Ronald L. Bannister

A Combined Cycle Designed to Achieve Greater Than 60 Percent Efficiency

In cooperation with the US Department of Energy`s Morgantown Energy Technology Center, Westinghouse is working on Phase 2 of an 8-year Advanced Turbine Systems Program to develop the technologies required to provide a significant increase in natural gas-fired combined cycle power generation plant efficiency. In this paper, the technologies required to yield an energy conversion efficiency greater than the Advanced Turbine Systems Program target value of 60% are discussed. The goal of 60% efficiency is achievable through an improvement in operating process parameters for both the combustion turbine and steam turbine, raising the rotor inlet temperature to 2,600 F (1,427 C), incorporation of advanced cooling techniques in the combustion turbine expander, and utilization of other cycle enhancements obtainable through greater integration between the combustion turbine and steam turbine.

Final Report on the Development of a Hydrogen-Fueled Combustion Turbine Cycle for Power Generation

Through its New Energy and Industrial Technology Development Organization (NEDO) the Japanese government is sponsoring the World Energy Network (WE-NET) Program. WE-NET is a 28-year global effort to define and implement technologies needed for hydrogen-based energy systems. A critical part of this effort is the development of a hydrogen-fueled combustion turbine system to efficiently convert the chemical energy stored in hydrogen to electricity when hydrogen is combusted with pure oxygen. A Rankine cycle, with reheat and recuperation, was selected by Westinghouse as the general reference system. Variations of this cycle have been examined to identify a reference system having maximum development feasibility, while meeting the requirement of a minimum of 70, 9 percent low heating value (LHV) efficiency. The strategy applied by Westinghouse was to assess both a near-term and long-term Reference Plant. The near-term plant requires moderate development based on extrapolation of current steam and combustion turbine technology. In contrast, the long-term plant requires more extensive development for an additional high pressure reheat turbine, and is more complex than the near-term plant with closed-loop steam cooling and extractive feedwater heating. Trade-offs between efficiency benefits and development challenges of the near-term and long-term reference plant are identified. Results of this study can be applied to guide the future development activities of hydrogen-fueled combustion turbine systems.

Development of a Hydrogen-Fueled Combustion Turbine Cycle for Power Generation

Consideration of a hydrogen based economy is attractive because it allows energy to be transported and stored at high densities and then transformed into useful work in pollution-free turbine or fuel cell conversion systems. Through its New Energy and Industrial Technology Development Organization (NEDO) the Japanese government is sponsoring the World Energy Network (WE-NET) Program. The program is a 28-year global effort to define and implement technologies needed for a hydrogen-based energy system. A critical part of this effort is the development of a hydrogen-fueled combustion turbine system to efficiently convert the chemical energy stored in hydrogen to electricity when the hydrogen is combusted with pure oxygen. The full-scale demonstration will be a greenfield power plant located sea-side. Hydrogen will be delivered to the site as a cryogenic liquid, and its cryogenic energy will be used to power an air liquefaction unit to produce pure oxygen.To meet the NEDO plant thermal cycle requirement of a minimum of 70.9%, low heating value (LHV), a variety of possible cycle configurations and working fluids have been investigated. This paper reports on the selection of the best cycle (a Rankine cycle), and the two levels of technology needed to support a near-term plant and a long-term plant. The combustion of pure hydrogen with pure hydrogen with pure oxygen results only in steam, thereby allowing for a direct-fired Rankine steam cycle. A near-term plant would require only moderate development to support the design of an advanced high pressure steam turbine and an advanced intermediate pressure steam turbine.© 1997 ASME

Fuel Gas Cleanup Parameters in Air-Blown IGCC

Fuel gas cleanup processing significantly influences overall performance and cost of IGCC power generation. The raw fuel gas properties (heating value, sulfur content, alkali content, ammonia content, tar content, particulate content) and the fuel gas cleanup requirements (environmental and turbine protection) are key process parameters. Several IGCC power plant configurations and fuel gas cleanup technologies are being demonstrated or are under development. In this evaluation, air-blown, fluidized-bed gasification combined-cycle power plant thermal performance is estimated as a function of fuel type (coal and biomass fuels), extent of sulfur removal required, and the sulfur removal technique. Desulfurization in the fluid bed gasifier is combined with external hot fuel gas desulfurization, or, alternatively with conventional cold fuel gas desulfurization, The power plant simulations are built around the Siemens Westinghouse 501F combustion turbine in this evaluation.

Evolution of Westinghouse Heavy-Duty Power Generation and Industrial Combustion Turbines

This paper reviews the evolution of heavy-duty power generation and industrial combustion turbines in the United States from a Westinghouse Electric Corporation perspective. Westinghouse combustion turbine genealogy began in March of 1943 when the first wholly American designed and manufactured jet engine went on test in Philadelphia, and continues today in Orlando, Florida, with the 230 MW, 501G combustion turbine. In this paper, advances in thermodynamics, materials, cooling, and unit size will be described. Many basic design features such as two-bearing rotor, cold-end drive, can-annular internal combustors, CURVIC{sup 2} clutched turbine disks, and tangential exhaust struts have endured successfully for over 40 years. Progress in turbine technology includes the clean coal technology and advanced turbine systems initiatives of the US Department of Energy.

