MODIFIED PERCOLATION PROCESS IN DILUTE-ACID HYDROLYSIS OF BIPHASIC HEMICELLULOSE

To improve the performance of a percolation reactor in dilute-acid pre treatment of biomass containing biphasic hemicellulose, a reactor simu lation study was conducted focusing on the refinement of operating str ategies and conditions. The optimum temperature difference in step-cha nge operation was determined to be 30 degrees C for a wide range of re action temperature. Application of temperature step change along with flow-rate step change brought about a 0.6% improvement in product yiel d over the case with temperature step change alone. The most significa nt improvement, however, was seen with the application of the two-stag e reverse-flow reactor arrangement with temperature change (a design c oncept originally developed at NREL). Use of this reactor has given an additional 5% improvement in product yield over that of the best-case percolation reactor employing temperature step change. In addition, t he effect of intraparticle diffusion on product yield was investigated . The critical chip size (above which the effect of diffusion becomes significant) was determined to be 0.40 cm for 140-170 degrees C operat ion and 0.29 cm for 150-180 degrees C operation.