A Study Of Continuous Hydrothermal Saccharification Of Straws Under Low Acid Condition

With the development of the technology of utilizing renewable energy, thesecond-generation fuel ethanol which is obtained from the biomass isprospering day by day. Besides, the conversion of biomass into reducingsugar as intermediates is an important research subject in the utilization ofbiomass. In this paper, being the research objects, wheat straw and rape straware used as raw materials to produce reducing sugar under low aid coupledwith continuous gradient heating mode. In this process, the by-product offurfural is systemically researched, and an economic evaluation ofsaccharification technology is given.Applying the continuous hydrothermal device designed by the author, thispaper mainly focuses on the influences of flow rate and the concentration ofsulfuric acid upon the hydrolysis of the two raw materials in producingreducing sugar and furfural. The conclusions are as follows: the highestreducing sugar concentration and yield can be got when the sulfuric acidconcentration is1.0%and the flow rate is25mL/min. Under the aboveoptimal circumstances, the reducing sugar concentration and yield of wheatare as high as32.91g/L and60.8%, with those of rape being20.1g/L and53.4%, respectively. The furfural concentration was less than1.0g/L duringthe whole gradient heating process and the reducing sugar concentration peakappeared before furfural concentration. Therefore, the reducing sugar andfurfural could be easily separated from the system, which could reduce theinhibition of the by-products in the process of fermentation. Moreover, basedon the observation of the residues by SEM, the content analysis and FT-IR analysis, this paper further explores the hydrothermal mechanism of strawsunder the optimal condition.Finally, this paper analyzes the economical efficiency of wheat and rapestraw saccharification. In2011, the utilization of wheat and rape strawmaterials were40.68million tons and6.34million tons respectively. Theycould get economic benefits about15.41billion yuan and2.47million yuan ifthey were used to produce reducing sugar. At the same time, approximately44.20million tons of carbon dioxide emission could be reduced, whichgreatly reduced greenhouse gas emissions.