Experimental studies of air extraction for cooling and/or gasification in gas turbine applications

This paper describes an experimental study on how the flow field inside the dump diffuser of an industrial gas turbine is affected by air extraction through a single port on the shell around the dump diffuser. A subscale, 360 deg model of the diffuser-combustor section of an advanced developmental industrial gas turbine was used in this study. The experiments were performed under cold flow conditions, which can be scaled to actual machine operation. Three different conditions were experimentally studied: 0, 5, and 20 percent air extraction. It was found that air extraction, especially extraction at the 20 percent rate, introduced flow asymmetry inside the dump diffuser and, in some locations, increased the local flow recirculations. This indicated that when air was extracted through a single port on the shell, the performance of the dump diffuser was adversely affected with an approximate 7.6 percent increase of the total pressure loss, and the air flow into the combustors did not remain uniform. The global flow distribution was shown to be approximately 35 percent nonuniform diametrically across the dump diffuser. Although a specific geometry was selected, the results provide sufficient generality for improving understanding of the complex flow behavior in the reverse flow diffuser-combustor sections of gas turbines under the influence of various air extractions.

Cold Flow Experiments in a Sub-Scale Model of the Diffuser-Combustor Section of an Industrial Gas Turbine

This paper describes the experimental facility and flow measurements in a sub-scale, 360-degree model of the diffuser-combustor section of an advanced developmental industrial gas turbine. The experiments were performed under cold flow conditions which can be scaled to actual machine operation through the use of a conventional flow parameter. Wall pressure measurements were used to calculate the static pressure recovery in the annular pre-diffuser. A five-hole probe was used to measure the complex three-dimensional flow in the dump diffuser. Mass-weighted average total pressures were calculated to examine the loss characteristics of the annular and the dump diffuser. The “sink” effect caused by the combustors induces a nonuniform velocity profile and pressure distribution at the exit of the annular pre-diffuser, thereby reducing the effectiveness of the annular pre-diffuser. The outer region of the dump diffuser effectively diffuses the flow while recirculation in other areas of the dump diffuser lowers diffuser effectiveness. Partially nonuniform flow distribution was observed at the entrance to the annular passage between the combustors and the combustor housing (top hat). The existence of circumferential flow in this annular passage tends to increase air flow uniformity into the combustor. Although a specific geometry was selected for the present study, the results provide sufficient generality for improving understanding of the complex flow behaviors in the reverse flow diffuser-combustor sections of industrial gas turbines.Copyright

EVALUATION OF THERMOCHEMICAL RECUPERATION AND PARTIAL OXIDATION CONCEPTS FOR NATURAL GAS-FIRED ADVANCED TURBINE SYSTEMS

An investigation into the potential benefits of thermochemical recuperation and partial oxidation in advanced natural gas-fired turbine systems is being carried out by a team consisting of the Westinghouse Electric Corporation and the Institute of Gas Technology under contract to the U.S. Department of Energy and the Gas Research Institute. The purpose of this study is to determine whether the application of thermochemical recuperation and/or partial oxidation technologies to advanced natural gas-fired power generation systems provides performance and/or cost benefits. This paper presents an overview of the concepts and technologies which are under investigation, as well as several of the thermodynamic cycles which are being developed to determine their viability.Copyright

Use of Thermochemical Recuperation in Combustion Turbine Power Systems

The performance and practicality of heavy duty combustion turbine power systems incorporating thermochemical recuperation (TCR) of natural gas has been estimated to assess the potential merits of this technology. Process models of TCR combustion turbine power systems based on the Westinghouse 501F combustion turbine were developed to conduct the performance evaluation. Two TCR schemes were assessed — Steam-TCR and Flue Gas-TCR. Compared to conventional combustion turbine power cycles, the TCR power cycles show the potential for significant plant heat rate improvements, but their practicality is an issue. Significant development remains to verify and commercialize TCR for combustion turbine power systems.© 1997 ASME

A Direct Coal-Fired Combustion Turbine Power System Based on Slagging Gasification With In-Situ Gas Cleaning

Westinghouse began the development of a compact, entrained, slagging gasifier technology utilizing in-situ fuel gas cleaning for combustion turbine power cycles in 1986. The slagging gasifier is air-blown, and produces a hot, low-heating value fuel gas that can be combusted and quenched to combustion turbine inlet temperatures while maintaining low levels of NO x emissions. The U.S. Department of Energy sponsored engineering studies and pilot testing during the period 1986 to 1992. This work has shown that the technology has promise, although performance improvements are required in some key areas. A major challenge has been the development of in-situ removal of sulfur, alkali vapor, and particulate to low enough levels to permit its use in combustion turbine power systems without additional, external gas cleaning. This paper reviews the Westinghouse slagging gasifier, direct coal-fired turbine power generation concept; the pilot test results; and the current development activities that Westinghouse is engaged in.