For the purpose of stable supply of energy while decreasing dependence of fossil fuels in the future, both clean coal technologies and environment load reduction technologies are extremely required to develop. For the development of clean-up system of sulfur-containing wastes from coal devoletilization process in coke oven, decomposition experiments of a thiocyanic ion, SCN-, in sub- and supercritical water were examined with oxygen and hydrogen peroxide as oxidizers at temperatures from 25 to 400 °C and at 25 MPa by a flow-through reactor. High-temperature water treatment in the presence of oxygen with O2/SCN- molar rario of 75 led to about 40 % decomposition of SCN- for 30 s at 350 °C. In contrast, the treatment in the presence of hydrogen peroxide with O2/SCN- molar rario of 30 led to complete decomposition of SCN- for 30 s at 200 °C. It was found that decomposition ratio of SCN- could be much improved with hydrogen peroxide as a oxidizer. These results show the clean-up system of sulfur-containing wastes can be made compact using sub- and supercritical water oxidation techniques.
In recent years, recycling of organic waste has been needed in Japan. To make biogas and compost are usual ways of the recycling today. And a microbial fuel cell (MFC), a direct generator using microorganism from organic and inorganic compounds, has been investigated recently. Volatile fatty acid, food processing wastewater and landfill leachate were used to produce electricity by MFC in the past studies. But there is little knowledge about MFC using wheat bran. We tried to produce electricity by the MFC using wheat bran and succeeded to generate between 0.2V and 0.36V for 250 hour. The factors affecting MFC performance were investigated, we found that substrate concentration, a kind of mediator, ion concentration and electrode material could affect the MFC performance. We tested the discharge transient behavior of the MFC and fitted theoretically calculated values to observed values. By the fitting, we clarified the equivalent circuit constant, i.e., inner resistances and capacitor of the MFC.
This paper presents new pyrolysis model of wood and grass biomass. It is named biomass-CPD model. A scheme of the Chemical Percolation Devolatilization (CPD) model which was used in numerical analysis of coal pyrolysis was applied to description of wood and grass biomass pyrolysis. Cellulose, hemicellulose and lignin which are three main components of wood and grass were modeled at first. A molecular structure of each component was determined from that of its monomer, and a rate constant of each component was determined from both the conventional model and the pyrolysis curve from experiment. The pyrolysis process of wood and grass biomass was expressed by a summation of that of cellulose, hemicellulose and lignin calculated from the developed model. The content of each component in wood and grass was predicted from the ultimate analysis and the proximate analysis of wood and grass. By using above-mentioned new method, the pyrolysis process and the yields of total volatiles and tar of wood and grass biomass was predicted by only values of biomass properties and pyrolysis conditions. From a comparison between calculation and experimental results, the predicted pyrolysis process and yields of total volatiles and tar of various wood and grass biomass pyrolyzed under various conditions are in good agreement with the experimental ones, and we show the validity of the biomass-CPD model.