TWO-STAGE FORCED CONVECTION FURNACE FOR RIBBED RUBBER SMOKED SHEET (RSS) PRODUCTION: PERFORMANCE EVALUATION

Abstract

Due to improper design of the original rubber smoking-room, Ribbed Rubber Smoked Sheets
(RSS) productions at Thai Rubber Smoking Cooperatives (RSCs) are undergoing. In this research, a prototype
of the two-stage forced convection system has been proposed to renovate the traditional smoking process.
Generally speaking, to enhance the efficiency of fuel consumption and to increase the number of qualitative
RSS, the new hot-gas supplying system was carefully designed and constructed. Eight small ventilating lids
were specifically used at the smoking-room ceiling to improve the velocity and temperature distributions. To
obtain the optimal temperature (60°C) for natural rubber smoking, the feeding rates of firewood and the
supplying rates of hot gas while operating this new forced convection system were optimized. According to
the RSS production (1458 sheets), the drying time and the fuel consumption were found at 90 hrs., and 1.04
ton per a ton of the dried sheets, respectively. Surprisingly, 92% (822 kg) of the dried RSS were found to be
above the selling grades; nevertheless, the remaining was in the cutting-grade due to having the unacceptable
thickness (> 3mm). Overall, the new two-stage forced convection system could save 25% of production time
and 35% of fuel consumption compared with the original natural convection system. Because the harmful
aerosol particles could be trapped, so this new forced convection system may be friendly to the environment
as well. In future work, a Computational Fluid Dynamics (CFD) technique will be used to enhance the
efficiency of this new smoking-room system for RSS production.