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Japan Chemical Innovation Institute
Makoto Fujie, Ph.D
Akifumi Inui, Ph.D
NIMC Department of Chemical Systems
Tsutomu Sugeta, Ph.D
Takeshi Sako, Ph.D
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@Along with world's economic development and increase in population, the needs
for fuel supply will be a serious issue because the petroleum, a resource which has been
available with relatively simple processing, will run out eventually. Therefore, in the
future, it will be required to use low grade fossil fuels such as coal and super heavy oil
as well as organic resources such as plastic waste and bio-mass which have not been
used as resources up till now. No technique which enables us to use these resources
as alternatives has been developed so far, either. In order to make this possible, an
environmentally safe combustion technique using low grade fuels with hazardous
substances and/or high water content has to be developed. That is to say, from the
points of environmental protection as well as effective use of resources, the
development of this technique is indispensable.
@Combustion technique in supercritical water under the temperature and pressure condition exceeding the critical point of water is expected as a technique free of generating toxic gas because NOX, SOX and dust, which have been the major causes of environmental pollution, can be captured in water. By using this combustion technique to generate steam, the construction of environmentally friendly novel power generation system will be possible. @Conventional power generation plant using coal demands high-grade coal with low toxic substances such as nitrogen or sulfur in order to achieve the environmental standard of NOX, SOX or dust emission. Furthermore, constructing and operating huge equipment to treat exhaust gas is expensive. @We have been investigating the combustion behavior of brown coal as a representative of low-grade fuels in supercritical water using an experimental apparatus shown in the photograph. We obtained the result that the exhaust gas generated from this experiment does not contain any hazardous components. As shown in the figure, NOX is not detected in the exhaust gas and more than 99% of SOX is removed from the exhaust under the condition of 30MPa and 600. Using this combustion technique suggests that low-value fossil fuels such as low-grade coal and super heavy oil with high sulfur content and waste materials such as plastic waste, municipal waste, bio-mass with high water content or sludge can be burned safely and the steam can be recovered for power generation. Thus, this technique enables us to have environmentally friendly novel power generation without exhaust gas treatment system, and the more, due to the relatively simple procedure to separate and collect CO2, its fixation may become easier. @Further investigations are necessary to make clear the mechanism of the combustion in supercritical water, the characteristics and behaviors of solids such as ash and salt, and the corrosion resistance of materials used for reactor. Moreover, the techniques such as neutralizing sulfur, discharging solids, economical supply of fuel and oxidizer and separating and collecting CO2 have to be developed to systemize the power generation. @This research has been carried out as a part of Leading Research Program of Development of Advanced Utilization Technologies of Supercritical Fluids entrusted to Japan Chemical Innovation Institute and National Institute of Materials and Chemical Research (NIMC) by New Energy and Industrial Technology Development Organization (NEDO) under the New Sunshine Program of Agency of Industrial Science and Technology (AIST), Ministry of International Trade and Industry (MITI).
 Experimental apparatus of supercritical water combustion
 Temporal change of exhaust gas composition in supercritical water combustion with semi-batch flow reactor |
Press Release