TSUTSUMI Kazuo KAWASAKI HEAVY IND.LTD.PARTICLERES.LAB.RESEARCHER, 粉体技術研究所, 研究員
KOBAYASHI Noriyuki NAGOYA UNIV., DEPT.CHEMICAL ENGNG.ASSIST.PROF., 工学研究科, 講師 (90242883)
FURUHATA Tomohiko NAGOYA UNIV., RES.CTR.FOR ADVANCED ENERGY CONVERSION RES.ASSOCI., 高温エネルギー変換研究センター, 助手 (80261585)
KITAGAWA Kuniyuki NAGOYA UNIV., RES.CTR.FOR ADVANCED ENERGY CONVERSION ASSOC.PROF., 高温エネルギー変換研究センター, 助教授 (00093021)
MIURA Takatoshi TOHOKU UNIV., DEPT.CHEMICAL ENGNG.PROF., 工学研究科, 教授 (60111259)
To respond to these challenges for gas-turbine system improvement, the Research Center for Advanced Energy Conversion, Nagoya University, established in April 1992, has launched an R&D program which has so far resulted in a break-through gas turbine technology, named the Chemical Gas Turbine (CGT), which has been based on promising developments in advanced fuel-rich combustion, and in C/C composites for the turbine blade rotor.
The principal components are a fuel-rich combustor, a fuel-lean combustor, two sets of gas turbines, a steam turbine, and heat exchangers. An important feature of this system is the use of fuel-rich combustion, named here Chemical Combustion, because of its following advantages :
(1) It produces low levels of NO_x,
(2) the exhaust gas from the fuel-rich combustor produces power during its expansion through the first turbine, and still contains chemical energy in its H_2 and CO components, (3) this exhaust gas can thus produce more power in second stage steam or gas
turbine, or possibly in a fuel cell,
(4) noting that currently the only candidate materials for turbine blade operation above 1773 K without internal cooling are C/C composites, and that such materials are sensitive to high-temperature oxidation, fuel-rich combustion, which results in significantly reduced quantities of oxygen in the exhaust stream, is very well suited for this application.
To develop the novel system proposed above, we mainly studied on the several theme as follows :
(1) fuel-rich combustion under high pressure by using the developed highly pressurized combustor
(2) flue gas combustion which derived from fuel-rich combustion gas
(3) fundamental performance characteristics by using the developed micro-Chemical gas turbine
We have obtained the following result :
(1) We investigated the dependency of the flame structure on presure and equivalence ratio in methane-air pressurized combustion to obtain detailed data for designing the fuel-rich combustor for the gas turbine. The flame under fuel-rich condition at 1 MPa had an underventilated structure like typical atmospheric fuel-rich flames, while the flame over 1.5 MPa had the shape of a fuel-lean flame. Under fuel-rich condition there was a smaller dependence of the flame length on pressure as compared with flames under fuel lean conditions. The flame length has increased with pressure under the fuel-lean conditions.
(2) The three-dimensional simulation on highly pressurized combustion was performed. There are good agreement with experimental and simulated results under fuel-lean condition. Several problems for fuel-rich conditions exist because of chemical kinetic models.
(3) We have developed a lab-scale chemical gas turbine for demonstration, and investigated its characteristics. The length of the combustor for the micro-chemical gas turbine was 230 mm and the inner diameter 50 mm. The mass flow rates of air and methane were designed as 62 Nl/sec and 22.8 Nl/sec at the rated operation, respectively. Under these conditions the equivalence ratio is 3.0, the compression ratio 2.6, the rated rotational velocity 100,000 rpm, and the rated output 2.5 kW. Less