD in Continuous Stirred Tank: Comparison between Rushton and Paddle Turbines

Biogas produced from palm oil mill effluent (POME) is common in Thailand. A 2-step digestion system, which consists of a continuous stirred-tank reactor (CSTR) and a UASB, is being implemented for biohythane (biohydrogen and biomethane) production. This paper describes three-dimensional computational fluid dynamics (CFD) simulations of POME flow in a laboratory-scale CSTR. The study focuses on comparisonof impellers, the Rushton and the paddle turbines, for the best POME mixing with minimum loss of granules. The result of flow patterns in CFD showed that better mixing in the bottom through the middle of the tank can be achieved by proper selection of impellers and baffles to avoid the loss of granules by effluent.