In addition, the oil-fired or coal-fired power generation can be reduced at this rate if the refuse incinerators which have incinerated the refuse only to emit CO2 is changed to a highly efficient power station, and the double contribution can be expected for CO2 reduction.
It is well-grounded that the power generation by the refuse incineration heat in Japan is behind. Penshable garbage in Japan contains much salt, and vinyl chlorides, etc. are mixed therein, and if they are incinerated, the concentration of hydrogen chloride in the combustion gas is increased. When the tubes of the boilers are heated using such a gas, the high-temperature chlorine corrosion is rapidly promoted around the temperature of the tube wall exceeding 330℃ with regular boiler tube steel. Thus, the temperature of the steam can not be increased above 330℃, and even when the steam turbine is driven with the steam of such a low temperature, the generating efficiency is at most 12%, and the refuse power generation has been kept at a distance due to little advantage.
Thus, the principle of the repowering is applied to the refuse incineration power generation. This means that the gas turbine is installed additionaly and is driven by separately burning the fuel. Even at the steam temperature at which the boiler tubes are not corroded, i.e., the steam temperature of whichi is about 290℃, this steam is superheated up to over 450℃ with the exhaust gas of the gas turbine, and the steam turbine is driven thereby to enable the combined cycle power generation, expecting the higher efficiency. The Institute of Applied Energy adopted this idea of repowering type combined cycle refuse incineration power generation proposed by the author, and has challenged its feasibility study since 1991 FY. The Ministry of Home Affairs attracted the attention to the refuse incineration power generation of this type in an early time, and started its study by establishing the "Examination and Research Working Group on Business Promotion of District Energy", and concluded its effectiveness, and gave the incentives of approving the flotation of the loan for the local governments to promote the business. The Working Group was chaired by the author, and such a power generation system was named the "super refuse power generation" by Mr. Morio. Sakamoto. then-Manager of Second Public Enterprise Division of the Ministry of Home Affairs.
Fig.4 is the system diagram of "Takahama Power Plant" of Gunma Prefecture which was put into business operation as the first super refuse power generation plant in November, 1996. The refuse incineration plant in the Takahama Clean Center to supply the steam to the power station was completed in June, 1988, and two sets of incinerators out of three sets of incinerators having the incineration capacity of 150 tons/day are generally in operation and treat the refuse of 300 tons/day. They drive the steam turbine generator of 1,300 kW to cover the power in the center, and the excessive power has been sold to the Tokyo Electric Power Co., Inc.
The gas turbine of 16 MW and the steam turbine of 9 MW are newly added this time, obtaining the actual generating efficiency of 35% (LHV standard) which is above the planned value. The waste heat is used for the air-conditioning service and hot water supply within the plant, and the hot water is also supplied to the Municipal Senior Welfare Center adjacent thereto. The super refuse power generation is followed by Sakai City as the second one, Kitakyushu City as the third one, and Chiba City as the fourth one.
