Bed-Shrinking Flow through Reactors
The bed-shrinking flow-through (BSFT) reactor uses spring-loaded plungers to continuously reduce the reactor bed volume during the hydrolysis process as shown in Figure 7.2. [36, 31, 37-39]. Joint research efforts from the National Renewable Energy Laboratory (NREL), Golden, Colorado, and Aurban University have shown that excellent cellulose hydrolysis yields can be achieved under extremely low sulfuric acid and high-temperature conditions using bed-shrinking flow-through reactors. They compared hydrolysis of cellulose and poplar under batch reaction and bed-shrinking
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pump Figure 7.2 The schematic diagram of a laboratory setup of bed-shrinking the flow-through (BSFT) reactor system invented at NREL. (Reprinted with permission from reference [39]; copyright 2001 Springer). |
flow-through reactors under extremely low acid (ELA) conditions (0.07 wt%) and at temperatures > 200°C. The maximum yield of glucose obtained from batch reactor experiment was about 60% for — cellulose, which occurred at 205-220°C. The maximum glucose yields from yellow poplar feedstocks were in the range of 26-50%. In another experiment using BSFT reactors, the glucose yields of 87.5, 90.3, and 90.8% were obtained for yellow poplar feedstocks at 205, 220, and 235°C, respectively. The hydrolysis rate for glucan was about three times higher with the BSFT than with the batch reactors. Additionally, Kim et al. have shown that the difference of observed kinetics and performance data between the BSFT and the batch reactors was far above that predicted by the reactor theory [39].