ABSTRACT Recuperators are considered essential hardware to achieve the efficiencies desired for advanced microturbines. Compact recuperator technologies, including primary surface, plate and fin, and spiral, all require thin section materials that have hightemperature strength and corrosion resistance up to 750 o C or above, and yet remain as low-cost as possible. The effects of processing and microstructure on creep-rupture resistance at 750 o C and 100 MPa were determined for a range of austenitic stainless alloys made into 0.1 mm foils. Two groups of alloys were identified with regard to improved creep-resistance relative to type 347 stainless steel. Alloys with better creep-rupture resistance included alloys 120, 230, modified 803 and thermiealloy, while alloy 214 and 625 exhibited much better creep strength. Alloys 120 and modified 803 appeared to have the most cost-effective improvements in creep-strength relative to type 347 stainless steel, and should be attractive for advanced microturbine recuperator applications.

ABSTRACT: This paper studies an Integrated Gasification Combined Cycle-Solid Oxide Fuel Cell (IGCC-SOFC) hybrid power system. Based on the intercrossing of electrochemical process and thermodynamic cycle, this paper has proposed a dual cycle IGCC-SOFC hybrid power system. Based on the Aspen Plus soft, the model of the IGCC-SOFC hybrid power system has been established and the performance of the overall hybrid power system affected by the main operating parameters of SOFC system has been analyzed and optimized. The obtained results show that IGCC system integrated with the high temperature SOFC combined cycle system has a higher thermal efficiency through decreasing the current density; the higher fuel utilization ratio (η g ) also improves the efficiency of hybrid power system; with the increase of the syngas distribution ratio X fl , both the total power output and system efficiency of the hybrid power system are improved greatly. When X fl is 1.0, compared with the base IGCC system without integration with SOFC system, the efficiency of hybrid power system increases by 10 percentage points approximately. Above research achievements will provide a valuable guide for further study on IGCC-SOFC hybrid power system. INTRODUCTION Integrated gasification combined cycle (IGCC) is one of the most efficient and cleanest technologies for coal-based power generation, with emissions to air comparable to those of natural gas-based power production in a gas steam combined cycle plant. Now many countries are developing and demonstrating IGCC system [1-2]. However, despite the worldwide commercial use and acceptance of gasification processes and natural gas combined cycle power systems, until recently IGCC was cited still not to be established as a mature technology for electricity generation. In addition, because of its high installed cost and complexity of total system (as shown in Currently, as a rapidly developing power generation technology, fuel cells can offer higher efficiencies and significantly lower emissions than conventional power generation technologies. It can directly convert the energy of a chemical reaction into electricity, with heat as a by-product. Among all types of fuel cells, the operating temperature of Solid Oxide Fuel Cell (SOFC) is the highest, with the temperature range from 700 -1000 . The higher exhaust temperature from SOFC provides the most convenient condition for the integration with the conventional thermal power generation system. The SOFC gas turbine hybrid power system usually has a higher efficiency than the traditional power generation system. So, it has been become a focus of research and development in recent years. From the aspect of technology, SOFC technology is now in a development phase ranging from fundamental research to prototype system operations and construction of new manufacturing capacity. Due to the totally different power generation systems between SOFC and gas turbine, there are some problems of mismatching when these two systems are integrated. For example, because the gas turbine is a fast reacting power system and the fuel cell is slow reacting system, this results in a typical mismatch problem of dynamic characteristics of gas turbine and the fuel cell, especially during the startup and shutdown period. When SOFC is integrated with the large-scale gas turbine with higher turbine inlet temperature (above 1300 ), because the exhaust temperature of SOFC is lower than the required turbine inlet temperature,

This paper reports an assessment of coupling micro gas turbine and high temperature fuel cell (SOFC) as a possibility to realize power plant with an efficiency of 75%. The application of such a technology will be in the decentralized feed-in of housing estates and buildings with electricity, heat and cooling energy. Nowadays the first implemented prototypes reach efficiencies among 57- 58 % /1/. The paper shows the necessity of further developments to be able to reach an efficiency of 75%. The developments include improvements in all components of the system like compressor, turbine, bearing and the increasing of the operating temperature.