General Electric initiated the development of a water-cooled gas turbine in the early 1960’s. The first laboratory model of a water-cooled rotor, 9.7 in. (24.7 cm) was successfully tested in 1973 at sustained firing temperatures of 2850 F (1556 C) and 16 atm pressure while maintaining bucket surface temperatures of 1000 F (583 C) or less. Maximum firing temperatures of 3500 F (1927 C) were also attained during this period. The Electric Power Research Institute (EPRI) funded initial preliminary design work which utilized the water-cooled turbine concept in a combined cycle starting in 1974. Development work to define and resolve potential barrier problems was also funded by EPRI in the original and subsequent follow-on contracts. The United States Energy Research and Development Administration (ERDA) awarded a contract to the General Electric Company in May 1976 to conduct a preliminary design study which incorporates the water-cooled gas turbine concept in a combined cycle plant. The design is based on a gas turbine firing temperature (gas temperature entering the first-stage buckets) of 2600 F (1427 C) utilizing a coal-derived low-Btu gas or coal-derived liquid. This paper presents the results of the ERDA Program. Particular emphasis is devoted to the description of the overall plant design and performance. Turbine subsystems of the water-cooled concept and the alternate cooling concepts considered are also presented in this paper. The operating features and characteristics of an advanced fixed-bed gasifier and associated gas cleanup systems are also discussed relative to the impact on the overall system design and performance.

The problems in water-cooled rotors have centered around the high pressuies generated in a closed circuit containing water by the high centrifugal field. The present program focusses on open circuit water cooling in which the water has been allowed to exit freely from the bucket tips. This eliminates the leaks and plugging of cooling channels that have been encountered before permits one to distribute the coolant uniformly around the bucket airfoil contour close to the surface. In this way the thermal gradients and thermal stresses on the airfoil can be held within safe limits. Using this approach a 9.7 in. (24.7 cm) diameter turbine wheel has been built and operated at inlet conditions of 2850 F (1560 C) and 16 atmosphere with tip speeds in excess of 1700 fps (518 m/sec) and with good aerodynamic efficiency. Recent developments in ceramic materials also indicate potential for use in stationary parts.

This paper presents an update on the status of the technology of the water-cooled gas turbine developed by the General Electric Company under contracts with EPRI, ERDA, and DOE. Particular emphasis is devoted to the design and development of water-cooled composite turbine nozzles and buckets, and a sectoral combustor designed for low-Btu coal-derived gas operation. The operating characteristics of a low-temperature coal gas chemical cleanup system which is to be added to the coal gasification facility are also discussed. Status of the materials and process developments in support of the designs are also presented, as are updates to the Phase I HTTT Program combined-cycle studies, which evaluate the commercial viability of integrated coal gasification and combined-cycle operation.

A continuing technology development program initiated by General Electric (GE) in the early 1960s and joined by the Electric Power Research Institute (EPRI) in 1974 is successfully resolving potential barrier problems in the development of water cooled turbines. Early work by GE Corporate Research and Development demonstrated the feasibility of closed circuit, pressurized water-cooling of stationary nozzles (vanes), and of open circuit, unpressurized water-cooling of rotating buckets (blades). A small-scale turbine was designed, fabricated, and operated at a gas temperature of 2850 F (1565 C) at 16 atm, with surface metal temperatures less than 1000 F (540 C). Early results from the EPRI sponsored Water-Cooled Gas Turbine Development Programs were presented at the 1978 Gas Turbine Conference (Report #ASME 78-GT-72). This paper reports more recent results, obtained between mid-1977 and mid-1978. Significant progress has been made in a number of areas: (a) water-cooled nozzle and bucket design and fabrication, (b) corrosion kinetics model verification and testing, (c) partially filled internal channel bucket heat transfer testing, and (d) stationary to rotating water transfer and collection testing. Results to date are encouraging with regard to the application of water-cooled turbine components to achieve improved reliability and fuels flexibility at increased turbine firing temperatures.

Development of water-cooled gas turbine technology was begun at General Electric in the early 1960’s, and by the early 1970’s, a small-scale turbine had been operated to temperatures of 2850 F and 16 atm, with metal temperature less than 1000 F. The Water-Cooled Turbine Development Program was begun in 1974, funded by the Electric Power Research Institute, to do preliminary design on a utility-size gas turbine using water cooling and to do basic technology development to address the problem areas. This paper presents the results of the program, including descriptions of the test hardware and data on phenomena, such as corrosion, erosion, heat transfer, and water collection. Cycle analysis results are presented for two potential combined cycle configurations: (a) one using low-Btu coal gas fuel, and (b) one using a heavy liquid fuel. Summary performance curves are given showing the effect of changes of pressure ratio and firing temperature. Methods of improving the baseline cycle and their effect on baseline performance which are judged most promising are also given on the performance curves. Turbine design features to achieve low component metal surface temperatures for increased fuels flexibility are given with particular emphasis to the first-stage nozzles and buckets. Fundamental development testing needs have been identified and programs have been put into place to bring the water-cooled turbine to a point where a full-size water-cooled turbine can be built. Descriptions of the development test facilities, task descriptions, test plans and /or test results are given for eight tasks.

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An experimental investigation was carried out at DOE NETL on the humid air combustion process using liquid fuel to determine the effects of humidity on pollutant emissions and flame stability. Tests were conducted at pressures of up to 100 psia (690 kPa), and a typical inlet air temperature of 860 °F (733 K). The emissions and RMS pressures were documented for a relatively wide range of flame temperature from 2440–3090 °F (1610 − 1970 K) with and without added humidity. The results show more than 90 percent reduction of NOx through 10 percent humidity addition to the compressed air compared with the dry case at the same flame temperature. The substantial reduction of NOx is due to a shift in the chemical mechanisms and cannot be explained by flame temperature reduction due to added moisture since the comparison was made for the same flame temperature.

An experimental investigation was carried out at DOE NETL on the humid air combustion process using liquid fuel to determine the effects of humidity on pollutant emissions and flame stability. Tests were conducted at pressures of up to 100 psia (690 kPa), and a typical inlet air temperature of 860°F (733 K). The emissions and RMS pressures were documented for a relatively wide range of flame temperature from 2440-3090°F (1610–1970 K) with and without added humidity. The results show more than 90% reduction of NOx through 10% humidity addition to the compressed air compared with the dry case at the same flame temperature. The substantial reduction of NOx is due to a shift in the chemical mechanisms and cannot be explained by flame temperature reduction due to added moisture since the comparison was made for the same flame temperature.