The reaction of chromic oxide ion in aqueous solution with twelve kinds of coal samples has been studied. It was found that the chromic oxide ion reacted selectively to catechol type compounds at 273K by the experimental result for some kinds of coal model chemical compounds. The existence ratio of catechol type components in each coals was estimated at 273K.

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The total efficiency of a co-generation system is commonly estimated using average heat and power demands. It is known that the estimated total efficiency greatly differs when using hourly average demand as opposed to annual demand data, owing to demand fluctuation.
The aim is to determine the numerical values of the error when examining the total efficiency of co-generation system; and to explain analytically why the error arises.
In the paper, based on mathematical model, the error is modeled as the ratio of the estimated total efficiency to the real total efficiency. The error was given by: (1) the heat to power ratios of the site and of the co-generation system itself; (2) the efficiencies of co-generation electric power and of auxiliary boiler; and (3) the demands fluctuation rates of the site.
Estimated total efficiency is overestimated. The error achieves its maximum value when the heat to power ratio of demand and of the co-generation system match. The error is nearly constant, when a heat to power ratio at the site is higher than the heat to power ratio of the co-generation system itself. Such error varies by 10% when considering a gas turbine co-generation system, if demands fluctuate by 10% from their respective average demands.

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The effects of hydrogen donation on coprocessing of coal and three kinds of plastics such as high density polyethylene (HDPE), polypropylene (PP), and polystylene (PS) were investigated under the presence of hydrogen from gas or liquid phase. In the liquefaction reaction of coal alone or each plastic alone, hydro-gen from liquid phase (tetralin) gave a large influence on yield, as compared with hydrogen from gas phase. Contrary to coal, the gasification of plastics was inhibited by the presence of hydrogen from liquid phase.
In the coprocessing using decalin solvent under hydrogen gas, the gas yield decreased greatly and the oil yield increased. However, in the coprocessing using tetralin solvent, little interaction was observed. It was suggested that the reactions between coal and plastic radicals were inhibited as a result of rapid stabi-lization of the produced radicals by hydrogen from tetralin.
The effect of plastic type on coprocessing reaction under decalin solvent was investigated. All the plastics tested decreased the gas yield, which suggested plastic radicals were stabilized in coprocessing reaction. Furthermore, experimental results suggested that HDPE radical tend to be stabilized by the contact with other radicals, and that PP and PS radicals tend to be stabilized by hydrogen transfer from decomposi-tion products of coal.

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