Yasushi Hayasaka

Development of an Advanced Microturbine System Using Humid Air Turbine Cycle

A prototype machine for a next generation microturbine system applying a simple humid air turbine system (design target of electrical output: 150 kW, electrical efficiency: 35% LHV) was developed for its laboratory evaluation. A low NOx combustor which applied a lean-lean zone combustion concept and water lubricated bearings were developed for the prototype machine. Operation using two water lines for the humid air turbine (HAT) was proposed as an effective way to obtain rated electric output to ambient temperature of 40 deg C. Tests for the main components were done successfully. Motoring tests, full speed test with no load, 50% load and 70% load tests as preliminary tests for rated load tests were also carried out successfully. Low NOx emission of 7.6 ppm and high efficiency of 95.6% for the power conversion system were achieved in the partial load tests. At the first rated load test without HAT and Water atomizing inlet air cooling (WAC) that followed those partial load tests, 150.3 kW electric output with electrical efficiency of 32% was obtained.© 2004 ASME

Development of a 150kw Microturbine System Which Applies the Humid Air Turbine Cycle

A prototype machine for a next generation microturbine system incorporating a simplified humid air turbine cycle has been developed for laboratory evaluation. Design targets of electrical output were 150 kW and of electrical efficiency, 35% LHV. The main feature of this microturbine system was utilization of water for improved electrical output, as lubricant for bearings and as coolant for the cooling system of the generator and the power conversion system Design specifications without WAC (Water Atomizing inlet air Cooling) and HAT (Humid Air Turbine) were rated output of 129 kW and efficiency of 32.5% LHV. Performance tests without WAC and HAT were done successfully. Electrical output of 135 kW with an efficiency of more than 33% was obtained in the rated load test. Operation tests for WAC and HAT were carried out under the partial load condition as preliminary tests. Water flow rates of WAC were about 0.43 weight % of inlet air flow rate of the compressor and of HAT, about 2.0 weight %. Effects of WAC and HAT were promptly reflected on electrical output power. Electrical outputs were increased 6 kW by WAC and 11kW by HAT, and efficiencies were increased 1.0 pt % by WAC and 2.0 pt % by HAT. Results of WAC and HAT performance tests showed significant effects on the electrical efficiency with an increase of 3.0 point % and electrical output with an increase of 20% by supplying just 2.4 weight % water as the inlet air flow rate of the compressor.Copyright

Life Management System for Hot-Gas-Path Components of Gas Turbines

Recently the number of gas-turbine-powered combined-cycle plants has been increasing because of their efficiency and environmental compatibility. Gas turbine operating conditions are severe, especially for hot-gas-path components. To improve the reliability of such components and to extend their life, we have developed a life management system based on a residual-life-assessment method. The system makes possible integrated residual-life-assessment based on numerical analyses, material destructive-tests, nondestructive inspections, statistical analyses of field machine data, and the use of a database. To develop the system, the primary damage mechanism for each component is clarified and material degradation is evaluated. For nozzles, the system describes a method of predicting the maximum surface crack growth. The validity of the methods is verified by assessment of the inspection data. This paper also describes optimization of operating cost and RAM (reliability, availability and maintainability).Copyright

Development of New SCADA System for 500kV Substations

AbstractWe developed a new SCADA system for 500-kV substations. To apply existing LAN-based SCADA system for unmanned 275-kV or 77-kV substations, we had to develop three functions. Firstly, the new SCADA system enables that 500-kV substation is supervised and controlled from multiple operating sites. Secondly, the database of the new SCADA system can be downloaded the maintenance data from the SCADA system for 500-kV control center via an IP network. Finally, the new SCADA system has supervisory control capability for manned 500-kV substations.In this paper, we describe these functional over view of the new SCADA system. Currently, 500-kV substations are manned substations. And these substations are supervised and controlled by human operators on sites. Using the new SCADA system, 500-kV substations will be realized remote supervisory control from the 500-kV control center a few years later. Therefore, manned 500-kV substations will convert into unmanned substations.

Analytical Method of Fatigue Damage Estimation for Compressor Stator Blades of Gas Turbines Experiencing Rotating Stall

To improve the reliability of compressor stator blades of gas turbines, an analytical method for estimating their fatigue damage has been developed. This method is based on blade-vibratory-stress analysis, stress-peak counting, and use of actual environmental data. The blade-vibratory-stress analysis takes the superposition of multi-peaks of the stress spectrum into account. The numerically simulated stress showed better agreement with measured stress than that from a conventional stress analysis, which is based on frequency-response analysis considering a single peak of the lowest single eigen-vibration-mode. A time-domain stress history was synthesized from the blade-vibratory-stress analysis results. Furthermore, the fatigue damage of the blade under rotating stall was estimated by the linear-damage-rule from the stress-peak counting of the stress and from material data. The estimated fatigue-damage agrees well with the measured results. This agreement means that our new fatigue-damage-estimation method is more accurate than the conventional one.Copyright