Production of Eco-Friendly Slurry Fuel from Biomass and Low Rank Coal Mixture by Hydrothermal Treatment

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During circulative hydrothermal treatments of biomass and low rank coal, it is clarified that the blend of these materials reveals a discrepancy in TOCs between the theoretical and experimental values due certainly to the adsorbent effect of the coal. Therefore, coalffication and partial adsorption of extractives are expected by mixing up the biomass with the coal during hydrothermal treatment. TOC variation is predicable from an on-line monitoring of the absorbance intensity during the treatment. Effects of treatment temperature and mixing ratio on the fuel characterization of the solid phase of the treated material were studied by the batch and continuous treatments. The treatment at higher temperature affects more on degree of the upgrading for both the materials and the upgrading reaction of the mixture was independent and in parallel with each other. The fuel ratio decreased as the mixing ratio increased, however, the chemical compositions of C,H,N and 0,and the gross calorific value were almost identical on a dry ash-free basis, independent of the mixing ratio. The continuous test produced the solid phases having a gross calorific value similar to that for the batch test. In addition, it is worth mentioning that a five-hour run of the continuous treatment was conducted successfully. The characterization of the liquid phase clarified that reducing phenols such as 2,6-dimethoxyphenol, guaiacol and etc. as well as acetic acid and methanol were contained in the liquid phase. The liquid phase reduced Cr (VI) effectively to Cr (III) and the addition of slaked lime or quicklime to the reduced system removed almost all amount of Cr (III) as a precipitate. The amount of sludge decreased 1/2 - 1/3 as compared with the use of iron (I) sulfate as a reducer.