Independent power producers (IPPs) in Japan attract close attention after the recent revision of the Electric Utilities Law. The revision abolished the licensing of wholesale electricity supply and at the same time introduced the wholesale bidding system. The background of this change consists of the technical innovation and economical condition. The technical innovation is the development of efficient and economical small size power sources which utilize gas-turbine, fuel cell or co-generation system and the economical condition is the situation that requires more competition for inexpensive energy supply. The bidding of wholesale electricity supply which was solicited in FY 1996 and FY 1997 proved the existence of considerably large amount of potential IPPs which are inexpensive than the projects of electric utilities. This fact leads to the further expansion of bidding system, which is that all thermal power plant will be decided to develop through the competition of the bidding after FY 1999. On the other hand, to correspond to the global warming issue, the bidding system will be revised to introduce the evaluation of the environmental impact which will be caused by the IPPs. It means a significant change of the philosophy of the present bidding system, which had established a principal value on the economical standpoint. To introduce furthermore completion into the electric industry, the liberalization of retail supply is under discussion now. Through this process, IPPs will get higher appreciation from the standpoint of more economically efficient electricity supply.
IPP's share in the world power generating market has grown year by year and its capacity had risen to 138, 909MW by July 1997. Major factors are deregulation of generating market in developed countries such as the U. K. and the active introduction of foreign IPPs to resolve the lack of electric power in developing countries. Many of IPPs expect that IPP's capacity will continue to grow because energy demand will continue to grow, rapidly in developing countries and modestly in mature markets.
The reactivity of entrained coal char is an important issue for improving total efficiency of the entrained bed gasifier by recycling cyclone captured char. This study aims to elucidate the differences of reactivities among chars that have different heating history. Four kinds of coals were used for the experiments. Char samples were collected by cyclone in the 3 ton/day bench scale entrained bed gasifier. In addition, carbonized char samples were prepared in the batch reactor to compare with reactivities of entrained chars. The differences of reactivities among char samples - were successfully correlated with the difference of numbers of active site. The effects of pressure and temperature were also investigated. The dependency of reaction rate constants on pressure was proportional to 1/4 power of total pressure at 1270 K. The pressure dependence on reactivities was not observed under the conditions of pressure over 1.6 MPa at the higher temperature as 1570 K. This may be caused by the reaction limiting step change from reaction control to diffusion control. The experimental results show that the entrained chars have the higher reactivities than carbonized char. This suggests that the entrained char recycle to the gasifier is beneficial to improve total efficiency of gasifier.
Fundamental study was carried out aiming at the development of a large amount of use technology as civil materials of the coal ash from the fluidized-bed combustion boilers. A series of study was done by using coal ash produced from the fluidized-bed combustion boilers of the normal pressure and pressurizing. The properties of coal ash, and the characteristic of the solidified coal ash by steam treatment for the kneading material with water were examined. The main results obtained are sumamarized as follows: (1) The amount of amorphous materials is not influenced by the condition in boiler (pressure, carbon dioxiide concentration and so on) though a solid phase reaction takes place between ash of coal and lime at boiler temperature 850°C, generates more amorphous substances with a lot of CaO contents of the fluidized bed materials.(2) In case the coal ash in the normal pressure and pressurizing is about 1 of CaO/SiO2 mole ratio and about 2.5 CaO/Al2O3 mole ratio, the solidified coal ash is optimized in the amount of the ettringite and C-S-H, and shows the maximum compressive strength.(3) The leached rate of the toxic heavy metals of the solidified coal ash satisfied a solid environmental standard. Moreover, the amount of the toxic heavy metals and the electric conductivity of the leached solution in the solidified coal ash reached lower value than those in the coal ash. Therefore, it is judged that the toxic heavy metals became steadier reactive materials by solidification.
Three kinds of finely pulverized iron ores (limonite, pyrite and hematite) and four types of synthesized iron compound (α-FeOOH, γ-FeOOH, α-Fe2O3 and Fe3O4) were tested as precursors for direct coal liquefaction catalyst. The liquefaction activity was increased with a decrease in the average particle size of finely pulverized iron ore. The HS yield was higher in the order; γ-FeOOH> α-FeOOH, limonite > pyrite > hematite. The correlation of the catalytic activity between the liquefaction of Yallourn coal and the hydrogenation of 1-methylnaphthalene (1-MN) was examined, and it was found that HS yield closely related to the yield of demethylated products (tetralin + naphthalene). The activity for the C-C bond cleavage such as the demethylation activity should be required for iron catalyst in the liquefaction of coal. It appeared that the demethylation activity was correlated with the pore volume of spent catalyst which consisted of fine particles of pyrrhotite. TEM photographs indicated that the pyrrhotite formed from γ-FeOOH had the smallest particle size among the spent catalysts.